Optimal HDR exploitation siting of gravity heat pipe geothermal systems via reservoir simulation

Abstract

Gravity heat pipe system has previously been proven as an environmental and efficient technology in exploiting hot dry rock. However, it is unclear what geothermal reservoir siting is more favorable for the system’s heat extraction performance. Herein, we analyzed the influences of geothermal field siting (rock property and reservoir environment) on heat extraction performance of gravity heat pipe systems through a 3D thermal–hydraulic coupled model. It is found that rock properties have huge influences on heat compensation, heat extraction ratio and heat compensation ratio. Low rock density, low rock specific heat capacity and high thermal conductivity could increase heat compensation, heat extraction ratio and heat compensation ratio. It is also found that geothermal reservoir environment affects the heat extraction rate seriously. High initial temperatures and low temperature gradients increase heat extraction rates. Geothermal reservoir pressure affects the heat extraction performance slightly, and low initial pressures increase heat extraction rate. The study results would provide suggestions on deep geothermal exploitation locations.