CA1205767A - Demulsification of bitumen emulsions using polyureas - Google Patents

Abstract

DEMULSIFICATION OF BITUMEN EMULSIONS USING POLYUREAS

ABSTRACT OF THE DISCLOSURE
A process for recovering bitumen from oil-in-wa-ter (O/W) emulsions is disclosed wherein water soluble demulsi-fiers are used. These demulsifiers are polyureas of average molecular weight greater than about 5,000 prepared by the reaction between a polyisocyanate and a polyoxyalkylenedi-amine. To resolve the bituminous petroleum emulsions, the process is carried out between 25 and 160°C wherein the de-mulsifier of the invention is contacted with the bituminous emulsion.

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Description

7~'7 sAcKGRouND OF THE INVENTION
Field of the In~ention . ._~
This invention is concerned with the breaking or resolution of oil-in-water (O/W~ bituminous emulsions by treatment with polyureas.
Descriptlon of the Prior ~rt 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 liguid 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 15 . pressure.
Where surface mining i5 not fea6ible, the bitumen must be recovered by rendering the tar material mobile in-situ and producing it through a well penetrating the tar sand deposit. Thesé in situ methods of recovery include thermal, both steam and in-situ combustion and solvent tech-niques. Where steam or hot water methods are used, a prob-lem results which aggravates the recovery of the bitumen.
The difficulty encountered is emulsions produce~ by the in-situ operations. These emulsions are highly stable O/W emul-sions which are made even more stable by the usual presenceof clays. Most ~g~ petroleum emulsions are water-in oil ~W/O) types~ These normal W/O emulsions are broken by mekhods known in the art. However, the bitumen emulsions which are O/W types present a much different problem, and the same demulsifiers used in W/O emulsions will not resolve `

the O/W bl-tumen emulsions. The uniqueness of -these O/W
bitumen emulsions is described in C. W. W. Gewers, J. Canad.
Petrol. Tech., 7(2), 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 bit-umen O/w emulsions with these W/O emulsions. The following is a list of several art references.
B. British Patent 1,213,392 discloses a polyure-thane for breaking W/O emulsions.

C. British Patent 1,112,908 disGloses the use of polyurethanes to break W/O emulsions. Even in a discussion of prior art, this British Patent discusses hydrophilic poly-urethanes and indica-tes that they are ineffective for break-ing emulsions.
1~ D. U. S . Patent 3,594,393 is also concerned wi-th breaking W/O emulsions with polyurethanes.
E. U.S. Patent 3,640,894 discloses polyurethanes and polyurethanes used in combination with Novolak alkoxy-lates to break W/O emulsions.

F. Canadian Patent 1,152,919 claims a process for recovering petroleum from bitumen emulsions by demulsi-fying the emulsions with the reaction product of a polyiso-cyanate and diols and -triols wherein the resulting poly urethane is grea-ter than about 8,000 molecular weight.
It is an object of the present in~ention to pro-vide a method whereby O/W bitumen emulsions may be broken by treatment with a class of polyureas.
SUMMARY OE' THE INVENTION
The invention is a method for recovering petroleum ~. .

7~7 from o/w bltumen emulsions by resolving or breaking these emulsions by contacting the emulsions at a temperature of from between about 25 and 160C with a polyurea prepared by the reaction under appropriate conditions of temperature and catalysis of a polyisocyanate and a diamine or mixture of diamines containing alkyleneoxy units having the general structure o[(cH2cEzo~m(cH2c~Io)nc~2cE~H23 2 CH3 C~3 where m i5 from 0 to 30 and n is from 0 to 5 and wherein the polyurea contains at least 70% by weight ethyleneoxy units and wherein the polyurea has an average molecular weight egual to or greater than about 5,000.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The process of this invention utilizing thç chemi-cal demulsifier as described above utilizes as a chemical demulsifier a particular polyurea.
Espec.ially useful and preferred in this process are polyureas prepared by xeaction under appropriate con-ditions of temperature and (optionally) catalysis of thefollowing two components: (a) a polyisocyanate, especially diisocyanate such as TDI or MDI of molecular weight under 500, and ~b~ a diamine containing alkyleneoxy units having the general structure O[(C~2CH20~m(C~I2CHo)nC~2 ~HNH2]2 : CH3 CH3 wherein m is from 10 to 22 and n is from 0 to 1.5. The poly-ureas useful in this in~ention have an average molecular weight equal to or greater than about 5,000. Especially use-ful as the diamine containing alkyleneoxy component o the 7~7 polyurea are the JEFFA~INE~ ED series polyoxyalkylenepoly-amines from Texaco Chemical Company prepared by reductive amination of an appropriate diol. An especially useful JEFFAMINE polyoxyalkylenediamine has a structure as above wherein m is 20~9 and n is 0.75. The relative values of m and n and the weight ratios of the diisocyanate and the diamines must be adjusted so that the final polyurea has a weight per cent ethyleneoxy content of about 70~ or greater.
Mixtures of different polyox~alkylenediamines may also be used. For example, the hydrophilicity of the demulsifier may be adjusted by one skilled in the art to maximize effectiveness on a particular emulsion. This may be done by adjusting the values of m and n in the product or by blend-ing different products.
' For example when the first amine has a value of m which is about 21 and n about 0.75, then a preferred add-itional amine has m = o and n ranging from about 2 to 6, and particularly preferred with m = o and n about 2.6.
The produced bitumen emulsions may be treated by , the process of our invention in a conventional manner, Eor example, in a conventional horizontal treater operated, for example, from about 25 to 160C and, preferably from about 50 - 150C at autogenous pressures. The concentration of the chemical demulsifier 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 p0r million with the optional addition of an organic diluent and/or inorganic salt as well as standard floccu-lants and mechanical or electrical means of demulsification.

i S7~i7 The following examples describe more full~v the present pro-cess. However, these examples are yiven for illustration and are not intended to limit the invention.
The examples which follow describe the preparation of chemical demulsifiers of the invention and the demulsif.i-cation test results.

4a 7~i7 E X A M P L E
POLYUREA DEMULSIFIER

A one-liter resin flask was charged with 200 grams of JEFF~MINE~ ED-2001 with structur~

' 0[(C~2CH20)20.9~cH~cHo)o.75cH2lH_NH2]2 The starting material was dried by stirring at 0.1 mm Hg pressure at 100C for one-half hour. To this material was added 400 grams toluene (previously dried over 3 angstrom ~I molecular sieves) and 0.2 grams 2,6-di-t-butyl-p-cre-~ol.
I 13.5 ml toluene diisocyanate was added with stirring over a five minute period at 50C. The reaction mixture was then ~: stirred under nitrogen for one hour at 60C and two hours at 100C. The reaction mixture was then vacuum stripped to re-move solvent. The product of this reaction was found to con-taln 0.017 meg~g total amin~ a~d was shown to have a molecular weight of 12,600 by liguid chromatographic analysis, using ~: poly(ethyleneoxy~glycol standards.

E X A M P L E II
LOW_MOLECULAR WEIGHT ANALOG OF PRODUCT OF EXAMPLE I

The general procedure of Example I was repeated using 0.5 moles toluene diisocyanate per mole of JEFFAMINE
ED-2001 to obtain a product with an approximate molecular weight of 4,200 and containing 0.41 meq/g total amine.
~1 :

5~7 MIXED POLY(UREA-URETHANE~

A one-liter resin flask was charged with 194 grams of 7,500 molecular welght poly(ethyleneoxy)glycol which was dried in vacuum at 100C for one-half hour. To this were added 400 grams toluene, 0.2 grams 2,6-di-t-butyl-p-cresol and 0.08 grams dibutyl tin dilaurate. To this mixture was added 6 grams J~FFAMINE~ D-230 (230 molecular weight diamine pre-pared by reductive amination of a poly(propyleneoxy)glycol),followed by addition of 6.7 ml toluene diisocyanate at 50C
over a six minute period. The reaction mixture was stirred under nitrogen for one hour at 50 and then two hours at 100. Solvent was removed under reduced pressure, leaviny a ~ product of high molecular weight too insoluble in most sol-vents to obtain adequate analysis.

E X A M P L E IV

~ POLYUR~A FROM A MIXTURE OF DIAMINES
193 grams JEFFAMINE ED 2001 was dried as in Ex-ample I. To this were then charged 7 grams JEFFAMINE D-230, ~ ~ 0.2 grams 2,6-di-t-butyl-p-cresol and 300 grams dry toluene.
; 16.0 milliliters toluene diisocyanate was added at 50C over eight minutes and the mixture was digested under N2 for one hour at 50 and two hours at 100, adding 300 grams ad-ditional toluene to reduce solution viscosity. Solvent was removed under reduced pressure and the resulting pol~mer found to con~ain 0.01 meq/g total amine and have an average molecular weight of 6,990.

~5i7~

E X A M P L E V
LOW ETHYLENEOXY-CONTENT POLYUREA

Charged one-liter resin flask with 200 grams JEFFAMINE ED-900 having general structure O [ ( CH2CH2 ) 7 . ~ ( C~2CHO ) o . 7 5CH2CHNH2 ] 2 C~3 CH3 and dried under reduced pressure for one-half hour at 80C.
Added 400 grams toluene and 0.2 grams 2,6-di t-butyl-p-cresol.
At 50C added 30.6 ml toluene diisocyanate over fiYe min-utes. Cooled reaction mixture after 35 minutes at 69 70C
and removed solvent under reduced pressure. The product had a weight average molecular weight of 5,689 by liquid chromatographic analysis.

E X A M P L E VI

HIGHER MOLECULAR WEIGHT ANALOG OF PRODUCT OF EXAMPLE IV
Repeated procedure of Example IV using 600 grams toluene, 16 ml toluene diisocyanate and digestion times of one hour at 60-70C, followed by one hour at 100C. The stripped product had a molecular weight of 13,400 and con-tained 0.036 meg/g total amine.

~}11~37~ji7 E X A M_P L E VII
MIXED P~LY(UREA-URETHANE~ FROM I~INO ALCOHOL

A one-liter resin flask was charged with 200 grams of a product obtained by incompletely reductively aminating (34.7 mole% conv~rsion) 2 diol of the ~eneral structure t ( CH2C~20 ) 4 ~ . ~,, ( C~2CHO ) o, 7 ~ C~2CHH] 2 This compound was dried at 100C for one-half hour at re-duced pressure. To this were charged 0.08 grams dibutyl tin dilaurate, 500 grams dry toluene and 0.2 grams 2,6-di-t-butyl-p-cresol. Then 6.2 ml toluene diisocyanate was added at 50C over four minutes and then mixture digested under nitro-gen for one hour at 50 and two and 1/~ hours at 100. Sol-vent was remo~ed under reduced pressure to leave 2 productcontaining 0.01 meq/g total amine and having a weight aver-age molecular weight of 30,879.

E X A M P L E VIII
_ .
DEMULSIFIER TESTING OF PRODUCTS FROM _XAMPLES 1-4 The method employed for testing the products of Examples 1-4 is as follows:
a) A 1% solution of each chemical was prepared (in H20 or in toluene).

b~ 100 ml o~ fresh, ho-t bitumen e~ulsion of known bitumen content obtained by in-situ steam ~looding in tar sand pattern located at Ft. McMurray, Alberta, Canada was poured into a sample bottle.
c~ 50 parts (volume) of Wizaxd Lake crude was added as diluent to 100 parts bitumen contained in the smul~
sion.

~8-d) Chemical was added to the diluted emulsion at the ollowing concentrations: 10, 20, 30, 50, 75 and 100 ppm.
e) con~ents of the bottle were mixed and placed in an o~en at 180-200F for a 24-hour period.
f) BS~W determinations were made on the oil layer.
With each emulsion, a blank was also run in which no chemical agent was introduced. Similar re-sults were obtained from all these blanks; namely, the sample consisted of a thin upper layer consisting mainly of diluent (sometimes containing substantial water), a broad middle layer consisting of unbroken emulsion, ancl a small (sometimes non-existent) dark water layer containing parti-cles or chunks of solid bitumen and clay.
Comparison results for no demulsifier and a poly-(ethylene oxide) demulsifier are also included.

E X

The general method employed in testing the pro-ducts of Examples 5-7 is as follows:
a~ A 1 wt.% solution of each chemical was pre-pared (in water or acetone).
b) A 30 ml PYREX~ test tube equipped with screw top was charged with 23 ml emulsion of 11.5 wt.% bitumen con-0 tent 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 dil-uent and the contents of the test tube were mixed.
d) The contents of the test tube were equili-brated in a 80C oven for 1-2 hours and mixed again.
e) Chemical was added to the hot, dllute emul- A
sion at the following concentrations: 30, 60, 120 ppm.
f) Contents of the test tubes were mixed, re-equilibra~ed in an oven~at 80C for 1 hour and mixed again.

g~ After 20 hours of standing at 80C, measure-ments 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 pipetting and sub-jected to Karl Fischer analysis for determination of the 5 water content.

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Claims (5)

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

1. A process for recovering petroleum from O/W
bitumen emulsions by demulsifying said emulsions by adding thereto demulsifiers comprising polyureas of greater than about 5,000 molecular weight prepared by reaction under appropriate conditions of a polyisocyanate and a diamine or mixture of diamines of the following general structure:

wherein m is from 0 to 30 and n is from 0 to 5 and wherein the polymer contains at least 70% by weight ethyleneoxy units.

2. A process as in claim 1 wherein the polyiso-cyanate is toluene diisocyanate.

3. A process as in claim 1 wherein m is about 21 and n is about 0.75.

4. A process as in claim 3 wherein an additional amine is present having m = 0 and n ranging from about 2 to 6.

5. A process as in claim 4 wherein the additional amine has m = 0 and n = about 2.6.