| Title | A Study on the Possibility of Mineral Formation in CO₂ Geothermal Power Generation Using THC Simulation |
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| Authors | Kentaro Masuoka, Claudia Fujita, Hajime Yamamoto, Amane Terai |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | |
| Abstract | CO2-EGS has been proposed as a novel concept of geothermal power generation. The system utilizes CO2 instead of water as the heat transfer fluid. Its potential advantages include greater heat extraction efficiency compared to water and the storage of unrecovered CO2 in underground geological formations. Although many researchers have investigated this concept, its implementation has not yet to be realized. In Japan, when CO2-EGS is implemented, it is often expected that CO2 will be injected into geothermal reservoirs composed of volcanic rocks containing water (i.e., hydrothermal reservoirs) due to high precipitation conditions. CO2-plume geothermal (CPG) has been investigated by Randolph and Saar (2011), focusing on sedimentary layers saturated with water at lower temperature ranges (~120 °C). Generally, it is considered that the mineral reactions will vary significantly with reservoir temperature and pressure, potentially could cause formation of mineral shells due to the geochemical reactions. However, studies of the possibility of formation of mineral shells in CO2 geothermal power generation have not yet been conducted enough. In this study, THC numerical simulations were performed to investigate formation of mineral shells and heat extraction efficiency, in the case where CO2 is injected as a heat transfer fluid into a geothermal reservoir composed of volcanic rocks saturated with water. As a result, we revealed that the possibility of forming a mineral shell due to chemical reactions that contributes to the prevention of CO2 leakage and the improvement of recovery rate of injected CO2. |