Filtration and reuse of surfactant-containing produced water for oil recovery

A method for recovering oil from an oil bearing formation comprising:

• i) recovering an oil-water mixture from the oil-bearing formation;
• ii) separating at least a portion of the oil from the oil-water mixture to form a produced water;
• iii) adding a polymeric alkylene oxide surfactant having a Mw of less than 10000 Da to the produced water;
• iv) adding a second surfactant to the produced water, wherein the second surfactant is represented by:
• wherein:
• R3 and R4 are each independently selected from a group consisting of hydrogen and linear and branched alkyl groups having from 1 to 16 carbons;
• and M is selected from sodium, potassium, lithium and ammonium;
• v) passing the produced water through a polymeric membrane form a permeate stream and a retentate stream;
• and
• vi) injecting the permeate stream into the oil bearing formation.