Alkylxylene sulfonates for enhanced oil recovery processes
The present invention is directed to alkylxylene sulfonate for enhanced oil recovery processes. The alkylxylene moiety in the alkylxylene sulfonate contains a high percentage of the 4-alkyl-1,2-dimethyl benzene isomer and a high percentage of alkyl group attachment to the xylene ring at positions higher than the 2-position on the alkyl carbon chain. The present invention is also directed to a method for enhancing the recovery of oil from a subterranean reservoir which method employs the alkylxylene sulfonate of the present invention. The alkylxylene sulfonate is employed in an aqueous media. The method optionally employs co-surfactants. It has surprisingly been discovered that the high percentage of the 4-alkyl-1,2-dimethyl benzene isomer and the high percentage alkyl group attachment to the xylene moiety at positions higher than the 2-position along the alkyl carbon chain on the alkylxylene sulfonate of the present invention provides an enhanced oil recovery (EOR) surfactant having low Interfacial Tension (IFT).
1. An alkylxylene sulfonate for enhanced oil recovery processes, having the general formula:
wherein R is an alkyl group containing from about 10 to about 58 carbon atoms, M is a mono-valent cation, and the alkylxylene moiety is alkyl-ortho-xylene in at least 85 percent of the total alkylxylene sulfonate and wherein the alkylxylene moiety in the alkylxylene sulfonate contains greater than about 70 percent of the 4-alkyl-1,2-dimethyl benzene isomer and the attachment of the alkyl group to the xylene moiety in the alkylxylene sulfonate is at positions higher than the 2-position along the alkyl chain in at least 40 percent of the total alkylxylene sulfonate, and wherein the alkyl group contains a distribution of alkyl chain lengths wherein the alkyl chain lengths comprise from about 40 to about 80 percent C 12 to C 20 and about 5 percent to about 15 percent of C 32 to C 58 , and further wherein the optimum salinity of the alkylxylene sulfonate is in the range of 0.1 to 0.5 weight percent sodium chloride.
2. The alkylxylene sulfonate of claim 1 , wherein the optimum salinity of the alkylxylene sulfonate is in the range of 0.2 to 0.5 weight percent sodium chloride.
3. The alkylxylene sulfonate of claim 2 , wherein the optimum salinity of the alkylxylene sulfonate is in the range of 0.3 to 0.4 weight percent sodium chloride.
4. The alkylxylene sulfonate of claim 3 , wherein the optimum salinity of the alkylxylene sulfonate is about 0.3 weight percent sodium chloride.
5. The alkylxylene sulfonate of claim 1 , wherein the alkylxylene moiety in the alkylxylene sulfonate contains greater than about 80 percent of the 4-alkyl-1,2-dimethyl benzene isomer.
6. The alkylxylene sulfonate of claim 5 , wherein the alkylxylene moiety in the alkylxylene sulfonate contains at least 90 percent of the 4-alkyl-1,2-dimethyl benzene isomer.
7. The alkylxylene sulfonate of claim 1 , wherein the alkyl group on the xylene moiety is attached at positions higher than the 2-position along the alkyl chain in at least 45 percent of the total alkylxylene sulfonate.
8. The alkylxylene sulfonate of claim 7 , wherein the alkyl group on the xylene moiety is attached at positions higher than the 2-position along the alkyl chain in at least 60 percent of the total alkylxylene sulfonate.
9. The alkylxylene sulfonate of claim 1 , wherein the mono-valent cation is an alkali metal.
10. The alkylxylene sulfonate of claim 9 , wherein the alkali metal is sodium.
11. The alkylxylene sulfonate of claim 1 , wherein the alkyl group is derived from a linear alpha olefin or an isomerized olefin containing from about 10 to about 58 carbon atoms.
12. The alkylxylene sulfonate of claim 11 , wherein the alkyl group is derived from a linear alpha olefin or an isomerized olefin containing from about 10 to about 40 carbon atoms.
13. The alkylxylene sulfonate of claim 1 , wherein the alkyl chain lengths comprise from about 50 to about 70 percent C 12 to C 20 and about 5 percent to about 15 percent of C 32 to C 58 .
14. The alkylxylene sulfonate of claim 13 , wherein the alkyl chain lengths comprise about 8 percent to about 12 percent of C 32 to C 58 .
15. The alkylxylene sulfonate of claim 1 , wherein the alkylxylene moiety is alkyl-ortho-xylene in at least 95 percent of the total alkylxylene sulfonate.
16. The alkylxylene sulfonate of claim 1 , wherein the mono-valent cation is an ammonium ion or an organic ammonium ion.