Abstract

Abstract

Abstract: Fluid pressurization rate is an important inducement to fracture slip. In order to characterize the fracture slip initiation during fluid pressurization, a series of stepwise injection induced shear tests were carried out. Results show that fracture slip initiation depends on fluid pressure under the stress conditions discussed in this paper. Fluid pressurization rate, fluid pressure non-uniform distribution, and fracture surface evolution all affect fracture slip hysteresis response to fluid pressure. Reducing fluid pressurization rate seems cannot effectively avoid induced earthquake, but can delay the time and scale of induced earthquake, especially can alleviate induced earthquake after shut-in. Earthquake induced after shut-in may be caused by secondary damage of concave-convex body on fault surface under the action of fluctuating pressure generated from injection wells or underground water sources around fault.