Impact of Aromatic Compounds on Acid Gas Injection: Experimental Measurements and Predictions with the GC-PR-CPA Equation Of State

As more new fields contain high concentrations of carbon dioxide and hydrogen sulphide, there is a requirement for accurate equilibrium data for systems containing CO2 and/or H2S. Acid gases are undesirable and they are removed from the hydrocarbon stream after gas processing. They can be re-injected into the reservoir to enhance gas/oil recovery. However some hydrocarbons (e.g. methane and ethane) and aromatic compounds (e.g. benzene and toluene) may remain in the acid gases stream, becoming undesirable impurities leading to operation issues.
Accurate experimental measurements of hydrate dissociation points are essential to validate predictions of thermodynamic models. Although there is a significant amount of data available for sweet gas there is still a requirement for measurements for sour gas systems. Experimental measurements, vapour-liquid and vapour-liquid-liquid equilibria or hydrate dissociation conditions, have been conducted for different mixtures of hydrocarbons containing CO2 and/or H2S in high concentration. The GC-PR-CPA and SRK72-CPA were used in this work to predict the different phase equilibria of systems with acid gases and the hydrate-forming conditions are modelled by the solid solution theory of van der Waals and Platteeuw. The results reveal that our model is in good agreement with experimental data