Pipe transportation crude oil pour point depressant as well as preparation method and application thereof

Abstract

The invention discloses a tubing crude oil pour point depressant 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 a terpolymer of ethylene, acrylate and vinyl acetate; the second component is an amination product of a quadripolymer of maleic anhydride, vinyl imidazole, acrylamide and methacrylate; the third component is a polyether compound of ethylene oxide, propylene oxide and Guerbet alcohol; and the fourth component is one or more of polymethylsilsesquioxane, sorbitan fatty acid ester, a polyisobutylene succinic anhydride derivative and ethylene glycol monobutyl ether. The problem of limitation of a single-component pour point depressant is solved, so that the pour point depressant is wider in application range, the condensation point of crude oil is remarkably reduced, the low-temperature fluidity of the crude oil is effectively improved, and the high-condensation-point crude oil is convenient to exploit and transport.

Description

Technical Field

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

[0002] Crude oil, a vital petroleum resource, contains a significant amount of easily crystallized substances, such as colloids, asphaltenes, and paraffin. Newly mined crude oil exhibits increasingly higher parameters, including its freezing point, wax content, and viscosity. During crude oil transportation, crystallization begins when the temperature drops below its wax precipitation point. Further temperature reduction increases the amount of crystallized crude oil, ultimately causing it to lose fluidity and solidify on the pipe wall. This poses significant challenges to crude oil extraction and transportation.

[0003] As a commonly used chemical additive, pour point depressants are widely used in crude oil extraction and transportation processes. They can effectively improve the fluidity of crude oil and reduce the transportation cost and risk of crude oil. Common crude oil pour point depressants mainly include ethylene-vinyl acetate copolymers, styrene-maleic anhydride copolymers and acrylic polymers. For example, Chinese invention patent CN105567353B discloses a modified ethylene-vinyl acetate copolymer pour point depressant: a surface-polymerized ethylene-vinyl acetate copolymer is then mixed with polycaprolactone to obtain this product. The application of these pour point depressants has been very effective in some areas, but there are differences in the composition of crude oil in various regions, resulting in crude oil being selective for pour point depressants. The applicability of a single type of pour point depressant is poor, and it is difficult to meet the pour point reduction requirements. This limits the use of existing crude oil pour point depressants and makes it difficult to achieve large-scale promotion and application. Summary of the Invention

[0004] The purpose of the present invention is to provide a pour point depressant for pipeline crude oil, a preparation method thereof, and an application thereof, so as to overcome the limitations of single-component pour point depressants, expand their application range, significantly reduce the pour point of crude oil, effectively improve the low-temperature fluidity of crude oil, and facilitate the extraction and transportation of high-pour point crude oil.

[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, a pour point depressant for pipeline crude oil is provided, comprising a first component, a second component, a third component and a fourth component; The first component is a terpolymer of ethylene, acrylic acid ester and vinyl acetate, and the molecular weight of the first component is 10,000-15,000; The second component is an amination product of a tetrapolymer of maleic anhydride, vinylimidazole, acrylamide and methacrylate, and the molecular weight of the second component is 8000-12000; The third component is a polyether compound of ethylene oxide, propylene oxide and Guerbet alcohol, and the molecular weight of the third component is 3000-8000; The fourth component is one or more of polymethylsilsesquioxane, sorbitan fatty acid ester, polyisobutenyl succinic anhydride derivative and ethylene glycol monobutyl ether.

[0006] Optionally, the mass ratio of the first component, the second component, the third component and the fourth component is (10-15): (35-55): (5-10): (1-5).

[0007] Optionally, the mass ratio of ethylene, acrylic acid ester and vinyl acetate in the first component is (50-65): (5-8): (15-45).

[0008] Optionally, the mass ratio of maleic anhydride, vinylimidazole, acrylamide and methacrylate in the second component is (10-15): (2-3): (1-2): (30-50).

[0009] Optionally, the mass ratio of ethylene oxide, propylene oxide and Guerbet alcohol in the third component is (20-30): (40-50): (1-10).

[0010] According to another aspect of the present application, a method for preparing a pour point depressant for pipeline crude oil is provided. The method is used to prepare any of the above-mentioned pour point depressants for pipeline crude oil, and the method comprises the following steps: (1) Adding acrylate, vinyl acetate, initiator and light aromatic solvent into a high-pressure reactor, raising the temperature to 80-150°C, introducing ethylene gas for reaction, wherein the mass ratio of ethylene, acrylate and vinyl acetate is (50-65): (5-8): (15-45); then hot washing with ethanol at 50-70°C to remove unreacted monomers, and then vacuuming at 150-170°C to remove the solvent to obtain the first component; (2) maleic anhydride, vinylimidazole, acrylamide and methacrylate in a mass ratio of (10-15): (2-3): (1-2): (30-50) are dissolved in a light aromatic hydrocarbon solvent, azobisisobutyronitrile is added, and a polymerization reaction is carried out at 60-90°C under the protection of nitrogen to obtain a tetrapolymer of maleic anhydride, vinylimidazole, acrylamide and methacrylate; then the tetrapolymer of maleic anhydride, vinylimidazole, acrylamide and methacrylate is mixed with amine and an amination reaction is carried out at 100-160°C; then, a mixed solution of methanol and water in a weight ratio of 1:1 is first hot washed at 60-80°C to remove unreacted monomers, and then vacuumed at 140-160°C to remove the solvent to obtain the second component; (3) adding Guerbet alcohol and a catalyst to a high-pressure reactor, raising the temperature to 110-130° C., introducing propylene oxide and ethylene oxide to react, wherein the mass ratio of ethylene oxide, propylene oxide, and Guerbet alcohol is (20-30):(40-50):(1-10); then applying vacuum at 120-150° C. to remove unreacted monomers, thereby obtaining the third component; (4) 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 (10-15): (35-55): (5-10): (1-5) to obtain the pipeline crude oil pour point depressant.

[0011] Optionally, the acrylate is one or more of lauryl acrylate, tetradecyl acrylate, hexadecyl acrylate and octadecyl acrylate; The methacrylate is one or more of lauryl methacrylate, tetradecyl methacrylate, hexadecyl methacrylate and octadecyl methacrylate; The amine is one or more of dodecylamine, tetradecylamine, hexadecylamine and octadecylamine; The Guerbet alcohol is one or more of Guerbet dodecanol, Guerbet tetradecanol, Guerbet hexadecanol and Guerbet octadecanol; The initiator is at least one selected from benzoyl peroxide, lauroyl peroxide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide and di-tert-butyl peroxide; The light aromatic hydrocarbon solvent is benzene, toluene or xylene; The catalyst is sodium hydroxide and / or potassium hydroxide; The heavy aromatic hydrocarbon solvent is No. 150 solvent oil.

[0012] Optionally, the initiator is added in an amount of 0.1 to 0.5 wt %; The addition amount of the azobisisobutyronitrile is 0.1 to 0.5 wt %; The molar ratio of the amine to maleic anhydride is (1-2):1; The added amount of the catalyst is 0.3-0.6 wt %.

[0013] According to another aspect of the present application, there is provided a use of any of the above-mentioned pour point depressants for pipeline crude oil in lowering the freezing point of crude oil, wherein the dosage of the pour point depressant for pipeline crude oil is 1700-1900 ppm.

[0014] The beneficial effects of this application include but are not limited to: 1. The pipeline crude oil pour point depressant of this application comprises the first, second, third, and fourth components, which work synergistically to overcome the limitations of single-component pour point depressants. A small amount of addition can significantly lower the pour point of crude oil, improve its low-temperature fluidity, and facilitate its extraction and transportation.

[0015] 2. The pipeline crude oil pour point depressant disclosed herein utilizes ethylene-vinyl acetate copolymer modified with acrylic acid esters. The resulting first component has a uniformly distributed polar portion, and its long-chain structure can interact with wax crystals in high-pour point crude oil. Furthermore, the acrylic acid ester structure has a high polarity, which can better adjust the wax crystal structure and lower the pour point of crude oil.

[0016] 3. The pour point depressant for pipeline crude oil disclosed herein is an amination product of a tetrapolymer of maleic anhydride, vinylimidazole, acrylamide, and methacrylate. It exhibits a comb-like structure, with the carbon chain lengths of its main and side chains similar to those of paraffin wax. This structure alters the crystallization of paraffin wax in crude oil, preventing it from forming a spatial network structure and significantly lowering the pour point of crude oil.

[0017] 4. The pour point depressant for pipeline crude oil disclosed in this application contains polar ether bonds in a polyether compound of ethylene oxide, propylene oxide, and Guerbet alcohols. These compounds adsorb onto the surface of wax crystals, preventing further aggregation of wax molecules into large crystals and maintaining finely dispersed wax crystals. These molecules can also insert into the wax crystal lattice, disrupting their regular arrangement and the orderly crystal structure, thereby reducing interactions and entanglement between wax crystals and lowering the freezing point of crude oil.

[0018] 5. The pour point depressant for pipeline crude oil of the present application, polymethylsilsesquioxane, sorbitan fatty acid ester, polyisobutenyl succinic anhydride derivative, and ethylene glycol monobutyl ether can enhance the interaction between the pour point depressant and crude oil, thereby improving the pour point depressant effect of the pour point depressant. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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 first component in the pour point depressant for pipeline crude oil in Example 3 of the present application.

[0020] Figure 2 This is the infrared spectrum of the second component in the pour point depressant for pipeline crude oil in Example 3 of the present application.

[0021] Figure 3 This is the infrared spectrum of the third component in the pour point depressant for pipeline crude oil in Example 3 of the present application. DETAILED DESCRIPTION

[0022] 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.

[0023] 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.

[0024] 1. A pour point depressant for pipeline crude oil and its preparation method 1.1. The present invention provides a pour point depressant for pipeline crude oil, comprising a first component, a second component, a third component, and a fourth component; The first component is a terpolymer of ethylene, acrylic acid ester and vinyl acetate, and the molecular weight of the first component is 10,000-15,000; The second component is an amination product of a tetrapolymer of maleic anhydride, vinylimidazole, acrylamide and methacrylate, and the molecular weight of the second component is 8000-12000; The third component is a polyether compound of ethylene oxide, propylene oxide and Guerbet alcohol, and the molecular weight of the third component is 3000-8000; The fourth component is one or more of polymethylsilsesquioxane, sorbitan fatty acid ester, polyisobutenyl succinic anhydride derivative and ethylene glycol monobutyl ether.

[0025] Among them, the mass ratio of the first component, the second component, the third component and the fourth component is (10-15): (35-55): (5-10): (1-5); the mass ratio of ethylene, acrylic acid ester and vinyl acetate in the first component is (50-65): (5-8): (15-45); the mass ratio of maleic anhydride, vinylimidazole, acrylamide and methacrylate in the second component is (10-15): (2-3): (1-2): (30-50); the mass ratio of ethylene oxide, propylene oxide and Guerbet alcohol in the third component is (20-30): (40-50): (1-10).

[0026] 1.2. The preparation method of the above-mentioned pour point depressant for pipeline crude oil comprises the following steps: (1) Adding acrylate, vinyl acetate, initiator and light aromatic solvent into a high-pressure reactor, raising the temperature to 80-150°C, introducing ethylene gas for reaction, wherein the mass ratio of ethylene, acrylate and vinyl acetate is (50-65): (5-8): (15-45); then hot washing with ethanol at 50-70°C to remove unreacted monomers, and then vacuuming at 150-170°C to remove the solvent to obtain the first component; (2) maleic anhydride, vinylimidazole, acrylamide and methacrylate in a mass ratio of (10-15): (2-3): (1-2): (30-50) are dissolved in a light aromatic hydrocarbon solvent, azobisisobutyronitrile is added, and a polymerization reaction is carried out at 60-90°C under the protection of nitrogen to obtain a tetrapolymer of maleic anhydride, vinylimidazole, acrylamide and methacrylate; then the tetrapolymer of maleic anhydride, vinylimidazole, acrylamide and methacrylate is mixed with amine, and the molar ratio of amine to maleic anhydride is (1-2): 1, and an amination reaction is carried out at 100-160°C; then, a mixed solution of methanol and water in a weight ratio of 1:1 is first hot washed at 60-80°C to remove unreacted monomers, and then vacuumed at 140-160°C to remove the solvent to obtain the second component; (3) adding Guerbet alcohol and a catalyst to a high-pressure reactor, raising the temperature to 110-130° C., introducing propylene oxide and ethylene oxide to react, wherein the mass ratio of ethylene oxide, propylene oxide, and Guerbet alcohol is (20-30):(40-50):(1-10); then applying vacuum at 120-150° C. to remove unreacted monomers, thereby obtaining the third component; (4) 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 (10-15): (35-55): (5-10): (1-5) to obtain a pipeline crude oil pour point depressant.

[0027] Wherein, the acrylate is one or more of lauryl acrylate, tetradecyl acrylate, hexadecyl acrylate and octadecyl acrylate, preferably octadecyl acrylate; The methacrylate is one or more of lauryl methacrylate, tetradecyl methacrylate, hexadecyl methacrylate and octadecyl methacrylate, preferably octadecyl methacrylate; The amine is one or more of dodecylamine, tetradecylamine, hexadecylamine and octadecylamine, preferably octadecylamine; The Guerbet alcohol is one or more of Guerbet dodecanol, Guerbet tetradecanol, Guerbet hexadecanol and Guerbet octadecanol, preferably Guerbet hexadecanol; The initiator is at least one selected from benzoyl peroxide, lauroyl peroxide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide and di-tert-butyl peroxide, preferably benzoyl peroxide; The light aromatic solvent is benzene, toluene or xylene, preferably xylene; The catalyst is sodium hydroxide and / or potassium hydroxide, preferably sodium hydroxide; The heavy aromatic solvent is No. 150 solvent oil.

[0028] The amount of initiator added is 0.1-0.5wt%, preferably 0.3wt%; The addition amount of azobisisobutyronitrile is 0.1 to 0.5 wt%, preferably 0.3 wt%; The molar ratio of amine to maleic anhydride is (1-2):1, preferably 1:1; The amount of catalyst added is 0.3-0.6 wt%, preferably 0.4 wt%.

[0029] 2. The preparation method of the pipeline crude oil pour point depressant of the present invention can be described in detail as follows: 2.1. A method for preparing a pour point depressant for pipeline crude oil, comprising the following steps: (1) Adding octadecyl acrylate, vinyl acetate, 0.3 wt% benzoyl peroxide, and xylene to a high-pressure reactor, raising the temperature to 80-150° C., introducing ethylene gas for reaction, wherein the mass ratio of ethylene, octadecyl acrylate, and vinyl acetate is (50-65):(5-8):(15-45); then, hot washing with ethanol at 50-70° C. to remove unreacted monomers, and then vacuuming at 150-170° C. to remove the solvent, thereby obtaining the first component; (2) maleic anhydride, vinylimidazole, acrylamide and octadecyl methacrylate in a mass ratio of (10-15): (2-3): (1-2): (30-50) are dissolved in xylene, 0.3 wt% azobisisobutyronitrile is added, and polymerization reaction is carried out at 60-90°C under the protection of nitrogen to obtain a tetrapolymer of maleic anhydride, vinylimidazole, acrylamide and octadecyl methacrylate; then the tetrapolymer of maleic anhydride, vinylimidazole, acrylamide and octadecyl methacrylate is mixed with octadecylamine, the molar ratio of octadecylamine to maleic anhydride being 1:1, and an amination reaction is carried out at 100-160°C; then, a mixed solution of methanol and water in a weight ratio of 1:1 is first hot washed at 60-80°C to remove unreacted monomers, and then vacuumed at 140-160°C to remove the solvent to obtain the second component; (3) adding Guerbet hexadecanol and 0.4 wt% sodium hydroxide to a high-pressure reactor, raising the temperature to 110-130° C., introducing propylene oxide and ethylene oxide to react, wherein the mass ratio of ethylene oxide, propylene oxide, and Guerbet hexadecanol is (20-30):(40-50):(1-10); then applying vacuum at 120-150° C. to remove unreacted monomers, thereby obtaining the third component; (4) The first component, the second component, the third component and the fourth component are dissolved in No. 150 solvent oil in a mass ratio of (10-15): (35-55): (5-10): (1-5) to obtain a pipeline crude oil pour point depressant.

[0030] 3. The preparation method of the pipeline crude oil pour point depressant of the present invention can also be described in detail as follows: 3.1. A method for preparing a pour point depressant for pipeline crude oil, comprising the following steps: (1) Adding octadecyl acrylate, vinyl acetate, 0.3 wt% benzoyl peroxide, and xylene to a high-pressure reactor, heating to 115°C, introducing ethylene gas for reaction, wherein the mass ratio of ethylene, octadecyl acrylate, and vinyl acetate is (50-65): (5-8): (15-45); then hot washing with ethanol at 60°C to remove unreacted monomers, and then vacuuming at 160°C to remove the solvent to obtain the first component; (2) maleic anhydride, vinylimidazole, acrylamide and octadecyl methacrylate in a mass ratio of (10-15): (2-3): (1-2): (30-50) are dissolved in xylene, 0.3 wt% azobisisobutyronitrile is added, and polymerization reaction is carried out at 75°C under the protection of nitrogen to obtain a tetrapolymer of maleic anhydride, vinylimidazole, acrylamide and octadecyl methacrylate; then the tetrapolymer of maleic anhydride, vinylimidazole, acrylamide and octadecyl methacrylate is mixed with octadecylamine, the molar ratio of octadecylamine to maleic anhydride is 1:1, and an amination reaction is carried out at 130°C; then, a mixed solution of methanol and water in a weight ratio of 1:1 is first hot washed at 70°C to remove unreacted monomers, and then vacuumed at 150°C to remove the solvent to obtain the second component; (3) adding Guerbet hexadecanol and 0.4 wt% sodium hydroxide to a high-pressure reactor, raising the temperature to 120° C., introducing propylene oxide and ethylene oxide to react, wherein the mass ratio of ethylene oxide, propylene oxide, and Guerbet hexadecanol is (20-30):(40-50):(1-10); then applying vacuum at 135° C. to remove unreacted monomers, thereby obtaining the third component; (4) The first component, the second component, the third component and the fourth component are dissolved in No. 150 solvent oil in a mass ratio of (10-15): (35-55): (5-10): (1-5) to obtain a pipeline crude oil pour point depressant.

[0031] The pour point depressants used in the following experimental examples were prepared according to the preparation method for pipeline crude oil transport described in 3.1. The differences from the preparation conditions in 3.1 are listed in Table 1, Examples 1-8, and Table 2, Comparative Examples 1-11. The following experimental examples are intended to provide a reference for those skilled in the art to implement the present invention or verify its effectiveness. These examples do not limit the scope of the claims.

[0032] Table 1 Preparation conditions of Examples 1 to 8

[0033] Table 2 Preparation conditions of Comparative Examples 1 to 11

[0034] The following is an evaluation of the pour point depressants in Examples 1 to 8 and Comparative Examples 1 to 11 using crude oil from a block in Xinjiang as a sample, 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

[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) have a good pour point depressing effect on crude oil, with a large pour point depressing range of up to 10°C, and the pour point depressing effect is better than that of the pour point depressants in Comparative Examples 1-11. The infrared spectrum of the first component in the pour point depressant for pipeline crude oil in Example 3 is shown in detail. Figure 1 The infrared spectrum of the second component in the pour point depressant for pipeline crude oil in Example 3 is shown in Figure 2 The infrared spectrum of the third component in the pour point depressant for pipeline crude oil in Example 3 is shown in Figure 3 .

[0037] The foregoing is merely an embodiment of the present application, and the scope of protection of the present application is not limited by these specific embodiments, but is determined by the claims of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modifications, equivalent substitutions, improvements, 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 for pipeline crude oil, characterized in that: comprising a first component, a second component, a third component and a fourth component; The first component is a terpolymer of ethylene, acrylic acid ester and vinyl acetate, and the molecular weight of the first component is 10,000-15,000; The second component is an amination product of a tetrapolymer of maleic anhydride, vinylimidazole, acrylamide and methacrylate, and the molecular weight of the second component is 8000-12000; The third component is a polyether compound of ethylene oxide, propylene oxide and Guerbet alcohol, and the molecular weight of the third component is 3000-8000; The fourth component is one or more of polymethylsilsesquioxane, sorbitan fatty acid ester, polyisobutenyl succinic anhydride derivative and ethylene glycol monobutyl ether; The mass ratio of the first component, the second component, the third component and the fourth component is (10-15): (35-55): (5-10): (1-5).

2. The pour point depressant for pipeline crude oil transportation according to claim 1, characterized in that: The mass ratio of ethylene, acrylic acid ester and vinyl acetate in the first component is (50-65): (5-8): (15-45).

3. The pour point depressant for pipeline crude oil transportation according to claim 1, characterized in that: The mass ratio of maleic anhydride, vinylimidazole, acrylamide and methacrylate in the second component is (10-15): (2-3): (1-2): (30-50).

4. The pour point depressant for pipeline crude oil transportation according to claim 1, characterized in that: The mass ratio of ethylene oxide, propylene oxide and Guerbet alcohol in the third component is (20-30): (40-50): (1-10).

5. A method for preparing a pour point depressant for pipeline crude oil, characterized in that: The method is used to prepare the pour point depressant for pipeline crude oil according to any one of claims 1 to 4, and the method comprises the following steps: (1) Adding acrylate, vinyl acetate, initiator and light aromatic solvent into a high-pressure reactor, raising the temperature to 80-150°C, introducing ethylene gas for reaction, wherein the mass ratio of ethylene, acrylate and vinyl acetate is (50-65): (5-8): (15-45); then hot washing with ethanol at 50-70°C to remove unreacted monomers, and then vacuuming at 150-170°C to remove the solvent to obtain the first component; (2) maleic anhydride, vinylimidazole, acrylamide and methacrylate in a mass ratio of (10-15): (2-3): (1-2): (30-50) are dissolved in a light aromatic hydrocarbon solvent, azobisisobutyronitrile is added, and a polymerization reaction is carried out at 60-90°C under the protection of nitrogen to obtain a tetrapolymer of maleic anhydride, vinylimidazole, acrylamide and methacrylate; then the tetrapolymer of maleic anhydride, vinylimidazole, acrylamide and methacrylate is mixed with amine and an amination reaction is carried out at 100-160°C; then, a mixed solution of methanol and water in a weight ratio of 1:1 is first hot washed at 60-80°C to remove unreacted monomers, and then vacuumed at 140-160°C to remove the solvent to obtain the second component; (3) adding Guerbet alcohol and a catalyst to a high-pressure reactor, raising the temperature to 110-130° C., introducing propylene oxide and ethylene oxide to react, wherein the mass ratio of ethylene oxide, propylene oxide, and Guerbet alcohol is (20-30):(40-50):(1-10); then applying vacuum at 120-150° C. to remove unreacted monomers, thereby obtaining the third component; (4) 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 (10-15): (35-55): (5-10): (1-5) to obtain the pipeline crude oil pour point depressant.

6. The method for preparing a pour point depressant for pipeline crude oil transportation according to claim 5, characterized in that: The acrylate is one or more of lauryl acrylate, tetradecyl acrylate, hexadecyl acrylate and octadecyl acrylate; The methacrylate is one or more of lauryl methacrylate, tetradecyl methacrylate, hexadecyl methacrylate and octadecyl methacrylate; The amine is one or more of dodecylamine, tetradecylamine, hexadecylamine and octadecylamine; The Guerbet alcohol is one or more of Guerbet dodecanol, Guerbet tetradecanol, Guerbet hexadecanol and Guerbet octadecanol; The initiator is at least one selected from benzoyl peroxide, lauroyl peroxide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide and di-tert-butyl peroxide; The light aromatic hydrocarbon solvent is benzene, toluene or xylene; The catalyst is sodium hydroxide and / or potassium hydroxide; The heavy aromatic hydrocarbon solvent is No. 150 solvent oil.

7. The method for preparing a pour point depressant for pipeline crude oil transportation according to claim 5, characterized in that: The amount of the initiator added is 0.1 to 0.5 wt%; The addition amount of the azobisisobutyronitrile is 0.1 to 0.5 wt %; The molar ratio of the amine to maleic anhydride is (1-2):1; The added amount of the catalyst is 0.3-0.6 wt %.

8. Use of the pour point depressant for pipeline crude oil according to any one of claims 1 to 4 in lowering the freezing point of crude oil, wherein the amount of the pour point depressant for pipeline crude oil is 1700-1900 ppm.

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