Hydrate formation during an offshore oil/gas drilling operation can yield serious problems, such as plugging in the pipeline and damages at the wellhead. On the other hand, the idea of using CO₂ hydrate as a self-trapping mechanism has been emerging for sequestering carbon dioxide in the offshore sediments. In this regard, we conducted a fundamental experimental study to investigate the characteristics of CO₂ hydrate’s formation-and-dissociation under the different CO₂-water ratios, stimulation method, and dissociation temperature, as well as the density and size of CO₂ bubbles after the dissociation of CO₂ hydrate. The overall results show that the amount of CO₂ in the bulk condition exerted a significant impact on the characteristics of the formation and dissociation of CO₂ hydrate. In the CO₂-limited condition, CO₂ was insufficient to saturate water, and thus, nucleate and form hydrate crystals. On the other hand, in the water-limited condition, the amount of CO₂ was able to fully saturate the aqueous phase and lead to the nucleation and formation of hydrate crystals. As the volumetric ratio of CO₂ increased, longer melting and equilibrium time was monitored, which suggests that the formed CO₂ hydrate could be denser and more stable. Besides, a denser population of smaller CO₂ bubbles resulted after the hydrate dissociation, which implies more intense shearing of CO₂ molecules in the water phase. Higher dissociation temperature from 8 to 22°C led to smaller and more bubble formation, while differences in the mixing speed (60 or 120 rpm) and style (full- or half-tumbling) resulted in a negligible effect on CO₂ hydrate formation and dissociation. Further study on the CO₂-water-solid system will help to understand the formation and dissociation characteristics of CO₂ hydrate under the different bulk and porous medium condition.

在海上石油/天然气钻井作业中形成水合物会产生严重的问题，例如管道堵塞和井口损坏。另一方面，已经出现了使用CO ₂水合物作为自捕机制来隔离离岸沉积物中二氧化碳的想法。在这方面，我们进行了基础实验研究，以研究不同CO _2-水比，刺激方法和离解温度下CO ₂水合物的形成和离解特征，以及CO ₂气泡的密度和大小CO ₂水合物解离后。总体结果表明，CO ₂的量在整体条件下，CO ₂水合物的形成和离解特性具有显着影响。在CO ₂限制的条件下，CO ₂不足以使水饱和，因此成核并形成水合物晶体。另一方面，在水受限的条件下，CO ₂的量能够使水相完全饱和并导致成核并形成水合物晶体。随着CO ₂体积比的增加，监测到更长的熔融和平衡时间，这表明所形成的CO ₂水合物可以更致密和更稳定。此外，更小的CO ₂密度更大水合物离解后会产生气泡，这意味着水相中的CO ₂分子剪切更强烈。从8到22°C较高的离解温度导致较小和更多的气泡形成，而混合速度（60或120 rpm）和样式（全翻转或半翻转）的差异导致对CO ₂水合物形成的影响可忽略离解。对CO _2-水-固体系统的进一步研究将有助于了解在不同的本体和多孔介质条件下CO ₂水合物的形成和离解特征。