Theory of Waterflooding in Fractured Reservoirs

This study presents a new theory of the incompressible flow of 2 fluids, water-displacing oil, in a fractured porous material composed by 2 distinct media; matrix blocks of low transmissibility embedded in a highly transmissible medium. This general description includes heterogeneous porous media not necessarily of the fractured type. The theory accounts for an important fact not considered in former models found in the literature; the blocks down- stream in a reservoir subject to waterflood are exposed to a varying water saturation resulting from the water imbibition of the upstream blocks. Expressions for the water-oil ratio and the cumulative oil production are derived, allowing a complete economic evaluation of a fractured reservoir waterflood project. Comparison of experimental curves reported in the literature and curves obtained using this theory show a good fit.