EA039138B1 - High density aqueous well fluids - Google Patents

Abstract

The invention relates to zinc-free aqueous brine compositions. These zinc-free aqueous brine compositions have a density of about 14.3 pounds per gallon (1.71 kg/l) or more, and a true crystallization temperature of about 20°F (-6.7°C) or less, and comprise water and one or more inorganic bromide salts, with the provision that when calcium bromide is present, one or more other water-soluble inorganic salts are also present, when lithium bromide is present, calcium bromide is absent, when bismuth(III) bromide is present, one or more other water-soluble inorganic salts are also present, and for a true crystallization temperature of about 10°F (-12.2°C) or less, when manganese(II) bromide is present, one or more other water-soluble inorganic salts are also present. Processes for forming these zinc-free aqueous brine compositions are also provided.

Description

Technical field

The present invention relates to high density aqueous brines suitable for use as well fluids.

State of the art

Common water brine fluids such as calcium bromide, which can have densities up to about 14.2 ppg (pounds per gallon) (1.70 kg/l), are widely used in the oilfield as clay-free completion fluids, drilling fluids, packer fluids etc. In some wells, bottom hole pressures can reach 30,000 psi (pounds per square inch) (2.1-10 ⁸ Pa). Such high pressures occur at least in wells in the Gulf of Mexico, and temperatures in shale pipelines in the Gulf of Mexico can reach 40°F (4.4°C). As a general rule, every 10,000 psi (6.9 x 10 ⁷ Pa) increase in pressure can raise the crystallization temperature of an aqueous brine solution by about ten degrees Fahrenheit (about 5.6°C).

Typical brine fluids include calcium bromide having densities up to about 14.2 ppg (1.70 kg/L). An aqueous calcium bromide brine solution with a density of approximately 14.2 ppg (1.70 kg/l) has a true crystallization temperature of 10°F (-12.2°C). Aqueous calcium bromide salt solutions can be obtained having a density of up to 15 ppg (1.8 kg/l), however, the true crystallization temperature of these solutions is about 61°F (16.1°C). Such high density aqueous calcium bromide brines are not suitable for some downhole applications, such as the conditions often encountered in the Gulf of Mexico, as these high density aqueous calcium bromide brines will form precipitates due to their relatively high true crystallization temperature.

High-density zinc-containing aqueous calcium bromide brines, such as about 14.5 pounds per gallon (1.74 kg/l) or more, are readily prepared by mixing enough zinc bromide with an aqueous calcium bromide brine to achieve the desired density. Zinc-containing aqueous calcium bromide brines typically have a true crystallization temperature of about 20°F (-6.7°C) or lower, making these zinc-containing brines more suitable for downhole applications. However, the inclusion of zinc requires increased reporting to government authorities for environmental reasons, resulting in more costly environmental mitigation efforts. For example, zinc is considered a highly hazardous pollutant by the US Environmental Protection Agency (EPA).

Thus, there is a need to develop high-density water-brine fluids that do not contain zinc and have a true crystallization temperature that is low enough for downhole applications.

The essence of the invention

The present invention provides zinc-free aqueous salt solutions with high density and low crystallization temperature. It has been found, for example, that a high density zinc-free aqueous brine can be obtained by combining water and one or more inorganic bromide salts such as calcium bromide, manganese bromide (MnBr ₂ ), tin bromide (SnBr ₂ or SnBr ₄ ), bismuth bromide and/or indium bromide; calcium bromide is used in combination with one or more other water-soluble inorganic salts, preferably selected from the inorganic bromide salt, manganese (II) nitrate and water-soluble polytungstate salt; lithium bromide is used in combination with an alkali metal polytungstate salt; bismuth(III) bromide is used in combination with one or more other water-soluble inorganic salts, preferably selected from the inorganic bromide salt; when lithium bromide is present, calcium bromide is absent. Such brine solutions may have densities of about 15.0 ppg (1.78 kg/L) or greater and have a crystallization temperature of about 20°F (-6.7°C) or lower, often about 10°F (-12.2 °C) or lower. These brines are suitable for use as well fluids such as well completion fluids, in particular shale completion fluids, as drilling fluids, packer fluids, workover fluids and other fluids that use aqueous brines, especially aqueous saline solutions of high density. The aqueous salt solutions of the present invention are well suited for offshore completion operations, including in high pressure formations such as oil and gas fields located in the Gulf of Mexico.

One embodiment of the present invention is a zinc-free aqueous saline composition. This composition has a density of about 14.3 pounds per gallon (1.71 kg/l) or more and a true crystallization temperature of about 20°F (-6.7°C) or lower, preferably about 10°F (-12.2 °C) or lower, and contains water and one or more inorganic bromide salts, provided that when calcium bromide is present, one or more other water-soluble inorganic salts are also present, preferably selected from an inorganic bromide salt, manganese (II) nitrate and a water-soluble polytungstate salt; when bismuth(III) bromide is present, one or more other water-soluble inorganic compounds are also present.

- 1 039138 calic salts, preferably selected from inorganic bromide salts; when lithium bromide is present, no calcium bromide is present, and when manganese(II) bromide is present and the true crystallization temperature is about -12.2°C (10°F) or lower, one or more other water-soluble inorganic salts are also present. Methods for preparing these aqueous saline compositions are also indicated.

These and other embodiments and characteristics of the present invention will emerge more clearly from the following description and the appended claims.

More detailed description of the invention

Throughout this document, the expression "zinc free" means that, except for unintentional impurities, neither zinc nor zinc compounds are present or included in the compositions or methods of the present invention. Typically, in the aqueous salt solutions of the present invention, zinc is present in an amount of about 25 ppm or less.

The term ppm, as used throughout this document, means, unless otherwise noted, parts per million (by weight). Throughout this document, ppg and lb/gal are abbreviations for pounds per gallon.

The abbreviation TCT, as used throughout this document, means true crystallization temperature (or true crystallization point). The true crystallization temperature is the temperature at which precipitation begins in the absence of supercooling. The method for determining the true crystallization temperature is described below.

The terms inorganic bromide salt, inorganic bromide, and bromide salt are used interchangeably throughout this document.

Solutions containing one or more inorganic bromide salts and manganese (II) nitrate or water-soluble polytungstate are aqueous salt solutions of the present invention.

Since the compositions of the invention can be used as clay-free well completion fluids, sedimentation and/or turbidity in the aqueous brines of the invention is undesirable. In order to be useful as well fluids, the aqueous salt solutions of the invention should form little or no precipitation over time (for example, for about one week) at ambient temperature and pressure (for example, at 17-25° C and 14-15 psi) or elevated temperature (for example, about 60°C) and ambient pressure.

The compositions of the invention are aqueous saline solutions containing one or more inorganic bromide salts other than zinc bromide. While it is convenient to refer to the compounds as bromide salts and as metal cations and bromide anions, the components in the compositions may be complexed with water or in some other form. Similarly, other water-soluble inorganic salts contained in the aqueous salt solutions of the invention, referred to as salts or their respective cations and/or anions, may be complexed with water or in any other form.

In the practice of the present invention, the inorganic bromide salts are selected from calcium bromide, manganese (II) bromide, tin (II) bromide, tin (IV) bromide, bismuth (III) bromide, indium (III) bromide, and mixtures of any two or more of them; when calcium bromide is used, one or more other water-soluble inorganic salts are also used, which are preferably selected from an inorganic bromide salt, manganese (II) nitrate, and a water-soluble polytungstate salt; when bismuth(III) bromide is used, one or more other water-soluble inorganic salts are also used, which are preferably selected from the inorganic bromide salt. Manganese (II) bromide is preferably used in combination with one or more other water-soluble inorganic salts, particularly when a brine with a true crystallization temperature of about 10°F (-12.2°C) or lower is required; in preferred embodiments, this other inorganic salt is preferably selected from an inorganic bromide salt, manganese(II) nitrate and a water-soluble polytungstate salt, more preferably an inorganic bromide, said inorganic bromide being preferably calcium bromide or a combination of calcium bromide and one or more other inorganic bromide salts. salts. In some embodiments, the inorganic bromide salt is lithium bromide in combination with an alkali metal polytungstate salt. In the case where only one bromide salt is present, preferred inorganic bromide salts include tin (IV) bromide and indium (III) bromide, in particular tin (IV) bromide. When two bromide salts are used, they are preferably a combination of calcium bromide and manganese (II) bromide; when three bromide salts are used, they are preferably a combination of calcium bromide, manganese (II) bromide and tin (IV) bromide or a combination of calcium bromide, manganese (II) bromide and bismuth (III) bromide.

In some preferred embodiments, the inorganic bromide salt is manganese(II) bromide, tin(II) bromide, tin(IV) bromide, indium(III) bromide, or a mixture

- 2 039138 any two or more of them. In other preferred embodiments, the inorganic bromide salt is a combination of calcium bromide and one or more inorganic bromide salts selected from manganese (II) bromide, tin (II) bromide, tin (IV) bromide, bismuth (III) bromide, indium bromide ( III) or mixtures of any two or more of them. In another preferred embodiment, the inorganic bromide salt is a combination of bismuth(III) bromide and one or more inorganic bromide salts selected from manganese(II) bromide, tin(II) bromide, tin(IV) bromide, indium(III) bromide, or a mixture any two or more of them. In yet another preferred embodiment, one inorganic bromide salt is present and the inorganic bromide salt is tin (IV) bromide or indium (III) bromide.

When the other water-soluble inorganic salt is a water-soluble polytungstate salt, it may be an alkali metal polytungstate, an alkaline earth metal polytungstate, a manganese polytungstate, etc. The alkali metal polytungstates include lithium polytungstate, lithium metatungstate, sodium polytungstate, sodium metatungstate, potassium polytungstate, potassium metatungstate, etc.;

preferred alkali metal polytungstates include sodium metatungstate and potassium metatungstate. Alkaline earth metal polytungstates include calcium polytungstate, magnesium polytungstate and strontium polytungstate;

preferred alkaline earth metal polytungstates include calcium polytungstate. The term metatungstate is often used to refer to the hydrated form of the polytungstate salt.

In the case of a combination of lithium bromide with an alkali metal polytungstate salt, the alkali metal polytungstate salts include lithium polytungstate, lithium metatungstate, sodium polytungstate, sodium metatungstate, potassium polytungstate, potassium metatungstate, etc.;

preferred alkali metal polytungstates include lithium metatungstate and sodium metatungstate.

When the inorganic salts of the aqueous brine consist of only the inorganic bromide salts, the total amount of the inorganic bromide salt or salts in the aqueous brine is typically from about 40 to about 75% by weight, based on the total weight of the composition. The preferred total amount of inorganic bromide salts is from about 45% to about 75% by weight, based on the total weight of the composition.

In some embodiments, the total amount of inorganic bromide salts in the aqueous saline solution preferably ranges from about 45 to about 65 wt.%, more preferably from about 55 to about 65 wt.%, based on the total weight of the composition, in particular when used calcium bromide and one other inorganic bromide salt and said other inorganic bromide salt is selected from tin (II) bromide, tin (IV) bromide, bismuth (III) bromide and indium (III) bromide.

In other embodiments, the total amount of inorganic bromide salts in the aqueous saline preferably lies in the range of from about 55 to about 70 wt.% based on the total weight of the composition, in particular when the inorganic bromide salts are calcium bromide and two other inorganic bromide salts , and these other inorganic bromide salts are a combination of manganese (II) bromide and one other metal bromide selected from tin (II) bromide, tin (IV) bromide, bismuth (III) bromide and indium (III) bromide.

When the inorganic salts in the aqueous brine consist of one or more inorganic bromide salts and one or more other water-soluble inorganic salts, the total amount of inorganic bromide salts in the aqueous brine typically lies in the range of from about 15 to about 60% by weight, preferably from about 20 to about 55% by weight, more preferably from about 25 to about 55% by weight, based on the total weight of the composition. The total amount of other water-soluble inorganic salts varies depending on the type of inorganic salt. For manganese (II) nitrate, the total amount in aqueous saline is typically from about 5 to about 75 wt.%, sometimes preferably from about 35 to about 70 wt.%, sometimes preferably from about 10 to about 50 wt.%, in the calculation for the total weight of the composition; for water-soluble polytungstate salts, the total amount in the aqueous saline solution is typically from about 5 to about 40 wt.%, preferably from about 10 to about 35 wt.%, based on the total weight of the composition.

The total amount of inorganic salts in an aqueous saline solution consisting of one or more inorganic bromide salts and one or more other water-soluble inorganic salts ranges from about 60 to about 85 wt.%, sometimes preferably from about 65 to about 85 wt.% , based on the total weight of the composition, when the other water-soluble inorganic salt is manganese (II) nitrate. When the other water-soluble inorganic salt is a water-soluble polytungstate, the total amount of inorganic salts in an aqueous salt solution consisting of one or more inorganic bromide salts and one or more other water-soluble inorganic salts lies in the range from about 50 to about 75 wt.%, preferably from about 55 to about 70 wt.% based on the total weight of the composition.

- 3 039138

Compositions of the invention have densities of about 14.3 pounds per gallon (1.71 kg/L) or greater. Preferably, the compositions have densities of about 14.6 ppg (1.75 kg/L) or greater. In some embodiments, the compositions preferably have densities of about 14.8 ppg (1.77 kg/l) or more, preferably about 15.0 ppg (1.80 kg/l) or more, more preferably about 15.1 ppg (1 .81 kg/l) or more. In other embodiments, particularly when the inorganic bromide salt is calcium bromide and the one or more inorganic bromide salts are selected from tin (IV) bromide, bismuth (III) bromide, or indium (III) bromide, the compositions preferably have a density of about 16.0 ppg (1.92 kg/l) or more.

Density ranges for compositions of the present invention are preferably from about 14.3 ppg (1.71 kg/l) to about 19.0 ppg (2.28 kg/l), more preferably from about 14.6 ppg (1.75 kg/l) to about 18.0 ppg (2.16 kg/l). In some embodiments, densities from about 14.8 ppg (1.77 kg/L) to about 16.0 ppg (1.92 kg/L) are preferred, more preferably from about 15.0 ppg (1.80 kg/L). ) to about 16.0 ppg (1.92 kg/l) and even more preferably from about 15.1 ppg (1.81 kg/l) to about 15.6 ppg (1.87 kg/l). In other embodiments, densities from about 14.6 ppg (1.75 kg/l) to about 15.0 ppg (1.80 kg/l) are preferred, more preferably from about 14.6 to about 14.8 ppg (1 .77 kg/l). In other embodiments, densities from about 15.0 ppg (1.80 kg/L) to about 18.0 ppg (2.16 kg/L) are preferred, more preferably from about 15.5 ppg (1.86 kg/L) ) to about 17.75 ppg (2.13 kg/L). In the following embodiments, particularly when the inorganic bromide salt is calcium bromide and the one other inorganic bromide salt is selected from tin (IV) bromide, bismuth (III) bromide, or indium (III) bromide, densities from about 16.0 are preferred. ppg (1.92 kg/l) to about 17.5 ppg (2.10 kg/l), more preferably from about 16.2 ppg (1.94 kg/l) to about 17.2 ppg (2.06 kg/l). In another embodiment, particularly when the inorganic bromide salt is calcium bromide and the other water-soluble inorganic salt is manganese (II) nitrate, preferred densities are from about 14.5 ppg (1.74 kg/L) to about 16.0 ppg (1.92 kg/l). In yet another embodiment, densities from about 14.5 ppg (1.74 kg/L) to about 17.5 ppg (2.10 kg/L) are preferred, more preferably from about 14.5 ppg (1.74 kg/L). /l) up to about 16.5 ppg (1.98 kg/l), in particular when the inorganic bromide salt is calcium bromide or manganese (II) bromide, and the other water-soluble inorganic salt is a water-soluble polytungstate salt, or when the inorganic bromide salt is lithium bromide in combination with an alkali metal polytungstate salt.

The compositions of the invention typically have a true crystallization temperature of about 20°F (-6.7°C) or less, preferably about 10°F (-12.2°C) or less, more preferably about 8°F (-13, 3°C) or less, and even more preferably about 7.5°F (-13.6°C) or less.

Preferred pH values for the aqueous brine composition of the invention are from about 0 to about 7; more preferably pH values in the range of about 1 to about 6, even more preferred pH values from about 1.5 to about 5, in particular from about 2.5 to about 5. Even more preferred pH values are in the range from about 3 to about 4.

It is known in the art that it is often useful to include one or more optional additives in an aqueous saline solution, and the inclusion of such additives is within the scope of the present invention. Optional additives may include, for example, corrosion inhibitors, lubricants, pH adjusters, surfactants, and/or solvents. Preferred optional additives are glycerol and formic acid.

In some preferred zinc-free aqueous brine compositions of the invention, only water, inorganic bromide salts, one or more other water-soluble inorganic salts, and compounds derived from these components are present; in some of these preferred embodiments, one of the inorganic bromide salts is calcium bromide. In some of these preferred embodiments, other water soluble inorganic salts are selected from manganese(II) nitrate and a water soluble polytungstate salt, more preferably one of the inorganic bromide salts is calcium bromide.

In other preferred zinc-free aqueous saline compositions of the invention, only water, inorganic bromide salts, and compounds derived from these components are present; in some of these preferred embodiments, one of the inorganic bromide salts is calcium bromide. In other preferred zinc-free aqueous saline compositions of the invention, only water, tin(IV) bromide, and compounds derived from these components are present.

Preferred compositions of the present invention include zinc-free aqueous salt solutions that contain water, calcium bromide and one or more other inorganic salts, preferably selected from manganese (II) bromide, tin (II) bromide, tin (IV) bromide, bismuth bromide (III), indium (III) bromide and mixtures of any two or more of them; wherein the composition has a density of about 14.3 ppg (1.71 kg/l) or greater, preferably about 14.6 ppg (1.75 kg/l) or

- 4 039138 greater, more preferably about 15.0 ppg (1.80 kg/l) or more and a true crystallization temperature of about 20°F (-6.7°C) or lower, preferably about 10°F (-12, 2°C) or less, more preferably about 8°F (-13.3°C) or less. In these calcium bromide-containing compositions, the amount of another or other inorganic bromide salts other than calcium bromide is preferably from about 3.0 to about 40 wt.% based on the total weight of the composition; and these calcium bromide containing compositions preferably have a pH in the range of from about 0 to about 8, more preferably from about 1 to 7.

Additional preferred compositions of the present invention include zinc-free aqueous salt solutions containing water and one inorganic bromide salt selected from tin (IV) bromide and indium (III) bromide, more preferably from tin (IV) bromide, and the composition has a density of about 15.0 ppg (1.80 kg/l) or more, preferably about 16.0 ppg (1.92 kg/l) or more, more preferably about 18.0 ppg (2.16 kg/l) or more.

In one preferred embodiment, the inorganic bromide salts are calcium bromide and manganese(II) bromide and the composition has a density of about 14.6 ppg (1.75 kg/L) or greater and a true atmospheric crystallization temperature of about 20°F ( -6.7°C) or less, preferably about 10°F (-12.2°C) or less. Particularly preferred are compositions containing calcium bromide and manganese(II) bromide that have densities of about 15 lb/gal (1.8 kg/L) or greater and a true atmospheric crystallization temperature of about 8°F (-13.3°C ) or below. Preferably, these compositions containing calcium bromide and manganese (II) bromide have a pH in the range of about 2.5-5, more preferably about 3-4.

In some preferred embodiments, the inorganic bromide salts are calcium bromide and manganese(II) bromide in combination with another inorganic bromide salt selected from tin(IV) bromide, tin(II) bromide, bismuth(III) bromide, and indium(III) bromide. ).

In another preferred embodiment, the inorganic bromide salts are calcium bromide, manganese (II) bromide and tin (IV) bromide and the composition has a density of about 15.0 ppg (1.80 kg/L) or greater. Particularly preferred compositions containing calcium bromide, manganese (II) bromide and tin (IV) bromide as inorganic bromide salts have densities of about 16.0 ppg (1.92 kg/l) or more, more preferably about 16.5 ppg (1.98 kg/l) or more.

In yet another preferred embodiment, the inorganic bromide salts are calcium bromide, manganese (II) bromide and bismuth (III) bromide and the composition has a density of about 16.0 ppg (1.92 kg/L) or greater. Particularly preferred compositions containing calcium bromide, manganese (II) bromide and bismuth (III) bromide as inorganic bromide salts have densities of about 16.3 ppg (1.95 kg/l) or more.

In another preferred embodiment, the inorganic bromide salt is calcium bromide and manganese (II) nitrate is present; the composition preferably has a density of about 14.5 ppg (1.74 kg/l) or more, more preferably about 14.8 ppg (1.77 kg/l) or more.

In yet another preferred embodiment, the inorganic bromide salt is calcium bromide or manganese(II) bromide and a water-soluble polytungstate is present, preferably an alkali metal polytungstate, more preferably sodium metatungstate, more preferably the composition has a density of about 14.5 ppg (1.74 kg/ l) or more, more preferably about 14.8 ppg (1.77 kg/l) or more.

In a further preferred embodiment, the inorganic bromide salt is lithium bromide in combination with an alkali metal polytungstate salt; more preferably, the alkali metal polytungstate salt is lithium metatungstate or sodium metatungstate; more preferably, the composition has a density of about 14.5 ppg (1.74 kg/l) or more, more preferably about 14.8 ppg (1.77 kg/l) or more.

Zinc-free aqueous salt solutions with a density of about 14.3 pounds per gallon (1.71 kg/l) or more and a true crystallization temperature of about 20°F (-6.7°C) or lower are prepared by methods that include the compound ( in any order) components containing water and one or more inorganic bromide salts, provided that when calcium bromide is present, one or more other water-soluble inorganic salts are also present, preferably selected from an inorganic bromide salt, manganese (II) nitrate and a water-soluble polytungstate salt; when lithium bromide is present, calcium bromide is absent; when bismuth(III) bromide is present, one or more other water-soluble inorganic salts are also present; and when manganese (II) bromide is present and the true crystallization temperature is about 10° F. or less, one or more other water-soluble inorganic salts are also present.

The inorganic bromide salt or salts include calcium bromide, manganese(II) bromide, tin(II) bromide, tin(IV) bromide, bismuth(III) bromide, indium(III) bromide, and mixtures of any two or more of these. When calcium bromide is used, one or more other water-soluble inorganic salts are also used, preferably selected from the inorganic bromide salt, manganese (II) nitrate and the water-soluble polytungstate salt. When bismuth(III) bromide is used, one or more other water-soluble inorganic salts are also used, preferably selected from the inorganic bromide salt. When lithium bromide is used, an alkali metal polytungstate salt is also used. Manganese (II) bromide is preferably used in combination with one or more other water-soluble inorganic salts, particularly when a true brine crystallization temperature of about 10°F (-12.2°C) or lower is required; in preferred embodiments, the other inorganic salt is an inorganic bromide, manganese(II) nitrate, or a water-soluble polytungstate salt; the inorganic bromide is preferably calcium bromide or a combination of calcium bromide and one or more other inorganic salts. When one inorganic bromide salt is used, it is preferably tin (IV) bromide or indium (III) bromide, more preferably tin (IV) bromide. Manganese(II) bromide as the inorganic bromide salt is preferably used together with calcium bromide, in particular when calcium bromide and one other bromide salt are present; when two bromide salts are used with calcium bromide, they are preferably a combination of manganese (II) bromide and tin (IV) bromide or a combination of manganese (II) bromide and bismuth (III) bromide.

The connection of water, inorganic bromide salt(s) and, if used, other water-soluble inorganic salts can be carried out by any method used for mixing inorganic salts and water. Usually and preferably, concentrated solutions of inorganic salts can be mixed with the addition or removal of water to obtain the desired composition. Alternatively, inorganic bromide salts are added to water. When there are two or more inorganic bromide salts, these inorganic bromide salts can be mixed with a portion of the water before they are combined with each other and, if necessary, with additional water. Co-feeding of components or mixtures thereof does not require that the feeds be completely uniform in time, and each feed may be interrupted at any one or more times in the co-feeding. Another preferred mode of action in the case of two or more inorganic bromide salts is to introduce one or more inorganic bromide salts as a solid into a pre-prepared aqueous solution of the other inorganic bromide salt or salts. If desired, a combination of these methods can be used.

One or more inorganic bromide salts may be formed during the process. The formation of the inorganic bromide salt during the process can be used to produce some or all of the inorganic bromide salt. When the inorganic bromide salt is produced during the process, it may be formed in water before some or all of the other inorganic bromides are introduced, or preferably in an aqueous solution of other inorganic bromides.

The inorganic bromide salt can be formed during the process in various ways. In some embodiments, the inorganic bromide salt can be formed from a metal in elemental form and elemental bromine (Br ₂ ), particularly when the metal is calcium, manganese, tin, bismuth, and/or indium. For example, metallic manganese and elemental bromine can be used to make manganese(II) bromide. In other embodiments, the inorganic bromide salt may be formed from an inorganic oxide and/or hydroxide and a bromide source that is hydrogen bromide and/or elemental bromine. In preferred embodiments, the inorganic bromide salt is formed from (i) an inorganic oxide and/or hydroxide and (ii) hydrogen bromide and/or bromine.

The inorganic oxides and/or hydroxides that can be used to produce the inorganic bromide salt during the process include one or more oxides and/or hydroxides of calcium, oxides and/or hydroxides of manganese, oxide and/or hydroxide of tin(II), oxide and/ or tin (IV) hydroxide, bismuth (III) oxide and/or hydroxide, indium (III) oxide and/or hydroxide, or a mixture of any two or more of them. Preferred inorganic oxides and hydroxides include one or more of oxides and/or hydroxides of manganese, oxides and/or hydroxides of tin (IV), oxide and/or hydroxide of bismuth (III). Of the manganese oxides and/or hydroxides, manganese (II) oxide, manganese (II) hydroxide and mixtures thereof are more preferred, manganese (II) oxide is even more preferred.

When one or more inorganic oxides and/or hydroxides are used, the source of bromide for the formation of inorganic bromide during the process is hydrogen bromide, bromine, or a mixture thereof. Preferably the bromide source is hydrogen bromide or a mixture of hydrogen bromide and bromine, more preferably it is a mixture of hydrogen bromide and bromine. In these mixtures, hydrogen bromide and bromine can be in any desired proportions from 100% hydrogen bromide to 100% Br ₂ , or in any intermediate ratios between them. For convenience, it may be preferable to use a mixture in which hydrogen bromide is present. When bromine (elemental bromine, Br ₂ ) is used alone or mixed with hydrogen bromide, a reducing agent is also present, which is typically methanol, ethanol, formic acid, hydrazine, and the like.

- 6 039138

In the case of a combination of lithium bromide and an alkali metal polytungstate salt, lithium bromide can be prepared by any of the methods described above, including from lithium metal and elemental bromine, and from lithium oxide and/or hydroxide and a source of bromide (typically hydrogen bromide or elemental bromine) .

In some preferred embodiments of the process, the inorganic bromide salt is manganese(II) bromide, tin(II) bromide, tin(IV) bromide, indium(III) bromide, or a mixture of any two or more of these. In other preferred embodiments of the process, the inorganic bromide salt is a combination of calcium bromide and manganese (II) bromide, tin (II) bromide, tin (IV) bromide, bismuth (III) bromide, indium (III) bromide, or a mixture of any two or more of them. . In another preferred embodiment, a combination of bismuth(III) bromide and manganese(II) bromide, tin(II) bromide, tin(IV) bromide, indium(III) bromide, or a mixture of any two or more of these is used. In yet another embodiment, only one inorganic bromide salt is used and the inorganic bromide salt is tin(IV) bromide or indium(III) bromide.

When only one inorganic bromide salt is used to prepare the zinc-free aqueous brine of the invention, the amount of inorganic bromide is typically from about 40 to about 75 wt.%, preferably from about 45 to about 75 wt.%, based on the total weight of the resulting aqueous composition. saline solution. When there are two or more inorganic bromide salts, this range refers to the total weight of all inorganic bromide salts. When the composition contains calcium bromide, the preferred amounts of inorganic bromide salts other than calcium bromide in the aqueous saline solution are from about 5 to about 35 wt.%, more preferably from about 6 to about 30 wt.%, based on the total weight of the composition.

When an inorganic bromide and one or more other water-soluble inorganic salts, such as manganese(II) nitrate or a water-soluble polytungstate salt, are used to prepare the zinc-free aqueous salt solution of the invention, the amount of inorganic bromide is typically from about 15 to about 60% by weight, preferably from about 20 to about 55 wt.%, more preferably from about 25 to about 55 wt.%, based on the total weight of the composition. When the other water-soluble inorganic salt is manganese (II) nitrate, manganese (II) nitrate is usually present in an amount of from about 5 to about 75 wt.%, sometimes preferably from about 35 to about 70 wt.%, sometimes preferably from about 10 to about 50% by weight, based on the total weight of the composition. When the other water-soluble inorganic salt is a water-soluble polytungstate salt, the amount of said polytungstate salt is typically from about 5 to about 40% by weight, preferably from about 10 to about 35% by weight, based on the total weight of the composition.

When an inorganic bromide salt is formed during the process, the amount of this inorganic bromide salt is calculated as if this inorganic bromide salt were added. The amounts of inorganic bromide salt will vary depending, to some extent, on the amount of other inorganic bromides, since as the amount of other inorganic bromide salts is increased, less inorganic bromide salt is required to achieve a particular density value.

In some embodiments, when forming a zinc-free aqueous brine of the invention, the amount of inorganic bromide salt in the aqueous brine is preferably from about 45 to about 65 wt.%, more preferably from about 55 to about 65 wt.%, based on the total weight of the composition, in particular, when calcium bromide and one other inorganic bromide salt is used, and the other inorganic bromide salt is selected from tin (II) bromide, tin (IV) bromide, bismuth (III) bromide and indium (III) bromide.

In other embodiments, when forming the zinc-free aqueous brine of the invention, the amount of the inorganic bromide salt in the aqueous brine is preferably in the range of from about 55 to about 70% by weight, based on the total weight of the composition, particularly when the inorganic bromide salts are bromide. calcium and two other inorganic bromide salts which are a combination of manganese (II) bromide and another metal bromide selected from tin (II) bromide, tin (IV) bromide, bismuth (III) bromide and indium (III) bromide.

The amount of water and/or inorganic bromide salts and/or other water-soluble inorganic salts used to prepare the aqueous brine solutions of the invention can be adjusted to achieve the desired density. To achieve the desired density of the zinc-free aqueous brine composition, water can be removed, for example by heating and/or applying a vacuum.

The zinc-free aqueous saline solution can be heated during the joining of the components and/or after the components have been combined to ensure the components are dissolved. In this optional heating step, the mixture formed during the process and/or the aqueous salt solution formed as a result of the process is heated to a temperature of about 40° C. or higher to obtain a heated solution. Elevated temperatures can increase the rate of dissolution of inorganic bromide salts. Such elevated heating temperatures of the aqueous saline solution are typically

- 7 039138 from about 40°C to the boiling point of the mixture, preferably from about 45 to about 100°C, more preferably from about 50 to about 95°C, and even more preferably from about 60 to about 95°C. In some embodiments, it is preferable to operate at elevated pressures, typically from about 20 to about 40 psi (1.4x105-2.77x105 Pa), as higher temperatures can be achieved. After cooling the aqueous salt solution to ambient temperature (typically from about 15 to about 25°C, often from about 17 to about 23°C), the inorganic bromide salt or salts usually remain in solution.

Optionally, the pH of the zinc-free aqueous saline solution can be adjusted by adding acid or base as needed. Suitable acids include inorganic acids and water-soluble organic acids, suitable bases are usually inorganic oxides and/or hydroxides. In some cases, after adding the inorganic oxide and/or hydroxide to the zinc-free aqueous brine solution, a precipitate may form, after filtration a clear aqueous brine solution is obtained.

Suitable inorganic oxides and hydroxides can be used to adjust the pH, which include oxides and hydroxides of manganese (II), tin (II), tin (IV), bismuth (III), indium (III), alkali metals, including lithium, sodium and potassium, alkaline earth metals including calcium and magnesium, and mixtures of any of these oxides and/or hydroxides. Preferred inorganic oxides and hydroxides include inorganic oxides and hydroxides of manganese, tin, calcium and sodium. In some preferred embodiments, the implementation of the inorganic oxides and/or hydroxides have one or more cations that are already present in the aqueous salt solution. In some embodiments, when an inorganic oxide and/or hydroxide is used to raise the pH, a small amount of precipitate is formed. After removal of the precipitate, for example by filtration, no additional precipitate formation usually occurs.

Suitable acids for pH adjustment include inorganic and organic acids which are soluble in water. Suitable inorganic acids include hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, sulfuric acid, phosphoric acid, and the like. Suitable organic acids include formic acid, tartaric acid, citric acid, gluconic acid, lactic acid, malic acid, maleic acid, malonic acid, oxalic acid, and the like. If desired, mixtures of any two or more acids can be used. The preferred acid is hydrobromic acid, which can be used in gaseous form or preferably as an aqueous solution.

Any optional additives that are included in aqueous saline solutions can be introduced by any of the methods by which the inorganic bromide salt or salts are introduced, or by any other convenient method.

Under storage conditions, aqueous salt solutions with a density of approximately 15.0 ppg (1.80 kg/l) or more often precipitate. These dense aqueous salt solutions can be stabilized by adjusting the pH of the aqueous salt solution. The pH is adjusted by adding an inorganic hydroxide and/or oxide and/or adding an acid, preferably hydrobromic acid, typically to a value in the range of from about 1 to about 7, more preferably from about 1 to about 6, even more preferably from about 2 .5 to about 5.

A small amount of fine precipitates sometimes form in aqueous salt compositions of the invention which have a pH of about 3.5 or higher and in which the inorganic bromide salts are calcium bromide and manganese (II) bromide. In particular, it has been found that by lowering the pH of the aqueous brine compositions, further precipitation in the aqueous brine can be minimized or prevented. In such cases, the pH can be adjusted as described above.

In some embodiments of the present invention, the presence of glycerol and/or formic acid in the composition is preferred. Glycerol can be introduced at any point in the process of the invention by any method suitable for combining glycerol and/or formic acid with process components.

A preferred method for introducing glycerol and/or formic acid is by adding glycerol and/or formic acid to an aqueous saline solution. If glycerol is present, the amount is preferably from about 3 to about 15% by weight, more preferably from about 5 to about 10% by weight, based on the total weight of the composition. The amount of formic acid, when used, is typically from about 500 to about 5000 ppm, preferably from about 750 to about 3000 ppm, more preferably from about 1000 to about 2500 ppm based on the total weight of the composition. It has been found that the presence of glycerol in the manganese-containing aqueous brines of the invention can prevent or minimize the formation of precipitates in aqueous brines, particularly at pH values of about 3.5 or higher.

In some preferred embodiments of the process of the present invention, only water, one or more inorganic bromide salts, and one or more other water-soluble inorganic salts are combined to form the zinc-free aqueous salt solutions of the present invention.

- 8 039138 salts. In some of these preferred embodiments, said other water-soluble inorganic salts are selected from manganese (II) nitrate and water-soluble polytungstate salt.

In some preferred embodiments of the process of the present invention, only water, one or more inorganic bromide salts, one or more inorganic oxides and/or hydroxides, and/or hydrogen bromide and/or bromine are combined to form the zinc-free aqueous salt solutions of the present invention.

Preferred methods of the present invention include combining (in any order) components containing water and one or more inorganic bromide salts, preferably selected from the group consisting of calcium bromide, manganese (II) bromide, tin (II) bromide, tin bromide (IV), bismuth(III) bromide, indium(III) bromide, and mixtures of any two or more of them; wherein when calcium bromide is present, one or more other water-soluble inorganic salts are also present, preferably selected from the inorganic bromide salt, manganese(II) nitrate, and the water-soluble polytungstate salt. When bismuth(III) bromide is present, one or more other water-soluble inorganic salts are also present, preferably selected from the inorganic bromide salt. Lithium bromide is used in combination with one or more alkali metal polytungstate salts. Manganese (II) bromide is preferably used in combination with one or more other water-soluble inorganic salts, preferably selected from an inorganic bromide salt, manganese (II) nitrate and a water-soluble polytungstate salt; in preferred embodiments, said other inorganic salt is a bromide and is calcium bromide or a combination of calcium bromide and one or more other inorganic salts. When only one bromide salt is present, preferred inorganic bromide salts include tin (IV) bromide and indium (III) bromide, in particular tin (IV) bromide. When two bromide salts are used, they are preferably a combination of calcium bromide and manganese (II) bromide; when three bromide salts are used, they are preferably a combination of calcium bromide, manganese (II) bromide and tin (IV) bromide or a combination of calcium bromide, manganese (II) bromide and bismuth (III) bromide.

The resulting composition has a density of about 14.3 ppg (1.71 kg/l) or more, preferably about 14.6 ppg (1.75 kg/l) or more, and a true crystallization temperature of about 20°F (-6.7° C) or less, preferably about 10°F (-12.2°C) or less. An aqueous salt solution in which manganese(II) bromide is the only salt, with a density of 15.0 ppg (1.80 kg/l), has a true crystallization temperature of approximately -10.3°C. In some embodiments, the resulting compositions preferably have densities of about 14.8 ppg (1.77 kg/L) or more, preferably about 15.0 ppg (1.80 kg/L) or more, more preferably about 15.1 ppg ( 1.81 kg/l) or more. In other embodiments, particularly when the inorganic bromide salts are calcium bromide and another inorganic bromide selected from tin (IV) bromide, bismuth (III) bromide, or indium (III) bromide, the compositions preferably have densities of about 16.0 ppg (1.92 kg/l) or more. The other inorganic bromide salt used in combination with calcium bromide is typically present in an amount of from about 3.0 to about 45% by weight, preferably from about 5 to about 40% by weight, more preferably from about 6 to about 35% by weight. based on the total weight of the resulting composition. When calcium bromide is used in combination with manganese (II) nitrate, the amount of manganese (II) nitrate is usually from about 30 to about 75 wt.%, sometimes from about 35 to about 70 wt.% is preferred, sometimes from about 10 to about 50% by weight, based on the total weight of the resulting composition. When calcium bromide or manganese (II) bromide is used in combination with a water-soluble polytungstate salt, the amount of water-soluble polytungstate salt is typically from about 5 to about 40 wt.%, preferably from about 10 to about 35 wt.%, based on the total weight of the composition formed. . When a combination of lithium bromide and one or more alkali metal polytungstate salts is used, the alkali metal polytungstate salt is typically present in an amount of from about 5 to about 40% by weight, preferably from about 10 to about 35% by weight, based on the total weight of the resulting composition.

In some preferred embodiments of the method, water, an inorganic bromide salt or salts, and, if used, one or more other water-soluble inorganic salts are combined to form an aqueous solution. In other preferred embodiments of the process, one or more inorganic bromide salts are obtained during the process from hydrogen bromide and/or bromine and an inorganic oxide and/or hydroxide. The inorganic oxide and/or hydroxide is preferably selected from oxides and/or hydroxides of calcium, manganese (II), tin (II), tin (IV), bismuth (III), indium (III) and mixtures of any two or more of them. When calcium oxides and/or hydroxides are used, one or more other water-soluble inorganic salts are also used, preferably selected from the inorganic bromide salt, manganese(II) nitrate and the water-soluble polytungstate salt. When oxides and/or hydroxides of manganese are used, they are preferably used in combi

- 9 039138 nation with one or more other water-soluble inorganic salts, preferably selected from the inorganic bromide salt, manganese (II) nitrate and water-soluble polytungstate salt. In the case of lithium bromide in combination with a water-soluble polytungstate salt, lithium bromide can be formed from lithium oxide and/or hydroxide with hydrogen bromide and/or bromine.

Preferred combinations of inorganic oxides and/or hydroxides are oxides and/or hydroxides of manganese (II), tin (II), tin (IV), indium (III) and/or bismuth (III) in combination with calcium bromide or oxides and/or calcium hydroxides. Also preferred as inorganic oxides and/or hydroxides are combinations of calcium bromide or oxides and/or hydroxides of calcium with oxides and/or hydroxides of manganese (II) and/or tin (IV), combinations of calcium bromide or oxides and/or hydroxides of calcium with oxides and/or hydroxides of manganese (II) and oxides and/or hydroxides of tin (IV), or a combination of calcium bromide with oxides and/or hydroxides of manganese (II) bromide and oxides and/or hydroxides of bismuth (III) bromide. When only one inorganic bromide salt is present, the preferred inorganic oxides and/or hydroxides are tin (IV) oxides and/or hydroxides and indium (III) oxides and/or hydroxides, in particular tin (IV) oxides and/or hydroxides.

In addition, the methods optionally include heating the aqueous saline solution during and/or after the components are combined, temperatures and preferences being as described above.

These preferred methods may further include adjusting the pH to values in the range of about 1 to about 7 by adding an acid and/or inorganic oxide and/or hydroxide to the aqueous brine composition; preferably, the inorganic oxide and/or hydroxide is an oxide and/or hydroxide of calcium, manganese (II) or tin (II), tin (IV), bismuth (III), indium (III) or mixtures of any two or more of them. Preferred pH ranges are described above.

Natural manganese is present in manganese nodules, more accurately referred to as polymetallic nodules, on the seafloor. These nodules form in oceans all over the world and the most abundant metals in these nodules are manganese and iron.

The following examples are given for illustrative purposes and are not intended to limit the scope of the present invention in any way.

In the following examples, the densities of the solutions were determined by the oscillating U-tube method, which measures the oscillation frequency of a liquid sample.

The determination of the true crystallization temperature in the examples was carried out according to one of the two methods described here.

Classical technique.

A jacketed glass tube containing 50 ml of sample was mechanically stirred while cooling using a recirculation bath containing a coolant (eg, glycol). When the sample reached a temperature about 10°C above the expected first crystal appearance temperature (FCTA), the sample was cooled at a rate of about 0.5°C/min or less temperature increment until the true crystallization temperature (TCT) was detected. The FCTA temperature was taken to be the lowest temperature reached before deposition, and the TCT was taken to be the highest temperature reached immediately after the start of deposition. The sample was removed from the recirculation bath and heated, when all precipitation had disappeared, the dissolution temperature of the last crystal (LCTD) was recorded. Each determination was carried out with a seed crystal of silicon oxide (<50 μm, ~0.03 g) in the sample.

Instrumental technique.

A sample tube containing 0.25 mL of sample was placed in a laboratory cloud point, pour point, and freeze point analyzer (Model 70Xi; Phase Technology, Richmond, Canada) and the sample was cooled at 0.5°C/min until freezing was detected by diffusion. light scattering.

Comparative example 1.

Measurements of the true crystallization temperature (TCT) were carried out on three samples with an aqueous solution of calcium bromide. These samples contained only water and calcium bromide. The results are shown in table. 1 below.

Comparative example 2.

Prepared two samples, based on 50.0 g of an aqueous solution of CaBr ₂ with a density of 14.2 ppg (1.70 kg/l). CaBr ₂ (4.32 g) was added to one sample, and ZnBr ₂ (3.19 g) was added to the other sample. The results are shown in table. 1 below.

Comparative example 3.

Prepared two samples, based on 40.0 g of an aqueous solution of CaBr ₂ with a density of 12.8 ppg (1.53 kg/l). CaBr ₂ (13.18 g) was added to one sample, and ZnBr ₂ (11.90 g) was added to the other sample. The results are shown in table. 1 below.

Comparative example 4.

A number of samples were prepared starting from 50.0 g of an aqueous solution of CaBr2 with a density of 14.2 ppg (1.70 kg/l).

- 10 039138

Salts of LiBr (4.18 g), SrBr2-6H2O (7.01 g) and BaBr2 (2.21 g) were added to give various solutions of CaBr ₂ . The study of the strontium-containing and barium-containing samples was discontinued due to problems with solubility and density.

A further series of samples were prepared, starting from 40.0 g of an aqueous solution of CaBr ₂ with a density of 12.8 ppg (1.53 kg/l). LiBr salts (15.18 g) and MgBr ₂ -6H ₂ O were added to give various solutions of CaBr ₂ . The study of the magnesium-containing sample was terminated due to solubility and density problems. The results are shown in table. 1 below.

Table 1

Comp. etc. An experience Inorganic bromides The amount of bromide other than CaBrr ^a Total amount of bromides ³ Density TST ^b one a CaVg ₂ No 56, 3 wt. % 14.76 ppm (1.769 kg/l) 35.6°F (2.0°C) b CaVg ₂ No 56.0 wt. % 14.68 ppm (1.759 kg/l) 32.9°F (0.5°C) With CaVg ₂ No 55.4 wt. % 14.58 ppm (1.747 kg/l) 24.8°F (-4.0°С) 2 a CaVg ₂ No 56.9 wt. % 14.54 ppm (1.742 kg/l) 22.1°F (-5.5°С) b CaBr, ZnBr ₂ 6.0 wt% 56.0 wt. % 14.57 ppm (1.746 kg/l) <-5.8°F (<-21.0°C) 3 a CaVg ₂ No 58.5 wt. % 14.63 ppm (1.753 kg/l) 26.6°F (-3.0°C) b CaBr, ZnBr ₂ 22.9 wt. % 57.5 wt. % 14.67 ppm (1.757 kg/l) <-5.8°F (<-21.0°C) four a CaBr ₂ , LiBr 7.7 wt% 56.8 wt. % 14.55 ppm (1.743 kg/l) 33.8°F (1.0°C) b CaBrg, LiBr 27.5 wt. % 66, 1 wt. % 14.60 ppm (1.749 kg/l) 39.2°F (4.0°C)

^a based on the total weight of the solution;

^b true crystallization temperature, determined by the classical method

Example 1

A sample was prepared from 50.0 g of an aqueous solution of CaBr ₂ with a density of 14.2 ppg (1.70 kg/l). MnBr ₂ (3.27 g) was added to the CaBr ₂ solution. The results are shown in table. 2 below.

Example 2

A sample was prepared from 40.0 g of an aqueous solution of CaBr2 with a density of 12.8 ppg (1.53 kg/L). MnBr ₂ (10.18 g) was added to the CaBr ₂ solution. The results are shown in table. 2 below.

Example 3

Five separate samples were prepared by adding some MnBr ₂ to aqueous solutions of CaBr ₂ with densities from 13.4 to 14.0 ppg (1.61-1.68 kg/l) to obtain aqueous salt solutions with densities of approximately 14.6 -15.1 ppg (1.75-1.81 kg/l). Some of these samples were filtered to remove haze. All samples were then analyzed to determine their density and true crystallization temperature (TCT). The results are shown in table. 2 below.

Example 4

160 g of CaBr ₂ solution with a density of 14.2 ppg (1.70 kg/l) were placed in a 500 ml flask. The solution was heated to 60° C. and then 30 g of SnBr ₂ powder was added with stirring. After mixing in

- 11 039138 for about 1 hour at 60°C all SnBr2 dissolved, giving a cloudy yellowish brown solution. The solution was cooled to ambient temperature and then subjected to vacuum filtration through a 1 μm filter medium, obtaining a clear colorless solution with a density of 16 ppg (1.9 kg/l). To a portion of this solution (approximately 90 g) was added deionized water (9 g) to obtain after mixing a solution with a density of 15 ppg (1.8 kg/l). Both samples were kept at 6-7°F (-14.4°C to -13.9°C) in the freezer overnight, after 24 hours it was clear and colorless with no precipitate. The results are shown in table. 2 below.

Example 5

A jacketed 3 liter round bottom flask equipped with a mechanical stirrer, thermocouple and addition funnel was charged with an aqueous solution of CaBr ₂ (14.2 ppg; 673.68 g), deionized water (126.32 g) and MnO powder (99 wt. 67.92 g). While stirring, this slurry was heated to 67° C. and an aqueous solution of HBr (48 wt%; 320.96 g) was added over an addition funnel over 1 hour. After keeping at 67°C for 40 min, an aqueous solution of NaOH (50 wt%) or an aqueous solution of HBr (48 wt%) was used to titrate to pH 4.89; some formation of a solid phase was observed. The total amount of HBr and/or NaOH solution added was less than 10 g. After cooling to room temperature, the mixture was filtered under vacuum and more aqueous HBr solution (48 wt.%) was added to adjust the pH in the range of 3.0-3.5. A total of 2.04 g NaOH solution was added, less than 5 g HBr aqueous solution was added. Water (159 g) was removed under gentle vacuum at 54° C. to give a clear pink solution (1004 g) with a density of 1.78 g/mL (14.8 ppg) and pH 3.4. The results are shown in table. 2 below.

Example 6

A jacketed 3 liter round bottom flask equipped with a mechanical stirrer, thermocouple and addition funnel was charged with an aqueous solution of CaBr ₂ (14.2 ppg; 673.68 g), deionized water (126.32 g) and MnO powder (99 wt. 67.92 g). While stirring, this slurry was heated to 67° C. and an aqueous solution of HBr (48 wt%; 320.96 g) was added over an addition funnel over 1 hour. After keeping at 67°C for 35 min, an aqueous solution of HBr (48 wt%; 0.12 g) (48 wt%) was added to titrate to pH 3.18; some formation of a solid phase was observed. After cooling to room temperature, the mixture was filtered under vacuum. Water (165.6 g) was removed under low vacuum at 54° C. to give a clear pink solution (1010 g) with a density of 1.78 g/mL (14.9 ppg) and pH 3.03. The results are shown in table. 2 below.

- 12 039138

table 2

Etc. An experience Inorganic bromides Amount of bromide, EXCELLENT Total amount of bromides ³ Density TST ^b from CaBr ₂ ^a one - CaVgg, MpVgg 6.1 wt% 56.1 wt% 14.76 ppg (1.769 kg/l) 10.4°F (-12.0°C) 2 - CaVgg, MpVgg 20.3 wt% 56.0 wt% 14.63 ppg (1.753 kg/l) <-13°F (-25°C) 3 a CaVgg, MpVgg 9.3 wt% 56.5 wt% 14.89 ppg (1.784 kg/l) <-7.6°F (-22°C) b CaVgg, MpVgg 14.4 wt. % 56.5 wt. % 15.01 ppg (1.799 kg/l) -9.4°F (-23.0°C) With CaVgg, MpVgg 13.6 wt. % 55.3 wt. % 15.10 ppg (1.809 kg/l) 7.7°F (-13.5°C) d CaVgg, MpVgg 13.6 wt. % 57.6 wt. % 14.67 ppg (1.758 kg/l) <-13°F (-25°C) e CaVgg, MpVgg 20.1 wt. % 57.2 wt. % 14.63 ppg (1.753 kg/l) <-13°F (-25°C) four a SaVgg, ZpVgg 15.8 wt. % 60.6 wt. % 16 ppg (1.9 kg/l) low ⁰ b SaVgg, ZpVgg 6.4 wt.% 47.1 wt. % 15 ppg (1.8 kg/l) low ⁰ 5 - CaBr ₂ , MnO/NBr 20.0 wt% ^d 55.7 wt. % 14.8 ppg (1.78 kg/l) -14.8°F (-26°C) 6 - CaBr ₂ , MnO/NBr 20.1 wt% ^d 55.6 wt. % 14.9 ppg (1.78 kg/l) -13°F (-25°C)

^a based on the total weight of the solution;

^b true crystallization temperature, determined by the classical method;

^c below freezer temperature (6-7°F; -14.4--13.9°C); no precipitation in the samples after 1 week of storage in the freezer;

^d calculated for MnBr ₂

Example 7

Several samples of an aqueous CaBr ₂ /MnBr ₂ salt solution were prepared at different pH values, starting from an aqueous CaBr ₂ /MnBr ₂ salt solution prepared as in Example 5. The pH value of each sample was adjusted by adding an aqueous solution of HBr (48 wt.%) and /or an aqueous solution of NaOH (50%) until the desired pH is reached. In each sample, the total amount of HBr and/or NaOH solution added was less than 5 g. Some samples to which NaOH was added formed a small amount of precipitate, these samples were filtered. These samples with different pH values were placed for one week in an oven at 60°C for thermal aging. Turbidity and the presence or absence of sediment were observed visually and recorded after a week. The results are shown in table. 3 below.

- 13 039138

Example 8

Several samples of an aqueous CaBr2/MnBr2 salt solution were prepared at different pH values, starting from an aqueous CaBr2/MnBr2 salt solution prepared as in Example 5. The pH value of each sample was adjusted by adding an aqueous solution of HBr (48 wt.%) and/or aqueous NaOH solution (50%) until the desired pH is reached. In each sample, the total amount of HBr and/or NaOH solution added was less than 10 g. Some samples to which NaOH was added formed a small amount of precipitate, these samples were filtered. Sufficient glycerol was added to some samples to give a solution containing 5 or 10% by weight of glycerol. These samples with different pH values were placed for one week in an oven at 60°C for thermal aging. Turbidity and the presence or absence of sediment were observed visually and recorded after a week. The results are shown in table. 3 below.

Example 9

Example 8 was repeated except that all samples were kept at ambient temperature rather than heat aged. The results are shown in table. 3 below.

Example 10

Several samples of an aqueous CaBr2/MnBr2 salt solution having a pH of about 3.5 or less were used, as in Example 5.

Sufficient glycerol was added to these samples to give a solution containing 5 or 10% by weight of glycerol. All of these solutions remained clear, and none of the solutions showed precipitation over time at room temperature.

Table 3

Etc. Inorganic bromides Amount of glycerin ³ pH Turbidity Sediment T-ra aging 7 CaVgg, MpVgg 0 1.00 transparent No 60°C 1.99 transparent No 3.00 transparent No 3.16 transparent No 3.30 transparent No 3.40 transparent No 3.62 turbid No 3.99 turbid Yes 4.28 turbid Yes eight CaVgg, MpVgg 0 4.58 turbid Yes 60°С 5% 4.58 turbid No 0 4.28 turbid Yes 5% 4.28 transparent No ten% 4.28 transparent No 9 CaVgg, MpVgg 0 4.58 turbid Yes t-ra environments 5% 4.58 transparent No 0 4.28 turbid Yes 5% 4.28 transparent No ten% 4.28 transparent No

^a Based on the total weight of the solution Example 11.

A sample was prepared from 100.0 g of a clear aqueous solution of CaBr2/MnBr2 (1.75:1 (w:w) CaBr2:MnBr2) with a density of 15.0 ppg (1.80 kg/L). SnBr2 (7.00 g) was mixed with a clear aqueous solution of CaBr2/MnBr2 at 48°C. After the solids dissolved, the mixture was cooled to room temperature and then subjected to vacuum filtration through a 2 micron glass filter, obtaining a clear liquid with a density of 15.8 ppg (1.89 kg/l). Part of the water was removed in vacuo at 54°C, obtaining a clear saline solution with a density of 16.0 ppg (1.92 kg/l). A sample of this clear brine was analyzed to determine its true crystallization temperature (TCT), which was found to be below -23°C. The results are shown in table. 4 below.

In examples 12, 13, 14, 15 and 16, the densities were measured using a calibrated graduated cylinder. In this method, a 50 ml graduated cylinder was calibrated using 30,000 g of deionized water. The volume (29.7 ml) was recorded to calibrate the scale of the graduated cylinder.

- 14 039138

Each well fluid sample (29.7 ml) was weighed and the density calculated using the following formula: density(g/ml)=mass(g)/29.7 ml. For smaller samples, a 10 ml graduated cylinder was calibrated and used in a similar manner to determine the densities.

Example 12.

Several samples were prepared by mixing some SnBr ₄ (4.00 g; 9.00 g) or BiBr ₃ (4.00 g; 6.00 g) with 27.00 g of CaBr ₂ /MnBr ₂ (1 .75:1 (wt:wt) CaBr ₂ :MpBr ₂ ) with a density of 14.8 ppg (1.77 kg/l). All samples were then analyzed to determine their density. Each sample was filtered through a 1-micron syringe filter and one part of each sample was placed in a freezer at -16°C and the other part of each sample was placed in an oven at 60°C. All samples, both oven and freezer, remained clear after 3 days or longer. The results are shown in table. 4 below.

Table 4

Etc. An experience Inorganic bromides The amount of bromides other than CaBr ₂ ^a Number of MpVg ₂ ^a Total number of bromides ³ Density Solution remains clear at -16°C eleven - CaVg ₂ , MpVg, ZpVg 26, 3 wt. % 19.6 wt. % 60.6 wt. % 16.0 ppd (1.92 kg/l) at least one week 12 a CaBr ₂ , MnBrg, SnBr ₄ 30.6 wt. % 17.7 wt. % 61.5 wt. % 16, 1 pp (1.93 at least one kg/l) week b CaBr ₂ , MnBrg, SnBr ₄ 40.3 wt. % 15.3 wt. % 66.9 wt. % 17.5 ppm (2.10 kg/l) at least 3 days ^from With CaBr ₂ , MnBrg, SnBr ₄ 34.9 wt. % 16.7 wt. % 64.0 wt. % 16, 7 ppd (2.00 kg/l) at least one day d CaBr ₂ , MnBr ₂ , BiBrs 30.6 wt. % 17.7 wt. % 61.5 wt. % 16, 3 ppd (1.95 kg/l) at least one week e CaBr ₂ , MpBr ₂ , BiBr ₃ 41.0 wt. % 20.7 wt. % 61.5 wt. % 16.5 ppd (1.98 kg/l) at least one week

^and based on the total weight of the solution;

^b true crystallization temperature -34.95°C, determined by the instrumental method;

^c true crystallization temperature below -32°C, determined by instrumental method

Example 13

Two samples were prepared by mixing SnBr ₂ (1.30 g; 4.00 g) with 27.00 g of CaBr ₂ /MpBr ₂ clear aqueous saline solution (1.75:1 (w:w) CaBr ₂ :MpBr ₂ ), having a density of 15.3 ppg (1.83 kg / l). Both samples were then analyzed to determine their densities. Each sample was filtered through a 1 micron syringe filter, then enough formic acid was added to give a solution concentration of 2000 ppm. Then one part of each sample was placed in a freezer at -16°C, and the other part of each sample was placed in an oven at 60°C. The samples both in the oven and in the freezer remained clear after one week. The results are shown in table. 5 below.

- 15 039138

Example 14

Two different samples were prepared by mixing SnBr2 (6.00 g) or BiBr ₃ (6.00 g) with an aqueous solution of CaBr2 containing formic acid (2000 ppm) and having a density of 14.2 ppg (1.70 kg/l) . Both samples were then analyzed to determine their densities. Each sample was filtered through a 1 micron syringe filter, then enough formic acid was added to give a solution concentration of 2000 ppm. Then, one part of each sample was placed in a freezer at -16°C, and the other part of each sample was placed in an oven at 60°C. The samples both in the oven and in the freezer remained clear overnight or longer. The results are shown in table. 5 below.

Table 5

Etc. An experience Inorganic bromides The amount of bromides other than CaBr ₂ ^a Number of MpVg ₂ ^a Total number of bromides ³ Density Solution remains clear at -16°C 13 a CaBr ₂ , MpBr ₂ , SnBr ₂ 24.0 wt. % 19.4 wt. % 57.9 wt. % 15.9 ppd (1.90 kg/l) at least one week b CaBr ₂ , MpBr ₂ , SnBr ₂ 30.6 wt. % 17.7 wt. % 61.5 wt. % 16, 3 ppd (1.95 kg/l) at least one week fourteen a CaBr ₂ , SnBr ₂ 18.2 wt. % No 61.7 wt. % 16.2 ppd (1.94 kg/l) at least during the night b CaBr ₂ , BrBrz 18.2 wt. % No 61.7 wt. % 16, 6 ppd (1.99 kg/l) at least 2 DAYS

^a based on the total weight of the solution

Example 15

Several samples were prepared by mixing some of one or more inorganic bromide salts and, in some cases, deionized water and formic acid, with some of an aqueous solution of calcium bromide with a density of 14.2 ppg (1/70 kg/l; WellBrom®, Albemarle Corporation ). Each mixture was heated to dissolve the solid. The details for obtaining each solution are as follows:

formic acid (80.0 mg) and InBr ₃ (6.00 g): deionized water (0.50 g) was added to 27.00 g of calcium bromide solution; heating up to 50°C;

InBr ₃ (6.90 g) and 27.00 g calcium bromide solution; heating up to 48-50°C;

an aqueous solution of MnBr ₂ (14.10 g; 50.3 wt%) and InBr ₃ (6.96 g); 13.15 g of calcium bromide solution; heating up to 48-50°C; and formic acid (80.0 mg) and SnBr ₄ with 27.00 g of calcium bromide solution to which deionized water (0.73 g) was added; heating up to 49°C.

After the solids had dissolved, the mixture was cooled to room temperature. After cooling to room temperature, each solution was analyzed to determine its density. One sample of each solution was placed in a -16°C freezer and another sample of each solution was placed in an oven at 60°C. The results are shown in table. 6 below.

Example 16

A sample was prepared by mixing SnBr ₄ (10.17 g) and deionized water (4.11 g) containing HBr (0.02 g; 48%). The mixture was heated to 35°C to dissolve the solids. After the solids dissolved, the mixture was cooled to room temperature, obtaining a clear liquid having a density of 18.8 ppg (2.25 kg/l). One sample of the solution was placed in a freezer at -16°C, and the other sample

- 16 039138 solution was placed in an oven at 60°C. The samples both in the oven and in the freezer remained transparent after 72 hours. The results are shown in table. 6 below.

Example 17.

A sample was prepared by mixing InBr ₃ and deionized water in such quantities as to form a clear solution with a density of 16.0 ppg (1.92 kg/l), the sample of which was placed in a freezer at -16°C. The results are shown in table. 6 below.

Table 6

Etc. An experience Inorganic Qty Complete Formic Raft- Solution bromides bromides f other than CaBr2 ^a number of bromides ³ acid ness remains clear at -16°C fifteen a CaBg ₂ , 1pBg ₃ 17.9 wt. % 60.8 wt% 2280ppm 16.0 prd (1.92 kg/l) at least 6 days b CaBg ₂ , MpBg ₂ , 1pBg ₃ 36.6 wt% 64.9 wt% No 17.2 ppd (2.06 kg/l) at least 72 ^hours With CaBg ₂ , MpBg ₂ , 1pBg ₃ 41.0 wt. % 61.5 wt% No 16, 6 ppd (1.99 kg/l) at least 96 hours d CaBr ₂ , SnBr ₄ 24.5 wt. % 63.7 wt% 2700ppm 16.5 ppd (1.98 kg/l) at least 6 days 16 - ZpVG4 71.1 wt. % 71.1 wt% No 18.8 prr (2.25 kg/l) at least 72 hours 17 - 1pVg ₃ 60 wt% 60 wt% No 16.0 prr (1.92 kg/l) at least 24 hours

^a based on the total weight of the solution;

^b true crystallization temperature below -32°C; determined by instrumental method

Example 18.

Several samples were prepared by dissolving some Mn(NO ₃ )2-H2O in deionized water at ambient temperature, adding CaBr ₂ to the solution and in some cases also adding HNO ₃ or HCl. Each mixture was heated to dissolve the solids. The details for obtaining each solution are as follows:

a) Mn(NO ₃ ) ₂ -H ₂ O (24.4 g) and deionized water (10.70 g), CaBr ₂ (20.45 g) was added at 56°C;

b) Mn(NO ₃ ) ₂ -H ₂ O (12.20 g) and deionized water (5.35 g), then CaBr ₂ (10.23 g), HNO ₃ (concentrated, 65 mg) were added;

c) Mn(NO ₃ ) ₂ -H ₂ O (12.20 g) and deionized water (2.09 g), CaBr ₂ (5.02 g);

d) Mn(NO ₃ ) ₂ -H ₂ O (12.20 g) and deionized water (5.35 g), then HCl (concentrated, 58 mg) was added, then CaBr ₂ (10.23 g) was added.

After the solids had dissolved, each mixture was cooled to room temperature. Cooled solutions were clear. After cooling to room temperature, each

- 17 039138 the sample was filtered through a 1 micron syringe filter and analyzed to determine its density. A portion of each sample was placed in a freezer at -16°C. None of the freezer samples formed crystals for at least one week. The results are shown in table. 7 below.

Example 19.

A sample was prepared by adding Mn(NO ₃ )2-H2O (3.00 g) to an aqueous solution of CaBr2 (57.6 wt%, 25.05 g). The mixture was heated to 50°C and then cooled to room temperature, obtaining a clear light pink solution with a density of 15.3 ppg (1.83 kg/l). After filtration through a 1 micron syringe filter, one part of the sample was placed in a freezer at -16°C, and the other part of the sample was placed in an oven at 60°C. Both samples remained clear after 24 hours. The results are shown in table. 7 below.

Table 7

Etc. An experience Inorganic bromides Amount of bromide OTHER THAN CaBr ₂ a Total number of bromides ³ Acid Density Solution remains clear at -16°C eighteen a CaVg ₂ 36.8 wt. % 43.9 wt. % - 14.9 ppm (1.79 kg/l) at least at least one week eighteen b CaVg ₂ 36.7 wt. % 43.8 wt. % _HNO3 14.9 ppm (1.79 kg/l) at least at least one week eighteen With CaVg ₂ 26.0 wt. % 57.2 wt. % - 15.1 pp (1.81 at least one kg/l) week eighteen d CaBr ₂ 36.7 wt. % 39.7 wt. % HC1 15.0 ppm (1.80 kg/l) at least at least one week 19 - CaVg ₂ 51.4 wt% 10.7 wt% - 15.3 pp (1.83 kg/l) at least 24 hours

^a based on the total weight of the solution

Example 20.

Several samples were prepared by diluting an aqueous solution of CaBr ₂ or MnBr ₂ with deionized water and adding some sodium metatungstate to the diluted solution at ambient temperature. Then each mixture was heated. The details for obtaining each solution are as follows:

a) CaBr ₂ (aqueous solution, 53.2 wt.%, 15.05 g), deionized water (2.81 g), sodium metatungstate hydrate (4.50 g); heating up to 54-56°C;

b) MnBr ₂ (aqueous solution, 50 wt.%, 15.00 g), deionized water (2.00 g), sodium metatungstate hydrate (3.29 g); heating up to 35°C;

c) MnBr ₂ (aqueous solution, 50 wt.%, 15.00 g), deionized water (2.00 g), sodium metatungstate hydrate (6.00 g); heating up to 50-58°C.

After the solids had dissolved, each mixture was cooled to room temperature. After cooling to room temperature, each sample was filtered through a 1 micron syringe filter to give clear, colorless solutions. Each sample was then analyzed to determine its density. A portion of each sample was placed in a freezer at -16°C. All samples in the freezer remained clear at least overnight. The results are shown in table. 8 below.

Example 21.

Two samples were prepared by mixing some lithium bromide with the metatungstate salt. The details for preparing each solution are as follows.

A) LiBr (8.00 g) was dissolved in deionized water (12.04 g). To this solution was added sodium metatungstate hydrate (8.33 g) to give a colorless solution with a density of 15.0 ppg (1.80 kg/l).

B) LiBr (10.00g) was dissolved in deionized water (10.00g). An aqueous solution was added to this solution.

- 18 039138 solution of lithium metatungstate (p=2.95 g/ml), obtaining a colorless solution with a density of 16.3 ppg (1.95 kg/l).

Each solution was filtered through a 1 micron syringe filter, after which one part of each sample was placed in a freezer at -16°C, and the other part of each sample was placed in an oven at 60°C. Samples from run A, both from freezer and oven, remained clear after one week. Samples from run B, both from the freezer and from the oven, remained clear after at least 20 hours. The results are shown in table. 8 below.

Table 8

Etc. An experience Inorganic bromide Total amount of bromides ³ Total amount of metatungstate salt ³ Density TST ^b twenty a CaVg ₂ 35.8 wt. % 20.0 wt% 14.9 ppm (1.79 kg/l) -27.8°С twenty b MpVg ₂ 37.0 wt. % 18.8 wt% 15.3 pp (1.83 kg/l) _With twenty With MpVg ₂ 32.6 wt. % 25.9 wt% 16.4 ppm (1.97 kg/l) -31.01°C 21 BUT LiBr 28.2 wt. % 29.4 wt% 15.0 ppm (1.80 kg/l) -29.8°С 21 AT LiBr 16.3 pp (1.95 kg/l) _d

^and based on the total weight of the solution;

^b true crystallization temperature, determined by the instrumental method;

^c solution remained clear at -16°C overnight;

^d the solution remained clear at -16°C for at least 20 hours

Components referred to by their chemical name or formula anywhere in a description or claim, whether singular or plural, are identified as they exist prior to their coming into contact with another substance denoted by its chemical name or chemical type. (eg other component, solvent, etc.). It does not matter what chemical changes, transformations and/or reactions, if any, take place in the resulting mixture or solution, since such changes, transformations and/or reactions are a natural consequence of bringing together these components under the conditions required according to the present invention . Thus, the components are identified as ingredients that must be brought together to carry out the desired operation or to form the desired composition. Similarly, even though the claims below may refer to substances, components and/or ingredients in the present tense (contains, has, etc.), the reference refers to the substance, component or ingredient as it existed at the moment immediately before its first contact, blending or mixing with one or more other substances, components and/or ingredients in accordance with the present invention. Thus, the fact that a substance, component or ingredient may lose its original identity due to a chemical reaction or transformation during contacting, blending or mixing operations is of no practical importance if carried out in accordance with the present invention by a chemist of average skill.

The invention may include, consist of, or essentially consist of the materials and/or procedures listed herein.

As used herein, the term approximately modifying the amount of a component in the compositions of the invention or used in the methods of the invention, refers to changes in numerical value that may occur, for example, as a result of typical procedures for measuring and handling liquids used to prepare concentrates or when using solutions in real conditions; due to unintentional errors in these procedures; due to differences in manufacturing, source or purity of ingredients used to make compositions or to carry out methods, etc. The term also roughly encompasses amounts that differ due to different equilibrium conditions for a composition made from a particular feed mixture. Whether or not modified by the term approximately, the claims include the equivalents of these quantities.

Unless expressly stated otherwise, the use of the singular in this document is not intended to be limiting and should not be construed as a limiting description or

- 19039138 the formula is the only element referred to in the singular. On the contrary, unless the text explicitly states otherwise, the use of the singular is intended to cover one or more of these elements.

The present invention is subject to significant changes in its practical implementation. Thus, the foregoing description is not intended to be limiting, and should not be construed as limiting the invention to the particular illustrative examples set forth above.

Claims (24)

CLAIM 1. A well fluid containing a zinc-free aqueous brine having a density of 1.71 kg/L (14.3 lbs per gallon) or greater and a true crystallization temperature of -6.7°C (20°F) or less, wherein said aqueous the saline solution contains calcium bromide and a manganese salt selected from manganese (II) bromide, manganese (II) nitrate and manganese polytungstate. 2. The wellbore fluid of claim 1, wherein the manganese salt is manganese(II) bromide. 3. A wellbore fluid according to claim 1 or 2, wherein said aqueous brine has a density of 1.75 kg/L (14.6 pounds per gallon) or greater. 4. The well fluid of claim 2 wherein said aqueous brine has a density of 1.75 kg/L (14.6 lbs per gallon) or greater and a pH in the range of 2.5 to 5. 5. A wellbore fluid according to claim 2, also containing tin (IV) bromide, wherein said aqueous brine has a density of 1.80 kg/l (15.0 pounds per gallon) or greater. 6. A well fluid according to claim 2, also containing bismuth (III) bromide, wherein said aqueous brine has a density of 1.92 kg/l (16.0 pounds per gallon) or greater. 7. Well fluid according to claim 2, also containing tin (II) bromide or indium (III) bromide. 8. The well fluid according to claim 2, which also contains tin(II) bromide, wherein said aqueous brine has a density of 1.80 kg/l (15.0 pounds per gallon) or more; or indium(III) bromide, wherein said aqueous brine has a density of 1.92 kg/l (16.0 lbs per gallon) or greater. 9. The method for producing a well fluid according to claims 1 to 8, including mixing, in any order, components containing water, calcium bromide and a manganese salt selected from manganese (II) bromide, manganese (II) nitrate and manganese polytungstate. 10. The method of claim 9 wherein the manganese salt is manganese(II) bromide. 11. The method of claim 9 or 10 wherein said aqueous brine has a density of 1.75 kg/l (14.6 lbs per gallon) or greater. 12. The method of claim 10 wherein said aqueous brine has a density of 1.75 kg/L (14.6 lbs per gallon) or greater and a pH in the range of 2.5 to 5. 13. The method of claim 10, wherein said aqueous brine also contains tin(IV) bromide, wherein said aqueous brine has a density of 1.80 kg/L (15.0 lbs per gallon) or greater. 14. The method of claim 10, wherein said aqueous brine also contains bismuth(III) bromide, wherein said aqueous brine has a density of 1.92 kg/L (16.0 lbs per gallon) or greater. 15. The method of claim 10 wherein said aqueous saline solution also contains tin(II) bromide or indium(III) bromide. 16. The method of claim 10, wherein said aqueous brine also contains tin(II) bromide, wherein said aqueous brine has a density of 1.80 kg/l (15.0 lbs per gallon) or greater; or indium(III) bromide, wherein said aqueous brine has a density of 1.92 kg/l (16.0 lbs per gallon) or greater. 17. A well treatment method comprising injecting a wellbore fluid containing a zinc-free aqueous brine having a density of 1.71 kg/l (14.3 lb per gallon) or greater and a true crystallization temperature of -6.7°C ( 20°F) or lower, wherein said fluid contains calcium bromide and a manganese salt selected from manganese (II) bromide, manganese (II) nitrate and manganese polytungstate. 18. The method of claim 17 wherein the manganese salt is manganese(II) bromide. 19. The method according to claim 17 or 18, wherein said aqueous brine has a density of 1.75 kg/l (14.6 pounds per gallon) or greater. 20. The method of claim 18 wherein said aqueous brine has a density of 1.75 kg/L (14.6 lbs per gallon) or greater and a pH in the range of 2.5 to 5. 21. The method of claim 18, wherein said aqueous brine also contains tin(IV) bromide, wherein said aqueous brine has a density of 1.80 kg/L (15.0 lbs per gallon) or - 20 039138 more. 22. The method of claim 18, wherein said aqueous brine also contains bismuth (B) bromide, wherein said aqueous brine has a density of 1.92 kg/L (16.0 lbs per gallon) or greater. 23. The method of claim 18, wherein said aqueous saline also contains tin(II) bromide or indium(III) bromide. 24. The method of claim 18, wherein said aqueous brine also contains tin(II) bromide, wherein said aqueous brine has a density of 1.80 kg/L (15.0 pounds per gallon) or greater; or indium(III) bromide, wherein said aqueous brine has a density of 1.92 kg/l (16.0 lbs per gallon) or greater.