西部油田某井油管腐蚀失效分析

摘要

采用化学成分分析、金相显微镜、扫描电子显微镜、X射线能谱分析仪和电化学方法等手段对西部某油田油管腐蚀失效件进行了检测分析.结果表明,井下油管管体外壁发生严重点蚀主要因素是酸化过程残酸反排阶段的残酸液和地层水中的高浓度氯离子,同时CO2和H2S也促进了腐蚀发生.油管管体相对于结箍发生了更严重的点蚀,主要是因为油管管体和结箍在材质、金相组织以及耐蚀性上均存在差异.%Chemical composition analysis,metallurgical microscopy,scanning electron microscopy,energy dispersive analysis of X-ray and electrochemical method were used to investigate the corrosion failure of oil tubing.Combined the field parameters,operation history and lab analysis results,it is concluded that the severe pitting corrosion occurred on the external surface of tnbing was mainly due to the failure of tube packer caused the entrance of acid (including fresh acid and residual acid) into the annulus between tubing and casing.The reason for the corrosion degree difference between tube body and coupling is the difference in the chemical composition,metallurgical structure,and electrochemical corrosion property between the tube boby and the coupling.