Localised corrosion failure of an L245N pipeline in a CO2-O-2-Cl- environment

Multicomponent thermal fluid flooding has become a widely used and very effective heavy-oil recovery technology, but the harsh CO2-O-2-Cl- environment can lead to serious corrosion perforation failure of the pipeline. Therefore, the influence of O-2 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 O-2 content, the general corrosion rate and localized corrosion rate increased. The uneven protection performance of the product after the addition of O-2 was found to be the key cause of localized corrosion. In addition, the synergistic effect of O-2-Cl- promoted the lateral and longitudinal expansion of pits. The results of the grey correlation showed that the temperature (30-120 degrees C) had a greater impact on localized corrosion compared with the content of O-2 (0-0.045 MPa) and Cl- (0-16,000 mg/L).