Gas injection into a moist porous medium with the formation of a gas hydrate

The model problem of the formation of a gas hydrate when a gas is injected into a porous medium, filled in the initial state with a gas and water, is considered in the one-dimensional approximation. A detailed pattern of the seepage flow with phase transitions for different modes of gas injection is obtained. Three seepage modes in a porous medium are possible, which differ qualitatively in the temperature and hydrate saturation fields. At low boundary pressures no hydrate is formed and the temperature distribution increases monotonically. As the boundary pressure increases, when the corresponding values of the pressure and temperature on the phase diagram lie in the region of gas-hydrate stability (below the equilibrium curve), a purely frontal pattern of hydrate formation is obtained with a monotonic temperature distribution. When the boundary pressure is increased further, an extended region of hydrate formation appears with a convex temperature profile, where, depending on the values of the boundary pressure, the hydrate saturation may be continuous (at high boundary pressures) or change abruptly at lower boundary pressures.