Simulation of controlled extraction of methane from submarine gas hydrate reservoirs and CO2 sequestration

A multi-dimensional and time-dependent model was developed to describe hydrate dissociation and formation for simultaneous methane production and CO2 sequestration in submarine hydrate reservoirs. The model describes gas and liquid flow through a submarine sediment partially filled with hydrate under non equilibrium conditions for gas/liquid mass transfer, hydrate formation/dissociation and heat transfer between five coexisting phases. The underlying partial differential equations are discretized in space by finite differences; the resulting system of differential-algebraic equations is solved by a numerical integrator. First simulations were run in a closed rectangular 2D-area for equilibrium approach, methane hydrate dissociation by depressurization and CO2 injection over the area boundary. At present, hydrate formation and dissociation is given by an overall rate equation with liquid phase gas concentrations as linear driving force. In future. more physically based descriptions should be integrated at this point leading to a multiphysics flow model for submarine methane production and CO2 sequestration.