Natural gas is sourced increasingly from shale reservoirs. Hydraulic fracture stimulation (fracking) is used to access this so-called shale gas cost-effectively. Fracking can reopen pre-existing natural fractures to create paths to the gas held in the shale. Gas then flows back along these paths and can be extracted. Better knowledge of the geometry of natural fractures will allow the design of more efficient hydraulic fracture systems.
Natural fracture networks observed in exposures of exhumed, shale-dominated strata are characterised by curved second-order fractures that connect larger, laterally extensive extension fractures. Our hypothesis is that curved second-order fractures result from static or dynamic perturbations at fracture intersections or during fracture perturbation. This project aims to model natural fracture propagation to test this hypothesis. This modelling will use numerical techniques developed by the Mechanics Research & Teaching Group in the School of Engineering and Computing Sciences at Durham University.