An Evaluation of the Available Energy Potential of the Gulf Coast Geopressured Zones

The geopressured zones presently under serious study in the U.S. are tertiary sediments in the Gulf Coastal basin which are water saturated and exhibit pressures significantly greater than hydrostatic. These sediments are primarily shale, interbedded with sandstone. The top of the geopressured zone is frequently near 10,000 ft. or so, and extends to indeterminate depths. The water contained in these zones is at a moderately elevated temperature and, more significantly, appears to contain dissolved methane at near-saturation values. Conceptually, wells drilled into the geopressured zone might be expected to produce water without pumping, due to the high pressures. The dissolved methane could then be separated at the surface and used conventionally as natural gas. The water may contain sufficient heat to provide a useful source of geothermal energy, and the hydraulic energy might also provide useful work. Development of the geopressured/geothermal resource is largely dependent upon production characteristics of geopressured reservoirs. These in turn are intimately related to properties of the formations, and can be defined within reasonable limits.