Application of a Thermodynamic Model to Predict the Solubility of CO₂ in Pure H₂O and in Salt Solutions and Corrosion Prediction of Carbon Steel under Supercritical Conditions

Abstract

CO₂ sequestration requires the prediction of pressure-temperature-composition (P-T-X) data for CO₂ and water mixtures at significantly high pressures and temperatures and these applications most commonly deal with subsurface water containing dissolved salts. In this study, a thermodynamic model was used to predict the solubility of supercritical CO₂ in pure water and in the presence of chloride salts in the aqueous phase (i.e. brine solutions) for temperatures up to 100⁰C and pressures up to 60 MPa. The concentrations of the corrosion species in the aqueous phase was predicted and were compared with experimental data available from open literature. A mechanistic model is presented to predict the internal corrosion of carbon steel under such operating conditions of temperature, pressure and salt concentrations.