Abstract: CO₂ sequestration in marine sediments as solid hydrates is a potential way to capture and store anthropogenic CO₂. In this study, hydrate formation from liquid CO₂ in marine sediments was simulated in a glass beads bed, and the factors affecting the kinetics of hydrate formation were investigated. The results indicated that the rapid initial hydrate formation with a high driving force always increases the mass transfer resistance, which slows down hydrate growth. The final ratio of water conversion is higher under conditions of low temperature and higher pressure. A smaller particle size is conductive to initial CO₂ hydrate growth, but the water conversion ratio in a bed with larger particles is slightly higher. Compared with other factors, the change in water saturation has an obvious effect on the final water conversion. To inhibit the initial hydrate formation during the injection process, in this paper, a kinetic inhibitor is proposed for pre-injection into marine sediments. This work shows that at a low pressure, a low-concentration inhibitor has an obvious inhibition effect on hydrate growth. However, at a high pressure, it is necessary to increase the concentration of inhibitor to produce an obvious inhibition effect.

Key words: Liquid CO₂, Hydrate formation, Sequestration, Kinetic, Water conversion

摘要： CO₂ sequestration in marine sediments as solid hydrates is a potential way to capture and store anthropogenic CO₂. In this study, hydrate formation from liquid CO₂ in marine sediments was simulated in a glass beads bed, and the factors affecting the kinetics of hydrate formation were investigated. The results indicated that the rapid initial hydrate formation with a high driving force always increases the mass transfer resistance, which slows down hydrate growth. The final ratio of water conversion is higher under conditions of low temperature and higher pressure. A smaller particle size is conductive to initial CO₂ hydrate growth, but the water conversion ratio in a bed with larger particles is slightly higher. Compared with other factors, the change in water saturation has an obvious effect on the final water conversion. To inhibit the initial hydrate formation during the injection process, in this paper, a kinetic inhibitor is proposed for pre-injection into marine sediments. This work shows that at a low pressure, a low-concentration inhibitor has an obvious inhibition effect on hydrate growth. However, at a high pressure, it is necessary to increase the concentration of inhibitor to produce an obvious inhibition effect.

关键词: Liquid CO₂, Hydrate formation, Sequestration, Kinetic, Water conversion