Localised corrosion failure of an L245N pipeline in a CO2–O2–Cl− environment

Multicomponent thermal fluid flooding has become a widely used and very effective heavy-oil recovery technology, but the harsh CO2–O2–Cl− environment can lead to serious corrosion perforation failure of the pipeline. Therefore, the influence of O2 content and main controlling factors on corrosion perforation were investigated through a weight-loss experiment, corrosion defect test, characterization and grey correlation method. The results showed that, with the increase in O2 content, the general corrosion rate and localized corrosion rate increased. The uneven protection performance of the product after the addition of O2 was found to be the key cause of localized corrosion. In addition, the synergistic effect of O2–Cl− promoted the lateral and longitudinal expansion of pits. The results of the grey correlation showed that the temperature (30–120 °C) had a greater impact on localized corrosion compared with the content of O2 (0–0.045 MPa) and Cl− (0–16,000 mg/L).