The effect of fluid pressure on frictional stability transition from velocity strengthening to velocity weakening and critical slip distance evolution in shale reservoirs

Seismic activities have been reported by the large-scale fluid injection in shale reservoirs both during hydraulic fracturing operations and wastewater disposal processes. Fluid overpressure has been regarded as the primary cause for the injection-induced seismicity since the fluid lubricates the fault and decreases the effective normal stress applied to the pre-existing faults. However, how fractures/faults slip after the activation remains...