A leak-proof material with slow-release dispersing effect, preparation method and application thereof

Abstract

The application provides a plugging material with slow-release dispersion and a preparation method and application thereof. The plugging material comprises a core and a shell with a mass ratio of (4-5):1. The core comprises silica porous microspheres, and the inside of the pores of the silica porous microspheres is adhered with polyacrylamide. The mass ratio of the silica porous microspheres and the polyacrylamide is 1:(16-18). The shell is formed by mixing clay and inorganic particles. The plugging material has slow-release dispersion, and the viscosity of the plugging slurry cannot be increased when the plugging material is just put into a well. The viscosity of the plugging slurry is slowly increased during the sinking process, so that the plugging effect is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of plugging materials, and in particular to a plugging material with a slow-release dispersing effect, a preparation method thereof, and an application thereof. Background Art

[0002] Lost circulation is a common wellbore complexity in drilling operations, with varying degrees of leakage occurring in most drilling processes. Severe lost circulation can cause a drop in wellbore pressure, disrupting normal drilling, causing wellbore instability, and triggering an influx of formation fluids into the wellbore, leading to blowouts. Lost circulation is typically caused by wellbore fluid pressure exceeding formation pressure, or by formations with large porosity, high permeability, or the presence of caves and fissures.

[0003] After a well leak occurs, plugging materials need to be lowered to seal the cracks in the wellbore. However, conventional plugging materials have a problem. Since polymers need to be added to the plugging materials to suspend and disperse the solid particles, after being configured into a plugging slurry, the polymers increase the viscosity of the plugging slurry and reduce its fluidity. After being injected into the wellbore, the amount of solid particles that can effectively reach the cracks in the leakage zone is very small. Therefore, an excess of solid particles needs to be added to ensure that the cracks are sealed. However, an excessive amount of solid particles will increase the density of the plugging slurry. When the plugging slurry density increases, there is a risk of fracturing the wellbore, resulting in a vicious cycle of more plugging and more leakage. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a plugging material with slow-release dispersing effect and its preparation method and application, so that the plugging material will not increase the viscosity of the plugging slurry when it is just entered into the well, and will slowly increase the viscosity of the plugging slurry during the sinking process, thereby exerting the plugging effect.

[0005] To achieve the above object, the present invention provides a plugging material with a slow-release dispersing effect, which comprises a core and a shell in a mass ratio of (4-5):1;

[0006] The inner core comprises porous silica microspheres, and polyacrylamide is adhered to the pores of the porous silica microspheres, wherein the mass ratio of the porous silica microspheres to the polyacrylamide is 1:(16-18);

[0007] The shell is made of a mixture of clay and inorganic particles.

[0008] In the above-mentioned plugging material with slow-release dispersing effect, preferably, the porous silica microspheres have a porous capillary structure; and the particle size of the porous silica microspheres is 0.3-0.5 mm.

[0009] In the above-mentioned plugging material with slow-release dispersing effect, preferably, the polyacrylamide is in powder form.

[0010] In the above-mentioned plugging material with slow-release and dispersing effects, preferably, the core further comprises a starch adhesive layer and / or a resin protective layer coated on the surface of the porous silica microspheres.

[0011] In the above-mentioned plugging material with slow-release and dispersing effects, preferably, the inner core further comprises, from the inside to the outside, a starch adhesive layer and a resin protective layer coated on the surface of the porous silica microspheres.

[0012] In the above-mentioned plugging material with slow-release and dispersing effects, preferably, the mass ratio of the porous silica microspheres, the starch adhesive layer, and the resin protective layer is 1:(20-24):(59-62).

[0013] In the above-mentioned plugging material with slow-release dispersing effect, preferably, the resin protective layer comprises paraffin wax and water-absorbing resin in a mass ratio of (30-34): (26-28).

[0014] In the above-mentioned plugging material with slow-release dispersing effect, preferably, the water-absorbing resin is sodium polyacrylate.

[0015] In the above-mentioned plugging material with slow-release dispersing effect, preferably, the shell is a fully enclosed structure; the mass ratio of clay and inorganic particles in the shell is (40-45):(15-18).

[0016] In the above-mentioned plugging material with slow-release dispersing effect, preferably, the inorganic particles contain calcium carbonate powder.

[0017] In the above-mentioned plugging material with slow-release dispersing effect, preferably, the particle size of the inorganic particles is 10-16 μm.

[0018] The present invention also provides a method for preparing the above-mentioned plugging material with slow-release dispersing effect, which comprises the following steps:

[0019] Preparation of porous silica microspheres;

[0020] loading polyacrylamide into the pores of the porous silica microspheres to obtain an inner core;

[0021] The paste containing clay and inorganic particles is coated on the surface of the inner core and dried to obtain the plugging material with slow-release dispersing effect.

[0022] In the above-mentioned method for preparing the plugging material with slow-release dispersing effect, preferably, the method for preparing the porous silica microspheres comprises the following steps:

[0023] A first reaction of dimethyldichlorosilane with hydrochloric acid yields an oily substance;

[0024] allowing the oil to undergo a second reaction with aqueous ammonia, filtering out a solid product to obtain semi-finished microspheres;

[0025] The semi-finished microspheres are calcined and cooled to obtain the porous silica microspheres.

[0026] In the above-mentioned method for preparing the plugging material with slow-release dispersing effect, preferably, the method for preparing the porous silica microspheres further comprises: after the second reaction, washing the filtered solid product with anhydrous ethanol.

[0027] In the preparation method of the above-mentioned plugging material with slow-release dispersing effect, preferably, the mass ratio of the dimethyldichlorosilane to the hydrochloric acid is (45-55): (15-20); and the mass concentration of the hydrochloric acid is 42-48 wt%.

[0028] In the above-mentioned method for preparing the plugging material with slow-release dispersing effect, preferably, the reaction temperature of the first reaction is 40-50° C., and the reaction time is 30-40 min.

[0029] In the preparation method of the above-mentioned plugging material with slow-release dispersing effect, preferably, the mass ratio of the oily substance to the ammonia water is (20-30):(8-10); and the mass concentration of the ammonia water is 28-32wt%.

[0030] In the above-mentioned method for preparing the plugging material with slow-release dispersing effect, preferably, the reaction temperature of the second reaction is 35-38° C., and the reaction time is 20-25 min.

[0031] In the above-mentioned method for preparing the plugging material with slow-release dispersing effect, preferably, the calcination temperature is 500-700° C., and the calcination time is 60-70 minutes.

[0032] In the above-mentioned method for preparing the plugging material with slow-release dispersing effect, preferably, the method for preparing the porous silica microspheres further comprises: washing the filtered solid product with anhydrous ethanol.

[0033] In the above-mentioned method for preparing the plugging material with slow-release and dispersing effects, preferably, the method for preparing the plugging material with slow-release and dispersing effects further comprises: fully contacting the porous silica microspheres loaded with polyacrylamide with starch powder and then wetting them to obtain the core.

[0034] In the above-mentioned method for preparing the plugging material with slow-release dispersing effect, preferably, the method for preparing the plugging material with slow-release dispersing effect further comprises: fully contacting the silica porous microspheres loaded with polyacrylamide with a molten mixture of paraffin wax and water-absorbing resin to obtain the core.

[0035] The present invention also provides a use of the above-mentioned plugging material with slow-release dispersing effect or the plugging material with slow-release dispersing effect obtained from the above-mentioned plugging material with slow-release dispersing effect in drilling plugging.

[0036] The plugging material with slow-release dispersing effect provided by the present invention includes two parts: a core and an outer shell. The outer shell is a fully enclosed structure that can effectively coat the silica porous microspheres inside it. When preparing the plugging slurry and just injecting it into the wellbore, the viscosity of the plugging slurry will not increase; as the plugging material descends, due to long-term immersion, the outer shell falls off, exposing the disintegrating inner shell inside it. Since the disintegrating inner shell is made of paraffin and water-absorbing resin, it begins to dissolve and fall off in the high-temperature environment underground, gradually exposing the inner core. The powdered polyacrylamide in the silica porous microspheres is released to increase the viscosity of the plugging slurry, thereby improving the suspension and dispersibility of the solid-phase particles as the main plugging material. In addition, the silica porous microspheres and inorganic particles can act as solid-phase particles to participate in plugging.

[0037] In addition, since the porous silica microspheres have a porous capillary structure, when the outer shell falls off and the inner core is exposed, the powdered polyacrylamide is in the pores of the porous silica microspheres, which slows down the loss rate and achieves a long-lasting slow-release effect. Moreover, the presence of starch paste in the pores further slows down the loss rate of the powdered polyacrylamide, that is, it can maintain the high viscosity of the plugging slurry near the leakage layer for a long time.

[0038] The technical solution provided by the present invention has the following beneficial effects:

[0039] The plugging material with a slow-release dispersing effect prepared by the present invention comprises a core and an outer shell. The outer shell has a fully enclosed structure that can effectively cover the inner core. When the plugging slurry is prepared and immediately injected into the wellbore, the viscosity of the plugging slurry does not increase, thus facilitating smooth flow of the plugging slurry into the wellbore. After continuous soaking, when the plugging material descends to the vicinity of the leakage zone, the outer shell gradually falls off, releasing the powdered polyacrylamide in the core to increase the viscosity of the plugging slurry, thereby improving the suspension and dispersibility of the solid-phase particles that serve as the main plugging material. The core and inorganic particles can act as solid-phase particles to participate in the plugging. In addition, because the core has a porous capillary structure, when the outer shell falls off and the core is exposed, the powdered polyacrylamide is trapped in the pores of the core, slowing the dissipation rate and achieving a slow-release, long-lasting effect. That is, it can maintain the high viscosity of the plugging slurry near the leakage zone for a long time. DETAILED DESCRIPTION

[0040] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

[0041] Example 1

[0042] This embodiment provides a method for preparing a plugging material with a slow-release dispersing effect, comprising the following steps:

[0043] S1. Prepare porous silica microspheres with a porous capillary structure and control their particle size to 0.5 mm:

[0044] S11, pouring 50 parts by weight of dimethyldichlorosilane into a beaker, adding 18 parts by weight of 45 wt% concentrated hydrochloric acid to the beaker, and stirring at 45° C. for 35 minutes to obtain oily octamethylcyclotetrasiloxane;

[0045] S12, taking 25 parts by weight of the octamethylcyclotetrasiloxane prepared in step S11, mixing it with 9 parts by weight of 30 wt% ammonia water, heating and stirring at 37° C. for 22 minutes, filtering, and washing with anhydrous ethanol to obtain octamethylcyclotetrasiloxane polymerized microspheres;

[0046] S13, calcining the octamethylcyclotetrasiloxane polymer microspheres obtained in step S12 at a temperature of 600° C. for 65 min, removing the microspheres and allowing them to cool naturally to obtain porous silica microspheres having a porous capillary structure and a particle size of 0.5 mm;

[0047] S2. Prepare the kernel:

[0048] S21, taking 1 part by weight of the porous silica microspheres obtained in step S13, placing them into a container containing powdered polyacrylamide, vibrating and stirring them, and then taking them out to obtain a first treated product, wherein the first treated product contains 17 parts by weight of powdered polyacrylamide;

[0049] S22, then transferring the first treated product to a container containing starch powder and vibrating and stirring, taking it out and transferring it to a clean container, sprinkling it with clean water, and draining it naturally to obtain a second treated product, wherein the second treated product contains 22 parts by weight of starch;

[0050] S23, after paraffin is melted, sodium polyacrylate water-absorbing resin is added thereto to obtain a melt, wherein the mass ratio of paraffin wax and sodium polyacrylate water-absorbing resin in the melt is 32:27 for example; the second processed material is placed into the melt and rolled with stirring, taken out and naturally drained to obtain a kernel containing 32 parts by weight of paraffin wax and 27 parts by weight of sodium polyacrylate water-absorbing resin in the kernel;

[0051] S3. Mix 42 parts by weight of clay, 17 parts by weight of calcium carbonate powder (particle size 13 microns) and 13 parts by weight of water to form a paste, take 5 parts by weight of the core obtained in step S23 and put it into the paste, mix and stir for 5 minutes, then take it out, drain, and then dry to obtain plugging material A1. The obtained plugging material A1 includes an outer shell and a core, and the mass ratio of the outer shell to the core is 1:4.6.

[0052] Example 2

[0053] This embodiment provides a method for preparing a plugging material with a slow-release dispersing effect, comprising the following steps:

[0054] S1. Prepare porous silica microspheres with a porous capillary structure and control their particle size to 0.4 mm:

[0055] S11, pouring 45 parts by weight of dimethyldichlorosilane into a beaker, adding 15 parts by weight of 45 wt% concentrated hydrochloric acid to the beaker, and stirring at 40° C. for 30 minutes to obtain oily octamethylcyclotetrasiloxane;

[0056] S12, taking 20 parts by weight of the octamethylcyclotetrasiloxane prepared in step S11, mixing it with 8 parts by weight of 30 wt% ammonia water, heating and stirring at 35° C. for 20 minutes, filtering, and washing with anhydrous ethanol to obtain octamethylcyclotetrasiloxane polymerized microspheres;

[0057] S13, calcining the octamethylcyclotetrasiloxane polymer microspheres obtained in step S12 at a temperature of 500° C. for 60 min, removing the microspheres and allowing them to cool naturally to obtain porous silica microspheres; testing showed that the porous silica microspheres had a porous capillary structure and a particle size of 0.4 mm;

[0058] S2. Prepare the kernel:

[0059] S21, taking 1 part by weight of the porous silica microspheres obtained in step S13, placing them into a container containing powdered polyacrylamide, vibrating and stirring them, and then taking them out to obtain a first treated product, wherein the first treated product contains 16 parts by weight of powdered polyacrylamide;

[0060] S22, then transferring the first treated product to a container containing starch powder and vibrating and stirring, taking it out and transferring it to a clean container, sprinkling it with clean water, and draining it naturally to obtain a second treated product, wherein the second treated product contains 20 parts by weight of starch;

[0061] S23, after paraffin is melted, sodium polyacrylate water-absorbing resin is added thereto to obtain a melt, wherein the mass ratio of paraffin wax and sodium polyacrylate water-absorbing resin in the melt is, for example, 15:13; the second processed material is placed into the melt and rolled with stirring, taken out and naturally drained to obtain a kernel containing 30 parts by weight of paraffin wax and 26 parts by weight of sodium polyacrylate water-absorbing resin in the kernel;

[0062] S3. Mix 40 parts by weight of clay, 15 parts by weight of calcium carbonate powder (particle size 10 microns) and 12 parts by weight of water to form a paste, add 5 parts by weight of the core obtained in step S23 into the paste and mix and stir for 3 minutes, then take out and drain, and then dry to obtain plugging material A2. The obtained plugging material A2 includes an outer shell and an inner core, and the mass ratio of the outer shell to the inner core is 1:5.

[0063] Example 3

[0064] This embodiment provides a method for preparing a plugging material with a slow-release dispersing effect, comprising the following steps:

[0065] S1. Prepare porous silica microspheres and control their particle size to 0.6 mm:

[0066] S11, pouring 55 parts by weight of dimethyldichlorosilane into a beaker, adding 20 parts by weight of 45 wt% concentrated hydrochloric acid to the beaker, and stirring at 50° C. for 40 minutes to obtain octamethylcyclotetrasiloxane in an oily state;

[0067] S12, taking 30 parts by weight of the octamethylcyclotetrasiloxane prepared in step S11, mixing it with 10 parts by weight of 30 wt% ammonia water, heating and stirring at 38° C. for 25 minutes, filtering, and washing with anhydrous ethanol to obtain octamethylcyclotetrasiloxane polymerized microspheres;

[0068] S13, calcining the octamethylcyclotetrasiloxane polymerized microspheres obtained in step S12 at a temperature of 700° C. for 70 minutes, removing the microspheres and allowing them to cool naturally to obtain porous silica microspheres; testing showed that the porous silica microspheres had a porous capillary structure and a particle size of 0.6 mm;

[0069] S2. Prepare the kernel:

[0070] S21, taking 1 part by weight of the porous silica microspheres obtained in step S13, placing them into a container containing powdered polyacrylamide, vibrating and stirring them, and then taking them out to obtain a first treated product, wherein the first treated product contains 18 parts by weight of powdered polyacrylamide;

[0071] S22, then transferring the first treated product to a container containing starch powder and vibrating and stirring, taking it out and transferring it to a clean container, sprinkling it with clean water, and draining it naturally to obtain a second treated product, wherein the second treated product contains 24 parts by weight of starch;

[0072] S23, after paraffin is melted, a water-absorbing resin is added thereto to obtain a melt, wherein the mass ratio of paraffin wax to sodium polyacrylate water-absorbing resin in the melt is, for example, 17:14; the second treated material is placed into the melt and rolled with stirring, taken out and naturally drained to obtain a kernel containing 34 parts by weight of paraffin wax and 28 parts by weight of sodium polyacrylate water-absorbing resin;

[0073] S3. Mix 45 parts by weight of clay, 18 parts by weight of calcium carbonate powder (particle size 16 microns) and 14 parts by weight of water to form a paste. Add the core obtained in step S23 to the paste and mix and stir for 7 minutes. Then take it out, drain it, and dry it to obtain plugging material A3. The obtained plugging material A3 includes an outer shell and a core, and the mass ratio of the outer shell to the core is 1:4.

[0074] Comparative Example 1

[0075] This comparative example provides a preparation method of a leak-proof material, which is the same as that of Example 1, except that the weight portion of the powdered polyacrylamide is 6 parts, thereby obtaining a leak-proof material D1.

[0076] Comparative Example 2

[0077] This comparative example provides a method for preparing a leak-proof material, which is the same as that of Example 1, except that steps S22 and S23 are omitted, ie, the starch bonding layer and the resin protective layer are not provided, to obtain a leak-proof material D2.

[0078] Comparative Example 3

[0079] This comparative example provides a preparation method of a leak-proof material, which is the same as that of Example 1, except that step S3 is omitted, that is, the outer shell is not provided, to obtain a leak-proof material D3.

[0080] Experimental example

[0081] The deeper the oil well, the higher its temperature. This experiment simulates different depths of the oil well at different temperatures.

[0082] Preparation of plugging slurry: by weight, at room temperature, add 100 parts by weight of water, 4 parts by weight of bentonite, and 20 parts by weight of plugging material to an enamel measuring cup, wherein the plugging materials are the plugging materials obtained in the above Examples 1-3 and Comparative Examples 1-3, respectively, and stir to obtain six parts of plugging slurry.

[0083] The plugging slurry was heated to 25°C, 50°C and 80°C respectively, and after being fully stirred at different temperatures, its dynamic shear force was measured to indicate its viscosity. The results are shown in Table 1.

[0084] Table 1 Viscosity properties of plugging slurry

[0085]

[0086] As can be seen from the experimental results in Table 1, for the plugging materials A1-A3 of Examples 1-3, as the temperature increases, the dynamic shear force of the prepared plugging slurry increases. At 25°C, the dynamic shear force of the plugging slurry is only 0.17, indicating that the plugging slurry at this time has good fluidity and can flow smoothly and quickly into the well; when the temperature rises to 50°C, the dynamic shear force of the plugging slurry only increases slightly; when the temperature rises to 80°C, its dynamic shear force reaches 0.43, indicating that the viscosity of the plugging slurry has increased, which can better suspend and disperse the solid phase particles therein, thereby improving its plugging effect. It can be seen that the plugging materials prepared in Examples 1-3 of the present invention have a good slow-release dispersion effect with temperature.

[0087] For the plugging material D1 of comparative example 1, since it is simply a mixture of porous silica microspheres and powdered polyacrylamide, the plugging slurry has a high dynamic shear force at the beginning, which will affect the efficiency of the plugging slurry flowing into the well and make it difficult to transport the solid phase particles to the underground leakage layer.

[0088] The plugging material D2 of Comparative Example 2 lacked a starch adhesive layer and a resin protective layer, and the plugging material D3 of Comparative Example 3 lacked an outer shell. In both cases, the porous silica microspheres were exposed to the slurry prematurely, releasing polyacrylamide, which prematurely increased the viscosity of the plugging slurry and affected its effectiveness.

[0089] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A plugging material with a slow-release dispersing effect, comprising a core and a shell in a mass ratio of (4-5):1; The inner core comprises porous silica microspheres, and polyacrylamide is adhered to the pores of the porous silica microspheres, wherein: The mass ratio of the porous silica microspheres to polyacrylamide is 1:(16-18); The shell is made of a mixture of clay and inorganic particles.

2. The plugging material with slow-release dispersing effect according to claim 1, wherein: The porous silica microspheres have a porous capillary structure.

3. The plugging material with slow-release dispersing effect according to claim 1, wherein: The polyacrylamide is in powder form.

4. The plugging material with slow-release dispersing effect according to claim 1, wherein: The inner core further comprises, from the inside to the outside, a starch bonding layer and / or a resin protective layer coated on the surface of the porous silica microspheres.

5. The plugging material with slow-release dispersing effect according to claim 1, wherein: The inner core comprises a starch bonding layer and a resin protective layer coated on the surface of the porous silica microspheres from the inside to the outside.

6. The plugging material with slow-release dispersing effect according to claim 4 or 5, wherein: The mass ratio of the porous silica microspheres, the starch bonding layer and the resin protective layer is 1:(20-24):(59-62).

7. The plugging material with slow-release dispersing effect according to claim 5, wherein: The resin protective layer comprises paraffin wax and water-absorbing resin in a mass ratio of (30-34): (26-28).

8. The plugging material with slow-release dispersing effect according to claim 7, wherein: The water-absorbing resin is sodium polyacrylate.

9. The plugging material with slow-release dispersing effect according to claim 1, wherein: The shell has a fully enclosed structure; the mass ratio of clay and inorganic particles in the shell is (40-45): (15-18).

10. The plugging material with slow-release dispersing effect according to claim 1, wherein: The inorganic particles are calcium carbonate powder.

11. The plugging material with slow-release dispersing effect according to claim 1, wherein: The particle size of the inorganic particles is 10-16 μm.

12. A method for preparing the plugging material with slow-release dispersing effect according to any one of claims 1 to 11, comprising the following steps: Preparation of porous silica microspheres; loading polyacrylamide into the pores of the porous silica microspheres to obtain an inner core; The paste containing clay and inorganic particles is coated on the surface of the inner core and dried to obtain the plugging material with slow-release dispersing effect.

13. The method for preparing the plugging material with slow-release dispersing effect according to claim 12, wherein: The preparation method of the porous silica microspheres comprises the following steps: A first reaction of dimethyldichlorosilane with hydrochloric acid yields an oily substance; allowing the oil to undergo a second reaction with aqueous ammonia, filtering out a solid product to obtain semi-finished microspheres; The semi-finished microspheres are calcined and cooled to obtain the porous silica microspheres.

14. The method for preparing the plugging material with slow-release dispersing effect according to claim 13, wherein: The method for preparing porous silica microspheres further comprises: after the second reaction, washing the filtered solid product with anhydrous ethanol.

15. The method for preparing the plugging material with slow-release dispersing effect according to claim 13, wherein: The mass ratio of dimethyldichlorosilane to hydrochloric acid is (45-55): (15-20); the mass concentration of the hydrochloric acid is 42-48wt%.

16. The method for preparing the plugging material with slow-release dispersing effect according to claim 13, wherein: The reaction temperature of the first reaction is 40-50° C., and the reaction time is 30-40 min.

17. The method for preparing the leak-proof material with slow-release dispersing effect according to claim 13, wherein: The mass ratio of the oily substance to the ammonia water is (20-30): (8-10); the mass concentration of the ammonia water is 28-32 wt%.

18. The method for preparing a leak-proof material with a slow-release dispersing effect according to claim 13, wherein: The reaction temperature of the second reaction is 35-38° C., and the reaction time is 20-25 min.

19. The method for preparing a leak-proof material with a slow-release dispersing effect according to claim 13, wherein: The calcination temperature is 500-700° C., and the calcination time is 60-70 minutes.

20. The method for preparing a leak-proof material with a slow-release dispersing effect according to claim 13, wherein: The method for preparing porous silica microspheres further comprises: washing the filtered solid product with anhydrous ethanol.

21. The method for preparing the leak-proof material with slow-release dispersing effect according to claim 12, wherein: The method for preparing the plugging material with slow-release dispersing effect further comprises: fully contacting the porous silica microspheres loaded with polyacrylamide with starch powder and then wetting them to obtain the core.

22. The method for preparing the leak-proof material with slow-release dispersing effect according to claim 12, wherein: The method for preparing the plugging material with slow-release dispersing effect further comprises: fully contacting the porous silica microspheres loaded with polyacrylamide with a molten mixture of paraffin wax and water-absorbing resin to obtain the core.

23. Use of the plugging material with slow-release dispersing effect according to any one of claims 1 to 11 or the plugging material with slow-release dispersing effect obtained by the preparation method according to any one of claims 12 to 22 in drilling plugging.

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