Waterflooding process employing anionic-nonionic copolymer

摘要

This specification discloses a waterflooding process for producing oil from an oil-containing subterranean formation that is penetrated by an injection well and a production well. An aqueous solution of a water soluble copolymer having segments formed of blocks of an aromatic monomer and blocks of an olefinic monomer chemically modified to have an anionic function on the olefinic segments is injected into the formation to improve the recovery of oil therefrom.