低Cr钢在H_2S/CO_2环境中的腐蚀行为研究

Corrosion Behavior of Low Cr Steel at the Simulated H_2S/CO_2 Environments

运用腐蚀失重和电化学测量技术,研究普通低Cr油套管用钢在模拟塔里木油田环境的H2S/CO2腐蚀行为。结果表明:在模拟CO2腐蚀环境中,Cr元素在腐蚀产物膜中的富集显著改善了膜的保护性,低Cr钢表现出良好的抗CO2均匀腐蚀和局部腐蚀能力;在模拟CO2/H2S腐蚀条件下,H2S腐蚀占主导作用,其均匀腐蚀速率远小于单独CO2腐蚀环境中的均匀腐蚀速率;低Cr材料H2S腐蚀的阳极极化曲线存在较为明显的钝化区,交流阻抗图谱(EIS)拟合的H2S腐蚀极化电阻远大于CO2腐蚀极化电阻。

H2 S/CO2 corrosion behavior of low Cr casing and tubing steel at the simulated environments of Tarim oilfield was studied with mass loss and electrochemical impedance spectroscopy （EIS） and polarization curves. The results show that low Cr steel has the superior CO2 uniform and local corrosion resistance because Cr-rich in corrosion scale which improve the protection of corrosion scale. At the simulated CO2/H2S environment, H2S electrochemical corrosion dominates the corrosion course, and the uniform corrosion rate of low Cr steel is much less than that in CO2 environment. The passivation zone of low Cr steel appears obviously on anodic polarization curve in H2 S corrosion environment, and the fitted EIS showed that the polarization resistance of H2 S corrosion is much larger than that of CO2 corrosion.