Numerical Study of The Influence of Fault Slip On Adjacent Fault Stability

Exploring the mechanisms of injection-induced seismicity has great significance for predicting and controlling the occurrence of large induced earthquake. The influence of fault slip on adjacent fault stability was systematically explored by numerical simulation of cold fluid injection into reservoir with two faults (fault1 and fault2) which were established according to the Pohang EGS project. Numerical results showed that water injection into fault2 successively caused fault2 and fault1 to slip. The sliding of fault2 affected the stability of adjacent fault1, and the closer the position of fault1 to the injection well of fault2, the greater the impact of fault2’ sliding on its stress state. In addition, the thermal stress effect on faults stability was examined by comparing isothermal case with non-isothermal case. The thermal stress made a faster decrease of effective normal stress and a slowly increase of shear stress, indicating that the thermal stress will weaken the stability of fault. These results emphasize the necessity of investigating fault information, hydromechanical properties, thermodynamic properties, and local stress state to accurately describe the geomechanical response of faults during the cold fluid injection process for the safe and efficient exploitation of geothermal resources.