Thermodynamic modelling of gas hydrate dissociation conditions in porous medium in the presence of NaCl/methanol aqueous solution

Abstract

Due to the growing significance of the existence of gas hydrates in natural media like the ocean floor/permafrost regions and the extraction of natural gas from hydrate reservoirs using thermodynamic hydrate inhibitors, investigating the dissociation of gas hydrates in porous media in the presence of inhibitors is crucial. This work examines a broad range of laboratory data on the dissociation conditions of gas hydrates in the porous mediums when salt/alcohol aqueous solutions are present. The temperature of gas hydrate dissociation in the presence of pure water is calculated using the van der Waals–Platteeuw solid solution theory. The water activity in the porous medium is then calculated by taking into account a number of variables, including the radius of the porous medium, molar volume, shape factor, wetting angle, and surface tension. The Pitzer and Margules activity coefficient models are used to determine the water activity in the presence of salt and alcohol, respectively. Lastly, the gas hydrate dissociation temperature in a porous medium in the presence of salt and/or alcohol aqueous solution is determined by combining Piereon's model with an enthalpy-based correlation that was proposed by Azimi et al. The selected package can consistently correlate the gas hydrate dissociation conditions in a porous medium in the presence of alcohol or salt aqueous solution. The average absolute deviation (AAD) of 0.67 K for the whole data bank (90 experimental data points) shows the precision of the model.