U.S. patent application number 15/650458 was filed with the patent office on 2018-01-18 for high density clear brine fluids.
The applicant listed for this patent is LANXESS SOLUTIONS US INC.. Invention is credited to David W. Bartley, Colin H. Keene, Thomas G. Ray, David J. Sikora, Dwight Tshudy, John Warner, Justin Whitfield, Joni P. Williams.
Application Number | 20180016484 15/650458 |
Document ID | / |
Family ID | 59416816 |
Filed Date | 2018-01-18 |
United States Patent
Application |
20180016484 |
Kind Code |
A1 |
Ray; Thomas G. ; et
al. |
January 18, 2018 |
HIGH DENSITY CLEAR BRINE FLUIDS
Abstract
Compounds are identified that act as crystallization
suppressants when added to clear brine fluids, significantly
lowering the true crystallization temperatures of the brines, and
allowing for higher salt content in clear brine fluids. The
crystallization suppressants of the invention also allow for the
preparation of higher density zinc free brines.
Inventors: |
Ray; Thomas G.; (El Dorado,
AR) ; Keene; Colin H.; (Stephens, AR) ;
Sikora; David J.; (Middlebury, CT) ; Bartley; David
W.; (El Dorado, AR) ; Warner; John;
(Wilmington, MA) ; Whitfield; Justin; (Billerica,
MA) ; Tshudy; Dwight; (Salem, MA) ; Williams;
Joni P.; (Medway, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LANXESS SOLUTIONS US INC. |
Middlebury |
CT |
US |
|
|
Family ID: |
59416816 |
Appl. No.: |
15/650458 |
Filed: |
July 14, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62362099 |
Jul 14, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09K 8/88 20130101; C09K
8/86 20130101; C09K 8/04 20130101; C09K 8/03 20130101; C09K 2208/12
20130101; C09K 8/68 20130101; C09K 8/08 20130101; C09K 8/40
20130101 |
International
Class: |
C09K 8/08 20060101
C09K008/08; C09K 8/03 20060101 C09K008/03 |
Claims
1. A method for lowering the true crystallization temperature of a
clear brine fluid comprising a halide salt and water and having a
density of at least 9 ppg, which method comprises adding from 2 to
20 wt %, based on the combined weight of the halide salt and water,
of a crystallization suppressant additive comprising an aldose or
ketose having at least 4 carbon atoms, an oligosaccharide compound,
an alditol having at least 3 carbon atoms or a 1,3 dicarbonyl
compound having from 3 to 7 carbon atoms.
2. The method according to claim 1 wherein the halide salt is a
chloride or bromide salt of sodium, potassium or calcium, and the
clear brine fluid comprises less than 1 ppm of zinc or cesium.
3. The method according to claim 1 wherein the crystallization
suppressant additive comprises an aldose or ketose having from 4 to
6 carbon atoms, an alditol having from 3 to 6 carbon atoms or a
malonamide having from 3 to 7 carbon atoms.
4. The method according to claim 3 wherein the crystallization
suppressant additive comprises an alditol having from 3-6 carbon
atoms or a malonamide having from 3 to 7 carbon atoms.
5. The method according to claim 1 wherein the crystallization
suppressant additive comprises a mixture of two or more compounds
selected from the group consisting of aldoses or ketoses having at
least 4 carbon atoms, alditols having at least 3 carbon atoms, and
1,3 dicarbonyl compounds having from 3 to 7 carbon atoms.
6. The method according to claim 2 wherein the crystallization
suppressant additive comprises an aldose or ketose having from 4 to
6 carbon atoms, an alditol having from 3 to 6 carbon atoms or a
malonamide having from 3 to 7 carbon atoms.
7. The method according to claim 6 wherein the crystallization
suppressant additive comprises an alditol having from 3-6 carbon
atoms or a malonamide having from 3 to 7 carbon atoms.
8. The method according to claim 1 wherein the clear brine fluid
has a density of at least 12 ppg.
9. The method according to claim 2 wherein the clear brine fluid
has a density of at least 12 ppg.
10. A clear brine fluid having a density of at least 10 ppg,
comprising water, a halide salt and from 2 to 20 wt %, based on the
combined weight of the water and halide salt, of an aldose or
ketose having at least 4 carbon atoms, an alditol having at least 3
carbon atoms or a 1,3 dicarbonyl compound having from 3 to 7 carbon
atoms.
11. The clear brine fluid according to claim 10 wherein the halide
salt comprises a chloride or bromide salt of sodium, potassium or
calcium, and the clear brine fluid comprises less than 1 ppm of
zinc or cesium.
12. The clear brine fluid according to claim 10 wherein the aldose
or ketose has from 4 to 6 carbon atoms, the alditol has from 3 to 6
carbon atoms and the 1,3 dicarbonyl compound is a malonamide.
13. The clear brine fluid according to claim 11 wherein the aldose
or ketose has from 4 to 6 carbon atoms, the alditol has from 3 to 6
carbon atoms and the 1,3 dicarbonyl compound is a malonamide.
14. The clear brine fluid according to claim 12 comprising water,
the halide salt, and from 2 to 20 wt %, based on the combined
weight of the water and halide salt, of an alditol having from 3-6
carbon atoms or a malonamide having from 3 to 7 carbon atoms.
15. The clear brine fluid according to claim 13 comprising water,
the halide salt, and from 2 to 20 wt %, based on the combined
weight of the water and halide salt, of an alditol having from 3-6
carbon atoms or a malonamide having from 3 to 7 carbon atoms.
16. The clear brine fluid according to claim 10 comprising a
mixture of two or more compounds selected from the groups
consisting of aldoses or ketoses having at least 4 carbon atoms,
alditols having at least 3 carbon atoms, and 1,3 dicarbonyl
compounds having from 3 to 7 carbon atoms.
17. The clear brine fluid according to claim 10 wherein the clear
brine fluid has a density of at least 12 ppg.
18. The clear brine fluid according to claim 11 wherein the clear
brine fluid has a density of at least 12 ppg.
19. A clear brine fluid having a density of at least 10 ppg,
comprising water, a halide salt and an oligosaccharide
compound.
20. The clear brine fluid according to claim 19 further comprising
one or more of an aldose or ketose having at least 4 carbon atoms,
an alditol having at least 3 carbon atoms or a 1,3 dicarbonyl
compound having from 3 to 7 carbon atoms.
Description
[0001] The addition of particular crystallization suppressants to
high density clear brine fluids significantly lower the true
crystallization temperatures of the fluids allowing for higher salt
content in the fluids and for the preparation of, e.g., higher
density zinc free brines.
BACKGROUND OF THE INVENTION
[0002] Clear brine fluids are solids-free, industrial fluids widely
used in operations where control of pressure in a well is needed,
such as in the oil and gas industry, and play an important role in
oil exploration and development of deep water wells, high-pressure
and deep oil wells, oil sands, and the like. Clear brine fluids
find use in well completion, work-over, drilling and fracturing
operations, and serve a variety of functions such as a displacement
fluid to remove drilling muds, as drill-in fluids, as permanent
packer fluid. They inhibit undesirable formation reactions such as
clay swelling and are used in preparing well equipment for
production, e.g., during insertion of liners, screens, packers, and
other equipment.
[0003] Clear brine fluids can be prepared with a variety of salts,
generally halide salts, at various concentrations to provide
specific densities for particular applications. For example, brines
with densities ranging, e.g., from 8.4 to over 22 lbs/gal (ppg),
may be desired. Commonly used salts include chloride and bromide
salts of sodium, potassium, calcium and zinc. Ammonium salts,
iodine salts, and other metals have also been used. More than one
salt may be present in the fluid.
[0004] Bromide fluids, e.g., sodium, potassium and calcium bromide
brines, are high density clear brine fluids that are suitable for
deepwater production and high temperature/high pressure oil and gas
formations. For example, bromide fluids are used in deepwater
fracturing operations in order to provide the necessary pressure in
the well to successfully fracture the geological formation area
that supplies oil and gas to the wellbore allowing for higher
volume flows to the production piping.
[0005] Clear brine fluids are solids free and thus contain no
particles that might plug or damage a producing well or equipment
and are used over a wide temperature range. The amount of a
particular salt in a brine fluid, and thus the density of the
brine, is limited by the solubility of that salt in water.
Precipitation of the salt during use must be avoided, and many
salts cannot be used on their own in higher density solutions,
e.g., 12 ppg or 14 ppg to 20 ppg. Historically, the need for high
density clear brine fluids, e.g., >14.2 ppg, has been met by
using zinc bromide to blend up calcium bromide to higher densities.
Zinc bromide and cesium formate brines traditionally have been used
to achieve higher density in completion fluids, up to 19 ppg for
high pressure applications such as kill-fluid and on-the-shelf gas
wells (high temperature/high pressure).
[0006] However, zinc based fluids have environmental and economic
limitations. Zinc is regulated and not environmentally friendly and
requires a zero-discharge system when in use. Zinc contaminated
flow-back and well-produced water has to be collected and shipped
to shore for disposal or treatment and cannot, e.g., be pumped
off-rig into the Gulf of Mexico. These regulations and a growing
consciousness regarding the contamination of ground water has
increased the interest in new clear brine fluids that are more
environmentally friendly and do not require zero-discharge. A clear
brine fluid is needed that can provide high densities and low
crystallization temperatures without using zinc components, which
fluids can be used in applications typically served with the
present zinc containing fluids such as zinc/calcium bromide
brines.
SUMMARY OF THE INVENTION
[0007] It has been found that certain organic compounds, e.g.,
certain sugars and 1,3-dicarbonyl compounds, can be added to clear
brine fluids to lower the temperature at which the salt
precipitates out of solution and increase the amount of a salt that
will remain dissolved in the water. The addition of these compounds
to non-zinc brines provides for new, high density, zinc-free, clear
brine fluids having low true crystallization temperatures and good
environmental compatibility.
[0008] One broad embodiment of the invention provides a method for
reducing or lowering the true crystallization temperature of a
clear brine fluid (CFB) by adding from 2 to 20 wt %, based on the
combined weight of the halide salt and water, of a crystallization
suppressant additive comprising an aldose or ketose having at least
4 carbon atoms, an oligosaccharide compound, an alditol having at
least 3 carbon atoms, or a 1,3 dicarbonyl compound, e.g., a
malonamide, having from 3 to 7 carbon atoms. A CFB of the invention
typically comprises a halide salt and in most embodiments has a
density of over 8.4 ppg, e.g., at least 9 ppg, often at least 10
ppg and frequently at least 12, 14, 14.2 or higher.
[0009] "True crystallization temperature" is the temperature at
which the salt begins to crystallize out from a clear brine fluid
(CBF) under conditions where the crystallization temperature is
determined by the salt composition, i.e., the composition and the
concentration of the salt, in the fluid. The crystallization
temperature of a CBF can be influenced by changes in pressure and
other factors, but the true crystallization temperature excludes
these factors and is determined only by the composition of the
fluid itself. In the present disclosure, true crystallization
temperatures are determined using API Protocol 13J 5th Edition,
October 2014 "Testing of Heavy Brines".
[0010] Another broad embodiment of the invention provides a clear
brine fluid having a density at 60.degree. F. of at least 9 ppg,
typically 10 ppg, 12 ppg or 14 ppg and often 14.2 or higher,
comprising water, a salt, generally a halide salt, and from 2 to 20
wt %, based on the combined weight of the water and halide salt, of
an aldose or ketose having at least 4 carbon atoms, an alditol
having at least 3 carbon atoms, or a 1,3 dicarbonyl compound having
from 3 to 7 carbon atoms as a crystallization suppressant. The
clear brine fluids of the invention have a true crystallization
temperature lower than similar CFBs of the same density that do not
contain the crystallization suppressant.
[0011] In certain embodiments, excellent results are obtained when
the crystallization suppressant comprises a C.sub.4-6 alditol,
e.g., a C.sub.5 or C.sub.6 alditol such as xylitol or sorbitol, or
a diamide such as a C.sub.3-7 malonamide, e.g., the compound
malonamide itself.
[0012] In many embodiments, the halide salt of the CBF of the
invention comprises a chloride or bromide salt of sodium, potassium
or calcium. In the present disclosure, the article "a" or "an",
unless otherwise indicated or necessarily inconsistent with the
context, means one or more than one, and more than one salt may be
present. Likewise, one or more than one crystallization suppressant
compound of the invention may be used. Other components common in
the art may also be present in the inventive fluid, including,
e.g., other crystallization suppressants or additives to improve a
particular property of the CBF, but any of these other components
need to be stable under the potentially harsh conditions the
present fluids may face, and, if present, these other components
make up only a small part of the fluid, e.g., less than 10 wt % or
less than 5 wt %, or less than 2 wt %.
[0013] In particular embodiments the clear brine fluid comprises
less than 1 ppm, e.g., less than 0.5 ppm of zinc or cesium.
DESCRIPTION OF THE INVENTION
[0014] One embodiment provides a method for lowering the true
crystallization temperature of a clear brine fluid, typically
comprising a halide salt and water, and generally having a density
of at least 9 ppg, at least 10 ppg, at least 14 ppg, e.g., at least
14.2 ppg, which method comprises adding to the clear brine fluid
from 2 to 20 wt %, e.g., from 5 to 20 wt % or from 8 to 20 wt %,
based on the combined weight of water and salt, typically a halide
salt, of a crystallization suppressant additive comprising an
aldose or ketose having at least 4 carbon atoms, e.g., an aldose or
ketose having from 4 to 6 or from 5 to 6 carbon atoms, an alditol
having at least 3 carbon atoms, e.g., from 4 to 6 carbon atoms,
e.g. 5 or 6 carbon atoms, or a 1,3 dicarbonyl compound, e.g., a
malonamide, having from 3 to 7 or from 3 to 5 carbon atoms.
[0015] The salt may be a metal or ammonium salt. Typically the salt
comprises a chloride or bromide salt of sodium, potassium or
calcium. In particular embodiments the CFB is zinc free and/or
cesium free meaning that it contains less than 1 ppm, e.g., less
than 0.5 ppm, of zinc and/or cesium.
[0016] For example, in some embodiments the method comprises adding
to a CBF comprising water and a chloride or bromide salt of sodium,
potassium or calcium and having a density of at least 9, 10, 12,
14, 14.2 ppg or higher, from 2 to 20 wt %, based on the combined
weight of salt and water, of a crystallization suppressant
described above, wherein the CFB contains less than 1 ppm, e.g.,
less than 0.5 ppm, of zinc and/or cesium.
[0017] In particular embodiments, the method comprises adding as a
crystallization suppressant malonamide, or a C.sub.5 or C.sub.6
alditol, such as xylitol or sorbitol.
[0018] Other embodiments provide a clear brine fluid that is free
of solids comprising a salt, typically a halide salt, and from 2 to
20 wt %, e.g., from 5 to 20 wt % or from 8 to 20 wt %, based on the
combined weight of water and salt, of a crystallization suppressant
additive comprising an aldose or ketose having at least 4 carbon
atoms, e.g., an aldose or ketose having from 4 to 6 or from 5 to 6
carbon atoms, an alditol having at least 3 carbon atoms, e.g., from
4 to 6 carbon atoms and often 5 or 6 carbon atoms, or a 1,3
dicarbonyl compound, e.g., a malonamide, having from 3 to 7 or from
3 to 5 carbon atoms.
[0019] The clear brine fluids of the invention have a density at
60.degree. F. of at least 9 ppg, typically at least 10 ppg, e.g.,
at least 12 ppg and in many embodiments at least 14 or 14.2 ppg,
and often greater than 14.2 ppg. The halide salt generally
comprises a chloride or bromide salt of sodium, potassium or
calcium, e.g., a chloride or bromide salt of sodium or calcium, and
in certain embodiments the salt comprises a bromide salt, e.g.,
sodium or calcium bromide, often calcium bromide. Generally, the
CFB is zinc and/or cesium free meaning that it contains less than 1
ppm, e.g., less than 0.5 ppm, of zinc and/or cesium.
[0020] For example, some embodiments of the invention provide a
clear brine fluid having a density of at least 10, ppg, 12 ppg or
14 ppg, e.g., at least 12, 14 or 14.2 ppg or higher, comprising
water, a halide salt, less than 1 ppm of zinc or cesium, and from 2
to 20 wt %, based on the combined weight of the water and halide
salt, of an aldose or ketose having 4 to 6 carbon atoms, an alditol
having 4 to 6 carbon atoms, or a malonamide having 3 to 7 or 3 to 5
carbon atoms, e.g., a C.sub.5 or C.sub.6 alditol, such as sorbitol
or xylitol, or malonamide. In some embodiments, the density of the
CFB is greater than 15 ppg.
[0021] As previously mentioned, one or more than one halide salt
may be present and more than one crystallization suppressant may be
used. For example, in one embodiment, a method for lowering the
true crystallization temperature of a clear brine fluid, and the
fluid obtained by a method comprising adding to a clear brine fluid
a crystallization suppressant additive comprising a mixture of two
or more compounds selected from aldoses or ketoses having at least
4 carbon atoms, alditols having at least 3 carbon atoms, and 1,3
dicarbonyl compounds having from 3 to 7 carbon atoms.
[0022] The amount of salt in the fluid will vary depending on the
chemical formula and solubility of the salt, and the desired
density of the fluid. The salt must of course be soluble in high
enough concentrations to obtain to densities needed. In many
embodiments, the fluid comprises as a salt, calcium chloride,
sodium bromide or calcium bromide in concentrations of greater than
35 wt %, in some embodiments the fluid comprises sodium bromide or
calcium bromide in concentrations of greater than 40 wt %. In
particular embodiments, the fluid comprises over 45 wt % calcium
bromide, e.g., 50 wt % calcium bromide or higher. For example, zinc
and cesium free fluids of the invention comprising an alditol or a
malonamide crystallization suppressant and 56 wt %, 60 wt %, or 64
wt % calcium bromide were clear and solid free at temperatures
below 20.degree. F.
[0023] In one example, at a concentration of 61.5%, calcium bromide
will begin to precipitate from an aqueous solution at approximately
83.degree. F., however, adding a crystallization inhibitor of the
invention at a loading of about 15% lowers the temperature at which
calcium bromide begins to precipitate to 4.5.degree. F. Table 1
illustrates the activity of crystallization suppressants of the
invention when added to a brine comprising 61.5 wt % CaBr.sub.2.
TCT is true crystallization temperature.
TABLE-US-00001 TABLE 1 TCT of 61.5 wt % CaBr.sub.2 aqueous solution
wt % Density Density Additive TCT @ 60.degree. F. @ 100.degree. F.
No additive 0 86.3.degree. F. -- 15.6 ppg D-sorbitol 12.5%
8.6.degree. F. 15.01 ppg -- Malonamide 13.5% 5.5.degree. F. 14.89
ppg -- Xylitol 15.0% 4.5.degree. F. 14.91 ppg --
[0024] Obviously, to maintain a clear, solid free fluid, each
component present in the brine, including the crystallization
suppressant, must also be soluble in the brine at the needed
concentrations and temperature of use.
[0025] Given that clear brine fluids are used over a wide
temperature range, not only do the brines need to stay clear and
free of solids at lower temperatures, e.g., below 60 or 50.degree.
F., and in some applications below 40.degree. F., e.g., below 30 or
20.degree. F., but because the fluids are often used at high
temperatures and pressure, the components in the fluid should be,
and often must be, stable at high temperatures, e.g., greater than
250.degree. F. and often greater than 400.degree. F. or 450.degree.
F. While the salts are typically stable at such temperatures, an
effective crystallization suppressant must also be thermally stable
at the temperatures at which the fluid is used. Thus, preferred
crystallization suppressants are shown to be thermally stable, as
determined by thermal gradient analysis (TGA), above temperatures
well above 250.degree. F., typically, preferred suppressants are
shown to be thermally stable at temperatures of 400.degree. F. or
higher, e.g., 450.degree. F. or higher.
[0026] While clear brine fluids are special fluids meeting specific
density and stability requirements, other issues common to the
handling of any fluid will also play a role in selecting the proper
CBF for a particular use. For example, in many applications where
clear brine fluids are used, it is important that the fluids can be
pumped in large quantities and/or high rates and a fluid that is
too viscous may be problematic. It is possible that a stable CBF
with the proper density may be undesirable for use because of
overly high viscosity. The viscosity of a fluid may therefore need
to be evaluated along with other features formulating a CBF, and
the formulation may need to be adjusted to provide the proper
handling characteristics.
[0027] As is well known in the chemical arts, sugars, such as those
useful in the invention, i.e., aldoses, hexoses and alditols, are
generally available in two optically active forms, D and L, often
one of the forms is more prevalent in nature. Generally, the
naturally occurring sugar will more economically attractive and
will be the one chosen for use in the present invention, e.g.,
D-sorbitol, but the opposite, less naturally abundant form of such
sugars may be used in some embodiments, but mixtures of a D and L
sugar may not perform the same as a composition wherein only, or
predominately, one optically active form is present.
[0028] Alternately, oligosaccharide compounds may be used as a
crystallization suppressant as described in this disclosure,
instead of or in addition to the disclosed aldoses, hexoses and
alditols. For example, the oligosaccharide compound may be a
cyclodextrin, such as .alpha. (alpha)-cyclodextrin (a 6-membered
sugar ring molecule), .beta. (beta)-cyclodextrin (a 7-membered
sugar ring molecule), or .gamma. (gamma)-cyclodextrin (an
8-membered sugar ring molecule) or a mixture of two or more
cyclodextrins.
[0029] The present invention provides a process for lowering the
TCT of a CFB and in certain embodiments provides zinc free clear
brine fluids, comprising e.g., halide salts of sodium or calcium,
with densities of greater than 14.2 and TCTs or less than
20.degree. F.
[0030] The invention allows one to move away from zinc based CBF's
when preparing higher density brines. The new, zinc free clear
brine fluids of the invention are solids free, high density,
environmentally friendly, are a cost-effective alternative to zinc
bromide and cesium formate completion fluids, and do not require
zero-discharge like zinc based CBF's.
EXAMPLES
[0031] Aqueous calcium bromide samples comprising 53 to 65 wt %
calcium bromide solution and 2 to 20 wt % were prepared by adding
the crystallization suppressant, i.e., D-sorbitol, malonamide or
xylitol, to an aqueous solution of calcium bromide. Generally, some
heating is required prior to addition of crystallization
suppressant to create a clear CaBr.sub.2 solution at higher
assays.
[0032] In the following examples, true crystallization temperature
was established according to API Protocol 13J 5th Edition, October
2014 "Testing of Heavy Brines". Clear brine fluid density of test
samples was determined at 60.degree. F. using an Anton PAAR Density
Meter set at 60.degree. F. and the results compared to the solution
without suppressant. Density of the CaBr.sub.2 solution without
suppressant is determined at 100.degree. F. due to the higher TCT
of the suppressant free fluids.
[0033] In the examples, the assay and density of the starting CBF
is lowered due to the mass amount of the crystallization
suppressant added, however, much higher aqueous brine
concentrations can be reached before crystallization occurs due the
drastic drop in TCT.
Examples 1-3: D-Sorbitol as Crystallization Suppressant
[0034] Ex. 1--D-Sorbitol was added in progressively larger amounts
to a 61.5% CaBr.sub.2 aqueous solution and the TCT and density at
60.degree. F. was determined. [0035] Ex 2.--D-Sorbitol was added in
progressively larger amounts to a 62% CaBr.sub.2 aqueous solution
and the TCT and density at 60.degree. F. was determined. [0036] Ex.
3--D-Sorbitol was added in progressively larger amounts to a 64%
CaBr.sub.2 aqueous solution and the TCT and density at 60.degree.
F. was determined.
[0037] Results for examples 1-3 are shown in the table below:
Sorbitol as Crystallization Suppressant
TABLE-US-00002 [0038] wt % wt % Density Density CaBr.sub.2
D-sorbitol TCT @ 60.degree. F. @ 100.degree. F. 61.5% 0
86.3.degree. F. -- 15.6 ppg 61.5% 12.5% 8.6.degree. F. 15.01 ppg --
62% 0 88.9.degree. F. -- 15.7 ppg 62% 13.6% <-12.degree. F.
15.10 ppg -- 64% 0 93.2.degree. F. -- 16.2 ppg 64% 15% 19.9.degree.
F. 15.47 ppg --
Examples 4-6: Malonamide as Crystallization Suppressant
[0039] Ex. 4--Malonamide was added in progressively larger amounts
to a 61.5% CaBr.sub.2 aqueous solution and the TCT and density at
60.degree. F. was determined. [0040] Ex. 5--Malonamide was added in
progressively larger amounts to a 63% CaBr.sub.2 aqueous solution
and the TCT and density at 60.degree. F. was determined. [0041] Ex.
6--Malonamide was added in progressively larger amounts to a 63.5%
CaBr.sub.2 aqueous solution and the TCT and density at 60.degree.
F. was determined.
[0042] Results are shown in the following table:
Malonamide as Crystallization Suppressant
TABLE-US-00003 [0043] wt % wt % Density Density CaBr.sub.2
Malonamide TCT @ 60.degree. F. @ 100.degree. F. 61.5 0 86.3.degree.
F. -- 15.6 ppg 61.5 13.5% 5.5.degree. F. 14.89 ppg -- 63% 0
91..degree. 4 F. -- 15.89 ppg 63% 14.0% 1.4.degree. F. 14.94 ppg --
63.5% 0 92.degree. F. -- 16.04 ppg 63.5% 15.1% 4.0.degree. F. 15.06
ppg --
Examples 7-9: Xylitol as Crystallization Suppressant
[0044] Ex. 7--Xylitol was added in progressively larger amounts to
a 61.5% CaBr.sub.2 aqueous solution and the TCT and density at
60.degree. F. was determined. [0045] Ex. 8--Xylitol was added in
progressively larger amounts to a 63% CaBr.sub.2 aqueous solution
and the TCT and density at 60.degree. F. was determined. [0046] Ex.
9--Xylitol was added in progressively larger amounts to a 63.5%
CaBr.sub.2 aqueous solution and the TCT and density at 60.degree.
F. was determined.
[0047] Results are shown in the table below:
Xylitol as Crystallization Suppressant
TABLE-US-00004 [0048] wt % wt % Density Density CaBr.sub.2 Xylitol
TCT @ 60.degree. F. @ 100.degree. F. 61.5 0 86.3.degree. F. -- 15.6
ppg 61.5 15% 4.5.degree. F. 14.91 ppg -- 63% 0 91.4.degree. F. --
15.89 ppg 63% 17% 7.4.degree. F. 15.00 ppg -- 64% 0 93..degree. 2
F. -- 16.2 ppg 64% 16.5% 14.4.degree. F. 15.17 ppg --
[0049] The suppression of TCT allows increases in concentrations of
calcium bromide in water to reach higher densities.
* * * * *