Experimental study on formation characteristics of carbon dioxide hydrate in frozen porous media

Abstract

ABSTRACT Gas hydrate-based technology is a promising method for solidifying and sequestrating of CO2 gas into stratum sediments to reduce anthropogenic CO2 emissions and realize the exploitation of natural gas hydrate in the permafrost regions. In order to clarify the formation characteristics of CO2 hydrate in the porous media under condition of below the freezing point, the experiments were conducted in the frozen quartz sands. And the formation rate, the conversion rate and the gas storage capacities for CO2 hydrate were investigated through experimental study in the porous media. The results showed that, under the same temperature and initial pressure conditions, the formation rate, the conversion rate, and the gas storage capacities of hydrate increased with the decrease of particle sizes of the frozen quartz sands. And the ice content of the frozen quartz sands played little influence on the formation rate and the conversion rate of hydrate at the same particle size. Furthermore, the average formation rate attained 0.000544 mol∙h−1 in porous media below the freezing point. The conversion rate of ice attained 70.14, 81.72, and 90.61% in the frozen quartz sands with particle sizes of 500, 380, and 250 μm, respectively. The results also illustrated that, the gas-storage capacity of hydrate achieved 127.58, 144.04, and 152.65 L/L in the corresponding porous media. These results are of significance for guiding capture and sequestration of CO2 gas in the form of gas hydrate in stratum sediments.