Crystallization suppressant combinations for 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. Crystallization suppressant blends are also identified that allow for the preparation of high density clear brine fluids with lower viscosities.

Claims

1. A clear brine fluid comprising: water, a halide salt in an amount of 50 to 64 wt %, and from 8 to 20 wt %, based on the combined weight of the water and halide salt, of a crystallization suppressant blend comprising glycerol and a C.sub.4-6 alditol, wherein the weight ratio of the glycerol to the C.sub.4-6 alditol is higher than 50:50, up to 80:20, and wherein the clear brine fluid has a density at 60° F. of at least 14 ppg, a true crystallization temperature of 15° F. or less than 15° F. as determined using API Protocol 13J 5.sup.th Edition, October 2014 “Testing of Heavy Brines”, and a Brookfield viscosity of 200 cps or less than 200 cps when measured at 40° F. using a #18 spindle at 60 rpm.

2. The clear brine fluid according to claim 1, 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.

3. The clear brine fluid according to claim 1, wherein the C.sub.4-6 alditol comprises xylitol.

4. The clear brine fluid according to claim 1, wherein the C.sub.4-6 alditol comprises mannitol.

5. A method for lowering the true crystallization temperature of a clear brine fluid comprising a halide salt in an amount of 50 to 64 wt % and water, which method comprises adding from 8 to 20 wt %, based on the combined weight of the halide salt and water, of a crystallization suppressant blend comprising glycerol and a C.sub.4-6 alditol, wherein the weight ratio of the glycerol to the C.sub.4-6 alditol is higher than 50:50, up to 80:20, to provide a clear brine fluid having a density at 60° F. of at least 14 ppg, a true crystallization temperature of 15° F. or less than 15° F. as determined using API Protocol 13J 5.sup.th Edition, October 2014 “Testing of Heavy Brines”, and a Brookfield viscosity of 200 cps or less than 200 cps when measured at 40° F. using a #18 spindle at 60 rpm.

6. The method according to claim 5, 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.

7. The method according to claim 5, wherein the C.sub.4-6 alditol comprises xylitol.

8. The method according to claim 5, wherein the C.sub.4-6 alditol comprises mannitol.

Description

DESCRIPTION OF THE INVENTION

(1) 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.

(2) 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.

(3) 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.

(4) 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.

(5) 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.

(6) The clear brine fluids of the invention have a density at 60° 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.

(7) 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.

(8) 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.

(9) 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° F.

(10) In one example, at a concentration of 61.5%, calcium bromide will begin to precipitate from an aqueous solution at approximately 83° 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° 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.

(11) TABLE-US-00001 TABLE 1 TCT of 61.5 wt % CaBr.sub.2 aqueous solution wt % Density Density Additive TCT @ 60° F. @ 100° F. No additive 0 86.3° F. — 15.6 ppg D-sorbitol 12.5%  8.6° F. 15.01 ppg — Malonamide 13.5%  5.5° F. 14.89 ppg — Xylitol 15.0%  4.5° F. 14.91 ppg —

(12) 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.

(13) 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° F., and in some applications below 40° F., e.g., below 30 or 20° 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° F. and often greater than 400° F. or 450° 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° F., typically, preferred suppressants are shown to be thermally stable at temperatures of 400° F. or higher, e.g., 450° F. or higher.

(14) 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.

(15) For example, various amounts of sorbitol were added to brines having a CaBr.sub.2 concentration of about 60-65 wt % to provide clear brine fluids with densities of more than 15 ppg, i.e., 15.2-15.3, and a TCT of ˜15° F., ˜10° F. and ˜5° F. The density and TCT each depend on the amounts of sorbitol added and the concentration of CaBr.sub.2 in the fluid. As more sorbitol is added, the TCT is lowered, however the viscosity increases as shown in the table below. The high viscosities, e.g., over 250 cps, can limit the use of the brine in some applications. See table B1.

(16) Work was undertaken to find a way to provide the low TCT and high density of the brine with maintaining a lower viscosity in the resulting CBF. Obviously, any compound or mixture of compounds used must form a stable solution in the brine and be thermally stable, as described herein. Blends made with sorbitol and urea appeared to lower viscosity, but these blends were not thermally stable, forming solids when heated at 200° F. for about one day. A 50/50 blend of sorbitol and glycerol, however, provided low TCTs, high densities, and lower viscosity, and passed the thermal stability test. Data from a CBF comprising a sorbitol/glycerol blend is shown in table B1.

(17) TABLE-US-00002 TABLE B1 Crystallization Viscosity, cps, Suppressant TCT ° F. Density ppg 40° F. Sorbitol 4.2 15.2 400 Sorbitol 10.8 15.2 300 Sorbitol 14.5 15.3 270 Glycerin/Sorbitol 6.4 15 225 50/50

(18) Another embodiment of the invention thus provides a method for reducing the true crystallization temperature of a clear brine fluid while limiting the increase in viscosity.

(19) The method comprises adding to a clear brine fluid comprising a halide salt and water and having a density of 10 ppg or higher, 12 ppg or higher, or 14 ppg or higher, 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, a crystallization suppressant blend comprising: a mixture of either two or more of an aldose or ketose having at least 4 carbon atoms and/or an alditol having at least 3 carbon atoms; or a mixture comprising at least one aldose or ketose having at least 4 carbon atoms or an alditol having at least 3 carbon atoms with another suitable compound such as an amine, amino acid, alcohol or polyol other than an aldose, ketose having or an alditol.

(20) Typically, the crystallization suppressant blend added to the brine is a mixture of either two or more of an aldose or ketose having at least 4 carbon atoms and/or an alditol having at least 3 carbon atoms;

(21) or is a mixture comprising at least one aldose or ketose having at least 4 carbon atoms or an alditol having at least 3 carbon atoms and a polyol having from 2 to 100 carbon atoms, other than an aldose, ketose or an alditol, e.g., a glycol having from 2 to 100 carbon atoms such as an alkylenoxy glycol, e.g., an ethylenoxy glycol, or an alkylene glycol, e.g., a C.sub.2-20 alkylene glycol such as propylene glycol.

(22) Often the crystallization suppressant blend comprises an aldose or ketose having from 4 to 6 or from 5 to 6 carbon atoms, or an alditol having from 3 to 15 carbon atoms. For example, in some embodiments, the crystallization suppressant blend comprises two alditols of 3 to 6 carbon atoms, such as glycerol and sorbitol, but blends comprising tripentaerythritol have proven successful.

(23) The less viscous CFB produced by the method has a density at 60° F. of 10 ppg or more, often 14 ppg or more. However, the value of the method is more readily appreciated in preparing less viscous, higher density CFBs, e.g. a less viscous high density CaBr.sub.2 brine with a density of 14 ppg or more, than a lower density brine e.g., 10 ppg.

(24) Thus, in some embodiments of the invention, the low viscosity CFB of the invention has a density at 60° F. of least 14 ppg of higher, e.g., 14.4 ppg or higher, 14.7 ppg or higher, 14.8 ppg or higher, or 15.0 or higher.

(25) Generally, the low viscosity brine of the invention, including those with a density of 14 ppg and higher, has a Brookfield viscosity at 40° F. of 250 cps or less, 200 cps or less, 150 cps or less, and in some embodiments, 125 cps or less, or 100 cps or less, measured as Brookfield viscosity at 40° F. using a #18 spindle at 60 rpm.

(26) Generally, the less viscous CFB produced by this method has a TCT of 20° F. or less, and often 15° F. or less, 10° F. or less, 5° F. or less.

(27) In many embodiments the density at 60° F. is 13 ppg or higher, 14 ppg or higher, 14.4 ppg or higher, 14.8 ppg or higher, or 15 ppg or higher.

(28) In some embodiments, the viscosity at 40° F. is 200 cps or less, or 150 cps or less, and in some select embodiments, 125 cps or less, or 100 cps or less.

(29) For example, in some select embodiments, the less viscous CFB of the invention has a TCT 15° F. or less, 10° F. or less, 5° F. or less, e.g., 10° F. or less, and a density at 60° F. of 14 ppg or higher, 14.6 ppg or higher, 14.8 ppg or higher, or 15 ppg or higher, e.g., 14.8 or higher and a viscosity at 40° F. of 200 cps or less. In some of these select embodiments, the less viscous CFB of the invention has a viscosity at 40° F. of 150 cps or less, 125 cps or less, or 100 cps or less.

(30) As above, the concentration of salt, e.g., calcium chloride, sodium bromide or calcium bromide, in the less viscous CFB is often greater than 35 wt %, generally, greater than 40 wt % or 45 wt %, and in many embodiments 50 wt % or more. For example, zinc and cesium free, less viscous CFBs of the invention comprising 50 to 64 wt % calcium bromide were clear and solid free at temperatures below 20° F., in many embodiments, at temperatures below 15° F., 10° F. or 5° F.

(31) For example, in many embodiments the less viscous CFB is prepared by adding the blend comprising the aldose or ketose having at least 4 carbon atoms and/or an alditol having at least 3 carbon atoms to brines containing 55-65 wt % CaBr.sub.2.

(32) A series of CFBs were prepared by adding various amounts of glycerol/sorbitol blends of different weight ratios to brines of CaBr.sub.2 with a CaBr2 concentration of about 60-65 wt % to provide clear brine fluids with densities of between 14.8 and 15.3 ppg and TCT of 10° F. or less. The glycerol/sorbitol ratios, TCT, density at 60° F., and viscosity shown in the table below. Also shown for comparison are samples from above using sorbitol alone as the suppressant, and a sample using glycerol alone.

(33) TABLE-US-00003 Crystallization Density Viscosity, cps, Suppressant TCT ° F. ppg 40° F. Sorbitol 4.2 15.2 400 Sorbitol 10.8 15.2 300 Glycerol 18 14.8 135 Glycerol/Sorbitol 50/50 6.4 15 225 75/25 7.7 14.8 145 70/30 −1.5 14.8 165 70/30 7.4 15.0 225 70/30 7.6 14.9 100 70/30 −0.8 14.8 110 70/30 6.3 14.8 105 80/20 2.5 14.8 150

(34) Sorbitol alone did not deliver the low TCT desired without large increases in viscosity. Glycerol alone was not able to provide TCTs of 10 or less at the high densities desired. However, even though it was found that adding glycerol along with sorbitol can slightly lower the resulting densities, blending the two provided an effective and flexible approach to preparing brines with a balance of very high densities, very low TCTs, and significantly lower viscosity when compared to similar brines using only sorbitol as suppressant.

(35) The blends above comprise a three carbon alditol with a six carbon alditol in weight ratios of 80/20 to 50/50, (glycerol to sorbitol), however, other alditols can be used, as can aldoses or ketoses, and the ratios will vary according to the components of the blend, e.g., 95:5 or 90:10 to 50:50 etc., of the two components in a binary blend may be employed. Also, 3-component, 4-componet, and higher order blends can be used.

(36) When a blend comprises a compound outside of an aldose or ketose having at least 4 carbon atoms and alditol having at least 3 carbon atoms, at least 20 wt % of the blend will be at least one aldose or ketose having at least 4 carbon atoms or alditol having at least 3 carbon atoms. For example, in many such embodiments, at least 25 wt % of the blend will be at least one aldose or ketose having at least 4 carbon atoms or alditol having at least 3 carbon atoms.

(37) In addition to the Glycerol/Sorbitol blends above, other blends were tested with mixed success. A sampling of the data is shown below.

(38) TABLE-US-00004 Density Viscosity, Sample Name TCT ° F. ppg 40° F., cps Sorbitol/Mannitol 1.7 15.2 480 50/50 Sorbitol/Propylene Glycol 13.7 14.6 190 50/50 Sorbitol/Pentaerythritol 22.5 14.9 245 25/75 Sorbitol/Tripentaerythritol 30.4 15.0 290 50/50 Sorbitol/Tripentaerythritol 43 15.0 370 25/75 Sorbitol/B-Alanine −1.5 15.0 280 75/25 Sorbitol/B-Alanine Solids N/A 340 50/50 formed Glycerol/Propylene Glycol 24.5 14.4 90 50/50 Glycerol/Propylene Glycol 12.8 14.6 110 75/25 Glycerol/Tripentaerythritol 16.8 14.8 160 75/25

(39) 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.

(40) 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 α (alpha)-cyclodextrin (a 6-membered sugar ring molecule), β (beta)-cyclodextrin (a 7-membered sugar ring molecule), or γ (gamma)-cyclodextrin (an 8-membered sugar ring molecule) or a mixture of two or more cyclodextrins.

(41) 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° F.

(42) 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

(43) Aqueous calcium bromide samples comprising 53 to 65 wt % calcium bromide solution and 2 to 20 wt % crystallization suppressant 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.

(44) 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° F. using an Anton PAAR Density Meter set at 60° F. and the results compared to the solution without suppressant. Density of the CaBr.sub.2 solution without suppressant is determined at 100° F. due to the higher TCT of the suppressant free fluids.

(45) 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

(46) 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° F. was determined. 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° F. was determined. 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° F. was determined.

(47) Results for examples 1-3 are shown in the table below:

(48) Sorbitol as Crystallization Suppressant

(49) TABLE-US-00005 wt % wt % Density @ Density @ CaBr.sub.2 D-sorbitol TCT 60° F. 100° F. 61.5% 0  86.3° F. — 15.6 ppg 61.5% 12.5%   8.6° F. 15.01 ppg —   62% 0  88.9° F. — 15.7 ppg   62% 13.6%  <−12° F. 15.10 ppg —   64% 0  93.2° F. — 16.2 ppg   64%   15%  19.9° F. 15.47 ppg —

Examples 4-6: Malonamide as Crystallization Suppressant

(50) 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° F. was determined. Ex. 5—Malonamide was added in progressively larger amounts to a 63% CaBr.sub.2 aqueous solution and the TCT and density at 60° F. was determined. 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° F. was determined.

(51) Results are shown in the following table:

(52) Malonamide as Crystallization Suppressant

(53) TABLE-US-00006 wt % wt % Density Density CaBr.sub.2 Malonamide TCT @ 60° F. @ 100° F. 61.5 0 86.3° F. —  15.6 ppg 61.5 13.5%  5.5° F. 14.89 ppg —   63% 0 91. °4F — 15.89 ppg   63% 14.0%  1.4° F. 14.94 ppg — 63.5% 0   92° F. — 16.04 ppg 63.5% 15.1%  4.0° F. 15.06 ppg —

Examples 7-9: Xylitol as Crystallization Suppressant

(54) 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° F. was determined. Ex. 8—Xylitol was added in progressively larger amounts to a 63% CaBr.sub.2 aqueous solution and the TCT and density at 60° F. was determined. 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° F. was determined.

(55) Results are shown in the table below:

(56) Xylitol as Crystallization Suppressant

(57) TABLE-US-00007 wt % wt % Density Density CaBr.sub.2 Xylitol TCT @ 60° F. @ 100° F. 61.5 0 86.3° F. —  15.6 ppg 61.5   15%  4.5° F. 14.91 ppg — 63% 0 91.4° F. — 15.89 ppg 63%   17%  7.4° F. 15.00 ppg — 64% 0 93. °2F —  16.2 ppg 64% 16.5% 14.4° F. 15.17 ppg —

(58) The suppression of TCT allows increases in concentrations of calcium bromide in water to reach higher densities.

(59) Low Viscosity Clear Brine Fluids

Example 10

(60) To a Base fluid comprising 61.5% by weight Calcium Bromide in water, was added a in a 50:50 blend by weight of glycerol and sorbitol to obtain brine comprising 13.89 wt % by weight of the sorbitol and glycerol blend, based on the weight of the resulting composition, to yield a low viscosity, high density clear brine fluid with a TCT of 5.3° F., a density at 60° F. of 14.99 ppg, and a Brookfield viscosity at 40° F. of 221 cps.

Example 11

(61) To a Base fluid comprising 60.45% by weight Calcium Bromide in water, was added a 70/30 blend by weight of glycerin and sorbitol to obtain fluid comprising 12.25% by weight of the sorbitol and glycerin blend, based on the weight of the resulting composition to yield a low viscosity, high density clear brine fluid with a TCT of 0° F., a density at 60° F. of 14.896 ppg, and a Brookfield viscosity at 40° F. of 114 cps.

Examples 12-31

(62) Following the procedure of Example 10, additional low viscosity clear brine fluids were prepared. Compositions, TCT, Density at 60° F. and Brookfield viscosity obtained at 40° F. using a #18 spindle at 60 rpm are of Examples 12-31 are shown in the table below.

(63) TABLE-US-00008 Visc, 40° F., Ex- Density, #18 am- Recrystallization TCT ppg spindle, 60 ple Suppressant ° F. 60° F. rpm 12 Glycerol/Sorbitol 50/50 6.4 15.0 225 13 Glycerol/Sorbitol 75/25 7.7 14.8 145 14 Sorbitol/Mannitol 50/50 1.7 15.2 480 15 Glycerol/Propylene Glycol 24.5 14.4 90 50/50 16 Sorbitol/Propylene Glycol 13.7 14.6 190 50/50 17 Sorbitol/Tripentaerythritol 30.4 15.0 290 50/50 18 Glycerol/Propylene Glycol 12.8 14.6 110 75/25 19 Glycerol/Sorbitol 75/25 19.3 15.0 255 (HiConc.) 20 Sorbitol/B-Alanine 75/25 −1.5 15.0 280 21 Sorbitol/Tripentaerythritol 43 15.0 370 25/75 22 Sorbitol/B-Alanine 50/50 Solids N/A 340 formed 23 100% Glycerol 18 14.8 135 24 Glycerol/Tripentaerythritol 16.8 14.8 160 75/25 25 Glycerol/Sorbitol 70/30 −1.5 14.8 165 26 Glycerol/Sorbitol 80/20 2.5 14.8 150 27 Sorbitol/Pentaerythritol 22.5 14.9 245 25/75 28 G/S 70/30 7.4 15.0 225 29 G/S 70/30 7.6 14.9 100 30 G/S 70/30 −0.8 14.8 110 31 G/S 70/30 6.3 14.8 105