Alkyl acrylamide-imide-quaternary ammonium salt polymers, paraffin control agents, and methods of making the same

Abstract

Disclosed are an alkyl acrylamide-imide-quaternary ammonium salt polymer, a wax cleaning and preventing agent, and a preparation method thereof. The polymer contains a structural unit shown in Formula I, a structural unit shown in Formula II, and a structural unit shown in Formula III: wherein R1 is selected from a hydrogen atom or a C1-C3 alkyl group; R2 is selected from a group containing a quaternary ammonium salt; R3 is selected from a hydrogen atom or a C1-C3 alkyl group; R4 is selected from a C4-C 24 alkyl group; R5 is selected from a hydrogen atom or a C1-C3 alkyl group; and R6 is selected from a group containing an imide structure shown in Formula IV: The wax cleaning and preventing agent of the present application includes the alkyl acrylamide-imide-quaternary ammonium salt polymer. The wax cleaning and preventing agent of the present application has both good wax cleaning and wax preventing effects, and has a wide applicable temperature range.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction technology, and particularly relates to an alkylacrylamide-imide-quaternary ammonium salt polymer, as well as a wax remover and its preparation method. Background Technology

[0002] After oil reservoir extraction, as reservoir fluids flow towards the surface, temperature and pressure gradually decrease, causing dissolved paraffin components in the crude oil to precipitate out. Simultaneously, mechanical impurities carried in the crude oil provide adhesion conditions for paraffin deposition. These wax molecules deposit and condense on tubing walls, casing walls, and other equipment, forming a wax deposition phenomenon. The deposition and condensation of paraffin affect oilfield production. Wax deposition on tubing walls reduces the tubing's planar flow area, increasing resistance to crude oil lifting and reducing production well output. Wax deposition on sucker rods increases the suspension load on the pumping unit; if wax deposition also exists on the tubing walls, this alternating load increases the risk of sucker rod breakage, and in more severe cases, can lead to wax jamming of the pumping unit. If wax deposition occurs at the pumping unit's inlet and outlet valves, it increases pump operating resistance and reduces pump efficiency. If wax deposition occurs within the formation, the porosity and permeability around the wax deposition decrease, increasing fluid flow resistance and causing reduced or halted well production.

[0003] Chemical paraffin removal technology is widely used due to its advantages such as rapid onset of action, thorough paraffin removal, simple operation, and no impact on normal oil well production. Generally speaking, chemical paraffin removal technology is based on two mechanisms: first, using one or more agents to form a polar film on the metal surface to affect the wettability of the metal surface, thereby reducing paraffin deposition; second, using one or more agents to change the structure of paraffin crystals or to disperse the paraffin crystals, thereby suspending them in the crude oil.

[0004] CN116355602A discloses a high-efficiency wax remover and its preparation method. The preparation method includes mixing methyl isobutylene oxide, dodecylbenzene sulfonic acid, acrylic acid, and phenolic resin in an alkaline solution and reacting them to obtain the wax remover. This wax remover is a polymer-type wax remover with strong polar groups, a low freezing point, high wax removal speed, and good viscosity reduction effect. However, the wax remover prepared by this method produces many byproducts and has poor wax-preventing effect.

[0005] Polymer-based wax removers, also known as wax crystal modifiers, are mostly oil-soluble comb-like polymers. These polymers have side chains of a certain length, and their main chain or side chains possess structures and polar groups similar to paraffin molecules. At lower temperatures, the paraffin-like structures in the polymer molecules form eutectic crystals with the paraffin molecules. Because the polymer molecules also contain polar groups, the resulting crystal nuclei are distorted and deformed, hindering further wax crystal growth.

[0006] However, existing wax removal and prevention agents are often not very targeted, resulting in short wax removal cycles for some oil wells. They also have the problem of low wax removal and prevention efficiency, and the wax removal and prevention effects often cannot be achieved simultaneously. Moreover, they may have low flash points and high pour points, making them unsuitable for low-temperature environments. Summary of the Invention

[0007] To address at least one of the aforementioned technical problems, the present invention aims to provide an alkylacrylamide-imide-quaternary ammonium salt polymer, as well as a wax remover and wax inhibitor and its preparation method. The wax remover and wax inhibitor of the present invention achieves both superior wax removal and wax inhibitor effects, and has a wide applicable temperature range.

[0008] To achieve the above objectives, a first aspect of the present invention provides an alkylacrylamide-imide-quaternary ammonium salt polymer containing structural units of Formula I, Formula II, and Formula III:

[0009]

[0010] Wherein, R1 is selected from hydrogen atoms or C1-C3 alkyl groups; R2 is selected from groups containing quaternary ammonium salts; R3 is selected from hydrogen atoms or C1-C3 alkyl groups; R4 is selected from C4-C6 alkyl groups. 24 R5 is selected from hydrogen atoms or C1-C3 alkyl groups; R6 is selected from groups containing the imide structure shown in Formula IV.

[0011] According to a specific embodiment of the present invention, preferably, R2 is selected from one of the following groups: Among them, X - It is selected from one of the halide ions.

[0012] According to a specific embodiment of the present invention, preferably, R6 is selected from one of the following groups:

[0013]

[0014] According to a specific embodiment of the present invention, preferably, R4 is selected from C. 10 ~C 24 Alkyl groups.

[0015] A second aspect of the present invention provides a method for preparing a wax-removing agent, comprising the following steps:

[0016] (1) An acyl halide compound containing an alkenyl group, an acid anhydride containing an alkenyl group, and a quaternary ammonium salt containing an alkenyl group are reacted in an organic solvent and in the presence of an initiator to obtain a first mixture system;

[0017] (2) The first mixture system and the long-chain alkyl primary amine are subjected to a second reaction in the presence of an acid-binding agent to obtain the wax-removing agent.

[0018] According to a specific embodiment of the present invention, preferably, the alkenyl-containing acyl halide compound includes one or more of acryloyl chloride, methacryloyl chloride, 2-ethylacryloyl chloride, and 2-propylacryloyl chloride.

[0019] According to a specific embodiment of the present invention, preferably, the alkenyl-containing acid anhydride includes one or more of 1,2,5,6-tetrahydrophthalic anhydride, norbornene anhydride, maleic anhydride, methyl maleic anhydride, ethyl maleic anhydride, and n-propyl maleic anhydride.

[0020] According to a specific embodiment of the present invention, preferably, the alkenyl-containing quaternary ammonium salt includes one or more of methacryloyloxyethyltrimethylammonium halide, allyltrimethylammonium halide, benzylvinyltrimethylammonium halide, (3-acrylamidopropyl)trimethylammonium halide, and halogenated-1-vinyl-3-methyl-1H-imidazolium.

[0021] According to a specific embodiment of the present invention, preferably, the molar ratio of the alkenyl-containing acyl halide compound, the alkenyl-containing acid anhydride, and the alkenyl-containing quaternary ammonium salt is 1:(1-1.5):(0.2-0.5).

[0022] According to a specific embodiment of the present invention, preferably, the initiator includes one or more of azo initiators and peroxide initiators.

[0023] According to a specific embodiment of the present invention, preferably, the amount of the initiator is 1 to 5% of the total molar amount of the alkenyl-containing acyl halide compound, the alkenyl-containing acid anhydride, and the alkenyl-containing quaternary ammonium salt.

[0024] According to a specific embodiment of the present invention, preferably, the temperature of the first reaction is 80-150°C and the time is 1-5 hours.

[0025] According to a specific embodiment of the present invention, preferably, the long-chain alkyl group in the long-chain alkyl primary amine has 4 to 24 carbon atoms. More preferably, the long-chain alkyl group in the long-chain primary amine has 10 to 24 carbon atoms. Even more preferably, the long-chain alkyl primary amine includes one or more of dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, eicosamine, docosamine, and docosamine.

[0026] According to a specific embodiment of the present invention, preferably, the molar ratio of the total amount of the long-chain alkyl primary amine, the alkenyl-containing acyl halide compound, and the alkenyl-containing acid anhydride is (0.8-1.2):1.

[0027] According to a specific embodiment of the present invention, preferably, the acid-binding agent comprises one or more of organic basic compounds and inorganic basic compounds. More preferably, the acid-binding agent comprises one or more of triethylamine, pyridine, N,N-diisopropylethylamine, sodium carbonate, potassium carbonate, and sodium acetate.

[0028] According to a specific embodiment of the present invention, preferably, the molar ratio of the acid-binding agent to the alkenyl acyl halide compound is (1-1.5):1.

[0029] According to a specific embodiment of the present invention, preferably, the temperature of the second reaction is 80-140°C and the time is 4-12 hours.

[0030] The third aspect of the present invention provides a wax remover, which is prepared by the above-described method for preparing wax removers.

[0031] According to a specific embodiment of the present invention, preferably, the dewaxing agent comprises the above-mentioned alkylacrylamide-imide-quaternary ammonium salt polymer.

[0032] The present invention has at least the following beneficial effects:

[0033] The alkylacrylamide-imide-quaternary ammonium salt polymer of the present invention contains multiple groups, and through the synergistic effect between these groups, it achieves both excellent dewaxing and anti-waxing effects. Furthermore, the alkylacrylamide-imide-quaternary ammonium salt polymer and the dewaxing and anti-waxing agent of the present invention have the advantage of low pour point and a wide applicable temperature range. Moreover, the alkylacrylamide-imide-quaternary ammonium salt polymer and the dewaxing and anti-waxing agent of the present invention have a good ability to lower the pour point of crude oil. Attached Figure Description

[0034] Figure 1 The image shows the infrared spectrum of the wax remover from Example 1. Detailed Implementation

[0035] To provide a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the present invention will now be described in detail below, but this should not be construed as limiting the scope of the invention.

[0036] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these 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 in this invention.

[0037] It should be noted that, unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0038] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0039] According to a specific embodiment of the first aspect of the present invention, the present invention provides an alkylacrylamide-imide-quaternary ammonium salt polymer containing structural units represented by Formula I, Formula II and Formula III:

[0040] Wherein, R1 is selected from hydrogen atoms or C1-C3 alkyl groups; R2 is selected from groups containing quaternary ammonium salts; R3 is selected from hydrogen atoms or C1-C3 alkyl groups; R4 is selected from C4-C6 alkyl groups. 24 R5 is selected from hydrogen atoms or C1-C3 alkyl groups; R6 is selected from groups containing the imide structure shown in Formula IV.

[0041] In some embodiments, R1, R3, and R5 are each independently selected from hydrogen atoms or methyl groups.

[0042] In some embodiments, R2 is selected from one of the following groups: Among them, X - Selected from one of the halide ions. Preferably, X - For Cl - .

[0043] In some embodiments, R6 is selected from one of the following groups:

[0044] In some embodiments, R4 is selected from C. 10 ~C 24 Alkyl group. Preferably, R4 is selected from C4. 10 ~C 24 Straight-chain alkyl groups.

[0045] In some embodiments, the molar ratio of the structural unit shown in Formula I, the structural unit shown in Formula II, and the structural unit shown in Formula III is (0.2-0.5):1:(1-1.5).

[0046] According to a specific embodiment of a second aspect of the present invention, the present invention provides a method for preparing a wax-removing agent, which includes the following steps:

[0047] (1) An acyl halide compound containing an alkenyl group, an acid anhydride containing an alkenyl group, and a quaternary ammonium salt containing an alkenyl group are reacted in an organic solvent and in the presence of an initiator to obtain a first mixture system;

[0048] (2) The first mixture system and the long-chain alkyl primary amine are subjected to a second reaction in the presence of an acid-binding agent to obtain the wax-removing agent.

[0049] In this invention, step (1) prepares an acrylamide halide-anhydride-quaternary ammonium salt polymer, and step (2) involves reacting a long-chain alkyl primary amine with the acrylamide halide and anhydride structures in the polymer. Compared to the carboxyl group, the acrylamide halide structure exhibits stronger reactivity with the long-chain alkyl primary amine, thus preparing the alkylacrylamide-imide-quaternary ammonium salt polymer. This invention, through a preparation step of copolymerization followed by side-chain modification, yields an alkylacrylamide-imide-quaternary ammonium salt polymer containing multiple functional groups. Through the synergistic effect between these groups, it achieves both good wax removal and wax prevention effects, making it suitable as a wax removal and wax prevention agent.

[0050] In some embodiments, the alkenyl-containing acyl halide compound includes one or more of acryloyl chloride, methacryloyl chloride, 2-ethylacryloyl chloride, and 2-propylacryloyl chloride. Preferably, the alkenyl-containing acyl halide compound includes one or more of acryloyl chloride and methacryloyl chloride. The alkenyl-containing acyl halide compound can be prepared by the following steps: mixing an acrylic acid compound and an acyl chloride reagent in a molar ratio of 1:(2-5) and reacting them to obtain the alkenyl-containing acyl halide compound. The acrylic acid compound includes one or more of acrylic acid, methacrylic acid, 2-ethylacrylic acid, and 2-propylacrylic acid. The acyl chloride reagent preferably includes one or more of oxaloyl chloride, sulfoxide, and phosphorus trichloride.

[0051] In some embodiments, the alkenyl-containing anhydride includes one or more of 1,2,5,6-tetrahydrophthalic anhydride, norbornene, maleic anhydride, methyl maleic anhydride, citrate anhydride, ethyl maleic anhydride, and n-propyl maleic anhydride. Preferably, the alkenyl-containing anhydride includes one or more of 1,2,5,6-tetrahydrophthalic anhydride, norbornene, maleic anhydride, and methyl maleic anhydride.

[0052] In some embodiments, the alkenyl-containing quaternary ammonium salt includes one or more of methacryloyloxyethyltrimethylammonium halide, allyltrimethylammonium halide, benzylvinyltrimethylammonium halide, (3-acrylamidopropyl)trimethylammonium halide, and 1-vinyl-3-methyl-1H-imidazole halide. Preferably, the alkenyl-containing quaternary ammonium salt includes one or more of methacryloyloxyethyltrimethylammonium chloride, allyltrimethylammonium chloride, benzylvinyltrimethylammonium chloride, (3-acrylamidopropyl)trimethylammonium chloride, and 1-vinyl-3-methyl-1H-imidazole chloride.

[0053] In some embodiments, the molar ratio of the alkenyl-containing acyl halide compound, the alkenyl-containing acid anhydride, and the alkenyl-containing quaternary ammonium salt is 1:(1-1.5):(0.2-0.5), preferably 1:(1.1-1.2):(0.2-0.3).

[0054] In some embodiments, the initiator includes one or more of azo initiators and peroxide initiators. Preferably, the initiator includes one or more of azobisisobutyronitrile, benzoyl peroxide, cumene hydroperoxide, tert-butyl peroxide, and diisopropyl peroxide.

[0055] In some embodiments, the amount of the initiator is 1 to 5% of the total molar amount of the alkenyl-containing acyl halide compound, the alkenyl-containing acid anhydride, and the alkenyl-containing quaternary ammonium salt.

[0056] In some embodiments, the organic solvent includes one or more of toluene, xylene, trimethylbenzene, naphtha, solvent oil, and C9 aromatics.

[0057] In some embodiments, the temperature of the first reaction is 80–150°C and the time is 1–5 h.

[0058] In some embodiments, the long-chain alkyl group in the long-chain alkyl primary amine has 4 to 24 carbon atoms. Preferably, the long-chain alkyl group in the long-chain alkyl primary amine has 10 to 24 carbon atoms. More preferably, the long-chain alkyl primary amine includes one or more of dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, eicosamine, docosamine, and docosamine.

[0059] In some embodiments, the molar ratio of the long-chain alkyl primary amine to the total amount of the alkenyl-containing acyl halide compound and the alkenyl-containing acid anhydride is (0.8–1.2):1.

[0060] In some embodiments, the acid-binding agent comprises one or more of organic basic compounds and inorganic basic compounds. Preferably, the acid-binding agent comprises one or more of triethylamine, pyridine, N,N-diisopropylethylamine, sodium carbonate, potassium carbonate, and sodium acetate.

[0061] In some embodiments, the molar ratio of the acid-binding agent to the alkenyl acyl halide compound is (1 to 1.5):1.

[0062] In some embodiments, the temperature of the second reaction is 80–140°C and the time is 4–12 h.

[0063] According to a specific embodiment of the third aspect of the present invention, the present invention provides a wax remover / preventive agent, which is prepared by the above-described method for preparing a wax remover / preventive agent.

[0064] In some embodiments, the wax remover comprises the aforementioned alkylacrylamide-imide-quaternary ammonium salt polymer.

[0065] It should be noted that the preparation method of the alkylacrylamide-imide-quaternary ammonium salt polymer of the present invention is the same as the preparation method of the above-mentioned dewaxing agent. Those skilled in the art will understand that the dewaxing agent obtained by the above preparation method is a mixture, and the alkylacrylamide-imide-quaternary ammonium salt polymer of the present invention can be obtained after conventional purification steps.

[0066] The present invention also provides the application of the above-mentioned alkylacrylamide-imide-quaternary ammonium salt polymer or the above-mentioned dewaxing and anti-waxing agent in oil extraction.

[0067] In some embodiments, the application is carried out by adding the alkylacrylamide-imide-quaternary ammonium salt polymer or the dewaxing agent to oil extraction equipment. Specifically, the alkylacrylamide-imide-quaternary ammonium salt polymer or the dewaxing agent can be added to the equipment alone or mixed with an organic solvent before being added to the equipment. The organic solvent may include one or more of toluene, xylene, trimethylbenzene, solvent oil, naphtha, kerosene, C9 aromatics, mixed aromatics, diesel oil, and gasoline. The mixing mass ratio of the alkylacrylamide-imide-quaternary ammonium salt polymer or the dewaxing agent to the organic solvent may be (1-3):(1-10). The oil extraction equipment may include, for example, oil wells, pipelines, downhole equipment, and pumping units.

[0068] The alkylacrylamide-imide-quaternary ammonium salt polymer of the present invention contains multiple groups, and through the synergistic effect of these groups, it achieves both good wax removal and wax prevention effects. Specifically, the alkylacrylamide-imide-quaternary ammonium salt polymer of the present invention contains a long alkyl chain comb-like structure. The long alkyl chain can form a eutectic with paraffin molecules or adsorb paraffin crystals, dispersing the paraffin crystals in the fluid, inhibiting the aggregation and growth of paraffin crystals, and dissolving and adsorbing crystallized paraffin, thus exhibiting good wax removal and wax prevention effects. Furthermore, the alkylacrylamide-imide-quaternary ammonium salt polymer of the present invention contains hydrophilic groups such as imide structures. When the long alkyl chain comb-like structure is adsorbed onto paraffin crystals, the hydrophilic groups are exposed on the surface of the paraffin crystals, thereby changing the surface wettability of the paraffin crystals and inhibiting further crystallization and growth. At the same time, the imide structure in the alkylacrylamide-imide-quaternary ammonium salt polymer of the present invention can also improve the rigidity and stability of the polymer, helping the polymer to continuously exert its wax removal and wax prevention effects. Moreover, the presence of the imide structure can also change the spatial conformation of the polymer molecules, which is beneficial for the polymer to adsorb onto the surface of paraffin crystals. Furthermore, the alkylacrylamide-imide-quaternary ammonium salt polymer of the present invention contains quaternary ammonium salt groups, which can reduce the surface tension between paraffin crystals and crude oil, and improve the dispersibility of paraffin in crude oil. Simultaneously, the cations of the quaternary ammonium salt groups can also enhance the polymer's adsorption on the negatively charged surface of paraffin crystals, further inhibiting the aggregation and growth of paraffin crystals. Additionally, for already deposited paraffin, the quaternary ammonium salt groups in the polymer of the present invention can penetrate between the paraffin and the equipment surface, reducing the adhesion between them; simultaneously, the long alkyl chain comb-like structure and imide structure in the polymer can interact with the paraffin, peeling the paraffin off the equipment surface.

[0069] Furthermore, the alkylacrylamide-imide-quaternary ammonium salt polymer of the present invention has a good ability to lower the pour point of crude oil. Specifically, because the alkylacrylamide-imide-quaternary ammonium salt polymer of the present invention has a structure and groups similar to paraffin molecules, it has good solubility in crude oil. The long alkyl chains in the polymer interact with paraffin molecules in the crude oil, causing the long alkyl chains to extend and adsorb paraffin crystals, thereby increasing the fluidity of the crude oil. At the same time, the quaternary ammonium salt groups in the polymer can reduce the surface tension between paraffin crystals and crude oil, thereby reducing the flow resistance of crude oil.

[0070] In addition, the alkylacrylamide-imide-quaternary ammonium salt polymer of the present invention has the advantages of low freezing point and high flash point, and its applicable temperature range is relatively wide.

[0071] The technical solutions of the present invention are specifically illustrated below through embodiments, but the present invention is not limited to these embodiments. Of course, various modifications can be made within the scope of the key points of the present invention.

[0072] Test method:

[0073] The structure of the alkylacrylamide-imide-quaternary ammonium salt polymer was determined using a Thermo Nicoleti S20 Fourier transform infrared spectrometer. Test conditions included a scan range of 4000-400 cm⁻¹. -1 The number of scans was 32, and the resolution was 4cm. -1 Background acquisition mode. Preparation method of test sample: The product obtained in the following examples is mixed with potassium bromide powder at a mass ratio of 1:100, and then compressed into tablets to obtain the test sample.

[0074] Example 1

[0075] 1 mol of acrylic acid was added to a three-necked flask, and then 2 mol of thionyl chloride was added dropwise to the flask under ice bath conditions. After the addition was complete, the temperature was raised to 60°C and the reaction was carried out for 2 hours. After the reaction was completed, the mixture was distilled to obtain acryloyl chloride. Then, 1 mol of acryloyl chloride, 1.1 mol of 1,2,5,6-tetrahydrophthalic anhydride and 0.2 mol of methacryloyloxyethyltrimethylammonium chloride were added to xylene and mixed evenly. Then, 0.05 mol of tert-butyl peroxide was added, and the temperature was raised to 135°C and the reaction was carried out for 5 hours to obtain the first mixture. Then, 2 mol of tetratetramine and 1 mol of triethylamine were added to the first mixture and mixed evenly. The mixture was then reacted at 140°C for 4 hours to obtain the wax remover.

[0076] The infrared spectrum of the wax remover prepared in this embodiment is shown below. Figure 1 As shown.

[0077] Depend on Figure 1 It can be seen that 3344cm -1 The absorption peak at 2925 cm⁻¹ is attributed to the stretching vibration peak of NH₃. -1 2852cm -1 The absorption peak at 1658 cm⁻¹ is attributed to both the antisymmetric and symmetric stretching vibrations of CH₄. -1 The absorption peak at 1465 cm⁻¹ is attributed to the stretching vibration of the carbonyl C=O group. -1 The absorption peak at 1378 cm⁻¹ is attributed to the bending vibration of the alkyl chain -CH₂-. -1 The absorption peak at 1258 cm⁻¹ is attributed to the CN stretching vibration peak of the amide II band and the imide ring. -1 The absorption peak at 1099 cm⁻¹ is attributed to the stretching vibration peak of COC. -1 The absorption peak at that point is attributed to the stretching vibration peak of C.

[0078] Therefore, the wax remover prepared in this embodiment comprises an alkylacrylamide-imide-quaternary ammonium salt polymer, which includes the following structural units:

[0079]

[0080] Example 2

[0081] 1 mol of methacrylic acid was added to a three-necked flask, and then 2 mol of oxaloyl chloride was added dropwise to the flask under ice bath conditions. After the addition was complete, the temperature was raised to 60°C and the reaction was carried out for 2 hours. After the reaction was completed, the mixture was distilled to obtain methacryloyl chloride. Then, 1 mol of methacryloyl chloride, 1.1 mol of 1,2,5,6-tetrahydrophthalic anhydride and 0.2 mol of allyltrimethylammonium chloride were added to xylene and mixed thoroughly. Then, 0.05 mol of tert-butyl peroxide was added, and the temperature was raised to 135°C and the reaction was carried out for 4 hours to obtain the first mixture. Then, 2 mol of octadecylamine and 1 mol of pyridine were added to the first mixture and mixed thoroughly. The mixture was then reacted at 135°C for 6 hours to obtain the wax remover.

[0082] The infrared spectrum of the wax remover prepared in this embodiment was tested, and the results are as follows: 3345 cm⁻¹ -1 The absorption peak at 2920 cm⁻¹ is attributed to the stretching vibration peak of NH₃. -1 2850cm -1 The absorption peak at 1660 cm⁻¹ is attributed to both the antisymmetric and symmetric stretching vibrations of CH₄. -1 The absorption peak at 1465 cm⁻¹ is attributed to the stretching vibration of the carbonyl C=O group. -1 The absorption peak at 1379 cm⁻¹ is attributed to the bending vibration of the alkyl chain -CH₂-. -1 The absorption peak at 1098 cm⁻¹ is attributed to the CN stretching vibration peak of the amide II band and the imide ring. -1 The absorption peak at that point is attributed to the stretching vibration peak of C.

[0083] Therefore, the wax remover prepared in this embodiment comprises an alkylacrylamide-imide-quaternary ammonium salt polymer, which includes the following structural units:

[0084]

[0085] Example 3

[0086] 1 mol of acrylic acid was added to a three-necked flask, and then 2 mol of phosphorus trichloride was added dropwise to the flask under ice bath conditions. After the addition was complete, the temperature was raised to 60°C and the reaction was carried out for 2 hours. After the reaction was completed, the mixture was distilled to obtain acryloyl chloride. Then, 1 mol of acryloyl chloride, 1.1 mol of maleic anhydride and 0.2 mol of benzylvinyltrimethylammonium chloride were added to xylene and mixed evenly. Then, 0.05 mol of tert-butyl peroxide was added, and the temperature was raised to 150°C and the reaction was carried out for 1 hour to obtain the first mixture. Then, 2 mol of octadecylamine and 1 mol of triethylamine were added to the first mixture and mixed evenly. The mixture was then reacted at 80°C for 12 hours to obtain the wax remover.

[0087] The infrared spectrum of the wax remover prepared in this embodiment was tested, and the results are as follows: 3342 cm⁻¹ -1 The absorption peak at 3100-3000 cm⁻¹ is attributed to the stretching vibration peak of NH. - The absorption peak at 1 is attributed to the stretching vibration of CH in the benzene ring; 2923 cm⁻¹ -1 2851cm -1 The absorption peak at 1655 cm⁻¹ is attributed to both the antisymmetric and symmetric stretching vibrations of CH. -1 The absorption peak at 1600 cm⁻¹ is attributed to the stretching vibration of the carbonyl C=O group. - 1 around and 1500cm - The absorption peak around 1 cm⁻¹ is attributed to the stretching vibration of the C=C skeleton of the benzene ring; 1465 cm⁻¹ -1 The absorption peak at 1376 cm⁻¹ is attributed to the bending vibration of the alkyl chain -CH₂-. -1 The absorption peak at 1097 cm⁻¹ is attributed to the CN stretching vibration peak of the amide II band and the imide ring. -1 The absorption peak at that point is attributed to the stretching vibration peak of C.

[0088] Therefore, the wax remover prepared in this embodiment comprises an alkylacrylamide-imide-quaternary ammonium salt polymer, which includes the following structural units:

[0089]

[0090] Example 4

[0091] 1 mol of acrylic acid was added to a three-necked flask, and then 2 mol of thionyl chloride was added dropwise to the flask under ice bath conditions. After the addition was complete, the temperature was raised to 60°C and the reaction was carried out for 2 hours. After the reaction was completed, the mixture was distilled to obtain acryloyl chloride. Then, 1 mol of acryloyl chloride, 1.5 mol of 1,2,5,6-tetrahydrophthalic anhydride and 0.2 mol of methacryloyloxyethyltrimethylammonium chloride were added to xylene and mixed thoroughly. Then, 0.05 mol of tert-butyl peroxide was added, and the temperature was raised to 135°C and the reaction was carried out for 5 hours to obtain the first mixture. Then, 2 mol of tetratetramine and 1 mol of triethylamine were added to the first mixture and mixed thoroughly. The mixture was then reacted at 140°C for 4 hours to obtain the wax remover.

[0092] Example 5

[0093] 1 mol of acrylic acid was added to a three-necked flask, and then 2 mol of thionyl chloride was added dropwise to the flask under ice bath conditions. After the addition was complete, the temperature was raised to 60°C and the reaction was carried out for 2 hours. After the reaction was completed, the mixture was distilled to obtain acryloyl chloride. Then, 1 mol of acryloyl chloride, 1.1 mol of 1,2,5,6-tetrahydrophthalic anhydride and 0.5 mol of methacryloyloxyethyltrimethylammonium chloride were added to xylene and mixed evenly. Then, 0.05 mol of tert-butyl peroxide was added, and the temperature was raised to 135°C and the reaction was carried out for 5 hours to obtain the first mixture. Then, 2 mol of tetratetramine and 1 mol of triethylamine were added to the first mixture and mixed evenly. The mixture was then reacted at 140°C for 4 hours to obtain the wax remover.

[0094] Comparative Example 1

[0095] 1 mol of methacrylic acid was added to a three-necked flask, and then 2 mol of oxaloyl chloride was added dropwise to the flask under ice bath conditions. After the addition was complete, the temperature was raised to 60°C and the reaction was carried out for 2 hours. After the reaction was completed, the mixture was distilled to obtain methacryloyl chloride. Then, 1 mol of methacryloyl chloride and 1.1 mol of 1,2,5,6-tetrahydrophthalic anhydride were added to xylene and mixed evenly. Then, 0.05 mol of tert-butyl peroxide was added, and the temperature was raised to 135°C and the reaction was carried out for 4 hours to obtain the first mixture. Then, 2 mol of octadecylamine and 1 mol of pyridine were added to the first mixture and mixed evenly. The mixture was then reacted at 135°C for 6 hours to obtain the wax remover.

[0096] This comparative example is basically the same as Example 2, except that allyltrimethylammonium chloride was not added.

[0097] Comparative Example 2

[0098] 1 mol of methacrylic acid, 1.1 mol of 1,2,5,6-tetrahydrophthalic anhydride and 0.2 mol of allyltrimethylammonium chloride were added to xylene and mixed thoroughly. Then, 0.05 mol of tert-butyl peroxide was added, and the mixture was heated to 135 °C and reacted for 4 h to obtain the first mixture system. Then, 2 mol of octadecylamine and 1 mol of pyridine were added to the first mixture system, mixed thoroughly, and reacted at 135 °C for 6 h to obtain the wax remover.

[0099] This comparative example is basically the same as Example 2, except that methacrylic acid is used instead of methacryloyl chloride for the reaction.

[0100] Comparative Example 3

[0101] 1.1 mol of 1,2,5,6-tetrahydrophthalic anhydride and 0.2 mol of allyltrimethylammonium chloride were added to xylene and mixed thoroughly. Then, 0.05 mol of tert-butyl peroxide was added, and the mixture was heated to 135 °C and reacted for 4 h to obtain the first mixture system. Then, 2 mol of octadecylamine and 1 mol of pyridine were added to the first mixture system, mixed thoroughly, and reacted at 135 °C for 6 h to obtain the wax remover.

[0102] This comparative example is basically the same as Example 2, except that methacryloyl chloride was not added.

[0103] Comparative Example 4

[0104] 1 mol of methacrylic acid was added to a three-necked flask, and then 2 mol of oxaloyl chloride was added dropwise to the flask under ice bath conditions. After the addition was complete, the temperature was raised to 60°C and the reaction was carried out for 2 hours. After the reaction was completed, the mixture was distilled to obtain methacryloyl chloride. Then, 1 mol of methacryloyl chloride and 0.2 mol of allyltrimethylammonium chloride were added to xylene and mixed evenly. Then, 0.05 mol of tert-butyl peroxide was added, and the temperature was raised to 135°C and the reaction was carried out for 4 hours to obtain the first mixture. Then, 2 mol of octadecylamine and 1 mol of pyridine were added to the first mixture and mixed evenly. The mixture was then reacted at 135°C for 6 hours to obtain the wax remover.

[0105] This comparative example is basically the same as Example 2, except that 1,2,5,6-tetrahydrophthalic anhydride was not added.

[0106] Comparative Example 5

[0107] 1 mol of methacrylic acid was added to a three-necked flask, and then 2 mol of oxaloyl chloride was added dropwise to the flask under ice bath conditions. After the addition was complete, the temperature was raised to 60°C and the reaction was carried out for 2 hours. After the reaction was completed, the mixture was distilled to obtain methacryloyl chloride. Then, 1 mol of methacryloyl chloride, 1.1 mol of 1,2,5,6-tetrahydrophthalic anhydride and 0.2 mol of allyltrimethylammonium chloride were added to xylene. After mixing evenly, 0.05 mol of tert-butyl peroxide was added, and the temperature was raised to 135°C and the reaction was carried out for 4 hours to obtain a wax remover.

[0108] This comparative example is basically the same as Example 2, except that octadecylamine was not used for side chain modification.

[0109] Comparative Example 6

[0110] 1 mol of methacrylic acid was added to a three-necked flask, and then 2 mol of oxaloyl chloride was added dropwise to the flask under ice bath conditions. After the addition was complete, the temperature was raised to 60°C and the reaction was carried out for 2 hours. After the reaction was completed, the mixture was distilled to obtain methacryloyl chloride. Then, 1 mol of methacryloyl chloride, 1.1 mol of 1,2,5,6-tetrahydrophthalic anhydride, 0.2 mol of allyltrimethylammonium chloride, 2 mol of octadecylamine, and 1 mol of pyridine were added to xylene. After mixing evenly, 0.05 mol of tert-butyl peroxide was added, and the temperature was raised to 135°C and the reaction was carried out for 6 hours to obtain a wax remover.

[0111] This comparative example is basically the same as Example 2, except that: instead of using the preparation steps of first copolymerization and then side chain modification, all raw materials are mixed and reacted.

[0112] Comparative Example 7

[0113] This comparative example provides a commercially available wax remover (Basoflux RD5119T).

[0114] Test Example 1

[0115] The wax-dissolving and wax-preventing properties of the wax-removing and wax-preventing agents of the above embodiments and comparative examples were tested.

[0116] The testing methods include:

[0117] Wax dissolution rate test: (1) Take paraffin samples from the site to prepare paraffin balls, and weigh the mass of the paraffin balls accurately to 0.0001g using a high-precision electronic balance; (2) Measure 15mL of wax remover and add it to a 50mL stoppered colorimetric tube, and then place the stoppered colorimetric tube in a 45℃ constant temperature water bath for 15min; (3) Then weigh about 1g of paraffin balls and add them to the stoppered colorimetric tube containing the wax remover, and observe the dissolution of the paraffin balls. After the paraffin balls are completely dissolved, continue to add about 1g of paraffin balls; (4) The total time for adding paraffin balls and observing the wax dissolution is 4h. The total mass of the paraffin balls added within this time range (i.e., 4h) is recorded as m0. Then take out the undissolved paraffin balls, dry them in an oven, and weigh them accurately to 0.0001g. The mass of the undissolved paraffin balls after drying is recorded as m1. The wax melting rate is calculated using the following formula: wax melting rate = (m0-m1) / t, where t = 240 min (i.e. 4 h).

[0118] Wax-resistant test: (1) Immerse the strip (made of A3 steel sheet) in petroleum ether, wipe it three times with degreased cotton, rinse it with water, soak it in anhydrous ethanol for 5 minutes, dry it with a hair dryer, wrap it with filter paper and dry it in a desiccator until constant weight, and obtain a clean and dry strip. Record its mass to 0.0001g, and record it as m2; (2) Pour the crude oil (shale oil) on site into a beaker, add 1g of the agent, which is a wax-resistant agent solution with a mass concentration of 10% prepared with xylene as solvent. The concentration of the agent added to the crude oil is 1500mg / L. Then place the beaker in a constant temperature water bath at 50℃ and shake it well. Then place it in a room temperature environment (23±2℃) for 10 minutes to obtain a wax-resistant agent solution containing the wax-resistant agent. (3) Then hang the clean and dry strip on the iron frame, so that the strip is completely immersed in the crude oil containing the anti-wax agent; (4) After placing it in the room temperature environment (23±2℃) for 30 minutes, take out the strip and hang it on the iron frame. After the crude oil on the strip no longer flows, weigh it with a high-precision electronic balance and record it as m3; (5) Hang the clean and dry strip on the iron frame, so that the strip is completely immersed in the crude oil on site (i.e., crude oil without anti-wax agent). The volume of crude oil is the same as the volume of crude oil containing anti-wax agent. After placing it in the room temperature environment (23±2℃) for 30 minutes, take out the strip and hang it on the iron frame. After the crude oil on the strip no longer flows, weigh it with a high-precision electronic balance and record it as m4. The anti-wax rate is calculated using the following formula: Anti-wax rate (%) = (m4-m3) / (m4-m2)×100%.

[0119] The test results are shown in Table 1.

[0120] Table 1. Test results of wax dissolving and wax resisting properties

[0121] project Dosage concentration (mg / L) Wax melting rate (g / min) Wax resistance rate (%) Example 1 1500 0.036 84.9 Example 2 1500 0.032 81.5 Example 3 1500 0.030 74.1 Example 4 1500 0.028 83.2 Example 5 1500 0.034 72.3 Comparative Example 1 1500 0.021 45.2 Comparative Example 2 1500 0.016 52..9 Comparative Example 3 1500 0.018 58.4 Comparative Example 4 1500 0.019 53.2 Comparative Example 5 1500 0.012 18.0 Comparative Example 6 1500 0.017 43.5 Comparative Example 7 1500 0.016 23.5

[0122] It should be noted that the dosage of the reagent in Table 1 is for the test of the anti-wax rate, while the test of the wax dissolution rate does not involve the dosage of the reagent.

[0123] As can be seen from Table 1, the wax removal and wax prevention effects of the embodiments of the present invention are significantly better than those of the comparative examples. The wax removal and wax prevention agents of the embodiments of the present invention include alkylacrylamide-imide-quaternary ammonium salt polymers, which contain multiple groups. Through the synergistic effect between these multiple groups, they achieve both better wax removal and wax prevention effects.

[0124] Test Example 2

[0125] The pour points of the wax-removing agents in the above examples and comparative examples were tested according to GB / T 510-2018 "Determination of Pour Point of Petroleum Products" using a manual pour point tester. The flash points of the wax-removing agents in the above examples and comparative examples were tested according to GB / T 261-2008 "Determination of Flash Point - Binsky-Martin Closed Cup Method". The test results are shown in Table 2.

[0126] Table 2. Results of Pour Point and Flash Point Tests for Wax Remover

[0127]

[0128]

[0129] As can be seen from Table 2, the freezing point of the wax remover in each embodiment of the present invention is less than -20℃ and the flash point is greater than 40℃. It has the advantages of low freezing point and high flash point and has a wide applicable temperature range.

[0130] Test Example 3

[0131] The dewaxing properties of the wax-reducing agents in the above embodiments and comparative examples were tested.

[0132] The test method includes testing the pour point of crude oil before and after adding the anti-wax agent, according to the description in SY / T 0541-1994 "Crude Oil Pour Point Test Method". Specifically, for the anti-wax agent in Example 1, four portions of crude oil from different blocks were taken and mixed evenly with the anti-wax agent at a mass ratio of 9:1 (crude oil to anti-wax agent). The mixture was then poured into test tubes, heated to 60°C, and cooled at a rate of 0.5°C / min. The fluidity of the sample was observed every 2.0°C until the sample stopped flowing after the test tube was placed horizontally for 5 seconds. This temperature was taken as the pour point of the crude oil. The pour point of crude oil without the anti-wax agent was also tested using the same method. For the anti-wax agents in other examples and comparative examples, one portion of crude oil (i.e., crude oil 1 in the table below) was used for testing. The pour point reduction rate was calculated using the following formula: Pour point reduction rate (%) = (Crude oil pour point - Crude oil pour point after adding anti-wax agent) ÷ Crude oil pour point × 100%.

[0133] The test results are shown in Tables 3 and 4.

[0134] Table 3. Results of pour point depressing performance test in Example 1

[0135] Crude oil pour point (°C) Pour point (°C) of crude oil after adding anti-wax agent Pour point depressant (%) Crude oil 1 22.0 7.1 67.1 Crude oil 2 20.2 8.3 58.9 Crude oil 3 18..0 6.5 63.4 Crude oil 4 24.0 8.9 62.9

[0136] Table 4. Results of pour point depressing performance tests for Examples 2-5 and Comparative Examples 1-7

[0137]

[0138]

[0139] As can be seen from Tables 3 and 4, the wax-removing agent of Example 1 can reduce the pour point of crude oil from 22.0℃ to 7.1℃, with a pour point reduction rate of 67%, demonstrating a significant ability to lower the pour point of crude oil. The pour point reduction performance of the wax-removing agents in each embodiment of the present invention is significantly better than that of the comparative examples.

[0140] In summary, the alkylacrylamide-imide-quaternary ammonium salt polymer and the wax remover / preventer containing it of the present invention have both good wax removal and wax prevention effects; moreover, they have the advantages of low pour point and high flash point, and are applicable to a wide range of temperatures; at the same time, they have a good ability to lower the pour point of crude oil.

[0141] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An alkylacrylamide-imide-quaternary ammonium salt polymer, comprising structural units shown in Formula I, Formula II, and Formula III: in, R1 is selected from hydrogen atoms or C1-C3 alkyl groups; R2 is selected from groups containing quaternary ammonium salts; R3 is selected from hydrogen atoms or C1-C3 alkyl groups; R4 is selected from C4-C6 alkyl groups. 24 R5 is selected from hydrogen atoms or C1-C3 alkyl groups; R6 is selected from groups containing the imide structure shown in Formula IV.

2. The alkylacrylamide-imide-quaternary ammonium salt polymer according to claim 1, wherein, R2 is selected from one of the following groups: Among them, X - It is selected from one of the halide ions.

3. The alkylacrylamide-imide-quaternary ammonium salt polymer according to claim 1, wherein, R6 is selected from one of the following groups:

4. The alkylacrylamide-imide-quaternary ammonium salt polymer according to claim 1, wherein, R4 is selected from C 10 ~C 24 Alkyl groups.

5. A method for preparing a wax-removing agent, comprising the following steps: (1) An acyl halide compound containing an alkenyl group, an acid anhydride containing an alkenyl group, and a quaternary ammonium salt containing an alkenyl group are reacted in an organic solvent and in the presence of an initiator to obtain a first mixture system; (2) The first mixture system and the long-chain alkyl primary amine are subjected to a second reaction in the presence of an acid-binding agent to obtain the wax-removing agent.

6. The method for preparing the wax remover according to claim 5, wherein, The alkenyl-containing acyl halide compounds include one or more of acryloyl chloride, methacryloyl chloride, 2-ethylacryloyl chloride, and 2-propylacryloyl chloride.

7. The method for preparing the wax remover according to claim 5, wherein, The alkenyl-containing anhydrides include one or more of 1,2,5,6-tetrahydrophthalic anhydride, norbornene anhydride, maleic anhydride, methyl maleic anhydride, ethyl maleic anhydride, and n-propyl maleic anhydride.

8. The method for preparing the wax remover according to claim 5, wherein, The alkenyl-containing quaternary ammonium salt includes one or more of methacryloyloxyethyltrimethylammonium halide, allyltrimethylammonium halide, benzylvinyltrimethylammonium halide, (3-acrylamidopropyl)trimethylammonium halide, and halogenated-1-vinyl-3-methyl-1H-imidazolium.

9. The method for preparing the wax remover according to claim 5, wherein, The molar ratio of the alkenyl-containing acyl halide, the alkenyl-containing acid anhydride, and the alkenyl-containing quaternary ammonium salt is 1:(1-1.5):(0.2-0.5).

10. The method for preparing the wax-removing agent according to claim 5, wherein, The initiator includes one or more of azo initiators and peroxide initiators.

11. The method for preparing the wax-removing agent according to claim 5, wherein, The amount of the initiator is 1 to 5% of the total molar amount of the alkenyl-containing acyl halide compound, the alkenyl-containing acid anhydride, and the alkenyl-containing quaternary ammonium salt.

12. The method for preparing the wax-removing agent according to claim 5, wherein, The temperature of the first reaction is 80–150°C and the time is 1–5 hours.

13. The method for preparing the wax-removing agent according to claim 5, wherein, The long-chain alkyl group in the long-chain alkyl primary amine has 4 to 24 carbon atoms.

14. The method for preparing the wax-removing agent according to claim 13, wherein, The long-chain alkyl group in the long-chain alkyl primary amine has 10 to 24 carbon atoms.

15. The method for preparing the wax-removing agent according to claim 14, wherein, The long-chain alkyl primary amines include one or more of dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, eicosamine, dodecylamine, and dodecylamine.

16. The method for preparing the wax-removing agent according to claim 5, wherein, The molar ratio of the total amount of the long-chain alkyl primary amine, the alkenyl-containing acyl halide compound, and the alkenyl-containing acid anhydride is (0.8–1.2):

1.

17. The method for preparing the wax-removing agent according to claim 5, wherein, The acid-binding agent includes one or more of organic basic compounds and inorganic basic compounds.

18. The method for preparing the wax-removing agent according to claim 17, wherein, The acid-binding agent includes one or more of triethylamine, pyridine, N,N-diisopropylethylamine, sodium carbonate, potassium carbonate, and sodium acetate.

19. The method for preparing the wax-removing agent according to claim 5, wherein, The molar ratio of the acid-binding agent to the alkenyl acyl halide compound is (1-1.5):

1.

20. The method for preparing the wax-removing agent according to claim 5, wherein, The second reaction is carried out at a temperature of 80–140°C for 4–12 hours.

21. A wax remover, which is prepared by the method of any one of claims 5-20.

22. The wax remover according to claim 21, wherein, The cleaning and waxing agent comprises the alkylacrylamide-imide-quaternary ammonium salt polymer according to any one of claims 1-4.

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