Prediction of CO2 solubility in electrolyte solutions using the e-PHSC equation of state

Abstract The aim of this work is to provide a reliable model to predict CO2 solubility in formation brines using an equation of state (EoS). In this regard, the electrolyte perturbed hard sphere chain equation of state (e-PHSC) was utilized to describe the solubility of carbon dioxide in aqueous electrolyte solutions. Using the ion-specific parameters and a binary interaction parameter between ions and CO2, CO2 solubilities in single electrolyte solutions (NaCl, KCl, CaCl2, MgCl2, Na2SO4, and K2SO4) were calculated. Then the model capability was evaluated for CO2 solubility in mixed-electrolyte solutions. Obtained results prove that e-PHSC EoS can be used for the prediction of CO2 solubility in mixed electrolyte solutions without any additional adjustable parameters. Finally, the predictive capacity of the e-PHSC EoS was explored for two synthetic formation brines up to 423 K. The result shows that the CO2 solubility in formation brines can be efficiently predicted using e-PHSC EoS.