Strength And Deformation Behaviors Of Methane Hydrate-Bearing Marine Sediments In The South China Sea During Depressurization

Investigating the mechanical behaviors of hydrate-bearing marine sediments can provide the basis for predicting the risks of silty reservoirs due to large-scale hydrate production, which are located in the South China Sea and contain huge hydrate reserves. To this end, hydrate-bearing marine sediments were remolded by the hydrate cores drilled from the South China Sea using the excess water method, and a series of triaxial tests with or without depressurization were conducted on these materials. The initial study shows that the hydrate obviously strengthens the strength and modulus of marine sediments, while the cement strength of the hydrate may depend on its cementing morphology content. No collapse occurs on this material during the depressurization even when the axial load reaches 90% peak strength of hydrate-bearing marine sediments, while serious deformations are observed and dominated mainly by the effective stress. The initial hydrate saturation plays a vital role in the deformation proportion of marine sediments induced by dissociation, while the stress also shows a certain impact during hydrate production. These results support the basic theory for hydrate production of silty reservoirs.