Geopressure/Geothermal Prospects

The Department of Energy is actively exploring the use of geopressured, geothermal resources as an alternative source of natural gas and energy for power generation. Bands of this resource are located along the Texas-Louisiana gulf coast. A resource assessment of these ''fairways'' has been made and reveals that only some of them show potential promise. The major unknowns are the number, size and properties of the reservoirs, and how they are faulted (i.e. how much continuous medium there is between faults). This GP/GT resource is located at depths in excess of 12,000 ft under extremely high pressure. The water may contain as much as 50 standard cubic feet of dissolved gas per barrel of fluid and have a temperature of 300-350 F. The proposed method to use this resource is to reduce the pressure through a turbine-generating power, strip off the gas as it comes out of solution, and flash the hot water into steam for further power generation. These three sources of energy--pressure, gas and heat--are about equal in energy content. If the water were pure, we could then use it for irrigation. Unfortunately, it is saltier than sea water. Disposal becomes a problem. There are two possible methods of disposal--injection into a shallow reservoir and injection into the same reservoir. The first requires less energy, the second helps maintain reservoir pressure and increases overall total product