Over 90% of hydrate reserves are located in marine reservoirs, particularly in low-permeability silty-clayey sediments in the South China Sea (SCS). Understanding the water seepage characteristics of these sediments is vital for the commercial exploitation of hydrates in the region. In this study, a customized experimental platform was used to prepare hydrate-bearing silty-clayey sediments, and steady-state water seepage experiments were conducted under varying hydrate saturation and sediment porosity conditions. Results show that the minimum hydraulic gradient increases with hydrate saturation below 5% but decreases above this threshold. Non-Darcy flow occurs below a hydraulic gradient of 15 × 105, while Darcy flow prevails above it. Permeability initially decreases and then increases with hydrate saturation. For sediments with a porosity of 45%, permeability is reduced to a minimum at a hydrate saturation of 3% and is subsequently increased. Permeability increases significantly with porosity, rising by 140% when porosity increases from 40% to 50% at 20% hydrate saturation. Factors such as the pore state, hydrate blockage, cementation, and preferential flow channels influence permeability. This study provides theoretical support for understanding water seepage in marine hydrate reservoirs.
Luo et al. (Thu,) studied this question.