In order to find out the relationship of the heat transfer and the dissociation of permafrost gas hydrate in porous media, this study has conducted a hydrate dissociation experiment below freezing point in a cuboid pressure vessel. The dependences of gas production and hydrate dissociation on the following heat fluxes are also analyzed through numerical simulation: the heat conducted across the boundary QB, the heat injected from the well Qinj, the sensible heat change of the deposit QS, the heat absorbed by hydrate dissociation QH, the latent heat of ice melting QI, and the unutilized heat QL. The results show that the dissociation process of frozen gas hydrate can be divided into three steps: ice melting, hydrate dissociation, and ice regeneration. The existence of solid ice shows strong inhibition effect on hydrate exploitation. QH mainly comes from Qinj, and the heat transferred across the boundary is the main component of QL. It implies that the heat injection is the dominating driving force for hydrate dissociation below freezing point.
Keywords gas hydrates, heat transfer, depressurization, thermal stimulation, freezing point