A downhole autonomous net-forming plugging agent, a preparation method and application thereof

Abstract

The application provides a downhole autonomous network forming type plugging agent, a preparation method and application thereof, and belongs to the technical field of drilling fluid leak prevention and plugging. The plugging agent is prepared from the following raw materials: a composite resin matrix, modified polyacrylamide, an acrylic monomer, an ethylene monomer, a first initiator, a curing agent, a filler, a coupling agent, a toughening agent and water. The plugging agent is curled at room temperature, easily enters a formation, rapidly extends / expands at the formation temperature and generates a recovery stress; through three-phase cooperation and staged particle distribution of a flexible phase rebound, a rigid phase bridging and a shape memory network thermal trigger, rapid bridging, adaptive filling, dense self-locking and high pressure bearing are realized; meanwhile, the curing time is wide-range adjustable and the high-temperature strength is reserved; the strength and temperature resistance of the sealing layer are significantly improved, and the plugging is suitable for deep and ultra-deep high-temperature, high-pressure, cross-scale crack / channel sealing.

Description

Technical Field

[0001] This invention belongs to the field of drilling fluid leak prevention and plugging technology, specifically relating to a downhole self-organizing network-type plugging agent, its preparation method, and its application. Background Technology

[0002] Deep and ultra-deep downhole wells commonly face complex leakage conditions characterized by high temperatures, high pressure differentials, and a wide range of fracture / void sizes (from microfractures to millimeter-wide cracks). Traditional granular, fibrous, and sheet-like materials, or conventional thermosetting shape memory plugs, primarily rely on particle bridging and matrix solidification for sealing. Their accessibility and adaptability are highly sensitive to fracture morphology: on the one hand, it is difficult to form a continuous and dense load-bearing pathway in wide fractures / irregular channels; on the other hand, under high temperature and pressure differentials, the plug is prone to extrusion, creep, or brittle fracture, resulting in low plug strength, insufficient temperature resistance, and unstable pressure plateau, making it difficult to meet the requirements for deep and ultra-deep wells. To improve adaptability, existing technologies have attempted to introduce shape memory polymers (SMPs) or expandable structures (such as thermally expandable microspheres, thermoplastic SMP particles / strips) to improve volume expansion and interfacial self-locking capabilities after insertion.

[0003] Chinese patent document CN116064009A discloses a bridging plugging slurry and its preparation method. The bridging plugging slurry utilizes a shape memory alloy with a two-way effect, taking advantage of its shape change under temperature influence, to form a novel plugging slurry with good backflow capability for reservoir plugging operations. However, shape memory alloys such as nickel-titanium alloys are very expensive special metal materials, making their use as a single-use plugging agent economically unfeasible and difficult to apply on a large scale in ordinary wells.

[0004] The literature "Development and Leakage Prevention Mechanism Study of Temperature-Responsive Shape Memory Materials" synthesized a bidirectional shape memory poly(acrylamide-acrylonitrile) crosslinked hydrogel, preparing a temperature-sensitive reversible expansion material. This material exhibits a swelling reversibility rate of 24.06% under high and low temperature cycling from 20℃ to 90℃, a response temperature of 64.61 to 97.84℃, good salt resistance, and can significantly reduce drilling fluid loss and improve filter cake quality. However, its applicable temperature is relatively low, failing to meet the requirements for deep and ultra-deep leakage plugging.

[0005] Existing SMP-based leak sealing technologies still generally suffer from the following common problems:

[0006] 1. Mismatch between trigger temperature window and well temperature: The activation temperature (T_trans) of many non-metallic SMP systems is concentrated around 90-120℃, making it difficult to stably trigger or maintain deformation recovery under deep and ultra-deep working conditions of ≥150℃; if T_trans is increased, the material often becomes brittle, resulting in limited elongation and easy cracking.

[0007] 2. Insufficient load-bearing strength after recovery: Some thermoplastic SMPs mainly soften physically after high-temperature triggering, lacking secondary chemical network support, resulting in rapid stress decay during recovery and low compressive and shear load-bearing capacity. The sealing layer is easily eroded and damaged under high pressure differential.

[0008] 3. Insufficient expansion and scale adaptation: SMP particles are mostly of a single particle size or a single shape, making it difficult to achieve graded filling and continuous force transfer of "micro-sealing + macro-bridging" in multi-scale cracks; when the volume fraction is insufficient, the effective filling rate after expansion is low.

[0009] 4. The contradiction between shape stability and rheology during the pumping stage: SMP needs to maintain its shape (curled / folded) at room temperature (or normal pumping temperature) to facilitate entry, but at the same time the system must have pumpability and low shear viscosity; existing solutions often have the contradiction of premature relaxation / unfolding or excessive rheology during transportation, which leads to difficulties in placement.

[0010] 5. Insufficient interfacial coupling and long-term stability: There is a lack of effective chemical coupling and mechanical synergistic design with rigid fillers (such as quartz sand, core and shell) and flexible matrix / polymer. Although it can temporarily block the opening after expansion, the interfacial bonding and overall load-bearing chain are insufficient. The strength of the sealing layer decreases significantly after thermal cycling and differential pressure cycling.

[0011] 6. Insufficient high-temperature mechanical properties and energy storage modulus: At 150-180℃, the modulus and strength retention rates of some SMP and its composite systems are low, making it difficult to maintain a high pressure-bearing platform and a low leakage rate.

[0012] In contrast, while existing non-SMP shape memory plugging agents can achieve high early strength through initiation-curing, they generally lack temperature-sensitive expansion and recovery stress, and are insufficient in supporting the continuous path of "entry-expansion-self-locking-bearing" in wide cracks / irregular channels, resulting in low sealing layer strength, insufficient temperature resistance and pressure stability. At the same time, their curing time is often limited, making it difficult to cover the field rhythm of different well sections and complex procedures.

[0013] In summary, the treatment of lost circulation in deep and ultra-deep wells urgently requires a plugging system with shape memory as its core and deeply coupled with rigid / flexible plugging phases and chemical curing processes. This system should be able to solidify at room temperature (curling / folding) for easy entry, rapidly extend and release recovery stress at formation temperatures (≥150℃), and form a dense, self-locking, continuous load-bearing pathway with coupling / toughening design. At the same time, it should have a wide-range adjustable curing / solidification time window and high-temperature strength / modulus retention, thereby significantly improving the strength and temperature resistance of the plugging layer and meeting the long-term steady-state plugging requirements of complex lost circulation scenarios in deep and ultra-deep wells. Summary of the Invention

[0014] When lost circulation occurs in deep and ultra-deep formations during drilling, the plugging agent must possess continuous sealing capabilities, including rapid entry, temperature-sensitive expansion, dense self-locking, and re-pressure self-healing. While traditional thermosetting shape memory plugging agents are widely used, they have shortcomings in high-temperature strength, cross-scale matching, adaptive plugging, and controllable triggering. On the one hand, traditional resins experience modulus decay at high temperatures, making it difficult to maintain long-term pressure resistance; on the other hand, conventional granular materials struggle to achieve adaptive behavior of "entering first and then reinforcing" in pores and fractures of different scales, making the plugging layer susceptible to erosion and damage. Therefore, this invention provides a downhole self-forming mesh-type plugging agent, its preparation method, and its application. The sealing agent of this invention exhibits room temperature curling and easy entry into the formation. It rapidly extends / expands and generates recovery stress at formation temperatures (≥150℃). Through the synergy of three phases—flexible phase rebound, rigid phase bridging, and shape memory network thermal triggering—and graded particle size distribution, it achieves rapid bridging, adaptive filling, dense self-locking, and high pressure resistance. Simultaneously, it achieves wide-range adjustable curing time and high-temperature strength retention. It significantly improves the strength and temperature resistance of the sealing layer and is suitable for sealing deep and ultra-deep high-temperature, high-pressure, and multi-scale cracks / channels.

[0015] The technical solution of the present invention is as follows:

[0016] One aspect of the present invention provides a self-forming mesh-type plugging agent for downhole drilling, which is prepared from the following raw materials in parts by weight: The composite resin matrix consists of 25-40 parts, modified polyacrylamide 2-6 parts, acrylic monomers 3-5 parts, ethylene monomers 2-5 parts, first initiator 0.5-1.5 parts, curing agent 1-7 parts, filler 5-15 parts, coupling agent 1-8 parts, toughening agent 1-5 parts, and water 7.5-59.5 parts. The composite resin matrix is ​​composed of composite resin material and shape memory material; the mass of the shape memory material is 20-40% of the mass of the composite resin material.

[0017] According to a preferred embodiment of the present invention, the sealing agent is prepared from the following raw materials in parts by weight: The composition consists of 25-40 parts of composite resin matrix, 2-6 parts of modified polyacrylamide, 3-5 parts of acrylic monomers, 2-5 parts of ethylene monomers, 1 part of first initiator, 1-7 parts of curing agent, 5-15 parts of filler, 3-6 parts of coupling agent, 1-3 parts of toughening agent, and 21-36 parts of water.

[0018] Preferably, the sealing agent is prepared from the following raw materials in parts by weight: The composition consists of 35 parts composite resin matrix, 4 parts modified polyacrylamide, 5 parts acrylic monomers, 5 parts ethylene monomers, 1 part first initiator, 5 parts curing agent, 10 parts filler, 6 parts coupling agent, 3 parts toughening agent, and 26 parts water.

[0019] According to the present invention, the composite resin material is preferably selected from at least two of polyurethane acrylate, polysiloxane modified epoxy resin, epoxy acrylate resin, unsaturated polyester resin, phenolic vinyl ester resin, benzoxazine resin, or thermosetting polyamide / polyimide resin; preferably, the composite resin material is a combination of epoxy acrylate resin, unsaturated polyester resin, phenolic vinyl ester resin, and benzoxazine resin; more preferably, the mass ratio of epoxy acrylate resin, unsaturated polyester resin, phenolic vinyl ester resin, and benzoxazine resin in the composite resin material is (0.1-2):(1-4):(0.5-3):(0.5-3), and most preferably 1:2:3:2.

[0020] Preferably, the epoxy acrylate resin is a water-based epoxy-modified acrylic resin; the unsaturated polyester resin is a Hite acid-type special unsaturated polyester; the phenolic vinyl ester resin is a water-soluble phenolic vinyl ester resin; and the benzoxazine resin is a benzoxazine-modified epoxy resin.

[0021] More preferably, the epoxy acrylate resin has an epoxy equivalent of 500-600 g / eq and a viscosity of 2000-3000 mPa·s at 25°C; the unsaturated polyester resin has a weight-average molecular weight of 3000-15000; the phenolic vinyl ester resin has a weight-average molecular weight of 10000-30000; and the benzoxazine resin has a weight-average molecular weight of 5000-30000.

[0022] According to a preferred embodiment of the present invention, the shape memory material is prepared according to the following method: Bisphenol A type benzoxazine monomer and bisphenol A type epoxy resin are fully dissolved in a mixed solvent of tetrahydrofuran and methyl isobutyl ketone. 4,4′-diaminodiphenyl sulfone is added as a curing agent and benzyl dimethylamine as an accelerator, and the mixture is completely dissolved. The polymer is then obtained through vacuum distillation, degassing, and curing. Mechanical strain is applied under conditions above the glass transition temperature, and the mixture is held under pressure and then cooled to solidify, resulting in a coiled or dense cured body. The cured body is then fiberized, granulated, and sieved, and then immersed in a solution of γ-glycidyl etheroxypropyltrimethoxysilane (KH-560). After soaking, filtration, and drying, a shape memory material is obtained. This invention uses a blend of bisphenol A type benzoxazine monomer and bisphenol A type epoxy resin, employing 4,4′-diaminodiphenyl sulfone as a curing agent. Under staged heating conditions, benzoxazine ring-opening polymerization and epoxy-amine addition reaction occur to construct a high-crosslink density co-network, increasing the glass transition temperature and high-temperature mechanical strength, and forming a programmable shape memory network.

[0023] Preferably, the mass ratio of bisphenol A type benzoxazine monomer to bisphenol A type epoxy resin is 2-4:2, more preferably 3:2; in the mixed solvent of tetrahydrofuran and methyl isobutyl ketone, the volume ratio of tetrahydrofuran to methyl isobutyl ketone is 1:1; the mass ratio of bisphenol A type benzoxazine monomer to the volume ratio of the mixed solvent of tetrahydrofuran and methyl isobutyl ketone is 0.1-0.5 g / mL; the mass of 4,4′-diaminodiphenyl sulfone is 7-9% of the mass of bisphenol A type epoxy resin, more preferably 8%; benzyl dimethylamine The mass of the bisphenol A epoxy resin is 0.01-1%, preferably 0.1%; the curing conditions are as follows: 140℃ for 1 hour, 160℃ for 1.5 hours, 180℃ for 1.5 hours, and 200℃ for 1 hour; the temperature above the glass transition temperature is 10-20℃ above the glass transition temperature; apply 30%-60% mechanical strain and hold under pressure for 5-15 minutes, maintain the deformed state, and cool down to below the glass transition temperature for cooling and shaping; the diameter of the fibers obtained by fiberization is 20-80 mm. The particle size of the γ-glycidoxypropyltrimethoxysilane (KH-560) solution is 2-8 mm in diameter and 20-30 mesh, 40-60 mesh, and 80-100 mesh, respectively. The preparation method of γ-glycidoxypropyltrimethoxysilane (KH-560) solution is as follows: γ-glycidoxypropyltrimethoxysilane (KH-560) is fully dispersed in a mixed solvent of ethanol and water. The mass of γ-glycidoxypropyltrimethoxysilane (KH-560) is 0.5-2% of the mass of the mixed solvent, preferably 1%. The volume ratio of ethanol to water is 1:1. The pH is adjusted to 4.5 using glacial acetic acid. The soaking treatment temperature is room temperature, and the soaking treatment time is 20-40 min.

[0024] According to a preferred embodiment of the present invention, the mass of the shape memory material is 30% of the mass of the composite resin material.

[0025] According to a preferred embodiment of the present invention, the modified polyacrylamide is prepared according to the following method: Acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, polyethylene glycol diacrylate and water are thoroughly mixed and homogeneous. A second initiator is added, and the modified polyacrylamide is obtained through reaction.

[0026] Preferably, the mass ratio of the total mass of 2-acrylamide-2-methylpropanesulfonic acid and polyethylene glycol diacrylate to the mass of acrylamide is 1:13-17, preferably 1:15; the mass ratio of 2-acrylamide-2-methylpropanesulfonic acid to polyethylene glycol diacrylate is 1:(10-12), preferably 1:12; the mass ratio of acrylamide to water is 1:1-3, preferably 1:2; the second initiator is persulfate, preferably sodium persulfate and potassium persulfate, with a mass ratio of sodium persulfate to potassium persulfate of (0.5-2):2, preferably 1:2; the mass of the second initiator is 0.5-2% of the mass of acrylamide; the reaction temperature is 75-85℃, the reaction time is 1-3h, and the reaction is carried out under stirring and anaerobic conditions.

[0027] According to a preferred embodiment of the present invention, the acrylic monomer includes at least one of isoborneol acrylate, hydroxyethyl methacrylate, acrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, butyl acrylate, methyl methacrylate, ethyl 2-propyl acrylate, or isoborneol methacrylate; preferably, the acrylic monomer is a combination of isoborneol acrylate, isoborneol methacrylate, and hydroxyethyl methacrylate in a mass ratio of 4:3:2.

[0028] According to a preferred embodiment of the present invention, the ethylene monomer includes at least one of vinyltoluene, α-methylstyrene, divinylbenzene, acrylonitrile, or methyl vinyl ether; preferably, the ethylene monomer is a combination of vinyltoluene, α-methylstyrene, and divinylbenzene in a mass ratio of 25:8:2.

[0029] According to a preferred embodiment of the present invention, the first initiator comprises at least one of benzoyl peroxide, diisopropyl peroxide dicarbonate, lauroyl peroxide, tert-butyl-2-ethylhexyl peroxide, dicumyl peroxide, tert-butyl peroxyvalerate, di-tert-butyl peroxide, or tert-butyl peroxide benzoate; preferably, it is a combination of lauroyl peroxide, tert-butyl-2-ethylhexyl peroxide, and dicumyl peroxide in a mass ratio of 3:2:1.

[0030] According to a preferred embodiment of the present invention, the curing agent comprises at least two of the following: ammonium persulfate, ammonium chloride, hexamethylenetetramine, dicyandiamide, adipate dihydrazide, 4,4′-diaminodiphenyl sulfone, isophthalic acid dihydrazide, methylhexahydrophthalic anhydride, phenylacetylene, p-toluenesulfonic acid, 2-ethyl-4-methylimidazole, diethanolamine, diethylenetriamine, or triethylenetetramine; preferably, it is a combination of 4,4′-diaminodiphenyl sulfone, methylhexahydrophthalic anhydride, and 2-ethyl-4-methylimidazole in a mass ratio of 2:1:1.

[0031] According to a preferred embodiment of the present invention, the filler comprises at least one of basalt short-cut fibers, barite, quartz sand, aluminum silicate ceramic support, nano-silica, hollow ceramic microspheres, or walnut shells; preferably a combination of basalt short-cut fibers, quartz sand, and hollow ceramic microspheres in a mass ratio of (2-4):(1-3):(1-2), and more preferably 3:2:1.

[0032] According to the present invention, the coupling agent is preferably at least one of hexyltrimethoxysilane (HTMS), γ-aminopropyltriethoxysilane (KH-550), γ-glycidoxypropyltrimethoxysilane (KH-560), γ-methacryloyloxypropyltrimethoxysilane (KH-570), vinyltrimethoxysilane (VTMS), or bis-[3-(triethoxysilane)propyl]tetrasulfide (TESPT); preferably a combination of γ-methacryloyloxypropyltrimethoxysilane (KH-570), γ-glycidoxypropyltrimethoxysilane (KH-560), vinyltrimethoxysilane (VTMS), and bis-[3-(triethoxysilane)propyl]tetrasulfide (TESPT) in a mass ratio of (2-3):(1-2):(1-2):(1-2), more preferably 2:1:1:1.

[0033] According to a preferred embodiment of the present invention, the toughening agent comprises at least one of amine-terminated nitrile rubber, core-shell particles, polyetherimide, dimer acid modified epoxy resin, polyurethane modified epoxy resin or polyethersulfone; preferably a combination of amine-terminated nitrile rubber, dimer acid modified epoxy resin and polyetherimide in a mass ratio of (1-2):(2-3):(1-2), more preferably 2:2:1.

[0034] The second invention provides a method for preparing the above-mentioned self-forming network-type plugging agent in downhole wells, comprising the following steps:

[0035] The composite resin matrix is ​​added to water and thoroughly mixed and dispersed; modified polyacrylamide is added and thoroughly mixed and dispersed to obtain the first mixture; ethylene monomers, acrylic monomers, the first initiator and water are thoroughly mixed and dispersed to obtain the second mixture; the first mixture and the second mixture are thoroughly mixed and dispersed; degassed, and a curing agent, toughening agent, coupling agent and filler are added, and the mixture is reacted to obtain a downhole self-forming network type plugging agent.

[0036] According to a preferred embodiment of the present invention, the mass ratio of water in the first mixture to water in the second mixture is (1.5-2.5):1.

[0037] According to a preferred embodiment of the present invention, the reaction conditions are as follows: stirring at 100-120°C for 25-40 min, followed by standing at 80-110°C for 1-3 h.

[0038] The third aspect of this invention provides the application of the aforementioned self-organizing network-type plugging agent in deep and ultra-deep well plugging.

[0039] According to a preferred embodiment of the present invention, the depth of the deep strata is greater than or equal to 4500m, and the depth of the ultra-deep strata is greater than or equal to 6000m.

[0040] The technical features and beneficial effects of this invention are as follows:

[0041] To address the challenge of existing resin-based plugging materials simultaneously achieving good penetration, tight sealing, and long-term pressure resistance in high-temperature (≥150℃) environments in deep and ultra-deep wells, this invention provides a high-T... g Leak-sealing agent and its preparation method. The raw materials of the leak-sealing agent include a composite resin matrix (composite resin material and programmable high-T... g The composition includes shape memory materials, modified polyacrylamide, acrylic monomers, ethylene monomers, a first initiator, a curing agent, fillers, coupling agents, toughening agents, and water.

[0042] Compared with the prior art, the present invention has the following advantages:

[0043] (1) Shape memory-enabled adaptive sealing of "room temperature curling-high temperature expansion"

[0044] This invention introduces programmable high-T into a composite resin matrix. g Shape memory networks, programmed temperature T prog =T g Deformation and shaping at +10~20℃ results in particles that are "curled / dense" and small in size at room temperature, facilitating rapid entry into leakage channels; when the downhole temperature reaches the activation temperature T... r (The trigger temperature at which the coiled material begins to recover to its extended state, preferably ≥150℃) allows the particles to rapidly extend / expand and release recovery stress, achieving volume filling and interfacial self-locking, significantly reducing cumulative leakage and raising the pressure plateau. After the sealing layer is disturbed, shape memory recovery can also exhibit a "step-to-plateau" self-healing process, improving sealing durability. Typical indicators include: shape retention rate E. f ≥98%, R r (T) r ( / 10min) ≥92%.

[0045] (2) Shape memory phase and "rigid-flexible" synergy improve density and erosion resistance.

[0046] The plugging agent is a compound of a shape memory rigid phase (SMP particles), a flexible plugging phase (a polymer system formed by composite resin materials, modified polyacrylamide, acrylic monomers, and ethylene monomers), and a rigid crosslinking phase (filler): the rigid crosslinking phase forms the initial crosslinking skeleton at the inlet; the flexible phase provides compressibility and resilience to improve accessibility and strain compatibility; the shape memory rigid phase at T... r The lower extension and application of restorative stress compensate for the porosity of the skeleton and thicken the dense layer; the three work together to give the sealing body a comprehensive advantage of high density, strong erosion resistance and stable cyclic pressure bearing, which is suitable for cross-scale pores and cracks.

[0047] (3) Material selection and network design significantly improve high-temperature applicability

[0048] Shape memory materials are preferably high in T g The T segment is precisely controlled by crosslinking density and flexible segment length. r (Adjustable from 150 to 180°C) and recovery rate; combined with heat-resistant resin components (composite resin materials), the plugging agent still has high modulus and thermal stability at high well temperatures, maintains shape memory effect and pressure bearing strength, and meets the service requirements of deep and ultra-deep wells.

[0049] (4) Pumping safety and triggering controllable, avoiding early thickening of the wellbore.

[0050] The system employs a latent / temperature-sensitive initiation-curing design and thermally triggered shape memory activation: maintaining good fluidity and dispersion stability before and during pumping, and upon entering the target layer, adjusting according to the set T value as the formation temperature rises. r Triggering shape memory recovery and network consolidation avoids early thickening or blockage of the wellbore, ensuring a wide operating window and high process safety.

[0051] (5) Grading and Coupling / Toughening to Improve Interface and Mechanical Integration

[0052] Using bimodal or multimodal graded SMP particles and fillers such as quartz sand and walnut shells, the system provides rapid bridging at the inlet and strong reinforcement at the depth. Coupling agents and toughening agents are introduced to improve the multi-interface bonding of resin-filler-skeleton and crack propagation resistance, so that the sealing layer remains dense, stable, erosion-resistant, and vibration-resistant under high temperature and cyclic loading.

[0053] (6) It is easy to prepare and apply and can be carried out quickly on site.

[0054] The construction and particle programming-grading process of shape memory networks is clear and industrially scalable; it has good compatibility with conventional curing agents / fillers / coupling agents / toughening agents, and dispersion, mixing, and pumping can be completed on-site as needed. Under a given process, T r The curing time and particle size can be fine-tuned through the formula, which is convenient for different well-specific solutions for different leakage scales and temperature gradients.

[0055] In summary, the present invention utilizes high T g The shape memory effect, combined with the three-phase synergy of rigid-flexible-shape memory, enables a continuous sealing path of rapid entry, temperature-sensitive extension, dense self-locking, and re-pressure self-healing in deep and ultra-deep high-temperature environments. Compared with traditional resin plugging materials, it significantly improves the sealing efficiency, pressure platform, and service stability, while also taking into account pump controllability and field adaptability. It can effectively solve the plugging problem under complex well leakage conditions. Attached Figure Description

[0056] Figure 1 Infrared spectrum of the shape memory material (SMP) prepared for Example 1;

[0057] Figure 2 Infrared spectrum of the modified polyacrylamide prepared in Example 2;

[0058] Figure 3 A photograph showing the appearance of the sealing agent prepared in Example 1. Detailed Implementation

[0059] The present invention will be further described below with reference to the embodiments. However, the embodiments of the present invention are merely illustrative examples and should not be construed as limiting the present invention under any circumstances.

[0060] Preparation Example 1

[0061] The preparation method of shape memory material (SMP) is as follows:

[0062] (A-1) Pre-reaction: Bisphenol A type benzoxazine and bisphenol A type epoxy resin (bisphenol A diglycidyl ether type, epoxy equivalent 0.51-0.54 equivalents / 100g) were dissolved in a mixed solvent of tetrahydrofuran and methyl isobutyl ketone in a volume ratio of 1:1 at a mass ratio of 3:2. The mass ratio of bisphenol A type benzoxazine monomer to the volume ratio of the mixed solvent of tetrahydrofuran and methyl isobutyl ketone was 1 / 3 g / mL. The mixture was heated and stirred at 450 r / min for 45 min at 65 °C under nitrogen protection until clear and homogeneous. 8 wt% of 4,4′-diaminodiphenyl sulfone relative to the bisphenol A type epoxy resin and 0.1 wt% of benzyl dimethylamine relative to the bisphenol A type epoxy resin were added. After complete dissolution, the pressure was reduced to -0.095 MPa, and about 60% to 70% of the solvent was slowly removed at 60 °C to obtain a homogeneous pre-reaction solution.

[0063] (A-2) Blending and casting: Vacuum degassing for 10 minutes at -0.095MPa, and then pour the system into a mold coated with release agent and preheated to 80°C. Cover the surface with a dustproof film to prevent skin separation.

[0064] (A-3) Staged curing: sequentially heat at 140℃ for 1 hour, 160℃ for 1.5 hours, 180℃ for 1.5 hours, and finally heat at 200℃ for 1 hour to complete the step curing (heating rate 2℃ / min), to obtain a shape memory polymer cured board with a thickness of 2-4 mm.

[0065] (A-4) Shape programming and shaping: Programming temperature T prog = Glass transition temperature +10~20℃; At glass transition temperature (150℃) +15℃, apply 50% strain in a press or three-point bending fixture and hold for 10 min; After cooling to room temperature while maintaining the deformed state, remove the pressure and demold to obtain a cured body in a "curled / dense" state.

[0066] (A-5) Fiberization-Grading-Surface Modification: The solidified body is placed in a hammer crusher and initially crushed into coarse particles of about 5-10 mm in size. The coarse particles are then processed into fibrous materials with a diameter of 20-80 μm and a length of 2-8 mm using a disc pulverizer. After that, the particles are granulated into spherical particles by a high-speed stirring granulator. The particles are then sieved sequentially to obtain multi-grade particles of 20-30 mesh, 40-60 mesh, and 80-100 mesh. A 1% ethanol / water (volume ratio 9:1) solution is prepared using γ-glycidyl etheroxypropyltrimethoxysilane (KH-560). The pH is adjusted to ≈4.5 using glacial acetic acid. The particles are then immersed in the solution at room temperature for 30 min, filtered, and dried at 80℃ for 1 h to obtain SMP particle size ranges for later use.

[0067] Figure 1 Infrared spectrum of the shape memory material (SMP) prepared in Example 1. The spectrum shows that at 3370 cm⁻¹... -1 A broad and strong absorption peak appears nearby, attributed to the -OH stretching vibration, indicating that a large number of hydroxyl groups were generated during the epoxy-amine addition reaction and the ring-opening polymerization of benzoxazine. 2925 cm⁻¹ -1 and 2870 cm -1 The absorption peak at 1608 cm⁻¹ corresponds to the asymmetric and symmetric stretching vibrations of -CH₂-. -1 and 1510 cm -1 The position represents a benzene ring skeletal vibration, preserving the aromatic ring characteristics of the bisphenol A structure. 1242 cm⁻¹ -1 The strong peak at 1105 cm⁻¹ represents the stretching vibration of the aromatic ether bond (Ar-OC). -1 The point represents the stretching vibration of secondary alcohol CO. 1023 cm⁻¹ -1 The peak at 940 cm⁻¹ is characteristic of ether bonds (COC). Compared to uncured bisphenol A type benzoxazine monomers, this peak is more pronounced. -1 The characteristic absorption peaks belonging to the oxazine ring (COC) in the vicinity have largely disappeared, indicating that the oxazine ring has undergone complete ring-opening polymerization. Meanwhile, at 915 cm⁻¹...-1 The significant decrease in the characteristic absorption peak of the epoxy group indicates that a complete addition reaction occurred between the epoxy group and the amine curing agent. (1700~1750 cm⁻¹) -1 No obvious carbonyl absorption peak was observed within the range, ruling out significant oxidation side reactions at high temperatures. These characteristic peaks collectively indicate that bisphenol A benzoxazine and bisphenol A epoxy resin formed a highly crosslinked network structure under the action of 4,4′-diaminodiphenyl sulfone curing agent, successfully constructing a polymer with high glass transition temperature and shape memory function.

[0068] Preparation Example 2

[0069] The preparation method of modified polyacrylamide is as follows:

[0070] (B-1) Premixing and deoxygenation: Acrylamide and deionized water are mixed at a mass ratio of 1:2 and stirred at 300 r / min at 40℃ until homogeneous. At the same time, nitrogen is passed through at a flow rate of 50 mL / min for 10 min to remove oxygen. Then, 2-acrylamide-2-methylpropanesulfonic acid and polyethylene glycol diacrylate (number average molecular weight 400) are added at a mass ratio of 1:12. (The mass ratio of 2-acrylamide-2-methylpropanesulfonic acid + polyethylene glycol diacrylate:acrylamide is 1:15. Stirring is continued until homogeneous to obtain a premixed solution.

[0071] (B-2) Incubation and polymerization: Heat to 70℃ and hold for 10 min. Add a persulfate system consisting of sodium persulfate and potassium persulfate in a mass ratio of 1:2. The amount of persulfate system added is 1 wt% of acrylamide. Heat to 85℃ and stir under a nitrogen atmosphere (maintaining slow stirring at 300 r / min to ensure heat transfer and uniformity) for 2 h. After the reaction is complete, cool to <40℃ to obtain modified polyacrylamide.

[0072] Figure 2 The infrared spectrum of the modified polyacrylamide prepared in Example 2. In the spectrum, 3425 cm⁻¹... -1 The broad peak at 2930 cm⁻¹ represents the superposition of the stretching vibration of amide NH₃ and structural water; -1 The vicinity exhibits both asymmetric and symmetric stretching vibrations of -CH2-. 1667cm -1 The strong absorption peak is the amide I band (C=O stretching vibration); 1610 cm⁻¹ -1 The location corresponds to the amide II band (NH bending vibration). 1450cm -1 The vibration is a -CH2- bending vibration. 1385 cm -1 The vibration at 1040 cm⁻¹ is a CN stretching vibration. -1 A peak of S=O stretching vibration appeared at 1185 cm⁻¹. -1The characteristic absorption of the sulfonic acid group (-SO3H) at this location confirms the successful introduction of the 2-acrylamide-2-methylpropanesulfonic acid unit into the copolymer chain. (1728 cm⁻¹) -1 The weak but distinct carbonyl absorption peak observed at this point is attributed to the ester bond in polyethylene glycol diacrylate, indicating that the crosslinking unit has been chemically bonded into the polymer backbone. Compared with unmodified polyacrylamide, the appearance of characteristic peaks of sulfonic acid groups and ester carbonyl groups in this spectrum, as well as the retention of the amide structure in the polymer backbone, jointly demonstrate the successful preparation of a crosslinked modified polyacrylamide containing sulfonic acid groups. This structure endows the product with good temperature and salt resistance as well as thickening ability.

[0073] Preparation of Comparative Example 1

[0074] The preparation method of modified polyacrylamide is as described in Example 1, except that:

[0075] (B-1) Premixing and deoxygenation: Acrylamide and deionized water are mixed at a mass ratio of 1:2 and stirred at 300 r / min at 40℃ until homogeneous. At the same time, nitrogen gas is passed through at a flow rate of 50 mL / min for 10 min to remove oxygen. Then, 2-acrylamide-2-methylpropanesulfonic acid is added, with a mass ratio of 2-acrylamide-2-methylpropanesulfonic acid to acrylamide of 1:15. Stirring is continued until homogeneous to obtain a premixed solution.

[0076] (B-2) Incubation and polymerization: Heat to 70℃ and hold for 10 min. Add a persulfate system consisting of sodium persulfate and potassium persulfate in a mass ratio of 1:2. The amount of persulfate system added is 1 wt% of acrylamide. Heat to 85℃ and stir under a nitrogen atmosphere (maintaining slow stirring at 300 r / min to ensure heat transfer and uniformity) for 2 h. After the reaction is complete, cool to <40℃ to obtain modified polyacrylamide.

[0077] Example 1

[0078] A self-forming mesh-type plugging agent for downhole drilling is prepared from the following raw materials in parts by weight: 35 parts composite resin matrix, 4 parts modified polyacrylamide, 5 parts acrylic monomer, 5 parts ethylene monomer, 1 part first initiator, 5 parts curing agent, 10 parts filler, 6 parts coupling agent, 3 parts toughening agent and 26 parts water;

[0079] The composite resin matrix is ​​a combination of composite resin material and shape memory material, with the shape memory material accounting for 30 wt% of the composite resin material. The composite resin material comprises, in a mass ratio of 1:2:3:2: epoxy acrylate resin (waterborne epoxy-modified acrylic resin: epoxy equivalent 500-600 g / eq, viscosity 2000-3000 mPa·s at 25℃), unsaturated polyester resin (Haite acid-type special unsaturated polyester (FUCHEM791H): halogen-introduced, oxidation-resistant, ester bond-stable, acid-corrosion-resistant, weight-average molecular weight 5000-10000), phenolic vinyl ester resin (water-soluble phenolic type, weight-average molecular weight 10000-13000, viscosity 300-600 mPa·s at 25℃), and benzoxazine resin (benzoxazine-modified epoxy resin, after curing T...). g The combination of materials with a temperature range of 160-180℃, volume shrinkage <2%, and weight-average molecular weight of 12000-15000; the shape memory material was prepared by the method of Preparation Example 1; the modified polyacrylamide was prepared by the method of Preparation Example 2; the acrylic monomers were a combination of isoborneol acrylate, isoborneol methacrylate, and hydroxyethyl methacrylate in a mass ratio of 4:3:2; the ethylene monomers were a combination of vinyltoluene, α-methylstyrene, and divinylbenzene in a mass ratio of 25:8:2; and the first initiator was a combination of materials with a mass ratio of 3: The curing agent is a combination of lauroyl peroxide, tert-butyl-2-ethylhexyl peroxide, and dicumyl peroxide in a 2:1 mass ratio; the curing agent is a combination of 4,4′-diaminodiphenyl sulfone, methylhexahydrophthalic anhydride, and 2-ethyl-4-methylimidazolium in a 2:1:1 mass ratio; the filler is a combination of basalt chopped fibers (7-13 μm in diameter, 3-6 mm in length), quartz sand (120-150 mesh), and hollow ceramic microspheres (true density 0.35-0.70 g·cm³) in a 3:2:1 mass ratio. -3 The mixture consists of a combination of KH-570, KH-560, VTMS and TESPT in a mass ratio of 2:1:1:1; and a toughening agent consisting of a combination of amine-terminated nitrile rubber (nitrile content 18-26%, number average molecular weight 3000-5000), dimer acid modified epoxy resin (acid value ≤10 mgKOH / g, viscosity 1000-3000 mPa·s at 25℃) and polyetherimide (glass transition temperature ≈215℃) in a mass ratio of 2:2:1.

[0080] The preparation method of the above-mentioned self-forming network-type plugging agent for downhole wells includes the following steps: The composite resin matrix was added to water (16 parts), and stirred at 80℃ and 600 r / min for 20 min to obtain the first mixture; modified polyacrylamide was added, and stirred at 100℃ and 800 r / min for 30 min to obtain the second mixture; ethylene monomers, acrylic monomers, the first initiator, and water (10 parts) were premixed at 110℃ and 800 r / min for 40 min, and then added to the second mixture, and stirred at 100℃ and 1000 r / min for 20 min to obtain the third mixture; the mixture was degassed under a vacuum of -0.08 MPa for 10 min, and then a curing agent, toughening agent, coupling agent, and filler were added, and stirred at 110℃ and 450 r / min for 30 min, and then allowed to stand at 100℃ for 2 h to obtain the sealing agent P1 (e.g. Figure 3 ).

[0081] Example 2

[0082] A self-forming mesh-type plugging agent for downhole drilling is prepared from the following raw materials in parts by weight: 25 parts composite resin matrix, 4 parts modified polyacrylamide, 5 parts acrylic monomer, 5 parts ethylene monomer, 1 part first initiator, 5 parts curing agent, 10 parts filler, 6 parts coupling agent, 3 parts toughening agent and 36 parts water;

[0083] Other raw materials are the same as in Example 1.

[0084] The preparation method of the above-mentioned self-forming network-type plugging agent in the well is the same as in Example 1, and plugging agent P2 is obtained.

[0085] Example 3

[0086] A self-forming mesh-type plugging agent for downhole drilling is prepared from the following raw materials in parts by weight: 30 parts composite resin matrix, 4 parts modified polyacrylamide, 5 parts acrylic monomer, 5 parts ethylene monomer, 1 part first initiator, 5 parts curing agent, 10 parts filler, 6 parts coupling agent, 3 parts toughening agent and 31 parts water;

[0087] Other raw materials are the same as in Example 1.

[0088] The preparation method of the above-mentioned self-forming network-type plugging agent in the well is the same as in Example 1, and plugging agent P3 is obtained.

[0089] Example 4

[0090] A self-forming mesh-type plugging agent for downhole drilling is prepared from the following raw materials in parts by weight: 40 parts composite resin matrix, 4 parts modified polyacrylamide, 5 parts acrylic monomer, 5 parts ethylene monomer, 1 part first initiator, 5 parts curing agent, 10 parts filler, 6 parts coupling agent, 3 parts toughening agent and 21 parts water;

[0091] Other raw materials are the same as in Example 1.

[0092] The preparation method of the above-mentioned self-forming network-type plugging agent in the well is the same as in Example 1, and plugging agent P4 is obtained.

[0093] Example 5

[0094] A self-forming mesh-type plugging agent for downhole drilling is prepared from the following raw materials in parts by weight: 35 parts composite resin matrix, 2 parts modified polyacrylamide, 5 parts acrylic monomer, 5 parts ethylene monomer, 1 part first initiator, 5 parts curing agent, 10 parts filler, 6 parts coupling agent, 3 parts toughening agent and 28 parts water;

[0095] Other raw materials are the same as in Example 1.

[0096] The preparation method of the above-mentioned self-forming network plugging agent in the well is the same as in Example 1, and plugging agent P5 is obtained.

[0097] Example 6

[0098] A self-forming mesh-type plugging agent for downhole drilling is prepared from the following raw materials in parts by weight: 35 parts composite resin matrix, 6 parts modified polyacrylamide, 5 parts acrylic monomer, 5 parts ethylene monomer, 1 part first initiator, 5 parts curing agent, 10 parts filler, 6 parts coupling agent, 3 parts toughening agent and 24 parts water;

[0099] Other raw materials are the same as in Example 1.

[0100] The preparation method of the above-mentioned self-forming network-type plugging agent in the well is the same as in Example 1, and plugging agent P6 is obtained.

[0101] Example 7

[0102] A self-forming mesh-type plugging agent for downhole drilling is prepared from the following raw materials in parts by weight: 35 parts composite resin matrix, 4 parts modified polyacrylamide, 3 parts acrylic monomer, 2 parts ethylene monomer, 1 part first initiator, 5 parts curing agent, 10 parts filler, 6 parts coupling agent, 3 parts toughening agent and 31 parts water;

[0103] Other raw materials are the same as in Example 1.

[0104] The preparation method of the above-mentioned self-forming network-type plugging agent in the well is the same as in Example 1, and plugging agent P7 is obtained.

[0105] Example 8

[0106] A self-forming mesh-type plugging agent for downhole drilling is prepared from the following raw materials in parts by weight: 35 parts composite resin matrix, 4 parts modified polyacrylamide, 5 parts acrylic monomer, 5 parts ethylene monomer, 1 part first initiator, 5 parts curing agent, 10 parts filler, 3 parts coupling agent, 1 toughening agent and 31 parts water;

[0107] Other raw materials are the same as in Example 1.

[0108] The preparation method of the above-mentioned self-forming network-type plugging agent in the well is the same as in Example 1, and plugging agent P8 is obtained.

[0109] Example 9

[0110] A self-forming mesh-type plugging agent for downhole drilling is prepared from the following raw materials in parts by weight: 35 parts composite resin matrix, 4 parts modified polyacrylamide, 5 parts acrylic monomer, 5 parts ethylene monomer, 1 part first initiator, 5 parts curing agent, 5 parts filler, 6 parts coupling agent, 3 parts toughening agent and 31 parts water;

[0111] Other raw materials are the same as in Example 1.

[0112] The preparation method of the above-mentioned self-forming network-type plugging agent in the well is the same as in Example 1, and plugging agent P9 is obtained.

[0113] Example 10

[0114] A self-forming mesh-type plugging agent for downhole drilling is prepared from the following raw materials in parts by weight: 35 parts composite resin matrix, 4 parts modified polyacrylamide, 5 parts acrylic monomer, 5 parts ethylene monomer, 1 part first initiator, 5 parts curing agent, 15 parts filler, 6 parts coupling agent, 3 parts toughening agent and 21 parts water;

[0115] Other raw materials are the same as in Example 1.

[0116] The preparation method of the above-mentioned self-forming network-type plugging agent in the well is the same as in Example 1, and plugging agent P10 is obtained.

[0117] Example 11

[0118] A self-forming mesh-type plugging agent for downhole drilling is prepared from the following raw materials in parts by weight: 35 parts composite resin matrix, 4 parts modified polyacrylamide, 5 parts acrylic monomer, 5 parts ethylene monomer, 1 part first initiator, 1 part curing agent, 10 parts filler, 6 parts coupling agent, 3 parts toughening agent and 30 parts water;

[0119] Other raw materials are the same as in Example 1.

[0120] The preparation method of the above-mentioned self-forming network-type plugging agent in the well is the same as in Example 1, and plugging agent P11 is obtained.

[0121] Example 12

[0122] A self-forming mesh-type plugging agent for downhole drilling is prepared from the following raw materials in parts by weight: 35 parts composite resin matrix, 4 parts modified polyacrylamide, 5 parts acrylic monomer, 5 parts ethylene monomer, 1 part first initiator, 7 parts curing agent, 10 parts filler, 6 parts coupling agent, 3 parts toughening agent and 24 parts water;

[0123] Other raw materials are the same as in Example 1.

[0124] The preparation method of the above-mentioned self-forming network-type plugging agent in the well is the same as in Example 1, and plugging agent P12 is obtained.

[0125] Example 13

[0126] A self-forming mesh-type plugging agent for downhole applications, with the raw material composition as described in Example 1, except that: the mass of the shape memory material is 20% of the mass of the composite resin material; the other raw material compositions are the same as in Example 1.

[0127] The preparation method of the above-mentioned self-forming network-type plugging agent in the well is the same as in Example 1, and plugging agent P13 is obtained.

[0128] Example 14 A self-forming mesh-type plugging agent for downhole applications, with the raw material composition as described in Example 1, except that: the composite resin material is an epoxy acrylic resin (water-based epoxy-modified acrylic resin: epoxy equivalent 500-600 g / eq, viscosity 2000-3000 mPa·s at 25℃) in a mass ratio of 1:3:2, a phenolic vinyl ester resin (water-soluble phenolic type, weight average molecular weight 10000-13000, viscosity 300-600 mPa·s at 25℃), and a benzoxazine resin (benzoxazine-modified epoxy resin, after curing T... g The combination of raw materials (160-180℃, volume shrinkage <2%, weight average molecular weight 12000-15000) is used; the composition of other raw materials is the same as in Example 1.

[0129] The preparation method of the above-mentioned self-forming network plugging agent in the well is the same as in Example 1, and plugging agent P14 is obtained.

[0130] Example 15

[0131] A self-forming mesh-type plugging agent for downhole applications, with the raw material composition as described in Example 1, except that: the acrylic monomer is a combination of isoborneol acrylate and hydroxyethyl methacrylate in a mass ratio of 4:2; the other raw material composition is the same as in Example 1.

[0132] The preparation method of the above-mentioned self-forming network-type plugging agent in the well is the same as in Example 1, and plugging agent P15 is obtained.

[0133] Example 16

[0134] A self-forming mesh-type plugging agent for downholes, with the raw material composition as described in Example 1, except that: the ethylene monomer is a combination of vinyltoluene and α-methylstyrene in a mass ratio of 25:8; the other raw material composition is the same as in Example 1.

[0135] The preparation method of the above-mentioned self-forming network-type plugging agent in the well is the same as in Example 1, and plugging agent P16 is obtained.

[0136] Example 17

[0137] A self-forming mesh-type plugging agent for downholes, with the raw material composition as described in Example 1, except that: the first initiator is a combination of lauroyl peroxide and tert-butyl-2-ethylhexyl peroxide in a mass ratio of 3:2; the other raw material compositions are the same as in Example 1.

[0138] The preparation method of the above-mentioned self-forming network plugging agent in the well is the same as in Example 1, and plugging agent P17 is obtained.

[0139] Example 18

[0140] A self-forming mesh-type plugging agent for downholes, with the raw material composition as described in Example 1, except that: the curing agent is a combination of 4,4′-diaminodiphenyl sulfone and methylhexahydrophthalic anhydride in a mass ratio of 2:1; the other raw material compositions are the same as in Example 1.

[0141] The preparation method of the above-mentioned self-forming network-type plugging agent in the well is the same as in Example 1, and plugging agent P18 is obtained.

[0142] Example 19 A self-forming mesh-type plugging agent for downholes, with the raw material composition as described in Example 1, except that: the filler is a combination of basalt short-cut fibers (diameter 7-13μm, length 3-6mm) and quartz sand (particle size 120-150 mesh) in a mass ratio of 3:2; the other raw material composition is the same as in Example 1.

[0143] The preparation method of the above-mentioned self-forming network-type plugging agent in the well is the same as in Example 1, and plugging agent P19 is obtained.

[0144] Example 20

[0145] A self-forming mesh-type plugging agent for downhole applications, with the raw material composition as described in Example 1, except that: the coupling agent is a combination of KH-570, VTMS, and TESPT in a mass ratio of 2:1:1; the toughening agent is a combination of amine-terminated nitrile rubber (nitrile content 18-26%, number average molecular weight 3000-5000) and dimer acid modified epoxy resin (acid value ≤10 mgKOH / g, viscosity at 25℃ 1000-3000 mPa·s) in a mass ratio of 2:2; and the other raw material compositions are the same as in Example 1.

[0146] The preparation method of the above-mentioned self-forming network-type plugging agent in the well is the same as in Example 1, and plugging agent P20 is obtained.

[0147] Comparative Example 1

[0148] A sealing agent, as described in Example 1, except that modified polyacrylamide is replaced with an equal amount of water. The other raw material composition is the same as in Example 1.

[0149] The preparation method of the above-mentioned sealing agent is the same as that described in Example 1, except that the sealing agent PP1 is obtained.

[0150] Comparative Example 2

[0151] A sealing agent, as described in Example 1, except that the curing agent is replaced with an equal amount of water. The other raw material composition is the same as in Example 1.

[0152] The preparation method of the above-mentioned sealing agent is the same as that described in Example 1, except that the sealing agent PP2 is obtained.

[0153] Comparative Example 3

[0154] A sealing agent, as described in Example 1, except that the acrylic monomers are replaced with an equal amount of water. The other raw material composition is the same as in Example 1.

[0155] The preparation method of the above-mentioned sealing agent is the same as that described in Example 1, except that the sealing agent PP3 is obtained.

[0156] Comparative Example 4

[0157] A sealing agent, as described in Example 1, except that the ethylene monomer is replaced with an equal amount of water. The other raw material composition is the same as in Example 1.

[0158] The preparation method of the above-mentioned sealing agent is the same as that described in Example 1, except that the sealing agent PP4 is obtained.

[0159] Comparative Example 5

[0160] A sealing agent, as described in Example 1, except that the toughening agent is replaced with an equal amount of water. The other raw material composition is the same as in Example 1.

[0161] The preparation method of the above-mentioned sealing agent is the same as that described in Example 1, except that the sealing agent PP5 is obtained.

[0162] Comparative Example 6

[0163] A sealing agent, as described in Example 1, except that the coupling agent is replaced with an equal amount of water. The other raw material composition is the same as in Example 1.

[0164] The preparation method of the above-mentioned sealing agent is the same as that described in Example 1, except that the sealing agent PP6 is obtained.

[0165] Comparative Example 7

[0166] A sealing agent, as described in Example 1, except that the initiator is replaced with an equal amount of water. The other raw material composition is the same as in Example 1.

[0167] The preparation method of the above-mentioned sealing agent is the same as that described in Example 1, except that the sealing agent PP7 is obtained.

[0168] Comparative Example 8

[0169] A sealing agent, as described in Example 1, except that the filler is replaced with an equal amount of water. The other raw material composition is the same as in Example 1.

[0170] The preparation method of the above-mentioned sealing agent is the same as that described in Example 1, except that the sealing agent PP8 is obtained.

[0171] Comparative Example 9

[0172] A sealing agent, as described in Example 1, except that the modified polyacrylamide was prepared by the method of Comparative Example 1; the composition of other raw materials is the same as in Example 1.

[0173] The preparation method of the above-mentioned sealing agent is the same as that described in Example 1, except that the sealing agent PP9 is obtained.

[0174] Comparative Example 10

[0175] A sealing agent, as described in Example 1, except that the shape memory material is replaced with an equal amount of composite resin material; the other raw material composition is the same as in Example 1.

[0176] The preparation method of the above-mentioned sealing agent is the same as that described in Example 1, except that the sealing agent PP10 is obtained.

[0177] Performance Evaluation

[0178] Test Example 1 - Plugging Performance

[0179] Apparatus and conditions: Steel columnar fractured core (fracture length 30cm, fracture height 3cm, fracture width 5mm); confining pressure 15MPa; temperature 150℃. Simulated drilling fluid: 40g / L bentonite, stirred at 2000r / min for 15h, solvent is water.

[0180] Steps: Maintain a constant temperature of 150℃ → Load the core and apply confining pressure → Inject the plugging agent at 10mL / min → Seal and cure for 24 hours → Inject simulated drilling fluid in reverse at 10mL / min, and record the highest stable pressure (pressure bearing) and cumulative leakage.

[0181] "-" indicates that the data is not solidified or there is no valid data.

[0182] Table 1. Sealing performance (150℃)

[0183]

[0184] Analysis: The shape memory phases P1 / P4 / P6 / P12 rapidly extended and released recovery stress after being held at 150℃ for 10 min, forming a dense, self-locking load-bearing pathway combined with the rigid and flexible copolymer phases, significantly reducing cumulative leakage and resulting in a high pressure plateau (≥19MPa). Both excessively low and high filler content (P9, P10) weakened continuous load-bearing capacity. P13 (20% SMP) showed inferior pressure (10.2MPa) and leakage (238mL) compared to P1 (30% SMP), demonstrating that insufficient shape memory phase content weakens volume filling and self-locking capabilities at high temperatures. P14 (lacking unsaturated polyester) had lower performance (16.5MPa) than P1, indicating that unsaturated polyester plays a crucial role in improving toughness and promoting copolymerization with other components. The pressure of P15 (lacking isobornyl methacrylate) and P16 (lacking divinylbenzene) decreased, confirming the role of multifunctional monomers in constructing a three-dimensional network. The necessity of increasing crosslinking density was highlighted. The performance of P17 (lacking dicumyl peroxide) (18.0 MPa) decreased slightly, indicating that the composite initiator system is crucial for achieving a full and stable curing reaction. The compressive strength of P18 (lacking 2-ethyl-4-methylimidazole) (15.8 MPa) decreased, demonstrating that imidazole accelerators are indispensable for achieving deep curing of the amine / anhydride composite curing system. The performance of P19 (lacking hollow ceramic microspheres) and P20 (simplified coupling / toughening system) was also lower than that of P1, confirming the synergistic effect of multi-level fillers in crosslinking and filling, and the role of multi-component coupling / toughening agents in interface reinforcement and stress dissipation. The compressive strength of the comparative phase lacking the key phase decreased significantly, and PP2 could not form a plug without a curing agent. Although the compressive strength (6.8 MPa) of PP9 (linear polyacrylamide) is slightly higher than that of PP1 (5.1 MPa) of completely unmodified polyacrylamide, it is much lower than that of P1, which confirms the key role of cross-linked modified polyacrylamide in improving the overall strength and stability of the system. The compressive strength of PP10 (non-shape memory material) is only 5.8 MPa, which is comparable to that of the comparative example PP1, directly proving that shape memory function is one of the core elements to achieve high compressive strength.

[0185] Test Example 2 - Shape Restoration Effect (E) f / R r / Volume Expansion B)

[0186] Method: The sealant was cured (curing conditions were: stirring at 120℃ for 30 min, then standing at 100℃ for 2 h, and cooling to room temperature) to obtain a cured board; 30×5×2mm test strips were processed; T prog =T g(T of shape memory material (SMP)) g The material volume was compressed by 50% at +15℃, held for 5-8 minutes, and then cooled to room temperature for shaping. The pressure was then removed after cooling. The shaping rate E was tested. f ; in T r Recovery rate R was measured at 150℃ for 10 minutes. r ; The volumetric elongation B of the test strip at 150℃ for 10 min.

[0187] E f =(L u -L0) / (L m -L0)×100%

[0188] R r =(L u -L r ) / (L u -L0)×100%;

[0189] B = (V) t -V0) / V0×100%;

[0190] Where L0 is the initial length, L m For T prog The length L after compressing the material by 50% of its volume. u L is the length of the temporary shape after cooling and setting. r For T r The length after 10 minutes, V0 is the volume after cooling and setting (temporary shape), V t For T r Volume after maintaining for 10 minutes; E f The higher the value, the better the shaping. r The higher the value, the better the shape recovery effect; the higher the value of B, the better the material stretching effect.

[0191] Table 2 Shape Recovery Effect

[0192]

[0193] Analysis: P1, P4, P6, and P12 can all reach E. f ≥99%, R r ≥95% and B≈23.9-25% indicate that rapid expansion and self-locking can be achieved by holding at 150℃ for 10 minutes, consistent with the high pressure resistance / low leakage ratio in Table 1; R of P13 (20% SMP) r Both (92.5%) and B (20.8%) are lower than P1, confirming that sufficient memory phase is the basis for generating large recovery stress and volume expansion; the R values ​​of P14 (lacking unsaturated polyester), P15 (lacking functional monomers), and P16 (lacking crosslinking monomers) are lower than those of P1, confirming that sufficient memory phase is the basis for generating large recovery stress and volume expansion; rBoth P19 (lacking hollow microspheres) and P20 (simplified coupling / toughening) showed varying degrees of decrease, indicating that the crosslinking density and network integrity of the matrix resin directly affect the deformation recovery efficiency and volume expansion of SMP particles. The matrix network acts as an elastic "container," and its integrity is crucial for the function of SMP. r The slight decrease in B indicates that good interfacial bonding helps stress transfer from SMP particles to the entire system, promoting uniform volume expansion. PP2 and PP7 performed the worst due to network deficiency or insufficiency. PP9 had a low recovery rate (87.5%) and elongation (16.8%) because the modified polyacrylamide has a linear structure and weak matrix strength. PP10, which contains no shape memory material, has a negligible volume elongation (<5%), contributed only by thermal expansion, directly proving that the observed volume elongation mainly comes from the shape memory effect.

[0194] Test Example 3 - High Temperature Resistance (T) g (with high temperature strength / retention rate)

[0195] Glass transition temperature (T) g Test (DMA method): Dynamic Mechanical Analyzer (DMA) was used. Test conditions were: temperature range 50-250℃, heating rate 3℃ / min, frequency 1Hz, static load 5N, dynamic load 2N; T g Take the temperature corresponding to the peak value of the loss modulus (E″).

[0196] High-temperature compressive strength and retention rate test: A universal testing machine was used. The test sample was a Φ10×20mm cylindrical specimen of sealant cured (cured at 120℃ for 3h). The test conditions were as follows: the specimen was first kept at 150℃ and 180℃ for 30min respectively, and then kept at the same temperature. The specimen was loaded at a loading rate of 1mm / min until it failed. The maximum pressure at failure was recorded, and the compressive strength was calculated (compressive strength = maximum pressure / specimen cross-sectional area); 180℃ strength retention rate = (180℃ compressive strength / 150℃ compressive strength) × 100%.

[0197] Table 3 High Temperature Resistance

[0198]

[0199] Analysis: The sealing agent of this invention exhibits long-term stable load-bearing capacity at ≥150℃; it is multi-crosslinked with high T g Network-linked / coupling / toughened / graded fillers maintain high-temperature modulus and load-bearing capacity; the 180℃ retention rate (81.4%) of P13 (20% SMP) is lower than that of P1, possibly due to the high T1 of the SMP particles themselves. g Rigidity contributes to the high-temperature modulus of the system; P14 (lacking unsaturated polyester) T gBoth the temperature (158℃) and retention rate (82.7%) were lower than P1, indicating that the unsaturated polyester participated in the copolymerization, improving the overall crosslinking density and heat resistance of the system; P16 (lacking divinylbenzene) had a lower T... g The significant decrease in (157℃) and retention rate (80.9%) confirms that divinylbenzene, as a crosslinking monomer, is crucial for constructing high-T g The key role of high heat-resistant three-dimensional networks; the T of P18 (lacking accelerator) g The heat resistance (157℃) and retention rate (81.2%) also decreased, indicating that incomplete curing impairs heat resistance; the high-temperature performance of P19 (lacking hollow microspheres) and P20 (simplified coupling / toughening) also declined, indicating that good interfacial bonding and optimized filler gradation are crucial for maintaining structural stability and strength at high temperatures; the comparative example generally T g Compared to the low retention rate, PP9 (linearly modified polyacrylamide) had a lower retention rate (76.4%), indicating that the cross-linked polymer network is crucial for maintaining high-temperature strength; notably, PP10 (non-shape memory material) had a lower retention rate (T...). g (158℃) is comparable to P1 (mainly contributed by the composite resin), but its compressive strength at 150℃ and 180℃ is much lower than P1, indicating that shape memory materials not only provide memory function, but also act as high-temperature precipitates. g Rigid packing also significantly enhances the overall mechanical strength of the system.

[0200] Comprehensive analysis

[0201] Blocking-memory collaboration is key to platform elevation. Shape memory phase in T r =R is generated within 10 minutes at 150℃ r With ≥93% and B>20%, on the one hand, volume expansion / interface self-locking rapidly reduces cumulative leakage; on the other hand, it works synergistically with rigid quartz sand and other graded bridging and flexible phase rebound to form a dense and continuous load-bearing pathway, corresponding to a higher pressure plateau and lower leakage. The grade and content window determine the "accessibility-strength" balance. P9 and P10 prove that too low filler content results in insufficient bridging, while too high content weakens resin bonding; P13 confirms that sufficient SMP content (e.g., 30%) is a necessary condition for achieving high recovery stress and volume filling, thereby obtaining the optimal sealing effect; P14 proves the irreplaceable role of unsaturated polyester resin in improving the overall toughness and crosslinking density of the system; P15, P16, P17, and P18 respectively prove the decisive role of multifunctional monomers (isobornyl methacrylate, divinylbenzene), composite initiators, and curing accelerators in constructing a high crosslinking density, high-performance three-dimensional network; P19 and P20 verify the key synergistic role of multi-level fillers in bridging filling and multi-element coupling / toughening systems in enhancing interfaces and dissipating energy. The three-dimensional network structure determines high-temperature stability. (High T) gMulti-crosslinked shape memory network + silane coupling + toughening brings T g Strength retention rate at approximately 160℃ and 180℃ is approximately 85%. The optimal balance between rapid bridging and high-temperature self-locking is achieved in P1 with 10wt% filler and SMP particles. The absence of key components (such as PP1, PP3-PP6, and PP8) will lead to R... r The pressure drop, pressure resistance, and retention rate all declined simultaneously; PP2 (without curing agent) failed to solidify, verifying the decisive role of the curing process; PP9 (linear polyacrylamide) demonstrated the key role of cross-linked modified polyacrylamide in improving the strength and stability of the matrix; PP10 (shape memory-free material) directly proved that the core of this invention—shape memory function—is an indispensable part of achieving high pressure resistance and low leakage sealing effect, and its performance is comparable to the control group without SMP, and far lower than the preferred embodiment containing SMP.

[0202] Overall optimal sample: P1. In the three types of tests, P1 exhibits the following advantages: effective sealing at a pressure of 19.3 MPa, cumulative leakage of 35 mL; shape retention rate of 99.2%, and R... r 96.5%, B24.7%; Temperature resistance: T g The strength retention rate at 160℃ and 180℃ is 84.7%. Its formulation is similar to that of "high-T". g The coupling mechanism of "shape memory network + rigid / flexible synergy + graded particle distribution" provides an integrated solution for deep and ultra-deep well leakage at ≥150℃, which includes rapid entry, temperature-sensitive extension, dense self-locking, and stable pressure bearing.

[0203] In summary, the sealant of this invention exhibits excellent performance in three dimensions: sealing performance, shape recovery, and high temperature resistance. In particular, the P1 embodiment demonstrates the best combination of high memory efficiency, high temperature strength, and pressure stability, making it suitable for rapid on-site treatment and long-term stable sealing of various types of high-temperature leakage channels.

[0204] While the present invention has been described with reference to specific embodiments, those skilled in the art will understand that various changes can be made without departing from the true spirit and scope of the invention. Furthermore, numerous modifications can be made to the subject, spirit, and scope of the invention to suit specific situations, materials, material compositions, and methods. All such modifications are included within the scope of the claims of the present invention.

Claims

1. A self-forming network-type plugging agent for downhole wells, characterized in that, It is prepared from the following parts by mass of raw materials: The composite resin matrix consists of 25-40 parts, modified polyacrylamide 2-6 parts, acrylic monomers 3-5 parts, ethylene monomers 2-5 parts, first initiator 0.5-1.5 parts, curing agent 1-7 parts, filler 5-15 parts, coupling agent 1-8 parts, toughening agent 1-5 parts, and water 7.5-59.5 parts. The composite resin matrix is ​​composed of composite resin material and shape memory material; the mass of the shape memory material is 20-40% of the mass of the composite resin material. The composite resin material is at least two of the following: polyurethane acrylate, polysiloxane-modified epoxy resin, epoxy acrylate resin, unsaturated polyester resin, phenolic vinyl ester resin, benzoxazine resin, or thermosetting polyamide / polyimide resin; wherein the epoxy acrylate resin is a waterborne epoxy-modified acrylic resin; the unsaturated polyester resin is a Hite acid-type special unsaturated polyester; the phenolic vinyl ester resin is a water-soluble phenolic vinyl ester resin; and the benzoxazine resin is a benzoxazine-modified epoxy resin. Shape memory materials are prepared according to the following method: Bisphenol A type benzoxazine monomer and bisphenol A type epoxy resin are fully dissolved in a mixed solvent of tetrahydrofuran and methyl isobutyl ketone. 4,4′-diaminodiphenyl sulfone is added as a curing agent and benzyl dimethylamine as an accelerator until complete dissolution. The polymer is then obtained through vacuum distillation, degassing, and curing. Mechanical strain is applied at a temperature higher than the glass transition temperature, and the mixture is held under pressure and then cooled to solidify, resulting in a coiled or dense cured body. The cured body is then fiberized, granulated, and sieved, and then immersed in a solution of γ-glycidyl etheroxypropyltrimethoxysilane (KH-560). After immersion treatment, filtration, and drying, a shape memory material is obtained. In the shape memory material preparation method, the mass ratio of bisphenol A type benzoxazine monomer to bisphenol A type epoxy resin is 2-4:2; the mixed solvent of tetrahydrofuran and methyl isobutyl ketone... The volume ratio of tetrahydrofuran to methyl isobutyl ketone is 1:1; the mass ratio of bisphenol A type benzoxazine monomer to the mixed solvent of tetrahydrofuran and methyl isobutyl ketone is 0.1-0.5 g / mL; the mass of 4,4′-diaminodiphenyl sulfone is 7-9% of the mass of bisphenol A type epoxy resin; the mass of benzyl dimethylamine is 0.01-1% of the mass of bisphenol A type epoxy resin; the curing conditions are as follows: 140℃ for 1 h, 160℃ for 1.5 h, 180℃ for 1.5 h, and 200℃ for 1 h; the temperature is 10-20℃ above the glass transition temperature; apply 30%-60% mechanical strain and hold for 5-15 min, maintain the deformed state and cool to below the glass transition temperature for cooling and shaping; the diameter of the fiber obtained by fiberization is 20-80 mm. The particle size of the particles obtained by sieving is 20-30 mesh, 40-60 mesh, and 80-100 mesh. The preparation method of γ-glycidoxypropyltrimethoxysilane (KH-560) solution is as follows: γ-glycidoxypropyltrimethoxysilane (KH-560) is fully dispersed in a mixed solvent of ethanol and water, the mass of γ-glycidoxypropyltrimethoxysilane (KH-560) is 0.5-2% of the mass of the mixed solvent, the volume ratio of ethanol to water is 1:1, and the pH is adjusted to 4.5 with glacial acetic acid. The soaking treatment temperature is room temperature, and the soaking treatment time is 20-40 min. Acrylic monomers include at least one of isoborneol acrylate, hydroxyethyl methacrylate, acrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, butyl acrylate, methyl methacrylate, ethyl 2-propyl acrylate, or isoborneol methacrylate. Ethylene monomers include at least one of vinyltoluene, α-methylstyrene, and divinylbenzene; Modified polyacrylamide was prepared according to the following method: Acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, polyethylene glycol diacrylate and water are thoroughly mixed and homogeneous. A second initiator is added, and the modified polyacrylamide is obtained through reaction.

2. The downhole self-forming network plugging agent according to claim 1, characterized in that, The composite resin material is a combination of epoxy acrylate resin, unsaturated polyester resin, phenolic vinyl ester resin and benzoxazine resin; in the composite resin material, the mass ratio of epoxy acrylate resin, unsaturated polyester resin, phenolic vinyl ester resin and benzoxazine resin is (0.1-2):(1-4):(0.5-3):(0.5-3).

3. The downhole self-forming network plugging agent according to claim 1, characterized in that, The epoxy acrylate resin has an epoxy equivalent of 500-600 g / eq and a viscosity of 2000-3000 mPa·s at 25°C; the unsaturated polyester resin has a weight-average molecular weight of 3000-15000; the phenolic vinyl ester resin has a weight-average molecular weight of 10000-30000; and the benzoxazine resin has a weight-average molecular weight of 5000-30000.

4. The downhole self-forming network plugging agent according to claim 1, characterized in that, In the preparation method of modified polyacrylamide, the mass ratio of the total mass of 2-acrylamide-2-methylpropanesulfonic acid and polyethylene glycol diacrylate to acrylamide is 1:13-17; the mass ratio of 2-acrylamide-2-methylpropanesulfonic acid to polyethylene glycol diacrylate is 1:(10-12); the mass ratio of acrylamide to water is 1:1-3; the second initiator is persulfate; the mass of the second initiator is 0.5-2% of the mass of acrylamide; the reaction temperature is 75-85℃, the reaction time is 1-3h, and the reaction is carried out under stirring and anaerobic conditions.

5. The downhole self-forming network plugging agent according to claim 1, characterized in that, Includes one or more of the following conditions: i. The mass of the shape memory material is 30% of the mass of the composite resin material; ii. The first initiator includes at least one of benzoyl peroxide, diisopropyl peroxide dicarbonate, lauroyl peroxide, tert-butyl-2-ethylhexyl peroxide carbonate, dicumyl peroxide, tert-butyl peroxyvalerate, di-tert-butyl peroxide, or tert-butyl peroxide. iii. The curing agent includes at least two of the following: ammonium persulfate, hexamethylenetetramine, dicyandiamide, adipate dihydrazide, 4,4′-diaminodiphenyl sulfone, isophthalic acid dihydrazide, methylhexahydrophthalic anhydride, 2-ethyl-4-methylimidazole, diethanolamine, diethylenetriamine, or triethylenetetramine. iv. The filler includes at least one of the following: basalt short-cut fibers, barite, quartz sand, aluminum silicate ceramic proppant, nano silica, hollow ceramic microspheres, or walnut shells. v. The coupling agent is at least one of hexyltrimethoxysilane (HTMS), γ-aminopropyltriethoxysilane (KH-550), γ-glycidyl etheroxypropyltrimethoxysilane (KH-560), γ-methacryloyloxypropyltrimethoxysilane (KH-570), vinyltrimethoxysilane (VTMS) or bis-[3-(triethoxysilyl)propyl]tetrasulfide (TESPT); vi. Toughening agents include at least one of amine-terminated nitrile rubber, polyetherimide, dimer acid modified epoxy resin, polyurethane modified epoxy resin, or polyethersulfone.

6. The downhole self-forming network plugging agent according to claim 1, characterized in that, Includes one or more of the following conditions: i. The acrylic monomers are a combination of isoborneol acrylate, isoborneol methacrylate and hydroxyethyl methacrylate in a mass ratio of 4:3:2; ii. The ethylene monomers are a combination of vinyltoluene, α-methylstyrene and divinylbenzene in a mass ratio of 25:8:2; iii. The first initiator is a combination of lauroyl peroxide, tert-butyl-2-ethylhexyl peroxide and dicumyl peroxide in a mass ratio of 3:2:1; iv. The curing agent is a combination of 4,4′-diaminodiphenyl sulfone, methylhexahydrophthalic anhydride and 2-ethyl-4-methylimidazole in a mass ratio of 2:1:1; v. The filler is a combination of basalt short-cut fibers, quartz sand and hollow ceramic microspheres in a mass ratio of (2-4):(1-3):(1-2); vi. The coupling agent is a combination of γ-methacryloyloxypropyltrimethoxysilane (KH-570), γ-glycidyl etheroxypropyltrimethoxysilane (KH-560), vinyltrimethoxysilane (VTMS) and bis-[3-(triethoxysilyl)propyl]tetrasulfide (TESPT) in a mass ratio of (2-3):(1-2):(1-2):(1-2). vii. The toughening agent is a combination of amine-terminated nitrile rubber, dimer acid-modified epoxy resin and polyetherimide in a mass ratio of (1-2):(2-3):(1-2).

7. The method for preparing the downhole self-forming network-type plugging agent as described in any one of claims 1-6, characterized in that, Including the following steps: The composite resin matrix is ​​added to water and thoroughly mixed and dispersed; modified polyacrylamide is added and thoroughly mixed and dispersed to obtain the first mixture; ethylene monomers, acrylic monomers, the first initiator and water are thoroughly mixed and dispersed to obtain the second mixture; the first mixture and the second mixture are thoroughly mixed; degassed, and a curing agent, toughening agent, coupling agent and filler are added, and the mixture is reacted to obtain a downhole self-forming mesh-type plugging agent; The mass ratio of water in the first mixture to water in the second mixture is (1.5-2.5):1; the reaction conditions are as follows: stir at 100-120℃ for 25-40 min, and then let stand at 80-110℃ for 1-3 h.

8. The application of the self-forming network-type plugging agent as described in any one of claims 1-6 in deep and ultra-deep well plugging, characterized in that, The depth of deep strata is greater than or equal to 4500m, and the depth of ultra-deep strata is greater than or equal to 6000m.

Images