Numerical simulation on physical composite stimulation and geothermal development performance of hot dry rock: A Case study from Matouying Uplift, China

To improve the production capacity of fractured reservoirs in the Matouying Uplift Area, the physical composite stimulation is proposed, and its effect is analyzed and verified based on numerical simulation methods of finite- discrete element and thermo-hydro-mechanical coupling theories. Results show that the artificial cracks generated by the on-site fracturing connect natural fractures to some extent, the large fractures generated by the secondary fracturing can promote the connection between injection and production wells, the micro-cracks generated by the blasting based on on-site fracturing increase both the crack density and crack coverage area, and adopting the physical composite stimulation can generate a dense network of main and branch cracks. After the mining of 40 a, the thermal mining rate of the original reservoir is 15.24 %, while those of reservoirs with the on-site fracturing, the secondary fracturing, the blasting based on on-site fracturing and the physical composite stimulation are 23.02 %, 27.69 %- 29.86 %, 26.80 %- 48.47 % and 79.85 %, respectively. The optimal displacement of hydraulic fracturing and peak pressure of liquid explosives is 5.07 m3/min and 800 MPa. Although the physical composite stimulation is very beneficial for the mining of hot dry rock, technical breakthroughs are still needed in areas such as the perfusion method, detonation way, and high-temperature stability of liquid explosives. This study can support the theoretical and technological development of hot dry rock reservoir stimulation.