A kind of clay stabilizer for fracturing acidification and preparation method thereof

Abstract

The present invention belongs to the technical field of oil extraction, and specifically relates to a kind of clay stabilizer for fracturing and acidification and its preparation method. The preparation method is as follows: trimethylolpropane allyl ether and distilled water are added to a four-necked flask, aminosulfonic acid is slowly added, water bath cooling, insulation reaction, and pH7-8 is adjusted; distilled water, 3-(methacrylamide) propyl dimethyl (3-sulfopropyl) ammonium inner salt, and buffer salt are sequentially added to the four-necked flask, and stirred evenly; an initiator aqueous solution is dripped into the above-mentioned four-necked flask, the reaction automatically heats up, and the temperature is no longer increased. After the reaction continues, the temperature is raised, the temperature is kept, and a reducing agent aqueous solution is added to terminate the reaction to obtain a clay stabilizer solution; the above-mentioned clay stabilizer solution is dried and granulated to obtain a product clay stabilizer. The clay stabilizer has the advantages of a wide source of raw materials, a simple preparation process, a high anti-swelling rate, and water-resistant, and the anti-swelling rate reaches more than 96%, and the anti-swelling rate after water washing reaches more than 93%.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum extraction, and in particular relates to a clay stabilizer for fracturing and acidification and a preparation method thereof. Background Art

[0002] Water injection is a commonly used oil extraction method in the later stage of oil field development. It has the advantages of low cost, high return, quick effect and simple method. The water injected into the ground is conducive to stabilizing the reservoir pressure. Water injection is an important measure for oil fields to maintain long-term stable production. During the mining process, the impact of injected water on the reservoir should be reduced as much as possible without damaging the reservoir permeability. The size of the reservoir permeability is the key to whether the oil field can produce stably and prolific. In the actual production process, as the amount of water injection increases, the production capacity of the oil field tends to decrease. Studies have shown that the swelling of clay minerals in the reservoir when exposed to water is an important factor causing this phenomenon. Clay minerals are widely present in oil reservoirs. If they come into contact with incompatible external fluids, they will hydrate, swell and disperse and migrate, blocking the reservoir channels and causing damage to the oil and gas layers.

[0003] According to the water-sensitive damage mechanism of clay minerals, if some additives are added to the injected water, the attraction of the dipole of the oxygen bond or the amino oxygen bond of the clay crystal layer to water molecules can be isolated, thus preventing the clay from hydrating and expanding. At the same time, the inter-ionic repulsion force is generated in the hydrated clay system, which plays a role in polymerization and condensation, causing the clay particles to aggregate into clay particles, and finally preventing the dispersion and migration of clay. This additive is a clay stabilizer.

[0004] Generally, clay stabilizers used for water injection are not only required to have good anti-swelling effect and low effective concentration, but also to have good compatibility with formation water, stable and lasting inhibition of clay expansion in the formation, and resistance to various fluid erosion. During the process of water injection in oil layers, the expansion of clay minerals and the migration of particles will damage the permeability of the oil layer.

[0005] Clay stabilizers are used more and more widely and there are more and more types. According to their chemical composition, they can be divided into inorganic salts, inorganic polymers, cationic surfactants, non-ionic and cationic organic polymers.

[0006] CN110129015A discloses a method for preparing a waterproof clay stabilizer, which belongs to the technical field of oilfield exploitation. The invention first soaks rice leaves in hydrochloric acid to obtain a reactant, then mixes the reactant with malic acid and aluminum chloride, stirs at high temperature, ultrasonically oscillates, calcines at high temperature, grinds, and then mixes and stirs with tetraethyl orthosilicate to obtain a reactant, and then mixes the reactant with ferric chloride solution to obtain a preformed product, and finally blends the preformed product with acrylate, propylene glycol and other additives to obtain a waterproof clay stabilizer. The invention adds malic acid to corrode and modify organic fibers, so that the organic fibers break, the length is reduced, and the surface roughness is increased, which is conducive to complexing aluminum ions, so that the salt corrosion resistance and waterproof performance of the clay are improved, and the tetraethyl orthosilicate is coated with carbon fibers, so that the surface of each molecule is coated with tetraethyl orthosilicate molecules, and Si-O bonds are introduced into each molecule, so that the acid and alkali corrosion resistance and water resistance of the clay agent are improved, and the invention has broad application prospects. However, from the perspective of the preparation process, the invention belongs to non-ionic organic matter, and has limited adsorption effect on negatively charged clay, thus affecting the anti-swelling effect to some extent, and the anti-swelling rate is less than 90%.

[0007] CN106147739A discloses a fracturing clay stabilizer and a preparation method thereof, which is prepared from the following raw materials in parts by weight: 35-50 parts of choline chloride, 3-8 parts of calcium chloride, 40-50 parts of water, 5-10 parts of methanol and 1-5 parts of alcohol ether solvent; the preparation method of the fracturing clay stabilizer comprises the following specific steps: (1) weighing choline chloride and methanol according to the above formula and mixing them evenly to obtain component a; (2) adding the formulated amount of water, calcium chloride and alcohol ether solvent to component a obtained in step (1) in sequence, stirring until the solid is completely dissolved, and discharging the material. The fracturing clay stabilizer prepared by the method has excellent anti-swelling performance and good compatibility. However, the clay stabilizer of the invention contains a large amount of methanol and alcohol ether, which are easily washed away by water, indicating that the clay stabilizer has limited water washing resistance, and the anti-swelling rate is only 50%, which cannot meet production needs. Summary of the invention

[0008] The present invention aims to provide a clay stabilizer for fracturing acidification and a preparation method thereof in view of the above-mentioned deficiencies in the prior art. The clay stabilizer has the advantages of a wide source of raw materials, a simple preparation process, a high anti-swelling rate, and water-resistant. When the concentration is 2wt%, the anti-swelling rate reaches more than 96%, and after water washing, the anti-swelling rate can reach more than 92%.

[0009] One of the purposes of the present invention is to disclose a clay stabilizer for fracturing and acidizing, wherein the molecular structure of the clay stabilizer is as follows:

[0010]

[0011] Wherein, m = 1000-10000;

[0012] n=200-10000.

[0013] Preferably, the viscosity average molecular weight of the clay stabilizer is 200,000-2,000,000.

[0014] Another object of the present invention is to disclose a method for preparing a clay stabilizer for fracturing and acidizing, wherein the specific steps of the preparation method are as follows:

[0015] (1) Add trimethylolpropane allyl ether and distilled water to a four-necked flask, slowly add sulfamic acid in batches, cool in a water bath, and continue to keep warm for 30-60 minutes after adding sulfamic acid. The reaction temperature is controlled not to exceed 60° C. during the whole process, and the pH is adjusted to 7-8 with potassium hydroxide solution;

[0016] (2) Add distilled water, 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, and buffer salt to a four-necked flask in sequence and stir evenly;

[0017] (3) adding an initiator aqueous solution dropwise to the above four-necked flask, the reaction temperature rises automatically, and the reaction is continued for 30-60 minutes after the temperature stops rising, and the temperature is raised to 60-65° C. and kept warm for 30-60 minutes, and a reducing agent aqueous solution is added to terminate the reaction to obtain a clay stabilizer solution;

[0018] (4) drying and granulating the clay stabilizer solution to obtain a clay stabilizer product.

[0019] In the present invention, preferably, based on 1 mol part of trimethylolpropane allyl ether, the amounts of aminosulfonic acid and 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt are 1.8-2.5 mol parts and 0.2-1 mol parts, respectively.

[0020] In the present invention, preferably, the weight ratio of distilled water to trimethylolpropane allyl ether in step (1) is 0.1-0.2:1.

[0021] In the present invention, preferably, the weight ratio of distilled water to trimethylolpropane allyl ether in step (2) is 4-6:1.

[0022] In the present invention, preferably, the buffer salt in step (2) is one of sodium dihydrogen phosphate, potassium dihydrogen phosphate, ammonium dihydrogen phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, and diammonium hydrogen phosphate, and the weight ratio of the buffer salt to trimethylolpropane allyl ether is 0.1-0.2:1.

[0023] More preferably, the buffer salt is one of potassium dihydrogen phosphate, ammonium dihydrogen phosphate, dipotassium hydrogen phosphate, and diammonium hydrogen phosphate.

[0024] In the present invention, preferably, the initiator in step (3) is one of potassium persulfate, ammonium persulfate and sodium persulfate, and the weight ratio of the initiator to trimethylolpropane allyl ether is 0.01-0.05:1.

[0025] More preferably, the initiator is one of potassium persulfate and ammonium persulfate.

[0026] In the present invention, preferably, the reducing agent in step (3) is one of sodium sulfite, potassium sulfite, sodium bisulfite and potassium bisulfite, and the weight ratio of the reducing agent to trimethylolpropane allyl ether is 0.01-0.05:1.

[0027] More preferably, the reducing agent is potassium sulfite or potassium bisulfite.

[0028] The reaction equation for the synthesis of the clay stabilizer for fracturing acidification of the present invention is as follows:

[0029]

[0030] The working principle of the clay stabilizer for fracturing acidification of the present invention mainly includes the following aspects:

[0031] (1) The clay stabilizer of the present invention contains quaternary ammonium cations, which can adsorb and neutralize the negative charge on the clay surface, reduce the repulsion between crystal layers, and play an anti-swelling role;

[0032] (2) The clay stabilizer of the present invention has ammonium groups in its molecules, which have the same functions as quaternary ammonium cations and can also enter the structural pores of the clay, firmly bind and are not easily released;

[0033] (3) The buffer salt, initiator, potassium hydroxide and reducing agent in the present invention can introduce ammonium ions and potassium ions, which can help prevent swelling;

[0034] (4) The sulfonic acid anions and sulfate anions in the clay stabilizer of the present invention are hydrophilic groups. After combining with the clay, the outer side is a hydrophobic polymerized alkyl chain, which is a lipophilic structure and can prevent water molecules from contacting with the clay to wet the clay and inhibit expansion;

[0035] (5) The clay stabilizer polymer of the present invention has a large amount of positive charge and can simultaneously form multi-point adsorption with multiple clay particles. After adsorption, a layer of organic cationic polymer adsorption protective film is formed on the surface of the clay particles to protect the clay particles and prevent the hydration, expansion, dispersion and migration of the clay particles.

[0036] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0037] (1) The clay stabilizer for fracturing and acidizing of the present invention has the characteristics of wide sources of raw materials and simple synthesis and preparation processes;

[0038] (2) The clay stabilizer for fracturing and acidizing of the present invention has the advantage of a high anti-swelling rate. When the concentration is 2wt%, the anti-swelling rate reaches more than 96%;

[0039] (3) The clay stabilizer for fracturing and acidizing of the present invention has the advantage of being resistant to water washing. When the concentration is 2 wt%, the anti-swelling rate after water washing can reach more than 92%. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with specific embodiments:

[0041] Example 1

[0042] (1) Add 0.2 mol of trimethylolpropane allyl ether and 6.96 g of distilled water to a four-necked flask, slowly add 0.36 mol of aminosulfonic acid in batches, cool in a water bath, and continue to keep warm for 30 minutes after the addition of aminosulfonic acid. The reaction temperature is controlled not to exceed 60° C. during the whole process, and the pH is adjusted to 7-8 with potassium hydroxide solution;

[0043] (2) In a four-necked flask, 139.2 g of distilled water, 0.04 mol of 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, and 3.48 g of sodium dihydrogen phosphate were added in sequence and stirred evenly;

[0044] (3) adding an aqueous solution containing 0.348 g of sodium persulfate to the above four-necked flask, the temperature of the reaction automatically rises, and the reaction is continued for 60 min after the temperature stops rising. The temperature is raised to 63° C. and kept warm for 30 min. An aqueous solution containing 0.348 g of sodium sulfite is added to terminate the reaction to obtain a clay stabilizer solution;

[0045] (4) drying and granulating the clay stabilizer solution to obtain a clay stabilizer product.

[0046] Example 2

[0047] (1) Add 0.2 mol of trimethylolpropane allyl ether and 3.48 g of distilled water to a four-necked flask, slowly add 0.4 mol of aminosulfonic acid in batches, cool in a water bath, and continue to keep warm for 60 minutes after the addition of aminosulfonic acid. The reaction temperature is controlled not to exceed 60° C. during the whole process, and the pH is adjusted to 7-8 with potassium hydroxide solution;

[0048] (2) In a four-necked flask, 158.8 g of distilled water, 0.08 mol of 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, and 4.99 g of disodium hydrogen phosphate were added in sequence and stirred evenly;

[0049] (3) adding an aqueous solution containing 0.457 g of sodium persulfate to the above four-necked flask, the temperature of the reaction automatically rises, and the reaction is continued for 30 min after the temperature stops rising. The temperature is raised to 62° C. and kept warm for 60 min. An aqueous solution containing 0.46 g of potassium sulfite is added to terminate the reaction to obtain a clay stabilizer solution;

[0050] (4) drying and granulating the clay stabilizer solution to obtain a clay stabilizer product.

[0051] Example 3

[0052] (1) Add 0.2 mol of trimethylolpropane allyl ether and 6.33 g of distilled water to a four-necked flask, slowly add 0.42 mol of aminosulfonic acid in batches, cool in a water bath, and continue to keep warm for 45 minutes after the addition of aminosulfonic acid. The reaction temperature is controlled not to exceed 60° C. during the whole process, and the pH is adjusted to 7-8 with potassium hydroxide solution;

[0053] (2) Add 208.8 g of distilled water, 0.2 mol of 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, and 6.96 g of potassium dihydrogen phosphate into a four-necked flask in sequence and stir evenly;

[0054] (3) adding an aqueous solution containing 1.74 g of sodium persulfate to the above four-necked flask, the reaction temperature automatically rises, and the temperature stops rising, and the reaction is continued for 40 min. The temperature is raised to 64° C. and kept warm for 60 min. An aqueous solution containing 1.73 g of sodium sulfite is added to terminate the reaction to obtain a clay stabilizer solution;

[0055] (4) drying and granulating the clay stabilizer solution to obtain a clay stabilizer product.

[0056] Example 4

[0057] (1) Add 0.2 mol of trimethylolpropane allyl ether and 5.94 g of distilled water to a four-necked flask, slowly add 0.44 mol of aminosulfonic acid in batches, cool in a water bath, and continue to keep warm for 40 minutes after the addition of aminosulfonic acid. The reaction temperature is controlled not to exceed 60° C. during the whole process, and the pH is adjusted to 7-8 with potassium hydroxide solution;

[0058] (2) 194.4 g of distilled water, 0.18 mol of 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, and 6.14 g of dipotassium hydrogen phosphate were added to a four-necked flask in sequence and stirred evenly;

[0059] (3) adding an aqueous solution containing 1.33 g of sodium persulfate to the above four-necked flask, the temperature of the reaction automatically rises, and the reaction is continued for 50 min after the temperature stops rising. The temperature is raised to 61° C. and kept warm for 30 min. An aqueous solution containing 1.29 g of sodium bisulfite is added to terminate the reaction to obtain a clay stabilizer solution;

[0060] (4) drying and granulating the clay stabilizer solution to obtain a clay stabilizer product.

[0061] Example 5

[0062] (1) Add 0.2 mol of trimethylolpropane allyl ether and 5.12 g of distilled water to a four-necked flask, slowly add 0.46 mol of aminosulfonic acid in batches, cool in a water bath, and continue to keep warm for 50 minutes after the addition of aminosulfonic acid. The reaction temperature is controlled not to exceed 60° C. during the whole process, and the pH is adjusted to 7-8 with potassium hydroxide solution;

[0063] (2) 161.3 g of distilled water, 0.1 mol of 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, and 5.33 g of diammonium phosphate were added to a four-necked flask in sequence and stirred evenly;

[0064] (3) adding an aqueous solution containing 0.97 g of potassium persulfate to the above four-necked flask, the temperature of the reaction automatically rises, and the reaction is continued for 40 min after the temperature stops rising. The temperature is raised to 63° C. and kept warm for 40 min. An aqueous solution containing 0.99 g of sodium bisulfite is added to terminate the reaction to obtain a clay stabilizer solution;

[0065] (4) drying and granulating the clay stabilizer solution to obtain a clay stabilizer product.

[0066] Example 6

[0067] (1) Add 0.2 mol of trimethylolpropane allyl ether and 4.45 g of distilled water to a four-necked flask, slowly add 0.48 mol of aminosulfonic acid in batches, cool in a water bath, and continue to keep warm for 35 minutes after the addition of aminosulfonic acid. The reaction temperature is controlled not to exceed 60° C. during the whole process, and the pH is adjusted to 7-8 with potassium hydroxide solution;

[0068] (2) 188.6 g of distilled water, 0.13 mol of 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, and 5.48 g of diammonium hydrogen phosphate were added to a four-necked flask in sequence and stirred evenly;

[0069] (3) adding an aqueous solution containing 0.76 g of potassium persulfate to the above four-necked flask, the temperature of the reaction automatically rises, and the reaction is continued for 30 min after the temperature stops rising. The temperature is raised to 62° C. and kept warm for 50 min. An aqueous solution containing 0.81 g of potassium sulfite is added to terminate the reaction to obtain a clay stabilizer solution;

[0070] (4) drying and granulating the clay stabilizer solution to obtain a clay stabilizer product.

[0071] Example 7

[0072] (1) Add 0.2 mol of trimethylolpropane allyl ether and 5.22 g of distilled water into a four-necked flask, slowly add 0.5 mol of aminosulfonic acid in batches, cool in a water bath, and continue to keep warm for 40 minutes after the addition of aminosulfonic acid. The reaction temperature is controlled not to exceed 60° C. during the whole process, and the pH is adjusted to 7-8 with potassium hydroxide solution;

[0073] (2) 174 g of distilled water, 0.2 mol of 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, and 6.2 g of diammonium hydrogen phosphate were added to a four-necked flask in sequence and stirred evenly;

[0074] (3) adding an aqueous solution containing 1.27 g of ammonium persulfate to the above four-necked flask, the reaction temperature rises automatically, and the temperature stops rising, and the reaction is continued for 60 min, and the temperature is raised to 60° C. and kept warm for 30-60 min, and an aqueous solution containing 1.33 g of potassium bisulfite is added to terminate the reaction to obtain a clay stabilizer solution;

[0075] (4) drying and granulating the clay stabilizer solution to obtain a clay stabilizer product.

[0076] Example 8

[0077] (1) Add 0.2 mol of trimethylolpropane allyl ether and 4.8 g of distilled water to a four-necked flask, slowly add 0.5 mol of aminosulfonic acid in batches, cool in a water bath, and continue to keep warm for 50 minutes after the addition of aminosulfonic acid. The reaction temperature is controlled not to exceed 60° C. during the whole process, and the pH is adjusted to 7-8 with potassium hydroxide solution;

[0078] (2) 178.6 g of distilled water, 0.16 mol of 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, and 6.3 g of dipotassium hydrogen phosphate were added to a four-necked flask in sequence and stirred evenly;

[0079] (3) adding an aqueous solution containing 1.43 g of ammonium persulfate to the above four-necked flask, the temperature of the reaction automatically rises, and the reaction is continued for 50 min after the temperature stops rising. The temperature is raised to 65° C. and kept warm for 45 min. An aqueous solution containing 1.46 g of potassium bisulfite is added to terminate the reaction to obtain a clay stabilizer solution;

[0080] (4) drying and granulating the clay stabilizer solution to obtain a clay stabilizer product.

[0081] Example 9 Evaluation of the Anti-swelling Capacity of Clay Stabilizer

[0082] Refer to method 7.5 in SY / T5971-2016 "Performance Evaluation Method of Clay Stabilizer for Oil and Gas Field Fracturing Acidification and Water Injection", and use the centrifugal method to test the anti-swelling rate.

[0083] The concentration was 2 wt %, and the experimental water was taken from the polymerized water used for fracturing at a water injection station in Shengli Oilfield.

[0084] A comparative experiment was conducted using the clay stabilizer HJZ-100 produced by Kaifeng Hengju Biotechnology Co., Ltd.

[0085] The test results of the anti-swelling rate of the clay stabilizer are shown in Table 1.

[0086] It can be seen from Table 1 that the anti-swelling rate of the clay stabilizer of the present invention (Examples 1-8) is greater than 96% when the usage concentration is 2wt%, among which the highest anti-swelling rate of Example 8 reaches 99%, while the anti-swelling rate of the clay stabilizer HJZ-100 of Kaifeng Hengju Biotechnology Co., Ltd. in the comparative example is 90.2%, which is significantly lower than that of the present invention. The clay stabilizer of the present invention has a good anti-swelling effect.

[0087] Example 10 Evaluation of the water washability of clay stabilizers

[0088] Refer to the implementation of method 7.4 in SY / T5971-2016 "Performance Evaluation Method of Clay Stabilizer for Oil and Gas Field Fracturing Acidification and Water Injection".

[0089] The water used in the experiment was taken from the prepared water used for fracturing at a water injection station in Shengli Oilfield.

[0090] The concentration was 2 wt %, and a comparative experiment was conducted using clay stabilizer HJZ-100 produced by Kaifeng Hengju Biotechnology Co., Ltd.

[0091] The test results of the water washability of the clay stabilizer are shown in Table 1.

[0092] Table 1 Anti-swelling rate and water washability test results

[0093] Clay stabilizer Anti-swelling rate, % Washing anti-swelling rate, % Example 1 96.2 93 Example 2 97 93.7 Example 3 97.8 94.5 Example 4 97.3 94 Example 5 98.2 94.8 Example 6 99 95.2 Example 7 98.5 95 Example 8 99 95.4 HJZ-100 90.2 83.6

[0094] It can be seen from Table 1 that the water washing anti-swelling rate of the clay stabilizer of the present invention (Examples 1-8) is greater than 92% when the use concentration is 2wt%, among which the highest water washing anti-swelling rate of Example 8 reaches 95.4%, while the water washing anti-swelling rate of the clay stabilizer HJZ-100 of the comparative example Kaifeng Hengju Biotechnology Co., Ltd. is 83.6%, which is significantly lower than that of the present invention. The clay stabilizer of the present invention has a strong water washing resistance.

[0095] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing a clay stabilizer for fracturing and acidizing, characterized in that: The specific steps of the preparation method are as follows: (1) Add trimethylolpropane allyl ether and distilled water to a four-necked flask, slowly add sulfamic acid in batches, cool in a water bath, and continue to keep warm for 30-60 minutes after adding sulfamic acid. The reaction temperature is controlled not to exceed 60° C. during the whole process, and the pH is adjusted to 7-8 with potassium hydroxide solution; (2) Add distilled water, 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, and buffer salt to a four-necked flask in sequence and stir evenly; (3) adding an initiator aqueous solution dropwise to the above four-necked flask, the reaction temperature rises automatically, and the reaction is continued for 30-60 minutes after the temperature stops rising, and the temperature is raised to 60-65° C. and kept warm for 30-60 minutes, and a reducing agent aqueous solution is added to terminate the reaction to obtain a clay stabilizer solution; (4) drying and granulating the clay stabilizer solution to obtain a clay stabilizer product; Based on 1 mole of trimethylolpropane allyl ether, the amounts of aminosulfonic acid and 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt are 1.8-2.5 mole parts and 0.2-1 mole parts respectively.

2. The method for preparing a clay stabilizer for fracturing acidification according to claim 1, characterized in that: The weight ratio of distilled water to trimethylolpropane allyl ether in step (1) is 0.1-0.2:

1.

3. The method for preparing a clay stabilizer for fracturing acidification according to claim 1, characterized in that: The weight ratio of distilled water to trimethylolpropane allyl ether in step (2) is 4-6:

1.

4. The method for preparing a clay stabilizer for fracturing and acidizing according to claim 1, characterized in that: The buffer salt in step (2) is one of sodium dihydrogen phosphate, potassium dihydrogen phosphate, ammonium dihydrogen phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, and diammonium hydrogen phosphate, and the weight ratio of the buffer salt to trimethylolpropane allyl ether is 0.1-0.2:

1.

5. The method for preparing a clay stabilizer for fracturing acidification according to claim 4, characterized in that: The buffer salt is one of potassium dihydrogen phosphate, ammonium dihydrogen phosphate, dipotassium hydrogen phosphate and diammonium hydrogen phosphate.

6. The method for preparing a clay stabilizer for fracturing and acidizing according to claim 1, characterized in that: The initiator in step (3) is one of potassium persulfate, ammonium persulfate and sodium persulfate, and the weight ratio of the initiator to trimethylolpropane allyl ether is 0.01-0.05:

1.

7. The method for preparing a clay stabilizer for fracturing and acidizing according to claim 1, characterized in that: The reducing agent in step (3) is one of sodium sulfite, potassium sulfite, sodium bisulfite and potassium bisulfite, and the weight ratio of the reducing agent to trimethylolpropane allyl ether is 0.01-0.05:

1.

8. A clay stabilizer for fracturing and acidizing, characterized in that: The molecular structure of the clay stabilizer is as follows: Wherein, m = 1000-10000; n＝200-10000。 9. The clay stabilizer for fracturing and acidizing according to claim 8, characterized in that: The viscosity average molecular weight of the clay stabilizer is 200,000-2,000,000.

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