Demulsification of bitumen emulsions using polyureas

A process for recovering bitumen from oil-in-water (O/W) emulsions is disclosed wherein water soluble demulsifiers are used. These demulsifiers are polyureas of average molecular weight greater than about 5,000 prepared by the reaction between a polyisocyanate and a polyoxyalkylenediamine. To resolve the bituminous petroleum emulsions, the process is carried out between 25.degree. and 160.degree. C. wherein the demulsifier of the invention is contacted with the bituminous emulsion.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention is concerned with the breaking or resolution of oil-in-water 
(O/W) bituminous emulsions by treatment with polyureas. 
2. 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 semisolid. These 
bituminous hydrocarbons are usually characterized 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 sand 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 bitumen. 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 liquid 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 demulsifiers used in W/O emulsions will 
not resolve the O/W bitumen 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 bitumen O/W emulsions with these W/O emulsions. The following is a 
list of several art references. 
B. British Pat. No. 1,213,392 discloses a polyurethane for breaking W/O 
emulsions. 
C. British Pat. No. 1,112,908 discloses the use of polyurethanes to break 
W/O emulsions. Even in a discussion of prior art, this British Patent 
discusses hydrophilic polyurethanes and indicates that they are 
ineffective for breaking emulsions. 
D. U.S. Pat. No. 3,594,393 is also concerned with breaking W/O emulsions 
with polyurethanes. 
E. U.S. Pat. No. 3,640,894 discloses polyurethanes and polyurethanes used 
in combination with Novolak alkoxylates to break W/O emulsions. 
F. U.S. application Ser. No. 152,453 filed May 22, 1980, now allowed, 
claims a process for recovering petroleum from bitumen emulsions by 
demulsifying the emulsions with the reaction product of a polyisocyanate 
and diols and triols wherein the resulting polyurethane is greater than 
about 8,000 molecular weight. 
It is an object of the present invention to provide a method whereby O/W 
bitumen emulsions may be broken by treatment with a class of polyureas. 
SUMMARY OF THE INVENTION 
The invention is a method for recovering petroleum from O/W bitumen 
emulsions by resolving or breaking these emulsions by contacting the 
emulsions at a temperature of from between about 25.degree. and 
160.degree. C. 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 
##STR1## 
where m is 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 equal to or greater than about 5,000. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The process of this invention utilizing the chemical demulsifier as 
described above utilizes as a chemical demulsifier a particular polyurea. 
Especially useful and preferred in this process are polyureas prepared by 
reaction under appropriate conditions of temperature and (optionally) 
catalysis of the following 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. 
##STR2## 
wherein m is from 10 to 22 and n is from 0 to 1.5. The polyureas useful in 
this invention have an average molecular weight equal to or greater than 
about 5,000. Especially useful as the diamine containing alkyleneoxy 
component of the polyurea are the JEFFAMINE.RTM. ED series 
polyoxyalkylenepolyamines 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 percent ethyleneoxy content of about 70% or greater. Mixtures 
of different polyoxyalkylenediamines 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 blending different 
products. 
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.degree. to 
160.degree. C. and, preferably, from about 50.degree.-150.degree. C. 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 per million with the optional addition of an organic diluent 
and/or inorganic salt as well as standard flocculants and mechanical or 
electrical means of demulsification. The following examples describe more 
fully the present process. However, these examples are given 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 demulsification test results. 
EXAMPLE I 
Polyurea Demulsifier 
A one-liter resin flask was charged with 200 grams of JEFFAMINE.RTM. 
ED-2001 with structure 
##STR3## 
The starting material was dried by stirring at 0.1 mm Hg pressure at 
100.degree. C. for one-half hour. To this material was added 400 grams 
toluene (previously dried over 3 angstrom molecular sieves) and 0.2 grams 
2,6-di-t-butyl-p-cresol. 13.5 ml toluene diisocyanate was added with 
stirring over a five minute period at 50.degree. C. The reaction mixture 
was then stirred under nitrogen for one hour at 60.degree. C. and two 
hours at 100.degree. C. The reaction mixture was then vacuum stripped to 
remove solvent. The product of this reaction was found to contain 0.017 
meq/g total amine and was shown to have a molecular weight of 12,600 by 
liquid chromatographic analysis, using poly(ehtyleneoxy)glycol standards. 
EXAMPLE 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. 
EXAMPLE III 
Mixed Poly(Urea-Urethane) 
A one-liter resin flask was charged with 194 grams of 7,500 molecular 
weight poly(ethyleneoxy)glycol which was dried in vacuum at 100.degree. C. 
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 JEFFAMINE.RTM. D-230 (230 molecular weight 
diamine prepared by reductive amination of a poly(propyleneoxy)glycol), 
followed by addition of 6.7 ml toluene diisocyanate at 50.degree. C. over 
a six minute period. The reaction mixture was stirred under nitrogen for 
one hour at 50.degree. and then two hours at 100.degree.. Solvent was 
removed under reduced pressure, leaving a product of high molecular weight 
too insoluble in most solvents to obtain adequate analysis. 
EXAMPLE IV 
Polyurea from a Mixture of Diamines 
193 Grams JEFFAMINE ED-2001 was dried as in Example 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 to 
50.degree. C. over eight minutes and the mixture was digested under 
N.sub.2 for one hour at 50.degree. and two hours at 100.degree., adding 
300 grams additional toluene to reduce solution viscosity. Solvent was 
removed under reduced pressure and the resulting polymer found to contain 
0.01 meq/g total amine and have an average molecular weight of 6,990. 
EXAMPLE V 
Low Ethyleneoxy-Content Polyurea 
Charged one-liter resin flask with 200 grams JEFFAMINE ED-900 having 
general structure 
##STR4## 
and dried under reduced pressure for one-half hour at 80.degree. C. Added 
400 grams toluene and 0.2 grams 2,6-di-t-butyl-p-cresol. At 50.degree. C. 
added 30.6 ml toluene diisocyanate over five minutes. Cooled reaction 
mixture after 35 minutes at 69-70.degree. C. and removed solvent under 
reduced pressure. The product had a weight average molecular weight of 
5,689 by liquid chromatographic analysis. 
EXAMPLE 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 60-70.degree. C., followed 
by one hour at 100.degree. C. The stripped product had a molecular weight 
of 13,400 and contained 0.036 meq/g total amine. 
EXAMPLE VII 
Mixed Poly(Urea-Urethane) from Amino Alcohol 
A one-liter resin flask was charged with 200 grams of a product obtained by 
incompletely reductively aminating (34.7 mole% conversion) a diol of the 
general structure 
##STR5## 
This compound was dried at 100.degree. C. for one-half at reduced 
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 50.degree. C. over four minutes and then mixture 
digested under nitrogen for one hour 50.degree. and two and 1/4 hours at 
100.degree.. Solvent was removed under reduced pressure to leave a product 
containing 0.01 meq/g total amine and having a weight average molecular 
weight of 30,879. 
EXAMPLE VIII 
Demulsifier Testing of Products from Example 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 H.sub.2 O or in 
toluene). 
(b) 100 ml of fresh, hot bitumen emulsion of known bitumen content obtained 
by in-situ steam flooding in tar sand pattern located at Ft. McMurray, 
Alberta, Canada was poured into a sample bottle. 
(c) 50 parts (volume) of Wizard Lake crude was added as diluent to 100 
parts bitumen contained in the emulsion. 
(d) Chemical was added to the diluted emulsion at the following 
concentrations: 10, 20, 30, 50, 75 and 100 ppm. 
(e) Contents of the bottle were mixed and placed in an oven at 
180-200.degree. F. 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 results 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, and a small (sometimes non-existent) dark water 
layer containing particles or chunks of solid bitumen and clay. 
Comparison results for no demulsifier and a poly-(ethylene oxide) 
demulsifier are also included. 
EXAMPLE IX 
Demulsifier Testing of Products from Example 5-7 
The general method employed in testing the products of Examples 5-7 is as 
follows: 
(a) A 1 wt.% solution of each chemical was prepared (in water or acetone). 
(b) A 30 ml PYREX.RTM. test tube equipped with screw top was charged with 
23 ml emulsion of 11.5 wt.% 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 diluent and the contents of the 
test tube were mixed. 
(d) The contents of the test tube were equilibrated in a 80.degree. C. oven 
for 1-2 hours and mixed again. 
(e) Chemical was added to the hot, dilute emulsion at the following 
concentrations: 30, 60, 120 ppm. 
(f) Contents of the test tubes were mixed, re-equilibrated in an oven at 
80.degree. C. for 1 hour and mixed again. 
(g) After 20 hours of standing at 80.degree. C., measurements 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 subjected to Karl Fischer analysis for determination of the 
water content. 
__________________________________________________________________________ 
DEMULSIFIER TESTING 
Treated Emulsion 
% Bitumen 
% BW & W in Oil 
Ex. 
Candidate in Emul- 
(ppm chemical 
8 Demuslifier sion used) Middle Phase 
Water Phase 
__________________________________________________________________________ 
a Product of Ex. 2 
12-16 13 (100) Wide and unstable 
Muddy 
b Product of Ex. 3 
14 6 (50) Thick Just translucent 
c Product of Ex. 3 
14 30 (100) Quite small 
Just translucent 
d POLYOX.RTM. WSR-301* 
14 31 (50) Large Heavily clouded 
e None 14 46 Moderate Dark, muddy 
f Product of Ex. 1 
20 4 (20) Small Light, muddy 
g Product of Ex. 1 
20 2.5 (75) None Light, muddy 
h POLYOX WSR-301* 
20 4.5 (20) Moderate Light, muddy 
i None 20 18 Very large 
Brown, muddy 
with bottom deposit 
j Product of Ex. 4 
20 4.5 (20) Moderate Brown, muddy 
k Product of Ex. 4 
20 3 (100) None Light, muddy 
l POLYOX WSR-301* 
20 5 (20) Moderate Heavily clouded 
m None 20 5 Very wide 
Brown, muddy 
with large bottom 
deposit 
__________________________________________________________________________ 
*Commercial 4,000,000 molecular weight poly(ethylene 
Note:) 
Horizontal lines on left group tests run on same day and on same emulsion 
__________________________________________________________________________ 
DEMULSIFIER TESTING 
Example 
Candidate Concentration 
Oil Phase Volume 
Emulsion Phase 
Aqueous 
9 Demulsifier 
ppm in ml (% H.sub.2 O) 
Volume in ml (% H.sub.2 O) 
Phase Appearance 
__________________________________________________________________________ 
a Product of Example 5 
60 7 (59.6) 0 Muddy with solid 
deposits 
b Product of Example 5 
120 3.5 3 Muddy 
c Product of Example 6 
60 7 (8.77) 1.5 Muddy 
d Product of Example 7 
60 5 3 Muddy 
e Product of Example 7 
120 7 (86) 2 Muddy 
f POLYOX WSR-301 
60 7.5 (60) 0.5 Yellow, translucent 
g None -- 1.5 3.5 Muddy 
__________________________________________________________________________