A Simplified Equivalent Pipe Network Approach To Model Flow Through Fractured Porous Rocks

Assessment of flow through fractured porous rock masses is a common problem in many engineering applications including hydrogeology, in-situ mineral recovery, hydro-geothermal resources, mining and oil and gas extraction. In all these applications, flow through the fracture network within the rock mass is, in general, dominant but the contribution to the overall flow from the flow through the intact rock will increase as the permeability of the intact rock increases. Therefore, in general, flow through both the fracture network and the porous rock must be considered simultaneously in order to derive a realistic flow model. The most common numerical approach to solving this problem is to use the dual permeability model in which the fracture network and porous rock are treated as two separate permeable media interacting by means of an exchange term between them. In this approach, the fracture network is usually grossly over-simplified, and the connectivity of the fractures is not directly considered in establishing the dual permeability model. In this work, we present a simple equivalent pipe network approach which solves the problem by considering the connectivity of the fracture network whilst, at the same time, taking into account the permeable nature of the intact rock. The proposed method has the additional benefit of reducing computing costs. A simple example is used to demonstrate the application of the proposed approach.