Effects of extraction well assisted by the fault on thermal recovery performance in hydrothermal system

In hydrothermal system, the fault acting as the fluid pathway to assist extraction wells for extracting hydrothermal resources is being concerned. In this study, a coupled thermal-hydraulic-mechanical model of a fault-controlled hydrothermal system was established. The spatiotemporal evolution of the temperature-seepage field in thermal recovery system was revealed, and effects of fault physical characteristics, extraction parameters and well distance on thermal recovery performance were analyzed. The results show that, with the prolongation of extraction time (0–20 years), the thermal recovery performance of the fracture-controlled hydrothermal system is significantly better than conventional hydrothermal system. With the permeability of fault rocks transforms from isotropic to anisotropic, the production power of hydrothermal system increases. In the unbalanced extraction scheme, the production power decreases with the reduction of the extraction flow rate of the middle well. Three extraction schemes were studied, and the hydrothermal system has a better thermal recovery performance when the scheme with a smaller imbalance coefficient. In addition, it is found that with the shortening of the distance between the extraction well and the recharge well, the production power decreases significantly.