HYDRAULIC FRACTURING: COULOMB FAILURE IN SHALE FRACTURING

The hydraulic fracturing (HF) technique has been widely used for unconventional reservoirs with extremely low permeability. Natural fractures are a ubiquitous feature of unconventional reservoir and due to low matrix permeability, HF generally intersects natural fractures leading to relatively complex geometrical system enables fluid and proppant transportation of shale reservoir. There are several factors influenced the shale reservoir during HF such as in-situ stress regime around the fracture, fracture orientations, fracture density distribution and pore connectivity. The stress state of a poroelastic medium, which entails both normal and shear stress of the rock is influenced by pore fluid diffusion. The coulomb stress changes due to fluid injection changes the pore pressure and hence the stress medium. This paper explains a comprehensive study on coulomb stress failure around the fracture due to HF induced by poroelastic diffusion. This method is implemented on a fractured shale core sample and results have been interpreted in terms of HF effect on coulomb stress failure. © (2021) by the European Association of Geoscientists & Engineers (EAGE)