Controlled Lab-Scale Evaluation of the Secondary Permeability Represented in a 3D Printed Discrete Fracture Network (DFN) Model

The evaluation of fluid flow through fractured media is essential for many applications. In hard rocks, fluid flow depends on fracture aperture and connectivity, as fractures are the preferential flow paths within the rock mass. Previous research studied fluid flow, using Discrete Fracture Networks (DFN) and numerical modelling methods, with fewer lab-scale experiments. Advancements in 3D printing technology allows for generating valuable lab-scale physical models representing fractured media. In this work, a DFN model is built using the DFN software MoFrac and a 3D physical model is generated with a 3D printer. The 3D printed DFN model is fixed in an experimental set-up, which functions as a differential pressure meter by restricting airflow through a transition duct. The objectives of the experiment are to establish the behavior of the changing pressure to fluid flow through fractures. This laboratory experiment is part of an ongoing research project investigating the constructability of a Natural Heat Exchange Engineering Technology system. This system uses natural means to provide economically significant thermal regeneration capacity through a volume of rocks for ventilating mine workings. The major contribution of the lab-scale experiment is to verify whether the secondary permeability of a rockmass can admit sufficient flow.