N80钢在CO2、H2S及其混合介质环境中的腐蚀行为研究

针对N80钢油套管在CO2/H2S共存环境中的腐蚀问题，利用失重法与电化学测试方法作对比分析，并利用扫描电子显微镜以及X射线衍射仪对浸泡腐蚀试验后的N80钢试样进行研究。结果显示，浸泡腐蚀试验结果与电化学测试结果一致，在单独CO2环境中，N80钢的自腐蚀电流与平均腐蚀速率最大，腐蚀最严重；在单独H2S环境中，N80钢试样腐蚀速率最小，自腐蚀电流最小；在PCO2/PH2S=1∶ 0.3 时，主要以H2S腐蚀为主，但在表面发生局部产物膜剥落，此时的腐蚀速率高于纯H2S条件下的腐蚀速率。研究表明，在单独CO2环境中，腐蚀以阴极反应过程控制为主；在单独H2S环境中，腐蚀以阳极反应过程控制为主；在PCO2/PH2S=1∶ 0.3时，腐蚀以阴极反应过程控制为主。

Study on Corrosion Behavior of N80 Steel in CO2, H2S and Mixed Medium Environment

Aiming at the corrosion problem of N80 steel oil casing in CO2/H2S coexistence environment, the weight loss method and electrochemical test method are compared and analyzed, and the N80 steel samples after immersion corrosion test are studied by scanning electron microscope and X-ray diffraction. The results show that the immersion corrosion test results are consistent with the electrochemical test results. In the CO2 environment, the self corrosion current and average corrosion rate of N80 steel is the largest and the corrosion is the most serious. In H2S environment, N80 steel sample has the lowest corrosion rate and the lowest self corrosion current. When PCO2/PH2S=1∶0.3, it is mainly H2S corrosion, but local product film peeling occurs on the surface. At this time, the corrosion rate is lower than that under H2S. This shows that in the CO2 environment, the corrosion is mainly controlled by the cathode reaction process; In H2S environment, the corrosion is mainly controlled by cathode reaction process; When PCO2/PH2S==1∶0.3, the corrosion is mainly controlled by cathode reaction process.