Polymer flooding high sweep efficiency

Polymer Flooding. Even in the absence of fractures and thief 2ones, the volumetric sweep efficiency of injected fluids can be quite low. The poor volumetric sweep efficiency exhibited in waterfloods is related to the mobiUty ratio, Af, the mobiUty of the injected water in the highly flooded (low oil saturation) rock, divided by the mobiUty of the oil in oil-bearing portions of the reservoir, (72,73). The mobiUty ratio is related to the rock permeabihty to oil, and injected water, and to the viscosity of these fluids by the following equation ... 

Low tension waterflooding is a method intermediate between alkaline and micellar/polymer technology. The LTWF employs a dilute surfactant to reduce IFT and mobilize residual oil. A few field trials (26-29) of this process have been tried with mixed success. None of these trials however employed sodium silicates in any part of the flood design. Instead, other alkalis such as sodium carbonate and sodium tripoly- phosphate were used. Some of the reasons proposed for the limited success in these trials were 1) high consumption of the sacrificial agents, leaving the surfactant unprotected, 2) poor sweep of the pay zone, 3) limited mobility control and lower than expected displacement efficiency. Recent work published and obtained in our laboratories has shown that sodium silicates may help to overcome some of these problems better than other alkalis. 

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