Hydro-mechanical modelling of multiphase flow in naturally fractured coalbeds applied to CBM recovery or CO₂ storage

This thesis is dedicated to the modelling of multiphase flows in naturally fractured rocks and, in particular, to the recovery of methane, or reversely to the storage of carbon dioxide, in coalbeds. In this context, some hydro-mechanical couplings can likely affect the permeability of the reservoir. On the one hand, the increase in effective stress after the reservoir depletion tends to decrease the permeability. On the other hand, the matrix shrinkage following gas desorption tends to increase the permeability. These phenomena are highlighted with some experimental tests carried out in laboratory. Some numerical models are developed in this thesis to properly take into account the permeability evolution during the gas production/storage. As coal is rarely dry in situ, constitutive models are developed for unsaturated conditions. These models are implemented in the finite element code Lagamine.