Impact of multi-set fracture pattern on the effective permeability of fractured porous media

In fractured porous media, a significant contribution to flow is made through fracture–matrix networks. These networks create flow channels which play an important role in overall fluid transport. Previous fracture simulation studies were mostly done with stochastic patterns. In contrast, the analysis of geomechanically generated discrete fracture data sets that closely render naturally occurring systems, whilst account for flow through matrix and fractures simultaneously was presented in this study. The used propagation algorithm provides similar results to physical experiments. The impact of multiple superposed fracture sets within geological formations, created by multiple deformation events, on the effective permeability has been analysed. A 2D fracture-matrix medium was simulated and effective permeability computed using a finite element based method. Specifically, the impact of certain detailed fracture characteristics, such as density, mean length, spacing, connectivity and matrix permeability on the flow was measured. Results indicated the increase of effective permeability in multiple-sets of fracture sets. Fractures superimposed at different angles to the main set, parallel to the flow, increase connectivity between main flowlines and neighbouring fracture clusters. Thus, an increase in connectivity leads to higher effective permeability of media and increased probability of percolation. Permeability anisotropy was also analysed in this study. An expression for the characterisation of anisotropic effective permeability was proposed and simulated permeability was compared to analytical predictions.