A method for estimating a permeability of an earth formation includes: receiving a discrete fracture network (DFN) of the earth formation; representing the DFN as one or more volume sections, each volume section having a plurality of boundaries; identifying fractures that are connected to each other and lead from a first boundary in the plurality of boundaries to a second boundary in the plurality of boundaries to provide one or more flow paths for each volume section; applying Oda's method to the connected fractures making up the one or more flow paths to estimate the permeability of the earth formation along the one or more flow paths for each volume section to provide a permeability value for each volume section; and performing an action related to the earth formation using the permeability value for each volume section and an apparatus related to the action.