| 摘要 |
The efficiency of an oil recovery process of the type wherein an aqueous surfactant solution is injected into a subterranean, petroleum-containing formation is increased by determining the optimum range of salinity and hardness, e.g. calcium and magnesium, for the particular surfactant being used, and formulating an aqueous preflush solution, the salinity and hardness of which are within the range for optimum surfactant effectiveness, and adding an effective amount of hydrophilic polymer to yield a suitable viscosity greater than the formation water viscosity, and injecting the aqueous preflush solution into the formation prior to injection of the surfactant solution. The viscous, controlled salinity and hardness solution displaces the formation water effectively, thereby insuring that the salinity and hardness of the surfactant solution will be at or near an optimum value for oil recovery. Suitable hydrophilic polymers include polyacrylamide, polysaccharide, polyvinyl aromatic sulfonate, polyethylene oxide, methyl cellulose, or carboxy methyl cellulose.
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