A mathematical model for dissociation of gas hydrate

This paper presents a model for natural gas hydrate dissociation from the methane hydrate reservoir by depressurization or temperature-falling of the well. In this model, the controlling equations are consisted of quality conservation, momentum equilibrium and energy conservation equations. Four media: Free methane (gas), methane hydrate (solid), rock skeleton, and water (liquid) are in thermodynamic equilibrium. The heat suction by the dissociation and the convection-conduction are considered also. The geological formation is assumed to be uniform and the flow of free methane is regarded as flow through a porous media with porosity. It is shown that the dissociation rate increases with the increase of depressurization and the increase of initial saturation of gas hydrate and degrades fast with the distance from the boundary. The changes of the pressure on the boundary have large effects on the dissipation of the pore pressure. The changes of the heat conductivity have little effects on the dissociation of gas hydrate and the dissipation of pore pressure. Copyright © 2009 by The International Society of Offshore and Polar Engineers (ISOPE).