Influence of bubble seepage on methane gas production and pore pressure evolution during hydrate dissociation in marine sediments
Influence of bubble seepage on methane gas production and pore pressure evolution during hydrate dissociation in marine sediments
Natural gas hydrates are widely distributed in marine sediments and are considered as a promising unconventional energy resource. The characterization of liquid-gas flow during hydrate dissociation plays a critical role in assessing both the hydrate exploitation efficiency and the reservoir geomechanical responses. In this work, the gas seepage in the forms of isolated bubbles, connected gas, their combinations, and the transitions among them were governed by a newly proposed gas relative permeability function. A multi-phase and multi-field coupled model was accordingly developed and validated based on existing unit tests of gas percolation and hydrate deposit dissociation. Following, the impacts of isolated bubble seepage during hydrate dissociation were preliminarily investigated. Results indicate that the isolated methane gas bubbles delayed the occurrence of peak gas production rate and facilitated the localized excess pore pressure accumulation during the initial stage of hydrate dissociation. Upon reaching the critical gas saturation, the gas phase started to evolve from isolated bubbles to connected gas, leading to a sharp increase in gas relative permeability and a rapid release of accumulated gas. This model provides a theoretical basis and numerical method for evaluating the gas migration under extremely low gas saturation, as well as the exploitation of marine hydrate deposits.
P. Wang; Lujun Wang; Z. Ye; Bin Zhu; Yunmin Chen
11th International Conference on Physical Modelling in Geotechnics (ICPMG2026)
Session 2: Scaling laws and fundamentals
https://doi.org/10.53243/ICPMG2026-148