Numerical simulation of residual strength of CNG underground gas storage well considering cracks

Since the gases such as hydrogen sulfide contained in natural gas are corrosive, cracks are likely to occur on the inner surface of the well pipe under the double effects of corrosion and stress during the construction and service of gas storage wells, and eventually lead to fracture failure of the well pipe. The numerical model of gas storage well pipe–cement sheath–stratum was established. The residual strength of gas storage wells with cracks was analyzed by the traditional methods based on the working stress and the stress intensity factor of fracture mechanics, and the allowable crack sizes under different conditions were obtained. The results show that, the location of dangerous points can be more accurately determined, and the hidden hazards that may cause safety accidents of CNG gas storage wells can be effectively eliminated by the analysis method, which is based on the fracture mechanics stress intensity factor.