GELLABLE BUFFERED AQUEOUS COMPOSITION AND ITS USE IN ENHANCED PETROLEUM RECOVERY

摘要

A gellable aqueous composition particularly suitable for reducing the permeability of high-permeability zones in an oil reservoir is an aqueous solution comprising: - a) a water-soluble organic polymer cross-linkable by the effect of a polyvalent metal ion cross-linking agent; - b) a Cr(III) ion cross-linking agent; - c) a buffer agent free or substantially-free of ligand characteristics towards the cross-linking agent, and chosen from organic bases and carboxylic or sulphonic aromatic organic acids; the solution pH being adjusted to a value within the range of about 2 to about 7.