Hydro-mechanical modelling of geological CO2 storage and the study of possible caprock fracture mechanisms
Résumé
The present study discusses the results of a large scale finite element modelling of a hypothetical underground carbon dioxide (CO2) storage operation. The hydro-mechanical properties of the materials modelled are chosen to be representative of a potential injection site. For high injection rates, local effective stress modifications may lead to various fracture mechanisms induced by shear or tensile stresses depending on the initial conditions. The results show the influence of the initial stress state on the possible fracture mechanisms. Sustainable injection rate maps are introduced that provide a first order estimate depending on initial stress states. The case of rock fracturing due to tensile stresses is treated. The stress intensity factor is used as the driving parameter describing the growth of initial vertical cracks. A probabilistic model based on rock heterogeneity is used to evaluate the probability of the formation and propagation of crack networks. The results show that a crack network can be generated. This crack network saturates quickly after the first crack activations.
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