A pour point depressant for transporting crude oil and a preparation method and application thereof

Abstract

The application discloses a pour point depressant suitable for transporting crude oil and a preparation method and application thereof, and belongs to the technical field of oilfield 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 is 600-1600; the second component is a covalent grafting product of a terpolymer of oleic acid, long-chain alpha-olefin and methyl acrylamide and graphene oxide, and the molecular weight is 3000-8000; the third component is a composite product of a terpolymer of acrylic ester, fumaric acid and vinyl acetate and nano silicon dioxide, and the molecular weight is 3000-5000; and the fourth component is one or more of sorbitol anhydride fatty acid ester, polyisobutylene succinic anhydride derivative and ethylene glycol monobutyl ether. The pour point depressant solves the problem of poor time effectiveness of single-component pour point depressants, significantly improves the time effectiveness of the product, and makes the product adapt to the transportation requirements.

Description

TECHNICAL FIELD

[0001] The present application relates to a pour point depressant suitable for transporting crude oil and its preparation method and application, belonging to the technical field of oil field chemicals. BACKGROUND

[0002] Waxy crude oil has high condensation point and poor low-temperature fluidity, and has been transported by heating technology for a long time, but heating transportation has safety and economic problems. Since the 1960s, it has been found that adding a pour point depressant to waxy crude oil can effectively reduce the condensation point of the crude oil. For example, Chinese invention patent CN116426259B discloses a crude oil viscosity and pour point depressant and its preparation method, which realizes the purposes of reducing the condensation point of crude oil and improving the low-temperature viscosity of crude oil, and solves the problem of high viscosity caused by gum. Adding a pour point depressant to waxy crude oil to improve low-temperature fluidity has become a widely used, safe and economical waxy crude oil transportation technology, which plays a very important role in the safe operation and energy saving of waxy crude oil pipelines.

[0003] However, the current traditional pour point depressant has the limitation of poor performance timeliness, which leads to an increase in the condensation point of modified crude oil after adding the pour point depressant in the later stage of transportation, affecting the transportation effect. SUMMARY

[0004] The purpose of the present application is to provide a pour point depressant suitable for transporting crude oil and its preparation method and application, which has a synergistic promotion effect between components, solves the problem of poor timeliness of single-component pour point depressant, and significantly improves the performance timeliness of the product, making it suitable for transportation requirements.

[0005] To achieve the above purpose, the technical solution adopted by the present application is as follows:

[0006] According to one aspect of the present application, a pour point depressant suitable for transporting crude oil is provided, which comprises a first component, a second component, a third component and a fourth component;

[0007] 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;

[0008] The second component is a covalent grafting product of a ternary copolymer of oleic acid, long-chain alpha-olefin and methacrylamide and graphene oxide, and the molecular weight of the second component is 3000-8000;

[0009] The third component is a composite product of a ternary copolymer of acrylic ester, fumaric acid and vinyl acetate and nano-silicon dioxide, and the molecular weight of the third component is 3000-5000;

[0010] The fourth component is one or more of sorbitan fatty acid ester, polyisobutylene succinic anhydride derivative and ethylene glycol monobutyl ether;

[0011] The length of the fatty chain in the polyoxyethylene fatty alcohol ether is C12-C24.

[0012] The length of the fatty chain in the polyoxyethylene fatty alcohol ester is C12-C18.

[0013] The length of the alkyl chain in the alkylphenol polyoxyethylene ether is C8-C12.

[0014] The long-chain alpha-olefin is one or more of alpha-dodecene, alpha-tetradecene, alpha-hexadecene and alpha-octadecene.

[0015] 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).

[0016] Optionally, the mass ratio of the oleic acid, the long-chain alpha-olefin and the methacrylamide in the second component is (20-30):(40-60):(1-3).

[0017] The amount of the graphene oxide accounts for 1-8% of the mass of the second component.

[0018] Optionally, the mass ratio of the acrylate, the fumaric acid and the vinyl acetate in the third component is (60-75):(2-3):(5-8).

[0019] The amount of the nano-silicon dioxide accounts for 1-5% of the mass of the third component.

[0020] According to another aspect of the present application, a preparation method of a pour point depressant for transporting crude oil is provided, which is used to prepare any of the pour point depressants for transporting crude oil described above, and the method comprises the following steps:

[0021] (1) oleic acid, long-chain alpha-olefin and methacrylamide with a mass ratio of (20-30):(40-60):(1-3) are dissolved in a light aromatic hydrocarbon solvent, 0.1-0.5wt% initiator is added, inert gas is introduced, and polymerization reaction is carried out at 65-120℃ to obtain a terpolymer of oleic acid, long-chain alpha-olefin and methacrylamide, then 0.3-0.6wt% p-toluenesulfonic acid and 1-8wt% graphene oxide of the second component are added to the terpolymer of oleic acid, long-chain alpha-olefin and methacrylamide, and grafting reaction is carried out at 120-170℃, followed by vacuumizing at 140-160℃ to remove unreacted monomers, and the second component is obtained;

[0022] (2) Dissolve the acrylic ester, fumaric acid and vinyl acetate in a mass ratio of (60-75):(2-3):(5-8) in toluene, add 0.1-0.5wt% initiator, and introduce inert gas, and conduct polymerization reaction at 65-95℃ to obtain a terpolymer of acrylic ester, fumaric acid and vinyl acetate, then add 1-5wt% of the third component of nano-silica to the terpolymer of acrylic ester, fumaric acid and vinyl acetate, and stir at 150-170℃ for 80-100min, then conduct hot washing with a mixed solution of ethanol and water at 60-80℃ to remove unreacted monomers, and conduct vacuum extraction at 140-160℃ to remove the solvent, and obtain the third component;

[0023] (3) Dissolve the first component, the second component, the third component and the fourth component in heavy aromatic hydrocarbon solvent according to a mass ratio of (1-5):(30-40):(35-50):(2-3) to obtain a pour point depressant suitable for transporting crude oil.

[0024] Optionally, the acrylic ester is one or more of dodecyl acrylate, tetradecyl acrylate, hexadecyl acrylate and octadecyl acrylate.

[0025] Optionally, the initiator is azobisisobutyronitrile.

[0026] The light aromatic hydrocarbon solvent is benzene, toluene or mixed xylene.

[0027] The heavy aromatic hydrocarbon solvent is No. 150 solvent oil.

[0028] Optionally, the method further comprises a step of surface treatment of the nano-silica.

[0029] The step of surface treatment comprises: adding nano-silica into toluene, ultrasonic dispersion for 20-40min, adding 5-15wt% of silane coupling agent, stirring and mixing uniformly, heating to 80-90℃, and stirring and reacting for 2-4h.

[0030] The silane coupling agent is at least one of KH-550, KH-560 and KH-570.

[0031] According to still another aspect of the present application, the pour point depressant suitable for transporting crude oil is applied in the transportation of crude oil, and the additive concentration is 2200ppm.

[0032] The beneficial effects of the present application include but are not limited to:

[0033] 1. The pour point depressant suitable for transporting crude oil of the present application, the first component, the second component, the third component and the fourth component synergistically act, solve the problem of poor time effectiveness of single-component pour point depressant, significantly improve the time effectiveness of product performance, and make it adapt to transportation requirements.

[0034] 2. The pour point depressant of the present application for transporting crude oil, the long chain alkyl in the first component is a hydrophobic group, the polyoxyethylene chain is a hydrophilic group, the hydrophobic group and the hydrophilic group synergistically interfere with the formation and growth of wax in the crude oil, thereby reducing the pour point of the crude oil.

[0035] 3. The pour point depressant of the present application for transporting crude oil, the covalent grafting product of the terpolymer of oleic acid, long chain alpha-olefin and methacrylamide and graphene oxide, the molecules can insert into the crystal lattice of wax crystal, interfere with the regular arrangement of wax crystal, destroy the ordered crystal structure, reduce the interaction and entanglement between the wax crystals, thereby reducing the pour point of the crude oil.

[0036] 4. The pour point depressant of the present application for transporting crude oil, the terpolymer of acrylic ester, fumaric acid and vinyl acetate in the third component has a comb structure, the main chain and branched chain carbon chain length is similar to the length of paraffin carbon chain, thereby changing the crystallization state of paraffin in the crude oil, making it not easy to form a space network structure, significantly reducing the pour point of the crude oil; nano silicon dioxide can weaken the structural strength of the wax crystal, improve the low temperature fluidity of the waxy crude oil, the dynamic and static aging stability is good, the shear resistance is improved, can significantly improve the performance aging of the product, making it suitable for transportation requirements.

[0037] 5. The pour point depressant of the present application for transporting crude oil, the fourth component can increase the interaction between the pour point depressant and the crude oil, improve the pour point depression effect of the pour point depressant. BRIEF DESCRIPTION OF DRAWINGS

[0038] The drawings described herein are intended to provide a further understanding of the present application, form a part of the present application, the illustrative embodiments of the present application and the description thereof are used to explain the present application, and do not constitute improper limitation on the present application. In the drawings:

[0039] Figure 1 The infrared spectrum of the second component in the pour point depressant for transporting crude oil of the present application embodiment 4.

[0040] Figure 2 The infrared spectrum of the third component in the pour point depressant for transporting crude oil of the present application embodiment 4. DETAILED DESCRIPTION

[0041] The endpoints of the ranges and any values described herein are not limited to the precise values stated. The ranges and values should be construed to be approximations that are understood to include values approximating these ranges and values. For ranges, the endpoints are included in the ranges, and the ranges are inclusive of the single points. The single points are included in the ranges, and the ranges are inclusive of the single points. The ranges and values are understood to be approximations that are understood to include values approximating these ranges and values.

[0042] Unless otherwise specified in the examples, the procedures were carried out under conventional conditions or according to the manufacturer's instructions. Unless otherwise specified, the raw materials or instruments used were conventional products available on the market.

[0043] 1. A pour point depressant for transporting crude oil and a preparation method thereof

[0044] 1.1. The present application provides a pour point depressant for transporting crude oil, comprising a first component, a second component, a third component and a fourth component;

[0045] 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;

[0046] The second component is a covalent grafting 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 3000-8000;

[0047] The third component is a composite product of a terpolymer of acrylic ester, fumaric acid and vinyl acetate and nano-silica, and the molecular weight of the third component is 3000-5000;

[0048] The fourth component is one or more of sorbitan fatty acid ester, polyisobutylene succinic anhydride derivative and ethylene glycol monobutyl ether.

[0049] Among them, the length of the fatty chain in the polyoxyethylene fatty alcohol ether is C12-C24; the length of the fatty chain in the polyoxyethylene fatty alcohol ester is C12-C18; the length of the alkyl chain in the 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 acrylic ester, fumaric acid and vinyl acetate in the third component is (60-75):(2-3):(5-8); the amount of nano-silica accounts for 1-5% of the mass of the third component.

[0050] 1.2. The preparation method of the pour point depressant for transporting crude oil comprises the following steps:

[0051] (1) Dissolve oleic acid, long-chain alpha-olefin and methacrylamide in a light aromatic hydrocarbon solvent in a mass ratio of (20-30):(40-60):(1-3), add 0.1-0.5wt% initiator, and pass in inert gas to carry out polymerization reaction at 65-120℃ to obtain a terpolymer of oleic acid, long-chain alpha-olefin and methacrylamide, then add 0.3-0.6wt% p-toluenesulfonic acid and 1-8wt% graphene oxide to the terpolymer of oleic acid, long-chain alpha-olefin and methacrylamide, and carry out grafting reaction at 120-170℃, followed by vacuum extraction at 140-160℃ to remove unreacted monomers, to obtain the second component;

[0052] (2) Dissolve acrylic ester, fumaric acid and vinyl acetate in toluene in a mass ratio of (60-75):(2-3):(5-8), add 0.1-0.5wt% initiator, and pass in inert gas to carry out polymerization reaction at 65-95℃ to obtain a terpolymer of acrylic ester, fumaric acid and vinyl acetate, then add 1-5wt% nanosilica to the terpolymer of acrylic ester, fumaric acid and vinyl acetate, and stir at 150-170℃ for 80-100min, followed by hot washing with a mixed solution of ethanol and water (weight ratio 1:1) at 60-80℃ to remove unreacted monomers, and vacuum extraction at 140-160℃ to remove the solvent, to obtain the third component;

[0053] (3) Dissolve the first component, the second component, the third component and the fourth component in 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.

[0054] The long-chain alpha-olefin is one or more of alpha-dodecene, alpha-tetradecene, alpha-hexadecene and alpha-octadecene, preferably alpha-octadecene;

[0055] The acrylic ester is one or more of dodecyl acrylate, tetradecyl acrylate, hexadecyl acrylate and octadecyl acrylate, preferably octadecyl acrylate;

[0056] The initiator is azobisisobutyronitrile;

[0057] The light aromatic hydrocarbon solvent is benzene, toluene or mixed xylene, preferably mixed xylene;

[0058] The heavy aromatic hydrocarbon solvent is 150# solvent oil;

[0059] It also includes a step of surface treatment of nanosilica;

[0060] The surface treatment step comprises: adding nano-silica into toluene, ultrasonic dispersion for 20-40 min, adding 5-15 wt% silane coupling agent, stirring and mixing uniformly, heating to 80-90℃, and stirring and reacting for 2-4 h.

[0061] Preferably, the step of surface treatment of nano-silica comprises: adding nano-silica into toluene, ultrasonic dispersion for 30 min, adding 10 wt% silane coupling agent, stirring and mixing uniformly, heating to 85℃, and stirring and reacting for 3 h.

[0062] The silane coupling agent in the present application can be at least one of KH-550, KH-560 and KH-570, and the type of the silane coupling agent is not limited in the embodiments of the present application and can be selected according to actual needs.

[0063] The preparation conditions described below are the preferred embodiments described above.

[0064] 2. The preparation method of the pour point depressant for transporting crude oil according to the present application can be described in detail as follows:

[0065] 2.1. A preparation method of a pour point depressant for transporting crude oil, comprising the following steps:

[0066] (1) Dissolving oleic acid, long-chain α-olefin and methyl acrylamide with a mass ratio of (20-30):(40-60):(1-3) in mixed xylene, adding 0.1-0.5 wt% azobisisobutyronitrile, passing nitrogen, and performing polymerization reaction at 65-120℃ to obtain a terpolymer of oleic acid, long-chain α-olefin and methyl acrylamide, 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 methyl acrylamide, and performing grafting reaction at 120-170℃, followed by vacuumizing at 140-160℃ to remove unreacted monomers, to obtain a second component;

[0067] (2) Dissolving acrylic ester, fumaric acid and vinyl acetate with a mass ratio of (60-75):(2-3):(5-8) in toluene, adding 0.1-0.5 wt% azobisisobutyronitrile, passing nitrogen, and performing polymerization reaction at 65-95℃ to obtain a terpolymer of acrylic ester, fumaric acid and vinyl acetate, then adding 1-5 wt% nano-silica to the terpolymer of acrylic ester, fumaric acid and vinyl acetate, stirring at 150-170℃ for 80-100 min, then performing hot washing with a mixed solution of ethanol and water (weight ratio 1:1) at 60-80℃ to remove unreacted monomers, and vacuumizing at 140-160℃ to remove solvents, to obtain a third component;

[0068] (3) the first component, the second component, the third component and the fourth component are dissolved in No. 150 solvent oil according to a mass ratio of (1-5):(30-40):(35-50):(2-3), so that a pour point depressant suitable for transporting crude oil is obtained;

[0069] The step of surface treatment of the nano-silicon dioxide comprises the following steps: the nano-silicon dioxide is added into toluene, ultrasonic dispersion is performed for 30 min, 10 wt% of the silane coupling agent is added, stirring and mixing are uniformly performed, temperature is raised to 85 DEG C, and stirring reaction is performed for 3 h.

[0070] 3, the preparation method of the pour point depressant suitable for transporting crude oil can be described in detail as follows:

[0071] 3.1, a preparation method of a pour point depressant suitable for transporting crude oil, comprising the following steps:

[0072] (1) the oleic acid, the long-chain alpha-olefin and the methacrylamide are dissolved in mixed xylene according to a mass ratio of (20-30):(40-60):(1-3), 0.1-0.5 wt% of azobisisobutyronitrile is added, nitrogen is introduced, polymerization reaction is performed at 93 DEG C, so that a terpolymer of the oleic acid, the long-chain alpha-olefin and the methacrylamide is obtained, then 0.3-0.6 wt% of p-toluenesulfonic acid and 1-8 wt% of graphene oxide are added into the terpolymer of the oleic acid, the long-chain alpha-olefin and the methacrylamide, grafting reaction is performed at 145 DEG C, then vacuumization is performed at 150 DEG C, so that unreacted monomers are removed, and the second component is obtained;

[0073] (2) the acrylate, the fumaric acid and the vinyl acetate are dissolved in toluene according to a mass ratio of (60-75):(2-3):(5-8), 0.1-0.5 wt% of azobisisobutyronitrile is added, nitrogen is introduced, polymerization reaction is performed at 80 DEG C, so that a terpolymer of the acrylate, the fumaric acid and the vinyl acetate is obtained, then 1-5 wt% of nano-silicon dioxide is added into the terpolymer of the acrylate, the fumaric acid and the vinyl acetate, stirring is performed at 160 DEG C for 90 min, then hot washing is performed on the terpolymer of the acrylate, the fumaric acid and the vinyl acetate by using a mixed solution of ethanol and water (weight ratio 1:1) at 70 DEG C, so that unreacted monomers are removed, and vacuumization is performed at 150 DEG C, so that the solvent is removed, and the third component is obtained;

[0074] (3) the first component, the second component, the third component and the fourth component are dissolved in No. 150 solvent oil according to a mass ratio of (1-5):(30-40):(35-50):(2-3), so that a pour point depressant suitable for transporting crude oil is obtained;

[0075] The step of surface treatment of the nano-silicon dioxide comprises the following steps: the nano-silicon dioxide is added into toluene, ultrasonic dispersion is performed for 30 min, 10 wt% of the silane coupling agent is added, stirring and mixing are uniformly performed, temperature is raised to 85 DEG C, and stirring reaction is performed for 3 h.

[0076] The pour point depressants used in the following experimental examples were prepared according to the above-described method for preparing a pour point depressant for transporting crude oil, with the differences in the preparation conditions of Examples 1 to 6 of Table 1 and Examples 7 to 8 and Comparative Examples 1 to 11 of Table 2 being listed in Tables 1 and 2. The following experimental examples can provide a reference for implementing the present application or verifying the effect for those having ordinary skills in the art.

[0077] Preparation conditions of Examples 1 to 6 of Table 1

[0078]

[0079] Preparation conditions of Examples 7 to 8 and Comparative Examples 1 to 11 of Table 2

[0080]

[0081] In Example 1 of the above Tables 1 and 2, the long-chain α-olefin is α-dodecene, the acrylate is dodecyl 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% each;

[0082] 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% each;

[0083] 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% each;

[0084] 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% each;

[0085] In Example 5, the long-chain α-olefins are α-dodecene and α-tetradecene (mass ratio 1:1), the acrylates are dodecyl acrylate and tetradecyl acrylate (mass ratio 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% each;

[0086] In Example 6, the long-chain α-olefins are α-tetradecene and α-hexadecene (mass ratio 1:1), the acrylates are tetradecyl acrylate and hexadecyl acrylate (mass ratio 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% each;

[0087] The long-chain α-olefin in Example 7 is α-hexadecene and α-octadecene (mass ratio 1:1), the acrylate is hexadecyl acrylate and octadecyl acrylate (mass ratio 1:1), the addition amount of p-toluenesulfonic acid is 0.6wt%, and the addition amount of azobisisobutyronitrile in steps (1) and (2) is 0.5wt% each;

[0088] The long-chain α-olefin in Example 8 is α-dodecene and α-octadecene (mass ratio 1:1), the acrylate is dodecyl acrylate and octadecyl acrylate (mass ratio 1:1), the addition amount of p-toluenesulfonic acid is 0.5wt%, and the addition amount of azobisisobutyronitrile in steps (1) and (2) is 0.3wt% each.

[0089] The pour point depressing effect of the pour point depressants in Examples 1-8 and Comparative Examples 1-11 after 15 days of dosing was evaluated below using crude oil from a certain block in Africa as a sample, and the method in GB / T 510-2018 was used, and the results are shown in Table 3.

[0090] Table 3 Evaluation results of pour point depressing effect of the pour point depressants in Examples 1-8 and Comparative Examples 1-11 after 15 days of dosing

[0091]

[0092] As can be seen from the data in Tables 1-3, the pour point depressants provided in Examples 1-8 (Examples 1-8) still have good pour point depressing effect on crude oil after 15 days of dosing, indicating that they have good performance timeliness, and the pour point depressing effect after 15 days of dosing is better than that of the pour point depressants in Comparative Examples 1-11. The infrared spectrum of the second component of the pour point depressant for transporting crude oil in Example 4 is shown in Figure 1 , and the infrared spectrum of the third component of the pour point depressant for transporting crude oil in Example 4 is shown in Figure 2 .

[0093] The above is only an embodiment of the present application, and the protection scope of the present application is not limited by these specific embodiments. Various modifications and changes can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the technical idea and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A pour point depressant suitable for use in transporting crude oil, characterized in that, The first component, the second component, the third component and the fourth component; The first component is one or more of polyoxyethylene fatty alcohol ether, polyoxyethylene fatty alcohol ester and alkylphenol polyoxyethylene ether, the molecular weight of the first component is 600-1600; the second component is a covalent grafting product of a terpolymer of oleic acid, long-chain alpha-olefin and methacrylamide and graphene oxide, the molecular weight of the second component is 3000-8000; the third component is a composite product of a terpolymer of acrylate, fumaric acid and vinyl acetate and nano-silica, the molecular weight of the third component is 3000-5000; The fourth component is one or more of sorbitan fatty acid ester, polyisobutylene succinic anhydride derivative and ethylene glycol monobutyl ether; The length of the fatty chain in the polyoxyethylene fatty alcohol ether is C12-C24; The length of the fatty chain in the polyoxyethylene fatty alcohol ester is C12-C18; The length of the alkyl chain in the alkylphenol polyoxyethylene ether is C8-C12; The long-chain alpha-olefin is one or more of alpha-dodecene, alpha-tetradecene, alpha-hexadecene and alpha-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); The mass ratio of oleic acid, long-chain alpha-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 nano-silica accounts for 1-5% of the mass of the third component; The acrylate is one or more of lauryl acrylate, myristyl acrylate, cetyl acrylate and stearyl acrylate; The method further comprises a step of surface treatment of the nano-silica; The step of surface treatment comprises: adding nano-silica into toluene, ultrasonic dispersion for 20-40 min, adding 5-15 wt% of silane coupling agent, stirring and mixing uniformly, heating to 80-90℃, stirring and reacting for 2-4 h.

2. The pour point depressant suitable for use in transporting crude oil according to claim 1, wherein, The silane coupling agent is at least one of KH-550, KH-560 and KH-570.

3. A process for the preparation of a pour point depressant suitable for use in the transportation of crude oil, characterised in that, The method is used for preparing the pour point depressant for transporting crude oil according to any one of claims 1-2, and the method comprises the following steps: (1) the oleic acid, long-chain alpha-olefin and methyl acrylamide are dissolved in a light aromatic hydrocarbon solvent in a mass ratio of (20-30):(40-60):(1-3), 0.1-0.5wt% initiator is added, inert gas is introduced, and polymerization reaction is carried out at 65-120℃ to obtain a terpolymer of oleic acid, long-chain alpha-olefin and methyl acrylamide, then 0.3-0.6wt% p-toluenesulfonic acid and 1-8wt% graphene oxide of the second component are added to the terpolymer of oleic acid, long-chain alpha-olefin and methyl acrylamide, and grafting reaction is carried out at 120-170℃, followed by vacuum extraction at 140-160℃ to remove unreacted monomers, to obtain the second component; (2) the acrylic ester, fumaric acid and vinyl acetate are dissolved in toluene in a mass ratio of (60-75):(2-3):(5-8), 0.1-0.5wt% initiator is added, inert gas is introduced, and polymerization reaction is carried out at 65-95℃ to obtain a terpolymer of acrylic ester, fumaric acid and vinyl acetate, then 1-5wt% nano-silicon dioxide of the third component is added to the terpolymer of acrylic ester, fumaric acid and vinyl acetate, stirring is carried out at 150-170℃ for 80-100min, then hot washing is carried out at 60-80℃ using a mixed solution of ethanol and water to remove unreacted monomers, and vacuum extraction is carried out at 140-160℃ to remove the solvent, to obtain the 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.

4. The process for the preparation of a pour point depressant suitable for use in the transportation of crude oil according to claim 3, characterized in that, The initiator is azobisisobutyronitrile; The light aromatic hydrocarbon solvent is benzene, toluene or mixed xylene; The heavy aromatic hydrocarbon solvent is No. 150 solvent oil.

5. Use of the pour point depressant according to any one of claims 1 to 2 for the transportation of crude oil, characterized in that, The additive concentration is 2200ppm.

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