Patent ID: 8513168

Claim:
A method of treating a hydrocarbon containing formation, comprising: (a) providing a hydrocarbon recovery composition to at least a portion of the hydrocarbon containing formation as an injectable fluid that has been admixed with brine from the formation, wherein (i) when the salinity of the brine is from about 2 wt % to about 4 wt %, the composition comprises a blend of a C 20-24 internal olefin sulfonate and a C 24-28 internal olefin sulfonate wherein the weight ratio of the C 20-24 internal olefin sulfonate to the C 24-28 internal olefin sulfonate is from about 90:10 to about 70:30 and (ii) when the salinity of the brine is greater than about 4 wt % up to about 13 wt % the composition comprises a blend of a C 20-24 internal olefin sulfonate and a C 15-18 internal olefin sulfonate wherein the weight ratio of the C 20-24 internal olefin sulfonate to the C 15-18 internal olefin sulfonate is from about 90:10 to about 70:30; and (b) allowing the composition to interact with hydrocarbons in the hydrocarbon containing formation.