Efficient finite-difference model for flow in a reservoir with multiple length-scale fractures

In this paper we describe a hierarchical approach for modeling fluid flow i n a naturally fractured reservoir with multiple length-scale fractures. Bas ed on fracture length relative to the finite difference grid size, fracture s are classified as short disconnected fractures, medium-length fractures, and long fractures. Effective gr id-block permeabilities, associated with t he short- and medium-length fractures, are used as input to a finite-differ ence simulator. We also present a separate transport equation for flow thro ugh long fractures to capture effects of large-scale high permeability path ways. Simulation results from the new hierarchical approach are compared wi th those from the conventional dual porosity/permeability model.