Effect of Gas Purity on Corrosion Behavior of Tubing and Casing under High-Temperature Supercritical CO₂Condition

In order to clarify the influence of gas source purity on the service performance of pipes during CO₂oil recovery, high-temperature and high-pressure reaction vessels were used to conduct corrosion simulation tests on N80 and 13Cr oil casings under high-temperature and supercritical CO₂conditions with different purity CO₂gas sources. SEM, EDS, and XRD methods were combined to analyze the corrosion product film. The results show that the corrosion of N80 and 13Cr samples was more severe in low purity CO₂environment, and there was a serious risk of pitting of 13Cr. The main reason was that under high pressure condition, low purity CO₂would increase the amount of dissolved oxygen in the solution and cause serious oxygen corrosion of N80 and 13Cr. Therefore, when using CO₂oil recovery technology, the purity of the gas source should be strictly controlled.