A small pore size effect on dissociation behavior of gas hydrates in fine-grained sediments

摘要

As capillarity in small pores is known to affect dissociation of gas hydrates, the dissociationrnbehavior of gas hydrates in fine-grained sediments need to be clearly understood for successful practices ofrnresource recovery. Therefore, this study investigated the dissociation behavior of gas hydrates in different sizedrnpores of host sediments. Gas hydrates were synthesized from a partially water-saturated conditions in a sandrnsample and a natural fine-grained sediment sample cored from Ulleung Basin (UB), offshore Korea, and thesernhydrates were thermally dissociated under a constant volume condition while monitoring the pressure andrntemperature. The dissociation of gas hydrate in the fine-grained sediments occurred at the lower temperaturernthan the bulk equilibrium by ∼1.5◦C. When compared with the pore size distribution obtained by the mercuryrnintrusion porosimetry, gas hydrate was preferentially formed in small pores for a given range due to the initialrnwater locations in partially water-saturated conditions.