Verwendung von Polyacrylamid und Glyoxal enthaltende Gelen zur selektiven Reduzierung der Wasserpermeabilität

摘要

A process is described for selectively reducing water permeability in very permeable regions of underground formations by means of an aqueous gel formed by in situ crosslinking of an aqueous solution of a non-ionic polyacrylamide or of a non-ionic and non-hydrolysed acrylamide copolymer containing less than 5 % of N-alkylsubstituted groups. The crosslinking is carried out by injection of an amount of glyoxal so that the glyoxal/polyacrylamide or acrylamide copolymer molar ratio is less than 0.2, and at a pH less than 7.5. Application to oil recovery.