Oil reservoir plugging composition and preparation method and application thereof

Abstract

The present invention discloses a Tibetan oil plugging composition, its preparation method, and its application. The composition comprises nanoparticles and an amphiphilic polymer. The nanoparticles have a core-shell structure, the core of which is a monomer with a hydrophobic rigid group. The surface of the nanoparticles is modified with β-cyclodextrin groups and hydrophilic groups. The nanoparticles have a particle size of 50-700 nm. The amphiphilic polymer has a number-average molecular weight of 1000-4000. This Tibetan oil plugging composition achieves a good balance between injectability and plugging effect in heterogeneous reservoirs, and has an excellent plugging effect.

Description

Technical Field

[0001] The present invention relates to the field of chemical agents for controlling water breakthrough during oil reservoir exploitation, and in particular to an oil reservoir plugging composition and a preparation method and application thereof. Background Art

[0002] As a national strategic resource and the foundation of its industry, demand for petroleum is increasing with rapid economic development. However, most of my country's oilfields are continental deposits with severe reservoir heterogeneity. This leads to significant water channeling during waterflooding and low recovery rates. Water channeling is particularly severe and prevalent in low-permeability reservoirs with fine pore throats, complex structures, and extensive fractures. Therefore, effectively preventing and controlling channeling of injected water and expanding the swept volume are key to efficiently extracting remaining oil and improving crude oil recovery. This is also a pressing need to alleviate my country's increasingly severe imbalance between oil supply and demand and safeguard national oil security.

[0003] Deep reservoir profile control, a key technology for improving production efficiency and enhancing oil recovery, has been widely applied in medium- and high-permeability reservoirs. In practical applications, faced with diverse reservoirs characterized by complex channel types, structures, and sizes and distributions, traditional profile control agents, which select their particle size based on a matching relationship between particle size and pore (fracture) size, have limited applicability and low plugging efficiency. Furthermore, smooth injection of profile control agents deep into the reservoir and effective plugging of these channels once they reach depth are essential for achieving deep reservoir profile control. However, numerous oilfield development cases demonstrate that a significant mismatch between the injectability of profile control agents and their deep plugging capacity leads to suboptimal deep profile control effectiveness, particularly in low-permeability reservoirs. Both laboratory simulations and oilfield production practices confirm that the significant contradiction between the injectability of profile control agents and their ability to plug deep water channeling channels in reservoirs is a technical bottleneck restricting water channeling control in various reservoirs. Resolving this contradiction has become a major focus of water channeling control efforts.

[0004] Patent application CN112694580A discloses a carbon-based nano-profile control agent, its preparation method, and application. Patent application CN 113717704 A discloses a method for preparing an intelligent profile control agent for oil fields. The profile control agents in the above two application documents are both made of an inorganic nano-substrate, which is then modified with hydrophilic and hydrophobic groups. The particles are assembled into particles with a stable particle size and then injected into the oil reservoir. However, the injectability and plugging effects of this type of profile control agent for heterogeneous oil reservoirs are still unsatisfactory. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies of the prior art and thus provide an oil reservoir plugging composition that has both injectability and plugging effect.

[0006] To achieve the above objectives, the present invention employs the following technical solution: a reservoir plugging composition composed of nanoparticles and an amphiphilic polymer. The nanoparticles have a core-shell structure, the core of which is a monomer with hydrophobic rigid groups. The surface of the nanoparticles is modified with β-cyclodextrin groups and hydrophilic groups. The nanoparticles have a particle size of 50-700 nm. The number-average molecular weight of the amphiphilic polymer is 1000-4000. The nanoparticles in the present invention are significantly smaller than the size of water channeling channels, while the amphiphilic polymer has low flow resistance, enabling smooth injection into the channels. The plugging composition of the present application does not select the particle size for plugging based on the traditional relationship between particle size and pore (fracture) size. Instead, it relies on the adaptive size of the particle clusters formed by self-assembly of nanoparticles and amphiphilic polymers to complex pores. Once the plugging solution reaches deep within the water channeling channels, the host-guest interaction between the nanoparticles and amphiphilic polymers assembles into particle clusters that match the channel size, effectively plugging the complex water / gas channeling channels of varying size and structure.

[0007] In the present invention, the rigid group refers to a group with a stable structure and low reactivity. During the polymerization and cross-linking process, the group does not react with other compounds. Common monomers with hydrophobic rigid groups include acrylate monomers, aromatic hydrocarbon monomers, and heteroaromatic hydrocarbon monomers. For example, acrylate monomers can be methyl acrylate, ethyl acrylate, butyl acrylate, and methyl methacrylate. Aromatic hydrocarbons include styrene, divinylbenzene, styrene propene, 4-chlorostyrene, 4-nitrostyrene, and the like. Heteroaromatic hydrocarbon monomers include vinyl pyridine, 1-vinylimidazole, and the like. The surface of the nanoparticles is modified with β-cyclodextrin groups and hydrophilic groups, wherein the source monomer of the β-cyclodextrin group can be acrylamido β-cyclodextrin sodium, allyl-β-cyclodextrin, and the like. The source monomer of the hydrophilic group can be a compound containing hydrophilic groups or hydrophilic chain segments such as carboxylic acid, polyoxyethylene ether, polyethylene glycol, amino group, sulfhydryl group, such as acrylamide, sodium acrylate, and the like.

[0008] The particle size of nanoparticles ranges from 50 to 700 nm. Particles that are too large will not meet the requirements for self-assembly to accommodate different water channel sizes. Particles that are too small will not achieve the grafting rate required for self-assembly with β-cyclodextrin and hydrophilic groups. Nanoparticle size varies with the size of the hydrophobic rigid groups. To achieve larger nanoparticles, crosslinking between hydrophobic rigid groups can be achieved using a suitable crosslinking agent, such as divinylbenzene, 1,2-bis(p-vinylphenyl)ethane, or ethylene glycol dimethacrylate.

[0009] The monomers for amphiphilic polymers can be conventional hydrophilic and lipophilic monomers. Common hydrophilic monomers include compounds containing groups or segments such as carboxylic acid, polyoxyethylene ether, polyethylene glycol, amino, and thiol groups. Common lipophilic monomers include compounds containing groups or segments such as acrylates, aromatic / heteroaromatic hydrocarbons, long-chain alkanes, and polyoxypropylene ethers. The number-average molecular weight of amphiphilic polymers is 1000-4000. Too large a molecular weight results in a high drag coefficient during injection; too small a molecular weight does not meet the requirements for self-assembly.

[0010] As a further improvement of the technical solution, the molar ratio of the hydrophobic rigid group, the hydrophilic group and the β-cyclodextrin group in the nanoparticles is 100:3.0~15:0.005~0.05, and the particle size of the nanoparticles is 50-300nm.

[0011] As a further improvement of the technical solution, the molar ratio of hydrophilic groups to hydrophobic groups in the amphiphilic polymer is 100:2.0-5.0, and the number average molecular weight of the amphiphilic polymer is 3000-4000.

[0012] As a further improvement of the technical solution, in order to balance the reactivity, availability and rigidity of the nanoparticles, the core of the nanoparticles is an aromatic compound monomer, such as one or a mixture of styrene, nitrostyrene, divinylbenzene, 4-chlorostyrene, and 4-nitrostyrene.

[0013] As a further improvement of the technical solution, the mass ratio of the nanoparticles to the amphiphilic compound in the plugging composition is 0.2 to 6:1.

[0014] As a further improvement of the technical solution, the mass ratio of the nanoparticles to the amphiphilic compound in the plugging composition is 0.5 to 4:1.

[0015] As a further improvement of the technical solution, the nanoparticles are prepared by emulsion polymerization using styrene, acrylamide, allyl β-cyclodextrin and N,N'-methylenebisacrylamide as synthetic monomers.

[0016] As a further improvement of the technical solution, the hydrophobic group in the amphiphilic polymer is an alkyl chain, and the main chain of the alkyl chain contains 12-20 Cs.

[0017] As a further improvement of the technical solution, the amphiphilic polymer is prepared by using N-dodecyl acrylamide or N-hexadecyl acrylamide as a hydrophobic monomer and acrylamide as a hydrophilic monomer, and is polymerized by free radical initiation.

[0018] A method for preparing the oil reservoir plugging composition comprises:

[0019] The preparation steps of the amphiphilic polymer are as follows: dissolving a hydrophobic monomer and a hydrophilic monomer in deionized water, and using vitamin C, ferric chloride, and sodium chloroacetate as an atom transfer radical polymerization initiator system, and heating to 50-90°C for reaction;

[0020] The preparation steps of nanoparticles are as follows: dissolving a hydrophilic monomer, N,N'-methylenebisacrylamide, and an emulsifier in deionized water, then adding a compound containing a β-cyclodextrin group and mixing evenly to form an aqueous phase; dissolving an initiator in a hard polymer monomer to form an oil phase, slowly pouring the oil phase into the aqueous phase under stirring conditions, and after emulsification, heating to 60-80°C for reaction to obtain nanoparticles.

[0021] As a further improvement of the technical solution, in the preparation process of the amphiphilic polymer, the mass fraction of the hydrophobic monomer in the aqueous phase is 1% to 3%, the mass fraction of acrylamide in the aqueous phase is 10% to 30%, the mass fraction of vitamin C in the aqueous phase is 0.18% to 0.26%, the mass fraction of ferric chloride in the aqueous phase is 0.012% to 0.02%, the mass fraction of sodium chloroacetate in the aqueous phase is 0.2% to 0.4%, and the polymerization reaction time is 5 to 40 hours; in the preparation step of the nanoparticles, the mass fraction of acrylamide in the aqueous phase is 10% to 30%, the mass fraction of vitamin C in the aqueous phase is 0.18% to 0.26%, the mass fraction of ferric chloride in the aqueous phase is 0.012% to 0.02%, and the mass fraction of sodium chloroacetate in the aqueous phase is 0.2% to 0.4%. The mass fraction of olefin amide in the aqueous phase is 0.5% to 3.0%, the mass fraction of allyl β-cyclodextrin in the aqueous phase is 0.01% to 0.1%, the mass fraction of N,N'-methylenebisacrylamide in the aqueous phase is 0.05% to 0.5%, the mass fraction of sodium fatty alcohol polyoxyethylene ether sulfate in the aqueous phase is 0.01% to 0.1%, the mass fraction of styrene in the aqueous phase is 20% to 30%, and the mass fraction of azobisisobutyronitrile in the aqueous phase is 0.1% to 0.2%.

[0022] One application of the reservoir plugging composition involves dissolving nanoparticles and an amphiphilic polymer in water to form a plugging solution. The nanoparticle concentration in the plugging solution is 500-4000 mg / L, and the amphiphilic polymer concentration is 1000-3000 mg / L. The dissolution and self-assembly temperatures are applicable from room temperature up to 100°C, ensuring that both components do not decompose at the set temperature, thus providing strong adaptability. The self-assembly time is 20-80 hours. The higher the temperature, the shorter the self-assembly time. Depending on the reservoir's geological conditions, the profile control agent can be injected in advance, allowing ample time for subsequent preparations.

[0023] The present invention has outstanding substantial features and significant improvements over the prior art. Specifically, the present invention can self-assemble into particle clusters that match the size of the water channel after entering the water channel, effectively blocking water / gas channel with very complex size and structure, and meeting the requirements of injectability and blocking properties.

[0024] Figures in the specification

[0025] Figure 1 This is the particle size distribution diagram of the nanoparticles prepared in Example 1.

[0026] Figure 2 This is a scanning electron microscope image of the nanoparticles prepared in Example 1.

[0027] Figure 3 This is a transmission electron microscope image of the nanoparticles prepared in Example 1.

[0028] Figure 4 Shown are the molecular weights of the amphiphilic polymer in Example 1 at different reaction times.

[0029] Figure 5 This is a graph showing the change in viscosity over time of the profile control system of combination A constructed from nanoparticles prepared in Example 1 and amphiphilic polymers.

[0030] Figure 6 This is a graph showing the change in viscosity over time of the profile control system of combination B constructed from the nanoparticles prepared in Example 1 and the amphiphilic polymer.

[0031] Figure 7 This is a graph showing the change in viscosity over time of the profile control system constructed with nanoparticles and amphiphilic polymers prepared in the comparative example.

[0032] Figure 8 The pressure dynamic curve diagram of the profile control process of the profile control system constructed with nanoparticles and amphiphilic polymers prepared in Example 1 and Comparative Example. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described in detail below through specific implementation methods.

[0034] In each embodiment, the particle size of the nanoparticles was measured using an NS-90 nanoparticle size analyzer, and the molecular weight of the amphiphilic polymer was measured using a GPC gel chromatography instrument.

[0035] Example 1

[0036] 0.5g acrylamide, 0.05g azobis(methylenebisacrylamide), and 0.01g sodium sulfate of fatty alcohol polyoxyethylene ether were dissolved in 100g deionized water. 0.01g allyl β-cyclodextrin was then added and mixed thoroughly. The aqueous phase was then transferred to a 250mL three-necked flask. 0.1g azobis(isobutyronitrile) initiator was dissolved in 20g styrene to form an oil phase. This phase was slowly poured into the aqueous phase under stirring, emulsified for 30 minutes, then heated to 70°C and allowed to react for 4 hours. After the reaction, the polymerized emulsion was washed with ethanol and dried to obtain surface-containing nanoparticles with β-cyclodextrin groups. The nanoparticles had a particle size of 170nm.

[0037] 1g of N-dodecyl acrylamide and 10g of acrylamide were dissolved in 100g of deionized water with rapid stirring. An atom transfer radical polymerization initiator system consisting of 0.18g of vitamin C, 0.012g of ferric chloride, and 0.2g of sodium chloroacetate was added. The mixture was then heated to 60°C and allowed to react for 40 hours. After the reaction, the mixture was dried to obtain the amphiphilic guest polymer with a number-average molecular weight of 3498.68.

[0038] Example 2

[0039] 0.5g acrylamide, 0.05g N,N'-methylenebisacrylamide, and 0.01g sodium sulfate of fatty alcohol polyoxyethylene ether were dissolved in 100g deionized water. 0.01g allyl β-cyclodextrin was then added and mixed thoroughly. The aqueous phase was then transferred to a 250mL three-necked flask. 0.1g azobisisobutyronitrile initiator was dissolved in 20g styrene to form an oil phase. This phase was slowly poured into the aqueous phase under stirring, emulsified for 30 minutes, then heated to 70°C and allowed to react for 4 hours. After the reaction, the polymerized emulsion was washed with ethanol and dried to obtain bulk nanoparticles with β-cyclodextrin groups on the surface. The nanoparticles had a particle size of 170nm.

[0040] 1g of N-hexadecyl acrylamide and 10g of acrylamide were dissolved in 100g of deionized water with rapid stirring. An atom transfer radical polymerization initiator system consisting of 0.18g of vitamin C, 0.012g of ferric chloride, and 0.2g of sodium chloroacetate was added. The mixture was then heated to 60°C and allowed to react for 40 hours. After the reaction, the mixture was dried to obtain the amphiphilic polymer with a number-average molecular weight of 3788.11.

[0041] Example 3

[0042] 1.0g acrylamide, 0.1g azobis(methylenebisacrylamide), and 0.05g sodium sulfate of fatty alcohol polyoxyethylene ether were dissolved in 100g deionized water. 0.02g allyl β-cyclodextrin was then added and mixed thoroughly. The aqueous phase was then transferred to a 250mL three-necked flask. 0.15g azobis(isobutyronitrile) initiator was dissolved in 25g styrene to form an oil phase. This phase was slowly poured into the aqueous phase under stirring and emulsified for 30 minutes. The reaction was then heated to 70°C and allowed to react for 4 hours. After the reaction, the polymerized emulsion was washed with ethanol and dried to obtain bulk nanoparticles with β-cyclodextrin groups on the surface. The particle size of the nanoparticles was 255nm.

[0043] 1 g of N-dodecyl acrylamide and 10 g of acrylamide were dissolved in 100 g of deionized water, stirred rapidly, and an atom transfer radical polymerization initiator system consisting of 0.18 g of vitamin C, 0.012 g of ferric chloride, and 0.2 g of sodium chloroacetate was added. The temperature was then raised to 60°C and the reaction was continued for 40 h. After the reaction was completed, the mixture was directly dried to obtain a guest amphiphilic polymer with a number average molecular weight of 3498.68.

[0044] Example 4

[0045] 2.0g acrylamide, 0.15g N,N'-methylenebisacrylamide, and 0.1g sodium sulfate of fatty alcohol polyoxyethylene ether were dissolved in 100g deionized water. 0.02g allyl β-cyclodextrin was then added and mixed thoroughly. The aqueous phase was then transferred to a 250mL three-necked flask. 0.2g azobisisobutyronitrile initiator was dissolved in 30g styrene to form an oil phase. This phase was slowly poured into the aqueous phase under stirring, emulsified for 30 minutes, then heated to 70°C and allowed to react for 4 hours. After the reaction, the polymerized emulsion was washed with ethanol and dried to obtain bulk nanoparticles with β-cyclodextrin groups on the surface. The particle size of the nanoparticles was 278nm.

[0046] 1.5 g of N-hexadecyl acrylamide and 15 g of acrylamide were dissolved in 100 g of deionized water, stirred rapidly, and an atom transfer radical polymerization initiator system consisting of 0.20 g of vitamin C, 0.010 g of ferric chloride, and 0.15 g of sodium chloroacetate was added. The temperature was then raised to 60°C and the reaction was continued for 30 h. After the reaction was completed, the mixture was directly dried to obtain a guest amphiphilic polymer with a number average molecular weight of 3316.50.

[0047] Comparative Example

[0048] 2.5g acrylamide, 0.2g N,N'-methylenebisacrylamide, and 0.1g sodium polyoxyethylene fatty alcohol ether sulfate were dissolved in 100g deionized water and mixed thoroughly. The aqueous phase was then transferred to a 250mL three-necked flask. 0.2g azobisisobutyronitrile initiator was dissolved in 30g styrene to form an oil phase. This phase was slowly poured into the aqueous phase under stirring, emulsified for 30 minutes, then heated to 70°C and allowed to react for 4 hours. After the reaction, the polymerized emulsion was washed with ethanol and dried to obtain bulk nanoparticles without β-cyclodextrin groups on the surface. The nanoparticles had a particle size of 268nm.

[0049] 1.5g of N-dodecyl acrylamide and 15g of acrylamide were dissolved in 100g of deionized water with rapid stirring. An atom transfer radical polymerization initiator system consisting of 0.20g of vitamin C, 0.010g of ferric chloride, and 0.15g of sodium chloroacetate was added. The mixture was then heated to 60°C and allowed to react for 30h before drying to obtain the amphiphilic polymer. The polymer had a number average molecular weight of 3012.28.

[0050] Performance Testing

[0051] Taking the host nanoparticles and the guest amphiphilic polymer prepared in Example 1 as an example, their performance was tested.

[0052] Characterization of nanoparticles and amphiphilic polymers

[0053] like Figure 1 The particle size distribution of the prepared main nanoparticles is shown in FIG. Figure 1 It can be seen that the particle size distribution of the nanoparticles is monodisperse, with an average particle size of 170 nm. Figure 2 The scanning electron micrograph of the nanoparticles is shown. Figure 2 It can be seen that the nanoparticles present a regular spherical morphology. Figure 3 The following is a projection electron microscope image of the nanoparticles, from which it can be seen that the nanoparticles present a regular core-shell structure. Figure 4 Shown are the molecular weights of amphiphilic polymers at different reaction times, Figure 4 It can be seen that the molecular weight of the amphiphilic polymer gradually increases with the increase of reaction time. When the acrylamide conversion rate is 76.9%, the molecular weight of the amphiphilic polymer is about 3500.

[0054] Self-assembly properties of nanoparticles and amphiphilic polymers

[0055] 2.1 Taking the host nanoparticles and the guest amphiphilic polymer prepared in Example 1 as an example, the self-assembly performance of the nanoparticles and the amphiphilic polymer was determined by measuring the viscosity change of the profile control system. Specifically:

[0056] Combination A: 0.1g nanoparticles and 0.2g amphiphilic polymer were added to 100g deionized water to prepare a sample solution. The viscosity change of the sample solution was tested using a Haake rheometer at 60°C. The results are as follows: Figure 5 shown.

[0057] Combination B: 0.4g nanoparticles and 0.1g amphiphilic polymer were added to 100g deionized water to prepare a sample solution. The viscosity change of the sample solution was tested using a Haake rheometer at 60°C. The results are as follows: Figure 6 shown.

[0058] 2.2 Taking the host nanoparticles and the guest amphiphilic polymer prepared in the comparative example as an example, the self-assembly performance of the nanoparticles and the amphiphilic polymer was determined by measuring the viscosity change of the profile control system. Specifically:

[0059] 0.1g of nanoparticles and 0.2g of amphiphilic polymer were added to 100g of deionized water to prepare a sample solution. The viscosity change of the sample solution was tested using a Haake rheometer at 60°C. The results are as follows: Figure 7 shown.

[0060] Depend on Figure 5 、 Figure 6 and Figure 7 It can be seen that after the host nanoparticles and the guest amphiphilic polymer self-assemble, the viscosity of the profile control system increases to 90 mPa·s. However, when the nanoparticles in the profile control system do not contain cyclodextrin groups on their surfaces, the nanoparticles and the amphiphilic polymer cannot produce host-guest interactions and cannot self-assemble into particle clusters, and the viscosity of the profile control system remains almost unchanged. Through comparative experiments, the increase in the viscosity of the profile control system can prove the self-assembly of the nanoparticles and the amphiphilic polymer. It can be seen that the nanoparticles prepared by the present invention and the amphiphilic polymer can form a self-assembled structure.

[0061] Profile control simulation experiment

[0062] Profile control simulation experiments were conducted using the host nanoparticles and guest amphiphilic polymers prepared in Example 1 and the comparative example as examples.

[0063] The core model used in the experiment is 30 cm long, 2.5 cm in diameter, and has an average permeability of 200×10 -3 µm 2 , the porosity is 27.2%. During the experiment, the core was first vacuumed and saturated with water at an injection rate of 1 mL / min until the injection pressure stabilized; then a 0.5 PV profile control system was injected at the same injection rate, wherein the profile control system in Example 1 was prepared by adding 0.1 g of nanoparticles and 0.2 g of amphiphilic polymers to 100 g of deionized water, and the profile control system in the comparative example was prepared by adding 0.2 g of nanoparticles and 0.2 g of amphiphilic polymers to 100 g of deionized water; aged at 60°C for 10 h, after the nanoparticles / amphiphilic polymers self-assembled, subsequent water drive was carried out until the pressure at the pressure measuring point was balanced and the experiment was stopped. The experimental results are as follows: Figure 8 As shown in Table 1. According to the formula, the resistance coefficient (Formula 1) and the residual resistance coefficient (Formula 2) are calculated, P0 is the initial water drive stable pressure value, P C is the pressure value during the injection of profile control agent, and P is the water flooding pressure value after plugging control.

[0064]

[0065] As shown in Table 1, when using the nanoparticle / amphiphilic polymer profile control system in Example 1, the injection pressure increases little compared to the water injection pressure, and the resistance coefficient is near 2.0. After the nanoparticle / amphiphilic polymer profile control system self-assembles to form a particle cluster, subsequent water flooding is carried out. At this time, the water flooding pressure obviously rises, and the residual resistance coefficient reaches more than 3.0, and the plugging rate is about 70%. When the profile control system constructed by the nanoparticle / amphiphilic polymer in the comparative example is used, when the nanoparticle / amphiphilic polymer cannot form self-assembly, the profile control system has no plugging effect. Shown by the above comparative experiment, the profile control system constructed by nanoparticle / amphiphilic polymer has good injectability, and can produce stronger plugging ability after self-assembly.

[0066] Table 1 Injectability and plugging effect results of profile control system

[0067]

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solutions of the present invention. They should all be included in the scope of the technical solutions for which protection is sought.

Claims

1. An oil reservoir plugging composition, characterized in that: It consists of nanoparticles and amphiphilic polymers. The nanoparticles have a core-shell structure. The core of the nanoparticles is a monomer with a hydrophobic rigid group. The surface of the nanoparticles is modified with β-cyclodextrin groups and hydrophilic groups. The particle size of the nanoparticles is 50-700 nm. The number average molecular weight of the amphiphilic polymer is 1000-4000. The core of the nanoparticle is an aromatic hydrocarbon compound monomer; The nanoparticles are prepared by emulsion polymerization using styrene, acrylamide, allyl β-cyclodextrin and N,N'-methylenebisacrylamide as synthetic monomers; The hydrophobic group in the amphiphilic polymer is an alkyl chain, and the chain length of the alkyl chain is 12-20 C; The amphiphilic polymer is prepared by using N-dodecyl acrylamide or N-hexadecyl acrylamide as a hydrophobic monomer and acrylamide as a hydrophilic monomer, and is polymerized by free radical initiation.

2. The oil reservoir plugging composition according to claim 1, characterized in that: The nanoparticles contain hydrophobic rigid groups, hydrophilic groups and beta-cyclodextrin groups in a molar ratio of 100:3-15:0.005-0.05, and the particle size of the nanoparticles is 50-300nm.

3. The oil reservoir plugging composition according to claim 1, characterized in that: The molar ratio of the hydrophilic group to the hydrophobic group in the amphiphilic polymer is 100:2.0-5.0, and the number average molecular weight of the amphiphilic polymer is 3000-4000.

4. The method for preparing the oil reservoir plugging composition according to any one of claims 1 to 3, characterized in that: include: The preparation steps of the amphiphilic polymer are as follows: dissolving a hydrophobic monomer and a hydrophilic monomer in deionized water, and using vitamin C, ferric chloride, and sodium chloroacetate as an atom transfer radical polymerization initiator system, and heating to 50-90°C for reaction; The preparation steps of nanoparticles are as follows: dissolving a hydrophilic monomer, N,N'-methylenebisacrylamide, and an emulsifier in deionized water, then adding a compound containing a β-cyclodextrin group and mixing evenly to form an aqueous phase; dissolving an initiator in a hard polymer monomer to form an oil phase, pouring the oil phase into the aqueous phase under stirring conditions, emulsifying, heating to 60-80°C for reaction, and reacting to obtain nanoparticles.

5. The preparation method according to claim 4, characterized in that: During the preparation of the amphiphilic polymer, the hydrophobic monomer accounts for 1% to 3% of the mass fraction of the aqueous phase, the hydrophilic monomer accounts for 10% to 30% of the mass fraction of the aqueous phase, the vitamin C accounts for 0.18% to 0.26% of the mass fraction of the aqueous phase, the ferric chloride accounts for 0.012% to 0.02% of the mass fraction of the aqueous phase, and the sodium chloroacetate accounts for 0.2% to 0.4% of the mass fraction of the aqueous phase. The polymerization reaction time is 5 to 40 hours; in the preparation step of the nanoparticles, the hydrophilic monomer accounts for 0.5% of the mass fraction of the aqueous phase. The β-cyclodextrin group-containing compound is allyl β-cyclodextrin, which accounts for 0.01% to 0.1% by mass of the aqueous phase; N,N'-methylenebisacrylamide accounts for 0.05% to 0.5% by mass of the aqueous phase; the emulsifier is sodium fatty alcohol polyoxyethylene ether sulfate, which accounts for 0.01% to 0.1% by mass of the aqueous phase; styrene accounts for 20% to 30% by mass of the aqueous phase; and azobisisobutyronitrile accounts for 0.1% to 0.2% by mass of the aqueous phase.

6. Use of the oil reservoir plugging composition according to any one of claims 1 to 3, characterized in that: The nanoparticles and the amphiphilic polymer are dissolved in water to form a plugging solution, wherein the concentration of the nanoparticles in the plugging solution is 500-4000 mg / L, and the concentration of the amphiphilic polymer is 1000-3000 mg / L.

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