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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