Pore-scale investigations on the effects of ice formation/melting on methane hydrate dissociation using depressurization

Abstract

Ice phase affects the methane hydrate dissociation in the porous medium channels. Thus, the investigations on the roles of ice formation and melting in hydrate dissociation around the freezing point are necessary. A model that considers the interphase heat transfer and microscale effects was developed in our previous work. In this study, we extended the work to investigate the effects of ice formation/melting on methane hydrate dissociation in micro porous media channels. Our investigations showed that water temperature, distribution of water and methane, pressure, cumulative methane generation and residual methane hydrate and heat changes in the system are affected seriously by the ice phase. The formation of ice favors the hydrate dissociation for a while, and then inhibits the dissociation of methane hydrate due to the thickening ice. The pressure variations are indications of the possible reformation of methane hydrate and deformation of porous medium channels. The change in heat as one of the key factors for hydrate decomposition shows a more complex changing peculiarity as a result of the ice formation/melting.