Polymerizable phosphonic acids (salts), their preparation methods, copolymers, and drilling fluids

Abstract

This invention relates to a polymerizable phosphonate monomer and its preparation method, as well as a copolymer prepared from the polymerizable phosphonate monomer and a drilling fluid using the copolymer. The polymerizable phosphonate (salt) has an anion with the structure shown in formula (1), and the cation is at least one of hydrogen, a monovalent metal cation, a divalent metal cation, a trivalent metal cation, and a tetravalent metal cation. 1 The H NMR spectrum shows virtually no peak at a chemical shift δ of 1.019. The method for preparing polymerizable phosphonic acid (salt) monomers provided by this invention uses an organic solvent as the solvent in the reaction system. Compared to an aqueous solvent system, this method results in higher reaction efficiency, fewer byproducts, simpler product separation, and higher product purity, thereby enabling the production of copolymers with higher molecular weights and improving the temperature and salt resistance of drilling fluids. Equation (1).

Description

Technical Field

[0001] This invention relates to a polymerizable phosphonate monomer and a method for preparing the same, as well as copolymers prepared from the polymerizable phosphonate monomer and drilling fluids using the copolymers. Background Technology

[0002] Currently, commonly used synthetic polymers in drilling fluids mainly include anionic polymers, cationic polymers, and zwitterionic polymers. Anionic and zwitterionic polymers are mostly used as filtration reducers, while cationic polymers are mainly used as shale inhibitors. Common zwitterionic polymers include commercially available drilling fluid filtration reducers such as LS-1, JT888, FA-367, and XY-27, synthesized from AM, AMPS, and DMDAAC.

[0003] CN108753267A discloses a high-temperature resistant anionic polymer filtration reducer for drilling and completion fluids and its preparation method. The high-temperature resistant anionic polymer filtration reducer is a terpolymer generated by aqueous solution polymerization using acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, and dimethylaminoethyl methacrylate as monomers. The polymer exhibits excellent filtration reduction performance at high temperatures, but its salt resistance is only moderate.

[0004] CN104388061A discloses a high-temperature and salt-resistant polymer filtration reducer for water-based drilling fluids and its preparation method. The filtration reducer is a quaternary copolymer copolymerized from monomers such as N-vinylcaprolactam, 2-acrylamido-2-methylpropanesulfonic acid, acrylic acid, and N,N-dimethylacrylamide. This filtration reducer can effectively improve the drilling fluid system's resistance to temperature and salt, as well as its viscosity retention after high-temperature aging. However, its filtration reduction ability is limited by changes in the physicochemical properties of subcritical water in high-temperature and high-pressure environments.

[0005] Currently, given the high formation temperature and high salinity in oilfield drilling, in order to achieve wellbore stability and safe drilling, drilling polymers must have higher filtration loss reduction capabilities and resistance to temperature, salt, and shear. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of this invention is to provide a polymerizable phosphonate (salt) monomer and its preparation method, as well as a copolymer prepared from the polymerizable phosphonate monomer and a drilling fluid using the copolymer. The method for preparing the polymerizable phosphonate (salt) monomer provided by this invention uses an organic solvent as the solvent in the reaction system, which results in higher reaction efficiency, fewer byproducts, and simpler product separation compared to an aqueous solvent system. Clear separation of the products can be achieved using only conventional separation methods such as filtration or centrifugation, and the resulting products have higher purity. This allows for the acquisition of copolymers with higher molecular weights, and also enables the drilling fluid to achieve higher temperature and salt resistance with less monomer.

[0007] To achieve the above objectives, a first aspect of the present invention provides a polymerizable phosphonate (salt) whose anion has the structure shown in formula (1), and whose cation is at least one selected from hydrogen, a monovalent metal cation, a divalent metal cation, a trivalent metal cation, and a tetravalent metal cation, and the polymerizable phosphonate... 1 The ¹H NMR spectrum showed almost no peak at the chemical shift δ of 1.019.

[0008]

[0009] R1, R2, R3, R4, R5, R6, R7 and R8 are each independently hydrogen or C1-C10 straight-chain or branched alkyl groups; preferably hydrogen or C1-C4 straight-chain or branched alkyl groups; more preferably hydrogen, methyl or ethyl.

[0010] A second aspect of the present invention provides a method for preparing a polymerizable phosphonic acid having the structure shown in formula (2), the method comprising: reacting phosphorous acid sequentially with an amine and an aldehyde shown in formula (3) in an organic solvent under reaction conditions.

[0011]

[0012] R1, R2, R3, R4, R5, R6, R7 and R8 are each independently hydrogen or C1-C10 straight-chain or branched alkyl groups; preferably hydrogen or C1-C4 straight-chain or branched alkyl groups; more preferably hydrogen, methyl or ethyl.

[0013] A third aspect of the present invention provides a method for preparing polymerizable phosphonate, the method comprising: preparing polymerizable phosphonate by the above-described method, and directly adding an alkaline substance for neutralization reaction without a product separation and purification step.

[0014] The fourth aspect of the present invention provides a polymerizable phosphonate prepared by the above method.

[0015] The fifth aspect of this invention provides the application of the above-mentioned polymerizable phosphonic acid (salt) and the polymerizable phosphonate prepared by the above method in oilfield chemicals, water treatment, papermaking industry, fiber industry, coating industry, absorbent materials, printing and dyeing auxiliaries, and biomedicine.

[0016] A sixth aspect of the present invention provides a phosphonate-containing copolymer, the copolymer comprising structural unit A and structural unit B; structural unit A being the aforementioned polymerizable phosphonic acid (salt); structural unit B being an acrylamide-based structural unit; the mass ratio of structural unit A to structural unit B being 1:3-3:1; and the weight-average molecular weight of the copolymer being 2.5 × 10⁻⁶. 5 -1×10 7 .

[0017] A seventh aspect of the present invention provides a drilling fluid containing the above-described copolymer.

[0018] Through the above technical solutions, the polymerizable phosphonic acid (salt), its preparation method, copolymer, and drilling fluid provided by the present invention can achieve the following beneficial effects:

[0019] 1) The method for preparing polymerizable phosphonic acid (salt) monomers provided by the present invention uses an organic solvent as the solvent of the reaction system, which makes the reaction efficiency higher, the byproducts fewer, and the separation of the obtained products simpler compared with the aqueous solvent system. The products can be clearly separated by conventional separation methods such as filtration or centrifugation, and the purity of the obtained products is higher. In this way, higher molecular weight copolymers can be obtained, and the binary copolymers obtained by combining with acrylamide can significantly improve the temperature and salt resistance and corrosion and scale inhibition properties of drilling fluids.

[0020] 2) When the copolymer provided by this invention is used as a filtration loss reducer, it still exhibits good filtration loss reduction effects under high temperature conditions of 180℃ and 200℃, and is resistant to NaCl saturation and CaCl2 saturation, and also has good corrosion resistance. This is likely because the copolymer has a high molecular weight and contains phosphonate groups, which can effectively adsorb onto the surface of clay particles to form a hydration film, resulting in good filtration loss reduction capabilities under high temperature conditions. The introduction of phosphonate groups improves the copolymer's resistance to calcium and salt deposits during use, and also provides good corrosion resistance. Attached Figure Description

[0021] Figure 1 Infrared spectra of sodium diallylaminomethylphosphonate solid powders obtained in Example 1 and Comparative Example 1;

[0022] Figure 2 The infrared spectra of the binary copolymers obtained by copolymerizing sodium diallylaminomethylphosphonate and acrylamide in Example 1 and Comparative Example 1 are shown.

[0023] Figure 3Sodium diallylaminomethylphosphonate solid powder of Example 1 1 H NMR spectrum;

[0024] Figure 4 Sodium diallylaminomethylphosphonate solid powder as Comparative Example 1 1 H NMR spectrum;

[0025] Figure 5 The copolymer obtained by copolymerizing sodium diallylaminomethylphosphonate and acrylamide in Example 1 is 1 HNMR spectrum;

[0026] Figure 6 The copolymer obtained by copolymerizing sodium diallylaminomethylphosphonate and acrylamide in Comparative Example 1 1 HNMR spectrum;

[0027] Figure 7 Sodium diallylaminomethylphosphonate solid powder of Example 1 31 P NMR spectrum;

[0028] Figure 8 Sodium diallylaminomethylphosphonate solid powder as Comparative Example 1 31 P NMR spectrum;

[0029] Figure 9 The copolymer obtained by the binary copolymerization of sodium diallylaminomethylphosphonate and acrylamide in Example 1 31 PNMR spectrum;

[0030] Figure 10 The copolymer obtained by the binary copolymerization of sodium diallylaminomethylphosphonate and acrylamide in Comparative Example 1 31 PNMR spectrum;

[0031] Figure 11 The infrared spectrum of sodium diallylaminomethylphosphonate solid powder in Comparative Example 2 is shown.

[0032] Figure 12 Sodium diallylaminomethylphosphonate solid powder as Comparative Example 2 1 H NMR spectrum. Detailed Implementation

[0033] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values ​​stated herein, and such ranges or values ​​should be understood to include values ​​close to such ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0034] The first aspect of this invention provides a polymerizable phosphonate (salt) whose anion has the structure shown in formula (1), and whose cation is at least one selected from hydrogen, a monovalent metal cation, a divalent metal cation, a trivalent metal cation, and a tetravalent metal cation, and the polymerizable phosphonate... 1 The H NMR spectrum showed almost no peaks near the chemical shift δ of 1.019.

[0035]

[0036] R1, R2, R3, R4, R5, R6, R7 and R8 are each independently hydrogen or C1-C10 straight-chain or branched alkyl groups; preferably hydrogen or C1-C4 straight-chain or branched alkyl groups; more preferably hydrogen, methyl or ethyl.

[0037] In this invention, examples of the C1-C10 straight-chain or branched alkyl groups may be, for example, any one of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, n-hexyl, isohexyl, n-heptyl, isoheptyl, 2-methylhexyl, 2-ethylhexyl, 1-methylheptyl, 2-methylheptyl, n-octyl, isooctyl, n-nonyl, isononyl, and 3,5,5-trimethylhexyl.

[0038] The polymerizable phosphonic acid (salt) of the present invention is a water-soluble solid powder that is readily soluble in water and slightly soluble in most organic solvents. It can be used as a novel monomer and is widely used in oilfield polymers, especially in the synthesis of polymer treatment agents for drilling and completion.

[0039] In this invention, the polymerizable phosphonate 1 The statement that there are virtually no peaks near the chemical shift δ of 1.019 in ¹H NMR means that the peak height ratio between the peak near the chemical shift δ of 1.019 and the peak near the chemical shift δ of 5.83 is less than 0.05. Here, "near" refers to acceptable instrument and operational errors, typically ±1 ppm.

[0040] According to the present invention, the peak near the chemical shift δ of 1.019 and the peak near the chemical shift δ of 5.83 are respectively attributed to PO3. 3- The peak height ratio of the two peaks (C=C group) is less than 0.05, indicating that the content of phosphorous acid impurities in the polymerizable phosphonic acid (salt) is very low, even lower than that of the C=C group. 1 The detection limit of H NMR.

[0041] And such Figure 4 As shown, the polymerizable phosphonic acid (salt) obtained by using an aqueous solvent as the reaction solvent in the prior art, even after various purification steps, still has the strongest peak at the δ position of 1.019.

[0042] from Figure 7 It can be seen that the polymerizable phosphonate provided by the present invention... 31 The P NMR spectrum showed almost no phosphorous acid peak near the chemical shift δ 4.46, which belongs to PO3. 3- The presence of functional groups also indicates that the polymerizable phosphonate provided by this invention has high purity and is essentially free of raw material phosphorous acid (below the detection limit).

[0043] In some embodiments, the liquid chromatography purity of the polymerizable phosphonic acid (salt) is 97-99.9 wt%, preferably 98.5-99.9 wt%. The liquid chromatography content of impurities does not exceed 3 wt%. In contrast, the liquid chromatography purity of prior art polymerizable phosphonic acids (salts) generally does not exceed 95 wt%, and contains not less than 5 wt% phosphorous acid or diallylamine impurities.

[0044] In some embodiments, the 1606 cm⁻¹ region is essentially absent in the infrared spectrum of the polymerizable phosphonic acid (salt). -1 The peak. 1606cm -1 The peak corresponds to diallylamine impurities, and existing technologies can polymerize phosphonic acid (salts) because of the high content of this impurity, which can generally be clearly seen in the infrared spectrum.

[0045] Because both the reactants and products have a certain degree of water solubility, it is difficult to remove phosphorous acid impurities and diallylamine impurities when water is used as the solvent in the reaction system. The presence of these impurities makes it difficult for the molecular weight of the polymer to exceed 200,000 in the copolymerization reaction. In particular, it leads to uneven distribution of polymerizable phosphonates (salts) in the copolymer, thus affecting the temperature and salt resistance, corrosion and scale inhibition properties of the drilling fluid when used as a filtration loss reducer. However, the polymerizable phosphonate provided by this invention has high purity. It only needs to be copolymerized with acrylamide, a commonly used component of filtration loss reducers, to obtain a binary copolymer that can achieve temperature and salt resistance and corrosion and scale inhibition properties comparable to or even better than those of existing ternary and quaternary copolymer filtration loss reducers.

[0046] The above results all demonstrate that the polymerizable phosphonic acid (salt) provided by this invention has high purity. The inventors of this invention have discovered that when using this high-purity polymerizable phosphonic acid (salt) with a phosphorous acid impurity content of less than 2 wt% copolymerized with commonly used monomers of drilling fluid filtration reducers such as acrylamide, compared with polymerizable phosphonic acid (salt) using existing technologies, the resulting polymer has a higher molecular weight and significantly improved high-temperature resistance and salt resistance, maintaining a low filtration loss reduction in a saturated sodium chloride / calcium chloride aqueous solution at 200°C. This is likely because the higher purity allows for a higher molecular weight and a more uniform distribution of phosphonate structural units, which is beneficial for improving the polymer's cohesive strength, thereby enhancing the polymer's molecular structural stability and improving its resistance to calcium fouling and its corrosion and scale inhibition properties.

[0047] In some embodiments, the cation of the polymerizable phosphonic acid (salt) is Na. + K + Li + Ca 2+ Mg 2+ Ba 2+ Cu 2+ Fe 2+ Fe 3+ Al 3+ Ti 4+ Zr 4+ One or more of the following, preferably Na + K + Li + Ca 2+ Mg 2+ Ba 2+ One or more of them.

[0048] In some embodiments, the solubility of the polymerizable phosphonic acid (salt) in water is not less than 40 g / 100 g, preferably 40-65 g / 100 g, for example 52 g / 100 g.

[0049] In this invention, the solubility test conditions are room temperature 20°C and normal pressure.

[0050] A second aspect of the present invention provides a method for preparing a polymerizable phosphonic acid having the structure shown in formula (2), the method comprising: reacting phosphorous acid sequentially with an amine and an aldehyde shown in formula (3) in an organic solvent under reaction conditions.

[0051]

[0052] R1, R2, R3, R4, R5, R6, R7 and R8 are each independently hydrogen or C1-C10 straight-chain or branched alkyl groups; preferably hydrogen or C1-C4 straight-chain or branched alkyl groups; more preferably hydrogen, methyl or ethyl.

[0053] In this invention, examples of the C1-C10 straight-chain or branched alkyl groups may be, for example, any one of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, n-hexyl, isohexyl, n-heptyl, isoheptyl, 2-methylhexyl, 2-ethylhexyl, 1-methylheptyl, 2-methylheptyl, n-octyl, isooctyl, n-nonyl, isononyl, and 3,5,5-trimethylhexyl.

[0054] According to this invention, the preparation method of polymerizable phosphonic acid uses an organic solvent as the reaction solvent, and the entire reaction process is carried out without the addition of water. The inventors of this invention have discovered that using an organic solvent as the reaction solvent and carrying out the reaction process without the addition of water can improve reaction efficiency, completing the reaction in 1-8 hours, reducing side reactions, and improving product purity. This is likely because the raw materials are more soluble in the reaction solvent than the reaction products, which are essentially insoluble in the organic solvent. Therefore, the separation of the product and the raw materials can be easily achieved, resulting in higher purity. However, when water is used as the reaction solvent, both the product and the raw materials are highly soluble in the solvent, making it difficult to separate the product from unreacted raw materials and other byproducts. This affects product purity and further impacts subsequent reactions, ultimately affecting the application performance of the polymerized product.

[0055] The preparation method of the present invention is a stepwise one-pot reaction, which has low energy consumption, short process, and is easy to achieve large-scale production.

[0056] In this invention, the organic solvent reaction system is used in the preparation, which is beneficial for the subsequent separation of the product. The product can be clearly separated by conventional separation methods such as filtration or centrifugation. The target product can be obtained by further drying at low temperature, and the solvent can be recycled.

[0057] To further improve the yield and purity of the product, the organic solvent is preferably an alcohol with 1-12 carbon atoms, an ester with 2-12 carbon atoms, or an ether or ketone with 2-12 carbon atoms, and more preferably one or more of methanol, ethanol, butanol, ethyl acetate, butyl acetate, isoamyl acetate, diethyl ether, butyl ether, acetone, and methyl ethyl ketone.

[0058] In some embodiments, the volume ratio of the organic solvent to phosphorous acid is 1:1-15, preferably 1:0.5-8.

[0059] In some embodiments, the molar ratio of the amine, phosphorous acid, and aldehyde shown in formula (3) is 1:(1-2):(1-2), preferably 1:(1-1.5):(1-1.5). Wherein, the aldehyde is expressed in moles equivalent to formaldehyde.

[0060] In some embodiments, the reaction conditions include: a pH value not exceeding 8, and a reaction temperature of -20°C to 10°C, preferably -10°C to 5°C.

[0061] In some embodiments, the pH value for the reaction of phosphorous acid with the amine shown in formula (3) is 1-6.8, preferably 1-4, and more preferably 1-3.

[0062] In some embodiments, the method does not include adding water as a solvent.

[0063] In some embodiments, the pH value of the reaction system is adjusted by adding an acidic substance, which is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, oxalic acid, glacial acetic acid, carbonic acid, hydrofluoric acid, citric acid, malic acid, tartaric acid, and succinic acid.

[0064] In this invention, the acidic substance can be any of the substances mentioned above, or other inorganic acids and / or organic acids.

[0065] In some embodiments, the aldehyde is one or more of formaldehyde, dioxymethylene, trioxymethylene, and paraoxymethylene, with formaldehyde being preferred.

[0066] In this invention, the aldehyde is preferably added in liquid form. For example, when formaldehyde is used, it can be added directly in liquid form. When paraformaldehyde, triformaldehyde, or polyformaldehyde is used, it can be dissolved in an organic solvent first and then added in liquid form. The organic solvent used can be one or more of alcohols, esters, ethers, and ketones. Furthermore, the alcohol, ester, ether, or ketone can have 1-12 carbon atoms, specifically selected from one or more of methanol, ethanol, butanol, ethyl acetate, butyl acetate, isoamyl acetate, diethyl ether, butyl ether, acetone, and methyl ethyl ketone.

[0067] A third aspect of the present invention provides a method for preparing polymerizable phosphonate, the method comprising: preparing polymerizable phosphonate by the above-described method, and directly adding an alkaline substance to carry out a neutralization reaction without separation and purification of the product.

[0068] In some embodiments, the alkaline substance is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, magnesium hydroxide, magnesium carbonate, calcium carbonate, calcium hydroxide, iron hydroxide, copper hydroxide, titanium hydroxide, zirconium hydroxide, etc., preferably sodium hydroxide and / or potassium hydroxide.

[0069] In this invention, the alkaline substance can be any of the substances mentioned above, or other inorganic bases and / or alkaline inorganic salts. The metal in the inorganic base and / or alkaline inorganic salt is selected from one or more monovalent, divalent, trivalent, and tetravalent metallic elements.

[0070] In some embodiments, the temperature of the neutralization reaction is 0-90°C, preferably 20-40°C; and the time of the neutralization reaction is 0.5-6 hours, preferably 1-3 hours.

[0071] In some embodiments, the method further includes: performing solid-liquid separation on the product obtained from the neutralization reaction, and recycling the separated liquid phase. The liquid phase mainly contains solvent and unreacted raw materials.

[0072] According to the present invention, the filtrate separated from the solid-liquid separation can be reused after replenishing with new materials, which greatly reduces production costs and improves the economy of the entire process.

[0073] According to a particularly preferred embodiment of the present invention, the method for preparing the polymerizable phosphonate includes the following steps:

[0074] S1. Mix the organic solvent and phosphorous acid, and then adjust the pH of the reaction system to be no greater than 7, preferably 1-6.8, more preferably 1-4, and even more preferably 1-3;

[0075] S2. Slowly add diallylamine to the reaction system of step S1 to carry out the reaction. The reaction temperature is -20°C to 10°C, preferably -10°C to 5°C.

[0076] S3. Slowly add aldehyde to the system after step S2 to carry out the reaction. The reaction temperature is -20℃ to 10℃, preferably -10℃ to 5℃.

[0077] S4. Adjust the pH of the system after step S3 to 6-8 and continue the reaction. The reaction temperature is 0-90℃, preferably 20-40℃; the reaction time is 0.5-6h, preferably 1-3h. The reaction product is further separated, and the separated solid phase is dried at 60-120℃ for 6-12h to obtain polymerizable phosphonate. The separated liquid phase is recycled back to step S1 for continued use.

[0078] In step S4, the separation is a solid-liquid separation. The solid-liquid separation can be achieved by any means that can separate the solid and liquid phases, specifically by one or more of the following methods: filtration separation, centrifugation separation, etc.

[0079] A fourth aspect of this invention provides a polymerizable phosphonate prepared by the above method. The polymerizable phosphonate obtained by this method has high purity, and when used in polymers obtained by polymerization with acrylamide and the like, it can significantly improve the temperature and salt resistance, corrosion and scale inhibition properties of drilling fluid filtration reducers.

[0080] The polymerizable phosphonic acid (salt) of this invention is a water-soluble solid powder, readily soluble in water and slightly soluble in most organic solvents. In the preparation process, organic solvents are used as reaction solvents, and the reaction is carried out under anhydrous conditions, which can improve reaction efficiency, reduce side reactions, and simultaneously improve the purity of the obtained product. As a novel monomer, it can be widely used in oilfield polymers, especially in the synthesis of polymer treatment agents for drilling and completion.

[0081] The present invention provides polymerizable phosphonic acid (salt) that can be applied in oilfield chemicals, water treatment, papermaking industry, fiber industry, coating industry, water-absorbing materials, printing and dyeing auxiliaries, and biomedicine. Among them, oilfield chemicals include, but are not limited to: oil displacement, enhanced oil recovery, viscosity reduction, water shut-off and profile control, drilling and completion polymer reagents.

[0082] A fifth aspect of the present invention provides a phosphonate-containing copolymer, the copolymer comprising structural unit A and structural unit B; structural unit A is derived from the above-mentioned polymerizable phosphonate; structural unit B is an acrylamide-based structural unit; the mass ratio of structural unit A to structural unit B is 1:3-3:1; and the weight-average molecular weight of the copolymer is 2.5 × 10⁻⁶. 5 -1.0×10 7 .

[0083] In some embodiments, the anion of structural unit A is a polymerizable phosphonate anion as shown in formula (I), and the cation is at least one of a monovalent metal cation, a divalent metal cation, a trivalent metal cation, and a tetravalent metal cation; the structural unit B is an acrylamide-based structural unit as shown in formula (II).

[0084]

[0085] Among them, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 and R 11 Each of the components is independently hydrogen or a C1-C10 straight-chain or branched alkyl group; preferably hydrogen or a C1-C4 straight-chain or branched alkyl group; more preferably hydrogen, methyl or ethyl.

[0086] In this invention, examples of the C1-C10 straight-chain or branched alkyl groups may be, for example, any one of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, n-hexyl, isohexyl, n-heptyl, isoheptyl, 2-methylhexyl, 2-ethylhexyl, 1-methylheptyl, 2-methylheptyl, n-octyl, isooctyl, n-nonyl, isononyl, and 3,5,5-trimethylhexyl.

[0087] In this invention, the cation is represented by M, which can be a monovalent, divalent, trivalent, or tetravalent metal. M is bonded to polymerizable phosphonate anions via ionic bonds. Further, when M is a monovalent metal, it can be one or more of Group IA metals, preferably sodium and / or potassium, more preferably sodium; when M is a divalent metal, it can be one or more of magnesium, calcium, copper, and ferrous metals; when M is a trivalent metal, it can be one or more of iron and aluminum; when M is a tetravalent metal, it can be one or more of titanium and zirconium. Clearly, according to the principle of electroneutrality, when M is a monovalent metal, one structural unit A contains two M's, and when M is a divalent metal, one structural unit A contains one M'.

[0088] According to the present invention, the structural unit shown in formula (I) is a polymerizable phosphonate structural unit derived from the above-mentioned polymerizable phosphonic acid (salt); the structural unit shown in formula (II) is an acrylamide structural unit.

[0089] When the copolymer of the present invention is used as a filtration loss reducer, it still has a good filtration loss reduction effect at 180°C, is resistant to NaCl saturation and CaCl2 saturation, and has good corrosion resistance.

[0090] In some embodiments, the infrared spectrum of the copolymer is as follows: Figure 2 As shown. By Figure 2 It can be seen that the aqueous system has significantly more impurity peaks, with 990 cm⁻¹ being particularly high. -1 and 954cm -1 The peak at 1420 cm⁻¹ represents the CH bending vibration of the terminal alkenyl group. -1 The position represents the -CN stretching vibration of the amide, at 1670 cm⁻¹. -1 The peak at 1620 cm⁻¹ is the characteristic absorption peak of the carbonyl group, i.e., the C=O stretching vibration of the amide. -1 The characteristic peak of the NH bending vibration of the amide indicates that the polymer contains diallylamine and polyamide.

[0091] In some embodiments, the copolymer's 1 H NMR image as follows Figure 5 As shown, Figure 5 In the chromatogram, the peak intensity is stronger at 1.1-1.8 ppm and weaker at 5.5-6.3 ppm, with a peak height ratio of not less than 5:1. The copolymer obtained using phosphonates prepared with water as a solvent... 1 H NMR image as follows Figure 6 As shown, Figure 6The peak intensity is stronger at 5.5-6.3 ppm and weaker at 1.1-1.8 ppm, with a peak height ratio of almost 0.1:1. This is presumably because the phosphonate prepared using water as a solvent contains a certain amount of unreacted diallylamine.

[0092] In some embodiments, the copolymer is a binary copolymer containing structural unit A and structural unit B.

[0093] In some embodiments, the binary copolymer is a random copolymer.

[0094] In some embodiments, the method for preparing the binary copolymer includes: mixing the above-mentioned polymerizable phosphonate monomer with the acrylamide monomer shown in formula (4) and water, then adding an initiator to carry out a polymerization reaction, and drying the reaction product to obtain the binary copolymer.

[0095]

[0096] Among them, R9, R 10 and R 11 Each of the components is independently hydrogen or a C1-C10 straight-chain or branched alkyl group; preferably hydrogen or a C1-C4 straight-chain or branched alkyl group; more preferably hydrogen, methyl or ethyl.

[0097] In this invention, examples of the C1-C10 straight-chain or branched alkyl groups may be, for example, any one of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, n-hexyl, isohexyl, n-heptyl, isoheptyl, 2-methylhexyl, 2-ethylhexyl, 1-methylheptyl, 2-methylheptyl, n-octyl, isooctyl, n-nonyl, isononyl, and 3,5,5-trimethylhexyl.

[0098] In some preferred embodiments, the mass ratio of the polymerizable phosphonate monomer to the acrylamide monomer shown in formula (4) is 1:3-3:1.

[0099] In some preferred embodiments, the total mass concentration of the polymerizable phosphonate monomer and the acrylamide monomer shown in formula (4) is 5%-60%.

[0100] In some preferred embodiments, the initiator is a persulfate, specifically at least one of potassium persulfate, sodium persulfate, and ammonium persulfate.

[0101] In some preferred embodiments, the amount of initiator is 0.05-1.5% of the total mass of the polymerizable phosphonate monomer and the acrylamide monomer shown in formula (4).

[0102] In some preferred embodiments, the polymerization temperature is 40-80°C, preferably 40-70°C.

[0103] In some preferred embodiments, the polymerization reaction takes 1-6 hours.

[0104] According to the present invention, the method for preparing polymerizable phosphonic acid (salt) monomers uses an organic solvent as the solvent of the reaction system, which makes the reaction more efficient, produces fewer by-products, and is simpler to separate than an aqueous solvent system. The products can be clearly separated by conventional separation methods such as filtration or centrifugation, and the resulting products have higher purity. This allows for the acquisition of copolymers with higher molecular weights, thereby improving the temperature and salt resistance of drilling fluids.

[0105] The binary copolymer of the present invention has good water solubility and can be effectively adsorbed on the surface of clay particles to form a hydration film. It has good filtration loss reduction ability, good calcium and salt resistance and good corrosion resistance under high temperature conditions.

[0106] In addition to structural units A and B described above, in some embodiments, the copolymer may also contain structural unit C, which is one or more derived from cationic monomers, anionic monomers, nonionic monomers, and zwitterionic monomers. Therefore, the copolymer may also be a ternary or higher copolymer containing structural units A, B, and C.

[0107] In some embodiments, the cationic monomer may be one or more of DMC (methacryloyloxyethyltrimethylammonium chloride), DMDAAC (dimethyl diallyl ammonium chloride), DAC (acryloyloxyethyltrimethylammonium chloride), DBC (acryloyloxyethyldimethylbenzylammonium chloride), DEDAAC (diethyl diallyl ammonium chloride), DMAEMA (dimethylaminoethyl methacrylate), and DMAEA (dimethylaminoethyl acrylate).

[0108] In some embodiments, the anionic monomer may be AA (acrylic acid), AMPS (2-acrylamide-2-methylpropanesulfonic acid), AS (sodium allyl sulfonate), SS (sodium p-styrene sulfonate), AMOPS (2-acryloyloxy-2-methylpropanesulfonic acid), AOBS (acryloyloxybutyl sulfonic acid), or AMC. 12 One or more of S (2-acrylamidododecanesulfonic acid), AOEMS (sodium 2-acryloyloxy-2-vinylmethylpropanesulfonate), FA (fumaric acid), SSS (sodium allyl sulfonate), and AOIAS (sodium 2-acryloyloxyisopentene sulfonate).

[0109] Furthermore, the zwitterionic monomer can be one or more of DMAPS (methacryloyloxyethyl-N,N-dimethylpropanesulfonate), DAPS (N,N-dimethylallylamine propanesulfonate), VPPS (4-vinylpyridinepropanesulfonate), MAPS (N-methyldiallylpropanesulfonate), and MABS (N-methyldiallylbutanesulfonate).

[0110] In some embodiments, the nonionic monomer may be one or more of NVP (N-vinylpyrrolidone), AN (acrylonitrile), NVF (vinylformamide), and NVA (vinylacetamide).

[0111] The introduction of different types of monomers can impart different properties to the polymer. For example, the introduction of anions acts as a polymeric protective agent in polydisperse bentonite colloidal systems, effectively maintaining the stability of bentonite particles and providing better filtration reduction under high-temperature conditions. The introduction of cationic monomers enhances the polymer's inhibitory properties, reduces clay hydration capacity, and improves the flow pattern and wellbore stability of drilling fluids. The introduction of zwitterions gives the polymer good high-temperature and salt resistance, effectively preventing formation damage and protecting oil and gas production capacity. The above monomers, combined with the phosphonate-containing monomers provided in this invention, can have a synergistic effect, further improving calcium and salt resistance and maintaining the rheological properties of the system.

[0112] In some preferred embodiments, the initiator is a persulfate, specifically at least one of potassium persulfate, sodium persulfate, and ammonium persulfate.

[0113] In some preferred embodiments, the amount of initiator is 0.05-1.5% of the total mass of the polymerizable phosphonate monomer, P monomer and acrylamide monomer as shown in formula (4).

[0114] In some preferred embodiments, the polymerization reaction is carried out at a temperature of 40-80°C, preferably 40-70°C.

[0115] In some preferred embodiments, the polymerization reaction takes 1-6 hours.

[0116] In some preferred embodiments, the drying temperature is 30-80°C and the drying time is 3-20 hours.

[0117] The polymers obtained by the above preparation method can be used as oilfield chemicals, such as polymers for oil displacement, enhanced oil recovery, viscosity reduction, water shut-off and profile control, drilling and completion, as well as in water treatment, papermaking industry, fiber industry, coating industry, absorbent materials, printing and dyeing auxiliaries, biomedicine and other fields.

[0118] A seventh aspect of the present invention provides a drilling fluid containing the above-described copolymer.

[0119] In some embodiments, the copolymer content is 0.5-5 wt% based on the total amount of drilling fluid.

[0120] The copolymer of this invention can be used as a filtration loss reducer in drilling fluids. Even as a binary copolymer, it maintains good filtration loss reduction effects at high temperatures of 180°C and 200°C, and retains high filtration loss reduction effects in saturated NaCl and CaCl2 solutions, while also exhibiting good corrosion resistance. This is likely because the copolymer contains phosphonate groups, and due to the high purity of the phosphonate monomers, the resulting polymer can effectively adsorb onto the surface of clay particles, forming a hydration film. This results in good filtration loss reduction capabilities under high temperature and high salinity conditions, as well as excellent corrosion resistance.

[0121] The following examples illustrate the function and effect of the method of the present invention, but the following examples do not constitute a limitation on the present invention.

[0122] Unless otherwise specified in the following examples and comparative examples, all conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0123] In the embodiments and comparative examples of this invention, the yield, wt% = (actual weight of product / theoretical weight of product) × 100%, wherein the theoretical weight of product is calculated based on 100% conversion of diallylamine. Purity is obtained by liquid chromatography.

[0124] 1 H NMR was measured using a Bruker Ravance III HD400 instrument;

[0125] 31 P NMR was measured using a Bruker Ravance III HD400 instrument;

[0126] The infrared spectrum was obtained by potassium bromide tablet compression method.

[0127] Example 1

[0128] (1) Synthesis of polymerizable phosphonate: 5.7 g of phosphorous acid and 7 mL of anhydrous ethanol were added to a reaction vessel. Then, 2 mL of concentrated sulfuric acid (98 wt%) was added to adjust the pH of the system to 1. The reaction vessel was then placed in an ice-water bath, and 8.6 mL of diallylamine was added dropwise through a constant dropping funnel, with the addition completed within 45 min. After the addition was completed, the temperature was raised to reflux temperature, and the reaction was continued for 2 h. Subsequently, a mixture of 12.6 g of paraformaldehyde and 7 mL of anhydrous ethanol was added dropwise through a constant dropping funnel, with the addition completed within 20 min. After the addition was completed, the reaction was continued under reflux for 3 h. Then, 5.6 g of NaOH was added to the system to adjust the pH to 7, and the reaction was carried out at 20 °C for 1 h. After further centrifugation, the obtained solid material was further dried at 80 °C for 10 h to obtain sodium diallylaminomethylphosphonate solid powder. The infrared spectrum of the target product is shown below. Figure 1 The target product 1 The H NMR spectrum is shown in [reference]. Figure 3 The target product 31 The P NMR spectrum is shown below. Figure 7 .

[0129] The infrared spectrum shows that in the 900-1300 cm⁻¹ range... -1 The spectral information at this location is relatively rich, and this range mainly consists of stretching vibrations of CP single bonds and P=O double bonds.

[0130] from 1 The 1H NMR spectrum shows that the peaks at chemical shift δ 5.20 and δ 5.83 belong to hydrogen atoms on different sides of the C=C double bond, while the peak at chemical shift δ 3.22 belongs to the hydrogen atom at the terminal C atom of the allylic group attached to the amino group. Furthermore... 1 The 1H NMR spectrum shows virtually no peak at δ 1.019 belonging to the phosphorous acid source, indicating high purity.

[0131] from 31 As can be seen from the p NMR spectrum 31 The chemical shift δ of the P NMR is 11.51, which falls within the range of a three-coordinate phosphine ligand, indicating that the hydrogen atom on the P atom is substituted by an alkyl group. Furthermore... 31 The P NMR spectrum shows virtually no peak at δ 4.46 belonging to the phosphorous raw material, indicating high purity.

[0132] The above spectral analysis, combined with the raw material analysis, proves that the obtained product is the target product, sodium diallylaminomethylphosphonate.

[0133] (2) Preparation of the binary copolymer: 4g of sodium diallylaminomethylphosphonate solid powder obtained in step (1) and 10g of acrylamide were added to 60g of deionized water. After complete dissolution, nitrogen gas was passed through to remove oxygen for 15min. Then the temperature was raised to 65℃, 0.1g of potassium persulfate was added, and after reacting for 2h, excess acetone was added to obtain a white precipitate. The white precipitate was dried and pulverized at 80℃ to obtain the copolymer. The results are shown in Table 1.

[0134] The infrared spectrum of the binary copolymer product is shown below. Figure 2 The binary copolymer product 1 The H NMR spectrum is shown in [reference]. Figure 5 Peak B at 1.1-1.8 ppm is stronger, while peak B at 5.5-6.3 ppm is weaker, with a peak height ratio greater than 8:1. 31 PNMR spectrum as shown Figure 9 As shown, the chemical shift δ is 6.212. The weight-average molecular weight of the copolymer, determined by GPC gel permeation chromatography, is 5 × 10⁻⁶. 6 .

[0135] The infrared and nuclear magnetic spectra of the monomers and copolymers obtained in other embodiments are similar to those in Example 1, and will not be described again.

[0136] Example 2

[0137] (1) Synthesis of polymerizable phosphonate: 5.7 g of phosphorous acid and 7 mL of ethyl acetate were added sequentially to a reaction vessel. Then, 2 mL of concentrated sulfuric acid (98 wt%) was added to adjust the pH of the system to 1. The reaction vessel was then placed in a -15°C water bath, and 8.6 mL of diallylamine was added dropwise through a constant dropping funnel, with the addition controlled to be completed within 30 min. After the addition was completed, the mixture was refluxed for 2 h. Subsequently, a mixture of 12.6 g of paraformaldehyde and 7 mL of ethyl acetate was added dropwise through a constant dropping funnel, with the addition controlled to be completed within 20 min. After the addition was completed, the mixture was refluxed for 3 h. Then, 5.6 g of NaOH was added to the system to adjust the pH to 7, and the reaction was carried out at 20°C for 1 h. After further centrifugation, the obtained solid material was dried at 80°C for 10 h to obtain the target product, sodium diallylaminomethylphosphonate solid powder.

[0138] (2) Preparation of binary copolymer: 15g of sodium diallylaminomethylphosphonate solid powder obtained in step (1) and 5g of acrylamide were added to 80g of deionized water. After complete dissolution, nitrogen gas was passed through to remove oxygen for 30min. The temperature was raised to 65℃, and 0.3g of potassium persulfate was added. After reacting for 2h, excess acetone was added to obtain a white precipitate. The white precipitate was dried and pulverized at 80℃ to obtain the copolymer. The results are shown in Table 1.

[0139] Example 3

[0140] (1) Synthesis of polymerizable phosphonate: 15g of phosphorous acid and 14mL of anhydrous ethanol were added sequentially to a reaction vessel. Then, 6mL of concentrated sulfuric acid (98wt%) was added to adjust the pH of the system to 1. The reaction vessel was then placed in an ice-water bath, and 8.6mL of diallylamine was added dropwise through a constant dropping funnel, completing the addition within 45min. After the addition was complete, the reaction was refluxed for 3h. Subsequently, a mixture of 15g of trioxymethylene and 14mL of anhydrous ethanol was added dropwise through a constant dropping funnel, completing the addition within 40min. After the addition was complete, the reaction was refluxed for 4h. 11.5g of KOH was added to the system to adjust the pH to 7, and the reaction was carried out at 20℃ for 3h. After further centrifugation, the obtained solid phase was further dried at 90℃ for 10h to obtain the target product, potassium diallylaminomethylphosphonate solid powder.

[0141] (2) Preparation of binary copolymer: Take 5g of potassium diallylaminomethylphosphonate solid powder obtained in step (1) and 10g of acrylamide and add them to 70g of deionized water. After complete dissolution, nitrogen gas is passed through to remove oxygen for 10min. Then, the temperature is raised to 65℃, 0.1g of potassium persulfate is added, and after reacting for 2h, excess acetone is added to obtain a white precipitate. The white precipitate is dried and pulverized at 80℃ to obtain the copolymer. The results are shown in Table 1.

[0142] Example 4

[0143] (1) Synthesis of polymerizable phosphonate: 5.7 g of phosphorous acid and 7 mL of methanol were added to a reaction vessel, followed by 7 mL of oxalic acid to adjust the pH to 2. The reaction vessel was then placed in an ice-water bath, and 8.6 mL of diallylamine was added dropwise through a constant dropping funnel, with the addition completed within 45 min. After the addition was completed, the reaction was refluxed for 2 h. Subsequently, a mixture of 6.3 g of paraformaldehyde and 3.5 mL of methanol was added dropwise through a constant dropping funnel, with the addition completed within 10 min. After the addition was completed, the reaction was refluxed for 1.5 h. Then, 5.6 g of NaOH was added to the system to adjust the pH to 7, and the reaction was carried out at 20 °C for 2 h. After further centrifugation, the obtained solid material was dried at 80 °C for 10 h to obtain the target product, sodium diallylaminomethylphosphonate solid powder.

[0144] (2) Preparation of the binary copolymer: 4g of sodium diallylaminomethylphosphonate solid powder obtained in step (1) and 10g of acrylamide were added to 70g of deionized water. After complete dissolution, nitrogen gas was passed through to remove oxygen for 5min. The temperature was raised to 80℃, and 0.14g of sodium persulfate was added. After reacting for 2h, excess acetone was added to obtain a white precipitate. The white precipitate was dried and pulverized at 80℃ to obtain the copolymer. The results are shown in Table 1.

[0145] Example 5

[0146] (1) Synthesis of polymerizable phosphonate: 11.4 g of phosphorous acid and 7 mL of anhydrous ethanol were added sequentially to a reaction vessel. Then, 3 mL of concentrated nitric acid (70 wt%) was added to adjust the pH of the system to 1. The reaction vessel was then placed in an ice-water bath, and 8.6 mL of diallylamine was added dropwise through a constant dropping funnel, with the addition completed within 45 min. After the addition was completed, the reaction was refluxed for 2.5 h. Subsequently, a mixture of 6.3 g of paraformaldehyde and 7 mL of anhydrous ethanol was added dropwise through a constant dropping funnel, with the addition completed within 10 min. After the addition was completed, the reaction was refluxed for 1.5 h. Then, 5.6 g of KOH was added to the system to adjust the pH to 7, and the reaction was carried out at 20 °C for 2.5 h. After further centrifugation, the obtained solid material was dried at 80 °C for 10 h to obtain the target product, potassium diallylaminomethylphosphonate solid powder.

[0147] (2) Preparation of the binary copolymer: Take 8g of potassium diallylaminomethylphosphonate solid powder obtained in step (1) and 24g of acrylamide and add them to 100g of deionized water. After complete dissolution, nitrogen gas is passed through to remove oxygen for 30min. Then, the temperature is raised to 60℃, 0.48g of potassium persulfate is added, and after reacting for 3h, excess acetone is added to obtain a white precipitate. The white precipitate is dried and pulverized at 80℃ to obtain the copolymer. The results are shown in Table 1.

[0148] Example 6

[0149] (1) Synthesis of polymerizable phosphonate: 11.4 g of phosphorous acid and 7 mL of butanol were added sequentially to a reaction vessel. Then, 7 mL of oxalic acid was added to adjust the pH of the system to 2. The reaction vessel was then placed in an ice-water bath, and 8.6 mL of diallylamine was added dropwise through a constant dropping funnel, with the addition controlled to be completed within 45 min. After the addition was completed, the reaction was refluxed for 2.5 h. Subsequently, a mixture of 12.6 g of paraformaldehyde and 7 mL of butanol was added dropwise through a constant dropping funnel, with the addition controlled to be completed within 10 min. After the addition was completed, the reaction was refluxed for 1.5 h. Then, 5.6 g of NaOH was added to the system to adjust the pH to 7, and the reaction was carried out at 20 °C for 2.5 h. After further centrifugation, the obtained solid phase was further dried at 80 °C for 10 h to obtain the target product, sodium diallylaminomethylphosphonate solid powder.

[0150] (2) Preparation of binary copolymer: Take 5g of sodium diallylaminomethylphosphonate solid powder obtained in step (1) and 5g of acrylamide and add them to 50g of deionized water. After complete dissolution, purge with nitrogen for 10min to remove oxygen, heat to 50℃, add 0.15g of potassium persulfate, react for 3h, add excess acetone to obtain a white precipitate, dry the white precipitate at 80℃ and pulverize it to obtain the copolymer. The results are shown in Table 1.

[0151] Example 7

[0152] (1) Synthesis of polymerizable phosphonate: 5.7 g of phosphorous acid and 7 mL of methanol were added to a reaction vessel, followed by 4 mL of glacial acetic acid to adjust the pH of the system to 4.5. The reaction vessel was then placed in an ice-water bath, and 7.5 mL of diallylamine was added dropwise through a constant dropping funnel, with the addition completed within 40 min. After the addition was completed, the reaction was refluxed for 3 h. Subsequently, a mixture of 7 g of paraformaldehyde and 5 mL of methanol was added dropwise through a constant dropping funnel, with the addition completed within 10 min. After the addition was completed, the reaction was refluxed for 1.5 h. Then, 9 g of Ca(OH)2 was added to the system to adjust the pH to 7.5, and the reaction was carried out at 20 °C for 3 h. After further centrifugation, the obtained solid material was dried at 80 °C for 10 h to obtain the target product, calcium diallylaminomethylphosphonate solid powder.

[0153] (2) Preparation of binary copolymer: 8g of calcium diallyl aminomethylphosphonate solid powder obtained in step (1) and 10g of acrylamide were added to 70g of deionized water. After complete dissolution, nitrogen gas was passed through to remove oxygen for 10min. The temperature was raised to 60℃, and 0.1g of potassium persulfate was added. After reacting for 2h, excess acetone was added to obtain a white precipitate. The white precipitate was dried and pulverized at 80℃ to obtain the copolymer. The results are shown in Table 1.

[0154] Example 8

[0155] (1) Synthesis of polymerizable phosphonate: 11.4 g of phosphorous acid and 7 mL of butanol were added sequentially to a reaction vessel. Then, 5 mL of oxalic acid was added to adjust the pH of the system to 3. The reaction vessel was then placed in an ice-water bath, and 8.6 mL of diallylamine was added dropwise through a constant dropping funnel, with the addition controlled to be completed within 45 min. After the addition was completed, the reaction was refluxed for 2.5 h. Subsequently, a mixture of 10.6 g of paraformaldehyde and 7 mL of butanol was added dropwise through a constant dropping funnel, with the addition controlled to be completed within 10 min. After the addition was completed, the reaction was refluxed for 1.5 h. Then, 8.8 g of Mg(OH)2 was added to the system, the pH of the system was adjusted to 7.5, and the reaction was carried out at 20 °C for 2.5 h. After further centrifugation, the obtained solid phase was further dried at 80 °C for 10 h to obtain the target product, magnesium diallylaminomethylphosphonate solid powder.

[0156] (2) Preparation of binary copolymer: 10g of magnesium diallylaminomethylphosphonate solid powder obtained in step (1) and 10g of acrylamide were added to 60g of deionized water. After complete dissolution, nitrogen gas was passed through to remove oxygen for 10min. The temperature was raised to 40℃, and 0.2g of potassium persulfate was added. After reacting for 2h, excess acetone was added to obtain a white precipitate. The white precipitate was dried and pulverized at 80℃ to obtain the copolymer. The results are shown in Table 1.

[0157] Comparative Example 1

[0158] (1) Synthesis of polymerizable phosphonate: 5.7 g of phosphorous acid and 7 mL of water were added sequentially to a reaction vessel. Then, 3 mL of concentrated nitric acid (70 wt%) was added to adjust the pH of the system to 1. The reaction vessel was then placed in an ice-water bath, and 8.6 mL of diallylamine was added dropwise through a constant dropping funnel, with the addition controlled to be completed within 45 min. After the addition was completed, the reaction was refluxed for 2 h. Subsequently, a mixture of 12.6 g of paraformaldehyde and 7 mL of water was added dropwise through a constant dropping funnel, with the addition controlled to be completed within 40 min. After the addition was completed, the reaction was refluxed for 2 h. 5.6 g of NaOH was added to the system to adjust the pH to 7, and the reaction was carried out at 20 °C for 1 h. After further centrifugation, the product was washed three times with ethanol. The resulting solid material was further dried at 80 °C for 10 h to obtain the target product, sodium diallylaminomethylphosphonate solid powder.

[0159] The infrared spectrum of the target product is shown below. Figure 1 The target product 1 The H NMR spectrum is shown in [reference]. Figure 4 The target product 31 See PNMR spectrum Figure 8 .

[0160] As can be seen from the infrared spectrum, the phosphonic acid monomers prepared through an aqueous system exhibit numerous impurity peaks. For example, at 3075 cm⁻¹... -1 The appearance of a small shoulder peak indicates the presence of olefins (v). C-H Stretching vibration, at 1649cm -1 A weaker v also appeared. C＝C Stretching vibrations, as indicated by the above two points, suggest the presence of olefins. At 1606 cm⁻¹ -1 Presenting δ N-H It is characterized by a moderately strong broad peak at 1072 cm⁻¹. -1 Present v C-N Weak absorption peak and at 830 cm⁻¹ -1 Presented γ N-H The broad absorption peaks indicate the presence of amines, and these two points confirm the presence of unreacted diallylamine.

[0161] from 1 The 1H NMR spectrum shows a strong peak at chemical shift δ 1.019, which corresponds to the phosphorous acid in the starting material. This indicates the presence of unreacted phosphorous acid in the starting material. Furthermore, the peak at chemical shift δ 1.019 is significantly stronger than the peak at chemical shift δ 5.15, suggesting a higher impurity content.

[0162] from 31 As can be seen from the p NMR spectrum 31 The chemical shift of the P NMR is δ13.19, but there are two peaks with chemical shifts of δ4.63 and δ4.25, which indicates the presence of impurities.

[0163] (2) Preparation of the binary copolymer: 4g of sodium diallylaminomethylphosphonate solid powder obtained in step (1) and 10g of acrylamide were added to 60g of deionized water. After complete dissolution, nitrogen gas was passed through to remove oxygen for 15min. The temperature was raised to 65℃, and 0.1g of potassium persulfate was added. After reacting for 2h, excess acetone was added to obtain a white precipitate. The white precipitate was dried and pulverized at 80℃ to obtain the copolymer. The results are shown in Table 1.

[0164] The infrared spectrum of the binary copolymer product is shown below. Figure 2 The binary copolymer product 1 The H NMR spectrum is shown in [reference]. Figure 6 The binary copolymer product 31 The P NMR spectrum is shown below. Figure 10 The peak intensity is stronger at the 1.1-1.8 ppm position and stronger at the 5.5-6.3 ppm position. The peak height ratio of peak A to peak B is about 0.1:1.

[0165] Comparative Example 2

[0166] (1) Synthesis of polymerizable phosphonate: 5.7 g phosphorous acid, 3.5 mL water, and 3.5 mL ethyl acetate were added to a reaction vessel, followed by 4 mL glacial acetic acid. The vessel was placed in an ice-water bath, and 8.6 mL diallylamine was slowly added dropwise to the mixture, completing the addition within 45 min. The mixture was then refluxed for 3 h. Next, a mixture of 12.6 g paraformaldehyde, 3.5 mL water, and 3.5 mL ethyl acetate was added to the system in proportion, with the reaction time controlled at 60 min. The mixture was then refluxed for another 4 h. 5.6 g NaOH was added to the system to adjust the pH to 7, and the reaction was carried out at 20 °C for 1 h. After further centrifugation, the product was washed three times with ethanol. The resulting solid material was then dried at 80 °C for 10 h to obtain the target product, sodium diallylaminomethylphosphonate solid powder.

[0167] The infrared spectrum of the target product is shown below. Figure 11 The target product 1 The H NMR spectrum is shown in [reference]. Figure 12 .

[0168] As can be seen from the infrared spectrum, 1640 cm⁻¹ -1 The peak at 914 cm⁻¹ is due to C=C stretching vibration. -1 and 980cm -1 The peak at the point is an out-of-plane rocking vibration of =C-H, proving the presence of unreacted diallylamine.

[0169] from 1 The H NMR spectrum shows that, compared with the pure solvent system, the mixed system exhibits impurity peaks, such as the peak at the chemical shift δ position of 1.826.

[0170] (2) Preparation of the binary copolymer: 4g of sodium diallylaminomethylphosphonate solid powder obtained in step (1) and 10g of acrylamide were added to 60g of deionized water. After complete dissolution, nitrogen gas was passed through to remove oxygen for 15min. The temperature was raised to 65℃, and 0.1g of potassium persulfate was added. After reacting for 2h, excess acetone was added to obtain a white precipitate. The white precipitate was dried and pulverized at 80℃ to obtain the copolymer. The results are shown in Table 1.

[0171] Comparative Example 3

[0172] 5g of DAC (acryloyloxyethyltrimethylammonium chloride), 5g of AMPS and 10g of acrylamide were added to 120g of deionized water. After complete dissolution, nitrogen gas was purged for 10 minutes to remove oxygen. The temperature was raised to 40℃, and 0.2g of ammonium persulfate was added. After reacting for 2 hours, excess acetone was added to obtain a white precipitate. The white precipitate was dried and pulverized at 80℃ to obtain the copolymer. The results are shown in Table 1.

[0173] Table 1

[0174]

[0175]

[0176] Evaluation test

[0177] The filtration loss reduction performance of the copolymers obtained in Examples 1-8 and Comparative Examples 1-3 was evaluated using a salt- and calcium-containing base slurry. The specific evaluation method is as follows:

[0178] Evaluation method for resistance to sodium salt

[0179] 350 mL of freshwater-based slurry was measured and stirred at high speed for 5 min. Then, 3.0 wt% of copolymer was added and stirred at high speed for another 5 min. After curing at room temperature for 24 h, the filtration loss under medium pressure was measured according to the test method of GB / T16783.2-2012. The change in filtration loss was determined by adding different amounts of NaCl to the freshwater-based slurry, with lower filtration loss being better. The filtration loss results at different NaCl concentrations are shown in Table 2.

[0180] Evaluation method for anti-calcium properties

[0181] Measure 350 mL of saturated brine-based slurry, stir at high speed for 5 min, then add 3.0 wt% of copolymer, stir at high speed for 5 min, and cure at room temperature for 24 h. Measure the medium-pressure filtration loss according to the test method of GB / T16783.2-2012. Continuously increase the amount of CaCl2 in the saturated brine-based slurry and measure the change in filtration loss. The filtration loss results at different CaCl2 concentrations are shown in Table 3.

[0182] High Temperature Resistance Evaluation Method

[0183] (1) Medium pressure filtration loss

[0184] Measure 350 mL of brine-based slurry (4% NaCl), add 3.0 wt% of copolymer, stir at high speed for 5 min, age at different temperatures for 16 h, remove and cool to room temperature, stir at high speed for 20 min, and measure the medium pressure filtration loss according to the test method of GB / T16783.2-2012. The specific results are shown in Table 4.

[0185] (2) High temperature and high pressure filtration

[0186] Measure 200 mL of brine-based slurry (4% NaCl), add 3.0 wt% of copolymer, stir at high speed for 5 min, and then determine the filtration loss using a high-temperature and high-pressure water loss meter according to the test method of GB / T16783.2-2012. The temperature was set to 200℃ and the pressure was set to 3.5 MPa. The specific results are shown in Table 4.

[0187] The preparation methods for freshwater-based slurry, brine-based slurry, and saturated brine-based slurry are as follows:

[0188] Freshwater-based slurry: Add 40g of calcium bentonite and 5g of sodium carbonate to 1000mL of water, stir at high speed for 20min, and cure at room temperature (25℃, the same below) for 24h to obtain freshwater-based slurry.

[0189] Saltwater-based slurry: Add 4 wt% NaCl to 1000 mL of freshwater-based slurry, stir at high speed for 20 min, and cure at room temperature for 24 h to obtain saltwater-based slurry.

[0190] Saturated brine-based slurry: Add 36wt% NaCl to 1000mL of fresh water-based slurry, stir at high speed for 20min, and cure at room temperature for 24h to obtain saturated brine-based slurry.

[0191] Corrosion Inhibition Evaluation Method

[0192] According to SY / T 5273-2000, the static corrosion rate test under normal pressure is performed as follows: Weighed metal test pieces are respectively immersed in test media with and without polymer solution, and soaked for a certain time under specified conditions. Then, the test pieces are removed, cleaned, dried, and weighed. The corrosion inhibition rate is calculated according to formula (1):

[0193]

[0194] Wherein, Δm0 is the mass loss of the sample in the blank test (without polymer solution), in g; Δm1 is the mass loss of the sample in the test with polymer solution, in g.

[0195] The test medium was self-prepared simulated water, the mineralization and ion concentration of which were formulated based on the actual water quality on site. The Ca content in the water... 2+ The concentration is 20000 mg / L, Mg 2+ The concentration is 920 mg / L, K + Na + The total concentration was 45530 mg / L. The polymer solution was an aqueous solution containing 5 wt% of the binary copolymer solid. The corrosion inhibition rate was determined experimentally under different polymer solution dosages. A higher corrosion inhibition rate indicates better corrosion inhibition. The results are shown in Table 5.

[0196] Scale inhibition evaluation method

[0197] The scale inhibition rate was determined using the static scale inhibition method: a quantitative amount of polymer powder was added to a solution containing a certain amount of Ca. 2+ Concentration and HCO3 - The polymer concentration in the prepared water was 200 mg / L. After being kept at pH 7 and 80℃ for 8 hours, the solution was cooled, shaken, and filtered. A certain amount of the filtrate was then analyzed by EDTA complexometric titration to determine the Ca concentration in the solution. 2+ Concentration. The scale inhibition rate of the corrosion and scale inhibitor is calculated according to formula (2):

[0198]

[0199] V0, V1, and V2 represent the volume of EDTA consumed in the determination of total calcium in water prepared without polymer, with polymer, and at room temperature, respectively. A higher scale inhibition rate indicates better scale inhibition performance. The results are shown in Table 5.

[0200] Table 2 Evaluation of Salt Resistance

[0201]

[0202]

[0203] Table 3 Evaluation of Calcium Resistance

[0204]

[0205] Table 4 Evaluation of High Temperature Resistance

[0206]

[0207] As can be seen from Tables 2, 3, and 4, the filtration loss all increased with the amount of Na. + Ca 2+ The increase is due to increased concentration or temperature. Compared to aqueous and mixed systems, phosphonic acid monomers prepared in pure solvent systems exhibit better performance, and the performance of the binary copolymers is comparable to that of existing AMPS-added terpolymers.

[0208] As can be seen from Table 4, the high-temperature and high-pressure filtration loss of the binary copolymer provided by the present invention is maintained at around 14 mL, while the filtration loss in the comparative examples is greater than 100 mL, indicating that the binary copolymer of the present invention has a good effect on reducing filtration loss under high temperature and high pressure.

[0209] Table 5 Corrosion Inhibition Evaluation

[0210]

[0211] As shown in Table 5, the corrosion inhibition rate increases with increasing concentration. Compared to aqueous and mixed systems, the phosphonic acid monomers prepared in the pure solvent system exhibit better performance.

[0212] As shown in Table 5, the binary copolymers provided by this invention all exhibit good scale inhibition effects. Compared to aqueous and mixed systems, the phosphonic acid monomers prepared in the pure solvent system have better performance, and the performance of the binary copolymers is comparable to that of existing AMPS-added terpolymers.

[0213] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a polymerizable phosphonic acid, wherein the polymerizable phosphonic acid has the structure shown in formula (2), the method comprising: In an organic solvent, under reaction conditions, phosphorous acid is reacted sequentially with the amine and aldehyde shown in formula (3), wherein the method does not involve adding water as a solvent. Equation (2), Equation (3), Among them, R1, R2, R3, R4, R5, R6, R7, and R8 are each independently hydrogen or C1-C10 straight-chain or branched alkyl groups, R 12 It is hydrogen.

2. The method according to claim 1, wherein, R1, R2, R3, R4, R5, R6, R7 and R8 are each independently hydrogen or C1-C4 straight-chain or branched alkyl groups.

3. The method according to claim 2, wherein, R1, R2, R3, R4, R5, R6, R7, and R8 are each independently hydrogen, methyl, or ethyl.

4. The method according to claim 1, wherein, The organic solvent is an alcohol with 1-12 carbon atoms, an ester with 2-12 carbon atoms, an ether or a ketone with 2-12 carbon atoms.

5. The method according to claim 4, wherein, The organic solvent is one or more of methanol, ethanol, butanol, ethyl acetate, butyl acetate, isoamyl acetate, diethyl ether, butyl ether, acetone, and methyl ethyl ketone.

6. The method according to claim 1, wherein, The volume ratio of the organic solvent to phosphorous acid is 1:1-15; and / or, The molar ratio of amine, phosphorous acid and aldehyde shown in formula (3) is 1:(1-2):(1-2).

7. The method according to claim 6, wherein, The molar ratio of amine, phosphorous acid and aldehyde shown in formula (3) is 1:(1-1.5):(1-1.5).

8. The method according to claim 1, wherein, The reaction conditions include: pH value not exceeding 8, and reaction temperature ranging from -20°C to 10°C.

9. The method according to claim 8, wherein, The reaction conditions include a reaction temperature of -10°C to 5°C.

10. The method according to claim 1, wherein, The pH value for the reaction of phosphorous acid with the amine shown in formula (3) is 1-6.

8.

11. The method according to claim 10, wherein, The pH value for the reaction of phosphorous acid with the amine shown in formula (3) is 1-4.

12. The method according to claim 11, wherein, The pH value for the reaction of phosphorous acid with the amine shown in formula (3) is 1-3.

13. The method according to claim 1, wherein, The aldehyde is one or more of formaldehyde, dioxymethylene, trioxymethylene, and paraoxymethylene.

14. The method according to claim 13, wherein, The aldehyde is formaldehyde.

15. A method for preparing a polymerizable phosphonate, the method comprising: Polymerizable phosphonic acid is prepared by means of any one of claims 1-14, and a neutralization reaction is carried out by directly adding an alkaline substance without separating and purifying the product.

16. The method according to claim 15, wherein, The alkaline substance is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, magnesium hydroxide, magnesium carbonate, calcium carbonate, calcium hydroxide, iron hydroxide, copper hydroxide, titanium hydroxide, and zirconium hydroxide.

17. The method according to claim 16, wherein, The alkaline substance is selected from sodium hydroxide and / or potassium hydroxide.

18. The method according to claim 15, wherein, The neutralization reaction is carried out at a temperature of 0-90℃ and for a time of 0.5-6 hours.

19. The method according to claim 18, wherein, The neutralization reaction is carried out at a temperature of 20-40°C for 1-3 hours.

20. The method of claim 15, wherein, The method further includes: performing solid-liquid separation on the product obtained from the neutralization reaction, and recycling the separated liquid phase.

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