Fracture Deformation and Thermal Performance of Sc‐CO ₂ , Water, and Brine Water in Dual‐Porosity Dual‐Permeability Geothermal System

The physical and thermal behaviours of supercritical CO 2 (Sc‐CO 2 ), brine water, acidic water, and freshwater as geothermal fluids were numerically investigated to provide better insights into their performance in enhanced geothermal systems (EGSs). First, we analyzed the hydrogeochemical (diffusive) characteristics of the fluids resulting from density changes within the reservoirs. We then performed a coupled thermo‐hydro‐mechanical (THM) analysis to investigate the fracture deformation and heat production performance. The study shows that the induced fracture deformation at the injection and production wells by Sc‐CO 2 is less than that of the other geofluids; however, it has the highest thermal performance. This makes Sc‐CO 2 a less viable fluid for hydraulic stimulation in EGS production. The magnitude of the fluid‐induced deformation in the injection zone was significantly higher than that in the production zone. The rock matrix saturation time by acidic water is the least; the increased residence time within the rock matrix could increase the thermal performance relative to fluids of similar thermophysical properties.