Preparation method of heterogeneous gel plugging agent, plugging agent and ion-enhanced plugging agent

Abstract

This invention discloses a method for preparing a heterogeneous gel plugging agent, as well as the plugging agent and an ion-reinforced plugging agent, belonging to the field of drilling fluid plugging technology. It utilizes ε-caprolactone ring-opening polymerization to prepare a reversibly molten monomer with a semi-crystalline structure, which is then applied to the preparation of shape memory hydrogel plugging agents. This invention obtains a monomer containing semi-crystalline hydrophobic side chains through bulk polymerization. After heating and stirring the monomer with the semi-crystalline hydrophobic side chains, along with a hydrophilic monomer, an unsaturated carboxylic acid monomer, and a toughening monomer until homogeneous, photo-initiated polymerization is performed to obtain a heterogeneous gel plugging agent. This heterogeneous gel plugging agent exhibits good mechanical properties. Immersing the above heterogeneous gel in a metal solution yields a heterogeneous gel-ion-reinforced plugging agent with a metal supramolecular hydrophilic framework and semi-crystalline lipophilic side chains. The metal-coordinated crosslinked heterogeneous gel-ion-reinforced plugging agent exhibits even superior mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of drilling fluid plugging technology, specifically relating to a method for preparing a heterogeneous gel plugging agent, as well as the plugging agent and an ion-enhanced plugging agent. Background Technology

[0002] Fracture-related leakage is a common and complex form of leakage during drilling, accounting for over 90% of the total cost of well leakage plugging. Based on different mechanisms and functions, plugging materials are mainly classified into bridging plugging materials, high-fluid-loss plugging materials, temporary plugging materials, chemical plugging materials, inorganic cementitious plugging materials, soft and hard plugging materials, high-temperature plugging materials, and composite plugging materials.

[0003] Bridging and sealing is a convenient and cost-effective method commonly used for on-site treatment of fracture-related leaks. This method requires precise knowledge of the leak channel dimensions and proper matching of the bridging and sealing material. However, the characteristic parameters of formation fractures (aperture, depth, etc.) are uncertain and multi-scale. Inappropriate particle size distribution of the sealing material can easily lead to blockages or flow into deeper formations with the sealing slurry, resulting in sealing failure. Traditional bridging plugging materials (plant particles, mineral particles, mica flakes, fiber materials, etc.) are highly sensitive to fracture aperture and cannot adaptively and effectively seal fractures. Water-absorbing and expanding resin plugging materials reduce dependence on the size of the leakage channel, but have weak temperature resistance, affect drilling fluid rheology, and have low strength after expansion (viscoelastic body), resulting in insufficient pressure bearing capacity of the plugging layer. Chemical gel plugging agents have good adaptive effects, but the on-site construction process is complex, and the product's temperature resistance and pressure bearing capacity need to be improved. When dealing with severe leakage with large fracture apertures, conventional large-size, high-density plugging materials have poor suspension stability, are prone to settling in mud tanks and long open-hole wellbores, and pose a risk of clogging drilling tools.

[0004] As oil drilling continues to advance towards informatization, intelligence, and automation, intelligent new materials will be increasingly applied in drilling. Shape memory materials are a type of intelligent material. These materials possess an initial shape, which, after being deformed and fixed under certain conditions, can return to its initial shape upon stimulation by external conditions (such as heat, electricity, light, and chemical induction). For example, Bao Dan reported a thermotropic shape memory "intelligent" plugging agent that can adaptively match the width of the leaking layer fracture within a certain range, achieving high plugging efficiency and realizing temperature-sensitive, adaptive, and efficient plugging. However, although plugging materials based on shape memory polymers have high strength, their deformation is small, resulting in poor plugging effect on large scales. Furthermore, their density is heavier than water, leading to poor suspension stability.

[0005] Therefore, developing a gel-based sealant that adapts to crack shape can help improve the sealing range of smart sealants and is expected to become a new generation of smart sealant materials. Summary of the Invention

[0006] The first objective of this invention is to provide a method for preparing a heterogeneous gel plugging agent, which utilizes the ring-opening polymerization of ε-caprolactone to prepare a monomer containing a semi-crystalline hydrophobic side chain. This monomer containing the semi-crystalline hydrophobic side chain is then photo-initiated with other monomers to obtain a heterogeneous gel plugging agent. The semi-crystalline regions in the network melt at high temperatures and recrystallize at low temperatures, exhibiting good thermal reversibility.

[0007] A second objective of this invention is to provide a heterogeneous gel sealing agent that has good thermal reversibility.

[0008] The third objective of this invention is to provide a heterogeneous gel-ion-reinforced sealing agent. The heterogeneous gel is immersed in a metal solution for a long time. Under the drive of osmotic pressure, the metal ions in the solution diffuse into the heterogeneous gel network. The metal ions diffused into the gel network can form metal coordination bonds with the COO- groups in the hydrophilic network, thereby forming a second crosslink in the heterogeneous gel network. The mechanical strength of the resulting heterogeneous gel-ion-reinforced sealing agent is further improved.

[0009] This invention is achieved through the following technical solution:

[0010] In a first aspect, the present invention provides a method for preparing a heterogeneous gel plugging agent, comprising the following steps:

[0011] An intermediate was prepared by ring-opening polymerization of ε-caprolactone as a raw material under the action of an initiator and a catalyst.

[0012] An acid-binding agent was added to the intermediate, and after complete dissolution, an acryloyl chloride monomer was added dropwise. After the reaction, a monomer containing a semi-crystalline hydrophobic side chain was obtained.

[0013] After heating and stirring the monomer containing semi-crystalline hydrophobic side chains with hydrophilic monomers, unsaturated carboxylic acid monomers and toughening monomers until uniform, photo-initiated polymerization is carried out to obtain a heterogeneous gel sealing agent.

[0014] The molar ratio of the monomer containing the semi-crystalline hydrophobic side chain to the total monomer is 0.5-2.5:100; the molar ratio of the toughening monomer to the total monomer is 15-35:100.

[0015] Further, in a preferred embodiment of the present invention, the initiator is an alcohol compound, a carboxylic acid compound, or water. Further, in a preferred embodiment of the present invention, the alcohol compound includes one or more of ethanol, ethylene glycol, methanol, butanol, glycerol, cetyl alcohol, and benzyl alcohol.

[0016] The carboxylic acid compounds include one or more of oxalic acid, glycolic acid, malic acid, and citric acid;

[0017] Further, in a preferred embodiment of the present invention, the catalyst includes an alkali metal catalyst, a rare earth catalyst, an enzyme catalyst, or a cationic catalyst. Further, in a preferred embodiment of the present invention, the unsaturated carboxylic acid monomer includes acrylic acid or methacrylic acid;

[0018] The hydrophilic monomers are N,N-dimethylacrylamide, N-isopropylacrylamide, N-ethylacrylamide, N,N-dimethylmethylacrylamide, N,N-diethylmethylacrylamide or N,N′-(1,2-dihydroxyethylene)diacrylamide.

[0019] Furthermore, in a preferred embodiment of the present invention, the toughening monomer includes 2-methoxyethyl acrylate, glycidyl methacrylate, or 2-hydroxyethyl acrylate.

[0020] Furthermore, in a preferred embodiment of the present invention, in the step of preparing the intermediate, the ring-opening polymerization temperature is 110-120°C and the time is 12-18h.

[0021] Furthermore, in a preferred embodiment of the present invention, in the above-mentioned step of preparing the heterogeneous gel plugging agent, the heating temperature is 65-75°C; the photo-initiated polymerization is carried out under ultraviolet light for 1-2 hours.

[0022] Secondly, the present invention provides a heterogeneous gel plugging agent, mainly prepared by the above-described preparation method.

[0023] Thirdly, the present invention provides a heterogeneous gel-ion-enhanced plugging agent, which is obtained by immersing the plugging agent prepared by the above preparation method in a metal ion solution; the molar mass ratio of the metal ion solution to the unsaturated carboxylic acid monomer is 3:(1-3).

[0024] Furthermore, in a preferred embodiment of the present invention, the metal ion solution is selected from iron ion solution, zinc ion solution, copper ion solution, and rare earth ion solution.

[0025] Compared with the prior art, the present invention has at least the following technical effects:

[0026] The method for preparing the heterogeneous gel plugging agent of the present invention utilizes the ring-opening polymerization of ε-caprolactone to prepare a monomer containing a semi-crystalline hydrophobic side chain. This monomer containing the semi-crystalline hydrophobic side chain is then photo-initiated with other monomers to obtain the heterogeneous gel plugging agent. The semi-crystalline regions in the network melt at high temperatures and recrystallize at low temperatures, exhibiting good thermal reversibility. This reversibility endows the plugging material with shape self-adaptability. By changing its shape at high temperatures and fixing its shape at low temperatures, it is then excited in the formation and gradually expands during the process of returning to its original shape, thus adaptively sealing the formation.

[0027] The present invention relates to a heterogeneous gel sealing agent, which has good thermal reversibility.

[0028] This invention relates to a heterogeneous gel-ion-reinforced sealing agent. The heterogeneous gel is immersed in a metal solution for a long time. Under the drive of osmotic pressure, the metal ions in the solution diffuse into the heterogeneous gel network. The metal ions diffused into the gel network can form metal coordination bonds with the COO- groups in the hydrophilic network, thereby forming a second crosslink in the heterogeneous gel network. The mechanical strength of the resulting heterogeneous gel-ion-reinforced sealing agent is further improved. Attached Figure Description

[0029] Figure 1 This is a rheological curve of the heterogeneous gel PDAM-C in Example 1 of the present invention.

[0030] Where G' is the elastic modulus and G" is the viscous modulus;

[0031] Figure 2 Infrared spectra of heterogels containing semi-crystalline hydrophobic side chains and monomers;

[0032] Figure 3 The XRD patterns of the heterogels PDAM-Cn prepared with different molecular weights of PCLn in Examples 1-3 are shown.

[0033] Figure 4 The DSC curve of the heterogeneous gel PDAM-C in Example 1 is shown.

[0034] Figure 5 The infrared spectra of the heterogeneous gel before and after immersion in iron ions in Example 1 are shown.

[0035] Figure 6 SEM images of different gels in Example 1: (a) heterogeneous gel PDAM-C; (b) hydrogel PDAM; (c) Fe 3+ (d) EDS diagram of Fe element in the cross-linked heterogeneous gel PDAM-C-Fe;

[0036] Figure 7 (a) Compressive stress-strain curves; (b) Modulus and toughness of the heterogeneous gel PDAM-C containing PCLn side chains of different molecular weights in Examples 1-3;

[0037] Figure 8 Examples 3-6 show different PCLs 6000 (a) Compressive stress-strain curves of PDAM-C gel with PDAM-C content; (b) Modulus and toughness;

[0038] Figure 9 (a) Compression stress-strain curves before and after iron ion crosslinking in Example 3; (b) Elastic modulus diagrams of gels before and after iron ion crosslinking in Examples 3, 7, and 8;

[0039] Figure 10 This is a graph showing the reversible and stable cyclic changes in Young's modulus of the heterogeneous gel in Example 3;

[0040] Figure 11 This is a graph showing the change in the elastic modulus G' of the heterogel before and after metal coordination crosslinking in Example 3 as a function of temperature.

[0041] Figure 12 This is a schematic diagram and photograph of the orthogonal shape memory process of the heterogeneous gel PDAM-C-Fe in Example 3;

[0042] Figure 13 This is a shape memory cycling diagram of the heterogeneous gel PDAM-C-Fe from Example 3;

[0043] Figure 14 This is a graph showing the thermally induced shape memory expansion characteristics of the heterogeneous gel PDAM-C-Fe in Example 3.

[0044] Figure 15 (a) Schematic diagram of crack sealing using heterogeneous gel PDAM-C-Fe in Example 3; (b) Visualized diagram of the sealing process. Detailed Implementation

[0045] The embodiments of the present invention will be described in detail below with reference to the examples. However, those skilled in the art will understand that the following examples are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Specific conditions not specified in the examples shall be carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0046] The technical solution of the specific embodiments of the present invention is as follows:

[0047] In a first aspect, specific embodiments of the present invention provide a method for preparing a heterogeneous gel plugging agent, comprising the following steps:

[0048] An intermediate was prepared by ring-opening polymerization of ε-caprolactone as a raw material under the action of an initiator and a catalyst; wherein the ring-opening polymerization temperature was 110-120℃ and the time was 12-18h.

[0049] An acid-binding agent was added to the intermediate, and after complete dissolution, an acryloyl chloride monomer was added dropwise. After the reaction, a monomer containing a semi-crystalline hydrophobic side chain was obtained; wherein the acid-binding agent was triethylamine.

[0050] The monomer containing semi-crystalline hydrophobic side chain is heated with hydrophilic monomer, unsaturated carboxylic acid monomer and toughening monomer to 65-75℃, stirred evenly, and then polymerized under ultraviolet light for 1-2 hours to obtain heterogeneous gel plugging agent.

[0051] The molar ratio of the monomer containing the semi-crystalline hydrophobic side chain to the total monomer is 0.5-2.5:100; the molar ratio of the toughening monomer to the total monomer is 15-35:100.

[0052] More preferably, the molar ratio of the monomer containing the semi-crystalline hydrophobic side chain to the total monomer is 0.5-2.0:100; more preferably, the molar ratio of the monomer containing the semi-crystalline hydrophobic side chain to the total monomer is 0.5-1.5:100; and more preferably, the molar ratio of the monomer containing the semi-crystalline hydrophobic side chain to the total monomer is 1.25:100.

[0053] Furthermore, the molecular weight of the above-mentioned ε-caprolactone is ≥2000; more preferably, the molecular weight of ε-caprolactone is 2000-6000.

[0054] Furthermore, the initiator mentioned above is an alcohol compound, a carboxylic acid compound, or water.

[0055] More preferably, the above-mentioned alcohol compounds include one or more of ethanol, ethylene glycol, methanol, butanol, glycerol, cetyl alcohol, and benzyl alcohol;

[0056] Carboxylic acid compounds include one or more of oxalic acid, glycolic acid, malic acid, and citric acid.

[0057] Furthermore, the catalyst includes alkali metal catalysts, rare earth catalysts, enzyme catalysts, or cationic catalysts;

[0058] Furthermore, the above-mentioned rare earth catalysts include one or more of the following: methyltin trichloride, tin tetrachloride, tin dichloride, dimethyltin dichloride, phenyltin trichloride, diphenyltin dichloride, trimethyltin chloride, stannous octoate, dibutyltin dichloride, diphenyltin oxide, butyltin trichloride, tributyltin oxide, trimethyltin, tetraphenyltin, tri-n-butyltin azide, hexa-n-butyltin, bis(dibutyltin chloride(IV)) oxide, hexamethylditin, hexaphenylditin, tributyltin hydride, tributylvinyltin, trimethyltin bromide, tetraethyltin, triethyltin bromide, tributyltin iodide, and (dimethylamine)trimethyltin(IV);

[0059] Furthermore, the aforementioned cationic catalyst includes one or more of methyl fluorosulfonic acid, methyl nitrobenzenesulfonic acid, and methyl methyl sulfonate.

[0060] Preferably, the catalyst is selected from Sn(Oct)2, aluminum triisopropoxide, zinc-based catalysts, and magnesium-based catalysts.

[0061] Furthermore, the unsaturated carboxylic acid monomer includes acrylic acid or methacrylic acid; acrylic acid is preferred.

[0062] Furthermore, the hydrophilic monomer is N,N-dimethylacrylamide, N-isopropylacrylamide, N-ethylacrylamide, N,N-dimethylmethylacrylamide, N,N-diethylmethylacrylamide or N,N′-(1,2-dihydroxyethylene)diacrylamide.

[0063] Furthermore, the toughening monomers include 2-methoxyethyl acrylate, glycidyl methacrylate, or 2-hydroxyethyl acrylate.

[0064] Secondly, specific embodiments of the present invention provide a heterogeneous gel plugging agent, which is mainly a plugging agent prepared by the above-mentioned preparation method.

[0065] Thirdly, in a specific embodiment of the present invention, a heterogeneous gel-ion-enhanced plugging agent is provided, wherein the plugging agent prepared by the above preparation method is immersed in a metal ion solution; the molar mass ratio of the metal ion solution to the unsaturated carboxylic acid monomer is 3:(1-3).

[0066] Furthermore, the aforementioned metal ion solution is selected from iron ion solution, zinc ion solution, copper ion solution, and rare earth ion solution.

[0067] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0068] Example 1 (PDAM-C) 1.25-4000 )

[0069] This embodiment provides a method for preparing a heterogeneous gel plugging agent, including the following steps:

[0070] Step 1: Preparation of PCL-OH (Mn = 4000) intermediate by ring-opening polymerization of ε-caprolactone. Benzyl alcohol was selected as the initiator and Sn(Oct)₂ as the catalyst. Figure 1 As shown. Specific synthesis steps: Benzyl alcohol (2.106 g, 0.0195 mol), ε-caprolactone (80 g, 0.351 mol), and Sn(Oct)₂ (0.24 g) were added to a 150 mL Schlenk flask and magnetically stirred for 10 min at room temperature until homogeneous. After three cycles of freezing-vacuuming-dissolution, the Schlenk flask was placed in a 120°C oil bath for 15 h. After the reaction was completed and cooled to room temperature, a white solid was obtained. This white solid was then dissolved with a small amount of CH₂Cl₂. After complete dissolution, it was added to excess ice-cold ethanol to precipitate three times. The mixture was filtered, and the filter cake was then vacuum-dried at 35°C for 48 h to obtain a white solid, PCL. 4000 -OH, yield 90%.

[0071]

[0072] Figure 1 Reaction equation for the synthesis of intermediate PCL-OH

[0073] Step 2: Preparation of monomers containing semi-crystalline hydrophobic side chains, such as... Figure 2 As shown; the specific synthesis steps are as follows: In a 250mL three-necked flask, add the intermediate PCL... 4000 -OH (16 g, 3.9 mmol) and triethylamine (3.151 g, 31.2 mmol) were dissolved in 100 mL of CH₂Cl₂. After complete dissolution, the three-necked flask was placed in an ice-water bath. Then, methacryloyl chloride (4.075 g, 39 mmol) was slowly added dropwise. After the addition was complete, the reaction was allowed to proceed at room temperature for 24 h. After the reaction was complete, excess CH₂Cl₂ was removed by rotary evaporation to obtain a viscous liquid. A small amount of CH₂Cl₂ was added to the viscous liquid to dissolve it, and then the liquid was precipitated three times with excess ice-cold ethanol. The precipitate was filtered to obtain a pale yellow solid. After vacuum drying at 35 °C for 48 h, the final product PCL was obtained. 4000 -MA, yield 73%.

[0074]

[0075] Figure 2 Reaction equation for poly(ε-caprolactone) methyl acrylate (PCLn-MA)

[0076] Step 3: Preparation of heterogeneous gel sealing agent. The PCL monomer containing semi-crystalline hydrophobic side chains obtained in Step 2 is used... 4000 -MA was mixed with hydrophilic monomers DMA (N,N-dimethylacrylamide) and AAc (acrylic acid), and toughening monomer MEA (2-methoxyethyl acrylate), with a total monomer content of 100g. The mixture was heated at 65℃ and stirred until homogeneous to obtain a transparent liquid. This liquid was then photoinitiated under ultraviolet light for 1 hour to obtain the heterogeneous gel plugging agent PDAM-C. -4000 (The semi-crystalline hydrophobic side chain monomer has a mass content of 52.6%, the hydrophilic monomer DMA has a mass content of 15.8%, the AAc mass content is 10.5%, and the toughening monomer MEA mass content is 21.1%).

[0077] This embodiment provides a heterogeneous gel-ion-reinforced plugging agent.

[0078] The heterogeneous gel sealing agent prepared above was immersed in ferric chloride solution to obtain the heterogeneous gel-ion-reinforced sealing agent PDAM-C. 4000 -Fe.

[0079] (where the iron ion solution concentration is 1 mol L) -1Add 10 parts of metal ion solution to each part of heterogeneous gel.

[0080] Example 2 (PDAM-C) 1.25-2000 )

[0081] This embodiment provides a method for preparing a heterogeneous gel plugging agent, including the following steps:

[0082] Step 1: Preparation of PCL-OH (Mn = 2000) intermediate by ring-opening polymerization of ε-caprolactone. Benzyl alcohol was selected as the initiator and Sn(Oct)₂ as the catalyst. Specific synthesis steps: Benzyl alcohol (4.212 g, 0.039 mol), ε-caprolactone (80 g, 0.351 mol), and Sn(Oct)₂ (0.24 g) were added to a 150 mL Schlenk flask and magnetically stirred for 10 min at room temperature until homogeneous. After three cycles of freezing-vacuuming-dissolution, the Schlenk flask was placed in a 120℃ oil bath for 14 h. After the reaction was completed and cooled to room temperature, a white solid was obtained. The white solid was then dissolved with a small amount of CH₂Cl₂. After complete dissolution, it was added to excess ice-cold ethanol to precipitate three times. The mixture was filtered, and the filter cake was vacuum dried at 35℃ for 48 h to obtain a white solid with a yield of 82%.

[0083] Step 2: Preparation of monomers containing semi-crystalline hydrophobic side chains; the specific synthesis steps are as follows: In a 250mL three-necked flask, add intermediate PCL... 2000 -OH (8 g, 3.9 mmol) and triethylamine (3.151 g, 31.2 mmol) were dissolved in 100 mL of CH₂Cl₂. After complete dissolution, the three-necked flask was placed in an ice-water bath. Then, methacryloyl chloride (4.075 g, 39 mmol) was slowly added dropwise. After the addition was complete, the reaction was allowed to proceed at room temperature for 24 h. After the reaction was complete, excess CH₂Cl₂ was removed by rotary evaporation to obtain a viscous liquid. A small amount of CH₂Cl₂ was added to the viscous liquid to dissolve it, and then the liquid was precipitated three times with excess ice-cold ethanol. The precipitate was filtered to obtain a pale yellow solid. After vacuum drying at 35 °C for 48 h, the final product PCL was obtained. 2000 -MA, yield 73%.

[0084] Step 3: Preparation of heterogeneous gel plugging agent. Hydrophilic monomers DMA and AAc, as well as toughening monomer MEA (ethanolamine), were added to the prepared poly(ε-caprolactone) methyl acrylate. The total amount of these monomers was 100g. The solution was heated at 75℃ and stirred until homogeneous to obtain a transparent liquid. Then, it was irradiated under ultraviolet light for photo-initiated polymerization for 1.2 hours to obtain the heterogeneous gel plugging agent PDAM-C. -2000(The semi-crystalline hydrophobic side chain monomer has a mass content of 35.7%, the hydrophilic monomer DMA has a mass content of 21.4%, the AAc mass content is 14.3%, and the toughening monomer MEA mass content is 28.6%).

[0085] This embodiment provides a heterogeneous gel-ion-reinforced plugging agent.

[0086] The heterogeneous gel plugging agent prepared above was immersed in ferric chloride solution to obtain heterogeneous gel-ion-enhanced plugging agent PDAM-C-Fe.

[0087] Example 3 (PDAM-C) 1.25-6000 )

[0088] This embodiment provides a method for preparing a heterogeneous gel plugging agent, including the following steps:

[0089] Step 1: Preparation of PCL-OH (Mn = 6000) intermediate by ring-opening polymerization of ε-caprolactone. Benzyl alcohol was selected as the initiator and Sn(Oct)₂ as the catalyst. Specific synthesis steps: Benzyl alcohol (1.053 g), ε-caprolactone (80 g, 0.351 mol), and Sn(Oct)₂ (0.24 g) were added to a 150 mL Schlenk flask and magnetically stirred for 10 min at room temperature until homogeneous. After three cycles of freezing-vacuuming-dissolution, the Schlenk flask was placed in a 110℃ oil bath for 12 h. After the reaction was completed and cooled to room temperature, a white solid was obtained. The white solid was then dissolved with a small amount of CH₂Cl₂. After complete dissolution, it was added to excess ice-cold ethanol to precipitate three times. The mixture was filtered, and the filter cake was vacuum dried at 35℃ for 48 h to obtain a white solid with a yield of 86%.

[0090] Step 2: Preparation of monomers containing semi-crystalline hydrophobic side chains; the specific synthesis steps are as follows: In a 250mL three-necked flask, add intermediate PCL... 6000 -OH (24 g, 3.9 mmol) and triethylamine (3.151 g, 31.2 mmol) were dissolved in 100 mL of CH₂Cl₂. After complete dissolution, the three-necked flask was placed in an ice-water bath. Then, methacryloyl chloride (4.075 g, 39 mmol) was slowly added dropwise. After the addition was complete, the reaction was allowed to proceed at room temperature for 24 h. After the reaction was complete, excess CH₂Cl₂ was removed by rotary evaporation to obtain a viscous liquid. A small amount of CH₂Cl₂ was added to the viscous liquid to dissolve it, and then the liquid was precipitated three times with excess ice-cold ethanol. The precipitate was filtered to obtain a pale yellow solid. After vacuum drying at 35 °C for 48 h, the final product PCL was obtained. 6000 -MA, yield 73%.

[0091] Step 3: Preparation of heterogeneous gel plugging agent. Hydrophilic monomers DMA and AAc, as well as toughening monomer MEA (ethanolamine), are added to poly(ε-caprolactone) methyl acrylate. The total amount of these monomers is 100g. After heating and stirring at 68℃ until homogeneous, a transparent liquid is obtained. Then, it is irradiated under ultraviolet light for photo-initiated polymerization for 1 hour to obtain the heterogeneous gel plugging agent PDAM-C. -6000 (The semi-crystalline hydrophobic side-chain monomer has a mass content of 62.5%, the hydrophilic monomer DMA has a mass content of 12.5%, the AAc mass content is 8.3%, and the toughening monomer MEA mass content is 16.7%).

[0092] This embodiment provides a heterogeneous gel-ion-reinforced plugging agent.

[0093] The heterogeneous gel plugging agent prepared above was immersed in ferric chloride solution to obtain heterogeneous gel-ion-enhanced plugging agent PDAM-C-Fe.

[0094] Example 4: (PDAM-C) 0.5-6000 )

[0095] This embodiment provides a method for preparing a heterogeneous gel plugging agent, including the following steps:

[0096] Step 1, the ring-opening polymerization of ε-caprolactone to prepare PCL-OH, and step 2, the preparation of monomers containing semi-crystalline hydrophobic side chains, are the same as in Example 3:

[0097] Step 3: Preparation of heterogeneous gel plugging agent, using the semi-crystalline hydrophobic side-chain monomer PCL obtained in Step 2. 6000 The heterogeneous gel plugging agent PDAM-C was obtained by photo-initiated polymerization under ultraviolet light after irradiation for 1 hour, consisting of 40% MA, 20% hydrophilic monomer DMA, 13.3% AAc, and 26.7% toughening monomer MEA. -6000 .

[0098] This embodiment provides a heterogeneous gel-ion-reinforced plugging agent.

[0099] The heterogeneous gel plugging agent prepared above was immersed in ferric chloride solution to obtain heterogeneous gel-ion-enhanced plugging agent PDAM-C-Fe.

[0100] Example 5: (PDAM-C) 2.5-6000 )

[0101] This embodiment provides a method for preparing a heterogeneous gel plugging agent, including the following steps:

[0102] Step 1, the ring-opening polymerization of ε-caprolactone to prepare PCL-OH, and step 2, the preparation of monomers containing semi-crystalline hydrophobic side chains, are the same as in Example 3:

[0103] Step 3: Preparation of heterogeneous gel plugging agent, using the semi-crystalline hydrophobic side-chain monomer PCL obtained in Step 2. 6000 The product contains 76.9% MA, 7.7% hydrophilic monomer DMA, 5.1% AAc, and 10.3% toughening monomer MEA. After photo-initiated polymerization under ultraviolet light for 1 hour, a heterogeneous gel plugging agent, PDAM-C, is obtained. -6000 .

[0104] This embodiment provides a heterogeneous gel-ion-reinforced plugging agent.

[0105] The heterogeneous gel plugging agent prepared above was immersed in ferric chloride solution to obtain heterogeneous gel-ion-enhanced plugging agent PDAM-C-Fe.

[0106] Example 6: (PDAM-C) 3.75-6000 )

[0107] This embodiment provides a method for preparing a heterogeneous gel plugging agent, including the following steps:

[0108] Step 1, the ring-opening polymerization of ε-caprolactone to prepare PCL-OH, and step 2, the preparation of monomers containing semi-crystalline hydrophobic side chains, are the same as in Example 3:

[0109] Step 3: Preparation of heterogeneous gel plugging agent, semi-crystalline hydrophobic side chain monomer PCL 6000 The product contains 83.3% MA, 5.6% DMA, 3.7% AAc, and 7.4% MEA (toughening monomer). After photo-initiated polymerization under UV light for 1 hour, a heterogeneous gel plugging agent, PDAM-C, is obtained. -6000 .

[0110] This embodiment provides a heterogeneous gel-ion-reinforced plugging agent.

[0111] The heterogeneous gel plugging agent prepared above was immersed in ferric chloride solution to obtain heterogeneous gel-ion-enhanced plugging agent PDAM-C-Fe.

[0112] Example 7:

[0113] This embodiment provides a method for preparing a heterogeneous gel plugging agent, including the following steps:

[0114] Step 1, the ring-opening polymerization of ε-caprolactone to prepare PCL-OH, and step 2, the preparation of monomers containing semi-crystalline hydrophobic side chains, are the same as in Example 3:

[0115] Step 3: Preparation of heterogeneous gel plugging agent. Hydrophilic monomers DMA and AAc, as well as toughening monomer MEA (ethanolamine), were added to the prepared poly(ε-caprolactone) methyl acrylate. The monomer solution was heated at 68°C and stirred until homogeneous to obtain a transparent liquid (semi-crystalline hydrophobic side-chain monomer content 62.5%, hydrophilic monomer DMA content 4.1%, AAc content 16.7%, and toughening monomer MEA content 16.7%). Then, it was irradiated under ultraviolet light, and photo-initiated polymerization was carried out for 1 hour to obtain the heterogeneous gel plugging agent PDAM-C. -6000 .

[0116] This embodiment provides a heterogeneous gel-ion-reinforced plugging agent.

[0117] The heterogeneous gel plugging agent prepared above was immersed in ferric chloride solution to obtain heterogeneous gel-ion-enhanced plugging agent PDAM-C-Fe.

[0118] Example 8

[0119] An example provides a method for preparing a heterogeneous gel plugging agent, comprising the following steps:

[0120] Step 1, the ring-opening polymerization of ε-caprolactone to prepare PCL-OH, and step 2, the preparation of monomers containing semi-crystalline hydrophobic side chains, are the same as in Example 3:

[0121] Step 3: Preparation of heterogeneous gel plugging agent. Hydrophilic monomers DMA and AAc, as well as toughening monomer MEA (ethanolamine), were added to the prepared poly(ε-caprolactone) methyl acrylate. The monomer solution was heated at 68°C and stirred until homogeneous to obtain a transparent liquid (semi-crystalline hydrophobic side-chain monomer content: 62.5%, hydrophilic monomer DMA content: 8.3%, AAc content: 12.5%, toughening monomer MEA content: 16.7%). Then, it was irradiated under ultraviolet light, and photo-initiated polymerization was carried out for 1 hour to obtain the heterogeneous gel plugging agent PDAM-C. -6000 .

[0122] This embodiment provides a heterogeneous gel-ion-reinforced plugging agent.

[0123] The heterogeneous gel plugging agent prepared above was immersed in ferric chloride solution to obtain heterogeneous gel-ion-enhanced plugging agent PDAM-C-Fe.

[0124] To demonstrate the excellent mechanical properties, temperature response, and shape memory effect of the heterogeneous gel and heterogeneous gel-ion-reinforced sealing agent provided in this application, the following experiments were conducted:

[0125] Experimental Example 1: Chemical Characterization and Microstructure Determination of Heterogeneous Gels Containing Semi-crystalline Hydrophobic Side Chains Rheological properties of the heterogeneous gel PDAM-C in Example 1:

[0126] The rheological properties of the samples were measured using a HAAKE MARSⅢ rheometer. A PL60 Ti L flat rotor (60 mm in diameter, 1 mm cross-sectional spacing) was used. After adjusting the rheometer parameters, the samples were placed on the sample stage for testing. Frequency scan: fixed strain of 0.1%; strain scan: fixed frequency of 1 Hz.

[0127] from Figure 1 Frequency scanning tests show that G' is always greater than G" throughout the entire frequency scanning range (0.1-100Hz), and neither G' nor G" is frequency-dependent, exhibiting obvious gel properties.

[0128] The infrared spectrum of heterogeneous gel PDAM-C in Example 1 was determined. Figure 2 ):

[0129] The samples were tested using an FTIR Nicolet 6700 spectrometer. A small amount of freeze-dried PDAM-C solid sample was ground and mixed with potassium bromide, then compressed into a pellet. The test resolution was 4 cm⁻¹. -1 The number of scans was 200, and the wavenumber scan range was 500–4000 cm⁻¹. -1

[0130] At 3346cm -1 The broad peak is the NH stretching vibration peak on the DMA molecule, at 2937 cm⁻¹. -1 Characteristic peaks of stretching vibrations of -CH3 and -CH2-, 1731 cm⁻¹ -1 and 1626cm -1 These are the C=O stretching vibration peaks on the ester and amide groups, respectively, at 1410 cm⁻¹. -1 and 927cm -1 It is the OH bending vibration peak, 1244 cm⁻¹ -1 and 1178cm -1 The peak is the CO stretching vibration peak. The infrared characteristic functional groups of PCLn-MA, DMA and AAc monomers are all present in the infrared spectrum of the dry heterogel, which indicates the successful synthesis of the heterogel.

[0131] The XRD patterns of heterogels PDAM-Cn prepared from PCLn (poly(ε-caprolactone)) of different molecular weights in Examples 1-3 were determined, and the results are as follows: Figure 3 As shown.

[0132] The prepared gel sample was spread or placed in a groove on a glass slide and tested at room temperature using an XPert PRO MPD X-ray diffractometer. The test conditions were as follows: a copper target was used as the radiation source, and the incident wavelength was... The scanning angle range was 2θ = 5-70°; the step size was 0.02°; and the scanning speed was 0.2 s / step. Data analysis was performed using MDI Jade6 software after the test.

[0133] From PDA-C 2000 The XRD pattern shows that the heterogel exhibits distinct diffraction peaks at 2θ = 21.5° and 23.8°, which correspond to the positions of the 110 and 200 crystal planes of PCL, respectively. This result confirms that rigid, semi-crystalline PCLn domains are uniformly dispersed within the hydrophilic framework. Similarly, PDAM-C 4000 and PDAM-C 6000 Obvious diffraction peaks were also observed at 2θ = 21.5° and 23.8°, and the intensity of these peaks increased significantly with the increase of PCLn molecular weight, indicating that the higher the molecular weight of PCLn, the higher the crystallinity.

[0134] Thermal behavior of heterogeneous gel PDAM-C in Example 1 was determined by DSC. Figure 4 ).

[0135] 5-10 mg of dried sample was taken, and the thermal behavior of the gel was tested and analyzed using a Mettler-Toledo DSC823e (Different scanning calorimetry, abbreviated as DSC). Test conditions: The temperature was increased from 5℃ to 90℃ at a heating rate of 5℃ / min and a nitrogen flow rate of 100 mL / min.

[0136] The thermal analysis curves of the heterogel show a sharp endothermic peak at 58.8℃. As the temperature gradually decreases from 90℃, a maximum exothermic peak appears at 30.6℃. This cyclic thermal analysis confirms that the semi-crystalline region of PCLn undergoes a reversible melting-crystallization transformation with temperature changes, with melting and crystallization temperatures of 58.8℃ and 30.6℃, respectively. The semi-crystalline region in the heterogel PDAM-C network melts at high temperatures and recrystallizes at low temperatures, exhibiting good thermal reversibility.

[0137] Subsequently, the heterogeneous gel PDAM-C from Example 1 was immersed in an iron solution for an extended period of time, and under osmotic pressure-driven Fe... 3+ The solution diffuses into the heterogeneous gel network, and Fe diffuses into the gel network. 3+ Able to work with the COO in the hydrophilic network - The groups form metal coordination bonds, thereby forming a second crosslink in the heterogeneous gel network. In the infrared spectrum of the heterogeneous gel PDAM-C-Fe ( Figure 5 Due to metal coordination interactions, 1731 cm⁻¹ is attributed to the carboxyl group. -1and 1626cm -1 The characteristic absorption peaks were red-shifted to 1724 cm⁻¹. -1 1621cm -1 This proves that metallic coordination bonds were indeed formed.

[0138] The microstructures of different gels were characterized using SEM, including the single-phase hydrogel PDAM (poly(ε-caprolactone) methyl acrylate, hydrophilic monomers DMA, AAc, and toughening monomer MEA), the heterogeneous gel PDAM-C, and the iron-impregnated heterogeneous gel PDAM-C-Fe. All three gels exhibited porous characteristics. Figure 6 It is known that the network pore size of heterogeneous gel PDAM-C containing hydrophobic side chains is approximately 7 μm, while the pore size of the single-phase hydrogel PDAM network backbone is 50-200 μm, almost tens of times that of heterogeneous gel PDAM-C. This indicates that the polymer network density in heterogeneous gel PDAM-C is significantly higher than that in hydrogel PDAM, which is largely related to the water content of the gel. It also indirectly confirms that the PCLn side chains hinder water molecules from entering the network pores, resulting in a higher polymer concentration and smaller network pore size. When the heterogeneous gel PDAM-C gel is in Fe... 3+ After immersion in the solution, the cross-linking density of the polymer network further increases, thus reducing the pore size of the heterogel PDAM-C-Fe to 1-10 μm. EDS analysis shows that iron ions are uniformly distributed within the heterogel PDAM-C-Fe network.

[0139] Experimental Example 2: Mechanical Behavior of Heterogeneous Gels Containing Semi-crystalline Hydrophobic Side Chains

[0140] The rigid, semi-crystalline PCLn side chains have a significant impact on the mechanical properties of gel PDAM-C. Figure 7The compressive mechanical properties of the heterogel PDAM-C containing PCLn side chains of different molecular weights in Examples 1-3 were demonstrated. All gels exhibited good elasticity throughout the compression range without significant mechanical failure. However, compared to the hydrogel (the gel state in Example 1 without the addition of semi-crystalline hydrophobic side chain monomers), the introduction of rigid semi-crystalline hydrophobic side chains significantly increased the compressive stress at ε=70%, regardless of the molecular weight of PCLn. Specifically, at ε=70%, the compressive stress of the pure hydrogel was 0.24 MPa, while the compressive stresses at ε=70% for PCLn molecular weights of 2000, 4000, and 6000 were 2.9 MPa, 4.4 MPa, and 17.6 MPa, respectively. The Young's modulus and toughness of the heterogel PDAM-C showed a monotonically increasing trend with increasing PCLn molecular weight. This is because, with increasing molecular weight, the higher the crystallinity of the semi-crystalline hydrophobic side chains of PCLn, the higher the strength of the material. The PCLn exhibits optimal mechanical properties when its molecular weight is 6000, with a compressive Young's modulus of 2780.2 kPa and a toughness of 2759.8 kJ / m². -3 .

[0141] Depend on Figure 8 The compressive stress-strain curve of a shows that, compared with soft hydrogels, the mechanical properties of PDAM-C gels can be further improved by increasing the content of rigid semi-crystalline PCLn. Figure 8 As can be seen from b, in Example 4, only 0.5 wt% of PCL was introduced. 6000 The mechanical properties of the resulting heterogel can be significantly improved; its compressive stress at ε=70% is 15 times that of the hydrogel. With increasing PCLn content, the Young's modulus, representing the strength of the heterogel, continuously increases. 6000 When the content is 3.75 wt% (Example 6), PDAM-C 3.75-6000 The Young's modulus of PCLn is nearly 20,000 kPa, which is almost comparable to that of human cartilage. However, with the continuous increase of PCLn content, the toughness of the heterogel PDMA-C shows a trend of first increasing and then decreasing. When PCLn content increases, the toughness of the heterogel PDMA-C decreases. 6000 At a content of 1.25 wt%, the Young's modulus and toughness of the heterogel were 1633.7 kPa and 2455.9 kJ / m, respectively. -3 This represents an improvement of 96 times and 103 times compared to hydrogels, respectively. If the content of the semi-crystalline side chain PCLn is further increased, the high content of rigid hydrophobic groups leads to a decrease in the elasticity of the heterogel, resulting in higher rigidity. Therefore, when ε is 25% and 20%, respectively, the heterogel PDMA-C exhibits... 2.5-6000and PDMA-C 3.75-6000 Mechanical damage occurred in all cases, leading to a decrease in mechanical properties. Based on the above analysis, the optimal content of the semi-crystalline hydrophobic side chain PCLn is 1.25 wt%.

[0142] The strength of the iron-crosslinked heterogel PDAM-C-Fe is significantly improved compared to the mechanical properties of the uncrosslinked heterogel PDAM-C. For example... Figure 9 a, PDAM-C -6000 The compressive stress at ε = 70% is 18.9 MPa, while the cross-linked PDAM-C -6000 The compressive stress of Fe is 46.9 MPa.

[0143] The Young's modulus of the heterogel before crosslinking was calculated to be 2.78 MPa using the linear region (ε = 0-15%). However, after immersion in an iron ion solution, the Young's modulus of the heterogel increased to 24.3 MPa due to metal coordination, which is 8 times higher than before.

[0144] Depend on Figure 9 b indicates that Fe 3+ The AAc content coordinates with carboxyl groups on the gel network, thus significantly affecting the mechanical properties of the heterogeneous gel. Examples 3, 7, and 8 show mechanical strength tests before and after different AAc contents and iron ion coordination. Heterogeneous gels with different AAc contents, without being immersed in an iron ion solution, exhibited... Figure 9 In step b, as the AAc content (the percentage of AAc in the total AAc and DMA) increases, the Young's modulus of the heterogel increases from 0.28 MPa to 1.05 MPa. When immersed in an iron ion solution, the strength of the heterogel is significantly improved compared to that without iron ion immersion, increasing by several tens of times. Furthermore, the mechanical strength of the iron-crosslinked heterogel increases proportionally with increasing AAc content. This is because increasing the AAc content leads to the formation of more high-strength metal coordination bonds in the gel network.

[0145] The metal coordination bonds formed between carboxylic acid groups and iron ions can be reversibly broken under the action of EDTA, reducing agents, or ascorbic acid, resulting in a significant decrease in the Young's modulus of the heterogeneous gel. Cyclic testing of the heterogeneous gel in Example 3 showed that… Figure 10 The Young's modulus of the iron-crosslinked heterogel PDAM-C-Fe is approximately 25 MPa. When immersed in an EDTA solution, the stronger complexation ability of EDTA with iron ions leads to competition with the carboxylic acid groups for Fe. 3+This disrupts the coordination interactions within the original gel network, reducing the Young's modulus of the heterogel to 2.6 MPa. When the heterogel is re-immersed in an iron ion solution, its strength rebounds to approximately 25 MPa, only to decrease again upon immersion in an EDTA solution. This cycle repeats multiple times, demonstrating a reversible decrease and increase in the strength of the heterogel due to the reversible removal and introduction of metal coordination interactions within the heterogel network, exhibiting a stable strength variation.

[0146] Experimental Example 3: Temperature Response Behavior of Heterogeneous Gels Containing Semi-crystalline Hydrophobic Side Chains

[0147] The unique crystallization property of hydrophobic side-chain PCLn is reversible; as the temperature rises, the crystals melt and the hydrophobic side chains become soft, but as the temperature decreases, they can reform into a high-strength semi-crystalline form. The DSC curves of the heterogel indicate that the phase transition temperature T of the hydrophobic side-chain PCL6000 is... m It was 58.8℃. From Figure 11 It can be seen that, regardless of whether it is the pre-crosslinked heterogel PDAM-C or the post-crosslinked heterogel PDAM-C-Fe, when the temperature is below the PCLn phase transition temperature, the elastic modulus G' of the heterogel does not change significantly with increasing temperature. However, when the temperature is above T... m At near-crosslinking temperatures, the G' of the heterogel decreases sharply because the rigid side chains of the semi-crystalline gel become soft, and the rigid crystalline domains are gradually destroyed. As the temperature rises further, the G' of the heterogel decreases slowly. This thermal softening property allows the gel to maintain good plasticity after heating. Furthermore, by comparing the elastic modulus of the heterogels before and after crosslinking, the elastic modulus G' of the metal-coordinated crosslinked heterogel PDAM-C-Fe is consistently about one order of magnitude higher than that of the heterogel PDAM-C. Therefore, the metal-coordinated crosslinked heterogel PDAM-C-Fe exhibits superior mechanical properties at high temperatures.

[0148] The thermal softening properties of heterogeneous gels are dominated by the reversible heating-melting-cooling-crystallization process of hydrophobic side chains in the gel network. Therefore, temperature cycling experiments show that as the temperature decreases, the heterogeneous gel that initially softened at high temperatures recovers its G' value due to recrystallization of the hydrophobic side chains. In multiple cycles, the G' of the PDMA-C-Fe heterogeneous gel exhibits a trend of decreasing at high temperatures and increasing at low temperatures, and the G' remains relatively stable at both room temperature and high temperature during multiple temperature cycles.

[0149] Experiment Example 4: Shape memory behavior of heterogels containing semi-crystalline hydrophobic side chains

[0150] In heterogel networks, the elastic hydrophilic network serves as a permanent network, while the hydrophobic side chains with reversible crystallization properties act as molecular switches within the gel network. This combination endows heterogels with excellent shape memory properties. The orthogonal shape memory process of the heterogel PDAM-C-Fe is as follows: Figure 12 As shown, when the temperature rises, the ordered, comb-like rigid semi-crystalline side chains gradually transform into disordered, flexible alkyl chains, making the heterogel easily deformable at high temperatures and allowing it to be pressed into sheet-like shapes. After maintaining external force and lowering the ambient temperature to room temperature, the sheet-like shape is fixed. At this point, if this sheet-like heterogel is placed at T... m In the above environment, it can return to its original cylindrical shape after a period of time. However, if the sheet-like heterogel is soaked in an iron ion solution, this temporary sheet shape will be locked into a new permanent shape, and heating the heterogel at this time will not restore it to its original cylindrical shape.

[0151] Subsequently, the shape memory properties of the heterogeneous gel were quantitatively investigated using a dynamic thermomechanical analyzer. Test method: The tensile mode of the dynamic thermomechanical analyzer (DMA TA Q800) was used to examine the change trend of G' at different temperatures. The sample preparation method was the same as that for the tensile test. First, the gel sample was cut into a strip with a length of 20 mm, a width of 8 mm, and a thickness of 0.8 mm, and then fixed with a suitable clamp. The tensile frequency in the test was 1 Hz, the preload was 0.01 N, the amplitude was 5 μm, and the heating rate was 5 °C min⁻¹. Temperature scanning tests were performed on the dynamic mechanical properties (storage modulus, loss modulus) of the gel within a certain temperature range.

[0152] from Figure 13 It can be seen that when the material is heated to 80℃, a constant stress (0.06MPa) is maintained after thermal equilibrium to stretch the heterogeneous gel. When the deformation ε = 50%, the stretching is stopped and this constant stress is maintained. The temperature is slowly reduced to 5℃ so that the sample is fixed at 50% deformation. Then the external force is removed and the temperature is raised to 80℃. After heating for 10 minutes, the deformation of the heterogeneous gel sample is almost completely recovered.

[0153] Experiment Example 5: Simulated Adaptive Deformation Blocking

[0154] In addition to the complex shape memory described above, this high-strength shape memory heterogel PDAM-C-Fe also exhibits thermally induced shape memory expansion properties. For example... Figure 14As shown, a block-shaped gel is compressed into a sheet shape by heating and external force, and this shape is fixed after cooling. When the temperature is raised, the sheet-shaped heterogeneous gel returns to its original block shape. The height of the heterogeneous gel expands from 1.4 mm after compression to 5.4 mm, which means that the heterogeneous gel expands about 4 times along the compression axis after heating, which is larger than the deformation of most shape memory bulk polymers.

[0155] The principle of adaptive plugging of fractured formations is as follows: Figure 15 As shown in Figure a, a heterogeneous gel PDAM-C-Fe, initially in a blocky shape, is heated, compressed, and cooled to prepare a sheet-like material. If this sheet is blended with unshaped blocky plugging material and injected into the formation, the blocky material can only enter fractures with an aperture larger than its particle size. If the fracture aperture is smaller than its particle size, it easily leads to "gate sealing," where a dense, pressure-bearing plugging layer does not form inside the fracture. Under the impact of downhole drilling tools, the plugging material accumulated at the gate is destroyed, causing leakage to recur. The sheet material is more adaptable to fracture aperture, easily entering finer fractures. After reaching the activation temperature, the sheet-like heterogeneous gel expands into a near-cubic block shape, adaptively matching fractures of different apertures and rapidly becoming lodged. If this thermotropically expanding heterogeneous gel plugging agent is combined with other types of bridging plugging materials, adaptive, synergistic, and intelligent plugging can be achieved.

[0156] To facilitate observation of the sealing effect, transparent plastic tubes of different shapes were used to simulate and observe the volume-adaptive sealing of the heterogeneous gel material. Figure 15 (b) First, a cylindrical gel is prepared. Then, by heating, part of the gel is compressed into disc-shaped sealing materials, and the rest is stretched into thin cylindrical sealing materials. For circular pipes, both the thin cylindrical and disc-shaped sealing materials can enter the circular pipe. When the temperature rises, both shapes will return to their original cylindrical shape. Since the diameter of the original cylindrical material is larger than the diameter of the transparent pipe, it can completely seal the pipe. However, in flat pipes, only the disc-shaped gel material can enter, while the blocky gel will block the outside of the pipe. When the temperature rises, the disc-shaped material returns to its cylindrical shape. From the side of the pipe, it can be seen that the area where the gel is located shows obvious expansion, completely sealing the flat pipe, and water cannot pass through.

[0157] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a heterogeneous gel sealing agent, characterized in that, Includes the following steps: An intermediate was prepared by ring-opening polymerization of ε-caprolactone as a raw material under the action of an initiator and a catalyst; the initiator was an alcohol compound. An acid-binding agent was added to the intermediate, and after complete dissolution, an acryloyl chloride monomer was added dropwise. After the reaction, a monomer containing a semi-crystalline hydrophobic side chain was obtained. The monomer containing semi-crystalline hydrophobic side chains is heated and stirred evenly with a hydrophilic monomer, an unsaturated carboxylic acid monomer, and a toughening monomer, and then photo-initiated to polymerize, yielding a heterogeneous gel plugging agent; wherein the unsaturated carboxylic acid monomer includes acrylic acid or methacrylic acid; the hydrophilic monomer is N,N-dimethylacrylamide, N-isopropylacrylamide, N-ethylacrylamide, N,N-dimethylmethacrylamide, N,N-diethylmethacrylamide, or N,N′-(1,2-dihydroxyethylene)diacrylamide; and the toughening monomer includes 2-methoxyethyl acrylate, glycidyl methacrylate, or 2-hydroxyethyl acrylate. The molar ratio of the monomer containing the semi-crystalline hydrophobic side chain to the total monomer is 0.5-2.5:100; the molar ratio of the toughening monomer to the total monomer is 15-35:

100.

2. The method for preparing a heterogeneous gel plugging agent according to claim 1, characterized in that, The alcohols include one or more of ethanol, ethylene glycol, methanol, butanol, glycerol, cetyl alcohol, and benzyl alcohol.

3. The method for preparing a heterogeneous gel plugging agent according to claim 1, characterized in that, The catalyst includes alkali metal catalysts, rare earth catalysts, enzyme catalysts, or cationic catalysts.

4. The method for preparing a heterogeneous gel plugging agent according to claim 1, characterized in that, In the step of preparing the intermediate, the ring-opening polymerization is carried out at a temperature of 110-120°C for 12-18 hours.

5. The method for preparing a heterogeneous gel plugging agent according to claim 1, characterized in that, In the step of preparing the heterogeneous gel plugging agent, the heating temperature is 65-75℃; the photo-initiated polymerization is carried out under ultraviolet light for 1-2 hours.

6. A heterogeneous gel sealing agent, characterized in that, It is prepared by any one of the preparation methods described in claims 1-5.

7. A heterogeneous gel-ion-reinforced sealing agent, characterized in that, The sealing agent prepared by any one of the preparation methods of claims 1-5 or the sealing agent of claim 6 is immersed in a metal ion solution; the molar mass ratio of the metal ion solution to the unsaturated carboxylic acid monomer is 3:(1-3).

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