采用高温高压釜模拟CO₂辅助蒸汽驱油注气井的工况条件，在温度160℃和CO₂分压1~4 MPa条件下，对N80钢进行了挂片腐蚀试验，研究了CO₂分压对其腐蚀行为的影响。结果表明：随着CO₂分压的升高，腐蚀速率先升高后降低，并在CO₂分压为2 MPa时达到最大，其值为0.073 7 mm·a^-1；N80钢腐蚀产物的主要成分是FeCO₃和少量Fe₂O₃，随着CO₂分压的升高，FeCO₃晶体尺寸减小，当CO₂分压为3~4 MPa时FeCO₃晶体发生融合；在试验条件下，N80钢的腐蚀速率在0.034 7~0.073 7 mm·a^-1范围，均小于油田腐蚀速率控制指标（0.076 mm·a^-1），满足CO₂辅助蒸汽驱油注气井油套管的性能要求。

The high temperature and high pressure autoclave was used to simulate the working conditions of CO₂ auxiliary steam drive oil gas injection well. The coupon corrosion test was conducted on N80 steel at 160℃ and CO₂ partial pressures of 1-4 MPa, and the effect of CO₂ partial pressure on corrosion behavior of N80 steel was studied. The results show that with CO₂ partial pressure increasing, the corrosion rate increased first and then decreased; when the CO₂ partial pressure was 2 MPa, the corrosion rate reached the maximum value of 0.073 7 mm·a^-1. The main composition of corrosion products of N80 steel was FeCO₃ and a small amount of Fe₂O₃. With the increase of CO₂ partial pressure, the size of FeCO₃ crystals decreased, and FeCO₃ crystals mixed together when CO₂ partial pressure was 3-4 MPa. Under the test condition, the corrosion rate of N80 steel was 0.034 7-0.073 7 mm·a^-1 which was lower than the corrosion rate control line of oil field (0.076 mm·a^-1) and met the property requirement of CO₂ auxiliary steam drive oil well casing.