Microemulsions and uses thereof to displace oil in heterogeneous porous media

Abstract

Novel microemulsion formulations comprising a surfactant or combination of surfactants are disclosed for improved crude oil cleanup or recovery from subsurface geological formations, especially those containing carbonate cements.

What is claimed is: 
     
         1 . A microemulsion, comprising:
 a surfactant selected from the group consisting of:
 (a) a surfactant comprising a linear tail and having a hydrophile-lipophile balance (HLB) number between 8 and 18, 
 (b) a surfactant comprising a branched tail and having a HLB number between 8 and 18, and 
 (c) mixtures thereof, 
   a coupling agent selected from an alcohol with a C 3 -C 20  linear or branched hydrocarbon chain;   a carrier fluid selected from a terpene, hydrocarbon liquid, or natural oil; and   brine.   
     
     
         2 . The microemulsion of  claim 1 , wherein:
 when the surfactant comprising the branched tail is present, the surfactant comprising the branched tail is selected from the group consisting of TRITON X-Series alkylphenol ethoxylates, TERGITOL NP-Series alkylphenol ethoxylates, and TERGITOL TMN-Series secondary alcohol ethoxylates; or   when the surfactant comprising the linear tail is present, the surfactant comprising the linear tail is selected from the group consisting of BIO-SOFT N-Series primary alcohol ethoxylates, GENAPOL X-Series primary alcohol ethoxylates, TRITON CG-Series alkyl polyglucosides, n-alkyl-β-D-maltosides, and TWEEN Series polysorbates.   
     
     
         3 . The microemulsion of  claim 1 , wherein:
 when the surfactant comprising the branched tail is present, the surfactant comprising the branched tail is selected from the group consisting of TRITON X-100, TRITON X-102, TRITON X-114, TRITON X-165, TERGITOL NP-6, TERGITOL NP-7, TERGITOL NP-8, TERGITOL NP-9, TERGITOL NP-9.5, TERGITOL NP-10, TERGITOL NP-11, TERGITOL NP-12, TERGITOL NP-13, TERGITOL NP-15, and TERGITOL TMN-6, TERGITOL TMN-10, TERGITOL TMN-100X; or   when the surfactant comprising the linear tail is present, the surfactant comprising the linear tail is selected from the group consisting of BIO-SOFT N91-6, BIO-SOFT N91-8, BIO-SOFT N1-5, BIO-SOFT N1-7, BIO-SOFT N1-9, BIO-SOFT N23-6.5, BIO-SOFT N25-7, BIO-SOFT N25-9, GENAPOL X-050, GENAPOL X-060, GENAPOL X-080, GENAPOL X-089, TRITON CG-50, TRITON CG-110, TRITON CG-650, n-octyl-β-D-maltoside, n-nonyl-β-D-maltoside, n-decyl-β-D-maltoside, n-undecyl-β-D-maltoside, n-dodecyl-β-D-maltoside, TWEEN 20, TWEEN 21, TWEEN 40, TWEEN 60, TWEEN 65, and TWEEN 80.   
     
     
         4 . The microemulsion of  claim 1 , wherein the coupling agent comprises isopropanol. 
     
     
         5 . The microemulsion of  claim 1 , wherein the carrier fluid comprises d-limonene. 
     
     
         6 . The microemulsion of  claim 1 , wherein a weight ratio of the surfactant to the carrier fluid to the brine to the coupling agent in the microemulsion is 2:1:1:0.8. 
     
     
         7 . The microemulsion of  claim 1 , wherein a weight ratio of the surfactant to the coupling agent in the microemulsion is between 1:1 and 10:1. 
     
     
         8 . The microemulsion of  claim 1 , wherein a weight ratio of the surfactant to the coupling agent in the microemulsion is 2.5:1. 
     
     
         9 . The microemulsion of  claim 1 , wherein a weight ratio of a mixture of the surfactant and the coupling agent to the carrier fluid in the microemulsion is higher than 6:4. 
     
     
         10 . The microemulsion of  claim 1 , wherein a concentration of the surfactant in the microemulsion is between 0.05% and 10% by weight. 
     
     
         11 . The microemulsion of  claim 1 , wherein a concentration of the carrier fluid in the microemulsion is between 0.01% and 10% by weight. 
     
     
         12 . The microemulsion of  claim 1 , wherein a concentration of the coupling agent in the microemulsion is between 0.01% and 10% by weight. 
     
     
         13 . The microemulsion of  claim 1 , wherein a concentration of the brine in the microemulsion is between 80% and 99.9% by weight. 
     
     
         14 . The microemulsion of  claim 1 , wherein:
 the coupling agent comprises isopropanol; and   the carrier fluid comprises d-limonene.   
     
     
         15 . The microemulsion of  claim 1 , wherein the surfactant comprises the mixture of surfactants. 
     
     
         16 . The microemulsion of  claim 1 , wherein the mixture of surfactants comprises at least two of TRITON X-100, BIO-SOFT N25-9, n-dodecyl-β-D-maltoside, TWEEN 40, or TERGITOL TMN-6. 
     
     
         17 . A method for recovering oil, the method comprising:
 injecting a microemulsion into a subsurface geological formation, the microemulsion comprising:
 a surfactant selected from the group consisting of:
 (a) a surfactant comprising a linear tail and having a hydrophile-lipophile balance (HLB) number between 8 and 18, 
 (b) a surfactant comprising a branched tail and having a HLB number between 8 and 18, and 
 (c) mixtures thereof; 
 
 a coupling agent selected from an alcohol with a C 3 -C 20  linear or branched hydrocarbon chain; 
 a carrier fluid selected from a terpene, hydrocarbon liquid, or natural oil; and 
 brine. 
   
     
     
         18 . The microemulsion of  claim 1 , wherein the surfactant comprises the mixture of surfactants. 
     
     
         19 . The method of  claim 17 , wherein:
 the coupling agent comprises isopropanol; and   the carrier fluid comprises d-limonene.   
     
     
         20 . A method for aquifer remediation, the method comprising:
 injecting a microemulsion into an oil-contaminated aquifer, the microemulsion comprising:
 a surfactant selected from the group consisting of:
 (a) a surfactant comprising a linear tail and having a hydrophile-lipophile balance (HLB) number between 8 and 18, 
 (b) a surfactant comprising a branched tail and having a HLB number between 8 and 18, and 
 (c) mixtures thereof, 
 
 a coupling agent selected from an alcohol with a C3-C20 linear or branched hydrocarbon chain; 
 a carrier fluid selected from a terpene, hydrocarbon liquid, or natural oil; and 
 brine.