Corrosion Behavior of N80 Steel and 13Cr Steel for Oil Well Pipe in Multi-Component Thermal Fluid Environment

The corrosion behavior of oil well pipe materials N80 steel and 13Cr steel in multi-component thermal fluid environment at different temperatures and O₂ partial pressures was investigated by simulated corrosion test in high temperature and high pressure reactor. The corrosion rates of the materials were evaluated by weight loss method. The change rule of corrosion rate and corrosion products of the two materials were analyzed by laser confocal microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that when the temperature exceeded 180 ℃, the corrosion rate of the two materials increased with the increase of temperature, and Fe₃O₄ was formed in the corrosion products. With the increase of O₂ partial pressure, the corrosion products gradually changed from FeCO₃ to Fe₃O₄, and the corrosion rates of two materials were increased. When the O₂ partial pressure was above 0.2 MPa, the corrosion products were all transformed into Fe₃O₄, and the uniform corrosion and local corrosion were aggravated.