Phase transition and gas migration channels evolutions with methane hydrate system in porous media under dynamic leakage conditions

Abstract

Methane, which is widely present in marine sediments, is not only a potential transitional energy source but also plays a critical role in the global carbon cycle. However, in–depth research on the hydrate phase transition and its effects in porous media under dynamic leakage conditions is still lacking. In this study, X-ray computed tomography was employed to capture the real–time three–dimensional structural evolution of hydrate phase transition. The results indicate that hydrate formation expands and stabilizes gas migration channels, increasing their volume to 6.9 times the original, while also enhancing structural complexity and system permeability. During hydrate dissociation, the combined effects of gravity and released gas and water altered the distribution of gas migration channels, reducing both their volume and permeability. On this basis, the ecological and environmental impacts of hydrate phase transition on the deep–sea methane seepage areas under dynamic seepage conditions were analyzed. Hydrate phase transition playing a crucial role in the biogeochemical processes and the evolution of benthic ecological communities in methane seepage areas. This study demonstrates the role of hydrate phase transitions in reshaping gas migration channels under dynamic leakage, with implications for ecological processes and hydrate resource development in marine sediments.