Evolution of hydrate habit and formation properties evolution during hydrate phase transition in fractured-porous medium

• Hydrate synthesis and decomposition occur simultaneously throughout phase transition process. growth habit is not monotonous change in fractured-porous medium sandstone at different stages of transition. occurences differs from that porous matrix system. The preferential occurence hydrates fracture leads to significantly permeability changes. Natural gas hydrate, as an efficient clean energy resource, are naturally distributed medium. With the most recent development advanced micro-scale imaging techniques, hydrate habits evolution, occurrences, pore structure evolution well seepage characteristics during hydrate-bearing sediments have been studied extensively scale. However, there few studies on sediment. In this work, xenon experiment by excess-gas method carried out a fractured core with in-situ micro computed tomography (micro-CT) scanning explore physical parameters host results indicate sediment dynamic equilibrium system each moment induced pressure change. occurrences reservoirs include contiguous-sheet, clustered isolated, which slightly formation; contiguous-sheet occurrence dominantly determines sediments. addition, logic diagram for paths presented first time. These findings significant detailed understanding pore-scale distribution process provide theoretical basis precise modeling