A Reduced Form Representation of Temperature Drawdown in Sedimentary Basin Geothermal Reservoirs for the Development of Optimal Management Strategies

Abstract

A geothermal resource is often considered to be sustainable if the temperature within the reservoir is maintained at a level that can provide cost-effective heat. But, the heat that is extracted from the geothermal resource is used to provide a service to society and an economic gain to the provider of that service. In this context, sustainability entails simultaneously considering the rate at which the reservoir temperature renews and the rate at which heat is extracted and converted into economic profit. We developed a reduced form representation of temperature drawdown in sedimentary basin geothermal reservoirs for future development of optimal heat extraction strategies that incorporate physical and economic tradeoffs. We used the Non-isothermal Unsaturated-saturated Flow and Transport (NUFT) model to simulate the performance of a sedimentary geothermal reservoir under a variety of geologic conditions and operational scenarios and developed a reduced form representation of the drawdown and regeneration of reservoir. This representation can be integrated into a natural resource economics model to determine the mass flowrate that maximizes the net present profit given the performance of the geothermal resource.