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Water-soluble polymers commonly used in the oil field are reviewed. The properties of guar, guar derivatives, cellulose derivatives, xanthan gum, locust bean gum, starches, and synthetic polymers, especially polyacrylamides, are discussed and related to chemical structures of the polymers. Original data comparing polymer solution viscosity properties under identical conditions are presented. These data include effect of polymer concentration on solution viscosity, temperature effect on solution viscosity, viscosity in acidic solution, and polymer solution viscosity in the presence of a hemicellulase enzyme.

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Using surfactants below their critical micelle concentrations, CCMC' to reduce gas mobility throughout a reservoir can be advantageous. When used in reservoir brines below their CCMC inexpensive anionic surfactants propagate through rock with little delay owing to adsorption. Yet gas mobility is reduced below that of a watertlood in either surfactant-water-altemating-gas (SWAG) or coinjection experiments. Moreover, oil recovery is higher than in processes without surfactant. In contrast, at concentrations above the CCMC, surfactant adsorption is much higher and the injected surfactant concentration can be greatly delayed. In addition, CO 2 mobility can be reduced so far below that of a watertlood that injectivity suffers. Moreover, oil recovery can be reduced because oil is emulsified and its mobility is lowered. This type of foam should be considered only for near-wellbore fluid diversions.

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