某油井P110油管腐蚀穿孔原因

Cause of Corrosion and Perforation of P110 Tubing in an Oil Well

西部油田某油井油管发生严重腐蚀甚至穿孔。通过宏观形貌和显微组织观察、化学成分分析、硬度测试、拉伸和冲击性能测试、腐蚀产物检测等方法对油管失效原因进行了分析。结果表明:油管在含Cl^-、H2S、CO2酸性环境下发生了均匀腐蚀和局部腐蚀。均匀腐蚀由H2S-CO2-H2O(Cl^-)体系引起的析氢腐蚀所致;而CaCO3沉积造成的微电偶效应以及Fe^2+与地层水中Cl^-的水合作用导致了油管的局部腐蚀穿孔。建议油井管材采用具有一定抗硫性的P110-3Cr钢或耐蚀性能更优的钢,并添加缓蚀阻垢剂进行防护。

The tubing of an oil well in western oilfield was corroded severely and even perforated.The cause of the tubing failure was analyzed by macroscopic morphology and microstructure observation,chemical composition analysis,hardness test,tensile and impact performance test,corrosion product detection.The results show that uniform corrosion and localized corrosion of the tubing occurred in the acidic environment containing Cl^-,H2S and CO2.The uniform corrosion occurred as a result of hydrogen evolution corrosion caused by the H2S-CO2-H2O(Cl^-)system.The micro galvanic effect caused by the deposition of CaCO3 and the hydration of Fe^2+and Cl^-in the formation water led to the localized corrosion and perforation of the tubing.It was suggested that P110-3 Cr steel with certain sulfur resistance or steel with better corrosion resistance should be used for the oil well tubing materials,and corrosion and scale inhibitors should be added for protection.