Surfactant-Based Waterflooding for Subterranean Oil Recovery

During oil exploration, the presence of the oil bank is determined and holes are drilled through the rock in order to access the oil. When this happens, the inherent 

Caneba, in Free-Radical Retrograde-Precipitation Polymerization (FRRPP), 

Waterflooding offers a simple method of post-primary production from an oilfield. A typical approach is to use a five-spot pattern of wells, in which the outer wells (injection wells) are used for pumping in water/brine, while the middle well (production well) is used for collecting the oil (Fig. 5.1.2). 

The product stream from the production well is a mixture of oil and water/brine, and the oil can easily be separated by gravity. Note that oil has a specific gravity of about 0.9, while water/brine at or slightly above 1.0. Thus, even if one allows the mixture to stand in a holding tank, the oil will naturally accumulate as a top layer of fluid. The bottom aqueous layer can be reused typically by pumping it back through the injection wells, for a closed-loop operation with some additional make-up water to replace the oil removed from the reservoir. 

In order to improve production from waterflooding operations, various water-soluble thickening polymers are incorporated into the injection fluid (Mohanty and Caneba, 2005). The idea is that there is a need for a relatively high capillary number, Ac, in order to realize more efficient oil displacement from solid surfaces. Note that the capillary number is related to the displacing fluid viscosity, fx, interstitial velocity, V, and interfacial tension (IFT), y, (Pope and Baviere, 1991) 

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