--> Abstract: A Potential Multiuse Environmentally Safe Energy Resource for the 21(st) Century - The Geopressured-Geothermal Reservoirs of the Gulf of Mexico Basin, by C. J. John and G. Maciasz; #90937 (1998).

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Abstract: A Potential Multiuse Environmentally Safe Energy Resource for the 21(st) Century - The Geopressured-Geothermal Reservoirs of the Gulf of Mexico Basin

JOHN, CHACKO J. and GINA MACIASZ, Basin Research Institute, Louisiana State University.

Summary

The United States Department of Energy established a geopressured-geothermal energy program in the mid 1970's as one response to America's need to develop alternate energy resources in view of the increasing dependence on imported fossil fuel energy. This program continued for sixteen years and approximately twenty million dollars were expended for various types of research and well testing to thoroughly investigate this alternate energy resource. The main goals of this program were to define the extent of the geopressured reservoirs, determine the technical feasibility of reservoir development including downhole, surface, and disposal technologies, establish the economics of production, identify and mitigate adverse environmental impacts, identify and resolve legal and institutional barriers and determine the viability of commercial exploitation of this resource (Division of Geothermal Energy, 1980).

The geopressured-geothermal reservoirs are essentially subsurface reservoirs containing hot pressurized brine saturated with dissolved methane at the temperature, pressure and salinity of the formation. They contain three forms of energy: (1) chemical energy: methane dissolved in brine under pressure, (2) thermal energy: hot brines with temperatures from over 225°F, which could be utilized for direct heating secondary hydrocarbon recovery, or generation of electricity, and (3) mechanical energy: high brine flow rates (over 20,000 barrels per day) and high well head pressures could be used for driving turbines to generate electricity. During the course of this research program involving industry contractors, private sector consultants and companies, university research groups and national laboratories, seventeen wells were tested to achieve the main goals of this research program enumerated earlier. The significant accomplishments of this program included (1) identification of the geopressured-geothermal onshore fairways in Louisiana and Texas, (2) determination that high brine flow rates of 20,000 - 40,000 barrels a day can be obtained for long periods of time, (3) brine, after gas extraction can be successfully reinjected into shallow aquifers without affecting the surface waters or the fresh water aquifers, (4) no observable subsidence or microseismic activity was induced due to the subsurface injection of brine, (5) sanding can be controlled by reducing flow rates,(6) corrosion controlled with inhibitors, (7) scaling controlled by phosphonate scale inhibitors, (8) demonstrated that production of gas from saturated brine under pressure was viable and (9) a hybrid power system can be successfully used for conversion of the thermal and chemical energy contained in the geopressured-geothermal resource for generation of electricity.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah