Gas hydrate equilibrium dissociation conditions in porous media using two thermodynamic approaches

We employ two thermodynamic approaches, based on the equal fugacities and the equal activities, to predict the gas hydrate equilibrium dissociation conditions in the porous media. The predictions are made for the hydrate systems, CH₄/H₂O, C₂H₆/H₂O, C₃H₈/H₂O, CO₂/H₂O, CH₄/CO₂/H₂O, C₃H₈/CH₄/C₂H₆/H₂O, and CH₄/CH₃OH/H₂O. For the non-hydrate phase, we used the Trebble–Bishnoi equation in the fugacity approach and the Soave–Redlich–Kwong equation in the activity approach. For the hydrate phase, the van der Waals–Platteeuw model incorporated with the capillary model of Llamedo et al. M. Llamedo, R. Anderson, B. Tohidi, Am. Mineral. 89 (2004) 1264–1270] was used in the two approaches. The predictions are found to be in satisfactory to good agreement with the experimental data. The predictive ability of the fugacity approach is better than that of the activity approach.