Fluorocarbon modified pour point depressant for crude oil, and preparation method and application thereof

Abstract

The application discloses a fluorocarbon modified crude oil pour point depressant and a preparation method and application thereof, and belongs to the technical field of oil field chemicals. The fluorocarbon modified crude oil pour point depressant comprises the following components in percentage by mass: a pour point depressant main agent 40-50%, polyfluoroalkyl acrylate 15-30%, ethylene glycol monobutyl ether 5-15%, polyisobutylene succinimide 3-8%, and the rest is an aromatic hydrocarbon solvent; wherein the pour point depressant main agent is a terpolymer of maleic acid fluoroalkyl ester, ethylene-vinyl acetate copolymer and styrene. Through the synergistic effect of the low surface energy characteristics of the fluorocarbon chain and the polar group, the wax crystal morphology is regulated and dispersed and stabilized, the pour point of high-wax-content and high-freezing-point crude oil is significantly reduced, and the low-temperature fluidity of the crude oil is improved.

Description

Technical Field

[0001] This application relates to a fluorocarbon-modified crude oil pour point depressant, its preparation method, and its application, belonging to the field of oilfield chemical technology. Background Technology

[0002] High-wax crude oil (15%-28% wax content) easily precipitates wax crystals at low temperatures. Some of these crystals adsorb onto oil production equipment and transportation pipelines, agglomerating and growing to form wax deposits, thus causing pipeline blockages. Others form a three-dimensional network structure within the crude oil, encapsulating it and causing it to lose its fluidity and solidify, posing significant challenges to crude oil production, transportation, and storage. Currently, the main method used in China to address these issues is physical heating. However, this method suffers from high fuel consumption, limited allowable flow rate variation, and difficulties in restarting operations after shutdown. Another method is the chemical method: adding pour point depressants to the crude oil. This method offers advantages such as lower equipment investment, simpler operation, significant improvement in the low-temperature fluidity of crude oil, and no need for post-treatment.

[0003] Traditional pour point depressants mostly employ long-chain alkyl structures with simple molecular configurations. They can only rely on the intercalation of wax crystals through alkyl chains, making it difficult to effectively disrupt the regular stacking structure of wax crystals in high-wax crude oils. This results in weak pour point depressant effects and poor improvement in the low-temperature fluidity of crude oil. Conventional hydrocarbon polymer pour point depressants suffer from defects such as easy molecular chain coiling and precipitation during application, leading to insufficient long-term pour point depressant stability. Simultaneously, crude oil systems often contain high levels of gums, asphaltenes, and polar impurities. Traditional pour point depressants, with their limited range of polar groups, cannot fully adsorb these substances, easily leading to colloidal aggregation and ultimately, pour point depressant failure. Chinese invention patent CN115305076B discloses a composite pour point depressant, its preparation method, and its application. This composite pour point depressant is prepared from carbon dioxide nanotubes and poly(α-olefin) octadecyl acrylate, effectively lowering the pour point of wax-based crude oils. However, this composite pour point depressant contains nanomaterials, resulting in poor dispersion stability. It is prone to sedimentation during long-term storage or transportation, leading to a decrease in efficacy. Summary of the Invention

[0004] The purpose of this invention is to provide a fluorocarbon modified crude oil pour point depressant, its preparation method and application. Through the low surface energy characteristics of the fluorocarbon chain and the synergistic effect of polar groups, the wax crystal morphology is regulated and the dispersion is stabilized, which significantly reduces the pour point of high wax content and high pour point crude oil and improves its low temperature fluidity.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: According to one aspect of this application, a fluorocarbon modified crude oil pour point depressant is provided, comprising the following components by mass percentage: 40-50% pour point depressant, 15-30% fluoroalkyl polyacrylate, 5-15% ethylene glycol monobutyl ether, 3-8% polyisobutylene succinimide, and the balance being an aromatic solvent. The pour point depressant is a terpolymer of fluoroalkyl maleate, ethylene-vinyl acetate copolymer, and styrene.

[0006] Optionally, the number-average molecular weight of the pour point depressant is 10,000 to 15,000.

[0007] Optionally, the fluoroalkyl maleate is selected from one or more of fluorohexyl ethyl maleate, heptafluorobutyl maleate, perfluorooctyl ethyl maleate, and perfluorodecyl ethyl maleate.

[0008] Optionally, the vinyl acetate content in the ethylene-vinyl acetate copolymer is 15-30%.

[0009] Optionally, the fluoroalkyl group in the polyacrylic acid fluoroalkyl ester has 8 to 12 carbon atoms; And / or, the number average molecular weight of the polyacrylic fluoroalkyl ester is 5000 to 10000.

[0010] Optionally, the aromatic solvent is selected from xylene or toluene.

[0011] According to another aspect of this application, a method for preparing a fluorocarbon-modified crude oil pour point depressant is provided, the method being used to prepare any of the above-described fluorocarbon-modified crude oil pour point depressants, the method comprising the following steps: (1) Mix maleic fluoroalkyl ester, ethylene-vinyl acetate copolymer and styrene evenly, add initiator, and react at 75-85℃ under nitrogen protection for 4-6 hours to obtain pour point depressant; (2) Add the pour point depressant obtained in step (1) into an aromatic solvent and stir to dissolve at 80-100°C. Then add poly(fluoroalkyl) acrylate, ethylene glycol monobutyl ether and polyisobutylene succinimide in sequence and keep warm and stir for 2-3 hours to obtain fluorocarbon modified crude oil pour point depressant.

[0012] Optionally, the mass ratio of the fluoroalkyl maleate, the ethylene-vinyl acetate copolymer, and the styrene is 8:(0.8-1.2):(0.3-0.5). And / or, the amount of the initiator is 0.3 to 0.8% of the total mass of fluoroalkyl maleate, ethylene-vinyl acetate copolymer and styrene.

[0013] Optionally, the initiator is azobisisobutyronitrile or benzoyl peroxide.

[0014] According to another aspect of this application, the application of any of the above-described fluorocarbon-modified crude oil pour point depressants in lowering the pour point of crude oil is provided, wherein the amount of the fluorocarbon-modified crude oil pour point depressant is 0.08 to 0.25% of the crude oil mass.

[0015] In this application, "EVA" refers to ethylene-vinyl acetate copolymer; "VA" refers to vinyl acetate; and "room temperature" refers to 20–30°C.

[0016] The beneficial effects of this application include, but are not limited to: 1. The fluorocarbon-modified crude oil pour point depressant of this application introduces fluorocarbon chains into the molecular structure of the pour point depressant. Utilizing the low surface energy of these chains, the inter-crystal forces are weakened, while the polar groups enhance compatibility with crude oil, significantly improving the pour point depressant's performance. Specifically, by introducing fluorocarbon alkyl chains for modification, the low surface energy of the fluorocarbon chains effectively interferes with the regular crystallization of paraffin molecules in crude oil, disrupting the wax crystal network structure and significantly reducing the crude oil's pour point. The polar composite structure of fluorocarbon groups and maleic acid prevents self-shrinkage and precipitation, ensuring long-term stability of the pour point depressant's performance. The synergistic effect of acidic polar groups and oil-soluble long chains, combined with fluorocarbon modification, effectively disperses gums, asphaltenes, and wax crystal particles in crude oil, inhibiting colloidal aggregation, pipe wall waxing, and sludge deposition, thus possessing multiple functions including pour point depressant, dispersion, and wax prevention.

[0017] 2. The fluorocarbon modified crude oil pour point depressant of this application has high fluorocarbon bond energy, is resistant to acid and alkali, resistant to media corrosion, and resistant to oxidation. It is not easy to fail under complex crude oil conditions and has a long service life. It overcomes the defects of traditional pour point depressants in poor adaptability to high wax content, high gum content, and heavy oil. It has good treatment effect on high pour point crude oil of different origins and different compositions, and the agent has strong versatility.

[0018] 3. The fluorocarbon modified crude oil pour point depressant of this application has a simple preparation process and mild reaction conditions, and has broad application prospects in the fields of crude oil extraction and pipeline transportation. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is the infrared spectrum of the fluorocarbon-modified crude oil pour point depressant in Example 3 of this application. Detailed Implementation

[0020] The endpoints and any values ​​of the ranges 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 endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0021] Unless otherwise specified in the examples, the procedures shall be performed under standard conditions or conditions recommended by the manufacturer. Raw materials or instruments whose manufacturers are not specified are all commercially available products.

[0022] In this application, the preparation method of fluorohexyl ethyl maleate includes: adding maleic anhydride and fluorohexyl ethanol to xylene in a molar ratio of 1.1:1, adding p-benzoquinone and p-toluenesulfonic acid, wherein the mass of p-benzoquinone accounts for 0.2% of the mass of maleic anhydride, and the mass of p-toluenesulfonic acid accounts for 1% of the total mass of maleic anhydride and fluorohexyl ethanol, heating to 87°C, stirring and reacting for 6 hours under nitrogen protection, cooling to 70°C, removing the solvent by vacuum distillation, and obtaining fluorohexyl ethyl maleate.

[0023] The preparation method of heptafluorobutyl maleate includes: adding maleic anhydride and heptafluorobutanol to xylene in a molar ratio of 1.1:1, adding p-benzoquinone and p-toluenesulfonic acid, wherein the mass of p-benzoquinone accounts for 0.2% of the mass of maleic anhydride, and the mass of p-toluenesulfonic acid accounts for 1% of the total mass of maleic anhydride and heptafluorobutanol, heating to 87°C, stirring and reacting for 6 hours under nitrogen protection, cooling to 70°C, removing the solvent by vacuum distillation, and obtaining heptafluorobutyl maleate.

[0024] The preparation method of perfluorooctyl ethyl maleate includes: adding maleic anhydride and perfluorooctyl ethyl alcohol in a molar ratio of 1.1:1 to xylene, adding p-benzoquinone and p-toluenesulfonic acid, wherein the mass of p-benzoquinone accounts for 0.2% of the mass of maleic anhydride, and the mass of p-toluenesulfonic acid accounts for 1% of the total mass of maleic anhydride and perfluorooctyl ethyl alcohol, heating to 87°C, stirring and reacting for 6 hours under nitrogen protection, cooling to 70°C, removing the solvent by vacuum distillation, and obtaining perfluorooctyl ethyl maleate.

[0025] The preparation method of perfluorodecyl ethyl maleate includes: adding maleic anhydride and perfluorodecyl ethyl alcohol in a molar ratio of 1.1:1 to xylene, adding p-benzoquinone and p-toluenesulfonic acid, wherein the mass of p-benzoquinone accounts for 0.2% of the mass of maleic anhydride, and the mass of p-toluenesulfonic acid accounts for 1% of the total mass of maleic anhydride and perfluorodecyl ethyl alcohol, heating to 87°C, stirring and reacting for 6 hours under nitrogen protection, cooling to 70°C, removing the solvent by vacuum distillation, and obtaining perfluorodecyl ethyl maleate.

[0026] Example 1 A method for preparing a fluorocarbon-modified crude oil pour point depressant includes the following steps: (1) Maleic anhydride grafted with perfluorohexyl ethyl ester, EVA (VA content 15%) and styrene were uniformly mixed in a mass ratio of 8:0.8:0.3. Azobisisobutyronitrile (AIBN) was added at a total mass of 0.3%. The mixture was stirred and reacted at 75°C under nitrogen protection for 6 hours to obtain a pour point depressant with a number average molecular weight of 11,000. (2) Add 40% of the pour point depressant to 22% xylene and stir at 80°C for 3 hours until completely dissolved. Then add 15% perfluorooctyl polyacrylate (number average molecular weight of 5500), 15% ethylene glycol monobutyl ether and 8% polyisobutylene succinimide in sequence. Keep stirring at 100°C for 2 hours and cool to room temperature to obtain fluorocarbon modified crude oil pour point depressant.

[0027] Application test: Select crude oil with a wax content of 18% and a pour point of 24℃, add the above pour point depressant at 0.08% of the crude oil mass, mix evenly and test: the pour point drops to 10℃ (a decrease of 14℃).

[0028] Example 2 A method for preparing a fluorocarbon-modified crude oil pour point depressant includes the following steps: (1) Mix heptafluorobutyl maleate, EVA (VA content 30%) and styrene in a mass ratio of 8:1.2:0.5, add 0.8% of the total mass of the mixed monomers of benzoyl peroxide, stir and react for 4 h at 85℃ under nitrogen protection to obtain a pour point depressant with a number average molecular weight of 12500. (2) Add 50% of the pour point depressant to 12% toluene and stir at 80°C for 1 hour until completely dissolved. Then add 30% of perfluorodecyl polyacrylate (number average molecular weight of 6000), 5% ethylene glycol monobutyl ether and 3% polyisobutylene succinimide in sequence. Keep stirring at 80°C for 2 hours and cool to room temperature to obtain fluorocarbon modified crude oil pour point depressant.

[0029] Application test: Select crude oil with a wax content of 22% and a pour point of 35℃, add the above pour point depressant at 0.1% of the crude oil mass, mix evenly and test: the pour point drops to 18℃ (a decrease of 17℃).

[0030] Example 3 A method for preparing a fluorocarbon-modified crude oil pour point depressant includes the following steps: (1) Maleic anhydride grafted with perfluorooctyl ethyl ester, EVA (VA content 20%) and styrene were uniformly mixed in a mass ratio of 8:0.9:0.4. Azobisisobutyronitrile (AIBN) was added at a total mass of 0.4% of the mixed monomers. The mixture was stirred and reacted at 80°C under nitrogen protection for 5 hours to obtain a pour point depressant with a number average molecular weight of 14,000. (2) Add 45% pour point depressant to 18% xylene and stir at 85°C for 2 hours until completely dissolved. Then add 20% perfluorododecyl polyacrylate (number average molecular weight of 7000), 12% ethylene glycol monobutyl ether and 5% polyisobutylene succinimide in sequence. Keep stirring at 90°C for 2.5 hours and cool to room temperature to obtain fluorocarbon modified crude oil pour point depressant.

[0031] Application test: Select crude oil with a wax content of 28% and a pour point of 40℃, add the above pour point depressant at 0.25% of the crude oil mass, mix evenly and test: the pour point drops to 17℃ (a decrease of 23℃).

[0032] Comparative Example 1 A method for preparing a fluorocarbon-modified crude oil pour point depressant includes the following steps: 20% perfluorododecyl polyacrylate (number average molecular weight 7000), 12% ethylene glycol monobutyl ether and 5% polyisobutylene succinimide were added sequentially to 63% xylene, and stirred at 90°C for 2.5 h. After cooling to room temperature, a fluorocarbon modified crude oil pour point depressant was obtained.

[0033] Application test: Select crude oil with a wax content of 28% and a pour point of 40℃, add the above pour point depressant at 0.25% of the crude oil mass, mix evenly and test: the pour point drops to 38℃ (a decrease of 2℃).

[0034] Comparative Example 2 A method for preparing a fluorocarbon-modified crude oil pour point depressant includes the following steps: 45% maleic anhydride-grafted perfluorooctyl ethyl ester was added to 18% xylene and stirred at 85°C for 2 hours until completely dissolved. Then, 20% perfluorododecyl polyacrylate (number average molecular weight 7000), 12% ethylene glycol monobutyl ether, and 5% polyisobutylene succinimide were added sequentially. The mixture was stirred at 90°C for 2.5 hours and then cooled to room temperature to obtain a fluorocarbon-modified crude oil pour point depressant.

[0035] Application test: Select crude oil with a wax content of 28% and a pour point of 40℃, add the above pour point depressant at 0.25% of the crude oil mass, mix evenly and test: the pour point drops to 35℃ (a decrease of 5℃).

[0036] Comparative Example 3 The difference from Example 3 is that step (1) is: Maleic anhydride grafted with perfluorooctyl ethyl ester and EVA (VA content 20%) were uniformly mixed at a mass ratio of 8:0.9. Azobisisobutyronitrile (AIBN) was added at a total mass of 0.4% of the mixed monomers. The mixture was stirred and reacted at 80°C under nitrogen protection for 5 hours to obtain a pour point depressant with a number average molecular weight of 12,000.

[0037] Application test: Select crude oil with a wax content of 28% and a pour point of 40℃, add the above pour point depressant at 0.25% of the crude oil mass, mix evenly and test: the pour point drops to 28℃ (a decrease of 12℃).

[0038] Comparative Example 4 The difference from Example 3 is that step (1) is: Maleic anhydride grafted with perfluorooctyl ethyl ester and styrene were uniformly mixed at a mass ratio of 8:0.4, and 0.4% of azobisisobutyronitrile (AIBN) was added. The mixture was stirred and reacted at 80°C under nitrogen protection for 5 hours to obtain a pour point depressant with a number average molecular weight of 9000.

[0039] Application test: Select crude oil with a wax content of 28% and a pour point of 40℃, add the above pour point depressant at 0.25% of the crude oil mass, mix evenly and test: the pour point drops to 25℃ (a decrease of 15℃).

[0040] Comparative Example 5 The difference from Example 3 is that maleic anhydride grafted with perfluorooctyl ethyl ester is replaced with maleic anhydride.

[0041] Application test: Select crude oil with a wax content of 28% and a pour point of 40℃, add the above pour point depressant at 0.25% of the crude oil mass, mix evenly and test: the pour point drops to 32℃ (a decrease of 8℃).

[0042] Comparative Example 6 The difference from Example 3 is that perfluorododecyl polyacrylate was not added.

[0043] Application test: Crude oil with a wax content of 28% and a pour point of 40℃ was selected. The above-mentioned pour point depressant was added at 0.25% of the crude oil mass. After mixing evenly, the pour point was tested and the result was: the pour point dropped to 22℃ (a decrease of 18℃). The effect was lower than that in Example 3, indicating that the pour point depressant has a significant effect on improving the pour point depressing efficiency.

[0044] Comparative Example 7 The difference from Example 3 is that ethylene glycol monobutyl ether was not added.

[0045] Application test: Crude oil with a wax content of 28% and a pour point of 40℃ was selected. The above-mentioned pour point depressant was added at 0.25% of the crude oil mass. After mixing evenly, the pour point was tested and the result was: the pour point dropped to 19℃ (a decrease of 21℃). The effect was lower than that in Example 3, indicating that the co-solvent has an effect on improving the pour point depressing efficiency.

[0046] Comparative Example 8 The difference from Example 3 is that polyisobutylene succinimide was not added.

[0047] Application test: Crude oil with a wax content of 28% and a pour point of 40℃ was selected. The above-mentioned pour point depressant was added at 0.25% of the crude oil mass. After mixing evenly, the pour point was tested and the result was: the pour point dropped to 19℃ (a decrease of 21℃). The effect was lower than that in Example 3, indicating that the dispersant has an effect on improving the pour point depressing efficiency.

[0048] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A fluorocarbon-modified crude oil pour point depressant, characterized in that, By mass percentage, it includes the following components: 40-50% pour point depressant, 15-30% fluoroalkyl polyacrylate, 5-15% ethylene glycol monobutyl ether, 3-8% polyisobutylene succinimide, and the balance being aromatic solvent. The pour point depressant is a terpolymer of fluoroalkyl maleate, ethylene-vinyl acetate copolymer and styrene in a mass ratio of 8:(0.8-1.2):(0.3-0.5). The number-average molecular weight of the depressant is 10,000 to 15,000; The fluoroalkyl maleate is selected from one or more of fluorohexyl ethyl maleate, heptafluorobutyl maleate, perfluorooctyl ethyl maleate, and perfluorodecyl ethyl maleate. The polyacrylic acid fluoroalkyl ester has 8 to 12 carbon atoms in the fluoroalkyl group; The number average molecular weight of the polyacrylic acid fluoroalkyl ester is 5000 to 10000.

2. The fluorocarbon-modified crude oil pour point depressant according to claim 1, characterized in that, The vinyl acetate content in the ethylene-vinyl acetate copolymer is 15-30%.

3. The fluorocarbon-modified crude oil pour point depressant according to claim 1, characterized in that, The aromatic solvent is selected from xylene or toluene.

4. A method for preparing a fluorocarbon-modified crude oil pour point depressant, characterized in that, The method is used to prepare the fluorocarbon-modified crude oil pour point depressant according to any one of claims 1 to 3, and the method includes the following steps: (1) Mix maleic fluoroalkyl ester, ethylene-vinyl acetate copolymer and styrene evenly, add initiator, and react at 75-85℃ under nitrogen protection for 4-6 hours to obtain pour point depressant; (2) Add the pour point depressant obtained in step (1) into an aromatic solvent and stir to dissolve at 80-100°C. Then add poly(fluoroalkyl) acrylate, ethylene glycol monobutyl ether and polyisobutylene succinimide in sequence and keep warm and stir for 2-3 hours to obtain fluorocarbon modified crude oil pour point depressant.

5. The preparation method of the fluorocarbon-modified crude oil pour point depressant according to claim 4, characterized in that, The amount of the initiator is 0.3 to 0.8% of the total mass of fluoroalkyl maleate, ethylene-vinyl acetate copolymer, and styrene.

6. The preparation method of the fluorocarbon-modified crude oil pour point depressant according to claim 4, characterized in that, The initiator is azobisisobutyronitrile or benzoyl peroxide.

7. The application of the fluorocarbon-modified crude oil pour point depressant according to any one of claims 1 to 3 in lowering the pour point of crude oil, characterized in that, The amount of the fluorocarbon modified crude oil pour point depressant is 0.08 to 0.25% of the crude oil mass.

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