Parametric study of methane hydrate dissociation in oceanic sediments driven by thermal stimulation

Abstract

We examine methane hydrate dissociation in porous media that is caused by thermal stimulation of the system (e.g. steam or hot water injection). We consider a semi-analytical model of the problem based on local equilibrium and build upon previous studies in order to obtain further insight on the effects of various parameters that can affect methane production. While previous studies have focused on porous media with properties corresponding to permafrost regions, the overall amount of hydrates in oceanic sediments is believed to be significantly high as well. Therefore, it is essential to examine the effect of oceanic sediments on methane production, since pore-size distributions, permeabilities and porosities of oceanic sediments can be significantly different from permafrost sediments. Parameters to be examined include among others: permeability, porosity, and thermodynamic/transport properties of the system. Study of such issues is of significant importance because it can delineate the possible range of parameters where methane production can be economically viable. It is demonstrated in this work, in contrast to previous studies on permafrost, that for the case of oceanic sediments (low permeabilities), the rate of hydrate dissociation depends on the permeability of the porous sediments. It is demonstrated that at low permeabilities corresponding to oceanic sediments extremely high dissociation pressures develop at the hydrate dissociation front that would result in fracturing of the hydrate-sediment and lead to break down of the model.