Patent ID: 9518208
Filing Date: 2016-12-13
CPC Classification: C09K

Claim Text:
1. A gelling agent for water shut-off in oil and gas wells, comprising: a water soluble polymer selected from the group consisting of polyvinyl alcohol, a polyvinyl alcohol copolymer and mixtures thereof; an amino aldehyde oligomer selected from the group consisting of urea formaldehyde and melamine formaldehyde; at least one gelation retarder selected from the group consisting of lignosulfonates and ethyl acetate; a cross-linking agent selected from the group consisting of boric acid, acetic acid, borax, ammonium chloride, ammonium sulfate, glyoxal, and glutardialdehyde; and an aqueous solvent, the water soluble polymer and the amino aldehyde oligomer being mixed in the aqueous solvent to form a polymer solution, the water soluble polymer being between 10% and 50% by weight of the polymer solution, and the amino aldehyde oligomer being between 50% and 90% by weight of the polymer solution.