In-situ observation and mechanistic investigation of bubble-size effects on gas hydrate formation and dissociation at the pore scale
Abstract
Natural gas hydrates represent a promising clean energy resource, whose multiphase evolution in subsea sediments, especially in association with seafloor gas seepage and bubble formation, remains poorly understood at the pore scale. To address this gap, this study aimed to quantitatively investigate how bubble size modulates the kinetics of hydrate formation and dissociation by employing high-pressure microfluidics under seafloor reservoir-relevant thermodynamic conditions. In-situ visualization uncovered a two-stage formation mechanism around gas bubbles: Rapid hydrate shell formation followed by gradual shell densification. The shell formation was found to be governed by local gas concentration gradients and exhibited a "chain induction" effect between adjacent bubbles, while the densification duration scaled linearly with bubble size. Likewise, hydrate dissociation was shown to follow a two-stage pathway: The internal hydrate dissociates rapidly in the initial stage, after which the remaining hydrate dissociates much more slowly because the intact dense outer shell restricts outward gas diffusion and internal pressure buildup weakens the thermodynamic driving force. These findings reveal the bubble-size-regulated pore-scale mechanism, providing a kinetic foundation for the dynamic optimization of natural gas hydrate exploitation.
Document Type: Original article
Cited as: Wen, L., Li, C., Zhang, R., Yu, Y., Deng, Y., Lu, H. In-situ observation and mechanistic investigation of bubble-size effects on gas hydrate formation and dissociation at the pore scale. Advances in Geo-Energy Research, 2026, 21(3): 283-296. https://doi.org/10.46690/ager.2026.09.07
DOI:
https://doi.org/10.46690/ager.2026.09.07Keywords:
Microfluidic chip, natural gas hydrate, gas bubbles, bubble-size regulation, Hydrate formation and dissociationReferences
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