High-pressure-bearing self-adaptive blocking agent for non-water-based drilling fluid and preparation method of high-pressure-bearing self-adaptive blocking agent

Abstract

The invention discloses a high-pressure-bearing self-adaptive plugging agent for non-water-based drilling fluid and a preparation method of the plugging agent. The preparation method comprises the following steps: firstly, uniformly mixing and stirring deionized water and a dispersing agent to obtain a dispersing agent solution; uniformly mixing a short-chain monounsaturated fatty acid ester monomer, a medium-chain monounsaturated fatty acid ester monomer, a long-chain monounsaturated fatty acid ester monomer, a cross-linking agent and an initiator to obtain a mixture; and finally, adding the mixture into the dispersing agent solution, adding the pore-enlarging agent, heating, stirring, filtering, and drying to obtain the plugging agent. The plugging agent prepared by the invention has certain strength, deformability and oil absorption expansion capability, can be stacked and filled in pores with different sizes, improves the well wall strengthening capability of the non-water-based drilling fluid, and improves the technical performance level of the non-water-based drilling fluid.

Description

Technical Field

[0001] The present invention belongs to the field of drilling fluids for drilling operations, and particularly relates to a high-pressure-bearing self-adaptive plugging agent for non-aqueous drilling fluids and a preparation method thereof. Background Art

[0002] Non-aqueous drilling fluids are drilling fluids with white oil, diesel oil or synthetic-based base oil as the continuous phase. Due to their good inhibition, lubricity and high-temperature resistance, they have become the main drilling fluid technology for drilling large-displacement wells offshore. However, with the continuous increase of the horizontal displacement of large-displacement wells, the non-aqueous drilling fluid system faces many challenges. During the operation of large-displacement wells, the filtrate of non-aqueous drilling fluids invades the formation and transmits pressure, forming "hydraulic cutting" in the formation with developed microfractures and microcracks, resulting in collapse and sloughing, and inducing wellbore instability. The plugging agent in the drilling fluid forms an effective plugging layer in the pores and cracks of the lost circulation zone or fractured zone through mechanisms such as bridging, adhesion, and filling, improving the pressure-bearing capacity of the formation wellbore and preventing the loss of drilling fluid and the invasion of solids. Existing technologies include bridging plugging, flexible elastic plugging, cement slurry plugging, etc. However, existing plugging materials generally have problems such as poor self-adaptability and low pressure-bearing strength after plugging. Conventional bridging plugging materials need to select the particle size of the plugging material, and can only plug gaps of specific sizes, making it difficult to effectively plug unknown-sized lost circulation channels, that is, poor self-adaptability; most flexible elastic plugging materials have insufficient pressure-bearing capacity, and are prone to pressure breakthrough and plugging failure when the pressure exceeds 6 MPa. Affected by the blindness of pore distribution in the formation and the insufficient pressure-bearing capacity of the material, it is of great practical significance to carry out research on high-pressure-bearing self-adaptive plugging agents for non-aqueous drilling fluids, which can provide technical support for further drilling large-displacement wells with oil-based and synthetic-based drilling fluids. Summary of the Invention

[0003] The present invention is proposed to solve the problems of poor plugging performance of non-aqueous drilling fluids and insufficient pressure-bearing capacity of the plugging layer when performing broad-spectrum plugging for lost circulation channels in the prior art, and its purpose is to provide a high-pressure-bearing self-adaptive plugging agent for non-aqueous drilling fluids and a preparation method thereof.

[0004] The present invention is achieved through the following technical solutions:

[0005] A preparation method of a high-pressure-bearing self-adaptive plugging agent for non-aqueous drilling fluids, comprising the following steps:

[0006] (i) Mix deionized water and a dispersant and stir evenly to obtain a dispersant solution;

[0007] (ii) Mix a short-chain monounsaturated fatty acid ester monomer, a medium-chain monounsaturated fatty acid ester monomer, a long-chain monounsaturated fatty acid ester monomer, a crosslinking agent and an initiator evenly to obtain a mixture;

[0008] (ⅲ) Add the mixture obtained in step (ⅱ) to the dispersant solution obtained in step (ⅰ), then add a pore-expanding agent, and stir and react at 60 °C to 90 °C and a stirring speed of 300 r / min for 5 h. After the reaction is completed, filter and dry to obtain the plugging agent.

[0009] In the above technical solution, the mass concentration of the dispersant in the dispersant solution is 0.25%.

[0010] In the above technical solution, the dispersant is any one of polyvinyl alcohol 1788, polyvinyl alcohol 0588, or polyvinyl alcohol 2488; the numbers of polyvinyl alcohol 1788, polyvinyl alcohol 0588, and polyvinyl alcohol 2488 represent the thousands and hundreds digits of the degree of polymerization of polyvinyl alcohol and the percentage of alcoholysis degree.

[0011] In the above technical solution, the short-chain monounsaturated fatty acid ester monomer is methyl acrylate or ethyl acrylate, and the number of carbon atoms of the short-chain monounsaturated fatty acid ester monomer is no more than 6 (n ≤ 6, n is the number of carbon atoms); the medium-chain monounsaturated fatty acid ester monomer is butyl acrylate or amyl acrylate, and the number of carbon atoms of the medium-chain monounsaturated fatty acid ester monomer is no more than 12 and greater than 6 (6 < n ≤ 12, n is the number of carbon atoms); the long-chain monounsaturated fatty acid ester monomer is lauryl acrylate or octadecyl acrylate, and the number of carbon atoms of the long-chain monounsaturated fatty acid ester monomer is greater than 12 (n > 12, n is the number of carbon atoms).

[0012] In the above technical solution, the short-chain monounsaturated fatty acid ester monomer is methyl methacrylate or methyl acrylate; the medium-chain monounsaturated fatty acid ester monomer is butyl methacrylate or butyl acrylate; the long-chain monounsaturated fatty acid ester monomer is octadecyl methacrylate or octadecyl acrylate.

[0013] In the above technical solution, the mass ratio of the short-chain monounsaturated fatty acid ester monomer, the medium-chain monounsaturated fatty acid ester monomer, and the long-chain monounsaturated fatty acid ester monomer is 5:4:1.

[0014] In the above technical solution, the crosslinking agent is any one of N,N'-methylenebisacrylamide, divinylbenzene, or diallyl phthalate; the initiator is any one of azobisisobutyronitrile, benzoyl peroxide, or tert-butyl peroxybenzoate; the pore-expanding agent is polyethylene glycol or ethyl acetate.

[0015] In the above technical solution, the added mass of the crosslinking agent is 0.17% to 1.2% of the total mass of the short-chain monounsaturated fatty acid ester monomer, the medium-chain monounsaturated fatty acid ester monomer, and the long-chain monounsaturated fatty acid ester monomer; the added mass of the initiator is 2.2% to 4.4% of the total mass of the short-chain monounsaturated fatty acid ester monomer, the medium-chain monounsaturated fatty acid ester monomer, and the long-chain monounsaturated fatty acid ester monomer; the added mass of the pore-expanding agent is 16.7% to 33.3% of the total mass of the short-chain monounsaturated fatty acid ester monomer, the medium-chain monounsaturated fatty acid ester monomer, and the long-chain monounsaturated fatty acid ester monomer.

[0016] In the above technical solution, the mass ratio of the total mass of the short-chain monounsaturated fatty acid ester monomer, the medium-chain monounsaturated fatty acid ester monomer, and the long-chain monounsaturated fatty acid ester monomer to the mass of the dispersant solution is 3:8 or 3:16.

[0017] A high-pressure-bearing self-adaptive plugging agent for non-aqueous drilling fluid is prepared by the foregoing method.

[0018] In the above technical solution, the molecular structure of the plugging agent is as follows formula (Ⅰ):

[0019]

[0020] In formula (Ⅰ): the value range of x is 6 to 12, and the value range of y is 13 to 24.

[0021] The beneficial effects of the present invention are:

[0022] The present invention provides a high-pressure-bearing self-adaptive plugging agent for non-aqueous drilling fluid and a preparation method thereof. The high-pressure-bearing self-adaptive plugging agent realizes the copolymerization of the short-chain monounsaturated fatty acid ester monomer, the medium-chain monounsaturated fatty acid ester monomer, and the long-chain monounsaturated fatty acid ester monomer by suspension polymerization. The material particles themselves have good toughness, can deform according to the pores, enter the formation under the action of differential pressure, and form effective filling; the resin particles squeezed into the pores continuously absorb oil, the volume gradually expands, adaptively fill and plug the pores, thereby improving the pressure-bearing capacity and forming a better plugging effect. Specific embodiments

[0023] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below through specific embodiments.

[0024] Example 1

[0025] A preparation method of a high-pressure-bearing self-adaptive plugging agent for non-aqueous drilling fluid includes the following steps:

[0026] a. Add 80 g of deionized water and 0.2 g of polyvinyl alcohol 1788 to a three-necked flask, add heating and stirring devices, and stir the dispersant until it is uniform to obtain a dispersant solution for use;

[0027] b. Add 15 g of methyl methacrylate, 12 g of butyl acrylate, 3 g of octadecyl methacrylate, 0.18 g of N,N-methylenebisacrylamide, and 0.66 g of azobisisobutyronitrile to a beaker, and mix them evenly through an ultrasonic device;

[0028] c. Add the mixture obtained in b to the dispersant solution obtained in a, add 5 g of polyethylene glycol, adjust the reaction temperature to 60 °C, and stir and react for 5 h;

[0029] d. Filter the product after the reaction in c and dry it at 50 °C for 12 h to obtain plugging agent 1.

[0030] Example 2

[0031] A preparation method of a high-pressure-bearing self-adaptive plugging agent for non-aqueous drilling fluid, comprising the following steps:

[0032] a. Add 80 g of deionized water and 0.2 g of polyvinyl alcohol 1788 to a three-necked flask, add heating and stirring devices, and stir the dispersant until it is uniform to obtain a dispersant solution for use;

[0033] b. Add 15 g of methyl acrylate, 12 g of butyl methacrylate, 3 g of lauryl acrylate, 0.18 g of N,N-methylenebisacrylamide, and 0.66 g of azobisisobutyronitrile to a beaker, and mix them evenly through an ultrasonic device;

[0034] c. Add the mixture obtained in b to the dispersant solution obtained in a, add 5 g of polyethylene glycol, adjust the reaction temperature to 60 °C, and stir and react for 5 h;

[0035] d. Filter the product after the reaction in c and dry it at 50 °C for 12 h to obtain plugging agent 2.

[0036] Example 3

[0037] A preparation method of a high-pressure-bearing self-adaptive plugging agent for non-aqueous drilling fluid, comprising the following steps:

[0038] a. Add 80 g of deionized water and 0.2 g of polyvinyl alcohol 1788 to a three-necked flask, add heating and stirring devices, and stir the dispersant until it is uniform to obtain a dispersant solution for use;

[0039] b. Add 15 g of methyl acrylate, 12 g of butyl methacrylate, 3 g of octadecyl methacrylate, 0.18 g of N,N-methylenebisacrylamide, and 0.66 g of azobisisobutyronitrile to a beaker, and mix them evenly through an ultrasonic device;

[0040] c. Add the mixture obtained in b to the dispersant solution obtained in a, add 5 g of polyethylene glycol, adjust the reaction temperature to 60 °C, and stir and react for 5 h;

[0041] d. Filter the product after the reaction in c and dry it at 50 °C for 12 h to obtain the plugging agent 3.

[0042] Comparative Example 1

[0043] A preparation method of a high-pressure-bearing self-adaptive plugging agent for non-aqueous drilling fluid, comprising the following steps:

[0044] a. Add 80 g of deionized water and 0.2 g of polyvinyl alcohol 1788 to a three-necked flask, add heating and stirring devices, and stir the dispersant until uniform to obtain a dispersant solution for use;

[0045] b. Add 12 g of butyl methacrylate, 3 g of octadecyl acrylate, 0.18 g of N,N-methylenebisacrylamide, and 0.66 g of azobisisobutyronitrile to a beaker, and mix them evenly through an ultrasonic device;

[0046] c. Add the mixture obtained in b to the dispersant solution obtained in a, add 5 g of polyethylene glycol, adjust the reaction temperature to 60 °C, and stir and react for 5 h;

[0047] d. Filter the product after the reaction in c and dry it at 50 °C for 12 h to obtain the comparative plugging agent 1.

[0048] Comparative Example 2

[0049] a. Add 80 g of deionized water and 0.2 g of polyvinyl alcohol 1788 to a three-necked flask, add heating and stirring devices, and stir the dispersant until uniform to obtain a dispersant solution for use;

[0050] b. Add 15 g of methyl acrylate, 12 g of butyl methacrylate, 3 g of octadecyl methacrylate, 0.05 g of N,N-methylenebisacrylamide, and 0.66 g of azobisisobutyronitrile to a beaker, and mix them evenly through an ultrasonic device;

[0051] c. Add the mixture obtained in b to the dispersant solution obtained in a, add 5 g of polyethylene glycol. Adjust the reaction temperature to 80 °C, and stir and react for 5 h;

[0052] d. Filter the product after the reaction in c and dry it at 50 °C for 12 h to obtain the comparative plugging agent 2.

[0053] Test the performance of the plugging agents prepared in Examples 1-3 and Comparative Examples 1 and 2:

[0054] I. Volume expansion rate test

[0055] Disperse resin particles of a certain particle size in diesel or linear α-olefin, swell at 180 °C for 24 h, place them on a filter screen and let them stand for a period of time, filter off the remaining oil with blotting paper, measure the diameter of the particles multiple times, and take the average value.

[0056] The test method for the resin volume swelling rate is shown in Equation (0-1):

[0057]

[0058] In the formula: P is the resin volume swelling rate; D1 is the particle size of the resin particles before swelling; D2 is the particle size of the resin particles after swelling by absorbing oil.

[0059] II. Elastic Modulus Test of Examples

[0060] Use an INSTRON 5967 universal material testing machine from the UK to test the elastic modulus of the examples, with a tensile rate of 2 mm / min. After melting the examples, pour them into a mold to prepare dumbbell-shaped standard parts for testing.

[0061] III. Sand Bed Pressure-bearing Plugging Test

[0062] Prepare a non-aqueous drilling fluid:

[0063] Synthetic-based drilling fluid formula: linear α-olefin + 30% CaCl2 solution (oil-water ratio 80:20) + 8% emulsifier + 2% organic clay + 1% sand-carrying flow pattern regulator + 3% CaO + 3% filtration loss reducer + 4% ultrafine calcium + barite, ρ = 1.7 g / cm 3 ;

[0064] Oil-based drilling fluid formula: diesel + 30% CaCl2 solution (oil-water ratio 85:15) + 6% emulsifier + 2% organic clay + 1% sand-carrying flow pattern regulator + 3% CaO + 6% filtration loss reducer + 4% ultrafine calcium + barite, ρ = 1.3 g / cm 3 ;

[0065] Add 2% of the examples to the prepared drilling fluid and stir at 12,000 r / min for 20 min; put the drilling fluid into an aging tank and place it in a roller heating furnace for aging at 180 °C for 16 h, and conduct a sand bed pressure-bearing plugging test after aging.

[0066] The specific measurement method is as follows:

[0067] (1) Fill 100 g (20 - 40, 40 - 60, 60 - 80 mesh) of quartz sand into a cylindrical sand bed plugging instrument respectively;

[0068] (2) Inject the pre-prepared drilling fluid, tighten the cylindrical plugging instrument and install it on the test bench. Set the temperature to 180 °C, connect the upper part to the hydraulic valve and the lower part to nitrogen, and adjust the air pressure to the target value;

[0069] (3) Open the intake valve rod, and the pressure enters the cylindrical plugging instrument;

[0070] (4) The test starts. Under the push of pressure, the drilling fluid flows into the simulated leakage pores. Apply a pressure of 2 MPa every 3 minutes, and record the cumulative leakage volume (mL) and the maximum bearing pressure (MPa) of the drilling fluid.

[0071] IV. Core Plugging Rate Test

[0072] Use 5 artificial cores with similar porosities and different permeabilities. The permeabilities range from low to high, which are 150 - 250×10 -3 μm 2 , 350 - 450×10 -3 μm 2 , 550 - 650×10 -3 μm 2 , 750 - 850×10 -3 μm 2 and 950 - 1050×10 -3 μm 2 , and evaluate their plugging effects respectively with the prepared non-aqueous drilling fluid.

[0073] The plugging experiment conditions are: temperature at room temperature, pressure difference of 3.5 MPa, shear rate of 100 s -1 , and plugging time of 30 minutes. Measure the core permeability before plugging and the core permeability after plugging respectively, and calculate the plugging rate and the average plugging rate to evaluate the self-adaptive plugging effect of the plugging agent.

[0074] The plugging rate of the core with different permeabilities of the drilling fluid is calculated according to the following formula:

[0075] F 150～250 =(Permeability after plugging - Permeability before plugging) / Permeability before plugging × 100% (0 - 2)

[0076] F 350～450 =(Permeability after plugging - Permeability before plugging) / Permeability before plugging × 100% (0 - 3)

[0077] F 550～650 =(Permeability after plugging - Permeability before plugging) / Permeability before plugging × 100% (0 - 4)

[0078] F 750～850 =(Permeability after plugging - Permeability before plugging) / Permeability before plugging × 100% (0 - 5)

[0079] F 950～1050 =(Permeability after plugging - Permeability before plugging) / Permeability before plugging × 100% (0 - 6)

[0080] The average plugging rate of the drilling fluid is calculated according to the following formula:

[0081] F 平均 =(F 150～250 + F 350～450 + F 550～650 + F 750～850 + F 50～1050 ) / 5 (0 - 7)

[0082] The performance evaluation results are as follows:

[0083] Table 1 shows the test results of the volume swelling rate of the examples and comparative examples in linear α - olefin. It can be seen that Example 1 has good toughness after swelling. The volume swelling rate is 5.86% after soaking in linear α - olefin for 24h, and it still has a relatively high elastic modulus of 25.97MPa after swelling. For Comparative Example 1, short - chain monounsaturated fatty acid ester was not added, and the elastic modulus was relatively low, only 2.43MPa, with poor toughness; for Comparative Example 2, the amount of cross - linker added was insufficient, the cross - linking degree of the material was low, the volume swelling rate was high, and the elastic modulus was also affected. The toughness of Example 1 after swelling is high, superior to the other examples.

[0084] Table 1 Test of Volume Swelling Rate and Elastic Modulus of Examples in Linear α - Olefin

[0085] Test object <![CDATA[D1(mm)]]> <![CDATA[D2(mm)]]> P(％) Elastic modulus (MPa) Example 1 0.50 0.95 5.86 25.97 Example 2 0.50 0.88 4.45 19.45 Example 3 0.50 0.80 3.10 20.67 Comparative example 1 0.50 1.74 41.14 2.43 Comparative example 2 0.50 1.87 51.31 1.36

[0086] Table 2 shows the test results of the volume swelling rate of the examples in diesel. It can be seen that Example 1 has good toughness after swelling. The volume swelling rate is 6.53% after soaking in diesel for 24h, and it still has a relatively high elastic modulus of 24.32MPa after swelling. Considering Table 1 and Table 2 together, Example 1 has good swelling ability and toughness for both the base oil of oil - based drilling fluid and the base oil of synthetic - based drilling fluid, indicating that Example 1 has good compatibility with the base oil of non - water - based drilling fluid.

[0087] Table 2 Test of Volume Swelling Rate and Elastic Modulus of Examples in Diesel

[0088] Test object <![CDATA[D1(mm)]]> <![CDATA[D2(mm)]]> P(％) Elastic modulus (MPa) Example 1 0.50 0.98 6.53 24.32 Example 2 0.50 0.82 3.41 21.33 Example 3 0.50 0.91 5.03 17.64 Comparative example 1 0.50 1.69 37.61 4.17 Comparative example 2 0.50 1.77 43.36 3.48

[0089] Table 3 shows the pressure-bearing test results of the examples for plugging sand beds with different mesh numbers in synthetic-based drilling fluids. It can be seen that Example 1 can effectively fill and plug leakage channels of different sizes, improving the pressure-bearing capacity. After adding 2% of Example 1, the leakage volume of the synthetic-based drilling fluid is controlled. The cumulative leakage volumes in the sand beds of three different mesh numbers are 3.2 mL, 1.1 mL, and 0.8 mL respectively, and the maximum pressure-bearing is 20 MPa. While the blank group can hardly bear pressure, and the leakage volume exceeds 70 mL. The self-adaptive plugging effect and pressure-bearing capacity of Example 1 in the synthetic-based drilling fluid are better than those of the other examples.

[0090] Table 3 Pressure-bearing Plugging Test of Synthetic-based Drilling Fluid Sand Bed

[0091]

[0092] Table 4 shows the pressure-bearing test results of the examples for plugging sand beds with different mesh numbers in oil-based drilling fluids. It can be seen that Example 1 can perform self-adaptive filling and plugging on leakage channels of different sizes, improving the pressure-bearing capacity. After adding 2% of Example 1, the cumulative leakage volumes of the oil-based drilling fluid in the sand beds of three different mesh numbers are 2.3 mL, 0.8 mL, and 0.5 mL respectively, and the maximum pressure-bearing is 20 MPa. While the maximum pressure-bearing of the blank group is 10 MPa, and the minimum cumulative leakage volume is 4.6 mL. The plugging effect is far inferior to the system with 2% of Example 1 added. Considering Table 3 and Table 4 together, Example 1 can bear a pressure of 20 MPa in both synthetic-based drilling fluid and oil-based drilling fluid, and the leakage volume remains at a low level among all examples, indicating that Example 1 has good self-adaptive plugging for non-aqueous drilling fluids and high pressure-bearing capacity after plugging.

[0093] Table 4 Pressure-bearing Plugging Test of Oil-based Drilling Fluid Sand Bed

[0094]

[0095] Table 5 shows the core plugging rate test of synthetic-based drilling fluid. From the above results, it can be seen that after adding 2% of Example 1, the plugging rate of the drilling fluid for cores with various permeabilities can reach over 90%, indicating that the plugging agent can "self-adapt" to pore throats of different sizes and effectively fills the pores of the plugging layer to make the permeability lower. While for Comparative Example 1 and Comparative Example 2, the plugging rates for cores with different permeabilities are not high, and the self-adaptive plugging effect is poor.

[0096] Table 5 Core Plugging Rate Test of Synthetic-based Drilling Fluid

[0097]

[0098] Table 6 shows the test of the core plugging rate of oil-based drilling fluid. It can be seen from the above results that after adding 2% of Example 1, the plugging rate of the core with various permeabilities by the drilling fluid can reach more than 90%, indicating that the plugging agent can "adaptively" plug pores and throats of different sizes, and effectively fills the pores of the plugging layer to make the permeability lower. Considering the test results of Table 5 and Table 6 comprehensively, the core plugging rate of Example 1 in synthetic-based drilling fluid and oil-based drilling fluid with various permeabilities exceeds 90%, indicating that Example 1 has strong adaptive plugging performance in non-aqueous drilling fluid and can effectively accumulate and fill in leakage channels of different scales.

[0099] Table 6 Test of Core Plugging Rate of Oil-Based Drilling Fluid

[0100]

[0101] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A preparation method of a high-pressure-bearing self-adaptive plugging agent for non-aqueous drilling fluids, characterized in that: It includes the following steps: (ⅰ) Mix deionized water and a dispersant and stir evenly to obtain a dispersant solution; (ⅱ) Mix a short-chain monounsaturated fatty acid ester monomer, a medium-chain monounsaturated fatty acid ester monomer, a long-chain monounsaturated fatty acid ester monomer, a crosslinking agent and an initiator evenly to obtain a mixture; (ⅲ) Add the mixture obtained in step (ⅱ) to the dispersant solution obtained in step (ⅰ), then add a pore-expanding agent, stir and react, and then obtain the plugging agent after filtration and drying.

2. The preparation method of the high-pressure-bearing self-adaptive plugging agent for non-aqueous drilling fluids according to claim 1, characterized in that: The mass concentration of the dispersant in the dispersant solution is 0.25%.

3. The preparation method of the high-pressure-bearing self-adaptive plugging agent for non-aqueous drilling fluids according to claim 1, wherein: The dispersant is any one of polyvinyl alcohol 1788, polyvinyl alcohol 0588 or polyvinyl alcohol 2488.

4. The preparation method of the high-pressure-bearing self-adaptive plugging agent for non-aqueous drilling fluid according to claim 1, wherein: The short-chain monounsaturated fatty acid ester monomer is methyl acrylate or ethyl acrylate, and the number of carbon atoms of the short-chain monounsaturated fatty acid ester monomer is not more than 6; the medium-chain monounsaturated fatty acid ester monomer is butyl acrylate or amyl acrylate, and the number of carbon atoms of the medium-chain monounsaturated fatty acid ester monomer is not more than 12 and greater than 6; the long-chain monounsaturated fatty acid ester monomer is lauryl acrylate or octadecyl acrylate, and the number of carbon atoms of the long-chain monounsaturated fatty acid ester monomer is greater than 12.

5. The preparation method of the high-pressure-bearing self-adaptive plugging agent for non-aqueous drilling fluid according to claim 1, characterized in that: The mass ratio of the short-chain monounsaturated fatty acid ester monomer, the medium-chain monounsaturated fatty acid ester monomer and the long-chain monounsaturated fatty acid ester monomer is 5:4:

1.

6. The preparation method of the high-pressure-bearing self-adaptive plugging agent for non-aqueous drilling fluids according to claim 1, characterized in that: The crosslinking agent is any one of N,N-methylenebisacrylamide, divinylbenzene or diallyl phthalate; the initiator is any one of azobisisobutyronitrile, benzoyl peroxide or tert-butyl peroxybenzoate; the pore-expanding agent is polyethylene glycol or ethyl acetate.

7. The preparation method of the high-pressure-bearing self-adaptive plugging agent for non-aqueous drilling fluid according to claim 1, wherein: The added mass of the crosslinking agent is 0.17% - 1.2% of the total mass of the short-chain monounsaturated fatty acid ester monomer, the medium-chain monounsaturated fatty acid ester monomer and the long-chain monounsaturated fatty acid ester monomer; the added mass of the initiator is 2.2% - 4.4% of the total mass of the short-chain monounsaturated fatty acid ester monomer, the medium-chain monounsaturated fatty acid ester monomer and the long-chain monounsaturated fatty acid ester monomer; the added mass of the pore-expanding agent is 16.7% - 33.3% of the total mass of the short-chain monounsaturated fatty acid ester monomer, the medium-chain monounsaturated fatty acid ester monomer and the long-chain monounsaturated fatty acid ester monomer.

8. The preparation method of the high-pressure-bearing self-adaptive plugging agent for non-aqueous drilling fluids according to claim 1, wherein: The mass ratio of the total mass of the short-chain monounsaturated fatty acid ester monomer, the medium-chain monounsaturated fatty acid ester monomer and the long-chain monounsaturated fatty acid ester monomer to the mass of the dispersant solution is 3:8 or 3:

16.

9. A high-pressure-bearing self-adaptive plugging agent for non-aqueous drilling fluids, characterized in that: Prepared by the method according to any one of claims 1 to 8.

10. The high-pressure bearing self-adaptive plugging agent for non-aqueous drilling fluid according to claim 9, characterized in that: The molecular structure of the plugging agent is as follows formula (Ⅰ): In formula (Ⅰ): the value range of x is 6 - 12; the value range of y is 13 - 24.

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