Corrosion Behavior of 80SS Steel in Simulated Gas Wellbore Environment

The corrosion laws of wellbore material 80SS steel in a gas field under different conditions of H₂S partial pressures (0.005-0.1 MPa), CO₂ partial pressures (0.1-1.0 MPa) and temperatures (30-90 ℃) were studied by high temperature and high pressure corrosion simulation experiment and corrosion theory analysis. The results show that under the condition of CO₂ partial pressure of 1.5 MPa and temperature of 80 ℃, with the increase of H₂S partial pressure, the corrosion rate of 80SS steel decreased from 1.69 mm/a to 0.12 mm/a. When the partial pressure of H₂S was 0.1 MPa, there were tiny pits on the surface of the sample. When the partial pressure of CO₂ increased, the corrosion rate of 80SS steel increased under the condition of H₂S partial pressure of 0.01 MPa and temperature of 80 ℃, and extremely serious corrosion occurred. When the temperature rose from 30 ℃ to 90 ℃, the corrosion rate of 80SS steel increased from 0.24 mm/a to 0.98 mm/a, the grain size of corrosion products increased, and corrosion products could not cover the surface of sample completely, and the risk of localized corrosion gradually appeared.