Permeability prediction in hydrate-bearing sediments via pore network modeling

Natural gas hydrates in marine sediments undergo phase transitions under non-equilibrium conditions, making it challenging to accurately measure the permeability characteristics of hydrate-bearing sediments using experimental methods. In this study, pore network modeling is utilized to simulate the hydrate formation process and investigate the single-phase and two-phase permeability of hydrate-bearing sediments, and a comparative analysis was performed on consolidated and unconsolidated sediment samples. The results revealed the evolution of effective permeability as a function of hydrate saturation, and quantitative relationships were observed for the water retention curves and gas-water relative permeability, emphasizing the influence of pore structure and hydrate distribution on flow behavior. On the basis of the simulation results, predictive methods for irreducible water saturation, maximum water saturation, and key parameters in the van Genuchten and Brooks-Corey models for hydrate-bearing sediments are proposed. The findings provide deeper insights into gas-water flow dynamics in hydrate-bearing sediments and offer valuable guidance for hydrate resource exploitation, the assessment of environmental risks associated with hydrate dissociation, and the evaluation of carbon sequestration potential.