Phase equilibrium modeling for carbon dioxide Capture and Storage (CCS) fluids in brine using an electrolyte association equation of state

A modified electrolyte cubic plus association equation of state (eCPA EoS) is proposed here as a suitable model for CO2 Capture and Storage (CCS) fluids to model CO2 , CH4 , H2S, N2 , O2 , Ar, and air solubility in multi-component brines containing NaCl, KCl, CaCl2 , MgCl2 , and Na2SO4. A new correlation of the g -factor of water as a function of temperature is presented to accurately calculate the dielectric properties of pure water with CPA EoS and a new formula related to ions associated with polar molecules is pre-sented to describe the mixed solvents containing salts by neglecting ion-solvent association, which avoid the computational complexity of hydrogen bond formation. The performance of the modified eCPA model is improved for modeling the gas-water system by considering the cross association between H2S/CO2 and water. The modified eCPA model can accurately calculate the gas solubility in brine and water con-tent in gas phase for water-salt-gas systems.(c) 2023 Elsevier Ltd. All rights reserved.