Gas hydrate: Methane-hydrate-bearing models based on the apparent permeability and apparent pore-size distribution of artificial and natural methane-hydrate-bearing sediment

In order to clarify the relation between permeability and these properties, the permeability, grain-size distribution, porosity, pore-size distribution, and surface-to-volume ratio of glass beads and sandy sediments have been measured. A semi-empirical (SE) equation for the permeability of glass beads and sandy sediment has been derived based on the Kozeny-Carman equation using pore-size distribution and porosity measured by mercury porosimetry. This SE equation has been approximated by the relation of the porosity, pore-size distribution, tortuosity, and surface-to-volume ratio of the sediment. The permeabilities calculated by the SE equation correspond well to the permeability measured by water flow. Furthermore, techniques for converting NMR-T ₂ distribution developed in our previous work were applied in order to obtain the pore-size distribution with higher spatial resolution.