Convection with Phase Change During Gas Formation from Methane Hydrates via Depressurization of Porous Layers

This is an analytical and numerical study of the generation and flow of methane gas through a layer of porous medium impregnated with solid clathrate hydrates. The porous layer is depressurized suddenly on its lower plane. The phase-change front advances upward under the influence of heat conduction and convection. The first part of the article describes a simplified analytical solution based on a unidirectional phase-change model in which the conduction in the gas-filled region behind the front is neglected. The second part presents numerical results for the evolution of the unidirectional phase-change process. Both methods lead to the conclusion that the rate of gas flow through the depressurized (bottom) plane of the layer decreases approximately as t−1/2.