ABSTRACT
Recent innovations in the field of oil recovery have led to a renewed interest in three-phase relative permeability. Three-phase flow occurs when the water saturation is higher than the irreducible level, and oil and gas are also present as mobile phases. All factors which influence flow in systems containing two mobile phases also apply to three-phase systems. Virtually all oil reservoirs constitute potential three-phase systems, since reservoir rocks invariably contain interstitial water, and naturally occurring oils completely devoid of gas are rare. Much of the credit for the classical work in three-phase relative permeability is accorded to Leverett and Lewis who were the first to measure three-phase relative permeability of a water-oil-gas system in an unconsolidated sand. An extension of Welge's two-phase unsteady-state technique was used by Donaldson and Dean to determine three-phase relative permeabilities of Berea sandstone and Arbuckle limestone.
