Permeability of hydrate-bearing sediments

Natural gas hydrate is one of the most potential carbon energy resources because of its tremendous reserves. Gas and water permeability of natural gas hydrate-bearing sediments (HBS) directly affects gas recovery from hydrate reservoirs and gas production efficiency. In this paper, we review the permeability of HBS with respect to its relevant factors and development in characterization. Hydrate morphology and distribution inherently affect the permeability, and are identified in both coarse- and fine-grained sediments. Measurement and estimation methods of permeability are discussed in four aspects: theoretical analysis and numerical simulation, laboratory experiment, and filed test. Research challenges to this subject are comprehensively discussed, and future prospects of research are addressed. We suggest that future research should focus on understanding hydrate formation and dissociation mechanism and their effect on the permeability in fine-grained sediments, obtaining reliable measurement results of the permeability, bridging the gap of permeability between laboratory samples and natural sediments, and highlighting multi-scale analysis on the permeability with appropriate parameters as well as developing models for safe and economically feasible gas production from HBS eventually.