Patent ID: 7159656

Claim:
A method of reducing the permeability of one or more selected sections of a subterranean formation penetrated of a horizontal well bore and the flow of water or water and hydrocarbons or hydrocarbons therefrom comprising the steps of: (a) preparing or providing an aqueous treating fluid comprising water and a water-soluble formation permeability reducing agent, wherein the water-soluble formation permeability reducing agent is a hydrophobically modified water-soluble polymer present in the aqueous treating fluid in an amount in the range of from about 0.1% to about 10% by weight of the aqueous treating fluid, wherein the hydrophobically modified water-soluble polymer is a reaction product of a hydrophilic monomer and a hydrophobically modified hydrophilic monomer, and wherein the hydrophobically modified water-soluble polymer comprises a dimethylaminoethyl methacrylat/hexadecyldimethylammoniumethyl methacrylate bromide copolymer having a mole ratio of hydrophilic monomer to hydrophobically modified hydropbilic monomer of 95:5; and (b) introducing the aqueous treating fluid containing the water-soluble formation permeability reducing agent into the one or more selected sections of the subterranean formation closest to the heel of the horizontal wellbore so that the permeabilities and flows of water or water and hydrocarbons or hydrocarbons therefrom are reduced.