Injection of liquid CO
2 in hydrate layers of natural gas is a promising tech-nique to recover CH
4 simultaneously segregating CO
2 from the biosphere. This work exam-ined the rate of the conversion of CH
4-hydrate immersed in liquid CO
2 to CO
2-hydrate in a tem-perature range of 274-281K and the pressure range of 4-10MPa for 800-1600h.
The conversion was on going even at the end of every experiment. Mass-transfer in hydrate solid is presumed to dominate the conversion rate. The solute mobility of methane and CO
2 in hydrate solid was determined for feasibility studies of this technique in the future. The solute mobility raised as the temperature increased, it decreased as the total pressure increased.
Significantly high conversion rate was observed when the total pressure was set below the dissociation pressure of CH
4-hydrate and above the hydrate forming pressure of CO
2.
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