Secondary recovery process

摘要

Hydrocarbons are recovered from a subterranean hydrocarbon-bearing formation penetrated by an injection well and a production well by displacing hydrocarbons toward the production well using an aqueous drive fluid such as water or brine containing dissolved therein: (a) a small amount of a nonionic surfactant formed by reacting an alcohol having not more than 6 carbon atoms or phenol first with butylene oxide and then with ethylene oxide and (b) a small amount of an anionic sulfate or sulfonate surfactant. Optionally the drive fluid may be saturated with natural gas, nitrogen and/or carbon dioxide at the injection pressure. A polymeric thickening agent also may be included in the drive fluid, if desired.