An Adaptive Method for Flow Simulation in Three-Dimensional Heterogeneous Discrete Fracture Networks

Natural fractured media are highly unpredictable because of existing complex structures at the fracture and at the network levels. Fractures are by themselves heterogeneous objects of broadly distributed sizes, shapes and orientations that are interconnected in large correlated networks. With little field data and evidence, numerical modeling can provide important information on the underground transport phenomena. However it must overcome several barriers. Firstly, the complex network structure produces a structure difficult to mesh. Secondly, the absence of a priori homogenization scale, along with the double fracture and network heterogeneity levels, requires the calculation of large but finely resolved fracture networks resulting in very large simulation domains. To tackle these two related issues, we reduce the high complex geometry of the fractures by applying a local transformation that suppresses the cumbersome meshing configurations while keeping the networks fundamental, geological and geometrical characteristics. We show that the flow properties are marginally affected while the problem complexity (i.e., memory capacity and resolution time) can be divided by orders of magnitude. To conclude, the developed method represents an adaptive method of the complex configurations.