Temperature-sensitive plugging material, plugging composition and application thereof

Abstract

The invention relates to a temperature-sensitive leaking stoppage material, a leaking stoppage composition and application of the temperature-sensitive leaking stoppage material, and the temperature-sensitive leaking stoppage material is prepared by the following steps: S1, epoxy resin and a curing agent are subjected to a heating cross-linking reaction in the presence of an accelerant to prepare a shape memory polymer; the mass ratio of the epoxy resin to the curing agent to the accelerant is 100: (51-78): (0.1-1); the epoxy resin is one or a combination of two of E-44, E-51 and E-20; the curing agent is one or a combination of more than two of m-phenylenediamine, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, a 593 curing agent and a K123 curing agent; the heating cross-linking reaction is performed according to a two-stage heating reaction; the heating reaction conditions are as follows: the reaction is performed for 4 hours at 100 DEG C, and then the temperature is raised to 150 DEG C to react for 2 hours; and S2, carrying out hot-pressing secondary shaping on the shape memory polymer obtained in the S1.

Description

Technical Field

[0001] This invention relates to a temperature-sensitive sealing material, a sealing composition, and its application, belonging to the field of oil and gas drilling technology. Background Technology

[0002] Oil, natural gas, and other underground resources are important energy sources for my country, playing a vital role in the country's economic and social development. Currently, these resources are primarily obtained through drilling. Drilling involves a rotary table driving the drill string and drill bit to break up formation rocks, while drilling fluid balances formation pressure and removes cuttings, continuously deepening the wellbore until the target formation is reached. Finally, casing is run in and cemented, creating a channel for extracting underground resources to the surface. Drilling fluid is indispensable in the drilling process; it is a general term for various circulating fluids that meet the needs of drilling operations. Besides using its own fluid column pressure to balance formation pressure and suspend and return cuttings, drilling fluid also cools and lubricates the drill bit and drill string, transmits water power, and stabilizes the wellbore, playing a crucial role in the safe and efficient conduct of drilling operations. With the continuous deepening of oil and gas exploration and development, the formations encountered during drilling are becoming increasingly complex, frequently resulting in large-scale wellbore leakage due to drilling fluid loss.

[0003] Currently used slug plugging technology offers high pressure resistance but has a long plugging cycle, while drilling-while-plugging technology is easy to operate but the particles are difficult to match with fractures, resulting in low pressure resistance. The gel plugging technology developed in recent years also has certain limitations; it is difficult to simultaneously achieve high strength and easy pumpability of the plugging gel. Generally, easily pumpable plugging gels have a low degree of gelation and poor plugging effect, while high-strength gels are difficult to inject into the formation and may even cause well blockage. While using encapsulated delayed crosslinking agents can partially solve these problems, it also has drawbacks such as short delay time, poor thermal stability of the encapsulated crosslinking agent, and high cost.

[0004] Thermosensitive shape memory material is a special type of functional material that exhibits a shape memory effect under temperature changes. After undergoing deformation, this material can recover its initial predetermined shape upon external temperature stimulation such as heating or cooling. The original product is in sheet form, which can adaptively enter leakage channels. When heated in cracks, it recovers its original shape into a block, sealing the cracks and improving the formation's bearing capacity.

[0005] Chinese invention patent CN111607367B discloses a temperature-sensitive gel plugging agent, which is composed of 40-50% by mass of gellan gum, 40-50% by mass of drilling fluid bentonite, 1-2% by mass of soda ash, and 5-15% by mass of viscosifier. This temperature-sensitive gel plugging agent can form a solid gel at high temperatures, completely fixing free water to achieve pressure-bearing plugging. It can also provide suitable viscosity and allow for the addition of suspended barite and other plugging materials, effectively ensuring downhole safety while plugging leaks and reducing the risk of blowouts. Chinese invention patent CN106433584B discloses a temperature-sensitive plugging agent composition and its application, as well as a drilling fluid and its application. Specifically, it discloses a temperature-sensitive plugging agent composition containing acrylamide polymers and polyols. This plugging agent composition exhibits good rheological properties and is easily pumpable at room temperature. However, after being pumped into the formation, it forms a stronger plugging gel at formation temperature, demonstrating good temperature sensitivity. Its swelling is less affected by formation environmental factors, exhibiting high controllability. However, the aforementioned temperature-sensitive plugging agents are all gel-type, resulting in issues with low shape recovery rate and pressure resistance. Summary of the Invention

[0006] The first objective of this invention is to provide a temperature-sensitive sealing material to solve the problems of low shape recovery rate and low pressure bearing capacity of existing temperature-sensitive sealing materials.

[0007] The second objective of this invention is to provide a temperature-sensitive sealing composition to solve the problem of poor adaptive matching between temperature-sensitive sealing agents and cracks in the prior art.

[0008] The third objective of this invention is to provide the application of temperature-sensitive plugging materials or temperature-sensitive plugging compositions in drilling fluids, in order to solve the problem that existing temperature-sensitive plugging materials have low shape recovery rate and pressure bearing capacity, resulting in poor plugging effect.

[0009] To achieve the above objectives, the technical solution of a temperature-sensitive sealing material in this invention is as follows:

[0010] A temperature-sensitive leak-sealing material is prepared by the following steps:

[0011] S1, epoxy resin, and curing agent are used to prepare a shape memory polymer by heating and crosslinking reaction in the presence of an accelerator; the mass ratio of epoxy resin, curing agent, and accelerator is 100:(51-78):(0.1-1); the epoxy resin is one or a combination of two of E-44, E-51, and E-20; the curing agent is one or a combination of two or more of m-phenylenediamine, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, 593 curing agent, and K123 curing agent; the heating and crosslinking reaction is carried out in a two-stage heating reaction; the heating reaction conditions are: reacting at 100℃ for 4 hours, and then heating to 150℃ for 2 hours.

[0012] S2. The shape memory polymer described in S1 is subjected to a second hot-pressing process.

[0013] The beneficial effects of the above technical solution are as follows: This invention uses epoxy resin and curing agent as the main materials, and in the presence of an accelerator, a two-stage heating reaction is carried out at 100℃ for 4 hours and at 150℃ for 2 hours to crosslink and form a block shape memory polymer. After secondary hot pressing and granulation, a sheet-like temperature-sensitive sealing material with ideal particle size is obtained. This invention optimizes the types and ratios of epoxy resin and curing agent, as well as the conditions for the heating and crosslinking reaction, resulting in a temperature-sensitive sealing material with a low density (1.16 g / cm³). 3 The particle size can be adjusted as needed, the glass transition temperature is between 50 and 100℃, the original shape is flake-like, and the shape recovers to block-like. The particle size growth rate is large and the shape recovery time range is wide. It can be reasonably adjusted according to the characteristics of the leakage layer, which can effectively seal cracks, improve the formation bearing capacity, and simplify the construction process.

[0014] As a further improvement, the accelerator mentioned in S1 is one or a combination of two of DMP-30, K54 epoxy resin accelerator, and AEP.

[0015] The beneficial effects of the above technical solution are that the above accelerator can efficiently promote the reaction of epoxy resin and curing agent, and is suitable for the reaction system of the present invention.

[0016] As a further improvement, the conditions for hot-press secondary shaping described in S2 include: a temperature of 120-140℃ and a pressure of not less than 30MPa.

[0017] The beneficial effect of the above technical solution is that, under the above temperature and pressure conditions, a temperature-sensitive sealing material with good recovery rate can be obtained after hot pressing.

[0018] As a further improvement, the temperature-sensitive sealing material is in the shape of a flat sheet.

[0019] The beneficial effect of the above technical solution is that the shape of the temperature-sensitive sealing material is a flat and thin sheet, which facilitates the sealing material to enter narrow cracks.

[0020] As a further improvement, the glass transition temperature of the shape memory polymer is 50–100°C.

[0021] The beneficial effect of the above technical solution is that when the glass transition temperature of the shape memory polymer is 50-100℃, it helps the shape memory polymer to easily recover its shape after being heated. Preferably, the glass transition temperature of the shape memory polymer is 55-95℃.

[0022] To achieve the above objectives, the technical solution of the temperature-sensitive leak-sealing composition of the present invention is as follows:

[0023] A temperature-sensitive leak-sealing composition comprising the aforementioned temperature-sensitive leak-sealing material.

[0024] The beneficial effects of the above technical solution are as follows: the original shape of the temperature-sensitive sealing material of the present invention is sheet-like, and after the shape is restored, it becomes block-like. The particle size growth rate is large. When combined with other types of sealing materials or sealing agents, they can complement each other and achieve a more comprehensive sealing effect.

[0025] As a further improvement, the temperature-sensitive sealing composition includes calcium carbonate material and fiber material; the mass ratio of the temperature-sensitive sealing material, calcium carbonate material and fiber material is 4-7:3-6:0.1-0.2.

[0026] The beneficial effects of the above technical solution are as follows: calcium carbonate material and fiber material are commonly used sealing materials in this field. They are easy to obtain and have a low price. Moreover, calcium carbonate material has a certain pressure resistance and fiber material has a certain toughness. When combined with the temperature-sensitive sealing material of the present invention, it can adapt to more crack conditions and expand the scope of application.

[0027] As a further improvement, the fiber material is polypropylene fiber.

[0028] The beneficial effects of the above technical solution are as follows: polypropylene fiber is a common fiber material in sealing agents, has stable properties, and is well compatible with the temperature-sensitive sealing material of the present invention.

[0029] To achieve the above objectives, the technical solution for the application of temperature-sensitive plugging materials or temperature-sensitive plugging compositions as plugging agents in drilling fluids in this invention is as follows:

[0030] Application of temperature-sensitive plugging materials or temperature-sensitive plugging compositions as plugging agents in drilling fluids.

[0031] The beneficial effects of the above technical solution are as follows: The temperature-sensitive plugging material of the present invention, after testing, has high pressure resistance and easily returns to its original shape after reaching the preset temperature. This characteristic is beneficial for adaptive bridging and sealing of fractures under high temperature and high pressure conditions at the bottom of the well, effectively avoiding the instability and damage of the sealing layer. Moreover, the temperature-sensitive plugging material synthesized by the present invention is in sheet form before reaching the activation temperature, which is convenient to be transported to the lost layer with the drilling fluid and easily adapts to the fracture. After activation by the temperature of the lost layer, it undergoes thermal expansion and stretching, and its shape returns to a cubic block shape, adaptively matching the fracture width, resulting in high sealing efficiency. When combined with other types of bridging plugging materials, a single plugging working fluid formula can successfully seal coexisting fractures with different openings of 3-5 mm, achieving a temperature-sensitive, adaptive, and highly efficient synergistic "intelligent" plugging effect.

[0032] As a further improvement, the temperature-sensitive plugging material accounts for 5% to 11% of the drilling fluid mass.

[0033] The beneficial effect of the above technical solution is that by adding temperature-sensitive plugging material to the drilling fluid in the above amount, a good pressure-bearing plugging effect can be achieved without affecting the basic properties of the drilling fluid.

[0034] Compared with existing technologies, the advantages of this invention are as follows:

[0035] 1. The temperature-sensitive sealing agent of the present invention has a low density (1.16 g / cm³). 3 The particle size can be adjusted as needed, and the glass transition temperature is 50-100℃, which can be reasonably adjusted according to the characteristics of the leak layer.

[0036] 2. The high-strength, easily recoverable, temperature-sensitive plugging material synthesized in this invention has a large expansion rate under high temperature and high pressure conditions. After being activated by the high temperature of the leaking layer, it has high compressive strength, which is conducive to adaptive bridging and sealing of cracks under high temperature and high pressure conditions at the bottom of the well, effectively avoiding the instability and damage of the plugging layer.

[0037] 3. The temperature-sensitive plugging agent synthesized in this invention is in flake form before reaching the activation temperature, which facilitates its delivery to the lost circulation zone with the drilling fluid and allows it to readily adapt to the fracture. After activation by the temperature of the lost circulation zone, it undergoes thermal expansion and stretching, returning to a cubic block shape, which adaptively matches the fracture width, resulting in high plugging efficiency. When combined with other types of bridging plugging materials, a single plugging working fluid formula can successfully plug coexisting fractures with different openings of 3-5 mm, achieving a temperature-sensitive, adaptive, and highly efficient synergistic "intelligent" plugging effect.

[0038] 4. The temperature-sensitive plugging material synthesized in this invention has good compatibility with drilling fluids and excellent memory recovery properties. It can also be used in combination with other types of plugging particles, self-healing while bonding other plugging particles to form a sealing layer, thus reducing usage costs. Attached Figure Description

[0039] Figure 1 These are photographs of the temperature-sensitive sealing material before and after particle expansion in Experimental Example 2 of this invention;

[0040] Figure 2 This is an experimental diagram of sealing a 3-5mm opening crack in Experiment Example 4 of this invention. Detailed Implementation

[0041] Currently used granular plugging materials have performance defects. For example, inert granular plugging materials such as walnut shells, peanut shells, nut shells, stones, and bricks are rigid and have poor deformability. When their size does not match the size of the downhole pores or fractures, they are prone to forming an unstable plugging layer, leading to plugging failure. Although elastic particles such as graphite have a certain degree of elastic deformation, they cannot achieve volume expansion. Although expandable particles such as gel microspheres and water-absorbing resins can achieve volume expansion by absorbing water, this will greatly weaken their own strength and deteriorate the rheological properties of the drilling fluid. Moreover, they have low shape recovery rate and poor pressure bearing capacity.

[0042] To address the aforementioned problems, this invention uses epoxy resin and curing agent as raw materials, and in the presence of an accelerator, a two-stage heating reaction is carried out to obtain a shape memory polymer. After hot pressing and secondary shaping, the polymer is pulverized and granulated to obtain a temperature-sensitive sealing material.

[0043] The rheological properties of drilling fluid containing temperature-sensitive plugging material were tested. The results showed that the experimental slurry exhibited good rheological properties before and after aging, possessing sufficient viscosity and shear strength to suspend and carry the plugging material. After adding shape memory composite plugging material, the rheological properties remained essentially unchanged, demonstrating good compatibility with the drilling fluid. The temperature-sensitive plugging agent is an inert material; its expansion properties are only affected by temperature and do not affect the rheological properties of the drilling fluid.

[0044] The particle size of temperature-sensitive sealing particles with different mesh sizes was analyzed by sieving to determine the particle size characteristic parameters (D50 and D90 values) at room temperature. The results showed that the particle size of the activated temperature-sensitive sealing agent increased, with a D50 particle size growth rate of 41.94% and a D90 particle size growth rate of 60.90%, exhibiting a high particle size expansion rate.

[0045] In the crack sealing experiment, a sealing slurry composed of temperature-sensitive sealing agents of different mesh sizes, calcium carbonate, and fiber materials was added to a high-temperature and high-pressure dynamic sealing instrument. Through reasonable particle size distribution and concentration control, it can seal cracks of different openings of 3-5 mm at 80℃, with a pressure bearing capacity of 12 MPa and low leakage, achieving the adaptive and synergistic intelligent sealing effect of the same sealing formula.

[0046] The present invention will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. The equipment and raw materials used are all commercially available or commonly used in the art. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art.

[0047] I. Specific Embodiments of a Temperature-Sensitive Leak-Sealing Material of the Present Invention

[0048] Example 1

[0049] The temperature-sensitive sealing material in this embodiment is prepared by the following steps:

[0050] (1) Pour 100g of epoxy resin E-44, 60g of curing agent methyltetrahydrophthalic anhydride and 1g of accelerator DMP-30 into a beaker, stir at 50℃ for 10 minutes, and mix evenly.

[0051] (2) Spray methyl silicone oil evenly onto the inner wall of the mold. The mold size is 10cm×1cm×5mm.

[0052] (3) Inject the mixture from step (1) into the mold and heat it for cross-linking reaction (two-stage heating reaction). The reaction conditions are: 100℃ for 4 hours and 150℃ for 2 hours.

[0053] (4) After crosslinking is completed, the sample is removed and cooled to room temperature before demolding to obtain the shape memory polymer;

[0054] (5) After placing the shape memory polymer from step (4) in an oil bath at 120°C for 20 minutes, apply pressure of 30MPa or more and maintain the external force for 10 minutes using a hot compression molding device.

[0055] (6) Cooling and unloading external forces, and obtaining temperature-sensitive sealing materials with different particle sizes through crushing and granulation.

[0056] The density of the temperature-sensitive sealing material is 1.16 g / cm³. 3 .

[0057] The glass transition temperature of the prepared temperature-sensitive sealing material was tested using a TA-Q20 differential scanning calorimeter (DSC) from the United States. The glass transition temperature of the temperature-sensitive sealing material was 70℃.

[0058] Example 2

[0059] The temperature-sensitive sealing material in this embodiment is prepared by the following steps:

[0060] (1) Pour 100g of epoxy resin E-44, 70g of curing agent methyltetrahydrophthalic anhydride and 1g of accelerator DMP-30 into a beaker, stir at 50℃ for 10 minutes, and mix evenly.

[0061] (2) Spray methyl silicone oil evenly onto the inner wall of the mold. The mold size is 10cm×1cm×5mm.

[0062] (3) Inject the mixture from step (1) into the mold and heat it for cross-linking reaction (two-stage heating reaction). The reaction conditions are: 100℃ for 4 hours and 150℃ for 2 hours.

[0063] (4) After crosslinking is completed, the sample is removed and cooled to room temperature before demolding to obtain the shape memory polymer;

[0064] (5) After placing the shape memory polymer from step (4) in an oil bath at 120°C for 20 minutes, apply pressure of 30MPa or more and maintain the external force for 10 minutes using a hot compression molding device.

[0065] (6) Cooling and unloading external forces, and obtaining temperature-sensitive sealing materials with different particle sizes through crushing and granulation.

[0066] The density of the temperature-sensitive sealing material is 1.16 g / cm³. 3 .

[0067] The glass transition temperature of the prepared temperature-sensitive sealing material was tested using a TA-Q20 differential scanning calorimeter (DSC) from the United States. The glass transition temperature of the temperature-sensitive sealing material was 75℃.

[0068] Example 3

[0069] The temperature-sensitive sealing material in this embodiment is prepared by the following steps:

[0070] (1) Pour 100g of epoxy resin E-44, 76g of curing agent methyltetrahydrophthalic anhydride and 1g of accelerator DMP-30 into a beaker, stir at 50°C for 10 minutes, and mix evenly.

[0071] (2) Spray methyl silicone oil evenly onto the inner wall of the mold. The mold size is 10cm×1cm×5mm.

[0072] (3) Inject the mixture from step (1) into the mold and heat it for cross-linking reaction (two-stage heating reaction). The reaction conditions are: 100℃ for 4 hours and 150℃ for 2 hours.

[0073] (4) After crosslinking is completed, the sample is removed and cooled to room temperature before demolding to obtain the shape memory polymer;

[0074] (5) After placing the shape memory polymer from step (4) in an oil bath at 120°C for 20 minutes, apply pressure of 30MPa or more and maintain the external force for 10 minutes using a hot compression molding device.

[0075] (6) Cooling and unloading external forces, and obtaining temperature-sensitive sealing materials with different particle sizes through crushing and granulation.

[0076] The density of the temperature-sensitive sealing material is 1.16 g / cm³. 3 .

[0077] The glass transition temperature of the prepared temperature-sensitive sealing material was tested using a TA-Q20 differential scanning calorimeter (DSC) from the United States. The glass transition temperature of the temperature-sensitive sealing material was 80℃.

[0078] Example 4

[0079] The temperature-sensitive sealing material in this embodiment is prepared by the following steps:

[0080] (1) Pour 100g of epoxy resin E-51, 76g of curing agent methyl hexahydrophthalic anhydride and 1g of accelerator DMP-30 into a beaker, stir at 50℃ for 10 minutes, and mix evenly.

[0081] (2) Spray methyl silicone oil evenly onto the inner wall of the mold. The mold size is 10cm×1cm×5mm.

[0082] (3) Inject the mixture from step (1) into the mold and heat it for cross-linking reaction (two-stage heating reaction). The reaction conditions are: 100℃ for 4 hours and 150℃ for 2 hours.

[0083] (4) After crosslinking is completed, the sample is removed and cooled to room temperature before demolding to obtain the shape memory polymer;

[0084] (5) After placing the shape memory polymer from step (4) in an oil bath at 120°C for 20 minutes, apply pressure of 30MPa or more and maintain the external force for 10 minutes using a hot compression molding device.

[0085] (6) Cooling and unloading external forces, and obtaining temperature-sensitive sealing materials with different particle sizes through crushing and granulation.

[0086] The density of the temperature-sensitive sealing material is 1.16 g / cm³. 3 .

[0087] The glass transition temperature of the prepared temperature-sensitive sealing material was tested using a TA-Q20 differential scanning calorimeter (DSC) from the United States. The glass transition temperature of the temperature-sensitive sealing material was 90℃.

[0088] Example 5

[0089] The temperature-sensitive sealing material in this embodiment is prepared by the following steps:

[0090] (1) Pour 100g of epoxy resin E-51, 51g of curing agent methyl hexahydrophthalic anhydride and 0.1g of K54 epoxy resin accelerator into a beaker, stir at 50℃ for 10 minutes, and mix evenly.

[0091] (2) Spray methyl silicone oil evenly onto the inner wall of the mold. The mold size is 10cm×1cm×5mm.

[0092] (3) Inject the mixture from step (1) into the mold and heat it for cross-linking reaction (two-stage heating reaction). The reaction conditions are: 100℃ for 4 hours and 150℃ for 2 hours.

[0093] (4) After crosslinking is completed, the sample is removed and cooled to room temperature before demolding to obtain the shape memory polymer;

[0094] (5) After placing the shape memory polymer from step (4) in an oil bath at 120°C for 20 minutes, apply pressure of 30MPa or more and maintain the external force for 10 minutes using a hot compression molding device.

[0095] (6) Cooling and unloading external forces, and obtaining temperature-sensitive sealing materials with different particle sizes through crushing and granulation.

[0096] The density of the temperature-sensitive sealing material is 1.16 g / cm³. 3 .

[0097] The glass transition temperature of the prepared temperature-sensitive sealing material was tested using a TA-Q20 differential scanning calorimeter (DSC) from the United States. The glass transition temperature of the temperature-sensitive sealing material was 60℃.

[0098] Example 6

[0099] The temperature-sensitive sealing material in this embodiment is prepared by the following steps:

[0100] (1) Pour 100g of epoxy resin E-51, 78g of curing agent methyl hexahydrophthalic anhydride and 1g of K54 epoxy resin accelerator into a beaker, stir at 50°C for 10 minutes, and mix evenly.

[0101] (2) Spray methyl silicone oil evenly onto the inner wall of the mold. The mold size is 10cm×1cm×5mm.

[0102] (3) Inject the mixture from step (1) into the mold and heat it for cross-linking reaction (two-stage heating reaction). The reaction conditions are: 100℃ for 4 hours and 150℃ for 2 hours.

[0103] (4) After crosslinking is completed, the sample is removed and cooled to room temperature before demolding to obtain the shape memory polymer;

[0104] (5) After placing the shape memory polymer from step (4) in an oil bath at 120°C for 20 minutes, apply pressure of 30MPa or more and maintain the external force for 10 minutes using a hot compression molding device.

[0105] (6) Cooling and unloading external forces, and obtaining temperature-sensitive sealing materials with different particle sizes through crushing and granulation.

[0106] The density of the temperature-sensitive sealing material is 1.16 g / cm³. 3 .

[0107] The glass transition temperature of the prepared temperature-sensitive sealing material was tested using a TA-Q20 differential scanning calorimeter (DSC) from the United States. The glass transition temperature of the temperature-sensitive sealing material was 95℃.

[0108] Example 7

[0109] The temperature-sensitive sealing material in this embodiment is prepared by the following steps:

[0110] (1) Pour 100g of epoxy resin E-51, 60g of curing agent m-phenylenediamine and 0.5g of accelerator DMP-30 into a beaker, stir at 50℃ for 10 minutes, and mix evenly;

[0111] (2) Spray methyl silicone oil evenly onto the inner wall of the mold. The mold size is 10cm×1cm×5mm.

[0112] (3) Inject the mixture from step (1) into the mold and heat it for cross-linking reaction (two-stage heating reaction). The reaction conditions are: 100℃ for 4 hours and 150℃ for 2 hours.

[0113] (4) After crosslinking is completed, the sample is removed and cooled to room temperature before demolding to obtain the shape memory polymer;

[0114] (5) After placing the shape memory polymer from step (4) in an oil bath at 120°C for 20 minutes, apply pressure of 30MPa or more and maintain the external force for 10 minutes using a hot compression molding device.

[0115] (6) Cooling and unloading external forces, and obtaining temperature-sensitive sealing materials with different particle sizes through crushing and granulation.

[0116] The density of the temperature-sensitive sealing material is 1.15 g / cm³. 3 .

[0117] The glass transition temperature of the prepared temperature-sensitive sealing material was tested using a TA-Q20 differential scanning calorimeter (DSC) from the United States. The glass transition temperature of the temperature-sensitive sealing material was 55℃.

[0118] Example 8

[0119] The temperature-sensitive sealing material in this embodiment is prepared by the following steps:

[0120] (1) Pour 100g of epoxy resin E-51, 65g of 593 and 0.1g of accelerator DMP-30 curing agent into a beaker, stir at 50℃ for 10 minutes, and mix evenly;

[0121] (2) Spray methyl silicone oil evenly onto the inner wall of the mold. The mold size is 10cm×1cm×5mm.

[0122] (3) Inject the mixture from step (1) into the mold and heat it for cross-linking reaction (two-stage heating reaction). The reaction conditions are: 100℃ for 4 hours and 150℃ for 2 hours.

[0123] (4) After crosslinking is completed, the sample is removed and cooled to room temperature before demolding to obtain the shape memory polymer;

[0124] (5) After placing the shape memory polymer from step (4) in an oil bath at 120°C for 20 minutes, apply pressure of 30MPa or more and maintain the external force for 10 minutes using a hot compression molding device.

[0125] (6) Cooling and unloading external forces, and obtaining temperature-sensitive sealing materials with different particle sizes through crushing and granulation.

[0126] The density of the temperature-sensitive sealing material is 1.15 g / cm³. 3 .

[0127] The glass transition temperature of the prepared temperature-sensitive sealing material was tested using a TA-Q20 differential scanning calorimeter (DSC) from the United States. The glass transition temperature of the temperature-sensitive sealing material was 58℃.

[0128] II. Specific Embodiments of the Temperature-Sensitive Leak-Sealing Composition of the Present Invention

[0129] Example 9

[0130] The temperature-sensitive sealing composition of this embodiment consists of the temperature-sensitive sealing material of Example 1, calcium carbonate (10-80 mesh), and polypropylene fibers (10-12 mm in length and 35-40 μm in diameter); the mass ratio of the temperature-sensitive sealing material, calcium carbonate (10-80 mesh), and polypropylene fibers is 5:4:0.2. The temperature-sensitive sealing material is composed of temperature-sensitive sealing materials with particle sizes of 10-20 mesh, 20-40 mesh, and 40-80 mesh; the mass ratio of the temperature-sensitive sealing materials with particle sizes of 10-20 mesh, 20-40 mesh, and 40-80 mesh is 2:1:2.

[0131] Example 10

[0132] The temperature-sensitive sealing composition of this embodiment consists of the temperature-sensitive sealing material of Example 1, calcium carbonate (10-80 mesh), and polypropylene fibers (10-12 mm in length and 35-40 μm in diameter); the mass ratio of the temperature-sensitive sealing material, calcium carbonate (10-80 mesh), and polypropylene fibers is 4:6:0.2. The temperature-sensitive sealing material is composed of temperature-sensitive sealing materials with particle sizes of 10-20 mesh, 20-40 mesh, and 40-80 mesh; the mass ratio of the temperature-sensitive sealing materials with particle sizes of 10-20 mesh, 20-40 mesh, and 40-80 mesh is 2:1:2.

[0133] Example 11

[0134] The temperature-sensitive sealing composition of this embodiment consists of the temperature-sensitive sealing material of Example 1, calcium carbonate (10-80 mesh), and polypropylene fibers (10-12 mm in length and 35-40 μm in diameter); the mass ratio of the temperature-sensitive sealing material, calcium carbonate (10-80 mesh), and polypropylene fibers is 7:3:0.1. The temperature-sensitive sealing material is composed of temperature-sensitive sealing materials with particle sizes of 10-20 mesh, 20-40 mesh, and 40-80 mesh; the mass ratio of the temperature-sensitive sealing materials with particle sizes of 10-20 mesh, 20-40 mesh, and 40-80 mesh is 2:1:2.

[0135] III. Comparative Example

[0136] Comparative Example 1

[0137] The temperature-sensitive leak-sealing material in this comparative example was prepared by the following steps:

[0138] (1) Pour 100g of epoxy resin E-44, 40g of curing agent methyltetrahydrophthalic anhydride and 1g of accelerator DMP-30 into a beaker, stir at 50℃ for 10 minutes, and mix evenly.

[0139] (2) Spray methyl silicone oil evenly onto the inner wall of the mold. The mold size is 10cm×1cm×5mm.

[0140] (3) Inject the mixture from step (1) into the mold and heat it for cross-linking reaction (two-stage heating reaction). The reaction conditions are: 100℃ for 4 hours and 150℃ for 2 hours.

[0141] (4) After crosslinking is completed, the sample is removed and cooled to room temperature before demolding to obtain the shape memory polymer;

[0142] (5) After placing the shape memory polymer from step (4) in an oil bath at 120°C for 20 minutes, apply 30 MPa of external force for 10 minutes using a hot compression molding device.

[0143] (6) Cooling and unloading external forces, and obtaining temperature-sensitive sealing materials with different particle sizes through crushing and granulation.

[0144] In the above comparative examples, the shape memory polymer was compressed and broken due to the low content of curing agent, making it impossible to obtain a temperature-sensitive sealing material.

[0145] Comparative Example 2

[0146] The temperature-sensitive leak-sealing material in this comparative example was prepared by the following steps:

[0147] (1) Pour 100g of epoxy resin E-44, 80g of curing agent methyltetrahydrophthalic anhydride and 1g of accelerator DMP-30 into a beaker, stir at 50℃ for 10 minutes, and mix evenly.

[0148] (2) Spray methyl silicone oil evenly onto the inner wall of the mold. The mold size is 10cm×1cm×5mm.

[0149] (3) Inject the mixture from step (1) into the mold and heat it for cross-linking reaction (two-stage heating reaction). The reaction conditions are: 100℃ for 4 hours and 150℃ for 2 hours.

[0150] (4) After crosslinking is completed, the sample is removed and cooled to room temperature before demolding to obtain the shape memory polymer;

[0151] (5) After placing the shape memory polymer from step (4) in an oil bath at 120°C for 20 minutes, apply 30 MPa of external force for 10 minutes using a hot compression molding device.

[0152] (6) Cooling and unloading external forces, and obtaining temperature-sensitive sealing materials with different particle sizes through crushing and granulation.

[0153] In the above comparative examples, the high content of curing agent resulted in the shape memory polymer being too strong to be compressed into sheets, thus making it impossible to produce a temperature-sensitive sealing material.

[0154] Comparative Example 3

[0155] The temperature-sensitive leak-sealing material in this comparative example was prepared by the following steps:

[0156] (1) Pour 100g of epoxy resin E-44, 70g of curing agent methyltetrahydrophthalic anhydride and 1g of accelerator DMP-30 into a beaker, stir at 50℃ for 10 minutes, and mix evenly.

[0157] (2) Spray methyl silicone oil evenly onto the inner wall of the mold. The mold size is 10cm×1cm×5mm.

[0158] (3) Inject the mixture from step (1) into the mold and heat it for cross-linking reaction (two-stage heating reaction). The reaction conditions are: 100℃ for 2 hours and 150℃ for 2 hours.

[0159] (4) After crosslinking is completed, the sample is removed and cooled to room temperature before demolding to obtain the shape memory polymer;

[0160] (5) After placing the shape memory polymer from step (4) in an oil bath at 120°C for 20 minutes, apply 30 MPa of external force for 10 minutes using a hot compression molding device.

[0161] (6) Cooling and unloading external forces, and obtaining temperature-sensitive sealing materials with different particle sizes through crushing and granulation.

[0162] In the comparative examples above, the short reaction time at the first-stage curing temperature of 100°C resulted in insufficient mechanical strength of the shape memory polymer, causing it to compress and break, thus making it impossible to produce a temperature-sensitive sealing material.

[0163] Comparative Example 4

[0164] The temperature-sensitive leak-sealing material in this comparative example was prepared by the following steps:

[0165] (1) Pour 100g of epoxy resin E-44, 70g of curing agent methyltetrahydrophthalic anhydride and 1g of accelerator DMP-30 into a beaker, stir at 50℃ for 10 minutes, and mix evenly.

[0166] (2) Spray methyl silicone oil evenly onto the inner wall of the mold. The mold size is 10cm×1cm×5mm.

[0167] (3) Inject the mixture from step (1) into the mold and heat it for cross-linking reaction (two-stage heating reaction). The reaction conditions are: 80℃ for 4 hours and 150℃ for 2 hours.

[0168] (4) After crosslinking is completed, the sample is removed and cooled to room temperature before demolding to obtain the shape memory polymer;

[0169] (5) After placing the shape memory polymer from step (4) in an oil bath at 120°C for 20 minutes, apply 30 MPa of external force for 10 minutes using a hot compression molding device.

[0170] (6) Cooling and unloading external forces, and obtaining temperature-sensitive sealing materials with different particle sizes through crushing and granulation.

[0171] In the comparative examples above, due to the low curing temperature of the first stage, only 80°C, the shape memory polymer had insufficient mechanical strength, resulting in compression and breakage, and thus the temperature-sensitive sealing material could not be produced.

[0172] IV. Experimental Examples: Application of Temperature-Sensitive Plugging Materials or Compositions in Drilling Fluids

[0173] This invention tests the basic properties, particle expansion rate, particle expansion mass, and plugging performance of the temperature-sensitive plugging material (hereinafter referred to as CK-SLCM) prepared in Example 1. The temperature-sensitive plugging materials of Examples 2-8 obtained the same or similar results as the temperature-sensitive plugging material of Example 1. The specific experimental process and results are as follows:

[0174] Experiment Example 1: Basic Performance Evaluation

[0175] This experiment involved adding a temperature-sensitive plugging material to a water-based drilling fluid to evaluate its effects on the fluid's rheology and filtration properties. The water-based drilling fluid formulation was as follows: 4% bentonite slurry + 0.4% CMC-HV (sodium carboxymethyl cellulose) + 4% CK-SLCM (10-20 mesh) + 4% CK-SLCM (20-40 mesh) + 3% CK-SLCM (40-80 mesh). The rheological properties of the drilling fluid were measured before aging and after aging at 90℃ for 16 hours to evaluate its basic properties. The results of the basic property evaluation are shown in Table 1.

[0176] Table 1. Experimental results on the effect of temperature-sensitive plugging agent on the rheological properties of drilling fluid.

[0177]

[0178] The results in Table 1 show that the experimental slurry exhibits good rheological properties before and after aging, possessing sufficient viscosity and shear strength to meet the requirements for suspending and carrying the plugging material. After adding the shape memory composite plugging material, the rheological properties remain essentially unchanged, demonstrating good compatibility with the drilling fluid. The temperature-sensitive plugging agent is an inert material; its expansion properties are only affected by temperature and do not affect the rheological properties of the drilling fluid.

[0179] Example 2: Evaluation of Particle Expansion Rate

[0180] A 6-20 mesh temperature-sensitive plugging material was used, and particle size analysis was performed on the particles of different mesh sizes using a sieve analysis method to determine the particle size characteristic parameters (D50 and D90 values) at room temperature. Then, the 6-20 mesh temperature-sensitive plugging material was mixed evenly with drilling fluid (drilling fluid formula: 4% bentonite slurry + 0.2% CMC-HV + 0.2% XC, where CMC-HV is sodium carboxymethyl cellulose and XC is xanthan gum) and poured into a sealing plugging device. After heating to 150℃, the piston was pushed by a hydraulic pump to pressurize to 20MPa, which was maintained for 20 minutes. The vessel was then removed, cooled to room temperature, and the pressure was released to end the experiment. The particle size characteristic parameters of the activated particles were determined again using a sieve analysis method. The particle expansion characteristics were evaluated using the D50 and D90 particle size growth rates as indicators. The activated temperature-sensitive plugging agent showed an increase in particle size, such as... Figure 1 As shown in Table 2, the specific particle size growth rate is as follows.

[0181] Table 2. Particle Expansion Rate of Temperature-Sensitive Sealing Materials

[0182] Blocking system D50 particle size growth rate D90 particle size growth rate Temperature-sensitive sealant (6-20 mesh) 41.94％ 60.90％

[0183] As shown in Table 2, the particle size growth rate of D50 is 41.94% and that of D90 is 60.90%, indicating that the temperature-sensitive sealing material of the present invention has a high particle size expansion rate.

[0184] Experimental Example 3: Evaluation of Particle Expansion Quality

[0185] Take 8-10 mesh, 10-20 mesh and 20-40 mesh temperature-sensitive plugging materials, weigh the mass of the temperature-sensitive plugging materials (before activation), mix the temperature-sensitive plugging materials with drilling fluid (drilling fluid formula is as follows: 4% bentonite slurry + 0.2% CMC-HV + 0.2% XC) evenly and pour it into the sealing and plugging device. After heating to 150℃, push the piston with a water pump to pressurize to 20MPa and maintain for 20min. Take out the vessel, cool to room temperature, depressurize and end the experiment. This is the activation. Then take out the temperature-sensitive plugging materials, dry the surface and weigh the mass. The test results are shown in Table 3.

[0186] Table 3. Mass changes of temperature-sensitive sealing material before and after temperature activation.

[0187] Particle size Mass before activation / g Mass after activation / g Quality change rate / % 8-10 mesh 20.0 20.0 0 10-20 mesh 20.0 20.0 0 20-40 mesh 20.0 20.0 0

[0188] As shown in Table 3, the mass change rate of the temperature-sensitive sealing material before and after activation is 0, and there is no mass change before and after particle expansion. This proves that the temperature-sensitive sealing material recovers its shape due to temperature, rather than being affected by the absorption medium.

[0189] Experiment Example 4: Crack Sealing Experiment

[0190] This experimental example uses a simulated crack sealing experiment. A sealing slurry composed of temperature-sensitive sealing materials of different mesh sizes, calcium carbonate, and fiber materials (the slurry formula is: 4% bentonite + 0.2% CMC-HV + 0.2% XC + 2% CK-SLCM (10-20 mesh) + 1% CK-SLCM (20-40 mesh) + 2% CK-SLCM (40-80 mesh) + 4% calcium carbonate (10-80 mesh) + 0.2% polypropylene fiber, with polypropylene fiber length 10-12 mm and diameter 35-40 μm) is added to the vessel of a high-temperature, high-pressure dynamic sealing instrument. A crack template is installed, and a piston in the vessel is pushed by a water pump. The piston pushes the sealing slurry into the crack, where the sealing material forms a sealing layer. The pressure sensor in the vessel displays the pressure increase after sealing. Through reasonable particle size distribution and concentration control, cracks with different openings of 3-5 mm can be sealed at 80℃. Specific results are shown in [link to results]. Figure 2As shown in Table 4, it has a pressure resistance of 12MPa, low leakage, and achieves adaptive and synergistic intelligent sealing with the same leak-sealing formula. Figure 2 As can be seen, the red box represents the sealing layer formed in the crack. This sealing layer is a mixture of temperature-sensitive sealant, calcium carbonate, and fiber materials. The light yellow component is the temperature-sensitive sealant, while the others are calcium carbonate and fiber materials. The resulting tight-fitting sealing layer has high pressure resistance and excellent sealing effect.

[0191] Table 4. Crack sealing experiment using temperature-sensitive plugging composition.

[0192]

[0193]

[0194] In summary, the temperature-sensitive plugging material synthesized in this invention is in sheet form before reaching the activation temperature, making it easy to be transported to the lost circulation zone with the drilling fluid and readily adapt to the fracture. After activation by the temperature of the lost circulation zone, it undergoes thermal expansion and stretching, restoring its shape to a cubic block, adaptively matching the fracture width, resulting in high plugging efficiency. When combined with other types of bridging plugging materials, a single plugging working fluid formula can successfully plug coexisting fractures with different openings of 3-5 mm, achieving a temperature-sensitive, adaptive, and highly efficient synergistic "intelligent" plugging effect.

[0195] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be determined by the claims. Similarly, any equivalent structural changes made based on the content of the present invention's specification shall also be included within the scope of protection of the present invention.

Claims

1. A temperature-sensitive leak-sealing material, characterized in that: It is prepared by the following steps: S1, epoxy resin, and curing agent are used to prepare a shape memory polymer by heating and crosslinking reaction in the presence of an accelerator; the mass ratio of epoxy resin, curing agent, and accelerator is 100:(51-78):(0.1-1); the epoxy resin is one or a combination of two of E-44, E-51, and E-20; the curing agent is one or a combination of two or more of m-phenylenediamine, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, 593 curing agent, and K123 curing agent; the heating and crosslinking reaction is carried out in a two-stage heating reaction; the heating reaction conditions are: reacting at 100℃ for 4 hours, and then heating to 150℃ for 2 hours. S2. The shape memory polymer described in S1 is subjected to a second hot-pressing process.

2. The temperature-sensitive sealing material according to claim 1, characterized in that: The accelerator mentioned in S1 is one or a combination of two of DMP-30, K54 epoxy resin accelerator, and AEP.

3. The temperature-sensitive sealing material according to claim 1 or 2, characterized in that: The conditions for hot-press secondary shaping described in S2 include: temperature of 120-140℃ and pressure of not less than 30MPa.

4. The temperature-sensitive sealing material according to claim 1 or 2, characterized in that: The temperature-sensitive sealing material is in the shape of a flat, thin sheet.

5. The temperature-sensitive sealing material according to claim 1, characterized in that: The glass transition temperature of the shape memory polymer is 50–100°C.

6. A temperature-sensitive leak-sealing composition, characterized in that: Includes the temperature-sensitive sealing material as described in any one of claims 1 to 5.

7. The temperature-sensitive leak-sealing composition according to claim 6, characterized in that: The temperature-sensitive sealing composition includes calcium carbonate material and fiber material; the mass ratio of the temperature-sensitive sealing material, calcium carbonate material and fiber material is 4-7:3-6:0.1-0.

2.

8. The temperature-sensitive leak-sealing composition according to claim 7, characterized in that: The fiber material is polypropylene fiber.

9. The application of a temperature-sensitive plugging material as described in any one of claims 1 to 5 or a temperature-sensitive plugging composition as described in any one of claims 6 to 8 in drilling fluid.

10. The application of the temperature-sensitive plugging material or temperature-sensitive plugging composition according to claim 9 in drilling fluid, characterized in that: The temperature-sensitive plugging material accounts for 5% to 11% of the drilling fluid mass.

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