Mathematical Simulation of the Injection of Gas into a Stratum Saturated Partially with Water with Regard for the Nonequilibrium Hydrate Formation in the Stratum

A mathematical model of the injection of methane into a porous stratum saturated initially with methane and water, constructed with regard for the nonequilibrium formation of a gas hydrate in the stratum, is presented. Distributions of the pressure and temperature in such a stratum and of its saturation with the hydrate formed in it were determined and analyzed. It is shown that, in the general case, the formation of a gas hydrate in a porous stratum proceeds with the formation of three characteristic regions in it: a near region with pores containing the gas and the hydrate, a far region saturated with gas and water, and an intermediate region dividing the near and far regions and containing the gas, the hydrate, and the water. It was established that, with time, the length of the intermediate region decreases. The hydrate-formation processes calculated by the equilibrium and nonequilibrium schemes were compared. It is shown that the higher the permeability of a stratum, the larger the difference between the results of calculations by these schemes.