CA1141146A

CA1141146A - Oil recovery by fluorochemical surfactant waterflooding

Info

Publication number: CA1141146A
Application number: CA000327831A
Authority: CA
Inventors: Thomas W. Cooke
Original assignee: Ciba Geigy Investments Ltd
Current assignee: BASF Schweiz AG
Priority date: 1978-09-22
Filing date: 1979-05-17
Publication date: 1983-02-15
Also published as: GB2031482A; JPS5542996A; DE2922928C2; NO791889L; NO149557B; FR2436778B1; MX151129A; DE2922928A1; FR2436778A1; JPS621071B2; IT1117222B; AU4761279A; BE876801A; IT7949325A0; AU529095B2; FR2436874A1; NL7904448A; GB2031482B; BR7903621A; NO149557C

Abstract

61-12042/CGC 872/+

Oil recovery by fluorochemical surfactant waterflooding Abstract of the Disclosure The instant invention relates to the recovery of oil from sub-terranean oil reservoirs involving the injection of an aqueous based liquid containing a fluorochemical surfactant possessing an oleo-phobic-hydrophobic fluoroaliphatic group, a hydrophilic group and an oleophilic group, optionally in conjugation with a conventional en-hanced oil recovery surfactant.

Description

61-12042/CGC 872/+

Oil recovery by fluorochemical surfactant waterfloodinz In the recovery of oil fro~ oil-bearing reservoirs, it is or-dinarily possible to recover onlya minor portion of the original oil in place by the so-called primary recovery methods which utili~e only the natural forces present in the reservoir. In order to increase oil - recovery over that economically recovered using suck natural forces, a variety of enhanced recovery techniques have been developed. One of the most widely used enhanced recovery techniques involves the use of waterflooding. The water is ordinarily injected into the reservoir to push the crude oil toward producing wells. The amount of oil re-covered by water flooding depends upon such factors as interfacial tension between the water and the crude oil, the relative mobilities of the crude oil and the water, and the wettability characteristics of the rocks holding the oil in the reservoir.

In order to increase the effectiveness of the waterflooding techniques, surfactants have been added to the water. The surfactant lowers the surface tension of the aqueous liquid and the interfacial tension between the aqueous liquid and the petroleum and increases the water-~etting properties thereof thereby reducing the capillary forces in the subterranean formation being treated. This aids in dis-lodging the oil from the subterranean sand and rock for~ations. Most ~^

' .
,

-2-commonly, aqueous compositions containing petroleum sulfonates havo been used advantageously in combination with controlled amounts of NaCl. Also, sodium carbonate and/or sodium tripolyphosphate may be added to such composition as an adjuvant in protecting the petroleum sulfonate surfactant from loss due to precipitation reactions with divalent cations. ~oreover, the use of thickeneing agents has been proposed in order to increase the sweep efficiency of the water flood.
One water flood technique involves the use of a preflush or condi-tioning slug, to minimize the amount of divalent cations (e.g., Ca Mg ) which would precipitate or absorb the surfactant, a surfactant containing slug to loosen and dislodge the oil from the sand and rock, and a mobility buffer slug, which can be used to push against the surfactant system.

The preflush or conditioning slug is free fro~ cations which would impair the surfactant and may contain, in part or whole, solutions of sodium carbonate and sodiu~ tripolyphosphate and the like. Optionally NaCl brine may be then injected to optimize the salt concentration for optimum sufactant performance. The sodium ions also displace the calcium and magnesium ions. Strong acid may be used to break up carbonate rock formation. After injection with the aqueous surfactant solution, the mobility buffer slug is injected. The mo-bility buffer usually contains a water soluble polymer such as poly-acrylamide or a bio-polymer (e.g., natural gums).

Subsequent to the injection of the mobility buffer or control slug, a driving fluid is injected in order to displace the previously injected fluids through the sand or rock formation. The nature of the driving fluid is not critical and may, for example, be locally available water. The driving fluid should not, however, be incompa-tible with the subterranean formation. In one embodiment of the aforementioned technique using a preflush slug, surfactant slug and mobility buffer slug, the surfactant slug is in the form of an aqueous microemulsion of oil, in combination with petroleum sulfonates, ' -, .

co-surfactants, such as alcohols and electrolytes.

In accordance with the present invention, there is provided a method of treating subterranean formations to stimulate the flow of oil therefrom, and surfactant compositions for use in such treatments.

More particularly, the present invention relates to a method of oil recovery from subterranean r~servoirs, by injection of an aqueous surfactant compositions to dislodge oil from said reser-voirs, wherein the surfactant is a compound of the formula (1) Rf~Zm~A~Qn RHC

wherein Rf is a hydrophobic-oleophobic fluoroaliphatic group of 4 to 24 carbon ato~s, æ is a divalent linking group, A is a divalent hydro-philic organic radical, Q is a divalent linking group, ~ C is an hydrophobic-oleophilic aliphatic radical of 6 to 24 carbon atoms, or an araliphatic radical of at least 9 carbon atoms, and m and n are independently O to 1, said fluorochemical surfactants are those which correspond to the above formula and provide a solubility in water at 30C of at least 0.01% by weight, exhibit a surface tension of less than 30 dynes/cm at 0.1% by weight actives in deionized water, and exhibit an interfacial tension of less than 12 dynes/cm at 0.1~ by weight actives in deionized water, measured against cyclohexane.

Optionally the aqueous surfactant composition contains further surfactants e.g. of the non-fluorinated type, which are anionics, mixtures of anionics and nonionics or cationics. The solubility of the eligible surfactants in deionized water may be less than that con-centration used (0.1% by weight in deionized water) n measuring sur-face and interfacial tensions. In such cases, the measurements are done in a saturated heterogenous aqueous system containing 0.1~ of the fluoroaliphatic surfactant in deionized water.
:
,. ~

' ' :

Preferably, the fluoroaliphatic surfactant exhibits a surface tension at 0.1% actives in deionizecl water of about 16 to 28 dynes/cm and an interfacial tension of less than 12 dynes/cm for example of about 4 to 10 dynes/cm in deionized water, measured against cyclo-hexane.

The fluoroaliphatic surfactants ordinarily contain at least 2 to 50% fluorine by weight, and preferably 5 to 35% fluorine by weight.

The Rf radical is advantageously a straight or branched chain perfluoraliphatic radical which contains 4 to 24 carbon atoms and may be interrupted by oxygen.

In a preferred embodiment, the Rf group is straight or branched chain perfluoralkyl of 4 to 20 carbon atoms, straight or branched chain perfluoroalkenyl of 4 to 20 carbon atoms, or straight or branched chain perfluoroalkyl-polyperfluoroalkoxy-perfluoroalkylene of up to 24 carbon atoms.

Suitable Rf groupF are those having the following formulae:

(2) CnF2n ~ 1 where n is 4 to 20;
.

(3) CnF2n~-~1 where n is 4 to 20;
:
and

(4) C F O(C F -0) C F-m 2m + 1 p ?.p q r 2r where m is 1 to 3, p is 2 to 4, q is 0 to 6, and r is 1 to 10, with the p~oviso that m + p ~ q ~ r is at least 4.

,, :

.

Suitable Rf groups of formula (2) are CF3(CF2)x- where x is 3 to 19 and mixtures thereof, as well as those of the type CF3\
: F /CF~CF2 2 and mixtures thereof.

Suitable Rf groups of formula (3) are those of the type CF3(cF2)o-8-cF=cF(cF2 ~ and mixtures thereof, as well as branched chain analogs such as Exemplary Rf groups of formula (4) are those of the type ~CF-O~CF2~

CF3-OtCF2CF2o ~ CF ~

-O~CF2CF2CF20)1-5)CF ~ 4' and /CF(o-cF2-cF ~ O

and mixtures thereof.
~"

. ~ .

The Rf radical may also contain substituents other than fluorine, such as chloro and hydrogen. However, ordinarily not more than 20~
of such substituents should be other than fluorine in order for the radical to maintain its hydrophobic-oleophobic character.

Suitable Rf radicals containing such other substituents include the following H( 2 ~ 0;

Cl Cl CF~ CF ~ CF-CF(CF ~

wbere a is 0 to 8, and b is 0 to 8, with the proviso that (a + b) is between 2 and 16.

The nature of the divalent linking group Z, when present, is not critical as long as it performs the essential function of convalently bonding the fluoroaliphatic group, Rf, to the hydrophilic organic ra-dical A.

Thus, Z may, for example, be selected from the following -cl-C6 alkylene-, -phenylene-, -(Cl~C6-alkylene)-Rl-(l-C6-alkyl2ne)-, - (Cl-C6-alkylene) -Rl), -Rl- (Cl-C6-alkylene)-, -Rl-(Cl-C6-alkylene-Rl)~, 1 ' -Rl-phenylene-(Cl-C6-alkylene-Rl)-, -Rl-phenylene-, or -phenylene-Rl wherein, in each case, said alkylene and phenylene are independently unsubstituted or substituted by hydroxy, halogen, nitro, carboxy, Cl-C6-alkoxy, Cl-C6-alkanoyl, Cl-C6-carbalkoxy, Cl-C6-alkanoyloxy or Cl-C6-alkanoylamino. The alkylene radical may be straight or branched chain.

Rl and Rl independently represent -N-, -CO-, -NR2CO-, -CONR2-, 1l -NR2CO-, OCONR2-, -O-, -S-, -SO-, -S02-, -NR2S02-, S02NR2-~ -~1R2CONR2-, 1l 10! 1l O
-NR2-S02-NR2-,-CO-, -OC-, -S020-, -OS02-, -OS020-,-OCO-,-OP-O-, O n O
Il ~ 11 _p_, -P-O- or ~O~P-O 9 O ~ o 3 R2 is hydrogen, Cl-C6-alkyl or Cl-C6-alkyl substituted by:
C -C -alkoxy, halogen, hydroxy, carboxy, Cl-C6-carbalkoxy, Cl-C6-al-kanoyloxy or Gl-C6-alkanoylamino.

In addition, Z may contain a cycloaliphatic or heterocyclic ra-dical.

Thus, for example, Rl may additionally represent R
6 COR~
~here R3 is -OR2, -OM where M is hereinafter defined, or -NHR2;
lR2 R4 ls -O- or -N-; and R5 is hydrogen, halogen, Cl-C6-alkyl or Cl-C6-alkoxy; or Rl is 4~

COR
-S~

~S~, -S O

~ ~ ~ N- ; or : ~ R

~: O

~ O

5 ~ ~ /
: ~: O

Suitable hydrophilic radicals A are for example, those hydrophi-lic divalent radical of the following formulae:

~CH2CH-O~

wherein R6 is hydrogen; or a mixture of hydrogen and ~ethyl, with the , . . . .

- : ;

proviso that such R6 are predominantly hydrogen;
OH
2CHts ~~ 2 2 l~s where R7 is hydrogen, lo~er alkyl or hydroxyethyl;

~CH2CH3--wherein R7 is hydrogen or hydroxyethyl;

~tCH2~1H~s 0~

Rl 8 X ~) -c4-alkYlene N )t where t is 1 to 3 and R8 is lower alkyl, hydroxy-lower alkyl or ~; t~2CH20)sH;

2-C ~
2)t T

where t is 1 to 3 and T is -S03M, -COOM, -P03M, -OS03M o~ -OP03M
and M is hydrogen, a~monium or an alkali metal cation; or : :

. ' . ~
,: . ' ' ~CH2 ICH~

~C~N~Rll X ~1 U
Rlo wherein R~, Rlo and Rll are independently hydrogen; Cl-C4-alkyl or c2-C4-alkyl substituted by hydroxy, Cl-C4-alkoxy or hydroxy-C2-C4~
al'~oxy; and one of Rg and Rlo may additionally represent benzyl; u is 0 or 1;

Rll is additionally Cl-C6-alkylene substituted by sulfo or carboxy; X is an acetate, halo, methosulfate or hydroxyl anion where u is 1 and Rll is other than said Cl-C6-alkylene; and t is 1 to 3.

In each of the above formulae where mentioned, s is 2 to 60, preferably 5 to 25.

Mixtures of the afore-mentioned hydrophilic radicals may be present.
:
; Also conte~plated are hydrophilic divalent radicals wherein atleast a portion of the hydrophilic character is due to a pendant group : such as divalent radical of the formulae:

) n CH2cH2-N-~ CH2CH20~-- H
where nl is 0 to 20 and n2 is 1 to 20;

¦CH2cH2)n H
CH20~1 CH2CH2-1 (C2-C9-alkylene)~(CH2CE~20 ( CH2CH20 ) n H

i --ll--where nl and n3 are independently O to 20 and n2 and n4 are indepen-dently 1 to 20;
~C2~,0)n5(C3H60~ C3H60)n6(C2H40'n5H

~*C2~340)n5(C3H60~ L~C3H60)n6(C2H4 ~5 wherein n5 is independently 2 to 20 and n6 is independently 1 to 10;

or C4 alkylene)yl-Ci (cl-c4-alkylene OCH2CH ~ OH

where R14 is hydrogen, Cl-C4 alkyl, or (OCH2CH2) OH; Yl and Y2 are independently O to 4; y3is 1 to 33 and n2 and n4 are independently 1 to 20.

Q is a divalent linking group, and, like Z, is not critical as long as it performs the essential function of covalently bonding the hydrophilic organic radical A to the hydrophobic-oleophilic group ~ C

Thus, the linking group Q is independently selected from those groups recited supra for Z, with the proviso that when Rl or Ri are directlybonded to A, and A terminates in an oxy or amino ligand; and Ri in this position is other than O O O O
Ii 11 . . Il 11 -S-, -O-C-O-, -OC-, -OSO2-, -OSO3-, -OP-O-, -O-P- or -O-.
OR . O

i5 a hydrophobic-oleophilic, aliphatic or araliphatic mono-valent group.

Suitable ~ C groups include hydrophobic-oleophilic higher alkyl or alkenyl or 6-24 carbon atoms, which are unsubstituted or substi-tuted by: chloro, bromo, alkoxy of up to 18 carbon atoms, nitro, alkanoyl of up to 18 carbon atoms, alkylmercapto of up to 18 carbon atoms, amino, Cl-C18-alkylamino or di-Cl-C18-alkylamino.

Preferably, ~C is said alkyl or alkenyl of at least 8 carbon atoms. The alkyl and alkenyl groups may be straight or branched chain.
Mixtures thereof may be used.

In addition, the ~C group may be a group of the formula ~CH2-CH-O ~ CH2CH-OR6 wherein R5 is Cl-C6-alkyl, n7 is 5 to 20, and R6 is hydrogen or alkyl of up to 24 carbon atoms.

Moreover, the ~C group may be a hydrophobic-oleophilic arali-phatic radical of at least 9 carbon atoms.

Suitable such groups include those of the formula:

C6-alkyiene~ ~R15 where n8 is 0 to 1;

R15 is alkyl of up to 20 carbon atoms, alkoxy of up to 20 car-bon atoms, alkanoyl of up to 20 carbon atoms, mono- or dialkylamino - of up to 20 carbon atoms, alkylmercapto of up to 20 carbon atoms, alkanoyloxy of up to 20 carbon atoms, or carbalkoxy of up to 20 carbon atoms;

Rl6 is hydrogen, halogen, nitro or R15.

Also contemplated are hydrophobic-oleophilic groups of the for-mula ~Cl C6~alkYlene ) n ~R16 where n8, Rl5 and R16 are defined as above.

In addition, the group -Qn-REC where n ls 1 may represent a group of the formula (C2~C4-alkylene)-N\

wherein R17 and R18 are independently higher alkyl groups of 6 to 24 carbon atoms, or the group ~C2-C6-alkylene~ 0-CHCOOR19 wherein R19 and R20 are higher alkyl of 6 to 24 carbon atoms.

Preferred compounds are those which are substantially nonionic;
i.e., free from strongly acidic groups, such as -S03H and -P03H and free from strongly basic quaternary a~monium groups.

, Amongst such preferred substantially nonionic surfactants especially highlighted are those which both exhibit a surface tension at 0.1% actives in deionized water of about 1 to 28 dynes/cm, provide a solubility in water of at least 0.01% by weight, exhibit an inter-facial tension of less than 12 dynes/cm at 0.1~ by weight actives in deionized water measured against cyclohexane and wherein the correspon-.~ ,.
ding hydrocarbon surfactant RHC-Q -A-OH, has an apparent HLB (hydro-~ , ' :

.

philic-lipophilic balance) in the range of about 5 to 24, and pre-ferably in the range oE about 12 to 18.

The HLB of a substantially nonionic hydrocarbon surfactant is a well known indication of the percentage weight of the hydrophilic portion of the nonionic hydrocarbon surfactan~ molecule. See, for e~ample Ind. and Eng. Chem., Anal. Ed. Vol. 18, page 500 (1946).

An especially preferred class of fluorochemical surfactants are those of the formula (5) Rf~Zm(CH2CH20)sQn ~C

wherein Rf straight or branched claim perfluoroalkyl of 4 to 20, es-pecially of 4 to 12 carbon atoms, RHC is alkyl of 6 to 24, preferably 12 to 18, carbon atoms or ¦ ~ 21 where R21 is alkyl of 3 to 20, preferably of 6 to 12 carbon atoms and R22 is hydrogen, halogen (chloro9 bromo, fluoro), nitro or R21;
m is O or l; s is 5 to 30; Z is -COO-, -S03-, -O-, -Cl-C4-alkylene-COO-, -Cl-C4-alkylene-S03~ COOH
-Cl-C4-alkylene-S-CH-CH2COO-, or -Cl-C4-alkylene-S-CH2CHCH~O-; n is O or l; and Q is -CO or -S02.
OH
Preferred are those compounds of formula (5), wherein Rf~ RHC
and s have the indicated meanings and m and n are zero.

Preferred are also those compounds of formula (5) wherein Z is -Cl-C4-alkylene-S-CHCOOH such as of the formula

(6) R -CH CH-S-CH-COOH
CH2-CoO(CH2cH20) SRHC
or wherein Z is -Cl-C4-alkylene-S-CH2-CH-CH20 OH
such as the formula

(7) Rf-CH2-CH2-SCH2-CH-CH2-0(CH2 CH2 )s ~IC
OH
wherein Rf~ ~C and s have the meanings indicated above.

The fluorochemical surfactants used in accordance with the in-stant invention can be prepared according to known procedures. Thus, for example, the fluorochemical surfactants can be prepared by reac-ting known hydrocarbon surfactants of the formula ~ C Qn A OH or RHc-Qn-A-NH~2 with a fluoroaliphatic acid halide in an inert solvent.
: ~ ~
For example, CF3~CF2)7S02F, prepared according to US Patent Specification 2,759,019 can be reacted with H(OCH2CH2)5 20 N(stearyl)2 in diethyl ether as a solvent vehicle and pyridine or triethylamine as acid acceptor, to yield the corresponding ester of the formula CF3(CF2)7S02(0CH2CH2)2o Ntstearyl)2.

Analogously, n-C3F70CFtCF3)COF as disclosed in Canadian Patent Specification 725,740, can be reacted with octylphenoxy-poly(ethylere-oxy) ethanol having an average molecular weight between 514 and 778 in the presence of diethyl ether and pyridine as acid acceptor to ; yield the corresponding ester.

:: :
Alternat:ively, alpha-perfluoroalkene of the formula CnF2n_l where n is 6-20 can be reacted with a hydrocarbon surfactant of the formula , , `

4~

-RHC-Qn-A-OH in the presence of potassium carbonate in an inert solvent, such as methyl ethyl ketone or acetone at a temperature of 20-70C, to yield the corresponding fluoroaliphatic ether For example, an oleic acid-ethylene oxide condensate (molecular weight of about 680) can be reacted with tetrafluoroethylene pentamer in the presence of potassium carborlate in acetone to yield a product of the formula CloFl9o(cH2cH2o)lococlsH29 Lf a mi~ture of cetyl/oleyl-ethylene oxide condendate is used (molecular weight of about 550), the corresponding cetyl/oleyl ether product is obtained having the formula CloF19(CH2CH2)10C16 31/33 Such compounds and their preparation are disclosed in British Patent Specification 1,371,054.

. .
Alternatively, fluoroaliphatic isocyanates and carbamic acid halides can be reacted with hydrocarbon surfactants of the formula -Qn-A-OH or ~HC-Qn-A-NHR2 to yield the corresponding urethanes and ureas, respectively. The reactions are advantageously carried out in the presence of an inert medium at temperatures of 20 to 50C.
Where the fluoroaliphatic carbamic acid halide is a reactant, a ter-tiary amine, such as triethyl amine or pyridine, lS advantageously added to promote the reaction and remove the hydrogen halide formed.

For example, l,l-dihydroperfluorooctyl carbamyl chloride, of the formula C7F15CH2~COCl, prepared in accordance with German Patent Specification ljl45,606, is added slowly to ethoxylated (15 moles) coco fatty acid in diethyl ether, in the presence of triethyl amine as an HCl getter, while stirring. The resulting product has the formula C7F15CH2NHC00-~CH2CH2-O ~ C0~ c, where ~C is the coco fatty acid hydrocarbon residue.

Similarly, CF3(CF2)6NC0, prepared in accordance with US-Patent Specification 2,617,817, can be reacted with a stearic or lauric acid amide-ethylenimine (4 to 6 mole~ condendate, such as those described -17~

in US-Patent Specification 2,163,807 for example, in an inert diluent to form a product of the formula CF~(CF2)6NHCO(NHCH2CH2 ~ NHC0- ~ C
wherein ~ C is the hydrocarbon resiclue of stearic or lauric acid.

The product can be neutralizecl with aqueous HCl or H2S04 to obtain the corresponding salts, or can be alkylated with dimethyl-sulfate or a methyl halide, such as methyl bromide to form the ter-tiary and quaternary ammonium derivatives thereof. Alternatively, the product can be reacted with ethylene oxide7 e.g., in amounts of 4 to 15 moles per mole of product, to form the ethoxylated derivatives thereof, in the presence of an HCl catalyst.

Analogously, phosgene can be reacted with nonionic hy~rocarbon surfactants of the for~ula RHC-~hA-OH to form the corresponding chloroformate and the acid chloride reacted with a fluoroaliphatic alcohol or amine to form the corresponding carbonate or urethane, respectively. Advantageously, the reactions are conducted in the pre-sence of a tertiary amine, such as triethylamine, and an inert di-luent.

For example~ C12H25S(CH2CH20 ~oHs can be reacted with phosgene in the presence of triethyl amine to yield the corresponding acid chloride, C12H25S(CH2CH20)1oCOCl, which in turn, is reacted with a fluoroal p t c a o ( 3)2 F2 2 2C 2 ONm(CH2)30H, disclosed in US-Patent Specification 3,697,564, in the presence of triethylamine in diethyl ether to yield a product of the formula (CF3)2CF0-CF2CF2CH2CH2CONH(CH2)30CO(OCH2CH ~ oS~C12H25.

Li~ewise, CloFlgOC6H4S02Cl, as described in ~ritish Patent Spe-cification N^s. 1,130,822 and 1,270,662 can be reacted with polyoxy-ethylene (20) sorbitan monolaurate in the presence of triethylamine in an inert diluent to obtain the corresponding ester.

r. _ Advantageously, the ~luorochemical surfactants can be made by reacting a hydrocarbon surfactant of the formula RHC-Q -A-OH with an equimolar amount of toluene diisocyanate to form the 1:1 urethane adduct thereof, and reacting the urethane monoisocyanate with a poly-fluoro aliphatic amine or alcohol.

Thus, nonylphenoxypolyethoxyethanol having an average of 4 moles of ethylene oxide CQn be reacted with one mole of toluene diisocyanate to form the corresponding L:l adduct, which, in turn is reacted with a perfluoroalkylalkylamine of the formula C8F17(CH2~5NH2, which can be prepared in accordance with US-Patent Specification 3,257,407, to form the corresponding urea derivative.

Analogously, many fluorochemical surfactants of the formula Rf-Z A-OH can be reacted with snitable aliphatic or araliphatic acid halides, isocyanates, and the likes, to form suitable fluorochemical surfactants for use in accordance with the instant invention.

For example, C8F17S02N(C2E15)-CHzCH2(0CH2C 2)10 in US-Patent Specification 2,915,554, can be reacted with dodecylben-zenesulfonyl chloride in diethyl ether in the presence of triethyl-amine to yield the corresponding sulfonate ester.

Useful surfactants for use in accordance with the instant in-vention can also be prepared by reacting a fluoroaliphatic thiol with an ethylenically unsaturated dicarboxylic acid anhydride, and reacting the resulting anhydride condensate with an equimolar amount of hydro-carbon surfactant of the formula E~HC-Qn-A-OH or RHC-Qn-A-NH2, to ob~
tain the resulting half ester or half amide, respectively. Alternatively, the ethylenically unsaturated dicarboxylic acid anhydride can be react-ed with an equimolar amount of hydrocarbon surfactant of the formula RHC-Qn-A-OH or E~C-Q-A-NH2, for example, and the reaction product re~
acted with a fluoroaliphatic thiol.

, For example, dodecylphenoxypo:Lyethoxyethanol (containing 9 moles of ethylene oxide) can be reacted with an equimolar amount of maleic anhydride in an inert diluent, such as sulfolane, to yield the corresponding half ester of the formula:
,~COOH
- ( ) HC
HC
\coo(cH2cH2o)9--C6H4 C12H25 The half ester can then be reacted with a fluoraliphatic thiol, such as CgFlgC2H4SH, obtained according to US-Patent Specifications 3,172,910 and U.S. 3,088,849. m e reaction is advantageously carried out in substantially stoichiometric amounts in aqueous ethanol in the presence of small amounts of sodium hydroxide and a tertiary amine, such as piperidine, at from 20 to 75C, to form, for example, a pro-duct of the formula:
COOH ..

-S-CH
'CH-coo~cH2cH2ot-9c6H4 C12H25 Analogously the compound of the formula CgF19CH2CH2SCHC0 ( 10) CH2C/

prepared in accordance with US-Patent Specification 3,471,518 can be reacted with the compound of the formula H(ocH2cH2)6 CI~I 500C8 17 (11) -4~

- disclo8ed in US-Patent Specification 2,341,846, by refluxing equimolar amounts in dioxane to produce thc corresponding half ester.

Likewise, the compound of the formula f 2 2 (12) C

o where Rf is a mixture of C6-C10 perfluoroalkyl, prepared by reacting norbornene anhydride and Rf CH2CH2SH in the presence of a small amount of an azobutyronitrile as catalyst, can be reacted with 3-(n-dodecyl-amino)propylamine in equimolar amounts at temperatures of 20 to 50C
in an inert diluent such as toluene and dehydrate the product by azeotropic distillation of~water to yield the corresponding imine9 which, in turn can be ethoxylated with 10 moles of ethylene oxide in an aqueous acidic medium to yield a product cf the formula:
O
;~ RfC 2C 2 C ~ r (cH2cH2o)loH
(13) ~ N-C32C32C l2N-(c~2)ll 3 O
Some of the fluorochemical surfactants which can be used in accordance with the instant invention are known compounds.

Suitable fluorochemical surfactants as defined above and used in accordance with the instant invention can readily be prepared from known starting materials by conventional techniques, such as those illustrated above, and as further illustrated in the following examples.

:~

~21~

Advantageously, the fluorochemical surfactants are used alone in an aqueous system or in cambination with a conventional water-flooding surfactant. Such surfactants for enhanced oil recovery are well known and include anionic surfactants, such as petroleum sul-fonates, synthetic alkyl aryl sulfonates and the like, anionic-non-ionic surfactant systems, such as those disclosed in US-Patent Speci-fications 3,811,504, 3,792,731 and 4,005,749, and cationic surfactant systems.

Mixtures of cationic and anionic surfactants are generally to be avoided as they may be incompatable due to interaction.

The total amount of surfactant based upon the aqueous medium may vary within wide limits, e.g., between 0.01 and 40 weigth percent, or-dinarily 0.05 to 20 weight percent. When using a mixture of fluoro-chemical surfactant according to the instant invention and a conven-tional waterflooding surfactant, ordinarily there is present at least 1%, preferably at least 4%, of the fluorochemical surfactant, based on the amount of non-fluorochemical surfactant.

The aqueous surfactant slug may also advantageously contain suitable co-surfactants such as aliphatic or alkyl aryl alcohols having a molecular weight of 40 to 220 in amounts of up to 10% by volume of the solution. A monovalent salt may also be present in the aqueous medium in amounts up to 5% by weight based upon the aqueous medium for purposes of salinity control.

Various thickening agents, such as guar g~m or polysaccharide, and sacrificial agents, such as inorganic polyphosphates or alkali metal carbonates, may al50 be present.

In one embodiment of the invention, the surfactant slug may be in the form of an aqueous petroleum oil emulsion containing 0.5 to 40% by weight of oil, based upon the weight of the aqueous phase.

~' : ~ , .

In a further embodiment of the invention, the terminal portion of the aqueous surfactant slug, or aqueous petroleum oil emulsionJ
exhibits a lower concentration of non-aqueous ingredients than the initial portion injected into the reservoir from which the oil is recovered. The use of such a concentration gradient thus reduces the total amount of surfactant necessarg in the oil recovery procedure.

The following examples are merely illustrative of the instant invention and are not intended to limit the scope thereof. All parts are by weight unless otherwise specified.

. ~

., , . , , , :

Example l: Into a 500 ml vessel fitted with a thermometer, stirrer and nitrogen inlet, there was placed 84.2 grams (0.075 moles) of poly-ethoxylated cetyl alcohol having an average of ZO ethoxy units and having the formula ( 101 ) Cl 6H~OCH2CH~oOH

and stirred at 50-55C under a nitrogen blanket. Boron trifluoride in the form of the diethyl ether complex (47.3% BF3) was added in the amount of 0.4 grams. Then 6.1 grams of epichlorohydrin 0.066 moles) was slowly added to the mixture while maintaining the temperature at 50-60C over a period of about 10 minutes. The reaction mixture was then stirred at a temperature of 50 to 60C for an additional 30 minutes. The product formed has the formula (102) Cl-CH2CH-CH2-O~CH2CH ~ oC16H33 OH
To this reaction product there was then added 140.3 grams of anhydrous isopropyl alcohol and 27.9 grams of RfCH2CH2SH, where Rf is straight chain perfluoroalkyl having the following Rf distribution:
0 9% C F -, 32.9% C6F13-, 37-5% C8F17 , 22-99% 10 21 C12F25 (average M.W. approx.~465), and the mixture stirred at about 50C. Then 5.4 grams of 50% àqueous NaOH (0.0672 moles) were slowly added at a rate which maintained the reaction mixture at 50 to 60C.
A white precipitate of NaCl formed. The mixture was stirred for an additional hour at 50-55C and turned from colorless to pale yellow.
The solution was then filtered to ~emove byproduct NaCl. Upon drying, 73.6 grams of product (about 70~ yield) was obtained. The product has the formula (103) RfCH2CH2SCH2CHCH20~CH2CH20t~Cl6H33-OH

~ .

:
1, . ~ ~, Example 2: Using the procedure of Example 1, polyethoxylated stearyl amine of the formula / (CH2CH20 ~qH
(104) CH3(CH2)l6CH2 C~2H2 - (where q + r is 15) in the amount of 54.69 grams (0.063 moles) was reacted with 5.09 grams (0.055 moles) of epichlorohydrin in the presence of 0.3 grams of BF3;
diethyl ether complex, and the resulting reaction product reacted with 23.25 grams of the RfCH2CH2SH of Example 1 in the presence of 4.48 grams of 50% aqueous NaOH in 98.85 grams of isopropanol. The reaction product was stirred for two hours before filtering to yield - 151.47 grams amber colored hazy solution. Upon refiltering, 142.01 grams of clear amber solution was obtained. Upon drying, 46.43 grams of the product of the formula 0~ . .
. I .
(105) RfCH2~H2SCH2C}~CH ~ CH2C~2tql~CH2(CH2)l6CH3 ! (c~2cH2o)rH

were obtained.

Example 3 Using the procedure of Example 1, 264.0 grams of ethoxylated (15~ p~nonyl ~ ol having the formula (106) HO~CH2CH20 ~ -CgHlg wcre reacted with 24.42 grams of epichlorohydrin in the presence of 1.6 grams of BF3; diethylether complex and the product thereof was subsequently reacted with 111.6 grams of RfCH2CH2SH, wherein Rf has the distribution as in Example 1, in the presence of 21.50 grams of 50% aqueous sodium hydroxide and , .
.

.
" ' .

460.4 grams of isopropyl alcohol. The resulting reaction product has the formula (107) RfcH2cH2scH2lHcH2otcH2cH2o ~ ~ C9Hg OH

Example 4: Maleic ahydride, 2.55 grams and 2.55 of sulfolane as sol-vent, were added to 36.45 grams of dinonyl polyethoxylated (24) phenol of the formula (108) C9~ ~ H2CH2~24H

and stirred for 20 hours at 60C, to form a reaction mixture containing a half ester of the formula HCCOOH ~ y~C9Hl9 (109) CHCOO(CH2CH20 ~ ~
::
Cg~lg :
To this reaction mixture th&re was then added 0.1 grams of tri-- ethylamine and 11.63 grams of RfCH2CH2SH having the Rf distribution as in Example 1 under a nitrogen blanket and the mixture stirred at 60C for about 7 hours. The product has the formula :
; (110) RfCH2CH2S-CHCOOH ~ CgHlg CH2COO(CH2CH20 ~
CgHlg Example 5: In order to measure the ef~ectiveness of fluorochemlcal surfactant in dislodging oil from an oil hearing subterranean formation by increasing the effectiveness of the aqueous medium, the following screening technique was used:
Procedure: 20 g of a sand-oil mixture (10% A.S.T.M. oil No. 3 and 90%
Ottawa standard sand 20-30 mesh) are placed in a 25 x 150 mm test tube.The test solution (25 ml at 0.1% actives of sample in deionized water) is carefully laid over the sand-oil mixture. The system is then allowed to stand, undisturbed, for 18-20 hours. Any oil that percolates to the surface is drawn off with a pipette and weighed. Results are reported as percent recovered (i.e., the weight of oil recovered compared to the theoretical maximum of 2.0 g oil in the tube). 3 to 5 runs are done for each sample for an average value.

In the following Tables, the compounds were screened at 0.10%
actives in deiGnized water; surface tensions and interfacial tensions were measured against cyclohexane. Except where otherwise indicated9 the Rf distribution in the perfluoroalkyl surfactants were: 0.9% C4F9-, 32.9% C6F13-, 37.5% C8F17-, 22.9% CloF21~, and 5.3% C12F25-.

, Table 1 Compounds of the formula (111) RfcH;~cH2sc~2cHcH2o~cH2cH2o~RHc, OH
prepared in accordance with the procedure set forth in Example 1 to 3.
~' .
j Approx. Percent Surface Interfacial No. Value RHC Oil Re- Tension Tension of s _ covered (dynes/cm) (dynes/cm) 1 15 ~ C9H1961.4 24.09 6.2 .
2 20 16 33 52.0 22.6 6.5 ; 3 20-C18H37 46.8 20.7 7.0 4 1513 27 36.7 19.9 6.0 R
S ~OCH2CH ~ N-tCH2CH2o)rH 69.8 25.6 7.3 q+r=15, R~stearyl 6 24 ~~ C H40.2 22.3 5.4 C9Hlg 7 5 ~ CgH19 10.2 20.7 18.6

8 11 ~ -C9~19 46.0 23.4 10.7

9 20 ~ -C9H19 35.4 20.7 5.0 ~-CgHlg~ 27.0 24.9 5.5 : ' .

:.
:~ ' ` : ` ' !Table 2 ,Compounds of the formula ,~ (112) RfCH2CH2SCHCOOH
CH2coo (CH2CH2o) SRHC

prepared in accordance with procedures set forth in Example 4.

Approx. Percent Surface Interfacial No. Value RHC Oil Re- Tension Tension of s covered (dynes/cm) (dynes/cm) ' 11 24 ~ ~ 44.7 29.2 6.6 ~C9H19 12 20 18 37 68.1 27.1 5.1 ,. _ ,.
~ 13 15 \ /- C9H19 86.9 24.2 7.1 =~

14 1) 20 \ / CgHlg 59.9 26.3 5.3 ~ 15 5 ~ -C9Hl9 36.6 24.5 7.5 ; R
2 2 q 2 2 r q~r=15~ R=stearyl I) Rf=25~ C6Fl3-, 50~ CBFl7-, 25~ CloF2l~

:

, G

Example 6: In the following table, formulations of various hydrocar-bon surfactants with representative fluorochemical surfactants and their effectiveness in dislodging oil according to the procedure set forth in Example 5 are given. In the following table, hydrocarbon surfactant ~ is a commercial anionic sulfate surfactant (Conco EL-30-Trademark); hydrocarbon surfactant ~ is a polyethoxylated nonyl-phenol nonionic surfactant (Igepal C0-710-Trademark); and surfactant ~ is petroleum sulfonate anionic surfactant (Petronate L-Trademark).

Table 3 .

~ctives in No solution % oi_recovered A 0-09% - l9.S
B 0.09~ 51.7 C 0.10~. 8.1 0 . 01~ 13 . S
0.01% 45.6 13 0.01~ 31.2 0.01% 34,9 A 0.09~
0.01% 57.S
B 0. 09%
: 5 0.01~ 1302 C 0. 09%
l 0.0l~ 28.3 A 0.09%
l ~.01~ 37.5 B 0.09 l 0.01~ 12.2 C O . 09%
'` .

No. Acti~es in % oil recovered solution 13 0.01% 29.2 A 0.09%
13 0.01% 67.0 B 0.09%
13 0.01% 14.4 C 0.09%
13 0.05% 77.9 B 0.05%

The results of the above table indicate the advantages which may be obtained using formulations oE conventional hydrocarbon surfactants coupled with the fluorochemical surfactants in tertiary oil recovery.

; ~ ~

. .
:
.

~ ,' `~ ' .

Claims

1. A method of oil recovery from subterranean oil reservoirs by injection of an aqueous surfactant composition to dislodge the oil from said reservoirs, wherein the surfactant is a compound of the formula Rf-Zm-A-Qn-RHC

wherein Rf is a hydrophobic-oleophobic fluoroaliphatic group of 4 to 24 carbon atoms, Z is a divalent linking group; A is a divalent hydrophilic organic radical; Q is a divalent linking group; RHC is a hydrophobic-oleophilic aliphatic radical of 6 to 24 carbon atoms or araliphatic radical of at least 9 carbon atoms, and m and n are in-dependently 0 or 1, said fluorochemical surfactant having a solubility in water at 30°C of at least 0.01 % by weight, exhibits a surface tension of less than 30 dynes/cm at 0.1 % by weight actives in deionized water and exhibits an interfacial tension of less than 12 dynes/cm at 0.1 % by weight actives in deionized water, measured against cyclohexane.

2. A method according to Claim 1 wherein the aqueous surfactant compositions contains in addition non-fluorinated surfactants which are anionics, mixtures of anionics and nonionics or cationics.

3. The method according to Claim 1, wherein said fluorochemical surfactant exhibits a surface tension at 0.1 % actives in deionized water of about 16 to 28 dynes/cm and an interfacial tension of less than 12 dynes/cm measured against cyclohexane.

4. The method according to Claim 3, wherein said fluorochemical sur-factant is substantially nonionic.

5. A method according to Claim 4, wherein the surfactant HO-A-Qn-RHC, corresponding to the fluorochemical surfactant Rf-Zm-A-Qn-RHC, has an apparent hydrophilic-lipophilic balance in the range of about 4 to 24.

6. A method according to Claim 5, wherein the surfactant HO-A-On-RHC
has an apparent hydrophilic-liphophilic balance in the range of about 12 to 18.

7. A method according to claim 5, wherein the fluorochemical sur-factant is of the formula Rf-Zm-(CH2CH2O)s-Qn-RHC

wherein Rf is straight or branched claim perfluoralkyl of 4 to 20 car-bon atoms, RHC is alkyl of 6 to 24 carbon atoms or wherein R21 is alkyl of 3 to 20 carbon atoms and R22 is hydrogen, halogen, nitro or R21; m is 0 or 1; s is 5 to 25; Z is -COO-, -SO3-, -O-, , or ;
, or ;

n is 0 or 1, and Q is -CO- or -SO2-.

8. A method according to Claim 7, wherein Rf is straight or branched chain perfluoroalkyl of 4 to 20 carbon atoms, RHC is alkyl of 6 to 24 carbon atoms or a group of the formula , m and n are zero, and s, R21, R22, Q and Z have the meanings indicated in claim 7.

9. A method according to Claim 7, wherein the fluorochemical sur-factant is of the formula or wherein Rf, RHC and s have the meanings indicated in claim 7.

10. Aqueous surfactant composition for carrying out the method according to claim 1 which contains 0.01 to 40 % by weight of a surfactant which is a compound of the formula Rf-Zm-A-Qn-RHC

wherein Rf is a hydrophobic-oleophobic fluoroaliphatic group of 4 to 24 carbon atoms, Z is a divalent linking group; A is a divalent hydrophilic organic radical; Q is a divalent linking group; RHC is a hydrophobic-oleophilic aliphatic radical of 6 to 24 carbon atoms or araliphatic radical of at least 9 carbon atoms, and m and n are in-dependently 0 or 1, said fluorochemical surfactant having a solubility in water at 30°C of at least 0.01 % by weight, exhibits a surface tension of less than 30 dynes/cm at 0.1 % by weight actives in deionized water and exhibits an interfacial tension of less than 12 dynes/cm at 0.1 % by weight actives in deionized water, measured against cyclohexane.

11. A composition according to claim 10 which contains in addition a conventional waterflooding non-fluorochemical surfactant.

12. Composition according to claim 11, which contains at least 1 %
by weight of the fluorochemical surfactant, based on the weight of the non-fluorochemical surfactant.