Energy Resources of Water-Bearing Geopressured Reservoirs-Tertiary Formations, Northwestern Gulf of Mexico (Summary)

Estimates for the total gas resource in place in geopressured Tertiary sandstone reservoirs along the United States Gulf Coast range from 3,000 to 100,000 tcf 185 to 2,832 trillion cu m). This wide range in estimates was the incentive for initiative research effort in Texas and Louisiane to obtain more reliable data on all aspects of developing the available heat and hydraulic energy present in these aquifers in addition to the methane. All resource calculations are based on interpretations of total sandstone thickness, lateral extent of reservoirs, porosity and permeability, reservoir drive, salinity, temperature, pressure, and methane solubility. Diverse estimates arise from inadequate knowledge concerning these critical parameters. Regional and detailed local geologic studies have been conducted ta delineate prospective areas for testing the geopressured resource. A prospective area should have reservoir volume of 3 Cu mi (12 cu km), minimum permeability of 20 mD, and fluid temperatures of 300°F (150°C). A geothermal designed test well has been drilled in Brazoria County, Texas, in order to test the potential of producing up to 40,000 barrels of water per day from a geopressured reservoir. The reservoir consists of 250 to 300 ft (75 to 90 m) of sandstone with core permeabilities between 40 and 60 mD and fluid temperatures from 300 to 350°F (159 to 177°C). The test period will continue for a 2-year period and, with other designed tests in Texas and Louisiana will provide invaluable data concerning high-volume production over long periods of time