The water permeability of methane hydrate (MH) sediments in distilled water increased somewhat with elapsed time under stable pressure and temperature conditions due to MH dissociation by the distilled water. The apparent water permeability increased with fluctuation under MH dissociation pressure and temperature conditions as a result of resistance against water flow caused by methane gas due to dissociation of the MH. The apparent water permeability gradually increased to absolute permeability, without gas and MH, after dissociation of MH in the sediment due to residual gas caused by the MH dissociation. Permeability measurements of MH sediments for methanol, surfactant (sodium dodecyl sulfate, SDS), and antifoaming agent solutions were examined under MH stable conditions and dissociation pressure and temperature conditions to increase the water permeability of MH sediment. Permeability increased under stable MH pressure and temperature conditions after the flow liquid was changed from distilled water to methanol and antifoaming solutions. However, permeability of the surfactant decreased after a change in the flow liquid from distilled water to surfactant solution. The permeability subsequently increased slowly with elapsed time. The permeability measured for each solution varied with the MH dissociation pressure and temperature conditions. Permeability of the methanol solution gradually increased with dissociation of the methane hydrate, but it took a long time to achieve absolute permeability because of residual gas due to methane hydrate dissociation. Permeability in the surfactant solution increased with fluctuation because gas bubbles formed in the pores. The permeability increased with dissociation of the methane hydrate when an antifoaming agent solution flowed in the sediment. Furthermore, the apparent permeability increased to absolute permeability when gas bubbles generated by methane hydrate dissociation dispersed and/or dissolved into the solution.


The Methane hydrate deposited in sea floor sediments and permafrost is a potential unconventional methane resource.

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