Coupled multiphysics modeling of gas hydrate bearing sediments

Gas hydrates are crystalline clathrate compounds made of water and a low molecular gas like methane (Sloan 1998). Gas hydrates are generally present in oil-producing areas and in permafrost regions. Methane hydrate deposits can lead to large-scale submarine slope failures, blowouts, platform foundation failures, and -borehole instability. Gas hydrates constitute also an attractive source of energy as they are estimated to contain very large reserves of methane. Hydrate formation, dissociation, and methane production from hydrate bearing sediments are coupled Thermo-Hydro-Mechanical and Chemical (THMC) processes that involve, for example, exothermic formation and endothermic dissociation of hydrate and ice phases, mixed fluid flow, and large changes in fluid pressure. A fully coupled formulation developed by the authors is used in the numerical simulations presented in this article. The main balance equations of the proposed formulations are: momentum balance, mass balance of species, and energy balance equations. Others key components of the approach are constitutive equations and equilibrium restrictions. Simulation results conducted for hydrate bearing sediments subjected to boundary conditions highlight the complex interaction among THMC processes in hydrate bearing sediments