Gas hydrate dissociation structures in clay slopes

Abstract

Dissociation of gas hydrates releases large quantities of water and methane gas, which, depending on the host sediment can cause increased pore pressures, volumetric expansion, and/or fluid escape structures, all which have the effect of reducing the sediment stability. To further our understanding of the interaction between gas released during dissociation and the sediment that contains the hydrates, small scale physical models, using synthetic materials that enabled the dissociation process to be captured by high speed cameras, as well as a calibrated and verified finite element model were created. The results of the investigation show that slope angle affects the orientation of the fluid escape structures, depth of burial of the hydrate and a stiff overburden affect the amount of gas required for escape to occur and the violence of escape. Thin hydrate sheets cause the most cavity inflation and multiple hydrate nodules influence the orientation of the surface deformation.