Abstract

PEREZ, Renee J.; HEIDEMANN, Robert A.  and  GONZALEZ-PARTIDA, Eduardo. Theoretical model to calculate mutual solubilities between non-polar gases and brines. Part 1: Development of thermodynamic equations. Bol. Soc. Geol. Mex [online]. 2009, vol.61, n.3, pp.325-337. ISSN 1405-3322.

We propose a thermodynamic model for the equilibrium of non-polar gases, water and aqueous sodium chloride solutions valid to high pressures, high temperatures, and to high ionic strength solutions. The model couples Henry's Law and an equation of state to reproduce experimental data in the aqueous phase and the gas-rich fuid phases. The standard state chemical potential of the solute in brines is related to the standard state chemical potential of the solute in pure water through a salting-out or Setschenov coefficient. The salting-out coeffcients are obtained from experimental data. The model reproduces all crucial phenomena, including three phase equilibrium, at temperatures below the critical temperature of water. The modeling approach cannot account for gas-gas equilibrium phenomena that occur in the vicinity of the water critical point, nor for the hydrate-vapor-liquid equilibrium near the melting point of water.

Keywords : Gases; brines; solubility; thermodynamics; water.

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