Method for producing an acrylic acid (CO)polymer

Abstract

The invention relates to a method for producing an acrylic acid (co)polymer in an aqueous medium, which comprises supplying water, acrylic acid, and optionally one or two comonomers to produce a reaction mass, neutralizing the mixture using a solution of a basic compound, then adding an initiator to the mixture, heating the mixture to 70-95°С under stirring, optionally supplying initiator to the reaction mass an additional one or two times, and, once the reaction is complete, drying the reaction mass until a dry product is obtained. This method makes it possible to produce a fully neutralized acrylic acid (co)polymer which exhibits high salt tolerance when used as a drilling fluid additive and reduces drilling fluid filtration in saltwater and freshwater formations.

Description

[0001] METHOD FOR PRODUCING (CO) POLYMER OF ACRYLIC ACID

[0002] Field of technology to which the invention relates The present invention relates to a method for producing

[0003] (co)polymer of acrylic acid, which can be used as an additive to reduce filtration of drilling fluids.

[0004] State of the art

[0005] Acrylic acid (AA) polymer products such as homo- and copolymers are used in a wide range of applications from pharmaceuticals to oil production due to the wide range of properties these products possess.

[0006] The variability of the properties of AC polymers is primarily due to their molecular weight, which can vary from 1,000 to 5,000,000 g / mol. For example, low-molecular-weight products with a molecular weight of up to 10,000 g / mol can be used as scale inhibitors in water supply systems, as they are capable of binding to hardness salts in water. Medium-molecular-weight products with a molecular weight of, for example, 100,000 g / mol can be used as viscosity reducers for various media. High-molecular-weight (co)polymers with a molecular weight of 1,000,000 g / mol can be used as water absorbents in medicine, personal hygiene products, etc.

[0007] In the oil production process, acrylic polymers can be used as components that change the viscosity of drilling fluids, as well as increase the temperature and salt resistance of the solution.

[0008] Acrylic polymers are also important components in oil production, where they are used as additives that improve the properties of drilling fluids. These polymers are used as components that enhance the temperature and salinity resistance of drilling fluids, as thinners and thickeners, and as filtration rate reducers. Numerous additives are currently known that can reduce filtration rate, such as modified starches or cellulose, and their derivatives. Filtration rate decreases with the use of such additives due to increased drilling fluid viscosity, which in turn significantly limits their applicability to water-flooded formations.

[0009] The uniqueness of the use of acrylic polymers in drilling fluids lies in the polymer's ability to create a flexible and dense filtration film on the formation walls, preventing the solution or "filtrate" from entering the formation, thereby reducing its loss and cutting down on water consumption, but without increasing the viscosity of the solution unless necessary.

[0010] The closest to the present solution is the invention known from EA 044955, which discloses a water-soluble polymer of acrylamide or a copolymer of acrylamide and acrylic acid, which is characterized by an average molecular weight of at least 0.5 million daltons (500,000 g / mol) and which can be used in the oil and gas industry, water purification, sludge dewatering, and the mining industry.

[0011] The main disadvantage of this known invention is that the polymer is presented in the form of an aqueous dispersion, which makes it inconvenient to use, for example, for drilling fluids due to the need to transport and load a large volume of the component at its low concentration.

[0012] The second important disadvantage is the need to add to the aqueous dispersion a mixture of at least one sulfuric acid salt and at least one phosphoric acid salt in strictly defined proportions, since only in the presence of this additive does the dispersion acquire its universal properties.

[0013] Disclosure of invention

[0014] The present invention is based on the objective of proposing a method for producing a (co)polymer of acrylic acid which can be used as an additive that reduces the filtration of drilling fluids.

[0015] The technical result of the present invention consists in reducing the filtration of drilling mud in salty and freshwater formations and obtaining a (co)polymer of acrylic acid that has greater salt resistance.

[0016] Detailed description of the invention

[0017] Various embodiments of the invention are given below.

[0018] The object of the invention is a method for producing a (co)polymer of acrylic acid in an aqueous medium, characterized in that water, acrylic acid and, optionally, one or two comonomers are loaded to obtain a reaction mass. The initial concentration of monomers in the aqueous solution is 15-25 mass % . The mixture is neutralized with a solution of the basic compound at a rate that ensures a temperature increase of no more than 45 ° C to a pH of 7-11, preferably to a pH of 8-10, more preferably to a pH of 9-10. After this, an initiator is added to the mixture in an amount of from 0.07 to 0.25 mass % of the total weight of the monomers, preferably from 0.07 to 0.1 mass % of the total weight of the monomers, more preferably in an amount of 0.07 mass % of the total weight of the monomers. The mixture is heated with stirring to 70-95°C, preferably 75-90°C, more preferably 80-85°C, after which self-heating to 90-95°C occurs. The initiator is additionally loaded into the reaction mass twice in an amount of 0.05-0.15 mass.% of the total mass of monomers, with 0.06-0.08 mass % of the total mass of monomers being preferably added first, and 0.13-0.15 mass % of the total mass of monomers being added a second time.

[0019] After completion of the reaction, the polymer solution is dried to obtain a dry product.

[0020] The inventors unexpectedly discovered that neutralization of the reaction mass before the polymerization process results in the production of a fully neutralized (co)polymer of acrylic acid, which has greater salt resistance when used as an additive in drilling fluids.

[0021] Acrylic acid can be added in partially neutralized form.

[0022] Aqueous solutions of the main compound with a concentration of 30-50% by weight are preferably used as the main compound. This range is optimal in terms of minimizing the formation of by-products, since adding a smaller amount of the main compound will increase the amount of water in the final product.

[0023] Sodium or potassium hydroxides, ammonia or amines, preferably triethanolamine, are used as the main compound.

[0024] The loading of water, acrylic acid, and optionally one or two comonomers can be carried out sequentially or simultaneously.

[0025] Any initiator used for the polymerization of acrylic monomers can be used as an initiator, for example, inorganic and organic peroxide compounds such as sodium persulfate, potassium persulfate, ammonium persulfate, hydrogen peroxide, di-tertiary butyl peroxide, cumene hydroperoxide, benzoyl peroxide, sodium thiosulfate, sodium hydrosulfite, etc.

[0026] In a preferred embodiment, sodium, potassium, or ammonium persulfates are used as the initiator. In a more preferred embodiment, sodium persulfate is used.

[0027] Before each stage of additional loading of the initiator, the mixture is optionally kept under stirring for 0.1-5 h, preferably for at least 1 h.

[0028] The method proposed in the invention is carried out in a periodic or semi-periodic mode. The process is carried out at atmospheric pressure, but it can be carried out at reduced or increased pressure.

[0029] According to the invention, the reaction mass is stirred for 1-10 hours, preferably 1-5 hours.

[0030] The drying stage can produce various product forms depending on the required parameters. The product can be converted into powder, granules, fibers, etc.

[0031] Drying can be carried out by various methods, but is preferably carried out by spray drying, roller drying or paddle drying.

[0032] Another object of the invention is a (co)polymer of acrylic acid, which is obtained by the method described above.

[0033] The (co)polymer of acrylic acid may be a homopolymer of sodium acrylate.

[0034] The (co)polymer proposed in the invention may be a copolymer of acrylic acid with a monomer that is selected from the group of α,β-ethylenically unsaturated comonomers suitable for radical polymerization.

[0035] The corresponding comonomers are selected from the group of amides of α,β-ethylenically unsaturated monocarboxylic and dicarboxylic acids with amino alcohols with 2-30 carbon atoms having a primary or secondary amino group, primary amides of α,β-ethylenically unsaturated monocarboxylic acids and their N-alkyl and N,N-dialkyl derivatives, N-vinyl lactams, N-vinyl amide compounds with an open chain, esters of allyl alcohol with monocarboxylic acids with 1-30 carbon atoms, esters of α,β-ethylenically unsaturated monocarboxylic and dicarboxylic acids with amino alcohols, amides of α,β-ethylenically unsaturated monocarboxylic and dicarboxylic acids with diamines having at least one primary or secondary amino group, N,N-diallylamines, N, N-diallyl-N-alkylamines, nitrogen heterocycles substituted with vinyl and allyl, vinyl ethers, monoolefins with 2-8 carbon atoms, non-aromatic hydrocarbons with at least two conjugated double bonds, polyether (meth)acrylates,monomers with urea groups and their mixtures.,

[0036] Examples of suitable primary amides of a, p-ethylenically unsaturated monocarboxylic acids and their N-alkyl and N, N-dialkyl derivatives include acrylic acid amide, methacrylic acid amide, methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-(n-butyl) (meth) acrylamide, N-(tert-butyl) (meth) acrylamide, N-(n-octyl) (meth) acrylamide, N-(1, 1, 3, 3-tetramethylbutyl) (meth) acrylamide, N-ethylhexyl (meth) acrylamide, N-(n-nonyl) (meth) acrylamide, N-(n-decyl) (meth) acrylamide, N-(n-undecyl) (meth) acrylamide, N-tridecyl-(meth)acrylamide, N-myristyl (meth)acrylamide, N-pentadecyl (meth)-acrylamide, N-palmityl (meth)acrylamide, N-heptadecyl (meth)acrylamide, N-nonadecyl (meth)acrylamide, N-arachininyl (meth)acrylamide, N-behenyl (meth)acrylamide, N-lignoceryl (meth)acrylamide, N-cerotinyl (meth)acrylamide, N-melissinyl (meth)acrylamide, N-palmitoleinyl (meth)acrylamide, N-oleyl (meth)acrylamide, N-linolyl (meth)acrylamide,N-linolenyl (meth) acrylamide, N-stearyl (meth) acrylamide, N-lauryl (meth) acrylamide, N,N-dimethyl (meth) acrylamide, N,N-diethyl (meth) acrylamide,

[0037] morpholinyl(meth)acrylamide.

[0038] The comonomer according to the invention is preferably acrylamide.

[0039] The comonomer content does not exceed 30 mass % based on the total monomer content.

[0040] The (co)polymer has a weight average molecular weight of 100,000 to 900,000 g / mol, preferably 200,000 to 800,000 g / mol, particularly preferably 300,000 to 700,000 g / mol, most preferably 300,000 to 500,000 g / mol.

[0041] Obtaining a polymer with a molecular weight greater than 900,000 g / mol will lead to an increase in the viscosity of its solution, which may become a technological limitation for isolating the polymer in dry form during the drying process, and will also lead to a decrease in the solubility of the product in water, which will complicate its use in drilling fluids due to uneven distribution.

[0042] Molecular weight values ​​below 100,000 will increase the filtration of drilling fluid into the formation.

[0043] The (co)polymer proposed in the invention has a fractional ratio from 2.0 to 6.5.

[0044] Acrylic polymers are added to drilling fluids as a component that reduces their filtration into the formation, in an amount from 0.1 to 1.0 mass.%.

[0045] Below, the present invention is explained in more detail using examples, which merely illustrate the invention but do not limit its scope.

[0046] Example 1 (according to the invention): Synthesis of an acrylic acid homopolymer

[0047] The synthesis is carried out in a 2000 ml glass flask. 750 g of distilled water and 250 g of acrylic acid are loaded into it, and then, with stirring, a 46% aqueous solution of sodium hydroxide is added at such a rate that the temperature does not exceed 60 °C. The supply of sodium hydroxide is stopped when the pH of the medium reaches 9. After this, a solution of 0.179 g of sodium persulfate in the form of a 35% aqueous solution is added to the flask. The mixture is heated to 80 °C with stirring, after which self-heating to 92-95 °C occurs. After 1 hour, an additional 0.179 g of sodium persulfate in the form of a 35% aqueous solution is added to the reaction mixture. After this, the reaction mixture is kept for another 1 hour at a temperature of 75-90 °C. Next, 0.357 g of sodium persulfate in the form of a 35% aqueous solution is added to the reaction mixture. After this, the reaction mixture is maintained for another 1 hour at a temperature of 75-90°C.The resulting polymer solution with a dry residue of 25% by weight is dried in a serpentine dryer. In this way, 346 g of cream-colored powder with a residual water content of 4.9% by weight and a residual acrylic acid content of 0.06% by weight are obtained.

[0048] Example 2 (according to the invention): Synthesis of acrylic acid copolymer

[0049] The synthesis is carried out in a 2000 ml glass flask. 921.9 g of distilled water, 120.0 g of acrylic acid and 51.4 g of acrylamide are loaded into it, and then, with stirring, a 46% aqueous solution of sodium hydroxide is added at such a rate that the temperature does not exceed 60 °C. The supply of sodium hydroxide is stopped when the pH of the medium reaches 9. After this, a solution of 0.122 g of sodium persulfate in the form of a 35% aqueous solution is added to the flask. The mixture is heated to 83 °C with stirring, after which self-heating to 92-95 °C occurs. After 1 hour, an additional 0.122 g of sodium persulfate in the form of a 35% aqueous solution is added to the reaction mixture. After this, the reaction mass is kept for another 1 hour at a temperature of 75-90°C.

[0050] Next, 0.122 g of sodium persulfate in the form of a 35% aqueous solution is added to the reaction mass. After this, the reaction mass is kept for another 1 hour at a temperature of 75-90 °C. The resulting polymer solution with a dry residue of 17 wt. % is dried in a coil dryer. In this way, 215 g of yellowish powder with a residual water content of 2.8 wt. % and a residual acrylic acid and acrylamide content of 0.08 and 0.02 wt. %, respectively, are obtained.

[0051] Example 3 (according to the invention): Synthesis of acrylic acid copolymer

[0052] The synthesis is carried out in a 2000 ml glass flask. 768.2 g of distilled water, 100.0 g of acrylic acid and 42.9 g of acrylamide are loaded into it, and then, with stirring, a 46% aqueous solution of sodium hydroxide is added at such a rate that the temperature does not exceed 60 °C. The supply of sodium hydroxide is stopped when the pH of the medium reaches 10. After this, a solution of 0.102 g of sodium persulfate in the form of a 35% aqueous solution is added to the flask. The mixture is heated to 82 °C with stirring, after which self-heating to 92-95 °C occurs. After 1 hour, an additional 0.102 g of sodium persulfate in the form of a 35% aqueous solution is added to the reaction mixture. After this, the reaction mass is kept for another 1 hour at a temperature of 75-90°C.

[0053] Next, 0.204 g of sodium persulfate in the form of a 35% aqueous solution is added to the reaction mass. After this, the reaction mass is kept for another 1 hour at a temperature of 75-90 °C. The resulting polymer solution with a dry residue of 17 wt. % is dried in a coil dryer. In this way, 179.7 g of yellowish powder with a residual water content of 3.1 wt. % and a residual acrylic acid and acrylamide content of 0.03 and 0.01 wt. %, respectively, are obtained.

[0054] Example 4 (according to the invention): Synthesis of an acrylic acid homopolymer

[0055] The synthesis is carried out in a 2000 ml glass flask. 480 g of distilled water and 120 g of acrylic acid are added to it, and then, with stirring, a 46% aqueous solution of sodium hydroxide is added at such a rate that the temperature does not exceed 60 °C. The supply of sodium hydroxide is stopped when the pH of the medium reaches 10. After this, a solution of 0.086 g of sodium persulfate in the form of a 35% aqueous solution is added to the flask. The mixture is heated to 85 °C with stirring, after which self-heating to 95-98 °C occurs. After 1 hour, an additional 0.086 g of sodium persulfate in the form of a 35% aqueous solution is added to the reaction mixture. After this, the reaction mixture is kept for another 1 hour at a temperature of 75-90 °C. Next, an additional 0.171 g of sodium persulfate in the form of a 35% aqueous solution is added to the reaction mixture. After this, the reaction mixture is maintained for another 1 hour at a temperature of 75-90°C.The resulting polymer solution with a dry residue of 21% by weight is dried in a coil dryer. In this way, 164 g of cream-colored powder with a residual water content of 3.4% by weight is obtained.

[0056] Example 5 (according to the invention): Synthesis of acrylic acid copolymer

[0057] The synthesis is carried out in a 2000 ml glass flask. 768.2 g of distilled water, 100.0 g of acrylic acid and 42.9 g of acrylamide are loaded into it, and then, with stirring, a 46% aqueous solution of sodium hydroxide is added at such a rate that the temperature does not exceed 60 °C. The supply of sodium hydroxide is stopped when the pH of the medium reaches 10. After this, a solution of 0.146 g of sodium persulfate in the form of a 35% aqueous solution is added to the flask. The mixture is heated to 80 °C with stirring, after which self-heating to 96-99 °C occurs. After 1 hour, an additional 0.146 g of sodium persulfate in the form of a 35% aqueous solution is added to the reaction mixture. After this, the reaction mass is kept for another 1 hour at a temperature of 75-90°C.

[0058] Next, 0.292 g of sodium persulfate in the form of a 35% aqueous solution is added to the reaction mass. After this, the reaction mass is kept for another 1 hour at a temperature of 75-90 °C. The resulting polymer solution with a dry residue of 17 wt. % is dried in a coil dryer. In this way, 180.2 g of yellowish powder with a residual water content of 3.3 wt. % and a residual acrylic acid and acrylamide content of 0.04 and 0.02 wt. %, respectively, are obtained.

[0059] Example 6 (according to the invention): Synthesis of acrylic acid copolymer

[0060] The synthesis is carried out in a 2000 ml glass flask. 768.2 g of distilled water, 100.0 g of acrylic acid and 42.9 g of acrylamide are loaded into it, and then, with stirring, a 46% aqueous solution of sodium hydroxide is added at such a rate that the temperature does not exceed 60 °C. The supply of sodium hydroxide is stopped when the pH of the medium reaches 10. After this, a solution of 0.073 g of sodium persulfate in the form of a 35% aqueous solution is added to the flask. The mixture is heated to 84 °C with stirring, after which self-heating to 92-94 °C occurs. After 1 hour, an additional 0.073 g of sodium persulfate in the form of a 35% aqueous solution is added to the reaction mixture. After this, the reaction mass is kept for another 1 hour at a temperature of 75-90°C.

[0061] Next, 0.146 g of sodium persulfate in the form of a 35% aqueous solution is added to the reaction mixture. After this, the reaction mixture is maintained for another 1 hour at a temperature of 75-90 °C. The resulting polymer solution with a dry residue of 17 wt.% is dried in a coil dryer. In this way, 185.5 g of yellowish powder with a residual water content of 6.1 wt.% is obtained.

[0062] Example 7 (according to the invention): Synthesis of acrylic acid copolymer

[0063] The synthesis is carried out in a 500 ml glass flask. 115.2 g of distilled water, 15.0 g of acrylic acid, and 6.4 g of acrylamide are added. A 46% aqueous solution of sodium hydroxide is then added with stirring at a rate such that the temperature does not exceed 60 °C. The sodium hydroxide supply is stopped when the pH of the medium reaches 4. A solution of 0.015 g of sodium persulfate in the form of a 35% aqueous solution is then added to the flask. The mixture is heated to 81 °C with stirring. The reaction mixture boils.

[0064] Example 8 (according to the invention): Synthesis of acrylic acid copolymer

[0065] The synthesis is carried out in a 500 ml glass flask. 115.2 g of distilled water, 15.0 g of acrylic acid and 6.4 g of acrylamide are loaded into it, and then, with stirring, a 46% aqueous solution of sodium hydroxide is added at such a rate that the temperature does not exceed 60 °C. The supply of sodium hydroxide is stopped when the pH of the medium reaches 12. After this, a solution of 0.015 g of sodium persulfate in the form of a 35% aqueous solution is added to the flask. The mixture is heated to 85 °C with stirring. No exothermic effect is observed. After 1 hour, an additional 0.015 g of sodium persulfate in the form of a 35% aqueous solution is added to the reaction mixture. After this, the reaction mixture is kept for another 1 hour at a temperature of 75-90 °C. Next, an additional 0.030 g of sodium persulfate in the form of a 35% aqueous solution is added to the reaction mixture. After this, the reaction mixture is maintained for another 1 hour at a temperature of 75-90°C.In this way, a polymer solution with an average molecular weight of 84,000 g / mol and a residual monomer content of 30.5 mass % is obtained.

[0066] Example 9 (according to the invention): Synthesis of acrylic acid copolymer

[0067] The synthesis is carried out in a 500 ml glass flask. 192.9 g of distilled water, 15.0 g of acrylic acid and 6.4 g of acrylamide are loaded into it, and then, with stirring, a 46% aqueous solution of sodium hydroxide is added at such a rate that the temperature does not exceed 60 °C. The supply of sodium hydroxide is stopped when the pH of the medium reaches 10. After this, a solution of 0.015 g of sodium persulfate in the form of a 35% aqueous solution is added to the flask. The mixture is heated to 85 °C with stirring. No exothermic effect is observed. After 1 hour, an additional 0.015 g of sodium persulfate in the form of a 35% aqueous solution is added to the reaction mixture. After this, the reaction mixture is kept for another 1 hour at a temperature of 75-90 °C. Next, an additional 0.030 g of sodium persulfate in the form of a 35% aqueous solution is added to the reaction mixture. After this, the reaction mixture is maintained for another 1 hour at a temperature of 75-90°C.In this way, a polymer solution with an average molecular weight of 112,000 g / mol and a residual monomer content of 12.8 mass % is obtained.

[0068] Example 10 (according to the invention): Synthesis of an acrylic acid homopolymer

[0069] The synthesis is carried out in a 500 ml glass flask. 116.5 g of distilled water and 50 g of acrylic acid are added, and then, with stirring, a 46% aqueous solution of sodium hydroxide is added at a rate such that the temperature does not exceed 60 °C. The sodium hydroxide supply is stopped when the pH of the medium reaches 10. After this, a solution of 0.036 g of sodium persulfate in the form of a 35% aqueous solution is added to the flask. The mixture is heated to 85 °C with stirring. The reaction mixture boils.

[0070] Example 11 (according to the invention): Synthesis of an acrylic acid homopolymer

[0071] The synthesis is carried out in a 2000 ml glass flask. 480 g of distilled water and 160 g of acrylic acid are added to it, and then, with stirring, a 46% aqueous solution of sodium hydroxide is added at such a rate that the temperature does not exceed 60 °C. The supply of sodium hydroxide is stopped when the pH of the medium reaches 11. After this, a solution of 0.098 g of sodium persulfate in the form of a 35% aqueous solution is added to the flask. The mixture is heated to 83 °C with stirring, after which self-heating to 95-98 °C occurs. After 1 hour, an additional 0.098 g of sodium persulfate in the form of a 35% aqueous solution is added to the reaction mixture. After this, the reaction mixture is kept for another 1 hour at a temperature of 75-90 °C. Next, 0.196 g of sodium persulfate in the form of a 35% aqueous solution is added to the reaction mixture. After this, the reaction mixture is maintained for another 1 hour at a temperature of 75-90°C.The resulting polymer solution with a dry residue of 24.8% by weight is dried in a serpentine dryer. In this way, 223 g of cream-colored powder with a residual water content of 6.2% by weight is obtained.

[0072] Example 12 (according to the invention): Synthesis of acrylic acid copolymer

[0073] The synthesis is carried out in a 2000 ml glass flask. 809.5 g of distilled water, 100.0 g of acrylic acid and 42.9 g of acrylamide are loaded into it, and then, with stirring, a 46% aqueous solution of sodium hydroxide is added at such a rate that the temperature does not exceed 60 °C. The supply of sodium hydroxide is stopped when the pH of the medium reaches 8. After this, a solution of 0.073 g of sodium persulfate in the form of a 35% aqueous solution is added to the flask. The mixture is heated to 85 °C with stirring, after which self-heating to 92-94 °C occurs. After 1 hour, an additional 0.073 g of sodium persulfate in the form of a 35% aqueous solution is added to the reaction mixture. After this, the reaction mass is kept for another 1 hour at a temperature of 75-90°C.

[0074] Next, an additional 0.146 g of sodium persulfate in the form of a 35% aqueous solution is added to the reaction mixture. After this, the reaction mixture is maintained for another 1 hour at a temperature of 75-90 °C. The resulting polymer solution with a dry residue of 15 wt. % is dried in a coil dryer. In this way, 178.0 g of yellowish powder with a residual water content of 2.2 wt. % is obtained.

[0075] Determination of molecular weight characteristics of acrylic acid-based polymers by gel permeation chromatography. The method is applicable to polyacrylic acid with an average molecular weight from 2000 to 1,000,000 g / mol.

[0076] Materials, reagents and auxiliary equipment:

[0077] - distilled water;

[0078] - sodium chloride (NaCl); - a set of calibration standards of polyacrylic acid PSS Standards Kit in the molecular weight range from 2000 to 1,000,000 g / mol

[0079] Preparation of eluent

[0080] For the buffer solution, a 2.9 g sample of sodium chloride is dissolved in 1 liter of distilled water.

[0081] Parameters for instrument calibration and chromatographic analysis

[0082] PLaquagel-OH MIXED-M analytical column, 300 mm long, 7.5 mm internal diameter, 8 µm particle size

[0083] No. 0006541038-67 (if peaks broaden and results differ from previous ones, the column must be replaced).

[0084] Measurements are performed in an isocratic eluent feed mode with the following chromatograph operating parameters:

[0085] - solvent feed rate 1.0 ml / min;

[0086] - column thermostat temperature 35°C;

[0087] - refractometer cell temperature 40 °C;

[0088] - chromatography time 15 min;

[0089] - volume of injected sample 80 µl.

[0090] Construction of a calibration curve

[0091] PSS Standards Kit acid calibration standards are prepared at a concentration of 0.15-0.2 mg / mL, which corresponds to approximately 1 mg of standard per 6 mL of distilled water.

[0092] To construct a calibration curve, each of the diluted solutions is chromatographed at least twice.

[0093] Next, using the instrument software, a calibration dependence is plotted (to plot a calibration graph, you can use a 2nd or 3rd degree polynomial or a linear dependence, check the calibration using the SOKOLAN SR-10 reference sample (3000-3100) for low-molecular polyacrylates and the SP-101 reference (450000-520000) for high-molecular polyacrylates and copolymers, as well as by processing standard samples). Carrying out measurements

[0094] When taking measurements, the following operations are performed.

[0095] The chromatograph is turned on in accordance with its operating manual and brought into operating mode.

[0096] A sample of polyacrylic acid weighing approximately 10 mg is weighed on an electronic scale to the second decimal place and transferred to a conical flask to prepare a solution.

[0097] The sample must be collected with a clean instrument. Next, add 10 ml of distilled water to the flask using a dispenser, place it on a magnetic stirrer, and stir until the sample is completely dissolved (at least 15 minutes). Transfer the sample solution to the vial using a disposable syringe, simultaneously filtering it through a nylon filter with a 0.45 µm mesh size. Place the vial containing the sample in the instrument's autosampler.

[0098] For each sample, 2 samples are prepared for analysis.

[0099] A solvent, which is water (an “empty” vial), is placed in a separate vial and placed in the autosampler in front of the vials with the sample.

[0100] The peak intensities of samples, standards and references should be in the same range from 1500 to 3500.

[0101] The ratio of mass ranges is determined using a cumulative curve. Specific mass ranges are selected for comparison of samples. Thus, the high-molecular-weight fraction according to the invention is a fraction with a molecular weight of 100,000 g / mol, preferably from 100,000 to 1,000,000 g / mol, more preferably from 100,000 to 700,000 g / mol, and the low-molecular-weight fraction is a fraction with a molecular weight of less than 100,000 g / mol.

[0102] The analytical data of the products obtained in the above examples are presented in Table 1. Table 1: Analytical data of the products obtained in examples 1-12

[0103] Example Total pH Temperature Amount Average Fractional concentration of the initiator environment weight ratio of the initial concentration in the first molecular weight of the monomers, reaction, additive, mass

[0104] mass % ° C mass %

[0105] 1 25 9 80 0 , 07 410000 4 , 2 2 17 9 83 0 , 07 465000 4 , 5 3 25 10 82 0 , 07 442000 3 , 8 4 20 10 85 0 , 07 306000 3 , 5 5 25 10 80 0 , 10 393000 2 , 5 6 25 10 84 0 , 05 480000 6 , 5 7 25 4 81 0 , 07 - - 8 25 12 - 0 , 07 84000 - 9 10 10 - 0 , 07 112000 - 10 30 10 85 0 , 07 - - 11 25 11 83 0 , 06 362000 2 , 1

[0106]

[0107] 12 15 8 85 0 , 05 361000 2 , 0

[0108] Determination of the filtration properties of drilling fluids The filtration and rheological properties of drilling fluids were determined according to GOST 33213-2014 (ISO 10414-1: 2008) “Monitoring of drilling fluid parameters under field conditions”. The following clay solution was used in the study: water in the amount of 336 g, sodium bicarbonate in the amount of 1 g, clay powder PBMB in the amount of 14 g, calcium carbonate MK-10 in the amount of 40 g. The products from examples 1-6 were added to the clay solution in the amount of 0.2 wt.%.

[0109] Thermostating was carried out in a roller furnace at a temperature of 110 ° C for 16 hours. When measuring the filtration properties in a saline solution, a saturated solution of sodium chloride was used.

[0110] The obtained results are presented in Table 2. SP-101 and GEOSPAN P were used as comparison samples. Table 2: Results of determining the filtration capacity

[0111] s

[0112] Sample Filtration, cm

[0113] Before After thermostatting (T=11 - 0 °C) Fresh Solution Fresh Solution NaCl solution NaCl solution 7.5 30 7.5 30 7.5 30 7.5 30 min min min min min min min Base solution 9.7 19.0 9.0 18.3

[0114] Example 1 4 , 0 7 , 8 32 , 8 14 , 9 3 , 6 7 , 9 13 , 8 34 , 2 Example 2 3 , 8 7 , 9 7 , 4 13 , 8 3 , 1 7 , 8 13 , 2 31 , 8 Example 3 3 , 9 9 , 1 7 , 2 14 , 3 3 , 5 7 , 6 17 , 6 31 , 9 Example 4 3 , 3 7 , 4 33 , 0 43 , 5 3 , 2 7 , 6 14 , 0 22 , 0 Example 5 4 , 1 8 , 3 7 , 5 15 , 1 3 , 6 7 , 8 17 , 8 31 , 2 Example 6 3 , 1 7 , 1 6 , 9 13 , 7 3 , 0 7 , 9 16 , 8 25 , 6 Example 11 3 , 4 8 , 5 31 , 0 42 , 0 3 , 2 7 , 9 19 , 0 37 , 0 Example 12 3 , 2 7 , 6 6 , 9 13 , 7 3 , 6 7 , 5 17 , 1 30 , 9 SP- 101 4 , 0 8 , 1 7 , 5 15 , 2 3 , 7 8 , 0 18 , 0 32, 5

[0115]

[0116] GEOSPAN P 3, 9, 9, 8, 3, 8, 9, 6, 3, 6, 8, 3, 22, 6, 42, 8

[0117] From the data presented in Table 2 it follows that the samples obtained in Examples 1-6, 11 and 12 in fresh solutions work at the level of frequently used filtration reducers SP-101 and GEOSPAN P both before and after thermostatting.

[0118] However, under conditions of high mineralization and exposure to temperature, samples from examples 4 and 6 reduce filtration more effectively than comparison samples.

Claims

CLAUSES OF THE INVENTION 1. A method for producing a (co)polymer of acrylic acid in an aqueous medium, characterized in that water, acrylic acid and optionally one or two comonomers are loaded to obtain a reaction mass, the mixture is neutralized with a solution of the main compound, after which an initiator is added to the mixture, the mixture is heated to 70-95°C with stirring, optionally an initiator is additionally loaded into the reaction mass once or twice and upon completion of the reaction the reaction mass is dried to obtain a dry product.

2. The method according to paragraph 1, characterized in that its aqueous solutions with a concentration of 30 to 50 mass % are used as the main compound.

3. The method according to claim 1, characterized in that sodium or potassium hydroxides, ammonia or amines, preferably triethanolamine, are used as the main compound.

4. The method according to claim 1, characterized in that the neutralization stage is carried out at a temperature of 25 to 45 °C to a pH in the range of 7 to 11.

5. The method according to claim 1, characterized in that the loading of water, acrylic acid and optionally one or two comonomers is carried out sequentially or simultaneously.

6. The method according to claim 1, characterized in that inorganic or organic peroxide compounds are used as the initiator, preferably sodium persulfate, potassium persulfate, ammonium persulfate, hydrogen peroxide, di-tertiary butyl peroxide, cumene hydroperoxide, benzoyl peroxide, sodium thiosulfate, sodium hydrosulfite.

7. The method according to claim 1, characterized in that sodium, potassium or ammonium persulfates, preferably sodium persulfate, are used as the initiator.

8. The method according to claim 1, characterized in that the initiator is fed into the reaction mass in one, optionally two or three stages in an amount of no more than 0.25% of the total mass of monomers, while at the initial moment of time the initiator is added in an amount of 0.07 to 0.25 mass % of the total mass of monomers, which makes it possible to obtain a polymer.

9. The method according to paragraph 1, characterized in that before each stage of additional loading of the initiator, the mixture is kept under stirring for 0.1-5 hours.

10. The method according to claim 1, characterized in that after adding the initiator, the mixture is heated with stirring to 70-95°C, preferably 75-90°C, more preferably 80-85°C, after which self-heating to 90-95°C occurs.

11. The method according to claim 1, characterized in that acrylic acid is added in a partially neutralized form.

12. The method according to item 1, which is carried out in a periodic or semi-periodic mode.

13. The method according to claim 1, characterized in that the process is carried out at atmospheric pressure or at reduced or increased pressure.

14. The method according to claim 1, characterized in that the reaction mass is stirred for 1-10 hours, preferably 1-5 hours.

15. The method according to claim 1, characterized in that at the drying stage it is possible to obtain various forms of the product, preferably powder, granules or fibers.

16. The method according to claim 1, characterized in that drying is possible using various methods, and preferably spray drying, roller drying, or drying in paddle dryers is carried out. 17 . (Co) polymer of acrylic acid obtained by the method according to paragraph 1 .

18. The (co)polymer of claim 17, which is a homopolymer of sodium acrylate.

19. (Co)polymer according to claim 17, which is a copolymer of acrylic acid with a monomer selected from the group of α,β-ethylenically unsaturated comonomers suitable for radical polymerization.

20. (Co)polymer according to claim 17, which is a copolymer of acrylic acid with a monomer selected from the group of amides of α,β-ethylenically unsaturated monocarboxylic and dicarboxylic acids with amino alcohols with 2-30 carbon atoms having a primary or secondary amino group, primary amides of α,β-ethylenically unsaturated monocarboxylic acids and their N-alkyl and N,N-dialkyl derivatives, N-vinyl lactams, open-chain N-vinyl amide compounds, esters of allyl alcohol with monocarboxylic acids with 1-30 carbon atoms, esters of α,β-ethylenically unsaturated monocarboxylic and dicarboxylic acids with amino alcohols, amides of α,β-ethylenically unsaturated monocarboxylic and dicarboxylic acids with diamines having at least one primary or secondary amino group, N,N-diallylamines, N,N-diallyl-N-alkylamines, nitrogen heterocycles substituted with vinyl and allyl, vinyl ethers, monoolefins with 2-8 carbon atoms,non-aromatic hydrocarbons with at least two conjugated double bonds, polyether (meth) acrylates, monomers with urea groups and mixtures thereof., 21. The (co)polymer of claim 17, which is a copolymer of acrylic acid with a monomer selected from the group of primary amides of α,β-ethylenically unsaturated monocarboxylic acids and their N-alkyl and N,N-dialkyl derivatives, which are acrylic acid amide, methacrylic acid amide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-(n-butyl) (meth) acrylamide, N-(tert-butyl) (meth) acrylamide, N-(n-octyl) (meth) acrylamide, N-(1,1,3,3-tetramethylbutyl) (meth) acrylamide, N-ethylhexyl (meth) acrylamide, N-(n-nonyl) (meth) acrylamide, N- (n-decyl) (meth) acrylamide, N-(n-undecyl) (meth) acrylamide, N-tridecyl (meth) acrylamide, N-myristyl (meth) acrylamide, N-pentadecyl (meth) acrylamide, N-palmityl (meth) acrylamide, N-heptadecyl (meth) acrylamide, N-nonadecyl (meth) acrylamide, N-arachininyl (meth) acrylamide, N-behenyl (meth) acrylamide, N-lignoceryl (meth) acrylamide, N-cerotinyl (meth) acrylamide, N-melissinyl (meth) acrylamide,N-palmitoleinyl (meth) acrylamide, N-oleyl (meth) acrylamide, N-linolyl (meth) acrylamide, N-linolenyl (meth) acrylamide, N-stearyl (meth) acrylamide, N-lauryl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, morpholinyl (meth) acrylamide.

22. (Co) polymer according to any one of claims 17, 19-21, which is a copolymer of acrylic acid with a comonomer which is acrylamide., 23. (Co)polymer according to any one of paragraphs 17-22, in which the comonomer content does not exceed 30 mass % based on the total monomer content.

24. (Co) polymer according to any one of paragraphs. 17-23, which has a fractional ratio from 2.0 to 6.

5.

25. (Co) polymer according to any one of claims 17 to 24, which has a weight average molecular weight of from 100,000 to 900,000 g / mol, preferably from 200,000 to 800,000 g / mol, particularly preferably from 300,000 to 700,000 g / mol, most preferably from 300,000 to 500,000 g / mol.

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