Patent ID: 7150319

Claim:
A method for reducing or completely eliminating water influx to a mineral oil or natural gas production borehole by introducing into this borehole an aqueous solution of a copolymer, the copolymer comprising A) 40–98% by weight of structural units of the formula in which R 1 is hydrogen or methyl, R 2 is C 2 –C 10 -alkylene and Me + is an ammonium or an alkali metal ion, B) from 0.1 to 58% by weight of structural units of the formula C) from 0.1 to 10% by weight of structural units of the formula in which R 3 and R 4 , independently of one another, are hydrogen, methyl or ethyl, or R 3 and R 4 together are propylene or pentamethylene, and D) from 0.1 to 10% by weight of structural units of the formula and, simultaneously with the copolymer or thereafter, introducing into the formation or deposit a crosslinking agent of the copolymer, which crosslinking agent is selected from the group consisting of a zirconium, a chromium, a titanium, an aluminum compound, and a mixture thereof, and then putting the borehole for the recovery of mineral oil or natural gas or a mixture thereof into operation.