Polysaccharide thickening agent for fracturing and preparation method thereof

Abstract

The invention relates to the technical field of oil field fracturing fluids, and discloses a polysaccharide thickening agent for fracturing and a preparation method thereof.Acrylamide, water, triazinyl modified alkenyl adamantane, modified guanidine gum, sodium sulfite and sodium persulfate are added into a stirrer to be stirred, and the polysaccharide thickening agent for fracturing is obtained. Chains in the triazinyl modified alkenyl adamantane can be subjected to cross-linking reaction, so that a three-dimensional network structure can be formed, and a thickening effect is realized; the viscosity-temperature characteristic of the thickening agent is improved by the ester group, so that the thickening agent can still keep relatively good stability under a high-temperature condition; the multi-chain structure of the guanidine gum fully extends to form a complex net structure, so that the viscosity of the thickening agent is increased; the amido group can enhance the rigidity of a polymer chain and improve the stability and temperature resistance of the polymer chain at high temperature, and the carboxyl group can interact with water molecules or other ions by forming hydrogen bonds or ionic bonds under the conditions of high temperature and high salinity, so that the stability of the thickening agent is enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield fracturing fluid, in particular to a polysaccharide thickener for fracturing and a preparation method thereof. Background Art

[0002] In the process of oil extraction, thickeners play an indispensable role in the fracturing process. By using thickeners to increase the viscosity and consistency of the fracturing fluid, the flow rate and pressure of the fracturing fluid in the pipeline and formation can be effectively controlled, thereby avoiding the occurrence of well wall collapse and achieving the effect of improving fracturing effects, protecting reservoirs, and increasing production.

[0003] As the temperature of the construction stratum increases and the mineralization increases, the fracturing thickener needs to maintain the stability of the structure in a high temperature and high salt environment, maintain the viscosity-increasing effect of the thickener, and be able to transmit the pressure to the deep stratum in order to form suitable cracks, which is conducive to the release of oil and gas. Therefore, how to maintain the stability of the thickener in a harsh environment is of great significance. For example, patent CN110028945B discloses a thickener for fracturing fluid, a preparation method thereof, and a fracturing fluid, which has the characteristics of being easy to store in a low temperature environment, but the thermal stability and salt resistance need to be improved. Summary of the invention

[0004] 1. Technical issues to be resolved In view of the deficiencies in the prior art, the present invention provides a polysaccharide thickener for fracturing and a preparation method thereof, which has good thermal stability and salt resistance.

[0005] (II) Technical solution To achieve the above-mentioned purpose, the present invention provides the following technical scheme: a polysaccharide thickener for fracturing and a preparation method thereof, comprising the following components by weight: 70-100 parts by weight of acrylamide, 80-140 parts by weight of water, 7-11 parts by weight of triazine-modified olefinic adamantane, 12-14 parts by weight of modified guar gum, 0.01-0.02 parts by weight of sodium sulfite, and 0.01-0.013 parts by weight of sodium persulfate initiator.

[0006] The preferred method for preparing the triazine-modified alkenyl adamantane is: Step 1: Add allyl hydroxyethyl ether, isophthaloyl chloride and 1,3-dihydroxyadamantane to N,N-dimethylformamide solvent, stir evenly, continue to add triethylamine catalyst, react at 70-95°C for 7-12h, and after completion, wash and dry to obtain intermediate 1; Step 2: Add sodium bicarbonate and intermediate 1 to deionized water, stir and disperse at 2-6°C, then add cyanuric chloride, heat to 20-40°C, and keep warm for 12-18h. After the reaction is completed, filter, wash with deionized water, and dry to obtain triazine-modified alkene-based adamantane.

[0007] Preferably, in the step 1, the mass ratio of allyl hydroxyethyl ether, isophthaloyl chloride, 1,3-dihydroxyadamantane and triethylamine catalyst is 0.72-0.94:1.21-1.66:1:0.01-0.02.

[0008] Preferably, in the step 2, the mass ratio of sodium bicarbonate, intermediate 1, and cyanuric chloride is 0.22-0.46:1.88-3.42:1.

[0009] Preferably, the preparation method of the modified guar gum is: S1. Add epichlorohydrin and anhydrous ethanol solvent to the reactor, stir evenly with magnetic force, add octadecenoic acid amide propyl dimethyl propylamine and hydroxypropyl guar gum, continue to stir evenly, heat to 60-80 ° C, react for 2-6 hours, stop stirring, wash with ethanol, filter, and dry to obtain quaternized hydroxypropyl guar gum; S2. Add quaternized hydroxypropyl guar gum and itaconic anhydride to N,N-dimethylformamide solvent, wherein the mass ratio of hydroxypropyl guar gum to itaconic anhydride is 0.66-0.84:1, stir and disperse, introduce nitrogen protection, react at 75-90°C, distill under reduced pressure after the reaction, wash, and obtain modified guar gum.

[0010] Preferably, the mass ratio of epichlorohydrin, octadecenoic acid amide propyl dimethyl propylamine and hydroxypropyl guar gum in S1 is 0.71-0.94:0.84-1.19:1.

[0011] Preferably, the reaction time in S2 is 10-15h.

[0012] Preferably, the preparation method of the polysaccharide thickener for fracturing is: add acrylamide, triazine-modified olefinic adamantane, and modified guar gum into water, stir to dissolve, introduce nitrogen, continue to add sodium sulfite and sodium persulfate initiators, react at 50-70°C for 14-22h, filter and wash after the reaction to obtain a polysaccharide polymer.

[0013] 3. Beneficial technical effects The invention prepares a polysaccharide thickener for fracturing by adding acrylamide, water, triazine-modified olefinic adamantane, modified guar gum, sodium sulfite and sodium persulfate into a stirrer for stirring.

[0014] The hydroxyl groups in allyl hydroxyethyl ether and 1,3-dihydroxyadamantane react with the acyl chloride in isophthaloyl chloride to introduce ester groups and hydroxyl groups to obtain intermediate 1; intermediate 1 undergoes a substitution reaction with cyanuric chloride to introduce triazine groups and carbon-carbon double bonds to obtain triazine-modified olefinic adamantane; the chlorine atom in epichlorohydrin reacts with the tertiary amine of octadecenoic acid amide propyl dimethylpropylamine to introduce quaternary ammonium salt and amide groups, and the product is graft-copolymerized with hydroxypropyl guar gum to introduce hydroxyl groups to obtain quaternized hydroxypropyl guar gum; the hydroxyl groups in the quaternized hydroxypropyl guar gum react with the anhydride in itaconic anhydride to introduce ester groups and carboxyl groups to obtain modified guar gum; acrylamide, triazine-modified olefinic adamantane and modified guar gum react in water, and sodium sulfite and sodium persulfate initiators are added to obtain a polysaccharide polymer.

[0015] The chains in triazine-modified alkene-based adamantane can undergo cross-linking reactions to form a three-dimensional network structure and achieve a thickening effect; the triazine group has good thermal stability, which helps to maintain the thickening effect of the thickener under high temperature conditions; the ester group improves the viscosity-temperature characteristics of the thickener, allowing it to maintain good stability under high temperature conditions; the hydrophobicity of the quaternary ammonium salt in the modified guar gum can promote hydrophobic association between molecules, making the polymer network structure more solid, thereby improving the stability of the thickener; the multi-chain structure of guar gum is fully extended to form a complex network structure, thereby increasing The viscosity of the thickener; the amide group can enhance the rigidity of the polymer chain, improve its stability and temperature resistance at high temperatures, and the polarity of the amide group can also form a stable hydration layer with salt ions, allowing the thickener to maintain a high viscosity in a high minerality environment; the carboxyl group can interact with water molecules or other ions by forming hydrogen bonds or ionic bonds under high temperature and high salinity conditions, thereby enhancing the stability of the thickener; the carboxyl group is an anionic functional group, which can form an electrostatic shielding effect with cations under extreme conditions, reducing the compression of the polymer molecular chain, thereby improving the temperature and salt resistance of the thickener. DETAILED DESCRIPTION Example 1

[0016] (1) Add allyl hydroxyethyl ether, isophthaloyl chloride, and 1,3-dihydroxyadamantane to N,N-dimethylformamide solvent, stir evenly, and continue to add triethylamine catalyst, wherein the mass ratio of allyl hydroxyethyl ether, isophthaloyl chloride, 1,3-dihydroxyadamantane, and triethylamine catalyst is 0.72:1.21:1:0.01, react at 70°C for 7 hours, and after completion, wash and dry to obtain intermediate 1; (2) Sodium bicarbonate and intermediate 1 are added to deionized water, stirred and dispersed at 2-6°C, and then cyanuric chloride is added thereto, wherein the mass ratio of sodium bicarbonate, intermediate 1, and cyanuric chloride is 0.22:1.88:1, and the temperature is raised to 20°C, and the temperature is kept to react for 12 hours. After the reaction is completed, the mixture is filtered, washed with deionized water, and dried to obtain triazine-modified alkene-based adamantane; (3) Add epichlorohydrin and anhydrous ethanol solvent to the reactor, stir evenly with magnetic force, then add octadecenoic acid amide propyl dimethyl propylamine and hydroxypropyl guar gum, wherein the mass ratio of epichlorohydrin, octadecenoic acid amide propyl dimethyl propylamine and hydroxypropyl guar gum is 0.71:0.84:1, continue to stir evenly, and heat to 60°C. After reacting for 2 hours, stop stirring, wash with ethanol, filter, and dry to obtain quaternized hydroxypropyl guar gum; (4) adding quaternized hydroxypropyl guar gum and itaconic anhydride to N,N-dimethylformamide solvent, wherein the mass ratio of hydroxypropyl guar gum to itaconic anhydride is 0.66:1, stirring and dispersing, introducing nitrogen protection, reacting at 75° C. for 10 h, distilling under reduced pressure after the reaction, washing, and obtaining modified guar gum; (5) Add 70 parts by weight of acrylamide, 7 parts by weight of triazine-modified ethylene-based adamantane, and 12 parts by weight of modified guar gum to 80 parts by weight of water, stir to dissolve, introduce nitrogen, and continue to add 0.01 parts by weight of sodium sulfite and 0.01 parts by weight of sodium persulfate initiator, react at 50°C for 14 hours, filter and wash after the reaction to obtain a polysaccharide polymer. Example 2

[0017] (1) Add allyl hydroxyethyl ether, isophthaloyl chloride, and 1,3-dihydroxyadamantane to N,N-dimethylformamide solvent, stir evenly, and continue to add triethylamine catalyst, wherein the mass ratio of allyl hydroxyethyl ether, isophthaloyl chloride, 1,3-dihydroxyadamantane, and triethylamine catalyst is 0.82:1.33:1:0.01, react at 75°C for 8 hours, and after completion, wash and dry to obtain intermediate 1; (2) Sodium bicarbonate and intermediate 1 are added to deionized water, stirred and dispersed at 2-6°C, and then cyanuric chloride is added thereto, wherein the mass ratio of sodium bicarbonate, intermediate 1, and cyanuric chloride is 0.3:2.25:1, and the temperature is raised to 25°C, and the temperature is kept to react for 13 hours. After the reaction is completed, the mixture is filtered, washed with deionized water, and dried to obtain triazine-modified alkene-based adamantane; (3) Add epichlorohydrin and anhydrous ethanol solvent to the reactor, stir evenly with magnetic force, then add octadecenoic acid amide propyl dimethyl propylamine and hydroxypropyl guar gum, wherein the mass ratio of epichlorohydrin, octadecenoic acid amide propyl dimethyl propylamine and hydroxypropyl guar gum is 0.77:0.95:1, continue to stir evenly, and heat to 65°C. After reacting for 3 hours, stop stirring, wash with ethanol, filter, and dry to obtain quaternized hydroxypropyl guar gum; (4) adding quaternized hydroxypropyl guar gum and itaconic anhydride to N,N-dimethylformamide solvent, wherein the mass ratio of hydroxypropyl guar gum to itaconic anhydride is 0.73:1, stirring and dispersing, introducing nitrogen protection, reacting at 80° C. for 12 h, distilling under reduced pressure after the reaction, washing, and obtaining modified guar gum; (5) Add 80 parts by weight of acrylamide, 8 parts by weight of triazine-modified ethylene-based adamantane, and 12 parts by weight of modified guar gum to 95 parts by weight of water, stir to dissolve, introduce nitrogen, and continue to add 0.012 parts by weight of sodium sulfite and 0.011 parts by weight of sodium persulfate initiator, react at 54°C for 15 hours, filter and wash after the reaction to obtain a polysaccharide polymer. Example 3

[0018] (1) Add allyl hydroxyethyl ether, isophthaloyl chloride, and 1,3-dihydroxyadamantane to N,N-dimethylformamide solvent, stir evenly, and continue to add triethylamine catalyst, wherein the mass ratio of allyl hydroxyethyl ether, isophthaloyl chloride, 1,3-dihydroxyadamantane, and triethylamine catalyst is 0.82:1.44:1:0.01, react at 82°C for 10 hours, and after completion, wash and dry to obtain intermediate 1; (2) Sodium bicarbonate and intermediate 1 are added to deionized water, stirred and dispersed at 4°C, and then cyanuric chloride is added thereto, wherein the mass ratio of sodium bicarbonate, intermediate 1, and cyanuric chloride is 0.33:2.51:1, and the temperature is raised to 30°C, and the temperature is kept for 15 hours. After the reaction is completed, the mixture is filtered, washed with deionized water, and dried to obtain triazine-modified alkene-based adamantane; (3) Add epichlorohydrin and anhydrous ethanol solvent to the reactor, stir evenly with magnetic force, then add octadecenoic acid amide propyl dimethyl propylamine and hydroxypropyl guar gum, wherein the mass ratio of epichlorohydrin, octadecenoic acid amide propyl dimethyl propylamine and hydroxypropyl guar gum is 0.82:1.04:1, continue to stir evenly, and heat to 70°C. After reacting for 4 hours, stop stirring, wash with ethanol, filter, and dry to obtain quaternized hydroxypropyl guar gum; (4) adding quaternized hydroxypropyl guar gum and itaconic anhydride to N,N-dimethylformamide solvent, wherein the mass ratio of hydroxypropyl guar gum to itaconic anhydride is 0.74:1, stirring and dispersing, introducing nitrogen protection, reacting at 82° C. for 13 h, and distilling under reduced pressure after the reaction, washing, to obtain modified guar gum; (5) Add 85 parts by weight of acrylamide, 9 parts by weight of triazine-modified ethylene-based adamantane, and 13 parts by weight of modified guar gum to 110 parts by weight of water, stir to dissolve, introduce nitrogen, and continue to add 0.015 parts by weight of sodium sulfite and 0.012 parts by weight of sodium persulfate initiator, react at 60°C for 18 hours, filter and wash after the reaction to obtain a polysaccharide polymer. Example 4

[0019] (1) Add allyl hydroxyethyl ether, isophthaloyl chloride, and 1,3-dihydroxyadamantane to N,N-dimethylformamide solvent, stir evenly, and continue to add triethylamine catalyst, wherein the mass ratio of allyl hydroxyethyl ether, isophthaloyl chloride, 1,3-dihydroxyadamantane, and triethylamine catalyst is 0.90:1.45:1:0.02, react at 90°C for 11 hours, and after completion, wash and dry to obtain intermediate 1; (2) Sodium bicarbonate and intermediate 1 are added to deionized water, stirred and dispersed at 5°C, and then cyanuric chloride is added thereto, wherein the mass ratio of sodium bicarbonate, intermediate 1, and cyanuric chloride is 0.40:3.18:1, and the temperature is raised to 35°C, and the temperature is kept to react for 16 hours. After the reaction is completed, the mixture is filtered, washed with deionized water, and dried to obtain triazine-modified alkene-based adamantane; (3) Add epichlorohydrin and anhydrous ethanol solvent to the reactor, stir evenly with magnetic force, then add octadecenoic acid amide propyl dimethyl propylamine and hydroxypropyl guar gum, wherein the mass ratio of epichlorohydrin, octadecenoic acid amide propyl dimethyl propylamine and hydroxypropyl guar gum is 0.86:1.04:1, continue to stir evenly, and heat to 76°C. After reacting for 5 hours, stop stirring, wash with ethanol, filter, and dry to obtain quaternized hydroxypropyl guar gum; (4) adding quaternized hydroxypropyl guar gum and itaconic anhydride to N,N-dimethylformamide solvent, wherein the mass ratio of hydroxypropyl guar gum to itaconic anhydride is 0.72:1, stirring and dispersing, introducing nitrogen protection, reacting at 86° C. for 14 h, distilling under reduced pressure after the reaction, washing, and obtaining modified guar gum; (5) Add 90 parts by weight of acrylamide, 10 parts by weight of triazine-modified ethylene-based adamantane, and 14 parts by weight of modified guar gum to 120 parts by weight of water, stir to dissolve, introduce nitrogen, and continue to add 0.018 parts by weight of sodium sulfite and 0.013 parts by weight of sodium persulfate initiator, react at 66°C for 19 hours, filter and wash after the reaction to obtain a polysaccharide polymer. Example 5

[0020] (1) Add allyl hydroxyethyl ether, isophthaloyl chloride, and 1,3-dihydroxyadamantane to N,N-dimethylformamide solvent, stir evenly, and continue to add triethylamine catalyst, wherein the mass ratio of allyl hydroxyethyl ether, isophthaloyl chloride, 1,3-dihydroxyadamantane, and triethylamine catalyst is 0.94:1.66:1:0.02, react at 95°C for 12 hours, and after completion, wash and dry to obtain intermediate 1; (2) Sodium bicarbonate and intermediate 1 are added to deionized water, stirred and dispersed at 6°C, and then cyanuric chloride is added thereto, wherein the mass ratio of sodium bicarbonate, intermediate 1, and cyanuric chloride is 0.46:3.42:1, and the temperature is raised to 40°C, and the temperature is kept to react for 18 hours. After the reaction is completed, the mixture is filtered, washed with deionized water, and dried to obtain triazine-modified alkene-based adamantane; (3) Add epichlorohydrin and anhydrous ethanol solvent to the reactor, stir evenly with magnetic force, then add octadecenoic acid amide propyl dimethyl propylamine and hydroxypropyl guar gum, wherein the mass ratio of epichlorohydrin, octadecenoic acid amide propyl dimethyl propylamine and hydroxypropyl guar gum is 0.94:1.19:1, continue to stir evenly, and heat to 80°C. After reacting for 6 hours, stop stirring, wash with ethanol, filter, and dry to obtain quaternized hydroxypropyl guar gum; (4) adding quaternized hydroxypropyl guar gum and itaconic anhydride to N,N-dimethylformamide solvent, wherein the mass ratio of hydroxypropyl guar gum to itaconic anhydride is 0.84:1, stirring and dispersing, introducing nitrogen protection, reacting at 90° C. for 15 h, distilling under reduced pressure after the reaction, washing, and obtaining modified guar gum; (5) Add 100 parts by weight of acrylamide, 11 parts by weight of triazine-modified ethylene-based adamantane, and 14 parts by weight of modified guar gum to 140 parts by weight of water, stir to dissolve, introduce nitrogen, and continue to add 0.02 parts by weight of sodium sulfite and 0.013 parts by weight of sodium persulfate initiator, react at 70°C for 22 hours, filter and wash after the reaction to obtain a polysaccharide polymer.

[0021] Comparative Example 1 70 parts by weight of acrylamide and 7 parts by weight of triazine-modified olefinic adamantane are added to 80 parts by weight of water, stirred to dissolve, nitrogen is introduced, 0.01 parts by weight of sodium sulfite and 0.01 parts by weight of sodium persulfate initiator are added thereto, the mixture is reacted at 50° C. for 14 hours, filtered and washed after the reaction to obtain a polysaccharide polymer.

[0022] Comparative Example 2 70 parts by weight of acrylamide and 12 parts by weight of modified guar gum are added to 80 parts by weight of water, stirred to dissolve, nitrogen is introduced, 0.01 parts by weight of sodium sulfite and 0.01 parts by weight of sodium persulfate initiator are added thereto, the mixture is reacted at 50°C for 14 hours, filtered and washed after the reaction to obtain a polysaccharide polymer.

[0023] 1 wt% of the thickeners prepared in Examples 1-5 and Comparative Examples 1-2 were tested for apparent viscosity without salt, and dissolved in 50, 100, and 200 g / L NaCl and CaCl2 solutions, respectively, and measured at a shear rate of 170 s using an electronic six-speed viscometer. -1 The apparent viscosity under the conditions is shown in Table 1.

[0024] Table 1: Salt resistance test

[0025] As can be seen from Table 1, the apparent viscosity of Examples 1-5 of the present invention is higher than that of Comparative Examples 1-2 under the same environment, and the viscosity can be maintained at a good level even in a high-salt environment, and the Examples 1-5 have good salt resistance.

[0026] 1 wt% of the thickeners prepared in Examples 1-5 and Comparative Examples 1-2 were measured at room temperature, 90°C, 140°C and 160°C at a shear rate of 170 s -1 The apparent viscosity under the conditions is shown in Table 2.

[0027] Table 2: Temperature resistance test Group Room temperature 90℃ 140℃ 160℃ Example 1 204 196 190 177 Example 2 212 197 194 181 Example 3 220 201 193 185 Example 4 215 194 187 174 Example 5 210 197 188 171 Comparative Example 1 200 184 166 154 Comparative Example 2 197 186 161 151 As can be seen from Table 2, compared with Comparative Examples 1-2, Examples 1-5 of the present invention can maintain better apparent viscosity under different temperature environments and have better temperature resistance.

[0028] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A polysaccharide thickener for fracturing, characterized in that: The invention comprises the following components by weight: 70-100 parts by weight of acrylamide, 80-140 parts by weight of water, 7-11 parts by weight of triazine-modified olefinic adamantane, 12-14 parts by weight of modified guar gum, 0.01-0.02 parts by weight of sodium sulfite and 0.01-0.013 parts by weight of sodium persulfate initiator.

2. The polysaccharide thickener for fracturing according to claim 1, characterized in that: The preparation method of the triazine-modified alkenyl-adamantane is as follows: Step 1: Add allyl hydroxyethyl ether, isophthaloyl chloride and 1,3-dihydroxyadamantane to N,N-dimethylformamide solvent, stir evenly, continue to add triethylamine catalyst, react at 70-95°C for 7-12h, and after completion, wash and dry to obtain intermediate 1; Step 2: Add sodium bicarbonate and intermediate 1 to deionized water, stir and disperse at 2-6°C, then add cyanuric chloride, heat to 20-40°C, and keep warm for 12-18h. After the reaction is completed, filter, wash with deionized water, and dry to obtain triazine-modified alkene-based adamantane.

3. The polysaccharide thickener for fracturing according to claim 2, characterized in that: In the step 1, the mass ratio of allyl hydroxyethyl ether, isophthaloyl chloride, 1,3-dihydroxyadamantane and triethylamine catalyst is 0.72-0.94:1.21-1.66:1:0.01-0.

02.

4. The polysaccharide thickener for fracturing according to claim 2, characterized in that: In the step 2, the mass ratio of sodium bicarbonate, intermediate 1 and cyanuric chloride is 0.22-0.46:1.88-3.42:

1.

5. The polysaccharide thickener for fracturing according to claim 1, characterized in that: The preparation method of the modified guar gum is: S1. Add epichlorohydrin and anhydrous ethanol solvent to the reactor, stir evenly with magnetic force, add octadecenoic acid amide propyl dimethyl propylamine and hydroxypropyl guar gum, continue to stir evenly, heat to 60-80 ° C, react for 2-6 hours, stop stirring, wash with ethanol, filter, and dry to obtain quaternized hydroxypropyl guar gum; S2. Add quaternized hydroxypropyl guar gum and itaconic anhydride to N,N-dimethylformamide solvent, wherein the mass ratio of hydroxypropyl guar gum to itaconic anhydride is 0.66-0.84:1, stir and disperse, introduce nitrogen protection, react at 75-90°C, distill under reduced pressure after the reaction, wash, and obtain modified guar gum.

6. The polysaccharide thickener for fracturing according to claim 5, characterized in that: The mass ratio of epichlorohydrin, octadecenoic acid amide propyl dimethyl propylamine and hydroxypropyl guar gum in S1 is 0.71-0.94:0.84-1.19:

1.

7. The polysaccharide thickener for fracturing according to claim 5, characterized in that: The reaction time in S2 is 10-15h.

8. A method for preparing a polysaccharide thickener for fracturing according to any one of claims 1 to 7, characterized in that: The preparation method of the polysaccharide thickener for fracturing is as follows: acrylamide, triazine-modified olefinic adamantane and modified guar gum are added into water, stirred to dissolve, nitrogen is introduced, sodium sulfite and sodium persulfate initiators are continuously added thereto, reacted at 50-70°C for 14-22h, filtered and washed after the reaction to obtain a polysaccharide polymer.

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