Stress Corrosion of Perforating Casing in Solution of High H2S Gas Well

In the gas production stage after perforating, perforating casing may suffer sudden rupture due to the serious corrosion during its service in the gas well containing high H2S level. Combined with materials and electrochemical corrosion knowledge, the stress corrosion cracking failure mechanism of perforating casing in H2S corrosive environment was analyzed. Based on this, perforating casing was looked on as an infinite cylinder shell with the cusp hole crack, the critical stress intensity factor of perforating casing with the circumferential or axial cusp hole crack in H2S corrosive environment was obtained, further, the hydrogen sulfide stress corrosion fracture critical stress of perforating casing and the maximum allowable cusp crack length were derived. According to the elastic-plastic mechanics theory, circumferential and axial tensile stress of perforating casing in H2S corrosive environment was derived, the two performance indicators of judging hydrogen sulfide stress corrosion and sensitivity of perforating casing were proposed. Theoretical reference and technical basis were provided for stress corrosion, strength safety, corrosion fatigue analysis and life estimation of perforating casing in the gas well containing high H2S level.