高含H2S介质气井中, 射孔段套管始终工作在腐蚀性环境中, 必然会引起射孔套管发生严重腐蚀甚至突然断裂。结合材料学和电化学腐蚀知识, 分析了含H2S腐蚀环境中射孔段套管的应力腐蚀开裂失效机理; 并在此基础上, 将射孔段套管看作带“尖角圆孔”型裂纹的无限大圆柱筒壳体, 运用弹塑性断裂力学理论, 得到了带环向和轴向尖角圆孔型裂纹的射孔段套管在H2S腐蚀环境中的应力腐蚀临界应力强度因子, 据此推导出了射孔段套管硫化氢应力腐蚀断裂临界应力和容许的最大尖角裂纹长度。根据弹塑性力学理论, 推导出了射孔段套管在H2S腐蚀环境中工作时的环向和轴向拉应力, 提出了判断射孔段套管硫化氢应力腐蚀程度和敏感性两项性能指标。为高深度H2S天然气井中射孔段套管的应力腐蚀、强度安全性、腐蚀疲劳分析和寿命估算提供理论参考和技术依据。

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.