Patent ID: 9475979
Filing Date: 2016-10-25
CPC Classification: C09K

Claim Text:
1. A process for producing mineral oil by means of Winsor type III microemulsion flooding, comprising injecting an aqueous surfactant formulation into a mineral oil deposit through at least one injection well for the purpose of lowering the interfacial tension between oil and water to <0.1 mN/m, and withdrawing crude oil from the deposit through at least one production well; wherein the aqueous surfactant formulation comprises a surfactant mixture comprising at least three ionic surfactants which differ in terms of the hydrocarbyl moiety (R where R R where R wherein the C each A k is an integer from 1 to 99, X is a branched or unbranched hydrocarbylene group which has 1 to 10 carbon atoms and may be substituted by an OH group; o is 0 or 1; M Y b is 1, 2 or 3 and a is 1 or 2.