Progress and perspectives on pore-scale flow in methane hydrate reservoirs: Microfluidic and numerical strategies for synergistic CH4 recovery and CO2 sequestration.

Natural gas hydrates, widely distributed in marine and permafrost regions, present a dual-function energy resource combining methane extraction with carbon dioxide sequestration, offering a promising pathway toward clean energy production and climate mitigation. However, the complexity of multiphase flow mechanisms within hydrate-bearing reservoirs presents critical challenges to achieving efficient and stable gas recovery and sequestration. This review examines the pivotal role of pore-scale modeling and microfluidic experiments as essential tools for understanding fluid behaviors and interfacial phenomena during hydrate dissociation and replacement. It synthesizes key theoretical frameworks governing gas-water-hydrate three phase flow dynamics and evaluates how these techniques reveal underlying microscopic flow mechanisms and replacement processes. Special emphasis is placed on the interactions between CO2 and hydrate phases, with a focused discussion of their implications for enhancing methane recovery and optimizing carbon sequestration strategies. Finally, the review identifies key challenges in current research, particularly those related to multiphase flow dynamics and reservoir heterogeneity, and outlines future directions to improve the efficiency and predictability of hydrate-based energy production and carbon storage.