Self-repairing amphiphobic fracturing fluid thickening agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of fracturing fluids, in particular to a self-repairing amphiphobic fracturing fluid thickener as well as a preparation method and application thereof. The self-repairing amphiphobic fracturing fluid thickening agent is prepared from the following raw materials in parts by mass: 15 to 30 parts of N-vinyl formamide, 5 to 10 parts of vinyl furan, 10 to 20 parts of octadecyl acrylate, 5 to 15 parts of 2-acrylamido-2-methylpropanesulfonic acid, 5 to 10 parts of dodecyl acrylate, 40 to 60 parts of a copolymerization regulator, 10 to 30 parts of an alcohol polymer and 2 to 6 parts of N-ethyl maleic imide. 1-3 parts of an emulsifier, 0.5-2 parts of a cross-linking agent and 0.1-1 part of a redox initiation system. The high-viscosity self-repairing fracturing fluid has high viscosity under the action of high temperature or low shear, shows viscosity reduction and excellent self-repairing performance under the action of high shear, is suitable for high-temperature deep well fracturing scenes, and is suitable for large-scale popularization and application.

Description

Technical Field

[0001] The present invention relates to the technical field of fracturing fluids, and particularly to a self-healing double-hydrophobic fracturing fluid thickener, a preparation method thereof, and an application thereof. Background Art

[0002] With the long-term development of oil and gas resources in China and the further increase in the depth of oil wells, the proportion of high-temperature wells with reservoir temperatures exceeding 150°C has been increasing year by year, and traditional fracturing fluid systems are facing severe technical challenges.

[0003] Commonly used fracturing fluids include: water-based fracturing fluids, oil-based fracturing fluids, emulsion fracturing fluids, foam fracturing fluids, acid-based fracturing fluids, etc.; among them, water-based fracturing fluids have become the most widely used fracturing stimulation method at present due to their advantages such as safety, environmental protection, and convenient application.

[0004] As the core component of water-based fracturing fluids, the performance of the thickener directly determines the sand-carrying capacity and fracture conductivity of fracturing operations. Currently, the mainstream double-hydrophobic fracturing fluid thickeners form a dynamic physical cross-linked network through hydrophobic association. Although they can exhibit good apparent viscosity at room temperature, they will expose defects in high-temperature and high-pressure service environments.

[0005] In an environment of continuous high temperature above 160°C for existing double-hydrophobic thickeners, the thermal motion of molecular segments intensifies, resulting in disordered arrangement of hydrophobic groups, irreversible breakage of hydrogen bond networks, and easy conformational transformation of thickener molecular chains under dynamic shear, causing a large viscosity loss rate. This defect in temperature and shear resistance leads to problems such as a sudden drop in sand-carrying capacity and insufficient fracture conductivity during the staged fracturing construction of horizontal wells, seriously affecting the fracturing stimulation effect.

[0006] In view of the above problems, developing a fracturing fluid thickener with shear resistance and temperature resistance has excellent research prospects. Summary of the Invention

[0007] The purpose of the present invention is to solve the disadvantages existing in the prior art, and to provide a self-healing double-hydrophobic fracturing fluid thickener, a preparation method thereof, and an application thereof.

[0008] A self-healing double-hydrophobic fracturing fluid thickener, the raw materials of which include, by mass: 15-30 parts of N-vinylformamide, 5-10 parts of vinyl furan, 10-20 parts of octadecyl acrylate, 5-15 parts of 2-acrylamido-2-methylpropanesulfonic acid, 5-10 parts of dodecyl acrylate, 40-60 parts of copolymerization regulator, 10-30 parts of alcohol polymer, 2-6 parts of N-ethylmaleimide, 1-3 parts of emulsifier, 0.5-2 parts of cross-linking agent, and 0.1-1 part of redox initiation system.

[0009] Preferably, the copolymerization regulator is acrylamide.

[0010] Preferably, the alcohol polymer is polyethylene glycol with a molecular weight of 2000 - 5000.

[0011] Preferably, the emulsifier is dodecylphenol polyoxyethylene ether or / and sodium dodecyl sulfate.

[0012] Preferably, the crosslinking agent is N,N'-methylenebisacrylamide.

[0013] Preferably, the redox system consists of ammonium persulfate and tetramethylethylenediamine.

[0014] More preferably, the mass ratio of ammonium persulfate to tetramethylethylenediamine is 1 - 5:0.5 - 2.

[0015] The preparation method of the above self-healing double-hydrophobic fracturing fluid thickener includes the following steps:

[0016] S1. Add 2-acrylamido-2-methylpropanesulfonic acid to water and stir evenly. Adjust the pH value of the system to 6.9 - 7.2 to obtain a prefabricated liquid.

[0017] S2. Add the emulsifier to deionized water at a temperature of 40 - 50°C and stir evenly. Sequentially add N-vinylformamide, dodecyl acrylate, octadecyl acrylate, and the alcohol polymer, and perform high-speed shear emulsification for 15 - 25 min. Add the prefabricated liquid, copolymerization regulator, and crosslinking agent thereto and stir for 10 - 20 min, then add vinyl furan and N-ethylmaleimide, and heat to 55 - 65°C and stir for 1 - 2 h to obtain a premix.

[0018] S3. Transfer the premix into a reaction kettle protected by nitrogen, add the redox initiation system, raise the temperature to 48 - 52°C and react for 90 - 150 min, then raise the temperature to 70 - 75°C and stir for 5 - 10 h, and then cool to room temperature.

[0019] Preferably, in S1, a sodium hydroxide solution with a concentration of 1 - 2 mol / L is used to adjust the pH value of the system to 6.9 - 7.2.

[0020] The above self-healing double-hydrophobic fracturing fluid thickener is used for high-temperature water-based fracturing fluid.

[0021] Beneficial effects:

[0022] In the present invention, since the vinyl furan molecule contains a furan ring, the conjugated double bond structure thereof can serve as a diene body to provide conjugated electrons, and N-ethyl maleimide has a strong activation effect on the diene body. The two are compounded to form a thermoreversible dynamic bond. The dodecyl acrylate, octadecyl acrylate, and 2-acrylamido-2-methylpropanesulfonic acid are compounded to achieve the dual-hydrophobic synergistic property of being oleophobic in water and hydrophobic in oil through intramolecular complementarity. At the same time, 2-acrylamido-2-methylpropanesulfonic acid contains a sulfonic group that can provide strong hydrophilicity, and is compounded with polyethylene glycol to form a hydrogen bond network, effectively enhancing the thickening ability of the aqueous phase. The dodecyl acrylate and octadecyl acrylate are compounded to form a hydrophobic association network, which synergistically acts with the dynamic bond and hydrogen bond network, and achieves multi-level self-repair through hydrophobic association reorganization, hydrogen bond and dynamic bond repair, with excellent self-repair performance.

[0023] It is found through experiments that in the present invention, the dynamic bond breaks at a high temperature of 160 °C, resulting in a temporary decrease in viscosity. When the temperature returns to 90 °C, the dynamic bond is reorganized, and the viscosity retention rate > 85% (1 h), completing the dynamic cycle.

[0024] The present invention has a high viscosity under high temperature or low shear conditions, while the viscosity decreases under high shear conditions, and has excellent self-repair performance, enabling the product to match the fracturing transformation of high-temperature reservoirs and better withstand mechanical shear and formation shear during application. It is suitable for high-temperature deep well fracturing scenarios and is suitable for large-scale popularization and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a comparison chart of the apparent viscosity and heat resistance of the fracturing fluid thickeners obtained in Example 5 and Comparative Examples 1-3.

[0026] Figure 2 It is a comparison chart of the high-temperature recovery performance and viscosity retention rate of the fracturing fluid thickeners obtained in Example 5 and Comparative Examples 1-3.

[0027] Figure 3 It is a comparison chart of the shear resistance and shear recovery performance of the fracturing fluid thickeners obtained in Example 5 and Comparative Examples 1-3. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention will be further explained below with reference to specific examples.

[0029] Example 1

[0030] A self-healing dual-hydrophobic fracturing fluid thickener, the raw materials of which include: 15 g of N-vinylformamide, 5 g of vinylfuran, 10 g of octadecyl acrylate, 5 g of 2-acrylamido-2-methylpropanesulfonic acid, 5 g of dodecyl acrylate, 40 g of acrylamide, 10 g of polyethylene glycol 2000, 2 g of N-ethylmaleimide, 1 g of sodium dodecyl sulfate, 0.5 g of N,N'-methylenebisacrylamide, and 0.1 g of a redox initiation system. Among them, the redox system is composed of ammonium persulfate and tetramethylethylenediamine in a mass ratio of 2:1.

[0031] The preparation method of the above self-healing dual-hydrophobic fracturing fluid thickener includes the following steps:

[0032] S1. Add 2-acrylamido-2-methylpropanesulfonic acid to deionized water and stir evenly. Adjust the pH value of the system to 6.9 - 7.2 with a 1 mol / L sodium hydroxide solution to obtain a prefabricated solution.

[0033] S2. Add sodium dodecyl sulfate to 500 g of deionized water at a temperature of 40 °C and stir evenly; successively add N-vinylformamide, dodecyl acrylate, octadecyl acrylate, and polyethylene glycol 2000, and perform high-speed shear emulsification at 800 r / min for 15 min to form a uniform emulsion; add the prefabricated solution, acrylamide, and N,N'-methylenebisacrylamide thereto and stir for 10 min at a stirring speed of 100 r / min, then add vinylfuran and N-ethylmaleimide, and heat to 55 °C and stir for 1 h to obtain a premix.

[0034] S3. Transfer the premix to a reaction kettle protected by nitrogen, add the redox initiation system, raise the temperature to 48 °C and react for 90 min, raise the temperature to 70 °C and stir for 5 h, and then cool to room temperature.

[0035] Example 2

[0036] A self-healing dual-hydrophobic fracturing fluid thickener, the raw materials of which include: 30 g of N-vinylformamide, 10 g of vinylfuran, 20 g of octadecyl acrylate, 15 g of 2-acrylamido-2-methylpropanesulfonic acid, 10 g of dodecyl acrylate, 60 g of acrylamide, 30 g of polyethylene glycol 5000, 6 g of N-ethylmaleimide, 3 g of sodium dodecyl sulfate, 2 g of N,N'-methylenebisacrylamide, and 1 g of a redox initiation system. Among them, the redox system is composed of ammonium persulfate and tetramethylethylenediamine in a mass ratio of 5:2.

[0037] The preparation method of the above self-healing dual-hydrophobic fracturing fluid thickener includes the following steps:

[0038] S1. Add 2 - acrylamido - 2 - methylpropanesulfonic acid to deionized water and stir evenly. Adjust the pH value of the system to 6.9 - 7.2 with a 2 mol / L sodium hydroxide solution to obtain a pre - prepared solution.

[0039] S2. Add sodium dodecyl sulfate to 700 g of deionized water at 50 °C and stir evenly. Sequentially add N - vinylformamide, dodecyl acrylate, octadecyl acrylate, and polyethylene glycol 5000, and perform high - speed shear emulsification at 1200 r / min for 25 min to form a uniform emulsion. Add the pre - prepared solution, acrylamide, and N,N’ - methylenebisacrylamide thereto and stir for 20 min at a stirring speed of 500 r / min. Then add vinyl furan and N - ethylmaleimide, heat to 65 °C and stir for 2 h to obtain a pre - mixture.

[0040] S3. Transfer the pre - mixture into a reaction kettle protected by nitrogen, add a redox initiation system, raise the temperature to 52 °C and react for 150 min, then raise the temperature to 75 °C, stir and react for 10 h, and then cool to room temperature.

[0041] Example 3

[0042] A self - healing double - hydrophobic fracturing fluid thickener, the raw materials of which include: 20 g of N - vinylformamide, 9 g of vinyl furan, 12 g of octadecyl acrylate, 12 g of 2 - acrylamido - 2 - methylpropanesulfonic acid, 7 g of dodecyl acrylate, 55 g of acrylamide, 15 g of polyethylene glycol 3000, 5 g of N - ethylmaleimide, 1.5 g of OP - 10, 1.6 g of N,N’ - methylenebisacrylamide, and 0.7 g of a redox initiation system. Among them, the redox system is composed of ammonium persulfate and tetramethylethylenediamine in a mass ratio of 10:7.

[0043] The preparation method of the above - mentioned self - healing double - hydrophobic fracturing fluid thickener includes the following steps:

[0044] S1. Add 2 - acrylamido - 2 - methylpropanesulfonic acid to deionized water and stir evenly. Adjust the pH value of the system to 6.9 - 7.2 with a 1.2 mol / L sodium hydroxide solution to obtain a pre - prepared solution.

[0045] S2. Add OP - 10 to 650 g of deionized water at 45 °C and stir evenly. Sequentially add N - vinylformamide, dodecyl acrylate, octadecyl acrylate, and polyethylene glycol 3000, and perform high - speed shear emulsification at 900 r / min for 22 min to form a uniform emulsion. Add the pre - prepared solution, acrylamide, and N,N’ - methylenebisacrylamide thereto and stir for 12 min at a stirring speed of 400 r / min. Then add vinyl furan and N - ethylmaleimide, heat to 58 °C and stir for 100 min to obtain a pre - mixture.

[0046] S3. Transfer the premix into a reaction kettle protected by nitrogen, add the redox initiation system, heat up to 49 °C and react for 140 min, then heat up to 71 °C, react and stir for 9 h, and cool down to room temperature.

[0047] Example 4

[0048] A self-healing superhydrophobic fracturing fluid thickener, whose raw materials include: 28 g of N-vinylformamide, 7 g of vinyl furan, 18 g of octadecyl acrylate, 8 g of 2-acrylamido-2-methylpropanesulfonic acid, 9 g of dodecyl acrylate, 45 g of acrylamide, 25 g of polyethylene glycol 5000, 3 g of N-ethylmaleimide, 2.5 g of OP-10, 0.8 g of N,N'-methylenebisacrylamide, and 0.3 g of redox initiation system. Among them, the redox system is composed of ammonium persulfate and tetramethylethylenediamine in a mass ratio of 4:1.

[0049] The preparation method of the above self-healing superhydrophobic fracturing fluid thickener includes the following steps:

[0050] S1. Add 2-acrylamido-2-methylpropanesulfonic acid to deionized water and stir evenly. Adjust the pH value of the system to 6.9 - 7.2 with a 1.8 mol / L sodium hydroxide solution to obtain a prefabricated solution.

[0051] S2. Add OP-10 to 550 g of deionized water at a temperature of 45 °C and stir evenly; successively add N-vinylformamide, dodecyl acrylate, octadecyl acrylate, and polyethylene glycol 5000, and perform high-speed shear emulsification at 1100 r / min for 18 min to form a uniform emulsion; add the prefabricated solution, acrylamide, and N,N'-methylenebisacrylamide thereto and stir for 18 min at a stirring speed of 200 r / min, then add vinyl furan and N-ethylmaleimide, heat up to 62 °C and stir for 80 min to obtain a premix.

[0052] S3. Transfer the premix into a reaction kettle protected by nitrogen, add the redox initiation system, heat up to 51 °C and react for 100 min, then heat up to 73 °C, react and stir for 7 h, and cool down to room temperature.

[0053] Example 5

[0054] A self-healing dual-hydrophobic fracturing fluid thickener, the raw materials of which include: 25 g of N-vinylformamide, 8 g of vinylfuran, 15 g of octadecyl acrylate, 10 g of 2-acrylamido-2-methylpropanesulfonic acid, 8 g of dodecyl acrylate, 50 g of acrylamide, 20 g of polyethylene glycol 4000, 4 g of N-ethylmaleimide, 2 g of OP-10, 1.2 g of N,N'-methylenebisacrylamide, and 0.5 g of a redox initiation system. Among them, the redox system is composed of ammonium persulfate and tetramethylethylenediamine in a mass ratio of 5:2.

[0055] The preparation method of the above self-healing dual-hydrophobic fracturing fluid thickener includes the following steps:

[0056] S1. Add 2-acrylamido-2-methylpropanesulfonic acid to deionized water and stir evenly. Adjust the pH value of the system to 6.9 - 7.2 with a 1.5 mol / L sodium hydroxide solution to obtain a prefabricated solution.

[0057] S2. Add OP-10 to 600 g of deionized water at a temperature of 45 °C and stir evenly; successively add N-vinylformamide, dodecyl acrylate, octadecyl acrylate, and polyethylene glycol 4000, and perform high-speed shear emulsification at 1000 r / min for 20 min to form a uniform emulsion; add the prefabricated solution, acrylamide, and N,N'-methylenebisacrylamide thereto and stir for 15 min at a stirring speed of 300 r / min, then add vinylfuran and N-ethylmaleimide, heat to 60 °C and stir for 90 min to obtain a premix.

[0058] S3. Transfer the premix into a reaction kettle protected by nitrogen, add the redox initiation system, raise the temperature to 50 °C and react for 120 min, raise the temperature to 72 °C and react and stir for 8 h, and then cool to room temperature.

[0059] Comparative Example 1

[0060] A self-healing dual-hydrophobic fracturing fluid thickener, the raw materials of which include: 25 g of N-vinylformamide, 15 g of octadecyl acrylate, 10 g of 2-acrylamido-2-methylpropanesulfonic acid, 8 g of dodecyl acrylate, 50 g of acrylamide, 20 g of polyethylene glycol 4000, 12 g of N-ethylmaleimide, 2 g of OP-10, 1.2 g of N,N'-methylenebisacrylamide, and 0.5 g of a redox initiation system. Among them, the redox system is composed of ammonium persulfate and tetramethylethylenediamine in a mass ratio of 5:2.

[0061] The preparation method of the above self-healing dual-hydrophobic fracturing fluid thickener includes the following steps:

[0062] S1. Add 2-acrylamido-2-methylpropanesulfonic acid to deionized water and stir evenly. Adjust the pH value of the system to 6.9 - 7.2 with a 1.5 mol / L sodium hydroxide solution to obtain a prefabricated solution.

[0063] S2. Add OP-10 to 600 g of deionized water at 45 °C and stir evenly. Sequentially add N-vinylformamide, dodecyl acrylate, octadecyl acrylate, and polyethylene glycol 4000, and perform high-speed shear emulsification at 1000 r / min for 20 min to form a uniform emulsion. Add the prefabricated solution, acrylamide, and N,N'-methylenebisacrylamide thereto and stir for 15 min at a stirring speed of 300 r / min. Then add N-ethylmaleimide and heat to 60 °C and stir for 90 min to obtain a premix.

[0064] S3. Transfer the premix into a reaction kettle protected by nitrogen, add a redox initiation system, raise the temperature to 50 °C and react for 120 min, then raise the temperature to 72 °C and stir for 8 h, and then cool to room temperature.

[0065] Comparative Example 2

[0066] A self-healing double-hydrophobic fracturing fluid thickener, the raw materials of which include: 25 g of N-vinylformamide, 8 g of vinyl furan, 15 g of octadecyl acrylate, 30 g of 2-acrylamido-2-methylpropanesulfonic acid, 8 g of dodecyl acrylate, 50 g of acrylamide, 4 g of N-ethylmaleimide, 2 g of OP-10, 1.2 g of N,N'-methylenebisacrylamide, and 0.5 g of a redox initiation system. Among them, the redox system is composed of ammonium persulfate and tetramethylethylenediamine in a mass ratio of 5:2.

[0067] The preparation method of the above self-healing double-hydrophobic fracturing fluid thickener includes the following steps:

[0068] S1. Add 2-acrylamido-2-methylpropanesulfonic acid to deionized water and stir evenly. Adjust the pH value of the system to 6.9 - 7.2 with a 1.5 mol / L sodium hydroxide solution to obtain a prefabricated solution.

[0069] S2. Add OP-10 to 600 g of deionized water at 45 °C and stir evenly. Sequentially add N-vinylformamide, dodecyl acrylate, and octadecyl acrylate, and perform high-speed shear emulsification at 1000 r / min for 20 min to form a uniform emulsion. Add the prefabricated solution, acrylamide, and N,N'-methylenebisacrylamide thereto and stir for 15 min at a stirring speed of 300 r / min. Then add vinyl furan and N-ethylmaleimide and heat to 60 °C and stir for 90 min to obtain a premix.

[0070] S3. Transfer the premix into a reaction kettle protected by nitrogen, add the redox initiation system, heat up to 50 °C and react for 120 min, then heat up to 72 °C, react and stir for 8 h, and then cool down to room temperature.

[0071] Comparative Example 3

[0072] A self-healing superamphiphobic fracturing fluid thickener, the raw materials of which include: 25 g of N-vinylformamide, 8 g of vinylfuran, 23 g of octadecyl acrylate, 10 g of 2-acrylamido-2-methylpropanesulfonic acid, 50 g of acrylamide, 20 g of polyethylene glycol 4000, 4 g of N-ethylmaleimide, 2 g of OP-10, 1.2 g of N,N'-methylenebisacrylamide, and 0.5 g of redox initiation system. Among them, the redox system is composed of ammonium persulfate and tetramethylethylenediamine in a mass ratio of 5:2.

[0073] The preparation method of the above self-healing superamphiphobic fracturing fluid thickener includes the following steps:

[0074] S1. Add 2-acrylamido-2-methylpropanesulfonic acid to deionized water and stir evenly. Adjust the pH value of the system to 6.9 - 7.2 with a 1.5 mol / L sodium hydroxide solution to obtain a prefabricated solution.

[0075] S2. Add OP-10 to 600 g of deionized water at 45 °C and stir evenly; successively add N-vinylformamide, octadecyl acrylate, and polyethylene glycol 4000, and perform high-speed shear emulsification at 1000 r / min for 20 min to form a uniform emulsion; add the prefabricated solution, acrylamide, and N,N'-methylenebisacrylamide thereto and stir for 15 min at a stirring speed of 300 r / min, then add vinylfuran and N-ethylmaleimide, and heat to 60 °C and stir for 90 min to obtain a premix.

[0076] S3. Transfer the premix into a reaction kettle protected by nitrogen, add the redox initiation system, heat up to 50 °C and react for 120 min, then heat up to 72 °C, react and stir for 8 h, and then cool down to room temperature.

[0077] Perform performance tests on the fracturing fluid thickeners obtained in Example 5 and Comparative Examples 1 - 3, specifically as follows:

[0078] 1. Weigh 959.9 g of distilled water accurately into a clean 2 L beaker, successively add 55.00 g of sodium chloride, 20.00 g of potassium chloride, 5.5 g of anhydrous calcium chloride, and 9.6 g of magnesium chloride hexahydrate (wait for each reagent to dissolve completely before adding the next one), and stir evenly to prepare mineralized water with a salinity of 85,000 (abbreviated as 85,000 mineralized water).

[0079] 2. Test the apparent viscosity: Place a beaker containing 400 mL of the mineralized water from the Bawanwu Mine on a stirrer, adjust the rotation speed to 400 r / min, weigh 4.0 g of each group of samples, add them to the above-mentioned mineralized water, and stir for 1 min to obtain the solution to be tested; use a Fann-35 six-speed rotational viscometer to test the apparent viscosity of the solution to be tested at a rotation speed of 100 r / min.

[0080] 3. Test the heat resistance performance: Place a beaker containing 400 mL of the mineralized water from the Bawanwu Mine on a stirrer, adjust the rotation speed to 400 r / min, weigh 4.0 g of each group of samples, add them to the above-mentioned mineralized water, and stir for 1 min to obtain the solution to be tested; place the solution to be tested in a constant-temperature heater at 95 °C, after 15 days, use a Fann-35 six-speed rotational viscometer to test the apparent viscosity of the solution to be tested at a rotation speed of 100 r / min.

[0081] 4. Test the high-temperature recovery performance: Place a beaker containing 400 mL of the mineralized water from the Bawanwu Mine on a stirrer, adjust the rotation speed to 400 r / min, weigh 4.0 g of each group of samples, add them to the above-mentioned mineralized water, and stir for 1 min to obtain the solution to be tested; heat the solution to be tested to 160 °C, adjust the rotation speed to 400 r / min, stir for 6 h, then lower the temperature to 90 °C and continue to stir for 60 min; then use a Fann-35 six-speed rotational viscometer to test the apparent viscosity of the solution to be tested at a rotation speed of 100 r / min and calculate the viscosity retention rate.

[0082] 5. Test the shear resistance performance: Place a beaker containing 400 mL of the mineralized water from the Bawanwu Mine on a stirrer, adjust the rotation speed to 400 r / min, weigh 4.0 g of each group of samples, add them to the above-mentioned mineralized water, and stir for 1 min to obtain the solution to be tested; place the solution to be tested on a variable-frequency high-speed stirrer and stir at 10,000 r / min for 30 min. After the high-speed stirring is completed, use a Fann-35 six-speed rotational viscometer to test the apparent viscosity of the solution to be tested at a rotation speed of 100 r / min.

[0083] 6. Test the recovery performance after shear: After the solution to be tested after the shear resistance performance test is left to stand for 5 min, use a Fann-35 six-speed rotational viscometer to test the apparent viscosity of the solution to be tested at a rotation speed of 100 r / min.

[0084] As Figure 1 shown, the apparent viscosity of the fracturing fluid thickener obtained in Example 5 is the highest, significantly superior to that of Comparative Example 2 and Comparative Example 3, but there is no significant difference from that of Comparative Example 1; and the heat resistance performance of the fracturing fluid thickener obtained in Example 5 is also the highest, significantly superior to that of Comparative Example 1, Comparative Example 2 and Comparative Example 3.

[0085] As Figure 2As shown, the high-temperature recovery performance and viscosity retention rate of the fracturing fluid thickener obtained in Example 5 are the highest, significantly superior to those of Comparative Example 1, Comparative Example 2, and Comparative Example 3.

[0086] As Figure 3 shown, the shear resistance of the fracturing fluid thickener obtained in Example 5 is the highest, significantly superior to those of Comparative Example 1, Comparative Example 2, and Comparative Example 3; and the post-shear recovery performance of the fracturing fluid thickener obtained in Example 5 is also the highest, significantly superior to those of Comparative Example 2 and Comparative Example 3, but there is no significant difference from Comparative Example 1.

[0087] The applicant believes that: This is because the present invention utilizes the fact that the vinyl furan molecule contains a furan ring, and its conjugated double bond structure can act as a diene body to provide conjugated electrons, while N-ethylmaleimide has a strong activating effect on the diene body, and the two are compounded to form a thermoreversible dynamic bond. The compounding of dodecyl acrylate, octadecyl acrylate, and 2-acrylamido-2-methylpropanesulfonic acid realizes the double-hydrophobic synergistic property of hydrophobic in water and hydrophilic in oil through intramolecular complementarity. At the same time, 2-acrylamido-2-methylpropanesulfonic acid contains a sulfonic acid group that can provide strong hydrophilicity, and its compounding with polyethylene glycol forms a hydrogen bond network to effectively enhance the water-phase thickening ability; the compounding of dodecyl acrylate and octadecyl acrylate forms a hydrophobic association network that synergistically acts with the dynamic bond and hydrogen bond network, and realizes multi-level self-repair through hydrophobic association recombination, hydrogen bond, and dynamic bond repair, with excellent self-repair performance.

[0088] As mentioned above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A self-healing superamphiphobic fracturing fluid thickener, characterized in that, Its raw materials by mass parts include: 15-30 parts of N-vinylformamide, 5-10 parts of vinyl furan, 10-20 parts of octadecyl acrylate, 5-15 parts of 2-acrylamido-2-methylpropanesulfonic acid, 5-10 parts of dodecyl acrylate, 40-60 parts of copolymerization regulator, 10-30 parts of alcohol polymer, 2-6 parts of N-ethylmaleimide, 1-3 parts of emulsifier, 0.5-2 parts of crosslinking agent, and 0.1-1 part of redox initiation system.

2. The self-healing double-hydrophobic fracturing fluid thickener according to claim 1, characterized in that, The copolymerization regulator is acrylamide.

3. The self-healing double-hydrophobic fracturing fluid thickener according to claim 1, wherein The alcohol polymer is polyethylene glycol with a molecular weight of 2000-5000.

4. The self-healing superhydrophobic fracturing fluid thickener according to claim 1, wherein, The emulsifier is dodecylphenol polyoxyethylene ether or / and sodium dodecyl sulfate.

5. The self-healing superhydrophobic fracturing fluid thickener according to claim 1, characterized in that, The crosslinking agent is N,N'-methylenebisacrylamide.

6. The self-healing double-hydrophobic fracturing fluid thickener according to claim 1, characterized in that, The redox system consists of ammonium persulfate and tetramethylethylenediamine.

7. The self-healing dual-hydrophobic fracturing fluid thickener according to claim 6, wherein The mass ratio of ammonium persulfate to tetramethylethylenediamine is 1-5:0.5-2.

8. A preparation method of the self-healing double-hydrophobic fracturing fluid thickener according to any one of claims 1-7, characterized in that, It includes the following steps: S1. Add 2-acrylamido-2-methylpropanesulfonic acid into water and stir evenly, adjust the pH value of the system to 6.9-7.2 to obtain a prefabricated solution. S2. Add the emulsifier into deionized water at a temperature of 40-50°C and stir evenly; successively add N-vinylformamide, dodecyl acrylate, octadecyl acrylate, and alcohol polymer, and carry out high-speed shear emulsification for 15-25 min; add the prefabricated solution, copolymerization regulator, and crosslinking agent thereto and stir for 10-20 min, then add vinyl furan and N-ethylmaleimide, heat to 55-65°C and stir for 1-2 h to obtain a premix. S3. Transfer the premix into a reaction kettle protected by nitrogen, add the redox initiation system, raise the temperature to 48-52°C and react for 90-150 min, raise the temperature to 70-75°C and react and stir for 5-10 h, and then cool to room temperature.

9. The preparation method of the self-healing double-hydrophobic fracturing fluid thickener according to claim 8, characterized in that, In S1, the pH value of the system is adjusted to 6.9-7.2 by using a sodium hydroxide solution with a concentration of 1-2 mol / L.

10. The self-healing double-hydrophobic fracturing fluid thickener according to any one of claims 1-7 is used for high-temperature water-based fracturing fluid.

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