Method for producing heavy well kill fluid

Abstract

The invention relates to the field of the oil production industry, and more particularly to heavy well kill fluids containing at least one of the compounds: calcium bromide, barium bromide, magnesium bromide, strontium bromide, zinc bromide, calcium iodide, barium iodide, magnesium iodide, strontium iodide and zinc iodide, and to methods for producing same. The invention discloses a method which makes it possible to broaden the range of components that can be used to produce heavy kill fluids. The claimed method makes it possible to produce a heavy well kill fluid using accessible salt solutions, wherein the resulting fluid has the necessary properties for effectively killing wells. The claimed method includes mixing solutions of salts at a molar ratio of 0.5-1.3:2, evaporating the resulting mixed solution to a density of 1400-2650 kg / m3, cooling the evaporated solution to a temperature of less than 25°C to form a precipitate, and filtering the evaporated solution to obtain a filtrate in the form of a heavy well kill fluid.

Description

[0001] Method for producing heavy well killing fluid

[0002] Field of technology.

[0003] The invention relates to the oil industry, specifically to heavy well-killing fluids comprising at least one of the following compounds: calcium bromide, barium bromide, magnesium bromide, strontium bromide, zinc bromide, calcium iodide, barium iodide, magnesium iodide, strontium iodide, or zinc iodide, and methods for producing them. The invention discloses a method for expanding the range of components for producing heavy well-killing fluids.

[0004] State of the art.

[0005] Heavy well killing fluids, or heavy killing fluids, or heavy process fluids, are used to create back pressure on the formation in order to prevent the influx of fluids or gases into the well; such measures can be carried out for well repair and maintenance, as well as in a number of emergency situations.

[0006] In the oil production industry, heavy well-killing fluids based on calcium bromide, barium bromide, strontium bromide, and zinc bromide have become widely used due to the high specific gravity of solutions of these substances.

[0007] At the same time, solutions of magnesium bromide, calcium iodide, barium iodide, magnesium iodide, strontium iodide, and zinc iodide also have a high specific gravity and can be used for the same purposes, but their use has not become widespread due to their high cost.

[0008] Thus, a process fluid for well killing and preservation is known from the prior art, according to patent RU2599395C1 "Process fluid for well workover" (priority date 05.06.2015), which may contain zinc iodide in an amount of 20 to 50% by weight. The fluid also contains a polyhydric alcohol, calcium bromide, and water; zinc bromide can be used instead of zinc iodide.

[0009] The patent does not disclose an accessible method for producing calcium bromide, zinc bromide, and zinc iodide, which are part of the liquid, which is a disadvantage, since the use of ready-made salts to produce the liquid is expensive.

[0010] A heavy process fluid for killing wells is known from the prior art according to patent RU2731965C1 “Heavy process fluid for killing wells, composition and method for its preparation” (priority date 09.09.2019), which is obtained by dissolving 35-41 wt.% calcium nitrate in water and adding calcium bromide to obtain fluids with densities from 1580 to 1820 kg / m3 3 at 20 °C.

[0011] The disadvantage of the technology for producing this well killing fluid is that it does not include a method for producing calcium bromide as part of the fluid, and the use of ready-made salt to produce the fluid is expensive.

[0012] A solution for preparing high-density process fluids is known from the prior art according to patent SU1189868 A 1 “Solution for preparing process fluids” (priority date 07.11.1985), this solution contains, by weight %:

[0013] Calcium bromide - 57 - 59;

[0014] Calcium hydroxide - 0.2 - 0.4;

[0015] Free ammonia - 0.2 - 0.4;

[0016] Water is the rest.

[0017] The preparation of a calcium bromide solution for the preparation of process fluids based on it is carried out according to the following scheme:

[0018] The presented method for producing calcium bromide solution has several drawbacks, particularly the use of molecular bromine, a toxic substance, which increases the hazard level of such production. A prior art fluid, according to patent BAZ 7172B 1 "Well Fluid Used with Swelling Elements" (application date May 18, 2012), may, in one embodiment, include calcium bromide, zinc bromide, and magnesium bromide. The patent does not disclose the technology for producing calcium bromide, zinc bromide, and magnesium bromide in the fluid, and using pre-mixed salts to produce the fluid is expensive.

[0019] A concentrated salt solution suitable as a well fluid is known from the prior art according to patent EA12513B1 “Solid-free concentrated salt solution suitable as a well fluid” (application date 12 / 14 / 2005), which, according to one embodiment of the invention, may include magnesium bromide, calcium bromide, strontium bromide, zinc bromide.

[0020] The patent does not disclose an accessible method for obtaining magnesium bromide, calcium bromide, strontium bromide, and zinc bromide, which are part of the liquid, which is a disadvantage, since the use of ready-made salts to obtain the liquid is expensive.

[0021] As can be seen from the examples provided, the use of the said salts for heavy well killing fluids is a common practice, while the identified technical solutions do not disclose accessible and safe methods for obtaining solutions of calcium bromide, barium bromide, magnesium bromide, strontium bromide, zinc bromide, calcium iodide, barium iodide, magnesium iodide, strontium iodide, and zinc iodide for these purposes.

[0022] The essence of the invention.

[0023] The aim of the present invention is to expand the arsenal of methods for producing heavy killing fluids and available components for producing heavy killing fluids.

[0024] The technical result of the invention is the production of a heavy well-killing fluid using readily available brine solutions, with the resulting fluid possessing the necessary characteristics for effective well-killing. PC17RU2025 / 000229

[0025] The use of available salt solutions and the implementation of the method according to this patent ensures the minimization of costs for the production of heavy killing fluids due to the elimination of the use of ready-made salts in the composition: calcium bromide, barium bromide, magnesium bromide, strontium bromide, zinc bromide, calcium iodide, barium iodide, magnesium iodide, strontium iodide, zinc iodide, or their solutions, which have a significant price.

[0026] The technical result is achieved in that, according to the first embodiment, the method for producing a heavy fluid for killing wells includes: mixing a first solution including one or more salts selected from magnesium chloride, barium chloride, strontium chloride, zinc chloride, with a second solution including one or more salts selected from sodium iodide, potassium iodide, sodium bromide, potassium bromide, while maintaining the molar ratio of the sum of said salts or salts included in the first solution to the sum of said salts or salts included in the second solution equal to 0.5-1.3:2; evaporating the solution obtained as a result of mixing to a density of 1400-2650 kg / m3 3; cooling the evaporated solution to a temperature of less than 25 °C to form crystals of sodium chloride or potassium chloride, or a mixture thereof; filtering the evaporated solution to obtain a filtrate in the form of a heavy well killing fluid containing at least one of the following salts: magnesium iodide, magnesium bromide, barium iodide, barium bromide, strontium iodide, strontium bromide, zinc iodide, zinc bromide, or any combination thereof.

[0027] The technical result is achieved in that, according to the second embodiment, the method for producing a heavy well killing fluid comprises: mixing a first solution including calcium chloride with a second solution including one or more salts selected from sodium iodide, potassium iodide, potassium bromide, while maintaining a molar ratio of calcium chloride in the first solution to the sum of said salts or salts included in the second solution equal to 0.5-1.3:2; evaporating the solution obtained as a result of mixing to a density of 1400-2650 kg / m3; cooling the evaporated solution to a temperature of less than 25 °C with the formation of crystals of sodium chloride, or potassium chloride, or a mixture thereof; filtering the evaporated solution to obtain a filtrate in the form of a heavy well killing fluid containing calcium bromide, or calcium iodide, or a mixture thereof.The technical result is achieved in that, according to the third embodiment, the method for producing a heavy well killing fluid includes: mixing a first solution including calcium chloride and one or more salts selected from magnesium chloride, barium chloride, strontium chloride, zinc chloride, with a second solution including one or more salts selected from sodium iodide, potassium iodide, potassium bromide, while maintaining a molar ratio of the sum of said salts included in the first solution to the sum of said salts or salts included in the second solution equal to 0.5-1.3:2; evaporating the solution obtained as a result of mixing to a density of 1400-2650 kg / m3. 3; cooling the evaporated solution to a temperature below 25 °C to form crystals of sodium chloride or potassium chloride or a mixture thereof; filtering the evaporated solution to obtain a filtrate in the form of a heavy well killing fluid containing calcium bromide or calcium iodide or a mixture thereof, as well as one of the following salts: magnesium iodide, magnesium bromide, barium iodide, barium bromide, strontium iodide, strontium bromide, zinc iodide, zinc bromide, or any combination thereof.

[0028] The technical result is achieved in that the mixed solutions can have a temperature from 40 to 120 °C, and before evaporation, the solution obtained as a result of their mixing is filtered; the cake separated as a result of filtration in the form of crystals of sodium chloride or potassium chloride, or a mixture thereof, can be dissolved in water and injected into the formation; the cake separated as a result of filtration in the form of crystals can be washed with water and dried; the water after washing the crystals can be sent for evaporation together with the solution obtained as a result of mixing; after cooling the evaporated solution and before its filtration, the solid phase in the form of precipitated crystals can be separated by centrifugation or settling, the separated solid phase can be washed and dried; the resulting heavy well killing fluid can be evaporated to obtain a dry product, after which, by dissolving the dry product in water, a new heavy well killing fluid can be obtained;The resulting heavy well-killing fluid can be mixed with additional components before being fed into the well; the described methods result in the production of well-killing fluid. PC17RU2025 / 000229;

[0029] The technical result is achieved in that mixing the first solution, including one or more salts selected from magnesium chloride, barium chloride, strontium chloride, zinc chloride, with the second solution, including one or more salts selected from sodium iodide, potassium iodide, sodium bromide, potassium bromide, while maintaining the molar ratio of the sum of the said salts or salts included in the first solution to the sum of the said salts or salts included in the second solution equal to 0.5-1.3:2 ensures the reaction and the production of a solution, including at least one of the salts: magnesium iodide, magnesium bromide, barium iodide, barium bromide, strontium iodide, strontium bromide, zinc iodide, zinc bromide, or any combination thereof, such a solution can be used as a raw material for the production of heavy killing fluid, since Solutions of magnesium iodide, magnesium bromide, barium iodide, barium bromide, strontium iodide, strontium bromide, zinc iodide, zinc bromide have a high specific density.Also, the original salts in the form of magnesium chloride, barium chloride, strontium chloride, zinc chloride, sodium iodide, potassium iodide, sodium bromide, potassium bromide are more accessible, including in the composition of waters and brines, than ready-made salts and solutions of magnesium iodide, magnesium bromide, barium iodide, barium bromide, strontium iodide, strontium bromide, zinc iodide, which provides the opportunity to expand the raw material base and reduces the cost of the final product.

[0030] The technical result is achieved by mixing a first solution containing calcium chloride with a second solution containing one or more salts selected from sodium iodide, potassium iodide, or potassium bromide, while maintaining a molar ratio of calcium chloride in the first solution to the sum of the said salts or salts included in the second solution of 0.5-1.3:2, ensuring the reaction and the production of a solution containing at least one of the salts: calcium bromide, calcium iodide, or a mixture thereof. Such a solution can be used as a feedstock for producing heavy well killing fluid, since calcium bromide and calcium iodide solutions have a high specific gravity. Also, the starting salts in the form of calcium chloride, sodium iodide, potassium iodide, and potassium bromide are more readily available, including in the composition of waters and brines than ready-made salts and solutions of calcium bromide and calcium iodide, which provides the possibility of expanding the raw material base and reduces the cost of the final product.The technical result is achieved in that mixing a first solution including calcium chloride and one or more salts selected from magnesium chloride, barium chloride, strontium chloride, zinc chloride, with a second solution including one or more salts selected from sodium iodide, potassium iodide, potassium bromide, while maintaining the molar ratio of the sum of said salts included in the first solution to the sum of said salts or salts included in the second solution equal to 0.5-1.3:2 ensures the reaction and the production of a solution including at least one of the salts: calcium bromide, or calcium iodide, or a mixture thereof, as well as one of the salts: magnesium iodide, magnesium bromide, barium iodide, barium bromide, strontium iodide, strontium bromide, zinc iodide, zinc bromide, or any combination thereof, such a solution can be used as a raw material for obtaining a heavy liquid jamming, becauseSolutions of calcium bromide, calcium iodide, magnesium iodide, magnesium bromide, barium iodide, barium bromide, strontium iodide, strontium bromide, zinc iodide, and zinc bromide have a high specific gravity. Furthermore, the initial salts in the form of calcium chloride, magnesium chloride, barium chloride, strontium chloride, zinc chloride, sodium iodide, potassium iodide, and potassium bromide are more readily available, including in waters and brines, than ready-made salts and solutions of calcium bromide, calcium iodide, magnesium iodide, magnesium bromide, barium iodide, barium bromide, strontium iodide, strontium bromide, zinc iodide, and zinc bromide. This allows for an expanded raw material base and a lower cost of the final product.

[0031] The technical result is achieved by evaporating the solution obtained as a result of mixing and reaction to a density of 1400-2650 kg / m3. 3, provides the required density of the resulting heavy fluid for killing wells, which makes it possible to effectively use it for its intended purpose.

[0032] The technical result is achieved by the fact that it is evaporated to a density of 1400-2650 kg / m3 3 The solution is cooled to a temperature below 25°C, which ensures effective salting out of sodium chloride, potassium chloride, or their mixture. This removes them from the solution, improves product purity, and prevents equipment from becoming clogged with salt crystals. The technical result is achieved by filtration of the evaporated and cooled solution, which allows for the most complete separation of sodium chloride, potassium chloride, or their mixture crystals, improving product purity, and preventing equipment from becoming clogged with salt crystals.

[0033] The technical result can also be achieved by allowing the mixed solutions to have temperatures ranging from 40 to 120°C, allowing for the use of more saturated solutions due to their greater solubility in hot water. This accelerates the reaction, saves heat transfer fluid and time during the subsequent evaporation of the solution, and reduces water consumption during solution preparation. Furthermore, before evaporation, the resulting mixed solution is filtered, allowing for the separation of some of the sodium or potassium chloride, facilitating further processing of the mixed solution.

[0034] The technical result can also be achieved by the fact that the cake separated as a result of filtration in the form of crystals of sodium chloride or potassium chloride, or a mixture thereof, can be dissolved in water and pumped into the formation, which ensures the utilization and use of this solution to meet the needs of operation or drilling of wells, which increases the economic effect of the process.

[0035] The technical result can also be achieved by the fact that the cake separated as a result of filtration in the form of crystals can be washed with water and dried, which makes it possible to obtain a separate product in the form of sodium chloride, potassium chloride or a mixture thereof and to increase the economic effect of the process, while washing the crystals increases the purity of the product.

[0036] The technical result can also be achieved by directing the water after washing the crystals for evaporation together with the resulting solution, which reduces material losses and increases the efficiency of the process.

[0037] The technical result can also be achieved by the fact that after cooling the evaporated solution and before its filtration, the solid phase in the form of precipitated crystals can be separated by centrifugation or settling, which ensures the effective separation of crystals from the solution and allows for a reduction in the load on filters at the filtration stage, which simplifies the process of separating crystals and increases the cost-effectiveness of the process.

[0038] The technical result can also be achieved by the fact that the obtained heavy well-killing fluid can be evaporated to obtain a dry product, after which, by dissolving the dry product in water, a heavy well-killing fluid can be obtained again, which increases the commercial properties of the heavy well-killing fluid, due to the possibility of selling it in dry form and simplifying transportation to the place of use.

[0039] The technical result can also be achieved by mixing the resulting heavy well killing fluid with additional components before feeding it into the well; the use of such a base ensures a reduction in the cost of the final fluid.

[0040] The technical result can also be achieved by the fact that, as a result of the described methods, a well killing fluid is obtained that has the necessary characteristics, including density, to create the necessary back pressure on the formation in order to prevent the influx of fluids or gases into the well, killing the well.

[0041] Description of drawings.

[0042] Fig. 1. General diagram of the method implementation.

[0043] Fig. 2. Particular diagram of the method implementation.

[0044] Table 1. First embodiment of the invention. Solution components.

[0045] Table 2. Second embodiment of the invention.

[0046] Components of solutions.

[0047] Table 3. Third embodiment of the invention.

[0048] Components of solutions.

[0049] Table 4. Obtaining target substances in the solution.

[0050] In its most general form, the method of the present invention can be implemented as set out below, but is not limited thereto. A general flow chart of the method is shown in Fig. 1. To implement the method, a first saline solution and a second saline solution are mixed, maintaining a molar ratio of the sum of the salts or salts included in the first solution to the sum of the salts or salts included in the second solution of 0.5-1.3:2.

[0051] Mixing can be carried out in a flow-type reactor, in a perfectly mixed reactor, or in another type of reactor that ensures efficient mixing of solutions.

[0052] During the mixing of the solutions, a reaction occurs to form target salts such as calcium bromide, barium bromide, magnesium bromide, strontium bromide, zinc bromide, calcium iodide, barium iodide, magnesium iodide, strontium iodide, zinc iodide, or combinations thereof, and by-product salts such as sodium chloride or potassium chloride, or mixtures thereof.

[0053] In this case, the target salts remain in a dissolved state, and the by-product salts, depending on the concentrations of the initial solutions, may partially precipitate.

[0054] The resulting solution is sent for evaporation, where the density of the solution is brought to 1400-2650 kg / m3 3 , and then cooled to a temperature below 25 °C, during which the solution actively precipitates by-product salts, such as sodium chloride or potassium chloride, or a mixture thereof, the cooled solution is sent for filtration to separate from the precipitated crystals, the resulting filtrate is a heavy liquid suitable for killing wells.

[0055] A specific flow chart of the method is shown in Figure 2. This method differs from the previous one by the addition of a filtration step after mixing the first and second salt solutions, but before evaporation. This step removes any crystals of by-product salts that may have precipitated during the reaction, simplifying further processing of the solution.

[0056] According to the first embodiment of the invention, the first saline solution contains one or more salts selected from magnesium chloride, barium chloride, strontium chloride, zinc chloride, and the second solution contains one or more salts selected from sodium iodide, potassium iodide, sodium bromide, potassium bromide, combinations of possible reactions are shown in Table 1.

[0057] Table 1 - First embodiment of the invention. Solution components.

[0058] According to the first embodiment of the invention, the exchange reactions can be represented in the form of the formula: where M 1 = Mg, Ba, Sr, Zn; M 2 = Na, K; X = Br, I.

[0059] According to the second embodiment of the invention, the first saline solution contains calcium chloride, and the second solution contains one or more salts selected from sodium iodide, potassium iodide, potassium bromide, combinations of possible reactions are given in Table 2.

[0060] Table 2 - Second embodiment of the invention. Solution components.

[0061] According to the second embodiment of the invention, the exchange reactions can be represented in the form of formulas:

[0062] CaС12+ 2NaI -► Cal2+ 2NaCl|;

[0063] CaC12+ 2KBr -> CaBr2+ 2KSC.

[0064] According to a third embodiment of the invention, the first saline solution comprises calcium chloride and one or more salts selected from magnesium chloride, barium chloride, strontium chloride, zinc chloride, and the second solution comprises one or more salts selected from sodium iodide, potassium iodide, potassium bromide, combinations of possible reactions are shown in Table 3.

[0065] Table 3 - Third embodiment of the invention. Solution components.

[0066] According to the third embodiment of the invention, the exchange reactions can be represented in the form of formulas:

[0067] CaC12+ MS12+ 4NaI Cal2+ Znl2+ 4NaClj;

[0068] CaC12+ MC12+ 4KX -* CaX2+ ZnX2+ 4KSC, where M = Mg, Ba, Sr, Zn; X - Br, I.

[0069] The composition of the solutions entering into the reaction is not limited to the presence of one or two salts; solutions may include more than one of the specified salts in any combination.

[0070] For example, according to the first embodiment of the invention, the reaction can be carried out using MgCl2, BaCl2, SrCl2, and ZnCl2 in the first solution and Na2Cl2, KI, NaBr, and KBr in the second solution. It is obvious to those skilled in the art that the exchange reactions will occur for any of the possible combinations of these substances in the first and second solutions.

[0071] In this case, for the reaction to proceed as completely as possible, it is necessary that the molar ratio of the sum of the indicated salts or salts included in the first solution to the sum of the indicated salts or salts included in the second solution be equal to 0.5-1.3:2.

[0072] Residual amounts of the original salts that enter into the reaction may remain in the composition of the TLS.

[0073] Thus, the TJS may contain not only calcium bromide, barium bromide, magnesium bromide, strontium bromide, zinc bromide, calcium iodide, barium iodide, magnesium iodide, strontium iodide, zinc iodide, but also residues of the original salts in the form of calcium chloride, magnesium chloride, barium chloride, strontium chloride, zinc chloride, sodium iodide, potassium iodide, sodium bromide, potassium bromide.

[0074] Below are specific examples of the implementation of the method according to the present invention.

[0075] Example 1.

[0076] Solutions containing the target substances in the form of calcium bromide, barium bromide, magnesium bromide, strontium bromide, zinc bromide, calcium iodide, barium iodide, magnesium iodide, strontium iodide and zinc iodide were obtained by mixing solutions of the starting substances in a perfectly mixed reactor according to Table 4.

[0077] Mixing was carried out while maintaining the molar ratio of the sum of the specified salts or salts included in the first solution to the sum of the specified salts or salts included in the second solution equal to 0.5-1.3:2.

[0078] Each of the resulting solutions was sent for evaporation, where the density of the solution was brought to 1400 kg / m3 3 , and then cooled to 25°C, causing by-product salts such as sodium chloride or potassium chloride to precipitate from the solution. The cooled solution was filtered to separate the precipitated crystals. The resulting filtrate was a heavy liquid suitable for well killing. Table 4 - Production of target substances in the solution.

[0079] Example 2.

[0080] Solutions containing the target substances in the form of calcium bromide, barium bromide, magnesium bromide, strontium bromide, zinc bromide, calcium iodide, barium iodide, magnesium iodide, strontium iodide and zinc iodide were obtained by mixing solutions of the starting substances in a perfectly mixed reactor according to Table 4.

[0081] Mixing was carried out while maintaining the molar ratio of the sum of the specified salts or salts included in the first solution to the sum of the specified salts or salts included in the second solution equal to 0.5-1.3:2.

[0082] Each of the resulting solutions was sent for evaporation, where the density of the solution was brought to 2650 kg / m3 3 , and then cooled to a temperature of 25 °C, during which time by-product salts such as sodium chloride or potassium chloride precipitated from the solution, the cooled solution was sent for filtration to separate from the precipitated crystals, the resulting filtrate was a heavy liquid suitable for killing wells.

[0083] Example 3.

[0084] The well killing fluid was obtained in a manner similar to Example 1, with the difference that the solution was cooled to a temperature of 10 °C after evaporation.

[0085] Example 4.

[0086] The well killing fluid was obtained in a manner similar to Example 2, with the difference that the solution was cooled to a temperature of 15 °C after evaporation.

[0087] Example 5. The well killing fluid was obtained in a manner similar to Example 1, with the difference that the mixed solutions had a temperature of 40°C, which ensured rapid reaction and evaporation of the resulting solution.

[0088] Example 6.

[0089] The production of well killing fluid was carried out similarly to Example 1, with the difference that the mixed solutions had a salt concentration of 909.1 g / l and a temperature of 120°C, which ensured the rapid reaction and evaporation of the resulting solution.

[0090] Example 7.

[0091] Well-killing fluid was prepared similarly to Example 1, except that the mixed solutions had a salt concentration of 967.0 g / L and a temperature of 120°C, which ensured rapid reaction. After the reaction, the solution was filtered and then evaporated.

[0092] Example 8.

[0093] The production of well killing fluid was carried out in a manner similar to Example 1, with the difference that the cake separated as a result of filtration in the form of sodium chloride or potassium chloride crystals was dissolved in water and injected into the formation.

[0094] Example 9.

[0095] The production of well killing fluid was carried out in a manner similar to Example 1, with the difference that the cake separated as a result of filtration in the form of sodium chloride or potassium chloride crystals was washed with water and dried to obtain a by-product.

[0096] Example 10.

[0097] The well killing fluid was obtained in a manner similar to Example 9, with the difference that the water after washing the crystals was sent for evaporation together with the solution obtained as a result of mixing, which allowed part of the target salt to be returned to the final solution.

[0098] Example 11. A well-killing fluid was produced similarly to Example 1, except that after cooling the evaporated solution and before filtering it, the solid phase (precipitated crystals) was separated by settling and centrifugation, reducing the frequency of filter backwashing. The separated solid phase was washed with water and dried to obtain a byproduct.

[0099] Example 12.

[0100] The well killing fluid was obtained in a manner similar to Example 1, with the difference that the obtained heavy well killing fluid was evaporated to obtain a dry product, after which it was transported to the place of use and by dissolving the dry product in water, heavy well killing fluid was again obtained, which was used for its intended purpose.

[0101] Example 13.

[0102] The production of well killing fluid was carried out in a manner similar to Example 1, with the difference that the resulting heavy fluid was mixed with slag, and then the resulting solution was used as a heavy well killing fluid.

[0103] Example 14.

[0104] The well killing fluid was obtained in a manner similar to Example 1, with the difference that the first solution simultaneously included calcium chloride, magnesium chloride, barium chloride, strontium chloride, and zinc chloride, while the second solution simultaneously included sodium iodide, potassium iodide, sodium bromide, and potassium bromide, resulting in the solution after the reaction including calcium bromide, barium bromide, magnesium bromide, strontium bromide, zinc bromide, calcium iodide, barium iodide, magnesium iodide, strontium iodide, and zinc iodide, and crystals of potassium chloride and sodium chloride precipitated during the evaporation process.

[0105] Example 15.

[0106] A 44% zinc chloride solution (30.1 g) and a 65% sodium iodide dihydrate solution (82.15 g) were prepared from the dry reagents. They were then mixed in a 250 ml flask equipped with a reflux condenser by pouring the sodium iodide solution into the zinc chloride suspension, after which the resulting mixture was boiled for 8 hours. The color of the solution changed from transparent to deep orange. After the reaction time, the solution was cooled to 25 °C and filtered. The density of the resulting solution was 1553.2 kg / m3. 3 .

[0107] Example 16.

[0108] A 44% zinc chloride solution (30.1 g) and a 65% sodium iodide dihydrate solution (82.15 g) were prepared from the dry reagents. They were then mixed in a 250 ml flask equipped with a reflux condenser by pouring the sodium iodide solution into the zinc chloride suspension, after which the resulting mixture was boiled for 8 hours. The color of the solution changed from transparent to deep orange. After the reaction time, the solution was evaporated by 44%, cooled to 20 °C and filtered; the color of the resulting solution was straw-yellow. The solution thus obtained had a density of 2650 kg / m3. 3 .

[0109] Example 17.

[0110] A 41% calcium chloride solution (16.69 g), a 44% zinc chloride solution (20.5 g), and a 47% sodium bromide solution (61.91 g) were prepared from the dry reagents. The resulting solutions were then mixed by alternately adding the calcium chloride solution and then sodium bromide to the zinc chloride suspension. The resulting mixture was stirred on a magnetic stirrer for 15 min, after which the mixture was evaporated by 32%, cooled to 25 °C, and filtered. The filtrate density was 1727.6 kg / m3. 3 .

[0111] Example 18.

[0112] A 41% calcium chloride solution (16.69 g), a 44% zinc chloride solution (20.5 g), and a 65% sodium iodide dihydrate solution (111.87 g) were prepared from the dry reagents. The resulting solutions were then mixed in a 250 ml flask equipped with a reflux condenser by alternately adding the calcium chloride solution and then sodium iodide to the zinc chloride suspension. The resulting mixture was heated and boiled for 6-8 hours. The color of the solution changed from transparent to yellow. After the reaction time, the solution was evaporated by 35%, cooled to 20 °C and filtered; the color of the resulting solution was straw-yellow. The solution obtained in this way had a density of 2309.4 kg / m 3 .

[0113] Example 19.

[0114] A 43.5% zinc chloride solution (10.8 g), 47% sodium bromide solution (61.14 g), and 43% calcium chloride solution (25.3 g) were prepared from the dry reagents. The resulting solutions were then mixed in a 250 ml flask equipped with a reflux condenser by alternately adding the calcium chloride solution and then sodium bromide to the zinc chloride suspension. The resulting mixture was stirred on a magnetic stirrer for 15 min, after which the mixture was evaporated by 40%, cooled to 20 °C, and filtered. The filtrate density was 1857.0 kg / m3. 3 .

[0115] Example 20.

[0116] A 43.5% zinc chloride solution (20.0 g), 47% sodium bromide solution (40.3 g), and 40% calcium chloride solution (5.4 g) were prepared from dry reagents. The resulting solutions were then mixed in a 250 ml flask equipped with a reflux condenser by alternately adding the calcium chloride solution and then sodium bromide to the zinc chloride suspension. The resulting mixture was stirred on a magnetic stirrer for 15 min, after which the mixture was evaporated by 40%, cooled, and filtered. The filtrate density was 1928.0 kg / m3. 3 .

[0117] Example 21.

[0118] A 44.5% zinc chloride solution (20.9 g), 47% sodium bromide solution (60.65 g), and 42% calcium chloride solution (17.3 g) were prepared from dry reagents. The resulting solutions were then mixed in a 250 ml flask equipped with a reflux condenser by alternately adding the calcium chloride solution and then sodium bromide to the zinc chloride suspension. The resulting mixture was stirred on a magnetic stirrer for 15 min, after which the mixture was evaporated by 44%, cooled to 20 °C, and filtered. The filtrate density was 2019.0 kg / m3. 3 .

[0119] Example 22.

[0120] A 47% zinc chloride solution (114.48 g) and a 46.5% sodium bromide solution (156.18 g) were prepared from the dry reagents and then mixed in a 500 ml flask equipped with a reflux condenser by pouring the sodium bromide solution into the zinc chloride suspension. The resulting mixture was stirred on a magnetic stirrer for 15 min, after which the mixture was evaporated by 42%, cooled to 20 °C and filtered; the filtrate density was 1986.0 kg / m3. 3 Example 23.

[0121] A 49% zinc chloride solution (124.88 g) and a 46.5% sodium bromide solution (156.18 g) were prepared from the dry reagents. They were then mixed in a 500 ml flask equipped with a reflux condenser by pouring the sodium bromide solution into the zinc chloride suspension. The resulting mixture was stirred on a magnetic stirrer for 15 min, after which the mixture was evaporated by 37%, cooled to 20 °C and filtered. The filtrate density was 1997.0 kg / m3. 3 .

Claims

CLAUSES OF THE INVENTION 1. A method for producing a heavy well killing fluid comprising: mixing a first solution comprising one or more salts selected from magnesium chloride, barium chloride, strontium chloride, zinc chloride, with a second solution comprising one or more salts selected from sodium iodide, potassium iodide, sodium bromide, potassium bromide, while maintaining a molar ratio of the sum of said salts or salts included in the first solution to the sum of said salts or salts included in the second solution equal to 0.5-1.3:2; evaporating the solution obtained as a result of mixing to a density of 1400-2650 kg / m3 3; cooling the evaporated solution to a temperature below 25°C to form crystals of sodium chloride or potassium chloride, or a mixture thereof; filtering the evaporated solution to obtain a filtrate in the form of a heavy well killing fluid containing at least one of the following salts: magnesium iodide, magnesium bromide, barium iodide, barium bromide, strontium iodide, strontium bromide, zinc iodide, zinc bromide, or any combination thereof.

2. A method for producing a heavy well killing fluid, comprising: mixing a first solution containing calcium chloride with a second solution containing one or more salts selected from sodium iodide, potassium iodide, potassium bromide, while maintaining a molar ratio of calcium chloride in the first solution to the sum of the said salts or salts included in the second solution equal to 0.5-1.3:2; evaporating the solution obtained as a result of mixing to a density of 1400-2650 kg / m3 3; cooling the evaporated solution to a temperature below 25 °C to form crystals of sodium chloride or potassium chloride, or a mixture thereof; filtering the evaporated solution to obtain a filtrate in the form of a heavy well killing fluid containing calcium bromide or calcium iodide, or a mixture thereof.

3. A method for producing a heavy well killing fluid, comprising: mixing a first solution comprising calcium chloride and one or more salts selected from magnesium chloride, barium chloride, strontium chloride, zinc chloride, with a second solution comprising one or more salts selected from sodium iodide, potassium iodide, potassium bromide, while maintaining the molar ratio of the sum of the said salts included in the first solution to the sum of the said salts or salts included in the second solution equal to 0.5- 1.3:2; evaporation of the resulting solution to a density of 1400-2650 kg / m3 3; cooling the evaporated solution to a temperature below 25°C to form crystals of sodium chloride or potassium chloride or a mixture thereof; filtering the evaporated solution to obtain a filtrate in the form of a heavy well killing fluid containing calcium bromide or calcium iodide or a mixture thereof, as well as one of the following salts: magnesium iodide, magnesium bromide, barium iodide, barium bromide, strontium iodide, strontium bromide, zinc iodide, zinc bromide or any combination thereof.

4. The method according to any of paragraphs 1-3, characterized in that the mixed solutions have a temperature of 40 to 120°C, and before evaporation, the solution obtained as a result of their mixing is filtered.

5. The method according to any one of paragraphs 1-3, characterized in that the cake separated as a result of filtration in the form of crystals of sodium chloride or potassium chloride, or a mixture thereof, is washed with water and dried, and the water after washing the crystals is sent for evaporation together with the solution obtained as a result of mixing.

6. The method according to any of paragraphs 1-3, characterized in that after cooling the evaporated solution and before filtering it, the solid phase in the form of precipitated crystals is separated by centrifugation or settling.

7. A heavy well killing fluid, the composition of which includes a brine solution containing at least one of the salts from the group: magnesium iodide, magnesium bromide, barium iodide, barium bromide, strontium iodide, strontium bromide, zinc iodide, zinc bromide or any combination thereof; or a brine solution containing calcium bromide or calcium iodide or a mixture thereof; or a brine solution containing calcium bromide or calcium iodide or a mixture thereof, as well as one of the salts from the group: magnesium iodide, magnesium bromide, barium iodide, barium bromide, strontium iodide, strontium bromide, zinc iodide or any combination thereof, obtained by the method according to any of claims 1 to 6.

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