摘要 |
Methods and compositions for altering the water permeability of subterranean formations are provided. The compositions are comprised of water, at least one polymer capable of being gelled when contacted with a crosslinking agent, at least one crosslinking agent comprised of polyvalent metal cation, and a cation reactivity retarding chelating agent which provides anion for chelating the polyvalent metal cation selected from substantially water soluble dicarboxylic acids, hydroxy carboxylic acids, ketocarboxylic acids and the corresponding salts thereof.
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