Mathematical Model of Replacing Methane in Hydrate with Carbon Dioxide When It Is Injected into a Reservoir Saturated with a Mixture of Hydrate, Methane, and Water

A mathematical model is proposed for the replacement of methane with carbon dioxide in a hydrate contained in a reservoir in thermodynamic equilibrium with water and free methane. The substitution reaction region is assumed to be narrow enough to be approximated by the conversion front. A self-similar solution is found that reduces the problem to the numerical analysis of a system of transcendental equations. Numerical experiments show that there exist three characteristic regimes of injection, whose implementation depends on the amount of water in the free state in the reservoir.