Poroelastic stress relaxation, slip stress transfer and friction weakening controlled post-injection seismicity at the Basel Enhanced Geothermal System

Abstract Induced seismicity is a limiting factor for the development of Enhanced Geothermal Systems (EGS). Its causal mechanisms are not fully understood, especially those post-injection seismicity. To better understand that induced in controversial case Basel EGS (Switzerland), we perform coupled hydro-mechanical simulation plastic response discrete pre-existing fault network built on basis monitored Simulation results show faults located vicinity injection well fail during mainly triggered by pore pressure buildup. Poroelastic stressing, which may be stabilizing or destabilizing depending orientation, reaches further than diffusion, having greater effect distant faults. After stops, poroelastic stress relaxation leads to immediate rupture previously stabilized Shear-slip transfer, also contributes reactivation faults, enhanced with slip-induced friction weakening.