A micro-nano plugging agent, a preparation method thereof, and a plugging drilling fluid prepared therefrom

Abstract

The application provides a micro-nano plugging agent, a preparation method thereof and a prepared plugging drilling fluid, and the preparation method comprises the following steps: S1: performing a gelation reaction on tetraethyl orthosilicate, tetrapropylammonium hydroxide and aluminum isopropoxide in water to obtain transparent gel; after drying and crushing the transparent gel, heating and calcining are performed to obtain porous zeolite; S2: modifying poly-p-phenyleneterephthalamide to obtain modified fiber material; S3: dissolving the modified fiber material in a mixed solution of dimethylacetamide and lithium chloride, and then immersing the porous zeolite, wherein the mass ratio of the modified fiber material to the porous zeolite is 4-6:16-18; after soaking, the micro-nano plugging agent is taken out and dried to obtain the micro-nano plugging agent. The micro-nano plugging agent prepared by the application can be more closely accumulated in the fissure, and has good plugging effect.

Description

Technical Field

[0001] The present invention relates to the technical field of drilling fluids, and in particular to a micro-nano plugging agent, a preparation method thereof, and the prepared plugging drilling fluid. Background Art

[0002] With the rapid increase in demand for oil and gas resources and advancements in drilling technology, researchers have increased their investment in the exploration and development of deep-seated oil and gas resources. Since some oil and gas resources are primarily buried deep in the formations, and the underground conditions are extremely complex, deep and ultra-deep well oil and gas drilling and the associated development technologies have become key factors restricting the development of these resources. As a crucial component of drilling engineering, the performance of drilling fluid is directly related to the drilling quality, drilling costs, and drilling cycle of deep and ultra-deep wells. As the depth of the formation increases, the complexity of the underground conditions increases, especially the cracks and fissures in the formation. These cracks and fissures can cause drilling fluid to enter the formation through these cracks and fissures after being injected into the wellbore, reducing the strength of the wellbore rock and leading to problems such as wellbore collapse.

[0003] For cracks and fissures in the formation, a common treatment method is to add plugging agents to the drilling fluid. The plugging agents are usually in the form of small particles or fibers. Their plugging principle is to enter the cracks and fissures and accumulate tightly, thereby isolating the inside of the wellbore from the formation and preventing the drilling fluid from entering the formation. However, most conventional plugging agents currently have poor sealing effects. The reason is that the plugging agent particles have poor dispersibility in water-based drilling fluid. Small particles easily aggregate into clumps in the drilling fluid, that is, their size becomes larger. As a result, they cannot effectively enter the cracks and fissures for sealing.

[0004] How to improve the plugging performance of plugging agents, that is, how to make the plugging agents disperse well in water-based drilling fluids and accumulate tightly in cracks and fissures, is an urgent problem in this field. Summary of the Invention

[0005] In order to solve the problem that the plugging agent has low accumulation density in the formation fissures and has poor plugging effect, the purpose of the present invention is to provide a micro-nano plugging agent and its preparation method and the prepared plugging drilling fluid, which can accumulate more densely in the fissures and have a good plugging effect.

[0006] To achieve the above object, the present invention provides a method for preparing a micro-nano plugging agent, which comprises the following steps:

[0007] S1: allowing tetraethyl orthosilicate, tetrapropylammonium hydroxide, and aluminum isopropoxide to undergo a gelation reaction in water to obtain a transparent gel; drying and crushing the transparent gel, and then heating and calcining the gel to obtain a porous zeolite;

[0008] S2: Modifying poly(p-phenylene terephthalamide) to obtain a modified fiber material;

[0009] S3: dissolving the modified fiber material in a mixture of dimethylacetamide and lithium chloride, and then immersing the porous zeolite, wherein the mass ratio of the modified fiber material to the porous zeolite is 4-6:16-18. After immersion, the modified fiber material is taken out and dried to obtain the micro-nano plugging agent.

[0010] In step S1 of the preparation method of the present invention, ethyl orthosilicate, aluminum isopropoxide and tetrapropylammonium hydroxide are used as raw materials to prepare a porous zeolite with a particle size of 200-500 nm, which is smaller than the size of conventional formation fissures of 1-2 microns, that is, it can smoothly enter the fissures for plugging.

[0011] In step S2 of the preparation method of the present invention, poly (p-phenylene terephthalamide) is hydrophilically modified using a silane coupling agent KH-792, thereby improving its dispersion performance in water. Specifically, the silane coupling agent KH-792 is a diamino-functional silane. When it is hydrolyzed in water, the -Si(OCH3)3 group is hydrolyzed into a highly hydrophilic -Si(OH)3. At the same time, the -(CH2)3NH(CH2)2NH2 at the other end of the molecular chain can react with the -COOH group on the surface of poly (p-phenylene terephthalamide) through the -NH2 and -NH groups, thereby successfully grafting the coupling agent to the surface of poly (p-phenylene terephthalamide), thereby improving its hydrophilicity and dispersibility. After such modification, since poly (p-phenylene terephthalamide), i.e., the fiber material, has good dispersibility, the micro-nano plugging agent particles are not easily aggregated in the water-based drilling fluid.

[0012] Step S3 of the preparation method of the present invention is to load the fiber material onto the porous zeolite using a mixed solution of dimethylacetamide and lithium chloride. The specific principle is: in the mixed solution, dimethylacetamide and lithium chloride form (DMAcLi) + Large cations, Li + With Cl - The charge distribution between Cl - With more negative charge, Cl - The ability to attack the H protons in the amide bonds on the poly(p-phenylene terephthalamide) molecular chain is greatly enhanced, and hydrogen bonds are formed with it, thereby destroying the poly(p-phenylene terephthalamide) crystalline region grid, ultimately causing the poly(p-phenylene terephthalamide) macromolecular chain to dissociate and dissolve, and after dissolution, it appears as a clear and transparent solution. When the porous zeolite is placed in it, the dissolved poly(p-phenylene terephthalamide) enters the pores of the porous zeolite and adheres to the surface of the porous zeolite. It is then heat-dried, and under heat treatment, the dimethylacetamide solution gradually evaporates, resulting in (DMAcLi) +The hydrogen bond between the large cation and the poly(p-phenylene terephthalamide) molecular chain is destroyed, causing the poly(p-phenylene terephthalamide) crystalline region to regenerate, that is, the dissolved fiber begins to regenerate. The roots of the regenerated fiber material are fixed in the pores, and the free ends are distributed on the outside of the porous zeolite.

[0013] According to a specific embodiment of the present invention, preferably, in S1, the mass ratio of tetraethyl orthosilicate, tetrapropylammonium hydroxide, and aluminum isopropoxide is 12-14:2-4:5-7.

[0014] According to a specific embodiment of the present invention, preferably, in S1, the gelation reaction temperature is 35-45° C., and the reaction time is 15-25 min.

[0015] According to a specific embodiment of the present invention, preferably, in S1, the heating temperature is 160-180°C and the heating time is 8-9 hours.

[0016] According to a specific embodiment of the present invention, preferably, in S1, the calcination temperature is 560-600° C., and the heating time is 4-5 hours.

[0017] According to a specific embodiment of the present invention, preferably, the particle size of the porous zeolite is 200-500 nm. The particle size of the porous zeolite is controlled during the crushing process of S1.

[0018] According to a specific embodiment of the present invention, preferably, in S2, the method for modifying poly(p-phenylene terephthalamide) comprises: subjecting poly(p-phenylene terephthalamide) to ultrasonic treatment in acetone and in a silane coupling agent solution in sequence to obtain the modified fiber material.

[0019] According to a specific embodiment of the present invention, preferably, the modification method further comprises: washing and drying the poly(p-phenylene terephthalamide) after ultrasonic treatment.

[0020] According to a specific embodiment of the present invention, preferably, the silane coupling agent solution includes at least one of KH-792 silane coupling agent, KH-902 silane coupling agent, and KH-571 silane coupling agent, preferably KH-792 silane coupling agent with a mass concentration of 25-28 wt%.

[0021] According to a specific embodiment of the present invention, preferably, the ultrasonic power of the ultrasonic treatment is 70-90W, and the treatment time is 3-4h.

[0022] According to a specific embodiment of the present invention, preferably, in S3, the mass ratio of the porous zeolite, the modified fiber material, and the mixed solution of dimethylacetamide and lithium chloride is 4-6:16-18:34-36.

[0023] According to a specific embodiment of the present invention, preferably, in S3, the mass ratio of dimethylacetamide to lithium chloride in the mixed solution of dimethylacetamide and lithium chloride is 1:9-11.

[0024] According to a specific embodiment of the present invention, preferably, in S3, the soaking time of the porous zeolite is 2-3 hours.

[0025] According to a specific embodiment of the present invention, preferably, in S3, the drying temperature is 60-70° C., and the drying time is 40-60 min.

[0026] According to a specific embodiment of the present invention, preferably, the preparation method of the micro-nano plugging agent comprises the following steps:

[0027] This embodiment is used to prepare a micro-nano plugging agent, including the following steps:

[0028] S1. Synthetic porous zeolite:

[0029] S11, adding 20-25 parts by weight of water, 12-14 parts by weight of ethyl orthosilicate, and 5-7 parts by weight of aluminum isopropoxide into a three-necked flask and stirring;

[0030] S12, adding 2-4 parts by weight of tetrapropylammonium hydroxide to a three-necked flask, stirring in a water bath to obtain a transparent gel;

[0031] S13, drying and grinding the transparent gel obtained in step S12, then transferring it to a hydrothermal kettle and heating it at 160-180° C. for 8-9 hours;

[0032] S14, transferring the material treated in step S13 into a muffle furnace and calcining at 560-600° C. for 4-5 hours to obtain a porous zeolite with a particle size of 200-500 nm;

[0033] S2. Modifying the dispersion performance of poly(p-phenylene terephthalamide) to obtain a modified fiber material:

[0034] S21, soaking poly(p-phenylene terephthalamide) in acetone and ultrasonically treating it at an ultrasonic power of 70-90 W for 3-4 hours;

[0035] S22, taking out the material treated in step S21 and placing it in a 25-28% silane coupling agent KH-792 solution, and ultrasonically treating it at an ultrasonic power of 70-90 W for 3-4 hours;

[0036] S23, taking out the material treated in step S22, washing it with deionized water and then drying it to obtain a modified fiber material;

[0037] S3, a first mixed solution of dimethylacetamide and lithium chloride is prepared, and the mass ratio of lithium chloride to dimethylacetamide is 1:9-11;

[0038] S4, the modified fiber material obtained in step S2 is placed in the first mixed solution obtained in step S3, and stirred at room temperature, and after the modified fiber material is completely dissolved, a second mixed solution is obtained;

[0039] S5, the porous zeolite obtained in step S1 is soaked in the second mixed solution obtained in step S4, and the soaking time is 2-3h;

[0040] S6, the porous zeolite soaked in step S5 is transferred to a forced air drying oven for heat baking, the heat baking temperature is 60-70℃, the heat baking time is 40-60min, and after heat baking, the micro-nano plugging agent is obtained.

[0041] The application also provides a micro-nano plugging agent prepared by the preparation method of the micro-nano plugging agent.

[0042] The application also provides a plugging drilling fluid prepared from the micro-nano plugging agent.

[0043] Preferably, in the plugging drilling fluid, the raw materials of the plugging drilling fluid include 3-5 parts of the micro-nano plugging agent, 4-6 parts of bentonite, 0.5-1.5 parts of sodium hydroxide, 2-4 parts of sodium carboxymethyl cellulose, 7-9 parts of xanthan gum, and 60-80 parts of barite.

[0044] The technical scheme provided by the application has the following beneficial effects:

[0045] The micro-nano plugging agent prepared by the application uses porous zeolite with certain dispersibility in water-based drilling fluid as the main body, so that the micro-nano plugging agent is not easy to gather into a group in the water-based drilling fluid; in addition, the modified fiber material is loaded in the pores of the porous zeolite, so that the roots of the modified fiber material are fixed in the pores and the free ends are distributed outside the porous zeolite; when the porous zeolite particles enter the stratum fissure, the size of the fissure is small, that is, the distance between the particles is small, and the free ends of the fiber material are intertwined with each other, so that the porous zeolite particles are more tightly stacked in the fissure, effectively improving the plugging effect. DETAILED DESCRIPTION

[0046] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the application, the technical scheme of the application will be described in detail below, but it cannot be understood as limiting the scope of the application.

[0047] Example 1

[0048] This embodiment provides a method for preparing a micro-nano plugging agent, comprising the following steps:

[0049] S1. Synthetic porous zeolite:

[0050] S11, adding 23 parts by weight of water, 13 parts by weight of ethyl orthosilicate and 6 parts by weight of aluminum isopropoxide into a three-necked flask and stirring;

[0051] S12, adding 3 parts by weight of tetrapropylammonium hydroxide to a three-necked flask, stirring in a water bath, to obtain a transparent gel;

[0052] S13, drying and grinding the transparent gel obtained in step S12, and then transferring it to a hydrothermal kettle and heating it at 170° C. for 8.5 hours;

[0053] S14, transferring the material treated in step S13 into a muffle furnace and calcining at 580° C. for 4.5 h to obtain a porous zeolite with a particle size of 350 nm;

[0054] S2. Modifying the dispersion performance of poly(p-phenylene terephthalamide) to obtain a modified fiber material:

[0055] S21, soaking poly(p-phenylene terephthalamide) in acetone and ultrasonically treating it at an ultrasonic power of 80 W for 3.5 h;

[0056] S22, taking out the material treated in step S21 and placing it in a KH-792 silane coupling agent with a concentration of 26 wt%, and ultrasonically treating it at an ultrasonic power of 80 W for 3.5 hours;

[0057] S23, taking out the material treated in step S32, washing it with deionized water and then drying it to obtain a modified fiber material;

[0058] S3. Prepare a mixed solution of dimethylacetamide and lithium chloride, with a mass ratio of lithium chloride to dimethylacetamide of 1:10.

[0059] S4. Add the modified fiber material obtained in step S2 to the mixed solution obtained in step S3, stir at room temperature, and after the modified fiber material is completely dissolved, immerse the porous zeolite obtained in step S1 for 2.5 hours. The mass ratio of the mixed solution, modified fiber material, and porous zeolite is 18:17:5.

[0060] S5. Transfer the porous zeolite soaked in step S4 to a blast drying oven for drying at a temperature of 65° C. for 50 min. Take it out after drying to obtain the micro-nano plugging agent A1.

[0061] Example 2

[0062] This embodiment provides a method for preparing a micro-nano plugging agent, comprising the following steps:

[0063] S1. Synthetic porous zeolite:

[0064] S11, adding 20 parts by weight of water, 12 parts by weight of ethyl orthosilicate and 5 parts by weight of aluminum isopropoxide into a three-necked flask and stirring;

[0065] S12, adding 2 parts by weight of tetrapropylammonium hydroxide to a three-necked flask, stirring in a water bath, to obtain a transparent gel;

[0066] S13, drying and grinding the transparent gel obtained in step S12, and then transferring it to a hydrothermal kettle and heating it at 160° C. for 8 hours;

[0067] S14, transferring the material treated in step S13 into a muffle furnace and calcining at 560° C. for 4 h to obtain a porous zeolite with a particle size of 200 nm;

[0068] S2. Modifying the dispersion performance of poly(p-phenylene terephthalamide) to obtain a modified fiber material:

[0069] S21, soaking poly(p-phenylene terephthalamide) in acetone and ultrasonically treating it at an ultrasonic power of 70 W for 3 h;

[0070] S22, taking out the material treated in step S21 and placing it in a 25 wt% KH-792 silane coupling agent, and ultrasonically treating it at an ultrasonic power of 70 W for 3 h;

[0071] S23, taking out the material treated in step S32, washing it with deionized water and then drying it to obtain a modified fiber material;

[0072] S3. Prepare a first mixed solution of dimethylacetamide and lithium chloride, with a mass ratio of lithium chloride to dimethylacetamide of 1:9.

[0073] S4. Add the modified fiber material obtained in step S2 to the mixed solution obtained in step S3, stir at room temperature, and after the modified fiber material is completely dissolved, immerse the porous zeolite obtained in step S1 for 2 hours. The mass ratio of the mixed solution, modified fiber material, and porous zeolite is 9:8:2.

[0074] S5. Transfer the porous zeolite soaked in step S4 to a blast drying oven for drying at a temperature of 60° C. for 40 min. Take it out after drying to obtain the micro-nano plugging agent A2.

[0075] Example 3

[0076] This embodiment provides a method for preparing a micro-nano plugging agent, comprising the following steps:

[0077] S1. Synthetic porous zeolite:

[0078] S11, adding 25 parts by weight of water, 14 parts by weight of ethyl orthosilicate and 7 parts by weight of aluminum isopropoxide into a three-necked flask and stirring;

[0079] S12, adding 4 parts by weight of tetrapropylammonium hydroxide to a three-necked flask, stirring in a water bath to obtain a transparent gel;

[0080] S13, drying and grinding the transparent gel obtained in step S12, then transferring it to a hydrothermal kettle and heating it at 180° C. for 9 hours;

[0081] S14, transferring the material treated in step S13 into a muffle furnace and calcining at 600° C. for 5 h to obtain a porous zeolite with a particle size of 500 nm;

[0082] S2. Modifying the dispersion performance of poly(p-phenylene terephthalamide) to obtain a modified fiber material:

[0083] S21, soaking poly(p-phenylene terephthalamide) in acetone and ultrasonically treating it at an ultrasonic power of 90 W for 4 h;

[0084] S22, taking out the material treated in step S21 and placing it in a KH-792 silane coupling agent with a concentration of 28 wt%, and ultrasonically treating it at an ultrasonic power of 90 W for 4 hours;

[0085] S23, taking out the material treated in step S32, washing it with deionized water and then drying it to obtain a modified fiber material;

[0086] S3. Prepare a first mixed solution of dimethylacetamide and lithium chloride, with a mass ratio of lithium chloride to dimethylacetamide of 1:11.

[0087] S4. Add the modified fiber material obtained in step S2 to the mixed solution obtained in step S3, stir at room temperature, and after the modified fiber material is completely dissolved, immerse the porous zeolite obtained in step S1 for 3 hours. The mass ratio of the mixed solution, modified fiber material, and porous zeolite is 18:18:5.

[0088] S5. Transfer the porous zeolite soaked in step S4 to a blast drying oven for drying at a temperature of 70° C. for 60 min. Take it out after drying to obtain the micro-nano plugging agent A3.

[0089] Example 4

[0090] The embodiment provides a plugging drilling fluid, and a preparation method thereof is as follows: 100 parts of water, 5 parts of bentonite, 1 part of sodium hydroxide, 3 parts of sodium carboxymethyl cellulose, 8 parts of xanthan gum, 70 parts of barite, and 4 parts of the micro-nano plugging agent A1 prepared in the embodiment 1 are mixed and stirred to obtain the plugging drilling fluid B1.

[0091] Example 5

[0092] The embodiment provides a plugging drilling fluid, and a preparation method thereof is as follows: 100 parts of water, 5 parts of bentonite, 1 part of sodium hydroxide, 3 parts of sodium carboxymethyl cellulose, 8 parts of xanthan gum, 70 parts of barite, and 4 parts of the micro-nano plugging agent A1 prepared in the embodiment 1 are mixed and stirred to obtain the plugging drilling fluid B1.

[0093] Example 6

[0094] The embodiment provides a plugging drilling fluid, and a preparation method thereof is as follows: 100 parts of water, 5 parts of bentonite, 1 part of sodium hydroxide, 3 parts of sodium carboxymethyl cellulose, 8 parts of xanthan gum, 70 parts of barite, and 4 parts of the micro-nano plugging agent A1 prepared in the embodiment 1 are mixed and stirred to obtain the plugging drilling fluid B1.

[0095] Comparative Example 1

[0096] The comparative example provides a drilling fluid, and a preparation method thereof is the same as that in the embodiment 4, except that the micro-nano plugging agent A1 is not added. The drilling fluid D1 is obtained.

[0097] Comparative Example 2

[0098] The comparative example provides a drilling fluid, and a preparation method thereof is the same as that in the embodiment 4, except that the micro-nano plugging agent A1 is not added, and a mixture of poly-p-phenyleneterephthalamide and porous zeolite (poly-p-phenyleneterephthalamide: porous zeolite = 17:5 in mass ratio) is added instead. The drilling fluid D2 is obtained.

[0099] Experimental Example

[0100] The experimental example is used for testing the plugging performance of the plugging drilling fluids B1-B3 prepared in the embodiments 4-6 and the drilling fluids D1 and D2 prepared in the comparative examples 1-2, and the specific operation is as follows:

[0101] The filtration loss of the prepared drilling fluid within half an hour is tested by using a high-temperature and high-pressure filtration instrument in a normal temperature environment and is recorded. Filter paper is placed on the inner bottom of a kettle body of the high-temperature and high-pressure filtration instrument, a plurality of small holes with a size of 1 micrometer are distributed on the filter paper, and the thickness of the filter paper is 5 millimeters. The result is shown in Table 1.

[0102] Table 1: Filtration loss of drilling fluid

[0103] Serial number Filtrate loss / mL Plugging drilling fluid B1 2.1 Plugging drilling fluid B2 2.2 Plugging drilling fluid B3 2.2 Drilling fluid D1 54 Drilling fluid D2 26

[0104] As can be seen from the data in Table 1, the micro-nano plugging agent prepared by the method provided by the present application, when added into the drilling fluid system to form the plugging drilling fluid B1-B3, has a filtration loss of less than 3 mL within half an hour, which indicates that the micro-nano plugging agent forms a tight accumulation on the surface and inside the pores of the filter paper within a short time, effectively blocking the environment inside and outside the filter press kettle.

[0105] As can be seen from the drilling fluid D1 as a blank control group, in the case where no plugging component is added, the filtrate in the drilling fluid continuously filters out, and the filtration loss reaches 54 mL within half an hour. In the drilling fluid D2, since the plugging component is only a mixture of poly-p-phenyleneterephthalamide and porous zeolite, it has a certain plugging effect, but the filtration loss is still large. On the one hand, the poly-p-phenyleneterephthalamide in the form of fibers is not modified for dispersion, so that the poly-p-phenyleneterephthalamide in the drilling fluid is intertwined with each other, increasing the volume of the solid phase particles, and the large-volume solid phase particles cannot enter the pores of the filter paper for effective plugging. On the other hand, the poly-p-phenyleneterephthalamide and the porous zeolite entering the pores of the filter paper cannot realize tight accumulation due to the absence of a stable connection relationship between the two, so that the plugging of the pores on the filter paper is not thorough enough, so that the filtrate continuously filters out through the filter paper, and the continuous filtration reaches 26 mL within half an hour, and this filtration loss will further increase with the extension of time.

[0106] The above is only a preferred embodiment of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a micro-nano plugging agent, comprising the following steps: S1: allowing tetraethyl orthosilicate, tetrapropylammonium hydroxide, and aluminum isopropoxide to undergo a gelation reaction in water to obtain a transparent gel; drying and crushing the transparent gel, and then heating and calcining the gel to obtain a porous zeolite; S2: treating poly(p-phenylene terephthalamide) with ultrasound in acetone and then in a silane coupling agent solution to obtain a modified fiber material; S3: dissolving the modified fiber material in a mixture of dimethylacetamide and lithium chloride, and then immersing the porous zeolite, wherein: The mass ratio of the modified fiber material to the porous zeolite is 4-6:16-18. After soaking, the modified fiber material is taken out and dried to obtain the micro-nano plugging agent.

2. The method for preparing the micro-nano plugging agent according to claim 1, wherein: In S1, the mass ratio of ethyl orthosilicate, tetrapropylammonium hydroxide, and aluminum isopropoxide is 12-14:2-4:5-7.

3. The preparation method of the micro-nano plugging agent according to claim 1, wherein: In S1, the gelation reaction temperature is 35-45° C., and the reaction time is 15-25 min.

4. The method for preparing the micro-nano plugging agent according to claim 1, wherein: In S1, the heating temperature is 160-180° C. and the heating time is 8-9 hours.

5. The method for preparing the micro-nano plugging agent according to claim 1, wherein: In S1, the calcination temperature is 560-600° C., and the heating time is 4-5 hours.

6. The method for preparing the micro-nano plugging agent according to claim 1, wherein: The particle size of the porous zeolite is 200-500 nm.

7. The method for preparing the micro-nano plugging agent according to claim 1, wherein: S2 further includes: washing and drying the poly(p-phenylene terephthalamide) after ultrasonic treatment.

8. The method for preparing the micro-nano plugging agent according to claim 1, wherein: The silane coupling agent solution includes at least one of KH-792 silane coupling agent, KH-902 silane coupling agent, and KH-571 silane coupling agent.

9. The method for preparing the micro-nano plugging agent according to claim 8, wherein: The silane coupling agent solution is a KH-792 silane coupling agent with a mass concentration of 25-28wt%.

10. The method for preparing the micro-nano plugging agent according to claim 1, wherein: The ultrasonic power of the ultrasonic treatment is 70-90W, and the treatment time is 3-4h.

11. The method for preparing the micro-nano plugging agent according to claim 1, wherein: In S3, the mass ratio of the porous zeolite, the modified fiber material, and the mixed solution of dimethylacetamide and lithium chloride is 4-6:16-18:34-36.

12. The method for preparing the micro-nano plugging agent according to claim 1, wherein: In S3, the mass ratio of dimethylacetamide to lithium chloride in the mixed solution of dimethylacetamide and lithium chloride is 1:9-11.

13. The method for preparing the micro-nano plugging agent according to claim 1, wherein: In S3, the porous zeolite is soaked for 2-3 hours.

14. The method for preparing the micro-nano plugging agent according to claim 1, wherein: In S3, the drying temperature is 60-70°C and the drying time is 40-60 minutes.

15. A micro-nano plugging agent obtained by the preparation method of the micro-nano plugging agent according to any one of claims 1 to 14.

16. A plugging drilling fluid prepared from the micro-nano plugging agent according to claim 15.

17. The plugging drilling fluid according to claim 16, wherein the raw materials thereof comprise, in parts by weight: 3-5 parts of the micro-nano plugging agent according to claim 14, 4-6 parts of bentonite, 0.5-1.5 parts of sodium hydroxide, 2-4 parts of sodium carboxymethyl cellulose, 7-9 parts of xanthan gum, and 60-80 parts of barite.