Process for secondary recovery

Claim 1

A process for recovering hydrocarbons from a subterranean hydrocarbon-bearing formation penetrated by an injection well and a production well which comprises; (a) injecting into the formation via an injection well a drive fluid comprising water having dissolved therein about 0.05 to about 5 weight percent of a material of number average molecular weight from about 10,000 to about 2,000,000 selected from the group consisting of (I) polyacrylamide and (II) partially hydrolyzed polyacrylamide or the sodium, potassium or ammonium salt thereof and from about 0.01 to about 2.0 weight percent of a substance selected from the group consisting of (III) polyacrylamide and (IV) partially hydrolyzed polyacrylamide or the sodium, potassium or ammonium salt thereof alkoxylated with about 2 to about 100 weight percent of 2,3-epoxy-1-propanol wherein in the partially hydrolyzed polyacrylamide or the sodium, potassium or ammonium salts thereof the proportion of amide containing monomers is about 33 to about 88 mole percent and the proportion of the carboxy containing monomers is about 12 to about 67 mole percent, (b) forcing the said fluid through the formation, and (c) recovering hydrocarbons through the production well.