海上某油田油管短节腐蚀穿孔失效分析

Failure Analysis of Corrosion and Perforation of Tubing Pup Joint in Offshore Oil Field

海上某油田油管短节发生严重腐蚀穿孔,导致油管失效,严重影响油田开采工作。本文通过宏观腐蚀形貌分析、化学成分分析、力学性能测试、腐蚀产物微观形貌观察和成分分析等方法对失效油管短节腐蚀原因和发生机理进行分析。结果表明,失效油管材料为N80,油管短节主要发生内腐蚀且腐蚀穿孔集中在油管一侧。失效油管内的腐蚀产物疏松多孔,表面存在裂纹,腐蚀产物膜对基体无保护作用。X射线衍射测试结果发现,腐蚀产物是FeCO_(3)、FeS和CaCO_(3)的混合物,主要成分是FeCO_(3),N80材质的油管短节在腐蚀介质中主要发生CO_(2)腐蚀。

For the serious corrosion and perforation failure of tubing short sections in an offshore oil field,the failure analysis of tubing short sections is carried out by macroscopic morphology analysis,chemical composition analysis,mechanical performance testing,scanning electron microscope,energy spectrum analysis and X-ray diffraction.The macroscopic analysis results show that the tubing pup joint corrosion is internal corrosion,the corrosion develops from the inside to the outside,and the perforation position is mainly concentrated on one side of the tubing.The results of chemical composition and mechanical performance test proves that the tubing pup joint material is N80 rather than L80-3 Cr used in the field data.The results of scanning electron microscope reveal that the corrosion products formed at the failure of the tubing are loose and porous,and some cracks can be observed on the surface.As a result,the corrosion product film can’t prevent the substrate from corrosion.X-ray diffraction results show that the corrosion products are a mixture of FeCO_(3),FeS and CaCO_(3),but the main component is FeCO_(3),and N80 tubing pup joint is mainly corroded by CO_(2) in corrosive media.