Modified graphene oxide and sodium oleate complexing agent, preparation method and application thereof

Abstract

The application discloses a modified graphene oxide and sodium oleate complexing agent and a preparation method and application thereof, and belongs to the technical field of oil field chemistry and oil transportation. A free radical polymerization method is adopted, and azobisisobutyronitrile is used as an initiator to graft octadecyl acrylate segments on the surface of graphene oxide, so that polyoctadecyl acrylate modified graphene oxide is obtained after precipitation, washing and drying; subsequently, the modified product and sodium oleate are mixed in a dimethylbenzene-anhydrous ethanol mixed solution according to a specific mass ratio, stirring is conducted, solvent is removed through rotary evaporation, and vacuum drying is conducted, so that a solid complexing type viscosity and pour point depressant is finally prepared. The application gives the graphene oxide a long-chain alkyl structure, increases the dispersibility of the graphene oxide and enables the graphene oxide to be eutectic with wax molecules in crude oil. In combination with the weakening effect of sodium oleate on the stacking structure of gum and asphaltene, the application realizes the double synergistic reduction of the viscosity and pour point of high pour point crude oil.

Description

Technical Field

[0001] This invention relates to the fields of oilfield chemistry and petroleum transportation technology, specifically to a modified graphene oxide and sodium oleate compound agent and its preparation method, as well as the application of the compound agent in reducing viscosity and pour point of high-pour-point crude oil. Background Technology

[0002] With the gradual depletion of conventional and easily accessible oil resources, the proportion of complex crude oils with high wax content, high pour point, and high viscosity, especially high-pour-point crude oil, being extracted and transported through pipelines is increasing. High-pour-point crude oil typically features high wax content, high pour point, and poor low-temperature fluidity. Some high-pour-point crude oils also contain high levels of heavy components such as gums and asphaltenes. When the crude oil temperature drops below the wax precipitation point, wax molecules gradually precipitate and form wax crystals. As the temperature further decreases to the pour point, the wax crystals continue to grow, aggregate, and form a three-dimensional network structure. Simultaneously, large molecular components such as gums and asphaltenes entangle or aggregate with the wax crystals, leading to a sharp increase in crude oil viscosity and a decrease in fluidity. In severe cases, this can cause pipeline clogging, pumping difficulties, and increased transportation energy consumption, affecting oilfield production and gathering and transportation safety.

[0003] Currently, methods for improving the low-temperature fluidity of crude oil mainly include physical and chemical methods. Physical methods, such as heating, dilution, and electric field treatment, can improve crude oil fluidity to some extent, but they typically suffer from high energy consumption, demanding equipment requirements, high operating costs, or limited field adaptability. Chemical methods mainly improve crude oil fluidity by adding pour point depressants, viscosity reducers, or drag reducers. They offer advantages such as simple operation, low dosage, and suitability for continuous field application, and are therefore widely used in crude oil extraction and pipeline transportation.

[0004] Traditional pour point depressants mainly include ethylene-vinyl acetate copolymers, polymethyl methacrylates, polyalphaolefins and their derivatives. Their mechanisms of action typically involve co-crystallization with wax crystals, adsorption on the surface of wax crystals, or inducing wax crystal nucleation, thereby inhibiting wax crystal growth, altering wax crystal morphology, and weakening the network structure between wax crystals. However, for high-pour-point crude oils with high wax content and high gum and asphaltenes content, heavy components such as gums and asphaltenes easily compete with wax crystals or pour point depressant molecules for adsorption or entanglement, affecting the effective interaction between the pour point depressant and wax crystals. This results in unstable pour point depressant effects, limited applicability, and sometimes requires higher dosages to achieve the desired effect.

[0005] In recent years, graphene oxide has shown promise in adsorbing, dispersing, and regulating the aggregation of heavy components due to its unique two-dimensional sheet structure, large specific surface area, and abundant oxygen-containing functional groups such as hydroxyl, carboxyl, and epoxy groups. Introducing graphene oxide into crude oil flowability improvement systems is expected to improve crude oil flowability by interacting with wax crystals through its sheet structure and surface functional groups, thereby regulating wax crystal morphology. However, when graphene oxide is used alone, its dispersion stability in crude oil systems and its synergistic effect with wax crystals and heavy components remain limited, making it difficult to fully realize its viscosity-reducing and pour point-reducing effects. Therefore, there is an urgent need to develop a graphene oxide-based compound agent that can simultaneously regulate wax crystals, disperse heavy components, and stabilize the system, in order to improve its viscosity-reducing and pour point-reducing effects on high-pour-point crude oils and its field applicability. Summary of the Invention

[0006] To address the shortcomings of existing pour point depressants in adapting to high-wax, high-colloid / asphaltite high-pour-point crude oils, and the limited dispersion stability and pour point depressing effect of graphene oxide in crude oil systems, this invention provides a compound agent of octadecyl acrylate-grafted modified graphene oxide and sodium oleate, its preparation method, and its application. This invention grafts octadecyl acrylate onto the surface of graphene oxide via free radical polymerization. Utilizing the oxygen-containing groups on the graphene oxide surface as chain transfer sites, under the action of an initiator, octadecyl acrylate undergoes free radical polymerization. The resulting polymer chain free radicals undergo a grafting reaction with the oxygen-containing functional groups or defect sites on the graphene oxide surface, resulting in at least a portion of the octadecyl acrylate segments grafted onto the graphene oxide surface, yielding polyoctadecyl acrylate-modified graphene oxide. This structure can co-crystallize or adsorb with wax molecules in crude oil, regulating wax crystal growth and aggregation, thereby reducing the viscosity and pour point of high-pour-point crude oil. Meanwhile, this invention combines graphene oxide with sodium oleate. Sodium oleate utilizes its amphiphilic structure to promote the dispersion of heavy components such as gums and asphaltenes, weaken their associated network structure, and improve the dispersion stability of modified graphene oxide in the crude oil system. Together with modified graphene oxide, it achieves viscosity reduction and pour point reduction.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first objective of this invention is to provide a modified graphene oxide and sodium oleate compound, the raw materials of which include: octadecyl acrylate, graphene oxide and sodium oleate.

[0008] Preferably, the modified graphene oxide is prepared by free radical graft polymerization of graphene oxide, octadecyl acrylate and an initiator.

[0009] Preferably, the initiator is azobisisobutyronitrile.

[0010] A second objective of this invention is to provide a method for preparing modified graphene oxide, comprising the following steps: Step A1: Add graphene oxide powder to an organic solvent and ultrasonically disperse it for 30 min under sealed conditions to obtain a uniform graphene oxide dispersion.

[0011] Step A2: Add octadecyl acrylate monomer and azobisisobutyronitrile to the above graphene oxide dispersion, and stir to dissolve for 20-30 min under inert gas protection.

[0012] Step A3: Under inert gas protection, the reaction system is heated to 80-100℃ and stirred for 8-12 hours. During this process, azobisisobutyronitrile initiates the polymerization of octadecyl acrylate, while the growing chain free radicals undergo chain transfer to hydroxyl, carboxyl, and other groups on the surface of graphene oxide, thereby grafting some octadecyl acrylate onto the surface of graphene oxide.

[0013] Step A4: After the reaction is complete, cool the reaction solution to room temperature, add an excess of precipitant such as anhydrous ethanol to precipitate, then centrifuge and discard the supernatant.

[0014] Step A5: Redisperse the precipitate with the organic solvent described in Step 1, then precipitate it with a precipitant, and wash it repeatedly 2-3 times to remove unreacted octadecyl acrylate monomer and free polymer.

[0015] Step A6: Place the washed product in a vacuum drying oven and dry it at 40~60℃ to constant weight to obtain polyoctadecyl acrylate modified graphene oxide.

[0016] Preferably, the organic solvent in step A1 is toluene or xylene.

[0017] Preferably, the mass-to-volume ratio of graphene oxide to organic solvent in step A1 is 1 mg:(100~150) mL.

[0018] Preferably, the mass ratio of graphene oxide, octadecyl acrylate, and azobisisobutyronitrile in step A2 is 1:(5~20):(0.1~0.5).

[0019] Preferably, the centrifugation conditions in step A4 are 8000~12000 rpm and the centrifugation time is 20~30 min.

[0020] A third objective of this invention is to provide a method for compounding the above-mentioned modified graphene oxide and sodium oleate, comprising the following steps: Step B1: Add the modified graphene oxide prepared above to an organic dispersion medium and mechanically stir to obtain a modified graphene oxide dispersion.

[0021] Step B2: Weigh out the appropriate mass of sodium oleate according to the target ratio, add it to the organic solvent, and stir mechanically to obtain a sodium oleate solution.

[0022] Step B3: Under mechanical stirring, add sodium oleate solution dropwise to the modified graphene oxide dispersion and continue stirring to mix it evenly.

[0023] Step B4: Remove the organic solvent by rotary evaporation, and dry under vacuum at 40~50℃ to constant weight to obtain the solid compound agent.

[0024] Preferably, the organic dispersion medium in step B1 is one or more of xylene, toluene, anhydrous ethanol, and a toluene / xylene-anhydrous ethanol mixed solvent.

[0025] Preferably, the mechanical stirring rate in steps B1 to B3 is 300 to 500 rpm, and the time is 20 to 30 min.

[0026] Preferably, the concentration of the modified graphene oxide dispersion in step B1 is 5~20 mg / mL.

[0027] Preferably, the concentration of the sodium oleate dispersion in step B2 is 2~20 mg / mL.

[0028] Preferably, the mass ratio of modified graphene oxide to sodium oleate in step B2 is 1:(0.5~2.0).

[0029] The fourth objective of this invention is to provide the application of the above-mentioned modified graphene oxide and sodium oleate compound in reducing viscosity and pour point of high-pour-point crude oil.

[0030] Preferably, the application method involves adding the modified graphene oxide and sodium oleate compound to high-pour-point crude oil, stirring and mixing to ensure uniform dispersion in the crude oil.

[0031] Preferably, the amount of modified graphene oxide and sodium oleate compound added is 0.05wt%~0.5wt% of the mass of the high-pour-point crude oil.

[0032] The beneficial effects of this invention are as follows: 1. This invention relates to a solution blending of octadecyl polyacrylate-modified graphene oxide and sodium oleate, which exhibits a synergistic effect in improving the low-temperature fluidity of high-pour-point crude oil. Specifically, the long-chain alkyl structure in the octadecyl polyacrylate-modified graphene oxide can co-crystallize, adsorb, or regulate the crystal structure with wax molecules in crude oil, inhibiting wax crystal growth and aggregation. Sodium oleate promotes the dispersion of heavy components such as gums and asphaltenes, weakens their associated network structure, and improves the dispersion stability of the octadecyl polyacrylate-modified graphene oxide in the crude oil system. The synergistic effect of these two components can simultaneously improve the viscosity and pour point of high-pour-point crude oil.

[0033] 2. In a specific embodiment of the present invention, when the amount of the compounding agent added is 0.05wt% to 0.5wt% of the mass of high pour point crude oil, the pour point of crude oil can be reduced by 3.5 to 5°C, and the viscosity of crude oil at 10°C can be reduced by 10.61% to 15.15%.

[0034] 3. This invention uses a free radical polymerization grafting method to prepare polyoctadecyl acrylate modified graphene oxide. The reaction conditions are mild, and the subsequent processing only involves precipitation, washing and drying. The modified graphene oxide is compounded with sodium oleate by solution blending, which is simple to operate, the organic solvent can be recycled and reused, no high temperature and high pressure are required, energy consumption is low, it is easy to scale up and has good potential for field application. Attached Figure Description

[0035] Figure 1 The Fourier transform infrared spectrum and X-ray diffraction pattern of the modified graphene oxide in Example 1 of this invention are shown. Figure 2 The effect of adding modified graphene oxide and sodium oleate compound agent on viscosity reduction of high pour point crude oil in Example 3 of the present invention; Figure 3 This is a schematic diagram illustrating the viscosity-reducing and pour point-reducing mechanism of modified graphene oxide and sodium oleate compound on low-temperature crude oil in Example 3 of the present invention. In this diagram, 1 represents linked wax crystals; 2 represents aggregated gum / asphaltene; 3 represents agglomerated graphene oxide; 4 represents a long chain of octadecyl acrylate; 5 represents sodium oleate molecules; 6 represents dispersed graphene oxide; 7 represents dispersed gum / asphaltene; and 8 represents dispersed wax crystals. Detailed Implementation

[0036] To more clearly illustrate the present invention, specific embodiments are described below. Those skilled in the art should understand that the following description is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0037] Example 1: Preparation of modified graphene oxide, specifically including the following steps: Step A1: Add 1 g of graphene oxide powder to 120 mL of xylene solvent and ultrasonically disperse for 30 min under sealed conditions to obtain a uniform graphene oxide dispersion.

[0038] Step A2: Add 5 g of octadecyl acrylate monomer and 0.15 g of azobisisobutyronitrile to the above graphene oxide dispersion, and stir to dissolve for 20 min under nitrogen atmosphere.

[0039] Step A3: Under nitrogen protection and reflux conditions, the reaction system is heated to 100°C and stirred for 10 h. During this process, azobisisobutyronitrile decomposes upon heating to generate free radicals, which initiate the polymerization of octadecyl acrylate. The generated polymer chain free radicals undergo a grafting reaction with oxygen-containing functional groups or defect sites on the surface of graphene oxide, causing at least some polyoctadecyl acrylate segments to be grafted onto the surface of graphene oxide.

[0040] Step A4: After the reaction is complete, cool the reaction solution to room temperature, add excess anhydrous ethanol, centrifuge at 8000 rpm for 30 min, and discard the supernatant.

[0041] Step A5: Redisperse the precipitate with xylene, then precipitate with anhydrous ethanol, and repeat the washing 2-3 times to remove unreacted octadecyl acrylate monomer and free polymer.

[0042] Step A6: Place the washed product in a vacuum drying oven and dry it at 40°C to constant weight to obtain modified graphene oxide.

[0043] Example 2: Blending of modified graphene oxide with sodium oleate. This example prepared three blended products with different mass ratios of modified graphene oxide and sodium oleate, specifically including the following steps: Step B1 (mass ratio 1:1): Weigh 0.2 g of modified graphene oxide and add it to 20 mL of xylene-anhydrous ethanol mixed solvent (volume ratio 4:1) to prepare a dispersion of 10 mg / mL. Stir mechanically at 60℃ and 500 rpm for 20 min. Weigh 0.2 g of sodium oleate and add it to 20 mL of xylene-anhydrous ethanol mixed solution (volume ratio 4:1) to prepare a dispersion of 10 mg / mL. Stir until dissolved. Under stirring conditions, add the sodium oleate solution dropwise to the modified graphene oxide dispersion. After the addition is complete, continue stirring for 30 min. Remove the xylene-anhydrous ethanol from the mixture by rotary evaporation. Place the resulting solid in a vacuum drying oven and dry to constant weight at 40℃ to obtain a compound agent with a modified graphene oxide to sodium oleate mass ratio of 1:1.

[0044] Step B2 (mass ratio 1:2): Referring to step B1, change the amount of sodium oleate to 0.4 g and dissolve it in 20 mL of xylene-anhydrous ethanol mixed solvent (volume ratio 4:1). Stir to dissolve and obtain a solution with a concentration of 20 mg / mL. Keep the amount of polymodified graphene oxide unchanged at 0.2 g. The rest of the operation is the same as in B1, and the compound product with a mass ratio of 1:2 is obtained.

[0045] Step B3 (mass ratio 2:1): Referring to step B1, the amount of modified graphene oxide is changed to 0.4 g and dispersed in 20 mL of xylene-anhydrous ethanol mixed solvent (volume ratio 4:1) to prepare a dispersion with a concentration of 20 mg / mL. The amount of sodium oleate is changed to 0.2 g and dissolved in 20 mL of xylene-anhydrous ethanol mixed solvent (volume ratio 4:1) to obtain a solution with a concentration of 10 mg / mL. The remaining operations are the same as in B1, thus obtaining a compound product with a mass ratio of 2:1.

[0046] Example 3: Based on the modified graphene oxide and sodium oleate compound prepared in Example 2 of this invention, the viscosity-reducing and pour point-reducing effects on high-pour-point crude oil were further investigated: (1) Characterization of modified graphene oxide structure: XRD crystal structure analysis was performed according to GB / T 30904-2014 "X-ray diffraction method for crystal structure analysis of inorganic chemical products". Fourier transform infrared spectroscopy was used to characterize unmodified graphene oxide and modified graphene oxide according to GB / T 6040-2019 "General rules for infrared spectroscopy analysis". Figure 1 The results are X-ray diffraction and Fourier transform infrared spectroscopy of unmodified GO and modified graphene oxide.

[0047] Figure 1 (a) In the X-ray diffraction pattern, unmodified graphene oxide exhibits a sharp and high-intensity characteristic diffraction peak at 2θ≈10°~11°, corresponding to its layered stacked crystal structure, according to the Bragg equation ( Calculations show that its interlayer spacing is approximately 0.8 nm. In contrast, the diffraction peaks of modified graphene oxide show significant changes. On the one hand, the peak positions shift towards lower angles to approximately 9°–10°, even exhibiting broadened low-angle diffuse peaks, indicating an increased interlayer spacing. This may be attributed to the introduction of octadecyl acrylate segments and their long-chain alkyl structures into the surface or interlayer of graphene oxide, thus increasing the interlayer spacing. On the other hand, the diffraction peak intensity is significantly weakened and the peak shape broadens, indicating that the original orderly layered stacking structure of graphene oxide is disrupted, and the interlayer order is reduced. This structural change facilitates the penetration of oil phase molecules into the interlayer, thereby promoting the exfoliation and uniform dispersion of graphene oxide in the oil phase medium.

[0048] Depend on Figure 1(b) Fourier transform infrared spectroscopy reveals that unmodified graphene oxide exhibits a broadened absorption peak near 3400 cm⁻¹, corresponding to the OH stretching vibration, indicating the presence of oxygen-containing functional groups such as hydroxyl groups on the graphene oxide surface. Modified graphene oxide shows distinct absorption peaks near 2920 cm⁻¹ and 2850 cm⁻¹, corresponding to the stretching vibration of CH in long-chain alkyl groups; a characteristic absorption peak for ester group C=O appears around 1735 cm⁻¹. These characteristic peaks indicate that the octadecyl polyacrylate segment has been introduced into the graphene oxide surface, and the graphene oxide has undergone organic modification.

[0049] (2) Evaluation of viscosity and pour point reduction performance: Test method: The viscosity of high pour point crude oil before and after the addition of compounding agent was determined according to the industry standard "SY / T 0520-2008 Crude Oil Viscosity Determination Rotation Viscometer Equilibrium Method", and the viscosity reduction rate was calculated according to the formula. The pour point of high pour point crude oil before and after the addition of compounding agent was determined according to the national standard "GB / T 510-2018 Petroleum Products Pour Point Determination Method".

[0050] ; in, η 0 indicates the viscosity of the high-pour-point crude oil before the addition of the compounding agent, in mPa·s. η The viscosity of the high-pour-point crude oil after the addition of the compounding agent is expressed in mPa·s.

[0051] The specific steps are as follows: High-pour-point crude oil was heated to 60°C to completely dissolve the wax. Modified graphene oxide and sodium oleate compound prepared in Example 2 were added at 0.1, 0.15, and 0.2 wt% of the high-pour-point crude oil mass, respectively, varying the ratio of graphene oxide to sodium oleate (modified graphene oxide:sodium oleate = 0:1, 1:0, 1:2, 2:1) while maintaining the same amount of compound added. The high-pour-point crude oil after adding the compound was stirred at 60°C for 30 min to ensure uniform dispersion of the additive. The viscosity and pour point of the high-pour-point crude oil at 10°C were then measured according to the specified testing method.

[0052] Figure 2The figure shows the viscosity-reducing effect of the compound agent prepared in this invention on high-pour-point crude oil. In the figure, the horizontal axis "0.20 (0:1)" represents the mass percentage of the compound agent in the high-pour-point crude oil as 0.20 wt%, and the "0:1" in parentheses indicates that the mass ratio of modified graphene oxide to sodium oleate is 0:1, i.e., sodium oleate is added alone. Compared with crude oil without additives, the viscosity of high-pour-point crude oil decreased after adding modified graphene oxide, sodium oleate, or a compound agent of polymodified graphene oxide and sodium oleate. The best viscosity-reducing effect was observed when the mass ratio of the compound agent was 0.15 wt% and the ratio of modified graphene oxide to sodium oleate was 1:2, with a viscosity reduction rate of 15.15% at 10℃; the pour point decreased from 33℃ to 28℃. Table 1 shows the pour point reduction effect of the compound agent prepared in this invention on high-pour-point crude oil. As shown in Table 1, when the total amount added is the same (e.g., 0.20 wt%), the pour point of the compound with a ratio of 1:2 is lower than that of sodium oleate alone or modified graphene oxide alone, which proves that there is a significant synergistic pour point depressing effect between modified graphene oxide and sodium oleate.

[0053] Table 1. Comparison of crude oil pour points before and after adding compounding agents. ; (3) Viscosity reduction and pour point depressing mechanism: such as Figure 3 As shown, in unmodified low-temperature crude oil, the linked wax crystals tend to grow and overlap during the cooling process, forming a dense three-dimensional network structure. Simultaneously, asphaltenes / colloids aggregate, further strengthening the internal structure of the system, leading to increased crude oil viscosity, a higher pour point, and loss of fluidity. Furthermore, unmodified graphene oxide exhibits poor dispersibility in the oil phase, easily agglomerating and settling, hindering its effective function. With the addition of the compounding agent of this invention, the dispersibility of graphene oxide is enhanced. The long chains of octadecyl acrylate grafted onto its surface can be adsorbed onto the wax crystal surface through eutectic action, interfering with the orderly growth and further aggregation of the wax crystals, thereby inhibiting the formation of the wax crystal network. Simultaneously, sodium oleate forms a stable dispersion layer around the graphene oxide sheets, inhibiting secondary agglomeration of graphene oxide and promoting the dispersion of asphaltenes / colloid micelles through steric hindrance and interfacial regulation, weakening the internal aggregated structure of the system. Based on the above synergistic effect, the compound agent significantly improves the dispersion state of wax crystals and heavy components in low-temperature crude oil, enhances system stability, and ultimately achieves the effects of reducing pour point, reducing viscosity, and restoring fluidity.

[0054] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A modified graphene oxide and sodium oleate compound, its preparation method and application, characterized in that, Its raw materials include: octadecyl polyacrylate modified graphene oxide and sodium oleate.

2. The modified graphene oxide and sodium oleate compound agent according to claim 1, characterized in that, The polyoctadecyl acrylate modified graphene oxide is prepared by free radical graft polymerization of graphene oxide, octadecyl acrylate and an initiator.

3. The polyoctadecyl acrylate modified graphene oxide according to claim 2, characterized in that, The initiator is azobisisobutyronitrile.

4. The modified graphene oxide and sodium oleate compound agent according to claim 2, characterized in that, The preparation method of the polyoctadecyl acrylate modified graphene oxide includes the following steps: Step A1: Add graphene oxide powder to an organic solvent and ultrasonically disperse it for 30 min under sealed conditions to obtain a uniform graphene oxide dispersion. Step A2: Add octadecyl acrylate and initiator to the above graphene oxide dispersion and stir and mix under inert gas protection; Step A3: Heat the reaction system to 80~100℃ and react for 8~12 h to carry out free radical polymerization grafting reaction; Step A4: After the reaction is complete, cool the reaction solution to room temperature, add excess precipitant such as anhydrous ethanol, centrifuge, discard the supernatant, and collect the precipitate; Step A5: Redisperse the precipitate with the organic solvent described in step A1, and precipitate it with a precipitant, repeating the washing process 2-3 times; Step A6: Dry the washed product to constant weight to obtain modified graphene oxide.

5. The modified graphene oxide and sodium oleate compound agent according to claim 4, characterized in that, In step A1, the mass-to-volume ratio of graphene oxide to organic solvent is 1 mg:(100~150) mL, and the organic solvent is toluene or xylene.

6. The modified graphene oxide and sodium oleate compound agent according to claim 4, characterized in that, In step A2, the mass ratio of graphene oxide, octadecyl acrylate, and azobisisobutyronitrile is 1:(5~20):(0.1~0.5).

7. A method for compounding modified graphene oxide and sodium oleate as described in any one of claims 1-3, comprising the following steps: Step B1: Disperse the modified graphene oxide in an organic solvent to obtain a dispersion; Step B2: Dissolve sodium oleate in an organic solvent to obtain a solution; Step B3: Under mechanical stirring, add sodium oleate solution dropwise to the modified graphene oxide dispersion and mix thoroughly; Step B4: Remove the organic solvent and dry to obtain the modified graphene oxide and sodium oleate compound.

8. The preparation method according to claim 7, characterized in that, In step B1, the organic solvent is one or more of anhydrous ethanol or a mixture of toluene / xylene-anhydrous ethanol.

9. The preparation method according to claim 7, characterized in that, In step B3, the mass ratio of graphene oxide to sodium oleate is controlled to be 1:(0.5~2.0).

10. An application of the modified graphene oxide and sodium oleate compound agent as described in any one of claims 1-3 in reducing viscosity and pour point of high-pour-point crude oil, characterized in that... The amount of the compounding agent added to the high-pour-point crude oil is 0.1wt% to 0.2wt% of the crude oil mass.

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