Pour point depressant suitable for conveying crude oil as well as preparation method and application of pour point depressant

Abstract

The invention discloses a pour point depressant suitable for conveying crude oil and a preparation method and application thereof, and belongs to the technical field of oil field chemicals. The pour point depressant comprises a first component, a second component, a third component and a fourth component, the first component is one or more of polyoxyethylene fatty alcohol ether, polyoxyethylene fatty alcohol ester and alkylphenol polyoxyethylene ether, and the molecular weight of the first component is 600-1600; the second component is a covalent grafting product of graphene oxide and a terpolymer of oleic acid, long-chain alpha-olefin and methacrylamide, and the molecular weight of the second component is 3000-8000; the third component is a composite product of nano silicon dioxide and a terpolymer of acrylate, fumaric acid and vinyl acetate, and the molecular weight of the third component is 3000-5000; and the fourth component is one or more of sorbitan fatty acid ester, a polyisobutylene succinic anhydride derivative and ethylene glycol monobutyl ether. The problem of poor timeliness of a single-component pour point depressant is solved, and the performance timeliness of the product is remarkably improved, so that the pour point depressant meets the conveying requirement.

Description

Technical Field

[0001] The present application relates to a pour point depressant suitable for transporting crude oil, a preparation method thereof, and an application thereof, and belongs to the technical field of oilfield chemicals. Background Art

[0002] Waxy crude oil has a high pour point and poor low-temperature fluidity. For a long time, heating technology has been used for pipeline transportation, but heating transportation has safety and economic problems. Since the 1960s, people have found that adding pour point depressants to waxy crude oil can effectively lower the pour point of crude oil. For example, Chinese invention patent CN116426259B discloses a crude oil viscosity reducer and pour point depressant and its preparation method. The crude oil viscosity reducer and pour point depressant achieves the purpose of lowering the pour point of crude oil, improving the low-temperature viscosity of crude oil, and solving the high viscosity problem caused by colloids. Adding pour point depressants to waxy crude oil to improve low-temperature fluidity has become a widely used, safe and economical waxy crude oil transportation technology. This technology plays a very important role in the safe operation of waxy crude oil pipelines and energy conservation and consumption reduction.

[0003] However, the current traditional pour point depressants have the limitation of poor performance and timeliness, which causes the freezing point of the modified crude oil after adding the pour point depressant to increase in the later stage of transportation, affecting the transportation effect. Summary of the Invention

[0004] The purpose of the present invention is to provide a pour point depressant suitable for transporting crude oil, a preparation method thereof, and an application thereof. The components have a synergistic promoting effect, thereby solving the problem of poor timeliness of single-component pour point depressants and significantly improving the performance timeliness of the product to adapt it to transportation requirements.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is: According to one aspect of the present application, there is provided a pour point depressant suitable for transporting crude oil, comprising a first component, a second component, a third component, and a fourth component; The first component is one or more of polyoxyethylene fatty alcohol ether, polyoxyethylene fatty alcohol ester and alkylphenol polyoxyethylene ether, and the molecular weight of the first component is 600 to 1600; The second component is a covalent graft product of a terpolymer of oleic acid, long-chain α-olefin and methacrylamide and graphene oxide, and the molecular weight of the second component is 3000 to 8000; The third component is a composite product of a terpolymer of acrylate, fumaric acid and vinyl acetate and nano-silicon dioxide, and the molecular weight of the third component is 3000 to 5000; The fourth component is one or more of sorbitan fatty acid ester, polyisobutenyl succinic anhydride derivative and ethylene glycol monobutyl ether; Wherein, the fatty chain length of the polyoxyethylene fatty alcohol ether is C12 to C24; The fatty chain length of the polyoxyethylene fatty alcohol ester is C12 to C18; The alkyl chain length of the alkylphenol polyoxyethylene ether is C8 to C12; The long-chain α-olefin is one or more of α-dodecene, α-tetradecene, α-hexadecene and α-octadecene; The mass ratio of the first component, the second component, the third component and the fourth component is (1-5): (30-40): (35-50): (2-3).

[0006] Optionally, the mass ratio of oleic acid, long-chain α-olefin and methacrylamide in the second component is (20-30): (40-60): (1-3); The amount of graphene oxide is 1 to 8% of the mass of the second component.

[0007] Optionally, the mass ratio of acrylate, fumaric acid and vinyl acetate in the third component is (60-75): (2-3): (5-8); The amount of the nano-silicon dioxide accounts for 1 to 5% of the mass of the third component.

[0008] According to another aspect of the present application, a method for preparing a pour point depressant suitable for transporting crude oil is provided. The method is used to prepare any of the above-mentioned pour point depressants suitable for transporting crude oil, and the method comprises the following steps: (1) Oleic acid, long-chain α-olefin and methacrylamide in a mass ratio of (20-30): (40-60): (1-3) are dissolved in a light aromatic solvent, 0.1-0.5 wt% of an initiator is added, an inert gas is introduced, and a polymerization reaction is carried out at 65-120°C to obtain a terpolymer of oleic acid, long-chain α-olefin and methacrylamide, and then 0.3-0.6 wt% of p-toluenesulfonic acid and 1-8 wt% of graphene oxide as a second component are added to the terpolymer of oleic acid, long-chain α-olefin and methacrylamide, a grafting reaction is carried out at 120-170°C, and then vacuum is applied at 140-160°C to remove unreacted monomers to obtain a second component; (2) dissolving acrylate, fumaric acid and vinyl acetate in a mass ratio of (60-75): (2-3): (5-8) in toluene, adding 0.1-0.5 wt% of an initiator, introducing an inert gas, and carrying out a polymerization reaction at 65-95°C to obtain a terpolymer of acrylate, fumaric acid and vinyl acetate, then adding 1-5 wt% of nano-silica as a third component to the terpolymer of acrylate, fumaric acid and vinyl acetate, stirring at 150-170°C for 80-100 min, then hot washing with a mixed solution of ethanol and water at 60-80°C to remove unreacted monomers, and vacuuming at 140-160°C to remove the solvent to obtain a third component; (3) The first component, the second component, the third component and the fourth component are dissolved in a heavy aromatic hydrocarbon solvent in a mass ratio of (1-5): (30-40): (35-50): (2-3) to obtain a pour point depressant suitable for transporting crude oil.

[0009] Optionally, the acrylate is one or more of lauryl acrylate, tetradecyl acrylate, hexadecyl acrylate and octadecyl acrylate.

[0010] Optionally, the initiator is azobisisobutyronitrile; The light aromatic hydrocarbon solvent is benzene, toluene or mixed xylenes; The heavy aromatic hydrocarbon solvent is No. 150 solvent oil.

[0011] Optionally, the method further comprises the step of surface treating the nano-silicon dioxide; The surface treatment step comprises: adding nano-silica to toluene, ultrasonically dispersing for 20 to 40 minutes, adding 5 to 15 wt% of a silane coupling agent, stirring and mixing uniformly, heating to 80 to 90° C., and stirring and reacting for 2 to 4 hours; Wherein, the silane coupling agent is at least one of KH-550, KH-560 and KH-570.

[0012] According to another aspect of the present application, there is provided a use of any of the above-mentioned pour point depressants suitable for transporting crude oil in crude oil transportation, wherein the concentration of the depressant is 2200 ppm.

[0013] The beneficial effects of this application include but are not limited to: 1. The pour point depressant suitable for transporting crude oil in the present application comprises the first, second, third and fourth components, which work synergistically to solve the problem of poor timeliness of single-component pour point depressants, significantly improve the performance timeliness of the product, and adapt it to transportation requirements. 2. In the pour point depressant for crude oil transportation disclosed herein, the long-chain alkyl group in the first component is a hydrophobic group, and the polyoxyethylene chain is a hydrophilic group. The hydrophobic and hydrophilic groups act synergistically to interfere with the formation and growth of wax in the crude oil, thereby lowering the pour point of the crude oil.

[0014] 3. The pour point depressant for crude oil transportation disclosed herein is a covalently grafted product of a terpolymer of oleic acid, long-chain α-olefins, and methacrylamide onto graphene oxide. Its molecules can insert into the wax crystal lattice, disrupting the regular arrangement of the wax crystals, destroying the ordered crystal structure, and reducing interactions and entanglement between the wax crystals, thereby lowering the pour point of crude oil.

[0015] 4. The pour point depressant suitable for crude oil transportation disclosed herein comprises a third component, a terpolymer of acrylate, fumaric acid, and vinyl acetate, exhibiting a comb-like structure. The carbon chain lengths of its main and side chains are similar to those of paraffin wax. This alters the crystallization of paraffin wax in crude oil, making it less likely to form a spatial network structure and significantly lowering the pour point of the crude oil. Nanosilica weakens the structural strength of wax crystals, improving the low-temperature fluidity of waxy crude oil, enhancing its dynamic and static aging stability, and increasing its shear resistance, significantly enhancing the product's performance and timeliness, making it suitable for transportation requirements.

[0016] 5. In the pour point depressant for transporting crude oil of the present application, the fourth component can increase the interaction between the pour point depressant and the crude oil, thereby improving the pour point depressant effect of the pour point depressant. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 This is the infrared spectrum of the second component in the pour point depressant suitable for transporting crude oil in Example 4 of the present application.

[0018] Figure 2 This is the infrared spectrum of the third component in the pour point depressant suitable for transporting crude oil in Example 4 of the present application. DETAILED DESCRIPTION

[0019] The endpoints of the ranges and any values ​​disclosed herein 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 endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0020] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or those recommended by the manufacturer. The raw materials or instruments used, if the manufacturers are not specified, are all conventional products that can be purchased commercially.

[0021] 1. A pour point depressant suitable for transporting crude oil and its preparation method 1.1. The present invention provides a pour point depressant suitable for transporting crude oil, comprising a first component, a second component, a third component, and a fourth component; The first component is one or more of polyoxyethylene fatty alcohol ether, polyoxyethylene fatty alcohol ester and alkylphenol polyoxyethylene ether, and the molecular weight of the first component is 600 to 1600; The second component is a covalent graft product of a terpolymer of oleic acid, long-chain α-olefin and methacrylamide and graphene oxide, and the molecular weight of the second component is 3000 to 8000; The third component is a composite product of a terpolymer of acrylate, fumaric acid and vinyl acetate and nano-silicon dioxide, and the molecular weight of the third component is 3000 to 5000; The fourth component is one or more of sorbitan fatty acid ester, polyisobutenyl succinic anhydride derivative and ethylene glycol monobutyl ether.

[0022] Among them, the fatty chain length of polyoxyethylene fatty alcohol ether is C12~C24; the fatty chain length of polyoxyethylene fatty alcohol ester is C12~C18; the alkyl chain length of alkylphenol polyoxyethylene ether is C8~C12; the mass ratio of the first component, the second component, the third component and the fourth component is (1~5): (30~40): (35~50): (2~3); the mass ratio of oleic acid, long-chain α-olefin and methacrylamide in the second component is (20~30): (40~60): (1~3); the amount of graphene oxide accounts for 1~8% of the mass of the second component; the mass ratio of acrylate, fumaric acid and vinyl acetate in the third component is (60~75): (2~3): (5~8); the amount of nanosilica accounts for 1~5% of the mass of the third component.

[0023] 1.2. The preparation method of the pour point depressant suitable for transporting crude oil comprises the following steps: (1) Oleic acid, long-chain α-olefin and methacrylamide in a mass ratio of (20-30): (40-60): (1-3) are dissolved in a light aromatic solvent, 0.1-0.5 wt% of an initiator is added, an inert gas is introduced, and a polymerization reaction is carried out at 65-120°C to obtain a terpolymer of oleic acid, long-chain α-olefin and methacrylamide, and then 0.3-0.6 wt% of p-toluenesulfonic acid and 1-8 wt% of graphene oxide are added to the terpolymer of oleic acid, long-chain α-olefin and methacrylamide, and a grafting reaction is carried out at 120-170°C, followed by vacuuming at 140-160°C to remove unreacted monomers to obtain a second component; (2) dissolving acrylate, fumaric acid and vinyl acetate in a mass ratio of (60-75): (2-3): (5-8) in toluene, adding 0.1-0.5 wt% of an initiator, introducing an inert gas, and carrying out a polymerization reaction at 65-95°C to obtain a terpolymer of acrylate, fumaric acid and vinyl acetate, then adding 1-5 wt% of nano-silica to the terpolymer of acrylate, fumaric acid and vinyl acetate, stirring at 150-170°C for 80-100 min, and then hot washing with a mixed solution of ethanol and water (weight ratio of 1:1) at 60-80°C to remove unreacted monomers, and vacuuming at 140-160°C to remove the solvent to obtain a third component; (3) The first component, the second component, the third component and the fourth component are dissolved in a heavy aromatic hydrocarbon solvent in a mass ratio of (1-5): (30-40): (35-50): (2-3) to obtain a pour point depressant suitable for transporting crude oil.

[0024] Wherein, the long-chain α-olefin is one or more of α-dodecene, α-tetradecene, α-hexadecene and α-octadecene, preferably α-octadecene; The acrylate is one or more of lauryl acrylate, tetradecyl acrylate, hexadecyl acrylate and octadecyl acrylate, preferably octadecyl acrylate; The initiator is azobisisobutyronitrile; The light aromatic solvent is benzene, toluene or mixed xylenes, preferably mixed xylenes; The heavy aromatic solvent is No. 150 solvent oil; The step of surface treating the nano-silicon dioxide is also included; The surface treatment steps include: adding nano-silica into toluene, ultrasonically dispersing for 20 to 40 minutes, adding 5 to 15 wt% of a silane coupling agent, stirring and mixing evenly, heating to 80 to 90° C., and stirring and reacting for 2 to 4 hours.

[0025] Preferably, the step of surface treating the nano-silica comprises: adding the nano-silica to toluene, ultrasonically dispersing for 30 minutes, adding 10 wt % of a silane coupling agent, stirring and mixing uniformly, heating to 85° C., and stirring and reacting for 3 hours.

[0026] The silane coupling agent in the present invention can be at least one of KH-550, KH-560, and KH-570. The embodiment of the present application does not limit the type of silane coupling agent, and it can be selected according to actual needs.

[0027] The following preparation conditions are all the preferred embodiments described above.

[0028] 2. The preparation method of the pour point depressant suitable for transporting crude oil of the present invention can be described in detail as follows: 2.1. A method for preparing a pour point depressant suitable for transporting crude oil, comprising the following steps: (1) dissolving oleic acid, long-chain α-olefin and methacrylamide in a mass ratio of (20-30): (40-60): (1-3) in mixed xylene, adding 0.1-0.5 wt% azobisisobutyronitrile, introducing nitrogen, and performing polymerization reaction at 65-120°C to obtain a terpolymer of oleic acid, long-chain α-olefin and methacrylamide, then adding 0.3-0.6 wt% p-toluenesulfonic acid and 1-8 wt% graphene oxide to the terpolymer of oleic acid, long-chain α-olefin and methacrylamide, performing grafting reaction at 120-170°C, and then vacuuming at 140-160°C to remove unreacted monomers to obtain a second component; (2) dissolving acrylate, fumaric acid and vinyl acetate in a mass ratio of (60-75): (2-3): (5-8) in toluene, adding 0.1-0.5 wt% azobisisobutyronitrile, introducing nitrogen, and carrying out polymerization reaction at 65-95°C to obtain a terpolymer of acrylate, fumaric acid and vinyl acetate, then adding 1-5 wt% nano-silica to the terpolymer of acrylate, fumaric acid and vinyl acetate, stirring at 150-170°C for 80-100 min, then hot washing with a mixed solution of ethanol and water (weight ratio of 1:1) at 60-80°C to remove unreacted monomers, and vacuuming at 140-160°C to remove the solvent to obtain a third component; (3) dissolving the first component, the second component, the third component and the fourth component in No. 150 solvent oil in a mass ratio of (1-5): (30-40): (35-50): (2-3) to obtain a pour point depressant suitable for transporting crude oil; The step of surface treating the nano-silica includes: adding the nano-silica to toluene, ultrasonically dispersing for 30 minutes, adding 10 wt% of a silane coupling agent, stirring and mixing evenly, heating to 85° C., and stirring and reacting for 3 hours.

[0029] 3. The preparation method of the pour point depressant suitable for transporting crude oil of the present invention can also be described in detail as follows: 3.1. A method for preparing a pour point depressant suitable for transporting crude oil, comprising the following steps: (1) Oleic acid, long-chain α-olefin and methacrylamide in a mass ratio of (20-30): (40-60): (1-3) are dissolved in mixed xylene, 0.1-0.5 wt% of azobisisobutyronitrile is added, nitrogen is introduced, and polymerization reaction is carried out at 93°C to obtain a terpolymer of oleic acid, long-chain α-olefin and methacrylamide, and then 0.3-0.6 wt% of p-toluenesulfonic acid and 1-8 wt% of graphene oxide are added to the terpolymer of oleic acid, long-chain α-olefin and methacrylamide, and grafting reaction is carried out at 145°C, followed by vacuuming at 150°C to remove unreacted monomers to obtain a second component; (2) Acrylate, fumaric acid and vinyl acetate in a mass ratio of (60-75): (2-3): (5-8) are dissolved in toluene, 0.1-0.5 wt% of azobisisobutyronitrile is added, nitrogen is introduced, and polymerization reaction is carried out at 80 ° C to obtain a terpolymer of acrylate, fumaric acid and vinyl acetate, and then 1-5 wt% of nano-silica is added to the terpolymer of acrylate, fumaric acid and vinyl acetate, and stirred at 160 ° C for 90 min, followed by hot washing with a mixed solution of ethanol and water (weight ratio of 1:1) at 70 ° C to remove unreacted monomers, and vacuuming at 150 ° C to remove the solvent to obtain a third component; (3) dissolving the first component, the second component, the third component and the fourth component in No. 150 solvent oil in a mass ratio of (1-5): (30-40): (35-50): (2-3) to obtain a pour point depressant suitable for transporting crude oil; The step of surface treating the nano-silica includes: adding the nano-silica to toluene, ultrasonically dispersing for 30 minutes, adding 10 wt% of KH-560, stirring and mixing evenly, heating to 85° C., and stirring and reacting for 3 hours.

[0030] The pour point depressants used in the following experimental examples were prepared according to the aforementioned method for preparing a pour point depressant suitable for transporting crude oil. The differences from the preparation conditions in 3.1 are listed in Tables 1 and 2 for Examples 1-8 and Comparative Examples 1-11. The following experimental examples can provide a reference for those having ordinary skill in the art to implement the present invention or verify its effectiveness.

[0031] Table 1 Preparation conditions of Examples 1 to 6

[0032] Table 2 Preparation conditions of Examples 7 to 8 and Comparative Examples 1 to 11

[0033] In Tables 1 and 2 above, in Example 1, the long-chain α-olefin is α-dodecene, the acrylate is lauryl acrylate, the amount of p-toluenesulfonic acid added is 0.3 wt %, and the amount of azobisisobutyronitrile added in steps (1) and (2) is 0.1 wt %; In Example 2, the long-chain α-olefin is α-tetradecene, the acrylate is tetradecyl acrylate, the amount of p-toluenesulfonic acid added is 0.6 wt %, and the amount of azobisisobutyronitrile added in steps (1) and (2) is 0.5 wt %; In Example 3, the long-chain α-olefin is α-hexadecene, the acrylate is hexadecyl acrylate, the amount of p-toluenesulfonic acid added is 0.4 wt %, and the amount of azobisisobutyronitrile added in steps (1) and (2) is 0.2 wt %; In Example 4, the long-chain α-olefin is α-octadecene, the acrylate is octadecyl acrylate, the amount of p-toluenesulfonic acid added is 0.5 wt %, and the amount of azobisisobutyronitrile added in steps (1) and (2) is 0.3 wt %; In Example 5, the long-chain α-olefins are α-dodecene and α-tetradecene (mass ratio of 1:1), the acrylates are dodecyl acrylate and tetradecyl acrylate (mass ratio of 1:1), the amount of p-toluenesulfonic acid added is 0.3 wt %, and the amount of azobisisobutyronitrile added in steps (1) and (2) is 0.4 wt %; In Example 6, the long-chain α-olefins are α-tetradecene and α-hexadecene (mass ratio of 1:1), the acrylates are tetradecyl acrylate and hexadecyl acrylate (mass ratio of 1:1), the amount of p-toluenesulfonic acid added is 0.3 wt %, and the amount of azobisisobutyronitrile added in steps (1) and (2) is 0.1 wt %; In Example 7, the long-chain α-olefins are α-hexadecene and α-octadecene (mass ratio of 1:1), the acrylates are hexadecyl acrylate and octadecyl acrylate (mass ratio of 1:1), the amount of p-toluenesulfonic acid added is 0.6 wt %, and the amount of azobisisobutyronitrile added in steps (1) and (2) is 0.5 wt %; In Example 8, the long-chain α-olefins are α-dodecene and α-octadecene (mass ratio of 1:1), the acrylates are lauryl acrylate and octadecyl acrylate (mass ratio of 1:1), the amount of p-toluenesulfonic acid added is 0.5 wt %, and the amount of azobisisobutyronitrile added in steps (1) and (2) is 0.3 wt %.

[0034] Using crude oil from a block in Africa as a sample, the pour point depressant effects of the pour point depressants in Examples 1 to 8 and Comparative Examples 1 to 11 were evaluated 15 days after addition according to the method in GB / T 510-2018. The results are shown in Table 3.

[0035] Table 3 Evaluation results of the pour point depressant effects of Examples 1 to 8 and Comparative Examples 1 to 11 15 days after addition of pour point depressants

[0036] From the data in Tables 1-3, it can be seen that the pour point depressants provided by the embodiments of the present invention (Examples 1 to 8) still have a good pour point depressing effect on crude oil 15 days after addition, indicating that their performance timeliness is good, and the pour point depressing effect 15 days after addition is better than the pour point depressants in Comparative Examples 1-11. Among them, the infrared spectrum of the second component in the pour point depressant suitable for transporting crude oil in Example 4 is detailed in Figure 1 The infrared spectrum of the third component in the pour point depressant for transporting crude oil in Example 4 is shown in Figure 2 .

[0037] The above description is merely an embodiment of the present application, and the scope of protection of the present application is not limited by these specific embodiments. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the technical ideas and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A pour point depressant suitable for transporting crude oil, characterized in that: comprising a first component, a second component, a third component and a fourth component; The first component is one or more of polyoxyethylene fatty alcohol ether, polyoxyethylene fatty alcohol ester and alkylphenol polyoxyethylene ether, and the molecular weight of the first component is 600 to 1600; The second component is a covalent graft product of a terpolymer of oleic acid, long-chain α-olefin and methacrylamide and graphene oxide, and the molecular weight of the second component is 3000 to 8000; The third component is a composite product of a terpolymer of acrylate, fumaric acid and vinyl acetate and nano-silicon dioxide, and the molecular weight of the third component is 3000 to 5000; The fourth component is one or more of sorbitan fatty acid ester, polyisobutenyl succinic anhydride derivative and ethylene glycol monobutyl ether; Wherein, the fatty chain length of the polyoxyethylene fatty alcohol ether is C12 to C24; The fatty chain length of the polyoxyethylene fatty alcohol ester is C12 to C18; The alkyl chain length of the alkylphenol polyoxyethylene ether is C8 to C12; The long-chain α-olefin is one or more of α-dodecene, α-tetradecene, α-hexadecene and α-octadecene; The mass ratio of the first component, the second component, the third component and the fourth component is (1-5): (30-40): (35-50): (2-3).

2. The pour point depressant suitable for transporting crude oil according to claim 1, characterized in that: The mass ratio of oleic acid, long-chain α-olefin and methacrylamide in the second component is (20-30): (40-60): (1-3); The amount of graphene oxide is 1 to 8% of the mass of the second component.

3. The pour point depressant suitable for transporting crude oil according to claim 1, characterized in that: The mass ratio of acrylate, fumaric acid and vinyl acetate in the third component is (60-75): (2-3): (5-8); The amount of the nano-silicon dioxide accounts for 1 to 5% of the mass of the third component.

4. A method for preparing a pour point depressant suitable for transporting crude oil, characterized in that: The method is used to prepare the pour point depressant suitable for transporting crude oil according to any one of claims 1 to 3, and the method comprises the following steps: (1) Oleic acid, long-chain α-olefin and methacrylamide in a mass ratio of (20-30): (40-60): (1-3) are dissolved in a light aromatic solvent, 0.1-0.5 wt% of an initiator is added, an inert gas is introduced, and a polymerization reaction is carried out at 65-120°C to obtain a terpolymer of oleic acid, long-chain α-olefin and methacrylamide, and then 0.3-0.6 wt% of p-toluenesulfonic acid and 1-8 wt% of graphene oxide as a second component are added to the terpolymer of oleic acid, long-chain α-olefin and methacrylamide, a grafting reaction is carried out at 120-170°C, and then vacuum is applied at 140-160°C to remove unreacted monomers to obtain a second component; (2) dissolving acrylate, fumaric acid and vinyl acetate in a mass ratio of (60-75): (2-3): (5-8) in toluene, adding 0.1-0.5 wt% of an initiator, introducing an inert gas, and carrying out a polymerization reaction at 65-95°C to obtain a terpolymer of acrylate, fumaric acid and vinyl acetate, then adding 1-5 wt% of nano-silica as a third component to the terpolymer of acrylate, fumaric acid and vinyl acetate, stirring at 150-170°C for 80-100 min, then hot washing with a mixed solution of ethanol and water at 60-80°C to remove unreacted monomers, and vacuuming at 140-160°C to remove the solvent to obtain a third component; (3) The first component, the second component, the third component and the fourth component are dissolved in a heavy aromatic hydrocarbon solvent in a mass ratio of (1-5): (30-40): (35-50): (2-3) to obtain a pour point depressant suitable for transporting crude oil.

5. The method for preparing a pour point depressant suitable for transporting crude oil according to claim 4, characterized in that: The acrylate is one or more of lauryl acrylate, tetradecyl acrylate, hexadecyl acrylate and octadecyl acrylate.

6. The method for preparing a pour point depressant suitable for transporting crude oil according to claim 4, characterized in that: The initiator is azobisisobutyronitrile; The light aromatic hydrocarbon solvent is benzene, toluene or mixed xylenes; The heavy aromatic hydrocarbon solvent is No. 150 solvent oil.

7. The method for preparing a pour point depressant suitable for transporting crude oil according to claim 4, characterized in that: The method further comprises the step of surface treating the nano-silicon dioxide; The surface treatment step comprises: adding nano-silica to toluene, ultrasonically dispersing for 20 to 40 minutes, adding 5 to 15 wt% of a silane coupling agent, stirring and mixing uniformly, heating to 80 to 90° C., and stirring and reacting for 2 to 4 hours; Wherein, the silane coupling agent is at least one of KH-550, KH-560 and KH-570.

8. Use of the pour point depressant suitable for transporting crude oil according to any one of claims 1 to 3 in crude oil transportation, characterized in that: The additive concentration is 2200ppm.

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