Abstract: The present invention provides a method for predicting the optimal salinity of individual members of a class of internal olefin sulfonate compositions in a mixture containing the individual member, a brine and hydrocarbons, wherein the internal olefin sulfonate compositions comprise a mixture containing hydroxy alkane sulfonates and alkene sulfonates. The invention further provides use of the weight ratio of hydroxy alkane sulfonates to alkene sulfonates in an internal olefin sulfonate composition to predict the optimal salinity of the surfactant composition in a mixture of the surfactant composition, a brine and an oil.

Abstract: The present invention provides a method for predicting the optimal salinity of individual members of a class of internal olefin sulfonate compositions in a mixture containing the individual member, a brine and hydrocarbons, wherein the internal olefin sulfonate compositions comprise a mixture containing hydroxy alkane sulfonates and alkene sulfonates. The invention further provides use of the weight ratio of hydroxy alkane sulfonates to alkene sulfonates in an internal olefin sulfonate composition to predict the optimal salinity of the surfactant composition in a mixture of the surfactant composition, a brine and an oil.

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.