Abstract: The invention relates to a method of treating a hydrocarbon containing formation, comprising: (a) providing a composition to at least a portion of the hydrocarbon containing formation, wherein the composition comprises an anionic surfactant based on an alkoxylated primary alcohol having a branched aliphatic group, which group has an average carbon number of from 9 to 15 and an average number of branches of from 0.5 to 2.5, and having an average of at least 0.5 mole of alkylene oxide groups per mole of primary alcohol; and (b) allowing the composition to interact with hydrocarbons in the hydrocarbon containing formation. Further, the invention relates to the hydrocarbon recovery composition that is used in said method.

Abstract: The invention relates to a method of treating a hydrocarbon containing formation, comprising the following steps: a) providing a composition, which comprises a surfactant which is a compound of the formula (I) R—O—[R?—O]x—X, wherein R is a hydrocarbyl group having a weight average carbon number of from 13 to 30, R?—O is an alkylene oxide group, x is the number of alkylene oxide groups R?—O, and X is selected from the group consisting of: (i) a group comprising a sulfate moiety; (ii) a group comprising a carboxylate moiety; and (iii) a group comprising a sulfonate moiety, to at least a portion of the hydrocarbon containing formation, wherein the hydrocarbon containing formation comprises a crude oil which has a weight ratio of saturates to aromatics of from 0.6 to 5.0; and b) allowing the surfactant from the composition to interact with the hydrocarbons in the hydrocarbon containing formation.

Abstract: The invention relates to a method of treating a hydrocarbon containing formation, comprising the following steps: a) providing a composition comprising two or more surfactants to at least a portion of the hydrocarbon containing formation having a salinity, wherein said two or more surfactants are selected such that the salinity range within which the interfacial tension between water and the hydrocarbons in the hydrocarbon containing formation can be reduced to a certain level is widened as compared to the cases wherein only one of said two or more surfactants is used; and b) allowing said two or more surfactants from the composition to interact with the hydrocarbons in the hydrocarbon containing formation.

Abstract: The invention relates to a method of treating a hydrocarbon containing formation, comprising: (a) providing a composition to at least a portion of the hydrocarbon containing formation, wherein the composition comprises water and an anionic surfactant which is an internal olefin sulfonate (IOS), which has a weight ratio of branched IOS molecules to linear IOS molecules N which is greater than 0 to smaller than 11:89; and (b) allowing the composition to interact with the hydrocarbons in the hydrocarbon containing formation. Further, the invention relates to a hydrocarbon recovery composition which comprises the composition used in said method, and to a hydrocarbon containing composition produced from a hydrocarbon containing formation which in addition to hydrocarbons contains the composition used in said method.