Salt-tolerant and temperature-resistant aqueous thickening agent for fracturing fluid and preparation method thereof

Abstract

The present application relates to the technical field of thickening agent, in particular to a kind of salt-resistant and temperature-resistant water thickening agent for fracturing fluid and preparation method thereof, for solving the problem of insufficient salt resistance and temperature resistance of existing thickening agent, the salt-resistant and temperature-resistant water thickening agent for fracturing fluid is obtained by sulfonic acid base-phenyl ether fluorenyl hyperbranched polyacrylamide, synthesis tetrahydroxy phenyl ether fluorene, with dihydroxyethyl amino propionic acid ethyl ester to obtain intermediate product 1 containing phenyl ether fluorenyl, intermediate product 1 and maleic anhydride synthesis intermediate product 2, intermediate product 2 and acrylic acid, acrylamide, 2-acrylamido-2-methylpropane sulfonic acid polymerization obtain sulfonic acid base-phenyl ether fluorenyl hyperbranched polyacrylamide, phenyl ether has good thermal stability, cooperates with fluorenyl to improve the temperature resistance of polymer, sulfonic acid group can effectively shield sodium ion, calcium ion and other cations Compression effect on polymer chain, improve the salt resistance of polymer, enhance the stability and strength of thickening agent.

Description

Technical Field

[0001] This invention relates to the field of thickener technology, specifically to a salt- and temperature-resistant water-resistant thickener for fracturing fluid and its preparation method. Background Technology

[0002] Fracturing fluid is an important processing agent in oil and gas field development, mainly used to increase the production of oil and gas wells. During fracturing, the fracturing fluid needs to withstand high temperature and high salinity environments to ensure its effectiveness and durability. The role of thickener is to ensure that the fracturing fluid maintains good performance under high temperature and high salinity conditions. Traditional fracturing fluid thickeners often fail to maintain good performance under high temperature or high salinity conditions, which limits their application in oil and gas field development. Although some existing thickeners can resist high temperature or high salinity, their overall performance under these two environmental factors is still not ideal and cannot meet the requirements of practical use. Therefore, this invention provides a salt- and temperature-resistant water-based thickener for fracturing fluid and its preparation method, which can effectively improve the stability of fracturing fluid in high temperature and high salinity environments. Summary of the Invention

[0003] In order to overcome the above-mentioned technical problems, the present invention aims to provide a salt- and temperature-resistant water-based thickener for fracturing fluid and its preparation method, thereby solving the problem of insufficient salt and temperature resistance of existing thickeners.

[0004] The objective of this invention can be achieved through the following technical solutions: In a first aspect, this application provides a method for preparing a salt- and temperature-resistant water-based thickener for fracturing fluid, comprising the following steps: Step A1: 2,7-Dibromo-9-fluorenone, 4-formylphenylboronic acid, 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride, tetrabutylammonium fluoride, tetrahydrofuran, and N,N-dimethylformamide were added to a four-necked flask equipped with a stirrer, thermometer, and reflux condenser. The mixture was stirred for 5-10 min, and then tripotassium phosphate-N,N-dimethylformamide solution was added dropwise. The mixture was purged with nitrogen three times, stirred at 60 °C for 2 h, heated to 70 °C, and reacted for 12 h. After cooling, saturated ammonium chloride solution was added, and the mixture was extracted with ethyl acetate. The organic phases were combined, washed three times with saturated brine, dried with anhydrous sodium sulfate, purified by petroleum ether silica gel column chromatography, and dried to obtain diformylfluorenone.

[0005] Step A2: Add 4,4'-diaminodiphenyl ether, anhydrous ethanol, and acetic acid solution to a four-necked flask equipped with a stirrer, thermometer, and reflux condenser. Stir for 30 min. Dissolve diformylfluorenone in dichloromethane and add it dropwise to the flask. Purge with nitrogen for protection and react at 70 °C for 8 h. Cool and adjust the pH to 7 with triethylamine. Combine the organic phases, wash twice with saturated sodium carbonate solution, dry with anhydrous sodium sulfate, concentrate under reduced pressure, purify by silica gel column chromatography with dichloromethane / methanol mixed solvent, and dry to obtain diaminophenyl ether fluorenone.

[0006] Step A3: Add diaminophenyl fluorene ketone and hydrochloric acid solution to a three-necked flask equipped with a thermometer and a stirrer, let stand for 30 min, add phenol and taurine solution, purge with nitrogen for protection, react at 65 °C for 10 h, raise the temperature to 70 °C and react for 4 h, cool, add to deionized water, stir until solid precipitates, filter under reduced pressure, dry to obtain dihydroxy-diaminophenyl fluorene;

[0007] Step A4: Add p-hydroxybenzaldehyde, dihydroxy-diaminophenyl fluorene, N,N-dimethylformamide and anhydrous ethanol to a three-necked flask equipped with a thermometer and a stirrer, sonicate for 20-30 min, stir and react at 70℃ for 8 h, raise the temperature to 80℃ and react for 6 h, filter, wash 5-7 times with ethanol solution, and dry to obtain tetrahydroxyphenyl fluorene;

[0008] Step A5: Add diethanolamine and methanol to a three-necked flask equipped with a stirrer and thermometer, stir for 10-20 min, add ethyl acrylate dropwise, control the dropwise addition time to 1 h, stir the reaction at 45 °C for 5 h, remove methanol and ethyl acrylate by rotary evaporation to obtain ethyl dihydroxyethylaminopropionate.

[0009] Step A6: Add tetrahydroxyphenyl ether fluorene, p-toluenesulfonic acid and N,N-dimethylformamide to a three-necked flask equipped with a thermometer and a stirrer, stir for 10-20 min, add ethyl dihydroxyethylaminopropionate, stir and react at 110 °C for 6 h, remove N,N-dimethylformamide by rotary evaporation to obtain intermediate product 1.

[0010] Step A7: Add intermediate product 1 and N,N-dimethylformamide to a three-necked flask equipped with a stirrer and thermometer, stir for 20-30 min, add maleic anhydride and p-toluenesulfonic acid, stir and react at 110℃ for 6 h, cool, adjust the pH to 7-8 with saturated sodium bicarbonate solution, and evaporate by rotary evaporation to obtain intermediate product 2. Step A8: Add acrylic acid, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and deionized water to a three-necked flask equipped with a stirrer and thermometer, stir for 10-20 min, adjust the pH to 7 with sodium hydroxide solution, add intermediate product 2 and stir for 20-30 min, add ammonium persulfate and sodium bisulfate and stir for 10-20 min, purge with nitrogen gas, seal and react at 40℃ for 6 h, cool, add to ethanol for purification, dry to obtain a salt- and temperature-resistant water-based thickener for fracturing fluid.

[0011] As a further embodiment of the present invention: the ratio of the amounts of 2,7-dibromo-9-fluorenone, 4-formylphenylboronic acid, 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride, tetrabutylammonium fluoride, tetrahydrofuran, N,N-dimethylformamide, and tripotassium phosphate-N,N-dimethylformamide solution in step A1 is 0.01-0.02 mmol: 0.3-0.6 mmol: 0.01-0.02 mmol: 0.01-0.02 mmol: 50-100 mL: 20-40 mL: 5-10 mL.

[0012] As a further aspect of the present invention: the molar concentration of the tripotassium phosphate-N,N-dimethylformamide solution in step A1 is 0.06 mmol / mL.

[0013] As a further embodiment of the present invention: the ratio of the amounts of 4,4'-diaminodiphenyl ether, anhydrous ethanol, acetic acid solution, diformylfluorenone and dichloromethane used in step A2 is 0.01-0.02 mol: 30-60 mL: 3-6 mL: 0.01-0.02 mol: 20-40 mL.

[0014] As a further aspect of the present invention: the molar concentration of the acetic acid solution in step A2 is 0.05 mol / L.

[0015] As a further aspect of the present invention: the volume ratio of dichloromethane to methanol in the dichloromethane / methanol mixed solvent in step A2 is 15:1.

[0016] As a further aspect of the present invention: the ratio of the amount of diaminophenyl ether fluorenone, hydrochloric acid solution, phenol and taurine solution used in step A3 is 0.01-0.02 mol: 10-20 mL: 40-80 mmol: 40-80 mL.

[0017] As a further aspect of the present invention: the molar concentration of the hydrochloric acid solution in step A3 is 0.05 mol / L.

[0018] As a further aspect of the present invention: the taurine solution in step A3 has a mass fraction of 0.2%.

[0019] As a further embodiment of the present invention: the ratio of the amount of p-hydroxybenzaldehyde, dihydroxy-diaminophenyl ether fluorene, N,N-dimethylformamide and anhydrous ethanol used in step A4 is 0.02-0.04 mol: 0.01-0.02 mol: 20-40 mL: 40-80 mL.

[0020] As a further aspect of the present invention: the mass fraction of the ethanol solution in step A4 is 95%.

[0021] As a further aspect of the present invention: the ratio of diethanolamine, methanol and ethyl acrylate used in step A5 is 0.5-1 mol: 40-80 mL: 0.5-1 mol.

[0022] As a further embodiment of the present invention: the ratio of tetrahydroxyphenyl fluorene, p-toluenesulfonic acid, N,N-dimethylformamide and ethyl dihydroxyethylaminopropionate in step A6 is 0.01-0.02 mol: 0.4-0.8 g: 50-100 mL: 0.04-0.08 mol.

[0023] As a further embodiment of the present invention: the ratio of intermediate product 1, N,N-dimethylformamide, maleic anhydride and p-toluenesulfonic acid in step A7 is 0.01-0.02 mol: 50-100 mL: 0.08-0.16 mol: 0.45-0.9 g.

[0024] As a further embodiment of the present invention: the ratio of acrylic acid, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, deionized water, intermediate product 2, ammonium persulfate and sodium bisulfate in step A8 is 0.017-0.034 mol: 0.068-0.136 mol: 0.147-0.294 mol: 200-400 mL: 0.003-0.006 mol: 0.4166-0.8332 mmol: 0.2083-0.4166 mmol.

[0025] As a further aspect of the present invention: the mass fraction of the sodium hydroxide solution in step A8 is 30%.

[0026] The beneficial effects of this invention are: The present invention discloses a salt- and temperature-resistant water-based thickener for fracturing fluid, which introduces phenyl ether groups, sulfonic acid groups and fluorene groups into polyacrylamide. This not only improves the crosslinking ability and structural stability of the polymer under high temperature environment and enhances its temperature resistance, but also inhibits the destruction of the polymer network structure by sodium ions and calcium ions, thereby improving its salt resistance.

[0027] A salt- and temperature-resistant water-based thickener for fracturing fluid was prepared. First, diformylfluorenone was synthesized from 2,7-dibromo-9-fluorenone and 4-formylphenylboronic acid. Diformylfluorenone reacted with 4,4'-diaminodiphenyl ether to obtain diaminophenyl ether fluorenone. Diaminophenyl ether fluorenone reacted with phenol under taurine catalysis to generate dihydroxy-diaminophenyl ether fluoren. Dihydroxy-diaminophenyl ether fluoren reacted with p-hydroxybenzaldehyde to obtain tetrahydroxyphenyl ether fluoren. Diethanolamine reacted with ethyl acrylate to generate ethyl dihydroxyethylaminopropionate. Ethyl dihydroxyethylaminopropionate reacted with tetrahydroxyphenyl ether fluoren to obtain intermediate 1. Maleic anhydride was activated under p-toluenesulfonic acid catalysis to enhance the electrophilicity of the carbonyl carbon. The terminal hydroxyl group in intermediate 1 underwent nucleophilic addition with the carbonyl carbon to form an ester bond, resulting in a product containing terminal carboxyl and alkenyl groups. Intermediate product 2 is subjected to free radical polymerization with acrylic acid, acrylamide, and 2-acrylamido-2-methylpropanesulfonic acid to obtain sulfonic acid-phenyl ether fluorene-based hyperbranched polyacrylamide, which is a salt- and temperature-resistant water-based thickener for fracturing fluids. The terminal carboxyl group enhances the hydrophilicity of the polymer, and the sulfonic acid group has electrostatic repulsion. When sodium and calcium ions are adsorbed on the polymer molecular chain, causing the molecular chain to curl, it can offset part of the electrostatic shielding effect of metal cations. Furthermore, the strong electron-withdrawing effect of the sulfonic acid group inhibits the hydrolysis of the amide group. The hyperbranched structure formed by polymerization can reduce molecular chain entanglement and improve conformational stability. The rigid conjugated structure of the fluorene group and the aromaticity of the phenyl ether chain work synergistically to improve the temperature resistance of the polymer, ensuring that the thickener still has stable and reliable working performance under conditions of large changes in salinity and temperature. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1: This embodiment describes a method for preparing a salt- and temperature-resistant water-based thickener for fracturing fluid, comprising the following steps: Step A1: 0.01 mmol of 2,7-dibromo-9-fluorenone, 0.3 mmol of 4-formylphenylboronic acid, 0.01 mmol of 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride, 0.01 mmol of tetrabutylammonium fluoride, 50 mL of tetrahydrofuran, and 20 mL of N,N-dimethylformamide were added to a four-necked flask equipped with a stirrer, thermometer, and reflux condenser. The mixture was stirred for 5 min, and 5 mL of 0.06 mmol / mL tripotassium phosphate-N,N-dimethylformamide solution was added dropwise. The mixture was purged with nitrogen three times, stirred at 60 °C for 2 h, heated to 70 °C, and reacted for 12 h. After cooling, a saturated ammonium chloride solution was added, and the mixture was extracted with ethyl acetate. The organic phases were combined, washed three times with saturated brine, dried over anhydrous sodium sulfate, purified by petroleum ether silica gel column chromatography, and dried to obtain diformylfluorenone. Step A2: 0.01 mol 4,4'-diaminodiphenyl ether, 30 mL anhydrous ethanol, and 3 mL 0.05 mol / L acetic acid solution were added to a four-necked flask equipped with a stirrer, thermometer, and reflux condenser. The mixture was stirred for 30 min. 0.01 mol diformylfluorenone was dissolved in 20 mL dichloromethane and added dropwise to the flask. Nitrogen gas was introduced for protection, and the mixture was reacted at 70 °C for 8 h. After cooling, the pH was adjusted to 7 with triethylamine. The organic phases were separated and combined, washed twice with saturated sodium carbonate solution, dried with anhydrous sodium sulfate, concentrated under reduced pressure, purified by silica gel column chromatography with a dichloromethane / methanol mixed solvent, and dried to obtain diaminophenyl ether fluorenone. Step A3: Add 0.01 mol of diaminophenyl fluorene ketone and 10 mL of 0.05 mol / L hydrochloric acid solution to a three-necked flask equipped with a thermometer and a stirrer. Let stand for 30 min, then add 40 mmol of phenol and 40 mL of 0.2% taurine solution. Purge with nitrogen and react at 65 °C for 10 h. Increase the temperature to 70 °C and react for 4 h. Cool and add to deionized water. Stir until a solid precipitates. Filter under reduced pressure and dry to obtain dihydroxy-diaminophenyl fluorene. Step A4: Add 0.02 mol p-hydroxybenzaldehyde, 0.01 mol dihydroxy-diaminophenyl fluorene, 20 mL N,N-dimethylformamide and 40 mL anhydrous ethanol to a three-necked flask equipped with a thermometer and a stirrer. Sonicate for 20 min, stir at 70 °C for 8 h, raise the temperature to 80 °C and react for 6 h. Filter, wash 5 times with 95% ethanol solution, and dry to obtain tetrahydroxyphenyl fluorene. Step A5: Add 0.5 mol diethanolamine and 40 mL methanol to a three-necked flask equipped with a stirrer and thermometer, stir for 10 min, add 0.5 mol ethyl acrylate dropwise, control the dropwise addition time to 1 h, stir the reaction at 45 °C for 5 h, remove methanol and ethyl acrylate by rotary evaporation to obtain ethyl dihydroxyethylaminopropionate. Step A6: Add 0.01 mol tetrahydroxyphenyl ether fluorene, 0.4 g p-toluenesulfonic acid and 50 mL N,N-dimethylformamide to a three-necked flask equipped with a thermometer and a stirrer, stir for 10 min, add 0.04 mol dihydroxyethylaminopropionate, stir and react at 110 °C for 6 h, remove N,N-dimethylformamide by rotary evaporation to obtain intermediate product 1; Step A7: Add 0.01 mol of intermediate product 1 and 50 mL of N,N-dimethylformamide to a three-necked flask equipped with a stirrer and thermometer, stir for 20 min, add 0.08 mol of maleic anhydride and 0.45 g of p-toluenesulfonic acid, stir and react at 110 °C for 6 h, cool, adjust the pH to 7 with saturated sodium bicarbonate solution, and evaporate by rotary evaporation to obtain intermediate product 2; Step A8: Add 0.017 mol acrylic acid, 0.068 mol acrylamide, 0.147 mol 2-acrylamido-2-methylpropanesulfonic acid and 200 mL deionized water to a three-necked flask equipped with a stirrer and thermometer. Stir for 10 min, adjust the pH to 7 with 30% sodium hydroxide solution, add 0.003 mol intermediate product 2 and stir for 20 min, add 0.4166 mmol ammonium persulfate and 0.2083 mmol sodium bisulfate and stir for 10 min, purge with nitrogen gas, seal and react at 40 °C for 6 h, cool, purify in ethanol, dry to obtain a salt- and temperature-resistant water-based thickener for fracturing fluid.

[0030] Example 2: This embodiment describes a method for preparing a salt- and temperature-resistant water-based thickener for fracturing fluid, comprising the following steps: Step A1: 0.015 mmol of 2,7-dibromo-9-fluorenone, 0.45 mmol of 4-formylphenylboronic acid, 0.015 mmol of 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride, 0.015 mmol of tetrabutylammonium fluoride, 75 mL of tetrahydrofuran, and 30 mL of N,N-dimethylformamide were added to a four-necked flask equipped with a stirrer, thermometer, and reflux condenser. The mixture was stirred for 7 min, and 7.5 mL of 0.06 mmol / mL tripotassium phosphate-N,N-dimethylformamide solution was added dropwise. The mixture was purged with nitrogen three times, stirred at 60 °C for 2 h, heated to 70 °C, and reacted for 12 h. After cooling, a saturated ammonium chloride solution was added, and the mixture was extracted with ethyl acetate. The organic phases were combined, washed three times with saturated brine, dried over anhydrous sodium sulfate, purified by petroleum ether silica gel column chromatography, and dried to obtain diformylfluorenone. Step A2: 0.015 mol 4,4'-diaminodiphenyl ether, 45 mL anhydrous ethanol, and 4.5 mL 0.05 mol / L acetic acid solution were added to a four-necked flask equipped with a stirrer, thermometer, and reflux condenser. The mixture was stirred for 30 min. 0.015 mol diformylfluorenone was dissolved in 30 mL dichloromethane and added dropwise to the flask. Nitrogen gas was introduced for protection, and the mixture was reacted at 70 °C for 8 h. After cooling, the pH was adjusted to 7 with triethylamine. The organic phases were separated and combined, washed twice with saturated sodium carbonate solution, dried with anhydrous sodium sulfate, concentrated under reduced pressure, purified by silica gel column chromatography with a dichloromethane / methanol mixed solvent, and dried to obtain diaminophenyl ether fluorenone. Step A3: Add 0.015 mol of diaminophenyl fluorene ketone and 15 mL of 0.05 mol / L hydrochloric acid solution to a three-necked flask equipped with a thermometer and a stirrer. Let stand for 30 min, then add 60 mmol of phenol and 60 mL of 0.2% taurine solution. Purge with nitrogen and react at 65 °C for 10 h. Increase the temperature to 70 °C and react for 4 h. Cool and add to deionized water. Stir until a solid precipitates. Filter under reduced pressure and dry to obtain dihydroxy-diaminophenyl fluorene. Step A4: Add 0.03 mol p-hydroxybenzaldehyde, 0.015 mol dihydroxy-diaminophenyl fluorene, 30 mL N,N-dimethylformamide and 60 mL anhydrous ethanol to a three-necked flask equipped with a thermometer and a stirrer. Sonicate for 25 min, stir at 70 °C for 8 h, raise the temperature to 80 °C and react for 6 h. Filter, wash 6 times with 95% ethanol solution, and dry to obtain tetrahydroxyphenyl fluorene. Step A5: Add 0.75 mol diethanolamine and 60 mL methanol to a three-necked flask equipped with a stirrer and thermometer, stir for 15 min, add 0.75 mol ethyl acrylate dropwise, control the dropwise addition time to 1 h, stir the reaction at 45 °C for 5 h, remove methanol and ethyl acrylate by rotary evaporation to obtain ethyl dihydroxyethylaminopropionate. Step A6: Add 0.015 mol tetrahydroxyphenyl ether fluorene, 0.6 g p-toluenesulfonic acid and 75 mL N,N-dimethylformamide to a three-necked flask equipped with a thermometer and a stirrer, stir for 15 min, add 0.06 mol dihydroxyethylaminopropionate, stir and react at 110 °C for 6 h, remove N,N-dimethylformamide by rotary evaporation to obtain intermediate product 1; Step A7: Add 0.015 mol of intermediate product 1 and 75 mL of N,N-dimethylformamide to a three-necked flask equipped with a stirrer and thermometer, stir for 25 min, add 0.12 mol of maleic anhydride and 0.675 g of p-toluenesulfonic acid, stir and react at 110 °C for 6 h, cool, adjust the pH to 7 with saturated sodium bicarbonate solution, and evaporate by rotary evaporation to obtain intermediate product 2; Step A8: Add 0.0255 mol acrylic acid, 0.102 mol acrylamide, 0.2205 mol 2-acrylamido-2-methylpropanesulfonic acid and 300 mL deionized water to a three-necked flask equipped with a stirrer and thermometer. Stir for 15 min, adjust the pH to 7 with 30% sodium hydroxide solution, add 0.0045 mol intermediate product 2 and stir for 25 min, add 0.6249 mmol ammonium persulfate and 0.31245 mmol sodium bisulfate and stir for 15 min, purge with nitrogen gas, seal and react at 40 °C for 6 h, cool, purify in ethanol, and dry to obtain a salt- and temperature-resistant water-based thickener for fracturing fluid.

[0031] Example 3: This embodiment describes a method for preparing a salt- and temperature-resistant water-based thickener for fracturing fluid, comprising the following steps: Step A1: 0.02 mmol of 2,7-dibromo-9-fluorenone, 0.6 mmol of 4-formylphenylboronic acid, 0.02 mmol of 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride, 0.02 mmol of tetrabutylammonium fluoride, 100 mL of tetrahydrofuran, and 40 mL of N,N-dimethylformamide were added to a four-necked flask equipped with a stirrer, thermometer, and reflux condenser. The mixture was stirred for 10 min, and 10 mL of 0.06 mmol / mL tripotassium phosphate-N,N-dimethylformamide solution was added dropwise. The mixture was purged with nitrogen three times, stirred at 60 °C for 2 h, heated to 70 °C, and reacted for 12 h. After cooling, a saturated ammonium chloride solution was added, and the mixture was extracted with ethyl acetate. The organic phases were combined, washed three times with saturated brine, dried over anhydrous sodium sulfate, purified by petroleum ether silica gel column chromatography, and dried to obtain diformylfluorenone. Step A2: 0.02 mol 4,4'-diaminodiphenyl ether, 60 mL anhydrous ethanol, and 6 mL 0.05 mol / L acetic acid solution were added to a four-necked flask equipped with a stirrer, thermometer, and reflux condenser. The mixture was stirred for 30 min. 0.02 mol diformylfluorenone was dissolved in 40 mL dichloromethane and added dropwise to the flask. Nitrogen gas was introduced for protection, and the mixture was reacted at 70 °C for 8 h. After cooling, the pH was adjusted to 7 with triethylamine. The organic phases were separated and combined, washed twice with saturated sodium carbonate solution, dried with anhydrous sodium sulfate, concentrated under reduced pressure, purified by silica gel column chromatography with a dichloromethane / methanol mixed solvent, and dried to obtain diaminophenyl ether fluorenone. Step A3: Add 0.02 mol of diaminophenyl fluorene ketone and 20 mL of 0.05 mol / L hydrochloric acid solution to a three-necked flask equipped with a thermometer and a stirrer. Let stand for 30 min, then add 80 mmol of phenol and 80 mL of 0.2% taurine solution. Purge with nitrogen and react at 65 °C for 10 h. Increase the temperature to 70 °C and react for 4 h. Cool and add to deionized water. Stir until a solid precipitates. Filter under reduced pressure and dry to obtain dihydroxy-diaminophenyl fluorene. Step A4: Add 0.04 mol p-hydroxybenzaldehyde, 0.02 mol dihydroxy-diaminophenyl fluorene, 40 mL N,N-dimethylformamide and 80 mL anhydrous ethanol to a three-necked flask equipped with a thermometer and a stirrer. Sonicate for 30 min, stir at 70 °C for 8 h, raise the temperature to 80 °C and react for 6 h. Filter, wash 7 times with 95% ethanol solution, and dry to obtain tetrahydroxyphenyl fluorene. Step A5: Add 1 mol of diethanolamine and 80 mL of methanol to a three-necked flask equipped with a stirrer and a thermometer, stir for 20 min, add 1 mol of ethyl acrylate dropwise, control the dropwise addition time to 1 h, stir the reaction at 45 °C for 5 h, remove methanol and ethyl acrylate by rotary evaporation to obtain ethyl dihydroxyethylaminopropionate. Step A6: Add 0.02 mol tetrahydroxyphenyl ether fluorene, 0.8 g p-toluenesulfonic acid and 100 mL N,N-dimethylformamide to a three-necked flask equipped with a thermometer and a stirrer, stir for 20 min, add 0.08 mol dihydroxyethylaminopropionate, stir and react at 110 °C for 6 h, remove N,N-dimethylformamide by rotary evaporation to obtain intermediate product 1; Step A7: Add 0.02 mol of intermediate product 1 and 100 mL of N,N-dimethylformamide to a three-necked flask equipped with a stirrer and thermometer, stir for 30 min, add 0.16 mol of maleic anhydride and 0.9 g of p-toluenesulfonic acid, stir and react at 110 °C for 6 h, cool, adjust the pH to 8 with saturated sodium bicarbonate solution, and evaporate by rotary evaporation to obtain intermediate product 2; Step A8: Add 0.034 mol acrylic acid, 0.136 mol acrylamide, 0.294 mol 2-acrylamido-2-methylpropanesulfonic acid and 400 mL deionized water to a three-necked flask equipped with a stirrer and thermometer. Stir for 20 min, adjust the pH to 7 with 30% sodium hydroxide solution, add 0.006 mol intermediate product 2 and stir for 30 min, add 0.8332 mmol ammonium persulfate and 0.4166 mmol sodium bisulfate and stir for 20 min, purge with nitrogen gas, seal and react at 40 °C for 6 h, cool, purify in ethanol, dry to obtain a salt- and temperature-resistant water-based thickener for fracturing fluid.

[0032] Comparative Example 1: This comparative example illustrates a method for preparing a salt- and temperature-resistant water-based thickener for fracturing fluids, comprising the following steps: Step A1: Add 0.02 mol of 2,7-dihydroxy-9-fluorenone and 20 mL of 0.05 mol / L hydrochloric acid solution to a three-necked flask equipped with a thermometer and a stirrer. Let stand for 30 min, then add 80 mmol of phenol and 80 mL of 0.2% taurine solution. Purge with nitrogen and react at 65 °C for 10 h. Increase the temperature to 70 °C and react for 4 h. Cool, add to deionized water, stir until solid precipitates, filter under reduced pressure, and dry to obtain tetrahydroxyfluorene. Step A2: Add 1 mol of diethanolamine and 80 mL of methanol to a three-necked flask equipped with a stirrer and a thermometer, stir for 20 min, add 1 mol of ethyl acrylate dropwise, control the dropwise addition time to 1 h, stir the reaction at 45 °C for 5 h, remove methanol and ethyl acrylate by rotary evaporation to obtain ethyl dihydroxyethylaminopropionate. Step A3: Add 0.02 mol tetrahydroxyfluorene, 0.8 g p-toluenesulfonic acid and 100 mL N,N-dimethylformamide to a three-necked flask equipped with a thermometer and a stirrer, stir for 20 min, add 0.08 mol dihydroxyethylaminopropionate, stir and react at 110 °C for 6 h, remove N,N-dimethylformamide by rotary evaporation to obtain intermediate product 1; Step A4: Add 0.02 mol of intermediate product 1 and 100 mL of N,N-dimethylformamide to a three-necked flask equipped with a stirrer and thermometer, stir for 30 min, add 0.16 mol of maleic anhydride and 0.9 g of p-toluenesulfonic acid, stir and react at 110 °C for 6 h, cool, adjust the pH to 8 with saturated sodium bicarbonate solution, and evaporate by rotary evaporation to obtain intermediate product 2; Step A5: Add 0.034 mol acrylic acid, 0.136 mol acrylamide, 0.294 mol 2-acrylamido-2-methylpropanesulfonic acid and 400 mL deionized water to a three-necked flask equipped with a stirrer and thermometer. Stir for 20 min, adjust the pH to 7 with 30% sodium hydroxide solution, add 0.006 mol intermediate product 2 and stir for 30 min, add 0.8332 mmol ammonium persulfate and 0.4166 mmol sodium bisulfate and stir for 20 min, purge with nitrogen gas, seal and react at 40 °C for 6 h, cool, purify in ethanol, dry to obtain a salt- and temperature-resistant water-based thickener for fracturing fluid.

[0033] Comparative Example 2: This comparative example illustrates a method for preparing a salt- and temperature-resistant water-based thickener for fracturing fluids, comprising the following steps: Step A1: Add 0.02 mol of 4,4'-dihydroxydiphenyl ether, 0.8 g of p-toluenesulfonic acid and 100 mL of N,N-dimethylformamide to a three-necked flask equipped with a thermometer and a stirrer. Stir for 20 min, add 0.04 mol of ethyl dihydroxyethylaminopropionate, and stir the reaction at 110 °C for 6 h. Remove N,N-dimethylformamide by rotary evaporation to obtain intermediate product 1. Step A2: Add 0.02 mol of intermediate product 1 and 100 mL of N,N-dimethylformamide to a three-necked flask equipped with a stirrer and thermometer, stir for 30 min, add 0.16 mol of maleic anhydride and 0.9 g of p-toluenesulfonic acid, stir and react at 110 °C for 6 h, cool, adjust the pH to 8 with saturated sodium bicarbonate solution, and evaporate by rotary evaporation to obtain intermediate product 2; Step A3: Add 0.034 mol acrylic acid, 0.136 mol acrylamide, 0.294 mol 2-acrylamido-2-methylpropanesulfonic acid and 400 mL deionized water to a three-necked flask equipped with a stirrer and thermometer. Stir for 20 min, adjust the pH to 7 with 30% sodium hydroxide solution, add 0.006 mol intermediate product 2 and stir for 30 min, add 0.8332 mmol ammonium persulfate and 0.4166 mmol sodium bisulfate and stir for 20 min, purge with nitrogen gas, seal and react at 40 °C for 6 h, cool, purify in ethanol, and dry to obtain a salt- and temperature-resistant water-based thickener for fracturing fluid.

[0034] Comparative Example 3: This comparative example illustrates a method for preparing a salt- and temperature-resistant water-based thickener for fracturing fluids, comprising the following steps: 0.034 mol acrylic acid, 0.136 mol acrylamide, 0.294 mol 2-acrylamido-2-methylpropanesulfonic acid, and 400 mL deionized water were added to a three-necked flask equipped with a stirrer and thermometer. The mixture was stirred for 20 min, and the pH was adjusted to 7 with 30% sodium hydroxide solution. 0.8332 mmol ammonium persulfate and 0.4166 mmol sodium bisulfate were added and stirred for 20 min. Nitrogen gas was introduced, and the mixture was sealed and reacted at 40 °C for 6 h. After cooling, the mixture was purified by adding it to ethanol and dried to obtain a salt- and temperature-resistant water-based thickener for fracturing fluid.

[0035] Performance testing: The thickeners of Examples 1-3 and Comparative Examples 1-3 were dissolved in tap water at a concentration of 0.6%, and the solution was diluted with water at a concentration of 170 s. -1 Viscosity was tested by shearing at a shear rate of 2 hours at different temperatures to obtain the viscosity. The thickeners of Examples 1-3 and Comparative Examples 1-3 were dissolved at a concentration of 1.4% in wastewater with a mineralization of 85,000, and subjected to treatment at 120°C for 170 seconds.-1 Viscosity was tested after 2 hours of shearing to obtain the viscosity in wastewater with a mineralization of 85,000. The thickeners of Examples 1-3 and Comparative Examples 1-3 were dissolved in 10% calcium chloride saline solution at a concentration of 1.4%, and then subjected to treatment at 120°C for 170 seconds. -1 Viscosity was measured after 2 hours of shearing in 10% calcium chloride brine.

[0036] Referring to the table above, based on the comparison between Examples 1-3 and Comparative Examples 1-3, it can be seen that the thickener prepared by sulfonic acid-phenyl ether fluorene hyperbranched polyacrylamide has good temperature resistance and salt resistance. Based on the comparison between Example 3 and Comparative Example 1, it can be seen that the viscosity of the thickener prepared by sulfonic acid-phenyl ether fluorene hyperbranched polyacrylamide at different temperatures is greater than that of the thickener prepared by sulfonic acid-fluorene hyperbranched polyacrylamide at different temperatures, indicating that the thickener prepared by sulfonic acid-phenyl ether fluorene hyperbranched polyacrylamide has excellent temperature resistance. Based on the comparison between Example 3 and Comparative Example 2, it can be seen that the viscosity of the thickener prepared by sulfonic acid-phenyl ether fluorene hyperbranched polyacrylamide at different temperatures is greater than that of the thickener prepared by sulfonic acid-phenyl ether fluorene hyperbranched polyacrylamide at different temperatures, indicating that the thickener prepared by sulfonic acid-phenyl ether fluorene hyperbranched polyacrylamide has excellent temperature resistance. Based on the comparison between Example 3 and Comparative Example 3, it can be seen that the viscosity of the thickener prepared by sulfonic acid-phenyl ether fluorene hyperbranched polyacrylamide at different temperatures is greater than that of the thickener prepared by sulfonic acid-based polyacrylamide at different temperatures, indicating that the thickener prepared by sulfonic acid-phenyl ether fluorene hyperbranched polyacrylamide has excellent temperature resistance.

[0037] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0038] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in this application, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a salt- and temperature-resistant thickener for fracturing fluid, characterized in that, Includes the following steps: Step A1: 2,7-Dibromo-9-fluorenone, 4-formylphenylboronic acid, 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride, tetrabutylammonium fluoride, tetrahydrofuran and N,N-dimethylformamide are stirred, tripotassium phosphate-N,N-dimethylformamide solution is added and stirred, and the reaction is heated to obtain diformylfluorenone; Step A2: Add 4,4'-diaminodiphenyl ether, anhydrous ethanol and acetic acid solution to a flask and stir. Dissolve diformylfluorenone in dichloromethane and add it dropwise to the flask to react and obtain diaminophenyl ether fluorenone. Step A3: Let diaminophenyl fluorene ketone and hydrochloric acid solution stand, add phenol and taurine solution to react, and heat the reaction to obtain dihydroxy-diaminophenyl fluorene; Step A4: Sonicate p-hydroxybenzaldehyde, dihydroxy-diaminophenyl fluorene, N,N-dimethylformamide and anhydrous ethanol, stir and react, and heat to obtain tetrahydroxyphenyl fluorene; Step A5: Diethanolamine and methanol are stirred, and ethyl acrylate is added and stirred to react, yielding ethyl dihydroxyethylaminopropionate; Step A6: Tetrahydroxyphenyl ether fluorene, p-toluenesulfonic acid and N,N-dimethylformamide are stirred, and ethyl dihydroxyethylaminopropionate is added and stirred to react, to obtain intermediate product 1; Step A7: Stir intermediate 1 and N,N-dimethylformamide, add maleic anhydride and p-toluenesulfonic acid and stir to react, to obtain intermediate 2; Step A8: Mix acrylic acid, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and deionized water, adjust the pH to 7, add intermediate product 2 and stir, add ammonium persulfate and sodium bisulfate and stir, react to obtain a salt- and temperature-resistant water-based thickener for fracturing fluid.

2. The method for preparing a salt- and temperature-resistant thickener for fracturing fluid according to claim 1, characterized in that, In step A1, the volume ratio of 2,7-dibromo-9-fluorenone, 4-formylphenylboronic acid, 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride, tetrabutylammonium fluoride, tetrahydrofuran, N,N-dimethylformamide, and tripotassium phosphate-N,N-dimethylformamide solution is 0.01-0.02 mmol: 0.3-0.6 mmol: 0.01-0.02 mmol: 0.01-0.02 mmol: 50-100 mL: 20-40 mL: 5-10 mL; the molar concentration of the tripotassium phosphate-N,N-dimethylformamide solution is 0.06 mmol / mL.

3. The method for preparing a salt- and temperature-resistant thickener for fracturing fluid according to claim 1, characterized in that, In step A2, the ratio of 4,4'-diaminodiphenyl ether, anhydrous ethanol, acetic acid solution, diformylfluorenone, and dichloromethane is 0.01-0.02 mol: 30-60 mL: 3-6 mL: 0.01-0.02 mol: 20-40 mL; the molar concentration of the acetic acid solution is 0.05 mol / L.

4. The method for preparing a salt- and temperature-resistant thickener for fracturing fluid according to claim 1, characterized in that, In step A3, the ratio of diaminophenyl ether fluorenone, hydrochloric acid solution, phenol, and taurine is 0.01-0.02 mol: 10-20 mL: 40-80 mmol: 40-80 mL; the molar concentration of the hydrochloric acid solution is 0.05 mol / L; and the mass fraction of the taurine solution is 0.2%.

5. The method for preparing a salt- and temperature-resistant thickener for fracturing fluid according to claim 1, characterized in that, The ratio of p-hydroxybenzaldehyde, dihydroxy-diaminophenyl fluorene, N,N-dimethylformamide and anhydrous ethanol used in step A4 is 0.02-0.04 mol: 0.01-0.02 mol: 20-40 mL: 40-80 mL.

6. The method for preparing a salt- and temperature-resistant thickener for fracturing fluid according to claim 1, characterized in that, The ratio of diethanolamine, methanol, and ethyl acrylate used in step A5 is 0.5-1 mol: 40-80 mL: 0.5-1 mol.

7. The method for preparing a salt- and temperature-resistant thickener for fracturing fluid according to claim 1, characterized in that, The ratio of tetrahydroxyphenyl fluorene, p-toluenesulfonic acid, N,N-dimethylformamide and ethyl dihydroxyethylaminopropionate in step A6 is 0.01-0.02 mol: 0.4-0.8 g: 50-100 mL: 0.04-0.08 mol.

8. The method for preparing a salt- and temperature-resistant thickener for fracturing fluid according to claim 1, characterized in that, The ratio of intermediate product 1, N,N-dimethylformamide, maleic anhydride and p-toluenesulfonic acid used in step A7 is 0.01-0.02 mol: 50-100 mL: 0.08-0.16 mol: 0.45-0.9 g.

9. The method for preparing a salt- and temperature-resistant thickener for fracturing fluid according to claim 1, characterized in that, The ratio of acrylic acid, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, deionized water, intermediate product 2, ammonium persulfate, and sodium bisulfate in step A8 is 0.017-0.034 mol: 0.068-0.136 mol: 0.147-0.294 mol: 200-400 mL: 0.003-0.006 mol: 0.4166-0.8332 mmol: 0.2083-0.4166 mmol.

10. A salt- and temperature-resistant water-based thickener for fracturing fluid, characterized in that, It is prepared using the method for preparing salt- and temperature-resistant water-based thickeners for fracturing fluid as described in any one of claims 1-9.

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