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LBNL-47002

EARTH SCIENCES DIVISION ANNUAL REPORT 1999 - 2000

UNIVERSITY OF CALIFORNIA B E R K E L E Y, C A L I F O R N I A 9 4 7 2 0 Prepared for the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

LBNL EARTH SCIENCES DIVISION

ANNUAL REPORT 1999-2000

LBNL EARTH SCIENCES DIVISION

ANNUAL REPORT 1999-2000

TABLE

OF

CONTENTS

EARTH SCIENCES 2000: A PERSPECTIVE FROM THE DIVISION DIRECTOR

1

RESOURCE DEPARTMENTS

3

MICROBIAL ECOLOGY AND ENVIRONMENTAL ENGINEERING

5

GEOCHEMISTRY

9

GEOPHYSICS AND GEOMECHANICS

7

HYDROGEOLOGY AND RESERVOIR DYNAMICS

11

CENTER FOR ENVIRONMENTAL BIOTECHNOLOGY

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15

RESEARCH PROGRAMS FUNDAMENTAL AND EXPLORATORY RESEARCH

17

An Effective Continuum Model for Flow and Transport in Fractured Rock Christine Doughty and Kenzi Karasaki

19

International Symposium: "Dynamics of Fluids in Fractured Rocks: Concepts and Recent Advances" Boris Faybishenko and Sally M. Benson

Reactive Chemical Transport in Structured Porous Media: X-ray Microprobe and Micro-XANES Studies Tetsu K. Tokunaga, Stephen R. Sutton and Keith R. Olson Unsaturated Fast Flow in Fractured Rock: Transient Film Flow Tetsu K. Tokunaga, Jiamin Wan and Stephen R. Sutton

20 21 22

Surface Excess of Clay Colloids at Gas-Water Interfaces Jiamin Wan and Tetsu K. Tokunaga

23

Colloid Formation during Infiltration of Waste Tank Liquid into Hanford Sediments Jiamin Wan, Tetsu Tokunaga, Eduardo Saiz, Keith Olson and Srinivas Veerapaneni Fe3+ Sorption on Quartz Surfaces: The Beginnings of Precipitation Glenn A. Waychunas, Rebecca Reitmeyer, James A. Davis and Jennifer A. Coston

Measurement of Reaction Rates in Natural Fluid-Rock Systems Using Sr and U Isotopes Donald J. DePaolo Geochemistry and Isotope Constraints in Oil Hydrogeology B. Mack Kennedy, Tom Torgersen, Matthijs van Soest and David L. Shuster

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Table of Contents

FUNDAMENTAL AND EXPLORATORY RESEARCH (CONTINUED)

Development of GPR Techniques to Non-Invasively Measure Subsurface Water Content Susan Hubbard, Katherine Grote and Yoram Rubin

28

Computation of Seismic Waveforms in Complex Media: Carbon Dioxide Sequestration Imaging Valeri A. Korneev, Lane R. Johnson and Thomas V. McEvilly

29

Center for Computational Seismology (CCS) Thomas V. McEvilly, Ernest L. Majer and Lane R. Johnson

31

Compaction and Fracturing of Weakly-Cemented Granular Rocks Larry R. Myer, Seiji Nakagawa, and Brad A. Bessinger

33

Three-Dimensional Interpretation of Borehole-to-Surface Electromagnetic Data Hung-Wen Tseng, Ki Ha Lee and Alex Becker

30

San Andreas Fault Monitoring at Parkfield Thomas V. McEvilly, Richard Clymer, Robert Nadeau, John Peterson and Don Lippert

32

Resonance Inversion for Elastic Moduli of Anisotropic Rocks Seiji Nakagawa, Kurt T. Nihei and Larry R. Myer

34

Decomposition of Scattering and Intrinsic Attenuation in Rock with Heterogeneous Multiphase Fluids Kurt T. Nihei, Seiji Nakagawa, and Larry R. Myer

36

Formation and Stability of Methane Hydrates in Clay Interlayers Sung-Ho Park, Garrison Sposito, Rebecca Sutton and Jeffery A. Greathouse

37

NUCLEAR WASTE PROGRAM

39

Shear-Induced Conversion of Seismic Waves on a Fracture Seiji Nakagawa, Kurt T. Nihei and Larry R. Myer

35

Geology of Yucca Mountain at the Potential Repository Horizon Jennifer Hinds

41

Interpretation of Injection Tests in Fractured Porous Media Jerry P. Fairley

43

Moisture Dynamics in the Repository Footprint at Yucca Mountain Rohit Salve

42

Interpreting Test Data on Water Flow in a Fault Curtis M. Oldenburg and Rohit Salve

44

Seepage into Underground Cavities: Field Experiments Robert C. Trautz and Joseph S.Y. Wang

45

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NUCLEAR WASTE PROGRAM (CONTINUED)

Systematic Hydrological Characterization of the Topopah Spring Lower Lithophysal Unit Paul Cook, Barry Freifeld, Rohit Salve and Yvonne Tsang Modeling of Water Seepage into an Underground Opening Stefan Finsterle and Robert C. Trautz

46 47

Seepage Model for Performance Assessment Guomin Li and Chin-Fu Tsang

48

Analysis of Calcite Deposition and Infiltration-Percolation flux in Unsaturated Fractured Tuffs Tianfu Xu, Eric Sonnenthal and Gudmundur S. Bodvarsson

50

Characterizing Flow and Transport Processes at Yucca Mountain Yu-Shu Wu, Winnie Zhang and Gudmundur S. Bodvarsson

52

Analysis of Yucca Mountain Pore-Water Chemical Data Jianchun Liu, Eric Sonnenthal and Gudmundur S. Bodvarsson

49

Unsaturated Zone Process Model for Yucca Mountain, Nevada Gudmundur S. Bodvarsson

51

Modeling Flow and Transport in Unsaturated Fractured Porous Media Hui Hai Liu, Charles Haukwa, Rick Ahlers and Gudmundur S. Bodvarsson

53

Radioactive Transport Modeling George J. Moridis and Qinhong Hu

54

Measuring the Thermal-Hydrological Processes in the Drift Scale Test Yvonne Tsang, Barry Freifeld and Sumit Mukhopadhyay

56

Water Chemistry and Rock Permeability Changes Around Nuclear Waste Emplacement Tunnels Nicolas Spycher and Eric Sonnenthal

58

Development of Borehole GPR Techniques to Monitor Moisture Redistribution Kenneth H. Williams, John E. Peterson and Ernest L. Majer

55

Acoustic Emission Monitoring during the Drift Scale Test at Yucca Mountain, Nevada John E. Peterson Jr., Kenneth H. Williams and Ernest L. Majer

57

Mineral Precipitation in an Unsaturated Tuff Fracture – Permeability Effects Timothy J. Kneafsey

59

Thermal Loading Studies Using the Unsaturated Zone Model Charles Haukwa, Yu-Shu Wu and Gudmundur S. Bodvarsson Use of Natural Analogs in the U.S. Nuclear Waste Program Ardyth M. Simmons

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NUCLEAR WASTE PROGRAM (CONTINUED)

Simulating Infiltration Tests in the Box Canyon Unsaturated Fractured Basalt Andre J.A. Unger, Boris Faybishenko, Gudmundur S. Bodvarsson and Ardyth M. Simmons

62

ENERGY RESOURCES PROGRAM

63

Cross-Well Seismic Imaging in Three Dimensions Valeri A. Korneev

65

Single-Well Seismic Imaging Ernest L. Majer, Roland Gritto and Tom Daley

66

Natural Fracture Characterization Using Passive Seismic Wave Illumination Kurt T. Nihei, Larry R. Myer, Peter Goldstein and Kevin M. Mayeda

68

Fracture Quantification in Gas Reservoirs Ernest L. Majer, Tom Daley, Roland Gritto, Larry Myer, S. Nakagawa and Kurt Nihei

67

Imaging, Modeling, Measurement and Scaling of Multiphase Flow Processes Liviu Tomutsa and Asoke De

69

Frequency-Dependent Seismic Attributes of Poorly Consolidated Sands Kurt T. Nihei, Seiji Nakagawa, Zhuping Liu, Liviu Tomutsa, Jil T. Geller, Larry R. Myer and James W. Rector

70

High Speed 3-D Hybrid Elastic Seismic Modeling Valeri A. Korneev and G. Michael Hoversten

71

Control of Fluid Injection into a Low-Permeability Rock Tad W. Patzek and Dmitriy B. Silin

73

EOSHYDR2: A TOUGH2 Module for the Simulation of CH4-Hydrate Systems in the Subsurface George J. Moridis, John A. Apps, Karsten Pruess and Larry R. Myer

75

Integrated Reservoir Monitoring using Seismic and Cross-well Electromagnetics G. Michael Hoversten

72

Dynamic Reservoir Characterization through the Use of Surface Deformation Data Don Vasco and Kenzi Karasaki

74

TOUGH2, Version 2.0 Karsten Pruess, Curt Oldenburg and George Moridis

76

Modeling of the Interaction of Hydrothermal Fluids with Rocks Tianfu Xu and Karsten Pruess

78

Geothermal Fields Seen as Dynamic Systems Marcelo Lippmann and Alfred Truesdell

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Table of Contents

ENERGY RESOURCES PROGRAM (CONTINUED)

Plume Separation by Transient Thermohaline Convection in Porous Media Curtis M. Oldenburg and Karsten Pruess

79

Tracing Injectate Returns to Geothermal Reservoirs B. Mack Kennedy and David L. Shuster

81

Phase-Partitioning Tracers in Fractured Geothermal Reservoirs Karsten Pruess, Michael O’Sullivan and B. Mack Kennedy

80

Heat and Helium in Geothermal Systems B. Mack Kennedy, Tobias P. Fischer and David L. Shuster

82

Wideband Downhole Time-Domain EM Transmitter Alex Becker, Ki Ha Lee and Lou Reginato

84

High Resolution Reservoir Characterization using Seismic, Well and Dynamic Data Don Vasco, Henk Keers, Lane Johnson and Akhil Datta-Gupta

86

ENVIRONMENTAL REMEDIATION TECHNOLOGY PROGRAM

87

Co-Metabolic Biological Reactions for the Treatment of MTBE-Contaminated Groundwater William T. Stringfellow

90

Estimating Fracture Closure under Hydrothermal Conditions Peter Persoff

83

Three-Dimensional Imaging of Geothermal Reservoirs Using Active and Passive Methods Ernest L. Majer, Roland Gritto, Tom Daley, Ann Kirkpatrick and John Peterson

Bioremediation, Education, Science and Technology (BEST): A Continued Partnership Terry Hazen

85

89

Aerobic Landfill Bioremediation Terry C. Hazen, Curtis M. Oldenburg, Sharon E. Borglin and Peter T. Zawislanski

91

Biotransformation of Metal Contaminants in Soils/Sediments: Chromium Tetsu Tokunaga, Jiamin Wan, Egbert Schwartz, Dominique Joyner, Stephen Sutton, Matt Newville, Mary Firestone and Terry Hazen

93

Development of Methods for Extracting DNA from Bacterial Spores Tamas Torok, Jennie C. Hunter-Cevera and Terrance Leighton

92

Kesterson Reservoir Ecological Risk Assessment Peter T. Zawislanski, Sally M. Benson, Tetsu K. Tokunaga and Keith R. Olson

94

Subsurface Imaging for Characterizing Heterogeneity Affecting Microbial Transport Properties in Sediments 95 Ernest L. Majer, Susan Hubbard, Ken Williams, John Peterson and Jinsong Chen

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Table of Contents

ENVIRONMENTAL REMEDIATION TECHNOLOGY PROGRAM (CONTINUED) Carbon Isotope Monitoring of Bioremediation of Chlorinated Solvents Mark E. Conrad, Donald L. Song and Lisa Alvarez-Cohen

96

Stable Isotopic Studies at the TAN Site of INEEL, Central Idaho Mark Conrad and Donald DePaolo

97

Chaotic Models of Dripping Water From a Fracture Under Ponded Infiltration at Hell's Half Acre, Idaho Boris Faybishenko

99

Contaminant Transport in a Sandy Aquifer with Discontinuous Clay Layers Curtis M. Oldenburg, Jennifer Hinds and Preston D. Jordan

101

Preferential Flow in a Contaminated Vadose Zone Christine Doughty, Curtis M. Oldenburg and Peter T. Zawislanski

98

High-Frequency Electromagnetic Measurements for Environmental Applications Ki Ha Lee, Alex Becker and William Frangos

100

Fast Flow in Unsaturated Coarse Sediments Tetsu K. Tokunaga, Jiamin Wan and Keith Olson

102

CLIMATE VARIABILITY AND CARBON MANAGEMENT PROGRAM

103

The California Water Resources Research and Applications Center Norman L. Miller, Jinwon Kim, William E. Dietrich and Phaedon C. Kyriakidis

106

Uncertainty in Regional Climate Precipitation Forecasts Applied to Streamflow Phaedon C. Kyriakidis, Jinwon Kim and Norman L. Miller

108

Satellite Retrievals of Surface Solar Irradiance James K.B. Bishop

105

Impacts of 2xCO2 Climate on the Southwestern U.S. Climate Jinwon Kim and Norman L. Miller

107

Modeling Water Resource and Environmental Impacts due to Climate Variability in the San Joaquin Basin Nigel W.T. Quinn, Norman L. Miller, John Dracup, Jinwon Kim and Richard Howitt

109

Seasonal Climate Hindcast and Prediction for the Western United States Using the Regional Climate System Model Jinwon Kim and Norman L. Miller

110

Applications of Remotely-Sensed Data for Seasonal Climate Prediction in East Asia and the Southwest United States Jinwon Kim, Norman L. Miller, Roger C. Bales and Linda O. Mearns

112

Simulation of Mean Monthly Precipitation and Streamflow in an East Asia Watershed Norman L. Miller and Jinwon Kim

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CLIMATE VARIABILITY AND CARBON MANAGEMENT PROGRAM (CONTINUED) The Impact of Global Change on Carbon Cycling in a California Grassland Margaret Torn, M. Rebecca Shaw and Simon Davis DOE Center for Research on Ocean Carbon Sequestration James K.B. Bishop Development of Robotic Ocean Carbon Observers James K.B. Bishop and Christopher K. Guay

113 114 115

Geologic Sequestration of Carbon Dioxide Sally M. Benson, Curt Oldenburg, G. Michael Hoversten and Larry R. Myer CO2 Injection for Carbon Sequestration and Enhanced Gas Recovery Curt M. Oldenburg, Karsten Pruess and Sally M. Benson

116 117

EARTH SCIENCES DIVISION PUBLICATIONS 1999-2000

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EARTH SCIENCES DIVISION STAFF 1999-2000

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LBNL EARTH SCIENCES DIVISION

ANNUAL REPORT 1999-2000

EARTH SCIENCES 2000: A PERSPECTIVE FROM THE DIVISION DIRECTOR

Sally M. Benson 510/486-5875 smbenson@lbl.gov

G

rowing populations and industrialization continue to demand more of our earth’s resources. Not surprisingly, the importance of the earth and ecosystem sciences in shaping our future grows larger than ever. Not only must earth scientists continue to address the issues that were so pressing during the past century—secure and economic energy and water resources, ground water and surface water pollution and natural hazards—we must face the challenges of the coming century. Growing concentrations of greenhouse gases in the atmosphere and the need for safe and secure nuclear waste management have emerged at the forefront of the concerns faced by our nation and others around the world. As one of the U.S. Department of Energy’s national laboratories, our mission is to provide a robust scientific foundation to better understand and identify solutions to these pressing issues. Our long-standing scientific strengths and fundamental research in hydrogeology and reservoir engineering, geophysics and geomechanics, geochemistry, and microbial ecology and environmental engineering provide the foundation for all of our programs. Building on this scientific foundation, we perform applied research and development to address important issues in support of the Department of Energy’s programs in a number of areas, namely: • Nuclear Waste Management—theoretical, experimental and simulation studies of the unsaturated zone at Yucca Mountain, Nevada. • Energy Resources—collaborative projects with industry to develop or improve technologies for exploration and production technology of oil, gas and geothermal reservoirs. • Environmental Remediation Technology—innovative technologies for containing and remediating metals, radionuclides, chlorinated solvents and energy-related contaminants. • Climate Change and Carbon Mangement—regional and global climate modeling; carbon cycling; geologic, terrestrial and ocean sequestration of carbon dioxide. Our new research programs in geologic sequestration of carbon dioxide, carbon cycling in the oceans and terrestrial biosphere, regional climate modeling and methane hydrates are the cornerstones of a major new research thrust related to understanding and mitigating the effects of growing greenhouse gas concentrations in the atmosphere. The global nature of this issue and the difficult choices that need to be made will present society with an unprecedented challenge. A rock solid scientific foundation will be needed to guide societal decisions and build the confidence needed to move us forward on the path to a sustainable future.

This year has been an exciting one. We have launched several new initiatives to prepare ourselves for the future, and we have made great strides in our ongoing research programs. In this report we present examples of our research projects. While it is not a complete accounting, it is representative of the nature and breadth of our research effort. We hope that you will be as excited about our research as we are.

ORGANIZATION OF THIS REPORT

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This report is divided into five sections that correspond to the major research programs in the Earth Sciences Division: • Fundamental and Exploratory Research • Nuclear Waste • Energy Resources • Environmental Remediation Technology • Climate Variability and Carbon Management These programs draw from each of our disciplinary departments: Microbial Ecology and Environmental Engineering, Geophysics and Geomechanics, Geochemistry, and Hydrogeology and Reservoir Dynamics. Short descriptions of these departments are provided as introductory material. A list of publications for the period June 1999 to June 2000, along with a listing of our personnel are appended to the end of this report. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

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Earth Sciences 2000

ACKNOWLEDGEMENTS

The Earth Sciences Division consists of 170 scientists, engineers, and technical and administrative staff. We gratefully acknowledge the support of our many sponsors in the Department of Energy. Our major sponsors at DOE include the Office of Science, Office of Fossil Energy, Office of Civilian Radioactive Waste Management and Office of Environmental Management. We also appreciate the support we receive from other federal agencies, including the U.S. Bureau of Reclamation, the U.S. Department of Defense and the U.S. Environmental Protection Agency. These activities support and enrich our programs by broadening the range of applications of our research. We also appreciate support from our industrial collaborators and colleagues, both financial and through partnerships that bring ideas, data and experience to our division.

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LBNL EARTH SCIENCES DIVISION

ANNUAL REPORT 1999-2000

RESOURCE DEPARTMENTS

Microbial Ecology and Environmental Engineering Geophysics and Geomechanics Geochemistry Hydrogeology and Reservoir Dynamics Center for Environmental Biotechnology

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Microbial Ecology and Environmental Engineering Department Terry Hazen

510/486-6223 tchazen@lbl.gov

shown that by using infrared analyses they can detect the juxtaposition of bacteria, toxic metals and solvents on basalt rocks from DOE waste sites. Indeed, they have shown that naturally occurring bacteria can detoxify Cr6+ to Cr3+, which is very stable. This promises to be a rapidly developing area for basic research in bioremediation and risk assessment.

ECOSYSTEM ENGINEERING

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The Microbial Ecology and Environmental Engineering Department has researched selenium transport in California’s Grassland Water District for many years. Recent research has focused on better methods for compliance monitoring and management. The U.S. Bureau of Reclamation has sponsored this work in an effort to better manage selenium loading in the San Luis Drain. Microbial studies have shown that selenium in-transit losses occur and that the fate of this selenium is bed sediments. Manipulation of the microbial ecology of the drain may stimulate the bioremediation of selenium from the water, thereby reducing the mass loading of selenium to the San Joaquin River.

he current expertise of the Microbial Ecology and Environmental Engineering Department (MEEED) is focused on bioremediation, ecosystem engineering, microbial ecology, biogeochemistry and environmental risk assessment. Department scientists support research in the Environmental Remediation Technology Program, Center for Environmental Biotechnology, Energy Resources Program, Nuclear Waste Program and the Climate Change and Carbon Management Program, all in the Earth Sciences Division.

BIOREMEDIATION

MEEED staff are internationally known for their research in bioremediation. This work has included in-situ, ex-situ and end-of-pipe treatments and natural attenuation (intrinsic bioremediation). The department has published papers on bioremediation of chlorinated solvents, polycyclic aromatic hydrocarbons, poly-chlorinated biphenyls, fuels, BTEX, MTBE, actinides, selenium, uranium and chromium. In addition to Department of Energy and Department of Defense waste sites, MEEED researchers have also studied municipal landfills, agricultural drainage areas, sewage treatment systems, groundwater treatment systems, pulp mills, oil refineries, oil production areas, explosives-contaminated soil, nuclear waste storage areas, solvent-contaminated sites, canneries, creosote treatment areas and nitrogen fertilizer factories. Researchers have several patents on bioremediation technologies, many of which have been licensed and are being used at sites around the world. A fascinating new area has developed over the last two years using the unique capabilities at Berkeley Lab’s Advanced Light Source (ALS). MEEED staff have

MICROBIAL ECOLOGY

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MEEED has considerable expertise in monitoring and characterizing microbes in all types of soil, groundwater, food, freshwater, marine, animal and human environments. Researchers have developed a large number of state-of-the-science techniques to detect and identify microorganisms in the environment using nucleic acid probes, polymerase chain reaction (PCR), phosphoHTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Microbial Ecology and Environmental Engineering

lipid fatty acids, fatty acid methyl esters, signature enzymes, fluorescent antibodies and direct fluorochrome staining. Department personnel have been actively characterizing microbes from the Chernobyl nuclear site and from Lake Baikal in Siberia. The department has also developed expertise using the Advanced Light Source to visualize individual microbes on mineral surfaces and identify their juxtaposition with minerals and organic compounds in situ.

ENVIRONMENTAL RISK ASSESSMENT

Using the ALS and various new techniques for enzyme assays, MEEED researchers have developed unique methods for a physiologically based protocol to estimate bioavailability and health hazards of petroleum products from soils to humans. This research is providing practical and realistic tools for evaluating various remedial technologies that cost-effectively protect humans—especially children—from exposure to residual petroleum hydrocarbons in surface soils of petroleum-contaminated sites.

Annual Report 1999 - 2000

FUNDING

MEEED research is funded by several DOE programs: (1) Office of Science, Office of Biological and Environmental Research; (2) Office of Environmental Management, Offices of Science and Technology and Environmental Restoration; (3) Office of Fossil Energy, Office of Gas and Petroleum Technologies; and (4) Office of Non-Proliferation and National Security, Office of Research and Development. Support is also received from the Department of Defense, U.S. Army Corps of Engineers; Department of the Interior, Bureau of Land Management; and from the State of California, Department of Water Resources and Department of the Interior, Bureau of Reclamation under the CALFED program. Finally, funding is received through LBNL’s Laboratory Directed Research and Develpment Program.

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Earth Sciences Division Berkeley Lab

Geophysics and Geomechanics Department Ernie L. Majer 510/486-6709 elmajer@lbl.gov

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he Geophysics and Geomechanics Department performs a wide variety of work ranging from fundamental to applied research.

properties of the subsurface, but for estimating the dynamic properties as well. We plan to accomplish this through an integrated effort of theoretical, laboratory and field programs. A specific thrust will be in the joint use of seismic and electrical methods for subsurface imaging. We have found that to address complex issues such as site remediation, flow and transport in fracture systems, vadose zone transport, CO2 sequestration, and reservoir stimulation and definition we must use an integrated approach to geophysics and geomechanics.

SCIENTIFIC THRUSTS

The department is organized into three different groups: Center for Computational and Applied Seismology Electrical and Potential Methods Rock and Soil Physics These groups work closely together to address issues in subsurface imaging. The scientific thrusts have been in joint inversion, wave propagation in complex media (seismic and electromagnetic), coupled-process definition and heterogeneity definition. Much of the work focuses on developing and applying high-resolution geophysical methods to derive physical, chemical and biological properties affecting flow and transport in heterogeneous media. A prime example is the work funded by the Department of Energy’s Natural and Accelerated Bioremediation Research (NABIR) program for the bacterial injection work. Another primary thrust is using geophysical methods for fracture quantification. This is evident in fundamental to very applied studies for DOE’s Fossil Energy, Environmental Restoration, Nuclear Waste and Geothermal programs. The Geophysics and Geomechanics Department is unique within the national laboratory and academic communities in having equally strong theoretical, modeling, lab, field/data acquisition and processing/interpretation capabilities. The department also works very closely with industrial partners in oil and gas and geothermal applications. This both strengthens the applied work and provides feedback into the fundamental studies. • • •

FUNDING

The work of the Geophysics and Geomechanics Department is derived from a variety of U.S. Department of Energy and Workfor-Others sources. The primary funding is received from DOE’s Office of Science (Basic Energy Sciences/Chemical Sciences and Office of Biological and Environmental Research), Fossil Energy, Geothermal Technology, Environmental Remediation and Nuclear Waste Isolation. Other funding sources include the U.S. Environmental Protection Agency, U.S. Air Force Office of Scientific Research and the U.S. Geological Survey’s Earthquake Hazard Reduction Program. Support has also been received from a variety of oil and service companies, including Chevron, Conoco, Texaco, Exxon, Schlumberger and Shell Oil.

INTEGRATED APPROACH TO FUTURE WORK

The future thrusts of the department are to continue to develop, test and apply high-resolution geophysical methods for not only characterizing static 7

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Geochemistry Department Donald J. De Paolo

510/643-5064 depaolo@socrates.berkeley.edu

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ISOTOPE GEOCHEMISTRY

he Geochemistry Department combines expertise in chemical and isotopic analysis, molecular environmental science, mineralogy and multiscale data-gathering methodology to enable geochemical characterization of earth systems from the macroscopic to the molecular. The department comprises four groups with complementary interests and capabilities.

AQUEOUS GEOCHEMISTRY

Studies in this group address issues of contaminant sequestration and migration in the environment, mineral-fluid reactions, and various aspects of aqueous solutions. Recent work includes characterization of the selenium speciation, transport and reaction rates within soil horizons at the Kesterson Reservoir, a site where national attention is focused as a result of selenium poisoning of wildlife related to agricultural runoff. Related investigations examine arsenic transport and redox reactions in soils, and microbial effects on the speciation of selenium in hydrologic systems. The important but overlooked effects of the vadose zone air-water interface on the transport of colloids has been identified and quantified by department scientists. Fundamental studies on the nature of the aqueous solution/mineral interface and on the structure of near-aqueous solvated ions and colloids are also being performed. The aim of these studies is to provide improved modeling capability for contaminant migration, weathering, sediment transfer, ion exchange and nutrient cycles. Current work includes: molecular dynamics modeling of the interlayer solvated cations in clays; studies of the solvation environment of contaminant and nutrient molecules in aqueous solution; determination of the molecular identity of initial iron oxide precipitates on quartz surfaces; and characterization of environmentally important minerals via simulation, x-ray scattering and x-ray spectroscopy methods. Many of these efforts involve newly developed capabilities utilizing synchrotron x-ray sources. Important new work on the aqueous behavior of humic and fulvic acids, hydroxyl speciation near cations in water, and the nature of organic contaminants on mineral surfaces has been carried out recently at Berkeley Lab’s Advanced Light Source.

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The Isotope Geochemistry group operates the Center for Isotope Geochemistry, which includes six analytical facilities: stable isotope and noble gas isotope laboratories; a soil carbon laboratory; an analytical chemistry laboratory; the Inductively Coupled Plasma Multi-Collector Magnetic Sector mass spectrometry laboratory, and a thermal ionization mass spectrometry laboratory located on the UC Berkeley campus. We also have an affiliation with the cosmogenic isotope laboratory in UC Berkeley’s Space Sciences Laboratory. These facilities provide state-of-theart characterization of all types of earth materials for research throughout the department and elsewhere in the division. Further, they support the Center's goals of (1) finding new ways to utilize isotopic ratio methods to study earth processes, and (2) applying isotopic and chemical analysis procedures to environmental and energy problems of national interest. Current research programs include: (1) development of models that use isotopic composition data from element pairs in fluids to constrain fluid flow rates, water-mineral reaction rates and the geometry and spacing of fractures in rock matrices; (2) development and application of noble gas isotopes as natural tracers for injectate return in geothermal reservoirs and as natural tracers for fluid source and movement in hydrocarbon and geothermal systems; (3) geochemical monitoring and analysis HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Annual Report 1999 - 2000

Geochemistry Department

of large-scale experiments simulating the effects of nuclear waste heat generation within the nuclear repository in Yucca Mountain, Nevada; (4) application of helium and neodymium isotopes to determine magma chamber recharge rates in areas having possible volcanic hazards or the potential for geothermal energy extraction; (5) development of C, N and O isotope techniques for quantifying in situ bio-remediation and environmental restoration; and (6) use of carbon isotopes to quantify rates of organic carbon cycling and storage efficiency in soils, the impact of climate change on carbon cycling, and linkages between carbon, water and nitrogen cycles.

• •

ATMOSPHERE AND OCEANS

The focus of this group is on the characterization of conditions and chemical components in the oceans and atmosphere, and the development of process models using these inputs combined with other hydrospheric data to explain and predict climatic change. The group operates the Regional Climate Center (RCC), where large-scale simulations using the Regional Climate System Model (RCSM) are used for weather forecasts, climate prediction and basic research. Ongoing collaborations include: streamflow simulations with the U.S. Geological Survey; runoff contaminant monitoring and management with the U.S. Bureau of Reclamation; development of landslide hazard prediction models with UC Berkeley; development of snow cover and snow water equivalent maps for California with UC Santa Barbara; and development of a shared information distribution system with DOE’s Accelerated Climate Prediction Initiative (DOE/ACPI) collaborators. Researchers are currently working with the National Energy Research and Scientific Computing Center (NERSC) at LBNL to develop a new high-performance version of the RCSM. DOE has also recently funded LBNL as co-host (with Lawrence Livermore National Laboratory) for the development of a new center for global climate change. The Center for Research on Ocean Carbon Sequestration is headed at LBNL by ESD’s Jim Bishop. Collaborators include Massachusetts Institute of Technology, Rutgers University, Scripps Institute of Oceanography, Moss Landing Marine Laboratories and Pacific International Center for High Technology Research. At Lawrence Livermore the leader is Ken Caldeira. The goal of the center is to research the feasibility, effectiveness and environmental acceptability of ocean carbon sequestration.

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Current projects include: Simulation and analysis of an ongoing largescale underground thermal test. Prediction of the coupled thermal-hydrological-chemical processes around potential waste emplacement tunnels and concomitant changes in water and gas chemistry, mineralogy and flow. Analysis of geochemical data from Yucca Mountain to constrain models of flow and transport in the unsaturated zone. Development of models for reactive-transport in unsaturated systems and improvements in the reactive-transport code TOUGHREACT. Study of natural analogue sites, including analysis of continuously cored intervals from the Yellowstone geothermal system to assess effects of mineral alteration on fracture and matrix permeability. Simulation and analysis of lab experiments of boiling in fractured tuff. Modeling of CO2 sequestration. Evaluation of solvent extraction using roomtemperature ionic liquids to strip and recover hazardous organic contaminants dissolved in ground and surface waters.

FUNDING

Funding for the Geochemistry Department comes from a variety of sources, including: the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Geosciences programs; Office of Environmental Management, Office of Science and Technology; Office of Energy Efficiency and Renewable Energy, Office of Utility Technologies, Office of Geothermal Technologies; Office of Civilian Radioactive Waste Management; U.S. Environmental Protection Agency; U.S. Navy; National Aeronautics and Space Administration, Office of Space Science and NASA Earth Enterprise; National Science Foundation, Office of Polar Programs; the University of California Campus-Laboratory Collaboration Hydrology Project; and the Laboratory-Directed Research and Development program at LBNL.

GEOCHEMICAL TRANSPORT

A major effort of this group is the simulation and study of coupled mineral-water-gas reactive transport in unsaturated porous media—particularly in fractured rock under boiling conditions. This work has focused predominantly on the prediction of thermally-driven processes accompanying the potential emplacement of high-level nuclear waste at Yucca Mountain, Nevada, and on the understanding of the evolution of the natural hydrogeochemical system. Divisional collaboration brings together essential pieces, including hydrological processes in the unsaturated zone, thermodynamics and kinetics of geochemical processes, and isotopic effects. 10

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Earth Sciences Division Berkeley Lab

Hydrogeology and Reservoir Dynamics Department Chin-Fu Tsang 510/486-5782 cftsang@lbl.gov

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he Hydrogeology and Reservoir Dynamics (HRD) Department is one of the most active groups internationally doing research in various areas within the fields of hydrogeology and reservoir engineering. The areas include the following:

field experiments designed and conducted by LBNL at Yucca Mountain; the data were analyzed by advanced theoretical techniques and numerical models. During the past year, HRD has also become active in the study of physical and chemical processes involved in CO2 injection into brine aquifers and oil and gas fields.

CONTAMINANT HYDROLOGY

Work conducted in this area covers various theoretical and experimental studies, including a major evaluation of contamination at LBNL. In this multi-year evaluation, details of the hydrogeologic structure of the site were identified, measured and modeled, then the contamination plumes (which are relatively minor) were characterized, monitored and studied. Finally, a control and remediation strategy is being developed. The work involves a multi-disciplinary effort of geologists, hydrologists, geophysicists and hydrogeochemists, which is characteristic of many of HRD’s research projects. Other efforts in this area include understanding tracer transport in heterogeneous media, developing advanced numerical models for transport studies and advancing well test techniques and borehole measurement methods to identify and estimate formation parameter values. Another subject where HRD has considerable experience is the emplacement of in-situ gel barriers to contain the contaminant plume. The experience includes both the choice of gel materials and the optimization of emplacement strategy.

FRACTURE AND STOCHASTIC HYDROLOGY

UNSATURATED ZONE HYDROLOGY

The study of air, water and moisture flow and transport in unsaturated formations is a very active area of HRD’s research, with applications to problems of both nuclear waste disposal and environmental evaluation. HRD has been in the forefront in the study of flow-channeling effect in unsaturated-medium and chaotic-flow models. Stimulated by the need to understand flow and transport in the unsaturated zone at Yucca Mountain, Nevada, much progress has been made both in field measurements and theoretical/modeling methods. The former includes a number of advanced

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For more that two decades, HRD has been active in the field of fracture hydrology, being one of the first groups to develop a fracture network model and a channeling model of flow through variable-aperture fracture systems, and to apply the annealing modeling to fracture hydrology. Our work is characterized by close interaction between modeling and field data evaluation, with complementary laboratory studies. This work continues and has been further generalized to research into strongly heterogeneous media, including studies with the stochastic continuum and double-permeability models. Work in HRD demonstrated flow channeling phenomena in both 3-D saturated and unsaturated media. Furthermore, new field measurement techniques are being developed to measure strongly varying permeabilities in the borehole and along underground tunnels. The former includes the further advancement of the dynamic borehole fluid logging method HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Hydrogeology and Reservoir Dynamics Department

developed at LBNL some years ago. The latter includes the so-called systematic testing, which is a repeated set of experiments at regularly space distances along an underground tunnel to provide unbiased data for stochastic modeling.

Annual Report 1999 - 2000

the hydrofracturing process, using injection wells. Advanced and unconventional well-test methods to determine and characterize production zones have been developed. Pore network models are being developed to understand drainage and imbibition processes in reservoir rocks during flooding operations. An interesting application being studied is the diatomic fields, which represent potentially billions of barrels of high-quality oil. However, production from the diatomites requires a secondary recovery process because of their low permeability, even though they have high porosity. Research into hydrofracturing with flooding is being conducted to explore optimal production strategies.

FLOW AND TRANSPORT MODELING

HRD has a long history in numerical modeling of flow and transport in geologic media. A suite of numerical models using finite-difference, finite-element and integrated finite-difference methods has been developed. The most well-tested and applied computer code is the TOUGH family of simulators, which calculates flow and transport of multi-phase multi-component fluids in complex fracture-porous media. Anumber of equation-of-state packages have been developed for different fluids appropriate for environmental, nuclear waste disposal, oil and gas and geothermal reservoir applications. Associated with these codes are the iTOUGH codes, which perform the inverse calculations of parameter estimation for such complex systems. Current development involves implementation of reactive chemistry into the TOUGH codes. This includes both homogeneous reactions, such as aqueous complexation and redox reactions, and heterogeneous reactions such as ion exchange, adsorption, mineral dissolution and precipitation, and gas dissolution and exsolution. The new code is called TOUGHREACT, which has already been applied to analyzing several sets of real field data with success. The coupling of mechanical stress and temperature effects of permeability of fractured rocks is important in injection testing, stimulation of oil and gas reservoirs and nuclear waste repository performance. HRD’s work involves the development of a coupled thermo-hydro-mechanical (THM) simulator for modeling of fully coupled HM processes in saturated and unsaturated media. Asecond effort has been the coupling of two powerful existing codes, TOUGH2 and the industry-standard code FLAC3D. The latter calculates mechanical and thermal-hydro-mechanical processes in soil and rock mechanics. The joining of these two codes gives us a new capability to address these coupled THM problems.

FUNDING

Funding for the Hydrogeology and Reservoir Dynamics Department comes primarily from the U.S. Department of Energy, including: Office of Science, Office of Basic Energy Science, Geosciences Research Program; Offices of Biological and Environmental Research; Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Geothermal Technologies; Office of Civilian Waste Management; and Assistant Secretary for Environmental Management. The department receives funding support also from the U.S. Environmental Protection Agency. Other funding is provided through the Laboratory Directed Research and Development program at LBNL.

RESERVOIR ENGINEERING

HRD is also very active in the study of oil and gas reservoirs. This includes optimization and control theory to maximize oil production with

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Earth Sciences Division Berkeley Lab

Center for Environmental Biotechnology Terry Hazen

510/486-6223 tchazen@lbl.gov

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he Center for Environmental Biotechnology (CEB) is a virtual center for integrated multi-disciplinary research in three main focus areas: biogeochemical transformations, environmental diagnostics and environmental health risk assessment based on bioavailability. The Center’s core staff members are from the Earth Sciences and Life Sciences divisions at Berkeley Lab. In addition, the Center has collaborating scientists from Environmental Energy Technologies, Engineering, Information and Computing Sciences, Accelerator and Fusion Research, Nuclear Physics, Materials Sciences and the Advanced Light Source. CEB’s responsibilities are to coordinate, integrate and provide multidisciplinary research teams to address specific environmental problems at Department of Energy and Department of Defense sites and within the State of California. CEB also manages the U.S. Army Core of Engineers' BEST (Bioremediation, Education, Science and Technology) Program and houses the Cal/EPA Bioremediation Validation and Certification Program.

and U at different scales in an effort to understand the forces that affect transport of these common contaminants at DOE sites. CEB, in cooperation with UC Berkeley, has been providing technical guidance and monitoring of a selenium and nitrate treatment system on agricultural land within the Panoche Water District for the past five years. Two side-by-side systems consisting of a shallow, high-rate algal pond, a deep reduction pond, a sedimentation unit and filter bed were constructed close to the tile sump draining a 1,000-acre field. Removal rates vary from 40 to 80% depending on the configuration of the system. Ongoing research is focused on increasing the removal efficiency and throughput of these systems under a variety of environmental conditions. The ultimate objective is to develop a low-cost, easy-to-implement technology to help farmers reduce selenium loads exported to the San Joaquin River and San Francisco Bay-Delta.

BIOGEOCHEMICAL TRANSFORMATIONS

Volatile organic compounds (VOCs) are the most common organic contaminants detected in polluted subsurface soil and fractured rock vadose zones. We are examining this microbial biodegradation in fractured rocks by investigating the use of intrinsic endolithic (rock-inhabiting) bacteria to transform VOCs, with respect to the range of critical environmental factors. In addition, stable isotopes are used to monitor the biotransformation processes. Aerobic co-metabolic processes are also being studied in the field for their ability to biodegrade recalcitrant organics. For example, chlorinated solvents and polycyclic aromatic hydrocarbons are being studied for their ability to bioremediate environments in situ to low ppb concentrations of contaminants. The center is extending this work also to landfills to facilitate rapid biodegradation of refuse and eliminate the production of green house gases and leachates that contaminate groundwater. This work has the potential to revolutionize the way we operate landfills. The center has still other projects looking at biotransformations of Cr

INFRARED MICROSPECTROSCOPY

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Pollution of subsurface geologic zones and the possibility of using the intrinsic endolithic (rock/mineral-inhabiting) bacteria to either detoxify or immobilize the pollutants have stimulated new interest in the exploration of endolithic bacteria and their long-term survival in the geologic environment. We have developed and demonstrated the applicability of surfaceHTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Center for Environmental Biotechnology

enhanced infrared absorption-reflection (SEIRA) microspectroscopy to study—quickly and with minimum sample preparation—in situ relationships between the microbial localization and the microscopic physiochemical structures of geologic materials such as rocks. Unlike traditional microscopy approaches, SEIRA microspectroscopy can provide to researchers simultaneously the biological, geochemical and physical characteristics of the intact environmental samples. This study has demonstrated that SEIRA microspectroscopy using a metal-overlayer is a promising tool for studying the in situ localization of bacteria within geologic materials.

Annual Report 1999 - 2000

present, biomass and physiological state.

ENVIRONMENTAL RISK ASSESSMENT

Assessing environmental risk based on bioavailability, i.e., what is actually being taken up by human, animal and plant cells, is a challenge for CEB. There is much data in the literature on high-dose exposure rates or single-dose, single-compound exposure rates to animals. CEB has taken the approach of examining the weathered material as it exists in nature and exposing human cell lines to this material over time. In many instances, our cell-line models consist of co-culturing two different types of cell lines on thin membranes. We are assessing the effects of ingested weathered PAH mixtures, organochlorines and dioxin by simulating the human digestion system. One team is examining the digestion of the material by human enzymes, uptake by intestinal cell lines (KACO2) and conversion by metabolic cell lines such as liver, kidney and breast cell lines. Using a combination of molecular biomarkers and the synchrotron, we can measure what material is left behind in the intestinal cell lines, what the compounds may be metabolized to, and any DNA damage and repair using specific molecular biomarker assays developed by our cell biologists.

BIODEGRADATION AND BIOCONVERSION OF FUELS

Another focus area in biogeochemical transformations is our work on the biodegradation of methyl tert-butyl ether (MTBE), an additive in gasoline that is a potential carcinogen. By designing a bioreactor that simulates the actual "process reactor," we have isolated indigenous microorganisms attached to the carbon material that have the capability of biodegrading. These microorganisms are currently being identified and optimized for use in an ex situ bioreactor. A pilot plant has been constructed in Southern California for treatability studies with Kinder Morgan Energy Partners, U.S. Filter/Envirex and North Carolina State University. In an extension of this work we are currently studying the ability of select microorganisms to biodegrade certain components found in crude oil, thus changing the viscosity or other properties. This work could result in new and greener technologies for petroleum refining.

ENVIRONMENTAL DIAGNOSTICS

CEB, in collaboration with the Earth Sciences Division’s Center for Isotope Geochemistry, has been employing stable isotope monitoring to validate bioremedial activities in field sites. The isotopic ratios of soil, gas and groundwater compounds are monitored to distinguish byproducts of biodegradation of petroleum hydrocarbons (e.g., CO2, CH4) from other potential sources. Furthermore, distinctive shifts in the isotopic compositions of the contaminants and metabolic byproducts have been used to differentiate between specific metabolic pathways used by the microorganisms to degrade the contaminants. More recently, we have concentrated on using isotopic measurements to detect in situ biodegradation of more recalcitrant contaminants, such as chlorinated solvents and gasoline oxygenates. CEB has also been studying methods for DNA extraction form anthrax spores. This work, funded by the FBI, is helping the agency find the best methods to extract DNA from spores found in environmental samples to determine if anthrax is present. We are also adapting phospholipid fatty acid analyses to studies of a wide variety of environmental samples. These membrane components found in all cells can be extracted directly from environmental samples and provide indications of the organisms

PARTNERS AND FUNDING

CEB research is funded by the U.S. Department of Energy, Department of Defense and Federal Bureau of Investigation. Industrial collaborators are Kinder Morgan and Geokinetics and the Petroleum Environmental Research Forum. Academic partners include the University of California at Davis, California Polytechnic Institute, University of Utah and the BEST Program partners: Jackson State University, Ana G. Mendez University System, Southern University of Mississippi, University of Texas at El Paso and University of California at Berkeley.

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LBNL EARTH SCIENCES DIVISION

ANNUAL REPORT 1999-2000

RESEARCH PROGRAMS Fundamental and Exploratory Research Nuclear Waste Energy Resources Environmental Remediation Technology Climate Variability and Carbon Management

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Annual Report 1999 - 2000

Earth Sciences Division Berkeley Lab

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Earth Sciences Division Berkeley Lab

Fundamental and Exploratory Research Program Sally M. Benson 520/486-5875 smbenson@lbl.gov

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he Fundamental and Exploratory Research Program (FERP) covers fundamental earth sciences research conducted in support of the Department of Energy’s science mission, which includes research in the natural sciences to provide a basis for new and improved energy technologies and for understanding and mitigating the environmental impacts of energy development and use. This part of the Earth Sciences Division’s program also includes exploratory research in important new energy and environmental topics conducted under the Laboratory Directed Research and Development (LDRD) program. The scientific insights and break-throughs achieved in FERP often become the underpinnings for projects that support DOE’s applied research and development program offices. Over the years, the basic earth sciences research program at Berkeley Lab has focused on three broad earth sciences problems, described below. • Fundamental studies of chemical and mass transport in geologic media with special reference to predictive modeling of multiphase, multi-component, non-isothermal fluid flow in saturated and unsaturated fractured rocks. • The development of new isotopic techniques for understanding the nature of a broad range of global processes—from the relatively shortterm effects of natural fluid migration in the crust to longer-term (i.e., 10–20 thousand years) global climate variations. • Fundamental studies in the propagation of waves through geologic media with emphasis on new computational techniques for analyzing seismic/acoustic and broadband electromagnetic signals for high-resolution imaging of near-surface structures, such as possible fracture flow paths, and for inferring the types of fluids present in pores and fractures. Results from these research endeavors have had major impacts on applied energy, environmental and radioactive waste management programs. Current research projects are briefly described here.

FLUID-CHEMICAL TRANSPORT INVESTIGATIONS

Laboratory experiments have revealed the nature of the complex processes of reactiondependent colloid generation and release, permeability changes, and flow-path alteration that strongly influence flow and chemical transport in the vadose zone beneath leaking tanks. In this study, we are mainly interested in understanding contaminant transport of the waste plume emanating from the leaking underground REDOX tanks at the Hanford Reservation, Wash. We organized and hosted an International Symposium entitled "Dynamic of Fluids in Fractured Rocks: Concepts and Recent Advances" to celebrate the 80th birthday of retired ESD researcher and UC Berkeley Professor Paul A. Witherspoon. Paul initiated some of the early investigations on flow and transport in fractured rocks, and was the initial director of the Earth Sciences Division, 19781983. The aim of the symposium was to bring together an international group of scientists from different earth sciences fields to exchange new ideas and approaches for research on fractured rock.

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Earth Sciences Division Berkeley Lab

Fundamental and Exploratory Research Program

ISOTOPE GEOCHEMISTRY

Annual Report 1999 - 2000

sis, to image and monitor gas present in manmade underground CO2 repositories.

The Center for Isotope Geochemistry (CIG) is a state-of-the-art analytical facility established in 1988 for the measurement of concentrations and isotopic compositions of elements in rocks, minerals, and fluids in the earth’s crust, atmosphere and oceans. Fundamental research conducted at this center is directed at finding new ways to use isotopic information to study earth processes such as long-term climate changes and to predict the chemical transport of mantle-derived or deep crustal fluids as they move through the crust. One of the major problems being studied at CIG is how to estimate fluid-solid reaction rates in natural groundwater higher temperature geothermal conditions, particularly as these rates affect mineral dissolution and secondary mineral precipitation. ESD researchers are developing novel ways of estimating reaction rates by using isotopic tracers (primarily Sr, but also U and Nd) to determine solid-fluid exchange rates in various natural situations. Scientists are able to derive the "reaction length," a parameter that depends on the ratio of isotope transport by diffusion and advection to the reaction rate. On the basis of these isotopic tracers in rock samples from the vadose zone at the Yucca Mountain, Nevada, test site, scientists have obtained constrained estimates of groundwater flow velocities, and information on mesoscale hydrogeology; i.e., fracture spacing.

ROCK PHYSICS

A variety of rock and soil science experiments are being conducted through the division’s Geoscience Measurements Facility, which supports both field and laboratory work. In one new laboratory project, researchers are studying the compaction and fracturing of weaklycemented granular rocks for the purpose of learning how to design stable boreholes under such conditions. In this research, we have performed a series of laboratory experiments to understand the effects of grain shape, cementation and the mechanical removal of debonded grains upon the failure mode of a weakly bonded medium. In another experiment, researchers have shown that mode conversion of seismic waves, both P and S, can be used to measure the magnitude and direction of a static shear stress acting on fractures in a rock.

ADVANCED COMPUTATION FOR EARTH IMAGING

FUNDING

The Center for Computational Seismology (CCS) was created in 1983 as the LBNL and UC Berkeley nucleus for seismic research related to data processing, advanced imaging and visualization. In recent years, a great deal of cross-fertilization between seismologists and other geophysicists and hydrogeologists has developed within the division, resulting in collaborations on a wide variety of fundamental imaging problems. An example of one such collaboration is a study to evaluate the feasibility of Ground Penetrating Radar (GPR) techniques to measure soil moisture content. A proof-of-principle test was successfully completed that showed that soil moisture may, in practice, be obtained from radar travel-times under controlled conditions. Another new imaging problem being studied involves the development and testing of a seismic mapping technique, involving full-waveform analy-

Funding for research in the Fundamental and Exploratory Research Program comes from a variety of sources, including primarily the U.S. Department of Energy’s Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences Research Program, and Office of Biological and Environmental Research, as well as the Laboratory Directed Research and Development Program at LBNL. Additional support comes from DOE’s Office of Environmental Management, Environmental Management Science Program.

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Earth Sciences Division Berkeley Lab

Fundamental and Exploratory Research Program

AN EFFECTIVE CONTINUUM MODEL FOR FLOW AND TRANSPORT Christine Doughty and Kenzi Karasaki

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Contact: Christine Doughty, 510/486-6453, cadoughty@lbl.gov

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FRACTURED ROCK

RESEARCH OBJECTIVES

The objective of this project is participate in the H-12 flow comparison, a multi-national project to investigate the uncertainties involved in the prediction of flow and transport behavior of a fractured rock mass.

APPROACH

Several international research organizations conducted numerical simulations with the same starting information regarding a fractured rock mass and the results were compared. Most organizations used discrete fracture network (DFN) models. Our approach to modeling flow and transport in a fractured rock mass is to construct a conceptual model by inverting field hydrologic test data such as the responses during flow tests and pressure interference tests. Unfortunately, our approach is largely incompatible with the specifications given for the H-12 flow comparison, which mostly consist of geometric data of fractures. Therefore, we interpreted the properties of the DFN data set as representing conditions observed in the field, and then used them to constrain the grid design and the parameters used in our equivalent continuum model (ECM). We used a stochastic permeability distribution to represent the fractured rock block and did not model individual fractures explicitly. In particular, we generated the stochastic permeability distributions based on an analysis of hydraulic conductivity data from pressure testing at the Kamaishi underground testing facility in Japan.

Figure 1. Example of streamlines depicting tracer transport. The black timing marks on each streamline are spaced 10 years apart. Note that the streamlines following the high-permeability feature at about x = 70 m show no timing marks, indicating a travel time of less than 10 years.

ACCOMPLISHMENTS

Our modeling approach differed markedly from most of the others, by using an effective continuum model rather than a discrete fracture network model. However, the results of all the models were shown to be reasonably consistent. It was found that the variability among different models was not much larger than the variability between realizations of a single model.

the design, execution and interpretation of the field tests.

RELATED PUBLICATION

Doughty, C., and K. Karasaki, Using an effective continuum model for flow and transport in fractured rock: The H-12 flow comparison, Berkeley Lab report LBNL-44966, 1999.

SIGNIFICANCE OF FINDINGS

The ECM approach is generally far more efficient than the DFN approach, and as such may be more useful for the larger scale of problems typically encountered in the field. There is not much uncertainty in the way different computer codes solve algebraic equations. A larger uncertainty lies in the development of the conceptual model. Another source of uncertainty that is tightly related to the development of the conceptual model can be in site characterization:

ACKNOWLEDGEMENTS

This work has been supported by Japan Nuclear Fuel Cycle Corporation (JNC) and JGC Corporation through the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

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Earth Sciences Division Berkeley Lab

"DYNAMICS

Fundamental and Exploratory Research Program

OF

FLUIDS

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INTERNATIONAL SYMPOSIUM FRACTURED ROCKS: CONCEPTS AND RECENT ADVANCES"

Boris Faybishenko and Sally M. Benson

Contact: Boris Faybishenko, 510/486-4852, bfayb@lbl.gov

An International Symposium on the Dynamics of Fluids in Fractured Rocks: Concepts and Recent Advances was held at Berkeley Lab Feb. 10–12, 1999. This symposium celebrated the 80th birthday of retired researcher and professor Paul A. Witherspoon, who initiated some of the early investigations on flow and transport in fractured rocks at UC Berkeley and Berkeley Lab. He has played a key role at these institutions in the development of research on basic concepts, modeling and investigations in the laboratory and field on fluid flow and contaminant transport in fractured rock systems. The aim of the symposium was to bring together an international group of scientists and engineers from different earth sciences fields to discuss these problems and exchange ideas on new approaches for research on fractured rocks. The technical problems of assessing fluid Paul A. Witherspoon flow, radionuclide transport, site characterization, modeling and performance assessment in fractured rocks remain the most challenging aspects of subsurface flow and transport investigations. An understanding of these important aspects of hydrogeology is needed to assess disposal of nuclear wastes, development of geothermal resources, production of oil and gas resources and remediation of contaminated sites. More than 100 papers from 12 countries were presented at the symposium to address recent scientific and practical developments and the status of our understanding of fluid flow and radionuclide transport in fractured rocks. More than 200 people participated, providing valuable information on different aspects of investigation of fractured rocks, including: • Theoretical studies of fluid flow in fractured rocks • Multi-phase flow and reactive chemical transport in fractured rocks • Fracture/matrix interactions • Hydrogeological and transport testing • Fracture flow models • Vadose zone studies • Isotopic studies of flow in fractured systems • Fractures in geothermal systems • Remediation and colloid transport in fractured systems • Nuclear waste disposal in fractured rocks The symposium proceedings, published by LBNL and containing more than 100 extended abstracts, and the monograph "Dynamics of fluids in fractured rocks: concepts and recent advances," containing 26 papers selected from those presented at the symposium (to be published by AGU in Fall 2000) will be used by many governmental agencies, universities, research organizations and private companies in solving a variety of fundamental scientific and practical problems in the earth sciences.

Figure 1. The symposium attracted more than 200 participants.

ACKNOWLEDGEMENTS

We would like to thank Paul Witherspoon for the many decades of insight, enthusiasm, friendship, and encouragement—and for giving us this wonderful occasion to grapple with the challenge of understanding the dynamics of flow in fractured rocks in the company of so many fine scientists. Support for the symposium and the monograph was provided by the U.S. Department of Energy (Oakland Operations Office, Office of Environmental Management, Office of Science and Technology, Subsurface Contaminants Focus Area, Office of Civilian Radioactive Waste Management), LBNL, Idaho National Engineering and Environmental Laboratory, U.S. Nuclear Regulatory Commission, U.S. Geological Survey and American Institute of Hydrology. The symposium steering committee included Gudmundur Bodvarsson (LBNL), John Bredehoeft (The Hydrodynamics Group, Inc., Calif.), R. Allan Freeze (R. Allan Freeze Engineering, Inc., Vancouver, B.C.), John E. Gale (St. Johns Memorial University, Newfoundland), Iraj Javandel (LBNL), Marcelo J. Lippmann (LBNL), Jane S.C. Long (University of Nevada, Reno), Frank Morrison (UC Berkeley), Shlomo P. Neuman (University of Arizona, Tucson), Thomas J. Nicholson (NRC, Washington, D.C.), John R. Nimmo (USGS), and Paul A. Witherspoon (LBNL).

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Earth Sciences Division Berkeley Lab

Fundamental and Exploratory Research Program

REACTIVE CHEMICAL TRANSPORT IN STRUCTURED POROUS MEDIA: X-RAY MICROPROBE AND MICRO-XANES STUDIES

Annual Report 1999 - 2000

Tetsu K. Tokunaga, Stephen R. Sutton1 and Keith R. Olson 1University of Chicago

OBJECTIVES

Contact: Tetsu K. Tokunaga, 510/486-7176, tktokunaga@lbl.gov

In subsurface reactive transport, large differences in chemical composition can be sustained in boundary regions such as those at sediment-water interfaces, interior regions of soil aggregates and surfaces of fractured rocks. Studies of reactive transport in such boundary zones require information on chemical speciation and concentration with appropriate spatial and temporal resolution. Predicting transport of trace elements between various environmental compartments is often unsuccessful, partly due to lack of sufficient spatial and temporal resolution. Batch studies can yield insights into kinetics and equilibrium in well-mixed systems, but much of the subsurface is very poorly mixed. Without in-situ, spatially- and temporally-resolved chemical information, transport between compartments can only be described with system-specific, nonmechanistic mass transfer models.

Micro-XANES analysis showed persistence of Cr in the Cr(VI) form along preferential transport pathways, and some reduction to Cr(III) within aggregates. X-ray microprobe and micro-XANES mapping of the aggregated soil columns following two months of slow drying (representing post-contamination conditions in a semi-arid environment) revealed reoxidation of Cr(III) to Cr(VI), and localized precipitation of Cr(VI). Localized zones of Cr(VI) precipitation were smaller than 0.1 mm, spaced about 0.5 mm apart and strongly associated with calcium.

In this project, the synchrotron x-ray microprobe and micro-XANES (xray absorption near-edge structure) techniques are used to obtain measurements of chemical profiles in a variety of critical microenvironments. Past efforts in this project focused on selenium transport and reduction in two types of microenvironments—that found at surface water-sediment boundaries, and that found within soil aggregates. Since FY 1998, the project emphasis has shifted to consider reactive transport of another environmentally important contaminant, chromium. The oxidized Cr(VI) species are mostly soluble, environmentally mobile and toxic. Most forms of reduced Cr(III) are insoluble precipitates of low toxicity. Our initial studies on reactive transport of Cr included flow-through experiments in columns of aggregated soils, including spatially-resolved, real-time tracking of initial contamination processes within soil aggregates, and later characterization of Cr redistribution upon long-term drying. The soil aggregate columns were prepared and incubated in the laboratory. The flow-through experiments were conducted under unsaturated conditions characteristic of a contamination event at a flux rate lower than the saturated permeability of the soil profile. Columns were infused with Cr(VI) solutions (concentrations up to 5200 ppm) under steady unsaturated flow for several hours. Following exposure to Cr(VI), the soil aggregate columns were mapped for distributions of total Cr, Cr(III) and Cr(VI) with x-ray microprobe and micro-XANES analyses conducted at the National Synchrotron Light Source (NSLS).

These experiments demonstrated possibilities and limitations of applying micro-XANES mapping techniques for studying reactive transport with both advection and diffusion. While the diffusive component (Cr transport into aggregates) is sufficiently slow such that micro-XANES mapping is easily performed, advective transport (through macropore networks) is typically too rapid for tracking with this technique. The relatively quick reoxidation of Cr(III) within aggregate interiors suggests that later reactions with Mn(IV) are important. Despite reoxidation, later precipitation of Cr(VI) with Ca in localized zones may diminish its mobility because of the low solubility and low surface area of the precipitate.

APPROACH

SIGNIFICANCE OF FINDINGS

ACKNOWLEDGEMENTS

Research was in part carried out at the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory. We thank Tony Lanzirotti and the staff of NSLS. This work has been supported by the Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences Research Program of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

ACCOMPLISHMENTS

X-ray microprobe mapping of total Cr distributions showed active macropore transport paths and transport into individual soil aggregates.

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Earth Sciences Division Berkeley Lab

Fundamental and Exploratory Research Program

UNSATURATED FAST FLOW

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FRACTURED ROCK: TRANSIENT FILM FLOW

Annual Report 1999 - 2000

Tetsu K. Tokunaga, Jiamin Wan and Stephen R. Sutton1 1University of Chicago Contact: Tetsu K. Tokunaga, 510/486-7176, tktokunaga@lbl.gov

OBJECTIVES

Water films along unsaturated fractures have recently been shown to be capable of supporting fast flow and transport.

The nature of unsaturated fast-flow in fractured rocks needs to be understood in order to obtain reasonable constraints on vadose zone transport. Water films along unsaturated fractures have recently been shown to be capable of supporting fast flow and transport. In this project, theoretical considerations and experiments are combined to improve our understanding of unsaturated flow in fractured rocks. Our work is concerned with water films on fracture surfaces under near-zero (negative) matric potentials, and examines the possibility of fast, unsaturated flow under "tension." Our past work examined equilibrium and steady-state conditions. Our recent studies in this area are concerned with transient film flow.

SIGNIFICANCE OF FINDINGS

By considering films on fracture surfaces as analogues to water in partially saturated porous media, the film hydraulic diffusivity and equation for transient film flow are obtained from their porous medium counterparts, the hydraulic diffusivity and the Richards equation. Fast film flow (average velocities greater than 3x10-7 m s-1 under unit gradient conditions) was observed for average film thicknesses greater than 2 Âľm and matric potentials greater than -1 kPa.

APPROACH

Since film flow appears to be a surface analog to flow in bulk unsaturated porous media, the macroscopic relations useful for describing film flow are expected to be surface analogs of the Darcy-Buckingham law and the Richards equation. This analogy was used to define the film hydraulic diffusivity and the constitutive equation for transient film flow. Transient film flow can be studied through measuring the rate of film spreading on initially dry, hydrophilic surfaces. A simple model for transient film flow under the step-function approximation was developed in a manner analogous to that of the early infiltration model of Green and Ampt, and was applied to water film spreading on a glass cast of a granite fracture surface, and on roughened glass. Three methods previously developed for determining saturation-dependent hydraulic diffusivities of porous media were also used. These methods use a suction plate device to impose step changes in potentials along one boundary. A modified version of the suction plate device was developed for purposes of measuring film hydraulic properties. Equilibrium and transient measurements of film thickness, matric potential and film hydraulic diffusivity were measured through xray fluorescence of a solute tracer (selenate) monitored using a synchrotron x-ray fluorescence microprobe (National Synchrotron Light Source (NSLS), beamline X26A).

PUBLICATIONS

Tokunaga, T.K. and J. Wan, Water film flow along fracture surfaces of porous rock, Water Resour. Res., 33, 1287-1295, 1997. Tokunaga, T.K., J. Wan and S.R. Sutton, Transient film flow on rough fracture surfaces, Water Resour. Res., 36, in press, 2000. Wan, J., T.K. Tokunaga, T. Orr, J. O'Neill and R.W. Conners, Glass cast of rock fracture surfaces: A new tool for studying flow and transport, Water Resour. Res., 36, 355-360, 2000.

ACKNOWLEDGEMENTS

Research was in part carried out at Brookhaven National Laboratory’s National Synchrotron Light Source (NSLS). We thank Grace Shea-McCarthy, Tony Lanzirotti and the staff of NSLS. This work has been supported by the Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences Research Program of the U.S. Department of Energy under Contract No. DEAC03-76SF00098.

ACCOMPLISHMENTS

The measurements showed the average film thickness dependence on matric potential is approximated as a power function. The various methods for determining film hydraulic diffusivities yielded consistent results. It was also shown that within the range of parameters tested, the film hydraulic diffusivity increases with increased film thickness (and with increased matric potential). Such a trend is indicative of flow through directly interconnected surface channels and has been termed "hypodiffuse" by P. G. de Gennes.

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Earth Sciences Division Berkeley Lab

Fundamental and Exploratory Research Program

SURFACE EXCESS

OF CLAY COLLOIDS AT GAS-WATER INTERFACES Jiamin Wan and Tetsu K. Tokunaga

Annual Report 1999 - 2000

Contact: Jiamin Wan, 510/486-6004, jmwan@lbl.gov

OBJECTIVES

Colloids have been found to favorably sorb at air-water interfaces in many natural environments. In vadose zones, sorption of colloid-associated contaminants at air-water interfaces can influence contaminant fate and transport. For solutions containing surface-active molecules, measurement of changes in surface tension with changes in solute concentration permits calculation of their surface excess through the Gibbs adsorption equation. For suspensions of particles, surface tension changes are often not measurable. Much effort has been devoted to characterizing surface accumulations of particles and associated species. Because of large uncertainties in thicknesses and interfacial areas sampled, results are often reported as the enrichment factors for a given estimated thickness. Our objectives were to develop a method for quantifying colloid surface excesses at air-water interfaces without requiring assumptions concerning the thickness of interfacial regions (completed in 1998), and to obtain the first partition coefficient data of most common subsurface colloids.

Figure 1. Vadose zone implications of colloid sorption at air-water interfaces. Depending on water film thickness and flow, colloid partitioning at air-water interfaces may enhance or retard their transport through the vadose zone.

APPROACH

The bubble column method (Wan and Tokunaga, 1998) was used to measuring partition coefficients of different types of clay (kolinite, montmorillonite and illite, and goethite colloids at the gas-water interface. In the bubble column, air is bubbled through a vertical column containing the dilute colloidal suspension, with an open free surface at the top. The rising bubbles sorb and carry the surface-active species upwards, then release them back to the solution at the free surface where the bubbles burst. At steady-state, a concentration profile is established along the column length, which reflects the balance between upward transport by partitioning onto rising bubbles and downward transport by eddy dispersion. By predetermining the column eddy dispersion coefficient for given conditions (column dimensions, air flow rate and bubble size) and measuring the steady-state concentration profile, the partitioning between bulk and surface regions can be determined.

ues of air-water interfacial area per unit bulk volume. Due to the common existence of thin water films in the vadose zone, the distribution of surface-active colloids between bulk water and the air-water interface can become significant. The calculated values of colloid distribution at the air-water interface relative to bulk water ranged from about 1 to 20 for a wide range of the soil saturation, for most types of colloids studied. This has important implications on colloid transport and transformation in vadose environments.

ACCOMPLISHMENTS

RELATED PUBLICATIONS

Using our bubble column method, we measured the partition coefficients (K) of many common types of subsurface colloids under environmentally relevant conditions. Montmorillonite is essentially non-surface active at any given pH and ionic strength. Illite was slightly surface active, with increased K values at lower pH and higher ionic strength (K= 0 to 40 µm). Kaolinite particles are very highly surface active at pH below 7 (K values are up to 240 µm). Humic acid is slightly to moderately surface active. Goethite is extremely surface active at pH below 9 (K values up to 320 µm). This method permits quantification of surface excesses of a wide range of inorganic, organic and microbial colloids, as well as molecular species complexed onto colloids. Through the measured K values, we are now able to predict what types of colloids are surface active, to what degree and under what conditions.

Wan, J., and T.K. Tokunaga, Measuring partition coefficients of colloids at air-water interfaces, Environ. Sci. Technol, 32, 3293-3298, 1998. Wan, J., and T.K. Tokunaga, Surface excess of clay colloids at gas-water interfaces, J. Colloid and Interface Science, submitted.

ACKNOWLEDGEMENTS

SIGNIFICANCE OF FINDINGS

The ability to measure colloid surface excesses at air-water interfaces enables more quantitative analyses of a variety of environmental processes. This is especially relevant in the vadose zone, where there can be high val-

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We thank Richard Stover, Jenny Yong and Keith Olson for assistance. Funding was provided by the Office of Environmental Management, Environmental Management Science Program, and the Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences Research Program, of the U.S. Department of Energy under Contract No. DE-AC03-76SF-00098. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Fundamental and Exploratory Research Program

COLLOID FORMATION DURING INFILTRATION OF WASTE TANK LIQUID INTO HANFORD SEDIMENTS

Annual Report 1999 - 2000

Jiamin Wan, Tetsu Tokunaga, Eduardo Saiz,1 Keith Olson and Srinivas Veerapaneni 1Materials Sciences Division, LBNL OBJECTIVES

Contact: Jiamin Wan, 510/486-6004, jmwan@lbl.gov

Leakage of underground tanks containing high-level nuclear waste solutions has been identified at various U.S. Department of Energy facilities. The Hanford, Wash., site is the main facility of concern, with about 2,300 to 3,400 m3 of waste liquids leaked. Radionuclides and other contaminants have been found in elevated concentrations in the vadose zone and groundwater underneath single-shell tank farms. Understanding the nature of pathways and mechanisms responsible for deep vadose zone contaminant transport is urgent for future remediation. It is speculated that colloid-facilitated contaminant transport significantly contributes to rapid contaminant migration. Due to the extreme chemical conditions of most of these tank-waste solutions, understanding interactions between the highly reactive waste solutions and sediments becomes a key step in predicting contaminant migration through the deep vadose zone. The objectives of this research are to identify the key processes occurring at the contaminant reaction front, including identifying reaction products, kinetics, colloid generation and permeability reduction.

Figure 1. (a) Tube 1 contains the original simulated tank waste solution. Tube 2 contains effluent from the leading edge of tank waste liquid draining from a column experiment at 70˚ C, containing greatest suspension concentration of secondary colloids. Tube 3 is the effluent immediately following tube 2, containing a much lower concentration of colloids, and an increasing concentration of Fe-rich particles. (b) Colloids formed at 21˚C (analytic electron microscope microphotograph).

APPROACH

The process of leaking tank-waste solution interacting with the underlying sediments was simulated through infiltration of the simulated REDOX tank waste solutions into columns packed with Hanford vadose zone sediments. Experiments were conducted at elevated (70°C) and room temperatures. The effluents from columns were collected with fraction collectors. Turbidity, pH and chemical compositions of the effluents were analyzed. The secondary colloids collected from effluents were characterized for their compositions (analytical electron microscopy), mineralogy (x-ray diffraction), particle size (transmission electron microscope and ZETA sizer) and surface charge properties (DELSA).

the large quantity of secondary colloids, the inventory of indigenous colloids is often small. Evaluating their carrying capacity of contaminants, the degree of release and transport is a critical issue for understanding highly sorptive contaminant transport at Hanford and other sites. This is an issue that must be addressed.

ACCOMPLISHMENTS

RELATED PUBLICATION

Precipitates of colloids form primarily at the infiltration front of the REDOX waste solution plume, which is the moving boundary of maximum geochemical disequilibrium. These secondary colloids formed by dissolution and precipitation have very different chemical compositions and mineralogy at different temperatures, indicating different formation mechanisms. These significant quantities of particles of colloidal size and larger are unstable in suspension, and can become attached to sand grains. Precipitation, plugging and cementation sometimes significantly reduce permeability. Plugging-cementation is most effective at high temperatures, but remains very influential at ambient temperatures as well. Colloid releases into effluent solutions were most significant during two short intervals, one associated with the leading edge of the waste front, and the second at the leading edge of the post-flushing (low ionic strength) solution.

Wan, J., T. Tokunaga, E. Saiz, K. Olson and S. Veerapaneni, Colloid formation during infiltration of waste tank liquid into Hanford sediments, Environ. Sci. Technol, submitted.

ACKNOWLEDGEMENTS

SIGNIFICANCE OF FINDINGS

Our laboratory studies revealed the complex processes of reactiondependent colloid generation/release, permeability change and flow pathway alteration that will strongly influence vadose zone flow and transport of REDOX tank contaminants in the Hanford vadose zone. In comparison to

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We thank Chuck Echer of LBNL’s National Center for Electron Microscopy (NCEM) for AEM analyses, Scott Mountford for chemical analyses and Peter Persoff for providing the Hanford vadose zone sediments. This work has been supported by the Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences Research Program, and the Environmental Management Science Program of the U.S. Department of Energy under Contract No. DEAC03-76SF00098. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

FE3+ SORPTION

ON

Fundamental and Exploratory Research Program

QUARTZ SURFACES: THE BEGINNINGS

OF

PRECIPITATION

Annual Report 1999 - 2000

Glenn A. Waychunas, Rebecca Reitmeyer,1 James A.Davis1 and Jennifer A. Coston1 1U.S. Geological Survey, Menlo Park, Calif. Contact: Glenn A. Waychunas, 510/486-2224, gawaychunas@lbl.gov

RESEARCH OBJECTIVES

Iron oxyhydroxides are powerful agents for metal sorption and scavenging in the environment. Recently we have determined that aquifer grains containing only trace amounts of iron oxyhydroxides may have sorption dominated by these phases due to their ubiquitous presence as nanometer coatings and precipitates. The coatings often show complex topology and local high surface area. Our goals are to understand the processes by which these coatings are formed, determine their reactivity for sorption processes compared to bulk iron phases, and describe the structure and crystal chemistry of the coatings as completely as possible on the nanometer to micron scale.

APPROACH

Both laboratory model studies and field sampling are being performed. In the laboratory we are using both perfect quartz crystals with m-, r- and c-plane surfaces and high surface area Aerosil silica for sorption experiments. The perfect crystal faces have only widely separated (thousands of Å) 2.6 Å layer steps on an otherwise smooth substrate, but these features provide a natural "defect" to explore heterogeneous nucleation. The Aerosil material has an irregular surface with a high concentration of surface silanol groups where binding can occur. In the field we have emplaced samples of the perfect quartz substrates into sampling wells at the U.S. Geological Survey Cape Cod aquifer site, and will emplace similar samples in an aquifer in Naturita, Colo., during FY 2000. Samples are being studied by x-ray spectroscopy (XAS) at the Stanford Synchrotron Radiation Laboratory (SSRL), with high resolution transmission electron microscopy (HRTEM) at the National Center for Electron Microscopy (NCEM) at LBNL, and with atomic force microscopy (AFM) at the USGS in Menlo Park. XAS measurements allow us to determine the molecular structure of sorbed iron atoms or multinuclear precipitates, as well as their relationship to the surface Si atoms. A special technique, called grazing incidence XAS (GIXAS), allows us to study the precipitates on crystal surfaces at the lowest possible concentrations, as well as determine precipitate orientation. The TEM and AFM studies produce images with nanometer resolution that aid in relating molecular structure to nanometer and larger surface structures and defects.

Figure 1. Geometry of sorbed Fe3+(O,OH)6 group on the quartz surface. Corner oxygen atoms not shown. Plus and minus signs refer to relative charge on oxygens that create a distorted Fe site.

SIGNIFICANCE OF FINDINGS

An important result is the effect of drying and aging on precipitate formation. Our observations suggest that the nucleation of initial precipitates occurs during undersaturated periods. This explains how the low density of surface complexes in natural aqueous systems can be driven to precipitate formation. Analogous phenomena occurs with other sorbants and mineral substrates. Hence studies of sorption reactions in natural systems must include the effects of undersaturation events in the history of the process.

RELATED PUBLICATIONS

Waychunas, G., J.A. Davis and R. Reitmeyer, Aqueous Fe3+ sorption on silica surfaces, 1997 SSRL Activity Report, 7, 145-147, 1998. Waychunas, G., J.A. Davis and R. Reitmeyer, Grazing-incidence EXAFS study of Fe3+ sorption on single crystal quartz substrates, J. Synchrotron Radiation 6, 615-617, 1999.

ACCOMPLISHMENTS

Our initial studies have indicated several dramatic changes in sorption behavior for Fe3+ sorbed from low-pH solutions. First, at surface concentrations below 0.30 micromol M-2, a direct inner sphere complex is observed, where individual Fe3+(O,OH)6 units are connected by corners to adjacent SiO4 tetrahedra on the surface (see Figure 1). This concentration is two orders of magnitude below the number of available surface silanol sites, yet above this value precipitation of multinuclear iron oxyhydroxy polymers occurs. Second, drying of samples having only sorbed complexes converts most of these into polymers and precipitates. Aging of samples kept wet also produces polymerization, but at a much slower rate. Third, polarized measurements indicate hematite-like precipitates with strong orientational order on single crystal samples. These precipitates are seen mainly at layer steps in AFM images.

ACKNOWLEDGEMENTS

This work has been supported by the Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098 and by the U.S. Geological Survey’s Water Resources Research Program. 25

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Earth Sciences Division Berkeley Lab

MEASUREMENT

OF

Fundamental and Exploratory Research Program

REACTION RATES IN NATURAL FLUID-ROCK SYSTEMS USING SR AND U ISOTOPES

Annual Report 1999 - 2000

Donald J. DePaolo

Contact: Donald J. DePaolo, 510/643-5064, djdepaolo@lbl.gov

RESEARCH OBJECTIVES

A major need of the Department of Energy, and indeed a major objective of geochemistry, is to be able to predict the transport of chemical constituents in fluids in the earth. This applies to environmental remediation, geothermal and fossil energy resources, climate change science and nuclear waste isolation. One of the weak points in models for reactive chemical transport is the estimation of fluid-solid reaction rates, particularly for dissolution and precipitation reactions. Fluid-solid reaction rates are also important for predicting corrosion and weathering rates. Formulations can be made using kinetic theory, but it is a seemingly ubiquitous occurrence that other factors, some presumably involving mineral surfaces and others involving transport limitations on various scales, alter the predicted reaction rate by up to several orders of magnitude. One means of addressing this issue is through the microscopic study of mineral surfaces, and substantial effort is now being made to do this using synchrotron radiation. A complementary and necessary approach, which we have taken, is to use isotopic tracers (primarily Sr, but also U and Nd) to determine fluid-solid exchange rates in various natural situations. The isotopic methods characterize the reaction rates in the system at the scale of the "reaction length." The reaction length depends on the ratio of the transport by diffusion and advection to the reaction rate, and can be anywhere from a few centimeters to hundreds of meters depending on the element used and the natural environment. The ultimate objective will be to understand the microscopic (as well as pore scale and mesoscale) characteristics of natural systems that contribute to establishing the "field scale" reaction rates. An intermediate goal is to establish empirically the natural range of fluid-solid reaction rates; if the range is limited and there are systematic variations, then a useful engineering-style tool is established.

slowest low temperature systems, to about 10-6 yr-1 for the fastest high temperature systems (at ca. 600°C). The determined rates are not highly variable, show a significant but relatively weak temperature dependence, and are 2 to 8 orders of magnitude smaller than typical laboratory rates measured far from equilibrium. In some cases, empirically inferred rates combined with isotopic measurements can serve to constrain groundwater flow velocities; this is particularly useful for cases where the velocities are very small, such as the vadose zone at Yucca Mountain, Nevada. The differing reaction lengths for different elements (eg., Sr and O; or Sr and Nd) in the same system can also be exploited to extract information on the mesoscale hydrology (eg., fracture spacing) of some fluidrock systems. Use of multiple isotope systems can help to identify the rates of specific reactions in complex natural systems.

SIGNIFICANCE OF FINDINGS

The results of these studies indicate that fluid-rock reaction rates can be deduced by measurements of the natural system at the scale of interest. The uncertainties in the deduced rates are far smaller than the uncertainties from application of kinetic theory, and can constitute a reasonably solid basis for predicting reactive chemical transport. The observation that reaction rates typically fall in a limited range is also useful.

APPROACH

To determine reaction rates, the Sr and U isotopic composition of fluids and rocks are measured in saturated zone groundwater, vadose zone groundwater, geothermal systems, deep sea pore fluids and in metamorphic rocks. The groundwater and geothermal systems are advective, the fluid velocities are meters to hundreds of meters per year (less in the vadose zone), and the reaction lengths for Sr are in the range of kilometers to hundreds of kilometers. In deep sea pore fluids and metamorphic systems, the transport in the fluid phase is mainly by diffusion; the reaction lengths vary from tens of centimeters to tens of meters. To determine the rates, the groundwater flow velocity (or fluid phase diffusivity) must be constrained. Uncertainties in these values are typically less than a factor of Âą3.

RELATED PUBLICATIONS

Johnson, T.M., and D.J. DePaolo, Rapid exchange effects on isotope ratios in groundwater systems, 2. Flow investigation using Sr isotope ratios, Water Resources Res., 33, 197-205, 1997.

ACKNOWLEDGEMENTS

This work has been supported by the Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences Research Program of the U.S. Department of Energy under Contract No. De-AC03-76SF00098.

RESULTS

Deduced fluid-solid exchange rates correspond to mineral dissolution time constants (grams dissolved/gram/yr) in the range 3 x 10-9 yr-1 for the

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Earth Sciences Division Berkeley Lab

Fundamental and Exploratory Research Program

GEOCHEMISTRY AND ISOTOPE CONSTRAINTS

IN

OIL HYDROGEOLOGY

Annual Report 1999 - 2000

B. Mack Kennedy, Tom Torgersen,1 Matthijs ("Thijs") van Soest and David L. Shuster 1University of Connecticut Contact: B. Mack Kennedy, 510/486-6451, bmkennedy@lbl.gov

RESEARCH OBJECTIVES

The mechanisms, processes and time scales of fluid flow in sedimentary basins represent fundamental questions relevant to the occurrence and distribution of energy and mineral resources. In this project, these questions are addressed using noble gas abundance and isotope variations measured in hydrocarbon fluids on a field and basin scale to identify fluid sources, the extent of oilwater-gas interaction and to delineate migration pathways.

APPROACH

Fluids of economic importance in sedimentary basins contain noble gases from a variety of sources, such as meteoric and connate waters, magmatic fluids, etc. (see Figure 1). Each source can have a unique noble gas isotopic and/or abundance characteristic from which it can be identified. Therefore, the noble gases can provide unique information about fluid sources, the relative importance of individual fluid sources and the extent they interact during the process of forming an economic resource, such as a hydrocarbon reservoir. In favorable cases they can be used to identify fluid migration pathways and time scales, reservoir filling sequences and the degree of reservoir isolation.

ACCOMPLISHMENTS

Figure 1. Sources of noble gases in fluids related to hydrocarbon reservoirs.

One of the most significant findings of this project is that production fluids from oil and gas reservoirs tend to be enriched in heavy noble gases (krypton and xenon). This component was derived originally from the atmosphere (probably from air saturated sea or ground water), was adsorbed and trapped in the petroleum source rock, and subsequently was expelled and mixed with the hydrocarbons during oil-gas expulsion and primary migration. Support for this hypothesis has been provided by laboratory studies of noble gases in carbon-rich and petroleum source rocks. During secondary migration and reservoir storage, the hydrocarbon system interacts with meteoric and connate groundwater, which dilutes the heavy noble gas enriched component by adding lighter noble gases extracted from the air-saturated waters. The degree of oil-water dilution provides a measure of the integrated volume of water that has been in contact with the hydrocarbon system and places geometric constraints on migration models and time scales.

• •

The limits on the volume of water that have been in contact with the hydrocarbons place geometric constraints on oil/gas formation/migration models and time scales. Field- or basin-wide systematic trends in the water dilution factors of production fluids from individual wells can be used to map oil and gas migration pathways and reservoir filling sequences, and identify individual reservoirs with common hydrocarbon source regions.

RELATED PUBLICATIONS

Torgersen, T., and B.M. Kennedy, Air-Xe enrichments in Elk Hills oil field gases: role of water in migration and storage, Earth Planet. Sci. Lett. 167, 239-253, 1999.

SIGNIFICANCE OF FINDINGS

The ability to use noble gas geochemistry to quantify oil-water-gas interaction during hydrocarbon expulsion, primary and secondary migration, and reservoir storage has several important applications: • The extent the heavy noble gas component associated with the hydrocarbons is diluted with gases extracted from air saturated groundwater places firm limits on the effective volume of water that has been in contact with the hydrocarbons during the course of secondary migration and reservoir storage.

ACKNOWLEDGEMENTS

This project has been supported by the Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences Research Program of the U.S. Department of Energy under Contract No. DE-AC03-76 SF00098. 27

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Earth Sciences Division Berkeley Lab

Fundamental and Exploratory Research Program

DEVELOPMENT OF GPR TECHNIQUES TO NON-INVASIVELY MEASURE SUBSURFACE WATER CONTENT

Annual Report 1999 - 2000

Susan Hubbard, Katherine Grote1 and Yoram Rubin1 of Civil and Environmental Engineering, UC Berkeley

1Dept.

RESEARCH OBJECTIVES

Contact: Susan Hubbard, 510/486-5266, sshubbard@lbl.gov

Water content information is vital for transportation, agriculture, vadose zone contaminant hydrogeology, global circulation models, soil erosion and geotechnical investigations. Subsurface water content is highly variable in both space and time. Conventional instruments for measuring soil moisture are not well-suited for collecting data over large areas since they require invasive drilling and sample only small volumes of soil. Currently, no technique is available to accurately provide soil water content measurements over the spatial and temporal scales necessary for estimating, monitoring and modeling subsurface moisture movement. In this project, we investigate the potential and limitations of ground penetrating radar (GPR) methods as a tool for providing accurate water content estimates in a non-invasive manner.

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APPROACH

We have conducted three field experiments to test the feasibility of using surface GPR to estimate subsurface moisture content. The first experiment was performed under very controlled conditions at a constructed "test pit" near Richmond, Calif., and the second was performed on two nearby engineered pavement sections. To test the method under more natural conditions, we have initiated a test at the Robert Mondavi Winery in Napa, Calif., where moisture content information is desired to dictate vineyard operations such as irrigation. GPR methods use short pulses of high-frequency electromagnetic energy to probe the subsurface. Figure 1a shows an example of a GPR data display; this cube displays reflections emanating from soil layer interfaces that have different moisture contents or textures. This figure shows lateral changes in the soil stratigraphy (as indicated by the GPR reflectivity), and in moisture content (as indicated by the neutron probe measurements). As the travel time of the radar signal is primarily affected by changes in the moisture content in unsaturated materials, once calibrated, we can estimate moisture content of subsurface layers by analyzing the time it takes for an electromagnetic wave to propagate through the layers. An example from the test pit is shown in Figure 1b, where volumetric moisture content measurements, obtained in the laboratory using gravimetric techniques, are compared to estimates obtained using travel time information extracted from surface GPR data at one location in space. The difference between measured and GPR-estimated water content at the test pit is less than 1%.

Figure 1. (a) GPR data display, and (b) comparison of GPR and gravimetric volumetric water content values vs. depth.

high-resolution estimates of moisture content in a non-invasive manner.

SIGNIFICANCE OF FINDINGS

Development of a tool that can quickly and accurately provide aerially extensive soil water content estimates in a non-invasive manner would be beneficial for many disciplines that require such information for their models or decision-making processes.

RELATED PUBLICATION

ACCOMPLISHMENTS

To date, we have completed a proof of principle for the surface GPR technique at the test pit under very controlled conditions, developed a procedure to very precisely process the GPR data and extract travel time information, and worked on developing the petrophysical relationships needed to link the GPR travel time to moisture content. We are currently testing the potentials and limitations of this GPR method under variable saturation conditions at a pavement study site and in natural heterogeneous soils at the Napa field site. Once the GPR techniques are developed for use in the field, we will integrate the GPR information with remote sensing data collected at the Napa site. Our goal is to provide time-lapse, three-dimensional and

Grote, K., S. Hubbard, A. Lawrence, J. Harvey, M. Riemer, J. Peterson and Y. Rubin, Nondestructive monitoring of sub-asphalt water content using surface ground penetrating radar techniques, EOS 80(46), PF291,1999.

ACKNOWLEDGEMENTS

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We acknowledge the support of Caltrans, the Water Resources Council and the California Energy Commission for supporting this endeavor. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Fundamental and Exploratory Research Program

COMPUTATION OF SEISMIC WAVEFORMS IN COMPLEX MEDIA: CARBON DIOXIDE SEQUESTRATION IMAGING

Annual Report 1999 - 2000

Valeri A. Korneev, Lane R. Johnson and Thomas V. McEvilly Contact: Valeri A. Korneev, 510/486-7214, vakorneev@lbl.gov

RESEARCH OBJECTIVES

The underground sequestration of CO2 presents a subsurface monitoring problem requiring new approaches in seismic waveform inversion techniques that can take into account the presence and effects of diffracted waves. This CO2 specific problem is an important example of the need for effective tools applicable to subsurface imaging problems. Seismic tomographic imaging methods are severely compromised when the target region and/or the background medium are complex at the wavelength scale of the probing waves and when diffracted energy becomes a significant part of the wavefield. Travel-time imaging alone is inadequate in such situations — the problem requires use of full-waveform characteristics, where potentially accessible information on image subtlety is contained. Waveform tomography, however, suffers from a lack of fast and accurate numerical simulators necessary for effective and efficient forward computation of the propagating wavefield.

APPROACH

Weyburn monitoring experiment. Elastic 2D wave propagation simulation. Point pressure source in Marley dolomite.

Figure 1. Numerical modeling of wave propagation in prospective CO2 storage reservoir chosen by Pan Canadian Inc. revealed a dominance of guided waves in transmitted field for cross hole experiment. Direct arrivals of body waves are weak and hidden by head waves coming from adjacent high velocity layers. This suggests use of guided waves for reservoir imaging and monitoring.

We develop a seismic mapping technique which will, among other applications, provide monitoring capability for the planned underground CO2 repositories. For this purpose a new hybrid 3-D finite-difference pseudospectral method is under implementation using overlap-domain decomposition in combination with a new mapping algorithm based on liquid saturated layers seismic properties. This requires a fundamental understanding of storage properties of potential reservoirs, along with the physics and chemistry involved in multiphase transport of CO2 in porous and fractured media. A geologically focused disposal strategy will require effective monitoring of the CO2 injection to define its phase state and distribution, to track migration paths and to map the accumulation in order to control the process and to estimate the potential capacities of CO2 reservoirs. To study the effects of gas and liquid formations on seismic wave energy we model seismic wave propagation through media containing local low-velocity liquid or gas phase regions. The complex character of CO2 deposits demands 3-D wave-propagation modeling. In order to study capabilities of different inversion techniques, 3-D elastic modeling can also be used to compute representative synthetic data sets for testing. The objective of this work is to develop and apply a powerful new inversion technique for imaging and monitoring man-made underground CO2 repositories, as well as other highly heterogeneous subsurface targets.

This will require development of an effective forward modeling program which will be applied to a set of specific applications covering a wide range of spatial scales, using real data sets we have acquired. One of the applications will be time-lapse imaging of gas/steam and CO2 injection experiments in existing oil fields, with a goal of better understanding steam floods, CO2 sequestration, gas storage and geothermal reservoir exploitation.

ACKNOWLEDGEMENTS

This work is supported by the Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences Research Program, of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

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Earth Sciences Division Berkeley Lab

Fundamental and Exploratory Research Program

THREE-DIMENSIONAL INTERPRETATION OF BOREHOLE-TO-SURFACE ELECTROMAGNETIC DATA

Annual Report 1999 - 2000

Hung-Wen Tseng, Ki Ha Lee and Alex Becker

Contact: Hung-Wen Tseng, 510/486-5502, hwtseng@lbl.gov

RESEARCH OBJECTIVES

Simulation and interpretation of 3-D electromagnetic (EM) problems are challenging tasks. The process involved is usually very time-consuming because of the large number of unknowns to solve. Consequently, the development of a simulation code of dramatically improved efficiency is essential. To this end, a new scheme dubbed the modified extended Born approximation (MEBA), has been developed for efficient 3-D simulation and interpretation of geophysical EM data.

APPROACH

Originating from the integral equation method and assuming a constant electric current density in a conductivity-anomalous region, the MEBA technique is used to calculate, without solving a huge matrix equation, the total electric field in the inhomogeneity by multiplying the background electric field with a depolarization tensor. Simulation results show that the MEBA technique yields better accuracy when current channeling dominates induction in the conductivity inhomogeneity. Fourier transform and convolution theorem have been used to improve the efficiency of the method. The MEBA method has been successfully incorporated into a 3-D inversion code, and its use in matrix leads to improved computational efficiency.

Figure 1. 3-D MEBA inversion results using (a) pre-extraction BTS data and (b) post-extraction data. The vertical section contains the transmitter well and the surface profile while the horizontal slice is at a depth of 28 m. (c) Conductivity change, in percentage with respect to the pre-extraction conductivity, due to the salt-water drawing.

absent in the post-extraction results shown in Figure 1b. The conductivity change due to the water removal is expressed in Figure 1c in percentage terms relative to the conductivity before the pumping. Clearly, the effect of the pumping has reduced the conductivity of the injected zone by as much as 35%.

deriving the Jacobian

ACCOMPLISHMENTS

The MEBA technique has been successfully applied to interpret borehole-to-surface (BTS) EM field data acquired at the University of California’s Richmond Field Station, where a brine spill was simulated by creating a saline water injection zone at a depth of about 30 m. The plume, of which the extent was to be determined from the post-injection BTS data, was later extracted and the experiment was construed as monitoring a remediation process. The BTS data were the vertical component of the magnetic fields collected at 5 m intervals along a 110-m-long surface profile centered at the injection well, in which the transmitter was run upward from 60-m-depth to the surface. Both data sets acquired before and after the water extraction were inverted by starting with a 12 ohm-m homogeneous half space as the initial model. Figure 1a shows the interpreted pre-extraction conductivity distribution in the vertical plane containing the surface profile and the transmitter borehole, and in a horizontal slice at 28-mdepth. The corresponding post-extraction results are displayed in Figure 1b. The sections in the lower left and the lower right corners in the vertical plane should be considered as contaminated due to numerical artifacts. The two distinct units with a boundary at about 40-m-depth correspond to the interwoven sediments and the basement at the test site, respectively. The injected salt-water plume manifests itself as a small conductive region,

SIGNIFICANCE OF FINDINGS

Applications of the Fourier transform and convolution theorem to the MEBA technique increase its efficiency dramatically and make EM 3-D interpretation on ordinary computing platforms practical.

ACKNOWLEDGEMENTS

30

This work has been supported by the Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences Research Program, and by the Assistant Secretary for Fossil Energy, Office of Gas and Petroleum Technologies, of the U.S. Department of Energy under Contract No. DEAC03-76SF00098. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Fundamental and Exploratory Research Program

CENTER

FOR

COMPUTATIONAL SEISMOLOGY (CCS)

Annual Report 1999 - 2000

Thomas V. McEvilly, Ernest L. Majer and Lane R. Johnson Contact: Thomas V. McEvilly, 510/486-7347,tvmcevilly@lbl.gov

RESEARCH OBJECTIVES

The Center for Computational Seismology (CCS) serves as the core data processing, computation and visualization facility for seismology-related research at LBNL. As such, it will be integral to our critical efforts in mapping the distribution and migration of fluids in the subsurface, a problem requiring new approaches in seismic waveform inversion techniques that can take into account the presence and effects of diffracted waves. A wide range of research projects relies upon CCS resources for development and application of methods for characterization, process definition and process monitoring in the rock-fluid-thermochemical subsurface environment. Pursuing an objective of providing modern tools for seismological research, the Center is designed and operated to provide a focused environment for research in modern computational seismology by scientists whose efforts at any time may be distributed among diverse research projects. A large number of varied, separately funded research projects, from many different sponsors, rely upon this resource for intellectual exchange as well as computational needs. Ph.D. theses and journal publications reveal a spectrum of effort from the most fundamental theoretical studies to field applications at all scales.

Figure 1. Seismic velocity tomograms (top) from the INEEL TAN site with location map (bottom) showing well pair. Zones of low velocity (yellow-red) are interpreted as fractured basalt (possibly rubblized contacts between basalt flows), which allows high flow within the aquifer. High-velocity zones (blue) are reinterpreted as dense, unfractured basalt that acts as a barrier to contaminant flow within the aquifer. The upper two inferred flow zones have been confirmed as contaminant transport zones by well logs.

RELATED PUBLICATIONS

APPROACH

Byun, J., and J.W. Rector, Wide angle effects in cross-well reflection imaging, J. Seismic Explor., in press. Gritto, R., V.A. Korneev and L.R. Johnson, Nonlinear 3-dimensional inversion of low frequency scattered elastic waves, Pure & Appl. Geoph., in press. Hubbard, S.S., Y. Rubin and E. Majer, Spatial correlation structure estimation using geophysical and hydrogeological data, Water Resources Research, vol. 35, no. 6, 1809-1825, 1999. Keers, H., L. Johnson and D. Vasco, Crosswell imaging using asymptotic waveforms, Geophysics, submitted. Nadeau, R.M., and T.V. McEvilly, Fault slip rates at depth from recurrence intervals of repeating microearthquakes, Science 285, 516-519, 1999. Parker, P., Genetic algorithms and their use in geophysical problems, 1999.

CCS provides a specially equipped and staffed computational facility to support and advance a wide-ranging program of seismological research. Beyond computers, workstations, seismic processing packages and visualization capabilities, it is a physical facility in which scientists pursuing individual research interact with other scientists and technical support staff in a multidisciplinary intellectual environment. CCS supports research in the general areas of wave propagation, geophysical inverse methods, earthquake and explosion source theory, seismic imaging, borehole geophysics, four-dimensional process monitoring and visualization technology.

ACCOMPLISHMENTS

Results from the diverse seismological program at CCS are best demonstrated in the CCS research output. Major accomplishments flow largely from the breadth of research support provided by CCS, and the cross-fertilization between applications and fundamental studies. Significant recent results involve successful imaging of contaminant flow zones in fractured basalt, development of borehole orbital vibrator technology and promising results in CO2-monitoring with borehole imaging methodology.

SIGNIFICANCE OF FINDINGS

Findings for a facility and scientific environment such as that provided by CCS must be defined in the context of the multidisciplined research base that is supported there, rather than project-specific accomplishments (those appear in other sections of this report). It is fair to attribute a large part of the scientific reputation in seismology at LBNL to the CCS environment.

ACKNOWLEDGEMENTS

31

This work has been supported by the Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences Research Program of the U.S. Depart-ment of Energy under Contract No. DE-AC03-76SF00098. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Fundamental and Exploratory Research Program

SAN ANDREAS FAULT MONITORING AT PARKFIELD

Annual Report 1999 - 2000

Thomas V. McEvilly, Richard Clymer, Robert Nadeau, John Peterson and Don Lippert Contact: Thomas V. McEvilly, 510/486-7347,tvmcevilly@lbl.gov

RELATED PUBLICATIONS

RESEARCH OBJECTIVES

Since 1987, a special network of 10 borehole seismographs has operated at Parkfield, Calif., as part of the U.S. Geological Survey-directed earthquake prediction experiment underway there. The purpose of the network is to provide data on the occurrence of earthquakes as small as magnitude 1.0 for improving our understanding of fault-zone dynamics. Of particular importance is the role of the network in providing a roadmap of the microearthquake population for the SAFOD (San Andreas Fault Observatory at Depth) deep drilling project to be conducted at Parkfield.

Burgmann, R., D. Schmidt, R.M. Nadeau, M. d'Alessio, E. Fielding, D. Manaker, T.V. McEvilly and M.H. Murray, Earthquake potential along the Northern Hayward Fault, California, Science, submitted. Foxall, W., Fault-zone heterogeneity as a controlling factor in the dynamic behavior of the San Andreas Fault in Central California, Ph.D. thesis, 1992. Johnson, P., Source processes of small earthquakes, M 1-5: Studies of the San Andreas Fault at Parkfield and Long Valley Caldera, California, Ph.D. thesis, 1997. Korneev, V.A., T.V. McEvilly and E.D. Karageorgi, Seismological studies at Parkfield VIII: modeling the observed controlled-source waveform changes, Bull. Seism. Soc. Am. 90, 702-708, 2000. Michelini, A., Fault zone structure determined through the analysis of earthquake arrival times, Ph.D. thesis, 1991. Nadeau, R.M., Full-waveform studies of elasticwave propagation in the San Andreas Fault Zone at Parkfield as a process-monitoring technique, Ph.D. thesis, 1995. Nadeau, R.M., and L.R. Johnson, Seismological studies at Parkfield VI: moment release rates and estimates of source parameters for small repeating earthquakes, Bull. Seism. Soc. Am., 88, 790-814, 1998. Nadeau, R.M., and T.V. McEvilly, Fault slip rates at depth from recurrence intervals of repeating microearthquakes, Science, 285, 718-721, 1999. Nadeau, R.M., and T. V. McEvilly, Seismological studies at Parkfield V: characteristic microearthquake sequences as fault-zone drilling targets, Bull. Seism. Soc. Am., 87, 1463-1472, 1997.

APPROACH

The network is designed to be able to detect and locate precisely the smallest earthquakes possible, a result of the extremely low background noise and attenuation found at the sensor depths of 200-300 meters. For the deep drilling project, we are adding three new sensors in boreholes near the planned intersection at 3-4 km depth on the active fault surface. Installation, operation, maintenance and much of the data reduction has been accomplished through joint efforts of campus and LBNL personnel.

ACCOMPLISHMENTS

Analyses of the 12+ years of monitoring data have revealed significant and unambiguous departures from stationarity both in the seismicity characteristics and in wave propagation details. A high Vp/Vs anomaly exists at depth. Synchronous changes well above noise levels have been seen among several independent parameters, including seismicity rates, average focal depth, Swave coda velocities, characteristic sequence recurrence intervals, fault creep and water levels in monitoring wells. Scaling laws have been developed from the Parkfield earthquakes that can be projected to fit earthquakes up to M6, and they predict unprecedented high stress drops and melting on the fault surface for the smallest events. Recurrence interval variations in the characteristic event sequences (>60% of the microearthquake population) have been used to map fault slip rate at depth on the fault surface. We have challenged the conventional "constant stress drop" source model, affirmed characteristic earthquake occurrence and developed four-dimensional maps of fault-zone microearthquake processes at the unprecedented scale of a few meters. This unique body of new observations and data analyses has provided much of the impetus for Parkfield as the preferred site for deep drilling into an active seismogenic fault zone - a concept that has become the large national initiative SAFOD.

SIGNIFICANCE OF FINDINGS

The significance of these findings lies in their apparent coupling and interrelationships, from which models for fault-zone process can be fabricated and tested with time. The more general significance of the project is its production of a truly unique continuous baseline, at very high resolution, of both the microearthquake pathology and the subtle changes in wave propagation, providing to the seismological community an earthquake laboratory available nowhere else.

ACKNOWLEDGEMENTS

This work has been supported by the U.S. Geological Survey's National Earthquake Hazards Reduction Program and the National Science Foundation through subcontracts from UC Berkeley. 32

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Earth Sciences Division Berkeley Lab

Fundamental and Exploratory Research Program

COMPACTION AND FRACTURING

OF

WEAKLY-CEMENTED GRANULAR ROCKS

Annual Report 1999 - 2000

Larry R. Myer, Seiji Nakagawa, and Brad A. Bessinger Contact: Larry R. Myer, 510/486-6456, lrmyer@lbl.gov

RESEARCH OBJECTIVES

In weakly cemented porous granular materials, the lack of dilatational forces at the grain scale can lead to the development of an unusual thin slitlike failure feature (Figure 1). In contrast to the typical borehole breakout resulting from KI-mode (opening mode) fractures propagating perpendicular to the direction of local tensile stress, this type of failure feature develops perpendicularly to the local compressional stress and therefore is called an "anti-KI" fracture. Understanding fundamental microprocesses associated with these features is important for design of stable boreholes in weakly cemented rock. Whereas a typical borehole breakout achieves a stable geometry for a given material strength and in situ stress state, observations imply that these features extend indefinitely. In this research, a series of laboratory experiments has been performed to understand the effect of grain shape, cementation and the mechanical removal of debonded grains upon the failure mode of a weakly cemented granular medium.

Pullvertical Quote pull axial quotecompression pull quote pull quote “splitting� fracture (KI mode)

horizontal dilatational fracture (anti-KI mode)

APPROACH

typical borehole breakout in Berea sandstone

Figure 1. Anti-KI mode fracture formed around a borehole within a synthetic sandstone. This failure feature is markedly different from the classical borehole breakout with fractures developing parallel to the local compressional stress field.

Laboratory uniaxial compression tests were performed on thin rectangular bricks of artificial sandstones made of glass beads and silica sand. Each brick contained a single small diameter hole as an analogue of a twodimensional borehole. Beads and natural sand were used so the effect of grain shape on the failure behavior of the specimens could be studied. Varying amounts of sodium silicate solution were used as a binder to achieve a range of cohesive strength between grains. The bricks were loaded vertically in the direction perpendicular to the borehole, and the development of compaction zones and fractures around the hole were observed.

of the anti-KI borehole failure. It is likely that this mode of failure can occur even within relatively competent sandstones if liquid flow (water, drilling fluid, etc.) can remove sand grains in a manner similar to the compressed air used in this study.

ACCOMPLISHMENTS

For glass bead specimens, the characteristic "anti-KI" fracture formed regardless of the amount of sodium silicate binder. In contrast, for silica sand specimens, "dog-ear" shaped compaction/shear zones formed in the direction perpendicular to the axial load. However, if the debonded grains were removed from the failure zone using compressed air flow, the fracture similar to the glass-bead specimens developed. In a silica sand specimen with very strong intergranular cohesion, fractures propagating parallel to the direction of compressional stress were observed (classical borehole breakout failure). These fractures penetrated through individual sand grains, indicating that the dilation due to failed grains allowed the transmission of local compressional stress driving the fractures in this direction.

RELATED PUBLICATIONS

Bessinger, B.A., Z. Liu, N.G.W. Cook and L.R. Myer, A new fracturing mechanism for granular media, Geophys. Res. Lett., 24(21), 26052608, 1997. Myer, L.R., S. Nakagawa and B.A. Bessinger, Role of local dilatation in formation of compaction bands, Eos, Trans. Am. Geophys. Union, 79(45), F1067, 1999.

ACKNOWLEDGEMENTS

SIGNIFICANCE OF FINDINGS

This work has been supported by the Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences of the U.S. Department of Energy under Contract No. DEAC03-76SF00098.

The results indicate the importance of grain removal in determining the failure mode of weakly cemented porous granular rock. Rock characteristics such as high porosity, round grains and the existence of a mechanical force that dislodges the grains from the fracture tip can assist in the development

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Earth Sciences Division Berkeley Lab

Fundamental and Exploratory Research Program

RESONANCE INVERSION

FOR

ELASTIC MODULI

OF

ANISOTROPIC ROCKS

Annual Report 1999 - 2000

Seiji Nakagawa, Kurt T. Nihei and Larry R. Myer

Contact: Seiji Nakagawa, 510/486-6792, snakagawa@lbl.gov

RESEARCH OBJECTIVES

Heterogeneities in rock in the form of systematically oriented mineral grains, bedding planes and aligned microcracks often result in anisotropic bulk stress-strain behavior that can be described by anisotropic elastic moduli. Although these elastic constants can be determined either statically from load-displacement tests or dynamically from the velocities of elastic waves, cumbersome testing procedures, including the preparation of multiple, oriented samples, makes the determination of the anisotropic elastic moduli difficult. However, acoustic resonance spectroscopy has been successfully applied to small single crystals and minerals. This research applies a similar technique to determine the elastic moduli of rocks with anisotopic properties resulting from micro-scale heterogeneities.

APPROACH

Figure 1. Comparison of experimentally measured and computed frequency responses of an anisotropic granite cube specimen. The computed response is for the five elastic moduli inverted from measured resonance frequencies.

Acoustic resonance spectroscopy is a technique for determining the dynamic elastic constants of a specimen using steady-state vibration of a specimen of known geometry. The technique consists of resonating the specimen over a broad range of frequencies, measuring the resonance frequencies and computing the elastic constants by nonlinear inversion of the measured resonance frequencies. Mode shapes of the anisotropic specimens are also measured using a laser Doppler vibrometer and compared with the prediction by the numerical model with the inverted elastic constants.

kHz ~ several MHz), frequency-dependent dynamic properties of rock can be examined from comparison with the obtained elastic moduli. In contrast with other techniques, the acoustic resonance technique requires only a single or a few measurements for determining anisotropic elastic constants of the specimen. Although the current technique requires modifications for measurements under realistic confining stresses, the results indicate that it can be a powerful tool for characterizing the anisotropic and frequency-dependent elastic properties of rocks.

ACCOMPLISHMENTS

A comparison of experimental and computed frequency responses for the inverted moduli of a granite specimen (transversely isotropic based on observations by optical microscope and ultrasonic transmission tests) is shown in Figure 1. Although there are discrepancies between spectral amplitudes, the resonance frequencies and the general shapes of the responses showed good agreement. A comparison between the elastic moduli determined by static loading tests, resonance inversion and ultrasonic transmission tests showed reasonable agreement between the ultrasonic and resonance results, but the moduli determined from ultrasonic measurements were consistently higher than the resonance inversion. This result may be due to the slight frequency-dependence of the wave velocity in microscopically heterogeneous rock and non-elastic (frictional) deformation of the rock specimen during the static loading tests.

RELATED PUBLICATIONS

Nakagawa, S., Acoustic resonance characteristics of rock and concrete containing fractures, Ph.D. thesis, UC Berkeley, 1998.

ACKNOWLEDGEMENTS

This work has been supported by the Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences of the U.S. Department of Energy under Contract No. DEAC03-76SF00098.

SIGNIFICANCE

Since acoustic resonance spectroscopy uses wave frequencies (frequency range) that are lower than those of the ultrasonic transmission tests (100

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Earth Sciences Division Berkeley Lab

Fundamental and Exploratory Research Program

SHEAR-INDUCED CONVERSION

OF

SEISMIC WAVES

ON A

Seiji Nakagawa, Kurt T. Nihei and Larry R. Myer

Contact: Seiji Nakagawa, 510/486-6792, snakagawa@lbl.gov

FRACTURE

Annual Report 1999 - 2000

RESEARCH OBJECTIVES

For geological and geotechnical applications, the behavior of fractures subjected to shear stress is of particular importance, particularly when frictional slip causes mechanical failure and changes in the hydraulic conductivity of the fracture. To monitor the changes in the stress acting on a fracture, seismic methods are among the most promising since the stress change causes changes in the stiffness of the fracture, which affects the transmission and reflection characteristics of the seismic waves. This research demonstrates how seismic waves can be used to measure the magnitude and direction of shear stress acting on fractures in rock.

APPROACH

Laboratory seismic wave transmission tests were performed on a single induced fracture in a granite core and in steel blocks with a periodic sawtooth surface that simulates a sheared fracture. Under a constant normal stress, the fractures were subjected to a range of static Figure 1. Conversion of incident S-waves to P-waves transmitted shear stress and the particle motion and amplitude of converted across a fracture. Amplitude of the converted wave increases with waves were measured. Numerical simulation was also performed increasing static shear stress and the particle motion changes the using a 2-D dynamic boundary element method modeling a sheared phase by 180Ëš when the direction of shear is reversed. fracture as an array of tilted open microcracks. Furthermore, an existing analytical model for the dynamic wave-fracture interaction (the seismic displacement discontinuity model) was extended to account for the dilaconverted waves can be related to those of the tion effect of a fracture under static shear stress. static shear stress. For a medium containing multiple parallel fractures, higher-order ACCOMPLISHMENTS anisotropy in the velocity and amplitude of The laboratory measurements showed the generation of mode convertwaves result. The shear-induced conversion ed waves (P to S and S to P waves) upon fractures subjected to static shear behavior of seismic waves has a potential as a stress (see Figure 1). The amplitude of converted waves increased with the stress-probing tool for not only geological and magnitude of static shear stress and the direction of particle motion changed geotechnical applications but also manufacturin accordance with the direction of applied shear stress. These results are ing and material processing applications. supported by the numerical simulations as well as the prediction by the anaRELATED PUBLICATIONS lytical model. Using the extended seismic displacement-discontinuity Nakagawa, S., K.T. Nihei and L.R. Myer, Shear model, anisotropic wave propagation in a multiply fractured medium subinduced conversion of seismic waves across jected to static shear stress was also examined both analytically and numersingle fractures, Int. J. Rock Mech. Min. Sci. & ically. The result indicated that the seismic anisotropy of the background Geomech. Abstr., 37(1-2), 203-218, 2000. medium can be strongly augmented by the shear-induced anisotropy of fractures.

ACKNOWLEDGEMENTS

SIGNIFICANCE

This work has been supported by the Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences of the U.S. Department of Energy under Contract No. DEAC03-76SF00098.

The experimental, numerical and theoretical results show that the static shear stress applied to compliant fractures alters the scattering characteristics of seismic waves. For normally incident seismic waves incident upon a single fracture, the amplitude and direction of particle motion of

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Earth Sciences Division Berkeley Lab

DECOMPOSITION

Fundamental and Exploratory Research Program

SCATTERING AND INTRINSIC ATTENUATION HETEROGENEOUS MULTIPHASE FLUIDS

OF

Kurt T. Nihei, Seiji Nakagawa, and Larry R. Myer

IN

ROCK

WITH

Annual Report 1999 - 2000

Contact: Kurt T. Nihei, 510/486-5349, ktnihei@lbl.gov

RESEARCH OBJECTIVES

This project investigates scattering and intrinsic attenuation of seismic waves in rock with heterogeneous distributions of fluids and gas. This research represents a departure from past studies on seismic attenuation in that the focus here is not a detailed study of a specific attenuation mechanism, but rather an investigation of theoretical and laboratory methods for obtaining separate estimates of scattering and intrinsic attenuation in rock with heterogeneous pore fluid distributions. The objectives of this project are threefold: (1) adapt and further refine methods for decomposing scattering and intrinsic attenuation in rock with heterogeneous multiphase fluids; (2) apply these methods to laboratory seismic measurements in porous rock with heterogeneous fluid distributions and compare these results with direct laboratory measurements; and (3) examine a new method for focusing seismic waves in heterogeneous media using time-reversal mirrors. These objectives are addressed in three tasks to be performed over a period of three years.

APPROACH

Figure 1. Selective focusing on a fluid front in a stratified elastic

The first phase of this project has focused on the third objecmedium using the DORT algorithm applied to time-lapse differenced pressure data (26 source/receiver array, 100 Hz). tive: the adaptation of time-reversal focusing concepts to monitoring the movement of fluids in the subsurface using fixed arrays of produce excellent focusing of the wavefield on sources and receivers that have the capability to selectively focus seismic the CO2 front. waves on heterogeneities formed by the impedance contrast between fluids and gas. Unlike seismic imaging, focused arrays do not provide images of SIGNIFICANCE OF FINDINGS the subsurface, but rather attempt to enhance the scattered wavefield off the While the potential of time-reversal focusing heterogeneity of interest while suppressing the scattering from surrounding methods for reservoir monitoring is clear, a numheterogeneities. This is achieved by providing the appropriate phase shifts ber of factors need to be addressed for the appliand amplitudes to the array of sources. The principal benefit of focusing is cation to monitoring heterogeneous multiphase the potential to selectively illuminate heterogeneities in situ, thus providing fluids. For example, the DORT method has been information about the number and the strengths of the heterogeneities. In demonstrated to be robust for illuminating disaddition, the use of prefocused data in seismic imaging algorithms may crete scatterers embedded in fluids and tissues. potentially result in higher resolution images of heterogeneities in the subSince geologic media typically contain scatterers surface. of varying size, shape, density and aspect ratios, ACCOMPLISHMENTS and, additionally, may be anisotropic and visNumerical studies of elastic wave focusing using a vertical array of coelastic (time-reversal invariance breaks down sources and receivers were performed using 2-D finite difference simulain the presence of intrinsic attenuation, the focus tions. The DORT (Decomposition of the Time Reversal Operator) algorithm of our research will be to adapt the time-reversal (Prada and Fink, 1994) was applied to determine the source phasing paramfocusing method to heterogeneous, anisotropic, eters for selective focusing on a particular scatterer. The figure displays a viscoelastic media. time-lapse fluid-front monitoring example of the DORT method. Strong verACKNOWLEDGEMENTS tical multiple reflections from the layered stratigraphy near the This work has been supported by the Office source/receiver array result in poor focusing when applying DORT to the of Science, Office of Basic Energy Sciences, scattered wavefield. However, if time-lapse data is available, differencing Division of Chemical Sciences of the U.S. the recorded wavefields obtained from surveys performed at two instances Department of Energy under in time during the migration of the fluid front effectively filters out these Contract No. DE-AC03-76SF00098. vertical reverberations. Application of DORT to the differenced wavefield 36

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Earth Sciences Division Berkeley Lab

Fundamental and Exploratory Research Program

FORMATION AND STABILITY OF METHANE HYDRATES

IN

CLAY INTERLAYERS

Annual Report 1999 - 2000

Sung-Ho Park, Garrison Sposito, Rebecca Sutton and Jeffery A. Greathouse Contact: Sung-Ho Park, 510/643-9951, sungho_park@lbl.gov

RESEARCH OBJECTIVES

The objectives of this project are to: (1) evaluate whether methane hydrates can form in hydrated 2:1 clay interlayers; (2) determine optimal conditions for hydrate formation of this kind, in terms of pressure, temperature and methane concentration; and (3) estimate the stability of the interlayer clathrate in terms of the translational motions of methane.

APPROACH

Our approach uses computer simulations based on Monte Carlo (MC) and molecular dynamics (MD) methods. Natural methane hydrates are found where marine sediments, including 2:1 clay minerals, are also found. Therefore, modeling was initiated by Monte Carlo phase-sampling of a system containing not only methane and water molecules, but also the clay mineral Na-montmorillonite. Our laboratory is well-experienced in the study of water structure in restricted geometry, especially within the clay interlayers. After finding a clathrate structure (20 to 22 methaneoxygen coordination number) from MC simulations, we carried out MD simulations to study its stability and dynamical properties.

Figure 1. Monte Carlo "snapshot" of methane hydrates in a Namontmorillonite interlayer. The "cage" indicates methane clathrate formation between water oxygens and oxygens from the clay mineral surface. The cage volume includes oxygens within 5.5 Ă… of the methane molecule.

RELATED PUBLICATIONS

ACCOMPLISHMENTS

From the MC simulations, the most stable structures observed were at atmospheric pressures of 10, 20 and 30 for a three-layer hydrate of Na-montmorillonite containing 0.5, 1.0, or 2.25 methane molecules per clay unit cell, respectively. The first two methane systems showed 22- and 20- coordination of methane with oxygens from both the clay surface and interlayer water molecules (Figure 1). The third system showed methane molecules in close proximity to each other, indicating possible phase separation. In our MD simulations, the first two systems showed relatively low methane self-diffusion coefficients in comparison with the third system. Clathrate-like behavior also was observed for the first two methane systems with respect to their velocity autocorrelation functions (VACFs) for methane. The power spectrum, obtained through Fourier transform of the VACF, is consistent with published inelastic incoherent neutron scattering data on methane hydrates in pure water alone. Pair correlations in terms of radial distribution functions, power spectra, VACFs and the self-diffusion coefficients of methane and water all indicated a clathrate-like structure of the methane hydrate in clay interlayers for both of the lower-concentration methane systems. The highest-concentration methane system did not show a stable clathrate structure.

Sposito, G., N.T. Skipper, R. Sutton, S.-H. Park, A.K. Soper and J. Greathouse, Surface geochemistry of the clay minerals, Proc. Natl. Acad. Sci. USA 96: 3358, Berkeley Lab report LBNL-43158, 1999. Sposito G., S.-H. Park and R. Sutton, Monte Carlo simulation of the total radial distribution function for interlayer water in sodium and potassium montmorillonites, Clays Clay Miner, 47: 192, Berkeley Lab report LBNL42847, 1999. Park, S.-H., and G. Sposito, Monte Carlo simulation of total radial distribution functions for interlayer water in Li-, Na-, and K-montmorillonite hydrates, J. Phys. Chem. B, 104: 4642, Berkeley Lab report LBNL-45842, 2000.

ACKNOWLEDGEMENTS

SIGNIFICANCE OF FINDINGS

This work has been supported by the Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences of the U.S. Department of Energy under Contract No. DEAC03-76SF00098.

The new clathrate structure proposed for hydrated clay interlayers is important for understanding the formation and stability of natural gas hydrates. Our modeling may give valuable insight for future studies of methane hydrate P/T relations.

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Earth Sciences Division Berkeley Lab

Fundamental and Exploratory Research Program

Annual Report 1999 - 2000

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Annual Report 1999 - 2000

Earth Sciences Division Berkeley Lab

Nuclear Waste Program Gudmundur S. Bodvarsson 520/486-4789 gsbodvarsson@lbl.gov

T

he role of the Nuclear Waste Program is to assist the U.S. Department of Energy, the United States and other countries in solving the problem of safe disposal of nuclear waste through high-quality scientific analyses and technology development. The primary work of the program involves investigating the feasibility and potential of the Yucca Mountain site in Nevada for permanent storage of high-level nuclear waste. The Nuclear Waste Program also does collaborative work on nuclear waste disposal issues with such countries as Japan, Switzerland, Sweden, China and Romania. The program has established the Center for International Radioactive Waste Studies, the main purpose of which is to foster relationships with other countries to promote exchange of ideas and research results. The Yucca Mountain Site is located about 120 km northwest of Las Vegas in a semi-arid region. The potential repository will be located about 350 m below the surface within a thick unsaturated zone (UZ). The subsurface rocks at Yucca Mountain consist primarily of fractured volcanic tuffs that vary in degree of welding. To date, a total of 60 deep surface boreholes have been drilled in the area. An 8-km-long underground tunnel, the Exploratory Studies Facility (ESF), was completed in 1996 at Yucca Mountain. Berkeley Lab’s work at Yucca Mountain consists of solving many ground-breaking problems related to multiphase, nonisothermal flow and transport through the UZ. Some of the key questions Laboratory scientists are addressing include: • How much water percolates through the UZ to the repository at Yucca Mountain? • What fraction of the water flows in fractures and how much flows through the matrix blocks? • How much of this water will seep into the waste canister emplacement drifts? • How will radionuclides migrate from the repository to the water table? • How will coupled TH (thermo-hydrological), THC (thermo-hydrologicchemical) and THM (thermo-hydrologic-mechanical) processes affect flow and transport?

The Nuclear Waste Program is organized into three main groups — Ambient Testing, Thermal Testing and Modeling — to address these questions, with support from geophysical studies.

AMBIENT TESTING GROUP

39

The Ambient Testing group investigates how water flows through the mountain and how much of this water will seep into the emplacement drifts. The group performs various tests within the ESF, including fracture/matrix interaction tests, drift-to-drift tests, the Paint Brush Unit test (PTn test), and niche (short drift) testing. Fracture/matrix interaction tests are relatively small-scale (a few meters) tests that focus on the components of water flow in fractures and matrix blocks and on the interaction between the two continua. The drift-to-drift tests address the same issues, but on a much larger spatial scale (10-20 m). The test in the Paint Brush Unit, which is an unwelded tuff unit, addresses issues of episodic flow, effects of faults and large-scale features, and lateral continuity of flow and transport. This unit, being above the potential repository, is key to dispersed fracture flow from the above fractured units and buffers the transient behavior of episodic flow. The niche studies address perhaps the most crucial problem of Yucca Mountain, i.e., determining the HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Annual Report 1999 - 2000

Nuclear Waste Program

fraction of water that will flow into the emplacement drifts. The niche studies are carried out by introducing water into boreholes above the drift opening and measuring what fraction actually seeps into the opening. Results to date suggest that there is a seepage threshold, below which no water will seep into the drifts.

ture tension, matrix potential, temperature, geochemical, perched water and other data from the UZ. The model is then used to predict all of these variables in new boreholes and new drifts to be drilled. The degree of agreement between the model predictions and the subsequent observations give a measure of the reliability for the model, and guidance to what additional data need to be collected and incorporated. A very important sub-model of the UZ model is the seepage model, which is on a tensof-meters scale, versus the UZ model’s hundreds-of-thousands-of-meters scale. The seepage model, in a similar fashion as the UZ model, predicts the results of the niche tests, and is modified subsequently to match the actual observations. Another sub-model of the UZ model is the coupled process THC model that is calibrated using the heater test data, and used to estimate the chemistry of water and gas entering the drifts. All these models—the UZ model, the seepage model and the THC model—are key process models for Total System Performance Assessment (TSPA); performance of the potential repository is only as reliable as these key models.

THERMAL TESTING GROUP

The Thermal Testing group works in collaboration with other national laboratories to evaluate the effects of heat on thermodynamic conditions, fluid flow and transport, and permanent property changes at and near the emplacement drifts. The Yucca Mountain Project has completed the first in situ heater test, called the Single Heater Test. The project is now involved with a large-scale heater test in a 50-m-long drift. This second test is intended to resemble the actual in-place conditions when the high-level radionuclide waste is placed in the emplacement drifts. Berkeley Lab’s role in the heater tests is to characterize the heater test rock block (area) prior to testing; monitor potential changes in fracture and matrix saturations through air injections, tracer testing and ground-penetrating radar measurements; and to perform predictive thermo-hydrological and thermo-hydrologicchemical calculations. The initial characterizations of the heater test areas are performed with air injection tests that yield the 3-D permeability structure of the fracture network. Continued air-injection testing during heating yielded changes that can be attributed to changes in fracture saturations or mechanical effects. Cross-hole radar tomography has also yielded very promising results regarding change in global saturations of the system due to heating. Laboratory scientists are also involved with measurements of the isotopic compositions of gases and condensate water collected in instrumented boreholes. Detailed 3-D thermo-hydrologic and thermo-hydrologic-chemical calculations were used to predict the behavior of the tests. These are being refined as the test progresses.

FUNDING

The Nuclear Waste Program’s Yucca Mountain Project research is supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memorandum Purchase Order EA9013MC5X between TRW Environmental Safety Systems Inc., and the Ernest Orlando Lawrence Berkeley National Laboratory (Berkeley Lab). The support is provided to Berkeley Lab through the U.S. Department of Energy Contract No. DE-AC03-76SF00098.

MODELING GROUP

Berkeley Lab has the primary responsibility for the development of the UZ flow and transport model. This is a comprehensive 3-D, dual-permeability numerical model that represents the entire UZ at and near Yucca Mountain. The model is intended to integrate in a single computational framework all of the relevant geological, hydrological, geochemical and other observations that have been made at the surface, in boreholes and in tunnels at Yucca Mountain. The model is calibrated against pneumatic mois-

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Earth Sciences Division Berkeley Lab

Nuclear Waste Program

GEOLOGY OF YUCCA MOUNTAIN AT

THE POTENTIAL Jennifer Hinds

REPOSITORY HORIZON

Annual Report 1999 - 2000

Contact: Jennifer Hinds, 510/486-7107, jhinds@lbl.gov

RESEARCH OBJECTIVES

The objective of this study is to describe the geological setting of the potential repository horizon at Yucca Mountain, Nevada, within which high-level radioactive waste would be stored. To a large extent, geological characteristics dictate how well the potential repository would perform as a structure for isolating waste. From a safety standpoint, the geological setting determines the stability of excavated underground tunnels. In terms of potential transport of hazardous particles (principally, by means of water percolating through the mountain), the geology of the site, along with climate, determine groundwater flow characteristics (e.g., preferential flow pathways and potential fast-flow pathways).

APPROACH

An evaluation of the geology at the potential repository horizon involves the collection and synthesis of available geological data from project reports, maps and models. Data obtained from a dozen surface-based vertical boreholes, a recent bedrock geologic map and two underground exploratory tunnels define the geology of the potential repository block. A 3-D geological model based on these data has been developed for the purpose of visualizing the geometric orientation of the multiple rock layers and major faults in the Yucca Mountain area.

ACCOMPLISHMENTS

The three geological units slated to house the potential repository are the middle nonlithophysal, the lower lithophysal and the lower nonlithophysal units of the Topopah Spring Tuff, a regionally extensive pyroclastic-flow sheet. These three units are characterized by dense welding (caused by compaction and fusion of the tuffs at high temperatures) and abundant fractures. A distinguishing feature of the lower lithophysal unit is the abundance of cavities (lithophysae) formed by bubbles of volcanic gases trapped in the tuff matrix during cooling. These cavities vary in size, reaching up to a meter in diameter. Under the 1999 repository design (Figure 1), the majority (approx. 80%) of the repository horizon would be located in the lower lithophysal unit (Tptpll). The remaining 20% of the repository would be divided almost equally between the middle nonlithophysal (Tptpmn) and the lower nonlithophysal (Tptpln) units. Large normal-type displacement faults bound the potential repository area to the east and west (i.e., the Ghost Dance and Solitario Canyon faults, respectively). No major faults have been projected into the current repository footprint, though numerous small-offset faults (<30 meters vertical displacement), such as the Sundance fault, have been observed.

Figure 1. Geological units encountered at the potential repository horizon at Yucca Mountain.

RELATED PUBLICATIONS

Clayton, R., Geologic framework model (GFM3.1), MDL-NBS-GS-000002 REV00 ICN 01, Las Vegas, Nevada, CRWMS M&O, 2000. Bodvarsson, G.S., et al., Unsaturated zone flow and transport model process model report (UZ PMR), Las Vegas, Nevada: CRWMS M&O, 2000. Hinds, J., and L., Pan, Development of numerical grids for UZ flow and transport modeling, ANLNBS-HS-000015 REV 00, Las Vegas, Nevada, CRWMS M&O, 2000.

ACKNOWLEDGEMENTS

This work was supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memorandum Purchase Order EA9013MC5X between TRW Environmental Safety Systems, Inc., and Ernest Orlando Lawrence Berkeley National Laboratory for the Yucca Mountain Site Characterization Project under Contract No. DE-AC03-76SF00098.

SIGNIFICANCE OF FINDINGS

Understanding the characteristics of the middle nonlithophysal, lower lithophysal and lower nonlithophysal units is vital to the construction of a potential repository. Fracture characteristics and lithophysal abundance within these units determine rock stability and the distribution of percolation flux, which has important implications for seepage into potential waste emplacement drifts and for transport of radionuclide particles. 41

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Earth Sciences Division Berkeley Lab

MOISTURE DYNAMICS

IN THE

Nuclear Waste Program

REPOSITORY FOOTPRINT AT YUCCA MOUNTAIN

Annual Report 1999 - 2000

Rohit Salve

Contact: Rohit Salve, 510/486-6416, r_salve@lbl.gov

RESEARCH OBJECTIVES

Measurements of rock water content and water potential are being pursued at the Exploratory Studies Facility (ESF) at Yucca Mountain, Nevada, to provide data for various numerical modeling efforts and for better understanding hydrologic processes. Recently, a Cross Drift was constructed as part of the Enhanced Characterization of the Repository Block (ECRB). This construction has provided the first opportunity for moisture measurements in the actual repository footprint. Because ventilation of the ESF and ECRB creates a dry-out zone around the drift that extends into the formation, the characterization of rock moisture properties needs to be coupled with investigations of moisture dynamics within the tunnel. The primary objective of this effort is to determine the status of water in the repository formation and the types of effects that are associated with ventilation of the ESF and ECRB.

APPROACH

Psychrometer measurements of water potential are being made along the length of boreholes installed at various locations within the ECRB and ESF. Additionally, electrical resistivity probes (ERPs) have been installed alongside the psychrometers to monitor temporal changes in moisture content. Along the tunnel bores humidity, temperature, barometric pressure and air velocity are being measured at various stations to provide information on moisture conditions along the tunnel. The ventilation effects on the formation are being investigated on a section of the Cross Drift where construction of a bulkhead has sealed the ECRB from tunnel ventilation effects (at depths greater than 1,743 m). While the Main Drift and the rest of the ECRB are subject to ventilation affects associated with air movement along the tunnel, the area behind the bulkhead has largely remained sheltered. The bulkhead was installed in June 1999, and was exposed to tunnel ventilation for a couple of days in January 2000 and then again in April 2000.

Figure 1. Water potential measurements from two locations within the ECRB after bulkhead installation in June, 1999. Station 20+00 was mined earlier and therefore shows more dry out (i.e., depth and magnitude of drying front) than Station 25+00.

ACCOMPLISHMENTS

Psychrometers and ERPs have been installed in three locations in the Cross Drift (two of which are located in the zone with minimized ventilation effects) and two locations in the Main Drift. Ten stations have been installed to monitor humidity, temperature and barometric pressure in the Cross Drift and Main Drift.

be close to saturation. Observed puddles of water in the non-ventilated zones in the ECRB raise questions about the source of this water and the conditions leading to such condensation/seepage.

SIGNIFICANCE OF FINDINGS

Preliminary data suggest that ventilation effects within the ECRB have reduced water potentials between 1.4 and 2.0 m in distance from the tunnel. At greater distances, water potentials are >-10 m. When the bulkhead was opened briefly in January and April 2000, small puddles of moisture were observed about 1000-1200 m from the bulkhead. The psychrometer data provides the first measurements of water potential in the potential repository formation. It shows that ventilation effects are important because they could potentially affect the advancement of water plumes into the main drift, thereby influencing the amount of seepage. However, beyond the zone affected by ventilation effects, the formation could

ACKNOWLEDGEMENTS

42

This work was supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memorandum Purchase Order EA9013MC5X between TRW Environmental Safety Systems, Inc., and Ernest Orlando Lawrence Berkeley National Laboratory for the Yucca Mountain Site Characterization Project under Contract No. DE-AC03-76SF00098. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

INTERPRETATION

Nuclear Waste Program

OF INJECTION TESTS IN FRACTURED Jerry P. Fairley

POROUS MEDIA

Annual Report 1999 - 2000

Contact: Joseph S. Wang, 510/486-6753, jswang@lbl.gov

RESEARCH OBJECTIVES

The objective of this study was to quantify wetting front instability in a fracture/matrix system and apply the results to the interpretation of two insitu injection tests. Understanding fracture flow and wetting front instability is critical for modeling fast pathways, fracture/matrix interaction and contaminant transport in heterogeneous media.

(a)

APPROACH

A mathematical representation of a fracture/matrix system was solved by approximate analytical methods and the system stability investigated using a first-order perturbation expansion. Model predictions were compared to field tests in which water was injected into a high permeability fracture and collected in a slot located 1.6 meters below the injection point (Figure 1a). The fraction of injected water recovered in the slot (β) was compared with model predictions to build confidence in the model and to gain insight into the test results.

(b)

ACCOMPLISHMENTS

In the first test (Figure 1b) model/data agreement was excellent for early-times (dimensionless times τ < 5, where τ = τ/τc, and τc is the time at which gravitational potential and water potential are equal at the wetting front). Erratic intermediate-time system response was attributed to capillary effects arising from fracture heterogeneity. This behavior resulted in poor model/observation agreement until shortly before test termination, at about τ = 18.5. A second test (not shown) displayed little influence from fracture heterogeneity, probably because wetting from the first test reduced the effective fracture heterogeneity. The shape of the curves matched closely for all times; however, model predictions overestimated β by a constant factor, consistent with a 20% loss of water from the test bed (or other experimental error).

Figure 1. (a) Members of the Ambient Testing Group inserting trays into the collection slot. The trays collected fracture flow from an injection point 1.6 meters above the slot (photo credit: C.M. Oldenburg). (b) The fraction of injected water recovered in the slot (β) vs. dimensionless time τ (Test 1). Model/data agreement is good for early and late times. Poor intermediate-time agreement probably results from fracture heterogeneity.

SIGNIFICANCE OF FINDINGS

The early- and late-time model/data agreement for the first test, and close correspondence in the shape of the recovery curves for the second test, provided confidence that the model accurately portrayed the gross system behavior. Extension of the model to heterogeneous fracture properties may improve model/data agreement. The analysis indicated that the scale of testing was too small to manifest instability, and provided an estimate of the scale needed for future tests.

ACKNOWLEDGEMENTS

This work was supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memorandum Purchase Order EA9013MC5X between TRW Environmental Safety Systems, Inc., and Ernest Orlando Lawrence Berkeley National Laboratory for the Yucca Mountain Site Characterization Project under Contract No. DE-AC03-76SF00098.

RELATED PUBLICATIONS

Fairley, J.P., Theoretical and field studies of fracture/matrix interaction, Ph.D. dissertation, Department of Materials Science and Mineral Engineering, University of California, Berkeley, Calif., 2000. Wang, J.S.Y. (ed.), Progress report on fracture flow, drift seepage and matrix imbibition tests in the Exploratory Studies Facilities, Lawrence Berkeley National Laboratory, Berkeley, Calif., 1998. 43

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Nuclear Waste Program

INTERPRETING TEST DATA ON WATER FLOW Curtis M. Oldenburg and Rohit Salve

IN A

FAULT

Annual Report 1999 - 2000

Contact: Curtis M. Oldenburg, 510/486-7419, cmoldenburg@lbl.gov

RESEARCH OBJECTIVES

To investigate the potential for fast flow through the Paintbrush nonwelded unit (PTn) at Yucca Mountain, Nevada, we carried out in situ field tests involving the release of water into a minor subvertical normal fault at Alcove 4 in the Exploratory Studies Facility (ESF) at Yucca Mountain. The zeolitically and argillically altered rocks of the lower Pah Canyon Tuff (Tpp) and the upper pre-Pah Canyon bedded tuffs (Tpbt2) are exposed in Alcove 4. Water was released at constant head into a packed-off interval straddling the fault within a horizontal borehole in the Tpp. The intake rate gradually fell from ~200 ml min-1 to 50 ml min-1 over a period of 41 hours of cumulative release time spread over 17 days of testing. Wetting was monitored using innovative electrical resistivity pads in a borehole 1 m below in the Tpbt2 in the fault interval and in the surrounding matrix.

APPROACH

Figure 1. Data and simulated (best-fit) water-intake rate in borehole 12 assuming exponential decline in permeability.

Data analysis by numerical simulation and inverse modeling using TOUGH2/ITOUGH2 was used to simulate the flow tests. A single-continuum three-dimensional numerical grid with ~11,000 grid blocks was constructed to model the fault and the surrounding formation. The fault is modeled as a discrete feature with permeability 5 x 10-11 m2, while matrix permeabilities are 200 or more times smaller. Capillary pressure parameters for the van Genuchten model were derived from core data from nearby boreholes. Because of the sensitivity of moisture in the PTn to ventilation effects, the initial conditions for the test bed were established by mimicking the construction history of Alcove 4, including the construction of the slot in summer 1998. The alcove and slot 50% relative humidity boundary conditions are modeled using the Kelvin equation.

plugging of flow paths in the fault decreases fault permeability remains to be tested in the laboratory. If the hypothesis is confirmed, the flow properties of the PTn may change with time as water content and water chemistry evolve due to repository heating or climate variation.

RELATED PUBLICATIONS

Salve, R., and C. Oldenburg, Water flow within a fault in altered nonwelded tuff, Water Resour. Res., submitted.

ACCOMPLISHMENTS

Simulation of the in situ flow tests showed that matrix imbibition alone was unable to account for the observed gradual decline in flow rate. Adding a time-dependent permeability function to model hypothetical effects of water on clay in the fault and fitting parameters to this function using ITOUGH2 resulted in a close fit to the data, as shown in Figure 1. Note in Figure 1 that the short-term intake rate declines are due to imbibition effects, whereas the longer timescale decline is due to permeability decrease associated with clay swelling or clay disaggregation and subsequent plugging of flow paths.

ACKNOWLEDGEMENTS

This work was supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memorandum Purchase Order EA9013MC5X between TRW Environmental Safety Systems, Inc., and Ernest Orlando Lawrence Berkeley National Laboratory for the Yucca Mountain Site Characterization Project under Contract No. DE-AC03-76SF00098.

SIGNIFICANCE OF FINDINGS

The hypothesis that clay swelling or disaggregation and subsequent

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Earth Sciences Division Berkeley Lab

SEEPAGE

INTO

Nuclear Waste Program

UNDERGROUND CAVITIES: FIELD EXPERIMENTS

Annual Report 1999 - 2000

Robert C. Trautz and Joseph S.Y. Wang

Contact: Robert C. Trautz, 510/486-7954, rctrautz@lbl.gov

RESEARCH OBJECTIVES

Water introduced at the land surface during a precipitation event, assuming it migrates through the unsaturated fractured rock to the potential nuclear waste repository beneath Yucca Mountain, Nevada, may potentially enter the more than 100 km of waste emplacement drifts. Over time, seepage water may contact the waste canisters, hasten corrosion (increasing the probability of canister failure), and potentially result in radionuclide migration beyond the canister environment. Because seepage can impact repository performance, it is important to study flow mechanisms and processes that influence seepage.

(a)

APPROACH

Figure 1. (a) Asymmetrical distribution of dye in fractures observed in the Tptpmn. (b) Symmetrical distribution of dye in lithophysae observed in the Tptpll.

Liquid-release tests were performed at several sites located in the Exploratory Studies Facility at Yucca Mountain to investigate seepage processes. A fixed volume of water containing dye was released at a constant rate into selected boreholes. A short drift was then excavated at each site using mechanical methods and employing as little construction water as practical to prevent the dyes from washing away during construction. Dye-stained fractures, rock matrix and natural cavities called lithophysae were mapped during construction to document the flow path traveled by the water.

lithophysae (macropores) rather than the smaller fractures where capillary-driven flow will dominate at lower saturations, as evidenced by the symmetrical pattern of dyes. Should this be the case, a multi-continuum model that incorporates the macropores, fracture network and rock matrix may be needed to adequately represent the flow of water, water vapor and air through the Tptpll.

ACCOMPLISHMENTS

Liquid-release tests were performed at five sites in two zones within the Topopah Spring Tuff (Tpt), the host rock for the proposed repository. Four of the sites are located in the middle nonlithophysal zone (Tptpmn), a densely welded, fractured zone containing few lithophysae. The fifth site is in the lower lithophysal zone (Tptpll), containing abundant lithophysae, providing ample opportunity to observe seepage into cavities as large as 0.5 m in diameter. Dye was observed along individual fractures and fracture networks to a maximum depth of 2.57 m below the release points in the Tptpmn. The dye pattern tended to be asymmetrical, showing a strong downward component of flow (Figure 1a). In contrast, dye was observed in fractures and lithophysae to a maximum depth of 1.37 m in the Tptpll. The dye patterns are more symmetric, with the lateral edges of the wetted area lying about equal distance from the release point (Figure 1b).

RELATED PUBLICATIONS

Finsterle, S., and R.C. Trautz, Drift seepage in unsaturated fractured rock, American Geophysical Union 1999 Fall Meeting, San Francisco, Calif., Dec. 13-17, 1999. Trautz, R.C., and J.S.Y. Wang, Evaluation of seep-age into an underground opening using small-scale field experiments, Yucca Mountain, Nevada, 2000 SME Annual Meeting & Exhibit, Salt Lake City, Utah, Feb. 28â&#x20AC;&#x201C;March 1, 2000.

SIGNIFICANCE OF FINDINGS

The dye patterns suggest that flow through fractures in the Tptpmn is predominately gravity-driven. In contrast, the symmetry of the dye patterns observed in the Tptpll suggests that capillary forces may be more important in this zone. Dye was observed on the walls, ceiling and floor of numerous lithophysae in the Tptpll. There was no evidence, however, that water accumulated and dripped into the cavities even though the liquid-release fluxes applied during the test were 1,000 times greater than the natural flux, estimated at 10 mm/yr. It is surprising that capillary forces appear to be stronger in the Tptpll because the average air permeability of the Tptpll is greater than the Tptpmn. Typically, capillary forces are less important in higher permeability media than in lower permeability materials. This may indicate that the air permeability measurements performed in the Tptpll represent the interconnected

(B)

ACKNOWLEDGEMENTS

45

This work was supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memorandum Purchase Order EA9013MC5X between TRW Environmental Safety Systems, Inc., and Ernest Orlando Lawrence Berkeley National Laboratory for the Yucca Mountain Site Characterization Project under Contract No. DE-AC03-76SF00098. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Nuclear Waste Program

SYSTEMATIC HYDROLOGICAL CHARACTERIZATION OF THE TOPOPAH SPRING LOWER LITHOPHYSAL UNIT

Annual Report 1999 - 2000

Paul Cook, Barry Freifeld, Rohit Salve and Yvonne Tsang

RESEARCH OBJECTIVES

Contact: Yvonne Tsang, 510/486-7047, ytsang @lbl.gov

Field experiments are being carried out in the lower lithophysal unit of the Topopah Springs welded tuff along the underground East-West Cross Drift at Yucca Mountain, Nevada, the potential site of a high level nuclear waste repository. These experiments are to investigate the hydrological properties that are important to repository performance. Parameters being measured are fracture permeability, effective porosity and characteristics of water seepage into the drift.

APPROACH

The lower lithophysal unit has many fractures that are less than 1 meter in length, and lithophysal cavities ranging in size from 15 to 100 cm abound. The cavity size and spacing vary significantly along the 5-meter drift walls within the same lower lithophysal unit, indicating that hydrological characteristics at one parFigure 1. Equipment system for hydrological characterization in the Exploratory Studies Facility. ticular location are not likely representative of the entire lower lithophysal unit. Therefore, systematic testing at regular intervals along the drift is needed to gain an understanding not only of the hydrological characteristics but also the associated heterogeneities of this unit. ACCOMPLISHMENTS Field tests are being carried out in 20-m-long boreholes that are drilled at 30meter regular intervals from the crown of the East-West Cross Drift, parallel We are in the first month of data collection in the first borehole. Air injection data indicate that to and inclined at a low angle (~15°) from the drift axis. Each borehole is typthe fracture permeability is on the order of 1.5 to ically installed with a packer string consisting of three 3-m-long inflatable 2.5 x 10â&#x20AC;&#x201C;11 m2. The liquid injection test needs to packers that isolate the borehole into three 2-m-long injection zones. Tests run around the clock and over a period of weeks, performed in each borehole interval involve air injection and liquid release. while the Cross Drift is only opened during the The fracture permeability is estimated by pressure responses to air injected day shift four days per week. The control of the into the borehole. Collection trays installed along the Cross Drift monitor entire equipment system, test protocol and data the rate at which water seeps into the Cross Drift following liquid releases evaluation is being conducted remotely from into the 2-m-long zone. Gas tracer tests to measure fracture porosity are carBerkeley. ried out in pairs (separated by 3 meters) of parallel, horizontal boreholes drilled from the sidewall of the drift, systematically at 90-meter intervals. ACKNOWLEDGEMENTS The equipment system for all testing is assembled on two mobile This work was supported by the Director, flatbed rail cars as shown in Figure 1. In the foreground of photograph, on Office of Civilian Radioactive Waste the first flatbed, the rack housing the computer, data acquisition system and Management, U.S. Department of Energy, power supplies is shown. Pumps and liquid supply systems for the three through Memorandum Purchase Order test zones are on the second flat bed in the center of the photograph. On the EA9013MC5X between TRW Environmental far end of this second flatbed, tubing leading from the drift crown to the Safety Systems, Inc., and Ernest Orlando water supply cylinder marks the position of the collar of the 20-m-long boreLawrence Berkeley National Laboratory for the hole. At the top right corner of the photograph, note the V-shaped curtain Yucca Mountain Site Characterization Project for collection of seepage water and two seepage collection cylinders into under Contract No. DE-AC03-76SF00098. which water from the collection curtain drains.

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Earth Sciences Division Berkeley Lab

MODELING

OF

Nuclear Waste Program

WATER SEEPAGE

INTO AN UNDERGROUND Stefan Finsterle and Robert C. Trautz

Contact: Stefan Finsterle, 510/486-5205, safinsterle@lbl.gov

RESEARCH OBJECTIVES

Seepage of liquid water into underground openings such as a waste emplacement drift is a key factor affecting the performance of the potential nuclear-waste repository at Yucca Mountain, Nevada. The prediction of drift seepage relies on capturing the relevant flow processes in an unsaturated fracture network as well as accurately representing the conditions encountered at the drift surface. The objective of this research is to design a modeling strategy for the development, calibration and testing of drift seepage models. The approach is applied to the analysis of liquid-release tests conducted at Yucca Mountain.

OPENING

Annual Report 1999 - 2000

The existence of a seepage threshold and the fact that seepage rates are likely to be smaller than percolation rates as a result of the capillary barrier effect is a result of great significance for the performance of a potential nuclear waste repository at Yucca Mountain.

APPROACH

Sensitivity analyses show that the heterogeneity, permeability and capillary strength of the fractures determine the amount of water seeping into an underground opening. The general modeling approach therefore consisted of the following steps. A geostatistical analysis of permeability data from air-injection tests was performed, providing measures of the smallscale variability and correlation structure. This information was then used to develop a three-dimensional, heterogeneous drift seepage model. The model was calibrated against seepage-relevant data from liquid-release tests, in which water was injected from boreholes and collected as it seeped into the opening. Calibration by inverse modeling is a critical step in the procedure as it provides effective, model-related, seepage-specific flow parameters on the scale of interest. To test the ability of the model to make seepage predictions, Monte Carlo simulations were performed and compared to data from additional liquid-release tests that were not used during calibration.

Figure 1. Saturation distribution during simulation of liquid-release test performed to calibrate three-dimensional, heterogeneous drift seepage model.

ACCOMPLISHMENTS

A high-resolution numerical model was developed (see Figure 1), which captures the relevant physical processes governing seepage into an underground opening excavated from unsaturated fractured rock. It was demonstrated that the estimation of effective flow parameters by conducting and analyzing seepage-relevant experiments is a key step in model development. The calibrated model was able to successfully predict seepage from liquid-release tests with different flow rates. Furthermore, it was demonstrated that the continuum approach can be appropriate for predicting a specific behavior of a complex discrete fracture network system.

RELATED PUBLICATIONS

Finsterle, S., Using the continuum approach to model unsaturated flow in fractured rock, accepted for publication in Water Resour. Res., 2000.

ACKNOWLEDGEMENTS

This work was supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memorandum Purchase Order EA9013MC5X between TRW Environmental Safety Systems, Inc., and Ernest Orlando Lawrence Berkeley National Laboratory for the Yucca Mountain Site Characterization Project under Contract No. DEAC03-76SF00098.

SIGNIFICANCE OF FINDINGS

The approach developed in this research provides the basis for extensive seepage predictions under a variety of conditions. The modeling results support the concept of a seepage threshold, i.e., a percolation flux below which no seepage occurs. The existence of a seepage threshold and the fact that seepage rates are likely to be smaller than percolation rates as a result of the capillary barrier effect is a result of great significance for the performance of a potential nuclear waste repository at Yucca Mountain. 47

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Earth Sciences Division Berkeley Lab

Nuclear Waste Program

SEEPAGE MODEL FOR PERFORMANCE ASSESSMENT

Annual Report 1999 - 2000

Guomin Li and Chin-Fu Tsang

Contact: Guomin Li, 510/495-2202, gmli@lbl.gov

RESEARCH OBJECTIVES

Seepage into drifts in unsaturated tuff is an important issue for the longterm performance of the potential nuclear-waste repository at Yucca Mountain, Nevada. The so-called Seepage Model and the Disturbed Drift Seepage Submodel and their results will be used in performance assessment (PA) to develop a probability distribution of waste seepage into waste emplacement drifts. The primary purpose is to evaluate seepage under various conditions, scenarios and parameter variations, with stochastic representations of hydrological properties, and to evaluate the effects of an alternative drift geometry representing a partially collapsed drift using the Disturbed Drift Seepage Submodel.

APPROACH

Seepage into drifts is evaluated by applying numerical models with stochastic representations of hydrological properties and performing multiple realizations of the permeability field around the drift. The Seepage Model for PA uses the distribution of permeability derived from niche tests in the Exploration Studies Facility (ESF) at Yucca Mountain, to stochastically simulate the 3-D flow of water in the fractured host rock in the vicinity of potential emplacement drifts under ambient conditions. A Disturbed Drift Seepage Submodel is developed to evaluate the impact of partial collapse of a drift on seepage. Figure 1 is a sketch summarizing the modeling cases. The top part of the figure shows a 3-D matrix, spanned by the three parameters, which are most sensitive in affecting drift seepage — namely, fracture continuum permeability kFC, van Genuchten α value and the standard deviation σ in ln kFC, which is a measure of heterogeneity of the permeability field. For each combination of these three parameters, i.e., at each point, seepage model calculations were made for three realizations, using a range of values for percolation flux Qp. The middle part of Figure 1 indicates a study of drift seepage for three alternative permeability spatial correlation lengths, λ. This allows an evaluation of the effect of this parameter. The minimum set of parameters that describe a simple heterogeneous field are the two parameters σ and λ. Thus we investigate how seepage depends on the heterogeneous field. The lower part of Figure 1 shows several scenarios of the Disturbed Drift Seepage Submodel. Based on a review of current information, alternative drift degradation modes are evaluated and four scenarios are identified for seepage model studies as indicated. The lower left part of Figure 1 shows the case when the percolation flux above the drift is episodic rather than at a constant average value, so that all the flux comes within a short period of time, with no flux between such pulses.

Figure 1. Different parameters varied in sensitivity studies on seepage.

cases, the results indicate that average seepage will be larger than the constant flux scenario for the same annual total flux.

SIGNIFICANCE OF FINDINGS

Using a realistic 3-D heterogeneous Seepage Model and Disturbed Drift Seepage Submodel provides quantitative measures of potential seepage for the following issues: (1) alternative correlation length λ values; (2) drift disturbed zone scenario and extended failure scenario; and (3) episodic percolation flux. Such data are essential to evaluate the performance of the potential nuclear waste repository.

RELATED PUBLICATIONS

Tsang, C.F., and G. Li, Seepage model for PA including drift collapse, AMR 0075, MOLNBS-HS-000002 Rev 00J, LBNL, 1999.

ACCOMPLISHMENTS

Results show the impact of various factors on seepage and provide data for PA to develop probability distributions. Generally, seepage is calculated to be larger for smaller kFC, smaller 1/α and larger Qp values. It is moderately sensitive to the van Genuchten parameter, n. The spread of results from the three realizations should give an indication of the geostatistical distribution. In general, the spread is large for larger λ and more limited if λ is much smaller than the drift diameter. The preliminary results for a degraded drift show that the effect of a single rock fall is not significant for seepage, whereas a deeper rock failure in the drift roof increases seepage. For the episodic percolation

ACKNOWLEDGMENTS

48

This work was supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memorandum Purchase Order EA9013MC5X between TRW Environmental Safety Systems, Inc., and Ernest Orlando Lawrence Berkeley National Laboratory for the Yucca Mountain Site Characterization Project under Contract No. DE-AC03-76SF00098.

HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

ANALYSIS

Nuclear Waste Program

OF YUCCA MOUNTAIN PORE-WATER CHEMICAL Jianchun Liu, Eric Sonnenthal and Gudmundur S. Bodvarsson Contact: Jianchun Liu, 510/486-5625, jcliu@lbl.gov

RESEARCH OBJECTIVES

Distribution of chemical constituents in the unsaturated zone (UZ) system of Yucca Mountain, Nevada, depends on many factors, such as hydrological and geochemical processes of surface precipitation, evapotranspiration, the water-fracture-matrix interactions, large-scale mixing via lateral flow and transport, and history of climate changes. This study analyzes the pore-water chemical concentration data and models the transport processes. The model results are then used to calibrate the UZ model, particularly, to refine the bounds on infiltration rates and percolation fluxes to the potential repository.

Although close on average, the infiltration map calibrated by pore-water chemical data indicates less spatial variation and a smoother distribution of infiltration rates than the one without calibration.

APPROACH

Major chemical data used in this study were pore-water chloride (Cl) concentrations and 36Cl/Cl isotopic ratios in pore waters. The sensitivity of these conservative tracers to infiltration rate is well known. These constituents were directly incorporated into a three-dimensional dual-permeability flow model. Chemical transport properties, such as molecular diffusion, mechanical dispersion and radioactive decay were taken into account. The boundary condition of the chemical was given by its surface flux. The flux was determined by the total amount of precipitation reaching the surface and chemical concentrations in the precipitation. The entire flow system was divided into domains based on the distribution of pore-water chemical data, infiltration data and hydrogeological and hydrostructural features. Model calibration proceeded by adjusting the site-scale infiltration map to reach a satisfying agreement between the simulated subsurface chemical distribution and measured chemical data in each region. An analytical solution of convection-diffusion was also applied for qualitative analysis and model validation.

Figure 1. Observed and simulated chloride (Cl) values in the cross drift.

useful for further study of percolation flux, flow pathways and transport time, and can also be important for future integrated repository assessment.

ACCOMPLISHMENTS

The model results of pore-water chemical distribution are compared with the measured data. The results using the calibrated infiltration map are more favorable than those using the one without calibration. The analytical solution was also able to capture major Cl and background 36Cl/Cl trends under conditions of transient Cl input. Although close on average, the infiltration map calibrated by pore-water chemical data indicates less spatial variation and a smoother distribution of infiltration rates than the one without calibration. Figure 1 shows the model results of pore-water Cl concentrations, by both 3-D simulation and analytical solution, against the measured data at the ECRB (Enhanced Characterization of the Repository Block) station. The simulation results using the infiltration map without calibration are also shown in the same figure for comparison.

RELATED PUBLICATIONS

Liu, J., Analysis and modeling of pore-water chemical data, Analysis/Model Report "UZ Models and Flow Models," Section 6.4, MDLNBS-HS-000006, Lawrence Berkeley National Laboratory, 2000.

ACKNOWLEDGEMENTS

This work was supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memorandum Purchase Order EA9013MC5X between TRW Environmental Safety Systems, Inc., and Ernest Orlando Lawrence Berkeley National Laboratory for the Yucca Mountain Site Characterization Project under Contract No. DEAC03-76SF00098.

SIGNIFICANCE OF FINDINGS

The percolation flux at the potential high-level nuclear waste repository is one of the main issues in the UZ study. The long-term performance of the repository is determined in part by the timing of subsurface fluid percolation. Percolation flux strongly depends on the infiltration rates and their spatial and temporal distributions. This refined infiltration data is therefore

DATA

Annual Report 1999 - 2000

49

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Earth Sciences Division Berkeley Lab

ANALYSIS

OF

Nuclear Waste Program

CALCITE DEPOSITION AND INFILTRATION-PERCOLATION IN UNSATURATED FRACTURED TUFFS

FLUX

Annual Report 1999 - 2000

Tianfu Xu, Eric Sonnenthal and Gudmundur Bodvarsson

RESEARCH OBJECTIVES

Contact: Tianfu Xu, 510/486-7057, tianfu_xu@lbl.gov

The percolation flux in the unsaturated zone is an important parameter that must be addressed in site characterization and hydrological modeling of the potential Yucca Mountain, Nevada, nuclear waste repository. Hydrogenic calcite deposits found in fractures and lithophysal cavities at Yucca Mountain have been used to estimate past percolation fluxes. Calcite precipitation in the unsaturated fractured tuff may be affected by many factors, including infiltration-percolation rate, water and gas chemistry, effective kinetic reaction rate and mineralogy. This process occurs through a complex interplay of fluid flow, chemical transport and reaction processes.

APPROACH

Calcite deposition was analyzed using reactive transport modeling. The code TOUGHREACT (Xu and Pruess, 1998) which was used for the calcite analysis, considers the following essential processes: (1) fracture-matrix interaction for water flow and chemical constituents; (2) gaseous CO2 diffusive transport and partitioning in liquid and gas phases; and (3) kinetics of fluid-rock chemical reactions. The ambient geothermal gradient is considered for geochemistry calculations. A number of simulations were performed using a range of variables that affect calcite precipitation.

Figure 1. Simulated changes of calcite volume fraction (in ppmV, lines) after 10 million years in the WT-24 column together with measured mass abundances (in diamond symbols) that are taken from the report Analysis of Geochemical Data (USGS data reported in AMR U0085, 2000).

RESULTS AND SIGNIFICANCE

Calcite abundances measured by the USGS (AMR U0085, 2000) were used as a basis for comparison and calibration to model results. Calcite distribution observed in borehole WT-24 were reasonably reproduced using a range of 2-20 mm/yr infiltration rate and modified reactive surface areas. This range of infiltration rate at this location is consistent with that calculated by USGS from infiltration modeling. The model presented is being used to further investigate processes for seepage in cavities that have been used as an analog for seepage into the potential repository waste emplacement drifts.

ACKNOWLEDGEMENTS

RELATED PUBLICATIONS

Fabryka-Martin, J., A. Meijer, B. Marshall, L. Neymark, J. Paces, J. Whelan, and A. Yang, Analysis of geochemical data for the Unsaturated Zone, ANL-NBS-HS-000017 Rev00., Las Vegas, Nev., CRWMS M&O, 2000. Wu, Y.-S., J. Liu, T. Xu, C. Haukwa, W. Zhang, H.H. Liu, and C.F. Ahlers, UZ Flow models and submodels, MDL-NBS-HS-000006 Rev00., Las Vegas, Nev., CRWMS M&O, 2000. Xu, T., and K. Pruess, Coupled modeling of non-isothermal multi-phase flow, solute transport and reactive chemistry in porous and fractured media: 1. Model Development and Validation, LBNL-42050, 1998.

This work was supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memor-andum Purchase Order EA9013MC5X between TRW Environmental Safety Systems, Inc., and Ernest Orlando Lawrence Berkeley National Laboratory for the Yucca Mountain Site Characterization Project under Contract No. DE-AC03-76SF00098.

50

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Earth Sciences Division Berkeley Lab

Nuclear Waste Program

UNSATURATED ZONE PROCESS MODEL FOR YUCCA MOUNTAIN, NEVADA

Annual Report 1999 - 2000

Gudmundur S. Bodvarsson

Gudmundur S. Bodvarsson, 510/486-4789, gsbodvarsson@lbl.gov

RESEARCH OBJECTIVES

The Department of Energy is evaluating Yucca Mountain, Nevada, for the development of a potential geological repository for the permanent disposal of the nation’s commercial and defense spent nuclear fuel and highlevel radioactive waste. This evaluation includes analyses of the ability of the natural geologic and engineered barrier systems of this potential repository to prevent the migration of radionuclides to the accessible environment. The primary pathway has been determined to be via the groundwater aquifer below the potential repository.

APPROACH

The Unsaturated Zone (UZ) Process Model Report (PMR) describes the modeling, analysis and current understanding of fluid flow and chemical (solute and colloidal) transport through the UZ at Yucca Mountain. The primary purpose of the UZ PMR is to document models and analyses for Total System Performance Assessment (TSPA) that evaluate the post-closure performance of the UZ. The models in the UZ PMR consider two principal factors: seepage into drifts and radionuclide retardation in the UZ. Seven other factors are also considered, including: climate, net infiltration into the mountain, UZ flow above the repository, coupled processes-effects on UZ flow, advective pathways in the UZ, colloid-facilitated transport in the UZ and coupled processes-effects on UZ transport. Most of the models in the UZ PMR are based on continuum approximations and employ the dual-permeability approach with van Genuchten equations to describe characteristic curves of both the fracture and matrix continua. The models are supported by site data collected since the early 1980s and the results of field testing in boreholes and underground drifts. Figure 1 shows some of the key models contained in the UZ PMR.

Figure 1. Process models included in the Unsaturated Zone Process Model Report.

from the potential repository footprint, with estimated temperature increases of 30 to 35ºC at the water table, and up to 5ºC at the ground surface.

SIGNIFICANCE OF FINDINGS

The UZ PMR process models are abstracted for use in TSPA. The degree of abstraction of these models varies from direct use of the process model in TSPA to using the model to justify neglecting certain processes. In the development of the process models, the uncertainties in parameters, processes, and conceptual models are identified and qualified where possible; TSPA then evaluates the importance of these uncertainties on the performance of the potential repository.

ACCOMPLISHMENTS

The major hydrogeologic units identified at Yucca Mountain are, from land surface to water table: Tiva Canyon welded unit (TCw), Paintbrush nonwelded unit (PTn), Topopah Spring welded unit (TSw), Calico Hills nonwelded unit (CHn), and Crater Flat undifferentiated unit (CFu). They are partially saturated with water. The potential repository will reside at a depth ranging from 200 to 425 m below ground surface, and from 175 to 365 m above the water table, in three geological units within the TSw. More than 80% of water flow at the repository horizon is through fractures, while the remainder flows through the low permeability (10-16 to 10-18 m2) rock matrix. Below the horizon, perched water bodies have been found primarily in the northern part of the repository area, where low-permeability zeolitic rock units are abundant. The presence of the perched water bodies creates the potential for the lateral flow of water to nearby highpermeability vertical features, such as faults. The rate of water seepage into drifts is expected to be considerably less than the prevailing percolation flux and may be zero for areas where the percolation flux is lower than the seepage threshold for that location. This is because the drifts act as capillary barriers which divert most of the flowing water around the drifts. As the radioactive waste emits heat, coupled thermal-hydrological-chemical processes in the UZ rock mass may be important for periods of up to about 10,000 years. The energy emitted will heat up the entire UZ, extending 600 m

ACKNOWLEDGEMENTS

51

This work was supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memorandum Purchase Order EA9013MC5X between TRW Environmental Safety Systems, Inc., and Ernest Orlando Lawrence Berkeley National Laboratory for the Yucca Mountain Site Characterization Project under Contract No. DE-AC03-76SF00098. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Nuclear Waste Program

CHARACTERIZING FLOW AND TRANSPORT PROCESSES AT YUCCA MOUNTAIN

Annual Report 1999 - 2000

Yu-Shu Wu, Winnie Zhang and Gudmundur S. Bodvarsson Contact: Yu-Shu Wu, 510/486-7291, yswu@lbl.gov

RESEARCH OBJECTIVES

Quantitative characterization of fluid flow and radionuclide transport in the unsaturated zone (UZ) at Yucca Mountain, Nevada, using a numerical model is an essential step for designing the potential repository and assessing its performance. Numerical modeling has played a crucial role in understanding UZ fluid movement and the effects of hydrogeologic, thermal and geochemical conditions on various aspects of the overall waste-disposal system. Whereas laboratory and field experiments are limited in both space and time, numerical modeling provides a means to study physical processes on large temporal and spatial scales relevant to understanding physical processes associated with nuclear waste disposal in a geologic formation. Modeling investigations summarized here were performed for evaluating the current and future conditions of the UZ so as to aid in the assessment of the potentail repositoryâ&#x20AC;&#x2122;s system performance and to estimate groundwater travel and radionuclide transport times

Whereas laboratory and field experiments are limited in both space and time, numerical modeling provides a means to study physical processes on large temporal and spatial scales relevant to understanding physical processes associated with nuclear waste disposal in a geologic formation. total percolation fluxes increases as mean infiltration rates increase. Tracer-transport studies indicate that there exists a wide range of radionuclide transport times using different infiltration rates, types of radionuclides and perched water conceptual models. Infiltration rates and adsorption effects in the CHn unit were found to be the most important factors for estimated transport times.

APPROACH

The methodology used in developing the characterization studies includes (1) design of a 3-D numerical grid that properly represents complicated geological features of Yucca Mountain; (2) model calibrations against field data; and (3) flow and transport simulation studies using different infiltration rates and hydrogeological conceptual models. The modeling approach in the UZ flow and transport model is based on a continuum mathematical formulation of coupled multiphase fluid and tracer transport through fractured porous rock with the TOUGH2 code. The flow and transport processes in the fractured porous rock are handled using a dual-continuum concept.

SIGNIFICANCE OF FINDINGS

The site-characterization efforts produced more than 30, 3-D steady-state flow fields, 18 of which have been directly used in the TSPA-SR analyses. In addition, the model results provide input to various other models, such as ambient and thermal drift-scale models, the mountainscale thermohydrological model and the UZ transport model used for LA.

ACCOMPLISHMENTS

A series of model calibrations and sensitivity analyses were conducted with the UZ flow and transport model to investigate the effects of variations in rock properties and in model boundary conditions, using different perched water conceptual models and different climate conditions. These model-calibration efforts conclude that the model can reproduce moisture conditions in the UZ system of Yucca Mountain. The model has been used to (1) integrate the available data from the UZ system into a single, comprehensive and calibrated 3-D model for simulating the ambient hydrological, thermal and geochemical conditions for use in predicting system response to future climate conditions; (2) quantify the moisture flow through the UZ, under present-day and estimated future climate scenarios; and (3) calculate times of radionuclide transport from the repository level to the water table. Model results indicate that repository-level percolation fluxes largely reflect surface infiltration patterns. These percolation fluxes and their distributions show little large-scale lateral flow or diversion by the PTn unit and flow focusing into faults in the vicinity of the potential repository. Fracture flow is predicted to be dominant in the welded tuffs. Significant lateral flow diversion is predicted to occur at the CHn, resulting from the presence of perched water or thick low-permeability zeolitic layers. Faults act as major flow paths through the CHn unit and the percentage of fault flow versus

RELATED PUBLICATIONS

Wu, Y.S., C. Haukwa and G.S. Bodvarsson, A site-scale model for fluid and heat flow in the unsaturated zone of Yucca Mountain, Nevada, Journal of Contaminant Hydrology, 38 (1-3), pp.185-217, 1999.

ACKNOWLEDGEMENTS

52

This work was supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memorandum Purchase Order EA9013MC5X between TRW Environmental Safety Systems, Inc., and Ernest Orlando Lawrence Berkeley National Laboratory for the Yucca Mountain Site Characterization Project under Contract No. DE-AC03-76SF00098. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Annual Report 1999 - 2000

Nuclear Waste Program

MODELING FLOW AND TRANSPORT

IN

UNSATURATED FRACTURED POROUS MEDIA

Hui Hai Liu, Charles Haukwa, Rick Ahlers and Gudmundur S. Bodvarsson Contact: Hui Hai Liu, 510/486-6452, hhliu@lbl.gov

RESEARCH OBJECTIVES

Modeling flow and transport in unsaturated fractured rocks is of interest in many areas, including geological disposal of nuclear wastes and subsurface contaminant transport. Because the continuum modeling approach is relatively simple and straightforward to implement, it is preferred for most applications that are encountered in practice. However, its usefulness for representing gravity-driven fingering flow and transport in unsaturated fractured rocks has often been questioned. The main objective of this study is to evaluate the continuum approach based on a combination of model calibration and prediction.

APPROACH

Data from an infiltration and tracer transport test carried out in a densely fractured rock were used in this study. The active fracture model was employed to handle the fingering flow and transport, and the MINC and an analytical approach used to capture the transient flow and transport between fractures and the matrix. The corresponding numerical model, calibrated with seepage data obtained from the early stage of the infiltration test, was used to predicate seepage rates at the late stage. The model was further calibrated with all the seepage data and then employed to predict observed tracer transport results. The simulation results and the data were compared to evaluate the usefulness and limitations of the continuum approach.

Figure 1. Comparison between the observed tracer concentrations and modeling results for different matrix tortuosities.

RELATED PUBLICATIONS

Liu, H.H., C. Doughty and G.S. Bodvarsson, An active fracture model for unsaturated flow and transport in fractured rocks, Water Resources Research, 29 (12), 2633-2646, 1998. Liu, H.H., C.B. Haukwa, R. Ahlers and G.S. Bodvarsson, Modeling flow and transport in unsaturated fractured rocks: An evaluation of the continuum approach, Water Resources Research, in review.

ACCOMPLISHMENTS

While more theoretical, numerical and experimental studies are needed to provide a more conclusive evaluation, the comparison between the simulated and observed results suggests that the continuum approach is practically valid for modeling flow and transport in the unsaturated fractured rocks. It was also found that the use of the active fracture model can approximately handle the average behavior of fingering flow and transport, and the matrix diffusion has a significant effect on the transport process in unsaturated fractured rocks.

ACKNOWLEDGEMENTS

This work was supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memorandum Purchase Order EA9013MC5X between TRW Environmental Safety Systems, Inc., and Ernest Orlando Lawrence Berkeley National Laboratory for the Yucca Mountain Site Characterization Project under Contract No. DEAC03-76SF00098.

SIGNIFICANCE OF FINDINGS

The continuum approach is commonly used for modeling complex flow and transport processes in unsaturated fractured rocks. This study reports a unique evaluation of this approach using field observations directly related to flow and transport. The positive evaluation results provide further confidence for the use of the continuum approach in modeling flow and transport in the unsaturated zone of Yucca Mountain, Nevada, potential site of a high-level nuclear waste repository.

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Earth Sciences Division Berkeley Lab

Nuclear Waste Program

RADIOACTIVE TRANSPORT MODELING

Annual Report 1999 - 2000

George J. Moridis and Qinhong Hu

Contact: George J. Moridis, 510/486-4746, gjmoridis@lbl.gov

RESEARCH OBJECTIVES

The U.S. Department of Energy is actively investigating the technical feasibility of the permanent disposal of high-level nuclear waste in an appropriate repository to be situated in the unsaturated zone (UZ) at Yucca Mountain (YM), Nevada. The objectives of this study are to (a) evaluate the transport of radioactive solutes and colloids under ambient conditions from the potential repository horizon to the water table; (b) document the UZ Radionuclide Transport Model (RTM); and (c) determine processes and geohydrologic features that significantly affect radionuclide transport.

The most important factors affecting radionuclide transport are the subsurface geology and site hydrology, the presence of faults, fractures, and the relative distribution of zeolitic and vitric tuffs.

APPROACH

The RTM considers the site hydrology and the effects of the spatial distribution of hydraulic and transport properties in the YM subsurface. The migration and retardation of radionuclides are analyzed using the EOS9nT numerical code (Moridis et al., 1999) and the FRACL semianalytical code (Moridis and Bodvarsson, 1999). These codes account for the complex processes in the YM subsurface, and include advection, diffusion, hydrodynamic dispersion, kinetic or equilibrium physical and/or chemical sorption (linear, Langmuir, Freundlich or combined), first-order linear chemical reactions, radioactive decay and tracking of daughters, colloid straining, colloid physical-chemical filtration (equilibrium, kinetic or combined), and colloidassisted solute transport.

RESULTS AND SIGNIFICANCE

The most important factors affecting radionuclide transport are the subsurface geology and site hydrology (Figure 1), i.e., the presence of faults (they dominate and control transport), fractures (the main migration pathways), and the relative distribution of zeolitic and vitric tuffs (CRWMS M&O, 2000). Diffusion from the fractures into, and subsequent sorption onto the matrix are the main retardation processes. Arrival times at the watertable increase with the sorption distribution coefficients of the various species, and may have to account for contributions from the decay daughters of certain radionuclides. Changes in future climatic conditions can have a significant effect on transport, as increasing infiltration leads to faster transport to the water table. The transport of colloids is strongly influenced by their size (as it affects diffusion into the matrix, straining at hydrogeologic unit interfaces and transport velocity) and by the parameters used in the kinetic filtration model. Different conceptual models of perched water at the site appear to have little effect on transport.

Figure 1. Relative concentration of the nonsorbing 99Tc in the fractures of the tsw39 layer below the potential repository at t=100 years of continuous release (CRWMS M&O, 2000). The importance of faults is evident.

ACKNOWLEDGEMENT

RELATED PUBLICATIONS

Moridis, G., and Q. Hu, Radionuclide transport models under ambient conditions, MDL-NBS-HS-000008, Las Vegas, Nev., CRWMS M&O, 2000. Moridis, G.J., and G.S. Bodvarsson, Semianalytical solutions of radioactive or reactive tracer transport in layered fractured media, Berkeley Lab Report LBNL-44155, 1999. Moridis, G.J., Y.S. Wu and K. Pruess, EOS9nT: A TOUGH2 module for the simulation of water flow and solute/colloid transport in the subsurface, Berkeley Lab Report LBNL-42351, 1999.

54

This work was supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memorandum Purchase Order EA9013MC5X between TRW Environmental Safety Systems and the Ernest Orlando Lawrence Berkeley National Laboratory under U.S. Department of Energy Contract No. DE-AC03-76SF00098. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

DEVELOPMENT

OF

Annual Report 1999 - 2000

Nuclear Waste Program

BOREHOLE GPR TECHNIQUES

TO

MONITOR MOISTURE REDISTRIBUTION

Kenneth H. Williams, John E. Peterson and Ernest L. Majer Contact: Kenneth H. Williams, 510/486-6775, khwillliams@lbl.gov

RESEARCH OBJECTIVES

Borehole Ground Penetrating Radar (GPR) tomography provides a high-resolution technique with which to characterize the temporal and spatial changes associated with fluid flow and moisture redistribution in the subsurface. Efforts are underway to streamline both the acquisition and processing of GPR data in order to provide realtime monitoring of a variety of changing fluid flow regimes.

APPROACH

In the borehole GPR method, modified surface radar antennas are emplaced into a rock formation and high-frequency electromagnetic signals are transmitted through the formation to a receiving antenna. The dielectric permittivity of the rock has a strong influence on the propagation of the signal and whether it travels at a high or low velocity. Moisture content affects dielectric permittivity and hence has such an effect. The high dielectric permittiv- Figure 1. Borehole GPR tomogram acquired at the Busted Butte experimental site. The image illustrates the change in rock saturation between two boreity (k) of water (k ~ 80) or wet rock (k ~ 20-30) in contrast holes as a result of tracer injection (dark blue colors represent increased satto drier rock (k ~ 3-6) typically results in greatly reduced uration). signal velocities. Because such changes in signal character are what are to be measured over the course of a radar study, any increase the traditional reach of most methods â&#x20AC;&#x201D; that of (or decrease) in background moisture content resulting from the fluid the immediate region of the borehole. Information obtained on moisture redistribution migration (or rock dry-out) should result in measurable changes in the and fluid flow between boreholes allows for data received radar wave velocity. The transmitted signals may be represented as sampling not available through other means. The multiple ray paths crossing through a zone of interest in the subsurface. If GPR tomography method provides an invalusufficient ray paths are recorded, a tomographic image may be obtained able means for verifying the predictions made by through computer processing. hydrologic models. In this way, this technique ACCOMPLISHMENTS appears to be quite successful in enhancing our GPR tomography has been undertaken in support of a variety of experunderstanding of fluid flow in the subsurface. iments, including the controlled injection of a fluid tracer into the subsurface RELATED PUBLICATIONS and the thermal activation of a rock mass and the accompanying moisture Y.W. Tsang, J. Apps, J.Birkholzer, J. Peterson, E. redistribution. Both experiments are ongoing and are conducted in support Sonnenthal, N. Spycher and K. Williams, Yucca of the characterization of the potential high-level nuclear waste repository at Mountain drift scale test progress report, Yucca Mountain, Nevada. The results of the GPR tomography indicate that Berkeley Lab report LBNL-42538, 1999. the technique is sufficiently sensitive to detect extremely small changes in moisture content (<2-3%) related to both increasing and decreasing rock satACKNOWLEDGMENTS uration over reasonably large distances (>10m). The technique has provided This work was supported by the Director, a means for delineating the extent of moisture redistribution and for highOffice of Civilian Radioactive Waste Management, lighting specific fluid transport pathways. Such information has been used U.S. Department of Energy, through Memoranto verify hydrologic modeling undertaken in advance to predict fluid flow dum Purchase Order EA9013MC5X between properties. TRW Environmental Safety Systems, Inc., and SIGNIFICANCE OF FINDINGS Ernest Orlando Lawrence Berkeley National Borehole GPR tomography provides a method with which to gather relLaboratory for the Yucca Mountain atively high-resolution estimates of moisture content between two boreSite Characterization Project under holes. The information obtained extends the zone of investigation beyond Contract No. DE-AC03-76SF00098. 55

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Earth Sciences Division Berkeley Lab

MEASURING

THE

Nuclear Waste Program

THERMAL-HYDROLOGICAL PROCESSES

IN THE

Annual Report 1999 - 2000

DRIFT SCALE TEST

Yvonne Tsang, Barry Freifeld and Sumit Mukhopadhyay Contact: Yvonne Tsang, 510/486-7047, ytsang@lbl.gov

RESEARCH OBJECTIVES

Lawrence Berkeley National Laboratory, as part of a multi-laboratory team, is carrying out a large-scale in-situ thermal test, the Drift Scale Test (DST), in an underground facility at Yucca Mountain, Nevada, the potential site for a high-level nuclear waste repository. The heating phase of the DST began in December 1997 and is designed to continue for four years, followed by another four years of cooling. The objective of this test is to gain a more in-depth understanding of the coupled thermal-hydrological-mechanical-chemical processes likely to exist in the fractured rock mass around a geological repository situated above the water table.

APPROACH

The host rock for the DST is densely fractured welded tuff. Permeability in the fractures is orders of magnitude larger than that Figure 1. Permeability (normalized to respective pre-heat values) in the matrix, where pores are about 90% saturated with water. Heat from air-injection into different borehole sections in the DST, at is provided by canister heaters placed in a drift 47.5 meters in length different stages of heating. and 5 meters in diameter, and by 11-meter-long rod heaters installed in boreholes drilled perpendicular to the drift axis, pointing to the north and to the south of the heated drift. Approximately 185 kW is supplied by nine canister heaters and 50 rod heaters. The thermally driven hydrological, chemical and mechanical coupled processes are monitored continuously by SIGNIFICANCE OF FINDINGS thousands of sensors installed in nearly 100 boreholes that encompass a rock block of 60 x 60 x 60 m3. Active testing such as cross-hole radar tomography, A close integration of measurements and simulations carried out in this large-scale and neutron logging, electrical resistivity tomography and air-permeability long-term test has contributed much toward the measurements are also performed at quarterly intervals to measure moisunderstanding of thermally driven coupled ture redistribution with time. Moisture redistribution arises chiefly from processes in a fractured rock in the unsaturated boiling of water near the heat sources, transport of vapor away from the zone. heat source, and its subsequent condensation in cooler rocks. Thermalhydrological processes in the DST have been simulated using a numerical RELATED PUBLICATIONS model that incorporates realistically the 3-D test configuration. The model Birkholzer, J.T., and Y.W. Tsang, Modeling the predictions are compared to the extensive set of measured data. thermal-hydrological processes in a large-scale ACCOMPLISHMENTS underground heater test in partially saturated The main manifestation of coupled thermal-hydrological processes is in fractured tuff, Water Resour. Res 36(6), 1431the time evolution of the drying and condensation zones. Good agreement 1448, 2000. occurred between the model predictions and measurements. Specifically, as ACKNOWLEDGEMENTS heating progresses, expanding zones of reduced liquid saturation in the This work was supported by the Director, rock matrix around the heaters predicted by the simulations are consistent Office of Civilian Radioactive Waste Management, with zones of drying shown in neutron logging data, cross-hole radar tomoU.S. Department of Energy, through grams and electrical resistivity tomography data. Similarly, periodic air perMemorandum Purchase Order EA9013MC5X meability measurements show that in those condensation zones where between TRW Environmental Safety Systems, numerical simulations show enhanced liquid saturation in the fractures, the Inc., and Ernest Orlando Lawrence Berkeley measured fracture permeability to air decreases. Figure 1 shows the measNational Laboratory for the Yucca Mountain Site ured air-permeability in different borehole sections as a function of time. Characterization Project under Contract No. DEThe air-permeability is normalized to the respective pre-heat values in difAC03-76SF00098. ferent borehole sections. 56

HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Nuclear Waste Program

ACOUSTIC EMISSION MONITORING DURING THE DRIFT SCALE TEST AT YUCCA MOUNTAIN, NEVADA

Annual Report 1999 - 2000

John E. Peterson Jr., Kenneth H. Williams and Ernest L. Majer

RESEARCH OBJECTIVES

Contact: John E. Peterson Jr., 510/486-4267, jepeterson@lbl.gov

The Drift Scale Test (DST) is part of the Exploratory Studies Facility (ESF) Thermal Test being conducted underground at the potential high-level nuclear waste repository at Yucca Mountain, Nevada. The purpose of the ESF Thermal Test is to acquire a more in-depth understanding of the coupled thermal, hydrological and chemical processes likely to be encountered in the rock mass surrounding the potential repository. The purpose of the acoustic emission monitoring effort is to quantify and infer changes in rock properties of the material surrounding the drift as the temperature increases. As rock is heated in a confined underground environment, thermal expansion may cause cracking of the rock mass or movement along any pre-existing fractures or joints. Seismic methods have been shown to assist in resolving such alterations.

The purpose of the ESF Thermal Test is to acquire a more in-depth understanding of the coupled thermal, hydrological and chemical processes likely to be encountered in the rock mass surrounding the potential geological repository.

APPROACH

In this work, acoustic emission activity is registered by using 14 accelerometers emplaced radially around the heater drift. Acoustic emission activity is analyzed both spatially and temporally. The location and timing of such changes in activity are expected to correspond to those areas encompassing the thermal testing where physical change or disturbance in the rock mass is occurring. Such areas are to be compared with the results from other tests conducted in support of the DST. Installation of the recording system occurred on Nov. 15, 1997, one month before heating was initiated. The system was initially plagued with noise problems, which deluged the system with false triggers. These problems were solved and the system has been working continuously since January 1999.

ACCOMPLISHMENTS

Figure 1. Locations of all microseismic events occuring between January 1, 1999, and April 6, 2000.

From January 1999 to April 2000, a total of 300 acoustic emission events have been analyzed and located. The microseismic activity appears to have dramatically increased after July 1999, from about five events per month to about 30 events per month for July and September (the system was down in August 1999), and 50 events per month until February 2000. The March 2000 and April 2000 data indicate a decrease in activity back to 5-10 events per month. Some of this activity may be related to the Hector Mine earthquake of October 1999. However, the increase in activity began more than a month before this earthquake occurred. The microseismic activity appears to be clustered within a few meters above the Heater Drift. Figure 1 shows the location of the events as circles, with the size of the circle indicating the magnitude relative to the magnitude of a sledgehammer hit to the side of the drift. The largest cluster of events occurred at about Y = 9 to 10 m. The area above the tunnel is naturally under stress due to geometry of the tunnel itself. It is also the area which may have the largest change in saturation due to increased temperature and draining of fractures and voids. The location of the acoustic emission events also agrees with measurements of mechanical displacement, which indicate larger displacements occurring at the top of the tunnel.

SIGNIFICANCE OF FINDINGS

Acoustic emissions provide spatial and temporal information about stress changes due to temperature increases. This work has provided data suggesting that the increase in temperature has a significant effect on the rock, especially above the drift.

ACKNOWLEDGEMENTS

57

This work was supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memorandum Purchase Order EA9013MC5X between TRW Environmental Safety Systems, Inc., and Ernest Orlando Lawrence Berkeley National Laboratory for the Yucca Mountain Site Characterization Project under Contract No. DE-AC03-76SF00098. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Nuclear Waste Program

WATER CHEMISTRY AND ROCK PERMEABILITY CHANGES AROUND NUCLEAR WASTE EMPLACEMENT TUNNELS

Annual Report 1999 - 2000

Nicolas Spycher and Eric Sonnenthal

RESEARCH OBJECTIVES

Contact: Nicolas Spycher, 510/495-2388, nspycher@lbl.gov

This project investigated coupled thermal, hydrological and chemical processes that could take place around waste-emplacement tunnels (drifts) at the potential high-level nuclear waste repository at Yucca Mountain, Nevada. In the unsaturated fractured volcanic tuffs around emplacement drifts, water is held mostly in the rock matrix pores. Upon heating, due to waste decay, water boils and travels as vapor in fractures. In cooler regions, it condenses and may drain back towards the boiling zone. This continuous boiling and refluxing of water, together with percolating rain water, may cause mineral precipitation and dissolution. An objective of this study was to evaluate to what extent such processes would alter rock permeability and water flow around drifts. Another objective was to predict the composition of water and gas that may enter the drifts.

APPROACH

Numerical simulations were performed using a modified version of the TOUGHREACT code developed at LBNL by T. Xu and K. Pruess. The model considers water, vapor, air and heat transport; reactive gas, mineral and aqueous phases; porosity-permeability-capillary pressure coupling; and dual permeability (fractures and rock matrix). A 2-D vertical and symmetrical half-drift model was developed that incorporated water chemistry and hydrogeologic data from field studies. The heat load due to waste package decay was imposed inside the drift.

ACCOMPLISHMENTS

Simulations were conducted over a 100,000-year time period, including possible climate changes, and two geochemical systems. Maximum dryout was predicted to occur approximately 600 years after waste emplacement, and, depending on the infiltration rate, extended to a radius of 10 to 25 m around the drift. Rewetting at the drift crown, due to meteoric water infiltration, was predicted to occur after 1,000 to 2,000 years, with return to ambient temperatures within 50,000 to 100,000 years. Calculated water and gas compositions varied depending on infiltration rates and the geochemical system considered. During rewetting at the drift crown, predicted pH in fracture water for various cases varied between 7.2 and 9.8. The water salinity typically remained less than 1,000 ppm. Calculated porosity changes around the drift due to mineral precipitation and dissolution were found to be negligible (< 0.1 %) for all infiltration rates considered, with more mineral precipitation occurring than dissolution after 10,000 years (Figure 1).

Figure 1. Modeled total fracture porosity change at 10,000 years (mean infiltration case). Blue areas show zones of maximum mineral precipitation (primarily calcite and zeolites). Temperature contours are superposed.

RELATED PUBLICATIONS

Sonnenthal, E.L., and N.F. Spycher, Drift-scale coupled processes (DST and THC seepage) models, Analysis/Model Report N0120/U0110, MDLNBS-000001, Lawrence Berkeley National Laboratory, Berkeley, Calif., 2000.

ACKNOWLEDGEMENTS

SIGNIFICANCE OF FINDINGS

The small calculated porosity change is predicted to have essentially no effect on the rock permeability around drifts. This conclusion differs from results of more simple modeling and experimental studies predicting possible sealing from mineral precipitation around waste emplacement drifts. The predicted water composition is of low salinity and near neutral to alkaline pH, a finding that is favorable for the performance of waste canisters and other in-drift engineered systems. More work is underway to reduce the uncertainty of the model and evaluate how this uncertainty affects the conclusions drawn from the model results.

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This work was supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memorandum Purchase Order EA9013MC5X between TRW Environmental Safety Systems, Inc., and Ernest Orlando Lawrence Berkeley National Laboratory for the Yucca Mountain Site Characterization Project under Contract No. DE-AC03-76SF00098. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

MINERAL PRECIPITATION

IN AN

Annual Report 1999 - 2000

Nuclear Waste Program

UNSATURATED TUFF FRACTURE – PERMEABILITY EFFECTS Timothy J. Kneafsey

Contact: Timothy J. Kneafsey, 510/486-4414, tjkneafsey@lbl.gov

RESEARCH OBJECTIVES

Upon the emplacement of heat-generating nuclear waste in the potential nuclear waste repository at Yucca Mountain, Nevada, water naturally present in the rock will begin to boil and will be transported in the open fractures. When this water vapor reaches cooler rock, it will condense and may begin to flow. This condensate will not be in chemical equilibrium with the surrounding rock; therefore it will begin to dissolve a portion of the rock it contacts. If it flows towards the hot nuclear waste and boils again, it will deposit the dissolved constituents in the fracture, reducing the fracture permeability. Upon boiling, the cycle will begin again. The objective of this research is to experimentally investigate tuff dissolution and mineral precipitation under similar conditions.

APPROACH

Figure 1. White precipitate bands in the near-boiling region.

An experiment was designed guided by numerical simulations. Water was equilibrated with carbon dioxide at levels comparable to those measured near the Drift-Scale Test, a large heated experiment at Yucca Mountain. It was then run through crushed tuff maintained at 95°C to simulate condensation and mineral dissolution. Water samples were analyzed to provide a data set for tuff dissolution at near-boiling temperatures. The water was then introduced into a book-sized tuff fracture made from two flat tuff slabs separated by about 20 microns which was heated to 130°C at the bottom. The permeability of the fracture was monitored for changes. The narrow fracture sealed in about 10 days. After the fracture clogged, it was opened and inspected to determine the physical and mineralogical structure of the precipitated solids.

dicted the effects of precipitation. This study provides an understanding of the processes of tuff dissolution in a water-saturated environment, and mineral precipitation in an unsaturated fracture. This study also provides insight towards the physical structure of the precipitate in relation to the structure of the fracture, which is crucial to understanding the effects on permeability and flow in the fracture.

ACCOMPLISHMENTS

RELATED PUBLICATIONS

The experiment has been completed and data analysis is ongoing. The primary constituents in the water leaving the crushed tuff were silica, sodium, carbonate and potassium. The pH, initially acidic due to dissolved carbon dioxide, ranged from 9.2 to 8.2. Solids precipitated in the fracture at temperatures from below boiling to 130°C. Only a few small regions of precipitate were observed in the below-boiling region. In the region near 100°C, mineral precipitation occurred nonuniformly in narrow bands which span the aperture and block flow (Figure 1), and in a glaze over part of the fracture wall. In regions near 130°C, the precipitate formed very porous honeycomb structures. The mineralogy of the precipitate with respect to the fracture location is currently being evaluated.

Kneafsey, T.J., and K. Pruess, Laboratory experiments on heat-driven two-phase flows in natural and artificial rock fractures, Water Resources Research, 34, pp. 3349 - 3367, 1998.

ACKNOWLEDGEMENTS

This work was supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memorandum Purchase Order EA9013MC5X between TRW Environmental Safety Systems, Inc., and Ernest Orlando Lawrence Berkeley National Laboratory for the Yucca Mountain Site Characterization Project under Contract No. DEAC03-76SF00098. Careful review of this paper by Nicholas Spycher is greatly appreciated.

SIGNIFICANCE OF FINDINGS

Mineral precipitation in fractures is important for both nuclear waste disposal and geothermal reservoir engineering. Experiments have been performed in water-saturated systems, and many numerical studies have pre-

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HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Nuclear Waste Program

THERMAL LOADING STUDIES USING

THE

UNSATURATED ZONE MODEL

Annual Report 1999 - 2000

Charles Haukwa, Yu-Shu Wu and Gudmundur S. Bodvarsson Contact: Charles Haukwa, 510/486-2933, cbhaukwa@lbl.gov

OBJECTIVES

The purpose of this study was to develop a thermo-hydrological (TH) model of the unsaturated zone (UZ) at Yucca Mountain, Nevada, that can be used to evaluate the performance of the potential nuclear waste repository. The numerical model provides a prediction of: (1) temperatures over the mountain and the size of the two-phase zone; (2) the evolution of moisture and gas distribution; (3) the effects of heat on liquid and gas flow; (4) the potential for temperature-induced property changes; and (5) the effects of heat on perched water.

APPROACH

The model uses a 2-D north-south cross-section grid, based on the FY2000 UZ 3-D Flow and Transport Model, and employs the dual-continuum formulation with the active fracture model. The initial thermal load is 72.7 kW/acre. We allow for natural decay of the heat source, and pre-closure ventilation reduces the heat load by 70% during the first 50 years. The numerical grid allows the heat source to be applied at the discrete drift locations at the potential repository. The simulations of coupled heat and mass flow were conducted using TOUGH2 (EOS3 module) over a simulated period of 100,000 years.

Figure 1. Predicted temperature distribution.

SIGNIFICANCE OF FINDINGS

The study demonstrates that TH processes associated with thermal loading of a repository in fractured unsaturated tuffs can be modeled using the dual-continuum approach, using the active fracture model concept. The model provides a prediction of a thermally affected zone and a map of the evolution of liquid and gas flux, temperature and liquid distribution in the mountain over a period of thousands of years. Such a model can serve as a predictive tool for assessment of alternative designs of the potential repository.

RESULTS

The model predicts hot and dry conditions within the fractures close to drifts that last for hundreds of years, even with ventilation. Other modeling results include the following: • Large temperature changes are predicted only directly above and below the repository (Figure 1). The temperature changes result in a two-phase zone that extends 20 m above the repository. Laterally, the thermally affected zone extends no more than 50 m from the repository. • Completely dry matrix conditions are predicted at several locations. The dry-out zones are confined to within 10 m of the repository drifts and may last 1,000 years. • Temperatures at the drifts are predicted to rise to boiling conditions (97°C) except in the low infiltration areas, where temperatures may rise to over 110°C. Temperatures between the drifts are predicted to rise to a maximum of 80-85°C after 1,000 years. • The predicted maximum temperature is 70-75°C on top of the CHn (910 m), 65-70°C at the water table (730 m), and 40-45°C in the PTn (1300 m) after 5,000 years. The model predicts little potential for temperatureinduced property changes in both the CHn and PTn. • Enhanced liquid flux is only predicted close to the repository, where there is substantial drying of the matrix and fracture continua. The maximum fracture liquid flux towards the drifts is 300 mm/year after 10 years, but is all vaporized by repository heat. Liquid flow adjacent to the drifts may be enhanced by drainage of condensate. • There is little potential for vaporization and mobilization of the perched water, except when the bodies are located close to the repository.

RELATED PUBLICATIONS

Haukwa, C., Mountain-scale coupled processes (TH) models, MDL-NBS-HS-000007, Las Vegas, Nev., CRWMS M&O, 1999. Sonnenthal, E.L., and N. Spycher, Drift scale coupled processes (DST, THC seepage) models, MDL-NBS-HS-000001, Las Vegas, Nev., CRWMS M&O, 1999.

ACKNOWLEDGEMENTS

This work was supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memorandum Purchase Order EA9013MC5X between TRW Environmental Safety Systems, Inc., and Ernest Orlando Lawrence Berkeley National Laboratory for the Yucca Mountain Site Characterization Project under Contract No. DE AC0376SF00098. 60

HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

USE

OF

Nuclear Waste Program

NATURAL ANALOGS

IN THE

U.S. NUCLEAR WASTE PROGRAM

Annual Report 1999 - 2000

Ardyth M. Simmons

Contact: Ardyth M. Simmons, 510/486-7106, asimmons@lbl.gov

ACCOMPLISHMENTS

RESEARCH OBJECTIVES

The U.S. Department of Energy’s Repository Safety Strategy for a potential nuclear waste repository at Yucca Mountain, Nevada, rests upon four repository system attributes: (1) limited water contacting waste packages; (2) long waste package lifetimes; (3) slow rate of radionuclide release; and (4) concentration reduction of radionuclides during transport. For each of these attributes, natural analog studies are applied to understand the bounds of processes occurring over long time periods and to test and build confidence in conceptual and numerical models of those processes. Natural analogs refer to natural or anthropogenic (human-produced) systems in which processes expected to occur in a nuclear waste repository have occurred over long time periods and large spatial scales.

Box Canyon was chosen to test the dual permeability modeling approach used at Yucca Mountain. Numerous air permeability and infiltration tests were used to calibrate the model. The dual permeability representation of the variably saturated, fractured basalt produced infiltration front arrival times that were consistent with bromide tracer data. Calibration parameters included a fracture-matrix interaction scaling factor and fracture continuum porosity. Parameter values were within similar ranges observed at Yucca Mountain despite differences between basalt and tuff, indicating the utility of the dual permeability approach. We are applying data from a plume at INEEL to build understanding of retardation of 237Np, 236U, 129I, and 99Tc, radionuclides that are also of interest at Yucca Mountain.

APPROACH

To achieve the objective of improved confidence in repository processes, investigations are underway to study where analogous processes have occurred in the past or are now taking place. The natural analog studies combine approaches that utilize literature surveys and modeling in conjunction with data from a number of sites world wide to understand flow and transport in unsaturated and saturated environments and the effect of thermal perturbations on the natural system. These include a field and modeling study at Peña Blanca, Mexico, as an analog to radionuclide transport in unsaturated ash flow tuffs and modeling studies of anthropogenic analog sites in the United States to gain a better understanding of plume dispersion, colloidal transport of Pu and fracture/matrix interactions. The Nopal I uranium deposit at Peña Blanca, Mexico, lies in unsaturated tuffs closely similar in composition to the Topopah Spring Tuff at Yucca Mountain. Previous investigators suggested that downward migration of uranium from the ore deposit has been minimal. We are testing this hypothesis and working to determine the timing and nature of events that caused uranium to migrate away from the ~8 Ma ore deposit. Transport of uranium has been almost entirely along major fractures (on the order of 0.5 cm aperture) with minor transport along microfractures, and almost no matrix diffusion. The majority of our uranium-series data indicate that the system has been closed to uranium migration for the past 300 k.y. Sites with contaminant plumes allow study of plume migration over time as well as radionuclide transport and retardation mechanisms. Although the anthropogenic sites have a much shorter history than natural analogs, their initial conditions are usually better known and some have been closely monitored. The goal is to utilized experience from modeling flow and transport at sites, such as the Idaho National Engineering and Environmental Laboratory, where flow has occurred along preferential pathways, to build confidence in approaches to modeling flow and transport processes at Yucca Mountain. Geothermal analogs may provide useful insights into complex coupled thermal-hydrologic-mechanical-chemical processes. We are using data and analyses from selected geothermal fields to obtain added confidence in expected thermohydrologic conditions at Yucca Mountain, particularly those related to dissolving or precipitating minerals to cause changes in fracture permeability.

SIGNIFICANCE OF FINDINGS

Analogs have been identified for a variety of processes expected to occur at the potential nuclear waste repository at Yucca Mountain. These provide a significant bound for numerical modeling and understanding of the effects of these processes; however, since the temporal and spatial conditions of the analogs differ from repository conditions, results are interpreted with caution.

RELATED PUBLICATIONS

Civilian Radioactive Waste Management System, Natural analogs for the unsaturated zone, ANL-NBS-HS-000007, Rev. 00, 2000. Civilian Radioactive Waste Management System, Yucca Mountain Site Description, Rev. 1.: Section 13, Natural Analogs, in press.

ACKNOWLEDGMENTS

61

This work was supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memorandum Purchase Order EA9013MC5X between TRW Environmental Safety Systems, Inc., and Ernest Orlando Lawrence Berkeley National Laboratory for the Yucca Mountain Site Characterization Project under Contract No. DE-AC037zF00098. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

SIMULATING INFILTRATION TESTS

Annual Report 1999 - 2000

Nuclear Waste Program

IN THE

BOX CANYON UNSATURATED FRACTURED BASALT

Andre J.A. Unger, Boris Faybishenko, Gudmundur S. Bodvarsson and Ardyth M. Simmons Contact: Andre J.A. Unger, 510/495-2823, ajaunger@lbl.gov

RESEARCH OBJECTIVES

The objective of this work is to examine the applicability of conceptual and numerical modeling methodologies utilized at Yucca Mountain, Nevada, to study the Box Canyon, Idaho, infiltration test data. The intent is to build confidence in the utility of these approaches for simulating mechanisms controlling infiltration in fractured rock and to substantiate the use of models as predictive tools for the potential Yucca Mountain repository. As such, the Box Canyon site serves as a natural analog to Yucca Mountain for studying flow processes in fractured rocks.

APPROACH

The site consists of layered basalt flows containing horizontal and vertical columnar fractures resulting from cooling of the basalt. The geological and numerical model for the Box Canyon site is used to address issues related to flow of infiltrating water in the basalt hydrogeological system. Field data at the Box Canyon site were gathered from pneumatic and infiltration tests almost entirely within the upper basalt flow. The elevation of the ground surface along with the location of instrumented vertical and slanted boreholes is shown in Figure 1. The box outline indicates the perimeter of the infiltration pond used to contain the ponded water at the ground surface. The numerical modeling effort was conducted using TOUGH2 with the EOS3 module to simulate both mobile water and gas phases though the fractures and matrix of the basalt rock using the dual-permeability approach. Calibration of the model involved analysis of both pneumatic and infiltration test data.

Figure 1. Elevation of (a) ground surface and (b) cross section through upper basalt flow.

ACCOMPLISHMENTS

Calibration results indicated that the fracture-continuum porosity was a very sensitive parameter, controlling the arrival time of the infiltration front. The fracture-continuum porosity of the upper basalt flow ranged from 0.01 to 0.02. The matrix-continuum permeability was increased relative to the core measurements to reflect the influence of the highly permeable vesicular zones on the field scale. Finally, the interfacial area between the fracture and matrix continua was multiplied by factors of 0.01 and 0.1 when using the Corey and van Genuchten relative permeability functions, respectively. Both fracture-continuum porosity and matrix-continuum permeability values were representative of independently measured values.

RELATED PUBLICATIONS

Unger, A., B. Faybishenko, G.S. Bodvarsson and A. Simmons, A 3-D model for simulating ponded infiltration tests in the variably saturated fractured basalt at the Box Canyon Site, Idaho, J. of Contaminant Hydrology, submitted. Simmons, A., A. Unger, and M. Murrell, Natural analogs for the unsaturated zone, ANL-NBSHS-000007 Rev 00., Las Vegas, Nev., CRWMS M&O, 2000.

SIGNIFICANCE OF FINDINGS

In general, a consistent set of parameters for a 3-D dual permeability model was obtained that allowed the model to replicate the majority of the infiltration test data. Although the dual-permeability approach is also applied to explain groundwater flow at Yucca Mountain, the vastly different scales of Box Canyon and Yucca Mountain imply that upscaling is an issue when comparing parameter values. The applicability of the dualpermeability modeling approach to both Box Canyon and Yucca Mountain does, however, build confidence in its ability to simulate infiltration processes in variably saturated fractured rocks.

ACKNOWLEDGEMENTS

62

This work was supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memorandum Purchase Order EA9013MC5X between TRW Environmental Safety Systems, Inc., and Ernest Orlando Lawrence Berkeley National Laboratory for the Yucca Mountain Site Characterization Project under Contract No. DE-AC03-76SF00098. HTTP://WWW-ESD.LBL.GOV

Annual Report 1999 - 2000

Earth Sciences Division Berkeley Lab

Energy Resources Program Larry R. Myer 510/486-6456 lrmyer@lbl.gov

T

he Energy Resources Program (ER) is responsible for two major program areas: Oil and Gas Exploration and Development, and Geothermal Energy Development.

OIL AND GAS EXPLORATION AND DEVELOPMENT

Multidisciplinary research is being conducted in reservoir characterization and monitoring, optimization of reservoir performance, and environmental protection. Using basic research studies as a source of innovative concepts, ER researchers seek to transform these concepts into tangible products of use to the industry within a time-frame consistent with today’s rapid growth in technology. Reservoir characterization and monitoring involves development of new seismic and electromagnetic techniques focused at the inter-well scale. Field acquisition, laboratory measurements and numerical simulation play important roles in the development activities. Optimization of reservoir performance is focused on simulation-based methods for enhancing reservoir management strategies. Emphasis is placed on the integration of geophysical data, production data and reservoir simulation. The next major step in research will focus on methods to optimize performance through integration of monitored geophysical data, production data and reservoir simulation. International and national concern about the variable climatic effects of greenhouse gases produced by burning of fossil fuels is increasing, while it is also recognized that these fuels will remain a significant energy source well into the next century. In response to these concerns, the Energy Resources Program is initiating research in methane hydrates and geologic sequestration of CO2. These studies are focused on development of technologies which will minimize the impact of fossil fuel usage on the environment. Principal research activities include: • Development of single-well and cross-well seismic technology, including instrumentation, acquisition and processing; • Applications of seismic methods for characterization of fractured reservoirs;

63

Laboratory measurement of the seismic properties of poorly consolidated sands; • Development of efficient 3-D elastic-wave propagation codes; • Development of magnetotellurics for marine applications; • Development of mid-frequency electromagnetic techniques with a focus on imaging through casing; • Improved inversion methods for reservoir characterization, with a focus on combining production and geophysical data; • Application of X-ray CT and NMR imaging to study multiphase flow processes; • Pore-to-laboratory-scale study of physical properties and processes, with a focus on controlling phase mobility, predicting multiphase flow properties and drilling efficiency; • Development of reservoir process-control methods; • Development of new methods to mitigate environmental effects of petroleum refining and use; • Enhancement of refining processes using biological technologies; • Numerical simulation of subsurface methane hydrate systems. Since 1994, the major part of the Oil and Gas Exploration and Development program has been funded through the Natural Gas and Oil Technology HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Annual Report 1999 - 2000

Energy Resources Program

Partnership Program. Begun in 1989, the partnership was expanded in 1994 and again in 1995 to include all nine Department of Energy multi-program laboratories, and has grown over the years to become an important part of the DOE Oil and Gas Technologies Program for the national laboratories. Partnership goals are to develop and transfer to the domestic oil industry the new technologies needed to produce more oil and gas from the nation’s aging, mature domestic oil fields, while safeguarding the environment. Partnership technology areas are: • Oil and gas recovery technology • Diagnostics and imaging technology • Drilling, completion and stimulation • Environmental technologies • Downstream technologies Projects are typically multi-year, are reviewed and reprioritized annually by industry panels and are collaborations between national laboratories and industry.

tion. At present, the main research activities of the program include: • Development and enhancement of computer codes for modeling heat and mass transfer in porous and fractured rocks; • Laboratory investigations of the hydraulic and thermal properties of fractured and intact reservoir rocks; • Isotopic and noble gas studies to characterize geothermal fluids and to identify their sources, their potential migration paths and the connectivity within the geothermal reservoir; • Documentation of the behavior of geothermal fluids under commercial production and injection operations (e.g., field case studies), with emphasis on The Geysers.

GEOTHERMAL ENERGY DEVELOPMENT

The main objective of ER’s geothermal energy development program is to reduce uncertainties associated with finding, characterizing and evaluating geothermal resources. The ultimate purpose is to lower the cost of geothermal energy for electrical generation or direct uses (e.g., agricultural and industrial applications, aquaculture, balneology, etc.). With these goals in mind, existing tools and methodologies are upgraded and new techniques and instrumentations are developed for use in the areas of geology, geophysics, geochemistry and reservoir engineering. The program encompasses theoretical, laboratory and field studies, with an emphasis on a multidisciplinary approach to solving the problems at hand. Cooperative work with industry, universities and government agencies draws from Berkeley Lab’s 25 years of experience in the area of geothermal research and development. In recent years, DOE’s geothermal program has become more industrydriven, and a significant part of the Berkeley Lab effort has been directed toward industry assistance, especially in the area of technology transfer and in understanding the nature and dynamics of The Geysers geothermal field in northern California, which has begun to show the effects of over exploita-

FUNDING

The Oil and Gas Exploration and Development program receives funding from the Fossil Energy, Natural Gas and Oil Technology Partnership Program and Office of Science of the U.S. Department of Energy. Support is also provided by the Gas Research Institute (GRI) and direct industry contributions. Industrial collaboration is an important component of the DOE Fossil Energy and GRI programs. The Geothermal Energy Development program receives support from the Office of Energy Efficiency and Renewable Energy, Office of Geothermal Technologies, of the U.S. Department of Energy.

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Earth Sciences Division Berkeley Lab

Energy Resources Program

CROSS-WELL SEISMIC IMAGING

IN

Valeri A. Korneev

THREE DIMENSIONS

Annual Report 1999 - 2000

Contact: Valeri A. Korneev, 510/486-7214, vakorneev@lbl.gov

RESEARCH OBJECTIVES

Recent advances in data acquisition, including shooting "on-the-fly" multilevel receiver systems, higher telemetry rates and stronger sources have dramatically decreased survey costs, opening up the potential for multi-well, 3-D surveys over large areas of existing reservoirs. Until recently, most cross-well surveys have been performed on a single vertical well pair, creating very limited 2-D cross-sections between the wells. Most of the imaging algorithms currently in use were developed under the assumption of near-well trajectories with minimal out of the plane dip. In real world geometries, 3-D effects must be incorporated. By performing multi-well surveys, 3-D coverage over sections of the reservoir is achieved. Extending cross-well imaging technology to handle the three-dimensional nature of wells and earth models is the ultimate objective of this work.

APPROACH

The extension from a single well pair to a 3-D well and survey geometry has revealed imaging issues that were not addressed in the initial development of the cross-well technology. Recently, Tomoseis Inc. researchers have developed a common earth model framework using a Chebychev polynomial representation for performing cross-well imaging. They have also developed visualization approaches to 3-D well and survey geometries. The general work plan involves the development and testing of 3-D traveltime inversions, 3-D reflection mapping and 3-D migration. The product of this work will be a series of algorithms and software that will be capable of performing cross-well imaging and visualization in real-world, 3-D, multiprofile cross-well data. The specific work plan for LBNL involves the development of algorithms and computer programs for 3-D simulation of elastic wave propagation. LBNLâ&#x20AC;&#x2122;s participation in the SBIR (Small Business Innovation Research) project jointly with Tomoseis Inc. consists of developing of efficient computer codes to simulate 3-D cross-well seismic data sets and computing of those data sets for variety of models. To provide a reliable good quality of data sets the first stage of code developing will include intensive testing and verification for variety of models. Figures 1 and 2 show very good accuracy of first arrivals compared to the ray method solution (blue) computed for a complex layered structure. The discrepancies are well inside of the 2% error corridor (red).

Figure 1. Vertical velocity model for sedimentary layered structure.

Figure 2. Tomoseis picks vs 3D FD for the source 61 (2700) FD zero time aligned to the first maximum of the pulse. Grid 160*128*160 with 5-ft spacing (800x640*800) 1.03, 5 point approx.

ACKNOWLEDGEMENTS

SIGNIFICANCE OF FINDINGS

This work has been supported by the U.S. Department of Energy under Contract No. DEAC03-76SF00098. Funding was provided by DOEâ&#x20AC;&#x2122;s Small Business Innovation Research (SBIR) Geosciences Program to Tomoseis Inc., where LBNL participates as a subcontractor.

The development of practical 3-D cross-well imaging will take crosswell technology from a limited market to widespread use by geoscientists and reservoir engineers. The use of the technology will greatly improve production of oil and gas from domestic reservoirs, increasing reserves, enhancing recovery and lowering development and production costs.

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Earth Sciences Division Berkeley Lab

Energy Resources Program

SINGLE-WELL SEISMIC IMAGING

Annual Report 1999 - 2000

Ernest L. Majer, Roland Gritto and Tom Daley

Contact: Ernest L. Majer, 510/486-6709, elmajer@lbl.gov

RESEARCH OBJECTIVES

The continuing objective of this project is to identify and provide solutions to fundamental issues surrounding single-well seismic imaging in order to evaluate and develop the technology in a timely and cost-effective fashion. Single-well imaging is in its infancy and there are many unanswered questions but only limited resources to address the issues. Therefore, this technology must be developed in an efficient and logical manner to quickly identify the fundamental attributes that must be included in a total methodology, while leveraging the best available resources to ensure its successful application and acceptance.

A very large and comprehensive data set is now available for analysis and processing for evaluating single-well processing methodology in general.

The work is an integrated, four-year approach to spur the development and application of a new technology in a time frame much quicker than if left to individuals working separately. The project is meant to leverage resources in order to address issues that would not be addressed by individual companies. It is a coordinated effort between three national laboratories working closely with industry and involving university support. In addition to LBNL, the other participating laboratories are Idaho National Engineering and Environmental Laboratory, and Sandia National Laboratories. It recognizes that in a time of shrinking funds, there is an obligation to spend wisely, while creating and maintaining fairness of opportunity to the industry as well as bringing the appropriate capabilities of the national laboratories to complement and catalyze industry's efforts in this area. The proposed work consists of four interdependent activities which comprise facets of the technology required for the ultimate, successful development of single-well seismic imaging and to some degree cross-well imaging: • Hardware: sources/receivers; telemetry/recording; borehole noise effects; deployment. • Modeling: synthetic seismograms; parametric studies; inversion; designs for hardware/surveys. • Field Testing: quality data sets; evaluation/validation at well characterized sites. • Data Processing and Interpretation: algorithms; 3-D imaging; noise reduction; visualization.

which we feel is close to a commercial prototype. A variety of field testing was performed in 1999. Several small single-well tests were performed by LBNL in December 1998-January 1999 to prepare and design the three main field tests in October-December 1999 at the Bayou Choctaw site. LBNL processed and analyzed the cross-well data set to map the location of the salt dome edge using both straight and curved ray approaches. The data from the December-January tests at Bayou Choctaw was also processed for reflectivity from the salt dome. In addition, Schlumberger processed the single-well data from their tests using a high frequency tool in 1998 at Bayou Choctaw. In 2000 emphasis will be placed on processing and analysis of the data collected in 1999. A very large and comprehensive data set is now available for analysis and processing for evaluating single-well processing methodology in general. LBNL will focus on processing for reflectivity and signal-to-noise enhancement. Also addressed will be such issues as the efficiency of the method as a function of source type, receiver type, well conditions, offset and other parameters encountered in full-scale field tests.

The LBNL fiberoptic system has been upgraded to a 24-channel system with the bandwidth increased to 3600 hz. Also addressed was noise reduction (due to source interference) through the addition of noise suppression filters and a redesign of the grounding of the downhole digitizer. This allowed a dramatic improvement in noise reduction. The LBNL/CONOCO POV was modified to operate in the fiber optic system. In the next year only minor modifications and field hardening will be performed to the system,

This work has been supported by the Assistant Secretary for Fossil Energy, Office of Natural Gas and Petroleum Technology, through the National Petroleum Technology Office, Natural Gas and Oil Technology Partnership, under U.S. Department of Energy Contract No. DE-AC03-76SF00098.

APPROACH

ACCOMPLISHMENTS

ACKNOWLEDGEMENTS

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Earth Sciences Division Berkeley Lab

Energy Resources Program

FRACTURE QUANTIFICATION

IN GAS RESERVOIRS Ernest L. Majer, Tom Daley, Roland Gritto, Larry Myer, S. Nakagawa and Kurt Nihei

Annual Report 1999 - 2000

Contact: Ernest L. Majer, 510/486-6709, elmajer@lbl.gov

RESEARCH OBJECTIVES

LBNL is the lead institution of a comprehensive program between the Department of Energy and industry for an integrated field testing and analysis effort aimed at improving the fundamental understanding of seismic wave propagation in naturally fractured gas reservoirs. A cooperative research program has been organized between LBNL and Conoco Inc., Lynn Inc., Schlumberger Inc., Stanford University and Virginia Tech. This effort is focused at the field scale on using field production and test facilities for both the development and validation of methods for predicting fractured reservoir performance. The overall objective of this work is to perform fundamental research that will eventually be used by industry to develop and deploy technology that can quantify the fracture characteristics controlling flow and transport in naturally fractured gas reservoirs.

The overall objective of this work is to perform fundamental research that will eventually be used by industry to develop and deploy technology that can quantify the fracture characteristics controlling flow and transport in naturally fractured gas reservoirs. industry partners meet all of these criteria. We anticipate that wells will be drilled on the results of this work for validation. The overall work plan can be divided into four broad tasks: 1. Modeling 2. Field measurements 3. Processing and interpretation 4. Reservoir simulation

APPROACH

We are starting with current state-of-the-art methods and extending the surface-based information with current borehole methods (vertical seismic profiling, cross-well and single-well) to quantify fracture characteristics. The approach will be an industry-coupled program tightly coupled to actual field cases, iterating between development and application. Past efforts have focused on field experiments in well-characterized field sites at both the intermediate and full field scale. We will continue this approach working at industry sites of opportunity which are representative of other sites. This project is organized into tasks which will focus on the test sites for experimental field work and model validation. LBNL personnel will work cooperatively with both the exploration and production departments of the petroleum companies to design integrated geophysical procedures and analysis techniques. The participating companies will provide access to the field sites and data collected at the test and production sites, and participate in the planning and execution of the experiments. LBNL will provide basic theory and modeling support to aid in the design of the investigations, and perform some of the characterization experiments. Data analysis will be done by both LBNL and the companies. The processed results generated by this project will be published and available to others at the end of the project. The effort is a balanced program between theoretical and mathematical improvements in the fundamental processing algorithms, and implementation in the field. The proposed field site is the Conoco property in New Mexicoâ&#x20AC;&#x2122;s San Juan Basin. The criteria we set for the field site are: (1) it must be in an area of ongoing commercial interest; (2) it must have a wealth of geologic and other geophysical information; and (3) we must be able to have ongoing access throughout the project. Ideally, we also like to be involved with the producer to such an extent that if our approaches and methodology are successful, they be integrated into future operational plans. The field site selected and

ACCOMPLISHMENTS

To date, a variety of field tests and data processing has shown that lab and intermediatescale seismic methods can detect the fracture or fracture sets controlling fluid flow. This project is meant to scale up these results to the commercial scale used in producing gas fields. Current work is focused on: (1) processing a 20-square-mile 3-D surface reflection section over a producing field; (2) modeling the results; (3) interpreting the results for fracture properties; (4) drilling the section; (5) collecting VSP and single-well data for validation; and (6) designing a follow-on program to delineate the permeable fractures.

ACKNOWLEDGEMENTS

This work has been supported by the Assistant Secretary for Fossil Energy, Office of Natural Gas and Petroleum Technology, through the National Energy Technology Laboratory, under U.S. Department of Energy Contract No. DE-AC03-76SF200098.

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Earth Sciences Division Berkeley Lab

Energy Resources Program

Annual Report 1999 - 2000

NATURAL FRACTURE CHARACTERIZATION USING PASSIVE SEISMIC WAVE ILLUMINATION Kurt T. Nihei, Larry R. Myer, Peter Goldstein1 and Kevin M. Mayeda1 1Lawerence Livermore National Laboratory, Livermore, Calif. Contact: Kurt T. Nihei, 510/486-5349, ktnihei@lbl.gov

RESEARCH OBJECTIVES

The presence of natural fractures in reservoir rock can significantly enhance gas production, especially in tight gas formations. Any general knowledge of the existence, location, orientations, spatial density and connectivity of natural fractures, as well as general reservoir structure, that can be obtained prior to active seismic acquisition and drilling can be exploited to identify key areas for subsequent higher resolution active seismic imaging. The objective of this research is to investigate the potential of 2-D surface arrays and multi-component seismic data from local earthquakes to identify and characterize potential fractured gas reservoirs located near seismically active regions.

APPROACH

Figure 1. Passive source reverse time imaging using a surface

Natural fractures in sedimentary rocks often appear as vertiarray. The receiver array consists of 180 two-component receivers spaced 46 m apart (8280 m aperture). The source is a 10 Hz, vercal planes of compliance with spacings on the order of the bed tically incident, plane P-wave. Horizontal lines indicate the posithickness. Past research has demonstrated that the seismic proptions of the layers. Vertical lines show the location of the vertical erties of a single set of aligned fractures can be described as an fractures. The image is formed by computing the vector product of anisotropic medium, provided that both the wavelength is large the direct P-wave and the scattered P-to-P and P-to-S waves as compared to the fracture spacing and the fractureâ&#x20AC;&#x2122;s equivalent these wavefields are back-propagated through the medium. background "thickness" (i.e., for a shear wave, the equivalent fracture thickness is the product of the shear modulus and shear fracture compliance). If either of these conditions is violated, recent research has wave is present, e.g., vertical seismic profiling demonstrated that fractures will support a variety of frequency-sensitive and cross-well imaging. waves, including fracture head waves, fracture interface waves, and fracSIGNIFICANCE OF FINDINGS ture channel waves, that are not predicted by the simple anisotropy Current methods for characterizing fractures description. A series of finite difference simulations in which fractures are in reservoir rocks are typically based on effective modeled explicitly (rather than as an effective medium) have demonstratmedium concepts. This research describes the ed that vertical fractures can be efficient generators of P-S converted body conditions under which fracture-converted waves, and that the magnitude of the fracture tip diffracted waves are waves are generated, and presents a new scheme small. for imaging fractures using converted waves ACCOMPLISHMENTS recorded along a seismic array. The fracture modeling described above stimulated a new approach for RELATED PUBLICATION solving the inverse problem of fracture detection from passive seismic array Nihei, K., P. Goldstein, L. Myer, K. Mayeda and data. The approach is an adaptation of the excitation-imaging condition for R. Parker, Natural fracture characterization active sources used in reverse time migration (Chang and McMechan, 1987) using passive seismic wave illumination, to passive sources. GasTIPS, 6 (1), 2000. The result of this passive-source reverse-time imaging using a linear array of 180 receivers is shown in Figure 1 for a model containing a 220-mACKNOWLEDGEMENTS thick layer with three fractures illuminated from below by a vertically inciThis work has been supported by the Gas dent, 20-Hz P-wave. Except for some vertical smearing caused by finite array Research Institute under Contract No. 5097-260aperture effects, the fracture locations and strengths are recovered using this 3775, under U.S. Department of Energy Contract passive-source reverse-time imaging algorithm. It should be noted that this No. DE-AC03-76SF00098. approach can also be used for active-source imaging provided that a direct

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Earth Sciences Division Berkeley Lab

Energy Resources Program

IMAGING, MODELING, MEASUREMENT AND SCALING

OF MULTIPHASE Liviu Tomutsa and Asoke De

Contact: Liviu Tomutsa, 510/486-5635, ltomutsa

Annual Report 1999 - 2000

FLOW PROCESSES

RESEARCH OBJECTIVES

Our objective was to develop methodologies based on advanced imaging technology for rapid and accurate measurement of petrophysical properties and prediction of engineering parameters needed for reservoir simulation.

APPROACH

To simulate multiphase flow in a reservoir, one needs to know—for the various facies—petrophysical parameters such as porosity, permeability, relative permeabilities and capillary pressures. Laboratory measurements of these parameters using core plugs are often expensive, time-consuming or unavailable due to lack of core material—thus the need to develop rapid methods that require a minimum of core material. A promising approach uses pore network models to compute rock properties. This project addresses the following: (1) obtaining pore network data to be used as input for existing network models; (2) validating the network predictions with laboratory core measurements; and (3) upscaling the core measurements to use in the field simulator.

Figure 1. View of LBNL’s new X-Ray CT Laboratory.

ACCOMPLISHMENTS

Three-dimensional pore network images have been analyzed by adapting the software package 3DMA (developed at SUNY by W.B. Lindquist). The network data have been used with the ANetSim pore network simulator (developed by T.W. Patzek, LBNL/UC Berkeley). Good agreement with laboratory measurements has been found. A new Rock-Fluid Imaging Laboratory has been installed. Its equipment, described briefly below, allows measurement and visualization of rock properties and fluid distribution from pore to whole-core scale. • CT scanner (third generation, maximum energy 150 kV, 0.2 mm/voxel and 2s/scan): used for measurement and display of 2-D and 3-D distribution of rock properties and fluid saturations at core plug scale. • Linear x-ray scanner (tunable x-ray source, 10-60 kV, and germanium detector): allows measurements of saturation in cores at up to 280°F and 8000 psi for steady state two- and three-phase relative permeability measurements. • MRI microscopy equipment (6.34 T magnet and a 90 Gauss/cm gradient): used to generate 3-D images of the pore space and fluids distribution at pore scale. • Low-field NMR (2 MHz): allows computation of core properties such as porosity, pore size distribution, permeability, saturation, bound and moveable water. • Probe permeameter (1–3000mD): used to perform measurements of permeability distribution on rock surfaces on rectangular and circular grid patterns. • Rock core ultracentrifuge(16,000 rpm): used for measuring core plug capillary pressures. • Petrographic image analysis: system consists of petrographic microscopes, visible and UV light sources, low-light cameras, and x-ray lumi-

nescence capability. Used for pore and grain measurements for use in the pore network model.

SIGNIFICANCE OF FINDINGS

By reducing the cost and time of petrophysical core measurements, the density of the petrophysical data can be significantly increased. The higher data density, combined with proper upscaling, will yield more accurate reservoir simulations, improved oil reservoir management and increased oil recovery.

RELATED PUBLICATION

Schatzinger, R.A., and L. Tomutsa, Multiscale heterogeneity characterization of tidalchannel, tidal delta, and foreshore facies, Almond Formation Outcrops, Rock Springs Uplift, Wyoming, Reservoir Characterization-Recent Advances, AAPG Memoir 71, p. 45-56 (R. Schatzinger and J. Jordan, eds.), 1999.

ACKNOWLEDGEMENTS

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This work has been supported by the Assistant Secretary for Fossil Energy, Office of Natural Gas and Petroleum Technology, through the National Petroleum Technology Office of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Annual Report 1999 - 2000

Energy Resources Program

FREQUENCY-DEPENDENT SEISMIC ATTRIBUTES

OF POORLY CONSOLIDATED SANDS Kurt T. Nihei, Seiji Nakagawa, Zhuping Liu, Liviu Tomutsa, Jil T. Geller, Larry R. Myer and James W. Rector Contact: Kurt T. Nihei, 510/486-5349, ktnihei@lbl.gov

RESEARCH OBJECTIVES

The objectives of this work are to: (1) provide a theoretical basis for frequency-dependent amplitude attributes associated with multiple fluid (and gas) phases in poorly consolidated sands for a range of consolidation conditions; (2) explore the possibility of new seismic attributes; (3) use numerical modeling to examine optimum 3-D seismic acquisition geometries and processing schemes for illuminating these attributes in poorly consolidated sand reservoirs; and (4) apply the results of these analyses to 4-D seismic imaging.

APPROACH

This research consists of a combination of laboratory acoustic measurements, theoretical development and three-dimensional visco-elastic wave simulations. The focus of the first two tasks is to obtain a frequency-dependent theory for wave propagation in poorly consolidated sands that can be used to predict the effects of fluid substitution and reservoir compaction on elastic waves. The third task will embed this rock physics model into a numerical simulator to predict the effects of fluid distributions and changes in fluid distributions on acoustic properties in the presence of different reservoir structures. The final task will be to analyze the synthetic data for robust seismic attributes that can be used for 4-D monitoring of changes in reservoir fluid/gas migration and reservoir consolidation.

Figure 1. Experimental set-up for measuring the seismic properties of sand packs under variable confining pressure and saturation conditions. The attenuation and velocities are determined from pulse-transmission and resonance measurements. The bulk saturation and fluid distribution is determined from X-ray CT scanning.

frequency-dependencies and sensitivities to spatial fluid distributions.

ACCOMPLISHMENTS

The first year of the project has focused on the design, fabrication and testing of a seismic wave apparatus for measuring the frequency-dependent (1-10 kHz) properties of poorly consolidated sands. The sand pack is housed in a polycarbonate tube (4.24 cm OD, 0.577 mm thickness, 0.81 m length) that is placed inside a tubular pressure vessel, fabricated of aluminum to allow x-ray CT scanning (Figure 1). The ends of the tube are sealed with two massive steel transducers, one containing a PZT piezoelectric crystal (5400 Navy II) for the wave excitation, and the other a triaxial accelerometer (PCB Piezotronics 356A12) for wave reception. The current source transducer is an extensional mode source. A piezoelectric torsional mode transducer is in the early stages of design. The first set of tests was conducted on a coarse-grain Monterey sand with 7 MPa hydrostatic (nitrogen gas) confining pressure, for dry and partial water-air saturations. Both resonance and pulse transmission measurements were made. For a frequency of 3 kHz, an increase in water saturation from 0 to 0.5 resulted in a strong increase in pulse-transmission and resonance-derived attenuation coefficients, and only minor changes in the velocity. The attenuation estimates for dry sand were approximately the same for the two methods of measurement. However, with increasing water-saturation, the pulse-transmission method displayed higher attenuation than the resonance method. Further experiments and numerical modeling are underway to explore the source(s) of the observed attenuation,

SIGNIFICANCE OF FINDINGS

Seismic characterization of fluids in poorly consolidated sands is a problem of growing importance, especially in the Gulf Coast. A basic understanding of the acoustic properties of sands under moderate stresses and in the presence of multiple fluids and gas is required to relate seismic attributes to fluid distributions. The laboratory effort described here will provide data that will be used to determine intrinsic attenuation and to infer scattering attenuation at sonic frequencies.

ACKNOWLEDGEMENTS

This work has been supported by the Assistant Secretary for Fossil Energy, Office of Natural Gas and Petroleum Technology, through the National Petroleum Technology Office, Natural Gas and Oil Technology Partnership, under U.S. Department of Energy Contract No. DE-AC03-76SF00098.

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Earth Sciences Division Berkeley Lab

Energy Resources Program

HIGH SPEED 3-D HYBRID ELASTIC SEISMIC MODELING

Annual Report 1999 - 2000

Valeri A. Korneev and G. Michael Hoversten

Contact: Valeri A. Korneev, 510/486-7214, vakorneev@lbl.gov

RESEARCH OBJECTIVES

The best tool for understanding and imaging complex structure and long offset data is an accurate, fully elastic 3-D algorithm. The applications of such algorithms are manyfold, including survey design, hypothesis testing, AVO evaluation, wave field interpretation, generation of test data sets for testing of new migration algorithms, and as forward calculation engines in 3-D prestack migration algorithms and new full waveform inversion algorithms. While such algorithms have been developed, uniform grid sampling produces costly over-sampling of high-velocity regions and unnecessarily small time integration steps in low-velocity regions. Thus, the scale of the computer resources required to model the entire geologic section, from source locations to the depths of interest, with a fully elastic representation, is prohibitive. In addition, the discretization of high-contrast boundaries such as the salt-sediment interface can produce high-energy diffraction events in the modeled data, which are often difficult to completely suppress even in processing. There is a critical need for an algorithm which can accurately model and image all of the elastic effects occurring in complex structures, while at the same time being efficient enough to run on clusters of available workstations in a reasonable time. Our objective is to develop an efficient 3-D elastic forward modeling algorithm that will address these requirements.

There is a critical need for an algorithm which can accurately model and image all of the elastic effects occurring in complex structures, while at the same time being efficient enough to run on clusters of available workstations in a reasonable time. Our objective is to develop an efficient 3-D elastic forward modeling algorithm that will address these requirements.

APPROACH

There are two critical concepts that will provide for a significant improvement in computation efficiency and accuracy over what is currently available. First is the decomposition of the original three-dimensional model into parts (subdomains) where wave propagation will be computed using the optimal spatial parameterization for each particular subdomain. The second critical concept is the use of local boundary-condition matching at high-contrast interfaces to eliminate artifacts from grid discretization.

Figure 1. Main subdomain types for optimal hybrid seismic wave propagation modeling.

The new variable grid subdomain FD algorithm is being designed for parallel cluster computing using a message passing interface technique. This will make its usage possible for local network computer clusters, and therefore affordable, relatively inexpensive and easily upgradable.

SIGNIFICANCE OF FINDINGS

The use of subdomains in finite-difference (FD) modeling has several major advantages over current single-domain algorithms. First, this approach allows fine griding to be used only in the low-velocity regions (sea water, loosely compacted sediments) where it is required, and allows courser griding in the higher velocity regions (salt, deep sediments). For a typical undersea salt body structure, the use of just two subdomains gives factor of 8 in memory and CPU savings, which can be used for model-size extension. Second, the use of subdomains allows the use of a computationally efficient acoustic approach for liquid parts (which gives approximately a factor of 5 in speed increase and memory savings) and a complete elastic formulation in the complex portions of the model. Third, just a subset of all subdomains can be used in the first stages to avoid unnecessary computations for the regions that are still out of reach of propagating waves. Considering the rather common case of very low velocities in the shallow parts of seismic structures, this will bring up to a 30% CPU efficiency-rate increase.

ACKNOWLEDGEMENTS

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This work has been supported by the Assistant Secretary for Fossil Energy, Office of Natural Gas and Petroleum Technology, through the National Petroleum Technology Office, Natural Gas and Oil Technology Partnership, under U.S. Department of Energy Contract No. DE-AC0376SF00098. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Energy Resources Program

INTEGRATED RESERVOIR MONITORING

USING SEISMIC AND G. Michael Hoversten

Annual Report 1999 - 2000

CROSS-WELL ELECTROMAGNETICS

Contact: G. Michael Hoversten. 510/486-5085, gmhoversten@lbl.gov

RESEARCH OBJECTIVES

The central problem in petroleum production is the development of a model or simulator that guides the drilling of wells, the management of the field and the design of enhanced recovery processes. Geophysics can play a major role in mapping the rock properties between wells and can in fact assign properties to the models of the interwell volume and greatly increase the effectiveness of in-fill drilling, reservoir production and reservoir stimulation. Using geophysics to extrapolate borehole data on porosity, saturation and permeability to the interwell volume, and to monitor changes in these reservoir properties over time, will literally revolutionize reservoir engineering. The development of cross-well and single-well seismic and electromagnetic (EM) techniques is proceeding. Work to date at LBNL and Sandia on the cross-well capabilities of EM on full-scale petroleum reservoirs has shown that at frequencies between 10 and 100 Hz, interwell volumes up to 1 km can be mapped. At these frequencies the effects of steel casing reduce to an attenuation factor that is manageable given current transmitter and receiver technology. The results from numerical experiments on the water flood of a North Sea reservoir show that when reservoir top and base geometry from seismic is incorporated into the inversion of crosswell EM data, the interwell resolution is greatly enhanced, and time-varying water saturation can be mapped.

APPROACH

Figure 1. Reservoir simulations at three times converted to resistivity (left side) and cross-well EM inversions of the numerical data generated from these models (right side). Note the build up of oil (blue-green) at +10 years near the transmitter well. The oil build up is shown in the inversion at +10 years. The starting model for the reservoir was a constant resistivity determined by averaging the resistivities at the wells. T0 water saturation (conductivity) is significantly lower than at later times, requiring a change in color tables between t0 and +7 years. +7 and +10 are displayed on the same color scale.

We have made considerable progress in this constrained or joint interpretation. We have a new algorithm in which the location of boundaries and the resistivity variations within specific boundaries are the parameters of the inversion. We have also modified existing general, smooth model inversions to allow certain sub volumes within the model to be fixed in their properties (as dictated by the reservoir model and log data for example) and only resistivity values in the region of anticipated change are obtained from the inversion.

Our third focus area is the interpretation of a cross-well EM data set in conjunction with reservoir simulation modeling for the Lost Hills Oil Field provided by Chevron. In this case we are using cross-well EM to improve the reservoir model used for production history matching during an EOR water flood project. In particular it is hoped that the cross-well EM will aid in the placement of fractures that control water flow in the reservoir. This work has just begun with an initial production history match done prior to incorporating the cross-well EM data.

RESULTS

The project has focused on three main areas of research. Our first focus area is a numerical model study of the Snorre Field in the North Sea (Figure 1). This exercise has demonstrated that cross-well EM, when used in conjunction with surface seismic for defining the reservoir geometry, can map the vertical average water saturation in the reservoir between wells at distances up to 1 km. The second focus area is the integrated interpretation of a cross-well seismic and EM data set provided by Texaco from the Kern River Oil Field in California. This is a unique data set where both seismic and EM data were acquired simultaneously in the same wells during a steam flood of the reservoir. Interpretation to date has shown a high degree of correlation between the interpreted seismic velocities and the temperature, and between the interpreted electrical conductivity and the water saturation. We are working with Texaco to complete an integrated interpretation of this data set.

ACKNOWLEDGEMENTS

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This work has been supported by the provided by the Assistant Secretary for Fossil Energy, Office of Natural Gas and Petroleum Technology, through the National Petroleum Technology Office, Natural Gas and Oil Technology Partnership of the U.S. Department of Energy, under Contract No. DE-AC03-76SF00098. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Energy Resources Program

CONTROL OF FLUID INJECTION

INTO A LOW-PERMEABILITY Tad W. Patzek and Dmitriy B. Silin

Contact: Tad W. Patzek, 510/643-5834, patzek@patzek.berkeley.edu

ROCK

Annual Report 1999 - 2000

RESEARCH OBJECTIVES

Low-permeability rocks hold about one-third of the world’s crude oil and a comparable fraction of oil reserves in the United States. The low-permeability fractured rock hold tens of billions of barrels of oil. We focused our efforts on the analysis, modeling and control of water injection into low-permeability fractured rocks. The volume of data processed in a cost-efficient and environmentally safe operation of a large oil field is immense. Therefore, our ultimate purpose is to design an integrated computer-driven system of field-wide waterflood surveillance and supervisory control. At present, this system consists of the Waterflood Analyzer software package and a network of individual injector controllers, all implemented in modular software (Figure 1).

APPROACH

An injection controller is an essential part of automated waterflood project surveillance and control. A reasonable decision can be made only if all the necessary information is appropriately collected, stored and analyzed. The Waterflood Analyzer is a fully functional software package that accesses the injection-production databases, locally or remotely, and visualizes the data in such a way that the current state of operations is displayed at the field scale.

Figure 1. The controller schematic.

by-well injection control. Using optimal control theory methods, we have developed a new model-based injection controller. The controller maintains the prescribed injection rate at changing injection conditions.

RESULTS

The Waterflood Analyzer is an integrated software tool for surveillance and analysis of waterflood operations and production forecasting based on the Matlab programming platform. It is designed to be flexible and easily extensible, so that new features can be added along with the progress of research. The injection controller is an essential part of the automated waterflood surveillance and control system (Figure 1). A distinctive feature of our approach is that the injection pressure is computed through a model of the injection process. The controller is designed using optimal control theory methods. It is based on the optimization of a quadratic performance criterion subject to the constraints imposed by the model of the injection well–hydrofracture–formation interactions. Our analysis of injection into a layered formation shows that the initially positive role of a hydrofracture can be quickly reversed because of possible linkage among the injectors and producers. This conclusion sends a crucially important warning: a poor fracturing job followed by aggressive injection may lead to irrecoverable reservoir damage at early stages of waterflood.

RELATED PUBLICATIONS

De, A., D.B. Silin and T.W. Patzek, Waterflood surveillance and supervisory control, SPE 59295, paper presented at SPE/DOE Improved Oil Recovery Symposium, Tulsa, Okla., April 3–5, 2000. Silin, D.B., and T.W. Patzek, Control of water injection into a layered formation, SPE 59300, paper presented at SPE/DOE Improved Oil Recovery Symposium, Tulsa, Okla., April 3–5, 2000.

ACKNOWLEDGEMENTS

This work has been supported by the Assistant Secretary for Fossil Energy, Office of Natural Gas and Petroleum Technology, through the National Petroleum Technology Office, Natural Gas and Oil Technology Partnership, under U.S. Department of Energy Contract No. DE-AC03-76SF00098.

SIGNIFICANCE OF FINDINGS

We have proposed a new concept of the integrated cradle-to-grave surveillance and control system. It combines field-wise data analysis with dynamic access to current waterflood-production data and individual well73

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Earth Sciences Division Berkeley Lab

Annual Report 1999 - 2000

Energy Resources Program

DYNAMIC RESERVOIR CHARACTERIZATION THROUGH THE USE OF SURFACE DEFORMATION DATA Don Vasco and Kenzi Karasaki

Contact: Don Vasco, 510/486-5206, dwvasco@lbl.gov

RESEARCH OBJECTIVES

The objective of this project is to develop a methodology to characterize a reservoir through the use of surface deformation data such as displacements and surface tilt induced by pumping or injection. This can be a costeffective remote-sensing technology for obtaining information regarding reservoir flow geometry, which is critical for successful reservoir management.

APPROACH

When fluid is produced from or injected into a reservoir, it causes volume changes in the reservoir, which in turn induce displacements on the ground surface. If a preferential flow path such as a fault zone exists in the reservoir (which is often the case in geothermal reservoirs), the flow will mostly occur along the fault. Observations of surface deformation can be used to estimate the distribution of the volume changes in the reservoir. For example, a vertical fault zone would produce a linear trough in the inverted image. The larger the volume change at a particular location, the more fluid has likely moved in or out of the location. The distribution of volume change is tightly coupled with that of the reservoir flow properties: permeability and compressibility. Surface expression of such reservoir dynamics can be monitored by using high-precision tiltmeters, GPS, laser level gages and InSAR (Interferometric Synthetic Aperture Radar). Monitoring of the deformation at or near the surface costs very little when compared to drilling a large number of boreholes and instrumenting them with pressure sensors. This remote-sensing approach also provides independent data of the reservoir dynamics that can be used to confirm/refute the reservoir model based on the borehole data alone.

Figure 1. Map view of some 326,000 InSAR range change rates at Coso geothermal field.

RELATED PUBLICATIONS

ACCOMPLISHMENTS

Vasco, D.W., L.R. Johnson and N.E. Goldstein, Using surface displacement and strain observations to constrain deformation at depth, with an application to Long Valley caldera, CA, J. of Geophys. Res., 93, 3232-3242, 1988. Vasco, D.W., K. Karasaki and L. Myer, Inversion of surface tilt caused by fluid migration, J. of Geotech. and Geoenv. Eng., 124, 29-37, 1998. Vasco, D.W., K. Karasaki and C. Doughty, Using surface deformation to image reservoir dynamics, 2000, Geophysics, 65(1), 132-147, 1999.

In 1999, a series of tilt surveys was conducted at three different sites in Japan. As many as 24 tiltmeters were used at Hijiori to improve spatial definition and to study the effects of emplacement depth on tilt signals. The second test at Wasabizawa was conducted to study the feasibility of tilt mapping at a naturally permeable reservoir at depth. At both sites, large tilt signals were observed, and the inversion results show that injected fluids may have migrated to a shallow depth through fracture zones. At the third site, Okuaizu, a long-term monitoring program has been initiated. In addition, Interferometric Synthetic Aperture Radar (InSAR) range changes were successfully used to infer subsurface volume changes at the Coso geothermal field (see Figure 1).

ACKNOWLEDGEMENTS

SIGNIFICANCE OF FINDINGS

This work has been supported by JAPEX Geosciences Institute, Japan, through Contract No. BG98-071(00).

We have shown that surface deformation data such as tilt and InSAR data can be utilized to characterize the dynamics of deep reservoirs.

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Earth Sciences Division Berkeley Lab

Energy Resources Program

EOSHYDR2: A TOUGH2 MODULE FOR THE SIMULATION OF CH4-HYDRATE SYSTEMS IN THE SUBSURFACE

Annual Report 1999 - 2000

George J. Moridis, John A. Apps, Karsten Pruess and Larry R. Myer

RESEARCH OBJECTIVES

Contact: George J. Moridis, 510/486-4746, gjmoridis@lbl.gov

Current estimates of the worldwide quantity of hydrocarbons trapped in gas hydrate deposits range between 1015 and 1018 m3, and even the most conservative estimates of the total quantity of gas in hydrates may easily surpass by a factor of two the energy content of the total fuel fossil reserves recoverable by conventional methods (Sloan, 1998). The objective of this study was to develop a module for the TOUGH2 family of codes (Pruess, 1991) for the simulation of the behavior of methane hydrate systems in the subsurface for use in feasibility studies of CH4 production from hydrate accumulations.

APPROACH

EOSHYDR2 is an extended version of the EOSHYDR module (Moridis et al., 1998) for the TOUGH2 general-purpose simulator (Pruess, 1991) for multi-component, multiphase fluid and heat flow and transport in the subsurface. EOSHYDR is designed to model the non-isothermal CH4 release, phase behavior and flow under conditions typical of CH4-hydrate deposits (i.e., in the permafrost and in deep ocean sediments) by solving the coupled equations of mass and heat balance. As with all other members of the TOUGH2 family of codes, EOSHYDR2 can handle multidimensional flow domains and cartesian, cylindrical or irregular grids, as well as porous and fractured media. Both an equilibrium and a kinetic model of hydrate formation or dissociation are included. Two new solid phases are introduced, one for the CH4-hydrate and the other for ice. Under equilibrium conditions, water, salt, hydrate inhibitors (such as alcohols) and CH4, as well as heat, are the main components. In the kinetic model, the solid hydrate is introduced as the fourth component. The mass components are partitioned among the gas, liquid and the two solid phases. Phase changes and the corresponding heat transfers are fully described. The effect of salt in the pore waters on the CH4 solubility and on the growth and dissociation of gas hydrates is described by thermodynamically correct relationships.

Figure 1. Contribution of dissociated hydrates to gas production from a well located below the hydrate-free gas interface (Case 1: no free gas in the hydrate zone; Case 2: free gas in the hydrate zone).

RELATED PUBLICATIONS

Moridis, G.J., J.A. Apps, K. Pruess and L.R. Myer, EOSHYDR: A TOUGH2 module for CH4release and flow in the subsurface, Berkeley Lab report LBNL-42386, 1998. Pruess, K., TOUGH2â&#x20AC;&#x201C;A general purpose numerical simulator for multi-phase fluid and heat flow, Berkeley Lab report LBL-29400, 1991. Sloan, E.D., Clathrate hydrates of natural gases, Marcel Dekker, Inc., New York, NY., 1998.

RESULTS AND SIGNIFICANCE OF FINDINGS

Different mechanisms and strategies for gas production from CH4hydrate reservoirs were explored in a set of test problems. These tests include modeling of thermal stimulation, depressurization and dissociation induced and/or enhanced by inhibitors (such as brines and alcohols) under both permafrost and marine conditions. The results tend to indicate that CH4 production from CH4-hydrates is technically feasible and has significant potential. Both depressurization and thermal stimulation appear capable of producing substantial amounts of CH4 gas, and their effectiveness can be further enhanced by inhibitors.

ACKNOWLEDGEMENTS

This work has been supported by the Laboratory Directed Research and Development Program at Lawrence Berkeley National Laboratory under U.S. Department of Energy Contract No. DE-AC03-76SF200098.

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Earth Sciences Division Berkeley Lab

Energy Resources Program

TOUGH2, VERSION 2.0

Annual Report 1999 - 2000

Karsten Pruess, Curt Oldenburg and George Moridis Contact: Karsten Pruess, 510/486-6732, k_pruess@lbl.gov

RESEARCH OBJECTIVES

TOUGH2 is a general-purpose numerical simulation program for multiphase, multi-component fluid and heat flows in porous and fractured media. Chief application areas are in geothermal reservoir engineering, nuclear waste isolation studies, environmental assessment and remediation, oil and gas production and storage, and flow under variably saturated conditions in the vadose zone (Pruess, 1998). Since the first release of TOUGH2 to the public in 1991, many new modules have been developed for enhanced process simulation capabilities, and for more efficient and robust solution of large problems. The purpose of this project was to make a collection of the better tested new process modules available to the public, along with full user documentation. Specific criteria and objectives in assembling the new TOUGH2 version were as follows: • Add significant capabilities for simulating flow and transport processes that will be useful for engineering and geoscience applications. • Add features to improve usability of the code, but avoid encumbering users with "feature creep." • Stay with FORTRAN77 and publish source code. • Increasingly emphasize solved problems and internal documentation as a way of communicating code features and use.

demanding flow problems. The T2VOC module for three-phase flows of water, air and a volatile organic chemical (VOC), and the T2DM module for hydrodynamic dispersion in 2-D flow systems have been integrated into the overall structure of the code and are included in the Version 2.0 package. Full documentation and user instructions for these new modules is available in a self-contained user’s guide (Pruess et al., 1999). Much useful information for TOUGH2 applications is available on the TOUGH2 homepage (http://wwwesd.lbl.gov/TOUGH2/). TOUGH2, Version 2.0 is available to the public through the Department of Energy’s Energy Science and Technology Software Center (http://www.osti.gov/estsc/).

SIGNIFICANCE OF FINDINGS

TOUGH2, Version 2.0 provides flexible flow and transport simulation capabilities for a broad range of multiphase and non-isothermal subsurface flow systems. Chief strengths of the code are a focus on practical problems in geosciences and reservoir engineering; cross-fertilization between different application areas, such as nuclear waste isolation and geothermal reservoir engineering; a continuous track record of code verification and testing; and the informal support system of a user community that presently includes approximately 200 installations in 27 countries.

APPROACH

Program modules to be included in Version 2.0 of TOUGH2 were selected based on the significance of new process simulation capabilities and their level of maturity and reliability as judged from in-house applications in various research projects. In order to facilitate code maintenance, the number of independent modules and "minor" variations among them was kept to a minimum. To preserve the value of existing applications, code changes were made only as needed to achieve the additional functionalities desired, and upward compatibility was maintained with the earlier version. Prior to official release, the code was subjected to beta-testing by a group of experienced users.

RELATED PUBLICATIONS

ACCOMPLISHMENTS

Pruess, K., C. Oldenburg and G. Moridis, TOUGH2 User’s Guide, Version 2.0, Berkeley Lab report LBNL-43134, 1999. Pruess, K. (ed.), Proceedings of the TOUGH Workshop ‘98, Berkeley Lab report LBNL41995, 1998.

The main features and advances of Version 2.0 relative to the earlier release include: (1) several new EOS (equation-of-state) modules for different fluid mixtures; (2) enhanced capabilities for previously released fluid property modules; (3) description of diffusion and dispersion in multiphase systems; (4) strongly coupled flow and transport processes; (5) coupling between flow in geothermal reservoir and wellbores in two-phase conditions; (6) tracer transport with sorption and radioactive decay; (7) flow in media with "strong" heterogeneity; (8) precipitation and dissolution effects, with associated porosity and permeability change; and (9) a new set of preconditioned conjugate gradient and direct solvers for more efficient and robust solution of large problems. In addition, numerous enhancements were made in existing modules to facilitate applications to more diverse and

ACKNOWLEDGEMENTS

This work has been supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Geothermal and Wind Technologies, of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

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Earth Sciences Division Berkeley Lab

Energy Resources Program

GEOTHERMAL FIELDS SEEN AS DYNAMIC SYSTEMS

Annual Report 1999 - 2000

Marcelo Lippmann and Alfred Truesdell

Contact: Marcelo Lippmann, 510/486-5035, mjlippmann@lbl.gov

RESEARCH OBJECTIVES

Geothermal systems are dynamic, showing continuous recharge and discharge of fluids and heat. If circulation were to stop, the systems would slowly fade away, and eventually the temperature of their permeable, fluidproducing rock formations (reservoirs) would reflect those of a normal geothermal gradient (i.e., average increase of about 30潞C per km depth). The purpose of this study is to identify the physical and chemical processes that occur in the subsurface and monitor their evolution before and during commercial exploitation of a geothermal field. The Cerro Prieto liquid-dominated system of northern Mexico is our focus.

APPROACH

Figure 1. Block diagram showing the top of the Silica-Epidote Zone in the eastern areas of Cerro Prieto (CP-II and CP-III). Vertical axis gives elevations in meters.

Our approach is to analyze production (i.e., pressure, enthalpy, flowrate) and chemical (i.e., chloride, stable isotope) data collected by the Comisi贸n Federal de Electricidad of Mexico, which operates the Cerro Prieto field. The goal is to correlate the information with reservoir processes, taking into consideration features of the hydrogeologic model of the system as well as changes in fluid production and injection rates and patterns. The hydrogeologic model and a general understanding of reservoir behavior with exploitation have been developed working jointly with our Mexican colleagues since 1978. The present emphasis is to refine the model as new data become available.

SIGNIFICANCE OF FINDINGS

Results indicate that the eastern regions of the system (CP-II and CP-III areas) are naturally recharged with colder groundwaters via Fault H. Fluid injection to maintain reservoir pressures and reduce subsidence should be implemented in these areas, but away from the fault, which provides natural injection. The work confirms the significance of multidisciplinary approaches when trying to understand and predict the behavior of complex and dynamic geothermal systems.

ACCOMPLISHMENTS

During the last year, more insight on the dynamics of the huge Cerro Prieto field has been gained. By studying the spatial and temporal distribution and magnitude of chloride changes in the produced brines, and correlating them with the location of faults, it was possible to infer the flow pattern within the system and its evolution with time. Under natural conditions the faults allowed ascent of hot waters into shallower levels. The location of these recharge areas is mainly controlled by faults, and the temperatures in the undisturbed system are reflected by the distribution of minerals resulting from the hydrothermal alteration of the rocks. Later, in response to the exploitation, groundwaters began descending into the producing reservoir. This type of circulation reversal was documented for a fault in the western part of the field (Fault L) in 1986. Recent findings indicate that a change in fluid flow direction in response to exploitation has also occurred in Fault H to the east. Earlier studies proved that this fault is not only recharging the system with hot fluids from depth, but also with colder groundwaters from shallower aquifers. Based mainly on monitored chemical changes, depth distribution of the top of the silica-epidote hydrothermal alteration zone, scant temperature data and supporting numerical simulation studies, it was concluded that under natural-state conditions, some of the deep geothermal fluids ascended through Fault H and discharged into the overlying groundwater aquifers. The spatial distribution of the alteration zone shown in Figure 1 reflects where and up to what depths the hot fluids ascended initially. Upward flow was clearly controlled by Fault H and was particularly localized in the area of wells E-43 and M-193.

RELATED PUBLICATIONS

Lippmann, M.J., A.H. Truesdell and K. Pruess, The control of Fault H on the hydrology of the Cerro Prieto III Area, Proceedings, 25th Workshop on Geothermal Reservoir Engineering, Stanford Geothermal Program report SGP-TR-165, pp. 266-274, 2000. Truesdell, A.H., and M.J. Lippmann, The lack of immediate effects from the 1979-80 Imperial and Victoria earthquakes on the exploited Cerro Prieto Geothermal Reservoir, Geothermal Resources Council Transactions, 10, 405- 411, 1986.

ACKNOWLEDGEMENTS

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Earth Sciences Division Berkeley Lab

MODELING

Energy Resources Program

OF THE INTERACTION OF HYDROTHERMAL Tianfu Xu and Karsten Pruess

FLUIDS

Contact: Tianfu Xu, 510/486-7057, tianfu_xu@lbl.gov

RESEARCH OBJECTIVES

The interaction of hydrothermal fluids with rocks occurs through a complex interplay of multi-phase fluid and heat flow, and chemical transport processes. We performed simulations of reactive hydrothermal flow that include: (1) detailed fracture-matrix interaction for fluid, heat and chemical constituents; (2) gas phase participation in multiphase fluid flow and geochemical reactions; (3) heat effects on thermophysical and chemical properties and processes; and (4) the kinetics of fluid-rock chemical interaction.

WITH

ROCKS

Annual Report 1999 - 2000

A.

APPROACH

Our simulations were made with the enhanced reactive chemical transport code TOUGHREACT (Xu and Pruess, 1998), which was developed by introducing reactive chemistry into the framework of the existing multiphase fluid and heat flow code TOUGH2 (Pruess, 1991). The model uses a sequential iteration approach, which solves the transport and reaction equations separately. The model can be applied to one-, two- or three-dimensional porous and fractured media with physical and chemical heterogeneity. The model can accommodate any number of chemical species present in liquid, gas and solid phases.

RESULTS AND SIGNIFICANCE OF FINDINGS

Here we present a simulation for the evolution of geothermal fields associated with magmatic activity, such as are encountered in the Long Valley Caldera (LVC), California. In the hydrothermal fluids, vapor and CO2 are the dominant gas-phase constituents (Figure 1a). Results (Figure 1b) indicate that vapor-CO2 discharges through fractures in the caprock cause strong alteration of the earlier formed primary minerals and lead to the formation of secondary minerals, resulting in changes in physical and chemical properties of the system. The predicted alteration of primary rock minerals and the development of secondary mineral assemblages are consistent with field observations such as in LVC. The model presented here may allow for testing production scenarios near a heat-source and in cold meteoric water mixing environments.

B.

RELATED PUBLICATIONS

Xu, T., and K. Pruess, Hydrothermal fluid flow and mineral alteration in a fractured rock under multiphase H2O-CO2 mixture conditions, Berkeley Lab report LBNL 44345, World Geothermal Congress 2000, KyushuTohoku, Japan, May 28 - June 10, 2000. Xu, T., and K. Pruess, On fluid flow and mineral alteration in fractured caprock of magmatic hydrothermal systems, Berkeley Lab report LBNL44804, Journal of geophysical research, submitted.

Figure 1. Vertical 2-D section model for hydrothermal fluid flow and rock alteration in a fractured rock. Change of K-feldspar and porosity (in volume fraction) after 1,000 years.

ACKNOWLEDGEMENTS

This work has been supported by the Laboratory Directed Research and Development Program of Lawrence Berkeley National Laboratory, and by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Geothermal and Wind Technologies, of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

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Earth Sciences Division Berkeley Lab

PLUME SEPARATION

BY

Energy Resources Program

TRANSIENT THERMOHALINE CONVECTION Curtis M. Oldenburg and Karsten Pruess

IN

Contact: Curtis M. Oldenburg, 510/486-7419, cmoldenburg@lbl.gov

Annual Report 1999 - 2000

POROUS MEDIA

RESEARCH OBJECTIVES

The purpose of this research is to investigate the effects of thermal retardation on porous media thermohaline convection. Research on double-diffusive convection began in oceanography and has been strongly influenced by viscous liquid concepts. However, the flow can be more complicated in porous media due to the solid grains of the matrix, which can absorb and conduct heat. Thermohaline convection is an important heat and mass transfer mechanism in liquid-dominated geothermal systems where dense brines are present, such as in the Salton Sea geothermal system.

APPROACH

In this study we have used numerical simulation to demonstrate effects of thermal retardation on thermohaline plumes. We used the numerical simulator TOUGH2 to carry out simulations in a simple two-dimensional domain with properties typical of liquid dominated geothermal systems. We included an extended brine density model for nonisothermal NaCl and CaCl2 brines. The fully coupled solution technique of TOUGH2 ensures efficient solution of the strongly coupled flow equations.

ACCOMPLISHMENTS

In Figure 1 we present the temperature, brine mass fraction and density fields for a situation where a thermohaline plume with 5% positive density contrast moves upward. As shown, the thermal plume is retarded due to interaction with the solid grains. In contrast, the brine plume does not interact with the solid grains, and moves upward at the pore velocity. This results in brine advancing ahead of the thermal plume. The advance of brine is limited however by density effects. This is shown dramatically by the density field in Figure 1, which reveals what we call a density lid, as brine moves incipiently upward while heat is retarded, resulting in a local density maximum at the head of the plume. In a simulation not shown here, complete separation of the thermal and brine plumes occurred for a thermohaline plume with 5% negative buoyancy contrast moving downward.

Figure 1. Temperature, brine mass fraction, and liquid density at t = 2 and 20 yrs for the case of positive initial buoyancy. Vectors show pore velocity.

RELATED PUBLICATION

Oldenburg, C.M., and K. Pruess, Plume separation by transient thermohaline convection in porous media, Geophys. Res. Letts., 26(19), 2997â&#x20AC;&#x201C;3000, 1999.

SIGNIFICANCE OF FINDINGS

Numerical experiments reveal that thermohaline convection in porous media causes brine and heat to separate, a phenomenon not observed in viscous liquid thermohaline convection. This feature of porous media thermohaline convection may contribute to the lack of mixing and effective separation of brine from less saline water in liquid-dominated geothermal systems. Furthermore, the results presented here show that Hele-Shaw cells are not strict analogs for porous media thermohaline convection, since the thermal interaction of the walls of the Hele-Shaw cell will lead to broad temperature fronts in contrast to the sharp, but retarded fronts that arise from thermal retardation in actual porous media.

ACKNOWLEDGEMENTS

This work has been supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Geothermal and Wind Technologies, of the U.S. Department of Energy under Contract No. DEAC03-76SF00098.

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Earth Sciences Division Berkeley Lab

Energy Resources Program

PHASE-PARTITIONING TRACERS

IN FRACTURED GEOTHERMAL Karsten Pruess, Michael Oâ&#x20AC;&#x2122;Sullivan and B. Mack Kennedy Contact: Karsten Pruess, 510/486-6732, k_pruess@lbl.gov

RESEARCH OBJECTIVES

Natural and artificial tracers can provide very useful information on geothermal fluid flows and reservoir processes. For applications in twophase and vapor-dominated reservoirs, there is increasing interest in tracers that partition between liquid and gas phases. Examples include naturally occurring noble gases and other non-condensible gases, such as CO2 and CH4, as well as a variety of man-made chemicals, such as halogenated hydrocarbons. Because of their phase-partitioning properties, these tracers can not only identify preferential flow paths, but they can also be used to monitor reservoir processes and conditions, including in-place water saturation, and the vaporization of injected water. This research is aimed at improving treatment of multiphase diffusion in our general-purpose reservoir simulator TOUGH2, and applying capabilities for advective and diffusive transport of phase-partitioning species to exploring tracer response in fractured geothermal reservoirs.

RESERVOIRS

Annual Report 1999 - 2000

previous interpretations of the underlying reservoir mechanisms. For depleted conditions, as in the SMUD region of The Geysers, tracer returns show a sharp peak after a few days. For undepleted conditions, a broad distribution is obtained with a maximum at about 50 days, similar to results obtained for the Bear Canyon region of The Geysers. Molecular diffusion is insignificant for well-to-well transport, but strongly affects fracture-matrix interaction. It gives rise to a long tail in simulated tracer returns, which agrees with field observations.

SIGNIFICANCE OF FINDINGS

Phase-partitioning tracers are sensitive to boiling processes and in situ water saturation, providing a means for enhanced reservoir definition. Tailing off of tracer concentrations at late time is sensitive to fracture-matrix interaction, and may provide a practical means of evaluating heat transfer areas available for reinjected water.

APPROACH

Existing simulation capabilities that treat advection and diffusion additively in gas and liquid phases were used as a starting point for this research. Field data from injection tests with phase-partitioning tritium and R134a tracers at The Geysers geothermal reservoir in California were available in the literature.

ACCOMPLISHMENTS

RELATED PUBLICATION

The standard approach of adding separately calculated upstreamweighted mass fluxes in gas and liquid phases was applied for tracer advection. For tracers that are both water-soluble and volatile, diffusive fluxes in gas and liquid phases are strongly coupled by phase partitioning effects, and it is not possible to evaluate these fluxes separately. We developed a scheme whereby the entire multiphase diffusive flux is written as the product of a single mass fraction gradient and a single effective strength coefficient. This formulation was shown to cope well even with the worst-case scenario of diffusion across a sharp gas-water interface. Simulations of phase-partitioning tracer tests were performed for a fivespot production injection system. Problem specifications were designed for typical reservoir conditions at The Geysers. Two cases were examined that represent highly depleted and undepleted reservoir regions, as had been studied in tracer testing in the field. The timing and trends of simulated tracer breakthrough agree remarkably well with field observations, supporting

Pruess, K., M.J. Oâ&#x20AC;&#x2122;Sullivan and B.M. Kennedy, Modeling of phase-partitioning tracers in fractured reservoirs, Berkeley Lab report LBNL44802, presented at the 25th Workshop on Geothermal Reservoir Engineering, Stanford University, January 2000.

ACKNOWLEDGEMENTS

This work has been supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Geothermal and Wind Technologies, of the U.S. Department of Energy under Contract No. DE-AC0376SF00098.

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Earth Sciences Division Berkeley Lab

Energy Resources Program

TRACING INJECTATE RETURNS

TO GEOTHERMAL B. Mack Kennedy and David L. Shuster

RESERVOIRS

Annual Report 1999 - 2000

Contact: B. Mack Kennedy, 510/486-6451, bmkennedy@lbl.gov

RESEARCH OBJECTIVES

Fluids re-injected into geothermal reservoirs to maintain pressure and extend productive lifetimes are always cooler than the reservoir fluid. Eventually, returning injectate will cool individual wells and entire reservoirs. To predict the likelihood or onset of cooling, it is necessary to have quantitative measures for early detection of injectate return and the rate that the proportion of coproduced injectate increases. Chloride and the stable isotopes of water have been widely used as natural tracers to monitor injectate returns. However, their reliability is limited by several factors, such as: (1) an assumption that there is only one indigenous geothermal fluid; (2) they can only be applied to single-phase liquid systems; and (3) the differences in composition between the natural reservoir fluid and the injectate are small. Aspects of noble gas geochemistry and their inert chemical behavior can eliminate or minimize these limitations. Thus, noble gases are particularly well-suited for monitoring injection programs.

APPROACH

The low solubility of noble gases in water makes them very sensitive natural tracers for monitoring injectate return. Initially, a geothermal reservoir fluid is expected to have a noble gas compoFigure 1. The noble gas composition in samples from Dixie Valley sition like natural meteoric recharge. Re-injected flashed producproduction wells collected in 1998 and 1999. The fluid composition fluid will be depleted in noble gases by factors of ~100-1000 tions (open and filled squares) are consistent with mixing re-injected brine (filled green square) and meteoric water (20째C ASW, times relative to the natural recharge waters, depending on the blue filled triangle), as depicted by the green mixing line. amount of steam produced. This large concentration difference makes the noble gases excellent tracers for early detection and monitoring. Steam fractions of ~20%, producing residual brines with chlomodel injectate returns. We have demonstrated ride and 36Ar concentrations of ~1.25 and ~0.01 times their pre-flash concentrations, are typical for most geothermal power plants. If the residual that noble gases are very sensitive, quantitative brine is re-injected and mixes linearly with the in-place reservoir fluid, noble and reliable natural tracers for detecting and gases will be ~4 times more sensitive than chloride for detection and monimonitoring injectate return. toring of injectate return.

RELATED PUBLICATIONS

ACCOMPLISHMENTS

Kennedy, B.M., C. Janik, D. Benoit and D.L. Shuster, Natural geochemical tracers for injectate fluids at Dixie Valley, Proc. 24th Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, Calif., pp. 108-115, Jan. 25-27, 1999.

Production and injection fluids collected in 1998 and 1999 from the Dixie Valley, Calif., geothermal field are depleted in noble gases relative to the expected natural recharge composition by factors of ~2 and ~100, respectively (Figure 1). Modeling the composition of the produced fluid as a linear mixture of re-injected brine and natural recharge water suggests that as much as 70-80% of the fluid is injectate and that the proportion of injectate in the production stream is increasing at a rate of ~20%/year.

ACKNOWLEDGEMENTS

This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Geothermal and Wind Technologies of the U.S. Department of Energy under Contract No. DE-AC03 76SF00098.

SIGNIFICANCE OF FINDINGS

Perhaps the most challenging aspect of geothermal reservoir engineering is the ability to predict thermal breakthrough: the onset of cooling in production wells resulting from cool fluids returning from injection wells. Addressing this challenge requires an ability to quantitatively assess and 81

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Earth Sciences Division Berkeley Lab

Energy Resources Program

HEAT AND HELIUM

IN GEOTHERMAL SYSTEMS B. Mack Kennedy, Tobias P. Fischer1 and David L. Shuster 1University of New Mexico

Annual Report 1999 - 2000

Contact: B. Mack Kennedy, 510/486-6451, bmkennedy@lbl.gov

RESEARCH OBJECTIVES

High-temperature geothermal reservoirs acquire heat from active magmatic systems or by deep fluid circulation in regions with elevated thermal gradients. This project investigates (1) the theoretical coherence between helium and heat, (2) the ability of this coherence to identify the heat source in continental geothermal systems, and (3) the feasibility of establishing the thermal state of a geothermal reservoir from deviated heat-helium coherence.

Heat-helium coherence provides a technique for calculating the proportion of geothermal heat derived from crust and mantle sources.

APPROACH

Approximately 75% of the earthâ&#x20AC;&#x2122;s heat budget and all of the 4He are produced by natural uranium and thorium radioactivity. This uniquely couples heat and helium with a calculated Heat (Q)/4He production ratio of ~2.5 x 107 Joule/ccSTP. Geothermal fluids in volcanic terranes are expected to have Q/3He ratios of ~2 x 1012 Joule/ccSTP, because mass and heat are supplied by partial melting of mantle material characterized by a constant 3He/4He ratio. In crustal regimes far removed from active volcanism, the corresponding Q/3He ratio of ~1 x 1015 Joule/ccSTP is three orders of magnitude larger than the expected mantle value. Therefore, helium isotopic compositions of thermal fluids, when coupled to the fluid enthalpy/3He ratio, can readily differentiate the relative proportions of mantle and crustal heat driving geothermal systems. The predicted heat-helium coherence has been confirmed by studies of the relatively simple geothermal systems associated with mid-ocean ridges. However, these systems also reveal that magma degassing, aging and fluid phase separation can fractionate helium from heat.

ACCOMPLISHMENTS

Figure 1. Heat and helium in continental hosted geothermal systems. Triangles labeled Crust, Mantle and Meteoric Water are calculated values. Filled circles represent individual geothermal fields. Data is from this work and published work of others.

Continental geothermal systems show a wide range of Q/3He ratios (Figure 1). Such systems as the Northwest Geysers (NWG), Wairaki (WK), etc., systems derive their heat almost exclusively from magmatic sources. Neither the Dixie Valley (DV) nor Beowave (B) geothermal fields are associated with recent volcanism, but their fluid compositions indicates that the mantle supplies ~90% of the 3He, but only ~5-10% of the heat. All of the systems have experienced significant Q/3He fractionation. A detailed study of each system can identify the responsible process. For example, our recent study of Philippine geothermal fields have found that variations in fluid enthalpy and 3He content suggest the invasion of cooler 3He-poor injectate waters.

a tool for geothermal exploration by providing a 3-D map of the proportion of magma-supplied heat.

RELATED PUBLICATIONS

Kennedy, B.M., T.P. Fischer and D.L. Shuster, Heat and helium in geothermal systems, Proc. 25th Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, Calif., Jan. 24-26, 2000.

SIGNIFICANCE OF FINDINGS

ACKNOWLEDGEMENTS

Heat-helium coherence provides a technique for calculating the proportion of geothermal heat derived from crust and mantle sources. Processes such as magma degassing and aging, adiabatic cooling, fluid mixing and conductive heat loss can fractionate helium from heat. Detailed studies of individual fields can identify the fractionation process(es), which can help constrain reservoir models. The heat-helium coherence can also be used as

This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Geothermal and Wind Technologies of the U.S. Department of Energy under Contract No. DE-AC0376SF00098. 82

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Earth Sciences Division Berkeley Lab

Energy Resources Program

ESTIMATING FRACTURE CLOSURE

UNDER

Peter Persoff

HYDROTHERMAL CONDITIONS

Annual Report 1999 - 2000

Contact: Peter Persoff, 510/486-5931, pepersoff@lbl.gov

RESEARCH OBJECTIVES

Geothermal wells must intersect fractures to be productive. Sealed veins in geothermal reservoirs represent formerly permeable fractures that have been filled by mineral precipitation. But the mechanism by which fractures close may depend upon mineral dissolution as well as upon precipitation. Pressure solution selectively dissolves material from contact points (asperities) or proppant grains that hold fractures open. A small amount of mineral dissolved from these contact points reduces the fracture aperture and transmissivity much more than the same amount precipitated on fracture walls. The partial molar volume of dissolved silica is less than the molar volume of the solid phase; as a result silica is more soluble at higher pressures (stresses). Deep in the reservoir, lithostatic stress is concentrated at asperities in fractures. A thin film of "structured" water is retained at high pressure within the asperity contact. Water in this film dissolves a higher concentration of silica than water in the open fracture. Silica diffuses to the open fracture (where it may precipitate) and more silica is dissolved from the stressed solid. Figure 1 shows a natural fracture from the Awibengkok field in Indonesia. After 25 Âľm of silica has dissolved away from the asperities, this fracture will have closed (see figure) and lost some of its transmissivity. It is of interest to estimate the rate of fracture closure because lost transmissivity is lost production.

Figure 1. Profile of a natural calcite-coated fracture from Awibengkok 4502 ft. As received (black line); Simulated after 25 Âľm closure (blue area).

APPROACH

Of the extensive literature discussing this process, only a few papers present equations for which all the necessary data for numerical evaluation in dimensionally consistent form are readily available. Most models predict compaction rates for sandstones, Figure 2. Estimated closure rates for 1 km depth, showing effect of increasing temperature. which are approximated as systems of packed spheres. These models, however, start by considering the contact between two grains, are greater than predicted by these models. and this portion of the model can be interpreted in terms of an asperity or Another area of uncertainty is rates of dissolution proppant grain holding open a fracture. of other minerals, many of which would dissolve RESULTS/SIGNIFICANCE OF FINDINGS more rapidly than quartz. The presence of clays The concentration gradient driving the process is nearly proportional to also accelerates pressure solution because interlaythe effective stress on the aperture. But the thickness of the water-film is er water adds to the thickness of the water film. The nearly inverse to the pressure; increasing the stress (as by going deeper) occurrence of stylolytes in carbonates also suggests does not increase the rate of pressure solution. Temperature, however, also that they may be more subject to pressure solution. increases with depth, and this increases the closure rate. Predictions for ACKNOWLEDGEMENTS three models are shown in Figure 2. These predicted rates of closure are This work has been supported by the Assistant slow enough not to be of concern from a commercial point of view. Secretary for Energy Efficiency and Renewable However, some experiments have produced faster closure rates. Also, Energy, Office of Geothermal and Wind other non-water-assisted mechanisms such as creep, glide, or cataclasis, Technologies of the U.S. may be more important in geothermal reservoirs, at least until the stress is Department of Energy under relieved at the most-stressed asperities. Contract No. DE-AC03-76SF00098. Some experiments have also shown consolidation rates in sandstone that 83

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Earth Sciences Division Berkeley Lab

Energy Resources Program

WIDEBAND DOWNHOLE TIME-DOMAIN EM TRANSMITTER

Annual Report 1999 - 2000

Alex Becker, Ki Ha Lee and Lou Reginato

Contact: Alex Becker, 510/643-9182, abecker@lbl.gov

RESEARCH OBJECTIVES

The objective of this research has been to fabricate a full-scale borehole time-domain electromagnetic (TEM) system, and to test the tool to demonstrate the wavefield transform (q-domain) methodology for high-resolution imaging of electrical conductivity.

We are certain that this equipment can now be used in an oil-field environment to acquire data suitable for a practical verification of the wavefield transform.

APPROACH

The basic criterion for the design was the production of experimental data which could be used to assess the device performance. We envisaged a simple self-contained, modular transmitter design based on a long solenoid with a non-dissipative magnetic core. The switching electronics would be lodged in a second module and powered by batteries located in a third module (Figure 1). An overall tool length of about 6 m and a weight of about 150 kg were deemed acceptable. A reference signal representative of the transmitter-current waveform would be sent to the surface via an optic fiber link. These data are then used to synchronize and normalize the received signals. For the field tests, the tool was lowered into the test hole via a nylon rope so that no electrical wires or other metallic conductors extended to the surface. The tests were principally designated to assess transmitter performance and were performed in a boreholeto-surface configuration with a commercially available receiver (Geonics EM 47) centered on the drillhole collar. Because of the short (30 m or less) transmitterâ&#x20AC;&#x201C;receiver separations dictated by the logistics of the experiment and the relatively high, 20 ohm-m, resistivity of the intersected formations, we realized that the recorded data would lack the bandwidth needed for its transformation to the wavefield domain. Consequently, transmitter performance was evaluated by comparing the observations with theoretical data that were corrected for the measured system response.

Figure 1. Driver schematic of the TEM transmitter.

performance of the prototype transmitter. We are certain that this equipment can now be used in an oil-field environment to acquire data suitable for a practical verification of the wavefield transform.

ACCOMPLISHMENTS

It has been demonstrated that a viable large-bandwidth TEM transmitter can be constructed using very conventional means, although in the present case, the effective magnetic permeability of the solenoid core was lower than expected. Only a small number of turns can be used to maintain reasonably low inductance. This has to be compensated for with the use of large currents. In this case, good ventilation must be provided to avoid overheating the electronics. In our case, the most temperature-sensitive element was the optic fiber transmitter, which usually failed after about an hour of operation. Care must also be taken to guarantee balance between the negative and positive pulses as this improves the signal/noise ratio.

ACKNOWLEDGEMENTS

This work has been done in collaboration with Baker-Atlas (formally Western Atlas Logging Services, WALS) through the Department of Energyâ&#x20AC;&#x2122;s Office of Science, Laboratory Technology Research Program (SCLTR), CRADA Project LBL94-14. The project has been supported in part by the Laboratory Technology Research Division, and in part by the DOE Office of Science, Office of Basic Energy Sciences, Geosciences Research Program under Contract No. DE-AC0376SF00098.

SIGNIFICANCE OF FINDINGS

In spite of the limited nature of the RFS tests, which prevented us from acquiring data suitable for a direct demonstration of the wavefield transform, we did secure high-quality wideband data that confirmed the proper 84

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Earth Sciences Division Berkeley Lab

Energy Resources Program

THREE-DIMENSIONAL IMAGING OF GEOTHERMAL RESERVOIRS USING ACTIVE AND PASSIVE METHODS

Annual Report 1999 - 2000

Ernest L. Majer, Roland Gritto, Tom Daley, Ann Kirkpatrick and John Peterson RESEARCH OBJECTIVES

Contact: Ernest L. Majer, 510/486-6709, elmajer@lbl.gov

The overall objective of this research is to develop and apply passive (microearthquake (MEQ)) and active (3-D surface reflection, vertical seismic profiling (VSP) and cross-well) methods to characterize and monitor geothermal reservoirs. The application would be both for exploring and monitoring the performance of the resources.

activities has been possible through microseismic analysis. Future work will be carried on by The Geysers field operators to apply and refine the method. The 3-D seismic reflection work has shown that surface reflection methods show promise, but they must be modified for geothermal environments. The final data set represented a 3-D cube of the subsurface structure in the reservoir. Additionally, the travel times were used to perform tomographic inversions for velocity estimates to support the findings of the surface seismic imaging. The 3-D imaging shows promise for geothermal applications. It is clear that petroleum processing cannot be directly transferred to the geothermal case. However, much of the technology can be modified and adapted for geothermal applications. An example would be work in the oil and gas industry focused at fractured reservoirs. A detailed report has been issued by LBNL on this work (Feighner et. al. 1999).

APPROACH

The overall approach has been to use both passive and active methods to collect data over potential and producing geothermal reservoirs (mainly in The Geysers geothermal field in California, but other areas have also been investigated). The MEQ effort involves using state-of-the-art, high-resolution instrumentation to record three-component digital data at high frequencies (500 Hz) over tight arrays (10 to 15 stations over a 5 x 5 km area). The data are then inverted for location in space and time as well as velocity and attenuation structure. These data are then correlated with production data to infer reservoir parameters (flow paths, lithology and fluid content). Although the approach is still experimental, it may also be possible to map the high-permeability zones common to most geothermal reservoirs, including The Geysers, by detecting any statistical trend in microseismic source mechanics that would indicate that open space associated with irregularities along fracture planes was being created or destroyed during microseismic events. In terms of active work, we have been evaluating 3-D surface reflection methods at the Rye Patch, Nevada, geothermal field. LBNL has been cooperating with The Industrial Corporation (TIC) and Transpacific Geothermal Inc. (TGI) to evaluate and apply modern state-of-the-art seismic imaging methods for geothermal reservoir definition. The overall objective of the work was to determine if modern off-theshelf, commercially-available techniques in 3-D surface seismic profiling could be successfully applied in geothermal environments. If not, could they be modified to derive useful information on reservoir structure. Past efforts using 2-D seismic reflection have proved marginally successful in some cases, but due to extreme heterogeneity in many geothermal areas 2-D seismic have not been cost effective.

RELATED PUBLICATIONS

Daley, T.M., T.V. McEvilly and E.L. Majer, Analysis of P- and S-wave vertical seismic profile data from the Salton Sea Scientific Res., 93, drilling project, J. Geophys. B11,13025-13036, 1988. Feighner, M.A., R. Gritto, T.M. Daley, H. Keers and E.L. Majer, Three-dimensional seismic imaging of the Rye Patch Geothermal Reservoir, Berkeley Lab report LBNL-44119, 1999. Majer, E.L., T.V. McEvilly, F. Eastwood and L. Myer, Fracture detection using P-wave and Swave vertical seismic profiling at the Geysers, Geophysics, 53, 76-84, 1988.

ACCOMPLISHMENTS

In general, the MEQ work has shown that injection at wells resulted in higher levels of microseismicity, but the increased seismicity also corresponded to larger flow rates in the production wells. While there was not a lag time between increased water injection and increased steam production rates, there was up to several monthsâ&#x20AC;&#x2122; lag time between increased water injection and increased seismicity. It appears that there was a threshold of water injection which caused increased seismicity, but once the system was primed, lower injection rates also increased the seismicity (i.e., as injection continued, the lag time between injection and seismicity decreased).

ACKNOWLEDGEMENTS

We are grateful to Bill Teplow for his support in the interpretation of the seismic and tomographic data sets. This work has been supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Geothermal and Wind Technologies of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

SIGNIFICANCE OF FINDINGS

Overall, a clearer understanding of the effects of injection and production 85

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Energy Resources Program

HIGH RESOLUTION RESERVOIR CHARACTERIZATION

USING SEISMIC, WELL AND Don Vasco, Henk Keers, Lane Johnson and Akhil Datta-Gupta1 1Texas A&M University

Annual Report 1999 - 2000

DYNAMIC DATA

Contact: Don Vasco, 510/486-5206, dwvasco@lbl.gov

RESEARCH OBJECTIVES

Seismic imaging is a very powerful tool for obtaining high-resolution views of the subsurface. The current goal of this research project is to improve existing methods of seismic imaging, primarily by using the entire seismic waveforms rather than simply first arrival times. In our previous work, we developed efficient methods for utilizing dynamic reservoir data such as water-cut. The end goal of this project is an effective integration of seismic, well log and dynamic reservoir engineering data to image reservoir flow structure.

APPROACH/ACCOMPLISHMENTS

This year we have developed a method that efficiently models high-frequency seismic waveforms in heterogeneous media. This method make possible the efficient imaging of reservoir structure using seismic data. We have applied imaging techniques to a set of laboratory data in which seismic observations were used to monitor saturation changes in a clean sand. Cross-well seismic data were collected before and after injection of a hydrocarbon into a sand tank. We applied the waveform imaging technique to the two laboratory datasets. Three different types of wave propagation were assumed: acoustic, viscoacoustic and poroelastic. The three models were compared with each other and to the results from traveltime imaging.

SIGNIFICANCE OF FINDINGS

We have demonstrated the significance of the use of waveforms, as opposed to only traveltimes, in seismic imaging. Images based on seismic traveltimes only produce a velocity model. Estimation of attenuation or hydrological properties is more difficult and less reliable. Not surprisingly, the waveform imaging results in a more detailed, higher resolution model. The significant influence of attenuation is more surprising, and may provide a tool for detecting reservoir changes over time. Traveltime imaging is still useful as it provides an initial large-scale model for the waveform imaging. Inversion of laboratory data for parameters of hydrological importance, such as porosity and saturation, is the subject of ongoing research.

Figure 1. Velocity and attenuation model obtained using waveform inversion after injection of a water saturated sand with NAPL. Low velocities and high attenuation correlate with pockets of NAPL found in the sand after excavation.

transient pressure data: An asymptotic approach, Water Resources Research, in press. Vasco, D., and Karasaki, K., Pressure pulse imaging, J. of Hydrology, submitted.

RELATED PUBLICATIONS

Keers, H., D. Vasco and L. Johnson, Poroelastic crosswell imaging using asymptotic waveforms, Geophysics, submitted. Keers, H., D. Vasco and L. Johnson, Viscoacoustic crosswell imaging using seismic waveforms, Geophysics, in press. Keers, H., L. Johnson and D. Vasco, Acoustic crosswell imaging of seismic waveforms, Geophysics, in press. Vasco, D., and A. Datta-Gupta, Asymptotic solutions for solute transport: A formalism for tracer tomography, Water Resources Research, 35, 1-16, 1999. Vasco, D., S. Yoon, and A. Datta-Gupta, Integrating dynamic data into high-resolution reservoir models using streamline-based analytic sensitivity coefficients, Soc. Petr. Eng. Journal, 4, (4), 1999 . Vasco, D., and A. Datta-Gupta, Asymptotics, saturation fronts, and high resolution reservoir characterization, Transport in Porous Media, in press. Vasco, D., Karasaki, K., and Keers, H., Estimation of reservoir properties using

ACKNOWLEDGEMENTS

86

This work has been supported by the Assistant Secretary for Fossil Energy, Office of Natural Gas and Petroleum Technology, through the National Petroleum Technology Office, Natural Gas and Oil Technology Partnership, under U.S. Department of Energy Contract No. DE-AC03-76SF00098. Computations were carried out at the Center for Computational Seismology and the National Energy Research Scientific Computing Center at LBNL. H. Keers acknowledges the Miller Institute for Basic Research in Science for a postdoctoral fellowship. HTTP://WWW-ESD.LBL.GOV

Annual Report 1999 - 2000

Earth Sciences Division Berkeley Lab

Environmental Remediation Technology Program Terry Hazen

510/486-6223 tchazen@lbl.gov

T

he Environmental Remediation Technology Program (ERTP) conducts multi-disciplinary environmental research on characterization, monitoring, modeling and remediation technologies. This research is directed primarily at Department of Energy (DOE) and Department of Defense (DoD) waste site problems. Since many of the contaminants or closely related compounds found at these sites are also dominant at industrial waste sites, much of this research is also applicable to problems faced by the private sector and other government agencies. These projects are both basic and applied, and include everything from molecular studies to full-scale field deployments in all types of media (gas, water, sediment) in all types of environments (wet lands to deserts). This year’s major customers have been: DOE Office of Environmental Management, DOE Office of Science, Work for Others/DoD, and Work for Others (Industry/Other Government Agencies).

Industrial Areas in Poland in completing a fullscale demonstration of biopile (aeration) technologies for cleaning up a petroleum refinery waste lagoon. The demonstration has shown that both passive and active aeration strategies can meet clean-up standards for polycyclic aromatic hydrocarbons in the soil and that active aeration cuts the remediation time in half. This demonstration has been so successful that the petroleum refinery is commercializing the process for other refineries and fuel stations in Poland. ERTP also supports EM 50 with technical expertise via the Strategic Laboratory Council, the Oakland Site Technology Coordination Group, the multi-agency DNAPL Technology Advisory Group, the Subsurface Contaminant Focus Area (SCFA) Vadose Zone Book, the Lead Lab Council for SCFA, and the Hanford Vadose-GroundwaterRiver Integrated Program.

DEMONSTRATIONS AND DEPLOYMENT

ERTP supports DOE’s Office of Environmental Management in both the areas of Environmental Restoration (EM 40) and the Office of Science and Technology (EM 50). Earth Science Division (ESD) scientists directly supervise characterization, remediation and monitoring, and provide regulatory and permitting support to LBNL’s Environmental Health and Safety Department for all environmental problems on site. During this past year, the program demonstrated and deployed technologies for bioventing/soil vapor extraction of VOCs, and air sparging of solvent-contaminated groundwater. ERTP research on viscous liquid barriers for containment (patent issued) provides a great opportunity for containing and controlling solvent, metal and radionuclide contamination at waste sites—DOE’s greatest environmental cleanup problem. Indeed, this technology was deployed at Brookhaven National Laboratory this year to contain radionuclide contamination in the subsurface at one of their facilities. This year ERTP, in partnership with the Savannah River Technology Center and Florida State University, assisted the Institute for Ecology of

FIELD AND LABORATORY STUDIES

87

DOE’s Office of Science provides funding for several ERTP projects. The basic research projects funded in this area take advantage of the unique facilities at LBNL, such as the Advanced Light Source, where researchers look at the interaction between contaminants, water, and minerals at the microscale. ERTP has a project funded in the Natural and Accelerated Bioremediation Research HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Environmental Remediation Technology Program

(NABIR) program, which looks at mesoscale biotransformation dynamics as the basis for predicting core scale reactive transport of chromium and uranium.

Annual Report 1999 - 2000

calls for proposals, review documents and other web sites. In addition, the NABIR program office also organizes the NABIR annual investigators’ meeting with more than 120 participants and sessions for posters, presentations and breakout sessions. The NABIR program office produced a new NABIR Bioremediation Primer this year for the public, available in print or electronically on the NABIR home page. The program office assisted DOE-Headquarters in reviewing, evaluating and starting up the Field Research Center for the NABIR program at Oak Ridge National Laboratory.

FIELD DEMONSTRATIONS FOR DOD

Field tests at McClellan Air Force Base for the Department of Defense have shown that Vadose Zone Monitoring Systems (VZMS)—instrument packages consisting of tensiometers, suction lysimeters, gas samplers, pressure transducers and thermistors—permanently installed at multiple levels provide better monitoring of contaminants at waste sides. The field tests at McClellan AFB allowed identification of significant shallow sources of contamination.

WORK FOR INDUSTRY/OTHER AGENCIES

PARTNERS AND FUNDING

ERTP has researched selenium transport in the Grassland Water District for many years. Recent research has focused on better methods for compliance monitoring and management. The U.S. Bureau of Reclamation has sponsored this work in an effort to better manage selenium loading in the San Luis Drain. Microbial studies this year have shown that selenium intransit losses occur and that the fate of this selenium is bed sediments. Manipulation of the microbial ecology of the Drain may stimulate the bioremediation of selenium from the water, thereby reducing the mass loading of selenium to the San Joaquin River. ERTP also provides technical consultation to private industry and other government agencies on implementing LBNL- and DOE-patented technologies at private and government-owned sites. Private industry must have a license to the technology for use at private sites and all ERTP expenses are reimbursed by the company or other agency. Several contracts this year were executed for consultation regarding bioremediation and characterization. ERTP also provides technical advisory support for the Bay Area Defense Conversion Action Team (BADCAT) and the California Environmental Business Council (CEBC).

ERTP receives support from DOE programs in Office of Science and the Office of Environmental Management. The EM programs include the Environmental Management Science Program, the Subsurface Contaminant Focus Area, the Characterization, Monitoring, and Sensor Technology Crosscutting Program. The Office of Science funds the NABIR Program Office at LBNL; the Office of Science, Office of Biological and Environmental Research funds two environmental remediation projects. Support is also received from DoD, Cal-EPA, other DOE Labs, UC Berkeley and U.S. Bureau of Land Management. Other Work for Others in 1999 includes: Pacific Northwest National Laboratory, Radian International, Earthtech, Woodward & Clyde, Florida State University and IT Corporation. Partners include UC Berkeley, Stanford University, Westinghouse Savannah River Company, Idaho National Engineering Laboratory, Lawrence Livermore National Laboratory, Pacific Northwest National Laboratory, Utah State University, University of Nevada and University of Illinois.

NABIR PROGRAM OFFICE

ERTP continued to be the NABIR program office for the Office of Science. The NABIR program office maintains the NABIR web home page (www.lbl.gov/NABIR/) with links to investigators, program element managers, science team leaders, recent publications, annual meeting registration,

88

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Earth Sciences Division Berkeley Lab

Environmental Remediation Technology Program

BIOREMEDIATION, EDUCATION, SCIENCE AND TECHNOLOGY (BEST): A CONTINUED PARTNERSHIP

Annual Report 1999 - 2000

Terry Hazen

INTRODUCTION

Contact: Terry Hazen, 510/486-6223, tchazen@lbl.gov

BEST program undergraduates who are currently continuing their education or are in scientific careers: 172. New technologies • Developed, demonstrated and validated: in situ stable isotope monitoring system for petroleum hydrocarbon degradation at a DoD site; microbial community monitoring system for industrial activated sludge hydrocarbon and toxic metal treatment systems; in situ x-ray absorption spectroscopy method for toxic metals speciation in plant and microbial biomass; in situ low background gamma-ray spectroscopy method for quantitating toxic metals in biomass. • Designed, constructed, demonstrated and validated an Advanced Integrated Pond System for toxic metal and nitrogen removal from waste streams at 10,000 GPD. • Developed the first set of regulations and standards for certification of bioremedial processes. • Developed gene chip technology for genome-wide expression analysis of hazardous metal detoxification responses. • Developed genotyping and metabolic engineering technology to characterize and optimize the remediation of GTN explosives. New knowledge through scientific accomplishments • BEST student and faculty presentations at national and international scientific meetings (166 presentations); • BEST student and faculty publications and meeting abstracts (34 papers in peer reviewed journals and 41 abstracts); • Determined the molecular mechanisms involved in toxic metal valence biotransformation by microbial systems; • Developed ecophysiological community models for high pH PAH and PCP impacted environments; • Discovered the chemotactic nature of TNT compounds to large groups of bacteria.

Over the next 75 years, the U.S. government will undertake what has been called the largest civil works project in world history to restore the environment damaged by previous activities at federal sites, e.g., Department of Defense (DoD) military bases and Department of Energy (DOE) nuclear facilities. Legislative action has mandated pollution control measures and environmental restoration of hazardous waste at all sites. Estimates of total cleanup costs range from $500 billion to more than a trillion dollars. Some of the environmental damage is permanent: cleanup technologies either do not exist or are unable to remediate the contamination. For DoD bases being closed by the Base Realignment and Closure Program, all toxic sites must be remediated before being returned to public use. The pollutants at these sites include chlorinated hydrocarbons, metals, petroleum products, explosives, mixed waste and other organics. In response to these needs, the BEST Program, a partnership funded by DoD in 1996, has pioneered a new and successful model for environmental science and education with a highly integrated programmatic focus on the scientific and workforce needs of DoD. BEST partners include: • Lawrence Berkeley National Laboratory (LBNL) • Jackson State University, Mississippi (JSU) • University of Texas at El Paso (UTEP) • University of Southern Mississippi–Gulf Coast Research Laboratory (USM) • Ana G. Méndez University System, Puerto Rico (AGMUS) • University of California at Berkeley (UCB)

ACCOMPLISHMENTS

Since the inception of the BEST program, participants have achieved many major milestones and deliverables. A brief sampling is provided below. Education and training • Environmental science degree programs established at JSU, AGMUS, UTEP, and UCB; • Center for Environmental Bioremediation (CEB)–BEST seminar program (82 seminar presentations; 34 key seminar speakers video taped for distribution and use in special topics courses); • Rotating Scholars program (10 outstanding CEB – BEST seminar speakers visited program member universities and taught students on site); • K-12 education: high school and middle school teacher summer bioremediation science workshops; • BEST “Principles of Bioremediation” video course that includes laboratory instructions (distributed to program member universities, federal agencies and DoD laboratories); • BEST collaborative research program (42 faculty participants); • BEST exchange research program (10 faculty participants, 40 student participants); Workforce diversity • Participants who went into academia: 40; government: 2; industry: 8; and professional schools: 4

ACKNOWLEDGEMENTS

89

This work has been supported by the U.S. Department of Defense, U.S. Army Corps of Engineers.

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Earth Sciences Division Berkeley Lab

Environmental Remediation Technology Program

CO-METABOLIC BIOLOGICAL REACTIONS FOR THE TREATMENT MTBE-CONTAMINATED GROUNDWATER

OF

Annual Report 1999 - 2000

William T. Stringfellow

RESEARCH OBJECTIVES

Contact: William T. Stringfellow, 510/486-7903, wstringfellow@lbl.gov

Approximately 70% of all gasoline in the United States contains methyl tert-butyl ether (MTBE). As a consequence, MTBE has become a widespread groundwater contaminant. Biological treatment of MTBE-contaminated groundwater has only recently been considered as a potentially applicable technology. Several investigators have been able to maintain MTBE-biodegrading treatment systems in the laboratory. In all cases the reactors exhibited slow growth, were difficult to start, and were generally unstable, being easily subject to a loss of MTBE treatment efficiency. The objective of the research presented here was to determine a biological process by which MTBE-contaminated groundwater could be treated. Once the mechanism was determined, field and laboratory tests were conducted to evaluate improved techniques for MTBE biological treatment.

APPROACH/ACCOMPLISHMENTS

The original hypothesis of this project was that organisms able to grow on MTBE as a sole carbon and energy source could be used in MTBE treatment. Enrichments from groundwater treatment systems produced three strains of bacteria and a fungus that were able to degrade MTBE in liquid culture. The growth of bacteria on MTBE was poor. In many cases, MTBE enrichments would not maintain MTBE degrading activity after multiple transfers. The poor growth, low activity and instability of the MTBE-degrading cultures raised several issues concerning the utility of growth-based transformation processes in MTBE biotreatment. It was proposed that co-metabolic biodegradation could be a more reliable mechanism for MTBE biotreatment. The focus of this research shifted to determining what supplemental carbon sources could serve as co-metabolites for MTBE degradation. Enrichment cultures grown on iso-pentane consistently demonstrated MTBE degradation activity (Figure 1). MTBE degradation appears to be a constant characteristic of iso-pentane degraders. Experiments and field tests are being conducted to examine the use of iso-pentane as a co-substrate for MTBE degradation. Tests in laboratory reactors have shown that iso-pentane addition can stimulate MTBE removal (data not shown).

Figure 1. Degradation of MTBE by an iso-pentane enrichment. Mean plotted with error bars of one standard deviation.

Wickramanayake, et al. (eds.), Bioremediation and Phytoremediation of Chlorinated and Recalcitrant Compounds, pp. 175-181, Battelle Press, Columbus, Ohio, Berkeley Lab report LBNL-45487, 2000. Stocking, A.J., R.A. Deeb, A.E. Flores, W.T. Stringfellow, J. Talley, R. Brownell and M.C. Kavanaugh, Bioremediation of MTBE: A practical perspective, in Biodegradation (in press), Berkeley Lab report LBNL-45016, 2000. Stringfellow, W.T., R.D. Hines and S.T. Kilkenny, Applying co-metabolic biological reactions for the ex-situ treatment of MTBE contaminated groundwater, Berkeley Lab report LBNL45018Abs, American Chemical Society National Meeting, San Francisco, Calif., March 26-30, 2000. Stringfellow, W.T., Using iso-pentane to stimulate MTBE biodegradation in groundwater treatment systems, Berkeley Lab report LBNL45017Abs, EPA MTBE Biodegradation Workshop, Cincinnati, Ohio, Feb. 1 â&#x20AC;&#x201C; 3, 2000.

SIGNIFICANCE OF FINDINGS

Laboratory and field data support the argument that the primary mechanism for MTBE removal in fluidized-bed reactors treating contaminated groundwater containing gasoline hydrocarbons will be co-metabolic biodegradation. Gasoline range alkanes, particularly iso-pentane, can serve as reliable co-substrates for the stimulation of MTBE biodegradation. Future research will focus on the use on iso-pentane as a co-substrate for MTBE degradation under field conditions.

ACKNOWLEDGEMENTS

RELATED PUBLICATIONS

This work has been supported by Kinder Morgan Energy Partners and Envirex/U. S. Filter Co.

Stringfellow, W.T., R.D. Hines, D.K. Cockrum and S.T. Kilkenny, Factors influencing biological treatment of MTBE in fixed film reactors, in G.B. 90

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Earth Sciences Division Berkeley Lab

Environmental Remediation Technology Program

AEROBIC LANDFILL BIOREMEDIATION

Annual Report 1999 - 2000

Terry C. Hazen, Curtis M. Oldenburg, Sharon E. Borglin and Peter T. Zawislanski Contact: Terry C. Hazen, 510/486-6223, tchazen@lbl.gov

RESEARCH OBJECTIVES

The purpose of this research is to determine the critical physical, chemical and biological processes that control aerobic landfill bioremediation. Currently, landfills are managed under CFR Subtitle D and require liners at the bottom to capture leachate, and impermeable caps at the top to limit infiltration. As such, landfills are "dry tombs," i.e., anaerobic and dry, with relatively slow biodegradation of the organic fraction of the waste and significant production of methane, an important greenhouse gas. An alternative approach that has shown promise in speeding up biodegradation and eliminating methane is aerobic biostimulation of landfills. In aerobic biostimulation, air and leachate are injected into the waste, resulting in relatively fast aerobic biodegradation and associated compaction, and no methane production. Our research is directed at understanding the process of aerobic landfill bioremediation so that optimal engineering designs can be developed.

APPROACH

Figure 1. Schematic of laboratory lysimeter for modeling biodegradation of municipal sold waste.

The complexity of landfills and landfill materials, as well as a host of practical and health-related issues, necessitates laboratory and modeling approaches as the first line of investigation as opposed to in situ landfill investigations. Our approaches to date have included literature reviews, design and construction of laboratory lysimeters and coding of biodegradation processes for numerical simulation.

SIGNIFICANCE OF FINDINGS

To date our findings are limited to results of literature surveys, experiment design, and numerical experiments. Although batch models of biodegradation of landfill materials have been developed and applied, no one has modeled unsaturated flow and transport with landfill biological processes. The differing needs of batch and fully 3-D simulations require careful consideration of oxygen and nitrogen components in air for modeling aerobic biodegradation processes.

ACCOMPLISHMENTS

In the laboratory, we are preparing several 55-gallon plexiglass lysimeters for monitoring the biodegradation of a typical mixture of materials modeled after municipal solid waste, including: paper (40% by weight), food waste (12%), garden waste (10%), glass (9%), plastic (8%), metal (7%), wood (3%) and other (11%). The lysimeters will be subjected to various combinations of leachate recirculation along with air injection (see Figure 1). The lysimeters will be instrumented for temperature, moisture content and density, along with gas and leachate composition and flow rates. We will use a neutron probe for monitoring moisture content and compaction, as well as visual inspection through the clear walls of the lysimeter. Aerobic biodegradation is sensitive to air injection and leachate recirculation, the details of which will be investigated in the laboratory experiments. On the modeling front, we are adding capabilities for modeling landfill biodegradation processes to the TOUGH2 reservoir simulator. The new module considers six components (water, acetic acid, carbon dioxide, methane, nitrogen, oxygen) and heat. The acetic acid is proxy for all biodegradable organic material. The model considers aerobic and anaerobic biodegradation depending on the local oxygen concentration. A full Monod kinetic model has been coded to simulate the biological reactions. All of the existing flow and transport capabilities of TOUGH2 will be retained in the new module. Preliminary simulations reveal that nitrogen and oxygen must be modeled separately, due to the local nature of oxygen content when aerobic processes consume oxygen and lead to relative increases in nitrogen in the gas phase.

RELATED PUBLICATIONS

Oldenburg, C.M., T.C. Hazen and S.E. Borglin, Simulation of landfill bioreactors, Berkeley Lab report, in preparation. March, J., M. Hudgins and T.C. Hazen, Aerobic landfill bioreactor demonstration, Environ. Sci. Technol., submitted.

ACKNOWLEDGEMENTS

91

This work has been supported by the Laboratory Directed Research and Development Program of Lawrence Berkeley National Laboratory under U.S. Department of Energy Contract No. DE-AC0376SF00098.

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Earth Sciences Division Berkeley Lab

DEVELOPMENT

Environmental Remediation Technology Program

OF METHODS FOR EXTRACTING DNA FROM BACTERIAL Tamas Torok, Jennie C. Hunter-Cevera and Terrance Leighton Contact: Tamas Torok, 510/486-5808, ttorok@lbl.gov

RESEARCH OBJECTIVES

The Federal Bureau of Investigation (FBI) has been mandated to develop and establish a wide range of unprecedented capabilities for providing scientific and technical forensic services to investigations involving hazardous chemical, biological and radiological materials, including extremely dangerous chemical and biological warfare agents. Presently, there are many technological shortfalls that must be addressed in order to achieve the required capabilities. Certain microbial spores, such as those of Bacillus anthracis, may be attractive to terrorists as weapons of mass destruction because they are easily produced, easily transported, resistant to environmental and other forms of degradation, and extremely hazardous. To date, spore structural signature assays have not been developed for use in a forensic scenario. The objective of this project was to develop methods for extracting PCRamplifiable DNA from endospores of Bacillus anthracis in sufficient quality and quantity for use in DNA-based forensic assays.

Annual Report 1999 - 2000

SPORES

A

B

APPROACH

At the sponsor’s special request, we had to avoid any toxic and hazardous chemicals or sophisticated instrumentation. Therefore, we needed to develop: • rapid spore disruption methods; • DNA capture and purification methods for spore extracts; • DNA quantitation methods for spore extracts; • assays and protocols to determine the efficacy and efficiency of DNA extraction and the reproducibility of results; • methods for the analysis of forensic sample matrices.

Figure 1. B. anthracis strain AMES showing vegetative cells, cells with spores (A) and free fully mature bacterial endospores (B) by phase contrast microscopy.

ACCOMPLISHMENTS

We prepared a critical state-of-the-art review of the chemical structure of bacterial endospores and the current methods and their limitations with regard to spore disruption, DNA extraction and purification. We identified sample preparation problems and made recommendations for the development of improved, reliable and reproducible methods that can be employed under real world forensic conditions. We developed methods used to prepare purified spores, optimized the ballistic disruption technique for crude spore preparation, and modified protocols for DNA capturing and purification. Also, we adapted qualitative methods for spore disruption verification and used fluorescence detection for rapid quantitative DNA concentration measurement. Using B. anthraci-spiked soil samples, we verified the efficacy and efficiency of the developed protocols. We also used a wide range of physical and chemical spore damaging factors and tested the developed methods. In a two-day session, we trained molecular biologist colleagues from the FBI in applying our standard operating procedures (SOPs).

SIGNIFICANCE OF FINDINGS

The developed protocols enable the FBI and other agencies to handle real world forensic samples and extract PCR-amplifiable DNA from bacterial endospores with high reproducibility under field conditions. The SOPs are included in the final report, which fully documents the project.

ACKNOWLEDGEMENTS

This Work for Others project has been supported by the Hazardous Materials Response Unit, Laboratory Division, Federal Bureau of Investigation (FBI).

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Earth Sciences Division Berkeley Lab

BIOTRANSFORMATION

Environmental Remediation Technology Program

Annual Report 1999 - 2000

OF METAL CONTAMINANTS IN SOILS/SEDIMENTS: CHROMIUM Tetsu Tokunaga, Jiamin Wan, Egbert Schwartz,1 Dominique Joyner, Stephen Sutton,2 Matt Newville,2 Mary Firestone1 and Terry Hazen 1UC Berkeley; 2University of Chicago

RESEARCH OBJECTIVES

Contact: Tetsu Tokunaga, 510/486-7176, tktokunaga@lbl.gov

Understanding transport and reactions of metal contaminants such as chromium in soils is complicated by small-scale variations in physical, chemical and microbiological characteristics. The fate of elements with highly redox dependent solubilities can be especially complex because strong redox potential gradients can develop over very short distances. In nature, Cr exists in the III and VI oxidation states, with the majority of the former species being stable solids, and the majority of the latter being more soluble and mobile. Transport and reactions of chromium in soils are critical concerns because of the carcinogenic effects of Cr(VI). Cr reduction rates reflect interdependent influences of physical, geochemical and microbial processes. The overall process tested in this study is the response of soil aggregates (cohesive structural units comprised of many primary mineral particles) to a Cr(VI) contamination event.

Figure 1. Profiles of Cr(VI) and Cr(III) in a soil aggregate, 23 days after exposure to Cr(VI) at the surface (x = 0 mm). The aggregate surface was in contact with a 260-ppm Cr(VI) solution for 2.5 days.

APPROACH

The interdependent influences that sediment structure and microbial communities have on transport and reduction of chromate are being investigated in soil aggregate (Altamont clay) microcosms. These microcosms were typically 30 mm in length, with an aerobic boundary at one end, and a potentially anaerobic core region on the opposite end. The soils were saturated with solutions containing 0 to 800 ppm organic carbon (OC). More rapid microbial growth, hence more reducing conditions, result from OC amendments. Following 14 days of incubation, the exterior boundary of each microcosm was exposed with up to 5200 ppm Cr(VI) solution for three days, representing a contamination event. Micro-XANES (x-ray absorption near edge structure) spectroscopy was used because of interest in Cr oxidation state determination, and the need for spatially-resolved measurements. Micro-XANES profiles of Cr(VI) and Cr(III) were measured at the GSECARS microprobe beamline (Advanced Photon Source, Argonne National Laboratory). Aggregates were later sectioned for characterization of microbial population profiles and other chemical analyses.

Direct counting of microbial populations in the sediment microcosms showed higher population densities in the outer layers due to the availability of oxygen.

SIGNIFICANCE OF FINDINGS

These results show how a metal contaminant, Cr(VI), can become very locally reduced within soil aggregates. In systems with high microbial activity, reducing conditions can develop at the mm scale. The spatial resolution needed for understanding such systems is determined by characteristic transport distances, and these distances are determined by diffusivities and reaction times. The need for measurements with at least mm-scale spatial resolution was demonstrated for highly nonequilibrium reactive transport of Cr within soil aggregates. In such systems, coarser scale volume-averaged chemical speciation will not permit mechanistic characterization of reactive transport.

ACCOMPLISHMENTS

Redox measurements in the sediment microcosms showed lower potentials in systems with higher OC addition, and more oxidizing conditions within 2 to 4 mm of aggregate surfaces. Micro-XANES spectroscopy showed short Cr penetration distances, with abrupt rather than diffuse termination, and direct evidence of nearly complete Cr(VI) reduction to Cr(III). The extent of Cr transport into sediment blocks was far less than expected by diffusion without reduction, inversely related to OC amendment, and proportional to the boundary Cr(VI) concentration. Microbial communities were characterized with DNA fingerprints, direct counting and enrichment culturing. The microbial community composition in the exposure region is different from those in sediments taken from greater depth. Several populations appear only in soil that was exposed to Cr, suggesting that they are chromium resistant and that they may play an active role in Cr reduction.

ACKNOWLEDGEMENTS

We thank Keith Olson, Andrew Mei and H. Scott Mountford of LBNL, and GSECARS staff for assistance. This work has been supported by the Office of Science, Office of Basic Energy Sciences, Geosciences Research Program, and NABIR program, of the U.S. Department of Energy under Contract No. DE-AC0376SF00098. 93

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Earth Sciences Division Berkeley Lab

Environmental Remediation Technology Program

KESTERSON RESERVOIR ECOLOGICAL RISK ASSESSMENT

Annual Report 1999 - 2000

Peter T. Zawislanski, Sally M. Benson, Tetsu K. Tokunaga and Keith R. Olson Contact: Peter T. Zawislanski, 510/486-4157, ptzawislanski@lbl.gov

RESEARCH OBJECTIVES

Kesterson Reservoir, California, which was contaminated with selenium (Se) in the late 1970s and early 1980s, was dried out and partially filled in 1988 with the intent of eliminating aquatic habitat that presented potential risks to wildlife. It was recognized, however, that during years of aboveaverage rainfall, ephemeral pools that persisted from winter to early spring were likely to form. The years immediately following the filling operation, 1988-1992, had lower than average rainfall and consequently did not provide the observations and data needed to assess the risk to wildlife. Since 1993, several years with significantly higher than average rainfall have occurred (1993, 1995 and 1998), providing the opportunity to collect the data needed. In particular, the 1998 El Niño rainfall represents an extreme event that helps bound the range of likely conditions at Kesterson. LBNL researchers have been working to provide chemical and physical input to the ecological risk assessment model, which is being jointly prepared with the consulting company of CH2MHill. The LBNL research objectives were: • To calculate statistical distributions of water-soluble selenium in soils. • To make long-term predictions of the extent and duration of ponding and ephemeral pool formation. • To predict ephemeral pool selenium concentrations.

APPROACH AND ACCOMPLISHMENTS

Statistical distributions of soil selenium concentrations were calculated by habitat (open, grassland and filled areas), and by location within the reservoir. Statistical analyses of temporal trends along with modeling of selenium net oxidation rates strongly suggest that soluble selenium levels in surface soils will not change to an extent which would significantly affect long-term ecological risk. The onset and duration of ponding were evaluated using a simple model that has been used successfully to estimate ponding at Kesterson for the period from 1990 to 1999. At Kesterson, ponding is largely determined by wet-season weather patterns. Since the meteorological database at Kesterson Reservoir is limited to only the past 16 years, weather data from nearby stations (Los Baños and Gustine), going back 126 years, was used to improve rainfall probability estimates. The model was also extended to provide estimates of areal ponding (Figure 1a). Selenium concentrations in ephemeral pools were estimated based on the development of a transfer factor that relates the water-soluble selenium concentration in the top 15 cm of soil to the pool water concentration (Figure 1b). The transfer factor was derived from available field and laboratory measurements, augmented by additional soil sampling at ephemeral pool sites.

Figure 1. (a) Probability of a certain fraction of Kesterson Reservoir being ponded during the rainy season. (b) Calculation of soil-to-pool transfer factor based on typical pool values and soluble Se in surface soils.

tionally wet years, which may require preventative action. This approach has provided the first comprehensive long-term prediction of Se exposure risk to both aquatic and terrestrial animals.

RELATED PUBLICATIONS

Zawislanski, P.T., T.K. Tokunaga, S.M. Benson, H.S. Mountford, H. Wong, T. Alusi, R. Terberg and K. Olson, Hydrological and geochemical investigations of selenium behavior at Kesterson Reservoir, progress report to the U.S. Bureau of Reclamation, Berkeley Lab report LBNL-43535, 1999.

SIGNIFICANCE OF FINDINGS

The statistical distributions of soil Se, soluble Se, ponding duration and extent, and soil-to-pool water transfer factor are key input parameters to the ecological risk assessment model. The model has shown that long-term Se exposure is ecologically insignificant during most years, due primarily to the small extent and short duration of ponding. Exposure increases during excep-

ACKNOWLEDGEMENTS

94

This work has supported by the U.S. Bureau of Reclamation (U.S. Department of Interior Interagency Agreement 99AA200176), under U.S. Department of Energy Contract No. DE-AC03-76SF00098. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Environmental Remediation Technology Program

SUBSURFACE IMAGING

FOR

CHARACTERIZING HETEROGENEITY

Annual Report 1999 - 2000

Affecting Microbial Transport Properties in Sediments Ernest L. Majer, Susan Hubbard, Ken Williams, John Peterson and Jinsong Chen1 1UC Berkeley OBJECTIVE

Contact: Ernest L. Majer, 510/486-6709, elmajer@lbl.gov

laboratory information to characterize the properties affecting chemical and bacterial transport, which can be imaged with in situ characterization methods. Efforts in this research have been in defining the hierarchy of physical characteristics that control transport and geophysical properties at the laboratory and field scale. Several other imaging techniques (radar, self potential, DC resistivity) are also being used to obtain a more direct measure of physical and microbial and chemical properties.

Although heterogeneity occurs at almost every scale, it is not known how key physical and chemical parameters affect microbial behavior at different scales in a natural environment. A primary goal is to relate physical and chemical parameters—using geophysical methods (i.e., parameters we have experience measuring in situ)—to the significant microbial properties, and thus predict their behavior in the subsurface.

APPROACH

This research involves an integrated approach to characterizing and identifying the fundamental properties and scales necessary to image heterogeneities using geophysical methods that may control transport in nearsurface sedimentary media. Particular emphasis is placed on understanding transport behavior relative to understanding subsurface microbial behavior. The approach uses controlled small-scale field sites and supplementary

ACCOMPLISHMENTS

Work in the past year has focused on using seismic and radar results to infer flow properties at the Oyster Site in Virginia as part of the Department of Energy’s NABIR program in bacterial transport. Geophysical properties are correlated to flow and transport properties affecting flow through a geostatistical approach. Also being investigated is the possibility of direct detection of microbes using geophysical methods. This involves monitoring electrical signals during bacterial injections. Initial results are promising. The characterization at this site is fully described at http://www-esd.lbl.gov/people/shubbard/web_page.

ACKNOWLEDGEMENTS

This work has been supported by the U.S. Department of Energy, Office of Biological and Environmental Research, Environmental Sciences Divison, Natural and Accelerated Bioremedation Research Program under Contract No. DE-AC03-765F0098.

Figure 1. The top of the figure is an example of hydraulic conductivity estimates obtained using radar tomographic data at the DOE Bacterial Transport Site in Oyster, VA. Both bromide and bacterial tracers were injected into the subsurface at the annotated injection zone (IZ) location. As shown by the subsequent bromide and bacterial breakthrough concentration data collected downgradient at 12, 48 and 200 hours after injection, the figure suggests that the physical heterogeneity predicted using the geophysical data influences both bromide and bacterial transport. By comparing the relative breakthrough of the conservative chemical and bacterial tracers compared to the estimated physical heterogeneity, we can also investigate the influence of chemical heterogeneity on bacterial transport at the Oyster Site.

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Earth Sciences Division Berkeley Lab

Environmental Remediation Technology Program

CARBON ISOTOPE MONITORING

OF BIOREMEDIATION OF CHLORINATED Mark E. Conrad, Donald L. Song and Lisa Alvarez-Cohen1 1University of California at Berkeley

Annual Report 1999 - 2000

SOLVENTS

Contact: Mark E. Conrad, 510/486-6141, msconrad@lbl.gov

RESEARCH OBJECTIVES

Chlorinated solvents are common groundwater contaminants. They are extremely difficult to remove from groundwater using standard remedial techniques such as pump-and-treat. In situ bioremediation of these compounds represents an attractive alternative. However, because these processes occur underground, they are very difficult to monitor. One promising technique for monitoring subsurface microbial activity is to measure the carbon isotopic compositions of the contaminants and their degradation byproducts. Microbial degradation of organic compounds favors 12C bonds rather than 13C bonds. This causes the products to be depleted in 13C and the substrates to become enriched in 13C. As a result, shifts in the carbon isotope ratios (δ13C values) can be used to track these processes, provided the magnitude of the isotopic shift is known. The purpose of this research is to quantify the carbon isotope fractionation caused by biodegradation of chlorinated solvents and demonstrate the use of these results for monitoring in situ biodegradation of these compounds.

Figure 1. Changes in the concentrations and δ13C values of TCE and its byproducts during reductive dechlorination by bacteria in laboratory cultures.

APPROACH

A combination of laboratory and field studies is being used to study carbon isotope monitoring of bioremediation of chlorinated solvents. Laboratory experiments with organisms known to degrade perchloroethene (PCE) and trichloroethene (TCE) are being conducted. Previous studies have shown that PCE and TCE can be degraded under anaerobic conditions via a process called reductive dechlorination, whereby microorganisms sequentially replace chlorine atoms with hydrogen atoms. In addition, TCE can be aerobically biodegraded directly to CO2, Cl- and H2O. Field monitoring of the δ13C values of chlorinated solvents is being carried out at several sites, including the TAN site at the Idaho National Engineering and Environmental Laboratory (INEEL), a plume of mixed chlorinated solvents at LBNL and Site 300 at the Lawrence Livermore National Laboratory (LLNL).

SIGNIFICANCE OF FINDINGS

The findings of this work demonstrate the potential for using carbon isotope monitoring to track bioremediation of chlorinated solvents. These results can be used to gain regulatory acceptance for in situ bioremediation of chlorinated compounds.

RELATED PUBLICATIONS

Conrad, M.E., D.J. DePaolo, D.L. Song and E. Neher, Isotopic evidence for groundwater flow and biodegradation of organic solvents at the Test Area North site, INEEL, in Ninth Annual V.M. Goldschmidt Conference, pp. 58-59, LPI Contribution No. 971, Lunar and Planetary Institute, Houston, 1999. Song, D.L., L. Alvarez-Cohen, M.E. Conrad and K. Sorenson, Monitoring of enhanced in-situ bioremediation of trichloroethylene using stable carbon isotopes, Program and Abstracts for the 4th International Symposium on Subsurface Microbiology, Vail, Colo., 1999.

ACCOMPLISHMENTS

Our laboratory experiments have demonstrated that reductive dechlorination of TCE causes significant shifts in the δ13C values isotopic fractionation during each step. This leads to big changes in the δ13C values of the residual substrates that can be related to the degree of biodegradation that has occurred. The results of this experiment are similar to results obtained for other experiments with reductive dechlorination. The shifts observed during a series of preliminary experiments with aerobic degradation of TCE and its byproducts have found much smaller carbon isotope shifts than these. The δ13C values of TCE and its byproducts were measured during a pilot study of enhancing bioremediation of TCE by injecting lactate into a plume at the INEEL. The results were similar to the laboratory results, demonstrating that complete reductive dechlorination of TCE is occurring at the site. At LBNL, the δ13C values of PCE and TCE are very different in the core of the plume, indicating that they are derived from separate sources. Down-gradient, however, the δ13C values of both compounds shift to higher values as they disappear, suggesting that natural reductive dechlorination is taking place in the plume.

ACKNOWLEDGEMENTS

96

This work has been supported by the LBNL site restoration program, and the Office of Environmental Management, Environmental Management Science Program of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Environmental Remediation Technology Program

STABLE ISOTOPIC STUDIES AT

THE TAN SITE OF INEEL, Mark Conrad and Donald DePaolo

Contact: Mark Conrad, 510/486-6141, msconrad@lbl.gov

RESEARCH OBJECTIVES

The purpose of this project was to explore and refine applications of isotope measurements for guiding environmental remediation strategies. The isotopic compositions of samples from field sites were analyzed to address both basic scientific issues and site-specific problems. Initial efforts were concentrated on two sites at the Idaho National Engineering and Environmental Laboratory (INEEL). During the final year of the project, the focus of work was shifted to the Hanford site in Washington. This contribution summarizes the results of work done on the TAN (Test Area North) Site in Idaho, a 2 km-long plume of mixed wastes containing low-level radionuclides, sewage and chlorinated solvents that were injected into the groundwater between 1955 and 1972. Our first objective was to determine the primary factors affecting regional groundwater flow at the TAN site. The direction of groundwater flow in the Snake River Aquifer is generally from northeast to southwest, but at the TAN site, groundwater flows eastward, then southeastward. The second objective was to evaluate the evidence for natural degradation of trichloroethene (TCE) in the TAN plume. The third objective was to monitor an enhanced bioremediation experiment, using carbon isotope ratios of TCE and its products to evaluate the extent of degradation.

CENTRAL IDAHO

Annual Report 1999 - 2000

The TCE concentrations in the TAN plume decrease much more quickly than the strontium isotope ratios, which indicates that rapid degradation of TCE is occurring in the plume, but not by what mechanism. However, monitoring of the δ13C compositions of TCE and the intermediary byproducts of reductive dechlorination during the enhanced bioremediation experiment confirmed that complete reductive dechlorination of the TCE was occurring.

SIGNIFICANCE OF FINDINGS

The results demonstrate that isotopic measurements can be used to help answer questions of critical importance for environmental management. Our studies show that natural biodegradation of chlorinated solvents can be documented by carbon isotope ratios and that engineered biodegradation can be verified by measurements of natural isotopic tracers. Natural isotopic tracers can be used in lieu of injection experiments for characterization of groundwater systems. The studies also produced basic field data applicable to understanding unsaturated zone hydrology and the potential for subsurface biologic activity in arid environments.

APPROACH

We used measurements of hydrogen (δD) and oxygen (δ18O) isotope in waters, stable carbon (δ13C) and radiocarbon (14C) in dissolved inorganic carbon compounds (DIC), the 87Sr/86Sr ratios of dissolved strontium, and the δ13C values of chlorinated solvents. Hydrogen and oxygen isotope measurements can be used to identify subsurface water that has undergone extensive evaporation at the surface. Carbon isotope measurements of DIC and chlorinated solvents can be used to identify the results of biodegradation of organic materials. The 87Sr/86Sr ratios of dissolved strontium is used to determine the recharge area of groundwaters and as a monitor of dilution of the contaminant plume by ambient groundwater.

RELATED PUBLICATIONS

Conrad, M.E., A.S. Templeton, P.F. Daley and L. Alvarez-Cohen, Seasonally-induced fluctuations in microbial production and consumption of methane during bioremediation of aged sub-surface refinery contamination, Environ. Sci. Technol. 33, 4061-4068, 1999. Johnson, T.M., and D.J. DePaolo, Interpretation of isotopic data in groundwater-rock systems: model development and application to Sr isotopic data from Yucca Mountain, Water Resources Res., v. 30, p.1571-1587, 1994.

RESULTS

The 87Sr/86Sr, δ18O, and δD data indicate that groundwaters in the TAN area have three sources. The water in the shallow aquifer containing the TCE plume comes from local infiltration of playa water derived ultimately from the Big Lost River. Water beneath the confining layer has two sources, that to the northeast is derived from Birch Creek, and that to the southwest has an unidentified source with lower 87Sr/86Sr (< 0.7096). The d18O values of the samples have a relatively large range of values (-15.3‰ to -18.5���) that generally decrease from west to east. The δ18O and δD values show a trend suggesting evaporation at low humidity, also indicating the playa as a source. The Sr isotope data also show that the low-87Sr/86Sr waters from the southwestern source are upwelling through the confining layer in the same area where the highest δ18O values are found. It may be the low-87Sr/86Sr waters or the infiltrating playa waters that are responsible for redirecting groundwater flow eastward.

ACKNOWLEDGEMENTS

This work has been supported by the Office of Environmental Management, Environmental Management Science Program of the U.S. Department of Energy under Contract No. DEAC03-76SF00098. 97

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Earth Sciences Division Berkeley Lab

Environmental Remediation Technology Program

PREFERENTIAL FLOW

IN A CONTAMINATED VADOSE ZONE Christine Doughty, Curtis M. Oldenburg and Peter T. Zawislanski

Annual Report 1999 - 2000

Contact: Christine Doughty, 510/486-6453, cadoughty@lbl.gov

RESEARCH OBJECTIVES

Understanding vadose zone flow and transport is important for prioritizing remedial actions at large government, military and industrial sites in the western United States, where multiple contamination problems compete for scarce financial resources. We investigated whether localized volatile organic contaminants (VOCs) in the shallow subsurface migrate through 30 m of sandy vadose zone to cause the observed widespread contamination of an underlying aquifer at a large government site in the Central Valley, California.

APPROACH

To assess the contribution of VOCs from a single, lightly contaminated site from among more than 250 potential sources of VOCs within a radius of 5 km, we installed a vadose zone monitoring system (VZMS), extending from the surface to the water table, and collected data for two years. In addition to field monitoring, we carried out enhanced data analysis that consisted of multiphase flow and transport modeling to help interpret observations and make quantitative predictions of system behavior.

Figure 1. Simulated liquid saturation profile and gasphase TCE concentration profiles (lines) at the end of 30-year simulations of contaminant evolution (1969-1999). Observed gas-phase TCE concentrations at two wells (open or filled symbols) for a series of times in late 1998 and early 1999.

ACCOMPLISHMENTS

Diverse data from 13 depths in two different VZMS wells were collected in situ, including moisture content, gas- and liquid-phase pressure, VOC concentrations and air permeability, supplemented by laboratory analysis of split-spoon and core samples. Observations of VOC concentrations and accompanying modeling suggest that VOCs are localized near the surface, VOC movement is slow and the primary loss mechanism is to the atmosphere, with smaller transport to the underlying groundwater. In contrast, observations of moisture content and gas pressure variations at depth, laboratory measurements of hydrologic properties and natural-state modeling suggest that percolation should be large enough to produce significant, ongoing downward movement of dissolved VOCs. We reconcile these contradictory findings by hypothesizing a heterogeneous vadose zone, with preferential flow in fast flow paths interspersed among isolated sediment blocks. A numerical model embodying this concept is able to reproduce all the observed data collected by the VZMS. A profile illustrating data and modeling results is shown in Figure 1.

porting evidence arises from diverse observations, including the moisture profile/percolation rate relationship, transient gas-pressure responses, and VOC concentration profiles. Our work demonstrates the importance of coupled data collection and interpretation in order to develop insight into complex vadose zone systems.

RELATED PUBLICATION

Doughty, C., C.M. Oldenburg and P.T. Zawislanski, Analysis of vadose zone data from a contaminated site: indirect evidence for preferential flow, Berkeley Lab report LBNL45319, 2000.

SIGNIFICANCE OF FINDINGS

The long-term prediction of VOC transport in the vadose zone is often challenging because of the spatial heterogeneity of both the hydrogeologic characteristics and the VOC plume. Data collection or modeling alone cannot unravel complex system behavior and its implications for remediation and contaminant transport. Using data from the VZMS with closely coupled data analysis by multiphase flow and transport simulation, we have developed considerable insight into the VOC distribution at the site of concern. While no direct evidence has been found for the existence of preferential flow, we feel that a body of circumstantial evidence supports it. The sup-

ACKNOWLEDGEMENTS

This work has been supported by the U.S. Department of Defense under a contract to Lawrence Berkeley National Laboratory, managed for the U.S. Department of Energy under Contract No. DE-AC0376SF00098. 98

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Earth Sciences Division Berkeley Lab

CHAOTIC MODELS

RESEARCH OBJECTIVE

OF

Environmental Remediation Technology Program

Annual Report 1999 - 2000

DRIPPING WATER FROM A FRACTURE UNDER PONDED INFILTRATION AT HELL'S HALF ACRE, IDAHO Boris Faybishenko

Contact: Boris Faybishenko, 510/486-4852, bfayb@lbl.gov

Preliminary analysis of the results of infiltration tests from the Hell’s Half Acre (HHA) field site, Idaho, showed that under some conditions, flow in fractured rocks can be described using chaotic models (Podgorney et al., 2000). The objective of this project is to perform a nonlinear dynamical analysis of the time variations of infiltration and outflow rates and dripping water phenomena observed during the HHA tests in order to determine phenomenological models describing spatial and temporal chaotic behavior of flow in fractured rocks.

APPROACH

The results of three small-scale ponded infiltration tests conducted in fractured basalt during the summer of 1998 at the Hell’s Half Acre field site were analyzed. The tests were conducted using a small reservoir (40 x 80 cm) constructed on the surface exposure of a fracture intersecting an overhanging basalt ledge (Podgorney et al., 2000). The spatial and temporal behavior of inflow and outflow rates, including temporal and spatial water dripping from the undersurface of the ledge were monitored. The data analysis was conducted using the phase-space reconstruction of one-dimensional time-series of water dripping intervals at different locations. The main idea behind the reconstruction of the system dynamics from one-dimensional scalar data is the evaluation of diagnostic parameters of chaos, such as the correlation time (∆t), global embedding dimension (GED), local embedding dimension (LED), Lyapunov dimension (LD), Lyapunov exponents (LE) and correlation dimension.

Figure 1. An example of a 3-D attractor plotted for 2,078 water dripping intervals (n) with ∆t=1, showing a determinsitic structure with a secondary noisy component. Parameters of chaos are: GED = 5, LED = 5, LD = 4.611, largest LE = 0.364, minimum LE = 0.724. (Test 8, Point 6, 7/6/98).

term predictions and only a range of possible long-term predictions. The models developed in this project would be of interest for investigations of dripping phenomena in fractured rocks at several DOE sites—e.g., at the potential nuclear waste repository at Yucca Mountain, Nevada, and in fractured karst at Oak Ridge, Tenn.

ACCOMPLISHMENTS

RELATED PUBLICATIONS

The results of this study show that a dripping water behavior is transient and either quasi-periodic or nonperiodic. The dripping-water behavior occurs on three temporal scales, such as seconds, hours and days, which are not related to changes in boundary conditions. The observed nonlinear behavior is caused by a superposition of several physical nonlinear processes generating chaos for flow in unsaturated fractured rocks, including the capillary barrier effect. The observed variations of the flow rate and dripping intervals are apparently caused by a combination of both deterministic-chaotic, reflecting the physical deterministic nature of nonlinear flow and transport processes, and random components (Faybishenko, 1999). The volumetric outflow rates combined from several dripping locations exhibit spatial and temporal instabilities with primary low-frequency fluctuations and secondary high-frequency fluctuations caused by local instabilities. The time series data and corresponding attractors indicated several routes to chaos in water dripping processes, such as intermittency fluctuations, bifurcation, gradual and/or rapid collapse of stability. It was determined that different models, such as deterministic, deterministic-chaotic, stochastic-chaotic and random models, can be used to describe the data for different times. Figure 1 illustrates an example of a time-series of water-dripping intervals exhibiting deterministic chaos and a 3-D phase-space attractor.

Faybishenko, B., Evidence of chaotic behavior in flow through fractured rocks, and how we might use chaos theory in fractured rock hydrogeology, Proc. Dynamics of Fluids in Fractured Rocks: Concepts and Recent Advances, pp. 207-212, Berkeley Lab report LBNL-42718, 2000. Podgorney, R., T. Wood, B. Faybishenko and T. Stoops, Spatial and temporal instabilities in water flow through variably saturated fractured basalt on a one-meter scale, AGU Monograph 122, Dynamics of Fluids in Fractured Rocks, in press.

ACKNOWLEDGEMENTS

SIGNIFICANCE OF FINDINGS

If a flow system exhibits a deterministic chaotic behavior, its long-term predictability is limited. For such a system, one can provide precise short-

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This work has been supported by the Environmental Management Science Program of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098 and by Idaho National Engineering and Environmental Laboratory. The field infiltration tests were conducted by R. Podgorney and T. Wood of INEEL. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Environmental Remediation Technology Program

HIGH-FREQUENCY ELECTROMAGNETIC MEASUREMENTS

FOR ENVIRONMENTAL Ki Ha Lee, Alex Becker and William Frangos Contact: Ki Ha Lee, 510/486-7468, khlee@lbl.gov

Annual Report 1999 - 2000

APPLICATIONS

RESEARCH OBJECTIVES

High-resolution imaging of the shallow subsurface is a valuable tool for delineation of buried waste, detection of unexploded ordinance, verification and monitoring of containment structures, and other environmental applications. To this end, we have been developing a non-invasive methodology for accurately imaging the electrical conductivity and the dielectric constant (normalized electrical permittivity) of the shallow subsurface using the highfrequency impedance (HFI) approach.

APPROACH

Studies have shown that electromagnetic (EM) measurements at frequencies between 1 and 100 MHz are important for such applications to determine the dielectric constant in addition to electrical conductivity of the subsurface. For high-resolution imaging, accurate measurements are necessary so the field data can be mapped into the space of the subsurface parameters. To achieve Figure 1. Toroid, a high-frequency electric field sensor. The device accurate measurements, electric and magnetic sensors have been measures electric field in the direction parallel to the toroid axis. tested in a known area against theoretical predictions. For the One shown here has 100 windings, and the size is 3" OD (comtransmitter, we used a function generator good to 30 MHz and an pare with the quarter on the right). amplifier with a bandwidth of 250 kHz through 110 MHz. We also built and tested electric & magnetic transmitter antennae good through at least 30 MHz. To minimize spurious pickup and parasitic radiation, coaxial cables have been replaced by optical fibers. Additionally, we set up and tested a digital data acquisition system that Additionally, we have refined the behavior of the operates under control of a notebook computer through a GPIB interface. toroid (Figure 1), a compact high-frequency elecIn the initial development of the field system and its verification, meastric field sensor. Improvements in the shielding urements were made at the Richmond Field Station (RFS), operated by the and extraneous pickup problems with the protoUniversity of California at Berkeley. The measured impedance showed good type toroid have led to an improved response. agreement with calculated values through 10 MHz. Conditions at the RFS SIGNIFICANCE OF FINDINGS are relatively conductive and the EM impedance is more sensitive to the High-frequency measurements of up to 30 subsurface conductivity. In a more resistive environment, such as the MHz have been made in terms of EM impedance Savannah River Site clay caps, model studies show that the impedance is for the first time. This is a critical frequency band more sensitive to the subsurface permittivity. Two attempts at securing (up to 100 MHz) that contains information about high-frequency impedance data in a resistive environment have been made the electrical property, both dielectric constant to date. The first attempt was at Donner Summit in the Sierra Nevada and electrical conductivity, of the shallow subRange. Initial analyses show that the impedance data agree well with a simsurface. ple homogeneous earth model. The second attempt was made in a very highly resistive environment at Point Reyes National Seashore. Near-surface ACKNOWLEDGEMENTS resistivities of 2,000 to 10,000 ohm-m have been measured. This work has been supported by the ACCOMPLISHMENTS Assistant Secretary for Environmental Following the initial sensor verification done last year for the frequency Restoration and Waste Management, Office of range of up to a few MHz, the project moved on to a wider portion of the Technology Development, of the U.S. radio spectrum, up to 30 MHz to date. This step required development of a Department of Energy under Contract No. DEtransmitter system in order to have a signal at specified frequencies. AC03-76SF00098.

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Earth Sciences Division Berkeley Lab

Environmental Remediation Technology Program

CONTAMINANT TRANSPORT

IN A SANDY AQUIFER WITH DISCONTINUOUS Curtis M. Oldenburg, Jennifer Hinds and Preston D. Jordan Contact: Curtis M. Oldenburg, 510/486-7419, cmoldenburg@lbl.gov

Annual Report 1999 - 2000

CLAY LAYERS

RESEARCH OBJECTIVES

The first objective of this research is to develop a three-dimensional hydrostratigraphic model of the unconfined aquifer (A-aquifer) below Operable Unit 1 (OU 1), at the former Fort Ord Army Base, along the central California coast. The broader objective of the project is to understand the groundwater flow and contaminant transport in the layered sands and clays at a depth of 30 m (100 ft), downgradient from OU 1. Historically, solvents and fuels were used at OU 1 for fire fighter training. The Army issued a Record of Decision for OU 1 in 1988 which specified a two-phase approach to remediation. The first phase required the excavation and bioremediation of contaminated soils in the Fire Drill Area. The second phase required the Army to install a groundwater extraction and treatment system to remediate contaminated groundwater. Cleanup standards were set at maximum contaminant levels (MCLs). A sampling study in 1993 confirmed the efficacy of the excavation and treatment of soils contaminated with solvents and fuels. Groundwater contamination consists of VOCs, primarily TCE; groundwater extraction and treatment from the A-aquifer at a depth of approximately 30 m (100 ft) has been underway since 1988. Quarterly sampling from monitoring wells in the area suggests the plume moves both to the northwest and to the north-northwest.

APPROACH

We used elevations of subsurface clay horizons from the field logs of approximately 60 vertical boreholes within OU 1. Geological logs from five new wells installed as part of the current project were also used to develop the hydrostatigraphic model (see Figure 1). The shallow subsurface at OU 1 (depth < 45 m (150 ft)) consists of two primary sediment types: (1) dune sands, and (2) underlying estuarine clay deposits referred to as the Fort Ordâ&#x20AC;&#x201C;Salinas Valley Aquitard (FO-SVA).

Figure 1. Three clay horizons beneath the Fort Ord OU 1 Fire Drill Area, with existing monitoring wells and newly installed flow sensor wells shown in yellow and red, respectively.

generating numerical grids for groundwater flow and transport simulations. Simulations based on plausible hydrostratigraphy can be used to test VOC source hypotheses, understand controls on groundwater flow and predict future groundwater flow and transport behavior.

ACCOMPLISHMENTS

The hydrostratigraphic model we developed for the OU 1 site includes multiple clay layers separated by sand (Figure 1). In the figure, the blue, green and brown layers represent the shallowest, intermediate and deepest clay layers at the site. The Fire Drill Area is shown by the white outline. The boreholes used to constrain the model are shown by the yellow and red open circles. Most of the boreholes at OU 1 terminate in the upper 30â&#x20AC;&#x201C;60 cm (1 to 2 ft) of the first clay encountered. A few boreholes, however, do penetrate through thin clay layers into underlying sand and then back into clay, providing direct evidence of multiple clay layers. Multiple sand and clay layers are formed by repeated marine transgressions and regressions.

ACKNOWLEDGEMENTS

This work has been supported by the U.S. Army Industrial Ecology Center through the Concurrent Technologies Corporation Contract No. DAAE30-98-C-1050, Task No. 281, CRDL No. B009 administered by the University of California at Santa Cruz, and by Lawrence Berkeley National Laboratory under U.S. Department of Energy Contract No. DE-AC0376SF00098.

SIGNIFICANCE OF FINDINGS

The conceptual model of multiple clay layers explains notable clay elevation differences between neighboring boreholes. Data from the 3-D hydrostratigraphic model of the Fort Ord OU 1 area are used as input for

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Environmental Remediation Technology Program

FAST FLOW

IN UNSATURATED COARSE SEDIMENTS Tetsu K. Tokunaga, Jiamin Wan and Keith Olson

Annual Report 1999 - 2000

Contact: Tetsu K. Tokunaga, 510/486-7176, tktokunaga@lbl.gov

RESEARCH OBJECTIVES

Unsaturated flow in very coarse sediments is a critical area for improving our understanding of vadose zone flow and transport. In particular, very coarse-textured (>1 mm grain-size) media can sustain high flow rates at relatively low saturations, doing so via film flow rather than by flow through an interconnected network of saturated pores. Thus, the physics of fast flow processes in unsaturated very coarse media is fundamentally different from that traditionally recognized in finer textured sediments. Our general objectives are (1) to quantify the macroscopic hydraulic properties of very coarse textured sediments in the near-zero (-10 to 0 kPa) matric potential region, and (2) determine the microscale basis for fast unsaturated flow. Through these studies, we will develop appropriate scaling relations for unsaturated flow in coarse-granular sediments.

through tested microscale concepts. A new tensiometer has been developed to provide measurements of hydraulic potentials with high spatial (1.0 mm) and energy (10 Pa) resolution. The new high-resolution tensiometer also has a fast response time (<1 s) in the near-zero matric potential region. Initial experiments on film hydraulic properties have been completed, with results similar to those obtained in our previous work on transient film flow. Film moisture characteristics on gravel surfaces are practically nonhysteretic. Film hydraulic diffusivities appear to be monotonically decreasing functions of average film thickness.

APPROACH

Reconciling macroscopic (column) and microscopic (grains, pores, films) aspects of unsaturated flow requires direct, quantitative measurements at both scales. Therefore, studies are being conducted to quantify macroscopic and microscopic hydraulic properties and processes in coarse sands and gravels. We are focusing most of our efforts on sediments from the Hanford Site (Hanford formation, grain-sizes ranging from 0.1 to 50 mm). This is a difficult energy region to study because of extreme changes in saturation and conductance that take place in coarser textured media. Three methods for obtaining bulk measurements of unsaturated potential-saturation-conductance have been modified to obtain these measurements: suction-plate equilibration, unit gradient infiltration, and steady evaporation. For microscale measurements of average film thickness, we employ a recently developed x-ray technique. These experiments build on our previous experience with film flow on roughened quartz glass surfaces. The method relies on determining average water film thicknesses using x-ray fluorescence of a solute tracer. A Hanford gravel sample is placed in a small suction plate device and scanned with a defocused synchrotron x-ray microbeam while equilibrating to selected matric potentials. These x-ray experiments are conducted at the National Synchrotron Light Source (Brookhaven National Laboratory). Experiments were conducted in the 0 to –10 kPa matric potential range, with most tests in the 0 to –2 kPa region, which permits fast film flow in larger, unsaturated pores.

SIGNIFICANCE OF FINDINGS

Our analyses of unsaturated flow in coarse sediments are showing that at near-zero matric potentials, fast film flow is possible. Magnitudes of fast, unsaturated flow in gravels at near-zero matric potentials are consistent with direct measurements of film hydraulic properties.

RELATED PUBLICATION

Tokunaga, T.K., J. Wan and S.R. Sutton, Transient film flow on rough fracture surfaces, Water Resour. Res., 36, in press, 2000.

ACKNOWLEDGEMENTS

This work has been supported by the Office of Environmental Management, Environmental Management Science Program of the U.S. Department of Energy under Contract No. DEAC03-76SF00098. We thank Andrew Mei and Robert Conners of LBNL for technical support; Steve Sutton, Tony Lanzirotti (University of Chicago) and Bill Rao (University of Georgia) for assistance at the NSLS beamline X26A; and John Zachara, Robert Lenhard, Steve Smith and Bruce Bjornstad of PNNL for samples of Hanford formation sediment. DOE’s Office of Science, Office of Basic Energy Sciences, Geosciences Research Program supported our related studies on unsaturated flow in fractured rock. Research was carried out (in part) at the National Synchrotron Light Source, Brookhaven National Laboratory.

ACCOMPLISHMENTS

The experiments on macroscopic hydraulic characteristics focus on the near-zero matric potential range where gravel pores are drained. This energy range was identified from capillary drainage calculations and from measured saturations. Under conditions of drained pores, the measured unsaturated hydraulic conductivity is film-controlled. Moisture characteristics (matric potential versus saturation), and unsaturated hydraulic conductivities are being obtained on Hanford formation gravels at the column scale. These hydraulic properties are being compared with grain-film hydraulic properties in order to explain macroscale flow and transport 102

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Annual Report 1999 - 2000

Earth Sciences Division Berkeley Lab

Climate Variability and Carbon Management Program Sally M. Benson 510/486-5875 smbenson@lbl.gov

C

limate variability and carbon management research is the newest addition to the Earth Sciences Division. Over the past three years we have added new staff with expertise in global and regional scale climate modeling, marine geochemistry and soil carbon cycling to provide a strong scientific foundation for addressing concerns related to carbon emissions and climate variability. We have also expanded the research focus of our existing staff to include issues related to deciphering the isotopic composition of ice-cores, developing methods for modeling production of methane from hydrate formations, geophysical monitoring of underground CO2 injection and predicting the reactivity of CO2 in deep geologic formations. Central to making an important scientific contribution in these important areas is a strong link to the newly formed Center for Atmospheric Sciences at UC Berkeley. Last year we reported success in developing two new initiatives, namely, the NASA-sponsored California Water Resources Regional Atmospheric Sciences Application Center (RESAC), which is focused on regional climate variability, and DOCS, the DOE Ocean Carbon Sequestration Center. This year, we report on early accomplishments of these new programs. In addition, we have developed two new initiatives to complement existing programs: the GEO-SEQ project and a project that will add carbon and water cycle monitoring data to DOEâ&#x20AC;&#x2122;s Atmospheric and Radiation Measurements Program (ARM). The GEO-SEQ project is a public-private partnership to develop the information and technology needed to enable geologic sequestration of CO2 by the year 2015. Partners include Lawrence Livermore and Oak Ridge national laboratories, Stanford University, Texas Bureau of Economic Geology, the Alberta Research Council, the U.S. Geological Survey and five private partners: BP, Chevron, Pan Canadian Resources, Texaco and Statoil. The major deliverables of the applied R&D plan are to develop: (1) methods

to co-optimize value-added sequestration for oil and gas formations; (2) procedures for lowering the cost of sequestration by understanding the trade-offs among the costs of separation, compression, transportation and wellfield and geologic considerations; (3) an optimized set of monitoring technologies ready for full-scale field demonstration in three years in oil, gas and brine formations, and two years later in coal formations; (4) improved capability of and confidence in computer simulation models for predicting the performance of CO2 sequestration in oil and gas, brine and coalbed formations; and (5) improved methodology and information for assessing the sequestration capacity of oil, gas, brine and unminable coal formations. This has been a very exciting time for us and we believe that this area will grow into one the major parts of our research activities in the years and decades to come.

FUNDING

Climate Variability and Carbon Management research is funded by the U.S. Department of Energyâ&#x20AC;&#x2122;s Office of Basic Energy Sciences; Office of Fossil Energy, Office of Biological and Environmental Research; and the National Aeronautics and Space Administration. 103

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Earth Sciences Division Berkeley Lab

Climate Variability and Carbon Management Program

SATELLITE RETRIEVALS

OF SURFACE James K.B. Bishop

SOLAR IRRADIANCE

Annual Report 1999 - 2000

Contact: James K.B. Bishop, 510/486-2457,jkbishop@lbl.gov

RESEARCH OBJECTIVES

Marine phytoplankton reproduce on time scales of hours to days. Understanding marine productivity and its role in the ocean's carbon cycle requires surface solar irradiance data on comparable time scales. Our contribution to the NASA SeaWiFS science team is the production and validation of global surface solar irradiance, photosynthetically active irradiance (PAR) and related parameters. Spatial and temporal resolution are 0.5 x 0.5 degrees and 3 hours/daily/monthly, respectively (Figure 1). Bishop, Rossow and Dutton (1997) found excellent agreement (e.g., accuracy better than 8 W m-2) in low-aerosol areas typical of much of the ocean. However, errors as high as 30% were found in aerosol-affected areas (e.g., South China Sea). This work describes irradiance results for 1991 through 1993 and progress on improvement of irradiance accuracy in aerosol-dominated regions. The period 1991-1993 is notable because the effects of aerosols from the Mt. Pinatubo eruption were observed globally.

APPROACH

Surface irradiance is computed using the Bishop, Rossow and Dutton (1997) scheme and DX data from the International Satellite Cloud Climatology Project (ISCCP). Modifications to the scheme include the treatment of ice clouds. ISCCP data began in July 1983 and are derived from multiple polar orbiting and geostationary satellites. NOAA aerosol optical thickness data were used to compute corrections and were applied to our irradiance results.

Figure 1. Surface solar irradiance calculated for the globe for 24 hours and 3-year annual average. Marine plant productivity responds to the day-by-day variations in solar irradiance.

ACCOMPLISHMENTS

We have performed validation of results against high-quality long-term surface observations. We examined aerosol affects using data from NOAA/PMEL at 0N 140W in the Pacific Ocean. Similarly, we studied a mineral dust-affected area in the subtropical Atlantic Ocean. At the site in the subtropical NE Atlantic, our data (after aerosol correction) are in excellent agreement with ocean mooring observations. The aerosol correction also improved the matchup of data from the equatorial Pacific Ocean; however, after the Pinatubo aerosol declined and the cloud regime shifted in mid1992, the retrieved irradiance results fell higher than mooring observations by ~10 W m-2. This is due to under-retrieval of scattered clouds smaller than the 4 km pixels sampled by ISCCP.

Kessler, W.S., and M.J. McPhaden, The 1991-1993 El Nino in the Central Pacific, Deep Sea Research II, 42, 295-333, 1995. Stowe, L.L., R.M. Carey and P.P. Pellegrino, Monitoring the Mt. Pinatubo aerosol layer with NOAA/AVHRR data, Geophys. Res. Lett., 19, 159-162, 1992 (and updates). Waliser, D.E., R.A. Weller and R.D. Cess, Comparisons between buoy-observed, satellite-derived, and modeled surface shortwave flux over the subtropical North Atlantic during the Subduction Experiment, J. Geophys. Res. (Atmospheres), 104 No. D24, 31, 301-31, 320, 1999.

SIGNIFICANCE OF FINDINGS

Accurate calculations of surface solar irradiance are required for better calculations of marine and terrestrial photosynthesis and for validation of climate models. We have demonstrated a global irradiance product that will span from 1983 to the present.

ACKNOWLEDGEMENTS

RELATED PUBLICATIONS

Potylitsina, T., and J.K.B. Bishop, Computation and validation of surface solar irradiance and PAR for the globe using ISCCP data, EOS, Trans., Am. Geophys. Union, 1999. Bishop, J.K.B., W.B. Rossow and E.G. Dutton, Surface solar irradiance from ISCCP 1983-1991, J. Geophys. Res. (Atmospheres), 102, 6883-6910, 1997.

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This research has been supported by NASA grant NAG5-6450, and by the Laboratory Directed Research and Development Program of Lawrence Berkeley National Laboratory under U.S. Department of Energy Contract No. DE-AC03-76SF00098. HTTP://WWW-ESD.LBL.GOV

Earth Sciences Division Berkeley Lab

Climate Variability and Carbon Management Program

Annual Report 1999 - 2000

THE CALIFORNIA WATER RESOURCES RESEARCH AND APPLICATIONS CENTER Norman L. Miller, Jinwon Kim, William E. Dietrich and Phaedon C. Kyriakidis Contact: Norman Miller, 510/486-2374, nlmiller@lbl.gov

RESEARCH OBJECTIVES

In 1999, seven NASA-sponsored Regional Earth Science Applications Centers (RESAC) were formed. Berkeley Lab won support as the California Water Resources Research and Applications Center. The Center is designed around a set of integrated activities that focus on California water resources and related impacts whose primary objectives are to advance our understanding of California climate and hydrologic variability and change. This core activity and the interrelated applications projects include building research partnerships that focus on analysis and educational outreach of hydroclimate impacts on natural systems, society and infrastructure. Our RESAC is a subset of the ESD Regional Climate Center (RCC), which is associated with LBNL’s Center for Isotope Geochemistry to take advantage of the overlap in research interests. During our first year of operation as a RESAC, we have made significant advances. The following highlights our approach and results.

APPROACH

The California Water Resources Research and Applications Center uses dynamic and statistical downscaling schemes within our expanding Regional Climate System Model (RCSM) framework. We produce hydroclimate simulations at short-term, seasonal and long-term time scales for weather and river flow forecasts, hydroclimate prediction, climate change sensitivity analyses, uncertainty estimates, landslide prediction, water quality monitoring and forecasting for climate change assessments of water resources, agriculture, rural economy and hazards. Our applications projects include: • Runoff contaminant monitoring and real-time management in the San Joaquin Basin with the U.S. Bureau of Reclamation and the San Joaquin River Management Program. • Contaminant identification and monitoring from Sierra Foothills mine sites with the UC Space Sciences Laboratory, U.S. Geological Survey and the California Department of Conservation. • Development and testing of dynamic sediment transport and land slide hazards prediction system with UC Berkeley’s Geology and Geophysics Department. • Snow cover area and snow water equivalent maps for California regions with UC Santa Barbara’s Earth Science System Workbench. • Geostatistical analysis of precipitation and stream flow simulations for impact assessment studies. • Annual California Climate, Impacts, Information Workshop hosted by LBNL. • Contributions to impact assessment reports.

ACCOMPLISHMENTS

Regional hydroclimate research in the Earth Sciences Division has become well recognized. We have reported on southwestern hydroclimate change to the U.S. National Assessment, Intergovernmental Panel on Climate Change and the Ecological Society of America. We have completed a series of seasonal and multi-year regional climate and streamflow simulations, developed a new statistical downscaling technique for estimating the limits of uncertainty, and have used our results as input to the above applications.

SIGNIFICANCE OF FINDINGS

As an applications research center, this year’s accomplishments have helped win new funding and increase community awareness of climate change and related hazards. The California Water Resources Research and Applications Center has become a voice in California climate change assessment and is now participating on the California Climate Change Panel.

RELATED PUBLICATIONS

Miller, N.L., and J. Kim, The Regional Climate System Model: Southwestern United States, Eastern Asia, and Northeastern Australia, WMO/ICSU/IOC World Climate Research Programme, Report No. 28, WMO/TD-No. 942, 1999. Field, C., G. Daily, R. Gaines, P. Matson, J. Melack and N. Miller, Climate change and California ecosystems: A report of the Union of Concerned Scientists and the Ecological Society of America. 62 pp., 1999.

ACKNOWLEDGEMENTS

Support for the California Water Resources Research and Applications Center is provided by the NASA Regional Earth Science Applications Center Program under grant NS-2791.

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Earth Sciences Division Berkeley Lab

IMPACTS

OF

Climate Variability and Carbon Management Program

2XCO2 CLIMATE

ON THE

SOUTHWESTERN U.S. CLIMATE

Annual Report 1999 - 2000

Jinwon Kim and Norman L. Miller

Contact: Jinwon Kim, 510/495-2375, jkim@lbl.gov

RESEARCH OBJECTIVES

The objective of this research is to study the effects of doubling the atmospheric CO2 on the regional climate and hydrology in the western United States. It includes evaluating the coupled Mesoscale Atmospheric Simulation-Soil Plant Snow (MAS-SPS) for multi-year regional climate simulations, building a link between GCM (general circulation model) scenarios and the MAS-SPS for downscaling, obtaining hydrologic model parameters for important California basins, and studying effects of 2xCO2 on precipitation and streamflow in the western United States.

APPROACH

To obtain regional climate sensitivities from a climate change scenario from a GCM (HADCM2), we carried out two multi-year simulations using the MAS-SPS. For present-day regional climate, we performed a control simulation using a large-scale forcing from the NCEP reanalysis. Results from this control run are also used to evaluate accuracy of the MAS-SPS. For climate sensitivity, we modified the large-scale temperature and water vapor of the NCEP reanalysis by the mean-monthly changes predicted by the HADCM2 since sub-daily GCM data were not available.

ACCOMPLISHMENTS

We have completed both the control and 2xCO2 climate simulations. Correlation coefficients between observed and simulated monthly precipitation ranged from 0.6 to 0.9 for each state. The 2xCO2 climate run shows that the MAS-SPS responds closely to the large-scale forcing from the GCM sensitivity scenario. The sensitivity run suggests large increases in the low-level moisture flux into the interior western U.S., which has an increase in summertime rainfall. Effects of 2xCO2 climate on wintertime precipitation is smaller; however, predicted timing of snowmelt is 1-3 months earlier than for the present climate due to the increased temperature. Hydrologic model simulations suggest that high elevation basins in the Sierra Nevada and northern California coastal range may be significantly affected by this predicted climate scenario. Figure 1 indicates that peak streamflow shifts from May-June to February-March for the mountainous American River and from March to February for the coastal Russian River. The suggested change in the coastal basin, however, is much smaller than that predicted for the Sierra Nevada basins as snow is not an important part of hydrologic cycle in this basin.

SIGNIFICANCE OF FINDINGS

Dynamical downscaling of global data using a regional climate model is an important method for studying effects of global climate change at regional scales. A preliminary investigation of effects of 2xCO2 climate on the western U.S., using a scenario from the HADCM2, suggests large increases in summer rainfall in the interior western U.S. and early snowmelt at high elevations in winter. In response to these changes, spring river flow peak may be shifted by 2-3 months earlier than the present day in high elevation Sierra Nevada basins with potentially significant impacts on future water supply.

Figure 1. The mean-monthly precipitation and streamflow from the multi-year hindcast (control) and 2xCO2 climate change simulation for (top) American River and (bottom) Russian River.

RELATED PUBLICATIONS

Kim, J., J.-E. Lee and N. Miller, A multi-year regional climate simulation for the western United States using the Mesoscale Atmospheric Simulation model, American Geophysical Union Eos Transactions, 80, Nov. 16, 1999. Miller, N.L., and J. Kim, Climate change sensitivity analysis for two California water sheds: downscaled climate and streamflow study of the southwestern United States, J. American Water Resources Assoc., 36, 657-661, 2000.

ACKNOWLEDGEMENTS

The global change scenario data was provided by the Hadley Centre, U.K. This work was supported by LBNLâ&#x20AC;&#x2122;s Laboratory Directed Research and Development Program under U.S. Department of Energy Contract No. DE-AC0376SF00098, and through NASA-RESAC Grant NS7291. 107

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Earth Sciences Division Berkeley Lab

Climate Variability and Carbon Management Program

UNCERTAINTY IN REGIONAL CLIMATE PRECIPITATION FORECASTS APPLIED Phaedon C. Kyriakidis, Jinwon Kim and Norman L. Miller Contact: Phaedon C. Kyriakidis, 510/495-2599, pckyriakidis@lbl.gov

SCIENTIFIC OBJECTIVES

TO

Annual Report 1999 - 2000

STREAMFLOW

Statistical analysis of climate projections allows scientists and policy makers to examine a set of alternative plausible predictions, and investigate their impact to society and the environment.

The objective of this project is to develop a statistical procedure for characterizing uncertainty in climate projections and propagating it to predictions regarding coupled hydrologic processes. Statistical analysis of climate projections allows scientists and policy makers to examine a set of alternative plausible predictions, and investigate their impact to society and the environment.

APPROACH

We developed a stochastic model for generating synthetic records of daily precipitation, which share important characteristics with given (observed or projected) precipitation records. We also developed a procedure for propagating uncertainty in the parameters of the stochastic precipitation model to associated streamflow predictions in a Monte Carlo framework. This twofold procedure provides uncertainty bounds of hydrologic response variables, e.g., streamflow, due to uncertain precipitation forcing.

ACCOMPLISHMENTS

We applied our stochastic precipitation model for the generation of synthetic daily precipitation records at the Hopland basin, in the northern California coastal range, for the period of Jan. 1, 1988, to Dec. 31, 1992. We then used the stochastic precipitation model for propagating uncertainty in forecasted daily precipitation to coupled streamflow predictions at the Hopland basin for December through February (DJF) 1997-98. In this forecast mode, the parameters of the stochastic precipitation model were inferred from a forecast precipitation record derived via dynamical downscaling of a GCM seasonal forecast. Uncertainty in the parameters of the stochastic precipitation model was then propagated to coupled streamflow forecasts using historical precipitation records for the same basin (Figure 1).

Figure 1. 95% probability intervals for streamflow (DJF 1958-1992).

SIGNIFICANCE OF FINDINGS

In a hindcast mode, we demonstrated that the developed precipitation model reproduces important characteristics of observed precipitation variability, such as persistence and seasonal trends. In a forecast mode, the stochastic precipitation model reproduces the characteristics of the seasonal forecast. Propagation of uncertainty in the precipitation model parameters to coupled streamflow predictions is shown to be of critical importance for providing realistic uncertainty bounds (Figure 2).

Figure 2. 95% probability intervals for streamflow (DJF 1997-1998).

RELATED PUBLICATIONS

Kyriakidis, P.C., J. Kim and N.L. Miller, Generation of synthetic daily precipitation records for hydroclimatic impact assessment: A geostatistical perspective, Journal of Climate, accepted. Kyriakidis, P.C., N.L. Miller and J. Kim, Propagation of uncertainty in regional climate model precipitation forecasts to hydrologic impact assessment, Journal of Hydrometeorology, in review.

ACKNOWLEDEGMENTS

This study is part of the California Water Resources Research and Application Center and was supported by NASA RESAC Grant NS-2791.

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Climate Variability and Carbon Management Program

MODELING WATER RESOURCE AND ENVIRONMENTAL IMPACTS IN THE SAN JOAQUIN BASIN

DUE TO

Annual Report 1999 - 2000

CLIMATE VARIABILITY

Nigel W.T. Quinn, Norman L. Miller, John Dracup,1 Jinwon Kim and Richard Howitt2 1UCLA; 2UC Davis

RESEARCH OBJECTIVES

Contact: Nigel W.T. Quinn, 510/486-7056, nwquinn@lbl.gov

Water resource planners need to develop contingency plans to deal with the potential impacts of global warming and related impacts in the San Joaquin Basin. The literature suggests that precipitation may be warmer and runoff earlier in the season, reducing the reservoir capture of snowmelt and rainfall runoff may occur under current reservoir operational policy. Research also suggests an increase in the variability of future weather and the incidence of extreme weather events under a global warming scenario. Mathematical models most useful to analyze the impacts of climate change scenarios on water resources and the environment do not lend themselves to a system-wide impact analysis. Hence the objective of this research is to develop an integrated modeling system (see Figure 1) that simulates a broad array of water resource and environmental impacts due to a range of future climate scenarios. The goals of this project are to produce a public domain toolbox, available on a CD, that can be readily used by agencies such as the Bureau of Reclamation and the Department of Water Resources and to analyze the impacts of climate change on water resources and the environment.

GCM Simulation

Global Observation

California Historical Weather and Streamflow

Regional Climate System Model Hydroclimate Impacts ECOSIM/CALSIM San Joaquin Basin Water Allocation Module

USFWS Fishery Simulation Model

SWAP/WADE Surface water agricultural production drainage economics model

IMPLAN Multi-sector economic analysis model

SJRIO/DSM2 San Joaquin River hydrodynamic flow and quality

APPROACH

State-of-the-art simulation models have been acquired from the U.S. Bureau of Reclamation, Department of Water Resources, the U.S. Geological Survey, and the University of California. The first phase of the study has involved becoming familiar with the various models and making preliminary runs to validate model codes. The second phase, to begin June 2000, will be to customize the Modular Modeling System (MMS), a software platform developed by the USGS, and link the models as a single toolbox postprocess of our Regional Climate System Model. We are building sets of subroutines for streamflow, water quality, water demand, sediment transport, agro-economics and related ecosystem response. Once the subroutines are implemented within the MMS toolbox, the third phase of the project will be to complete a series of impact analysis runs for the San Joaquin Basin. We will compare future climate change scenario impacts with impacts based on a historic time series.

Figure 1. Integration of models for vulnerability assessment of the San Joaquin Sasin, Calif., due to potential future climate variability and extreme weather events.

RELATED PUBLICATIONS

Quinn N.W.T, N.L. Miller, J.A. Dracup, L. Brekke and L.F. Grober, An integrated modeling system for environmental impact analysis of climate variability and extreme weather events in the San Joaquin Basin, California, Environmental Software Systems, Environmental Information and Decision Support, IFIPTC5 WG5.11, (Ralf Denzer, David A. Swayne, Martin Purvis and Gerald Schimak, eds.), 3rd International Workshop on Environmental Software Systems (ISESS'2000), May 28-June 4, 2000, Zell Am See, Austria, 2000.

ACCOMPLISHMENTS

The Modular Modeling System has been imported and is running on our local workstations; a training session with USGS personnel will take place June 19-20, 2000, at Berkeley Lab. A paper has been prepared on the initial phase of our research and will be presented at the International Society of Environmental Systems Software conference on June 2, 2000, in Austria.

SIGNIFICANCE OF FINDINGS

ACKNOWLEDGEMENTS

Model integration has become a topic of great importance to land and water resource agencies owing to the increasing complexity of water resource and environmental management problems. LBNL is uniquely qualified to assist in this area of applied research.

This research is supported by NASA RESAC Grant NS7291 and EPA STAR Grant 99-NCERQA-GI. 109

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Climate Variability and Carbon Management Program

Annual Report 1999 - 2000

SEASONAL CLIMATE HINDCAST AND PREDICTION FOR THE WESTERN UNITED STATES USING THE REGIONAL CLIMATE SYSTEM MODEL Jinwon Kim and Norman L. Miller

RESEARCH OBJECTIVES

Contact: Jinwon Kim, 510/495-2375, jkim@lbl.gov

The objective of this research is to develop and advance a regional prediction system for seasonal climate and hydrology of the western United States using dynamic downscaling methods. Specific application of the seasonal prediction data is to improve water resources management and provide predictive information on the likelihood of natural disasters such as floods and landslides.

APPROACH

To evaluate the performance of the Regional Climate System Model (RCSM), a three-month simulation forced by the NOAA reanalysis was performed. For a seasonal climate prediction, the UCLA-General Circulation Model (GCM) was run using sea-surface temperatures (SST) predicted by the NOAA/NCEP global climate model. The global prediction from the UCLA-GCM was, in Figure 1. The simulated (HCST) and predicted (FCST) precipitaturn, used to drive the RCSM’s Mesoscale Atmospheric Simulation tion for December 1997 – February 1998 at six California regions (MAS) model for downscaling. The downscaled data from the (NCC: Northern California Coast; CCC: Central California Coast; MAS model was used to run RCSM’s topography-based hydrologSCC: Southern California Coast; NCV: Northern Central Valley; NSN: Northern Sierra Nevada; and SSN: Southern Sierra ic model (TOPMODEL) for streamflow simulations. For this experiment, we selected the winter of 1997-1998 (Dec. 1997-Feb. 1998). The NCEP coupled model has well-simulated the tropical Pacific SST anomaly associated with strong El Niño during the winter.

RELATED PUBLICATIONS

ACCOMPLISHMENTS

The seasonal hindcast experiment has closely simulated observed precipitation during the same period. Figure 1 compares precipitation from both the seasonal hindcast and predictions within California against observed values in six regions geographically classified to represent spatial variations of precipitation in California. Simulated daily precipitation in California was closely correlated with observed precipitation, with a correlation coefficient of 0.8. The season-total precipitation was well-predicted in the seasonal forecast experiment. Time variations of weather events, however, were not well-predicted by the global model. This inaccuracy of predicted daily events was the main source of uncertainty in predicting streamflow. The coupled seasonal streamflow prediction for the Hopland Basin under-estimated the occurrence of high streamflow and over-estimated low streamflow.

Kim, J., N. Miller, J. Farrara and S. Hong, A seasonal precipitation and streamflow hindcast and prediction study in the western United States during the 1997/1998 winter season, J. Hydrometeorology, in press, 2000. Miller, N., J. Kim, R. Hartman and J. Farrara, Downscaled climate and streamflow study of the southwestern United States, J. Amer. Wat. Res. Assoc., 35, 1525-1537, 1999.

ACKNOWLEDGEMENTS

Computational resources were provided by the National Energy Research Scientific Computing Center (NERSC) and the San Diego Supercomputing Center (SDSC). This research has been supported by NASA–RESAC Grant NS7291, and the Laboratory Directed Research and Development Program at Lawrence Berkeley National Laboratory under U.S. Department of Energy Contract No. DE-AC0376DF00098.

SIGNIFICANCE OF FINDINGS

Nested modeling has a significant potential for predicting and diagnosing seasonal-scale climate at high spatial resolutions, useful for improving water resources management and preparation for natural disasters. Inherent uncertainties due to the global forecast model’s predictability is the main source of uncertainties in the downscaled prediction of seasonal climate and streamflow.

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SIMULATION

Climate Variability and Carbon Management Program

OF

SCIENTIFIC OBJECTIVES

MEAN MONTHLY PRECIPITATION AND STREAMFLOW IN AN EAST ASIA WATERSHED

Annual Report 1999 - 2000

Norman L. Miller and Jinwon Kim

Contact: Norman Miller, 510/486-2374, nlmiller@lbl.gov

The objectives of this project were to understand East Asian hydroclimate and its impacts on surface hydrology, water resources and agriculture. This study is important for better understanding the magnitude of mean monthly streamflow response and how this impacts water resources and agricultural productivity. By diagnosing coupled hindcast simulations, one can move forward into seasonal streamflow predictions and crop simulations for monthly and seasonal time scales with increased confidence. This NASA project has focused on precipitation and streamflow simulations as part of our larger activity to improve atmospheric and land-surface prediction for assessing impacts and sustainability.

APPROACH

We have dynamically downscaled global-scale climate data using the Regional Climate System Model and evaluated the results for East Asia and in the Xixian River. The Xixian River is a tributary of the Yangtze River, and is one of the Global Energy and Water Cycle Experiment (GEWEX) intensive observation sites. The Korean Meteorological Administration implemented the Mesoscale Atmospheric Simulation (MAS) model at 60 km resolution for East Asia and produced mean watershed area forcing for our hydrology model, TOPMODEL. Hydrologic calibration is based on a Monte Carlo optimization using historical daily precipitation, streamflow and temperature provided to us by the Chinese Ministry of Water Resources. A second time series of observed precipitation, streamflow and temperature was used for verification.

ACCOMPLISHMENTS

We calibrated the Xixian Basin with a better than 65-percent model to observation streamflow correlation. A multi-year simulation of East Asia hydroclimate and Xixian basin streamflow for January 1979 to December 1983 was completed. This work has allowed us to begin to link our simulations with crop production modeling, develop strong collaborations with the Korean Meteorological Administration and the Chinese Ministry of Water Resources, and train visiting scientists. During 1999-2000, three Korean meteorologists and one Chinese hydrologist visited and worked with our group on East Asian meteorological and hydrological modeling applications.

Figure 1. Monthly precipitation and streamflow at the Xixian Basin.

during 1982 and generally over-predict during other years. The over-prediction was most significant during the summer, but was close to observations during the fall and winter. The over-prediction may be due in part to the large-scale forcing or the mesoscale precipitation scheme. Further investigation of the observation record, the reanalysis data and model performance will be required to fully understand this weakness in the simulation. In general, the multi-year simulation indicates the ability of the coupled system to downscale climate data, simulate mean area precipitation and produce streamflow.

RELATED PUBLICATIONS

Kim, J., N.L. Miller, J-H. Oh, J-S. Chung and DK. Rha, Eastern Asian hydrometeorology simulation using the Regional Climate System Model, Global and Planetary Change, 19, 225-240, 1998. Miller, N.L., and J. Kim, Coupled hydrologic simulations at the GAME/HUBEX site: Xixian Basin, Journal of the Meteorological Society of Japan, accepted.

SIGNIFICANCE OF FINDINGS

A time series of the simulated and observed mean-monthly precipitation and streamflow for the Xixian Basin shows that the precipitation and streamflow seasonal trends are well captured. The simulated precipitation was over-estimated during the summer and fall seasons, periods of heaviest precipitation in this watershed, resulting in an over-prediction of streamflow. The winter and spring months showed much better predictive skill. The monthly-mean analysis indicates a summertime wet season with high streamflow and dry winter and spring seasons with low streamflow. The simulated precipitation and streamflow compare well with observations

ACKNOWLEDGEMENTS

This project was funded for 1997-2000 by the NASA Mission to Planet Earth, Interdisciplinary Sciences Program under Contract No. W19502.

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APPLICATIONS

Annual Report 1999 - 2000

Climate Variability and Carbon Management Program

OF REMOTELY-SENSED DATA FOR SEASONAL CLIMATE PREDICTION IN EAST ASIA AND THE SOUTHWEST UNITED STATES Jinwon Kim, Norman L. Miller, Roger C. Bales1 and Linda O. Mearns2 1University

of Arizona, Tucson, 2National Center for Atmospheric Research, Boulder, Colo.

RESEARCH OBJECTIVES

Contact: Jinwon Kim, 510/495-2375, jkim@lbl.gov

The objective of this new study is to improve seasonal to interannual climate prediction by incorporating remotely-sensed land surface data for a more realistic initialization of land surface models. The improved climate predictions will provide input forcing to water resources, river flow and agricultural productivity models with climate variability represented. The modeling framework, methodology and data obtained in this study will be applied toward advancing seasonal and inter-annual regional climate predictions and climate impact assessments for East Asia and the Southwest United States.

APPROACH

Global Analysis and Prediction Improved landsurface data Satellite and station observation

We will generate improved land-surface data for snow cover, soil moisture content and vegetation by combining satellite-observed and station-data in collaboration with the University of Arizona, NASA Data Centers and East Asia institutions. Satellite data to be used includes NASAâ&#x20AC;&#x2122;s Earth Observing System/MODIS and NOAAâ&#x20AC;&#x2122;s AVHRR for snow cover and vegetation characteristics, and the NASA AMSR for soil moisture. Improved land-surface data is then used to initialize the Soil-Plant-Snow (SPS) model as coupled with the Mesoscale Atmospheric Simulation (MAS) model for dynamical downscaling. The SPS will be modified to examine the effects of different interpretations of satellite-observed surface data. The coupled MAS-SPS will be used to investigate the effects of improved land-surface data on regional simulations for seasonal and interannual time scales. The predicted atmospheric data will be used to predict streamflow and agricultural production.

MAS

SPS

Streamflow model

Agricultural model

Figure 1. An outline of the regional climate prediction experiment in this study. Black arrows indicate one-way data flow and green arrow indicates interactive coupling.

Asian monsoon rain bands simulated with the two different large-scale data sets. Even though overall skills of both simulations are similar, there are enough differences in details of the simulated regional features. This preliminary result implies a potential difficulty in regional climate modeling since evaluation of regional modeling systems heavily relies on an assumption that large-scale analyses provided by meteorological agencies worldwide are reference representation of the atmospheric states. We are planning another experiment in which a large-scale forcing is to be obtained from the reanalysis by the European Center for Medium-range Weather Forecasting (ECMWF).

ACCOMPLISHMENTS

This project is a follow-on from our previous NASA IDS precipitation and streamflow hindcast project. Our preliminary investigation is focused on an evaluation of our Regional Climate System Model and the generation of data sets for this study. We have begun to investigate the accuracy of the system and the large-scale forcing data. Simulations for the 1998 and 1999 East Asia monsoon season have been completed using the large-scale analysis data sets from NOAA and the Korean Meteorological Agency. An eightyear simulation for the western United States has been completed and is being studied for the effects of vertically-varying root density on warm-season regional climate. Fine-scale global vegetation data sets are being analyzed and processed to generate surface vegetation characteristic data for the SPS. We are obtaining hydrologic data for several basins in China and Korea for streamflow research.

RELATED PUBLICATIONS

Kim, J., N. Miller, J.-H. Oh, J.-S. Chung and D. Rha, Eastern Asian hydroclimate simulation using the Regional Climate System Model, Global and Planetary Change, 19, 225-240, 1998. Miller, N., J. Kim and J. Zhang, Coupled precipitation and streamflow simulations at the GAME/HUBEX site: Xixian Basin, J. Japan. Meteorol. Soc., accepted.

ACKNOWLEDGEMENTS

This work is supported by NASA RESAC Grant NS-2791, and new NASA IDS Grant MDAR-0171-0368.

SIGNIFICANCE OF FINDINGS

We found a significant difference in the location and intensity of East 112

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THE IMPACT

OF

Climate Variability and Carbon Management Program

GLOBAL CHANGE

ON CARBON CYCLING IN A CALIFORNIA Margaret Torn, M. Rebecca Shaw and Simon Davis Contact: Margaret S. Torn, 510/495-2223, mstorn@lbl.gov

Annual Report 1999 - 2000

GRASSLAND

RESEARCH OBJECTIVES

We are investigating the impacts of global change on carbon cycling in an annual grassland experiment at Jasper Ridge Biological Preserve (JR) in Stanford, Calif. (Figure 1). Here we report on treatment effects on decomposition rate and the relative contribution of new vs. old C to soil respiration losses after one growing season.

APPROACH

The experimental plots at JR have been exposed to elevated CO2, warming, increased precipitation and N fertilization, singly and in combination, since Fall 1998. The fossil fuel source of elevated CO2 is depleted in 13C relative to the ambient atmosphere. Critical to our work, this creates an isotopic label in plant inputs in the elevated CO2 plots that we can use to trace carbon cycling through plants, soil organic mater and soil respiration. We are using the isotopic signature to identify the age of carbon being respired—recently photosynthesized carbon (i.e., since the experiment began) vs. carbon fixed in previous years. As part of this project, we have linked a headspace autosampler to an isotope ratio mass spectrometer to achieve rapid throughput of the large numbers of isotope samples from this and other ecological experiments.

Figure 1. An experimental plot at the Jasper Ridge Integrated Global Change Experiment. The small black tubes at grass height are CO2 emitters. The silver lampshade houses an infra-red lamp for heating the

RESULTS

The results presented here are based on soil respiration measurements made on Oct. 30, 1999. The first major rain of the season had fallen, but plants had not yet germinated. Thus, essentially all CO2 efflux resulted from microbial decomposition (i.e., there was virtually no plant root respiration). Soil respiration was significantly higher in the treatments that included nitrogen (Figure 2). Plant inputs the previous season were also higher in the nitrogen treatments (data not shown). Did increased respiration reflect increased plant inputs from the prior season or a stimulation of decomposition of old carbon? The isotopic signature of respiration from the control plots was -27.9‰, matching the 13C of plant inputs (-28 ‰), and from plots that included an elevated CO2 treatment it ranged from -34 to –40‰. The values were lightest in the two treatments that received nitrogen. Using a mass balance, this translates to a difference in the contribution of new carbon to respiration. New C made up 65-70% of soil respiration in the nitrogen treatments while it made up only 55% in the other treatment (Figure 3).

Figure 2. Soil respiration at the beginning of the second growing season, October 1999.

SIGNIFICANCE OF FINDINGS

The increased respiration from the nitrogen treatments was made up of the carbon fixed in the previous year. The fact that the increased plant inputs below ground were accompanied by an increase in C fluxes out of the soil suggests that there may be little new storage of carbon despite nitrogen stimulation of plant inputs.

Figure 3. Contribution to soil respiration from carbon fixed in the previous year (i.e., since the experiment began).

ACKNOWLEDGEMENTS

This work has been supported by the Laboratory Directed Research and Development Program at Lawrence Berkeley National Laboratory under U.S. Department of Energy Contract No. DE-AC03-76SF00098.

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DOE CENTER

Climate Variability and Carbon Management Program

FOR

RESEARCH

ON OCEAN James K.B. Bishop

CARBON SEQUESTRATION

Annual Report 1999 - 2000

Contact: 510/486-2457, jkbishop@lbl.gov

RESEARCH OBJECTIVES

Increased energy efficiency, decarbonization of fuels and carbon sequestration are three research areas that the U.S. Department of Energy (DOE) is investigating for managing levels of CO2 gas in the atmosphere. Carbon sequestration is the storage of CO2 in terrestrial ecosystems and soils, geological formations and in the ocean. Ocean carbon sequestration is a viable option for investigation since the oceans are already a sizable reservoir of carbon. In July 1999, DOE's Office of Science announced the formation of the DOE Center for Research on Ocean Carbon Sequestration (DOCS). The center is jointly shared between Lawrence Berkeley National Laboratory (J. Bishop, co-director) and Lawrence Livermore National Laboratory (K. Caldeira, co-director) and includes participants from six outside groups from across the nation.

Figure 1. SeaWiFS ocean color image of plant biomass in the waters of the southern ocean. Ocean fertilization of the nutrient rich waters of the Southern Ocean has been proposed as a way to stimulate vertical transport of CO2 from the atmosphere to the deep sea.

The center is performing research necessary to evaluate the feasibility, effectiveness and environmental acceptability of ocean carbon sequestration by: • addressing ocean fertilization and direct injection, and other ocean carbon sequestration strategies; • advancing understanding of the biological, chemical and physical processes that are critical to the ocean carbon cycle; • understanding the effects of proposed sequestration strategies on this system; • training graduate students and post doctoral investigators; • interacting with the larger community to advance the state of ocean sequestration science; • providing accurate information on ocean carbon sequestration for the government, other researchers and the public.

Figure 2. Lawrence Livermore National Laboratory model simulation of the fate of liquid CO2 injected at a depth of 1700 m near New York City. Direct CO2 injection uses CO2 captured at a central site of fossil fuel usage, for example, a power plant.

APPROACH

ACCOMPLISHMENTS

The center has identified key gaps in the understanding of ocean sequestration. For example, great uncertainty exists in the fate of biologically produced carbon in the upper ocean as it sinks into the deep sea. Furthermore, significant variability of the ocean carbon system occurs on day-to-day time scales — the growth times of marine plants — yet this variability is unsampled in many of the biologically dynamic regions of the ocean. Such information is required for accurate representation of biological processes in ocean models being developed at LLNL. Similarly, there remain uncertainties on the fate of liquid CO2 injected into mid-depth ocean waters. LBNL is addressing these gaps by developing methods to observe ocean carbon variability using robotic autonomous observing systems. Key elements of needed research have been identified and communicated in scientific and public forums.

RELATED PUBLICATIONS

Bishop, J.K., S.E. Calvert and M.Y.-S. Soon, Spatial and temporal variability of POC in the northeast subarctic Pacific, Deep-Sea Research II, 46(11-12) 2699-2733, 1999.

Fung, I.Y., S.K. Meyn, I. Tegen, S.C. Doney, J.G. John and J.K.B. Bishop, Iron supply and demand in the upper ocean, Global Biogeochemical Cycles, 14(N1):281-295, 2000. Bensen, S., T. Dorchak, G. Jacobs, J. Ekmann, J.K.B. Bishop and T. Grahame, Carbon dioxide reuse and sequestration: the state of the art today, ENERGY 2000, The State of the Art, P. Catania, ed., Publ. Balaban International Science Services, L'Aquila, Italy. pp 205-226, ISBN 086689-05-56, 2000.

ACKNOWLEDGEMENTS

This work has been supported by the U.S. Department of Energy’s Office of Science, Office of Biological and Environmental Research, Environmental Sciences Division, under Contract No. DE-AC0376SF00098.

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Climate Variability and Carbon Management Program

DEVELOPMENT

OF ROBOTIC OCEAN CARBON OBSERVERS James K.B. Bishop and Christopher K. Guay

Annual Report 1999 - 2000

Contact: James K.B. Bishop, 510/486-2457, JKBishop@lbl.gov

RESEARCH OBJECTIVES

The ocean's biological carbon pump (photosynthetic fixation of dissolved inorganic carbon in surface waters and downward transport of fixed carbon into the deep sea) plays a critical role in the ocean's carbon cycle and partially determines concentrations of atmospheric CO2. Marine photosynthetic organisms reproduce and are eaten on the time scale of hours to days. Knowledge of the biological pump is therefore severely limited because most oceanographic observing and sampling methods cannot obtain data efficiently on these short-time scales. Our objective is to develop methods for observing carbon biomass variability on spatial and temporal scales that match biological processes in the oceans. It is important to understand the variability of particulate organic carbon (POC) and particulate inorganic carbon (PIC) because formation of these phases during photosynthesis reduces and enhances, respectively, the concentration of dissolved molecular CO2 in the waters in which these organisms grow. PICproducing organisms (coccolithophores) sometimes occur in blooms that are readily visible from space. Reflective waters reduce the capacity of the ocean to absorb solar radiation; such blooms have negatively impacted fisheries.

Figure 1. The Sounding Oceanographic Lagrangian Observer (SOLO). More than 1,000 profiling floats like SOLO have been widely deployed in the oceans for ocean temperature, salinity and circulation observations. LBNL is developing carbon biomass concentration sensors for the SOLO. (Photo courtesy of Russ Davis, Scripps Institution of Oceanography). Figure 2. Photographs illustrating calcite birefringence compared with non-birefringent halite and glass. Calcite lights up when polarizers are crossed.

APPROACH

We are developing sensors for carbon biomass which will be added to new low-cost autonomous robotic floats and gliders that are capable of profiling to mid ocean depths (Figure 1). The optical basis of measuring POC is established and we are now working on a birefringence sensor for PIC. The new sensor uses the fact that PIC is dominated by carbonate minerals (calcite and aragonite) which have extremely high birefringence (measure of the ability of the mineral to interact with and change polarized light) compared to other commonly occurring mineral particles in seawater. Furthermore, PIC dominates the concentrations of mineral particles in most oceanic regimes.

Guay, C.K., and J.K.B. Bishop, A rapid birefringence method for measuring suspended CaCO3 concentrations in water, Deep-Sea Research, submitted. Bishop, J.K.B, and R.E. Davis, Autonomous observing strategies for the ocean carbon cycle, ENERGY 2000, The beginning of a new millennium, P. Catania, B. Golchert, C. Zhou, eds., Publ. Balaban International Science Services, L'Aquila, Italy. pp 1256-1261. ISBN 1-58716016-1, 2000.

ACCOMPLISHMENTS

The concept of our PIC sensor has been demonstrated in the laboratory (Figure 2). We have measured birefringence of suspensions of calcite in water in the presence and absence of non-birefringent particles. PIC may be readily determined in seawater using a commercial bench-top spectrophotometer adapted with linear polarizing filters.

SIGNIFICANCE OF FINDINGS

We have designed sensors which will measure the two components of carbon biomass in ocean water, and when attached to newly developed robotic profiling flats and gliders, will permit a major improvement in ocean biomass observations. These observers are inexpensive enough to be widely deployed in the oceans to follow the natural carbon cycle and perform observations during and after small-scale experiments to study ocean ecosystem response to ocean fertilization.

RELATED PUBLICATIONS

Bishop, J.K.B., S.E. Calvert and M.Y.-S. Soon, Spatial and temporal variability of POC in the northeast subarctic Pacific, Deep-Sea Research II, 46(1112) 2699-2733, 1999.

ACKNOWLEDGEMENTS

This research is supported by grants from the National Oceanographic Partnership Program, NOAA Postdoctoral Fellowship Program, NOAA Office of Global programs, and the U.S. Department of Energy through the DOE Center for Research on Ocean Carbon Sequestration under Contract No. DE-AC03-76SF00098. 115 115

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Climate Variability and Carbon Management Program

GEOLOGIC SEQUESTRATION

OF CARBON DIOXIDE Sally M. Benson, Curt Oldenburg, G. Michael Hoversten and Larry R. Myer

Annual Report 1999 - 2000

Contact: Sally M. Benson, 510/486-5875, smbenson@lbl.gov

SCIENTIFIC OBJECTIVES

The objective of this work is to initiate a set of projects that will develop our capabilities for building the scientific foundations and technology for safe and cost-effective geologic sequestration of CO2.

APPROACH

Four primary approaches are being pursued: Modify our TOUGH2 family of codes to have the capability for simulating all of the short- and long-term physical, chemical and biological processes controlling geologic sequestration of CO2 in oil, gas, brine and coal formations. These codes will then be used for capacity assessment, risk assessment and sequestration optimization. • Enhance or modify our seismic and electromagnetic imaging capabilities for monitoring CO2 migration in the subsurface. • Establish working relationships with industry and other R&D partners to initiate a set of pilot-projects and gain real-world experience in geologic sequestration of CO2. • Improve methods for capacity assessment through selected case studies. Together, these capabilities will provide the foundation for contributing significantly to the evaluation and development of geologic sequestration science and technology. •

Figure 1. Simulated CO2 migration at 5, 10 and 20 years after injection into the Rio Vista Gas Field at the rate equivalent to CO2 generated from a 680 MW gas field power plant.

ACCOMPLISHMENTS

Significant progress has made in all of the above areas. Highlights include: (1) an assessment of the sequestration capacity of oil, gas and brine formations in California; (2) development and evaluation of the concept of CO2-enhanced production from natural gas fields; and (3) evaluation of the sensitivity of seismic, electromagnetic and gravity methods for assessing CO2 migration in the subsurface.

Hoversten, G.M., and L.R. Myer, Monitoring of CO2 sequestration using integrated geophysical and reservoir data, Proc. Fifth International Conference on Greenhouse Gas Control Technologies, Cairns, Australia, Aug. 13-16, 2000. Myer, L.R., A strategy for monitoring of geologic sequestration of CO2, presented and published ENERGEX'2000: Proc. of the 8th International Energy Forum, pp. 1226-1231, Las Vegas, Nev., July 23-28, 2000. Oldenburg, C.M., K. Pruess and S.M. Benson, Process modeling of CO2 injection into natural gas reservoirs for carbon sequestration and enhanced gas recovery, Proc. of the 220th National Meeting of the ACS, Washington, D.C., Aug. 20-24, 2000.

SIGNIFICANCE OF FINDINGS

Large-scale implementation of geologic sequestration of carbon dioxide will require establishing that it is both safe and effective. The work initiated here will help build the scientific foundation needed to answer these questions.

RELATED PUBLICATIONS

Benson, S.M., An overview of geologic sequestration of CO2, ENERGEX '2000: Proceedings of the 8th International Energy Forum, pp. 1219-1225, Las Vegas, Nev., July 23-28, 2000. Benson, S.M., Comparison of three options for geologic sequestration of CO2 – A case study for California, Proc. Fifth International Conference on Greenhouse Gas Control Technologies, Cairns, Australia, Aug. 13-16, 2000. Benson, S.M., and L.R. Myer, The GEO-SEQ Project, Proc. Fifth International Conference on Greenhouse Gas Control Technologies, Cairns, Australia, Aug. 13-16, 2000. Benson, S.M., et al., Carbon dioxide reuse and sequestration: the state of the art today, Energy 2000: State of the Art, P. Catania (ed.), pp. 205-226, Las Vegas, Nev., July 23-28, 2000.

ACKNOWLEDGEMENTS

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Earth Sciences Division Berkeley Lab

CO2 INJECTION

Climate Variability and Carbon Management Program

FOR

Annual Report 1999 - 2000

CARBON SEQUESTRATION AND ENHANCED GAS RECOVERY

Curt M. Oldenburg, Karsten Pruess and Sally M. Benson Contact: Curt M. Oldenburg, 510/486-7419, cmoldenburg@lbl.gov

RESEARCH OBJECTIVES

Injection of CO2 into depleted natural gas reservoirs offers the potential to sequester carbon while simultaneously enhancing CH4 recovery. The enhanced CH4 recovery can partially offset the costs of CO2 injection. To analyze the feasibility of carbon sequestration with enhanced gas recovery (CSEGR), we are carrying out simulations of CO2 injection into a prototype natural gas field. Simulations based on the Rio Vista Gas Field in the Central Valley of California are used to model CSEGR using CO2 separated from flue gas generated by the 680 MW Antioch gas-fired power plant located approximately 20 km away.

APPROACH

Figure 1. Mass fraction of CO2 in the gas phase and gas velocity

at t =1 yr and 10 yrs with no CH4 production. In order to model gas reservoir processes, we have developed a module called EOS7C for simulating gas and water flow in natural gas reservoirs within the TOUGH2 framework. The module handles five components (water, brine, CO2, tracer and CH4) along with to its greater density relative to CH4, a process favorable for CSEGR. heat. The main gas species partition between the gas and liquid phases according to their temperature- and pressure-dependent solubilities. SIGNIFICANCE OF FINDINGS Review of the properties of CH4 and CO2 at typical depleted gas reservoir Simulations of CO2 injection into a depleted conditions shows that the higher density and viscosity of CO2 will favor CSEGR. The large areal extent of producing formations in gas fields will also natural gas reservoir carried out with favor CSEGR by preventing mixing as the gas in place repressurizes relaTOUGH2/EOS7C confirm the plausibility of CSEGR as a way to sequester carbon while tively quickly. enhancing methane recovery. Simulations that ACCOMPLISHMENTS use realistic estimates of CO2 produced from the We have simulated various scenarios for CO2 injection into a gently dipAntioch gas-fired power plant show that CSEGR ping depleted natural gas reservoir with water table based on the Rio Vista allows more than five times the mass of methane Gas Field. The model domain is two-dimensional and models 1/16 of the to be recovered relative to that which would be actual gas field. In the simulations, the injection rate of CO2 is equal to the produced without CSEGR. scaled rate of CO2 production from the Antioch gas-fired power plant. In the RELATED PUBLICATIONS scenario shown in Figure 1, the reservoir is at a pressure of 39 bars when Oldenburg, C.M., K. Pruess and S.M. Benson, CH4 production is turned off and CO2 injection begins. As shown in the figure, the injected CO2 depresses the water table locally due to its greater denProcess modeling of CO2 injection into natural sity. The CO2 front moves approximately one-half of the way to the producgas reservoirs for carbon sequestration and tion well at the right-hand side of the domain in 10 years. During this time, enhanced gas recovery, Berkeley Lab report the pressure at the production well increases by 15 bars. Methane produced LBNL-45820, 2000. after this injection remains more than 90% pure for approximately seven ACKNOWLEDGEMENTS years. In a scenario not shown here, CO2 is injected at the same time as CH4 is produced under a constant pressure of 39 bars. In this latter scenario, This work was supported by the Laboratory nearly pure CH4 can be produced at constant pressure for 14 years. Directed Research and Development program at In another scenario to study density effects, CO2 was injected for 10 Lawrence Berkeley National Laboratory under years and then allowed to migrate as driven by gravity. A strong density Department of Energy Contract No. DE-AC03stratification was observed in the simulation as CO2 moved downwards due 76SF00098.

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Earth Sciences Division Berkeley Lab

Earth Sciences Division Publications 1999-2000

Ahlers, C.F., S. Finsterle and G.S. Bodvarsson, Characterization and prediction of subsurface pneumatic response at Yucca Mountain, Nevada, J. Contaminant Hydrology – Special Issue, 38, 47-68, 1999. Apps, J., and I.N. Solodov, The chemical interactions between a migrating plume of liquid radioactive waste and weathered bedrocks in the vicinity of Lake Karachai, near Chelyabinsk, Russia, presented at Fourth USA/CIS Joint Conference on Environmental Hydrology and Hydrogeology, San Francisco, Calif., Nov. 7-10, 1999, Berkeley Lab Report LBNL-43116, 1999. Bandurraga, T.M., and G.S. Bodvarsson, Calibrating hydrogeologic parameters for the 3-D site-scale unsaturated zone model of Yucca Mountain, Nevada, J. Contaminant Hydrology – Special Issue, 38, 25-46, 1999. Becker, A., K.H. Lee and L. Reginato, Field test of a wideband downhole EM transmitter, Berkeley Lab Report LBNL-43762, 1999. Benson, S.M., Earth Sciences Division Annual Report 1998-1999, Berkeley Lab Report LBNL-43816, 1999. Benson, S.M., An overview of geologic sequestration of CO2, ENERGEX ‘2000: Proceedings of the 8th International Energy Forum, pp. 12191225, Las Vegas, Nev., July 23-28, 2000. Benson, S.M., Comparison of three options for geologic sequestration of CO2 – A case study for California, Proc. Fifth International Conference on Greenhouse Gas Control Technologies, Cairns, Australia, Aug. 13-16, 2000. Benson, S.M., T. Dorchak, G. Jacobs, J. Ekmann, J.K.B. Bishop and T. Grahame, Carbon dioxide reuse and sequestration: the state of the art today, ENERGY 2000, The State of the Art, P. Catania, ed., Publ. Balaban International Science Services, L’Aquila, Italy, pp 205-226, ISBN 08668905-56, 2000. Benson, S.M., and L.R. Myer, The GEO-SEQ Project, Proc. Fifth International Conference on Greenhouse Gas Control Technologies, Cairns, Australia, Aug. 13-16, 2000. 119

Birkholzer, J.T., G. Li, C.-F. Tsang and Y. Tsang, Modeling studies and analysis of seepage into drifts at Yucca Mountain, J. Contaminant Hydrology – Special Issue, 38, 349-384, 1999. Birkholzer, J.T., and Y.W. Tsang, Modeling the thermal-hydrological processes in a largescale underground heater test in partially saturated fractured tuff, Water Resources Research, 36(6), 1431-1448, 2000. Bishop, J.K. B., S.E. Calvert and M.Y.Y. Soon, Spatial and temporal variability of POC in the northeast Subarctic Pacific, Deep Sea Research II, 46(11-12), 2699-2733, 1999. Bishop, J.K.B, and R.E. Davis, Autonomous observing strategies for the ocean carbon cycle, ENERGY 2000, The beginning of a new millennium, P. Catania, B. Golchert, C. Zhou, eds., Publ. Balaban International Science Services, L’Aquila, Italy, pp. 12561261. ISBN 1-58716-016-1, 2000. Bodvarsson, G.S., Geologic disposal of nuclear waste – progress made and lessons learned, in AGU Geophysical Monograph 122, Dynamics of Fluids in Fractured Rocks: Concepts and Recent Advances, pp. 181-183, 2000. Bodvarsson, G.S., The Geysers and Dixie Valley high-enthalpy systems in the United States, short course presented at World Geothermal Congress 2000, Japan, May-June 2000, in Proc. Course on Long-Term Monitoring of High- and Low-Enthalpy Fields Under Exploitation, pp. 193-202, 2000.

Earth Sciences Division Berkeley Lab

Annual Report 1999 - 2000

Publications 1999-2000

Bodvarsson, G.S., Modeling and management of geothermal systems, short course presented at World Geothermal Congress 2000, Japan, May-June 2000, in Proc. Course on Long-Term Monitoring of High- and LowEnthalpy Fields Under Exploitation, pp. 77-96, 2000. Bodvarsson, G.S., et al., Unsaturated zone flow and transport model process model report (UZ PMR), Las Vegas, Nevada: CRWMS M&O, 2000. Bodvarsson, G.S., W. Boyle, R. Patterson and D. Williams, Overview of scientific investigations at Yucca Mountain – The potential repository for high-level nuclear waste, J. Contaminant Hydrology – Special Issue, 38, 3-24, 1999. Chang, F.-R.C., N.T. Skipper, K. Refson, J.A. Greathouse and G. Sposito, Interlayer molecular structure and dynamics in Li-, Na-, and K-montmorillonite-water systems, in Mineral-Water Interfacial Reactions, Kinetics and Mechanisms (D.L. Sparks and T.J. Grundl, eds), 715, 88106, American Chemical Society, Washington, D.C., 1999. Charette, M.A., S.B Moran and J.K.B. Bishop, 234Th as a tracer of particulate organic carbon export in the subarctic Northeast Pacific Ocean, DeepSea Research II 46(11-12), 2833-2862, 1999. Cohen, A.J.B., Three-dimensional numerical modeling of the influence of faults on groundwater flow at Yucca Mountain, Nevada, Ph.D. thesis, Berkeley Lab Report LBNL-43377, 1999. Compton, J.S., M.E. Conrad and T.W. Vennemann, Stable isotope evolution of volcanic ash layers during diagenesis of the Miocene Monterey Formation, California, Clays and Clay Minerals, 47(1), 84-95, 1999. Conrad, M.E., D.J. DePaolo, D.L. Song and E. Neher, Isotopic evidence for groundwater flow and biodegradation of organic solvents at the Test Area North site, INEEL, in Ninth Annual V.M. Goldschmidt Conference, pp. 58-59, LPI Contribution No. 971, Lunar and Planetary Institute, Houston, 1999. Conrad, M.E., W.T. Stringfellow and G.M. Lamble, Uptake and precipitation of metals from basalt by the lichen Stereocaulon volcanii, presented at the Geological Society of American Annual Meeting, San Francisco, Calif., October 1999, Berkeley Lab Report LBNL-44883, 1999. Conrad, M.E., A.S. Templeton, P.F. Daley and L. Alvarez-Cohen, Seasonallyinduced fluctuations in microbial production and consumption of methane during bioremediation of aged subsurface refinery contamination, Environmental Science & Technology, 33(22), 4061-4068, 1999. Conrad, M.E., A.S. Templeton, P.F. Daley and L. Alvarez-Cohen, Isotopic evidence for biological controls on migration of petroleum hydrocarbons, Org. Geochem., in press. Daley, T. M., Borehole source comparison - vertical hydraulic vibrator and orbital vibrator using multi-component crosswell data, Berkeley Lab Report LBNL-44022, 1999. Daley, T.M., R. Gritto, V.A. Korneev, M.A. Feighner, E.L. Majer and J.E. Peterson, Surface-to-tunnel seismic tomography on kilometer scale at Yucca Mountain, Berkeley Lab Report LBNL-44537, 1999. Daley, T.M., J.E. Peterson and E.L. Majer, Simultaneous acquisition of P- and S-wave crosswell seismic profiles in a contaminated basalt aquifer, Berkeley Lab Report LBNL-42627, 1999. Daley, T.M., M.A. Feighner and E.L. Majer, Monitoring underground gas storage in a fractured reservoir using time lapse VSP, Berkeley Lab Report LBNL-44876, 2000.

Daley, T.M., E.L. Majer and R. Gritto, Single-well seismic imaging: status report, Berkeley Lab Report LBNL-45342, 2000. De, A., D.B. Silin and T.W. Patzek, Waterflood surveillance and supervisory control, SPE 59295, paper presented at SPE/DOE Improved Oil Recovery Symposium, Tulsa, Okla., April 3–5, 2000. Dickens, G., and B.M. Kennedy, Noble gases in hydrate from the Black Ridge, in Proc. Ocean Drilling Program, Scientific Results, 164, in press. Doughty, C., Investigation of conceptual and numerical approaches for evaluating moisture, gas, chemical, and heat transport in fractured unsaturated rock, J. Contaminant Hydrology – Special Issue, 38, 69-106, 1999. Doughty, C., and K. Karasaki, Flow and transport in hierarchically fractured rock, Journal of Hydrology, submitted. Doughty, C. and K. Karasaki, Using an effective continuum model for flow and transport in fractured rock: The H-12 flow comparison, Berkeley Lab Report LBNL-44966, 1999. Doughty, C., C.M. Oldenburg and A.L. James, Site S-7 VOC transport modeling for the Vadose Zone Monitoring System (VZMS), McClellan AFB – 1999 Semi-Annual Report, Berkeley Lab Report LBNL-43526, 1999. Doughty, C., C.M. Oldenburg and P.T. Zawislanski, Analysis of vadose zone data from a contaminated site: indirect evidence for preferential flow, Water Resources Research, submitted. Doughty, C., and C-F. Tsang, BORE-II – A code to compute dynamic wellbore electrical conductivity logs with multiple inflow/outflow points including the effects of horizontal flow across the well, Berkeley Lab Report LBNL-46833, 2000. Fairley, J.P., Theoretical and field studies of fracture/matrix interaction, Ph.D. Thesis, Department of Materials Science and Mineral Engineering, University of California, Berkeley, Calif., 2000. Fan, J., Overlap domain decomposition technique for modeling wave propagation, Ph.D. Thesis, LBNL-42881, Lawrence Berkeley National Laboratory, Berkeley, Calif., 1999.

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Earth Sciences Division Berkeley Lab

Annual Report 1999 - 2000

Publications 1999-2000

Faybishenko, B., Evidence of chaotic behavior in flow through fractured rocks, and how we might use chaos theory in fractured rock hydrogeology, Proc. Dynamics of Fluids in Fractured Rocks: Concepts and Recent Advances, pp. 207-212, Berkeley Lab Report LBNL-42718. Faybishenko, B. (ed.), Proceedings of the International Symposium on Dynamics of Fluids in Fractured Rocks: Concepts and Recent Advances, Berkeley Lab Report LBNL-42718, 1999. Faybishenko, B., Tensiometer for shallow and deep measurements of water pressure in vadose zone and groundwater, Soil Sciences, 165(6), 473-482, 1999. Faybishenko, B., A.J. Babchin, A.L. Frenkel, D. Halpern and G.I. Sivanshinski, A model of chaotic evolution of an ultrathin liquid film flowing down an inclined plane, Geophysical Research Letters, submitted. Faybishenko, B., M. Bandurraga, S.M. Conrad, P. Cook, C. Eddy-Dilek, L. Everett, T. Hazen, S. Hubbard, A.R. Hutter, P. Jordan, C. Keller, F.J. Leij, N. Loaiciga, E.L. Majer, L. Murdoch, S. Renehan, B. Riha, J. Rossabi, Y. Rubin, A. Simmons, S. Weeks and C.V. Williams, Vadose zone characterization and monitoring: current technologies, applications and future developments, Vadose Zone Science and Technology Solutions, Battelle, Ohio, in press. Faybishenko, B., C. Doughty, M. Steiger, J.C.S. Long, T. Wood, J. Jacobsen, J. Lore and P.T. Zawislanski, Conceptual model of the geometry and physics of water flow in a fractured basalt vadose zone: Box Canyon Site, Idaho, Water Resources Research, in press. Faybishenko, B. and S. Finsterle, On the physics of tensiometry in fractured rocks, in GSA Monograph in honor of the 60th Birthday of S. Neuman, Geological Society of America, Berkeley Lab Report LBNL-43864, in press. Faybishenko, B., P.A. Witherspoon, C. Doughty and J.T. Geller, Multi-scale investigations of liquid flow in a fractured basalt vadose zone, Berkeley Lab Report LBNL-42910, 1999. Feighner, M., R. Gritto, T.M. Daley, H. Keers and E.L. Majer, Three-dimensional seismic imaging of the Ryepatch Geothermal Reservoir, Berkeley Lab Report LBNL-44119, 1999. Finsterle, S., Demonstration of optimization techniques for ground water plume, Berkeley Lab Report LBNL-46746, 2000. Finsterle, S., ITOUGH2 Userâ&#x20AC;&#x2122;s Guide, Berkeley Lab Report LBNL-40040, 1999. Finsterle, S., Using the continuum approach to model unsaturated flow in fractured rock, Water Resources Research, 36(8), 2055-2066, Berkeley Lab Report LBNL-45459, 2000. Finsterle, S., G. Bjornsson, K. Pruess, and A. Battistelli, Evaluation of geothermal well behavior using inverse modeling, in AGU Monograph 122, International Symosium on Dynamics of Fluids in Fractured Rocks: Concepts and Recent Advances, pp. 377-387, American Geophysical Union, 1999. Finsterle, S., and J. Najita, Robust estimation of hydrogeologic model parameters, Water Resources Research, in press. Finsterle, S., and K. Pruess, Automatic calibration of geothermal reservoir models through parallel computing on a workstation cluster, Proc. 24th Workshop on Geothermal Reservoir Engineering, Stanford, Calif., Stanford Geothermal Program Report SGP-TR-162, pp. 123-130, 1999. 121

Finsterle, S., and R.C. Trautz, Drift seepage in unsaturated fractured rock, paper submitted at American Geophysical Union 1999 Fall Meeting, San Francisco, Calif., Dec. 1317, 1999. Finsterle, S., and R.C. Trautz, Numerical modeling of seepage into underground openings, in Society for Mining Metallurgy and Exploration, Inc., 2000 SME Annual Meeting, 1999. Frangos, W., and S. Ter-Saakian, Resistivity and induced polarization survey at a Russian nuclear waste site, Geophysics, in press. Fung, I.Y., S.K. Meyn, I. Tegen, S.C. Doney, J.G. John and J.K.B. Bishop, Iron supply and demand in the upper ocean, Global Biogeochemical Cycles, 14(N1), 281-295, 2000. Gabuda, S.P., S.G. Kozlova, V.V. Terskikh, C. Dybowski, G. Neue and D.L. Perry, 207Pb NMR study of novel Pb-Pb chemical bonding in lead monoxides, -PbO and - PbO, Chemical Physics Letters, 305, 353, 1999. Garcia, J., and K. Pruess, Local grid refinement for multi-scale geothermal reservoir simulation with TOUGH2, Berkeley Lab Report LBNL-45646, 2000. Geller, J.T., M.B. Kowalsky, P.K. Seifert and K.T. Nihei, Acoustic detection of immiscible liquids in sand, Geophysical Research Letters, 27(3), 417-420, 1999. Goth-Goldstein, R., H-Y. Holman and M. Russell, In vitro model for intestinal uptake of benzo[a]pyrene, Environmental Health Perspectives, 1999. Gritto, R., T.M. Daley and E.L. Majer, Seismic mapping of the subsurface structure at the Ryepatch Geothermal Reservoir, Berkeley Lab Report LBNL-47032, 2000. Gritto, R., V.A. Korneev and L.R. Johnson, Inversion of scattered waves for material properties in fractured rock, Berkeley Lab Report LBNL-39109, 1999. Gritto, R., V.A. Korneev, and L.R. Johnson, Nonlinear 3-dimensional inversion of lowfrequency scattered elastic waves, Pure and Applied Geophysics, 155, 1-33, 1999. Gritto, R., and E.L. Majer, Seismic mapping of subsurface cavities, in SAGEEP 2000, Berkeley Lab Report LBNL-44606, 1999. Gritto, R., A.E. Romero and T.M. Daley, VSP analysis at Long Valley Caldera, Eastern California, Berkeley Lab Report LBNL39108, 1999.

Earth Sciences Division Berkeley Lab

Annual Report 1999 - 2000

Publications 1999-2000

Gritto, R., E.L. Majer and T.M. Daley, Development and application of 3-D seismic imaging methods for geothermal environments, Geothermal Resources Council Trans., 24, pp. 235-238, 2000. Grote, K., S. Hubbard, A. Lawrence, J. Harvey, M. Riemer, J. Peterson and Y. Rubin, Nondestructive monitoring of sub-asphalt water content using surface ground penetrating radar techniques, EOS 80(46), PF291,1999. Guay, C.K., and J.K.B. Bishop, A rapid birefringence method for measuring suspended CaCO3 concentrations in water, Deep-Sea Research, submitted. Halliday, A.N., J.N. Christensen, D-C. Lee, C.M. Hall, X. Luo and M. Rehkamper, Multiple-collector inductively coupled plasma mass spectrometry, in Inorganic Mass Spectrometry, (C.M. Barshirk, D.C. Duckworth, D.H. Smith, eds.), Marcel Dekker Inc., New York, N.Y., 2000. Haukwa, C., Mountain-scale coupled processes (TH) models, MDL-NBSHS-000007, Las Vegas, Nev., CRWMS M&O, 1999. Haukwa, C.B., Y.S. Wu and G.S. Bodvarsson, Thermal loading studies using the Yucca Mountain unsaturated zone model, J. Contaminant Hydrology – Special Issue, 38, 217-255, 1999. Hinds, J., and L., Pan, Development of numerical grids for UZ flow and transport modeling, ANL-NBS-HS-000015 REV 00, Las Vegas, Nevada, CRWMS M&O, 2000. Holman, H-Y.N., R. Goth-Goldstein, M.C. Martin, M.L. Russel and W.R. McKinney, Low-dose responses to 2,3,7,8-tetrachlorodibenzo-p-dioxin in single living human cells measured by synhrotron infrared spectromicroscopy, Environmental Science & Technology, 34(12), 2513-2517, 1999. Holman, H.-Y.N., D.L. Perry, M.C. Martin and W.R. McKinney, Applications of synchrotron infrared microspectroscopy to the study of inorganic–organic interactions at the bacterial-mineral interface, in Application of Synchrotron Radiation Techniques to Materials Sciences, MRS Symposium Series, 54, in press. Holman, H-Y.N., D.L. Perry, M.C. Martin, G.M. Lamble, W.R. McKinney and J.C. Hunter-Cevera, Real-time characterization of biogeochemical reduction of Cr(VI) on basalt surfaces by SR-FTIR imaging, Geomicrobiology Journal, 16(4), 307-324, 1999. Holman, H-Y.N., Y.W. Tsang and W.R. Holman, Mineralization of sparsely water-soluble polycyclic aromatic hydrocarbons in a water table fluctuation zone, Environmental Science & Technology, 33(11), 1819-1824, 1999. Holman, H-Y.N., M. Zhang, R. Goth-Goldstein, M.C. Martin, M. Russell, W.R. McKinney, M. Ferrari and J.C. Hunter-Cevera, Detecting exposure to environmental organic toxins in individual cells: towards development of a micro-fabricated device, in SPIE’s BiOS ‘99, LBNL-43749, 1999. Hoversten, G.M., S. Constable and H.F. Morrison, Marine magnetotellurics for base salt mapping: Gulf of Mexico field-test at the Gemini structure, Geophysics, 65(5) 1476-1488, 1999. Hoversten, G.M., and L.R. Myer, Monitoring of CO2 sequestration using integrated geophysical and reservoir data, Proc. Fifth International Conference on Greenhouse Gas Control Technologies, Cairns, Australia, Aug. 13-16, 2000. 122

Hoversten, G.M., G.A. Newman, H.F. Morrison, E. Gasperikova and J.I. Berg, Reservoir characterization using crosswell EM inversion: A feasibility study for the Snorre Field, North Sea, Geophysics, in press. Hu, M.Q., T.J. Kneafsey, R.C. Trautz and J.S.Y. Wang, Tracer penetration into welded tuff matrix from the flowing fracture, Water Resources Research, submitted. Hu, M.Q., R. Salve, W. Stringfellow and J. Wang, Field tracer transport tests in unsaturated fractured tuff, Journal of Contaminant Hydrology, submitted. Huang, K., Y.W. Tsang and G.S. Bodvarsson, Simultaneous inversion of air injection tests in fractured unsaturated tuff at Yucca Mountain, Water Resources Research, 35(8), 2375-2386, 1999. Hubbard, S.S., Y. Rubin and E. Majer, Spatial correlation structure estimation using geophysical and hydrogeological data, Water Resources Research, 35(6), 1809-1825, 1999. Hunter-Cevera, J.C., The value of microbial diversity, Current in Microbiology, in press. Hunter-Cevera, J.C., and A. Belt, Isolation of cultures, industrial microbiology and biotechnology, ASM Press, in press. Kaelin, B., and L.R. Johnson, Using seismic crosswell surveys to determine the aperture of partially water saturated fractures, Geophysics, accepted. Karasaki, K., B. Freifeld, A. Cohen, K. Grossenbacher, P. Cook and D.W. Vasco, A multidisciplinary fractured rock characterization study at Raymond field site, Raymond, CA, Journal of Hydrology, 236(12), 17-34, 2000. Keers, H., L. Johnson and D. Vasco, Acoustic crosswell imaging of seismic waveforms, Geophysics, in press. Keers, H., L. Johnson and D. Vasco, Poroelastic crosswell imaging using asymptotic waveforms, Geophysics, submitted. Keers, H., D.W. Vasco and L.R. Johnson, Viscoacoustic cross-well imaging using asymptotic waveforms, Geophysics, in press. Kennedy, B.M., C. Janik, D. Benoit and D.L. Shuster, Natural geochemical tracers for injectate fluids at Dixie Valley, in Proc. 24th Workshop on Geothermal Reservoir Engineering, Stanford Geothermal Program Report SGP-TR-162, pp. 108-115, 1999.

Earth Sciences Division Berkeley Lab

Annual Report 1999 - 2000

Publications 1999-2000

Kennedy, B. M., T.P. Fischer and D.L. Shuster, Heat and helium in geothermal systems, Proc. 25th Workshop on Geothermal Reservoir Engineering, Stanford, Calif., Stanford Geothermal Program Report SGP-TR-165, pp. 167-173, 2000. Kennedy, B.M., and D.L. Shuster, Noble gases: sensitive natural tracers for detection and monitoring injectate returns to geothermal reservoirs, Geothermal Resources Council Trans., 24, 247-252, 2000. Kharaka, Y.K., J. James, W. Thordsen, C. Evans and B.M. Kennedy, Geochemistry and hydromechanical interactions of fluids associated with the San Andreas Fault System, California, in Faults and Subsurface Fluid Flow in The Shallow Crust, AGU Geophysical Monograph 113, American Geophysical Union, 1999. Kim, J., J.-E. Lee and N. Miller, A multi-year regional climate simulation for the western United States using the Mesoscale Atmospheric Simulation model, American Geophysical Union Eos Transactions, 80, Nov. 16, 1999. Kim, J., N. Miller, J. Farrara and S. Hong, A seasonal precipitation and streamflow hindcast and prediction study in the western United States during the 1997/1998 winter season, J. Hydrometeorology, in press. Kirkpatrick, A., and E. Majer, Monitoring injection at The Geysers, California, geothermal field with microseismic methods, Berkeley Lab Report LBNL-43198, 1999. Kirkpatrick, A., J.E. Peterson Jr., E.L. Majer and R. Nadeau, Characteristics of microseismicity in the DV11 injection area, Southeast Geysers, California, Proc. 24th Workshop on Geothermal Reservoir Engineering, Stanford Geothermal Program Report SGP-TR-162, pp. 236-242, 1999. Kiryukhin, A., and K. Pruess, Modeling studies of pressure cycling associated with seismicity in Mutnovsky Geothermal Field, Kamchatka, Russia, Proc. World Geothermal Congress 2000, Japan, May 28-June 10, 2000, pp. 2659-2664, 2000. Kiryukhin, A., K. Pruess, K. Maltseva, and I. Delemen, Modeling Studies of the Paratunsky Geothermal Field, Kamchatka, Russia, Proc. 25th Workshop on Geothermal Reservoir Engineering, Stanford Geothermal Program Report SGP-TR-165, pp. 374-380, 2000. Korneev, V., and L.R. Johnson, Attenuation and fluctuations of elastic waves due to random scattering from inclusions, LBNL-43341, 1999. Kyriakidis, P.C., J. Kim and N.L. Miller, Generation of synthetic daily precipitation records for hydroclimatic impact assessment: A geostatistical perspective, Journal of Climate, accepted. Kyriakidis, P.C., N.L. Miller and J. Kim, Propagation of uncertainty in regional climate model precipitation forecasts to hydrologic impact assessment, Journal of Hydrometeorology, in review. Laverov, N.P., V.I. Velichkin, A.A. Pek and V.D. Akunov, The geological disposal of high-level nuclear waste: conceptual approach and related problems, Berkeley Lab Report LBNL-45282, 2000. Lee, S.K., H.J. Kim, Y. Song, H.F. Morrison and K.H. Lee, A new formulation of magnetic field integral equation for 3-D EM modeling, paper presented at 2nd International Symposium on 3-D Electromagnetics, Berkeley Lab Report LBNL-43940, 1999. Liou, T.S. Statistical analysis of liquid seepage in partially saturated heterogeneous fracture systems, Berkeley Lab Report LBNL-44823, 1999.

Lippmann, M., A. Truesdell and G. Frye, The Cerro Prieto and Salton Sea Geothermal Fields – Are they really alike?, Proc. 24th Workshop on Geothermal Reservoir Engineering, Standford Geothermal Program Report SGP-TR-162, pp. 1-10, 1999. Lippmann, M.J., A.H. Truesdell and K. Pruess, The control of fault H on the hydrology of the Cerro Prieto III area, Proc. 25th Workshop on Geothermal Reservoir Engineering, Stanford, Calif., Stanford Geothermal Program Report SGP-TR-165, pp. 266-274, 2000. Liu, J., Analysis and modeling of pore-water chemical data, Analysis/Model Report “UZ Models and Flow Models,” Section 6.4, MDL-NBS-HS-000006, Lawrence Berkeley National Laboratory, 2000. Liu, H.H., and G.S. Bodvarsson, A simple scheme to determine particle transfer in random walk algorithms for dual continua, Water Resources Research, in press. Liu, H.H., and G.S. Bodvarsson, Constitutive relations for unsaturated flow in a fracture network: A numerical investigation, Journal of Hydrology, submitted. Liu, H.H., G.S. Bodvarsson and L. Pan, Determination of particle transfer in random walk particle methods for fractured porous media, Water Resources Research, in press. Liu, H.H., C.B. Haukwa, C.F. Ahlers, G.S. Bodvarsson, A. Flint and William Guertal, Modeling flow and transport in unsaturated fractured rocks: An evaluation of the continuum approach, Water Resources Research, in review. Malkovsky, V.I., A.A. Pek and V.I. Velichkin, A new refined method for computer simulation of transport in the geosphere and its application of leakage from underground HLW repositories, Berkeley Lab Report LBNL-45280, 1999. Marques, O., and D. Vasco, Solving large linear inverse problems in geophysics by means of Eigenvalue calculations, presented at First SIAM Conference on Computational Science and Engineering, 2000. Mays, D., and B. Faybishenko, Washboards in unpaved highways as a complex dynamic system, Complexity, submitted. McCullough, J., NABIR News, Winter 1999, v. 3, n. 1, Berkeley Lab Report PUB-784, 1999. 123

Publications 1999-2000

Annual Report 1999 - 2000

McCullough, J., T. Hazen and S.M Benson, Bioremediation of metals and radionuclides: What it is and how it works, Berkeley Lab Report LBNL42595, 1999. Miller, N.L., and J. Kim, Climate change sensitivity analysis for two California water sheds: downscaled climate and streamflow study of the southwestern United States, J. American Water Resources Assoc., 36, 657-661, 2000. Miller, N.L., and J. Kim, The Regional Climate System Model: Southwestern United States, Eastern Asia, and Northeastern Australia, WMO/ICSU/IOC World Climate Research Programme, Report No. 28, WMO/TD-No. 942, 1999. Miller, N.L., J. Kim, R.K. Hartman and J. Farrara, Downscaled climate and streamflow study of the Southwestern United States, Journal of the American Water Resources Association, 35(6), 1-13, 1999. Miller, N.L., J. Kim and J.Y. Zhang, Coupled precipitation-streamflow simulations at the GAME/HUBEX site: Xixian Basin, Journal of the Meteorological Society of Japan, accepted. Mizunaga, H., K.H. Lee and H.J. Kim, Three-dimensional transient electromagnetic modeling in the Laplace Domain, Berkeley Lab Report LBNL42677, 1999. Moore, J.N., D. I. Norman and B.M. Kennedy, Fluid-inclusion gas composition from an active magmatic-hydrothermal system: A case study of The Geysers, California Geothermal Field, Chemical Geology, in press. Moridis, G.J., Semianalytical solutions for parameter estimation in diffusion cell experiments, Water Resources Research, 35(6), 1729-1740, 1999. Moridis, G., and Q. Hu, Radionuclide transport models under ambient conditions, MDL-NBS-HS-000008, Las Vegas, Nev., CRWMS M&O, 2000. Moridis, G., S. Finsterle and J. Heiser, Evaluation of alternative designs for an injectable barrier at the Brookhaven National Laboratory Site, Long Island, New York, Water Resources Research, 35(10), 2937-2953, 1999. Moridis, G.J., Q. Hu, Y.S. Wu and G.S. Bodvarsson, Modeling studies of radionuclide transport in the unsaturated zone of Yucca Mountain, Nevada, Berkeley Lab Report LBNL-45870, 2000. Moridis, G.J., Y-S. Wu and K. Pruess, EOS9NT: A TOUGH2 module for the simulation of water flow and solute/colloid transport in the subsurface, Berkeley Lab Report LBNL-42351, 1999. Mukhopadhyay, S., and Y. Tsang, Understanding the thermal-hydrology in unsaturated fractured rock: The Large Block Test, Proc. 199 American Geophysical Union Fall Meeting, San Francisco, Calif., December 1999. Myer, L.R., A strategy for monitoring of geologic sequestration of CO2, presented and published ENERGEX’2000: Proc. of the 8th International Energy Forum, pp. 1226-1231, Las Vegas, Nev., July 23-28, 2000. Myer, L.R., S. Nakagawa and B.A. Bessinger, Role of local dilatation in formation of compaction bands, Eos, Trans. Am. Geophys. Union, 79(45), F1067, 1999. Myneni, S.C.B., J.T. Brown, G.A. Martinez and W. Meyer-Ilse, Imaging of humic substance macromolecular structures in water and soils, Science, 286(5443), 1335-1337, 1999. Nakagawa, S., K.T. Nihei and L.R. Myer, Shear induced conversion of seismic waves across single fractures, Int. J. Rock Mech. Min. Sci. & Geomech. Abstr., 37(1-2), 203-218, 2000.

Nakagawa, S., K.T. Nihei and L.R. Myer, Stoppass behavior of acoustic waves in a 1-D fractured system, Journal of the Acoustical Society of America, 107(1), 40-50, 2000. Nakagawa, S., K.T. Nihei and L.R. Myer, Wave propagation along a sheared fracture, JGR – Solid Earth, submitted. Narasimhan, T.N., Fourier’s heat conduction equation: history, influence, and connections, Reviews of Geophysics, 37(1), 151-172, 1999. Narasimhan, T.N., Ohm’s Law, Fick’s Law, Joule’s Law and ground water flow, in Proc. Theory Modeling and Field Investigations in Hydrogeology: A special volume in honor of Shlomo P. Neuman, Tucson, Ariz., Oct. 17, 1998, Berkeley Lab Report LBNL-42824, in press. Narasimhan, T.N. and J. Reynolds, Protection of subsurface aquifers: A broader context, Acta Hungaria, submitted. Nihei, K., P. Goldstein, L. Myer, K. Mayeda and R. Parker, Natural fracture characterization using passive seismic wave illumination, GasTIPS, 6 (1), 2000. Nikolskii, I., and B. Faybishenko, Semi-analytical approach for calculating the horizontal drain spacing taking into account infiltration through the vadose zone, Soil Science Society of America Journal, submitted. Nguyen, T.S., L. Borgesson, M. Chijimatsu, J. Rutqvist, T. Fujita, J. Hernelind, A. Kobayashi, Y. Ohnishi, M. Tanaka and L. Jing, Hydro-mechanical response of a fractured rock mass to excavation of a test pit— the Kamishi mine experiment in Japan, International Journal of Rock Mechanics and Mining Sciences, submitted. Oh, K.C., Biologically active (“bioactive”) absorbents/adsorbents and additives used in pollution control and remediation: acceptance criteria and process guidance, Berkeley Lab Report LBNL-46862, 2000. Oldenburg, C.M. and K. Pruess, Plume separation by transient thermohaline convection in porous media, Geophysical Research Letters, 26(19), 2997-3000, 1999. Oldenburg, C.M., and K. Pruess, Layered thermohaline convection in hypersaline geothermal systems, Transport in Porous Media, in press.

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Oldenburg, C.M., and K. Pruess, Simulation of propagating fronts in geothermal reservoirs with the implicit Leonard total variation diminishing scheme, Geothermics, 29, 1-25, 2000. Oldenburg, C.M., and K. Pruess, Thermohaline convective mixing at a brine interface, in Proc., 25th Workshop on Geothermal Reservoir Engineering, Stanford, Calif., Stanford Geothermal Program Report SGP-TR-165, pp. 152-158, 2000. Oldenburg, C.M., K. Pruess and S.M. Benson, Process modeling of CO2 injection into natural gas reservoirs for carbon sequestration and enhanced gas recovery, Proc. of the 220th National Meeting of the ACS, Washington, D.C., Aug. 20-24, 2000. O’Sullivan, M.J., K. Pruess and M.J. Lippmann, Geothermal reservoir simulation: The state-of-practice and emerging trends, Proc. World Geothermal Congress 2000, Japan, May 28-June 10, 2000, pp. 4065-4070 (also submitted to Geothermics), 2000. Park, S.-H., and G. Sposito, Monte Carlo simulation of total radial distribution functions for interlayer water in Li-, Na-, and K-montmorillonite hydrates, J. Phys. Chem. B, 104: 4642, Berkeley Lab report LBNL-45842, 2000. Parker, P.B., Genetic algorithms and their use in geophysical problems, Ph.D. Thesis, Berkeley Lab Report LBNL-43148, 1999. Persoff, P. Estimating fracture closure under hydrothermal conditions, Geothermal Resources Council Trans., 24, 273-279, 2000. Persoff, P., and J.B. Hulen, Hydrologic characterization of reservoir metagraywacke from shallow and deep levels of The Geysers vapordominated geothermal system, California, Geothermics, accepted. Pfiffner, S.M., A.V. Palumbo, T.J. Phelps, J.J. Beauchamp, D.B. Ringelberg, H.C. Pinkart, D.C. White and T.C. Hazen, Microbial monitoring as a measure of success for in-situ TCE bioremediation, Environmental Science and Technology, submitted. Pratt, M. (ed.), DOE/NABIR PI Workshop: Abstracts, January 31-February 2, 2000, Berkeley Lab Report LBNL-44645, 2000. Pruess, K., A mechanistic model for water seepage through thick unsaturated zones in fractured rocks of low matrix permeability, Water Resources Research, 35(4), 1039-1051, 1999. Pruess, K. Multiphase flow in fractured rocks – lessons learned from mathematical models, in Dynamics of Fluids in Fractured Rocks: Concepts and Recent Advances, AGU Geophysical Monograph 122, pp. 25-29, American Geophysical Union, 1999. Pruess, K., Multiphase fluid flow and heat transfer at Hanford single-shell tanks – A progress report on modeling studies, Berkeley Lab Report LBNL-45283, 2000. Pruess, K., Multiphase flow in fractured rocks – some lessons learned from mathematical models, in Dynamics of Fluids in Fractured Rocks: Concepts and Recent Advances, AGU Geophysical Monograph 122, pp. 225-234, American Geophysical Union, 2000. Pruess, K., Treatment of two-phase flow in repository performance assessment at Yucca Mountain, in Gas Generation, Accumulation and Migration In Underground Repository Systems for Radioactive Waste: Safety-Relevant Issues, submitted. Pruess, K., B. Faybishenko and G.S. Bodvarsson, Alternative concepts and approaches for modeling flow and transport in thick unsaturated zones of fractured rocks, J. Contaminant Hydrology – Special Issue, 38, 281322, 1999.

Pruess, K., and J. Garcia, A systematic approach to local grid refinement in geothermal reservoir simulation, Proc. World Geothermal Congress, Japan, May-June 2000, pp. 28092814, 1999. Pruess, K., and J. Garcia, Multiphase flow dynamics during CO2 disposal into saline aquifers, Berkeley Lab Report LBNL-46793, 2000. Pruess, K., C.M. Oldenburg and G.J. Moridis, TOUGH2 User’s Guide Version 2, Berkeley Lab Report LBNL-43134, 1999. Pruess, K., M.J. O’Sullivan and B.M. Kennedy, Modeling of phase-partitioning tracers in fractured reservoirs, Proc. 25th Workshop on Geothermal Reservoir Engineering, Stanford, Calif., Stanford Geothermal Program Report SGP-TR-165, pp. 334-348, 2000. Quinn, N.W.T., A decision support system for realtime management of water quality in the San Joaquin River, California, in Environmental Information & Decision Support 1999, Kluwer Academic Publishers, 1999. Quinn, N.W.T., J. McGahan and M. Delamore, Innovative drainage management techniques to meet monthly and annual selenium load targets, Calif. Agriculture, in press. Quinn, N.W.T., N.L. Miller, J.A. Dracup and L.F. Grober, An integrated modeling system for environmental impact analysis of climate variability and extreme weather events in the San Joaquin Basin, California, in Environmental information and Decision Support 2000, Kluwer Academic Publishers, 2000. Ritcey, A.C., and Y. S. Wu, Evaluation of the effect of future climate change on the distribution and movement of moisture in the unsaturated zone at Yucca Mountain, NV, J. Contaminant Hydrology – Special Issue, 38, 257-279, 1999. Rutqvist, J., J. Noorishad and C-F. Tsang, Coupled thermohydromechanical analysis of a heater test in unsaturated clay and fractured rock at Kamaishi Mine, Berkeley Lab Report LBNL-44203, 1999. Rutqvist, J., C.-F. Tsang and O. Stephansson, Uncertainty in the maximum principal stress estimated from hydraulic fracturing measurements due to the presence of the induced fracture, International Journal of Rock Mechanics and Mining Sciences, v.37, no.1-2, pp.107-120, 2000.

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Publications 1999-2000

Reynolds, J.L., and T.N. Narasimhan, Water resources development in Santa Clara Valley, California: insights into the human-hydrologic relationship, Berkeley Lab Report LBNL-46598, 2000. Salve, R., Seepage response along an alluvial valley in a semi-arid catchment, Hydrological Processes, submitted. Salve, R., Variations in soil moisture content in a rangeland catchment, Journal of Range Management, submitted. Salve, R., and C.M. Oldenburg, Water flow within a fault in altered nonwelded tuff, Water Resources Research, submitted. Salve, R., and T.K. Tokunaga, Flow process in a rangeland catchment in California, Journal of Range Management, 53(5), 489-498, 2000. Salve, R. T., J.S.Y. Wang and T.K. Tokunaga, A probe for measuring wetting front migration in rocks, Water Resources Research, submitted. Seifert, P.K., B. Kaelin and L.R. Johnson, Effect on ultrasonic signals of viscous pore fluids in unconsolidated sand, J. of the Acoustical Society of America, in press. Seol, S.J., Y. Song and K.H. Lee, Fracture characterization using single-hole EM data, in World Geothermal Congress 2000, Japan, May-June, 2000, pp. 1725-1730, 2000. Shan, C., An analytical solution for the capture zone of two arbitrarily located wells, Journal of Hydrology, 222(1-4), 123-128, 1999. Shan, C., and I. Javandel, Approximate equations for gas flow through porous media, Water Resources Research, submitted. Shan, C., I. Javandel and P. A. Witherspoon, Characterization of leaky faults: study of air flow in faulted vadose zone, Water Resources Research, 35(7), 2007-2013, 1999. Shvidler, M., and K. Karasaki, Exact averaging of stochastic equations for transport in random fields, Water Resources Research, submitted. Shvidler, M., and K. Karasaki, Multi-continuum description of flow and transport and splitting the fields in composite heterogeneous media, Water Resources Research, submitted. Shvidler, M., and K. Karasaki, Probability density functions for solute transport in random fields, Water Resources Research, submitted. Silin, D.B., and T.W. Patzek, Control of water injection into a layered formation, SPE 59300, paper presented at SPE/DOE Improved Oil Recovery Symposium, Tulsa, Okla., April 3â&#x20AC;&#x201C;5, 2000. Silin, D.B., and T.W. Patzek, Support-operators method in the identification of permeability tensor orientation, Proc. 2000 SPE/DOE Improved Oil Recovery Symposium, LBNL-46517, 2000. Silin, D.B., and C.-F. Tsang, Identification of formation properties from operations data, Journal of Hydrology, submitted. Simmons, A., A. Unger, and M. Murrell, Natural analogs for the unsaturated zone, ANL-NBS-HS-000007 Rev 00., Las Vegas, Nev., CRWMS M&O, 2000. Smith, T., and K.H. Lee, Controlled-source magnetotellurics: source effects, Berkeley Lab Report LBNL-43121, 1999. Solodov, I.N., A.V. Zotov, A.D. Khoteev, A.P. Mukhamet-Galeev, B.R. Tagirov and J. Apps, Geochemistry of natural and contaminated subsurface waters in fissured bed rocks of the Lake Karachai Area, Southern Urals, Russia, App. Geochem., accepted. Song, D.L., L. Alvarez-Cohen, M.E. Conrad and K. Sorenson, Monitoring of enhanced in-situ bioremediation of trichloroethylene using stable carbon isotopes, Program and Abstracts for the 4th International Symposium on Subsurface Microbiology, Vail, Colo., 1999.

Sonnenthal, E.L., and G.S. Bodvarsson, Constraints on the hydrology of the unsaturated zone at Yucca Mountain, Nevada, from three-dimensional models of chloride and strontium geochemistry, J. Contaminant Hydrology â&#x20AC;&#x201C; Special Issue, 38, 107-156, 1999. Sonnenthal, E.L., and N.F. Spycher, Drift-scale coupled processes (DST and THC seepage) models, Analysis/Model Report N0120/U0110, MDL-NBS-000001, Lawrence Berkeley National Laboratory, Berkeley, Calif., 2000. Sposito G., S.-H. Park and R. Sutton, Monte Carlo simulation of the total radial distribution function for interlayer water in sodium and potassium montmorillonites, Clays Clay Miner, 47: 192, 1999. Sposito, G., N.T. Skipper, R. Sutton, S.-H. Park, A.K. Soper and J.A. Greathouse, Surface geochemistry of the clay minerals, Proc. National Academy of Sciences, 96, 33583364, 1999. Stirling, C.H., D.-C. Lee, J.N. Christensen and A.N. Halliday, High precision in situ U234U-230Th isotopic analysis using laser ablation multiple-collector ICPMS, Geochimica et Cosmochimica Acta, submitted. Stocking, A.J., R.A. Deeb, A.E. Flores, W. Stringfellow, J. Talley, R. Brownell and M.C. Kavanaugh, Bioremediation of MTBE: A review from a practical perspective, Biodegradation, in press. Stringfellow, W.T., Using iso-pentane to stimulate MTBE biodegradation in ground water treatment systems, paper presented at EPA MTBE Biodegradation Workshop, Cincinnati, Ohio, Feb. 1-3, 2000. Stringfellow, W.T., and L. Alvarez-Cohen, Evaluating the relationship between the sorption of PAHs to bacterial biomass and biodegradation, Water Research, 33(11), 2535-2544, 1999. Stringfellow, W.T., R.D. Hines, D.R. Cockrum and S.T. Kilkenny, Factors influencing biological treatment of MTBE in fixed film reactors, in Bioremediation and Phytoremediation of Chlorinated and Recalcitrant Compounds (G.B. Wickramanayake, et al, eds), Battelle Press, pp.175-181, 2000.

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Stringfellow, W.T., R.D. Hines and S.T. Kilkenny, Applying co-metabolic biological reactions for the ex-situ treatment of MTBE contaminated groundwater, paper presented at American Chemical Society National Meeting, San Francisco, Calif., March 26-30, 2000. Stringfellow, W.T., M.Q. Hu, R. TerBerg and G. Castro, Analyzing multiple fluorobenzoate tracers in the presence of interfering compounds, Berkeley Lab Report LBNL-46976, 1999. Su, G.W., Flow dynamics and solute transport in unsaturated rock fractures, Berkeley Lab Report LBNL-44440, 1999. Su, G.W., J.T. Geller, K. Pruess and F. Wen, Experimental studies of water seepage and intermittent flow in unsaturated, rough-walled fractures, Water Resources Research, 35(4), 1019-1037, 1999. Tokunaga, T., J. Wan and S.R. Sutton, Transient film flow on rough fracture surfaces, Water Resources Research, 36(7), 1737-1746, 2000. Torgersen, T., and B.M. Kennedy, Air-Xe enrichments in Elk Hills oil field gases: role of water in migration and storage, Earth Planet. Sci. Lett., 167, 239-253, 1999. Trautz, R.C. and J.S.Y.m Wang, Evaluation of seepage into an underground opening using small-scale field experiments, Yucca Mountain, Nevada, in 2000 SME Annual Meeting & Exhibit, Salt Lake City, Utah, Feb. 28 – March 1, 2000. Tretbar, D.R., G.B. Arehart and J N. Christensen, Dating gold deposition in a Carlin-type gold deposit using Rb/Sr methods on the mineral galkhaite, Geology, 28(10), 947-950, 2000. Trew, M., M. O’Sullivan, C. Harvey, E. Anderson and K. Pruess, Computer modeling of gas and liquid tracers in geothermal reservoirs, Proc. 25th Workshop on Geothermal Reservoir Engineering, Stanford Geothermal Program Report SGP-TR-165, pp. 43-50, 2000. Truesdell, A.H., M.J. Lippmann, J. de Leon, and M.H. Rodriguez, Cerro Prieto cold water injection: effects on nearby production wells, Geothermal Resources Council Trans., 23, 367-376, 1999. Tsang, C.-F., Linking thermal, hydrological and mechanical processes in fractured rocks, in Annual Review of Earth and Planetary Sciences, 27, in press. Tsang, C.-F., Modeling groundwater flow and mass transport in heterogeous media-issues and challenges, in Proc. International Association of Hydrogeologists XXX Congress 2000, Capetown, South Africa, Nov. 26Dec. 1, 2000. Tsang, C.-F., L. Moreno, Y.W. Tsang and J. Birkholzer, Dynamic channeling of flow and transport in saturated and unsaturated heterogeneous media, AGU Monograph GM42, 2000. Tsang, C.-F., O. Stephansson and J.A. Hudson, A discussion of thermohydro-mechanical (THM) processes associated with nuclear waste repositories, International Journal of Rock Mechanics and Mining Sciences, 37(1-2), 397-402, 1999. Tsang, Y.W., J. Apps, J.T. Birkholzer, B. Freifeld, M.Q. Hu, J. Peterson, E. Sonnenthal and N. Spycher. Yucca Mountain single heater test final report: Yucca Mountain Site Characterization Project, Berkeley Lab Report LBNL-42537, 1999. Tsang, Y.W., J. Apps, J.T. Birkholzer, J.E. Peterson, E. Sonnenthal, N. Spycher and K.H. Williams, Yucca Mountain drift scale test progress report, Berkeley Lab Report LBNL-42538, 1999. 127

Tsang, Y.W., and J.T. Birkholzer, Predictions and observations of the thermal-hydrological conditions in the single heater test, Journal of Contaminant Hydrology- Special Issue, 38(1-3), 385-425, 1999. Tsang, Y.W., and B.M. Freifeld, Role of fractures at different scales in underground heater experiments, Proc. Dynamics of Fluids in Fractured Rocks: Concepts and Recent Advances, Feb. 10-12, Berkeley, Calif., pp. 120-123, 2000. Unger, A.J.A., B. Faybishenko, G.S. Bodvarsson and A.M. Simmons, A three-dimensional model for simulation ponded infiltration tests in the variably saturated fractured basalt at the Box Canyon site, Idaho, Journal of Contaminant Hydrology, submitted. Vasco, D.W., and A. Datta-Gupta, Asymptotic solutions for solute transport: A formalism for tracer tomography, Water Resources Research, 35(1), 1-16, 1999. Vasco, D., and A. Datta-Gupta, Asymptotics, saturation fronts, and high resolution reservoir characterization, Transport in Porous Media, in press. Vasco, D.W., K. Karasaki and C. Doughty, Using surface deformation to image reservoir dynamics, Geophysics, 65(1), 132-147, 1999. Vasco, D.W., H. Keers and K. Karasaki, Estimation of reservoir properties using transient pressure data: An asymptotic approach, Water Resources Research, in press. Vasco, D., S. Yoon and A. Datta-Gupta, Integrating dynamic data into high-resolution reservoir models using streamlinebased analytic sensitivity coefficients, Soc. Petr. Eng. Journal, 4 (4), 1999 . Wan, J., T.K. Tokunaga, T. Orr, J. O’Neill and R.W. Conners, Glass cast of rock fracture surfaces: A new tool for studying flow and transport, Water Resources Research, 36, 355-360, 2000. Wan, J., and T.K. Tokunaga, Surface excess of clay colloids at gas-water interfaces, J. Colloid and Interface Science, submitted. Wan, J., T.K. Tokunaga, E. Saiz, K. Olson and S. Veerapaneni, Colloid formation during infiltration of waste tank liquid into Hanford sediments, Environ. Sci. Technol., submitted. Wang, D., J.Y. Shin, M.A. Cheney, G. Sposito and T.G. Spiro, Manganese dioxide as a catalyst for oxygen-independent atrazine dealkylation, Environmental Science and Technology, 33(18), 3160-3165, 1999.

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Annual Report 1999 - 2000

Wang, J.S.Y, R.C. Trautz, P.J. Cook, S. Finsterle, A.L. James and J.T. Birkholzer, Field tests and model analyses of seepage into drift, J. Contaminant Hydrology – Special Issue, 38, 323-347, 1999. Waychunas, G., J.A. Davis and R. Reitmeyer, Grazing-incidence EXAFS study of FE3+ sorption on single crystal quartz substrates, J. Synchrotron Radiation 6, 615-617, 1999. Wu, Y-S., A virtual node method for treatment of wells in modeling multiphase flow in reservoirs, Proc. 24th Workshop on Geothermal Reservoir Engineering, Stanford, Calif., Stanford Geothermal Program Report SGP-TR-162, pp. 144-157, 1999. Wu, Y.S., A virtual node method for handling well bore boundary conditions in modeling multiphase flow in porous and fractured media, Water Resources Research, 36, 807-814, 2000. Wu, Y.S., Numerical simulation of non-Darcy flow in porous and fractured media, Geothermal Resources Council Trans., 24, 641-646, 2000. Wu, Y-S., Non-Darcy displacement of immiscible fluids in porous media, Water Resources Research, submitted. Wu, Y-S., On the effective continuum method for modeling multiphase flow, multicomponent transport and heat transfer in fractured rock, in Dynamics of Fluids in Fractured Rocks: Concepts and Recent Advances, AGU Geophysical Monograph 122, pp. 299-312, 2000. Wu, Y.-S., C.B. Haukwa and G.S. Bodvarsson, A site-scale model for fluid and heat flow in the unsaturated zone of Yucca Mountain, Nevada, J. Contaminant Hydrology – Special Issue, 38, 185-215, 1999. Wu, Y.-S., J. Liu, T. Xu, C. Haukwa, W. Zhang, H.H. Liu, and C.F. Ahlers, UZ Flow models and submodels, MDL-NBS-HS-000006 Rev00., Las Vegas, Nev., CRWMS M&O, 2000. Wu, Y.S., A.C. Ritcey and G.S. Bodvarsson, A modeling study of perched water phenomena in the unsaturated zone at Yucca Mountain, J. Contaminant Hydrology – Special Issue, 38, 157-184, 1999. Wu, Y.S. and K. Pruess, Numerical simulation of nonisothermal multiphase tracer transport in heterogeneous fractured porous media, Advances in Water Resources, 23, 699-723, 2000. Wu, Y-S., W. Zhang, L. Pan, J. Hinds, and G.S. Bodvarsson, Capillary barriers in unsaturated fractured rocks of Yucca Mountain, Nevada, Water Resources Research, submitted. Xie, G, and J. Li, New parallel stochastic global integral and local differential equation modeling and inversion, Physica D, 133, 477-487, 1999. Xie, G., J. Li, E. Majer, D. Zuo and M. Oristaglio, New 3-D electromagnetic modeling and nonlinear inversion, Geophysics, 804-822, 1999.

Xu, T., and K. Pruess, Hydrothermal fluid flow and mineral alteration in a fractured rock under multiphase H2O - CO2 mixture conditions, Proc. World Geothermal Congress 2000, Japan, May-June 2000, pp. 2983-2989, 2000. Xu, T., and K. Pruess, On fluid flow and mineral alteration in fractured cap rock of magmatic hydrothermal systems, Journal of Geophysical Research, submitted. Xu, T., K. Pruess and G. Brimhall, An improved equilibrium-kinetics speciation algorithm for redox reactions in variably saturated subsurface flow systems, Computers & Geosciences, 25, 655-666, 1999. Xu, T., K. Pruess and G. Brimhall, Oxidative weathering chemical migration under variably saturated conditions and supergene copper enrichment, Berkeley Lab Report LBNL-43129, 1999. Zawislanski, P.T., and B. Faybishenko, New casing and backfill design for neutron logging access boreholes, Groundwater J., in press. Zawislanski, P.T., C.M. Oldenburg, C.A. Doughty and B.M. Freifeld, Application of the vadose zone monitoring system at a TCE-contaminated site: field data and modeling summary, Berkeley Lab Report LBNL44325, 1999. Zawislanski, P.T., R. Salve, B. Freifeld, H.S. Mountford, R. Dahlquist, S.J. Rodriguez, and B. Faybishenko, Monitoring and data analysis for the vadose zone monitoring system (VZMS), McClellan AFB 11/20/1998-2/20/1999, Berkeley Lab Report LBNL-43084, 1999. Zawislanski, P.T., T.K. Tokunaga, S.M. Benson, H.S. Mountford, H. Wong, T. Alusi, R. Terberg and K. Olson, Hydrological and geochemical investigations of selenium behavior at Kesterson Reservoir, progress report to the U.S. Bureau of Reclamation, Berkeley Lab Report LBNL-43535, 1999.

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DIVISION DIRECTOR Sally M. Benson

DIVISION DEPUTY DIRECTOR Norman E. Goldstein

Earth Sciences Division Staff 1999-2000

SCIENTISTS/ENGINEERS

Geochemistry Apps, John A. Bishop, James K. Conrad, Mark S. Christensen, John N. Dobson, Patrick Guerin, Marianne Kennedy, B. Mack Kim, Jinwon Miller, Norman L. Myneni, Satish Perry, Dale L. Riley, William Simmons, Ardyth M. Torn, Margaret S. Waychunas, Glenn A.** Wollenberg Jr., Harold A. Zawislanski, Peter T.

Hydrogeology and Reservoir Dynamics Bodvarsson, Gudmundur S. Doughty, Christine A. Faybishenko, Boris A. Finsterle, Stefan A. Freifeld, Barry M. Gonzalez Jr., Emilio Guerin, Marianne Guo, Yonghai Hu, Qinhon Javandel, Iraj Karasaki, Kenzi Kneafsey, Timothy J. Li, Guomin Lippmann, Marcelo J. Liu, Hui-Hai Liu, Jianchun Liou, Ta-Sheng Geophysics and Geomechanics Moridis, George J. Clyde, John R. Mukhopadhyay, Sumit Dougherty, James R. Oldenburg, Curtis M. Feighner, Mark A. Pan, Lehua Geller, Jil T. Persoff, Peter Gritto, Roland Pruess, Karsten Haught, John R. Rutqvist, Jonny Hoffpauir, Cecil Salve, Rohit Hoversten, G. Michael** Silin, Dmitriy Hubbard, Susan S. Sonnenthal, Eric Korneev, Valeri A. Spycher, Nicolas Lee, Ki-Ha Truesdell, Alfred Majer, Ernest L.* Tsang, Chin-Fu* Myer, Larry R. Tsang, Yvonne T. Nihei, Kurt T. Unger, Andre Peterson, John E. Wang, Joseph S. Sell, Russell W. Wu, Yu-Shu Smith, Jeremy T. Xu, Tianfu Tomutsa, Liviu Zimmerman, Robert Vasco, Donald W. Wan, Jiamin Williams, Kenneth H. Xie, Ganquan

Microbial Ecology and Environmental Engineering Borglin, Sharon Hazen, Terry C.* Holman, Hoi-Ying Hunter-Cevera, Jennie C. Quinn, Nigel W. Stringfellow, William T. Tokunaga,Tetsu K.

*Department Head **Deputy Department Head 129

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FACULTY

Geochemistry Boering, Kristie A. Fung, Inez DePaolo, Donald* Dietrich, William Doner, Harvey E. Doyle, Fiona M. Ingram, B. Lynn

Geophysics and Geomechanics Becker, Alex Cooper, George A. Glaser, Steven Johnson, Lane R. McEvilly, Thomas V. Morrison, H. Frank Rector, James W. Sposito, Garrison

Hydrology and Reservoir Dynamics Brimhall, George Narasimhan, T.N. Patzek, Tadeusz W. Radke, Clayton J. Rubin, Yoram Shen, Hsieh W. Witherspoon, Paul A. Microbial Ecology and Environmental Engineering Buchanan, Bob B. Leighton, Terrance J.

POST DOCTORAL FELLOWS Geochemistry Bill, Markus Bryce, Julia G. Cervini-Silva, Javiera Davis, Simon Fischer, Tobias Guay, Christopher Kim, Tae Kook Kong, Ping Kyriakidis, Phaedon C. Lin, Jo Chiu Fang van Soest, Matthijs Veerapaneni, Srinivas Villalobos, Mario Vrdoljak, Gordon A.

Geophysics and Geomechanics Hoppe, Kathryn Keers, Henk Milligan, Paul A. Nadeau, Robert Nakagawa, Seiji Park, Sung-Ho Tseng, Hung-Wen Watanabe, Toshiki

Hydrology and Reservoir Dynamics De, Asoke Fairley, Jerry P. Haukwa, Charles Su, Grace Zhang, Keni Microbial Ecology and Environmental Engineering Chauhan, Sadhana Letain, Tracy 130

Annual Report 1999 - 2000

Earth Sciences Division Berkeley Lab

RESEARCH ASSOCIATES, SPECIALISTS AND TECHNICIANS Geochemistry Alusi, Thana Carpenter, Scott A. Czarnomski, Atlantis Gatti, Raymond C. Macomber, Tara Mountford, H. Scott Olson, Keith R. Owens, Thomas L. Robitaille, Daniel Shuster, David Smith, Donna S. Weekley, Caryl Wood, Todd Zhao, Wenguang

Geophysics and Geomechanics Choi, Youngki Daley, Thomas M. Kirkpatrick, Elizabeth A. Scott, Clark L. Solbau, Ray D.

Hydrology and Reservoir Dynamics Ahlers, C. Fredrik Bandurraga, T. Mark Cohen, Andrew J. Cook, Paul J. Flexser, Steven Gadelle, Frederic Gozalez, Emilio Jr. Hedegaard, Randall F. Hinds, Jennifer Hoch, Gavin Jordan, Preston D. Link, Suzanne M. Liu, Zhuping Lo, Wei-Cheng Menendez-Barreto, Melani Shan, Chao Stanley, Mary TerBerg, Robert Trautz, Robert C. Valladao, Carol Yaros, Heather Zhang, Linbin Zhang, Winnie W. Microbial Ecology and Environmental Engineering Castro, Grace M. Miller, Marla Oh, Keun-Chan Rychel, Erin

GRADUATE STUDENT RESEARCH ASSISTANTS Geochemistry Bessinger, Brad A. Hammersley, Lisa Hendricks, Melissa B. Johnson, Kathleen Maher, Katharine Winter, Stacey J.

Geophysics and Geomechanics Anderson, Heidi L. Bhatt, Divesh Das, Kaushik K. Frangos, William Hildenbrand, Keary L.

Geophysics and Geomechanics (continuted) Kowalsky, Michael Sutton, Rebecca A. Tseng, Hung-Wen Yang, Jeong-Seok Hydrogeology and Reservoir Dynamics Benito, Pascual H. Garcia, Julio

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TECHNICAL, ADMINISTRATIVE AND MANAGEMENT STAFF Aden-Gleason, Nancy Bell, Andre R. Bradley, R. Maren Cushey, Mark Cuzner, Marlene C. Denn, Walter Fink, Maria Fissekidou, Vassiliki A. Glover, Pam Harris, Stephen D. Hodge, Sheryl A. Houseworth, James Kaszuba, David Kramer, Bridget R. Lau, Peter K. Lippert, Donald R. Lucido, Nina

Mangold, Donald C. McClung, Ivelina A. Miller, Grace A. Montgomery, Lizette Nieder-Westermann, Gerald Nodura, Donald Oberlander, Phil L. Pratt, Mary G. Reen, Lorraine Seybold, Sherry A. Stover, Richard C . Swantek, Diana M. Taliaferro, Carol L. Villavert, Maryann Wentworth, H. Katherine Wuy, Linda D.

132

Photo Credits Front Cover

Back Cover Page iii Page 1 Page 5 Page 7 Page 9 Page 11 Page 13 Page 17 Page 39 Page 63

Page 87 Page 103 Page 119

Top left: Monte Carlo "snapshot" of methane hydrates in a Namontmorillonite interlayer, Sung-Ho Park, LBNL. Top right: SeaWiFS ocean color image of plant biomass in the waters of the southern ocean, Jim Bishop, LBNL. Bottom left: Hypocenter location across the San Andreas fault zone near Parkfield, Calif. Site of repeating earthquakes in red. Robert Nadeau and Thomas McEvilly, LBNL. Bottom right: Satellite view of Yucca Mountain, Nevada, courtesy YMP Photography. Sunset view of Berkeley Lab looking west, Roy Kaltschmidt, LBNL. Collecting soil gas samples at Mammoth Mountain, Long Valley Caldera in eastern California, Roy Kaltschmidt, LBNL. Aerial view of Berkeley Lab looking north, Roy Kaltschmidt, LBNL. Sampling a remediation system at LBNL for biological activity, Roy Kaltschmidt, LBNL. Coil tubing deployed during a cross-well imaging study at the Pan Canada CO2 Injection Project near Weyburn, Saskatchewan, Ernie Majer, LBNL. Field work at Mammoth Mountain, Calif., Roy Kaltschmidt, LBNL. Full-scale heaters within a heated drift at Yucca Mountain, Nevada, Roy Kaltschmidt, LBNL. Bioreactor for treating groundwater contaminated with MTBE, Roy Kaltschmidt, LBNL. ESD scientist acquiring acoustic data after CT scan on sand pack with partial gas saturation, Kurt Nihei, LBNL. Yucca Mountain, Nevada, courtesy YMP Photography. LBNL's seismic vibroseis source trucks are being deployed for a borehole seismic survey near Royal Center, Indiana. The borehole (background left, below crane) was used as part of a DOE project in improving underground storage of natural gas, Tom Daley, LBNL. Soil vapor extraction remediation at LBNL, Roy Kaltschmidt, LBNL. Test deployment of a robotic ocean carbon observer from R/V Sproul Nov. 5, 2000, Jim Bishop, LBNL. Coastal waters near San Diego, Calif., Jim Bishop, LBNL.

Design and Production: Walter Denn Maria Fink Editor: Mary Pratt

ANNUAL REPORT

EARTH SCIENCES DIVISION

1999 - 2000

Prepared for the U.S. Department of Energy under Contract Number DE-AC03-76SF00098


1999-2000 Annual Report