Method to calculate the solubilities of light gases in petroleum and coal liquid fractions on the basis of their P/N/A composition

In this paper, a paraffinic/naphthenic/aromatic (P/N/A) compositional model is proposed for calculation of the solubilities of light gases such as methane, ethane, carbon dioxide, and hydrogen in various petroleum and coal liquid fractions under different conditions of temperature and pressure. The proposed model uses Scatchard-Hildebrand theory with a corrected value for the solubility parameter of the dissolving gas and characterizes the liquid phase by its P/N/A composition. The results show that, for the fractions studied, the P/N/A composition has an effect on gas solubility. The model correlated the solubilities of gases with an average error of 4.5% when evaluated with 11 fractions and more than 180 data points for a pressure range of 5-250 bar. Corrected solubility parameters for hydrocarbon gases are recommended for their use with petroleum fractions and coal liquids of different P/N/A compositions. The main advantage of the proposed approach is that no experimental data are required to adjust any binary parameter. The approach is of direct use with the values of the solubility parameters reported in this work and characterization parameters of the fraction.