A model for single-phase PVTx properties of CO2-CH4-C2H6-N2-H2O-NaCl fluid mixtures from 273 to 1273Â K and from 1 to 5000Â bar

A thermodynamic model explicit in Helmholtz free energy is constructed to calculate the single-phase PVTx properties of the CO2-CH4-C2H6-N2-H2O fluid mixtures. Parameters of the binary CO2-H2O, CH4-H2O, C2H6-H2O and N2-H2O mixtures are regressed from assessed experimental data. On the basis of the binary mixture parameters, the model can be used to predict the single-phase volumes of the CO2-CH4-C2H6-N2-H2O-NaCl fluid mixtures with a simple approach. Comparison with a large number of experimental data shows that the model can reproduce the single-phase PVTx properties of the CO2-CH4-C2H6-N2-H2O-NaCl fluid mixtures from 273 to 1273 K and from 1 to 5000 bar, with or close to experimental accuracy. Online calculations can be made on the website: www.geochem-model.org/.