Experimental Evaluation of Corrosion Modeling on Carbon Steel in Sub-critical and Supercritical CO₂ Environments

This study is aimed to compare the corrosion rate predictions obtained from CO₂ corrosion models with experimental results on mild carbon steel (C1018) exposed in brine solutions in both sub-critical CO₂ and supercritical CO₂ (SC-CO₂) environments. Corrosion behavior of mild carbon steel is investigated by immersing in a still 1 wt.% NaCl solution at temperatures from 60 – 120°C in both 400 psi (Sub-critical CO₂) and in 1600 psi (Supercritical CO₂), respectively. The experimental results are evaluated by comparing with the CO₂ corrosion calculation algorithms developed by Anderko et al. The corrosion mechanism kinetics are studied by Linear Polarization Resistance (LPR) and Electrochemical Impendence Spectrum (EIS). Surface morphology, element distributions on the surface, and crystal structures of the mild carbon steel are evaluated The results indicate that the corrosion rate of C1018 in the sub-critical environment at steady state in the LPR measurement showed higher corrosion rate than its theoretical value at high temperature, whereas the corrosion rate of C1018 in supercritical environment at steady state was found to decrease with the temperature and was found consistently lower than the predicted value.