A computational tool for parameter estimation in EoS: New methodologies and natural gas phase equilibria calculations

Brazilian pre-salt reservoirs represent the discovery of large amounts of light oil, but at high pressures and containing high concentration of CO₂. Proper parameter estimation procedures are essential to perform more accurate predictions of their thermodynamic properties. Therefore, two new methodologies for such calculations have been implemented here: by applying simultaneously VLE and LLE to the metric;and by handling water content in dew point conditions. Utilizing the Cubic-Plus-Association (CPA) EoS, they were employed to obtain new parameters for water. Also, new parameters were obtained forH₂O + CO₂ mixtures, whose average absolute deviation in water content at high pressures fell from 24% to 3% compared to previous publications. The same procedure was performed for other aqueous mixtures containing H₂S and light hydrocarbons. Finally, this study has been applied into a natural gas compressing simulation with CO₂, studying streams properties comparing the parameters obtained in this work with the literature.