Investigating the micro-turbulent corrosion mechanism of pipeline defects based on a combined experimental and simulation approach

The existence of pipeline defects in oil and gas gathering pipelines predisposed the pipeline to rupture under the synergistic effects of local micro–turbulence and electrochemical corrosion. Here, a combination of experimental and simulation methods was proposed to facilitate the investigation of CO₂ corrosion and the mass transfer process in pipeline defects. The corrosion kinetic characteristics of the defect region were clarified by coupling wire beam microelectrode (WBE) and electrochemical impedance spectroscopy (EIS). Additionally, the effect of flow mass transfer on the corrosion of pipeline defects was investigated by using the existing mass transfer models and COMSOL Multiphysics simulations. The results showed that different locations of the pipeline defects exhibited different mass transfer behavior and corrosion variations. The mass transfer process at the bottom of the defect was lower than that in the upper and lower edge of the defect. Furthermore, the bottom of the defect behaved as an anode and corrodes more severely at low flow velocities. The enhanced mass transfer process led to more severe corrosion at the upper and lower edges of the defect at high flow velocities.