CA1225003A - Demulsification of bitumen emulsions - Google Patents

Abstract

DEMULSIFICATION OF BITUMEN EMULSIONS

ABSTRACT OF THE DISCLOSURE
A process for recovering bitumen from oil-in-water (O/W) emulsions is disclosed wherein water soluble demulsi-fiexs are used. These demulsifiers are salts of polymers and/or co-polymers of specific cationic monomers. To resolve the bituminous petroleum emulsions, the process is carried out between 25 and 160°C wherein the demulsifier of the in-vention is contacted with the bituminous emulsion.

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Description

~2~g~1D3 BACKGROUND OF THE INVENTION
Field of the Invention This invention is concerned with the breaking or resolution of oil-in-water (O/W) bituminous emulsions by treatment with salts of polymers Andre co-polymers.
Description of the Prior Art A great volume of hydrocarbons exist in known deposits of tar sands. These deposits occur at various places, the Athabasca tar sands in Canada being an example.

The petroleum in a tar sand deposit is an asphaltic bitumen of a highly viscous nature ranging from a liquid to a semi-solid. These bituminous hydrocarbons are usually char-acterized by being very viscous or even non-flowable under reservoir conditions by the application of driving fluid pressure.
Where surface mining is not feasible, the bitumen must be recovered by rendering the tar material mobile in-situ and producing it through a well penetrating the tar Rand deposit. These in-situ methods of recovery include thermal, both steam and in-situ combustion and solvent techniques. Where steam or hot water methods are used, a problem results which aggravates the recovery of the bit-men. The difficulty encountered is emulsions produced by the in-situ operations. These emulsions are highly stable O/W emulsions which are made even more stable by the usual presence of clays. Most go petroleum emulsions are water-in-oil (W/O) types. These normal W/O emulsions are broken by methods known in the art. However, the bitumen emulsions which are O/W types present a much different problem, and the same emulsifiers used in W/O emulsions I

will not resolve the O/W bitumen emulsions. The uniqueness of these O/W bitumen emulsions is described in C. W. W.
cowers, J. Caned. Petrol. Tech., I, 85-90 (1968~. (Prior art Reference A.) There is much prior art concerning the resolution of normal W/O emulsions Some of the art even mistakenly equates bitumen O/W emulsions with these W/O
emulsions. The following is a list of several art rev-erences.
B. U. S. Patent 4,238,230 discloses the breaking of an O/W emulsion by adding to the emulsion a cat ionic polyp acrylamide. This patent discloses and claims using polymers and co-polymers of monomers disclosed herein but not neutral-iced to make the salt. Our invention makes clear that in order to break bitumen emulsions which are not addressed in the patent the polymers and co-polymers of the cat ionic polyp acrylamides must be converted to the salt form, and in the case of co-polymers comprise the majority of the polymer.
The patent only breaks conventional O/W emulsions (not bit-men emulsions) and uses the polymers without conversion to salt forms. Also, the patent discloses that as the per-cent age of the cat ionic polyacrylamide portion of the co-polymer declines, the effectiveness of the emulsification increases. Surprisingly, we have found that the cat ionic polyacrylamides, whether in homopolymer or co-polymer form, must be neutralized to the salt form before they are effect-ivy on bitumen emulsions and must be the majority component in any co-polymer in order to be effective bitumen emulsion breakers.
C. U. S. Patent 4,141,854 and 4,154,698 disk - 30 close the cat ionic polyacryl~amides encompassed by our in-I

mention as co-polymers wherein the cat ionic polyacrylamides comprise less than 50% of the copolymer and are not in the salt form to break standard (not bitumen) W/O or O/W Emil-sons. We have found that these emulsion breakers are in-effective in breaking bitumen emulsions.
D. U. S. Patent 3,316,181 discloses the use of Delilah dimethylamine co-polymers for breaking O/W emulsions.
E. U. S. 3,171,805 discloses flocculating solids from sewage containing anionic surfactants by using home- or co-polymers of cat ionic polyacrylamides.
F. U. S . Patent 3,487,003 discloses separating middlings from tar sand mining streams by treating with a flocculent which includes cat ionic polyacrylamides.
We have found that the use of particular co-lo polymers or homopolymers of certain cat ionic polyacryl-asides, when used in the acid form and when comprising the majority of any co-polymer, are effective in breaking bitumen emulsions.
SUMMARY OF THE INVENTION

the invention is a method for recovering petroleum from oil-in-water bitumen emulsions by resolving or breaking these emulsions by contacting the emulsions at a temperature of between 25 and 160~C with salts ox polymers and/or co-polymers of cat ionic monomers having the general structure CH2=C-C-X-(CH2)nN

where R = H or lower alkyd, X = NH or 0, n I and Al and R2 are hydrogen or alkyd. The polymers or co-polymers must 1~2~3 have a molecular weight greater than about 2,000. Also, the above monomer is present in any co-polymer in greater than 50 wt.% of the total co~polymer composition.
The invention also includes the optional step of converting the salts of the polymers or co-polymers into in-active polymers or co-polymers by pi adjustment of the a-use phase of the broken emulsion and reinfection of the aqueous phase into a hydrocarbon containing formation to recover additional hydrocarbons or bitumen.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
Especially useful and preferred in this process are salts of polymers and/or co-polymers of cat ionic monomers represented by the general structure CH2=c-c-x-(c~2)nN -where R - H or lower alkyd, preferably SHEA, X = NH or 0, n I preferably 2 to 3, and Al and R2 = hydrogen or alkyd, preferably SHEA. In order to be effective, the polymer or co-polymer must have a molecular weight greater than about

2,000 and be in the salt form. Any copolymer must have the above monomer present in greater than 50 wt.% of the total co-polymer composition, preferably greater than 80 wit%. The salt is formed by the addition of enough inorganic or or-genie acid to the pollers to render a 1 weight per cent aqueous solution to a pi of less than 8 and preferably less than 7.
In one embodiment of this invention the monomers of the general structure given above are formed into home-polymers. In another embodiment of this invention the monk omens of the structure above are combined with acrylamide, styrenes (meth)acrylate esters, vinyl acetate, vinyl color-ides vinyl pyrrolidine, etc. to form co-polymars wherein the monomer of the structure given above is present in amounts greater than 50 wt.% of the total co-polymer composition, and preferably greater than 80 wt.% of the total co-polymer come position.
The emulsifiers of the present invention are found to cause complete, clean breaks of bitumen O/W Emil-sons at advantageously short residence times, sometimes almost instantaneously upon addition of the emulsifier as described above.
U. S. Patent 4,154,698 teaches that cat ionic co-polymers similar to those claimed in the present invention(containin~, however, only 50 wt.% or less of the amino monk omen) will break O/W emulsions only after treating the Emil-soon with ammonia to raise the pi to 9 and investing the emulsion with a surfactant. No such treatment was found necessary using the present process.
Reference A teaches that pi adjustments on bitumen in water emulsions in the range of 6 to 9 have no effect on emulsion stability. Addition of alkaline inorganic disk closed in U. s. Patent 3,846,276 helps to break the emulsion but addition of clue or H2S04 has little effect on emulsion stability unless enough acid is added to the emulsion to lower the pi below 4.5. however, it was discovered that addition of acids to the amido-amino polymers of the present invention prior to chemical treatment of the emulsion had a - 30 dramatic effect on emulsion stability even though the acids -~25~Q13 were present in such small quantities that they did not appreciably lower the pi of the emulsion. U. S. Patent

3,316,181 teaches the use of amido-amine polymers and their salts for breaking 0/W emulsions but no mention of bitumen emulsions is made, the amino co-polymer is not of the type claimed in the present invention, and the preferred co-polymers contain only 10-40 wt.% of the amino monomer.
Homopolymers, co polymers and salts of the type described in the present invention are disclosed in U. S.

Patents 3,171,305 and 3,487,003 as flocculants for solids but not for emulsifying purposes. In the first case, they are specifically used to treat sewage waters containing anionic surfactants, and in the second case they are used to settle effluents from tar sand mining containing from 0.5 to 2% bitumen and 35 to 55 wt.% solids. The emulsions of in-tersest in the present invention contain in general greater than 10% bitumen and less than 2% solids. Also, in U. S.
Patent 3,487,003 centrifugation and pi adjustment of the effluent to greater than 9 or less than 7.5 were needed as part of the process, unlike the present invention which no-quirks neither step (pi adjustment of bitumen emulsion after cat ionic polymer addition had little or no effect on Emil-soon stability).
There are superficial similarities between the polymer structures claimed herein and those disclosed in Us S. Patents 3,445,441 and 3,509,047, both used for treatment of emulsions containing I oil. Also, Buckles, Water Soluble Polymers, Plenum Press, 1973, p. 243, disclose polyp mews of a type shown to be ineffective as a bitumen emulsion - 30 emulsifier in our examples which follow.

~;~25~3 The produced bitumen emulsions may be treated by the process of our invention in a conventional manner, for example, in a conventional horizontal treater operated, for example, from about 25 to 160C and, preferably, from about 50 to 150C at autogenous pressures. The concentration of the chemical emulsifier described above used in treating the bitumen in water emulsions may range from about 1 to 200 parts per million and, preferably, from about 10 to 100 parts per million with the optional addition of an organic delineate and/or inorganic salt as well as standard phlox-tents and mechanical or electrical means of emulsification.
Following the emulsification process, the water containing phase is available for use in recovering ad-ditional bitumen and/or petroleum. However, if the aqueous phase still contains the polymers and/or co-polymers in the salt form, great harm would result by injecting this ma-tonal into a formation. Since many recovery processes in-elude the yo-yo of forming emulsions in situ to aid in no-covey, it is necessary that the salt forms of the polymers or co-polymers of the invention first be converted into polyp mews or co-polymers which are not in the salt form. These materials are then inactive in emulsifying bitumen Emil-sons. Many times during the treatment of the recovered bitumen emulsions as described in thy application, the pi is changed and the salts are converted into the polymers and/or co-polymers. however, it this natural process does not take place, it will be necessary to convert these salt forms of the polymers and co-polymers to polymers and co-polymers which are not in the salt form by pi adjustment before injecting them into a bitumen containing formation.

~2~5~

Therefore, another embodiment of our invention is a process for recovering bitumen from tar sand formation comprising injecting into the tar sand a fluid containing hot water Andre steam in order to emulsify the bitumen in the tar sand, recovering the emulsified bitumen, de-emulsifying said emulsions by adding thereto emulsifiers comprising homopolymers or co-polymers of greater than about 2,000 molecular weight of monomers having the general structure CH2=C-C-X-(CH2)nN-- 1 where R = H or lower alkyd, X = NH or 0, n I Al and R2 are hydrogen or alkyd wherein the homopolymer and/or co-polymer is in the salt form and monomers of the above structure come prose greater than 50% of the total co-polymer where a co-polymer is used, converting the salts of the polymers or co-polymers into inactive polymers or co-polymers by pi adjust-! mint of the aqueous phase of the broken emulsion, and no-injecting the aqueous phase into a bitumen containing for-motion to recover additional bitumen.
The following examples describe more fully the present process. However, these examples are given for illustration and are not intended to limit the invention.

E X A M P L E_ I
To a one liter resin kettle were charged 247g DMAPMA*, 250g isopropanol and lo cc of a solution of 17.9%, 2,2'-azobis(2,4-dimethylvaleronitrile) in Tulane. The no-suiting solution was deoxygenated for 65 minutes by bubbling nitrogen through at a rake of 14 liters/hour. The nitrogen padded solution was then heated first to 45C, then the tempt erasure was elevated to 88~C over 2.5 hours. After 0.5 hour of heating, 3.5 cc of the initiator solution was added;

after 1.0 hour of heating, 5.0 cc was added; and after 1.5 hour, 5.0 cc more was added for a total of 14.5 cc initiator solution.
The resulting solution (270g) was evaporated to 140g with a pump vacuum of about 2 mm Hug and a boiling water bath. The solid residue was treated at -78C, then chipped from the evaporation flask to provide a yellowish, glassy solid.
Molecular weight was determined by size exclusion liquid chromatography on a Toy Soda 3000 POW. column using as a solvent 0.8M trishydroxymethylaminomethane adjusted to pi = 7. Using polyethylene glycol molecular weight stand-ends, the weight average molecular weight of the polymer was 58,000.

*DMAPMA = dimethylaminopropylmethacrylamide, o (CH3)2NcH2cH2cH2NHc-c(c~3)=c~2 ~;~25~3 E X A M P LYE
In an experiment similar to Example I, the follow-in were charged to the reactor. 300g DMAPMA, 500g demon-iced water, log 2,2'-azobis(2-amidinopropane)hydrochloride, and 0.05g sodium salicylate. Deoxygenation was accomplished by nitrogen stream for 70 minutes. The reaction mixture was heated first at 55C for 4.3 hours, then the temperature was increased to 80C and held at temperature for 6.7 hours.
Conversion of the monomer was 89% complete and a polymer resulted which had a molecular weight of about 1.5 million by size exclusion liquid chromatography using posy acrylamide standards. The solvent used was Own nitric acid; the column material was 1000 angstrom silica coated with alkyd amine groups E X A M P L E III
In an experiment similar to Example I, a polymer of DMAEMA* was prepared having an approximate molecular weight of 290,000 (as measured in Example II). Acetone was the polymerization solvent.

*DMAEMA = dimethylaminoethylmethacrylate o CH2=c(cH3)cocH2cH2N(cH3)2 E X A M P L E IV
A 50:50 co-polymer of acrylamide and DMAPMA was prepared in an experiment similar to Example III. The no-actor charge was 50g DMAPMA, So acrylamide, 300g deionized water, loo isopropanol, 0.5g 2,2'-azobis(2,4-dimethyl-valeronitrile) and Old ethylenediamine tetracetic acid, dip sodium salt. The heating time was 6 hours at 50C. Con-version of both monomers was 98% or more. The resulting polymer (product a) had a molecular weight of 435,000 as measured in Example II.
The Preparation of Hal salt of 80% DMAPMA:20% Acrylamide To 46.35g DMAPMA were added slowly 58.lg 17.1%
aqueous hydrochloric acid with external cooling to keep the contents below 30C. Final pi was 5Ø This solution was transferred to a resin flask with 214.16g deionized water followed by 23.18g of SO% aqueous acrylamide, O.llg sodium salicylate and 0.5g 2,2'-azobis(2-amidinopropane) Hal. The kettle and contents were nitrogen purged with mechanical stirring fur one hour. Nitrogen flow through emulator was reduced to 4.5 liter/hour and contents were held at 50C for 5.6 hours. Analysis of a 0.5 wt.% assay solution of the product showed a 25C kinetic viscosity of 17.4 as and a polymer molecular weight (My) by liquid chromatography of 1,500,000 (product b). Bottle test data in Example XI show this copolymer to be an active emulsifier for bitumen soys-terms and is superior to the 50:50 co-polymer described above.

~L~,2S~[313 E X A M P L E V
A co~nercial flocculent contains an acrylamide-N-(dimethylaminomethyl)acrylamide co-polymer of >200,000 molecular weight. Analyses performed on this compound India acted it to contain virtually no unsubstituted acrylamidegroupings. Thus, it is apparently a o homopolymer of CH2=CH~C-NHCH2N(C~3)2. Labeled product a.
This malarial was dissolved in water containing enough Howe drochloric acid to prepare a 1 weight per cent polymer 50-lotion of pi 6-7. This solution of aminopol~ner salt (product b) was used for subsequent emulsifier tests.

Lo 3 E X A M P L E VI
salts of Product of Example I
a. One gram of the solid polymer isolated from Example I was dissolved in 99 grams deionized water and enough 10% hydrochloric acid added to bring the solution pi to 6-7.
b. As in a. above, except that concentrated sulk uric acid was used to give a pi of 6.5.
c. As in a. above, except that pi = 8.5.

d. As in a. above, except that pi = 7.
e. As in a. above, except that pi - 3.2 E X A M P LYE VII
Salt of Product of Example II

To 35.6g of the polymer solution in Example II
(previously diluted with water to 2.81 weight per cent polymer content) were added 63.8g H20 and lug concentrated hydrochloric acid so as to prepare a 1 weight per cent amino polymer salt solution for emulsifier testing.

E X A M P L E VIII
Salts of Product of Exam The acetone polymer solution of Example III was added to deionized water containing hydrochloric acid so as to prepare 1% aqueous polymer solutions having oh's of 7.5 (product a.), 6.7 (product b.) and 2.4 (product c.), no-spectively.

Sue E X A M P L E IX
Salts of Product of Example IV
The aqueous isopropanol polymer solution of En-ample IV was added to deionized water containing hydra-caloric acid so as to prepare 1% aqueous polymer solution shaving oh's of 6.8 (product a.) and 2.5 (product b.), no spectively.

lo E X A M P L E X
Product of Prior Art L
The procedure of Buckles, referred to above, was used on 50,000-100,000 molecular weight poly(ethyleneimine) to prepare a carbamoylated analog. Infrared analysis on the final product was consistent with a primary tertiary urea.

~225~3 E X A M P L E XI
Emulsifier Testing The following basic testing procedure was em-plowed:
a. A 1 weight per cent solution (on an amine charged basis where amino polymers were used, rather than on an amine salts basis) of each chemical was prepared (in water or acetone).
b. A 30 ml PYREX test tube equipped with screw top was charged with 23 ml emulsion of 11.5 weight per cent bitumen content obtained by in-situ steam flooding in tar sand pattern located at Ft. McMurray, Alberta, Canada.
c. 2 ml Wizard Lake crude oil was added as dill vent and the contents of the test tube were mixed.

d. The contents of the test tune were equal-brazed in a 80C oven for 1-2 hours and mixed again.
e. Chemical was added to the hot, dilute Emil-soon at thy following concentrations: 30, 60, 120 ppm.
f. Contents of the test tubes were mixed, no-equilibrated in an oven at 80C for l hour and mixed again.
g. After 20 hour of standing at 80C, measure-mints were made on the volume of top and middle layers, and the appearance of the aqueous phase was noted. Samples of some top layers were carefully removed by pupating and sub-jetted to Karl-Fischer analysis for determination of the water content. pi measurements were made on the aqueous phases of some broken emulsions to confirm that the addition of even highly acidic emulsifier solutions in the small quantities used have little effect on lowering the pi from - I the initially observed emulsion pi of 7.8.

~225~3 Comparative examples XIk, r, s and y are given to show the relative ineffectiveness of prior art compounds.
Comparative examples Via and Jib show the necessity of n being greater than 1 in the monomer specified in the claims.
The necessity of >50 weight per cent amino-con-twining monomer in ale claimed co-polymers for this invention (preferably >80 weight per cent) is demonstrated by the borderline results obtained with the 50:50 co-polymer of En-ample IV and its salts (see Examples Vial through If').
The desirability of reducing emulsifier oh's tubule 8 prior to addition to the emulsion is fully demon-striated numerous times in these examples as is the desirable treatment concentration range (>60 ppm).

The relatively small effect of polymer molecular weight on emulsifying ability can be seen by the good no-suits obtained on polymers of ~58,000 molecular weight (En-apples I and VI) and ~1,500,000 (Examples II and VII).
Specific test results art summarized in the tables on the following pages.
Examples Tic and d represent the first successful reductions to practice of this invention.

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Liz 3 Examples XII~XV show the improvement over the method of U. S. 3,487,003.

E X M P L E XII
The basic method of Example XI was utilized on the DMAPMA polymer of Example I at 120 ppm treating level.

E X A M P L E XIII
Example XII above was repeated with lug 0.02N H2SO4 added after the oven equilibration of step f in procedure XI.
This lowered the solution pi to 6.6.

E X A M P L E XIV
Repeated Example XIII using 2g ~2S04 solution to lower pi to 5.6.

E X A M P L E XV
Used the basic method of Example XI with 120 ppm DMAPMA polymers salt of Example Vb (repeat of Jim).
(The method ox the present invention.
Oil Phase, Vol. in ml Emulsion Aqueous Example I% H20 in oil) Phase Vol. Phase XII 2.5 5.0 Muddy XIII 2.5 5.5 Muddy XIV 5 4.5 Muddy XV 9 (27.2) 0 Clear, yellow E X A M P L E XVI
CAT IONIC MONOMER SALTS
Enough sulfuric acid was added to 1% aqueous so-lotions of various cat ionic monomers (DMAPMA = dim ethyl-aminopropylmethacrylamide; DMAEMA = dimethylaminoethyl-acrylate; DMAEA* I- dimethylaminoethylacrylate) to render them pi 2-7. Bottle test data in the accompanying table show these monomer salts to be totally inactive as demulsi-liens for bitumen systems, in contrast to reported results in U. S. 4,238,330.

Oil Emulsion Phase, Phase, Concern- Volume Volume Aqueous Candidate traction in ml. in ml. Phase example Emulsifier (ppm) (% Ho ~æ~

a DMAPM~H2S04 60 3 2.5 Muddy b DMAPMA-H2SO~ 120 1.25 3.5 Muddy c None - 1.75 3.5 Muddy d DMAEMA-H2S04 120 2 5 Muddy e DMAEA-H S04 120 2.5 5 Muddy f None 2 3.5 2 Muddy *DMAEA = dimethylaminoethylacrylate o C~I2=CHCOCH2CH2N( SUE ) 2 ~20-

Claims (7)

The embodiments of the invention in which an exclusive property or prilvilege is claimed are defined as follows:

1. A process for recovering petroleum from oil-in-water bitumen emulsions by demulsifying said emulsions by adding thereto demulsifiers comprising homopolymers or co-polymers of greater than about 2,000 molecular weight of mon-omers having the general structure where R = H or lower alkyl, X = NH or O, n >1, R1 and R2 are hydrogen or alkyl wherein the homopolymer and/or co-polymer is in the salt form and monomers of the above structure com-prise greater than 50% of the total co-polymer where a co-polymer is used.

2. A process as in claim 1 wherein the demulsi-fier is a homopolymer.

3. A process as in claim 1 wherein the demulsi-fier is a co-polymer.

4. A process for recovering petroleum from O/W
bitumen emulsions by demulsifying said emulsions by adding thereto demulsifiers comprising homopolymers or co-polymers of greater than about 2,000 molecular weight of monomers having the general structure where R, R1 and R2 are all CH3, X = NH and n = 3 wherein the homopolymer and/or copolymer is in the salt form and monomers of the above structure comprise greater than 50% of the total copolymer where a copolymer is used.

5. A process as in claim 4 where the demulsifier is a homopolymer.

6. A process as in claim 4 wherein the demulsifier is a copolymer.

7. A process for recovering bitumen from a tar sand formation comprising injecting into the tar sand a fluid containing hot water and/or steam in order to emulsify the bitumen in the tar sand, recovering the emulsified bitumen, demulsifying said emulsions by adding thereto demulsifiers comprising homopolymers or copolymers of greater than about 2,000 molecular weight of monomers having the general structure where R = H or lower alkyl, X = NH or 0, n >1, R1 and R2 are hydrogen or alkyl wherein the homopolymer and/or copolymer is in the salt form and monomers of the above structure comprise greater than 50% of the total copolymer where a copolymer is used, converting the salts of the polymers or copolymers into inactive polymers or copolymers by pH adjustment of the aqueous phase of the broken emulsion, and reinjecting the aqueous phase into a bitumen con-taining formation to recover additional bitumen.