| 摘要 |
A composition for selectively reducing the permeability of the higher permeability zones of a subterranean reservoir having heterogeneous permeability, such permeability reduction extending continuously from nearby the well as far into the reservoir as is desired. Said composition comprises an aqueous solution or solutions of a water-soluble polymer, a material capable under certain conditions of at least partially cross-linking the polymer to form a gelatinuous precipitate, a water-soluble alkaline material in an amount sufficient to maintain the pH of the polymer-containing composition above the pH at which cross-linking occurs until the composition has passed a desired distance through the reservoir, and a temperature-activated water-soluble acidic material dissolved in the aqueous solution in an amount sufficient to lower the pH of the overall solution to the pH at which cross-linking occurs when said solution is subjected to an elevated temperature. When injected into a reservoir, the composition forms a continuous gelatinuous plug which extends from the immediate vicinity of the well to a point as close to the well as about 20 feet, when it is desired to plug a feature of the strata which extends only a short distane therein, or as far into the well as is desired, for example up to 200 feet, when it is desired to plug an extensive zone of high permeability.
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