Alcohol-free micellar solutions which yield high solubilization ratios (15-30 cc/cc), high final oil recoveries and eliminate the use of alcohol, a costly chemical, have been formulated for application in chemical floods.

A major difficulty was to preclude gels, liquid crystals, macroemulsions and precipitates along the composition path during a chemical flood. A screening strategy was applied to select among combinations of quite different surfactant structures. Corefloods were run with a blend of pure surfactants (C180CH2· CH2-S03Na, 8øC16SO3Na and 7øC14SO3Na), an ethoxylated sulfonate (6C16(OCH2·CH2)2 SC3 Na and a blend of an internal olefine sulfonate and a petroleum sulfonate. A slug size-efficiency curve obtained from corefloods with screened alcohol-free formulations, was compared to previous data with a conventional petroleum sulfonate/alcohol system (TRS 10-410/IBA) at 65° C taken as our basecase.

An equimolar blend of an internal olefin (C20-C24) sulfonate and a petroleum sulfonate gave a final oil recovery of 94% with a 13% Pvi slug size, 3v% surfactant concentration, at 80° C. When the slug size was reduced to 3% Pvi, the oil recovery still was 80%. Final results are compared to the basecase and other combinations tested and reported under comparable conditions.

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