A robust assessment method of recoverable geothermal energy considering optimal development parameters

Abstract

It is known that development parameters such as injection and production rate, injection temperature, and well location and spacing play an important role in determining the recoverable geothermal energy in a licensed region during the exploitation stage, but they are seldomly considered in geothermal resource assessment. In this study, a robust assessment method of recoverable geothermal energy considering the optimal development parameters is developed. To maximize the recoverable geothermal energy whilst avoid environmental disasters including reservoir pressure declining, thermal breakthrough and surface subsidence, an efficient approach of optimizing development parameters is proposed using the fully coupled thermo-hydro-mechanical reservoir model, experimental design and proxy model, and multiple response optimization method. Based on the case study of two doublets in the Tongzhou district, China, the robustness and reasonability of the developed assessment method are demonstrated. The results show that the optimal development parameters can significantly increase the recoverable geothermal energy, but the optimal development parameters for different doublets are different due to the complexity in geological structures and the heterogeneity in reservoir parameters. Therefore, it is highly recommended to maximize the recoverable geothermal energy by selecting the optimal development parameters.