CH4 Mass Conservation Equation
The CH4 mass conservation equations for STOMP-HYDT-KE are shown. These equations equate the time rate of change of CH4 mass within a control volume with the flux of CH4 mass crossing the control volume surface. The conservation equation for mobile CH4 mass includes kinetic exchange of hydrate formers between the mobile (m) and hydrate (h) and gross transport between the mobile and hydrate phase through kinetic hydrate formation:
where, CH4 can exist in the aqueous (l), nonaqueous liquid (n), and gas (g) phases.
The flux of mobile CH4 is a combination of advective and diffusive components:
where V is the Darcy velocity.
Diffusive fluxes of CH4 through the mobile phases are computed from gradients in molar concentration, considering molecular diffusion, but ignoring hydraulic dispersion;
where a combined diffusion-dispersion coefficient, D, replaces the classical Fickian diffusion coefficient.
The conservation equation for hydrate CH4 mass includes kinetic exchange of hydrate formers between the mobile (m) and hydrate (h) and gross transport between the mobile and hydrate phase through kinetic hydrate formation:
