Effect of Well Depth Temperature on Corrosion of X60 Pipeline Steel in Environment with High CO₂-H₂S-Cl^- Content

A high temperature and high pressure reactor was used to simulate the corrosion environment with high CO₂-H₂S-Cl^- content, and corrosion simulation tests were carried out on X60 pipeline steel at constant well depth temperatures and step-changing well depth temperatures. The uniform corrosion rate of X60 pipeline steel was evaluated by weight loss method. And the effect of well depth temperature on the corrosion behavior of X60 pipeline steel were studied by means of laser confocal microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results showed that in the environment with high CO₂-H₂S-Cl^- content, pitting corrosion occurred on the surface of X60 pipeline steel at constant well depth temperatures. The corrosion rates of X60 pipeline steel decreased with the increase of temperatures. The corrosion rates of X60 pipeline steel at step-changing well depth temperatures were lower than those at constant well depth temperatures, but the risk of localized corrosion rose with the increase of temperature drop.