渤海某油田F井旁路管腐蚀失效研究

Corrosion Failure of Bypass Pipe of Well F in Bohai Oilfield

目的旁路管腐蚀现象在渤海油田时有发生,以渤海某油田F井为例,研究该油田旁路管腐蚀机理,指导该油田旁路管选材,确定该油田的防腐方向与措施。方法基于对管材腐蚀的初步分析,通过扫描电子显微镜、拉伸强度试验机、X射线衍射仪等仪器,对F井已发生腐蚀的旁路管进行理化性能分析、金相显微分析、腐蚀产物XRD分析以及腐蚀产物能谱分析。结果化学成分方面,1#、2#、3#旁路管的原化学成分均满足API Spec 5CT的要求;力学性能方面,1#旁路管抗拉强度和屈服强度略低于标准要求,2#、3#旁路管的力学性能均满足API Spec 5CT的要求;腐蚀产物方面,1#、2#、3#旁路管腐蚀产物主要由Fe、C、O、S、Ca、Mn组成,以铁的氧化物为主,硫化物次之,其中C、O、Ca元素应来源于环境介质,少量的Ti元素可能来源于周围的接触金属。对于腐蚀所生成化合物,1#旁路管主要为铁氧化物,其中所含的Ca2Fe2O5来源于地层中的沙土或矿石;2#旁路管外壁腐蚀产物为典型铁锈成分,以铁的氧化物为主,存在少量Fe O(OH),该物质不稳定,在空气中暴露后易形成铁的氧化物。结论 F井旁路管腐蚀属于冲刷腐蚀和电偶腐蚀。

Objective The phenomenon of bypass pipe corrosion failure occurs in Bohai Oilfield. Taking Well F in Bohai Oilfield as an example, this paper investigated the corrosion mechanism of bypass pipe to guide the selection of bypass pipe materi- al, and to determine the antieorrosive direction and measures of this oil field. Methods Based on the preliminary analysis of pipe corrosion, using scanning electron microscope, tensile strength test machine, X ray diffraction instrument and so on, physical and chemical performance analysis, metallographic analysis, corrosion product XRD analysis and corrosion product spectrum analysis were carried out on corroded bypass pipe of well F. Results In the aspect of chemical composition, the original chemical compo- sition of the 1#, 2#, 3# bypass pipes met the requirements of Spec 5CT API. In the aspect of mechanical properties, the tensile strength and yield strength of 1# bypass pipe were slightly lower than the standard requirements, and the mechanical properties of the 2#, 3Obypass pipes met the requirements of Spec 5CT API. In the aspect of corrosion products, the corrosion products of the 1#, 2#, 3# bypass pipes were mainly composed of C, O, S, Fe, Ca and Mn. Iron oxide was the main product, followed by sulfide, inwhich C, Ca, O elements should be derived from environmental media, and a small amount of Ti element might be derived from the surrounding contact metal. In the aspect of compounds produced by corrosion, Iu bypass pipe mainly produced iron oxide, and it contained Ca2Fe205 which was inferred to be derived from the formation of sand or ore. 2#bypass pipe mainly produced typical rust components, mainly iron oxide, and a small amount of FeO（OH）, which was unstable, and could easily produce iron oxide in the air Conclusion The corrosion of well F was erosion-corrosion and galvanic corrosion.