A composite shape memory epoxy polymer and its preparation method and application

Abstract

The application provides a composite shape memory epoxy polymer and a preparation method and application thereof, and the preparation method of the composite shape memory epoxy polymer comprises the following steps: uniformly mixing water-based epoxy resin emulsion and a curing agent system A, and heating and curing to obtain a first cured body; uniformly mixing the water-based epoxy resin emulsion and a curing agent system B, and heating and curing to obtain a second cured body; and finally mixing the first cured body and the second cured body to obtain the composite shape memory epoxy polymer. The application firstly prepares epoxy resins with different high and low glass transition temperatures by using water-based epoxy emulsion, and then forms a low-activation high-adhesion-high-activation high-strength-low-activation high-adhesion composite layer by combining the epoxy polymer layer with low glass transition temperature, high toughness and high viscosity and the epoxy polymer layer with high glass transition temperature, high strength, and forms a shape memory sheet by high-temperature hot pressing at a temperature higher than the shape memory activation temperature. After the sheet is cooled to normal temperature and the pressure is released, the surface adhesive layer is cured and loses the adhesion effect, and the sheet is easily dispersed in water-based or oil-based drilling fluid and easily enters a leakage passage.

Description

Technical Field

[0001] This invention belongs to the field of drilling fluid technology, specifically relating to a composite shape memory epoxy polymer, its preparation method, and its application. Background Technology

[0002] As oil drilling projects continue to advance into deep wells and complex formations, well leakage problems are becoming increasingly prominent. Leakage channels in complex formations have multi-scale characteristics. Using conventional bridging materials for plugging often results in low success rates due to the poor adaptability of the materials and the difficulty in matching the particle size of the material with the size of the leakage channels.

[0003] Temperature-triggered shape memory materials possess advantages such as large recoverable deformation, high strength, and fast response speed, giving leak-sealing technology an "intelligent" characteristic. These materials utilize the expansion and deformation they undergo at a certain temperature (above room temperature) to seal leaks. They can be compressed and fixed at a certain temperature, and the deformation is preserved at room temperature. When heated to the activation temperature, they expand and recover their shape, successfully bridging and sealing the crack. They exhibit good adaptability to crack size and can easily achieve excellent bridging and sealing effects when used in conjunction with other materials.

[0004] Chinese patent CN113122204A discloses a memory polymer-type temperature-controlled rigid expansion sealant. The process involves mixing oligomer monomers, a crosslinking agent, and a catalyst, injecting the mixture into a mold, undergoing a crosslinking reaction, cooling and demolding, and then granulating to obtain the temperature-controlled rigid expansion sealant. Its activation temperature is 70℃~100℃. Once activated, it can seal cracks of varying openings, has a pressure resistance ≥8MPa, and exhibits low leakage. However, this sealant has an activation temperature below 100℃ and does not disclose expansion parameters.

[0005] Chinese patent CN113652212B discloses a shape memory leak-proofing and sealing system. This shape memory sealing agent composition contains epoxy resin, amine curing agent, reactive diluent, and foaming agent. Based on shape memory materials, the intelligent leak-proofing system allows the sealing fluid to recognize the leak layer temperature and achieve shape change through the shape recovery of the shape memory sealing agent. This develops a thermotropic shape memory intelligent leak-proofing and sealing material, forming an intelligent leak-proofing and sealing technology. The shape memory polymer has a response temperature range of 80-105℃ and a volume expansion rate of 120%. However, the activation temperature of this shape memory sealing agent composition is generally below 100℃, making it unsuitable for temperatures between 100-120℃.

[0006] Chinese patent CN114702722B discloses a high-temperature shape memory foam composite material. This composite material is obtained by mixing an aqueous dispersion of nanoparticles with epoxy monomers to obtain a Pickering emulsion; a curing agent is added to the Pickering emulsion, which is then poured into a mold and cured at a high temperature to obtain the shape memory epoxy foam composite material. This shape memory epoxy foam composite material has a rubber-state storage modulus of 10 MPa; an expansion rate of 350% at a shape memory transition temperature of 100℃; an expansion rate of 50% at a shape memory transition temperature of 170℃; and a crack-sealing pressure resistance of 20 MPa. However, although the activation temperature of this composite material is higher than 100℃, it lacks bonding properties between materials, and the sealing system relies on particle size distribution for sealing. Therefore, the leakage of the high-concentration sealing system implemented is relatively large.

[0007] Existing shape memory plugging products have several limitations. Some have activation temperatures below 100℃. When used in high-temperature deep well plugging operations, they may expand prematurely before entering the leakage space, losing their adaptive leakage size effect. Others, when used as sheet or granular plugging materials in water-based drilling fluids, have poor hydrophilicity, affecting their dispersion in the fluid. Still others use materials of different particle sizes to bridge and fill the plug under pressure. Some flexible materials can act as "bracing and wrapping," but the materials cannot interact and adhere tightly together, resulting in inefficient sealing of cracks and failure to reduce repeated leakage caused by downhole pressure changes.

[0008] Therefore, there is an urgent need for a shape memory plugging material with high activation temperature, good toughness, and simple shaping process that is suitable for fractured formations with high temperature, complex and multi-scale leakage space, and difficulty in matching plugging particle size. Summary of the Invention

[0009] To address the aforementioned problems in the prior art, this invention proposes a composite shape memory epoxy polymer, its preparation method, and its applications.

[0010] In a first aspect, the present invention provides a method for preparing a composite shape memory epoxy polymer, characterized in that the preparation method includes the following steps:

[0011] S1: Mix the water-based epoxy resin emulsion with curing agent system A evenly, and heat to cure to obtain the first cured body;

[0012] S2: Mix the water-based epoxy resin emulsion with curing agent system B evenly, and heat to cure to obtain the second cured body;

[0013] S3: Mix the first cured body and the second cured body to obtain a composite shape memory epoxy polymer.

[0014] As a specific embodiment of the present invention, the waterborne epoxy resin includes at least one of epoxy resin E51, GEM254, epoxy resin GEM370, and polypropylene glycol diglycidyl ether (PPGGE).

[0015] As a specific embodiment of the present invention, the curing agent system A includes at least one of monoamine curing agents, polyamine curing agents, and polyphenolic compounds; preferably selected from at least one of diethylene glycolamine (DGA), tetravinylpentamine-TETA, D230, D400, tannic acid, catechol, and dopamine; more preferably, the curing agent system A is a mixture of diethylene glycolamine-DGA and tetravinylpentamine-TETA, wherein the mass ratio of diethylene glycolamine-DGA to tetravinylpentamine-TETA is (3-8):1.

[0016] As a specific embodiment of the present invention, the mass of the curing agent system A is 30-50% of the mass of the waterborne epoxy resin.

[0017] As a specific embodiment of the present invention, the curing agent system A further includes a binary polyether epoxy, preferably polypropylene glycol diglycidyl ether (PPGGE), and the amount of the binary polyether epoxy added is 5 to 10% of the mass of the waterborne epoxy resin.

[0018] As a specific embodiment of the present invention, in step S1, the heating and curing conditions include: a curing temperature of 60-120℃ and a curing time of 2-6h; preferably, the heating and curing is a stepped temperature rise curing, including curing at 60-80℃ for 4h and curing at 100-120℃ for 2h, wherein the glass transition temperature is measured to be 60-80℃ using a differential thermal scanner.

[0019] As a specific embodiment of the present invention, the present invention adopts a stepped curing and heating mode, which produces a material with better toughness than the mode of curing at a single temperature for a period of time.

[0020] As a specific embodiment of the present invention, the curing agent system B includes at least one of aromatic amine curing agents and polyamine curing agents, preferably selected from at least one of diethyltoluenediamine-DETDA, diaminodiphenyl sulfone-DDS, diaminodiphenylmethane-DDM, tetravinylpentamine-TETA, and polyetheramine D230; more preferably, the curing agent system B is a mixture of diaminodiphenyl sulfone-DDS and tetravinylpentamine-TETA; wherein the mass ratio of diaminodiphenyl sulfone-DDS to tetravinylpentamine-TETA is (1-5):1.

[0021] As a specific embodiment of the present invention, the mass of the curing agent system B is 60-80% of the mass of the waterborne epoxy resin.

[0022] As a specific embodiment of the present invention, in step S2, the heating and curing conditions include: a heating temperature of 60-140℃ and a curing time of 2-12h; preferably, the heating and curing is a stepped temperature rise curing, including curing at 60-80℃ for 3-5h, curing at 100-120℃ for 1-3h, and curing at 120-140℃ for 2-4h, wherein the glass transition temperature measured by a differential thermal scanner is 100-130℃.

[0023] In a specific embodiment of the present invention, in step S3, the mass ratio of the first cured body and the second cured body is (1-2):1;

[0024] The mixing method of the first cured body and the second cured body includes hot pressing into sheets;

[0025] The conditions for hot pressing the first cured body and the second cured body in a 1:1 ratio include: a temperature of 120-160℃ and a pressure of 8-10 MPa.

[0026] The conditions for hot pressing the first cured body and the second cured body in a 2:1 ratio include: a temperature of 120-160℃ and a pressure of 8-12 MPa.

[0027] In a preferred embodiment of the present invention, the first cured body and the second cured body are hot-pressed in a 2:1 ratio. The hot-pressing mode is that the first cured body is stacked on top of the second cured body, and then the first cured body is stacked on top of the first cured body again, wherein the second cured body is located in the middle layer. During the hot-pressing process, the cured bodies are gradually flattened. The sheet-like material obtained by hot pressing is used as a sealing agent. The sheet-like sealing agent has stronger retention than the spherical one, so it is pressed into a sheet shape. Preferably, the sheet thickness is 0.5-1 mm.

[0028] Secondly, the present invention provides a composite shape memory epoxy polymer obtained by the preparation method described in the first aspect, which has an expansion rate of 40-70%.

[0029] Thirdly, the present invention provides the application of the composite shape memory epoxy polymer obtained by the preparation method described in the first aspect or the composite shape memory epoxy polymer described in the second aspect in the field of sealing agents;

[0030] As a specific embodiment of the present invention, a composite shape memory epoxy polymer powder is combined with a leak-sealing material to be used as a leak-sealing agent for sealing cracks.

[0031] As a specific embodiment of the present invention, the composite shape memory epoxy polymer is pulverized into particles of different sizes between 6 and 100 mesh.

[0032] All of the above-mentioned raw materials used in this invention can be prepared in-house or purchased commercially; this invention does not impose any particular limitations on them.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1. The composite shape memory epoxy polymer of the present invention first prepares epoxy resins with different glass transition temperatures (TVTs) using an aqueous epoxy emulsion. Then, an epoxy polymer layer with a lower TVT, higher toughness, and higher viscosity is combined with an epoxy polymer layer with a higher TVT and higher strength to form a low-activation high-viscosity-high-activation high-strength-low-activation high-viscosity composite layer. This composite layer is then hot-pressed at a temperature higher than the shape memory activation temperature to form a shape memory sheet. After the sheet cools to room temperature and the pressure is released, the surface adhesive layer solidifies and loses its adhesive effect, making it easy to disperse in water-based or oil-based drilling fluids and also easy to enter leakage channels.

[0035] 2. As the drilling fluid reaches the high-temperature, high-pressure lost formation, the composite shape memory epoxy polymer of this invention deforms and stores heat to form recovery power. The outer low-activation viscosity layer first expands and bridges in the lost formation. At the same time, the viscosity gradually recovers under high temperature and pressure, adsorbing and adhering to other plugging materials in the surrounding area to form a bridging network structure. The surrounding free plugging particles fill the gap, rapidly reducing the amount of leakage. Meanwhile, the middle layer of high-activation, high-strength shape memory plugging material continues to accumulate energy, gradually expands, and releases elasticity to further compact the plugging layer, improving the pressure-bearing strength and "breathing effect" of the plugging layer.

[0036] 3. The composite shape memory epoxy polymer of this invention simultaneously possesses high activation temperature, high strength, and high toughness. Its shape memory activation temperature is above 130°C. When used as a sealing material, it expands by 62% upon reaching the activation temperature, adapting to the sealing space and matching other sealing particles of different sizes while simultaneously bonding other sealing material particles, thus enhancing the sealing effect. Even at low concentrations, its high-temperature pressure resistance at 150°C reaches over 12.6 MPa, with a leakage rate of less than 50 mL, achieving effective bridging pressure resistance, tight sealing, and an expanded safety density window. Detailed Implementation

[0037] The present invention will be further described below with reference to specific embodiments, but this does not constitute any limitation on the present invention.

[0038] The testing methods used in the various embodiments of this invention include:

[0039] 1. Activation phase transition temperature (Tg) test method:

[0040] The phase transition temperature (Tg) of the prepared thin film was analyzed using a Q100 differential scanning calorimeter. In a nitrogen atmosphere, the temperature was first increased from room temperature to 300℃ at a rate of 10℃ / min, then decreased from 300℃ to -30℃ at a rate of 10℃ / min to eliminate thermal history. Finally, the temperature was increased from -30℃ to 300℃ at a rate of 10℃ / min to analyze the glass transition temperature of the sample.

[0041] 2. Expansion Rate Test Method

[0042] The pressed sheet (thickness H0) is reheated to its Tg temperature, its thickness H1 is measured, and the expansion rate is calculated:

[0043]

[0044] 3. Blocking performance test method

[0045] A novel long fracture plugging experimental device was used to simulate high-temperature and high-pressure conditions downhole to evaluate the pressure-bearing capacity of plugging materials for sealing fractures. The fractures had an aperture of 3×2mm, and the pressure-bearing capacity of the plugging materials for sealing fractures was evaluated at room temperature (25℃) and temperatures ranging from 100 to 180℃.

[0046] Example 1

[0047] This embodiment provides a composite shape memory epoxy polymer and its preparation method, with specific details as follows:

[0048] S1: Mix 100g of waterborne epoxy resin emulsion E51, curing agent diethylene glycolamine-DGA (25% of epoxy resin mass), and tetravinylpentamine-TETA (10% of epoxy resin mass) in the specified ratio and stir evenly. Pour the mixture onto the substrate surface and heat it in an oven to 80℃ for 4 hours and then to 120℃ for 2 hours to obtain the first cured body. The glass transition temperature Tg1 of the first cured body was determined to be 60℃ by DSC.

[0049] S2: Mix 100g of waterborne epoxy resin emulsion E51, curing agent diethyltoluene diamine-DETDA (40% of epoxy resin mass), and polyetheramine D230 (20% of epoxy resin mass) in the specified ratio and stir evenly. Pour the mixture onto the substrate surface and heat it in an oven to 60℃ for 4h, 100℃ for 2h, and 120℃ for 2h to obtain the second cured body. The glass transition temperature Tg2 of the second cured body was determined by DSC to be 100℃.

[0050] S3: The first cured body and the second cured body are stacked together in the order of first cured body + second cured body + first cured body, and hot-pressed into a sheet at 120℃ and 8MPa, and then cooled to room temperature under pressure to obtain a composite shape memory epoxy polymer sheet with a thickness of 0.5mm.

[0051] The composite shape memory epoxy polymer sheet obtained in Example 1 expands by 50% when reheated to 100°C.

[0052] Application Example 1

[0053] The composite shape memory epoxy polymer sheet prepared in Example 1 was pulverized into (10-20 mesh) and (30-50 mesh) particles, mixed in a 1:1 ratio, with a total concentration of 4%. This mixture was then combined with 8% calcium carbonate particles (20-40 mesh) and 0.2% cottonseed hulls (2-3 mm), and added to a 4% bentonite-based slurry to form an experimental plugging slurry. A long crack (3×2 mm) plugging test device was used to test the plugging performance of the composite shape memory epoxy polymer obtained in Example 1 at 120°C. The results showed that the plugging system including the composite shape memory epoxy polymer sheet obtained in Example 1 withstood a pressure of 7 MPa and a leakage of 45 mL.

[0054] Comparative Application Example 1

[0055] 8% calcium carbonate granules (20-40 mesh) were combined with 0.2% cottonseed hulls (2-3 mm) and added to 4% bentonite base slurry to form an experimental plugging slurry. The long crack (3×2 mm) plugging experimental device was used to test at 120℃, and the experimental result was complete leakage.

[0056] Example 2

[0057] This embodiment provides a composite shape memory epoxy polymer and its preparation method, with specific details as follows:

[0058] S1: Mix 100g of waterborne epoxy resin emulsion E51, and use diethylene glycolamine-DGA (25% of the epoxy resin mass) and tetravinylpentamine-TETA (5% of the epoxy resin mass) as curing agents, and polypropylene glycol diglycidyl ether-PPGGE (10% of the epoxy resin mass) as epoxy monomers, and stir evenly. Pour the mixture onto the substrate surface and cure it in an oven at 60℃ for 4 hours and then at 100℃ for 2 hours to obtain the first cured body. The glass transition temperature Tg1 of the first cured body was measured to be 80℃.

[0059] S2: Mix 100g of waterborne epoxy resin emulsion E51, diaminodiphenyl sulfone-DDS (60% of the epoxy resin mass), and tetravinylpentamine-TETA (20% of the epoxy resin mass) and stir evenly. Pour the mixture onto the substrate surface and heat it in an oven to 80℃ for 4 hours, 120℃ for 2 hours, and 140℃ for 2 hours to obtain the second cured body. The glass transition temperature Tg2 of the second cured body was measured to be 130℃.

[0060] S3: The first cured body obtained in step S1 and the second cured body obtained in step S2 are stacked in the order of first cured body + second cured body + first cured body, and hot-pressed at 160℃ and 10MPa, and then cooled to room temperature to obtain a 1mm thick composite shape memory epoxy polymer sheet.

[0061] The composite shape memory epoxy polymer sheet obtained in Example 2, when reheated to 150°C, has an expansion rate of 62%.

[0062] Application Example 2

[0063] The composite shape memory epoxy polymer sheet obtained in Example 2 was pulverized into (10-20 mesh) and (30-50 mesh) particles, mixed in a 3:2 ratio, with a total concentration of 5%. This mixture was then combined with 12% calcium carbonate particles (5% (20-40 mesh) + 7% (100-800 mesh) and 0.4% cottonseed hulls (2-3 mm), and added to a 4% bentonite-based slurry to form an experimental plugging slurry. A 3×2 mm long crack was used for the plugging test, and the plugging performance of the composite shape memory epoxy polymer obtained in Example 2 was tested at 150°C with the above-mentioned experimental plugging slurry added. The experimental results showed that the plugging system including the composite shape memory epoxy polymer sheet obtained in Example 2 withstood a pressure of 12.6 MPa and a leakage of 10 mL.

[0064] Comparative Application Example 2

[0065] A combination of 12% calcium carbonate granules (5% (20-40 mesh) + 7% calcium carbonate (100-800 mesh)) and 0.4% cottonseed hulls (2-3 mm) was added to a 4% bentonite base grout to form an experimental sealing grout. A sealing experiment was conducted using a 3×2 mm long crack, and the above experimental sealing grout was added at 150°C. The experimental result showed complete leakage.

[0066] Example 3

[0067] S1: As in Example 1, except that the curing agents used to prepare the cured body 1 are diethylene glycolamine-DGA (25% of the epoxy resin mass) and D230 (25% of the epoxy resin mass). The cured body is cured at 70°C for 4 hours and at 100°C for 2 hours in an oven to obtain the first cured body. The glass transition temperature Tg1 of the first cured body is measured to be 73°C.

[0068] S2: Diaminodiphenylmethane-DDM (60% of epoxy resin by mass) and tetravinylpentamine-TETA (20% of epoxy resin by mass), cured at 80℃ for 4h, 120℃ for 2h, and 140℃ for 2h to obtain a second cured body. The glass transition temperature Tg2 of the second cured body was measured to be 115℃.

[0069] S3: Stack the first cured body + the second cured body + the first cured body together in the order of hot pressing at 140℃ and 10MPa, and then cool down to room temperature to obtain a 1mm thick composite shape memory epoxy polymer sheet.

[0070] The composite shape memory epoxy polymer sheet obtained in Example 3, when heated to 115°C, has an expansion rate of 43%.

[0071] Application Example 3

[0072] The composite shape memory epoxy polymer flakes obtained in Example 3 were pulverized into (10-20 mesh) and (30-50 mesh) particles, mixed in a 3:2 ratio, with a total concentration of 5%. This mixture was then combined with 10% calcium carbonate particles (5% (20-40 mesh) + 5% (100-800 mesh) and 0.4% polyester fiber 2-3 mm), and added to a 4% bentonite-based slurry. The sealing performance of the system before and after the addition of the shape memory epoxy flakes was tested at 150°C using a long crack (3×2 mm) sealing test apparatus. The sealing system formed in Example 3 withstood a pressure of 9.3 MPa and a leakage rate of 15 mL.

[0073] Comparative Application Example 3

[0074] A combination of 5% calcium carbonate (20-40 mesh) + 5% calcium carbonate (100-800 mesh) and 0.4% polyester fiber (2-3 mm) was added to a 4% bentonite base grout to form an experimental plugging grout. The grout was tested at 150°C using a long crack (3×2 mm) plugging test device. The result was complete leakage.

[0075] Example 4

[0076] S1: Mix 100g of waterborne epoxy resin emulsion E51, curing agents are diethylene glycolamine-DGA (30% of epoxy resin mass) and D400 (20% of epoxy resin mass), and epoxy monomer polypropylene glycol diglycidyl ether-PPGGE (10% of epoxy resin mass) in the following proportions and stir evenly. Pour the mixture onto the substrate surface and cure it in an oven at 60℃ for 4 hours and then at 100℃ for 2 hours to obtain the first cured body. The glass transition temperature Tg1 of the first cured body was measured to be 60℃.

[0077] S2: Mix 100g of waterborne epoxy resin emulsion E51, and the curing agents are diaminodiphenylmethane-DDM (50% of the epoxy resin mass) and D230 (20% of the epoxy resin mass) and stir evenly. Pour the mixture onto the substrate surface and heat it in an oven to 80℃ for 4 hours, 120℃ for 2 hours, and 140℃ for 2 hours to obtain the second cured body. The glass transition temperature Tg2 of the second cured body was measured to be 106℃.

[0078] S3: The first cured body and the second cured body are stacked together in the order of first cured body + second cured body + first cured body, and hot-pressed at 130℃ and 10MPa, and then cooled to room temperature to obtain a 1mm thick composite shape memory epoxy polymer sheet.

[0079] The composite shape memory epoxy polymer sheet obtained in Example 4, when heated to 110°C, has an expansion rate of 46%.

[0080] Application Example 4

[0081] The composite shape memory epoxy polymer sheet obtained in Example 4 was pulverized into (10-20 mesh) and (30-50 mesh) particles, mixed in a 3:2 ratio, with a total concentration of 5%. This mixture was then combined with 12% calcium carbonate particles (5% (20-40 mesh) + 7% (100-800 mesh)) and 0.4% polyester fiber (2-3 mm), and added to a 4% bentonite-based grout to form an experimental plugging slurry. A long crack (3×2 mm) plugging test device was used to test the plugging performance of the composite shape memory epoxy polymer obtained in Example 4 at 150°C. The results showed that the plugging system including the composite shape memory epoxy polymer sheet obtained in Example 4 withstood a pressure of 8.9 MPa and a leakage of 13 mL.

[0082] Comparative Application Example 4

[0083] A combination of 5% calcium carbonate (3% (10-20 mesh) and 2% (30-50 mesh)) + 7% calcium carbonate (100-800 mesh) and 0.4% polyester fiber (2-3 mm) was added to a 4% bentonite base grout. The test was conducted at 150°C using a long crack (3×2 mm) sealing test device. The above-mentioned sealing grout was added, and the test result showed complete leakage.

[0084] Example 5

[0085] S1: Using 100g of waterborne epoxy resin emulsion E51, and diethylene glycolamine-DGA (20% of the epoxy resin mass) and tannic acid (30% of the epoxy resin mass) as curing agents, the first cured body was obtained by curing at 60℃ for 4h and 100℃ for 2h in an oven. The glass transition temperature Tg1 of the first cured body was measured to be 76℃.

[0086] S2: Using 100g of waterborne epoxy resin emulsion E51, and curing agents of diaminodiphenylmethane-DDM (50% of the epoxy resin mass) and polyetheramine D230 (20% of the epoxy resin mass), the second cured body was obtained by curing at 80℃ for 4h, 110℃ for 2h, and 130℃ for 2h. The glass transition temperature Tg2 of the second cured body was measured to be 106℃.

[0087] S3: The first cured body and the second cured body are stacked together in the order of first cured body + second cured body + first cured body, and hot-pressed at 130℃ and 10MPa, and then cooled to room temperature to obtain a 1mm thick composite shape memory epoxy polymer sheet.

[0088] The composite shape memory epoxy polymer sheet obtained in Example 5, when heated to 106°C, has an expansion rate of 45%.

[0089] Application Example 5

[0090] The composite shape memory epoxy polymer sheet obtained in Example 5 was pulverized into (10-20 mesh) and (30-50 mesh) particles, mixed in a 3:2 ratio, with a total concentration of 5%. This mixture was then combined with 10% calcium carbonate particles (5% (20-40 mesh) + 5% (100-800 mesh)) and 0.4% polyester fiber (2-3 mm), and added to a 4% bentonite-based grout to form an experimental plugging slurry. A long crack (3×2 mm) plugging test device was used to test the plugging performance of the composite shape memory epoxy polymer obtained in Example 5 at 150°C. The results showed that the plugging system including the composite shape memory epoxy polymer sheet obtained in Example 5 withstood a pressure of 7.9 MPa and a leakage of 15 mL.

[0091] Comparative Application Example 5

[0092] A combination of 5% calcium carbonate (3% (10-20 mesh) and 2% (30-50 mesh)) + 5% calcium carbonate (2% (20-40 mesh) + 3% (100-800 mesh)) and 0.4% polyester fiber (2-3 mm) was added to a 4% bentonite base grout to form an experimental plugging grout. A long crack (3×2 mm) plugging test device was used to test at 150°C. The above experimental plugging grout was added, and the experimental result was complete leakage.

[0093] Example 6

[0094] S1: Using 100g of waterborne epoxy resin emulsion E51, and diethylene glycolamine-DGA (30% of the epoxy resin mass) and catechol (20% of the epoxy resin mass) as curing agents, the first cured body was obtained by curing at 60℃ for 4h and at 100℃ for 2h. The glass transition temperature Tg1 of the first cured body was measured to be 63℃.

[0095] S2: Using 100g of waterborne epoxy resin emulsion E51 and curing agents of diaminodiphenylmethane-DDM (70% of the epoxy resin mass) and D230 (10% of the epoxy resin mass), the second cured body was obtained by curing at 80℃ for 4h, 120℃ for 2h, and 140℃ for 2h. The glass transition temperature Tg2 of the second cured body was measured to be 121℃.

[0096] S3: The first cured body and the second cured body are stacked together in the order of first cured body + second cured body + first cured body, and hot-pressed at 150℃ and 10MPa, and then cooled to room temperature to obtain a 1mm thick composite shape memory epoxy polymer sheet.

[0097] The composite shape memory epoxy polymer sheet obtained in Example 6, when heated to 121°C, has an expansion rate of 40%.

[0098] Application Example 6

[0099] The composite shape memory epoxy polymer sheet obtained in Example 6 was pulverized into (10-20 mesh) and (30-50 mesh) particles, mixed in a 3:2 ratio, with a total concentration of 5%. This mixture was then combined with 10% calcium carbonate particles (5% (20-40 mesh) + 5% (100-800 mesh) and 0.4% walnut shells (2-3 mm), and added to a 4% bentonite-based grout to form an experimental sealing slurry. A long crack (3×2 mm) sealing test device was used to test the sealing performance of the composite shape memory epoxy polymer obtained in Example 6 at 150°C. The results showed that the sealing system including the composite shape memory epoxy polymer sheet obtained in Example 6 withstood a pressure of 8.3 MPa and a leakage of 15 mL.

[0100] Comparative Application Example 6

[0101] A combination of 5% calcium carbonate (3% (10-20 mesh) and 2% (30-50 mesh)) + 5% calcium carbonate (2% (20-40 mesh) + 3% (100-800 mesh)) and 0.4% walnut shell (2-3 mm) was added to a 6% bentonite base grout to form an experimental sealing grout. A long crack (3×2 mm) sealing test device was used to test the grout at 150°C. The result was that the grout was completely lost.

[0102] Example 7

[0103] S1: Mix 100g of waterborne epoxy resin emulsion E51, and the curing agents are diethylene glycolamine-DGA (20% of the epoxy resin mass) and dopamine (30% of the epoxy resin mass) and stir evenly. Pour the mixture onto the substrate surface and cure it in an oven at 60℃ for 4 hours and then at 100℃ for 2 hours to obtain the first cured body. The glass transition temperature Tg1 of the first cured body was measured to be 72℃.

[0104] S2: Mix 100g of waterborne epoxy resin emulsion E51 with diaminodiphenylmethane-DDM (40% of the epoxy resin mass) and TETA (30% of the epoxy resin mass) as curing agents and stir evenly. Pour the mixture onto the substrate surface and heat it in an oven to 80℃ for 4 hours, 110℃ for 2 hours, and 130℃ for 2 hours to obtain the second cured body. The glass transition temperature Tg2 of the second cured body was determined by DSC to be 101℃.

[0105] S3: The first cured body and the second cured body are stacked together in the order of first cured body + second cured body + first cured body, and hot-pressed at 130℃ and 10MPa, and then cooled to room temperature to obtain a 1mm thick composite shape memory epoxy polymer sheet.

[0106] The composite shape memory epoxy polymer sheet obtained in Example 7, when heated to 101°C, has an expansion rate of 44%.

[0107] Application Example 7

[0108] The composite shape memory epoxy polymer sheet obtained in Example 7 was pulverized into (10-20 mesh) and (30-50 mesh) particles, mixed in a 3:2 ratio, with a total concentration of 5%. This mixture was then combined with 10% calcium carbonate particles (5% (20-40 mesh) + 5% (100-800 mesh)) and 0.4% walnut shells (2-3 mm), and added to a 4% bentonite-based grout to form an experimental sealing slurry. A long crack (3×2 mm) sealing test device was used to test the sealing performance of the composite shape memory epoxy polymer obtained in Example 7 at 150°C. The results showed that the sealing system including the composite shape memory epoxy polymer sheet obtained in Example 7 withstood a pressure of 7.1 MPa and a leakage of 35 mL.

[0109] Comparative Application Example 7

[0110] A combination of 5% calcium carbonate (3% (10-20 mesh) and 2% (30-50 mesh)) + 5% calcium carbonate (2% (20-40 mesh) + 3% (100-800 mesh)) and 0.4% walnut shell (2-3 mm) was added to a 10% bentonite base grout to form an experimental sealing grout. A long crack (3×2 mm) sealing test device was used to test at 150°C. The above experimental sealing grout was added, and the experimental result was complete leakage.

[0111] Example 8

[0112] S1: Using 100g of waterborne epoxy resin emulsion E51, and curing agents of diethylene glycolamine-DGA (20% of epoxy resin mass), dopamine (20% of epoxy resin mass), and D230 (10% of epoxy resin mass), the first cured body was obtained by curing at 60℃ for 4h and at 100℃ for 2h. The glass transition temperature Tg1 of the first cured body was measured to be 70℃.

[0113] S2: Using 100g of waterborne epoxy resin emulsion E51 and curing agents of diaminodiphenylmethane-DDM (70% of the epoxy resin mass) and D400 (10% of the epoxy resin mass), the second cured body was obtained by curing at 80℃ for 4h, 120℃ for 2h, and 140℃ for 2h. The glass transition temperature Tg2 of the second cured body was measured to be 105℃.

[0114] S3: Stack the first cured body obtained in step S1 and the second cured body obtained in step S2 in the order of first cured body + second cured body + first cured body, and hot press at 130℃ and 10MPa, then hold the pressure and cool down to room temperature to obtain a 1mm thick composite shape memory epoxy polymer sheet.

[0115] The composite shape memory epoxy polymer sheet obtained in Example 8, when heated to 105°C, has an expansion rate of 48%.

[0116] Application Example 8

[0117] The composite shape memory epoxy polymer sheet obtained in Example 8 was pulverized into (10-20 mesh) and (30-50 mesh) particles, mixed in a 3:2 ratio, with a total concentration of 5%. This mixture was then added to a 4% bentonite-based grout to form an experimental plugging slurry. The slurry was tested at 150°C using a long crack (3×2mm) plugging experimental apparatus, with the addition of the above-mentioned experimental plugging slurry to test the plugging performance of the composite shape memory epoxy polymer obtained in Example 8. The experimental results showed that the plugging system including the composite shape memory epoxy polymer sheet obtained in Example 8 withstood a pressure of 10.1 MPa and a leakage of 30 mL.

[0118] Comparative Application Example 8

[0119] A combination of 5% calcium carbonate (3% (7-20 mesh) and 2% (30-50 mesh)) + 5% calcium carbonate (2% (20-40 mesh) + 3% (100-800 mesh)) and 0.4% elastic mesh (2-3 mm) was added to a 6% bentonite base grout to form an experimental plugging grout. A long crack (3×2 mm) plugging test device was used to test at 150°C. The above experimental plugging grout was added, and the experimental result was complete leakage.

[0120] Example 9

[0121] S1: Mix 100g of waterborne epoxy resin emulsion E51, and the curing agent is diethylene glycolamine-DGA (20% of the epoxy resin mass), tannic acid (20% of the epoxy resin mass), and TETA (10% of the epoxy resin mass) in a ratio and stir evenly. Pour the mixture onto the substrate surface and cure it in an oven at 60℃ for 4 hours and then at 100℃ for 2 hours to obtain the first cured body. The glass transition temperature Tg1 of the first cured body was measured to be 69℃.

[0122] S2: Mix 100g of waterborne epoxy resin emulsion E51, and the curing agents are diaminodiphenylmethane-DDM (60% of the epoxy resin mass) and D230 (20% of the epoxy resin mass) and stir evenly. Pour the mixture onto the substrate surface and heat it in an oven to 80℃ for 4 hours, 120℃ for 2 hours, and 130℃ for 2 hours to obtain the second cured body. The glass transition temperature Tg2 of the second cured body was measured to be 122℃.

[0123] S3: Stack the first cured body obtained in step S1 and the second cured body obtained in step S2 in the order of first cured body + second cured body + first cured body, and hot press at 150℃ and 10MPa, then hold the pressure and cool down to room temperature to obtain a 1mm thick composite shape memory epoxy polymer sheet.

[0124] The composite shape memory epoxy polymer sheet obtained in Example 9, when heated to 101°C, has an expansion rate of 46%.

[0125] Application Example 9

[0126] The composite shape memory epoxy polymer sheet obtained in Example 9 was pulverized into (10-20 mesh) and (30-50 mesh) particles, mixed in a 3:2 ratio, with a total concentration of 5%. This mixture was then added to a 4% bentonite-based grout to form an experimental plugging slurry. A 3×2mm long crack was used for the plugging test, and the plugging performance of the composite shape memory epoxy polymer obtained in Example 9 was tested at 150°C with the above-mentioned experimental plugging slurry added. The experimental results showed that the plugging system including the composite shape memory epoxy polymer sheet obtained in Example 9 had a pressure resistance of 11.8 MPa and a leakage rate of 15 mL.

[0127] Comparative Application Example 9

[0128] A combination of 5% calcium carbonate (2% (7-10 mesh) + 1% (10-20 mesh) + 2% (30-50 mesh)) + 5% calcium carbonate (2% (20-40 mesh) + 3% (100-800 mesh)) and 0.4% elastic mesh (2-3 mm) was added to a 4% bentonite base grout to form an experimental plugging grout. The plugging test device was used to test the plugging of a 3×2 mm long crack. The above experimental plugging grout was added at 150℃, and the experimental result was complete leakage.

[0129] Example 10

[0130] S1: Using 100g of waterborne epoxy resin emulsion E51, and curing agents of diethylene glycolamine-DGA (20% of epoxy resin mass), catechol (20% of epoxy resin mass), and TETA (10% of epoxy resin mass), the first cured body was obtained by curing at 60℃ for 4h and at 100℃ for 2h. The glass transition temperature Tg1 of the first cured body was measured to be 65℃.

[0131] S2: Using 100g of waterborne epoxy resin emulsion E51 and curing agents of diaminodiphenylmethane-DDM (60% of the epoxy resin mass) and D230 (10% of the epoxy resin mass), the second cured body was obtained by curing at 80℃ for 4h, 110℃ for 2h, and 130℃ for 2h. The glass transition temperature Tg2 of the second cured body was measured to be 110℃.

[0132] S3: Stack the first cured body obtained in step S1 and the second cured body obtained in step S2 in the order of first cured body + second cured body + first cured body, and hot press at 130℃ and 10MPa, then hold the pressure and cool down to room temperature to obtain a 1mm thick composite shape memory epoxy polymer sheet.

[0133] The composite shape memory epoxy polymer sheet obtained in Example 10 expanded by 46% when heated to 105°C.

[0134] Application Example 10

[0135] The composite shape memory epoxy polymer sheet obtained in Example 10 was pulverized into (10-20 mesh) and (30-50 mesh) particles, mixed in a 3:2 ratio, with a total concentration of 5%. This mixture was then combined with 10% calcium carbonate particles (5% (20-40 mesh) + 5% (100-800 mesh) and 0.4% elastic porous mesh (2-3 mm), and added to a 4% bentonite-based grout to form an experimental plugging slurry. A 3×2 mm long crack was used for the plugging test, and the plugging performance of the composite shape memory epoxy polymer obtained in Example 10 was tested at 150°C with the above experimental plugging slurry added. The experimental results showed that the plugging system including the composite shape memory epoxy polymer sheet obtained in Example 10 withstood a pressure of 7.8 MPa and a leakage of 15 mL.

[0136] Comparative Application Example 10

[0137] A combination of 5% calcium carbonate (3% (7-20 mesh) + 2% (30-50 mesh)) + 8% calcium carbonate (2% (20-40 mesh) + 3% (80-100 mesh) + 3% (100-800 mesh)) and 0.4% elastic mesh (2-3 mm) was added to a 4% bentonite base grout to form an experimental plugging grout. The plugging test device was used to test the plugging of a 3×2 mm long crack. At 150°C, the above experimental plugging grout was added and completely leaked out.

[0138] Comparative Example 1

[0139] Steps S1 and S2 are the same as in Example 2, but the sheet pressing in step S3 is different. The specific details are as follows:

[0140] S3: Stack the first cured body and the second cured body in sequence, hot press at 160℃ and 10MPa, hold pressure and cool down to room temperature to obtain a 1mm thick composite shape memory epoxy polymer sheet.

[0141] The composite shape memory epoxy polymer sheet obtained in Comparative Example 1, when heated to 80°C, had an expansion rate of 18%.

[0142] The composite shape memory epoxy polymer sheet obtained in Comparative Example 1 was pulverized into (10-20 mesh) and (30-50 mesh) particles, and mixed in a 4:3 ratio to a total concentration of 7%. This mixture was then combined with 12% calcium carbonate particles (5% (20-40 mesh) + 7% (100-800 mesh)) and 0.4% cottonseed hulls (2-3 mm), and added to a 4% bentonite-based grout to obtain the experimental sealing slurry. A long crack (3×2 mm) sealing test device was used to test the slurry at 150°C. The results showed that the sealing system including the composite shape memory epoxy polymer sheet from Comparative Example 1 withstood a pressure of 6.2 MPa and a leakage of 113 mL; the sealing agent without the shape memory epoxy sheet resulted in complete leakage.

[0143] Comparative Example 2

[0144] Steps S1 and S2 are the same as in Example 2, but the sheet pressing in step S3 is different. The specific details are as follows:

[0145] S3: Stack the two first cured bodies, hot press them at 160℃ and 10MPa, hold the pressure and cool them down to room temperature to obtain a 1mm thick composite shape memory epoxy polymer sheet.

[0146] The composite shape memory epoxy polymer sheet obtained in Comparative Example 2, when heated to 130°C, had an expansion rate of 5%.

[0147] The composite shape memory epoxy polymer sheet obtained in Comparative Example 2 was pulverized into (10-20 mesh) and (30-50 mesh) particles, and mixed in a 4:3 ratio to a total concentration of 7%. This mixture was then combined with 12% calcium carbonate particles (5% (20-40 mesh) + 7% (100-800 mesh)) and 0.4% cottonseed hulls (2-3 mm), and added to a 4% bentonite-based grout to obtain the experimental sealing slurry. A long crack (3×2 mm) sealing test device was used to test the slurry at 150°C. The results showed that the sealing system including the composite shape memory epoxy polymer sheet obtained in Comparative Example 2 withstood a pressure of 8.7 MPa and a leakage of 160 mL.

[0148] Comparative Example 3

[0149] Steps S1 and S2 are the same as in Example 2, but step S3 is different, as detailed below:

[0150] S3: Stack the two pieces of the second cured body, hot press them at 160℃ and 10MPa, hold the pressure and cool them down to room temperature to obtain a 1mm thick composite shape memory epoxy polymer sheet.

[0151] The composite shape memory epoxy polymer sheet obtained in Comparative Example 3, when heated to 140°C, had an expansion rate of 8%.

[0152] The composite shape memory epoxy polymer sheet obtained in Comparative Example 3 was pulverized into (10-20 mesh) and (30-50 mesh) particles, and mixed in a 4:3 ratio to a total concentration of 7%. This mixture was then combined with 12% calcium carbonate particles (5% (20-40 mesh) + 7% (100-800 mesh)) and 0.4% cottonseed hulls (2-3 mm), and added to a 4% bentonite-based grout to obtain the experimental sealing slurry. A long crack (3×2 mm) sealing test device was used to test the slurry at 150°C. The results showed that the sealing system including the composite shape memory epoxy polymer sheet obtained in Comparative Example 3 withstood a pressure of 8.2 MPa and a leakage of 125 mL.

[0153] In summary, the composite shape memory epoxy polymer of this invention first prepares epoxy resins with different glass transition temperatures using an aqueous epoxy emulsion. Then, an epoxy polymer layer with a lower glass transition temperature, higher toughness, and higher viscosity is combined with an epoxy polymer layer with a higher glass transition temperature and higher strength to form a low-activation high-viscosity-high-activation high-strength-low-activation high-viscosity composite layer. This composite layer is then hot-pressed at a temperature higher than the shape memory activation temperature to form a shape memory sheet. After the sheet cools to room temperature and the pressure is released, the surface adhesive layer solidifies and loses its adhesive effect, making it easy to disperse in water-based or oil-based drilling fluids and also easy to enter leakage channels.

[0154] As the drilling fluid reaches the high-temperature, high-pressure lost formation, the epoxy resin deforms and stores heat, accumulating to form recovery power. The outer low-activation viscous layer first expands and bridges the lost formation. At the same time, the viscosity gradually recovers under high temperature and pressure, adsorbing and adhering to other plugging materials in the surrounding area to form a bridging network structure. The surrounding free plugging particles fill the gap, rapidly reducing the amount of leakage. Meanwhile, the middle layer of high-activation, high-strength shape memory plugging material continues to accumulate energy, gradually expands, and releases its elasticity, further densifying the plugging layer and improving its pressure-bearing strength and "breathing effect".

[0155] Composite shape memory epoxy polymers possess high activation temperature, high strength, and high toughness. With a shape memory activation temperature above 130℃, when used as a sealant, it expands by 62% upon reaching the activation temperature, adapting to the sealant space and matching sealant particles of other sizes while simultaneously bonding other sealant particles to enhance the sealing effect. Even at low concentrations, it maintains a high-temperature pressure resistance of over 12.6 MPa at 150℃, with a leakage rate of less than 50 mL, achieving effective bridging pressure resistance, tight sealing, and an expanded safety density window.

[0156] Any numerical value mentioned in this invention, if there is only a two-unit interval between any minimum and any maximum value, includes all values ​​that increase by one unit each time from the minimum to the maximum value. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, or time, is stated as 50-90, in this specification it means specifically listing values ​​such as 51-89, 52-88… and 69-71 and 70-71, etc. For non-integer values, it may be appropriately considered that a unit is 0.1, 0.01, 0.001, or 0.0001. These are merely some specifically specified examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed minimum and maximum values ​​are considered to have been disclosed.

[0157] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for preparing a composite shape memory epoxy polymer, characterized in that, The preparation method includes the following steps: S1: Mix the water-based epoxy resin emulsion with curing agent system A evenly, and heat to cure to obtain the first cured body; S2: Mix the water-based epoxy resin emulsion with curing agent system B evenly, and heat to cure to obtain the second cured body; S3: The first cured body and the second cured body are mixed to obtain a composite shape memory epoxy polymer sheet with a thickness of 0.5-1 mm; The curing agent system A includes at least one of monoamine curing agents, polyamine curing agents, and polyphenolic compounds; The curing agent system B includes at least one of aromatic amine curing agents and polyamine curing agents; The mixture of the first cured body and the second cured body comprises: the first cured body superimposed on the second cured body and then superimposed on the first cured body, wherein the second cured body is located in the middle layer.

2. The preparation method according to claim 1, characterized in that, The waterborne epoxy resin includes at least one of epoxy resin E51, GEM254, and epoxy resin GEM370.

3. The preparation method according to claim 1, characterized in that, The curing agent system A is selected from at least one of diethylene glycolamine-DGA, tetravinylpentamine-TETA, D230, D400, tannic acid, catechol and dopamine.

4. The preparation method according to claim 3, characterized in that, The curing agent system A is a mixture of diethylene glycolamine-DGA and tetravinylpentamine-TETA, wherein the mass ratio of diethylene glycolamine-DGA to tetravinylpentamine-TETA is (3~8):

1.

5. The preparation method according to claim 1, characterized in that, The mass of the curing agent system A is 30-50% of the mass of the waterborne epoxy resin.

6. The preparation method according to any one of claims 1-5, characterized in that, The curing agent system A also includes a binary polyether epoxy, wherein the amount of the binary polyether epoxy added is 5 to 10% of the mass of the waterborne epoxy resin.

7. The preparation method according to claim 6, characterized in that, The binary polyether epoxy is polypropylene glycol diglycidyl ether.

8. The preparation method according to any one of claims 1-5, characterized in that, In step S1, the heating and curing conditions include: a curing temperature of 60-120℃ and a curing time of 2-6 hours.

9. The preparation method according to claim 8, characterized in that, The heat curing process is a stepped temperature curing process, including curing at 60~80℃ for 4 hours and curing at 100~120℃ for 2 hours, wherein the glass transition temperature is 60~80℃.

10. The preparation method according to any one of claims 1-5, characterized in that, The curing agent system B is selected from at least one of diethyltoluenediamine-DETDA, diaminodiphenyl sulfone-DDS, diaminodiphenylmethane-DDM, tetravinylpentamine-TETA, and polyetheramine D230.

11. The preparation method according to claim 10, characterized in that, Curing agent system B is a mixture of diaminodiphenyl sulfone-DDS and tetravinylpentamine-TETA; wherein the mass ratio of diaminodiphenyl sulfone-DDS to tetravinylpentamine-TETA is (1~5):1; and the mass of curing agent system B is 60~80% of the mass of waterborne epoxy resin.

12. The preparation method according to any one of claims 1-5, characterized in that, In step S2, the heating and curing conditions include: a heating temperature of 60-140℃ and a curing time of 2-12h.

13. The preparation method according to claim 12, characterized in that, The heat curing process involves a stepped temperature increase, including curing at 60~80℃ for 3-5 hours, curing at 100~120℃ for 1-3 hours, and curing at 120~140℃ for 2-4 hours.

14. The preparation method according to any one of claims 1-5, characterized in that, In step S3, the mass ratio of the first cured body to the second cured body is (1-2):1; The mixing method of the first cured body and the second cured body includes hot pressing into sheets; The conditions for hot pressing the first cured body and the second cured body in a 1:1 ratio include: a temperature of 120-160℃ and a pressure of 8-10 MPa. The conditions for hot pressing the first cured body and the second cured body in a 2:1 ratio include: a temperature of 120-160℃ and a pressure of 8-12 MPa.

15. A composite shape memory epoxy polymer obtained by the preparation method according to any one of claims 1-5, having an expansion rate of 40-70%.

16. The application of the composite shape memory epoxy polymer obtained by the preparation method according to any one of claims 1-14 or the composite shape memory epoxy polymer according to claim 15 in the field of sealing agents.

17. The application according to claim 16, characterized in that, The composite shape memory epoxy polymer is crushed and combined with a sealing material to be used as a sealing agent for crack sealing.

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