CN115651629B - A kind of guar gum viscosifier for fracturing and its preparation method and application - Google Patents

Abstract

The invention provides a guar gum viscosifier for fracturing, a preparation method and application thereof, and belongs to the technical field of fracturing fluid. The metal salt dopamine hydrochloride is reacted with a catalyst to form a temperature-controlled slow-release cross-linking agent, which is mixed with cationic vegetable gum prepared from a mixture of squash gum and hydroxypropyl guar gum treated with lye, and added to the Introduce 1-vinyl-3-ethylimidazolium bromide salt, ethyl acrylate, acrylamide, and octadecyl methacrylate into the emulsion tackifier obtained on the obtained molecule, and mix uniformly to obtain the melon for fracturing. Seoul gum thickener. The guar gum viscosifier for fracturing in the present invention has good performances of temperature resistance, salt resistance and shear resistance, fast stickiness, and slow release of the crosslinking agent through temperature control, so that the fracturing fluid has suitable viscoelasticity , greatly reduce the cost of construction operations, anti-oxidative degradation, long-term viscosity unchanged, can be used for a long time, high storage stability, cost reduction, and has broad application prospects.

Description

A kind of guar gum viscosifier for fracturing and its preparation method and application

technical field

The invention relates to the technical field of fracturing fluids, in particular to a guar gum viscosifier for fracturing, a preparation method and application thereof.

Background technique

Viscosifier is a polymer additive used to increase the viscosity of water-based systems and improve rheology. Adding a little tackifier to the system that needs to be thickened can significantly increase the apparent viscosity of the system to meet the requirements. It is widely used in oil drilling, food industry, agriculture, daily chemical industry, pharmaceutical industry, textile printing and dyeing and other fields. Currently, the most widely used synthetic tackifiers are alkali-soluble polyacrylic tackifiers. The molecular chain of this kind of tackifier contains a certain amount of carboxyl groups. When neutralized with alkali, it can quickly change from a low-viscosity dispersion system to a water-soluble transparent viscous body, and the viscosity of the entire system suddenly increases. They are characterized by high relative molecular weight, low flow viscosity, good miscibility with various emulsions and water-soluble systems, no biodegradation, and obvious thickening effect. Among them, the polyethyl acrylate series has developed rapidly in recent years due to the advantages of convenient application, strong thickening ability, good leveling, and low cost, and has become the most important synthetic tackifier.

The research on tackifiers at home and abroad has a history of more than 40 years. It has experienced the development from natural polymers to synthetic polymers. At present, three types of tackifier systems have been formed: natural polymers, biopolymers species and synthetic polymers.

Natural polymers mainly include vegetable gum and its derivatives, cellulose and its derivatives. Vegetable gums include guar gum, kale gum, cougar gum, konjac gum and various plant gum derivatives. They are mainly composed of galactomannan. Molecules form associations, stretch and elongate in the solution to produce thickening effect. The modified vegetable gum can improve the solubility and temperature resistance and shear resistance of molecules, and reduce the residue content. Hydroxypropyl guar gum (HPG) is A modified vegetable gum that is widely used.

Cellulose is a non-ionic polysaccharide. Under the action of intermolecular hydrogen bonds, cellulose can only swell but not dissolve in water. By introducing modifying groups into its molecules, the solubility can be improved. Commonly used modified cellulose thickeners include carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC) and carboxymethyl hydroxyethyl cellulose (CMHEC). The modified cellulose polymer has good water solubility, good thermal stability, salt resistance and shear resistance, but the construction friction is high, which is not conducive to large-scale on-site construction.

Biopolymer thickener mainly refers to xanthan gum, also known as xanthan gum and xanthan gum, which is a microbial polysaccharide produced by the fermentation of Xanthomonas bacterium. It has good thickening ability and temperature resistance and shear resistance. It is non-toxic, but it is easily degraded by bacteria and enzymes, so it needs to be used with fungicides.

Compared with natural polymers, synthetic polymers have better heat resistance and shear resistance, strong thickening ability, strong sand suspension ability, good gel breaking performance, less damage to the formation, and insensitive to bacteria , are superior to natural polymers in all aspects. At present, there are many studies on synthetic polymers at home and abroad, and the main products are: acrylamide polymers, vinyl polymers and cross-linked polymers.

At present, the demand for oil is large, and the development of a low-cost fracturing fluid system suitable for tight oil reservoirs is of great significance for oil production.

Chinese patent CN104861951B discloses a viscosifier, which is easy to prepare and has a certain salt resistance. When it is mixed with water to prepare fracturing fluid, it swells rapidly and has low requirements for the preparation of water, even if seawater (salt) is used. , does not affect the swelling effect of the thickener. However, it has been found through research that the suspension stability of the above-mentioned viscosifiers is still difficult to meet the requirements of high-performance standards in the market.

Contents of the invention

The purpose of the present invention is to propose a guar gum tackifier for fracturing and its preparation method and application, which has good temperature resistance, salt resistance, shear resistance, fast sticking, and slow release through temperature control The cross-linking agent makes the fracturing fluid have a suitable viscoelasticity, and neither needs to be prepared in advance nor a continuous mixing vehicle, which greatly reduces the construction operation cost, resists oxidation and degradation, keeps the viscosity unchanged for a long time, can be used for a long time, and is stable in storage High reliability, low cost, and broad application prospects.

Technical scheme of the present invention is realized like this:

The invention provides a preparation method of a guar gum viscosifier for fracturing, in which a metal salt is reacted with dopamine hydrochloride and a catalyst to form a temperature-controlled slow-release cross-linking agent, which is mixed with kale gum treated with lye and Mix the cationic vegetable gum prepared from the mixture of hydroxypropyl guar gum, add 1-vinyl-3-ethylimidazolium bromide, ethyl acrylate, acrylamide, and methacrylic acid to the molecules prepared by emulsion polymerization Mix evenly with the emulsion tackifier obtained from the octaalkyl ester to prepare a guar gum tackifier for fracturing.

As a further improvement of the present invention, comprising the following steps:

S1. Preparation of temperature-controlled slow-release cross-linking agent: under the protection of inert gas, after dissolving metal salt in water, add dopamine hydrochloride and catalyst, heat and stir for reaction, cool to room temperature, add mixed solvent, filter, wash, Drying and crushing to obtain a temperature-controlled slow-release cross-linking agent;

Preferably, the inert gas is selected from at least one of nitrogen, argon, and helium.

S2. Combination of vegetable gum: mixing squash gum and hydroxypropyl guar gum to obtain vegetable gum;

S3. Preparation of cationic vegetable gum: disperse the vegetable gum prepared in step S2 in water, add lye and cationic etherification agent, heat the reaction, adjust the pH value of the solution, filter, wash, dry, and pulverize to obtain cationic vegetable gum;

S4. Preparation of emulsion tackifier: 1-vinyl-3-ethylimidazolium bromide, ethyl acrylate, acrylamide, octadecyl methacrylate, first initiator and chain transfer agent are dissolved in water , to obtain the water phase; mixing the white oil, the lipophilic emulsifier and the second initiator uniformly to obtain the oil phase; under the protection of an inert gas, adding the water phase to the oil phase dropwise, stirring and reacting to obtain the emulsion tackifier;

Preferably, the inert gas is selected from at least one of nitrogen, argon, and helium.

S5. Preparation of guar gum tackifier for fracturing: mix the temperature-controlled slow-release cross-linking agent prepared in step S1, the cationic vegetable gum prepared in step S3, and the emulsion tackifier prepared in step S4, and stir uniformly, to obtain a guar gum viscosifier for fracturing.

As a further improvement of the present invention, the metal salt described in step S1 is selected from titanium tetrachloride, molybdenum tetrachloride, tungsten tetrachloride, manganese chloride, zinc chloride, ferric chloride, ferrous chloride, ferric nitrate , aluminum chloride, aluminum nitrate, zinc nitrate, manganese nitrate, titanium nitrate at least one; preferably, be the mixture of titanium tetrachloride and iron chloride, mass ratio is 3-5:2; The metal salt , the mass ratio of dopamine hydrochloride and catalyzer is 3-5:10:0.5-0.7; Described catalyzer is the Tris-HCl solution that is 5-6 that the pH that contains 3-5wt% _CoCl is 5-6; Described heating and stirring reaction The temperature is 50-70° C., and the time is 2-3 hours; the mixed solvent is a mixture solvent of dichloromethane and ethyl acetate, and the mass ratio is 5-7:2.

As a further improvement of the present invention, the mass ratio of squash gum and hydroxypropyl guar gum in step S2 is 3-5:7.

As a further improvement of the present invention, the mass ratio of vegetable gum, lye and cationic etherifying agent in step S3 is 10:15-20:2-4; the lye is 50-60wt% NaOH or KOH solution ; The temperature of the heating reaction is 45-55 ℃, and the time is 3-5h; the pH value is adjusted to 7.5-8 with glacial acetic acid; the cationic etherification agent is 3-chloro-2-hydroxypropyl trimethyl chloride ammonium chloride.

As a further improvement of the present invention, the 1-vinyl-3-ethylimidazolium bromide, ethyl acrylate, acrylamide, octadecyl methacrylate, chain transfer agent, first initiator described in step S4 The mass ratio of agent and water is 4-7:2-4:3-5:1-2:0.05-0.1:0.02-0.05:50-70; the chain transfer agent is tert-butylmercaptan, tert-dodecyl At least one of alkyl mercaptan, butyl mercaptan, isopropyl mercaptan, dodecyl mercaptan; the mass ratio of the white oil, lipophilic emulsifier and the second initiator is 100-120:3 -5:0.5-1; the first initiator is selected from at least one of azobisisobutylamidine hydrochloride, sodium persulfate, potassium persulfate, ammonium persulfate; the second initiator is selected from At least one of azobisisobutyronitrile, azobisisobutyronitrile, azobisisoheptanonitrile, and dimethyl azobisisobutyrate; the mass ratio of the water phase to the oil phase is 5-7 : 10; the time of the stirring reaction is 2-4h.

As a further improvement of the present invention, the mass ratio of the temperature-controlled slow-release crosslinking agent, cationic vegetable gum and emulsion thickener in step S5 is 3-5:15-30:30-50.

As a further improvement of the present invention, it specifically includes the following steps:

S1. Preparation of temperature-controlled slow-release crosslinking agent: under nitrogen protection, after dissolving 3-5 parts by weight of metal salt in 100 parts by weight of water, add 10 parts by weight of dopamine hydrochloride and 0.5-0.7 parts by weight of catalyst, and heat to 50-70°C, stirred for 2-3 hours, cooled to room temperature, added an equal volume of mixed solvent, filtered, washed, dried, and pulverized to obtain a temperature-controlled slow-release crosslinking agent;

The metal salt is a mixture of titanium tetrachloride and ferric chloride, with a mass ratio of 3-5:2;

The catalyzer is a Tris-HCl solution containing 3-5wt% _CoCl2 with a pH of 5-6;

Described mixed solvent is the mixture solvent of dichloromethane and ethyl acetate, and mass ratio is 5-7:2;

S2. Combination of vegetable gums: mixing 3-5 parts by weight of squash gum and 7 parts by weight of hydroxypropyl guar gum to obtain vegetable gums;

S3. Preparation of cationic vegetable gum: disperse 10 parts by weight of vegetable gum prepared in step S2 in 50 parts by weight of water, add 15-20 parts by weight of 50-60wt% NaOH or KOH solution and 2-4 parts by weight of 3-chloro -2-Hydroxypropyltrimethylammonium chloride, heated to 45-55°C, reacted for 3-5h, adjusted the pH value of the solution to 7.5-8 with glacial acetic acid, filtered, washed, dried, and pulverized to obtain cationic vegetable gum;

S4. Preparation of emulsion tackifier: 4-7 parts by weight of 1-vinyl-3-ethylimidazolium bromide, 2-4 parts by weight of ethyl acrylate, 2-4 parts by weight of acrylamide, 3-5 parts by weight Octadecyl methacrylate, 0.05-0.1 parts by weight of the first initiator and 1-2 parts by weight of chain transfer agent are dissolved in 100 parts by weight of water to obtain an aqueous phase; 100-120 parts by weight of white oil, 3-5 parts by weight Mix parts by weight of lipophilic emulsifier and 0.5-1 parts by weight of the second initiator uniformly to obtain an oil phase; under the protection of nitrogen, add 50-70 parts by weight of the water phase dropwise to 100 parts by weight of the oil phase, and stir for 2-4 hours , to obtain emulsion tackifier;

Preferably, the lipophilic emulsifier is at least one selected from Span-20, Span-40, Span-60 and Span-80.

S5. Preparation of guar gum viscosifier for fracturing: 3-5 parts by weight of the temperature-controlled slow-release crosslinking agent prepared in step S1, 15-30 parts by weight of cationic vegetable gum prepared in step S3 and 30- Mix 50 parts by weight of the emulsion tackifier prepared in step S4, and stir and mix for 15-30 minutes to obtain a guar gum tackifier for fracturing.

The present invention further protects a guar gum viscosifier for fracturing prepared by the above-mentioned preparation method.

The present invention further protects the application of the above-mentioned guar gum viscosifier for fracturing in oil and gas well fracturing fluid.

The present invention has following beneficial effects:

Directly adding vegetable glue into the fracturing fluid as a viscosifier has a temperature resistance of less than 195°C, and the viscosity of the base fluid is relatively high, generally greater than 100mPa·s. Increased construction pressure and other issues. The temperature-controlled slow-release cross-linking agent prepared by the present invention, through the polydopamine polymerization reaction, through the abundant hydroxyl, amino and carboxyl groups on the polydopamine structure, as a chelating agent to fix metal ions, and by adding a suitable cross-linking agent amount, so that it releases the metal ion of the cross-linking substance at a suitable temperature, thereby playing the role of temperature-controlled release and delaying cross-linking, so that the vegetable gum added in the present invention has better temperature resistance, and its viscosity can be Control, so that the friction will not increase during construction, and the construction pressure will be avoided.

The metal salts are titanium tetrachloride and ferric chloride, the cost of which is relatively low, and the valence state of metal ions is high, which can play a role in efficient crosslinking. The addition of the two can better control the crosslinking effect. The temperature-controlled slow-release cross-linking effect is obvious, and it has a synergistic effect.

The cationic vegetable gum prepared by the present invention, after dissolving water-soluble squash gum and hydroxypropyl guar gum in water, is alkalized to obtain cationic vegetable gum, the preparation method is simpler, and the squash gum and hydroxypropyl guar gum Seoul gum is mainly composed of galactose and mannan. After alkalization treatment, it has positively charged quaternary ammonium salt branch chains, main chain galactose residues and multiple mannose residues. Hydroxyl, so that the cationic vegetable gum can be stretched in fresh water, salt water and saturated salt water, and form a hydrated film, which acts as a thickener in various water media. At the same time, the positively charged quaternary ammonium salt branch chain can neutralize the negative charge on the clay surface and can inhibit the dispersion of clay; while the multiple hydroxyl groups of the main chain are adsorbed on the clay surface by hydrogen bonds at multiple points to prevent dispersion and stabilize the well wall. The quaternary ammonium salt ion with a certain length of carbon chain is also a good bactericidal and antioxidant material, which can prevent the fracturing fluid viscosifier from being oxidized and degraded, and the viscosity remains unchanged for a long time, which can be used for a long time and has good storage stability High, reduce costs.

In addition, the present invention prepares an emulsion tackifier through the method of reverse emulsion polymerization, which is obtained through the polymerization reaction of double bonds. The ionic liquid compound 1-vinyl-3-ethylimidazolium bromide with a double bond is introduced into the main chain, which improves the high temperature stability, shear resistance and salt resistance of the emulsion tackifier. The group will not be shielded by the added salt, thereby avoiding the electrostatic repulsion between the salt ions and weakening the ion, the curling range of the molecular chain is reduced, and the apparent viscosity of the solution is not significantly reduced, showing a good salt tolerance effect. In addition, under continuous shearing, due to the steric effect of the imidazole ring structure, greater steric hindrance is generated as a rigid molecular motion, and the apparent viscosity decreases to a small extent, showing good shear strength. In addition, the introduction of ethyl acrylate further improves the salt resistance, and the introduction of octadecyl methacrylate further improves the temperature resistance and solubility, which has a synergistic effect. The emulsion viscosifier prepared by the present invention can quickly build up viscosities in the viscosifiers for fracturing fluids, and has good viscoelasticity. Construction work costs.

In the present invention, the emulsion viscosifier plays a role in rapid viscoelasticity, so that the fracturing fluid has good viscoelasticity. After further heating, the cationic vegetable gum is gradually viscosified through temperature control and slow release of the crosslinking agent. At the same time, the emulsion viscosifies The viscosity of the fracturing agent is also increased to a certain extent, so as to control the viscosity of the fracturing fluid and play a good role in increasing the viscosity. In the presence of polydopamine, it can promote the mutual adhesion between the cationic vegetable glue and the emulsion thickener, and play a role of immobilization.

The guar gum viscosifier for fracturing prepared by the present invention has good temperature resistance, salt resistance, and shear resistance, and can quickly become viscous, and the crosslinking agent is released slowly through temperature control, so that the fracturing fluid has a suitable Excellent viscoelasticity, neither pre-dosing nor continuous mixing vehicles are required, greatly reducing construction operation costs, anti-oxidative degradation, long-term viscosity, long-term use, high storage stability, cost reduction, and wide application prospect.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Tianjing gum was purchased from Shenzhen Love Biotechnology Co., Ltd., with an active substance content of >99%; hydroxypropyl guar gum was purchased from Shanghai Liming Chemical Co., Ltd., with an active substance content of >99.5%.

Example 1

The present embodiment provides a preparation method of a guar gum tackifier for fracturing, which specifically includes the following steps:

S1. Preparation of temperature-controlled slow-release cross-linking agent: under nitrogen protection, after dissolving 3 parts by weight of metal salt in 100 parts by weight of water, add 10 parts by weight of dopamine hydrochloride and 0.5 parts by weight of catalyst, and heat to 50 ° C. Stir and react for 2 hours, cool to room temperature, add an equal volume of mixed solvent, filter, wash with water, dry at 105°C for 1 hour, and pulverize to obtain a temperature-controlled slow-release crosslinking agent;

Described metal salt is the mixture of titanium tetrachloride and ferric chloride, and mass ratio is 3:2;

Described catalyzer is to contain 3wt% _CoCl The Tris-HCl solution that pH is 5;

Described mixed solvent is the mixture solvent of dichloromethane and ethyl acetate, and mass ratio is 5:2;

S2. Combination of vegetable gum: mixing 3 parts by weight of squash gum and 7 parts by weight of hydroxypropyl guar gum to obtain vegetable gum;

S3. Preparation of cationic vegetable gum: disperse 10 parts by weight of the vegetable gum prepared in step S2 in 50 parts by weight of water, add 15 parts by weight of 50wt% NaOH solution and 2 parts by weight of 3-chloro-2-hydroxypropyl trimethyl ammonium chloride, heated to 45°C, reacted for 3 hours, adjusted the pH of the solution to 7.5 with glacial acetic acid, filtered, washed with water, dried at 70°C for 1 hour, and crushed to obtain cationic vegetable glue;

S4. Preparation of emulsion tackifier: 4 parts by weight of 1-vinyl-3-ethylimidazolium bromide, 2 parts by weight of ethyl acrylate, 2 parts by weight of acrylamide, and 3 parts by weight of octadecyl methacrylate , 0.05 parts by weight of ammonium persulfate and 1 part by weight of tert-dodecyl mercaptan are dissolved in 100 parts by weight of water to obtain an aqueous phase; 100 parts by weight of white oil, 3 parts by weight of Span-60 and 0.5 parts by weight of azobis The isobutyramide was mixed evenly to obtain an oil phase; under the protection of nitrogen, 50 parts by weight of the water phase was added dropwise to 100 parts by weight of the oil phase, and stirred for 2 hours to obtain an emulsion tackifier; Infrared characterization of the polymer, among which, 3440cm ^-1 and 3175cm ^-1 are the NH stretching vibration peaks of the amide group; 2922cm ^-1 is the CH stretching vibration peak on the substituent of the imidazole ring, and 2852cm ^-1 is the symmetrical stretching vibration peak of -CH ₂ - , 1681cm ^-1 is the stretching vibration peak of C=O, 1555cm ^-1 and 1410cm ^-1 are the antisymmetric and symmetric stretching vibration peaks of -COO-, 952cm ^-1 is the in-plane rocking bending vibration peak of CH on the imidazole ring, 767cm ^-1 is the out-of-plane rocking bending vibration peak of CH on the imidazole ring, and 720cm ^-1 is the absorption peak of the hydrophobic chain -(CH ₂ )n.

S5. Preparation of guar gum viscosifier for fracturing: 3 parts by weight of the temperature-controlled slow-release crosslinking agent prepared in step S1, 15 parts by weight of cationic vegetable gum prepared in step S3, and 30 parts by weight of the cationic vegetable gum prepared in step S4 The obtained emulsion tackifier was mixed, stirred and mixed for 15 minutes to obtain a guar gum tackifier for fracturing.

Example 2

The present embodiment provides a preparation method of a guar gum tackifier for fracturing, which specifically includes the following steps:

S1. Preparation of temperature-controlled slow-release cross-linking agent: under nitrogen protection, after dissolving 5 parts by weight of metal salt in 100 parts by weight of water, add 10 parts by weight of dopamine hydrochloride and 0.7 parts by weight of catalyst, and heat to 70 ° C. Stir and react for 3 hours, cool to room temperature, add an equal volume of mixed solvent, filter, wash with water, dry at 105°C for 1 hour, and pulverize to obtain a temperature-controlled slow-release crosslinking agent;

Described metal salt is the mixture of titanium tetrachloride and ferric chloride, and mass ratio is 5:2;

Described catalyzer is to contain 5wt% _CoCl The Tris-HCl solution that pH is 6;

Described mixed solvent is the mixture solvent of dichloromethane and ethyl acetate, and mass ratio is 7:2;

S2. Combination of vegetable gum: mixing 5 parts by weight of squash gum and 7 parts by weight of hydroxypropyl guar gum to obtain vegetable gum;

S3. Preparation of cationic vegetable gum: disperse 10 parts by weight of the vegetable gum prepared in step S2 in 50 parts by weight of water, add 20 parts by weight of 60wt% KOH solution and 4 parts by weight of 3-chloro-2-hydroxypropyltrimethyl ammonium chloride, heated to 55°C, reacted for 5 hours, adjusted the pH of the solution to 8 with glacial acetic acid, filtered, washed with water, dried at 70°C for 1 hour, and pulverized to obtain cationic vegetable gum;

S4. Preparation of emulsion tackifier: 7 parts by weight of 1-vinyl-3-ethylimidazolium bromide, 4 parts by weight of ethyl acrylate, 4 parts by weight of acrylamide, and 5 parts by weight of octadecyl methacrylate , 0.1 parts by weight of potassium persulfate and 2 parts by weight of tert-butyl mercaptan are dissolved in 100 parts by weight of water to obtain an aqueous phase; Nitriles were mixed evenly to obtain an oil phase; under the protection of nitrogen, 70 parts by weight of the water phase was added dropwise to 100 parts by weight of the oil phase, and stirred for 4 hours to obtain an emulsion tackifier;

S5. Preparation of guar gum viscosifier for fracturing: 5 parts by weight of the temperature-controlled slow-release crosslinking agent prepared in step S1, 30 parts by weight of cationic vegetable gum prepared in step S3, and 50 parts by weight of the cationic vegetable gum prepared in step S4 The obtained emulsion tackifier was mixed, and stirred and mixed for 30 minutes to obtain a guar gum tackifier for fracturing.

Example 3

The present embodiment provides a preparation method of a guar gum tackifier for fracturing, which specifically includes the following steps:

S1. Preparation of temperature-controlled slow-release cross-linking agent: under nitrogen protection, after dissolving 4 parts by weight of metal salt in 100 parts by weight of water, add 10 parts by weight of dopamine hydrochloride and 0.6 parts by weight of catalyst, and heat to 60 ° C. Stir the reaction for 2.5 hours, cool to room temperature, add an equal volume of mixed solvent, filter, wash with water, dry at 105°C for 1 hour, and pulverize to obtain a temperature-controlled slow-release crosslinking agent;

Described metal salt is the mixture of titanium tetrachloride and ferric chloride, and mass ratio is 4:2;

Described catalyzer is to contain 4wt% _CoCl The pH is the Tris-HCl solution of 5.5;

Described mixed solvent is the mixture solvent of dichloromethane and ethyl acetate, and mass ratio is 6:2;

S2. Combination of vegetable gums: 4 parts by weight of squash gum and 7 parts by weight of hydroxypropyl guar gum are mixed to obtain vegetable gums;

S3. Preparation of cationic vegetable gum: disperse 10 parts by weight of the vegetable gum prepared in step S2 in 50 parts by weight of water, add 17 parts by weight of 55wt% NaOH solution and 3 parts by weight of 3-chloro-2-hydroxypropyl trimethyl ammonium chloride, heated to 50°C, reacted for 4 hours, adjusted the pH of the solution to 7.7 with glacial acetic acid, filtered, washed with water, dried at 70°C for 1 hour, and crushed to obtain cationic vegetable gum;

S4. Preparation of emulsion tackifier: 5 parts by weight of 1-vinyl-3-ethylimidazolium bromide, 3 parts by weight of ethyl acrylate, 3 parts by weight of acrylamide, and 4 parts by weight of stearyl methacrylate , 0.07 parts by weight of sodium persulfate and 1.5 parts by weight of dodecyl mercaptan are dissolved in 100 parts by weight of water to obtain an aqueous phase; 110 parts by weight of white oil, 4 parts by weight of Span-80 and 0.7 parts by weight of azodiiso Butyronitrile was mixed evenly to obtain an oil phase; under the protection of nitrogen, 60 parts by weight of the water phase was added dropwise to 100 parts by weight of the oil phase, and stirred for 3 hours to obtain an emulsion tackifier;

S5. Preparation of guar gum viscosifier for fracturing: 4 parts by weight of the temperature-controlled slow-release crosslinking agent prepared in step S1, 22 parts by weight of cationic vegetable gum prepared in step S3, and 40 parts by weight of the cationic vegetable gum prepared in step S4 The obtained emulsion tackifier was mixed, stirred and mixed for 20 minutes, and the guar gum tackifier for fracturing was obtained.

Example 4

Compared with Example 3, the difference lies in that the metal salt is a single titanium tetrachloride.

Example 5

Compared with Example 3, the difference is that the metal salt is a single ferric chloride.

Comparative example 1

Compared with Example 3, the difference is that polydopamine is replaced by polyethylene glycol in step S1.

details as follows:

S1. Preparation of temperature-controlled slow-release cross-linking agent: under nitrogen protection, after dissolving 4 parts by weight of metal salt in 100 parts by weight of water, add 10 parts by weight of polyethylene glycol, heat to 60°C, and stir for 2.5 hours. Cool to room temperature, add an equal volume of mixed solvent, filter, wash with water, dry at 105°C for 1 hour, and pulverize to obtain a temperature-controlled slow-release cross-linking agent;

Described metal salt is the mixture of titanium tetrachloride and ferric chloride, and mass ratio is 4:2;

The mixed solvent is a mixture solvent of dichloromethane and ethyl acetate, and the mass ratio is 6:2.

Comparative example 2

Compared with Example 3, the difference is that step S1 is not performed, and the crosslinking agent is a mixture of metal salts of titanium tetrachloride and ferric chloride, with a mass ratio of 4:2.

details as follows:

S1. Preparation of cross-linking agent: 4 parts by weight of titanium tetrachloride and 2 parts by weight of ferric chloride were uniformly mixed to obtain a cross-linking agent;

S2. Combination of vegetable gums: 4 parts by weight of squash gum and 7 parts by weight of hydroxypropyl guar gum are mixed to obtain vegetable gums;

S3. Preparation of cationic vegetable gum: disperse 10 parts by weight of the vegetable gum prepared in step S2 in 50 parts by weight of water, add 17 parts by weight of 55wt% NaOH solution and 3 parts by weight of 3-chloro-2-hydroxypropyl trimethyl ammonium chloride, heated to 50°C, reacted for 4 hours, adjusted the pH of the solution to 7.7 with glacial acetic acid, filtered, washed with water, dried at 70°C for 1 hour, and crushed to obtain cationic vegetable gum;

S4. Preparation of emulsion tackifier: 5 parts by weight of 1-vinyl-3-ethylimidazolium bromide, 3 parts by weight of ethyl acrylate, 3 parts by weight of acrylamide, and 4 parts by weight of stearyl methacrylate , 0.07 parts by weight of sodium persulfate and 1.5 parts by weight of dodecyl mercaptan are dissolved in 100 parts by weight of water to obtain an aqueous phase; 110 parts by weight of white oil, 4 parts by weight of Span-80 and 0.7 parts by weight of azodiiso Butyronitrile was mixed evenly to obtain an oil phase; under the protection of nitrogen, 60 parts by weight of the water phase was added dropwise to 100 parts by weight of the oil phase, and stirred for 3 hours to obtain an emulsion tackifier;

S5. Preparation of guar gum tackifier for fracturing: 4 parts by weight of the cross-linking agent prepared in step S1, 22 parts by weight of the cationic vegetable gum prepared in step S3 and 40 parts by weight of the emulsion made in step S4 The viscose was mixed, stirred and mixed for 20 minutes to obtain a guar gum viscosifier for fracturing.

Comparative example 3

Compared with Example 3, the difference is that the vegetable gum in step S2 is a single kale gum.

details as follows:

S2. The vegetable gum is squash gum.

Comparative example 4

Compared with Example 3, the difference is that the vegetable gum in step S2 is a single hydroxypropyl guar gum.

details as follows:

S2. The vegetable gum is hydroxypropyl guar gum.

Comparative example 5

Compared with Embodiment 3, the difference is that step S3 is not performed.

details as follows:

S1. Preparation of temperature-controlled slow-release cross-linking agent: under nitrogen protection, after dissolving 4 parts by weight of metal salt in 100 parts by weight of water, add 10 parts by weight of dopamine hydrochloride and 0.6 parts by weight of catalyst, and heat to 60 ° C. Stir the reaction for 2.5 hours, cool to room temperature, add an equal volume of mixed solvent, filter, wash with water, dry at 105°C for 1 hour, and pulverize to obtain a temperature-controlled slow-release crosslinking agent;

Described metal salt is the mixture of titanium tetrachloride and ferric chloride, and mass ratio is 4:2;

Described catalyzer is to contain 4wt% _CoCl The pH is the Tris-HCl solution of 5.5;

Described mixed solvent is the mixture solvent of dichloromethane and ethyl acetate, and mass ratio is 6:2;

S2. Combination of vegetable gums: 4 parts by weight of squash gum and 7 parts by weight of hydroxypropyl guar gum are mixed to obtain vegetable gums;

S3. Preparation of emulsion tackifier: 5 parts by weight of 1-vinyl-3-ethylimidazolium bromide, 3 parts by weight of ethyl acrylate, 3 parts by weight of acrylamide, and 4 parts by weight of octadecyl methacrylate , 0.07 parts by weight of sodium persulfate and 1.5 parts by weight of dodecyl mercaptan are dissolved in 100 parts by weight of water to obtain an aqueous phase; 110 parts by weight of white oil, 4 parts by weight of Span-80 and 0.7 parts by weight of azodiiso Butyronitrile was mixed evenly to obtain an oil phase; under the protection of nitrogen, 60 parts by weight of the water phase was added dropwise to 100 parts by weight of the oil phase, and stirred for 3 hours to obtain an emulsion tackifier;

S4. Preparation of guar gum tackifier for fracturing: 4 parts by weight of the temperature-controlled slow-release crosslinking agent prepared in step S1, 22 parts by weight of vegetable gum prepared in step S2 and 40 parts by weight of step S4 The emulsion viscosifier was mixed, stirred and mixed for 20 minutes, and the guar gum viscosifier for fracturing was obtained.

Comparative example 6

Compared with Example 3, the difference is that 1-vinyl-3-ethylimidazolium bromide is not added in step S4, and ethyl acrylate is 8 parts by weight.

details as follows:

S4. Preparation of emulsion tackifier: 8 parts by weight of ethyl acrylate, 3 parts by weight of acrylamide, 4 parts by weight of stearyl methacrylate, 0.07 parts by weight of sodium persulfate and 1.5 parts by weight of dodecyl sulfide Alcohol was dissolved in 100 parts by weight of water to obtain a water phase; 110 parts by weight of white oil, 4 parts by weight of Span-80 and 0.7 parts by weight of azobisisobutyronitrile were uniformly mixed to obtain an oil phase; under nitrogen protection, 60 Parts by weight of the water phase are added dropwise to 100 parts by weight of the oil phase, stirred and reacted for 3 hours to obtain an emulsion thickener.

Comparative example 7

Compared with Example 3, the difference is that no 1-vinyl-3-ethylimidazolium bromide was added in step S4, and 9 parts by weight of octadecyl methacrylate.

details as follows:

S4. Preparation of emulsion tackifier: 3 parts by weight of ethyl acrylate, 3 parts by weight of acrylamide, 9 parts by weight of stearyl methacrylate, 0.07 parts by weight of sodium persulfate and 1.5 parts by weight of dodecyl sulfide Alcohol was dissolved in 100 parts by weight of water to obtain a water phase; 110 parts by weight of white oil, 4 parts by weight of Span-80 and 0.7 parts by weight of azobisisobutyronitrile were uniformly mixed to obtain an oil phase; under nitrogen protection, 60 Parts by weight of the water phase are added dropwise to 100 parts by weight of the oil phase, stirred and reacted for 3 hours to obtain an emulsion thickener.

Comparative example 8

Compared with Example 3, the difference is that no octadecyl methacrylate is added in step S4.

details as follows:

S4. Preparation of emulsion tackifier: 9 parts by weight of 1-vinyl-3-ethyl imidazolium bromide, 3 parts by weight of ethyl acrylate, 3 parts by weight of acrylamide, 0.07 parts by weight of sodium persulfate and 1.5 parts by weight of ten Dialkyl mercaptan is dissolved in 100 parts by weight of water to obtain an aqueous phase; 110 parts by weight of white oil, 4 parts by weight of Span-80 and 0.7 parts by weight of azobisisobutyronitrile are mixed uniformly to obtain an oil phase; 60 parts by weight of the water phase was added dropwise into 100 parts by weight of the oil phase, stirred and reacted for 3 hours to obtain an emulsion tackifier.

Comparative example 9

Compared with Example 3, the difference is that no ethyl acrylate is added in step S4.

details as follows:

S4. Preparation of emulsion tackifier: 8 parts by weight of 1-vinyl-3-ethylimidazolium bromide, 3 parts by weight of acrylamide, 4 parts by weight of octadecyl methacrylate, and 0.07 parts by weight of sodium persulfate Dissolve 1.5 parts by weight of dodecyl mercaptan in 100 parts by weight of water to obtain an aqueous phase; mix 110 parts by weight of white oil, 4 parts by weight of Span-80 and 0.7 parts by weight of azobisisobutyronitrile to obtain an oil phase; under the protection of nitrogen, 60 parts by weight of the water phase was added dropwise to 100 parts by weight of the oil phase, and stirred for 3 hours to obtain an emulsion tackifier.

Comparative example 10

Compared with Example 3, the difference is that in step S5, the temperature-controlled slow-release cross-linking agent is replaced by an equivalent amount of polydopamine.

details as follows:

S1. Preparation of polydopamine: under nitrogen protection, add 10 parts by weight of dopamine hydrochloride and 0.6 parts by weight of catalyst to 100 parts by weight of water, heat to 60°C, stir for 2.5 hours, cool to room temperature, and add an equal volume of mixed solvent , filtered, washed with water, dried at 105°C for 1 hour, and pulverized to obtain polydopamine;

Described mixed solvent is the mixture solvent of dichloromethane and ethyl acetate, and mass ratio is 6:2;

S2. Combination of vegetable gums: 4 parts by weight of squash gum and 7 parts by weight of hydroxypropyl guar gum are mixed to obtain vegetable gums;

S3. Preparation of cationic vegetable gum: disperse 10 parts by weight of the vegetable gum prepared in step S2 in 50 parts by weight of water, add 17 parts by weight of 55wt% NaOH solution and 3 parts by weight of 3-chloro-2-hydroxypropyl trimethyl ammonium chloride, heated to 50°C, reacted for 4 hours, adjusted the pH of the solution to 7.7 with glacial acetic acid, filtered, washed with water, dried at 70°C for 1 hour, and crushed to obtain cationic vegetable gum;

S4. Preparation of emulsion tackifier: 5 parts by weight of 1-vinyl-3-ethylimidazolium bromide, 3 parts by weight of ethyl acrylate, 3 parts by weight of acrylamide, and 4 parts by weight of stearyl methacrylate , 0.07 parts by weight of sodium persulfate and 1.5 parts by weight of dodecyl mercaptan are dissolved in 100 parts by weight of water to obtain an aqueous phase; 110 parts by weight of white oil, 4 parts by weight of Span-80 and 0.7 parts by weight of azodiiso Butyronitrile was mixed evenly to obtain an oil phase; under the protection of nitrogen, 60 parts by weight of the water phase was added dropwise to 100 parts by weight of the oil phase, and stirred for 3 hours to obtain an emulsion tackifier;

S5. Preparation of guar gum tackifier for fracturing: 4 parts by weight of the polydopamine prepared in step S1, 22 parts by weight of the cationic vegetable gum prepared in step S3 and 40 parts by weight of the emulsion prepared in step S4 are thickened agent, and stirred and mixed for 20 minutes to obtain a guar gum viscosifier for fracturing.

Comparative example 11

Compared with Example 3, the difference is that no cationic vegetable gum is added in step S5.

details as follows:

S1. Preparation of temperature-controlled slow-release cross-linking agent: under nitrogen protection, after dissolving 4 parts by weight of metal salt in 100 parts by weight of water, add 10 parts by weight of dopamine hydrochloride and 0.6 parts by weight of catalyst, and heat to 60 ° C. Stir the reaction for 2.5 hours, cool to room temperature, add an equal volume of mixed solvent, filter, wash with water, dry at 105°C for 1 hour, and pulverize to obtain a temperature-controlled slow-release crosslinking agent;

Described metal salt is the mixture of titanium tetrachloride and ferric chloride, and mass ratio is 4:2;

Described catalyzer is to contain 4wt% _CoCl The pH is the Tris-HCl solution of 5.5;

Described mixed solvent is the mixture solvent of dichloromethane and ethyl acetate, and mass ratio is 6:2;

S2. Preparation of emulsion tackifier: 5 parts by weight of 1-vinyl-3-ethylimidazolium bromide, 3 parts by weight of ethyl acrylate, 3 parts by weight of acrylamide, and 4 parts by weight of octadecyl methacrylate , 0.07 parts by weight of sodium persulfate and 1.5 parts by weight of dodecyl mercaptan are dissolved in 100 parts by weight of water to obtain an aqueous phase; 110 parts by weight of white oil, 4 parts by weight of Span-80 and 0.7 parts by weight of azodiiso Butyronitrile was mixed evenly to obtain an oil phase; under the protection of nitrogen, 60 parts by weight of the water phase was added dropwise to 100 parts by weight of the oil phase, and stirred for 3 hours to obtain an emulsion tackifier;

S3. Preparation of guar gum tackifier for fracturing: 4 parts by weight of the temperature-controlled slow-release crosslinking agent prepared in step S1 and 62 parts by weight of the emulsion tackifier prepared in step S2 were mixed, stirred and mixed for 20 minutes, Obtain guar gum viscosifier for fracturing.

Comparative example 12

Compared with Example 3, the difference is that no emulsion tackifier is added in step S5.

details as follows:

S1. Preparation of temperature-controlled slow-release cross-linking agent: under nitrogen protection, after dissolving 4 parts by weight of metal salt in 100 parts by weight of water, add 10 parts by weight of dopamine hydrochloride and 0.6 parts by weight of catalyst, and heat to 60 ° C. Stir the reaction for 2.5 hours, cool to room temperature, add an equal volume of mixed solvent, filter, wash with water, dry at 105°C for 1 hour, and pulverize to obtain a temperature-controlled slow-release crosslinking agent;

Described metal salt is the mixture of titanium tetrachloride and ferric chloride, and mass ratio is 4:2;

Described catalyzer is to contain 4wt% _CoCl The pH is the Tris-HCl solution of 5.5;

Described mixed solvent is the mixture solvent of dichloromethane and ethyl acetate, and mass ratio is 6:2;

S2. Combination of vegetable gums: 4 parts by weight of squash gum and 7 parts by weight of hydroxypropyl guar gum are mixed to obtain vegetable gums;

S3. Preparation of cationic vegetable gum: disperse 10 parts by weight of the vegetable gum prepared in step S2 in 50 parts by weight of water, add 17 parts by weight of 55wt% NaOH solution and 3 parts by weight of 3-chloro-2-hydroxypropyl trimethyl ammonium chloride, heated to 50°C, reacted for 4 hours, adjusted the pH of the solution to 7.7 with glacial acetic acid, filtered, washed with water, dried at 70°C for 1 hour, and crushed to obtain cationic vegetable gum;

S4. Preparation of guar gum viscosifier for fracturing: Mix 4 parts by weight of the temperature-controlled slow-release crosslinking agent prepared in step S1 and 62 parts by weight of the cationic vegetable gum prepared in step S3, and stir and mix for 20 minutes to obtain Guar gum type viscosifier for fracturing.

Test Example 1 Stability Test

The guar gum viscosifiers for fracturing prepared in Examples 1-5 and Comparative Examples 1-12 of the present invention were left to stand for 6-8 months, and their stratification was observed.

The results are shown in Table 1.

Table 1

It can be seen from the above table that the guar gum viscosifiers for fracturing prepared in Examples 1-3 of the present invention have better storage stability.

test case 2

The guar gum viscosifiers for fracturing prepared in Examples 1-5 and Comparative Examples 1-12 of the present invention were formulated into aqueous solutions with a content of 0.5 wt%, and performance tests were performed.

1. Thickening performance test

The apparent viscosity was measured by a six-speed rotational viscometer at room temperature (25°C) and a shear rate of 170 s ^-1 , and was defined as the initial state apparent viscosity (η ₀ ).

2. Salt resistance test

NaCl was added to the solution so that the NaCl concentration in the solution was 0.2wt%, and the apparent viscosity was measured by a six-speed rotational viscometer at room temperature (25°C) and a shear rate of 170s ^-1 , and the viscosity retention (%) was calculated.

3. Temperature resistance test

The apparent viscosity was measured by a six-speed rotational viscometer at a temperature of 80 °C, 120 °C and 200 °C at a shear rate of 170 s ^-1 , and the viscosity retention rate (%) was calculated.

4. Shear resistance test

The solution was continuously sheared for 2 h with a six-speed rotational viscometer, and the apparent viscosity was measured by a six-speed rotational viscometer at room temperature (25°C) and a shear rate of 170 s ^-1 to calculate the viscosity retention (%).

Viscosity retention (%) = (apparent viscosity at the time of measurement η ₁ - initial state apparent viscosity η ₀ )/initial state apparent viscosity η ₀ × 100%

The results are shown in Table 2.

Table 2

It can be seen from the above table that the guar gum viscosifier for fracturing prepared in Examples 1-3 of the present invention has better salt resistance, temperature resistance and shear resistance.

Embodiment 4, 5 compare with embodiment 3, metal salt is single titanium tetrachloride or ferric chloride. Compared with Example 3 in Comparative Example 10, the temperature-controlled slow-release cross-linking agent in step S5 is replaced by an equivalent amount of polydopamine, and its temperature resistance decreases. The metal salt of the present invention is titanium tetrachloride and ferric chloride, and its cost The valence state of metal ions is lower, and the valence state of metal ions is higher, which can play the role of efficient cross-linking. The addition of the two can play a better role in controlling cross-linking. effect.

Compared with Example 3 in Comparative Example 1, polydopamine was replaced by polyethylene glycol in step S1, its stability decreased, and the temperature-controlled slow-release effect decreased significantly. At the same time, the storage stability decreased, and the viscosity at 80 ° C decreased. 120 °C and 200 °C, the viscosity further decreased, and it did not have a good temperature-controlled slow-release effect. It can be seen that compared with polyethylene glycol, polydopamine can better chelate metal ions and release them at a suitable temperature. , the presence of polydopamine can play a better role in stabilizing the thickening agent.

Compared with Example 3, Comparative Example 2 did not carry out step S1, and the cross-linking agent was a mixture of titanium tetrachloride and ferric chloride as a metal salt, and the temperature-controlled slow-release effect decreased significantly, and the stability decreased. The presence of polydopamine, It can play a better role in stabilizing the tackifier.

Comparative Examples 3 and 4 Compared with Example 3, the vegetable gum in step S2 is a single squash gum or hydroxypropyl guar gum, and its storage stability, apparent viscosity, and shear resistance are decreased. Squat gum and hydroxypropyl guar gum of the present invention are mainly composed of galactose and mannan, and the combination of the two can effectively increase the viscosity. After alkalization treatment, it has positive Electric quaternary ammonium salt branch chain, multiple hydroxyl groups on the main chain galactose residue and mannose residue, so that the cationic plant gum can be stretched in fresh water, salt water and saturated salt water, and form a hydration film, It acts as a viscosifier in various water media. The quaternary ammonium salt ion with a certain length of carbon chain is also a good bactericidal and antioxidant material, which can prevent the prepared fracturing fluid viscosifier from oxidative degradation. Long-term unchanged, can be used for a long time, high storage stability.

Compared with Example 3, Comparative Example 5 did not perform step S3, and its storage stability and shear resistance decreased. After the vegetable gum of the present invention is treated by alkalization, it has a positively charged quaternary ammonium salt branch chain, a plurality of hydroxyl groups on the main chain galactose residue and mannose residue, so that the cationic vegetable gum can be used in fresh water, It can stretch in both salt water and saturated salt water, and form a hydrated film, which acts as a thickener in various aqueous media. At the same time, the positively charged quaternary ammonium salt branch chain can neutralize the negative charge on the clay surface and can inhibit the dispersion of clay; while the multiple hydroxyl groups of the main chain are adsorbed on the clay surface by hydrogen bonds at multiple points to prevent dispersion and stabilize the well wall. The quaternary ammonium salt ion with a certain length of carbon chain is also a good bactericidal and antioxidant material, which can prevent the fracturing fluid viscosifier from being oxidized and degraded, and the viscosity remains unchanged for a long time, which can be used for a long time and has good storage stability High, reduce costs.

Comparative Example 6 Compared with Example 3, no 1-vinyl-3-ethylimidazolium bromide was added in step S4, and ethyl acrylate was 8 parts by weight. Compared with Example 3 in Comparative Example 9, no ethyl acrylate was added in step S4. Its salt-tolerance performance decreased significantly. In the present invention, the ionic liquid compound 1-vinyl-3-ethylimidazolium bromide with double bonds is introduced into the main chain to improve the high-temperature stability, shear resistance and salt resistance of the emulsion tackifier. Its ionic groups will not be shielded by the added salt, thus avoiding the electrostatic repulsion between ions weakened by salt ions, the curling range of the molecular chain is reduced, and the apparent viscosity of the solution is not significantly reduced, showing a good salt tolerance effect. In addition, the introduction of ethyl acrylate further improves the salt resistance and has a synergistic effect.

Comparative Example 7 Compared with Example 3, no 1-vinyl-3-ethylimidazolium bromide was added in step S4, and 9 parts by weight of octadecyl methacrylate. Compared with Example 3 in Comparative Example 8, no octadecyl methacrylate was added in step S4. Its high temperature resistance performance decreases, and the viscosity retention rate at 120°C and 200°C decreases significantly. In the present invention, the ionic liquid compound 1-vinyl-3-ethylimidazolium bromide with double bonds is introduced into the main chain to improve the high-temperature stability, shear resistance and salt resistance of the emulsion tackifier. In addition, the introduction of octadecyl methacrylate further improves the temperature resistance and solubility, and has a synergistic effect.

Compared with Example 3 in Comparative Examples 11 and 12, no cationic vegetable gum or emulsion thickener was added in step S5. In Comparative Example 11, the apparent viscosity decreased, the stability decreased, the high temperature viscosity retention rate decreased, and the shear resistance decreased. In Comparative Example 12, the high temperature resistance and stability decreased, and the salt resistance and shear resistance decreased. The emulsion viscosifier of the present invention plays a role in rapid viscoelasticity, so that the fracturing fluid has good viscoelasticity. After further heating, the cationic vegetable gum is gradually viscosified through temperature control and slow release of the cross-linking agent. At the same time, the emulsion viscosifier The viscosity of the fracturing fluid is also increased to a certain extent, so as to control the viscosity of the fracturing fluid and play a good role in increasing the viscosity. In the presence of polydopamine, it can promote the mutual adhesion between the cationic vegetable glue and the emulsion thickener, and play a role of immobilization.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (7)

1. The preparation method of the guar gum tackifier for fracturing is characterized by comprising the following steps:

s1, preparing a temperature-controlled slow-release cross-linking agent: under the protection of inert gas, dissolving metal salt in water, adding dopamine hydrochloride and a catalyst, heating and stirring for reaction, cooling to room temperature, adding a mixed solvent, filtering, washing, drying and crushing to obtain a temperature-controlled slow-release cross-linking agent; the mass ratio of the metal salt to the dopamine hydrochloride to the catalyst is 3-5; the mixed solvent is a mixture solvent of dichloromethane and ethyl acetate, and the mass ratio is 5-7;

s2, combination of vegetable gum: mixing sesbania gum and hydroxypropyl guar gum to obtain vegetable gum; the mass ratio of the sesbania gum to the hydroxypropyl guar gum is 3-5;

s3, preparation of cationic vegetable gum: dispersing the vegetable gum prepared in the step S2 in water, adding an alkali liquor and a cationic etherifying agent, heating for reaction, adjusting the pH value of the solution, filtering, washing, drying and crushing to obtain cationic vegetable gum; the mass ratio of the vegetable gum to the alkali liquor to the cationic etherifying agent is (10-20);

s4, preparing an emulsion tackifier: dissolving 1-vinyl-3-ethylimidazole bromine salt, ethyl acrylate, acrylamide, octadecyl methacrylate, a first initiator and a chain transfer agent in water to obtain a water phase; uniformly mixing white oil, a lipophilic emulsifier and a second initiator to obtain an oil phase; under the protection of inert gas, dropwise adding the water phase into the oil phase, and stirring for reaction to obtain an emulsion tackifier; the mass ratio of the 1-vinyl-3-ethylimidazole bromine salt, the ethyl acrylate, the acrylamide, the octadecyl methacrylate, the chain transfer agent, the first initiator and the water is 4-7: 0.02-0.05:50-70 parts of; the mass ratio of the white oil to the lipophilic emulsifier to the second initiator is 100-120; the mass ratio of the water phase to the oil phase is 5-7;

s5, preparing a guar gum tackifier for fracturing: mixing the temperature-controlled slow-release cross-linking agent prepared in the step S1, the cationic plant gum prepared in the step S3 and the emulsion tackifier prepared in the step S4, and uniformly stirring to obtain the guar gum tackifier for fracturing; the mass ratio of the temperature-controlled slow-release cross-linking agent to the cationic vegetable gum to the emulsion tackifier is 3-5.

2. The method according to claim 1, wherein the metal salt in step S1 is selected from titanium tetrachloride, molybdenum tetrachloride, tungsten tetrachloride, manganese chloride, zinc chloride, chlorineAt least one of ferric chloride, ferrous chloride, ferric nitrate, aluminum chloride, aluminum nitrate, zinc nitrate, manganese nitrate and titanium nitrate; the catalyst is a catalyst containing 3-5wt% of CoCl ₂ Tris-HCl solution with pH of 5-6; the temperature of the heating and stirring reaction is 50-70 ℃, and the time is 2-3h.

3. The method according to claim 2, wherein the metal salt is a mixture of titanium tetrachloride and ferric chloride in a mass ratio of 3 to 5.

4. The method according to claim 1, wherein the alkali solution in step S3 is 50-60wt% NaOH or KOH solution; the heating reaction is carried out at the temperature of 45-55 ℃ for 3-5h; adjusting pH to 7.5-8 with glacial acetic acid; the cationic etherifying agent is 3-chloro-2-hydroxypropyl trimethyl ammonium chloride.

5. The method according to claim 1, wherein the chain transfer agent in step S4 is at least one selected from the group consisting of t-butyl mercaptan, t-dodecyl mercaptan, butyl mercaptan, isopropyl mercaptan, and dodecyl mercaptan; the first initiator is selected from at least one of azodiisobutyramidine hydrochloride, sodium persulfate, potassium persulfate and ammonium persulfate; the second initiator is at least one of azodiisobutyramidine, azodiisobutyronitrile, azodiisoheptonitrile and dimethyl azodiisobutyrate; the stirring reaction time is 2-4h.

6. A guar gum tackifier for fracturing prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the guar viscosifier for fracturing according to claim 6 in fracturing fluids for oil and gas wells.