Geothermal resources for global new energy development because of its wide distribution, huge reserves and environment-friendly. The enhanced geothermal system (EGS) is one of the key technologies for the extraction and utilization of geothermal energy in high-temperature rock masses in deep formations. The use of supercritical carbon dioxide (S-CO2) as a working medium in EGS has many advantages for heat exploitation. But the change of thermal properties of supercritical carbon dioxide is very rapidly during EGS production, which affects the transport of fluids and rock-fluid heat exchange. To investigate the effect of S-CO2 in EGS, in the present work, we develop the heat and mass transfer models for S-CO2 in EGS based on the Embedded Discrete Fracture Model (EDFM). The simulation results show that the complex fracture network has significant effects on the heat and mass transfer of supercritical carbon dioxide in the reservoir. In addition, S-CO2 not only has higher heating efficiency than water, but also captures and stores carbon dioxide.
Keywords Enhanced Geothermal System, Supercritical carbon dioxide , Embedded Discrete Fracture Model, Heat and mass transfer.