This software implements two models. The default model is an equation of state for the NaCl-H₂O-CO₂-CH₄ system (publication pending) that extends the earlier model for the NaCl-H₂O-CO₂ system reported in Geochimica Cosmochimica Acta (1995), Vol. 59, pages 2869-2882. This model is in good agreement with the PVT and phase equilibria data in a temperature range from 300 to 1000 degrees C and a pressure range from 0 to 6000 bar (PVT data) or 0 to 3000 bar (phase equilibria). If the input compositions do not include NaCl, the program automatically reverts to the highly accurate equation of state for the H₂O-CO₂-CH₄ system reported in Geochimica Cosmochimica Acta, (1992), Vol. 56, pages 2619 to 2631. This second model applies to the temperature range from 50 to 1000 degrees C (lower temperatures than those of the default model) and pressures from 0 to 3000 bar. Results of this model are considerably more accurate in the critical region for a given composition than are those of the default model.

Run Geofluids Model 1

This software implements the one fluid corresponding states equation of state model for the H₂O-CO₂-CH₄-N₂ system reported in Geochimica Cosmochimica Acta (2000), Vol. 64, pages 1069-1075. The model is most accurate in the high temperature and pressure ranges from about 1.3 times the critical temperature of the least volatile component to 2000 K and from 0 to 100 kbar. It should not be used to calculate thermodynamic properties near and below the critical condition of water. It will not predict the lower critical curve or liquid-vapor coexistence.

Run Geofluids Model 2