Deep sea NMR: Methane hydrate growth habit in porous media and its relationship to hydraulic permeability, deposit accumulation, and submarine slope stability

We apply the lattice-Boltzmann method to simulate fluid flow and dissolution and precipitation in the reactive solid phase in a porous medium. Both convection and diffusion as well as temporal geometrical changes in the pore space are taken into account. The numerical results show that at high Peclet and Peclet-Damkohler numbers, a wormhole is formed and permeability increases greatly because of the dissolution process. At low Peclet and high Peclet-Damkohler numbers, reactions mainly occur at the inlet boundary, resulting in the face dissolution and the slowest increase of the permeability in the dissolution process. At moderate Peclet and Peclet-Damkohler numbers, reactions are generally nonuniform, with more in the upstream and less in the downstream. At very small Peclet-Damkohler number, dissolution or precipitation is highly uniform, and these two processes can be approximately reversed by each other. These numerical examples have not been yet confirmed by physical experimentation. Nevertheless, we believe that these simulation results can serve to estimate the effects of dissolution and precipitation during reactive fluid flow.