Vinyl copolymer pour point depressant as well as preparation method and application thereof

Abstract

The invention discloses a vinyl copolymer pour point depressant as well as a preparation method and application thereof, and relates to the technical field of vinyl copolymer pour point depressants. Acrylamide, a methacrylate compound, a fumaric acid compound and alkyl coupling agent modified nano silicon dioxide are used as monomers, and the prepared copolymer pour point depressant has the characteristics and characteristic chemical bonds of copolymer macromolecules; due to the specific molecular chain and structure of the copolymer, the flexibility and flexibility variation range of copolymer molecules in the presence of dissolution or a solution is extremely large, crude oil can be quickly and effectively dispersed, the fluidity of the crude oil can be enhanced, blockage is reduced, and the oil production amount is increased; and the condensation point and the viscosity of crude oil can be obviously reduced under the condition of a very small amount (such as 500ppm).

Description

Technical Field

[0001] The invention relates to the technical field of vinyl copolymer pour point depressants, and in particular to a vinyl copolymer pour point depressant, a preparation method and application thereof. Background Art

[0002] Energy is a necessity for human survival and development, and petroleum processed from crude oil is an important part of human production and life. Therefore, the extraction, transportation and storage of crude oil are particularly important. However, the high wax content in crude oil will lead to its high freezing point and high viscosity, which in turn leads to problems such as difficulty in oil production, low efficiency and transportation. Pour point depressant is a commonly used additive in the process of crude oil extraction and transportation. By adding a small amount of pour point depressant, the pour point and viscosity of crude oil can be significantly reduced, and no special post-processing process is required. Compared with heating and dilution methods, the use of pour point depressant has the advantages of small dosage, easy use, good effect and low cost.

[0003] The principle of adding a small amount of pour point depressant to crude oil to achieve significant results is that the pour point depressant can solubilize wax, change the nucleation and growth of wax crystals, inhibit the formation of network fine crystals, or play a good dispersing role. The pour point depressants discovered so far all have polar groups (such as carbonyl, etc.) and non-polar groups (long-chain alkyl, phenyl, etc.), and are typical surfactants with relatively special structures. Since the composition of crude oil is very complex and the geological structure of oil wells is complex and variable, different pour point depressants are required for oil wells in different regions and different stages of crude oil production, that is, general pour point depressants are not universal. The common defects of the currently used pour point depressants are that they cannot be quickly and effectively dispersed in crude oil while ensuring efficiency, and the dosage is still high (generally 800ppm-1800ppm is required).

[0004] Therefore, there is an urgent need to develop a pour point depressant that can quickly and effectively disperse crude oil while significantly reducing the pour point and viscosity of crude oil.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The object of the present invention is to provide a vinyl copolymer pour point depressant, a preparation method and application thereof, aiming to improve the pour point depressant and viscosity reducing effects while significantly reducing the amount of pour point depressant used.

[0007] The present invention is achieved in that: In a first aspect, the present invention provides a vinyl copolymer pour point depressant, which is obtained by polymerizing acrylamide, a methacrylate compound, a fumaric acid compound, and nano-silica modified by an alkyl coupling agent as monomers; The weight ratio of the fumaric acid compound, acrylamide and methacrylate compound is (1-2): (1-2): (3-7); The weight ratio of the total amount of fumaric acid compounds, acrylamide and methacrylate compounds to the nano-silica modified by the alkyl coupling agent is (20-45):1.

[0008] In an optional embodiment, the fumaric acid compound is selected from at least one of fumaric acid, monoethyl fumarate and diethyl fumarate.

[0009] In an optional embodiment, in the fumaric acid compound, the weight ratio of fumaric acid, monoethyl fumarate and diethyl fumarate is (1-3): (0-1): (0-1).

[0010] In an optional embodiment, the methacrylate compound is selected from at least one of octadecyl methacrylate and hexadecyl methacrylate.

[0011] In an optional embodiment, in the methacrylate compound, the weight ratio of octadecyl methacrylate to hexadecyl methacrylate is (1-3): (0-1).

[0012] In a second aspect, the present invention provides a method for preparing a vinyl copolymer pour point depressant according to any one of the aforementioned embodiments, comprising: using acrylamide, methacrylate compounds, fumaric acid compounds and nano-silica modified by an alkyl coupling agent as monomers to carry out a polymerization reaction.

[0013] In an optional embodiment, the method comprises: mixing the monomer and the solvent, heating the mixture to 55° C. to 95° C., adding an initiator and polymerizing the mixture for 4 h to 9 h; Wherein, the initiator is selected from at least one of potassium persulfate, sodium persulfate, ammonium persulfate, azobisisoheptanenitrile and azobisisobutyronitrile; the mass ratio of the initiator to the total amount of the monomer is (0.1-0.5): 100; The solvent is selected from at least one of toluene, xylene, butanol, isobutanol, propanol, isopropanol and ethanol; After the polymerization reaction is completed, the solvent is distilled to obtain a solid material, which is then washed and dried.

[0014] In an optional embodiment, the preparation process of nano-silica modified by an alkyl coupling agent comprises: The silane coupling agent is hydrolyzed at a pH value of 4-7 and a temperature of 30° C.-65° C. for 0.5 h-4 h to obtain a hydrolysis reaction material; The nano-silicon dioxide and the hydrolysis reaction material are subjected to a coupling grafting reaction, and the reaction temperature is controlled to be 55° C.-95° C. and the reaction time is 4 h-9 h.

[0015] In an optional embodiment, the silane coupling agent is selected from at least one of A171, A173, ZQ172, KH560 and KH570; And / or, the mass ratio of nano-silica to silane coupling agent is (3-5):1.

[0016] In a third aspect, the present invention provides the use of any vinyl copolymer pour point depressant in the aforementioned embodiments or the vinyl copolymer pour point depressant prepared by any preparation method in the aforementioned embodiments in treating waxy crude oil; Wherein, the addition amount of the vinyl copolymer pour point depressant is 400ppm-600ppm.

[0017] The invention has the following beneficial effects: the copolymer pour point depressant prepared by using acrylamide, fumaric acid compounds, methacrylate compounds and nano-silica modified by an alkyl coupling agent as monomers has the characteristics and characteristic chemical bonds of copolymer macromolecules, and the softness and elasticity of the copolymer molecules vary greatly when the copolymer is dissolved or in solution due to the unique molecular chain and structure of the copolymer, and the crude oil can be quickly and effectively dispersed, and the pour point and viscosity of the crude oil can be significantly reduced under the condition of a very small dosage (such as 500ppm). BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 These are infrared characterization images of the vinyl copolymer pour point depressant prepared in Example 1 of the present invention; (a) represents SiO2; (b) represents OSiO2; (c) is the product of Example 1 of the present application. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0021] In view of the problems of high dosage and unsatisfactory crude oil dispersion effect of existing pour point depressants, the embodiments of the present invention improve the monomer types and ratios of the vinyl copolymer pour point depressant, so that the prepared vinyl copolymer pour point depressant can significantly reduce the pour point and viscosity of crude oil at a very small dosage (such as 500ppm), and the pour point of crude oil can be reduced by about 30°C, with a very significant pour point depressing effect.

[0022] The embodiment of the present invention provides a method for preparing a vinyl copolymer pour point depressant, which is obtained by polymerizing acrylamide, a methacrylate compound, a fumaric acid compound and nano-silica modified by an alkyl coupling agent as monomers, and the specific steps are as follows: S1. Preparation of nano-silica modified by alkyl coupling agent Nano-silica modified by alkyl coupling agent is obtained by modifying nano-silica with alkyl coupling agent. Due to the introduction of alkyl coupling agent, nano-silica modified by alkyl coupling agent can participate in subsequent polymerization reaction, and introduce nano-scale (20-60nm) large groups into the main chain of polymer molecules. The large groups also have certain structures and polar groups and non-polar groups, which can further adjust the molecular structure of the copolymer and the ratio and distribution of polar groups and non-polar groups. In some embodiments, the preparation process of nano-silica modified by an alkyl coupling agent includes: first fully hydrolyzing the silane coupling agent, and then coupling and grafting with the nano-silica. In the actual operation process, the following steps are included: hydrolyzing the silane coupling agent at a pH value of 4-7 and a temperature of 30°C-65°C for 0.5h-4h to obtain a hydrolysis reaction material; coupling and grafting the nano-silica with the hydrolysis reaction material, controlling the reaction temperature to 55°C-95°C, and the reaction time to 4h-9h. By adjusting the hydrolysis conditions of the silane coupling agent (such as stirring intensity-rate and the form of stirring blades), the purpose of sufficient hydrolysis is achieved to increase the grafting rate with nano-silica.

[0023] Specifically, the pH value of the hydrolysis reaction of the silane coupling agent can be 4.0, 5.0, 6.0, 7.0, etc., the hydrolysis temperature can be 30°C, 40°C, 50°C, 60°C, 65°C, etc., and the hydrolysis time can be 0.5h, 1.0h, 2.0h, 3.0h, 4.0h, etc.; the reaction temperature when the nano-silicon dioxide and the hydrolysis reaction material are coupled and grafted can be 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, etc., and the reaction time can be 4h, 5h, 6h, 7h, 8h, 9h, etc. After the coupling and grafting reaction is completed, solid-liquid separation can be performed by filtering or the like, and the obtained solid material can be washed and dried to obtain the nano-silicon dioxide modified by the alkyl coupling agent, which can be used as a monomer synthesis pour point depressant in the subsequent use.

[0024] In some embodiments, the silane coupling agent is selected from at least one of A171, A173, ZQ172, KH560 and KH570, and the silane coupling agent can be any one or more of the above. The mass ratio of nano-silica and silane coupling agent is (3-5): 1, such as 3: 1, 4: 1, 5: 1, etc., and the mass ratio of nano-silica and silane coupling agent is regulated to regulate the amount of silane coupling agent introduced, and then the structure of the vinyl copolymer pour point depressant is regulated, which can further improve the pour point and viscosity reduction effect. The particle size of nano-silica is nanometer level, and the specific particle size can be 20nm-60nm.

[0025] S2. Polymerization The polymerization reaction is carried out using acrylamide, methacrylate compounds, fumaric acid compounds and nano-silica modified by an alkyl coupling agent as monomers.

[0026] It should be noted that the embodiment of the present invention uses a variety of comonomers, so that the vinyl copolymer pour point depressant product has a rich, adjustable and three-dimensional molecular configuration that is compatible with complex crude oil, and has polar groups and non-polar groups; and because the polymer molecule main chain is introduced by grafting into a large group of nanometer scale, the large group also has a certain structure and polar groups and non-polar groups, and the molecular structure and the polar groups and non-polar groups of the copolymer can be further adjusted. The proportion and distribution. The vinyl copolymer pour point depressant with this new molecular structure has a wide range of oil solubility and water solubility, and the molecular softness and elasticity are greatly improved. It can increase the solubility of crude oil wax in the system, change the nucleation and growth characteristics of wax crystals, and can also be quickly and effectively dispersed in the crude oil system (due to the simultaneous presence of polar and non-polar substances in crude oil, and contains a dispersed microemulsion water phase, etc.), which makes the pour point depressant have excellent pour point and viscosity reduction effects.

[0027] In some embodiments, the weight ratio of the fumaric acid compound, acrylamide and methacrylate compound is (1-2): (1-2): (3-7); the weight ratio of the total amount of the fumaric acid compound, acrylamide and methacrylate compound to the alkyl coupling agent modified nano-silica is (20-45): 1. By adjusting the amount of several monomers, the three-dimensional molecular configuration of the vinyl copolymer pour point depressant is further adjusted, the compatibility with complex crude oil is improved, and the pour point and viscosity reducing effects of the pour point depressant are improved.

[0028] Specifically, the weight ratio of fumaric acid compounds, acrylamide and methacrylate compounds can be 1.0:1.0:3.0, 1.3:1.3:4.0, 1.5:1.5:5.0, 1.8:1.8:6.0, 2.0:2.0:7.0, etc.; the weight ratio of the total amount of fumaric acid compounds, acrylamide and methacrylate compounds to the alkyl coupling agent modified nano silica can be 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, etc.

[0029] In some embodiments, the fumaric acid compound is selected from at least one of fumaric acid, monoethyl fumarate and diethyl fumarate, and the fumaric acid compound can be any one or more of the above. In a preferred embodiment, in the fumaric acid compound, the weight ratio of fumaric acid, monoethyl fumarate and diethyl fumarate is (1-3): (0-1): (0-1), such as 1.0:0:0, 1.5:0.1:0.1, 2.0:0.3:0.3, 2.5:0.5:0.5, 2.8:0.8:0.8, 3.0:1.0:1.0, etc.

[0030] In some embodiments, the methacrylate compound is selected from at least one of octadecyl methacrylate and hexadecyl methacrylate, and the methacrylate compound can be any one or more of the above. In the methacrylate compound, the weight ratio of octadecyl methacrylate to hexadecyl methacrylate is (1-3): (0-1), such as 1.0:0.0, 1.5:0.3, 2.0:0.5, 2.5:0.8, 3.0:1.0, etc.

[0031] In some embodiments, the specific operation steps of the polymerization reaction include: mixing the monomer and the solvent and heating to 55°C-95°C (such as 55°C, 60°C, 70°C, 80°C, 90°C, 95°C, etc.), adding a free radical initiator under reflux for polymerization for 4h-9h (such as 4h, 5h, 6h, 7h, 8h, 9h, etc.), and regulating the polymerization temperature and time to fully carry out the reaction. The initiator is selected from at least one of potassium persulfate, sodium persulfate, ammonium persulfate, azobisisoheptanenitrile and azobisisobutyronitrile, and the initiator can be any one or more of the above; the mass ratio of the initiator to the total amount of the monomer is (0.1-0.5): 100, such as 0.1:100, 0.2:100, 0.3:100, 0.4:100, 0.5:100, etc., and it is appropriate to be within this dosage range to promote the polymerization reaction.

[0032] Furthermore, the solvent is selected from at least one of toluene, xylene, butanol, isobutanol, propanol, isopropanol and ethanol, and the solvent may be any one or more of the above.

[0033] Furthermore, after the polymerization reaction is completed, the solvent is distilled to obtain a solid material, and the solid material is washed and dried to obtain a copolymer product pour point depressant. The washing method is not limited, and it can be washed with water multiple times to fully remove unreacted raw materials, and then the washing solvent is removed by drying to obtain the final product.

[0034] The embodiment of the present invention also provides a vinyl copolymer pour point depressant, which is obtained by polymerizing acrylamide, methacrylate compounds, fumaric acid compounds and nano-silica modified by an alkyl coupling agent as monomers; wherein the nano-silica modified by an alkyl coupling agent is obtained by modification by an alkyl coupling agent; the ratio of each monomer can refer to the description in the above-mentioned preparation method, and will not be repeated here.

[0035] It should be noted that the vinyl copolymer pour point depressant provided in the embodiments of the present invention has a wide range of oil solubility and water solubility, and the molecular softness and elasticity are greatly improved. It can increase the solubility of crude oil wax in the system and change the nucleation and growth characteristics of wax crystals. It can also be quickly and effectively dispersed in the crude oil system, and can have excellent pour point and viscosity reduction effects with a small amount of use.

[0036] The embodiments of the present invention also provide the use of the vinyl copolymer pour point depressant in treating waxy crude oil. The unique molecular chain and structure of the vinyl copolymer pour point depressant enable the softness and elasticity of the copolymer molecules to vary greatly when it is dissolved or in solution, and the crude oil can be dispersed quickly and effectively, and the pour point and viscosity of the crude oil can be significantly reduced under the condition of a very small amount.

[0037] In some embodiments, the addition amount of the vinyl copolymer pour point depressant is 400 ppm-600 ppm, such as 400 ppm, 450 ppm, 500 ppm, 550 ppm, 600 ppm, etc., preferably 500 ppm.

[0038] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0039] Example 1 This embodiment provides a method for preparing a vinyl copolymer pour point depressant, the steps are as follows: (1) Preparation of nano-silica modified with alkyl coupling agent Weigh 4.00 g of nano-silicon dioxide with an average particle size of 37 nm and 1.00 g of a silane coupling agent (KH560).

[0040] The silane coupling agent and 1.5 mL of deionized water were mixed and stirred, the pH value was adjusted to 5 with a 10% by mass dilute hydrochloric acid solution, and hydrolyzed at 39° C. for 1 h to obtain a hydrolysis reaction material.

[0041] Nano-silica and 40 mL of propanol were mixed and stirred, heated to 70°C, mixed and stirred with the hydrolysis reaction material, and the grafting reaction was carried out at 70°C for 8 hours. After the reaction was completed, the nano-silica modified with an alkyl coupling agent was obtained after washing and drying (100°C, 5 hours) for use in synthesizing a pour point depressant.

[0042] (2) Polymerization reaction Weigh 14.29 g of acrylamide, 28.57 g of octadecyl methacrylate, 7.14 g of fumaric acid and 2.00 g of modified nano-silica monomer.

[0043] The above weights of monomers were added to a four-necked flask containing 120 mL of xylene and butanol (volume ratio of 1:1, the same below), stirred and heated to reflux, and 20 mL of azobisisoheptanonitrile solution was added dropwise at 65°C for 100 minutes. After the addition was completed, the reaction was continued for 5 hours. After the reaction was completed, the solvent was distilled, and then washed with water and dried (100°C, 3 hours).

[0044] Example 2 This embodiment provides a method for preparing a vinyl copolymer pour point depressant, the steps are as follows: (1) Preparation of nano-silica modified with alkyl coupling agent Please refer to Example 1 for the specific steps.

[0045] (2) Polymerization reaction Weigh 14.29 g of acrylamide, 28.57 g of octadecyl methacrylate, 5.9 g of fumaric acid, 2.00 g of monoethyl fumarate and 2.00 g of modified nano-silica monomer.

[0046] The above weights of monomers were added to a four-necked flask containing 120 mL of xylene and butanol, stirred and heated to reflux, and 20 mL of azobisisoheptanitrile solution was added dropwise at 65°C for 100 min. After the addition was completed, the reaction was continued for 5 h. After the reaction was completed, the solvent was distilled, and then washed with water and dried (100°C, 3 h).

[0047] Example 3 The only difference from Example 1 is that the type of methacrylate monomer in step (2) is different. 14.29 g of acrylamide, 28.57 g of hexadecyl methacrylate, 7.14 g of fumaric acid and 2.00 g of modified nano-silica monomer are weighed.

[0048] Example 4 The only difference from Example 1 is that the amounts of monomers used in step (2) are different: 21.44 g acrylamide, 42.86 g octadecyl methacrylate, 11.85 g fumaric acid and 2.00 g modified nano-silica monomer are weighed.

[0049] Note: In this embodiment, the weight ratio of the total amount of fumaric acid compounds, acrylamide and methacrylate compounds to the alkyl coupling agent modified nano-silica is 38:1, and the weight ratio of fumaric acid compounds, acrylamide and methacrylate compounds is 1:1.8:3.61.

[0050] Example 5 The only difference from Example 1 is that in step (1), the amount of nano-silica is 4.00 g, the amount of silane coupling agent is 1.3 g, and the weight ratio of nano-silica to silane coupling agent is 3:1.

[0051] Comparative Example 1 The pour point depressant provided in this comparative example is an octadecyl acrylate-maleic anhydride copolymer pour point depressant, and the preparation method is as follows: refer to Example 1 of Patent 201910527927.3.

[0052] Comparative Example 2 The pour point depressant provided in this comparative example refers to octadecyl acrylate-maleic anhydride copolymer aniline depressant, and the preparation method is as follows: refer to Example 3 of Patent 201910527927.3.

[0053] Comparative Example 3 The only difference from Example 1 is that the amounts of monomers used in step (2) are different: 14.29 g of acrylamide, 17.86 g of octadecyl methacrylate, 7.14 g of fumaric acid and 2.00 g of modified nano-silica monomer are weighed.

[0054] Note: In this comparative example, the weight ratio of the total amount of fumaric acid compounds, acrylamide and methacrylate compounds to the alkyl coupling agent-modified nano-silica is 19.6:1, and the weight ratio of fumaric acid compounds, acrylamide and methacrylate compounds is 1:2.0:2.5.

[0055] Comparative Example 4 The only difference from Example 1 is that the amounts of monomers used in step (2) are different: 9.52 g of acrylamide, 19.05 g of octadecyl methacrylate, 5.27 g of fumaric acid and 2.00 g of modified nano-silica monomer are weighed.

[0056] Note: In this comparative example, the weight ratio of the total amount of fumaric acid compounds, acrylamide and methacrylate compounds to the alkyl coupling agent-modified nano-silica is 16.92:1, and the weight ratio of fumaric acid compounds, acrylamide and methacrylate compounds is 1:1.8:3.6.

[0057] Comparative Example 5 The only difference from Example 1 is that: no modified nano-silica monomer is added; 14.29 g of acrylamide, 28.57 g of octadecyl methacrylate, and 7.14 g of fumaric acid.

[0058] Comparative Example 6 The only difference from Example 1 is that fumaric acid is not added; 14.29 g of acrylamide, 28.57 g of octadecyl methacrylate and 2.00 g of modified nano-silica monomer are added.

[0059] Comparative Example 7 The only difference from Example 1 is that no acrylamide is added; 28.57 g of octadecyl methacrylate, 7.14 g of fumaric acid and 2.00 g of modified nano-silica monomer are added.

[0060] Test Example 1 The vinyl copolymer pour point depressant prepared in Example 1 was subjected to infrared characterization. The results are as follows: Figure 1 shown.

[0061] Figure 1 (a) shows that SiO2 has a peak at 1056 cm -1 and 800 cm -1 On the left and right are the antisymmetric stretching vibration peaks of silicon-oxygen-silicon and the symmetric stretching vibration peaks, 474 cm -1 The absorption peak at is the bending vibration of silicon-oxygen-silicon. Figure 1 In (b), after organic grafting, the carbon-carbon double bond stretching vibration absorption peak of KH560 appears at 1703, proving that the organic grafting is successful. Figure 1 (c) shows that the vinyl copolymer product of the present application has a peak at 1044 cm -1 The left and right sides are the silicon-oxygen-silicon stretching vibration absorption peaks, 465 cm -1 The left and right are the absorption peaks of silicon-oxygen-silicon bending vibration. The rest are the absorption peaks of polymers at a high wave number of 3200 cm -1 、3343 cm -1 The stretching vibration absorption peak of -NH2 of primary amine was observed at 2917 cm -1 and 2850 cm -1 . —(CH) n —The characteristic bending vibration absorption peak appears at 723 cm -1 At 1670~1640 cm -1 At 1708 cm, the C=C bond stretching vibration absorption peak disappears, indicating that there is no unreacted monomer in the copolymer. -1 The absorption peak of C=O was also observed, which originated from the carboxylic acid dimer. The peak intensity and absorption band width increased with the mole fraction of the carboxylic acid dimer in the range of 1708–1724 cm -1The structural characteristics of the vinyl copolymer nano pour point depressant of the present application monomer are fully proved.

[0062] Test Example 2 The pour point depressants prepared in the test examples and comparative examples were tested for their pour point depressant and viscosity reducing effects. The test results are shown in Table 1.

[0063] High waxy crude oil was used as the experimental oil. The wax content of the experimental oil was 9%, the colloidal asphalt content was 8.3% (by weight), the pour point was 12°C, and the viscosity was 82.6 Pa.s (20°C).

[0064] Test method: The viscosity in this example is the value measured when 500 ppm of pour point depressant is added to crude oil at 20°C.

[0065] Table 1 Pour point depressant and viscosity reduction effects of the pour point depressants prepared in Examples and Comparative Examples

[0066] It can be seen that the viscosity and pour point effects of different pour point depressants vary greatly, which may be due to: the difference in the structure of the pour point depressant molecule (which depends largely on the difference in the monomer molecule and structure); the reason why the nano pour point depressant provided in the embodiment of the present invention has excellent performance is that the nano silicon dioxide macro-group is introduced into the copolymer molecular chain by grafting, so that the pour point depressant is further improved and enriched in hydrophilic and lipophilic groups from the perspective of molecular structure. Therefore, when the pour point depressant provided in the embodiment of the present invention is used in the crude oil system, it can be effectively and quickly dispersed and distributed, and is more compatible with various substances in the crude oil system, and can work together in solubilization, dispersion and crystallization change at the same time.

[0067] Test Example 3 The pour point depressant and viscosity reducing effects of the vinyl copolymer pour point depressant provided in Example 1 at different dosages were tested. The results are shown in Table 2.

[0068] Table 2 Pour point depressant and viscosity reduction effects of vinyl copolymer pour point depressant in Example 1 at different dosages

[0069] It can be seen that when the dosage is 500ppm, the effect of reducing freezing point and viscosity is the best.

[0070] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A vinyl copolymer pour point depressant, characterized in that: The nano-silica modified by acrylamide, methacrylate compounds, fumaric acid compounds and alkyl coupling agents is obtained by polymerization of monomers; The weight ratio of the fumaric acid compound, the acrylamide and the methacrylate compound is (1-2): (1-2): (3-7); The weight ratio of the total amount of the fumaric acid compound, the acrylamide and the methacrylate compound to the nano-silica modified by the alkyl coupling agent is (20-45):

1.

2. The vinyl copolymer pour point depressant according to claim 1, characterized in that The fumaric acid compound is selected from at least one of fumaric acid, monoethyl fumarate and diethyl fumarate.

3. The vinyl copolymer pour point depressant according to claim 2, characterized in that In the fumaric acid compound, the weight ratio of the fumaric acid, the monoethyl fumarate and the diethyl fumarate is (1-3): (0-1): (0-1).

4. The vinyl copolymer pour point depressant according to claim 1, characterized in that The methacrylate compound is selected from at least one of octadecyl methacrylate and hexadecyl methacrylate.

5. The vinyl copolymer pour point depressant according to claim 4, characterized in that In the methacrylate compound, the weight ratio of octadecyl methacrylate to hexadecyl methacrylate is (1-3):(0-1).

6. A method for preparing the vinyl copolymer pour point depressant according to any one of claims 1 to 5, characterized in that: include: The acrylamide, the methacrylate compound, the fumaric acid compound and the nano-silica modified by the alkyl coupling agent are used as monomers to carry out a polymerization reaction.

7. The preparation method according to claim 6, characterized in that: include: Mix the monomer and solvent and heat to 55°C-95°C, add initiator and polymerize for 4h-9h; Wherein, the initiator is selected from at least one of potassium persulfate, sodium persulfate, ammonium persulfate, azobisisoheptanenitrile and azobisisobutyronitrile; the mass ratio of the initiator to the total amount of the monomer is (0.1-0.5): 100; The solvent is selected from at least one of toluene, xylene, butanol, isobutanol, propanol, isopropanol and ethanol; After the polymerization reaction is completed, the solvent is distilled to obtain a solid material, which is then washed and dried.

8. The preparation method according to claim 6, characterized in that: The preparation process of the alkyl coupling agent modified nano silicon dioxide comprises: The silane coupling agent is hydrolyzed at a pH value of 4-7 and a temperature of 30° C.-65° C. for 0.5 h-4 h to obtain a hydrolysis reaction material; The nano-silicon dioxide is subjected to a coupling grafting reaction with the hydrolysis reaction material, and the reaction temperature is controlled to be 55° C.-95° C., and the reaction time is 4 h-9 h.

9. The preparation method according to claim 8, characterized in that: The silane coupling agent is selected from at least one of A171, A173, ZQ172, KH560 and KH570; And / or, the mass ratio of the nano-silica to the silane coupling agent is (3-5):

1.

10. Use of the vinyl copolymer pour point depressant according to any one of claims 1 to 5 or the vinyl copolymer pour point depressant prepared by the preparation method according to any one of claims 6 to 9 in treating waxy crude oil; in, The added amount of the vinyl copolymer pour point depressant is 400ppm-600ppm.

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