  In this paper, we develop a multiscale finite element method for solving
flows in fractured media. Our approach is based on Generalized Multiscale
Finite Element Method (GMsFEM), where we represent the fracture effects on a
coarse grid via multiscale basis functions. These multiscale basis functions
are constructed in the offline stage via local spectral problems following
GMsFEM. To represent the fractures on the fine grid, we consider two approaches
(1) Discrete Fracture Model (DFM) (2) Embedded Fracture Model (EFM) and their
combination. In DFM, the fractures are resolved via the fine grid, while in EFM
the fracture and the fine grid block interaction is represented as a source
term. In the proposed multiscale method, additional multiscale basis functions
are used to represent the long fractures, while short-size fractures are
collectively represented by a single basis functions. The procedure is
automatically done via local spectral problems. In this regard, our approach
shares common concepts with several approaches proposed in the literature as we
discuss. Numerical results are presented where we demonstrate how one can
adaptively add basis functions in the regions of interest based on error
indicators. We also discuss the use of randomized snapshots
(\cite{randomized2014}) which reduces the offline computational cost.
