Plugging composition as well as preparation method and application thereof

Abstract

The invention discloses a plugging composition as well as a preparation method and application thereof. The plugging composition comprises the following raw materials in parts by mass: 15-30 parts of an organic monomer, 8-15 parts of a reinforcing monomer, 1-5 parts of an initiator, 0.5-4 parts of a cross-linking agent, 2-6 parts of a dispersing agent, 1-3 parts of a stabilizer and 100 parts of water. The elastic microsphere plugging composition provided by the invention not only has good compatibility with the oil-based drilling fluid, but also does not influence the rheological property, sedimentation stability and emulsion stability of the oil-based drilling fluid. By adopting an inverse emulsion polymerization method, the prepared nano-micron elastic microsphere plugging composition can have a better plugging effect by utilizing elastic deformation generated under the action of pressure difference, meanwhile, the temperature resistance of the composition can reach 220 DEG C, and the composition can be applied to a deep layer and an ultra-deep layer and has a good application prospect. Good temperature-resistant and salt-resistant effects are achieved.

Description

Technical Field

[0001] The invention relates to a plugging composition and a preparation method and application thereof. Background Art

[0002] In the exploration and development of unconventional oil and gas resources at home and abroad, leakage, instability of wellbore, collapse, and stuck drill are often encountered. Such situations usually lead to extended drilling cycles, increased drilling costs, and even wellbore scrapping, which cannot achieve the purpose of exploration and development, thus causing huge economic losses. Oil-based drilling fluids are widely used in complex formations, such as shale oil, gas reservoirs / tight oil, gas reservoirs, deep wells, ultra-deep wells, high-temperature and ultra-high-temperature formations, and complex salt formations. Due to the development of micro-cracks in mud and shale formations, the micro-cracks vary in width and shape, and most of the pores and cracks are at the micro-nano level. Drilling fluid filtrate, drilling fluid infiltration, and drilling fluid pressure transmission have become important reasons for the instability of the wellbore in mud and shale formations.

[0003] Aiming at the plugging problem of micro-cracks and micropores at the micro and nano level, many scholars at home and abroad have devoted themselves to the research of different types of nano and micro plugging agents, and have achieved certain results. At present, the plugging materials used in oil-based drilling fluids are mostly hydrophilic bridge plug materials. However, this type of material has poor compatibility in oil-based drilling fluids, poor pressure bearing capacity, and is mostly non-elastic plugging agents, which will cause the formed plugging layer to be unable to adapt to the deformation of the pores and cracks, thereby affecting the plugging effect.

[0004] Chinese patent CN105462568A provides a resin nanoparticle latex plugging agent for drilling fluid. After the plugging agent is added to the drilling fluid, it basically does not affect the rheological properties of the drilling fluid, and at the same time can significantly improve the plugging ability of the drilling fluid and reduce the filtration loss of the drilling fluid. However, the temperature resistance of the resin nanoparticle latex plugging agent only reaches 150°C, which is difficult to meet the deep high-temperature application requirements of oil-based drilling fluid.

[0005] Chinese patent 201410602573.1 discloses a method for preparing a while-drilling plugging agent for oil-based drilling fluid. The product invented by this method has a particle size of 1μm-100μm and a temperature resistance of up to 150°C. It can quickly and effectively plug the permeability loss of micron-level cracks and pores during the drilling of oil-based drilling fluid. However, the applicable formation temperature is only 150°C, which cannot meet the plugging requirements for high-temperature formations.

[0006] Chinese patent CN109666464A adopts the inverse emulsion polymerization method to cross-link and polymerize the hydrophilic monomer 2-acrylamido-2-methylpropanesulfonic acid, alkyl acrylamide, acrylamide, and the cross-linking agent N,N-methylenebisacrylamide and divinylbenzene to form a plugging polymer fluid loss reducer for water-based drilling fluid, which has a temperature resistance of up to 170°C, but has poor compatibility with oil-based drilling fluid, and cannot guarantee the emulsification stability and rheological properties of the system. Summary of the invention

[0007] In order to at least partially solve the above-mentioned technical problems existing in the prior art, the embodiment of the present invention provides a plugging composition with a small particle size, good elastic deformation performance and plugging effect and a preparation method thereof, so as to achieve the purpose of stabilizing the well wall and reducing the consumption of oil-based drilling fluid.

[0008] As one aspect of the present invention, a plugging composition is provided, which comprises the following constituent raw materials, measured by mass: 15 to 30 parts of an organic monomer, 8 to 15 parts of a reinforcing monomer, 1 to 5 parts of an initiator, 0.5 to 4 parts of a cross-linking agent, 2 to 6 parts of a dispersant, 1 to 3 parts of a stabilizer and 100 parts of water.

[0009] In one or some possible embodiments, the organic monomer is an acrylic monomer and / or an alkenyl amide monomer.

[0010] In one or some possible embodiments, the reinforcing monomer is selected from one or more of 2-acrylamido-2-methylpropanesulfonic acid, N-trimethylolmethyl acrylamide or 3-cyclohexylaminopropanesulfonic acid.

[0011] In one or some possible embodiments, the initiator is bisulfite and / or peroxymonosulfate.

[0012] In one or some possible embodiments, the initiator is selected from one or more of sodium bisulfite, potassium bisulfite, ammonium peroxymonosulfate or potassium peroxymonosulfate.

[0013] In one or some possible embodiments, the cross-linking agent is selected from one or more of hydroxyethyl methacrylate, hydroxypropyl methacrylate, diacetone acrylamide or hydroxyethyl acrylate.

[0014] In one or some possible embodiments, the dispersant is selected from one or more of calcium dihydrogen phosphate, dipotassium hydrogen phosphate or ammonium dihydrogen phosphate.

[0015] In one or some possible embodiments, the stabilizer is selected from one or more of sodium carbonate, sodium bicarbonate or potassium bicarbonate.

[0016] As another aspect of the present invention, it relates to a method for preparing the above-mentioned plugging composition, the method comprising the following steps:

[0017] S1. Add organic monomer, reinforcing monomer, crosslinking agent, dispersant, stabilizer and initiator to water in order according to the formula amount, stir and mix to obtain an aqueous phase solution;

[0018] S2. Under stirring conditions, drop the aqueous solution prepared in S1 into the heated oil phase. After the dropwise addition is completed, continue stirring for a certain period of time, let stand to separate the layers, take the lower layer of reaction product, dry it, and then crush it to obtain a plugging composition.

[0019] In one or some possible embodiments, in S2, the temperature of the heated oil phase is 60-90° C.;

[0020] The oil phase is selected from one or more of 3# white oil, 5# white oil, diesel, gas-to-liquid oil or vegetable oil.

[0021] In one or some possible embodiments, in S2, the volume ratio of the aqueous phase solution to the oil phase is (3-5):(5-9).

[0022] In one or some possible embodiments, in S2, the stirring rate is 1600-2000 r / min, and the stirring time is 0.5-1.5 h.

[0023] In one or some possible embodiments, in S2, the standing time is 1 to 2 hours.

[0024] In one or some possible embodiments, in S2, the particle size of the reaction product is 800 μm to 2 mm; and the particle size of the plugging composition is 300 nm to 200 μm.

[0025] As another aspect of the present invention, it relates to the use of the plugging composition in oil-based drilling fluid.

[0026] As another aspect of the present invention, it relates to an oil-based drilling fluid, which comprises the plugging composition prepared by the above method; wherein the addition amount of the plugging composition is 1-2 wt %.

[0027] As another aspect of the present invention, it relates to an oil-based drilling process, wherein the oil-based drilling process uses the above-mentioned oil-based drilling fluid.

[0028] The beneficial effects of the above technical solution provided by the embodiment of the present invention include at least:

[0029] 1) The elastic microsphere plugging composition prepared by the present invention not only has good compatibility with the oil-based drilling fluid, but also does not affect the rheological properties, sedimentation stability and emulsification stability of the oil-based drilling fluid.

[0030] 2) The elastic microsphere plugging composition of the present invention introduces the rigid groups of the reinforcing monomers, the stabilizer carbide and the water-soluble initiator and the crosslinking agent reaction, thereby improving the crosslinking degree and strength of the polymer itself, thereby improving the temperature resistance of the elastic microsphere plugging composition.

[0031] 3) The elastic microsphere plugging composition prepared by the present invention has good adaptability to pore throat size and certain deformability. Under the pressure difference of the wellbore or well wall, the composition will deform to adapt to cracks of different shapes and sizes. For pores and throats with a large size distribution range, it will have a good plugging effect, thereby effectively plugging the cracks in the layer wall, reducing the filtration loss and loss of the oil-based drilling fluid, so as to improve the stability of the well wall, reduce the occurrence of complex problems downhole, and thus reduce the comprehensive cost of the oil-based drilling fluid.

[0032] 4) The present invention adopts the method of reverse emulsion polymerization to prepare the nano-micron elastic microsphere plugging composition. By controlling the particle size between 300nm-200μm, the elastic deformation generated under the pressure difference can be utilized, so that the composition has a better plugging effect.

[0033] 5) The elastic microsphere plugging composition prepared by the present invention has a temperature resistance of up to 220°C, can be used in deep and ultra-deep layers, and has good temperature and salt resistance effects.

[0034] 6) The elastic microsphere plugging composition prepared by the present invention can directly obtain a relatively uniform product with a small particle size after polymerization. The preparation method is relatively simple, the equipment requirements are low, and the product quality is controllable.

[0035] 7) The oil-based drilling fluid of the present invention can obtain better filtration reduction effect and plugging ability with only a small amount of elastic microsphere plugging composition, has better economic benefits, and is conducive to the promotion and application of the product.

[0036] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0038] Figure 1 This is a schematic diagram of preparing a plugging composition S1 according to an embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram of preparing the plugging composition S2 according to an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0041] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0042] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which the invention belongs. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0043] In the description of the present invention, it should be noted that the terms "include", "including", "have", "contain" and the like are open terms, meaning including but not limited to.

[0044] The present invention is further described below in conjunction with specific examples, and the protection scope of the present invention is not limited by the following examples. The sources of materials mainly involved in the examples are all conventional commercial products.

[0045] Example 1

[0046] See attached Figure 1 , 2 The plugging composition of this embodiment is prepared by the following steps:

[0047] S1. Add 15 g of sodium acrylate (organic monomer), 7.5 g of N-trimethylol methacrylamide (reinforcement monomer), 2 g of hydroxypropyl methacrylate (crosslinking agent), 2 g of ammonium dihydrogen phosphate (dispersant), 1 g of sodium carbonate (stabilizer), and 1 g of ammonium permonosulfate (initiator) to 50 g of distilled water, stir and mix to obtain an aqueous solution;

[0048] S2. Control the stirring rate to 1800r / min. Under stirring conditions, drop the aqueous solution prepared in S1 into the oil phase (a mixture of 3# white oil and 5# white oil) heated to 80°C at a volume ratio of 1:1 between the aqueous phase and the oil phase. After the addition is completed, continue stirring for 0.8h, let it stand for 1.5h, separate the layers, take the reaction product of the lower layer, and crush it after drying to obtain a plugging composition.

[0049] Example 2

[0050] See attached Figure 1 , 2 The plugging composition of this embodiment is prepared by the following steps:

[0051] S1. Add 11 g acrylamide (organic monomer), 6 g 3-cyclohexylaminopropanesulfonic acid (enhancing monomer), 1 g diacetone acrylamide (cross-linking agent), 2 g monocalcium phosphate (dispersant), 1 g sodium bicarbonate (stabilizer), and 1 g sodium bisulfite (initiator) to 50 g distilled water, stir and mix to obtain an aqueous solution;

[0052] S2. Control the stirring rate to 1600r / min. Under stirring conditions, add the aqueous solution prepared in S1 to the oil phase (a mixture of 3# white oil and gas-to-oil) heated to 70°C at a volume ratio of 1:2. After the addition is completed, continue stirring for 1h, let it stand for 1h, separate the layers, take the lower layer of reaction product, dry it and crush it to obtain a plugging composition.

[0053] Example 3

[0054] See attached Figure 1 , 2 The plugging composition of this embodiment is prepared by the following steps:

[0055] S1, to 50g of distilled water, 7.5g of acrylamide and sodium acrylate (organic monomers), 4g of 2-acrylamido-2-methylpropanesulfonic acid (reinforcement monomer), 0.5g of hydroxyethyl acrylate (cross-linking agent), 1g of dipotassium hydrogen phosphate and ammonium dihydrogen phosphate (dispersant), 0.5g of potassium bicarbonate (stabilizer), 0.5g of potassium permonosulfate and ammonium permonosulfate (initiator) were added in sequence, stirred and mixed to obtain an aqueous solution;

[0056] S2. Control the stirring rate to 2000r / min. Under stirring conditions, add the aqueous solution prepared in S1 to the oil phase (a mixture of 3# white oil and vegetable oil) heated to 70°C at a volume ratio of 1:3 between the aqueous phase and the oil phase. After the addition is completed, continue stirring for 1.5h, let it stand for 1.5h, separate the layers, take the lower layer of reaction product, dry it and crush it to obtain a plugging composition.

[0057] Example 4

[0058] See attached Figure 1 , 2 The plugging composition of this embodiment is prepared by the following steps:

[0059] S1, to 50g of distilled water, add 10g of sodium acrylate (organic monomer), 7.5g of 3-cyclohexylaminopropanesulfonic acid (reinforcement monomer), 2g of diacetone acrylamide (cross-linking agent), 3g of monocalcium phosphate (dispersant), 0.5g of sodium bicarbonate and potassium bicarbonate (stabilizer), 0.5g of sodium bisulfite (initiator), stir and mix to obtain an aqueous solution;

[0060] S2. Control the stirring rate to 2000r / min. Under stirring conditions, add the aqueous solution prepared in S1 to the oil phase (a mixture of 3# white oil and diesel) heated to 85°C at a volume ratio of 1:3. After the addition is completed, continue stirring for 0.6h, let it stand for 2h, separate the layers, take the lower layer of reaction product, dry it and crush it to obtain a plugging composition.

[0061] Comparative Example 1

[0062] The difference between this comparative example and Example 2 is that no reinforcing monomer is contained.

[0063] Comparative Example 2

[0064] The difference between this comparative example and Example 2 is that it does not contain a stabilizer.

[0065] Comparative Example 3

[0066] The difference between this comparative example and Example 2 is that no dispersant is contained.

[0067] The above-mentioned Examples 1 to 4 and Comparative Examples 1 to 3 were applied to oil-based drilling fluids, and the following performance tests were performed. The test results are recorded in the following Table 1;

[0068] The oil-based drilling fluid used is the oil-based drilling fluid for shale oil in Liaohe Oilfield, with an oil-water ratio of 80:02 and a density of 1.70 g / cm 3 The specific formula is: a mixture of white oil and water in a volume ratio of 80:20 + 25% calcium chloride aqueous solution + 2.2% organic soil + 5% emulsifier + 1% quicklime + 2.5% organic lignite + 0.4% polymer filtration reducer + 2.5% asphalt + 0.4% viscosity enhancer + 0.8% wetting agent + barite.

[0069] (1) According to the relevant standards recorded in GB / T 16783.2-2012 "Field Test of Drilling Fluids in the Petroleum and Natural Gas Industry", the performance parameters of the oil-based drilling fluid after adding 1% of the plugging composition at 220±1°C were tested;

[0070] (2) According to the relevant standards recorded in GB / T 16783.2-2012 "Field Test of Drilling Fluids in the Petroleum and Natural Gas Industry", the high temperature and high pressure fluid loss (HTHP) of the oil-based drilling fluid after adding 1% of the plugging composition was measured under the environmental conditions of 150°C and 3.5MPa.

[0071] Table 1 Performance test results

[0072]

[0073] Through Examples 1 to 4, combined with the performance test results of Table 1, it can be seen that the elastic microsphere plugging composition prepared by the present invention has good compatibility with the oil-based drilling fluid and has little effect on the rheology of the system. After adding 1% of the plugging composition, the high-temperature and high-pressure filtration loss is significantly reduced, while the viscosity and shear force remain basically unchanged, the emulsification stability is stable, and it embodies good temperature resistance and plugging performance.

[0074] Combining Example 2 with Comparative Examples 1 to 3, it can be seen that no reinforcing monomer is added to Comparative Example 1. It can be seen from the performance test results of Table 1 that the temperature resistance of the plugging composition is poor, and the high-temperature and high-pressure filtration loss is significantly increased, indicating that the reinforcing monomer mainly affects the high-temperature stability of the plugging composition; no stabilizer is added to Comparative Example 2. It can be seen from the performance test results of Table 1 that the plastic viscosity and dynamic shear force values ​​after aging are greatly reduced, the stability is deteriorated, and the high-temperature and high-pressure filtration loss is significantly increased, indicating that the stabilizer has a greater impact on the high-temperature stability and plugging performance of the plugging composition; no dispersant is added to Comparative Example 3. It can be seen from the performance test results of Table 1 that the plastic viscosity increases significantly after aging and the high-temperature and high-pressure filtration loss increases significantly, indicating that the plugging composition has been high-temperature agglomerated, affecting the high-temperature rheological stability and plugging effect of the system. Based on the above reasons, the inventor believes that the present invention effectively improves the cross-linking degree and strength of the polymer itself by introducing the rigid groups, stabilizers and dispersants of the reinforcing monomers, thereby achieving better temperature resistance and plugging performance.

[0075] In order to verify whether different plugging compositions with different mass contents will produce different performance effects when applied to the same oil-based drilling fluid, the inventors tested the rheological properties, high temperature and high pressure filtration loss and PPA plugging performance of the following Examples 5 to 8 according to the relevant standards recorded in GB / T 16783.2-2012 "Field Test of Drilling Fluids in the Petroleum and Natural Gas Industry", as shown in Table 2.

[0076] Comparative Example 4

[0077] The comparative example is a blank group, and the oil-based drilling fluid used in the blank group is the above-mentioned oil-based drilling fluid for shale oil in Liaohe Oilfield.

[0078] Example 5

[0079] The composition of the oil-based drilling fluid of this example is: blank group + 0.5 wt % of Example 2.

[0080] Example 6

[0081] The composition of the oil-based drilling fluid of this example is: blank group + 1.0 wt% of Example 2.

[0082] Example 7

[0083] The composition of the oil-based drilling fluid of this example is: blank group + 2.0 wt% of Example 2.

[0084] Example 8

[0085] The composition of the oil-based drilling fluid of this example is: blank group + 3.0 wt % of Example 2.

[0086] Table 2 Performance test results

[0087]

[0088] Note: The core filter disc used in the PPA plugging instrument has a specification of 50-200μm, and the high-temperature and high-pressure filter paper is a medium-speed filter paper.

[0089] Through comparative example 4 and examples 5 to 8, combined with the performance test results of Table 2, it can be seen that after adding different amounts of elastic microsphere plugging composition to the oil-based drilling fluid, the rheological properties of the system are less affected, the viscosity and cutting are moderate after aging at 220°C, the emulsification stability and sedimentation stability meet the requirements, and the temperature resistance of the composition can reach 220°C. In addition, under the action of pressure difference, the elastic microsphere plugging composition will deform to adapt to the pore throat of the core filter disc, and the high temperature and high pressure filtration loss will be significantly reduced from 3.8mL to 1.0mL; from the PPA plugging evaluation, the filtration loss is reduced from 6.8mL to 1.4mL, indicating that its plugging effect is good, and it has a good plugging effect on nano- and micron-level cracks. Comprehensively comparing the product's filtration loss reduction and plugging performance, as well as the rheological performance comparison, the optimal addition amount of the product is 1-2%.

[0090] In summary, the elastic microsphere plugging composition prepared by the present invention has good adaptability to pore throat size and certain deformability. Under the pressure difference of the wellbore or well wall, the composition will deform to adapt to cracks of different shapes and sizes. For pores and throats with a large size distribution range, it will have a good plugging effect, thereby effectively plugging the cracks in the layer wall, reducing the loss and loss of oil-based drilling fluid, reducing the occurrence of complex problems downhole, and thus reducing the comprehensive cost of oil-based drilling fluid.

[0091] Although the description of the present invention has been quite detailed and has been described in particular with respect to several described embodiments, it is not intended to be limited to any of these details or embodiments or any particular embodiment, so as to effectively cover the intended scope of the present invention. In addition, the present invention is described above with the embodiments foreseeable by the inventors, and its purpose is to provide a useful description, and those non-substantial changes to the present invention that are not currently foreseen may still represent equivalent changes of the present invention.

[0092] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0093] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A plugging composition, characterized in that: The plugging composition comprises the following raw materials by weight: 15 to 30 parts of organic monomer, 8 to 15 parts of reinforcing monomer, 1 to 5 parts of initiator, 0.5 to 4 parts of cross-linking agent, 2 to 6 parts of dispersant, 1 to 3 parts of stabilizer and 100 parts of water.

2. The plugging composition according to claim 1, characterized in that: The organic monomer is an acrylic monomer and / or an alkenyl amide monomer.

3. The plugging composition according to claim 1, characterized in that: The reinforcing monomer is selected from one or more of 2-acrylamide-2-methylpropanesulfonic acid, N-trimethylol methacrylamide or 3-cyclohexylaminopropanesulfonic acid.

4. The plugging composition according to claim 1, characterized in that: The initiator is bisulfite and / or peroxymonosulfate.

5. The plugging composition according to claim 4, characterized in that: The initiator is selected from one or more of sodium bisulfite, potassium bisulfite, ammonium peroxymonosulfate or potassium peroxymonosulfate.

6. The plugging composition according to claim 1, characterized in that: The crosslinking agent is selected from one or more of hydroxyethyl methacrylate, hydroxypropyl methacrylate, diacetone acrylamide or hydroxyethyl acrylate.

7. The plugging composition according to claim 1, characterized in that: The dispersant is selected from one or more of calcium dihydrogen phosphate, dipotassium hydrogen phosphate or ammonium dihydrogen phosphate.

8. The plugging composition according to claim 1, characterized in that: The stabilizer is selected from one or more of sodium carbonate, sodium bicarbonate or potassium bicarbonate.

9. A method for preparing the plugging composition according to any one of claims 1 to 10, characterized in that: The method comprises the following steps: S1. Add organic monomer, reinforcing monomer, crosslinking agent, dispersant, stabilizer and initiator to water in order according to the formula amount, stir and mix to obtain an aqueous phase solution; S2. Under stirring conditions, drop the aqueous solution prepared in S1 into the heated oil phase. After the dropwise addition is completed, continue stirring for a certain period of time, let stand to separate the layers, take the lower layer of reaction product, dry it, and then crush it to obtain a plugging composition.

10. The method for preparing the plugging composition according to claim 9, characterized in that: In S2, the temperature of the heated oil phase is 60-90°C; The oil phase is selected from one or more of 3# white oil, 5# white oil, diesel, gas-to-liquid oil or vegetable oil.

11. The method for preparing the plugging composition according to claim 9, characterized in that: In S2, the volume ratio of the aqueous phase solution to the oil phase is (3-5):(5-9).

12. The method for preparing the plugging composition according to claim 9, characterized in that: In S2, the stirring rate is 1600-2000 r / min, and the stirring time is 0.5-1.5 h.

13. The method for preparing the plugging composition according to claim 9, characterized in that: In S2, the standing time is 1 to 2 hours.

14. The method for preparing the plugging composition according to claim 9, characterized in that: In S2, the particle size of the reaction product is 800 μm to 2 mm; the particle size of the plugging composition is 300 nm to 200 μm.

15. Use of the plugging composition according to any one of claims 1 to 8 in oil-based drilling fluid.

16. An oil-based drilling fluid, characterized in that: The oil-based drilling fluid comprises the plugging composition prepared by the method according to any one of claims 9 to 14.

17. The oil-based drilling fluid according to claim 16, characterized in that The addition amount of the plugging composition is 1-2 wt %.

18. An oil-based drilling process, characterized in that: The oil-based drilling process uses the oil-based drilling fluid as claimed in claim 16 or 17.

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