A hybrid-dimensional discrete fracture model for non-isothermal two-phase flow in fractured porous media

Abstract

We present a hybrid-dimensional numerical model for non-isothermal two-phase flow in fractured porous media, in which the fractures are modeled as entities of codimension one embedded in a bulk domain. Potential fields of applications of the model could be radioactive waste disposal or geothermal energy production scenarios in which a two-phase flow regime develops or where $$\hbox {CO}_2$$ is used as working fluid. We test the method on synthetic test cases involving compressible fluids and strongly heterogeneous, full tensor permeability fields by comparison with a reference solution obtained from an equi-dimensional discretization of the domain. The results reveal that especially for the case of a highly conductive fracture, the results are in good agreement with the reference. While the model qualitatively captures the involved phenomena also for the case of a fracture acting as both hydraulic and capillary barrier, it introduces larger errors than in the highly-conductive fracture case, which can be attributed to the lower-dimensional treatment of the fracture. Finally, we apply the method to a three-dimensional showcase that resembles setups for the determination of upscaled parameters of fractured blocks.