Chapter 5 - Percolation Behaviour of Fracture Networks

Abstract

In this chapter, a series of two-dimensional simulations based on four groups of fracture patterns is used to investigate the connectivity of fractures with increasing fracture density. The relationship of fracture connectivity to a range of parameters such as fracture density, length, orientation, and architecture is also explored in the chapter. Fracture density appears to be the most important factor in controlling connectivity where fracture length is relatively small in relation to the region of interest. A power law is characterized by a critical fracture density and an exponent and is used to describe the relationship between connectivity and fracture density. These relationships are tested for 15 natural fracture networks. Distinct element (DE) methods are used to model the deformation and permeability of the simulated fracture networks at different stages of connectivity. The connectivity can be assessed from the fracture density and hence the deformation and permeability of a fractured rock can be predicted. The connectivity has an important effect on deformation and permeability; both increase at the percolation threshold.