Patent ID: 7595283

Claim:
A method for treating a subterranean formation penetrated by a well bore to reduce its permeability to aqueous-based fluids comprising: providing a permeability-modifying aqueous treatment fluid comprising a hydrophobically modified water-soluble polymer that has a molecular weight in the range of about 100,000 to about 10,000,000 once synthesized and comprises a polymer backbone and a hydrophobic branch, the polymer backbone comprising polar heteroatoms, the hydrophobic branch comprising an organic acid derivative selected from the group consisting of: an anhydride of octenyl succinic acid, an ester of octenyl succinic acid, an amide of octenyl succinic acid, an anhydride of dodecenyl succinic acid, an ester of dodecenyl succinic acid, and an amide of dodecenyl succinic acid; and injecting into the subterranean formation penetrated by a well bore said permeability-modifying aqueous treatment fluid, wherein the hydrophobically modified water-soluble polymer reduces the permeability of the subterranean formation to aqueous-based fluids.