A review of multiscale mechanics and pore-scale flow in natural gas hydrate-bearing sediments

Natural gas hydrates, as a promising clean energy resource with abundant reserves, face critical challenges in commercial exploitation due to thermal–hydraulic–mechanical (THM) coupling effects and formation stability concerns. This paper reviews recent advances in multiscale investigations of hydrate-bearing sediments, focusing on their mechanical responses and fluid-flow behaviour within porous media. Key challenges include: maintaining the integrity of core samples during recovery; limitations in pore-scale imaging and simulation caused by sample accessibility and computational constraints; complex fluid-flow mechanisms in clay-rich and silty layers; and uncertainties associated with boundary conditions and phase-change simplifications in coupled THM simulations. To address these issues, a multiscale research framework is recommended – integrating high-resolution imaging with molecular dynamics simulations, standardizing high-pressure in situ core sampling and permeability testing procedures, and exploring reservoir–wellbore interaction and failure mechanisms. Future research should prioritize breakthroughs in microstructural characterization, scale-bridging constitutive modelling, and multiphysics coupling techniques to support the safe and efficient development of gas hydrate resources.