Fractures or cracks affect the movement of fluids in petroleum reservoirs.Fracture orientations reflect the histories of stresses acting upon reservoirs.In moderate to deep reservoirs,many fractures are vertically oriented with horizontal widths.To describe fluid flow effects in vertical fractures,oil and brine permeability and relative permeability functions were measured in vertically oriented,smooth-walled plastic fracture cells.While the cells did not mimic all features of fractured rock,they were simple to use and instrumental in isolating effects of fracture widths on oil-brine relative permeability functions.Experiments were performed with both wide(787 μm)and narrow(51 μm)fractures.Fracture widths and saturation distributions during flow tests were measured using an X-ray scanner.From fracture cell measurements,single phase permeabilities agreed well with permeabilities predicted from the literature.In the wide fracture,oil and brine relative permeability versus saturation functions were greatly influenced by the densities of the fluids as well as flow directions.In the narrow fracture,relative permeabilities were found to be simple functions of fluid saturations and agreed well with results from the literature.
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