LAUSR

Abstract Solubility of N2, CO2 and CH4 in petroleum fluids is estimated using the Peng-Robison cubic equation of state and three different mixing rules: the classical mixing rule of van der Waals (vdW), the modified Huron-Vidal of order one (MHV1) mixing rule and the universal mixing rule (UMR). The petroleum fluids were split out in pseudocomponents using a mass distribution procedure. Then, to determine equation-of-state parameters, pseudocomponents were characterized by a group contribution method, where the Gibbs free energy is minimized. In the proposed methodology, mixing-rule parameters for predicting gas solubility from binary mixtures of identifiable components were used in unidentifiable petroleum fluids. Twenty-two systems, which include bitumens, heavy oils, refinery cuts and coal liquids, were considered in order to assess the methodology. Good agreement between experimental data and predicted values were obtained for the UMR and vdW mixing rules, but significant deviations are obtained with the MHV1 mixing rule. The total absolute average deviations are 13%, 15% and 30% for the UMR, vdW and MHV1 mixing rules, respectively.