Patent ID: 7985718
Filing Date: 2011-07-26
Classification: C09K

Abstract:
1. A method of tertiary mineral oil extraction, which is a method for surfactant flooding, comprising injecting a surfactant formulation through at least one injection bore into a mineral oil deposit, thereby lowering an interfacial tension between water and mineral oil, and removing crude oil from the deposit through at least one production bore, said surfactant mixture comprising at least the following surfactants: from 50 to 99% by weight of at least one surfactant (A) of the general formula R from 1 to 50% by weight of at least one cosurfactant (B), where the amounts stated are based in each case on the total amount of all surfactants in the mixture, wherein the cosurfactant (B) has the general formula R 2 —O—(R 3 —O) n —R 4 (I) and where the R 2 , R 3 and R 4 radicals and the number n are each defined as follows: n is from 2 to 20, R R R R R R with the proviso that the amount of surfactants (A) and cosurfactants (B) together is at least 25% by weight based on the amount of all surfactants in the mixture, wherein the surfactant mixture is used in the presence of formation water which comprises more than 150 g/l of dissolved salts.