In-situ stress magnitudes determined by retrieved cores in China's first enhanced geothermal system in Gonghe Basin, Tibetan Plateau

In-situ stress knowledge involves the entire process of enhanced geothermal system (EGS) development, such as borehole stability, hydraulic fracturing propagation patterns, and mitigation of induced seismic risk. To eliminate the influence of high temperature, we employ the Anelastic Strain Recovery (ASR) technique for in-situ stress measurements in geothermal boreholes. ASR is a rock-core-based three-dimensional stress measurement method. Using the ASR method, we successfully measured the magnitude of in-situ stress at depths of 1500-4000m in China's first large-scale EGS site. To evaluate induced seismicity and fracture stimulation during EGS development, we simulated the variations in fracture slip tendency (T-s) near the injection well using the in-situ stress data. The results show that T-s, is initially small, but as injection pressure increases to 46 MPa, the fractures reach a critical state (T-smax = 0.6), and further pressurization leads to gradual slipping of the fractures (T-s > 0.6).