Some Observations on the Corrosion of Carbon Steel in Sour Gas Environments: Effects of H₂S and H₂S/CO₂/CH₄/C₃H₈ Mixtures

Experimental results and analyses on the corrosion of carbon steel in simulated aqueous sour gas environments are reported. Tests were performed at temperatures and pressures up to 95 C (203 F) and 4.2 MPa (600 psig), respectively. Detailed thermodynamic and kinetic analyses of the experimental data were used to explain the observed corrosion behavior by partial reconstruction of the experimental polarization characteristics from theory. The results suggest that the cathodic polarization characteristics originate in the reduction of H₂O, HCO₃⁻, H₂S, and HS⁻, and that corrosion product formations during anodic polarization are preceded by the oxidation of iron to the soluble cation Fe²⁺.