  In this paper we carry out numerical analysis for a family of simplified gas
transport models with hydrate formation and dissociation in subsurface, in
equilibrium and non-equilibrium conditions. These models are adequate for
simulation of hydrate phase change at basin and at shorter time scales, but the
analysis does not account directly for the related effects of evolving
hydraulic properties.
  To our knowledge this is the first analysis of such a model. It is carried
out for the transport steps while keeping the pressure solution fixed. We frame
the transport model as conservation law with a non-smooth space-dependent flux
function; the kinetic model approximates this equilibrium. We prove weak
stability of the upwind scheme applied to the regularized conservation law. We
illustrate the model, confirm convergence with numerical simulations, and
illustrate its use for some relevant equilibrium and non-equilibrium scenarios.
