Thermodynamic Consistency Test for Experimental Solubility Data in Carbon Dioxide/Methane + Water System Inside and Outside Gas Hydrate Formation Region

Abstract

Accurate knowledge of solubility in carbon dioxide/methane þ water system over wide ranges of temperatures and pressuresisessentialforthepetroleumindustry.However,experimentalmeasurementsofsuchsolubilities(especiallyingashydrate formation region) are challenging. For instance, concentrations of these gases in water are low, and furthermore reaching the equilibrium conditions near and inside gas hydrate formation region is a time-consuming process. Those difficulties may consequently result in generation of unreliable experimental data. This work aims at performing a thermodynamic consistency test based on an area approach to study the reliability of such experimental data reported in the literature and points out the suspected inconsistent data. A thermodynamic model based on the Valderrama modification of the Patel-Teja equation of state along with non-density dependent mixing rules is used to model the solubilities in the gas/vapor and liquid water phases. For modeling the solubility of carbon dioxide/methane in water under liquid water-hydrate equilibrium conditions, the van der Waals- Platteeuw model accompanied with Henry's law approach is employed. The results show that about 23 % of all of the investigated experimental data seem to be thermodynamically consistent, 57 % inconsistent, and 20 % not fully consistent data.