DIVALENT BRINES WITH LOW TCT AND HIGH DENSITY AND THEIR USES.

Abstract

A method is provided for using a suppression factor fluid during well activity. The method comprises the steps of introducing a suppression factor fluid into a well, wherein the suppression factor fluid comprises an untreated divalent brine and a suppression sugar alcohol, the suppression sugar alcohol being in an operative amount to achieve a suppression factor of at least 1, wherein the suppression factor fluid has an upper density limit that is greater than the upper density limit of the untreated divalent brine, and wherein the suppression factor fluid does not contain zinc; and completing the well activity in the well in such a way that the suppression sugar alcohol inhibits crystallization during the well activity.

Description

DIVALENT BRINES WITH LOW TCT AND HIGH DENSITY AND THEIR USES BACKGROUND Related Patent Applications This patent application claims priority from U.S. Provisional Patent Application No. 62 / 312,868, filed on March 24, 2016. For purposes of U.S. patent practice, this patent application incorporates the contents of the provisional patent application by reference in their entirety. Technical field Compositions for use as well fluids are described. More specifically, compositions with low true crystallization temperatures and high densities for use as well fluids are described. Description of related art When used as a heavy completion fluid, brines can crystallize if exposed to lower temperatures or higher pressures. As the density of a brine increases above its eutectic point, so do the true crystallization temperature (TCT) and the pressure crystallization temperature (PCT), which can lead to the blockage of well tubulars above the surface if the fluid crystallizes. Applying pressure to a divalent brine at a density above the eutectic point results in an increase in density, which in turn can lead to crystallization. Crystallization inhibitors can be used to decrease TCT and PCT, but this can also lead to a reduction in brine density. Zinc, such as zinc bromide (ZnBr2), can be added to increase density. However, zinc is a marine pollutant and can cause problems during processing if residual zinc is present in the crude oil sent to the refinery. In conventional brine systems, typical crystallization inhibitors such as methanol and ethylene glycol can lower the total crystallization temperature (TCT), but they can also dramatically decrease the brine density (making it unsuitable for the original purpose). This means that more solid divalent salt must be added to restore the brine density to the operating density. In most cases, sufficient divalent salt cannot be added to achieve the required operating density and crystallization temperature without adding weighting agents such as zinc bromide. Summary of the invention Compositions for use as well fluids are described. More specifically, compositions with low true crystallization temperatures and high densities for use as well fluids are described. In the first aspect, a method is provided for using a suppression factor fluid during well work. The method includes the steps of introducing a suppression factor fluid into a well. The suppression factor fluid comprises untreated divalent brine and a suppression sugar alcohol. The suppression sugar alcohol is in an operable quantity to achieve a suppression factor of at least 0.1, where the upper density limit of the suppression factor fluid is greater than the upper density limit of the divalent brine and where the suppression factor fluid does not contain zinc. The method further includes the step of terminating the well work in such a way that the suppression sugar alcohol inhibits crystallization during the well work. In certain aspects, the untreated divalent brine is selected from the group consisting of calcium bromide-based brine, calcium chloride-based brine, magnesium bromide-based brine, magnesium chloride-based brine, strontium bromide-based brine, and combinations thereof. In certain aspects, the suppression sugar alcohol is selected from the group consisting of sorbitol, xylitol, and combinations thereof. In certain aspects, the suppression factor is in the range of 0.1 to 10. In certain aspects, the suppression factor fluid also includes a polyol. In a second aspect, a composition is provided for use as a suppression factor fluid. The composition includes an untreated divalent brine and a suppression sugar alcohol. The suppression sugar alcohol is in an operable amount to achieve a suppression factor of at least 0.1, wherein the suppression factor fluid has an upper density limit greater than the upper density limit of the divalent brine. In certain aspects, the composition does not contain zinc. In a third aspect, a composition is provided for use as a suppression factor fluid. The composition includes from 70% to 99.9% by weight of an untreated divalent brine and from 0.1% to 30% by weight on a dry weight basis of a suppression sugar alcohol. In a fourth aspect, a method for creating a suppression factor fluid is provided. The method includes the steps of adding a quantity of a suppression sugar alcohol to a divalent brine to create a mixture, where the quantity of the suppression sugar alcohol is operable to achieve a suppression factor of between 0.1 and 10, and mixing the mixture until the suppression sugar alcohol is dissolved. In certain aspects, the amount of suppressant sugar alcohol ranges from 0.1% to 30% by weight on a dry weight basis. In certain embodiments, the suppressant sugar alcohol is added in solid form. In certain aspects, the suppressant sugar alcohol is added in aqueous form. In certain aspects, the method further comprises adding another divalent salt to the suppressant factor fluid after the suppressant sugar alcohol, following the mixing step, such that the other divalent salt achieves an operating density of the suppressant factor fluid. In certain aspects, the composition further includes the step of adding a polyol. Brief description of the drawing These and other features, aspects, and advantages of the embodiments will be better understood with reference to the following descriptions, claims, and accompanying drawings. However, it should be noted that the drawings illustrate only several embodiments and should therefore not be considered exhaustive of the scope, as might be the case for other equally effective embodiments. Figure 1 is a graph showing the TCT as a function of weight percent (% wt) of suppression sugar alcohol for a suppression sugar alcohol of 1.79 kg / liter of calcium-based brine from Example 5. Detailed Description of the Invention Although the scope is described with several embodiments, it is understood that a person skilled in the relevant art will appreciate that many examples, variations, and alterations to the apparatus and methods described herein fall within the scope and spirit. Accordingly, the examples of embodiments described herein are set forth without any loss of generality and without imposing any limitations. Implementations of a suppression factor fluid may include a divalent brine and a suppression sugar alcohol and methods for using the suppression factor fluid as a well fluid during a well activity. As used herein, crystallization refers to the formation of crystals in a brine solution upon cooling. Without adhering to any particular theory, crystallization occurs when it is thermodynamically favorable, meaning it requires less energy to crystallize than to remain in solution. For example, crystallization in a well can occur in the mud line due to the mud line temperature and the pressure exerted on the fluid. As used herein, well fluid refers to a fluid that can be used in a well. Well fluids include drilling fluids, completion fluids, packing fluids, production fluids, fracturing fluids, and similar fluids used in well activities. As used herein, well activity refers to drilling activities, production activities, and completion activities. Some examples of well activities include, but are not limited to, drilling, completion, and alteration. As used herein, stable or stabilize means that when a composition, component, or compound is stable, the composition, component, or compound does not degrade, decompose, or precipitate out of solution. As used herein, the true crystallization temperature (TCT) refers to the temperature at which crystals form in a brine for a given brine density. The true crystallization temperature is defined as the temperature corresponding to the maximum temperature reached after the minimum supercooling. On a temperature chart during a cooling cycle, the TCT is the maximum temperature reached after the minimum supercooling or the inflection point in cases without any supercooling. If there is no supercooling, the TCT is equivalent to the first crystal to appear (FCTA). The TCT is the measured crystallization temperature closest to the temperature at which a brine naturally crystallizes in pumps, lines, filtration units, and tanks. It is also described in API Recommended Practice 13J, Testing of Heavy Brines, 5th Ed. October 2014 [Recommended Practice for API 13J, Testing of Heavy Brines, 5th Edition, October 2014]. As an example, in an untreated divalent brine containing only a divalent salt and water, as the brine density changes, the TCT changes. Table 1 provides examples of TCT and brine density for untreated brines containing only a divalent salt and water. Table 1. Examples of TCT and brine density for untreated brines Brine Brine Density TCT CaBrc 1.737 kg / 1 -1.1°C CaCl2 1.389 kg / 1 6.7°C MgBrc 1.581 kg / 1 0°C MgCl2 1.258 kg / 1 -16.7°C As used herein, a suppression sugar alcohol refers to a component derived from the reduction of a saccharide that is useful as a suppression additive in suppressing the true crystallization temperature. Examples of suitable suppression sugar alcohols include sorbitol, xylitol, and combinations thereof. In at least one embodiment, the suppression sugar alcohol includes sorbitol in combination with other sugar alcohols. In at least one embodiment, the suppression sugar alcohol includes xylitol in combination with other sugar alcohols. In at least one embodiment, the suppression sugar alcohol includes sorbitol and xylitol in combination with other sugar alcohols. Sugar alcohols do not contain sugars. Advantageously, the sugar alcohols described herein are biodegradable, exhibit low toxicity, and do not bioaccumulate. As used herein, polyol refers to an alcohol containing at least three hydroxyl groups that is not derived from a sugar. For the purposes of this description, the term polyol does not include sugar alcohols. Examples of polyols include glycerol, triglycerol, polypropylene glycol triol, polyester triols, trimethylpropane, trimethylolethane, and combinations thereof. As used herein, the suppression factor is a measure of the reduction in TCT relative to the amount of suppression sugar alcohol. The suppression factor is determined by the following equation: suppression factor = [TCTSm ad of sup - TCTad of sup] / % of suppression additive (equation 1) where TCTSin ad of sup is the TCT of an untreated divalent brine, TCTad of sup is the TCT of a divalent brine with an added suppression additive, and % of suppression additive refers to the amount of suppression additive added to the divalent brine. As used herein, the upper density limit refers to the density that can be achieved in a brine fluid while preventing crystallization under well conditions, including mud line temperature and pressure. Density is a measure of the divalent salt loading in an aqueous fluid, measured in kg per liter. For a calcium bromide-based brine (a solution of calcium bromide and water only), the upper density limit is 1.701 kg / L for a TCT of -11.7°C. For a calcium chloride-based brine (a solution of calcium chloride and water only), the upper density limit is 1.354 kg / L for a TCT of 10.6°C. As used herein, operating density refers to the desired or target density of a well fluid needed for a particular well activity. As used herein, solubility refers to the measure of how much of a component can be dissolved in a fluid. As used herein, untreated divalent brine refers to a divalent brine that does not contain a suppression additive, where the suppression additive suppresses TCT. The embodiments provide a suppression factor fluid that has a lower TCT than untreated divalent brine of similar density. The addition of a suppression sugar alcohol to untreated divalent brine results in minimal density loss compared to untreated divalent brine. Advantageously, the addition of a suppression sugar alcohol to divalent brine can reduce the TCT of the divalent brine for a given brine density. The embodiments can provide zinc-free suppression factor fluids with upper density limits of 1.893 kg / L and a TCT at least -16.1°C below that of untreated divalent brine of the same density. The compositions described herein suppress the thermodynamic event leading to crystallization and allow more divalent salts to be added to the solution than compositions that do not contain a suppression sugar alcohol.Suppression factor fluids are stable (do not crystallize) even when the salt content of the fluid exceeds the saturation point of salt in water at any given temperature. Advantageously, the compositions described herein provide fluids with densities that expand beyond those of conventional fluids used in well operations, while suppressing TCT, which addresses a need in the industry. A suppression factor fluid is provided for use in a well activity. The composition of the suppression factor fluid includes an untreated bivalent brine and a suppression sugar alcohol. In at least one embodiment, the suppression factor fluid further includes a polyol. In at least one embodiment, the suppression factor fluid includes a polyol present in an amount of between 0% and 20% by weight on a dry weight basis, alternatively between 0% and 15% by weight on a dry weight basis, alternatively between 0% and 10% by weight on a dry weight basis, alternatively between 0% and 7% by weight on a dry weight basis, and alternatively between 5% and 7% by weight on a dry weight basis.In at least one embodiment, the polyol is glycerol. Untreated divalent brine can be any aqueous solution containing at least one divalent salt with an upper density limit suitable for well operations. The untreated divalent brine can be selected based on the well activity to be performed, well conditions, operating density, and upper density limit. Examples of untreated divalent brines include calcium bromide-based brine (CaBr₂-based brine), calcium chloride-based brine (CaCl₂), magnesium bromide-based brine (MgBr₂), magnesium-based brine (MgCl₂-based brine), strontium-based brine (SrBr₂-based brine), and combinations thereof. Untreated divalent brine has a true crystallization temperature related to its upper density limit. The suppression sugar alcohol is added in an operable amount to obtain a suppression factor of at least 0.1, alternatively between 0.1 and 10, alternatively between 1 and 5, alternatively between 1 and 4, alternatively between 1 and 3, alternatively between 2 and 3, and alternatively between 5 and 10. In at least one embodiment, the suppression sugar alcohol is added in an operable amount to obtain a TCT suppression of at least 16.1°C. As used herein, suppression means reduction; in other embodiments, a TCT suppression is a reduction of the TCT. In at least one embodiment, the suppression sugar alcohol is added to the divalent brine in a solid form. The solid form of a suppression sugar alcohol is free-flowing and allows for easier handling, does not require storage tanks and pumps, and can be housed in locations, including remote locations, with space constraints.In at least one embodiment, the suppression sugar alcohol is added to the divalent brine in an aqueous form calculated on the basis of dry weight. The amount of added suppressing sugar alcohol may be between 0.1 percent (%) by weight on a dry weight basis and 30% by weight on a dry weight basis, alternatively between 0.5% by weight on a dry weight basis and 25% by weight on a dry weight basis, alternatively between 1% by weight on a dry weight basis and 20% by weight on a dry weight basis, alternatively greater than 5% by weight on a dry weight basis, alternatively more than 10% by weight on a dry weight basis, alternatively between 10% by weight on a dry weight basis and 15% by weight on a dry weight basis, alternatively between 15% by weight on a dry weight basis and 20% by weight on a dry weight basis, and alternatively less than 20% by weight on a dry weight basis. The suppression factor fluid has an upper density limit. The upper density limit can be between 1.80 kg / L and 1.893 kg / L. In at least one embodiment, the upper density limit of the suppression factor fluid is greater than 1.70 kg / L. The true crystallization temperature of the suppression factor fluid for a given upper density limit is lower than the true crystallization temperature of divalent brine at the same upper density limit. The true crystallization temperature of the suppression factor fluid can range from -40°C to -56.7°C. In at least one embodiment, the suppression factor fluid does not contain added zinc in any form, including, but not limited to, elemental zinc, zinc salts, zinc compounds, or combinations thereof. As used herein, added zinc refers to zinc added to the suppression factor fluid and is not understood to include trace levels of zinc that may be present in the components. In at least one embodiment, the suppression sugar alcohol and the suppression factor fluid do not contain glycols, including, for example, ethylene glycol and propylene glycol. The suppression factor fluid is created by adding a quantity of a suppression sugar alcohol to an untreated divalent brine to create a mixture. The quantity of the suppression sugar alcohol is operable to achieve a suppression factor of between 0.1 and 10, or alternatively up to 10. The mixture may be stirred until the suppression sugar alcohol dissolves. As used herein, stirring or mixing includes any form of combining a liquid and a solid, such as agitation, beating, or blending, and any equipment capable of creating a mixed fluid may be used. In at least one embodiment, the density of the divalent brine is higher than the operating density of the suppression factor fluid, such that when the suppression sugar alcohol is added, the density of the suppression factor fluid is reduced to the operating density.In at least one embodiment, another divalent salt can be added to the suppression factor fluid after the suppression sugar alcohol is added to increase or restore the desired density. The embodiments provide suppression factor fluids that have densities on the salt side of a solubility curve, i.e., densities above the eutectic point. On the salt side of a solubility curve, as density increases (i.e., more salt is added), so does the total soluble concentration (TSC). Conversely, on the ice side of a solubility curve, below the eutectic point, as density increases, the TSC decreases. In at least one embodiment, the suppression factor fluid includes a calcium bromide-based brine where the suppression sugar alcohol is sorbitol. The density of sorbitol is 1.48 kg / L. The solubility of sorbitol in CaBr₂ can be 19%. At a 19% loading, cooling the suppression factor fluid to -15.6°C does not result in crystal formation. In this range, the pour point is reached before any crystals can be observed. In at least one embodiment, increasing the amount of sorbitol continued to reduce the TCT. In at least one embodiment, the suppression factor fluid includes a calcium bromide-based brine with sorbitol as the suppression sugar alcohol and has an upper density limit of 1.893 kg / L. A method is provided for using suppression factor fluid during well activity. The suppression factor fluid is introduced into a well. Well activity is terminated in such a way that, during well activity, the suppression sugar alcohol inhibits crystallization. In at least one embodiment, the suppression factor fluid may include additives used in well fluids. In at least one embodiment, an additive that may be added to the suppression factor fluid includes a stabilizing compound to inhibit the degradation of the suppression sugar alcohol at downhole temperatures, where the stabilizing compound is effective in inhibiting degradation at downhole temperatures above 121.1°C. Examples of suitable stabilizing compounds for use include amine bases such as monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TERA), pentaethylenetetramine (PETA), pentaethylenehexamine (PEHA), aminoethylpiperazine (AEP), and ethylenamine E-100 (available in Huntsman Corporation), piperazine, diethylhydroxylamine (DEHA), diethylaminoethanol (DEAE), dimethylethanolamine (DMEA), methoxypropylamine (ΜΟΡΑ), morpholine, n-aminopropylmorpholine (APM), 4-[2-hydroxyethyl]morpholine, diglycolamine, N-[3aminopropyl]diethanolamine, aminoethylethanolamine (AEEA) and combinations thereof themselves. Examples Example 1. Example 1 shows the effect of various polyol additives on suppressing the total thermal conductivity (TTC) of calcium bromide-based brines. Each of the calcium bromide-based brines was formulated to have a density of 1.725 kg / L with varying amounts of polyol additives present, as shown in Table 2. The TTC of each brine was measured, and a suppression factor was calculated according to Equation 1. Table 2. Suppression factors for various polyol additives in calcium bromide-based brine Polyol additive Density (kg / 1) TCT (°C) Additive (wt%) Suppression factor Sample 1 None 1.737 -7.8 0 None Sample 2 Ethylene glycol 1.738 -10.2 9.4 0.42 Sample 3 Propylene glycol 1.733 -1.7 10 Negative Sample 4 Sorbitol 1.737 -27.2 7 5 Sample 5 Xylitol 1.737 <-37.2 14.2 3.7 As shown in Table 2, sugar alcohols have a higher suppression factor compared to other polyol additives. Example 2. Example 2 compared the use of different sugar alcohols as suppression additives in a calcium bromide-based brine. Density and TCT were measured for each sample. The composition, along with density, TCT, and suppression factor for each sample, can be seen in Table 3. Table 3. Suppression factors of various sugar alcohols in calcium bromide-based brine Additive Quantity of Additive Density (kg / 1) TCT (°F) Suppression Factor Suppression (% by weight) Sample 1 None 0 1.833 22.8 0 Sample 2 Sorbitol 14 1.833 -15.2 4.87 Sample 3 Xylitol 14 1.834 1.8 2.7 Sample 4 Mannitol 14 1.832 >23 0 Sample 5 Erythritol 14 1.833 >23.5 0 In sample 4, after standing for two weeks, crystals were found coating the walls of the sample container. In sample 5, the divalent salt did not remain in solution but precipitated upon mixing. The results of Example 2 unexpectedly show that not all sugar alcohols can be used as a suppressing sugar alcohol as described herein. Example 3. In Example 3, a sample of a suppression factor fluid was created. To 400 g of a CaBr₂ solution, 15 g of water and 91 g of sorbitol were added, and the sample was mixed until the sorbitol dissolved. After the sorbitol dissolved, 159 g of solid CaBr₂ were added to the sample, and the sample was mixed again. After the exothermic reaction from the addition, the CaBr₂ sank and all of it dissolved in the sample. The sample was then allowed to cool to room temperature. The density, viscosity, and TCT of the suppression factor fluid were measured. The final density was 1.857 kg / L (at 15.6°C), the viscosity was 234 cP, and the TCT was -6.1°C. The suppression factor was 4.3. Table 4. Composition of the suppression factor fluid of example 3 Component weight (g) % by weight Divalent brine - 1.701 kg / 1 of CaBr2 material 400 60.1 Water 15 2.3 Suppression sugar alcohol - Sorbitol 91 13.7 Added solid CaBr2 159 23.9 Example 4. Example 4 shows the impact of adding various suppressive sugar alcohols on the reduction of TCT and the corresponding suppression factors. The untreated divalent brine for each sample was CaBrz. The density of each sample was 1.833 kg / L. Table 5. Compositions of 1,833 kg / 1 of samples 1-5 of Example 4. Suppression Sugar Alcohol Amount of Suppression Sugar Alcohol (% by weight) TCT (°C) Suppression Factor Sample 1 None 0 22.8 0 Sample 2 Xylitol 8 11.4 2.56 Sample 3 Xylitol 12 2.9 2.98 Sample 4 Xylitol 14 1.8 2.69 Sample 5 Sorbitol 14 -15.2 4.89 As shown by Sample 1, the TCT of a saturated divalent brine based on CaBr2 with 1.833 kg / L is 22.8°C. The addition of sorbitol, as shown in Sample 5, had the highest suppression factor compared to the other suppression sugar alcohols tested in Example 4. Example 5. Example 5 compared the total chemical transition (TCT) of suppression factor fluids with a density of 1.797 kg / L with sorbitol at various concentrations, such as suppression sugar alcohol and calcium bromide-based brine, such as divalent brine. Sorbitol was added to the calcium bromide-based brine and mixed. The TCT was then measured. The results are shown in Table 6. Table 6. Compositions of samples 1-5 of 1,797 kg / 1 of Example 5. Sorbitol Amount (% by weight) TCT (°C) Suppression Factor Sample 1 0 10.6 0 Sample 2 7 -1.7 3.14 Sample 10 -5.1 2.82 Sample 3 4 11 -12.3 3.75 Sample 5 13 -14.6 3.48 Sample 6 18 -17.8 2.83 Table 6 shows that sorbitol at 7 wt% and 13 wt% resulted in suppression factors of 2.82 and 3.75, respectively. As shown in Figure 1, maintaining a constant density while replacing some of the water with sugar alcohol reduces the TCT of the brine. The suppression factor for Example 5 is 2.5 at -15.6°C per wt% of the added sugar alcohol. Example 6. Example 6 compared the TCT of fluids with a suppression factor of 1.84 kg / L. The divalent brine was a CaBr2-based brine. Sample 1 was a comparator sample that did not include a suppression additive. Samples 3, 4, 5, and 6 tested the suppression sugar alcohols sorbitol, xylitol, and combinations thereof. Samples 2, 7, and 8 tested the suppression sugar alcohols sorbitol and xylitol in combination with the polyol glycerol. The composition of each sample can be found in Table 7. Table 7. Compositions of Samples 1-8 of 1,845 kg / 1 of Example 6. Glycerol Amount (% by weight) Sorbitol Amount (% by weight) Xylitol Amount (% by weight) TCT (°C) Suppression Factor Sample 1 0 0 0 24.4 0 Sample 2 7 7 0 1.8 2.91 Sample 3 0 13 0 -0.2 3.41 Sample 4 0 14 0 -4.3 3.69 Sample 5 0 15 0 -7.6 3.84 Sample 6 0 0 15 0.8 2.84 Sample 7 5 15 0 <-15 >3.8 Sample 8 5 0 15 -4.4 2.6 Table 7 shows the impact of suppressive sugar alcohols on TCT suppression over a range of concentrations. Example 7. This example shows that sugar alcohols can operate at low loadings, reducing cost and minimizing density losses. To determine the effect of a low suppression sugar alcohol loading on the TCT of a suppression factor fluid, a CaBr2-based brine (1.737 kg / L calcium bromide-based brine) was formulated with 2 wt% sorbitol as the suppression sugar alcohol. The TCT of this suppression factor fluid was determined to be 5.0°C, a suppression factor of nearly 6, as shown in Table 8. Table 8. Fluid Suppression Factor for Example 7 Additive Density (kg / 1) Additive (% by weight) TCT (°C) Suppression Factor Sample 1 Sorbitol 1.737 2.0 -14.5 6.1 Sample 2 None 1.737 0.0 -i.i 0 Example 8. This example shows the effect of sorbitol on the TCT of a calcium chloride-based brine. A 1.389 kg / L CaCl₂-based brine with 10 wt% sorbitol had a TCT of 30°C compared to a CaCl₂-based brine without a sugar alcohol suppression agent, also with a TCT of 30°C. The TCT suppression factor was determined to be 4.2 with the composition shown in Table 9. Table 9. Fluid Suppression Factor for Example 8 Sorbitol (% by weight) TCT (°C) Suppression Factor Sample 1 0 -1.1 0 Sample 2 10 -17.2 4.2 Example 9. Example 9 shows that sorbitol also suppresses divalent TCT brines made from a combination of salts. A divalent brine was produced from a combination of calcium bromide and calcium chloride, the composition of which is shown in Table 10. Table 10. Effect of sorbitol on the TCT of a brine based on a calcium bromide and calcium chloride mixture Density (kg / 1) Sorbitol (% by weight) CaBr2 (% by weight) CaCl2 (% by weight) TCT (°C) Sample 1,755 kg / 1 12.2 47.1 4.2 -33.9 Example 10. Example 10 shows that sorbitol, as a suppressing sugar alcohol, reduces the TCT of divalent brines composed of magnesium bromide and magnesium chloride. The compositions of the samples are shown in Table 11. Table 11. Effect of sorbitol on the TCT of brines based on MgBr2 and MgC12 Salt Density (kg / 1) Sorbitol (% by weight) TCT (°C) Suppression Factor Sample 1 MgBr2 1.629 0 -9.3 0 Sample 2 MgBr2 1.629 7.5 -14.7 1.3 Sample 3 MgCl2 1.282 0 -15.8 0 Sample 4 MgCl2 1.282 8.5 -27.8 2.5 Example 11. Example 11 shows that sorbitol is effective in reducing the TCT of a strontium bromide-based brine compared to a strontium bromide-based brine that does not contain sorbitol. The compositions of the samples are shown in Table 12. Table 12. Effect of sorbitol on the TCT of a SrBr2-based brine Density (kg / 1) Suppression Sugar Alcohol TCT (°C) Suppression Factor Sample 1 1.641 None 2.8 0 Sample 2 1.641 10% by weight of sorbitol -13.7 3.0 Although the present embodiments have been described in detail, it should be understood that various changes, substitutions, and alterations may be made herein without departing from the principle and scope. Accordingly, the scope shall be determined by the claims and their appropriate legal equivalents. The singular forms un, una and el or la include plural references, unless the context clearly indicates otherwise. Optionally means that the event or circumstances described below may or may not occur. The description includes cases in which the event or circumstance occurs and cases in which it does not. Ranges can be expressed herein as from one particular value to another particular value. When such a range is expressed, it should be understood that another realization is from that particular value to that other particular value, along with all combinations within that range. As used herein and in the claims appended hereto, each of the terms comprise, have and include and all grammatical variants thereof is intended to have an open, non-exhaustive definition that does not exclude additional elements or steps. As used herein, terms such as first and second are assigned arbitrarily and are intended simply to differentiate between two or more components of an apparatus. It should be understood that the words first and second serve no other purpose and do not form part of the component's name or description, nor do they necessarily define a location or relative position of the component. Furthermore, it should be understood that the mere use of the terms first and second does not require the existence of a third component, although that possibility is contemplated within the scope.

Claims

1. A method for using a suppression factor fluid during a well activity, the method being characterized in that it comprises: introducing a suppression factor fluid into a well, wherein the suppression factor fluid comprises: an untreated divalent brine; and more than 5% by weight on a dry basis of a suppression sugar alcohol, the suppression sugar alcohol being in an operative amount to achieve a suppression factor of at least 1, wherein the suppression sugar alcohol is selected from the group consisting of sorbitol, xylitol, and combinations thereof;and a stabilizing compound comprising an amine base, the stabilizing compound operating to inhibit the degradation of the suppression sugar alcohol, wherein the suppression factor fluid has an upper density limit that is greater than the upper density limit of the untreated divalent brine, wherein the density of the suppression factor fluid is on the salt side of a solubility curve of the untreated divalent brine, wherein the suppression factor fluid is thermally stable; and terminating well activity in the well, such that the suppression sugar alcohol inhibits crystallization during well activity.

2. The method of claim 1, characterized in that the untreated divalent brine comprises a divalent salt, wherein the divalent salt is selected from the group consisting of calcium bromide, calcium chloride, magnesium bromide, magnesium chloride, strontium bromide and combinations thereof.

3. The method according to claim 1, characterized in that the suppression factor is in the range between 1 and 10.

4. The method according to claim 1, characterized in that the suppression factor fluid further comprises a polyol, wherein the polyol is selected from the group consisting of glycerol, triglycerol, polypropylene glycol triol, polyester triols, trimethylpropane, trimethylolethane and combinations thereof.