Fluid flow pathways in shales: Damage induced permeability change

Shale reservoir potential is largely determined by the connected pore network in the rock and the connection between the pore network and the naturally present or mechanically induced fracture network. These together determine the total permeability of the rock. We have used a number of different techniques to investigate the microstructure and permeability of Early Jurassic Shales from the UK (Whitby mudstone) when intact and with a mechanical induced fracture network. Permeability changes in the shales due to mechanically induced fractures are not straightforward, depending on the bedding orientation with respect to fluid flow and bedding orientation with respect to induced fractures permeability of the samples either increase by orders of magnitude, increase slightly or are very similar before and after fracturing.