A water-resistant clay stabilizer

Abstract

The invention relates to the technical field of stabilizers, and relates to a water-washable clay stabilizer. The stabilizer comprises the following components in parts by weight: 0.1-0.5 parts by weight of a composite stabilizer, 0.5-1.5 parts by weight of polydimethyldiallylammonium chloride, 1-5 parts by weight of hexadecyltrimethylammonium bromide, 3-5 parts by weight of potassium chloride, 2-4 parts by weight of ethylene glycol, 0.2-0.4 parts by weight of xanthan gum, and 0.05-0.09 parts by weight of a sodium hydroxide pH regulator; wherein the composite stabilizer is obtained by mixing hexamethylenediaminetetramethylenephosphoric acid and oleoyl chloride in a molar ratio of 1:1.1-1.3, and the composite stabilizer is used to introduce hydrophobic oleoyl chloride into the hexamethylenediaminetetramethylenephosphoric acid, so that the composite stabilizer can not only form a stable complex with metal ions on the surface of clay, but also form a dense covering layer on the surface of clay particles through hydrophobic groups, thereby significantly improving the water-washing resistance of the clay stabilizer, reducing the hydration expansion phenomenon of the clay particles, and improving the stability of the composite stabilizer under different pH conditions.

Description

Technical Field

[0001] The invention relates to the technical field of stabilizers, in particular to a water-resistant clay stabilizer. Background Art

[0002] Clay stabilizer is a chemical additive widely used in fields such as oil extraction, drilling, geological exploration and civil engineering. Its main function is to improve and control the dispersion, expansion, migration and deposition behavior of clay particles, thereby improving the efficiency, safety and economy of engineering operations. Clay minerals, such as montmorillonite, illite and kaolinite, are easy to absorb water, swell and disperse in water environments due to their unique layered structure and surface properties. This will not only reduce the sand carrying capacity of the drilling fluid and increase the viscosity of the mud, but may also lead to serious problems such as well wall instability and formation collapse. Therefore, the research and development and application of clay stabilizers are particularly important.

[0003] However, traditional clay stabilizers are easily washed away by water under water flow or high water pressure conditions, and have poor water washability, resulting in a decrease in the stabilization effect. This is particularly evident in operations such as fracturing and water injection in oil production, and can easily cause problems such as reservoir pollution and well wall instability. In view of this, a water-washable clay stabilizer is provided. Summary of the invention

[0004] The object of the present invention is to provide a water-resistant clay stabilizer to solve the problem of poor water-resistant performance in the preparation process of the water-resistant clay stabilizer mentioned in the above background technology.

[0005] To achieve the above object, the present invention provides a water-resistant clay stabilizer, comprising the following components in parts by weight: 0.1-0.5 parts by weight of a composite stabilizer, 0.5-1.5 parts by weight of polydimethyldiallylammonium chloride, 1-5 parts by weight of hexadecyltrimethylammonium bromide, 3-5 parts by weight of potassium chloride, 2-4 parts by weight of ethylene glycol, 0.2-0.4 parts by weight of xanthan gum, and 0.05-0.09 parts by weight of a sodium hydroxide pH regulator;

[0006] The composite stabilizer is obtained by mixing hexamethylenediaminetetramethylenephosphoric acid and oleoyl chloride in a molar ratio of 1:1.1-1.3.

[0007] As a further improvement of the technical solution, the specific preparation method of the composite stabilizer is as follows:

[0008] Add hexamethylenediaminetetramethylenephosphoric acid to a three-necked flask containing anhydrous dichloromethane to fully dissolve it, then add 4-dimethylaminopyridine to catalyze the reaction, and add triethylamine to adjust the reaction pH. Under stirring conditions, use a dropping funnel to drop oleoyl chloride drop by drop, and continue to drop for 15-20 minutes. Continue to stir the reaction solution, and control the water bath heating at 30-35°C. After the addition of oleoyl chloride is completed, gradually increase the reaction temperature to 50-55°C, maintain this temperature for 4-6 hours, and continue to stir during the period. After the reaction is completed, cool to room temperature, stand for stratification, remove the lower layer of liquid, wash the upper layer of liquid with anhydrous ethanol, and dry it in a vacuum drying oven at 50-60°C to obtain a composite stabilizer.

[0009] Since the surface of clay particles contains a large amount of exchangeable metal ions, such as calcium (Ca²⁺), magnesium (Mg²⁺), sodium (Na⁺), etc., the presence of these metal ions on the surface of clay particles has a great influence on the hydration and expansion behavior of clay. When these metal ions are hydrated, the distance between particles increases, causing the clay particles to aggregate and expand.

[0010] Hexamethylenediaminetetramethylenephosphonic acid (HEDP) contains multiple phosphate groups (-PO3H2), which can be partially dissociated into negatively charged forms (-PO4³⁻) in aqueous solution. This structure enables organic phosphates to bind to metal ions on the surface of clay through coordination bonds to form stable complexes. Once metal ions form complexes with organic phosphates, they become inactive and cannot easily bind to water molecules or participate in other chemical reactions. This means that metal ions that could originally promote the attraction between clay particles are "captured", reducing their activity on the surface of clay particles, weakening the interaction between clay particles, and making it difficult for clay particles to aggregate. Therefore, the hydration and swelling of clay particles are reduced, achieving the effect of stabilizing clay. However, the chelating ability and stability of organic phosphorus compounds are closely related to pH value. Therefore, hexamethylenediaminetetramethylenephosphonic acid is chemically modified by introducing oleoyl chloride containing hydrophobic groups.

[0011] Since the hydrophobic groups tend to avoid the water environment, they can interact with the hydrophobic areas on the surface of the clay particles. This interaction increases the binding force between the molecules and the clay surface, making the hexanedettramethylenephosphonic acid more firmly adsorbed on the surface of the clay particles. In this way, the hexanedettramethylenephosphonic acid molecules can not only rely on the chelating ability of the phosphate group, but also rely on the physical adsorption ability of the hydrophobic group. Even when the pH changes, they can maintain a high stability, indirectly overcoming the stability problem of hexanedettramethylenephosphonic acid in different environments.

[0012] In an aqueous environment, hydrophobic groups tend to gather together or combine with the hydrophobic areas on the surface of clay particles to form a hydrophobic area. The intermolecular force in this hydrophobic area is strong, making it difficult for the hexamethylenediaminetetramethylenephosphonic acid molecules to be washed away by water, thereby improving the water resistance. At the same time, the hydrophobic groups are more likely to form a dense covering layer on the surface of clay particles, occupying the space on the surface of clay particles, reducing the exposed area of ​​clay particles, forming a physical barrier, and reducing the possibility of hydration and expansion of clay particles.

[0013] HEDP molecules contain multiple phosphate groups, which have strong electrophilicity and coordination ability. Oleoyl chloride, as a long-chain fatty acid derivative, contains an oleoyl group and a chlorine atom, which is easy to undergo nucleophilic substitution reactions. The phosphate groups in HEDP have abundant lone pairs of electrons and show strong nucleophilicity. When they encounter the carbon-chlorine bond in oleoyl chloride, nucleophilic attack occurs, causing the chlorine to leave and form a new ester bond, which introduces a hydrophobic group into the HEDP molecule.

[0014] As a further improvement of the technical solution, the mass ratio of dichloromethane to hexamethylenediaminetetramethylenephosphoric acid is 15-20:1.

[0015] As a further improvement of the technical solution, the added amount of 4-dimethylaminopyridine is 1-3% of the mass of hexamethylenediaminetetramethylenephosphoric acid.

[0016] As a further improvement of the technical solution, the mass ratio of the added amount of triethylamine to oleoyl chloride is 0.6-0.8:1.

[0017] As a further improvement of the technical solution, the triethylamine is used to adjust the pH value of the solution to 7-8.

[0018] As a further improvement of the technical solution, the dripping rate of the dropping funnel is controlled at 1-3 drops per minute.

[0019] As a further improvement of the technical solution, the specific preparation method of the water-resistant clay stabilizer is as follows:

[0020] The composite stabilizer and ethylene glycol are first mixed to form a premixed liquid, potassium chloride is added to deionized water, and the mixture is fully stirred with a stirrer until it is completely dissolved, and the mixture is heated to 30-40°C, and polydimethyldiallylammonium chloride, hexadecyltrimethylammonium bromide, xanthan gum and the remaining ethylene glycol are sequentially added, and the mixture is fully stirred and mixed evenly. Each time a raw material is added, the mixture needs to be stirred for 30-40 minutes before the next raw material is added, and the premixed liquid is added to the mixed solution, and the mixture is continuously stirred and mixed evenly. Finally, a sodium hydroxide pH regulator is added to adjust the pH value of the mixed solution to obtain a water-washable clay stabilizer.

[0021] As a further improvement of the technical solution, the volume of ethylene glycol in the premixed liquid accounts for 11-15% of the total volume of the premixed liquid.

[0022] As a further improvement of the technical solution, the sodium hydroxide pH regulator adjusts the pH value of the mixed solution to 7-9.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] In the water-washable clay stabilizer, a composite stabilizer is used to introduce hydrophobic oleoyl chloride onto hexamethylenediaminetetramethylenephosphonic acid, which can not only form a stable complex with metal ions on the clay surface, reduce active metal ions on the clay surface, and thus weaken the interaction between clay particles, but also form a dense covering layer on the surface of clay particles through hydrophobic groups, reduce the exposed area of ​​clay particles, form a physical barrier, significantly improve the stability of clay in water environment, and reduce the hydration expansion phenomenon of clay particles. In addition, the introduced hydrophobic groups can further alleviate the problem that the chelation of hexamethylenediaminetetramethylenephosphonic acid with metal ions is easily affected by pH value, so that the stability of the composite stabilizer under different pH conditions is significantly improved, and its chelation ability and adsorption performance can be maintained in a wider pH range, greatly improving the water-washable performance of the clay stabilizer. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] A water-resistant clay stabilizer comprises the following components in parts by weight: 0.1-0.5 parts by weight of a composite stabilizer, 0.5-1.5 parts by weight of polydimethyldiallylammonium chloride, 1-5 parts by weight of hexadecyltrimethylammonium bromide, 3-5 parts by weight of potassium chloride, 2-4 parts by weight of ethylene glycol, 0.2-0.4 parts by weight of xanthan gum, and 0.05-0.09 parts by weight of a sodium hydroxide pH regulator; wherein the composite stabilizer is obtained by mixing hexamethylenediaminetetramethylenephosphoric acid and oleoyl chloride in a molar ratio of 1:1.1-1.3.

[0027] Example 1: In this example, the specific preparation method of the water-resistant clay stabilizer is as follows:

[0028] Prepare the following components: 0.5 parts by weight of composite stabilizer, 1.5 parts by weight of polydimethyldiallylammonium chloride, 5 parts by weight of hexadecyltrimethylammonium bromide, 5 parts by weight of potassium chloride, 4 parts by weight of ethylene glycol, 0.4 parts by weight of xanthan gum, and 0.09 parts by weight of sodium hydroxide pH adjuster;

[0029] The composite stabilizer is obtained by mixing hexamethylenediaminetetramethylenephosphoric acid and oleoyl chloride in a molar ratio of 1:1.1; the mass ratio of dichloromethane to hexamethylenediaminetetramethylenephosphoric acid is 20:1; the amount of 4-dimethylaminopyridine added is 3% of the mass of hexamethylenediaminetetramethylenephosphoric acid; the mass ratio of triethylamine added to oleoyl chloride is 0.8:1; the volume of ethylene glycol in the premixed liquid accounts for 15% of the total volume of the premixed liquid;

[0030] Add hexamethylenediaminetetramethylenephosphoric acid to a three-necked flask containing anhydrous dichloromethane to fully dissolve it, then add 4-dimethylaminopyridine to catalyze the reaction, and add triethylamine to adjust the reaction pH to 8. Under stirring conditions, use a dropping funnel to drop oleoyl chloride drop by drop, and the dropping rate is controlled at 1 drop per minute. Continue to drop for 15 minutes, continue to stir the reaction solution, and control the water bath heating at 30°C. After the addition of oleoyl chloride is completed, gradually increase the reaction temperature to 50°C, maintain this temperature for 6 hours, and continue to stir during the period. After the reaction is completed, cool to room temperature, stand for stratification, remove the lower layer of liquid, wash the upper layer of liquid with anhydrous ethanol, and dry it in a vacuum drying oven at 60°C to obtain a composite stabilizer;

[0031] The composite stabilizer is first mixed with ethylene glycol to form a premixed liquid, potassium chloride is added to deionized water, and the mixture is fully stirred with a stirrer until it is completely dissolved, and the mixture is heated to 40°C, and polydimethyldiallylammonium chloride, hexadecyltrimethylammonium bromide, xanthan gum and the remaining ethylene glycol are added in sequence, and the mixture is fully stirred and mixed evenly. Each time a raw material is added, the mixture is stirred for 30 minutes before the next raw material is added, and the premixed liquid is added to the mixed solution, and the mixture is continuously stirred and mixed evenly. Finally, sodium hydroxide pH regulator is added to adjust the pH value of the mixed solution to 7, and a water-resistant clay stabilizer is obtained.

[0032] Example 2: In this example, the specific preparation method of the water-resistant clay stabilizer is as follows:

[0033] Prepare the following components: 0.5 parts by weight of composite stabilizer, 1.5 parts by weight of polydimethyldiallylammonium chloride, 5 parts by weight of hexadecyltrimethylammonium bromide, 5 parts by weight of potassium chloride, 4 parts by weight of ethylene glycol, 0.4 parts by weight of xanthan gum, and 0.09 parts by weight of sodium hydroxide pH adjuster;

[0034] The composite stabilizer is obtained by mixing hexamethylenediaminetetramethylenephosphoric acid and oleoyl chloride in a molar ratio of 1:1.2; the mass ratio of dichloromethane to hexamethylenediaminetetramethylenephosphoric acid is 20:1; the addition amount of 4-dimethylaminopyridine is 3% of the mass of hexamethylenediaminetetramethylenephosphoric acid; the mass ratio of triethylamine to oleoyl chloride is 0.8:1; the volume of ethylene glycol in the premixed liquid accounts for 15% of the total volume of the premixed liquid;

[0035] Add hexamethylenediaminetetramethylenephosphoric acid to a three-necked flask containing anhydrous dichloromethane to fully dissolve it, then add 4-dimethylaminopyridine to catalyze the reaction, and add triethylamine to adjust the reaction pH to 8. Under stirring conditions, use a dropping funnel to drop oleoyl chloride drop by drop, and the dropping rate is controlled at 1 drop per minute. Continue to drop for 15 minutes, continue to stir the reaction solution, and control the water bath heating at 30°C. After the addition of oleoyl chloride is completed, gradually increase the reaction temperature to 50°C, maintain this temperature for 6 hours, and continue to stir during the period. After the reaction is completed, cool to room temperature, stand for stratification, remove the lower layer of liquid, wash the upper layer of liquid with anhydrous ethanol, and dry it in a vacuum drying oven at 60°C to obtain a composite stabilizer;

[0036] The composite stabilizer is first mixed with ethylene glycol to form a premixed liquid, potassium chloride is added to deionized water, and the mixture is fully stirred with a stirrer until it is completely dissolved, and the mixture is heated to 40°C, and polydimethyldiallylammonium chloride, hexadecyltrimethylammonium bromide, xanthan gum and the remaining ethylene glycol are added in sequence, and the mixture is fully stirred and mixed evenly. Each time a raw material is added, the mixture is stirred for 30 minutes before the next raw material is added, and the premixed liquid is added to the mixed solution, and the mixture is continuously stirred and mixed evenly. Finally, sodium hydroxide pH regulator is added to adjust the pH value of the mixed solution to 7, and a water-resistant clay stabilizer is obtained.

[0037] Example 3: In this example, the specific preparation method of the water-resistant clay stabilizer is as follows:

[0038] Prepare the following components: 0.5 parts by weight of composite stabilizer, 1.5 parts by weight of polydimethyldiallylammonium chloride, 5 parts by weight of hexadecyltrimethylammonium bromide, 5 parts by weight of potassium chloride, 4 parts by weight of ethylene glycol, 0.4 parts by weight of xanthan gum, and 0.09 parts by weight of sodium hydroxide pH adjuster;

[0039] The composite stabilizer is obtained by mixing hexamethylenediaminetetramethylenephosphoric acid and oleoyl chloride in a molar ratio of 1:1.3; the mass ratio of dichloromethane to hexamethylenediaminetetramethylenephosphoric acid is 20:1; the amount of 4-dimethylaminopyridine added is 3% of the mass of hexamethylenediaminetetramethylenephosphoric acid; the mass ratio of triethylamine added to oleoyl chloride is 0.8:1; the volume of ethylene glycol in the premixed liquid accounts for 15% of the total volume of the premixed liquid;

[0040] Add hexamethylenediaminetetramethylenephosphoric acid to a three-necked flask containing anhydrous dichloromethane to fully dissolve it, then add 4-dimethylaminopyridine to catalyze the reaction, and add triethylamine to adjust the reaction pH to 8. Under stirring conditions, use a dropping funnel to drop oleoyl chloride drop by drop, and the dropping rate is controlled at 1 drop per minute. Continue to drop for 15 minutes, continue to stir the reaction solution, and control the water bath heating at 30°C. After the addition of oleoyl chloride is completed, gradually increase the reaction temperature to 50°C, maintain this temperature for 6 hours, and continue to stir during the period. After the reaction is completed, cool to room temperature, stand for stratification, remove the lower layer of liquid, wash the upper layer of liquid with anhydrous ethanol, and dry it in a vacuum drying oven at 60°C to obtain a composite stabilizer;

[0041] The composite stabilizer is first mixed with ethylene glycol to form a premixed liquid, potassium chloride is added to deionized water, and the mixture is fully stirred with a stirrer until it is completely dissolved, and the mixture is heated to 40°C, and polydimethyldiallylammonium chloride, hexadecyltrimethylammonium bromide, xanthan gum and the remaining ethylene glycol are added in sequence, and the mixture is fully stirred and mixed evenly. Each time a raw material is added, the mixture is stirred for 30 minutes before the next raw material is added, and the premixed liquid is added to the mixed solution, and the mixture is continuously stirred and mixed evenly. Finally, sodium hydroxide pH regulator is added to adjust the pH value of the mixed solution to 7, and a water-resistant clay stabilizer is obtained.

[0042] Example 4: In this example, the specific preparation method of the water-resistant clay stabilizer is as follows:

[0043] Prepare the following components: 0.5 parts by weight of composite stabilizer, 0.5 parts by weight of polydimethyldiallylammonium chloride, 1 part by weight of hexadecyltrimethylammonium bromide, 3 parts by weight of potassium chloride, 2 parts by weight of ethylene glycol, 0.2 parts by weight of xanthan gum, and 0.05 parts by weight of sodium hydroxide pH adjuster;

[0044] The composite stabilizer is obtained by mixing hexamethylenediaminetetramethylenephosphoric acid and oleoyl chloride in a molar ratio of 1:1.3; the mass ratio of dichloromethane to hexamethylenediaminetetramethylenephosphoric acid is 15:1; the addition amount of 4-dimethylaminopyridine is 1% of the mass of hexamethylenediaminetetramethylenephosphoric acid; the mass ratio of triethylamine to oleoyl chloride is 0.6:1; the volume of ethylene glycol in the premixed liquid accounts for 11% of the total volume of the premixed liquid;

[0045] Add hexamethylenediaminetetramethylenephosphoric acid to a three-necked flask containing anhydrous dichloromethane to fully dissolve it, then add 4-dimethylaminopyridine to catalyze the reaction, and add triethylamine to adjust the reaction pH to 8. Under stirring conditions, use a dropping funnel to drop oleoyl chloride drop by drop, and the dropping rate is controlled at 1 drop per minute. Continue to drop for 15 minutes, continue to stir the reaction solution, and control the water bath heating at 30°C. After the addition of oleoyl chloride is completed, gradually increase the reaction temperature to 50°C, maintain this temperature for 6 hours, and continue to stir during the period. After the reaction is completed, cool to room temperature, stand for stratification, remove the lower layer of liquid, wash the upper layer of liquid with anhydrous ethanol, and dry it in a vacuum drying oven at 60°C to obtain a composite stabilizer;

[0046] The composite stabilizer is first mixed with ethylene glycol to form a premixed liquid, potassium chloride is added to deionized water, and the mixture is fully stirred with a stirrer until it is completely dissolved, and the mixture is heated to 40°C, and polydimethyldiallylammonium chloride, hexadecyltrimethylammonium bromide, xanthan gum and the remaining ethylene glycol are added in sequence, and the mixture is fully stirred and mixed evenly. Each time a raw material is added, the mixture is stirred for 30 minutes before the next raw material is added, and the premixed liquid is added to the mixed solution, and the mixture is continuously stirred and mixed evenly. Finally, sodium hydroxide pH regulator is added to adjust the pH value of the mixed solution to 7, and a water-resistant clay stabilizer is obtained.

[0047] Example 5: In this example, the specific preparation method of the water-resistant clay stabilizer is as follows:

[0048] Prepare the following components: 0.1 parts by weight of composite stabilizer, 1.5 parts by weight of polydimethyldiallylammonium chloride, 5 parts by weight of hexadecyltrimethylammonium bromide, 5 parts by weight of potassium chloride, 4 parts by weight of ethylene glycol, 0.4 parts by weight of xanthan gum, and 0.09 parts by weight of sodium hydroxide pH adjuster;

[0049] The composite stabilizer is obtained by mixing hexamethylenediaminetetramethylenephosphoric acid and oleoyl chloride in a molar ratio of 1:1.3; the mass ratio of dichloromethane to hexamethylenediaminetetramethylenephosphoric acid is 20:1; the amount of 4-dimethylaminopyridine added is 3% of the mass of hexamethylenediaminetetramethylenephosphoric acid; the mass ratio of triethylamine added to oleoyl chloride is 0.8:1; the volume of ethylene glycol in the premixed liquid accounts for 15% of the total volume of the premixed liquid;

[0050] Add hexamethylenediaminetetramethylenephosphoric acid to a three-necked flask containing anhydrous dichloromethane to fully dissolve it, then add 4-dimethylaminopyridine to catalyze the reaction, and add triethylamine to adjust the reaction pH to 8. Under stirring conditions, use a dropping funnel to drop oleoyl chloride drop by drop, and the dropping rate is controlled at 1 drop per minute. Continue to drop for 15 minutes, continue to stir the reaction solution, and control the water bath heating at 30°C. After the addition of oleoyl chloride is completed, gradually increase the reaction temperature to 50°C, maintain this temperature for 6 hours, and continue to stir during the period. After the reaction is completed, cool to room temperature, stand for stratification, remove the lower layer of liquid, wash the upper layer of liquid with anhydrous ethanol, and dry it in a vacuum drying oven at 60°C to obtain a composite stabilizer;

[0051] The composite stabilizer is first mixed with ethylene glycol to form a premixed liquid, potassium chloride is added to deionized water, and the mixture is fully stirred with a stirrer until it is completely dissolved, and the mixture is heated to 40°C, and polydimethyldiallylammonium chloride, hexadecyltrimethylammonium bromide, xanthan gum and the remaining ethylene glycol are added in sequence, and the mixture is fully stirred and mixed evenly. Each time a raw material is added, the mixture is stirred for 30 minutes before the next raw material is added, and the premixed liquid is added to the mixed solution, and the mixture is continuously stirred and mixed evenly. Finally, sodium hydroxide pH regulator is added to adjust the pH value of the mixed solution to 7, and a water-resistant clay stabilizer is obtained.

[0052] Example 6: In this example, the specific preparation method of the water-resistant clay stabilizer is as follows:

[0053] Prepare the following components: 0.3 parts by weight of composite stabilizer, 1.5 parts by weight of polydimethyldiallylammonium chloride, 5 parts by weight of hexadecyltrimethylammonium bromide, 5 parts by weight of potassium chloride, 4 parts by weight of ethylene glycol, 0.4 parts by weight of xanthan gum, and 0.09 parts by weight of sodium hydroxide pH adjuster;

[0054] The composite stabilizer is obtained by mixing hexamethylenediaminetetramethylenephosphoric acid and oleoyl chloride in a molar ratio of 1:1.3; the mass ratio of dichloromethane to hexamethylenediaminetetramethylenephosphoric acid is 20:1; the amount of 4-dimethylaminopyridine added is 3% of the mass of hexamethylenediaminetetramethylenephosphoric acid; the mass ratio of triethylamine added to oleoyl chloride is 0.8:1; the volume of ethylene glycol in the premixed liquid accounts for 15% of the total volume of the premixed liquid;

[0055] Add hexamethylenediaminetetramethylenephosphoric acid to a three-necked flask containing anhydrous dichloromethane to fully dissolve it, then add 4-dimethylaminopyridine to catalyze the reaction, and add triethylamine to adjust the reaction pH to 8. Under stirring conditions, use a dropping funnel to drop oleoyl chloride drop by drop, and the dropping rate is controlled at 1 drop per minute. Continue to drop for 15 minutes, continue to stir the reaction solution, and control the water bath heating at 30°C. After the addition of oleoyl chloride is completed, gradually increase the reaction temperature to 50°C, maintain this temperature for 6 hours, and continue to stir during the period. After the reaction is completed, cool to room temperature, stand for stratification, remove the lower layer of liquid, wash the upper layer of liquid with anhydrous ethanol, and dry it in a vacuum drying oven at 60°C to obtain a composite stabilizer;

[0056] The composite stabilizer is first mixed with ethylene glycol to form a premixed liquid, potassium chloride is added to deionized water, and the mixture is fully stirred with a stirrer until it is completely dissolved, and the mixture is heated to 40°C, and polydimethyldiallylammonium chloride, hexadecyltrimethylammonium bromide, xanthan gum and the remaining ethylene glycol are added in sequence, and the mixture is fully stirred and mixed evenly. Each time a raw material is added, the mixture is stirred for 30 minutes before the next raw material is added, and the premixed liquid is added to the mixed solution, and the mixture is continuously stirred and mixed evenly. Finally, sodium hydroxide pH regulator is added to adjust the pH value of the mixed solution to 7, and a water-resistant clay stabilizer is obtained.

[0057] Comparative Example 1: The method of Example 3 was adopted without adding a composite stabilizer.

[0058] Comparative Example 2: The method of Example 3 was adopted, the composite stabilizer contained only hexamethylenediaminetetramethylenephosphonic acid, and oleoyl chloride was removed.

[0059] Comparative Example 3: The method of Example 3 was adopted, and the composite stabilizer contained only oleoyl chloride, and hexamethylenediaminetetramethylenephosphonic acid was removed.

[0060] The present invention prepares a water-washable clay stabilizer, which has good anti-swelling rate, water-washing resistance and stability in the application of the stabilizer technology field. Specific tests are shown in the following table:

[0061] The test steps of clay stabilizer anti-swelling rate are as follows: ① Take a 10mL centrifuge tube, weigh 10mL of kerosene and add it into the centrifuge tube, then accurately weigh 0.50g (accurate to two decimal places) of bentonite and add it into the centrifuge tube, stir it thoroughly with a glass rod, let it stand at room temperature for 2 hours, put it into a centrifuge, centrifuge it at 1500r / min for 15 minutes, take out the centrifuge tube, mark the concave liquid surface with colored tape, take out the upper clear liquid in the centrifuge tube with a dropper, and weigh the mass m1 of the clear liquid with a precision balance, and Wash the centrifuge tube, add kerosene to the mark, weigh the mass of kerosene added m2, calculate the expansion volume V0 of bentonite in kerosene, ② replace 10mL kerosene with 10g distilled water, calculate the expansion volume V2 of bentonite in distilled water, ③ repeat step ①, replace 10mL kerosene with 10g clay stabilizer solution with a mass fraction of 0.5%, calculate the expansion volume V1 of bentonite in clay stabilizer solution, anti-swelling rate B = (V2-V1) / (V2-V0)×100%.

[0062] The steps for the water wash resistance test are as follows: take 5.0g of calcium-based bentonite and add it into a glass test tube, then add 0.5% by mass fraction of water-resistant clay stabilizer solution to the 50mL mark, shake well, let it stand for 6 hours and record the data, pour out 30mL of supernatant and add distilled water to the 50mL mark, shake well, let it stand for a cycle experiment, and record the change in expansion volume after 30 water washes. The expansion volume change rate = (initial volume-expansion volume after the 30th water wash) / initial volume × 100%.

[0063] The test steps for resistance to pH influence are as follows: 5.0g of calcium-based bentonite is added to a glass test tube, and then a 0.5% by mass fraction of a water-resistant clay stabilizer solution is added thereto to the 50mL scale line. At this time, 3 drops of 1% by mass fraction of hydrochloric acid solution are added to adjust the pH of the solution. The solution is shaken and recorded after standing for 6 hours. The pH expansion volume change rate = (initial volume - expansion volume after pH adjustment) / initial volume × 100%.

[0064] The obtained data are shown in Table 1

[0065] Table 1 Performance data of Examples 1-6 and Comparative Examples 1-3

[0066]

[0067] By comparing Examples 1-6 with Comparative Examples 1-3, it can be seen that in a water-resistant clay stabilizer, the composite stabilizer will have a significant impact on the anti-swelling rate, water-resistant and stable performance of the clay stabilizer.

[0068] According to Examples 1-3, as the proportion of components in the composite stabilizer continues to change, the anti-swelling rate, water washing resistance and stability of the clay stabilizer are better. This is because the composite stabilizer is obtained by mixing hexamethylenediaminetetramethylenephosphonic acid and oleoyl chloride in a certain molar ratio, and the hydrophobic groups introduced by oleoyl chloride form a dense covering layer on the surface of the clay particles, occupying the space on the surface of the clay particles, reducing the exposed area of ​​the clay particles, forming a physical barrier, reducing the possibility of hydration and expansion of the clay particles, and can effectively improve the problem that hexamethylenediaminetetramethylenephosphonic acid is easily affected by pH value, thereby improving the water washing resistance and stability of the clay stabilizer.

[0069] According to Example 3 and Example 4, the anti-swelling rate, water washability and stability of the clay stabilizer do not change significantly with the continuous change in the proportion of other components in the clay stabilizer. This shows that a small change in other components within a certain range is not enough to significantly change the water washability and stability of the clay stabilizer. Therefore, the proportion and structure of the composite stabilizer are the key factors that determine the performance of the clay stabilizer.

[0070] According to Examples 3, 5 and 6, the anti-swelling rate, water wash resistance and stability of the clay stabilizer change continuously with the continuous change of the content of the composite stabilizer. This is because the hexamethylenediaminetetramethylenephosphonic acid in the composite stabilizer contains multiple phosphate groups, which can form stable complexes with the metal ions on the surface of the clay, reduce the activity of these metal ions, and further reduce their binding with water molecules, thereby weakening the interaction between the clay particles and preventing the aggregation and expansion of the clay particles. The hydrophobic groups form a dense covering layer on the surface of the clay particles, which enhances the binding force between the composite stabilizer and the clay surface and further improves the water wash resistance. Therefore, reducing the content of the composite stabilizer, its effect becomes worse, and the water wash resistance and stability of the clay stabilizer are also worse.

[0071] According to the above test experiments, Example 3 is used as the optimal example and compared with Comparative Examples 1-3 respectively.

[0072] By comparing Example 1 with Comparative Example 1, it can be seen that the less the composite stabilizer is added, the worse the anti-swelling rate, water washability and stability of the clay stabilizer are. This is because hexamethylenediaminetetramethylenephosphonic acid can chelate with metals, inhibit the combination of metal ions and water molecules, and prevent clay swelling. The hydrophobic group of oleoyl chloride can provide a physical barrier to reduce the contact between clay and water molecules, while improving the stability of phosphate groups and metal ions. Without the composite stabilizer, the ability to chelate with metal ions and the hydrophobic covering layer are missing, and it is easily affected by pH, thereby significantly reducing the performance of the clay stabilizer.

[0073] By comparing Example 1 and Comparative Example 2, it can be seen that the composite stabilizer contains only hexamethylenediaminetetramethylenephosphonic acid and the oleoyl chloride is removed, and the anti-swelling rate, water washing resistance and stability of the clay stabilizer are worse. This is because the hydrophobic groups introduced by oleoyl chloride can interact with the hydrophobic areas on the clay surface to form a hydrophobic covering layer. This hydrophobic covering layer not only enhances the binding force between the composite stabilizer and the clay surface, but also reduces the direct contact between water molecules and clay particles, reduces the possibility of hydration expansion, and the hydrophobic groups form a physical barrier on the surface of the clay particles, further improving the water washing resistance. However, without the introduction of oleoyl chloride, the surface of the clay particles lacks an effective hydrophobic covering layer, which makes it easy for water molecules to penetrate between the clay particles, causing hydration expansion, and poor water washing resistance and stability.

[0074] By comparing Example 1 and Comparative Example 3, it can be seen that the composite stabilizer contains only oleoyl chloride and the anti-swelling rate, water washing resistance and stability of the clay stabilizer are worse when hexamethylenediaminetetramethylenephosphonic acid is removed. This is because hexamethylenediaminetetramethylenephosphonic acid can react with the metal ions on the surface of the clay, thereby weakening the interaction between the clay particles and preventing the aggregation and expansion of the clay particles. In the absence of hexamethylenediaminetetramethylenephosphonic acid, the activity of the metal ions is not effectively inhibited, and oleoyl chloride alone cannot fully solve the hydration expansion problem of the clay particles, thereby making the water washing resistance and stability of the clay stabilizer worse.

[0075] In summary, the composite stabilizer is used to improve the anti-swelling effect of clay through the chelation between the phosphoric acid group of hexamethylenediaminetetramethylenephosphonic acid and the metal, and the hydrophobic group of oleoyl chloride is used to provide a physical barrier on the clay surface, further improving the water washing resistance. At the same time, the hydrophobic group is also conducive to alleviating the chelation between hexamethylenediaminetetramethylenephosphonic acid and metal ions, which is easily affected by pH value, thereby improving the stability of the phosphoric acid group and thus improving the stability of the water-resistant clay stabilizer.

[0076] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and the above embodiments and descriptions are only preferred examples of the present invention, and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A water-resistant clay stabilizer, characterized in that: The invention comprises the following components in parts by weight: 0.1-0.5 parts by weight of a composite stabilizer, 0.5-1.5 parts by weight of polydimethyldiallylammonium chloride, 1-5 parts by weight of hexadecyltrimethylammonium bromide, 3-5 parts by weight of potassium chloride, 2-4 parts by weight of ethylene glycol, 0.2-0.4 parts by weight of xanthan gum, and 0.05-0.09 parts by weight of a sodium hydroxide pH regulator; Among them, the specific preparation method of the water-resistant clay stabilizer is as follows: First, the composite stabilizer and ethylene glycol are mixed to form a premixed liquid, potassium chloride is added to deionized water, and the mixture is fully stirred with a stirrer until it is completely dissolved, and the mixture is heated to 30-40° C., polydimethyldiallylammonium chloride, hexadecyltrimethylammonium bromide, xanthan gum and the remaining ethylene glycol are added in sequence, and the mixture is fully stirred and mixed evenly, and each time a raw material is added, the mixture is stirred for 30-40 minutes before the next raw material is added, and the premixed liquid is added to the mixed solution, and the mixture is stirred and mixed evenly, and finally sodium hydroxide pH regulator is added to adjust the pH value of the mixed solution to obtain a water-resistant clay stabilizer; The composite stabilizer is obtained by mixing hexamethylenediaminetetramethylenephosphoric acid and oleyl chloride in a molar ratio of 1:1.1-1.3; The specific preparation method of the composite stabilizer is as follows: Add hexamethylenediaminetetramethylenephosphoric acid to a three-necked flask containing anhydrous dichloromethane to fully dissolve it, then add 4-dimethylaminopyridine to catalyze the reaction, and add triethylamine to adjust the reaction pH. Under stirring conditions, use a dropping funnel to drop oleoyl chloride drop by drop, and continue to drop for 15-20 minutes. Continue to stir the reaction solution, and control the water bath heating at 30-35°C. After the addition of oleoyl chloride is completed, gradually increase the reaction temperature to 50-55°C, maintain this temperature for 4-6 hours, and continue to stir during the period. After the reaction is completed, cool to room temperature, stand for stratification, remove the lower layer of liquid, wash the upper layer of liquid with anhydrous ethanol, and dry it in a vacuum drying oven at 50-60°C to obtain a composite stabilizer.

2. A water-resistant clay stabilizer according to claim 1, characterized in that: The mass ratio of the dichloromethane to hexamethylenediaminetetramethylenephosphoric acid is 15-20:

1.

3. A water-resistant clay stabilizer according to claim 1, characterized in that: The added amount of the 4-dimethylaminopyridine is 1-3% of the mass of the hexamethylenediaminetetramethylenephosphoric acid.

4. The water-resistant clay stabilizer according to claim 1, characterized in that: The mass ratio of the added amount of triethylamine to oleoyl chloride is 0.6-0.8:

1.

5. The water-resistant clay stabilizer according to claim 1, characterized in that: The triethylamine solution is adjusted to a pH value of 7-8.

6. The water-resistant clay stabilizer according to claim 1, characterized in that: The dropping rate of the dropping funnel is controlled at 1-3 drops per minute.

7. The water-resistant clay stabilizer according to claim 1, characterized in that: The volume of ethylene glycol in the premixed liquid accounts for 11-15% of the total volume of the premixed liquid.

8. The water-resistant clay stabilizer according to claim 1, characterized in that: The sodium hydroxide pH regulator adjusts the pH value of the mixed solution to 7-9.

Images