Preparation and application of oil-soluble viscosity reducer

Abstract

The invention discloses preparation and application of an oil-soluble viscosity reducer, and relates to the field of oil exploitation and processing.The preparation method of the oil-soluble viscosity reducer comprises the steps that fatty alcohol-polyoxyethylene ether acrylate, 2-acrylamido-2-methylpropanesulfonic acid and 4-(4-vinyl phenoxy)-2-hydroxybenzoic acid are dissolved in an organic solvent, and a first solution is obtained; adding an initiator into the first solution in an inert atmosphere to obtain a reaction solution; and heating the reaction liquid to react, and removing the organic solvent to obtain the oil-soluble viscosity reducer. The novel multifunctional oil-soluble viscosity reducer is prepared by polymerizing three monomers, and the synthesis mode has the characteristics of environmental friendliness, no industrial waste residue, high interfacial activity and simple synthesis method. The multifunctional oil-soluble viscosity reducer is dissolved in water to obtain a thick oil viscosity reducer with a good viscosity reduction effect, and the thick oil viscosity reducer is convenient to prepare on site, small in dosage, low in cost, small in damage to stratums and suitable for oil exploitation.

Description

Technical Field

[0001] The present invention relates to the preparation and application of a heavy oil viscosity reducer, and in particular to the preparation and application of an oil-soluble viscosity reducer. Background Art

[0002] Heavy oil, a globally significant unconventional oil and gas resource with abundant reserves and widespread distribution, has become an indispensable component of the global energy system. Due to its high viscosity, high density, and low fluidity, heavy oil presents significant flow resistance during extraction, gathering, transportation, and processing, severely restricting the technical and economic viability of its development and utilization. To address the high viscosity and low fluidity of heavy oil, the development of efficient viscosity reduction technologies has become a core technical focus for improving oilfield production efficiency, reducing energy costs, and promoting sustainable energy utilization.

[0003] Existing heavy oil viscosity reduction technologies include heating, solvent dilution, emulsification, and chemical viscosity reduction. Chemical viscosity reduction technology, with its advantages of simple process, wide adaptability, and long-lasting viscosity reduction effect, has gradually become an important means of heavy oil extraction and transportation. Chemical viscosity reducers usually reduce the viscosity of the system and improve the flow properties of the oil phase by destroying the aggregation structure between colloid and asphaltene molecules in the heavy oil system. Although traditional chemical viscosity reducers have improved the rheological properties of heavy oil to a certain extent, due to the complex component characteristics of the heavy oil system, existing viscosity reducers generally have technical bottlenecks such as insufficient oil solubility, limited viscosity reduction efficiency, short action period, and poor environmental adaptability, making it difficult to meet the application requirements in high-temperature, high-salinity, and high-density reservoir environments.

[0004] With the rapid development of polymer chemistry, interface science, and molecular engineering technologies, functionalized polymers have shown significant application potential in the field of heavy oil viscosity reduction. By introducing lipophilic segments, hydrophilic functional groups, and rigid structural units into the polymer molecular chain, precise control of the microscopic interface of the heavy oil system can be achieved, significantly improving the dispersion stability of the viscosity reducer in the oil phase and its interaction with heavy components, effectively promoting the depolymerization and reorganization of the internal structure of the heavy oil, and thus achieving a significant reduction in viscosity. Despite this, the functional polymer viscosity reducers reported so far still have problems such as insufficient oil solubility and interfacial activity compatibility, complex synthesis processes, limited environmental tolerance, and difficulty in cost control, which restrict their technical feasibility and economic viability in large-scale application in oil fields. Summary of the Invention

[0005] Objectives of the Invention: The present invention aims to provide a method for preparing an oil-soluble viscosity reducer, thereby addressing the problem of preparing a heavy oil viscosity reducer with good oil solubility, high viscosity reduction efficiency, long action period, and good environmental adaptability. Another objective of the present invention is to propose the use of an oil-soluble viscosity reducer in heavy oil viscosity reduction, thereby addressing the problem of reducing heavy oil viscosity.

[0006] Technical solution: The preparation method of the oil-soluble viscosity reducer described in the present invention comprises the following steps:

[0007] (1) dissolving fatty alcohol polyoxyethylene ether acrylate, 2-acrylamido-2-methylpropanesulfonic acid and 4-(4-vinylphenoxy)-2-hydroxybenzoic acid in an organic solvent to obtain a first solution;

[0008] (2) adding an initiator to the first solution under an inert atmosphere to obtain a reaction solution;

[0009] (3) The reaction solution is heated to react and then the organic solvent is removed to obtain an oil-soluble viscosity reducer.

[0010] The present invention uses fatty alcohol polyoxyethylene ether acrylate, 2-acrylamido-2-methylpropanesulfonic acid, and 4-(4-vinylphenoxy)-2-hydroxybenzoic acid as monomers, and produces a polymer through a free radical polymerization process. The polymer's molecular structure is designed to balance lipophilic segments, hydrophobic groups, and a rigid backbone, endowing the viscosity reducer with excellent oil solubility, interfacial activity, dispersion stability, and environmental adaptability. In heavy oil viscosity reduction applications, the viscosity reducer can effectively disrupt the spatial network structure of colloid and asphaltene aggregates in the heavy oil, significantly reducing viscosity and improving fluidity.

[0011] Preferably, in step (1), the chemical formula of the fatty alcohol polyoxyethylene ether acrylate is as follows:

[0012]

[0013] Where n = 10-20, R is C 12-18 alkyl.

[0014] Preferably, in step (1), the organic solvent comprises at least one of cyclohexane, toluene, xylene and trimethylbenzene.

[0015] Preferably, in step (1), the molar ratio of fatty alcohol polyoxyethylene ether acrylate, 2-acrylamido-2-methylpropanesulfonic acid and 4-(4-vinylphenoxy)-2-hydroxybenzoic acid is 1-2:1-2:1-2, and the mass ratio of the total weight of fatty alcohol polyoxyethylene ether acrylate, 2-acrylamido-2-methylpropanesulfonic acid and 4-(4-vinylphenoxy)-2-hydroxybenzoic acid to the organic solvent is 10-25:75-90.

[0016] Preferably, in step (2), the initiator comprises at least one of azobisisobutyronitrile, benzoyl peroxide, and tert-butyl hydroperoxide, and the content of the initiator in the reaction solution is 0.01-0.05 wt%.

[0017] Preferably, in step (2), the inert atmosphere is created by continuously introducing an inert gas into the reaction vessel and maintaining the inert gas flow for at least 30 minutes.

[0018] Preferably, the inert gas includes at least one of nitrogen, helium and argon.

[0019] Preferably, in step (3), the heating reaction conditions are: heating the reaction solution to 50-100° C. for 4-7 hours.

[0020] Preferably, in step (3), the method for removing the organic solvent is: heating the reaction solution after the heating reaction to 100-120° C. and performing rotary evaporation for at least 1 hour.

[0021] Another aspect of the present invention discloses the use of the oil-soluble viscosity reducer prepared by the preparation method in reducing the viscosity of heavy oil.

[0022] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0023] The present invention features a simple synthesis process, a wide range of raw material sources, and excellent overall performance. The resulting viscosity reducer exhibits excellent oil solubility, interfacial activity, and environmental stability. It can achieve efficient and long-lasting viscosity reduction in complex heavy oil systems, significantly improving heavy oil development and gathering efficiency. It has broad engineering application prospects and industrial promotion value. Experimental results show that a 100mg / L AAVH aqueous solution can dehydrate heavy oil emulsions by 83.9%, and a 400mg / L AAVH aqueous solution can reduce the viscosity of heavy oil by 84.77%, meeting relevant national standards for the petroleum and natural gas industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the infrared characterization result of AAVH-1;

[0025] Figure 2 The results of heavy oil viscosity reduction performance test of different viscosity reducer aqueous solutions at different concentrations are shown;

[0026] Figure 3 The surface activity test results of different viscosity reducer aqueous solutions at different concentrations;

[0027] Figure 4 The results of oil-water interfacial activity test of different viscosity reducer aqueous solutions at different dosages;

[0028] Figure 5 This is the wetting performance test result of AAVH-2 aqueous solution. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0030] Example 1: A method for preparing an oil-soluble viscosity reducer is as follows:

[0031]

[0032] Where n is 18, R is C 14 Directly linked alkyl, the final product is a mixture, x is 0-5, y is 0-5, z is 0-5.

[0033] (1) Fatty alcohol polyoxyethylene ether acrylate, 2-acrylamido-2-methylpropanesulfonic acid, and 4-(4-vinylphenoxy)-2-hydroxybenzoic acid were weighed in a molar ratio of 1:1:1, and the three were dissolved in cyclohexane to obtain a first solution; the mass ratio of the total weight of fatty alcohol polyoxyethylene ether acrylate, 2-acrylamido-2-methylpropanesulfonic acid, and 4-(4-vinylphenoxy)-2-hydroxybenzoic acid to cyclohexane was 15:85;

[0034] (2) continuously introducing nitrogen into the reaction vessel and maintaining the nitrogen flow for 30 minutes, and adding azobisisobutyronitrile to the first solution to a final concentration of 0.03 wt % to obtain a reaction solution;

[0035] (3) The reaction solution was heated to 80°C for 6 hours, then heated to 110°C for 3 hours, and the organic solvent was completely removed to obtain a light brown transparent liquid product, which was the oil-soluble viscosity reducer AAVH-1. Figure 1 As shown in the infrared spectrum of the polymer, the 3500-3200 cm -1 The broad absorption band at 3040~2959cm corresponds to the stretching vibration of hydroxyl groups; -1 The C—H stretching vibration of the benzene ring is about 1730 cm -1 A strong absorption peak of ester carbonyl (C=O) stretching appears at about 1660 cm -1 The stretching peak of amide group (C=O) appears at about 1600 cm -1 and 1500cm -1 Absorption occurs at about 1180 cm; the S=O stretching vibration of the sulfonic acid group (SO3H) is at about 1180 cm -1 and 1040cm -1 In addition, the C—O—C ether bond in the polyether segment is at about 1100 cm -1 The C—O stretching absorption was observed at the alkyl group. The infrared characterization was consistent with the target compound, indicating that the target polymer was successfully synthesized.

[0036] Example 2: The rest is the same as Example 1, except that:

[0037] n is 12, R is C 18Straight-linked alkyl, x is 0-3, y is 0-7, and z is 0-7.

[0038] The molar ratio of fatty alcohol polyoxyethylene ether acrylate, 2-acrylamido-2-methylpropanesulfonic acid and 4-(4-vinylphenoxy)-2-hydroxybenzoic acid is 1:2:2;

[0039] Toluene was selected as the solvent, and the mass ratio of the total weight of fatty alcohol polyoxyethylene ether acrylate, 2-acrylamido-2-methylpropanesulfonic acid and 4-(4-vinylphenoxy)-2-hydroxybenzoic acid to toluene was 10:90;

[0040] Helium gas was continuously introduced into the reaction container and kept flowing for 40 minutes, and benzoyl peroxide was added to the first solution to a final concentration of 0.01 wt % to obtain a reaction solution;

[0041] The reaction solution was heated to 50°C for 7 hours, and then heated to 120°C for 1 hour to completely remove the organic solvent to obtain the oil-soluble viscosity reducer AAVH-2.

[0042] Example 3: The rest is the same as Example 1, except that:

[0043] n is 16, R is C 12 Straight-linked alkyl, x is 0-5, y is 0-5, z is 0-7.

[0044] The molar ratio of fatty alcohol polyoxyethylene ether acrylate, 2-acrylamido-2-methylpropanesulfonic acid and 4-(4-vinylphenoxy)-2-hydroxybenzoic acid is 1:1:1.5;

[0045] Xylene was selected as the solvent, and the mass ratio of the total weight of fatty alcohol polyoxyethylene ether acrylate, 2-acrylamido-2-methylpropanesulfonic acid and 4-(4-vinylphenoxy)-2-hydroxybenzoic acid to xylene was 25:75;

[0046] Continuously introducing argon gas into the reaction container and maintaining the argon gas flow for 30 minutes, adding tert-butyl hydroperoxide to the first solution to a final concentration of 0.05 wt %, to obtain a reaction solution;

[0047] The reaction solution was heated to 100° C. for 4 h, and then heated to 100° C. for 6 h to completely remove the organic solvent to obtain the oil-soluble viscosity reducer AAVH-3.

[0048] Comparative Example 1: All other aspects are the same as Example 1, except that 4-(4-vinylphenoxy)-2-hydroxybenzoic acid is not added.

[0049] Comparative Example 2: All other aspects are the same as Example 1, except that fatty alcohol polyoxyethylene ether acrylate is not added.

[0050] Comparative Example 3: All other aspects are the same as Example 1, except that 2-acrylamido-2-methylpropanesulfonic acid is not added.

[0051] Comparative Example 4: The rest is the same as Example 1, except that 4-(4-vinylphenoxy)-2-hydroxybenzoic acid is replaced by the following compound:

[0052]

[0053] The final product is:

[0054]

[0055] Comparative Example 5: The rest is the same as Example 1, except that 4-(4-vinylphenoxy)-2-hydroxybenzoic acid is replaced by the following compound:

[0056]

[0057] The final product is:

[0058]

[0059] Comparative Example 6: The rest is the same as Example 1, except that 4-(4-vinylphenoxy)-2-hydroxybenzoic acid is replaced by the following compound:

[0060]

[0061] The final product is:

[0062]

[0063] Comparative Example 7: The rest is the same as Example 1, except that:

[0064] Replace 4-(4-vinylphenoxy)-2-hydroxybenzoic acid with the following compound:

[0065]

[0066] The final product is:

[0067]

[0068] The stability, heavy oil viscosity reducing performance, surface activity, interfacial activity, and wetting properties of the viscosity reducers prepared in Examples 1-3 and Comparative Examples 1-7 were tested. At the same time, the fatty alcohol polyoxyethylene ether acrylate, 2-acrylamido-2-methylpropanesulfonic acid, and 4-(4-vinylphenoxy)-2-hydroxybenzoic acid in Example 1 were used alone as a control group, and the blank group was water. The experimental method is as follows:

[0069] Stability test:

[0070] The viscosity reducers prepared in Examples 1-3 and Comparative Examples 1-7, as well as fatty alcohol polyoxyethylene ether acrylate, 2-acrylamido-2-methylpropanesulfonic acid, and 4-(4-vinylphenoxy)-2-hydroxybenzoic acid, were dissolved in water to a final concentration of 100 mg / L to obtain viscosity reducer test samples. The viscosity reducer test samples were added to the heavy oil (China South China Sea Offshore Oil) at a volume ratio of 1:1 and mixed to obtain a heavy oil emulsion. The heavy oil emulsion was added to a stoppered graduated cylinder and allowed to stand in a constant temperature water bath at 50°C for 60 minutes. The natural sedimentation dehydration rate was calculated. The results are as follows:

[0071] Table 1 Natural sedimentation dehydration rate of different viscosity reducers

[0072] Group Natural sedimentation dehydration rate (%) Example 1 83.9 Example 2 78.9 Example 3 80.2 Comparative Example 1 57.6 Comparative Example 2 49.2 Comparative Example 3 46.1 Comparative Example 4 35.7 Comparative Example 5 54.3 Comparative Example 6 45.8 Comparative Example 7 42.4 Fatty alcohol polyoxyethylene ether acrylate 56.3 2-Acrylamido-2-methylpropanesulfonic acid 60.5 4-(4-vinylphenoxy)-2-hydroxybenzoic acid 44.2 water 18.4

[0073] As shown in Table 1, the results of Comparative Examples 1-3 indicate that lacking any of the three segments does not result in high stability, and the polymer formed by polymerization of any two segments does not effectively improve the stability of the monomer, and may even be slightly lower than the stability of the monomer. Comparative Examples 4-7 demonstrate that the hydroxyl and formate groups on the phenoxyhydroxybenzoic acid residues, as well as their substitution sites, have a certain impact on the stability of the polymer. Furthermore, the oxygen atom connecting the two phenyl groups is also important for polymer stability. Incorrect selection of substituents and substitution sites can easily lead to a significant reduction in the overall stability of the polymer.

[0074] Heavy oil viscosity reduction performance test:

[0075] Different viscosity reducers were dissolved in water to prepare viscosity reducer test samples with different concentrations (0, 100, 200, 300, 400 mg / L). The viscosity reducer test samples with different concentrations were added to the heavy oil at a volume ratio of 1:1. After mixing, the mixture was kept at 50°C for 1 hour, 250 r / min, and stirred for 2 minutes. The apparent viscosity was measured using an MCR302 rheometer. The results are as follows. Figure 2 As shown by Figure 2 It can be seen that the viscosity reducer prepared by the present invention can effectively reduce the viscosity of heavy oil with increasing concentration, and can significantly reduce the viscosity of heavy oil to below 500mPa·s, showing excellent viscosity reduction performance. The viscosity reduction performance of the polymers formed by any two monomers in Comparative Examples 1-3 is equal to or slightly higher than that of the three monomers, and the viscosity reduction performance is not significantly improved. The viscosity reduction performance of the polymers prepared in Comparative Examples 4-7 is significantly lower than that of Example 1 and the three monomers, indicating that only the phenoxyhydroxybenzoic acid residue can effectively improve the overall viscosity reduction performance of the polymer, and other derivatives with similar structures cannot improve the viscosity reduction performance of the polymer, and there is a phenomenon of weakening the viscosity reduction performance compared with the monomers.

[0076] Surface activity test

[0077] The surface tension of the viscosity reducer at different concentrations was measured using a JK99M6 fully automatic surface tension meter. The surface tension of aqueous solutions of viscosity reducers at different concentrations (0.1, 1, 10, 100, and 1000 mg / L) was tested using a hanging sheet method (Pt, width 24 mm). Each sample was measured three times and the average value was taken. Figure 3 As shown by Figure 3 It can be seen that as the concentration of Examples 1-3 increases, the surface tension decreases and the surface activity increases. Similar to the viscosity reduction performance, the surface activity of Comparative Examples 1-7 and the three monomers at different concentrations is significantly lower than that of Example 1.

[0078] Surface activity test

[0079] The viscosity reducer aqueous solution was used as the aqueous phase, and one drop of oil was slowly injected. The interfacial tension at the interface between the oil drop and the viscosity reducer aqueous solution was measured using a CNG Series Spinning DropTensiometer (CNG Enterprise Limited, USA). The temperature was kept constant at 50°C and the rotation speed was 6000 r / min. The interfacial tension value was tested and recorded. Figure 4 As shown, Figure 4 In Examples 1-3, as the concentration increases, the oil-water interfacial tension decreases and the interfacial activity increases, showing better interfacial activity, while the interfacial activity of Comparative Examples 1-7 is significantly lower than that of Example 1.

[0080] Wetting performance test

[0081] Using Drop Shape Analyzer-DSA30( The contact angles of different viscosity reducer aqueous solutions with a concentration of 100 mg / L on the oil-wet rock surface were measured. The droplet volume was fixed at 3 μL. The contact angles of pure water and viscosity reducer aqueous solutions on the oil-wet rock core surface were compared. The results are shown in Table 2 and Figure 5 As shown:

[0082] Table 2 Wetting performance test results of different viscosity reducer aqueous solutions

[0083]

[0084]

[0085] In Table 2, the wetting properties of Comparative Examples 1-7 are significantly lower than those of Examples 1-3, indicating that the three monomer segments are indispensable, and the phenoxyhydroxybenzoic acid residue plays a key role in improving the various properties of the polymer and cannot be replaced by other similar groups. Figure 5 It can be seen that the contact angle between the AAVH-2 aqueous solution and the oil-wet core surface is significantly reduced, indicating that AAVH-2 has good wettability, which helps it to better cover the rock surface, mix with oil, reduce friction, and improve the collection rate.

Claims

1. A method for preparing an oil-soluble viscosity reducer, characterized in that: The steps include: (1) dissolving fatty alcohol polyoxyethylene ether acrylate, 2-acrylamido-2-methylpropanesulfonic acid and 4-(4-vinylphenoxy)-2-hydroxybenzoic acid in an organic solvent to obtain a first solution; (2) adding an initiator to the first solution under an inert atmosphere to obtain a reaction solution; (3) The reaction solution is heated to react and then the organic solvent is removed to obtain an oil-soluble viscosity reducer.

2. The method for preparing the oil-soluble viscosity reducer according to claim 1, wherein: In step (1), the chemical formula of the fatty alcohol polyoxyethylene ether acrylate is as follows: Where n = 10-20, R is C 12-18 alkyl.

3. The method for preparing the oil-soluble viscosity reducer according to claim 1, wherein: In step (1), the organic solvent includes at least one of cyclohexane, toluene, xylene, and trimethylbenzene.

4. The method for preparing the oil-soluble viscosity reducer according to claim 1, wherein: In step (1), the molar ratio of fatty alcohol polyoxyethylene ether acrylate, 2-acrylamido-2-methylpropanesulfonic acid and 4-(4-vinylphenoxy)-2-hydroxybenzoic acid is 1-2:1-2:1-2, and the mass ratio of the total weight of fatty alcohol polyoxyethylene ether acrylate, 2-acrylamido-2-methylpropanesulfonic acid and 4-(4-vinylphenoxy)-2-hydroxybenzoic acid to the organic solvent is 10-25:75-90.

5. The method for preparing the oil-soluble viscosity reducer according to claim 1, wherein: In step (2), the initiator includes at least one of azobisisobutyronitrile, benzoyl peroxide, and tert-butyl hydroperoxide, and the content of the initiator in the reaction solution is 0.01-0.05 wt%.

6. The method for preparing the oil-soluble viscosity reducer according to claim 1, wherein: In step (2), the inert atmosphere is created as follows: an inert gas is continuously introduced into the reaction vessel, and the inert gas flow is maintained for at least 30 minutes.

7. The method for preparing the oil-soluble viscosity reducer according to claim 6, wherein: The inert gas includes at least one of nitrogen, helium and argon.

8. The method for preparing the oil-soluble viscosity reducer according to claim 1, wherein: In step (3), the heating reaction conditions are: heating the reaction solution to 50-100° C. for 4-7 hours.

9. The method for preparing the oil-soluble viscosity reducer according to claim 8, wherein: In step (3), the method for removing the organic solvent is: heating the reaction solution after the heating reaction to 100-120° C. and performing rotary evaporation for at least 1 hour.

10. Use of the oil-soluble viscosity reducer prepared according to the preparation method according to any one of claims 1 to 9 in reducing the viscosity of heavy oil.

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