Effect of temperature and pressure on corrosion behavior of X65 carbon steel in water-saturated CO₂ transport environments mixed with H₂S

The effect of temperature and pressure on corrosion behavior of X65 carbon steel in water-saturated supercritical CO₂ containing H₂S was studied to determine the role of H₂S on the corrosion product formation and corrosion mechanism. Weight loss measurements showed that the highest corrosion rate of 0.190 mm/year was recorded at 35 °C and 8 MPa. The presence of 1000 ppmv H₂S resulted in the corrosion products comprised of a double-layer structure in both supercritical and non-supercritical conditions. The results indicated that the presence of 1000 ppmv H₂S has significantly influenced on the corrosion mechanisms, corrosion product morphology and composition as well as promoted the precipitation of water based on thermodynamic model.