An example of rock fracturing: Geomechanical risks for geological CO2 storage

The mechanical behavior of quasi-brittle materials is of great interest in a wide range of engineering applications. Among them, an increasing attention is paid to damage and fracturing of clay-rich rocks with their implication within environmental and energy applications. Clay-rich rocks have been studied as potential host formations for radioactive waste repository, potential caprock for geological storage of energy vectors (hydrogen, compressed air, mixture of  H2/CH4) and CO2 and the extraction of shale oil and gas.

Some industrial applications will be first presented. A special attention will be payed to the fracture networks formation around underground structures in the context of radioactive waste repository. Different parameters controlling the pattern and the extent of fracture networks will be discussed. A non-local damage model accounting for the rock heterogeneities will be then presented. A Weibull model was used to account for the randomness of crack initiation(s) and then a fracture mechanics based threshold was considered to model crack propagation. The model was then extended to account for hydromechanical couplings. Some perspectives and open problems will be finally discussed.