Formation kinetics of s-II gas hydrates in simulated marine sediments: Effects of pore structure and marine soil content

To reveal the regulation mechanism of porous media structure and mineral components in marine sediments on the formation kinetics of structure-II (s-II) gas hydrates, this study investigated the regulatory effects of porous media structure and marine soil content on structure-II (s-II) gas hydrate formation kinetics. Porous media models with different glass sand particle sizes were built, and experiments were conducted via constant-volume cooling in a high-pressure visual reactor. Results showed that medium sand achieved the optimal balance with the shortest induction time (76 min) and 18.59% gas conversion rate, while fine sand had the highest conversion rate (20.2%) but a longer induction time (230 min). Adding marine soil significantly promoted hydrate formation: 1% marine soil minimized induction time (61 min), and 5% maximized conversion rate (23.75%). Marine soil promotes nucleation by providing sites, improving wettability, and optimizing gas-water distribution, though excessive content weakens this effect. This work provides experimental support for marine hydrate accumulation analysis and efficient exploitation technologies.