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 0.01 to about 5.0 weight percent of an alkoxylated terpolymer of number average molecular weight of about 50,000 to about 8,000,000 comprising recurring E-type units of the formula: ##STR8## recurring F-type units of the formula: ##STR9## and recurring G-type units of the formula: ##STR10## wherein M is selected from the group consisting of hydrogen, sodium, potassium and ammonia and wherein in the said terpolymer the weight percent of the E-type units ranges from about 60 to about 95, the weight percent of the G-type units ranges from about 2 to about 10 and with the balance being the F-type units; said terpolymer being alkoxylated with about 2 to about 150 weight percent of a material selected from the group consisting of ethylene oxide and a mixture of ethylene oxide and propylene oxide wherein the weight percent of ethylene oxide in the said mixture is about 60 to about 95. (B) forcing the said fluid through the formation, and (C) recovering hydrocarbons through the production well.