某N80S油管腐蚀穿孔的失效分析

Failure Analysis of Corrosion Perforation of N80S Tubing

通过宏观观察、理化性能检测、组织分析、扫描电镜观察和能谱分析等方法,并结合现场服役工况,系统分析了某N80S油管发生腐蚀穿孔的原因。结果表明:酸化作业残酸返排过程中介质的低pH和高Cl^-含量是导致油管腐蚀穿孔的主要原因,腐蚀井段局部水平或倾斜造成管段积液使得局部点蚀加剧,最终在积液位置发生腐蚀及穿孔。最后,给出了避免或减缓此类问题再次发生的几点建议。

On the basis of the survey of service environment,the reasons for N80S tubing perforation failure were elaborated via macroscopic observation,physical and chemical property testing,microstructure observation,scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS).The results show that low pH value and high Cl^- concentration in acidizing fluid and residual acid solution dominantly induced the perforation failure of the tubing.Meanwhile,the effusion in tubing caused by the partial level and inclination of the tubing string deteriorated the pitting.Finnally the tubing corroded and perforated in the position of effusion.Some suggestions were proposed for avoiding this kind of problem again.