On injection of hydrate-forming gas into a gas-saturated snowy agglomerate while transition through the ice melting point

Abstract

The paper considers the process of injection of hydrate-forming gas (methane) into a snowy agglomerate (ini-tially saturated with methane). The self-similar problem statement demonstrates that if the warm gas (T_e > 0 °C) is injected under a high pressure (p_e ≥ p_*, where the critical values are found from the initial temperature T₀, pressure p₀, volumetric snow saturation S_i0, and permeability of snow) into the filtration zone with phase transition, this produces four characteristic zones: the nearest zone with all snow transformed into hydrate, therefore, the aggregate filled only with gas and hydrate, the two intermediate zones where gas, snow or water and hydrate are in phase equilibrium state, and the distant zone filled only with gas and snow. The obtained analytical and numerical solutions give an analysis of the influence of key input parameters like initial state of the aggregate, gas injection rate, and its temperature, on the structure and the length of four filtration zones.