Abstract: A water-flood surfactant and the method of making it which comprises the steps of mixing, in a reactor, sodium hydroxide with a sulfonated natural petroleum crude, the sodium hydroxide being in excess of the amount required to convert the sulfonate to phenol and sufficient to convert a portion of the phenol to sodium phenolate; heating the mixture while stirring to about 319.degree. C. for a period of about one hour; passing a current of inert gas through the top of the reactor during the heating step; cooling the mixture to a temperature of approximately 200.degree. C. while continuing to pass an inert gas through the top of the reactor; and passing ethylene oxide gas through the mixture in the reactor while maintaining the temperature in the reactor between 200.degree. C. and 220.degree. C.