Experimental research on gas hydrate decomposition in frozen rocks

Abstract

In the course of experimental investigations, the self-preservation effect of hydrocarbon gas hydrate was discovered after a pressure decrease below the equilibrium point of hydrate formation at temperatures below 0°C ( T < 0°C). Primary surface decomposition of gas hydrates leads to the formation of an isolating ice film on the surface of hydrate particles, which stops their further decomposition, and so gas hydrates can exist at low pressures for a very long time. Geologic applications of the effect are discussed. Gas hydrate decomposition in unfrozen rocks at low temperatures (0 to + 5°C) can initiate permafrost rocks formation as a consequence of heat through phase transitions of hydrates. Special experiments on rocks freezing by decomposing gas hydrates were made. Thermodynamic two-phase equilibrium between ice and methane hydrate is discussed with the Van Der Waals-Platteeuw clathrate solution model.