模拟油田CO2驱油现场环境, 利用高温高压反应釜, 采用失重法、扫描电镜(SEM)、X射线衍射(XRD)等方法, 研究了不同CO2分压对X80管线钢腐蚀性能的影响。结果表明, X80管线钢的腐蚀速率随着CO2分压的升高呈先升高后下降的趋势, 在CO2分压为1.5 MPa时达到最大值。当CO2分压为0 MPa和0.5 MPa时发生均匀腐蚀, 当分压升高到1.5 MPa和2 MPa时发生了局部腐蚀。CO2分压为0 MPa时的腐蚀产物为非晶态物质, 其余各分压下的腐蚀产物均以FeCO3为主。随着CO2分压的升高, 腐蚀产物与基体结合的紧密度随着CO2分压的升高越来越紧密; 腐蚀产物膜厚度呈先升高后降低的趋势, 与腐蚀速率的变化相对应。

The effect of CO2 partial pressure on corrosion resistance of X80 pipeline steel was investigated in high temperature and pressure autoclave simulating the downhole environment of an oil field, using the weight loss method, SEM and XRD. The results showed that with increasing CO2 partial pressure , the corrosion rate of X80 pipeline steel showed the tendency of fluctuation, and the maximum rate appeared at the CO2 partial pressure of 1.5 MPa. Uniform corrosion occurred when the CO2 partial pressure was 0 MPa and 0.5 MPa. When the CO2 partial pressure was 1.5 MPa and 2 MPa, localized corrosion occurred. The corrosion product was composed of noncrystalline substance at partial pressure of 0 MPa, and mainly composed of FeCO3 at other partial pressures. With increasing the CO2 partial pressure, the combination between corrosion product and substrate was increasingly close, and the thickness of corrosion product showed the tendency of fluctuation, corresponding to the change in corrosion rate.