Permeability investigation and hydrate migration of hydrate?bearing silty sands and silt

Permeability is a crucial parameter to evaluate the recovery and separation of natural gas from hydrate reservoirs. In this work, the water effective and relative permeability (kw and krw) of silty sands and silt with different hydrate saturation (SH) was supplemented. Experimental results showed that the differential pressure changes of sediments during the permeability measurement were diverse. It was necessary to record the complete differential pressure process and find the stable stage of pressure difference. The decrease of dissolved methane in water would bring about the dissociation of hydrate, which led to the formation of flow channel in the sediment. The effect of SH on kw was very obvious even if the SH was at a relatively low level. The effect of SH lower and greater than about 5% on krw was different, and SH had more obvious effect on krw of silt than that of silty sands. The migration behavior of hydrate was discussed in the simple cubic model, and hydrate migration might be the main factor causing the seriously effect of low SH on kw, and the different effect of SH lower and greater than about 5% on krw. Moreover, for the porous media with particle size lower than silt, the method of steady?state water injection was no longer recommended.