Petroleum reservoirs waterflooding

In this chapter, in an attempt to devise methods for helping to foresee such unfavorable consequences, we construct models of the chemical interactions between injected fluids and the sediments and formation waters in petroleum reservoirs. We consider two cases the effects of using seawater as a waterflood, taking oil fields of the North Sea as an example, and the potential consequences of using alkali flooding (i.e., the injection of a strong caustic solution) in order to increase oil production from a clastic reservoir. 

Below the bubble-point, pressure gas percolates out of the oil phase, coalesces and displaces the crude oil. The gas phase, which is much less viscous and thus more mobile than the oil phase, fingers through the displaced oil phase. In the absence of external forces, the primary depletion inefficiently produces only 10 to 30 percent of the original oil in place. In the secondary stage of production, water is usually injected to overcome the viscous resistance of the crude at a predetermined economic limit of the primary depletion drive. The low displacement efficiencies, 30 to 50 percent, of secondary waterfloods are usually attributed to vertical and areal sweep inefficiencies associated with reservoir heterogeneities and nonconformance in flood patterns. Most of the oil in petroleum reservoirs is retained as a result of macroscopic reservoir heterogeneities which divert the driving fluid and the microscopically induced capillary forces which restrict viscous displacement of contacted oil. This oil accounts for approximately 70 percent, or 300 x 10 bbl, of the known reserves in the United States. 

We want to develop the equations for the two-phase flow of fluids in porous media and discuss numerical methods for their solution. These problems are important in describing the flow of water and oil in petroleum reservoirs. The process of waterflooding is where water is injected into a reservoir in order to recover the oil that is residual in the void spaces of rocks such as sandstone and limestone. In order to describe this process, a mathematical model must be developed for the two-phase flow of water and oil through the porous rock material. 

Craig, F. F. The Reservoir Engineering Aspects of Waterflooding Monograph Series 3, Society of Petroleum Engineers Richardson, TX 1971. 

F. Craig, Jr., in "The Reservoir Engineering Aspects of Waterflooding," published by the Society of Petroleum Engineers of AIME, Dallas, Texas (1971). 

Craig, F.F., The Reservoir Engineering Aspects of Waterflooding, SPE Monograph Series, Soeiety of Petroleum Engineers, Dallas, 1971. 

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