The Investigation of Fault Slip Mechanisms During Hydraulic Fracturing in Horizontal Shale Gas Wells

Fault slip is the primary cause of casing deformation during the hydraulic fracturing process of shale gas horizontal wells. This paper investigates the mechanism of fault slip and its correlation with the integrity of the cement sheath. By establishing a numerical model of the casing-cement sheath-reservoir rock system, the effects of fracturing fluid pressure and temperature, mechanical parameters of the cement sheath, and the wall thickness of the casing and cement sheath on the integrity of the cement sheath were calculated. The results indicate that low-temperature fracturing fluids lead to changes in the stress state at the casing-cement sheath interface and the reservoir rock-cement sheath interface, with failure at the casing-cement sheath interface occurring approximately 600s after exposure. Increasing the temperature of the fracturing fluid, selecting a cement sheath with a lower elastic modulus and higher Poisson's ratio, and increasing the casing wall thickness can effectively enhance the integrity of the casing-cement sheath-reservoir rock system and prevent fault slip induced by fracturing fluids.