油井管的腐蚀疲劳研究进展

Progress in Research on Corrosion Fatigue of Oil-well Tubing

油井管在服役工况下常常受到腐蚀介质和交变载荷(弯曲、振动)的共同作用,会发生严重的腐蚀疲劳破环。分析了环境、力学状态和材料特性等因素对腐蚀疲劳的影响,介绍了油井管腐蚀疲劳的国内外研究现状、裂纹萌生机理和裂纹扩展机理。裂纹萌生机理包括点蚀坑处应力集中、构件几何不连续、驻留滑移带和表面膜破裂等,裂纹扩展机理包括阳极溶解、活性因子、表面能减小、产物转移和产物膜因素等。指出油井管腐蚀疲劳研究的重点和难点是腐蚀环境下的腐蚀疲劳机理,应深入研究服役工况下各种影响因素之间的耦合作用对油井管腐蚀疲劳的影响。以现场测试数据为基础,结合试验和数值模拟方法进行腐蚀疲劳研究,可为油井管的断裂理论奠定基础,也可为油气井安全生产提供保障。

Oil-well tubing in service is frequently subject to combined effects of corrosive media and alterna- ting loads （bending, vibration） and may experience severe corrosion fatigue. In this paper, impacts of environ- ment, dynamic properties and materials to corrosion fatigue have been analyzed. In addition, researches related to corrosion fatigue of oil-well tubing in China and overseas have been reviewed. Moreover, crack germination mecha- nisms and crack expansion mechanisms have been highlighted. Crack germination mechanisms include concentration of stresses around the corrosion pit, geometric discontinuity of relevant elements, persistent slip bands and busting of surface films; crack expansion mechanisms include anodic dissolution, active factors, reduction of surface en- ergy, product transmission and product films. It has been highlighted that researches related to corrosion fatigue of oil-well tubing shall focus on mechanisms of corrosion fatigue in corrosive environments. More researches are re- quired for impacts related to coupling of various factors under working conditions to corrosion fatigue of oil-well tub- ing. Combination of on-site test results, lab test data and numerical simulation in researches related to corrosion fa- tigue may provide solid foundation for failure mechanism of the oil-well tubing and may ensure safe production of oil and gas wells.