Shear-resistant fracturing fluid and preparation method thereof

Abstract

The invention relates to the technical field of petrochemical engineering, in particular to a shear-resistant fracturing fluid and a preparation method thereof.The shear-resistant fracturing fluid is prepared from, by weight, 15-22 parts of a thickening agent, 10-12 parts of modified polyacrylamide, 6-8 parts of a reinforcing additive, 2-2.5 parts of a cross-linking agent, 3-3.5 parts of a clay stabilizer, 1-1.2 parts of a cleanup additive and 1000 parts of water. Therefore, the problem that an existing fracturing fluid is insufficient in shear resistance is solved, the fracturing fluid can still keep good performance after being sheared for a long time under different temperature conditions, and the use performance of the fracturing fluid is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of petrochemical industry, and in particular to a shear-resistant fracturing fluid and a preparation method thereof. Background Art

[0002] Hydraulic fracturing technology is one of the most important technologies for shale gas exploration and development, and fracturing fluid is an important component of hydraulic fracturing technology. Its performance directly affects the success or failure of hydraulic fracturing construction. At present, fracturing fluid is mainly composed of water-soluble polymer thickeners and various additives, which has the advantages of low damage and easy flowback. At present, the main factor that determines the performance of fracturing fluid is its variable shear performance, which affects the transportation, sand carrying, friction and fracturing effect of fracturing fluid, and the commonly used fracturing fluid has gradually failed to meet market demand. Summary of the invention

[0003] The purpose of the present invention is to provide a shear-resistant fracturing fluid and a preparation method thereof, which solves the problem of insufficient shear resistance of the existing fracturing fluid by adding modified polyacrylamide and reinforcing additives, so that the fracturing fluid can still maintain good performance after long-term shearing under different temperature conditions, thereby greatly improving the performance of the fracturing fluid.

[0004] The object of the present invention can be achieved by the following technical scheme: a method for preparing a shear-resistant fracturing fluid, comprising the following steps: weighing the following raw materials in parts by weight: 15-22 parts of a thickener, 10-12 parts of a modified polyacrylamide, 6-8 parts of a reinforcing agent, 2-2.5 parts of a cross-linking agent, 3-3.5 parts of a clay stabilizer, 1-1.2 parts of a drainage agent and 1000 parts of water, mixing the thickener, the modified polyacrylamide, the reinforcing agent, the cross-linking agent, the clay stabilizer, the drainage agent and the water, stirring for 30 minutes at a temperature of 40°C to prepare a shear-resistant fracturing fluid; The thickener is WE-216 thickener, the cross-linking agent is Xuanhao New Material 550 cross-linking agent, the clay stabilizer is Qiquan clay stabilizer, and the drainage aid is Yuxing F3237 drainage aid; The reinforcing aid is prepared by the following steps: Step A1: 4-cyanoaniline, sodium nitrite, hydrochloric acid solution and deionized water are mixed, and the mixture is reacted for 15-20 minutes at a stirring rate of 80-100 rpm and a temperature of 5° C., and phenol, sodium hydroxide and sodium carbonate are added with stirring, and the reaction is continued for 6-8 hours to obtain intermediate 1. Intermediate 1, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 4-dimethylaminopyridine and dichloromethane are mixed, and thioctic acid is added at a stirring rate of 120-140 rpm and room temperature, and the reaction is continued for 24 hours to obtain intermediate 2; The molar concentration of the hydrochloric acid solution is 3 mol / L; the dosage ratio of 4-cyanoaniline, sodium nitrite, hydrochloric acid solution, phenol, sodium hydroxide and sodium carbonate is 0.1-0.11 mol: 0.1-0.11 mol: 140-150 mL: 0.1-0.11 mol: 4-5 g: 15.5-16 g; the dosage ratio of the intermediate 1, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 4-dimethylaminopyridine and thioctic acid is 0.02-0.024 mol: 3.8-3.9 g: 0.5-0.55 g: 0.3-0.32 mol; During the reaction, under acidic conditions and the action of sodium nitrite, 4-cyanoaniline is diazotized, and then undergoes a coupling reaction with phenol to form an azo group to obtain intermediate 1. Then, under the action of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 4-dimethylaminopyridine, the phenolic hydroxyl group in intermediate 1 reacts with the carboxyl group in lipoic acid to form an ester group to obtain intermediate 2. Step A2: γ-aminopropyltriethoxysilane, hydrochloric acid solution and ethanol were mixed, and the mixture was reacted for 18 hours at a stirring rate of 80-100 rpm and a temperature of 90° C., and tetrahydrofuran was added to obtain intermediate 3. Intermediate 3, thioctic acid and tetrahydrofuran were mixed, and the mixture was reacted for 6-8 hours at a stirring rate of 120-140 rpm and a temperature of 60° C. under nitrogen protection to obtain intermediate 4; The mass concentration of the hydrochloric acid solution is 15%, the dosage ratio of γ-aminopropyltriethoxysilane, hydrochloric acid solution, ethanol and tetrahydrofuran is 0.02-0.03 mol: 7.5-8 mL: 70-80 mL: 60-62 mL; the dosage ratio of intermediate 3 and thioctic acid is 0.01-0.012 mol: 0.08-0.084 mol; During the reaction, in a hydrochloric acid solution, the silyl ethoxy group in γ-aminopropyltriethoxysilane undergoes hydrolysis and self-condensation to form a cage-type silsesquioxane structure to obtain intermediate 3, wherein the amino group in intermediate 3 reacts with the carboxyl group in lipoic acid to form an amide bond to obtain intermediate 4; Step A3: Sodium isethionate, 4-dimethylaminopyridine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide and dimethyl sulfoxide are mixed, stirred at a stirring rate of 120-150 rpm and room temperature, and lipoic acid is added to react for 4-6 hours to obtain intermediate 5; intermediate 2, intermediate 4, intermediate 5 and tetrahydrofuran are mixed, stirred at a stirring rate of 70-80 rpm and a temperature of 80° C., and reacted for 2-3 hours to obtain a reinforcing agent; The dosage ratio of sodium isethionate, 4-dimethylaminopyridine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide and lipoic acid is 0.01-0.012 mol: 5-6 g: 8-10 g: 0.011-0.012 mol; the dosage ratio of intermediate 2, intermediate 4 and intermediate 5 is 0.01-0.012 mol: 0.003-0.004 mol: 0.02-0.024 mol; During the reaction, under the action of 4-dimethylaminopyridine and 1-ethyl-(3-dimethylaminopropyl)carbodiimide, the hydroxyl group in sodium isethionate reacts with the carboxyl group in lipoic acid to form an ester group, thereby obtaining intermediate 5. Then, at 80°C, the lipoic acid structures in intermediates 2, 4 and 5 open the ring and combine with each other to form a disulfide bond, thereby obtaining a reinforcing agent. The modified polyacrylamide is prepared by the following steps: Step B1: 4-methoxyphenol, potassium carbonate and acetonitrile are mixed, stirred at a rate of 120-140 rpm and a temperature of 80°C, propargyl bromide is added, and the reaction is carried out for 8-10 hours to obtain intermediate a; intermediate a, terephthalate, polyformaldehyde and dichloromethane are mixed, stirred at a rate of 100-120 rpm and room temperature, and the reaction is carried out for 30 minutes, and then boron trifluoride ether is added and allowed to stand for 12 hours to obtain intermediate b; The dosage ratio of 4-methoxyphenol, potassium carbonate and propargyl bromide is 0.018-0.02 mol: 6.5-7 g: 0.019-0.021 mol; the dosage ratio of intermediate a, p-phenylene dimethyl ether, paraformaldehyde and boron trifluoride ether is 0.01-0.011 mol: 0.18-0.2 mol: 11-12 g: 10-12 mL; During the reaction, the phenolic hydroxyl group in 4-methoxyphenol reacts with the bromine in propyne bromide to obtain intermediate a, and then under the action of boron trifluoride etherate, intermediate a and p-phenylene dimethyl ether react with polyformaldehyde to form a cyclic pillar aromatic structure to obtain intermediate b; Step B2: N,N-dimethylacrylamide, 2-bromo-2-methylpropionyl bromide, pentamethyldiethylenetriamine, copper bromide and cyclohexanone are mixed, and the mixture is reacted for 24 hours at a stirring rate of 100-120 rpm and a temperature of 100° C. to obtain polyacrylamide; polyacrylamide, sodium azide and N,N-dimethylformamide are mixed, and the mixture is reacted for 48 hours at a stirring rate of 120-140 rpm and a temperature of 55° C. to obtain azid polyacrylamide; The dosage ratio of N,N-dimethylacrylamide, 2-bromo-2-methylpropionyl bromide, pentamethyldiethylenetriamine, copper bromide and cyclohexanone is 1.2-1.4 mol: 0.02-0.03 mol: 0.018-0.02 mol: 2.5-2.6 g: 65-70 mL; the dosage ratio of polyacrylamide and sodium azide is 10-11 g: 6.5-6.7 g; During the reaction, under the conditions of pentamethyldiethylenetriamine and copper bromide as catalysts and 2-bromo-2-methylpropionyl bromide as initiator, bromine-terminated polyacrylamide was synthesized by ATRP method, and the bromine-terminated polyacrylamide was converted into azide group under the action of sodium azide to obtain azidized polyacrylamide. Step B3: Mixing polyacrylamide azide, intermediate b, copper iodide, diethylenetriamine and tetrahydrofuran, and reacting for 24 hours under nitrogen protection, stirring at a rate of 80-100 rpm, and a temperature of 80° C. to obtain modified polyacrylamide; The ratio of polyacrylamide azide, intermediate b, copper iodide and diethylenetriamine is 10-11 g: 0.1-0.12 mol: 4-5 g: 12-13 g; During the reaction, under the action of copper iodide and diethylenetriamine, the azide group in the middle of the azidized polyacrylamide undergoes a cycloaddition reaction with the alkyne group in the intermediate b to form a 1,2,3-triazole structure, thereby obtaining a modified polyacrylamide. The beneficial effects of the invention are as follows: the invention discloses a shear-resistant fracturing fluid and a preparation method thereof. The invention solves the problem of insufficient shear resistance of the existing fracturing fluid by adding modified polyacrylamide and a reinforcing auxiliary agent, so that the fracturing fluid can maintain good performance after long-term shearing under different temperature conditions, thereby greatly improving the performance of the fracturing fluid. Since the modified polyacrylamide is based on N,N-dimethylacrylamide as a monomer, and a pillar aromatic structure is grafted at the end through a triazole structure, and the reinforcing auxiliary agent contains electron-withdrawing cyano and sulfonic acid groups, the electron-withdrawing cyano and sulfonic acid groups can be guided into the cyclic pillar aromatic structure under the action of the triazole group, thereby generating a host-guest compatibility effect, so that the modified polyacrylamide is combined with the reinforcing auxiliary agent. Since the reinforcing auxiliary agent contains a cage-type silsesquioxane structure and is polymerized through a disulfide bond, the modified polyacrylamide has good shear resistance. During the shearing process, the disulfide bond and the host-guest effect will first be broken or disassembled, but due to its own characteristics, the original performance can be restored, thereby avoiding a significant decrease in its performance due to long-term shearing. DETAILED DESCRIPTION

[0005] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0006] Example 1 A method for preparing a shear-resistant fracturing fluid comprises the following steps: weighing the following raw materials in parts by weight: 15 parts of a commercially available WE-216 thickener, 10 parts of a modified polyacrylamide, 6 parts of a reinforcing agent, 2 parts of a commercially available Xuanhao New Material 550 cross-linking agent, 3 parts of a commercially available Qiquan clay stabilizer, 1 part of a commercially available Yuxing F3237 drainage aid, and 1000 parts of water, mixing the thickener, modified polyacrylamide, the reinforcing agent, the cross-linking agent, the clay stabilizer, the drainage aid, and the water, stirring for 30 minutes at a temperature of 40° C., to prepare a shear-resistant fracturing fluid; The reinforcing aid is prepared by the following steps: Step A1: 4-cyanoaniline, sodium nitrite, hydrochloric acid solution and deionized water were mixed, and the mixture was reacted for 15 min at a stirring rate of 80 rpm and a temperature of 5° C., and phenol, sodium hydroxide and sodium carbonate were added with stirring, and the reaction was continued for 6 h to obtain intermediate 1. Intermediate 1, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 4-dimethylaminopyridine and dichloromethane were mixed, and thioctic acid was added at a stirring rate of 120 rpm and room temperature, and the reaction was continued for 24 h to obtain intermediate 2; The molar concentration of the hydrochloric acid solution is 3 mol / L, and the amount ratio of 4-cyanoaniline, sodium nitrite, hydrochloric acid solution, phenol, sodium hydroxide and sodium carbonate is 0.1 mol: 0.1 mol: 140 mL: 0.1 mol: 4 g: 15.5 g; the amount ratio of intermediate 1, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 4-dimethylaminopyridine and thioctic acid is 0.02 mol: 3.8 g: 0.5 g: 0.3 mol; Step A2: γ-aminopropyltriethoxysilane, hydrochloric acid solution and ethanol were mixed, and the mixture was reacted for 18 hours at a stirring rate of 80 rpm and a temperature of 90° C., and tetrahydrofuran was added to obtain intermediate 3. Intermediate 3, thioctic acid and tetrahydrofuran were mixed, and the mixture was reacted for 6 hours at a stirring rate of 120 rpm and a temperature of 60° C. under nitrogen protection to obtain intermediate 4; The mass concentration of the hydrochloric acid solution is 15%, the amount ratio of γ-aminopropyltriethoxysilane, hydrochloric acid solution, ethanol and tetrahydrofuran is 0.02 mol: 7.5 mL: 70 mL: 60 mL; the amount ratio of intermediate 3 and thioctic acid is 0.01 mol: 0.08 mol; Step A3: Sodium isethionate, 4-dimethylaminopyridine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide and dimethyl sulfoxide were mixed, stirred at a stirring rate of 120 rpm and room temperature, and lipoic acid was added to react for 4 hours to obtain intermediate 5; intermediate 2, intermediate 4, intermediate 5 and tetrahydrofuran were mixed, stirred at a stirring rate of 70 rpm and a temperature of 80° C., and reacted for 2 hours to obtain a reinforcing agent; The amount ratio of sodium isethionate, 4-dimethylaminopyridine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide and lipoic acid is 0.01 mol: 5 g: 8 g: 0.011 mol; the amount ratio of intermediate 2, intermediate 4 and intermediate 5 is 0.01 mol: 0.003 mol: 0.02 mol; The modified polyacrylamide is prepared by the following steps: Step B1: 4-methoxyphenol, potassium carbonate and acetonitrile were mixed, stirred at a stirring rate of 120 rpm and a temperature of 80°C, propargyl bromide was added, and the reaction was carried out for 8 hours to obtain intermediate a; intermediate a, terephthalate, paraformaldehyde and dichloromethane were mixed, stirred at a rate of 100 rpm and room temperature, and the reaction was carried out for 30 minutes, and then boron trifluoride ether was added and allowed to stand for 12 hours to obtain intermediate b; The ratio of 4-methoxyphenol, potassium carbonate and propargyl bromide is 0.018 mol: 6.5 g: 0.019 mol; the ratio of intermediate a, p-phenylene dimethyl ether, paraformaldehyde and boron trifluoride ether is 0.01 mol: 0.18 mol: 11 g: 10 mL; Step B2: N,N-dimethylacrylamide, 2-bromo-2-methylpropionyl bromide, pentamethyldiethylenetriamine, copper bromide and cyclohexanone were mixed, and the mixture was reacted at a stirring rate of 100 rpm and a temperature of 100° C. for 24 hours to obtain polyacrylamide; polyacrylamide, sodium azide and N,N-dimethylformamide were mixed, and the mixture was reacted at a stirring rate of 120 rpm and a temperature of 55° C. for 48 hours to obtain azid polyacrylamide; The dosage ratio of N,N-dimethylacrylamide, 2-bromo-2-methylpropionyl bromide, pentamethyldiethylenetriamine, copper bromide and cyclohexanone is 1.2 mol: 0.02 mol: 0.018 mol: 2.5 g: 65-70 mL; the dosage ratio of polyacrylamide and sodium azide is 10 g: 6.5 g; Step B3: Mix the azid polyacrylamide, intermediate b, copper iodide, diethylenetriamine and tetrahydrofuran, and react for 24 hours under nitrogen protection, at a stirring rate of 80 rpm and a temperature of 80° C. to obtain modified polyacrylamide; The usage ratio of polyacrylamide azidate, intermediate b, copper iodide and diethylenetriamine is 10g:0.1mol:4g:12g.

[0007] Example 2 A method for preparing a shear-resistant fracturing fluid comprises the following steps: weigh the following raw materials in parts by weight: 22 parts of a commercially available WE-216 thickener, 12 parts of a modified polyacrylamide, 6 parts of a reinforcing agent, 2.5 parts of a commercially available Xuanhao New Material 550 cross-linking agent, 3.5 parts of a commercially available Qiquan clay stabilizer, 1 part of a commercially available Yuxing F3237 drainage aid, and 1000 parts of water, mix the thickener, modified polyacrylamide, the reinforcing agent, the cross-linking agent, the clay stabilizer, the drainage aid, and the water, stir for 30 minutes at a temperature of 40°C, and prepare a shear-resistant fracturing fluid; The reinforcing aid is prepared by the following steps: Step A1: 4-cyanoaniline, sodium nitrite, hydrochloric acid solution and deionized water were mixed, and the mixture was reacted for 20 min at a stirring rate of 80 rpm and a temperature of 5° C., and phenol, sodium hydroxide and sodium carbonate were added with stirring, and the reaction was continued for 8 h to obtain intermediate 1. Intermediate 1, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 4-dimethylaminopyridine and dichloromethane were mixed, and thioctic acid was added at a stirring rate of 120 rpm and room temperature, and the reaction was continued for 24 h to obtain intermediate 2; The molar concentration of the hydrochloric acid solution is 3 mol / L, and the amount ratio of 4-cyanoaniline, sodium nitrite, hydrochloric acid solution, phenol, sodium hydroxide and sodium carbonate is 0.11 mol: 0.1 mol: 150 mL: 0.1-0.11 mol: 5 g: 15.5 g; the amount ratio of intermediate 1, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 4-dimethylaminopyridine and thioctic acid is 0.02 mol: 3.9 g: 0.5 g: 0.32 mol; Step A2: γ-aminopropyltriethoxysilane, hydrochloric acid solution and ethanol were mixed, and the mixture was reacted for 18 hours at a stirring rate of 80 rpm and a temperature of 90° C., and tetrahydrofuran was added to obtain intermediate 3. Intermediate 3, thioctic acid and tetrahydrofuran were mixed, and the mixture was reacted for 6 hours at a stirring rate of 140 rpm and a temperature of 60° C. under nitrogen protection to obtain intermediate 4; The mass concentration of the hydrochloric acid solution is 15%, the amount ratio of γ-aminopropyltriethoxysilane, hydrochloric acid solution, ethanol and tetrahydrofuran is 0.03 mol: 7.5 mL: 80 mL: 60 mL; the amount ratio of intermediate 3 and thioctic acid is 0.01 mol: 0.084 mol; Step A3: Sodium isethionate, 4-dimethylaminopyridine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide and dimethyl sulfoxide are mixed, stirred at a stirring rate of 150 rpm and room temperature, and lipoic acid is added to react for 4 hours to obtain intermediate 5; intermediate 2, intermediate 4, intermediate 5 and tetrahydrofuran are mixed, stirred at a stirring rate of 80 rpm and a temperature of 80° C., and reacted for 2 hours to obtain a reinforcing agent; The ratio of sodium isethionate, 4-dimethylaminopyridine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide and lipoic acid is 0.012 mol: 6 g: 8 g: 0.011 mol; the ratio of intermediate 2, intermediate 4 and intermediate 5 is 0.01 mol: 0.004 mol: 0.024 mol; The modified polyacrylamide is prepared by the following steps: Step B1: 4-methoxyphenol, potassium carbonate and acetonitrile were mixed, stirred at a stirring rate of 140 rpm and a temperature of 80°C, propargyl bromide was added, and the reaction was carried out for 8 hours to obtain intermediate a; intermediate a, terephthalate, paraformaldehyde and dichloromethane were mixed, stirred at a rate of 100 rpm and room temperature, and the reaction was carried out for 30 minutes, and then boron trifluoride ether was added and allowed to stand for 12 hours to obtain intermediate b; The ratio of 4-methoxyphenol, potassium carbonate and propargyl bromide is 0.02 mol: 7 g: 0.019 mol; the ratio of intermediate a, p-phenylene dimethyl ether, paraformaldehyde and boron trifluoride ether is 0.01 mol: 0.2 mol: 11 g: 12 mL; Step B2: N,N-dimethylacrylamide, 2-bromo-2-methylpropionyl bromide, pentamethyldiethylenetriamine, copper bromide and cyclohexanone were mixed, and the mixture was reacted at a stirring rate of 120 rpm and a temperature of 100° C. for 24 hours to obtain polyacrylamide; polyacrylamide, sodium azide and N,N-dimethylformamide were mixed, and the mixture was reacted at a stirring rate of 120 rpm and a temperature of 55° C. for 48 hours to obtain azid polyacrylamide; The ratio of N,N-dimethylacrylamide, 2-bromo-2-methylpropionyl bromide, pentamethyldiethylenetriamine, copper bromide and cyclohexanone is 1.4 mol: 0.02 mol: 0.02 mol: 2.5 g: 70 mL; the ratio of polyacrylamide and sodium azide is 11 g: 6.5 g; Step B3: Mixing polyacrylamide azide, intermediate b, copper iodide, diethylenetriamine and tetrahydrofuran, and reacting for 24 hours under nitrogen protection, at a stirring rate of 100 rpm and a temperature of 80° C. to obtain modified polyacrylamide; The usage ratio of polyacrylamide azidate, intermediate b, copper iodide and diethylenetriamine is 10g:0.12mol:5g:12g.

[0008] Example 3 A method for preparing a shear-resistant fracturing fluid comprises the following steps: weighing the following raw materials in parts by weight: 15 parts of a commercially available WE-216 thickener, 12 parts of a modified polyacrylamide, 8 parts of a reinforcing agent, 2.5 parts of a commercially available Xuanhao New Material 550 cross-linking agent, 3.5 parts of a commercially available Qiquan clay stabilizer, 1 part of a commercially available Yuxing F3237 drainage aid, and 1000 parts of water, mixing the thickener, modified polyacrylamide, the reinforcing agent, the cross-linking agent, the clay stabilizer, the drainage aid, and the water, stirring for 30 minutes at a temperature of 40° C., to prepare a shear-resistant fracturing fluid; The reinforcing aid is prepared by the following steps: Step A1: 4-cyanoaniline, sodium nitrite, hydrochloric acid solution and deionized water were mixed, and the mixture was reacted for 20 min at a stirring rate of 100 rpm and a temperature of 5° C., and phenol, sodium hydroxide and sodium carbonate were added with stirring, and the reaction was continued for 8 h to obtain intermediate 1. Intermediate 1, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 4-dimethylaminopyridine and dichloromethane were mixed, and thioctic acid was added at a stirring rate of 140 rpm and room temperature, and the reaction was continued for 24 h to obtain intermediate 2; The molar concentration of the hydrochloric acid solution is 3 mol / L, and the amount ratio of 4-cyanoaniline, sodium nitrite, hydrochloric acid solution, phenol, sodium hydroxide and sodium carbonate is 0.11 mol: 0.11 mol: 150 mL: 0.1 mol: 5 g: 16 g; the amount ratio of intermediate 1, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 4-dimethylaminopyridine and thioctic acid is 0.024 mol: 3.9 g: 0.55 g: 0.32 mol; Step A2: γ-aminopropyltriethoxysilane, hydrochloric acid solution and ethanol were mixed, and the mixture was reacted for 18 hours at a stirring rate of 100 rpm and a temperature of 90° C., and tetrahydrofuran was added to obtain intermediate 3. Intermediate 3, thioctic acid and tetrahydrofuran were mixed, and the mixture was reacted for 8 hours at a stirring rate of 140 rpm and a temperature of 60° C. under nitrogen protection to obtain intermediate 4; The mass concentration of the hydrochloric acid solution is 15%, the amount ratio of γ-aminopropyltriethoxysilane, hydrochloric acid solution, ethanol and tetrahydrofuran is 0.03 mol: 8 mL: 80 mL: 62 mL; the amount ratio of intermediate 3 and thioctic acid is 0.012 mol: 0.084 mol; Step A3: Sodium isethionate, 4-dimethylaminopyridine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide and dimethyl sulfoxide are mixed, stirred at a stirring rate of 150 rpm and room temperature, and lipoic acid is added to react for 4-6 hours to obtain intermediate 5; intermediate 2, intermediate 4, intermediate 5 and tetrahydrofuran are mixed, stirred at a stirring rate of 80 rpm and a temperature of 80° C., and reacted for 3 hours to obtain a reinforcing agent; The amount ratio of sodium isethionate, 4-dimethylaminopyridine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide and lipoic acid is 0.012 mol: 6 g: 10 g: 0.012 mol; the amount ratio of intermediate 2, intermediate 4 and intermediate 5 is 0.012 mol: 0.004 mol: 0.024 mol; The modified polyacrylamide is prepared by the following steps: Step B1: 4-methoxyphenol, potassium carbonate and acetonitrile were mixed, stirred at a stirring rate of 140 rpm and a temperature of 80°C, propargyl bromide was added, and the reaction was carried out for 10 hours to obtain intermediate a; intermediate a, terephthalate, paraformaldehyde and dichloromethane were mixed, stirred at a rate of 120 rpm and room temperature, and the reaction was carried out for 30 minutes, and then boron trifluoride ether was added and allowed to stand for 12 hours to obtain intermediate b; The ratio of 4-methoxyphenol, potassium carbonate and propargyl bromide is 0.02 mol: 7 g: 0.021 mol; the ratio of intermediate a, p-phenylene dimethyl ether, paraformaldehyde and boron trifluoride ether is 0.011 mol: 0.2 mol: 12 g: 12 mL; Step B2: N,N-dimethylacrylamide, 2-bromo-2-methylpropionyl bromide, pentamethyldiethylenetriamine, copper bromide and cyclohexanone were mixed, and the mixture was reacted at a stirring rate of 120 rpm and a temperature of 100° C. for 24 hours to obtain polyacrylamide; polyacrylamide, sodium azide and N,N-dimethylformamide were mixed, and the mixture was reacted at a stirring rate of 140 rpm and a temperature of 55° C. for 48 hours to obtain azid polyacrylamide; The ratio of N,N-dimethylacrylamide, 2-bromo-2-methylpropionyl bromide, pentamethyldiethylenetriamine, copper bromide and cyclohexanone is 1.4 mol: 0.03 mol: 0.02 mol: 2.6 g: 70 mL; the ratio of polyacrylamide and sodium azide is 11 g: 6.7 g; Step B3: Mixing polyacrylamide azide, intermediate b, copper iodide, diethylenetriamine and tetrahydrofuran, and reacting for 24 hours under nitrogen protection, at a stirring rate of 100 rpm and a temperature of 80° C. to obtain modified polyacrylamide; The usage ratio of polyacrylamide azidate, intermediate b, copper iodide and diethylenetriamine is 11g:0.12mol:5g:13g.

[0009] Comparative Example 1 Compared with Example 3, this comparative example is different in that 4-cyanoaniline is replaced by aniline in the preparation process of the reinforcing auxiliary agent in Example 3, and the other steps are the same.

[0010] Comparative Example 2 Compared with Example 3, this comparative example is different in that the intermediate 3 in the preparation process of the reinforcing auxiliary agent in Example 3 is replaced with a commercially available Fangde double-terminated aminosiloxane, and the other steps are the same.

[0011] Comparative Example 3 Compared with Example 3, this comparative example is different in that the intermediate b in the preparation process of the modified polyacrylamide in Example 3 is replaced by phenylacetylene, and the other steps are the same.

[0012] The shear resistant fracturing fluids prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2 and Comparative Example 3 were used to evaluate the shear resistance of the fracturing fluids. The shear resistance of the fracturing fluids was evaluated by using a rheometer. The starting temperature was 25°C and the temperature was increased to the test temperature at a rate of 3°C / min. The test temperatures were 75°C, 85°C and 95°C, respectively. The shear rate was 180s -1 To 30s -1 , and then from 30s -1 To 180s -1 The shearing time for each section is 20 minutes, repeated 5 times, and the apparent viscosity is measured to evaluate its shear resistance. A natural rock core with a diameter of 2.5 cm and a length of 3.75 cm is selected, and the core matrix damage rate is measured with reference to SY / T 5107-2005. The test results are as follows: Table 1 Test results Test items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 75℃ apparent viscosity (mPa·s) 77.16 78.30 79.97 70.20 73.45 71.23 85℃ apparent viscosity (mPa·s) 58.76 60.12 61.58 50.73 52.21 49.40 95℃ apparent viscosity (mPa·s) 55.02 56.41 57.24 45.75 47.52 44.77 Injury rate (%) 11.03 10.91 10.27 11.35 10.96 11.27 It can be seen from the test results in the table shown that when Example 1, Example 2 and Example 3 are compared with Comparative Example 1, Comparative Example 2 and Comparative Example 3, Comparative Example 1 replaces 4-cyanoaniline with aniline in the preparation process of the reinforcing auxiliary agent in Example 3, which lacks a cyano group, resulting in a significant decrease in its performance. Comparative Example 2 replaces intermediate 3 in the preparation process of the reinforcing auxiliary agent in Example 3 with commercially available Fangde double-terminal aminosiloxane, which lacks a silsesquioxane structure, resulting in a significant decrease in its performance. Comparative Example 3 replaces intermediate b in the preparation process of the modified polyacrylamide in Example 3 with phenylacetylene, and its performance is decreased due to the lack of a pillar aromatic structure.

[0013] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0014] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a shear-resistant fracturing fluid, characterized in that: The method comprises the following steps: weighing the following raw materials in parts by weight: 15-22 parts of a thickener, 10-12 parts of modified polyacrylamide, 6-8 parts of a reinforcing agent, 2-2.5 parts of a crosslinking agent, 3-3.5 parts of a clay stabilizer, 1-1.2 parts of a drainage agent and 1000 parts of water, mixing the thickener, modified polyacrylamide, the reinforcing agent, the crosslinking agent, the clay stabilizer, the drainage agent and the water, stirring for 30 minutes at a temperature of 40° C., and preparing a shear-resistant fracturing fluid; The thickener is WE-216 thickener, the cross-linking agent is Xuanhao New Material 550 cross-linking agent, the clay stabilizer is Qiquan clay stabilizer, and the drainage aid is Yuxing F3237 drainage aid.

2. A method for preparing a shear-resistant fracturing fluid, characterized in that: The reinforcing aid is prepared by the following steps: Step A1: 4-cyanoaniline, sodium nitrite, hydrochloric acid solution and deionized water are mixed, and the mixture is reacted for 15-20 minutes at a stirring rate of 80-100 rpm and a temperature of 5° C., and phenol, sodium hydroxide and sodium carbonate are added with stirring, and the reaction is continued for 6-8 hours to obtain intermediate 1. Intermediate 1, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 4-dimethylaminopyridine and dichloromethane are mixed, and thioctic acid is added at a stirring rate of 120-140 rpm and room temperature, and the reaction is continued for 24 hours to obtain intermediate 2; Step A2: γ-aminopropyltriethoxysilane, hydrochloric acid solution and ethanol were mixed, and the mixture was reacted for 18 hours at a stirring rate of 80-100 rpm and a temperature of 90° C., and tetrahydrofuran was added to obtain intermediate 3. Intermediate 3, thioctic acid and tetrahydrofuran were mixed, and the mixture was reacted for 6-8 hours at a stirring rate of 120-140 rpm and a temperature of 60° C. under nitrogen protection to obtain intermediate 4; Step A3: Sodium hydroxyethyl sulfonate, 4-dimethylaminopyridine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide and dimethyl sulfoxide are mixed, stirred at a stirring rate of 120-150 rpm and room temperature, and thioctic acid is added, and the reaction is carried out for 4-6 hours to obtain intermediate 5. Intermediate 2, intermediate 4, intermediate 5 and tetrahydrofuran are mixed, and the reaction is carried out for 2-3 hours at a stirring rate of 70-80 rpm and a temperature of 80°C to obtain a reinforcing agent.

3. The method for preparing a shear-resistant fracturing fluid according to claim 1, characterized in that: In step A1, the molar concentration of the hydrochloric acid solution is 3 mol / L, and the amount ratio of 4-cyanoaniline, sodium nitrite, hydrochloric acid solution, phenol, sodium hydroxide and sodium carbonate is 0.1-0.11 mol: 0.1-0.11 mol: 140-150 mL: 0.1-0.11 mol: 4-5 g: 15.5-16 g; the amount ratio of intermediate 1, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 4-dimethylaminopyridine and thioctic acid is 0.02-0.024 mol: 3.8-3.9 g: 0.5-0.55 g: 0.3-0.32 mol.

4. The method for preparing a shear-resistant fracturing fluid according to claim 1, characterized in that: In step A2: the mass concentration of the hydrochloric acid solution is 15%, the amount ratio of γ-aminopropyltriethoxysilane, hydrochloric acid solution, ethanol and tetrahydrofuran is 0.02-0.03 mol: 7.5-8 mL: 70-80 mL: 60-62 mL; the amount ratio of intermediate 3 and thioctic acid is 0.01-0.012 mol: 0.08-0.084 mol.

5. The method for preparing a shear-resistant fracturing fluid according to claim 1, characterized in that: In step A3, the ratio of sodium hydroxyethyl sulfonate, 4-dimethylaminopyridine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide and thioctic acid is 0.01-0.012 mol: 5-6 g: 8-10 g: 0.011-0.012 mol; the ratio of intermediate 2, intermediate 4 and intermediate 5 is 0.01-0.012 mol: 0.003-0.004 mol: 0.02-0.024 mol.

6. The method for preparing a shear-resistant fracturing fluid according to claim 1, characterized in that: The modified polyacrylamide is prepared by the following steps: Step B1: 4-methoxyphenol, potassium carbonate and acetonitrile are mixed, stirred at a rate of 120-140 rpm and a temperature of 80°C, propargyl bromide is added, and the reaction is carried out for 8-10 hours to obtain intermediate a; intermediate a, terephthalate, polyformaldehyde and dichloromethane are mixed, stirred at a rate of 100-120 rpm and room temperature, and the reaction is carried out for 30 minutes, and then boron trifluoride ether is added and allowed to stand for 12 hours to obtain intermediate b; Step B2: N,N-dimethylacrylamide, 2-bromo-2-methylpropionyl bromide, pentamethyldiethylenetriamine, copper bromide and cyclohexanone are mixed, and the mixture is reacted for 24 hours at a stirring rate of 100-120 rpm and a temperature of 100° C. to obtain polyacrylamide; polyacrylamide, sodium azide and N,N-dimethylformamide are mixed, and the mixture is reacted for 48 hours at a stirring rate of 120-140 rpm and a temperature of 55° C. to obtain azid polyacrylamide; Step B3: Mix the azid polyacrylamide, intermediate b, copper iodide, diethylenetriamine and tetrahydrofuran, and react for 24 hours under nitrogen protection, at a stirring rate of 80-100 rpm and a temperature of 80° C. to obtain modified polyacrylamide.

7. The method for preparing a shear-resistant fracturing fluid according to claim 6, characterized in that: In step B1, the ratio of 4-methoxyphenol, potassium carbonate and propargyl bromide is 0.018-0.02 mol: 6.5-7 g: 0.019-0.021 mol; the ratio of intermediate a, p-phenylene dimethyl ether, paraformaldehyde and boron trifluoride ether is 0.01-0.011 mol: 0.18-0.2 mol: 11-12 g: 10-12 mL.

8. The method for preparing a shear-resistant fracturing fluid according to claim 6, characterized in that: In step B2, the ratio of N,N-dimethylacrylamide, 2-bromo-2-methylpropionyl bromide, pentamethyldiethylenetriamine, copper bromide and cyclohexanone is 1.2-1.4 mol: 0.02-0.03 mol: 0.018-0.02 mol: 2.5-2.6 g: 65-70 mL; the ratio of polyacrylamide and sodium azide is 10-11 g: 6.5-6.7 g.

9. The method for preparing a shear-resistant fracturing fluid according to claim 6, characterized in that: In step B3: the ratio of polyacrylamide azidate, intermediate b, copper iodide and diethylenetriamine is 10-11 g: 0.1-0.12 mol: 4-5 g: 12-13 g.

10. A shear resistant fracturing fluid, characterized in that: Prepared according to any one of claims 1 to 9.