Modeling the dissociation of carbon dioxide and methane hydrate using the phase field theory

Abstract

Hydrate that is exposed to fluid phases which are undersaturated with respect to equilibrium with the hydrate will dissociate due to gradients in chemical potential. Kinetic rates of methane hydrate dissociation towards pure water and seawater is important relative to hydrate reservoirs that are partly exposed towards the ocean floor. Corresponding results for carbon dioxide hydrate is important relative to hydrate sealing effects related to storage of carbon dioxide in cold aquifers. In this work we apply a phase field theory to the prediction of carbon dioxide hydrate and methane hydrate dissociation towards pure water at various conditions, some of which are inside and some which are outside the stability regions of the hydrates with respect to temperature and pressure. As expected from the differences in water solubility the methane hydrate dissolves significantly slower towards pure water than carbon dioxide hydrate.