Carbon dioxide response type core-shell polymer gas channeling regulating agent and preparation method thereof

Abstract

The invention belongs to the technical field of oil exploitation, and particularly relates to a carbon dioxide response type core-shell polymer gas channeling regulating agent and a preparation method thereof. The raw materials comprise an ionic hydrophilic monomer, an amino-containing CO2 response monomer and an orthogonal reaction monomer pair (A-B). Through the design of combining RAFT polymerization with emulsion polymerization and the introduction of an orthogonal reaction monomer pair (A-B), the structure controllability and function synergy are realized. The prepared regulating agent contains a hydrophilic shell layer and a hydrophobic core layer, when CO2 is not introduced, the monomer A and the monomer B do not react due to spatial isolation, and the solution is in a low-viscosity stable state. After CO2 is introduced, the amido-containing CO2 response monomer in the core layer is protonated, the core layer is gradually hydrophilized, the particles absorb water and swell, and the particle size is increased. When a core layer is completely protonated, particles are dissolved, the monomer A and the monomer B are in contact and are subjected to orthogonal reaction, so that a hydrophilic polymer chain is crosslinked to form a three-dimensional hydrogel network, the viscosity of a solution is increased, and the problem of gas channeling caused by high heterogeneity of an oil reservoir of CO2 flooding can be effectively solved.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum extraction, and in particular relates to a carbon dioxide-responsive core-shell polymer gas channeling regulator and a preparation method thereof. Background Art

[0002] Water control and plugging technology has long been an effective means of improving waterflooding development and increasing reservoir production in oilfields. Traditional inorganic control agents are prone to precipitation and cannot penetrate deep into the formation to provide plugging. Movable weak gels have poor crosslinking controllability and high cost. Water-swellable polymer gels are large in size, resulting in a trade-off between injection depth and plugging strength, leading to rapid failure.

[0003] CO2 flooding technology holds significant promise for enhancing oil recovery due to its high oil recovery efficiency and carbon sequestration potential. However, due to the high reservoir heterogeneity and the large difference in the mobility ratio of CO2 to crude oil, CO2 can easily channel along high-permeability pathways during flooding, significantly reducing sweep efficiency. This problem is particularly acute in low-permeability reservoirs, where the coexistence of matrix pores and fractures complicates channeling pathways, making them difficult to effectively block with traditional modulating agents.

[0004] Patent CN118206687A provides a heat-resistant and salt-resistant CO2-stimulated viscosity-increasing polymer for preventing gas channeling in the CO2 flooding process and its preparation method. The polymer comprises acrylamide monomer, CO2-responsive monomer, amphiphilic functional monomer solution and cosolvent, and then an initiator solution is added. N2 is introduced into the sealed reaction to obtain a polymer powder. The viscosity-increasing mechanism of the patented polymer relies on CO2 to protonate the tertiary amine group into a quaternary ammonium salt, thereby increasing the hydrophilicity and electrostatic repulsion of the molecular chain. However, this process is highly reversible, resulting in a temporary plugging and the inability to form a long-term, stable plugging section. Patent CN119529204A provides a triblock expansion viscosity-increasing carbon dioxide gas channeling profile control agent and its preparation method. The profile control agent prepared by the invention can form a gel-like plugging body, but it is difficult to achieve fracture-pore coordinated regulation, and the multi-step synthesis has low production efficiency, high time cost and economic cost, making it difficult to carry out industrial scale-up production.

[0005] Existing plugging agents are primarily designed to target macrofractures and are unable to penetrate micro- and nano-scale matrix pores, making it difficult to achieve synergistic fracture-pore regulation and resulting in short-term plugging. Furthermore, in high-temperature, highly salinized formations, conventional polymers are prone to hydrolysis or salt precipitation, resulting in a sudden drop in viscosity and even precipitation failure. This prevents long-term, stable plugging and makes it difficult to meet actual reservoir requirements. Therefore, developing a synergistic plugging material that combines nanoscale permeability, high-temperature, high-salinity stability, and intelligent CO2 responsiveness has become crucial to breaking through the bottleneck of CO2 flooding channeling control technology. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a carbon dioxide-responsive core-shell polymer gas channeling regulator and a preparation method thereof. Through the precise design of RAFT polymerization (reversible addition-fragmentation chain transfer polymerization) combined with emulsion polymerization and the introduction of orthogonal reaction monomer pairs (AB), the structural controllability, functional synergy and environmental responsiveness of CO2-responsive core-shell polymer nanoparticles are achieved. They are used in the CO2 displacement process of low-permeability oil reservoirs to overcome the problem of severe gas channeling caused by strong formation heterogeneity during crude oil extraction.

[0007] The technical solutions adopted are: A carbon dioxide-responsive core-shell polymer gas channeling regulator, comprising, by molar proportions, 2 to 100 parts of an ionic hydrophilic monomer, 2 to 100 parts of an amino-containing CO2-responsive monomer, and 1 to 50 parts of an orthogonal reaction monomer pair; The orthogonal reaction monomer pair is composed of an orthogonal reaction monomer A and an orthogonal reaction monomer B, i.e., any pair of acrylate carboxyl monomer-acrylate aziridine monomer, acrylate aldehyde monomer-acrylate cyano monomer, acrylate azide monomer-acrylate alkyne monomer; the molar ratio of the orthogonal reaction monomer A to the orthogonal reaction monomer B is 1:0.5-2; The ionic hydrophilic monomer is any one of 2-methacryloyloxyethyltrimethylammonium chloride, 2-acrylamide-2-methylpropanesulfonic acid, N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt, trimethylglycine methacrylate and phosphorylcholine methacrylate, which have heat and salt resistance. The amino-containing CO2 responsive monomer is any one of N, N-diethylaminoethyl acrylate, N, N-dimethylacrylamide, N, N-dimethyl methylacrylamide ethyl ester, N, N-diethyl methylacrylamide ethyl ester, and N, N-dimethylphenylene glycol.

[0008] A method for preparing a carbon dioxide-responsive core-shell polymer gas channeling regulator comprises the following steps: (1) Synthesis of macromolecular chain transfer reagents: Trithioester 2-(dodecyl trithiocarbonate)-2-isobutyric acid, deionized water, orthogonal reaction monomer A, ionic hydrophilic monomer, and initiator I are added to a reactor, purged with nitrogen, and heated for reaction; after the reaction is completed, the reaction solution is poured into a precipitant for precipitation; The precipitate is filtered to obtain a filter cake, and the filter cake is vacuum dried to obtain a macromolecular chain transfer reagent; Wherein, the initiator I is any one of ammonium persulfate and cerium ammonium nitrate; the precipitant is any one of methanol or acetone; (2) Synthesis of CO2-responsive core-shell polymer nanoparticles: An organic solvent is added to a three-necked flask, and then the macromolecular chain transfer reagent aqueous solution prepared in step (1) (i.e., the macromolecular chain transfer reagent is dissolved in water and stirred uniformly), the orthogonal reaction monomer B, the amino-containing CO2 responsive monomer, and the initiator II are added respectively, and ultrasonic stirring is performed for 10 to 30 minutes to emulsify the emulsion into dispersed droplets. After nitrogen purging, the reaction is carried out to obtain CO2 responsive core-shell polymer nanoparticles, i.e., CO2 responsive core-shell polymer nanoparticle gas channeling regulator; Wherein, the initiator II is any one of azobisisobutyronitrile and dimethyl azobisisobutyrate.

[0009] Preferably, in step (1), the molar ratio of trithioester 2-(dodecyl trithiocarbonate)-2-isobutyric acid, ionic hydrophilic monomer, orthogonal reaction monomer A and initiator I is 1-4:10-200:5-100:0.1-1.

[0010] Preferably, the molar ratio of the orthogonal reaction monomer A to the ionic hydrophilic monomer is 1:4.

[0011] Preferably, in step (1), the heating reaction temperature is 60 to 80° C., and the reaction time is 3 to 24 hours.

[0012] Preferably, in step (2), the organic solvent is any one of toluene, xylene and anisole.

[0013] Preferably, in step (2), the molar ratio of the macromolecular chain transfer reagent, the amino-containing CO2 responsive monomer, the orthogonal reaction monomer B and the initiator II is 1-4:10-200:5-100:0.1-1.

[0014] As a further preference, the molar ratio of the orthogonal reaction monomer B to the amino-containing CO2 response monomer is 3:17.

[0015] Preferably, in step (2), the reaction temperature is 60-80° C., and the reaction time is 8-24 hours.

[0016] Compared with the prior art, the present invention has the following beneficial effects: A carbon dioxide-responsive core-shell polymer gas channeling regulator prepared by the present invention has excellent CO2-responsive expansion and viscosity-increasing properties. Before CO2 is introduced, the orthogonal reaction group A and the orthogonal reaction group B are respectively in the hydrophilic shell layer and the hydrophobic core layer, and are not in contact in space, and cannot undergo orthogonal reaction, so that the solution can maintain a stable low viscosity; after CO2 is introduced, the CO2-responsive functional groups in the core layer of the polymer nanoparticles are protonated, and the core layer will gradually become hydrophilic, and the nanoparticles will also gradually increase in particle size due to water absorption and swelling; when the amino-containing CO2-responsive monomer in the hydrophobic core layer is completely protonated, the entire nanoparticle is completely dissolved in water to form a polymer aqueous solution, at which time the orthogonal reaction group pair A and B contact each other and undergo orthogonal reaction, the hydrophilic polymer chains are cross-linked to form a three-dimensional hydrogel network, and the solution viscosity is significantly increased; the prepared CO2-responsive core-shell polymer nanoparticles have adjustable initial particle size and expansion ratio, and the final viscosity-increasing degree is adjustable, which can realize customized functions according to the specific conditions of the oil reservoir, and can also achieve a good viscosity-increasing effect in highly salinized formation water.

[0017] RAFT chain transfer agents ensure uniform polymer chain length, avoiding the broad distribution drawback of traditional emulsion polymerization, resulting in uniform nanoparticle size and excellent injection performance. Orthogonal reactive monomer pairs synergize with amino-containing CO2-responsive monomers to enhance plugging efficiency in fracture-pore complex formations.

[0018] The preparation method of the present invention is simple, the reaction conditions are easy to achieve, and it can be promoted on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the chemical structure of the CO2-responsive core-shell polymer nanoparticle gas channeling regulator prepared in the present invention.

[0020] Figure 2 This is a schematic diagram of the principle of expansion and viscosity increase of CO2-responsive core-shell polymer nanoparticles prepared in the present invention in response to CO2.

[0021] Figure 3 Schematic diagram of the chemical structure of CO2-responsive core-shell polymer nanoparticles prepared in Example 1 of the present invention.

[0022] Figure 4 This is a Fourier transform infrared (FTIR) spectrum of the CO2-responsive core-shell polymer nanoparticles prepared in Example 1 of the present invention.

[0023] Figure 5 Diagrams of the CO2-responsive core-shell polymer nanoparticles prepared in Example 1 before (a) and after (b) injection of CO2 (relative to 100 mol% of CO2-responsive groups on the polymer chain).

[0024] Figure 6Transmission electron microscopy (TEM) images of the CO2-responsive core-shell polymer nanoparticles prepared in Example 1 injected with different amounts of CO2.

[0025] Figure 7 This is a scanning electron microscope (SEM) image of the CO2-responsive core-shell polymer nanoparticles prepared in Example 1 after injection of sufficient CO2 for cross-linking.

[0026] Figure 8 The storage modulus and loss modulus of the CO2-responsive core-shell polymer nanoparticles prepared in Example 1 were increased in viscosity to form a gel after CO2 injection (relative to 100 mol% of CO2-responsive groups on the polymer chain).

[0027] Figure 9 The particle size of the CO2-responsive core-shell polymer nanoparticles prepared in Example 1 changes with the amount of CO2 injected (relative to the mol% of CO2-responsive groups on the polymer chain).

[0028] Figure 10 The viscosity of the CO2-responsive core-shell polymer nanoparticles prepared in Example 1 changes with the amount of CO2 injected (relative to the CO2-responsive groups on the polymer chain).

[0029] Figure 11 The viscosity of the CO2-responsive core-shell polymer nanoparticles prepared in Example 4 changes with the amount of CO2 injected (relative to the CO2-responsive groups on the polymer chain).

[0030] Figure 12 Graph showing the effect of temperature on the particle size of CO2-responsive core-shell polymer nanoparticles prepared in Examples 1-4.

[0031] Figure 13 Graph showing the effect of salt concentration on the particle size of CO2-responsive core-shell polymer nanoparticles prepared in Examples 1-4.

[0032] Figure 14 This is a graph showing the change in final viscosity with temperature after CO2 injection (relative to the CO2 responsive groups on the polymer chain) of the CO2 responsive core-shell polymer nanoparticles prepared in Examples 1-4.

[0033] Figure 15 The final viscosity of the CO2-responsive core-shell polymer nanoparticles prepared in Examples 1-4 after injection of CO2 (relative to the CO2-responsive groups on the polymer chain) varies with salt concentration.

[0034] Figure 16 The particle size change of the CO2-responsive core-shell polymer nanoparticles prepared in Examples 1-4 during the 180-day storage period. DETAILED DESCRIPTION

[0035] The accompanying drawings are for illustrative purposes only. The specific embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and examples. The examples described are only a portion of the entire embodiment and embody the technical features, purposes, and effects of the present invention. For process parameters not otherwise specified, conventional techniques can be used. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0036] like Figure 1 、 2 As shown, the present invention utilizes RAFT polymerization (reversible addition-fragmentation chain transfer polymerization) combined with emulsion polymerization to prepare CO2-responsive core-shell polymer nanoparticles in a two-step process by combining an ionic hydrophilic monomer, an amino-containing CO2-responsive monomer, and an orthogonal reaction monomer. Trithioester 2-(dodecyl trithiocarbonate)-2-isobutyric acid is used as a RAFT agent, and polymerization is controlled by a reversible chain transfer reaction. A macromolecular chain transfer agent is used as a macromolecular emulsifier and chain transfer agent to construct a core-shell structure through step-by-step polymerization. Figure 2 Medium R A is the group of the orthogonal reaction monomer A, R B is the group of the orthogonal reaction monomer A.

[0037] Core layer: Orthogonal reaction monomer B and amino-containing CO2 response monomer are polymerized in an organic solvent to form a hydrophobic core.

[0038] Shell layer: The ionic hydrophilic monomer and the orthogonal reaction monomer A wrap the core layer under the guidance of the hydrophilic macromolecular chain transfer reagent to form an outer shell.

[0039] Before CO2 is introduced, the orthogonal reactive groups A in the shell and B in the core essentially don't come into contact, resulting in no reaction. After a small amount of CO2 is introduced, the CO2-responsive components in the core of the polymer nanoparticle become partially protonated, repelling each other and causing the core to swell and expand. Further CO2 injection causes all CO2-responsive components to protonate, transforming from a hydrophobic state to a hydrophilic state, and the core dissociates. At this point, the polymer chains are fully extended in the solution, and the orthogonal reactive groups A and B come into contact and react, resulting in cross-linking of the polymers to form a three-dimensional network structure, significantly increasing the solution viscosity.

[0040] Example 1: A method for preparing a carbon dioxide-responsive core-shell polymer gas channeling regulator, wherein carbon dioxide-induced expansion and viscosity-increasing core-shell polymer nanoparticles are prepared by RAFT polymerization combined with emulsion polymerization. The regulator has the characteristics of CO2-responsive expansion and viscosity-increasing, high temperature resistance, and salt resistance. The preparation process includes the following steps: S1. Synthesis of Macromolecular Chain Transfer Reagents: 0.01 g of RAFT365 20 mL of deionized water, 1.44 g of orthogonal reaction monomer A (acrylic acid monomer), 1 g of N,N-dimethyl(methacryloyloxyethyl)aminopropanesulfonic acid inner salt, and 2 mg of ammonium persulfate were added. After nitrogen purging, the mixture was ultrasonically stirred at 70°C for 12 hours. After completion of the reaction, the reaction solution was poured into methanol for precipitation, filtered, and the filter cake was vacuum dried to obtain the macromolecular chain transfer reagent.

[0041] S2. Synthesis of CO2-responsive core-shell polymer nanoparticles: In a three-necked flask, 5 mL of the aqueous solution containing 0.05 g of the macromolecular chain transfer reagent prepared in S1, 10 mL of toluene, 1.2 g of N, N-diethylaminoethyl acrylate, 0.6 g of the orthogonal reaction monomer B aziridine monomer and 2 mg of azobisisobutyronitrile were added respectively. The mixture was ultrasonically stirred for 20 min to emulsify it into small-sized dispersed droplets. After nitrogen purging, the mixture was stirred at 70 °C for 12 h to obtain CO2-responsive core-shell polymer nanoparticles.

[0042] Example 2: A method for preparing a carbon dioxide-responsive core-shell polymer gas channeling regulator. When synthesizing CO2-responsive core-shell polymer nanoparticles, the difference is that the orthogonal reaction monomer A used in step S1 is 0.72 g of acrylic acid monomer, and CO2-responsive core-shell polymer nanoparticles are obtained.

[0043] The remaining parts not mentioned are the same as those in Example 1.

[0044] Example 3: A method for preparing a carbon dioxide-responsive core-shell polymer gas channeling regulator. When synthesizing CO2-responsive core-shell polymer nanoparticles, the difference is that the orthogonal reaction monomer A used in step S1 is 1.71 g of 5-acrylamide valeric acid, to obtain CO2-responsive core-shell polymer nanoparticles.

[0045] The remaining parts not mentioned are the same as those in Example 1.

[0046] Example 4: A method for preparing a carbon dioxide-responsive core-shell polymer gas channeling regulator. When synthesizing CO2-responsive core-shell polymer nanoparticles, the difference is that the orthogonal reaction monomer A used in step S1 is 1.57 g of 4-acrylamidebutyric acid, to obtain CO2-responsive core-shell polymer nanoparticles.

[0047] The remaining parts not mentioned are the same as those in Example 1.

[0048] The carbon dioxide-responsive core-shell polymer gas channeling regulators prepared in Examples 1-4 were tested.

[0049] 1) CO2 responsiveness test.

[0050] a. Expansion performance: CO2-responsive core-shell polymer nanoparticles in Examples 1-4 were selected, and the hydrodynamic diameters of the nanoparticles in CO2 environments and air environments were measured by dynamic light scattering to characterize the CO2-responsive expansion behavior of the nanoparticles.

[0051] At 25°C, the polymer nanoparticles prepared in Example 1 had an initial particle size of 250-300 nm before CO2 injection, and a particle size of 950-1300 nm after CO2 injection (relative to 20 mol% of the tertiary amine on the polymer); The polymer nanoparticles prepared in Example 2 had an initial particle size of 320-380 nm before CO2 injection, and a particle size of 1020-1350 nm after CO2 injection (relative to 20 mol% of the tertiary amine on the polymer); The polymer nanoparticles prepared in Example 3 had an initial particle size of 200-280 nm before CO2 injection, and a particle size of 800-1000 nm after CO2 injection (relative to 20 mol% of the tertiary amine on the polymer); The polymer nanoparticles prepared in Example 4 had an initial particle size of 380-430 nm before CO2 injection, and a particle size of 1200-1500 nm after CO2 injection (20 mol % relative to the tertiary amine on the polymer).

[0052] b. Viscosity Test: The core-shell polymer nanoparticles of Examples 1-4 were selected, and the viscosity changes of the nanoparticles after expansion in air and CO2 at different temperatures (10-110°C) were measured using the plate measurement system in a rotational rheometer, where the shear strain was 1% and the oscillation frequency was 10 Hz.

[0053] At 25°C, the polymer nanoparticles prepared in Example 1 had an initial viscosity of 43-48 mPa·s before CO2 injection, and a particle size of 83,000-88,000 mPa·s after CO2 injection (relative to 20 mol% of the tertiary amine on the polymer); The polymer nanoparticles prepared in Example 2 had an initial viscosity of 31-35 mPa·s before CO2 injection, and a particle size of 71,000-76,000 mPa·s after CO2 injection (relative to 20 mol% of the tertiary amine on the polymer); The polymer nanoparticles prepared in Example 3 had an initial viscosity of 57-65 mPa·s before CO2 injection, and a particle size of 85,000-100,000 mPa·s after CO2 injection (relative to 20 mol% of the tertiary amine on the polymer); The polymer nanoparticles prepared in Example 4 had an initial viscosity of 84-92 mPa·s before CO2 injection, and a particle size of 92,000-115,000 mPa·s after CO2 injection (relative to 20 mol% of tertiary amine on the polymer).

[0054] Therefore, the particle size and viscosity increased significantly after CO2 injection.

[0055] 2) Temperature and salt resistance test.

[0056] The core-shell polymer nanoparticles in Examples 1-4 were selected to test the viscosity and particle size changes of the nanoparticles in NaCl solutions at different temperatures (25°C to 100°C) and different salt concentrations (0% to 15 wt%). Figure 10-13 shown.

[0057] 3) Stability test.

[0058] The core-shell polymer nanoparticles in Examples 1-4 were selected and the particle size change of the nanoparticles was tested within 180 days. Figure 14 shown.

[0059] The present invention discloses a carbon dioxide responsive core-shell polymer gas channeling regulator, wherein the shell layer comprises a hydrophilic component and an orthogonal reaction group A, and the core layer comprises a CO2 responsive component and an orthogonal reaction group B.

[0060] Depend on Figure 4 It can be seen that the infrared characteristic absorption peak of the core-shell structure polymer nanoparticles prepared in Example 1 is 1189 cm −1 and 1067 cm −1 Corresponding to the sulfonic acid group (-SO3 − ) asymmetric stretching vibration and symmetric stretching vibration. Characteristic peak 3320cm −1 Due to the amide group (–CONH - ) stretching vibration of N–H in 1451 cm −1 、1550 cm −1 The peak at 1660 cm is the mixed surface bending vibration peak of CN and N–H in –CONH-. −1 and 3192 cm −1 The stretching vibration peaks of OH and C=O in the carboxyl group are shown above. From the perspective of molecular design, the core-shell polymer nanoparticles were successfully prepared.

[0061] Depend on Figure 5 It can be seen that the 10 mg / mL core-shell polymer nanoparticle system prepared in Example 1 thickened and turned into a gel after the injection of CO2 (relative to 100 mol% of the CO2 responsive groups on the polymer chain) (b in the figure).

[0062] Depend on Figure 6It can be seen that after the 10 mg / mL core-shell polymer nanoparticle system prepared in Example 1 was injected with CO2 (20 mol% relative to the CO2 responsive groups on the polymer chain), the nanoparticles began to swell. When the injection amount of CO2 was further increased (100 mol% relative to the CO2 responsive groups on the polymer chain), the nanoparticles dissociated.

[0063] Depend on Figure 7 It can be seen that the gel generated by the core-shell polymer nanoparticles prepared in Example 1 after the injection of CO2 (relative to 100 mol% of the CO2 responsive groups on the polymer chain) has a typical three-dimensional network structure.

[0064] Depend on Figure 8 It can be seen that the gel generated by the core-shell polymer nanoparticles prepared in Example 1 after injecting CO2 (relative to 100 mol% of the CO2 responsive group on the polymer chain) has a storage modulus of 15~20 Pa and a loss modulus of 0~5 Pa in the angular frequency range of 0.1~100 rad / s. The storage modulus is greater than the loss modulus, indicating that it is in a gel state.

[0065] Depend on Figure 9 It can be seen that when the CO2 injection amount is in the range of 0~25 mol% (relative to the CO2 response group on the polymer chain), the particle size of the nanoparticles prepared in Example 1 gradually expands and increases with the increase of CO2 injection amount (from 250±30 nm to 1265±91 nm); when CO2 injection continues, the particle size of the nanoparticles decreases sharply to 18±4 nm, indicating that the nanoparticles have dissociated into a polymer solution at this time.

[0066] Depend on Figure 10 As shown, within the CO2 injection range of 0–25 mol% (relative to the CO2-responsive groups on the polymer chain), the viscosity of the 10 mg / mL core-shell polymer nanoparticle system prepared in Example 1 slowly increases due to nanoparticle expansion. At a CO2 injection rate of 30 mol%, the viscosity decreases, attributed to nanoparticle dissociation. Subsequent increases in the CO2 injection rate lead to a sharp increase in the system viscosity, reaching 81,741 ± 2,252 mPa·s at 50 mol%. Further increases in the CO2 injection rate lead to a gradual increase in the viscosity, ultimately reaching 85,488 ± 1,898 mPa·s.

[0067] Depend on Figure 11As can be seen, within the CO2 injection range of 0–20 mol% (relative to the CO2-responsive groups on the polymer chain), the viscosity of the 10 mg / mL core-shell polymer nanoparticle system prepared in Example 4 slowly increases due to nanoparticle expansion. At a CO2 injection rate of 25 mol%, the viscosity decreases, which is attributed to nanoparticle dissociation. Subsequent increases in the CO2 injection rate lead to a sharp increase in the system viscosity, reaching 101,692 ± 8,352 mPa·s at 55 mol%. Further increases in the CO2 injection rate lead to a gradual increase in the viscosity, ultimately reaching 111,425 ± 5,538 mPa·s.

[0068] Depend on Figure 12 It can be seen that within the temperature range of 25-100°C, as the temperature increases, the particle size of the 10 mg / mL nanoparticles of Examples 1-4 gradually increases, but the increase is small and the overall effect is relatively stable. The effect of temperature on the particle size of the nanoparticles is small.

[0069] Depend on Figure 13 It can be seen that the salt concentration (1-15%) has almost no effect on the particle size of the nanoparticles of Examples 1-4.

[0070] Depend on Figure 14 It can be seen that the final viscosity of the core-shell polymer nanoparticle system prepared in Examples 1-4 at a concentration of 10 mg / mL after injection of 100 mol% CO2 (relative to the CO2 responsive groups on the polymer chain) is not sensitive to temperature, and the final viscosity is basically consistent in the range of 25~100℃.

[0071] Depend on Figure 15 It can be seen that the final viscosity of the core-shell polymer nanoparticle system prepared in Examples 1-4 at a concentration of 10 mg / mL after injection of 100 mol% CO2 (relative to the CO2 responsive groups on the polymer chain) is not sensitive to salt concentration, and the final viscosity is basically the same within the salt concentration range of 0~15%.

[0072] Depend on Figure 16 It can be seen that the particle size of the core-shell polymer nanoparticles prepared in Examples 1-4 at a concentration of 10 mg / mL does not change much during the 180-day storage period and remains basically consistent, indicating that the nanoparticles are very stable.

[0073] Example 5: A method for preparing a carbon dioxide-responsive core-shell polymer gas channeling regulator, comprising the following steps: S1. Synthesis of macromolecular chain transfer reagents: To a three-necked flask, add 0.02 g of RAFT365, 40 mL of deionized water, 1.76 g of benzaldehyde acrylate (orthogonal monomer A), 3.2 g of 2-acrylamido-2-methylpropanesulfonic acid, and 3 mg of ceric ammonium nitrate. After purging with nitrogen, the mixture was stirred ultrasonically at 75°C for 10 hours. After completion of the reaction, the reaction mixture was poured into acetone for precipitation, filtered, and the filter cake was vacuum-dried to obtain the macromolecular chain transfer reagent.

[0074] S2. Synthesis of CO2-responsive core-shell polymer nanoparticles: In a three-necked flask, 10 mL of an aqueous solution containing 0.1 g of a macromolecular chain transfer reagent prepared in S1, 20 mL of toluene, 2.56 g of N,N-dimethylacrylamide propyl acrylate, 1.97 g of acrylic acid acetonitrile (a monomer obtained by the reaction of HEMA and cyanoacetic acid), and 3 mg of dimethyl azobisisobutyrate were added respectively. Ultrasonic stirring was used to emulsify the solution into small droplets. After nitrogen purging, the solution was stirred at 70 °C for 16 hours to obtain CO2-responsive core-shell polymer nanoparticles.

[0075] Example 6: A method for preparing a carbon dioxide-responsive core-shell polymer gas channeling regulator. When synthesizing CO2-responsive core-shell polymer nanoparticles, the difference is that the orthogonal reaction monomer A used in step S1 is 2.69 g of acrylate azide (a monomer obtained by the reaction of HEMA and 6-azidohexanoic acid) and the orthogonal reaction monomer B used in step S2 is 1.82 g of acrylic acid alkyne (a monomer obtained by the reaction of HEMA and propiolic acid), resulting in CO2-responsive core-shell polymer nanoparticles.

[0076] The remaining parts not mentioned are the same as those in Example 5.

[0077] The present invention provides a method for preparing a carbon dioxide-responsive core-shell polymer gas channeling regulator, which has good CO2-responsive viscosity increase, temperature resistance, and salt resistance, and can achieve gas channel blocking and flow regulation during the CO2 displacement process under high temperature and high salinity.

[0078] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A carbon dioxide responsive core-shell polymer gas channeling regulator, characterized in that The raw materials include, by mole ratio: 2 to 100 parts of ionic hydrophilic monomer, 2 to 100 parts of amino-containing CO2 responsive monomer, and 1 to 50 parts of orthogonal reaction monomer pair; The orthogonal reaction monomer pair is composed of an orthogonal reaction monomer A and an orthogonal reaction monomer B, i.e., any pair of acrylate carboxyl monomer-acrylate aziridine monomer, acrylate aldehyde monomer-acrylate cyano monomer, acrylate azide monomer-acrylate alkyne monomer; the molar ratio of the orthogonal reaction monomer A to the orthogonal reaction monomer B is 1:0.5-2; The ionic hydrophilic monomer is any one of 2-methacryloyloxyethyltrimethylammonium chloride, 2-acrylamide-2-methylpropanesulfonic acid, N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt, trimethylglycine methacrylate and phosphorylcholine methacrylate, which have heat and salt resistance. The amino-containing CO2 responsive monomer is any one of N, N-diethylaminoethyl acrylate, N, N-dimethylacrylamide, N, N-dimethyl methylacrylamide ethyl ester, N, N-diethyl methylacrylamide ethyl ester, and N, N-dimethylphenylene glycol.

2. The method for preparing a carbon dioxide responsive core-shell polymer gas channeling regulator according to claim 1, wherein: The steps include: (1) Synthesis of macromolecular chain transfer reagents: Trithioester 2-(dodecyl trithiocarbonate)-2-isobutyric acid, deionized water, orthogonal reaction monomer A, ionic hydrophilic monomer, and initiator I are added to a reactor, purged with nitrogen, and heated for reaction; after the reaction is completed, the reaction solution is poured into a precipitant for precipitation; The precipitate is filtered to obtain a filter cake, and the filter cake is vacuum dried to obtain a macromolecular chain transfer reagent; Wherein, the initiator I is any one of ammonium persulfate and cerium ammonium nitrate; the precipitant is any one of methanol or acetone; (2) Synthesis of CO2-responsive core-shell polymer nanoparticles: An organic solvent is added to a three-necked flask, and then the macromolecular chain transfer reagent aqueous solution, orthogonal reaction monomer B, amino-containing CO2 responsive monomer and initiator II prepared in step (1) are added respectively, and ultrasonic stirring is performed for 10 to 30 minutes to emulsify them into dispersed droplets. After nitrogen purge, the reaction is carried out to obtain CO2 responsive core-shell polymer nanoparticles, i.e., CO2 responsive core-shell polymer nanoparticle gas channeling regulator; Wherein, the initiator II is any one of azobisisobutyronitrile and dimethyl azobisisobutyrate.

3. The method for preparing a carbon dioxide responsive core-shell polymer gas channeling control agent according to claim 2, characterized in that: In the step (1), the molar ratio of trithioester 2-(dodecyl trithiocarbonate)-2-isobutyric acid, ionic hydrophilic monomer, orthogonal reaction monomer A and initiator I is 1-4:10-200:5-100:0.1-1.

4. The method for preparing a carbon dioxide responsive core-shell polymer gas channeling control agent according to claim 3, characterized in that: The molar ratio of the orthogonal reaction monomer A to the ionic hydrophilic monomer is 1:

4.

5. The method for preparing a carbon dioxide responsive core-shell polymer gas channeling control agent according to claim 2, wherein: In the step (1), the heating reaction temperature is 60 to 80° C., and the reaction time is 3 to 24 hours.

6. The method for preparing a carbon dioxide responsive core-shell polymer gas channeling control agent according to claim 2, characterized in that: In the step (2), the organic solvent is any one of toluene, xylene and anisole.

7. The method for preparing a carbon dioxide responsive core-shell polymer gas channeling control agent according to claim 3, characterized in that: In the step (2), the molar ratio of the macromolecular chain transfer reagent, the amino-containing CO2 responsive monomer, the orthogonal reaction monomer B and the initiator II is 1-4:10-200:5-100:0.1-1.

8. The method for preparing a carbon dioxide responsive core-shell polymer gas channeling regulator according to claim 7, characterized in that: The molar ratio of the orthogonal reaction monomer B to the amino-containing CO2 response monomer is 3:

17.

9. The method for preparing a carbon dioxide responsive core-shell polymer gas channeling control agent according to claim 2, characterized in that: In step (2), the reaction temperature is 60 to 80°C and the reaction time is 8 to 24 hours.

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