Experimental study on the effect of pore size on carbon dioxide hydrate formation and storage in porous media

• A feasible method for sequestration and capture of CO2 gas into stratum sediments is proposed.
• We study the formation characteristics of CO2 hydrate in porous media with different pore size.
• Average formation rate of CO2 hydrate increases with pore size decreasing within a certain range.
• Performance of gas storage capacity relies on the characteristics of porous media.
• The mechanism explains the influence of porous media on formation characteristics of hydrate.

Hydrate method is feasible for solidification and storage of CO2 gas into stratum sediments. In order to study the storage process of carbon dioxide in the form of hydrate into seafloor sediments, the formation characteristics of carbon dioxide hydrate was investigated in porous media and the formation experiment of carbon dioxide hydrate has been conducted in quartz sand porous media in high-pressure vessel of 1.8 L with pore size of 26.7 nm, 14.2 nm and 13.8 nm, respectively. The results show that, pore size of porous media has an important influence on the formation characteristics of CO2 hydrate. Compared with porous media of 14.2 nm and 26.7 nm, the average formation rate and gas storage capacity of carbon dioxide hydrate attained 0.01328 mol/h and 53.558 L/L respectively. The results also indicated that, the smaller the pore size is, the longer the induction time and the larger the average formation rate and gas storage capacity of hydrate in porous media with pore size between 13.8 nm and 26.7 nm. It provided a theoretical guidance for solidification and storage of CO2 into seafloor sediments in the form of gas hydrate.