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Presented by the University of Kentucky’s Center for Applied Energy Research Vol. 23 No. 3/2012 Fracture Stimulation of Shale Gas Wells Is it Dangerous? Brandon Nuttall, Kentucky Geological Survey Gas produced from low-permeability organic-rich shale has revolutionized the energy outlook in the United States. The total shale gas resource is estimated to be as much as 3,000 trillion cubic feet (Tcf) by the Energy Information Administration and the United States Geological Survey. Estimates of proven reserves likely exceed 97 Tcf. Exploration and development of these resources has increased petroleum liquids production, significantly reduced oil imports, and electric utilities are now turning to natural gas for new generation. Geologists have long recognized organicrich shales as petroleum-source rocks, but the combination of horizontal wells and fracture stimulation has unlocked the resources from these rocks. However, these technologies are not without controversies associated with the chemicals used, the potential for groundwater pollution, flaming faucets, and earthquakes. Oil and gas accumulations have four main properties: a reservoir, a seal that forms a trap, a source rock, and a migration pathway to connect the source and reservoir. Reservoirs are rocks characterized by a similar depositional system, structural set- An underground source of drinking water (USDW) that is hundreds of feet below ground and a fracture stimulated horizontal well that is thousands of feet underground (not to scale). The illustration shows the well to be cemented from surface to the top of the gas shale. There are several rock units and sealing zones between the gas shale and the water source. ting, porosity, permeability, pressure, and fluids. Seals are low porosity, low-permeability rocks that confine fluids in the reservoir. A source rock contains sufficient organic matter to generate hydrocarbons. In a reservoir, porosity is a measure of the total volume of void space in a rock and defines the available volume for fluid storage. Po- rosity can occur within and between grains and in fractures. Permeability is a measure of the resistance to fluid flow within the rock and varies with the viscosity of the fluid. In gas shales, micrometer-scale and smaller pores, nanodarcy-scale permeability, and organic content contribute to make the shale a reservoir, trap, and source. continued on page 3 Revealing New Energy in a New CAER Building Energy research became more energy efficient as the University of Kentucky opened its newest energy research building this summer - a living laboratory devoted to renewable energy and energy storage. The $20.8 million laboratory building allows CAER to expand research devoted to Kentucky’s growing renewable energy industries, including biomass and biofuels, electrochemical power sources (like capacitors and batteries), and distributed solar-energy technologies. What does the public think about energy, or does it? see page 2 At a press conference in August, Kentucky’s Governor Steve Beshear said, “It makes good sense for all buildings-not just those devoted to energy research-to be as energy-efficient as possible. Smart energy usage in buildings saves money and resources. Most importantly, the people inside this building are performing critical work in advanced energy research. Their efforts will undoubtedly impact Kentucky’s future in energy innovation.” continued on page 5 1

Energeia 23.3

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