Water retention curve for hydrate-bearing sediments

The water retention curve plays a central role in numerical algorithms that model hydrate dissociation in sediments. The determination of the water retention curve for hydrate-bearing sediments faces experimental difficulties, and most studies assume constant water retention curves regardless of hydrate saturation. This study employs network model simulation to investigate the water retention curve for hydrate-bearing sediments. Results show that (1) hydrate in pores shifts the curve to higher capillary pressures and the air entry pressure increases as a power function of hydrate saturation; (2) the air entry pressure is lower in sediments with patchy rather than distributed hydrate, with higher pore size variation and pore connectivity or with lower specimen slenderness along the flow direction; and (3) smaller specimens render higher variance in computed water retention curves, especially at high water saturation S _w > 0.7. Results are relevant to other sediment pore processes such as bioclogging and mineral precipitation. Key Points Network modeling of the water retention curve for hydrate-bearing sediments Effects of pore and hydrate characteristics on water retention curves Specimen size and geometry may bias measured water retention curves