A method for using a surfactant formulation in chemical enhanced oil recovery, wherein said surfactant formulation comprises at least: (i) an anionic salt of an alkyl alkoxylated sulfate, wherein said alkyl alkoxylated sulfate has a molecular structure as shown in (I), wherein R is a linear, branched or mixture of linear and branched alkyl group having from 10 to 20 carbon atoms, n=4 −15, m=0-10, M+ is an alkali metal ion, an alkanolamine ion, an alkyl amine ion or an ammonium ion; and (ii) a non-ionic alcohol O ethoxylate, wherein said alcohol ethoxylate has a molecular structure as shown in (II), wherein R1 is a linear, branched or mixture of linear and branched alkyl group having from 8 to 24 carbon atoms, y=20-100.