长庆油田某采油厂集输管道内腐蚀原因及腐蚀机理

采用光学显微镜、扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)等对长庆油田6个典型区块管道腐蚀失效的原因进行了分析,并对腐蚀机理进行了探讨。结果表明:6个典型区失效管道的组织为铁素体和少量的珠光体,元素分布均匀,化学成分符合20#钢的标准规定。1号、3号、4号、5号、6号典型区块腐蚀穿孔管节腐蚀产物的主要成分为铁的氧化物(Fe2O3、Fe3O4)。2号典型区块腐蚀穿孔管节腐蚀产物的主要成分为铁的氧化物(Fe2O3、Fe3O4)和铁的硫化物(FeS)。1号、4号、5号、6号典型区块管道主要发生了二氧化碳腐蚀。2号典型区块管道发生了二氧化碳和硫化氢腐蚀。3号典型区块管道发生了二氧化碳和氧腐蚀。

Causes of Internal Corrosion and Corrosion Mechanism for Gathering and Transportation Pipes in An Oil Production Plant of Changqing Oilfield

Optical microscopy,scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS)and Xray diffraction(XRD)were used to analyze the causes of corrosion failure of pipes in six typical blocks in Changqing Oilfield,and the corrosion mechanism was also investigated.The results show that the microstructure of failed pipes in 6 typical blocks was ferrite and a little pearlite,and the element distribution was uniform.The chemical composition of the failed pipes was in accord with the standard requirements of 20#steel.The main components of corrosion products on the perforated corrosion pipe sections in typical blocks No.1,No.3,No.4,No.5 and No.6 were iron oxides(Fe2O3,Fe3O4).The main components of corrosion products on the perforated corrosion pipe sections in typical blocks No.2 were iron oxides(Fe2O3,Fe3O4)and iron sulfide(FeS).Carbon dioxide corrosion occurred on pipes in typical blocks No.1,No.4,No.5 and No.6.Carbon dioxide and hydrogen sulfide corrosion occurred on pipes in typical block No.2.Carbon dioxide and oxygen corrosion occurred on pipes in typical block No.3.