Multiscale mimetic method for two-phase flow in fractured media using embedded discrete fracture model

•The presented multiscale method could avoid the complicated unstructured grid generation and computing process.•The presented formulation can generate accurate results on the fine-scale grid with very high computational efficiency.•Our multiscale method could produce conservative velocity fields which are necessary for flow simulation.•This multiscale method is not only easy to compute fine-scale solutions but also more flexible for complex grid geometry. A multiscale mimetic method is developed for the simulation of multiphase flow in fractured porous media in the context of an embedded discrete fracture model (EDFM). The EDFM constructs independent grids for matrix and fracture system. Therefore, it is an efficient and practical flow model as it avoids the complicated unstructured grid subdivision and computing process. In order to extend the EDFM to field-scale applications, we integrate EDFM into a multiscale mimetic method. In this work, we use the multiscale basis functions to capture the detailed interactions between the fractures and the background. The multiscale basis functions are calculated numerically by solving EDFM on the local fine-grid with mimetic finite difference (MFD) method. The MFD method is conservative and robust, which makes it possible to deal with highly complex grid systems. Through combination of multiscale mimetic method and EDFM, this formulation can generate accurate velocity field and pressure field on the fine-scale grid more efficiently than the traditional methods. Numerical results are presented for verification of this multiscale mimetic approach for embedded discrete fracture media, and demonstrate its computational efficiency. The results show that this method is an accurate and efficient method for flow simulation in real-field fractured heterogeneous reservoirs.