Study of Filtration Processes in a Gas-Hydrate Reservoir Taking into Account Salinity and Solid-Phase Inclusions

The method of splitting by physical processes is consistently applied to the problems of underground hydromechanics related to gas hydrates, taking into account the presence of ice and the ice–water phase transition, as well as the presence of salt and gas dissolved in water. The systems are reduced to a block form, with the separation of the dissipative and hyperbolic parts. It is shown by the method of characteristics that the usual approximation of the upstream coefficients must be modified here. The governing variables in flow zones that differ from each other in the number of phases and components are chosen using the Gibbs phase rule. A general mathematical model is constructed for the entire region of the process, taking into account the dynamic appearance and disappearance of such zones as a result of filtration and phase transitions. Based on the developed discrete algorithms, the problem of the interaction of a vertical fault and a horizontal reservoir containing a gas hydrate with a dynamic transition of the hydrate-equilibrium and thawed zones is numerically studied.