Effect of Fracture Density on Effective Permeability of Matrix‐Fracture System in Shale Formations

Fractures play an important role in providing preferred flow pathways in low‐permeability shale matrix and significantly enhance its permeability. They can improve gas production for shale gas development but can also increase the risks for leaking of CO₂ or brine from geological storage sites. In this chapter, a generalized lattice Boltzmann (LB) model for fluid flow through porous media is adopted to simulate fluid flow in matrix‐fracture systems and to predict the effective permeability k_eff . Discrete fracture‐matrix networks (DFN) are constructed using line fractures and elliptical fractures in 2D and 3D systems, respectively. Power law relationships are observed between k_eff and fracture density in the DFN. Further, the combined finite discrete element method (FDEM) is adopted to simulate fracture propagation process. Dynamic evolution of k_eff during the propagation is simulated using the LB model. The results show that power law relationship between k_eff and fracture density is also obeyed.