Well Placement Optimization for Maximum Energy Recovery from Hot Saline Aquifers

Abstract

Hot saline aquifers are a large potential geothermal resource for the US Gulf coast. These geopressured reservoirs could produce geothermal energy because of their high pressures and permeabilities, in spite of their moderate temperatures of circa 140°C. Although these resources have been researched extensively, previous investigations have reached mixed conclusions regarding the technical and economic feasibility of these reservoirs. Gulf Coast geothermal reservoir development is further complicated by the requirement to dispose of the high-salinity produced brine with minimal environmental and geomechanical risk. Injection of cooled brine reduces reservoir temperature and may affect the well productivity and economic performance. Decisions on the location of the injection and production wells are important for estimating energy recovery. This article provides estimates of energy generation using reasonable approximations for the study site, the Camerina A zone of the Gueydan field, Vermilion Parish, Louisiana. Well locations in the field are optimized with net enthalpy recovery for a 30 year project life as the objective function. A subset of existing wells originally drilled for oil exploration purposes are used for modeling geothermal exploitation. The results confirm that injection into cooler areas of the reservoir and producing from hotter regions is the best heat harvesting strategy. The results include simple performance models available for binary power plants. Louisiana geothermal resources, previously viewed as marginal, appear to be feasible targets for geothermal energy production.