Fracture Mechanisms in Organic-Rich Shales: Role of Kerogen

In this work we study role of kerogen in the fracture properties of organic-rich shales and, in particular, in the ductility of shales. The presence of kerogen and clays in shale is known to increase the ductility. We propose here a multiscale approach to develop a fine understanding of shale ductility from the molecular scale. We develop and validate a methodology at the molecular scale that can capture the toughness and ductility of a material. We apply this methodology successfully to a silica polymorph and to a kerogen analog, and we confirm the significant ductility of kerogen. Interestingly the silica-kerogen interface exhibits a similar ductility, which is central for the properties of the heterogeneous shale. Finally, we consider a tentative upscaling considering the pull out phenomenon as a likely mechanism of fracture of the shale.