Modelling of the permeability evolution of coal due to sorption

Hydro-mechanical couplings in coalbeds are a critical issue for carbon dioxide storage or coalbed methane (CBM) recovery. For instance, coal swells (or shrinks) due to gas sorption (or desorption). Any change of the fractures network likely modifies the permeability of the material.

In many existing CBM models, sorption- and stress-induced coal permeability alteration is a remarkable aspect which is improperly simplified. To take into account properly these phenomena, a microscale model was developed for the modelling of laboratory experiments carried out at the University of Newcastle. The presentation will mainly focus on this model and the modelling of these laboratory experiments. However, a direct modelling approach would be computationally too expensive for the modelling at a reservoir scale. Homogenization techniques have to be employed. An overview of a macroscale and a multi-scale model developed in this purpose will also be briefly presented.