Method and composition for enhanced hydrocarbons recovery

Abstract

An injectable fluid for treating a hydrocarbon containing formation is described. The injectable fluid includes ((i) when the salinity of the brine is from about 2 wt % to about 4 wt %, a composition that 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 %, a 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.

What is claimed is: 
     
         1 . An injectable fluid for treating a hydrocarbon containing formation, comprising
 (a) a hydrocarbon recovery composition comprising 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; admixed with   (b) brine from the formation, wherein the salinity of the brine is from about 2 wt % to about 4 wt %.   
     
     
         2 . The injectable fluid of  claim 1  wherein the blend of the C 20-24  internal olefin sulfonate and the C 24-28  internal olefin sulfonate comprises from about 0.01 to about 0.1 wt % of the injectable fluid. 
     
     
         3 . The injectable fluid of  claim 1  wherein the injectable fluid also comprises less than about 0.1 wt % of the total composition of a solubilizer. 
     
     
         4 . The injectable fluid of  claim 3  wherein the injectable fluid comprises from about 0.02 to about 0.05 wt % of the solubilizer. 
     
     
         5 . The injectable fluid of  claim 1 , comprising an overall internal olefin sulfonate blend of 1) a first internal olefin sulfonate blend having an average carbon number of from about 20.5 to about 23 and at least 50% by weight of the internal olefin sulfonates in the blend contain from about 20 to about 24 carbon atoms and 2) a second internal olefin sulfonate blend having an average carbon number of from about 25 to about 27 and at least 50% by weight of the internal olefin sulfonates in the blend contain from about 24 to about 28 carbon atoms, wherein the weight ratio of the first internal olefin sulfonate blend to the second internal olefin sulfonate blend is from about 90:10 to about 70:30. 
     
     
         6 . The injectable fluid of  claim 5  wherein at least about 65 percent by weight of the internal olefin sulfonates in the first blend contain from about 20 to 24 carbon atoms and at least about 60 percent by weight of the internal olefin sulfonates in the second blend contained from about 24 to about 28 carbon atoms. 
     
     
         7 . An injectable fluid for treating a hydrocarbon containing formation, comprising
 (a) a hydrocarbon recovery composition comprising 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; admixed with   (b) brine from the formation, wherein the salinity of the brine is greater than about 4 wt % up to about 13 wt %.   
     
     
         8 . The injectable fluid of  claim 7  wherein the blend of the C 20-24  internal olefin sulfonate and the C 15-18  internal olefin sulfonate comprises from about 0.01 to about 0.1 wt % of the injectable fluid, and then injecting the injectable fluid into the formation. 
     
     
         9 . The injectable fluid of  claim 7  wherein the injectable fluid also comprises less than about 0.1 wt % of the total composition of a solubilizer. 
     
     
         10 . The injectable fluid of  claim 9  wherein the injectable fluid comprises from about 0.02 to about 0.05 wt % of the solubilizer. 
     
     
         11 . The injectable fluid of  claim 7  comprising an overall internal olefin sulfonate blend of 1) a first internal olefin sulfonate blend having an average carbon number of from about 20.5 to about 23 and at least 50% by weight of the internal olefin sulfonates in the blend contain from about 20 to about 24 carbon atoms and 2) a second internal olefin sulfonate blend having an average carbon number of from about 16 to about 17 and at least 50% by weight of the internal olefin sulfonates in the blend contain from about 15 to about 18 carbon atoms, wherein the weight ratio of the first internal olefin sulfonate blend to the second internal olefin sulfonate blend is from about 90:10 to about 70:30. 
     
     
         12 . The injectable fluid of  claim 11  wherein at least about 65 percent by weight of the internal olefins in the first blend contain from about 20 to about 24 carbon atoms and at least about 75 percent by weight of the internal olefin sulfonates in the second blend contain from about 15 to about 18 carbon atoms.