Corrosion Behavior of CO₂-EOR Downhole Accessories in Oil Wells

The corrosion behavior of 35CrMo, 3Cr13 and 45^# steel in simulated CO₂ dioxide enchanced oil recovery (CO₂-EOR) oil well environment at 13 MPa, 60 ℃, with CO₂ content (volume fraction) of 20%, 50% and 80% and well flow material injected circularly at 3mL/min were studied by means of high temperature and high pressure dynamic corrosion test and electrochemical test. The morphology of corrosion products was characterized by scanning electron microscopy (SEM). The results showed that the maximum corrosion rate of 3Cr13 steel was 0.006 mm/a, and only slight CO₂ corrosion occurred. The minimum corrosion rates of 35CrMo and 45^# steel were both greater than 0.076 mm/a, and the CO₂ corrosion resistance was poor. The corrosion rate of steels with low Cr (0-9%) decreased with the increase of CO₂ content. 3Cr13 steel was suitable as downhole accessory material of CO₂-EOR oil well.