ABSTRACT
To understand the different mechanisms of enhanced oil recovery, it is very important to know the displacement mechanisms, either by miscible or by immiscible fluids. Considering the influencing factors and basic assumptions of multiphase fluid flow through porous media with its application to two-phase immiscible fluids, the chapter describes fractional flow and the Buckley-Leverett equation for the displacement of oil by water in a one-dimensional system. Welge method is introduced to overcome the limitation of the Buckley-Leverett equation in describing the water-swept reservoir as well as flood front in determining the recovery. The chapter also elaborates on the importance of proper distribution of injection and production wells in the maintenance of the pressure of the reservoir and waterflooding to achieve uniform and balanced displacement of oil throughout the field. Finally, the definition and the factors affecting macroscopic efficiency and microscopic displacement efficiency are discussed.
