Effect of Initial Pressure on the Formation of Carbon Dioxide Hydrate in Frozen Quartz Sand

Sequestration and storage of CO2 in naturally occurring gas hydrate reservoirs is considered an effective strategy against global warming. In order to study the formation process of CO2 hydrate simulating the permafrost environment, the experiment was carried out in high-pressure vessel frozen quartz sand. The formation characteristics of CO2 hydrate were studied, and the influence of initial pressure on the hydrate formation process was discussed through experiments. The results showed that the formation rate of CO2 hydrate increased with the increase of the initial pressure of CO2 under the condition below the liquefied pressure. Furthermore, the formation rate of hydrate presented a similar change trend under the condition of the liquefied pressure. The results also indicated that the higher the initial pressure of CO2, the higher the final conversion rate of hydrate. Under the condition below the liquefied pressure, the highest conversion rate of ice was 66.3%. Furthermore, the highest conversion rate of ice attained 72.8% under the condition of the liquefied pressure. These results will provide a theoretical guidance for sequestration and storage of CO2 gas and exploitation of natural gas hydrate in permafrost regions.