Analysis of Sweet Lake Geopressured-Geothermal Aquifer

Abstract

Geopressured-geothermal aquifers are presumed to contain a large resource of natural gas in solution with the native brine. Whether this resource can be produced economically at the present time depends upon the ability of these reservoirs to produce at high rates for extended periods of time. The Sweet Lake geopressured-geothermal aquifer, located southeast of Lake Charles, Louisiana, is one such aquifer modeled by a two-dimendonal geopressured- geothermal simulator. This aquifer a sandstone within the Frio formation at depths between 15,000 to 15,640 ft with a net porous thickness of 250 ft, a calculated in-situ permeability (from drawdown data) of 17 md, an estimated porosity of 24 pez7cenJ5 a uniaxial compaction coefficient of 4.5 x 10 psi and a solution gas-water ratio of 11 SCFISTB all at the initial reservoir pressure of 12,060 psi These parameters are typically pressure sensitive in geopressured- geothermal aquifers and are critically important to aquifer performance. Several simulation experiments are conducted which investigate the effects of varying initial values for these parameters with the experimentally determined values as means. The mmulations give both optimistic and pessimistic expectations for aquifer performance. The expected life of the geopressured-geothermal well is reported for each simulation.