Oil recovery process using polymer microemulsion complexes
First Claim
1. A process for recovering crude oil from a subterranean formation which comprises injecting into the formation a stabilized microemulsion system which contains a polymer-microemulsion complex in an amount effective to displace oil, said microemulsion system comprising(a) a microemulsion containing as components(1) an oil,(2) water having up to 25% by weight of dissolved inorganic salts, and(3) 0.2 to 15 wt. %, based on the microemulsion, of at least one anionic surfactant balanced to form the microemulsion, and(b) from 0.1 to 10% by weight, based on the microemulsion of a polar polymer capable of forming a polymer-microemulsion complex wherein the polar polymer has a molecular weight of from 4,000 to 5,000,000 and is selected from the group consisting of branched polyethylene oxide condensation product of polyethylene oxide, bisphenol A and epichlorohydrin and polyvinyl pyrrolidone, the polymer-microemulsion complex being characterized by a complexation energy of at least 2 Kcal/mole, driving the microemulsion system through the formation to displace oil, and recovering the resultant crude oil.
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Abstract
A process for the enhanced recovery of oil from a subterranean formation using a polymer-microemulsion complex is disclosed. The polymer is polyethylene oxide or polyvinyl pyrrolidone and interacts with the surfactant of the microemulsion to form a physical association. The resulting complex is characterized by a complexation energy of at least 2 Kcal/mole. Slugs containing the present polymer-microemulsion complexes are stable at high salinity, show reduced destabilization due to surfactant adsorption and retention by the formation, have low interfacial tensions and achieve an early banking, as well as increased displacement of crude oil.
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Citations
24 Claims
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1. A process for recovering crude oil from a subterranean formation which comprises injecting into the formation a stabilized microemulsion system which contains a polymer-microemulsion complex in an amount effective to displace oil, said microemulsion system comprising
(a) a microemulsion containing as components (1) an oil, (2) water having up to 25% by weight of dissolved inorganic salts, and (3) 0.2 to 15 wt. %, based on the microemulsion, of at least one anionic surfactant balanced to form the microemulsion, and (b) from 0.1 to 10% by weight, based on the microemulsion of a polar polymer capable of forming a polymer-microemulsion complex wherein the polar polymer has a molecular weight of from 4,000 to 5,000,000 and is selected from the group consisting of branched polyethylene oxide condensation product of polyethylene oxide, bisphenol A and epichlorohydrin and polyvinyl pyrrolidone, the polymer-microemulsion complex being characterized by a complexation energy of at least 2 Kcal/mole, driving the microemulsion system through the formation to displace oil, and recovering the resultant crude oil. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
- 9. The process of claim 7 wherein the sulfate has the formula
- space="preserve" listing-type="equation">[R.sup.4 --O--SO.sub.3 ].sup.⊖
Y.sup.⊕
where R4 is C8 to C25 aliphatic, C14 to C38 alkylaryl or R5 --(OCH2 CH2)n where R5 has the same definition as R4 and n is an integer from 1 to 60, and Y is hydrogen, alkali metal cation or N(R3)4.sup.⊕
where each R3 is independently hydrogen, alkyl of 1 to 4 carbon atoms or hydroxy alkyl of 1 to 4 carbon atoms. - space="preserve" listing-type="equation">[R.sup.4 --O--SO.sub.3 ].sup.⊖
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10. The process of claim 6 wherein the mixture contains dodecylxylene sulfonate or dodecylbenzene sulfonate as the anionic surfactant.
- 11. The process of claim 6 or 10 wherein the nonionic cosurfactant is an ethoxylated C8 to C25 alkanol or an ethoxylated phenol of the formula
- space="preserve" listing-type="equation">(R.sup.6).sub.r --A--[O(CH.sub.2 CH.sub.2 O).sub.p ].sub.q H
where R6 is C1 to C24 alkyl, A is benzene, P is 2 to 60, q is 1 or 2 and r is 1 to 5 with the proviso that when R is 1, R6 is at least C8.
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23. A process for recovering crude oil from a subterranean formation which comprises injecting into the formation an aqueous solution containing from 0.25 to 5 wt. % of a polar polymer having a molecular weight of from 4,000 to 5,000,000 and selected from the group consisting of branched polyethylene oxide condensation product of polyethylene oxide, bisphenol A and epichlorohydrin and polyvinyl pyrrolidone, a microemulsion containing an oil, water having up to 25 wt. % of dissolved inorganic salts and from 0.2 to 15 wt. % of at least one anionic surfactant balanced to form the microemulsion whereby a polymer-microemulsion complex is formed in-situ, said complex being characterized by a complexation energy of at least 2 Kcal/mole, driving the polymer-microemulsion complex through the formation to displace oil and recovering the resultant oil.
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24. A process for recovering crude oil from a subterranean formation which comprises injecting into the formation a stabilized microemulsion system which contains a polymer-microemulsion complex in an amount effective to displace oil, said microemulsion system comprising
(a) a microemulsion containing as components (1) an oil, (2) water having up to 25% by weight of dissolved inorganic salts, and (3) 0.2 to 15 wt. % based on the microemulsion of at least one anionic surfactant balanced to form the microemulsion, and (b) from 0.1 to 10% by weight, based on the microemulsion of a polar polymer capable of forming a polymer-microemulsion complex wherein the polar polymer is a branched polyethylene oxide condensation product of polyethylene oxide, bisphenol A and epichlorohydrin having a molecular weight of from 10,000 to 500,000, the polymer-microemulsion complex being characterized by a complexation energy of from about 5 to 15 Kcal/mole, driving the microemulsion system through the formation to displace oil, and recovering the resultant crude oil.
Specification