| 摘要 |
An adjusted salinity and hardness, aqueous preflush containing a thickening material which can be, for example, a hydrophilic material such as polyacrylamide, polysaccharide, polyvinyl aromatic sulfonate, polyethylene oxide, methyl cellulose, etc. or colloidal silica, etc. in a concentration sufficient to increase the viscosity of the adjusted salinity aqueous preflush fluid is injected into a subterranean, petroleum-containing formation. Optionally, the preflush fluid may contain a sacrificial agent, such as sodium tripolyphosphate, etc. The high salinity formation water is efficiently displaced by viscous low salinity aqueous preflush fluid to increase the effectiveness of a subsequently injected high salinity sensitive single surfactant solution. The surfactant may be displaced by a mobility buffer solution, which then may be displaced by water.
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