Pore-scale analysis of hydrate saturation on the physical parameters of hydrate-bearing sediment with different particle shapes

Methane hydrate is the most potential novel energy source with huge reserves to be developed, and is the priority of countries' future energy development strategies. Evaluating the basic physical characteristics of hydrate reservoirs, especially permeability, thermal, and electrical conductivity, is essential for clarifying the main controlling factors of physical characteristics and formulating a reasonable development strategy. Accordingly, 16 cementing hydrate-bearing models with different particle shapes were constructed account of a new three dimensions morphologic modeling algorithm for hydrate in this study. Based on the above models, the evolution of pore space distribution and basic physical properties of hydrate-bearing sediments (HBS) have been analyzed via pore network modeling (PNM) and finite volume method (FVM). The results show that (1) the quantity of pores and throats of HBS with round particles is higher, and the average radius is smaller than those of HBS with irregular particles, (2) increasing hydrate saturation leads to a decrease in absolute permeability, with a more rapid decrease in permeability for HBS with irregular particles, (3) the thermal conductivity of HBS with round particles exceeds those of HBS with irregular particles, and the their curves remain parallel with increasing hydrate saturation, (4) the resistivity index of HBS with round particles increases faster as hydrate forms, and the conductivity is always smaller than those of HBS with irregular particles.