A kind of anti-collapse agent for drilling fluid and preparation method thereof

Abstract

The invention relates to the technical field of anti-collapse agents, and discloses an anti-collapse agent for drilling fluid and a preparation method thereof. The invention obtains the anti-collapse agent for drilling fluid by adding boron-containing quaternary ammonium salt-modified phenolic resin, ester-containing epoxy resin-modified polyacrylamide, natural asphalt and calcium chloride into a reactor for stirring. The quaternary ammonium salt forms a protective film on the surface of the rock to prevent the formation from collapsing due to external force, thereby improving the anti-collapse effect; the three-dimensional network structure formed by the boron oxygen bond is not easily destroyed at high temperature, thereby improving the high temperature resistance; the network structure formed by cyanuric chloride is still stable at high temperature, thereby improving the bonding force and high temperature resistance of the anti-collapse agent; the hydroxyl and carboxyl groups generated after the ester group is hydrolyzed can cause cross-linking between polymers, thereby improving the anti-collapse effect; the epoxy resin can increase the viscosity of the anti-collapse agent, help to form a denser mud cake, improve the plugging effect of the anti-collapse agent, and also help to stabilize the well wall, thereby improving the anti-collapse effect.

Description

Technical Field

[0001] The invention relates to the technical field of anti-collapse agents, in particular to an anti-collapse agent for drilling fluid and a preparation method thereof. Background Art

[0002] Drilling fluid anti-collapse agent is an important chemical substance used to improve the stability of the well wall and prevent the formation from collapsing during the drilling process, and plays a vital role in drilling operations. At present, the commonly used asphalt anti-collapse agent is mainly to soften and deform the asphalt particles under certain downhole temperature and pressure conditions, and is squeezed into the pores and cracks of the formation, thereby preventing water from entering the mud shale, but this physical plugging anti-collapse agent cannot be closely adsorbed with the rock surface, and the anti-collapse plugging effect is poor, and it is limited by the asphalt softening point temperature, and it is impossible to meet the deep well drilling requirements under high temperature conditions. Therefore, how to avoid this phenomenon is the key to solving the problem. For example, patent CN103980868B discloses a kind of zwitterionic emulsified asphalt anti-collapse agent for drilling fluid, which has good storage stability and frost resistance, but its anti-collapse effect and high temperature resistance need to be improved. Summary of the invention

[0003] 1. Technical issues to be resolved

[0004] In view of the shortcomings of the prior art, the present invention provides an anti-collapse agent for drilling fluid and a preparation method thereof, which has good anti-collapse effect and high temperature resistance.

[0005] (II) Technical solution

[0006] To achieve the above object, the present invention provides the following technical solution: an anti-collapse agent for drilling fluid, comprising the following weight components: 14-18 weight parts of boron-containing quaternary ammonium salt-modified phenolic resin, 20-25 weight parts of ester-containing epoxy resin-modified polyacrylamide, 5-7 weight parts of natural asphalt, and 8-10 weight parts of calcium chloride;

[0007] Preferably, the method for preparing the boron-containing quaternary ammonium salt modified phenolic resin comprises the following steps:

[0008] (1) Add 3-(dimethylamino)phenylboronic acid and 3-bromopropylene to tetrahydrofuran solvent, stir and mix, and reflux at 78-90° C. for 2.5-3.5 h. After the reaction is completed, filter, wash and dry to obtain intermediate 1;

[0009] (2) Add phenol and formaldehyde solution to the reactor, mix well, add citric acid to adjust the pH to 2.5-3, react at 68-75°C for 0.5-1h, add intermediate 1, raise the temperature to 90-100°C and continue to react for 2.5-3h. After the reaction, add sodium hydroxide solution to adjust the pH to 7, wash with distilled water, let stand for 3-5h, suck out the upper water layer, and vacuum dry the lower layer to obtain intermediate 2;

[0010] (3) adding intermediate 2, 2-mercaptoethanol and diphenyl ether initiator to N,N-dimethylformamide solvent, irradiating with 365 nm ultraviolet light at 28-42 °C, centrifuging, washing and drying to obtain intermediate 3;

[0011] (4) Add intermediate 3 to acetone solvent, introduce nitrogen protection, add cyanuric chloride and sodium hydride catalyst, stir and mix, react at 15-25°C for 2-4 hours. After the reaction is completed, filter and distill under reduced pressure to obtain a boron-containing quaternary ammonium salt modified phenolic resin.

[0012] Preferably, in step (1), the mass ratio of 3-(dimethylamino)phenylboronic acid to 3-bromopropylene is 1:0.7-0.9.

[0013] Preferably, the mass fraction of the formaldehyde solution in step (2) is 35-40%.

[0014] Preferably, the ultraviolet light irradiation time in step (3) is 2-2.5 hours.

[0015] Preferably, in step (4), the mass ratio of the intermediate 3, cyanuric chloride and sodium hydride is 1:0.8-1.2:0.02-0.024.

[0016] Preferably, the preparation method of the ester-containing epoxy resin modified polyacrylamide comprises the following steps:

[0017] S1. Add maleic acid, 3-chloro-1,2-propanediol and p-toluenesulfonic acid catalyst to dichloromethane solvent, heat and reflux at 75-95°C for 1.5-3h. After the reaction is completed, filter, wash and dry to obtain intermediate 4;

[0018] S2. Add intermediate 4, bisphenol A epoxy resin, and potassium hydroxide catalyst to N,N-dimethylformamide solvent, stir and mix, react at 30-50° C. for 1.5-2.5 h, filter, wash and dry after the reaction to obtain an ester-containing epoxy resin;

[0019] S3. Add acrylamide and acrylic acid to deionized water, stir evenly, add sodium hydroxide to adjust the solution pH to 7, slowly drop ammonium persulfate initiator, and then add ester-containing epoxy resin to make it completely dispersed in water, pass nitrogen protection, react at 45-55°C for 8-12h, after the reaction is completed, wash, and vacuum dry to obtain ester-containing epoxy resin modified polyacrylamide.

[0020] Preferably, the mass ratio of maleic acid, 3-chloro-1,2-propanediol and p-toluenesulfonic acid in S1 is 1:1.2-1.3:0.04-0.06.

[0021] Preferably, the mass ratio of the intermediate 4, bisphenol A epoxy resin and potassium hydroxide in S2 is 1:0.7-0.9:0.02-0.025.

[0022] Preferably, the mass ratio of acrylamide, acrylic acid, sodium hydroxide, ammonium persulfate and ester-containing epoxy resin in S3 is 1:0.4-0.48:0.03-0.05:0.2-0.4:0.8-0.84.

[0023] Preferably, the preparation method of the anti-collapse agent for drilling fluid is: adding boron-containing quaternary ammonium salt-modified phenolic resin, ester-containing epoxy resin-modified polyacrylamide, natural asphalt, and calcium chloride into a reactor, stirring at a speed of 1300-1500 rpm for 8-15 minutes to obtain the anti-collapse agent for drilling fluid.

[0024] 3. Beneficial technical effects

[0025] The invention prepares the anti-collapse agent for drilling fluid by adding boron-containing quaternary ammonium salt-modified phenolic resin, ester-containing epoxy resin-modified polyacrylamide, natural asphalt and calcium chloride into a reactor and stirring the mixture.

[0026] The tertiary amine in 3-(dimethylamino)phenylboronic acid reacts with 3-bromopropylene to generate a quaternary ammonium salt, and a boric acid group and a carbon-carbon double bond are introduced to obtain intermediate 1. Phenol and formaldehyde undergo a polycondensation reaction to obtain a phenolic resin. The boric acid group in intermediate 1 reacts with a hydroxyl group in the phenolic resin to obtain intermediate 2. The carbon-carbon double bond in intermediate 2 reacts with a thiol group in 2-mercaptoethanol to undergo a click reaction to introduce a hydroxyl group to obtain intermediate 3. The hydroxyl group in intermediate 3 reacts with cyanuric chloride to form an ether bond to obtain a boron-containing quaternary ammonium salt-modified phenolic resin. The carboxyl group in maleic acid reacts with a hydroxyl group in 3-chloro-1,2-propylene glycol to introduce an ester group and a carbon-halogen bond to obtain intermediate 4. The carbon-halogen bond in intermediate 4 reacts with a hydroxyl group in a bisphenol A-type epoxy resin to obtain an ester-containing epoxy resin. The ester-containing epoxy resin is used as a hydrophobic monomer to copolymerize with acrylamide and acrylic acid to obtain an ester-containing epoxy resin-modified polyacrylamide.

[0027] The positive charge of the quaternary ammonium salt can be adsorbed onto the negatively charged rock surface through electrostatic action to form a protective film, thereby improving the stability and strength of the rock, preventing the formation from collapsing due to external forces, and improving the anti-collapse effect of the anti-collapse agent; the three-dimensional network structure formed by the boron oxygen bond is interconnected by covalent bonds to form a stable framework, which is not easily destroyed at high temperatures, thereby improving the high temperature resistance of the anti-collapse agent; cyanuric chloride can form a network structure with other components in the anti-collapse agent and remain stable at high temperatures, thereby improving the adhesion and high temperature resistance of the anti-collapse agent, reducing the risk of formation collapse, and enabling it to maintain the performance of the anti-collapse agent in a high-temperature drilling environment; the hydroxyl and carboxyl groups generated after the hydrolysis of the ester group can cause cross-linking between polymers, thereby improving the stability and mechanical strength of the anti-collapse agent, thereby improving the anti-collapse effect; epoxy resin can significantly increase the viscosity of the anti-collapse agent, help form a denser mud cake, further seal the pores and cracks in the formation, improve the sealing effect of the anti-collapse agent, and also help stabilize the well wall, prevent the falling off and collapse of formation fragments, thereby improving the anti-collapse effect. DETAILED DESCRIPTION Example 1

[0028] (1) Add 3-(dimethylamino)phenylboronic acid and 3-bromopropylene to tetrahydrofuran solvent, stir and mix, wherein the mass ratio of 3-(dimethylamino)phenylboronic acid to 3-bromopropylene is 1:0.7, and reflux and heat at 78°C for 2.5h. After the reaction is completed, filter, wash and dry to obtain intermediate 1;

[0029] (2) Add phenol and formaldehyde solution to the reactor, wherein the mass fraction of the formaldehyde solution is 35%, mix well, add citric acid to adjust the pH to 2.5, react at 68°C for 0.5h, add intermediate 1, raise the temperature to 90°C and continue to react for 2.5h. After the reaction is completed, add sodium hydroxide solution to adjust the pH to 7, wash with distilled water, let stand for 3h, suck out the upper water layer, and vacuum dry the lower layer to obtain intermediate 2;

[0030] (3) adding intermediate 2, 2-mercaptoethanol and diphenyl ether initiator to N,N-dimethylformamide solvent, irradiating with 365 nm ultraviolet light at 28 °C for 2 h, centrifuging, washing and drying to obtain intermediate 3;

[0031] (4) adding intermediate 3 to acetone solvent, introducing nitrogen protection, adding cyanuric chloride and sodium hydride catalyst, wherein the mass ratio of intermediate 3, cyanuric chloride and sodium hydride is 1:0.8:0.02, stirring and mixing, reacting at 15° C. for 2 h, filtering after the reaction, and distilling under reduced pressure to obtain a boron-containing quaternary ammonium salt modified phenolic resin;

[0032] (5) Adding maleic acid, 3-chloro-1,2-propylene glycol and p-toluenesulfonic acid catalyst to dichloromethane solvent, wherein the mass ratio of maleic acid, 3-chloro-1,2-propylene glycol and p-toluenesulfonic acid is 1:1.2:0.04, heating under reflux at 75°C for 1.5 h. After the reaction is completed, filtering, washing and drying to obtain intermediate 4;

[0033] (6) adding intermediate 4, bisphenol A epoxy resin and potassium hydroxide catalyst to N,N-dimethylformamide solvent, wherein the mass ratio of intermediate 4, bisphenol A epoxy resin and potassium hydroxide is 1:0.7:0.02, stirring and mixing, reacting at 30° C. for 1.5 h, filtering after the reaction, washing and drying to obtain an ester-containing epoxy resin;

[0034] (7) Add acrylamide and acrylic acid to deionized water, stir evenly, add sodium hydroxide to adjust the solution pH to 7, slowly drop ammonium persulfate initiator, and then add ester-containing epoxy resin, wherein the mass ratio of acrylamide, acrylic acid, sodium hydroxide, ammonium persulfate, and ester-containing epoxy resin is 1:0.4:0.03:0.2:0.8, and make them completely dispersed in water, pass nitrogen protection, react at 45°C for 8h, and after the reaction is completed, wash and vacuum dry to obtain ester-containing epoxy resin modified polyacrylamide;

[0035] (8) 14 parts by weight of boron-containing quaternary ammonium salt-modified phenolic resin, 20 parts by weight of ester-containing epoxy resin-modified polyacrylamide, 5 parts by weight of natural asphalt, and 8 parts by weight of calcium chloride were added to a reactor and stirred at a speed of 1300 rpm for 8 minutes to obtain an anti-collapse agent for drilling fluid. Example 2

[0036] (1) Add 3-(dimethylamino)phenylboronic acid and 3-bromopropylene to tetrahydrofuran solvent, stir and mix, wherein the mass ratio of 3-(dimethylamino)phenylboronic acid to 3-bromopropylene is 1:0.9, and reflux at 90° C. for 3.5 h. After the reaction is completed, filter, wash and dry to obtain intermediate 1;

[0037] (2) Add phenol and formaldehyde solution to the reactor, wherein the mass fraction of the formaldehyde solution is 40%, mix well, add citric acid to adjust the pH to 3, react at 75°C for 1 hour, add intermediate 1, heat to 100°C and continue to react for 3 hours. After the reaction is completed, add sodium hydroxide solution to adjust the pH to 7, wash with distilled water, let stand for 5 hours, suck out the upper water layer, and vacuum dry the lower layer to obtain intermediate 2;

[0038] (3) adding intermediate 2, 2-mercaptoethanol and diphenyl ether initiator to N,N-dimethylformamide solvent, irradiating with 365 nm ultraviolet light at 42 °C for 2.5 h, centrifuging, washing and drying to obtain intermediate 3;

[0039] (4) adding intermediate 3 to acetone solvent, introducing nitrogen protection, adding cyanuric chloride and sodium hydride catalyst, wherein the mass ratio of intermediate 3, cyanuric chloride and sodium hydride is 1:1.2:0.024, stirring and mixing, reacting at 25°C for 4 hours, filtering after the reaction, and distilling under reduced pressure to obtain a boron-containing quaternary ammonium salt modified phenolic resin;

[0040] (5) Adding maleic acid, 3-chloro-1,2-propanediol and p-toluenesulfonic acid catalyst to dichloromethane solvent, wherein the mass ratio of maleic acid, 3-chloro-1,2-propanediol and p-toluenesulfonic acid is 1:1.3:0.06, heating under reflux at 95°C for 3 h. After the reaction is completed, filtering, washing and drying to obtain intermediate 4;

[0041] (6) Adding intermediate 4, bisphenol A epoxy resin and potassium hydroxide catalyst to N,N-dimethylformamide solvent, wherein the mass ratio of intermediate 4, bisphenol A epoxy resin and potassium hydroxide is 1:0.9:0.025, stirring and mixing, reacting at 50° C. for 2.5 h, filtering, washing and drying after the reaction is completed, to obtain an ester-containing epoxy resin;

[0042] (7) Add acrylamide and acrylic acid to deionized water, stir evenly, add sodium hydroxide to adjust the solution pH to 7, slowly drop ammonium persulfate initiator, and then add ester-containing epoxy resin, wherein the mass ratio of acrylamide, acrylic acid, sodium hydroxide, ammonium persulfate, and ester-containing epoxy resin is 1:0.48:0.05:0.4:0.84, and make them completely dispersed in water, pass nitrogen protection, react at 55°C for 12 hours, and after the reaction is completed, wash and vacuum dry to obtain ester-containing epoxy resin modified polyacrylamide;

[0043] (8) 18 parts by weight of boron-containing quaternary ammonium salt-modified phenolic resin, 25 parts by weight of ester-containing epoxy resin-modified polyacrylamide, 7 parts by weight of natural asphalt, and 10 parts by weight of calcium chloride were added to a reactor and stirred at a speed of 1500 rpm for 15 minutes to obtain an anti-collapse agent for drilling fluid. Example 3

[0044] (1) Add 3-(dimethylamino)phenylboronic acid and 3-bromopropylene to tetrahydrofuran solvent, stir and mix, wherein the mass ratio of 3-(dimethylamino)phenylboronic acid to 3-bromopropylene is 1:0.8, and reflux and heat at 84°C for 3 h. After the reaction is completed, filter, wash and dry to obtain intermediate 1;

[0045] (2) Add phenol and formaldehyde solution to the reactor, wherein the mass fraction of the formaldehyde solution is 37%, mix well, add citric acid to adjust the pH to 2.7, react at 72°C for 0.7h, add intermediate 1, raise the temperature to 95°C and continue to react for 2.8h. After the reaction is completed, add sodium hydroxide solution to adjust the pH to 7, wash with distilled water, let stand for 4h, suck out the upper water layer, and vacuum dry the lower layer to obtain intermediate 2;

[0046] (3) adding intermediate 2, 2-mercaptoethanol and diphenyl ether initiator to N,N-dimethylformamide solvent, irradiating with 365 nm ultraviolet light at 35 °C for 2.3 h, centrifuging, washing and drying to obtain intermediate 3;

[0047] (4) adding intermediate 3 to acetone solvent, introducing nitrogen protection, adding cyanuric chloride and sodium hydride catalyst, wherein the mass ratio of intermediate 3, cyanuric chloride and sodium hydride is 1:1:0.022, stirring and mixing, reacting at 20° C. for 3 h, filtering after the reaction, and distilling under reduced pressure to obtain a boron-containing quaternary ammonium salt modified phenolic resin;

[0048] (5) Adding maleic acid, 3-chloro-1,2-propylene glycol and p-toluenesulfonic acid catalyst to dichloromethane solvent, wherein the mass ratio of maleic acid, 3-chloro-1,2-propylene glycol and p-toluenesulfonic acid is 1:1.25:0.05, heating under reflux at 85°C for 2.3 h. After the reaction is completed, filtering, washing and drying to obtain intermediate 4;

[0049] (6) Adding intermediate 4, bisphenol A epoxy resin and potassium hydroxide catalyst to N,N-dimethylformamide solvent, wherein the mass ratio of intermediate 4, bisphenol A epoxy resin and potassium hydroxide is 1:0.8:0.023, stirring and mixing, reacting at 40° C. for 2 h, filtering, washing and drying after the reaction, to obtain an ester-containing epoxy resin;

[0050] (7) Add acrylamide and acrylic acid to deionized water, stir evenly, add sodium hydroxide to adjust the solution pH to 7, slowly drop ammonium persulfate initiator, and then add ester-containing epoxy resin, wherein the mass ratio of acrylamide, acrylic acid, sodium hydroxide, ammonium persulfate, and ester-containing epoxy resin is 1:0.44:0.04:0.3:0.82, and make them completely dispersed in water, pass nitrogen protection, react at 50°C for 10 hours, and after the reaction is completed, wash and vacuum dry to obtain ester-containing epoxy resin modified polyacrylamide;

[0051] (8) 16 parts by weight of boron-containing quaternary ammonium salt-modified phenolic resin, 23 parts by weight of ester-containing epoxy resin-modified polyacrylamide, 6 parts by weight of natural asphalt, and 9 parts by weight of calcium chloride were added to a reactor and stirred at a speed of 1400 rpm for 12 minutes to obtain an anti-collapse agent for drilling fluid.

[0052] Comparative Example 1

[0053] The difference between this comparative example and Example 3 is that no boron-containing quaternary ammonium salt-modified phenolic resin is added.

[0054] Comparative Example 2

[0055] The difference between this comparative example and Example 3 is that no ester-containing epoxy resin-modified polyacrylamide is added.

[0056] Weigh 15g of dry bentonite, compact it at 4MPa for 3min, measure 10mL of drilling fluid anti-collapse agent solution, inject it into the bentonite, and use NP-1 shale expansion instrument to test the linear expansion for 5h. The test results are shown in Table 1.

[0057] Table 1: Linear expansion test.

[0058]

[0059] It can be seen from Table 1 that Examples 1-3 of the present invention have better anti-collapse effects than Comparative Examples 1-2.

[0060] 5 mL of anti-collapse agent sample solution was added to 50 mL of drilling mud, and then rolled and aged for 16 h at different temperatures, the filtration loss was measured, and the filtration reduction rate was calculated. The test results are shown in Table 2.

[0061] Table 2: Fluid loss reduction test.

[0062]

[0063] It can be seen from Table 2 that after aging at different temperatures, the filtration loss reduction rates of Examples 1-3 and Comparative Example 2 are relatively stable. After Comparative Example 1 is aged at 180°C for 18 hours, the filtration loss reduction rate of the anti-collapse agent decreases significantly, indicating that Examples 1-3 and Comparative Example 2 have better high temperature resistance than Comparative Example 1.

[0064] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. An anti-collapse agent for drilling fluid, characterized in that: The invention comprises the following components by weight: 14-18 parts by weight of a phenolic resin modified by a boron-containing quaternary ammonium salt, 20-25 parts by weight of an ester-containing epoxy resin modified polyacrylamide, 5-7 parts by weight of natural asphalt, and 8-10 parts by weight of calcium chloride; The preparation method of the boron-containing quaternary ammonium salt modified phenolic resin comprises the following steps: (1) Add 3-(dimethylamino)phenylboronic acid and 3-bromopropylene to tetrahydrofuran solvent, stir and mix, and reflux at 78-90° C. for 2.5-3.5 h. After the reaction is completed, filter, wash and dry to obtain intermediate 1; (2) Add phenol and formaldehyde solution to the reactor, mix well, add citric acid to adjust the pH to 2.5-3, react at 68-75°C for 0.5-1h, add intermediate 1, raise the temperature to 90-100°C and continue to react for 2.5-3h. After the reaction, add sodium hydroxide solution to adjust the pH to 7, wash with distilled water, let stand for 3-5h, suck out the upper water layer, and vacuum dry the lower layer to obtain intermediate 2; (3) adding intermediate 2, 2-mercaptoethanol and diphenyl ether initiator to N,N-dimethylformamide solvent, irradiating with 365 nm ultraviolet light at 28-42 °C, centrifuging, washing and drying to obtain intermediate 3; (4) Add intermediate 3 to acetone solvent, introduce nitrogen protection, add cyanuric chloride and sodium hydride catalyst, stir and mix, react at 15-25° C. for 2-4 hours, filter and distill under reduced pressure after the reaction is completed to obtain boron-containing quaternary ammonium salt modified phenolic resin; The preparation method of the ester-containing epoxy resin modified polyacrylamide comprises the following steps: S1. Add maleic acid, 3-chloro-1,2-propanediol and p-toluenesulfonic acid catalyst to dichloromethane solvent, heat and reflux at 75-95°C for 1.5-3h. After the reaction is completed, filter, wash and dry to obtain intermediate 4; S2. Add intermediate 4, bisphenol A epoxy resin, and potassium hydroxide catalyst to N,N-dimethylformamide solvent, stir and mix, react at 30-50° C. for 1.5-2.5 h, filter, wash and dry after the reaction to obtain an ester-containing epoxy resin; S3. Add acrylamide and acrylic acid to deionized water, stir evenly, add sodium hydroxide to adjust the solution pH to 7, slowly add ammonium persulfate initiator dropwise, and then add ester-containing epoxy resin to completely disperse it in water, pass nitrogen protection, react at 45-55 ° C for 8-12h, after the reaction is completed, wash, and vacuum dry to obtain ester-containing epoxy resin modified polyacrylamide; The mass ratio of maleic acid, 3-chloro-1,2-propylene glycol and p-toluenesulfonic acid in S1 is 1:1.2-1.3:0.04-0.06; The mass ratio of intermediate 4, bisphenol A epoxy resin and potassium hydroxide in S2 is 1:0.7-0.9:0.02-0.025; The mass ratio of acrylamide, acrylic acid, sodium hydroxide, ammonium persulfate and ester-containing epoxy resin in S3 is 1:0.4-0.48:0.03-0.05:0.2-0.4:0.8-0.

84.

2. The anti-collapse agent for drilling fluid according to claim 1, characterized in that: In the step (1), the mass ratio of 3-(dimethylamino)phenylboronic acid to 3-bromopropylene is 1:0.7-0.

9.

3. The anti-collapse agent for drilling fluid according to claim 1, characterized in that: The mass fraction of the formaldehyde solution in step (2) is 35-40%.

4. The anti-collapse agent for drilling fluid according to claim 1, characterized in that: The ultraviolet light irradiation time in step (3) is 2-2.5 hours.

5. The anti-collapse agent for drilling fluid according to claim 1, characterized in that: In the step (4), the mass ratio of the intermediate 3, cyanuric chloride and sodium hydride is 1:0.8-1.2:0.02-0.

024.

6. A method for preparing an anti-collapse agent for drilling fluid according to any one of claims 1 to 5, characterized in that: The preparation method of the anti-collapse agent for drilling fluid is as follows: adding boron-containing quaternary ammonium salt-modified phenolic resin, ester-containing epoxy resin-modified polyacrylamide, natural asphalt and calcium chloride into a reactor, stirring at a rotation speed of 1300-1500 rpm for 8-15 minutes to obtain the anti-collapse agent for drilling fluid.

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