| 摘要 |
In a waterflooding process for oil recovery from oil-bearing earth formations, a high-permeability zone is isolated from a low-permeability zone at the injection well. A water solution of sodium silicate is injected into one zone, a water solution of an activator - a chemical such as ammonium sulfate which causes sodium silicate solution to gel - being injected into the other zone. Preferably, the two solutions are injected simultaneously, the rates of injection being proportional to the pore volumes of the two zones to keep the solution fronts together. Fracturing pressures are avoided.
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