某注水井油管穿孔原因

Cause of corrosion and perforation of tubing in a water injection well

在某注水井油管起出井下管柱作业过程中发现其存在穿孔。采用宏观观察、化学成分分析、硬度测试、金相检验、力学性能测试、附着物分析、结垢预测及细菌检测、能谱分析、腐蚀模拟试验等方法,分析了油管穿孔的原因。结果表明:油管受到井下工况环境与注入水介质成分的影响,在其内壁形成并附着了CaCO_(3),BaSO_(4)等垢层,形成了垢下腐蚀环境;在Cl^(-)、还原菌的双重作用下,局部敏感区域的垢下腐蚀不断加剧,最终导致该油管发生了腐蚀穿孔。

The perforations were found in tubing of a water injection well during tripping out the downhole string.The causes of tubing perforation were analyzed by macroscopic observation,chemical composition analysis,hardness test,metallographic examination,mechanical properties test,attachment analysis,scaling prediction and bacteria detection,energy spectrum analysis and corrosion simulation experiment.The results show that the tubing was affected by the downhole working environment and the composition of the injected water medium,and scale layers such as CaCO_(3) and BaSO_(4) were formed and attached to its inner wall,forming an under-deposit corrosion environment.Under the dual action of Cl^(-)and sulfate-reducing bacteria,the under-deposit corrosion in local sensitive areas was continuously intensified,which led to in corrosion perforation of the tubing.