Thickening agent for high-temperature acidification and preparation method thereof

Abstract

The invention relates to a thickening agent for high-temperature acidification and a preparation method thereof, and belongs to the technical field of petroleum additives. The thickening agent is prepared from the following components in percentage by weight: 37 to 45 weight percent of modified CMC thickening agent, 5.2 to 7.0 weight percent of cosolvent, 1.2 to 1.6 weight percent of dispersing aid, 2.4 to 3.1 weight percent of stabilizer and the balance of water, according to the modified CMC thickening agent, carboxymethyl cellulose is used as a matrix, a side chain containing sulphobetaine and cyclosiloxane is introduced for modification, in the process of injecting acid liquor into a well, the cyclosiloxane structure is subjected to hydrolytic condensation, the viscosity of the acid liquor in the well is greatly increased, a slow flow division and continuous high-temperature acid environment is formed underground, the main chain of carboxymethyl cellulose is decomposed and broken gel, and the viscosity of the acid liquor in the well is reduced; further, self-adaptive thickening is formed, and the requirements of underground acidification thickening are met; and meanwhile, the use of refractory polymers is avoided, and the method has profound research significance in the environment-friendly exploitation technology of oil and gas.

Description

Technical Field

[0001] The present invention belongs to the technical field of petroleum additives, and in particular relates to a thickener for high-temperature acidification and a preparation method thereof. Background Art

[0002] In oil and gas well stimulation, acidizing is a key technology for increasing permeability by injecting acid (such as hydrochloric acid or earth acid) into the formation to dissolve rock minerals, expand pore channels, and enhance permeability. However, the low viscosity and rapid acid-rock reaction rate of conventional acid fluids lead to excessive acid consumption near the wellbore, making it difficult to effectively transform deeper formations. Thickeners, as acid fluid additives, increase viscosity and slow the acid-rock reaction rate, enabling deeper migration and uniform dissolution of the acid fluid.

[0003] At present, acrylamide-based multipolymers are commonly used as the main thickener for deep well high-temperature acidizing. Their molecular chains contain temperature-resistant groups (such as sulfonic acid groups and tert-butyl acrylamide), which maintain good stability at high temperatures and thus maintain the viscosity of the acid. In addition, the molecular chains of this type of thickener are highly designable, and thermal stability is improved by introducing temperature-resistant monomers, as well as providing a basic thickening effect at low concentrations. However, this type of polymer thickener has unavoidable defects: the high-temperature depolymerization of the linear polymer chain causes the viscosity to continue to decay, and it is unable to dynamically adapt to changes in well temperature and dissolve, resulting in difficulty in achieving a breakthrough in the production increase effect. In addition, this type of polymer is difficult to degrade naturally, and the post-processing of the returned waste is difficult, which does not meet the needs of environmental protection development. Summary of the Invention

[0004] In order to solve the technical problems mentioned in the background technology, the purpose of the present invention is to provide a thickener for high-temperature acidification and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions: A thickener for high-temperature acidification comprises the following components by weight: 37-45 wt% of a modified CMC thickener, 5.2-7.0 wt% of a cosolvent, 1.2-1.6 wt% of a co-dispersant, 2.4-3.1 wt% of a stabilizer, and the balance being water.

[0006] Among them, the modified CMC thickener is prepared by the following method: Step A1: Carboxymethyl cellulose and anhydrous acetone are mixed and swelled under the protection of dry nitrogen, triethylamine is added, and the mixture is controlled in a water bath at a temperature of 25-40°C. Acryloyl chloride is slowly added and stirred to react for 4.5-6.5 hours, and then the temperature is raised to reflux for 1.2-1.8 hours. After the reaction is completed, the acetone is removed by rotary evaporation and vacuum drying is performed to obtain an intermediate.

[0007] Furthermore, the dosage ratio of carboxymethyl cellulose, acryloyl chloride, triethylamine and anhydrous acetone is 50 g: 15-22 mmol: 10-15 mL: 350-400 mL, and the highly active acryloyl chloride is esterified with the carboxymethyl cellulose to introduce an acrylate structure into the molecular side chain.

[0008] Preferably, the degree of substitution of carboxymethyl cellulose is 0.8-1.2, under which the carboxymethyl cellulose has good swelling properties and reactivity.

[0009] Step A2: The intermediate, methacryloylethyl sulfobetaine and ethanol solution were mixed, the temperature was raised to 55-65° C., azobisisobutyronitrile solution was added, and the mixture was stirred and reacted for 2.2-3.5 hours. After the reaction was completed, ethanol and water were removed under reduced pressure to obtain a modified matrix.

[0010] Furthermore, the usage ratio of the intermediate, methacryloylethyl sulfobetaine, azobisisobutyronitrile and ethanol solution is 50 g: 25-30 mmol: 0.1-0.13 g: 280-330 mL. Under the initiation of azobisisobutyronitrile, methacryloylethyl sulfobetaine is added to the grafted acrylate structure in the intermediate molecule, and the side chain is modified by introducing the sulfobetaine structure.

[0011] Step A3: premix tetramethylcyclotetrasiloxane, allyl glycidyl ether, and anhydrous toluene, raise the temperature to 70-80°C under dry nitrogen protection, add a platinum catalyst, and stir to react for 3-4 hours. After the reaction is completed, remove the toluene by vacuum rotary evaporation to obtain a modifier; Furthermore, the usage ratio of tetramethylcyclotetrasiloxane, allyl glycidyl ether, platinum catalyst and anhydrous toluene is 0.1 mol: 0.15-0.18 mol: 0.15-0.2 g: 170-220 mL, and allyl glycidyl ether and tetramethylcyclotetrasiloxane are subjected to hydrosilylation to introduce an epoxy structure.

[0012] Step A4: The modified substrate, modifier and tetrahydrofuran are mixed, and dry nitrogen is introduced for protection. The temperature of the mixture is controlled at 45-60°C in a water bath and stirred for 8-11 hours. Then, 4-dimethylaminopyridine is added and the temperature is raised to reflux for reaction for 0.4-0.6 hours. After the reaction is completed, the tetrahydrofuran is removed by rotary evaporation to obtain a modified CMC thickener.

[0013] Furthermore, the usage ratio of the modified matrix, modifier, 4-dimethylaminopyridine and tetrahydrofuran is 50g:8.5-12g:0.2-0.3g:200-280mL, and the betaine structure introduced into the side chain of the modified matrix molecule self-promotes the ring-opening reaction between the epoxy group of the modifier and the oxygen-containing groups (carboxyl group and residual hydroxyl group) on the cellulose molecule, thereby introducing cyclosiloxane into the side chain of cellulose.

[0014] Preferably, the dispersant is sodium lauryl sulfate, which interacts with the side chain sulfobetaine structure of the modified CMC thickener to improve its dispersibility.

[0015] A preparation method of a thickener for high-temperature acidification comprises the following steps: grinding and dispersing a modified CMC thickener, a cosolvent, a co-dispersant and water, and then adding a stabilizer and mixing to obtain the thickener.

[0016] Beneficial effects of the present invention: The present invention is based on a bio-based raw material carboxymethyl cellulose, which is modified as a main thickening component. Acryloyl chloride is esterified with part of the hydroxyl groups in the carboxymethyl cellulose molecule to introduce an acrylate structure. Methacryloylethyl sulfobetaine is then added to the introduced acrylate to introduce a sulfobetaine side chain to obtain a modified matrix. Allyl glycidyl ether and tetramethylcyclotetrasiloxane are subjected to a silane hydrogenation reaction to graft epoxy groups onto the cyclosiloxane structure molecule to prepare a modifier. Finally, the modifier and the oxygen-containing groups in the modified matrix molecule are ring-opened, and a cyclosiloxane structure is introduced into the cellulose side chain of the modified matrix to obtain a modified CMC thickener. Compared with the prior art, the molecular side chain of the modified CMC thickener of the present invention contains sulfobetaine. The hydrophilic structures such as hydroxyl groups match the aqueous acidizing system and provide a moderate initial viscosity by absorbing water and swelling. With the injection of the acidizing fluid and the increase of the temperature in the well, the cyclosiloxane structure of the side chain hydrolyzes and condenses under acidic conditions, which greatly increases the viscosity of the acidizing fluid in the well and forms a slow diversion underground, which is beneficial for the acid agent to fully dissolve underground cracks and improve the efficiency of oil and gas production. With the progress of acidizing and the continuous high-temperature acidic environment, the main chain of carboxymethyl cellulose decomposes, and then breaks the gel autonomously, which is beneficial to flowback. The modified CMC thickener realizes an adaptive thickening mechanism and adapts to the thickening needs of underground acidizing. In addition, the present invention avoids the use of difficult-to-degrade polymers and uses bio-based carboxymethyl cellulose as the matrix, which has far-reaching research significance in the environmentally friendly production technology of oil and gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 The curves of dynamic viscosity change of the acid solution prepared with the thickener of Example 4 of the present invention and the comparative example as the temperature changes. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0020] Example 1, preparation of a thickener for high temperature acidification, the specific implementation process is as follows: (1) Preparation of modified CMC thickener Step A1: Carboxymethyl cellulose (CMC) and anhydrous acetone were mixed under dry nitrogen protection, heated to 50°C for swelling for 2 hours, cooled, and then controlled in a water bath at 25°C. Triethylamine was added and mixed, and then acryloyl chloride was slowly added and stirred for 6.5 hours. The mixture was then heated and refluxed for 1.8 hours. The degree of substitution of the carboxymethyl cellulose was approximately 0.85, and the dosage ratio of carboxymethyl cellulose, acryloyl chloride, triethylamine, and anhydrous acetone was 50 g:15 mmol:10 mL:350 mL. After the reaction, the acetone was removed by rotary evaporation and the mixture was dried in vacuo to obtain an intermediate.

[0021] Step A2: Take the intermediate, methacryloylethyl sulfobetaine and ethanol solution, mix them, heat to 55°C, add azobisisobutyronitrile solution and stir to react for 3.5h, wherein the volume fraction of the ethanol solution is 65%, the azobisisobutyronitrile solution is a saturated ethanol solution at room temperature, and the amount ratio of the intermediate, methacryloylethyl sulfobetaine, azobisisobutyronitrile and ethanol solution is 50g:25mmol:0.1g:280mL. After the reaction is completed, ethanol and water are removed under reduced pressure to obtain a modified matrix.

[0022] Step A3: Premix tetramethylcyclotetrasiloxane, allyl glycidyl ether and anhydrous toluene, heat to 70°C under dry nitrogen protection, add a platinum catalyst and stir to react for 4 hours, wherein the platinum catalyst uses a Custer catalyst with an active platinum component of 5000 ppm, and the amount ratio of tetramethylcyclotetrasiloxane, allyl glycidyl ether, platinum catalyst and anhydrous toluene is 0.1 mol: 0.15 mol: 0.15 g: 170 mL. After the reaction is completed, remove toluene by vacuum rotary evaporation to obtain a modifier.

[0023] Step A4: Take the modified substrate, modifier and tetrahydrofuran, mix them, introduce dry nitrogen protection, control the temperature in a water bath at 45°C and stir for 11 hours, then add 4-dimethylaminopyridine and heat and reflux to react for 0.6 hours, wherein the amount ratio of the modified substrate, modifier, 4-dimethylaminopyridine and tetrahydrofuran is 50g:8.5g:0.2g:200mL. After the reaction is completed, the tetrahydrofuran is removed by rotary evaporation to obtain a modified CMC thickener.

[0024] (2) Preparation of thickener The raw materials were calculated according to weight percentage: 37 wt % of modified CMC thickener, which was prepared in this embodiment; 5.2 wt % of cosolvent, which was ethylene glycol mono-tert-butyl ether; 1.2 wt % of co-dispersant, which was sodium lauryl sulfate; 3.1 wt % of stabilizer, which was polyethylene glycol 400; and the balance was water.

[0025] The modified CMC thickener, cosolvent, co-dispersant and water are mixed and ground and dispersed, and then a stabilizer is added and mixed to obtain a thickener.

[0026] Example 2, preparation of a thickener for high temperature acidification, the specific implementation process is as follows: (1) Preparation of modified CMC thickener Step A1: Carboxymethyl cellulose and anhydrous acetone were mixed under dry nitrogen protection, heated to 50°C and swelled for 1.5 hours, cooled, and the temperature in a water bath was controlled at 40°C. Triethylamine was added and mixed, and acryloyl chloride was slowly added and stirred for 4.5 hours. The mixture was then heated and refluxed for 1.2 hours. The degree of substitution of carboxymethyl cellulose was approximately 1.2, and the amount ratio of carboxymethyl cellulose, acryloyl chloride, triethylamine, and anhydrous acetone was 50 g:22 mmol:15 mL:400 mL. After the reaction, the acetone was removed by rotary evaporation and the mixture was dried in vacuo to obtain an intermediate.

[0027] Step A2: Take the intermediate, methacryloylethyl sulfobetaine and ethanol solution, mix them, heat to 65°C, add azobisisobutyronitrile solution and stir to react for 2.2h, wherein the volume fraction of the ethanol solution is 65%, the azobisisobutyronitrile solution is a saturated ethanol solution at room temperature, and the amount ratio of the intermediate, methacryloylethyl sulfobetaine, azobisisobutyronitrile and ethanol solution is 50g:30mmol:0.13g:330mL. After the reaction is completed, ethanol and water are removed under reduced pressure to obtain a modified matrix.

[0028] Step A3: Premix tetramethylcyclotetrasiloxane, allyl glycidyl ether and anhydrous toluene, heat to 80°C under dry nitrogen protection, add a platinum catalyst and stir to react for 3 hours, wherein the platinum catalyst uses a Custer catalyst with an active platinum component of 5000 ppm, and the amount ratio of tetramethylcyclotetrasiloxane, allyl glycidyl ether, platinum catalyst and anhydrous toluene is 0.1 mol: 0.18 mol: 0.2 g: 220 mL. After the reaction is completed, remove toluene by vacuum rotary evaporation to obtain a modifier.

[0029] Step A4: Take the modified substrate, modifier and tetrahydrofuran, mix them, introduce dry nitrogen protection, control the temperature in a water bath at 60°C and stir for 8 hours, then add 4-dimethylaminopyridine and heat and reflux to react for 0.4 hours, wherein the amount ratio of the modified substrate, modifier, 4-dimethylaminopyridine and tetrahydrofuran is 50g:12g:0.3g:280mL. After the reaction is completed, the tetrahydrofuran is removed by rotary evaporation to obtain a modified CMC thickener.

[0030] (2) Preparation of thickener The raw materials were calculated according to weight percentage: 45 wt % of a modified CMC thickener, prepared in this embodiment; 7.0 wt % of a cosolvent, ethylene glycol mono-tert-butyl ether; 1.6 wt % of a co-dispersant, sodium lauryl sulfate; 2.4 wt % of a stabilizer, polyethylene glycol 400; and the balance was water.

[0031] The modified CMC thickener, cosolvent, co-dispersant and water are mixed and ground and dispersed, and then a stabilizer is added and mixed to obtain a thickener.

[0032] Example 3, preparation of a thickener for high temperature acidification, the specific implementation process is as follows: (1) Preparation of modified CMC thickener Step A1: Carboxymethyl cellulose and anhydrous acetone were mixed under dry nitrogen protection, heated to 50°C and swelled for 1.5 hours. After cooling, the water bath temperature was controlled at 30°C, triethylamine was added and mixed, and acryloyl chloride was slowly added and stirred for 5.5 hours. The mixture was then heated and refluxed for 1.6 hours. The degree of substitution of carboxymethyl cellulose was approximately 1.1, and the amount ratio of carboxymethyl cellulose, acryloyl chloride, triethylamine and anhydrous acetone was 50 g:20 mmol:12 mL:380 mL. After the reaction was completed, the acetone was removed by rotary evaporation and the mixture was dried in vacuo to obtain an intermediate.

[0033] Step A2: Take the intermediate, methacryloylethyl sulfobetaine and ethanol solution, mix them, heat to 60°C, add azobisisobutyronitrile solution and stir to react for 2.8h, wherein the volume fraction of the ethanol solution is 65%, the azobisisobutyronitrile solution is a saturated ethanol solution at room temperature, and the amount ratio of the intermediate, methacryloylethyl sulfobetaine, azobisisobutyronitrile and ethanol solution is 50g:27mmol:0.11g:300mL. After the reaction is completed, the ethanol and water are removed under reduced pressure to obtain a modified matrix.

[0034] Step A3: Premix tetramethylcyclotetrasiloxane, allyl glycidyl ether, and anhydrous toluene, raise the temperature to 75°C under dry nitrogen protection, add a platinum catalyst, and stir the reaction for 3.5 hours, wherein the platinum catalyst uses a Custer catalyst with an active platinum component of 5000 ppm, and the amount ratio of tetramethylcyclotetrasiloxane, allyl glycidyl ether, platinum catalyst, and anhydrous toluene is 0.1 mol: 0.17 mol: 0.15 g: 200 mL. After the reaction is completed, remove toluene by vacuum rotary evaporation to obtain a modifier.

[0035] Step A4: Take the modified substrate, modifier and tetrahydrofuran, mix them, introduce dry nitrogen protection, control the temperature in a water bath at 55°C and stir for 10 hours, then add 4-dimethylaminopyridine and heat and reflux to react for 0.6 hours, wherein the amount ratio of the modified substrate, modifier, 4-dimethylaminopyridine and tetrahydrofuran is 50g:10g:0.25g:250mL. After the reaction is completed, the tetrahydrofuran is removed by rotary evaporation to obtain a modified CMC thickener.

[0036] (2) Preparation of thickener The raw materials were calculated according to weight percentage: 40 wt % of a modified CMC thickener, prepared in this embodiment; 5.8 wt % of a cosolvent, ethylene glycol mono-tert-butyl ether; 1.3 wt % of a co-dispersant, sodium lauryl sulfate; 2.7 wt % of a stabilizer, polyethylene glycol 400; and the balance was water.

[0037] The modified CMC thickener, cosolvent, co-dispersant and water are mixed and ground and dispersed, and then a stabilizer is added and mixed to obtain a thickener.

[0038] Example 4, preparation of a thickener for high temperature acidification, the specific implementation process is as follows: (1) Preparation of modified CMC thickener Step A1: Carboxymethyl cellulose and anhydrous acetone were mixed under dry nitrogen protection, heated to 50°C for swelling for 2 hours, cooled, and then the water bath temperature was controlled at 35°C. Triethylamine was added and mixed, and then acryloyl chloride was slowly added and stirred for 5.2 hours. The mixture was then heated and refluxed for 1.8 hours. The degree of substitution of the carboxymethyl cellulose was approximately 1.1, and the amount ratio of carboxymethyl cellulose, acryloyl chloride, triethylamine, and anhydrous acetone was 50 g:20 mmol:13 mL:350 mL. After the reaction, the acetone was removed by rotary evaporation and the mixture was dried in vacuo to obtain an intermediate.

[0039] Step A2: The intermediate, methacryloylethyl sulfobetaine and ethanol solution were mixed, the temperature was raised to 65°C, and azobisisobutyronitrile solution was added and stirred for 3.2 hours, wherein the volume fraction of the ethanol solution was 65%, the azobisisobutyronitrile solution was a saturated ethanol solution at room temperature, and the amount ratio of the intermediate, methacryloylethyl sulfobetaine, azobisisobutyronitrile and ethanol solution was 50 g: 25-mmol: 0.12 g: 300 mL. After the reaction was completed, the ethanol and water were removed under reduced pressure to obtain a modified matrix.

[0040] Step A3: Premix tetramethylcyclotetrasiloxane, allyl glycidyl ether, and anhydrous toluene, raise the temperature to 80°C under dry nitrogen protection, add a platinum catalyst, and stir the reaction for 3.3 hours, wherein the platinum catalyst uses a Custer catalyst with an active platinum component of 5000 ppm, and the amount ratio of tetramethylcyclotetrasiloxane, allyl glycidyl ether, platinum catalyst, and anhydrous toluene is 0.1 mol: 0.18 mol: 0.2 g: 190 mL. After the reaction is completed, remove toluene by vacuum rotary evaporation to obtain a modifier.

[0041] Step A4: Take the modified substrate, modifier and tetrahydrofuran, mix them, introduce dry nitrogen protection, control the temperature of the water bath at 50°C and stir for 11 hours, then add 4-dimethylaminopyridine and heat and reflux to react for 0.5 hours, wherein the amount ratio of the modified substrate, modifier, 4-dimethylaminopyridine and tetrahydrofuran is 50g:11g:0.3g:270mL. After the reaction is completed, the tetrahydrofuran is removed by rotary evaporation to obtain a modified CMC thickener.

[0042] (2) Preparation of thickener The raw materials were calculated according to weight percentage: 42 wt % of a modified CMC thickener, prepared in this embodiment; 6.5 wt % of a cosolvent, ethylene glycol mono-tert-butyl ether; 1.3 wt % of a co-dispersant, sodium lauryl sulfate; 2.5 wt % of a stabilizer, polyethylene glycol 400; and the balance was water.

[0043] The modified CMC thickener, cosolvent, co-dispersant and water are mixed and ground and dispersed, and then a stabilizer is added and mixed to obtain a thickener.

[0044] In a comparative example, a commercially available KHF071 polyacrylamide-based high-temperature resistant thickener was selected.

[0045] Acid solution preparation: 15% hydrochloric acid is used as an acid agent, 0.12wt% of YTY-04 quinoline quaternary ammonium salt is added thereto as a corrosion inhibitor, 0.08wt% of ascorbic acid is used as an iron ion stabilizer, and 1.5wt% of the above thickener is mixed uniformly to obtain an acid solution.

[0046] Dynamic viscosity test: The acid solution prepared with the thickener of Example 4 and the comparative example was used as the test object. The acid solution was tested at 170s-1 Shearing was performed, the temperature was raised from 30°C to 180°C and kept warm, the viscosity of the acid solution was tested, and a dynamic viscosity change curve was drawn. Figure 1 As shown; In the dynamic viscosity test of simulated acid injection, Figure 1 It can be seen that the initial viscosity of the thickened acid solution prepared in Example 4 is slightly lower than that of the comparative example. As the temperature increases, the viscosity of Example 4 first decreases and then increases, with a peak viscosity of approximately 125 mPa·s. The viscosity of the comparative example shows a visible staged decrease as the temperature increases.

[0047] Core dissolution test: artificial marble cores (porosity 18%) with a size of Φ25×50mm were taken and injected with the acid solution prepared above. The temperature was controlled at 150°C and the compressed air pressure was increased to 2.0MPa. The dissolution cycles were 120 minutes and 240 hours respectively. The dissolution rate and dissolution depth of the cores were tested. The specific test results are shown in Table 1:

[0048] From the test results in Table 1, it can be seen that the acid solution prepared with the thickener prepared in the example has good dissolution performance on the core, especially in the long-term dissolution process, the dissolution efficiency and depth are significantly better than those of the comparative example.

[0049] Throughout the specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these 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 any one or more embodiments or examples.

[0050] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A thickener for high temperature acidification, characterized in that: The components by weight percentage are: modified CMC thickener 37-45wt%, cosolvent 5.2-7.0wt%, co-dispersant 1.2-1.6wt% and stabilizer 2.4-3.1wt%, and the balance is water; The modified CMC thickener is prepared by the following method: Step A1: Carboxymethyl cellulose and anhydrous acetone are mixed and swelled under dry nitrogen protection, triethylamine is added, and the mixture is kept in a water bath at 25-40°C. Acryloyl chloride is slowly added and stirred for 4.5-6.5 hours, followed by reflux for 1.2-1.8 hours to obtain an intermediate; Step A2: Mix the intermediate, methacryloylethyl sulfobetaine and ethanol solution, raise the temperature to 55-65°C, add azobisisobutyronitrile solution, and stir to react for 2.2-3.5 hours to obtain a modified matrix; Step A3: premix tetramethylcyclotetrasiloxane, allyl glycidyl ether, and anhydrous toluene, raise the temperature to 70-80° C. under dry nitrogen protection, add a platinum catalyst, and stir the mixture for 3-4 hours to obtain a modifier; Step A4: Mix the modified substrate, modifier and tetrahydrofuran, introduce dry nitrogen for protection, control the temperature in a water bath at 45-60°C and stir for 8-11 hours, then add 4-dimethylaminopyridine and heat under reflux for 0.4-0.6 hours to obtain a modified CMC thickener.

2. A thickener for high temperature acidification according to claim 1, characterized in that: The usage ratio of carboxymethyl cellulose, acryloyl chloride, triethylamine and anhydrous acetone is 50 g:15-22 mmol:10-15 mL:350-400 mL.

3. A thickener for high temperature acidification according to claim 2, characterized in that: The degree of substitution of carboxymethyl cellulose is 0.8-1.

2.

4. A thickener for high temperature acidification according to claim 2, characterized in that: The usage ratio of the intermediate, methacryloylethyl sulfobetaine, azobisisobutyronitrile and ethanol solution is 50 g: 25-30 mmol: 0.1-0.13 g: 280-330 mL.

5. A thickener for high temperature acidification according to claim 4, characterized in that: The usage ratio of tetramethylcyclotetrasiloxane, allyl glycidyl ether, platinum catalyst and anhydrous toluene is 0.1 mol: 0.15-0.18 mol: 0.15-0.2 g: 170-220 mL.

6. A thickener for high temperature acidification according to claim 5, characterized in that: The usage ratio of the modified matrix, the modifier, 4-dimethylaminopyridine and tetrahydrofuran is 50g:8.5-12g:0.2-0.3g:200-280mL.

7. The thickener for high temperature acidification according to claim 1, characterized in that: The dispersant is sodium lauryl sulfate.

8. The method for preparing a thickener for high temperature acidification according to any one of claims 1 to 7, characterized in that: Specifically, the modified CMC thickener, cosolvent, co-dispersant and water are ground and dispersed, and then a stabilizer is added and mixed to obtain a thickener.

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