采用高温高压模拟腐蚀试验、动电位扫描技术和X射线光电子能谱仪(XPS)等手段研究了镍基合金G3在高含H2S和CO2腐蚀环境中的腐蚀行为。结果表明, 在高温高压(90 ℃, 32 MPa, pH2S为3.4 MPa, 体积分数10.49%, pCO2为3.3 MPa, 体积分数为10.41%)的模拟气田采出液中, 镍基合金G3发生了明显腐蚀, 腐蚀产物由片状晶粒构成; 在含50%H2S气田采出水中加入CO2促进了合金的腐蚀, 当CO2的体积分数进一步提高到50%, 合金点蚀敏感性下降; 在50%H2S和50%CO2环境中, Cl-提高了合金点蚀敏感性, 同时高浓度Cl-破坏了合金钝化膜自修复能力, G3在该腐蚀环境中形成的钝化膜由Cr2S3, Cr2O3, FeS, Fe2O3, Ni(OH)2和MoO3等组成。随着使用环境条件的恶化, 合金钝化膜遭到破坏, 腐蚀加速。

Corrosion behaviors of the nickel base alloy G3 in the environment containing high contents of H2S and CO2 were investigated by simulated high temperature and high pressure corrosion test, dynamic potential scanning technique and X-ray photoelectron spectroscopy (XPS). The results show that the nickel base alloy G3 corroded distinctly in simulated natural gas field produced-water under the conditions of 90℃, total pressure of 32 MPa, H2S partial pressure of 3.4 MPa and CO2 partial pressure of 3.3 MPa. Corrosion scale formed on the alloy surface was made up with flake-like grains. Adding CO2 enhanced the pitting corrosion susceptibility of the alloy in the simulated natural gas field produced-water containing 50% H2S, however, pitting corrosion was suppressed when CO2 content further increased. In 50%H2S and 50%CO2 containing environment, chloride increased the pitting corrosion susceptibility, and high concentration of chloride harmed the self-repair of the passive film. The passive film was consisted of Cr2S3, Cr2O3, FeS, Fe2O3, Ni(OH)2 and MoO3 in above corrosive environment. The passive film formed on the alloy was damaged and corrosion becames more badly when the alloy was used under the condition of higher temperature and partial pressures of H2S and CO2, and higher concentration of chloride.