Temperature / CO2 dual-response zwitterionic hydrogel profile control agent and preparation method thereof

Abstract

The invention discloses a temperature / CO2 dual-response zwitterionic hydrogel profile control agent, which is prepared by taking a monomer A, a monomer B and a monomer C as raw materials, adding a cross-linking agent and an initiator, and carrying out polymerization reaction in a water medium. The monomer A is selected from any one of acrylamide, acrylic acid and 1-vinyl-2-pyrrolidone; the monomer B is selected from any one of [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide, 2-methacryloyloxyethyl phosphorylcholine and 3-((2-(methacryloyloxy) ethyl) dimethylamino) propionic acid inner salt; and the monomer C is selected from any one of 2-(dimethylamino) ethyl methacrylate, dimethylamino propyl methacrylamide and polyethyleneimine. The profile control agent has double swelling mechanisms, has outstanding temperature and salt resistance, resists 220000 mg / L of mineralization water, is suitable for high-salt reservoirs, and is good in long-term aging property.

Description

Technical Field

[0001] The present invention relates to the technical field of oilfield chemical water plugging and profile control agents, and in particular to a temperature / CO 2 dual-responsive zwitterionic hydrogel profile control agent and its preparation method. Background Art

[0002] With the in-depth development of oilfields, the permeability of oil reservoirs has become increasingly complex. Especially during the water alternating gas (WAG) flooding process, the injection of water and gas alternates, which can lead to excessive water absorption in some high-permeability layers or too rapid gas loss, resulting in the failure of injected water or gas and seriously affecting the oil recovery rate of the oilfield. Especially during the process of alternating injection of water and gas, in some areas, due to the mismatch of water and gas, excessive water injection often occurs and it is unable to effectively displace the crude oil in the reservoir, resulting in uneven oil displacement effect and further reducing the oil recovery rate. There is also the problem of water channeling in the WAG flooding. Therefore, how to solve the water plugging problem in the WAG flooding and improve the oil recovery rate of the oilfield has become an urgent technical problem to be solved. Although the profile control agents currently used in the field have achieved certain results, the profile control and water plugging material particles have a fast water absorption and swelling rate, limited injection depth, and the particle materials are prone to fragmentation after water absorption saturation, unable to achieve precise plugging, with poor plugging effect and high cost.

[0003] For example, Patent CN107445857A discloses a preparation method of a long-chain alkyl acid amide propyl dimethylamine with CO 2 responsive performance, and its aqueous solution can be used as a CO 2 responsive gel. The prepared compound can also be used in enhanced oil recovery applications in oil and gas fields. Its aqueous solution belongs to an in-situ forming gel, and chromatographic separation effects may occur in the formation, and the preparation conditions are harsh and the response mechanism is single.

[0004] Patent CN118772327A discloses a CO 2 responsive deep profile control agent and its preparation method and application. The prepared deep profile control agent can be injected deep into the formation at an injection pressure close to that of water. After reacting with CO 2 in the deep formation, it undergoes secondary swelling, thereby achieving the purpose of selectively plugging the CO 2 channeling layer. However, it only conducts plugging through a CO 2 single response mechanism, with a single response condition, and does not consider the tolerance to extreme formation environments and long-term aging.

[0005] In summary, existing prefabricated particle profile control agents are difficult to migrate deep into the reservoir. They not only undergo hydrolysis under high-temperature conditions but also experience salt shrinkage under high salinity conditions, and their deformability is average, making them unsuitable for reservoir stimulation work under harsh conditions. To address the profile control and water plugging work in medium-high temperature and high salinity environments, the present invention designs a dual-intelligent response profile control agent with excellent mechanical properties and temperature and salt resistance. Summary of the Invention

[0006] Aiming at the defects that existing prefabricated particle profile control agents cannot migrate to the far well zone, the response conditions are single and uncontrollable, and they cannot exert their due effects in the face of high-salinity reservoirs and long-term aging conditions. The present invention provides a temperature / CO 2 dual-responsive zwitterionic hydrogel profile control agent.

[0007] The temperature / CO 2 dual-responsive zwitterionic hydrogel profile control agent provided by the present invention is prepared as follows:

[0008] Dissolve monomer A, monomer B, and monomer C in water to form an aqueous solution, add a crosslinking agent, disperse evenly in an ultrasonic instrument, pass nitrogen for 30 minutes, then add an initiator, stir magnetically until evenly mixed, and react at 50 - 70 °C for 10 - 15 h. After the reaction ends, take out the product, cut, dry, and crush it to obtain the target hydrogel profile control agent.

[0009] The monomer A is selected from any one of acrylamide, acrylic acid, and 1-vinyl-2-pyrrolidone.

[0010] The monomer B is a zwitterionic monomer and is selected from any one of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide, 2-methacryloyloxyethyl phosphorylcholine, and 3-((2-(methacryloyloxy)ethyl)dimethylamino) propionic acid inner salt.

[0011] The monomer C is a carbon dioxide-responsive monomer containing a tertiary amine group and is specifically selected from any one of ethyl 2-(dimethylamino)acrylate, dimethylaminopropyl methacrylamide, and polyethyleneimine.

[0012] The crosslinking agent is selected from any one of N,N-methylenebisacrylamide, 1,6-hexanediol diacrylate, and divinylbenzene.

[0013] The initiator is selected from any one of potassium persulfate, ammonium persulfate, and sodium persulfate.

[0014] The dosage ratios of each raw material are as follows:

[0015] Monomer A accounts for 10%-30% of the mass of water, monomer B accounts for 5-30% of the mass of monomer A, monomer C accounts for 20-40% of the mass of monomer A, the cross-linking agent accounts for 0.5-1% of the mass of monomer A, and the initiator accounts for 0.2%-2% of the total mass of the three monomers.

[0016] Preferably, the polymerization reaction conditions are to react at 60 °C for 12 h.

[0017] Aiming at the problem that conventional profile control agents have too high swelling performance in a low-salt environment and poor swelling performance in a high-salt environment, the present invention solves this problem by adding zwitterionic monomer B. Monomer B belongs to betaine zwitterionic monomer, and the zwitterions with an upper critical solution temperature (UCST) show increased hydrophilicity with increasing temperature because the inter- and intra-electrostatic associations will be disrupted in the positively and negatively charged parts. In addition, the solubility of such zwitterionic polymers in aqueous salt solutions will also increase. When swelling under pure water conditions, the anions and cations in the gel network will attract each other, thereby controlling the overall swelling ratio of the gel not to be too large; while in a high-salt environment, the anions and cations will be attracted by the positive and negative charges present in the environment and thus disperse, allowing the main chain to fully absorb water. This property is called the anti-polyelectrolyte effect, and this property is currently rarely applied in particulate profile control agents, but using this property can enable it to cope with the high-salt reservoir conditions that conventional profile control agents are difficult to handle. And the zwitterionic monomer used in the present invention has UCST, mainly C-UCST relying on Coulomb electrostatic attraction, and the response temperature can be adjusted. Between the positive and negative ions of the same unit within the zwitterionic polyelectrolyte molecule, between the ions of different units within the molecule, and between the positive and negative ion groups on different molecular chains, ion pairs can be formed through electrostatic interactions. At this time, the polymer molecular chain is in a curled state and has poor water solubility. When the temperature rises above its UCST, the interaction between the positive and negative ion groups weakens under the action of thermal energy, and the interaction between the polymer molecular chain and water molecules strengthens, and the molecular chain is in an extended state, showing hydrophilicity.

[0018] The monomer C is CO 2 Responsive monomer, so that the prepared polymer profile control agent has CO 2 Responsive performance, CO 2 As a greenhouse gas, while enhancing oil recovery in the oilfield, greenhouse gas sequestration is also carried out, which conforms to the concept of green development. In water-alternating-gas flooding, the dual-responsive swelling solves the problem that conventional prefabricated particulate gels are difficult to migrate deep. At low temperature and in the absence of response stimuli, the particles are easy to inject, and when the target reservoir temperature is reached and there are stimulation points, swelling plays a profile control role.

[0019] The polymer profile control agent of the present invention is based on the formation temperature and greenhouse gas CO 2As a response point, it is environmentally friendly, has low economic costs, is conducive to industrial production, and the response conditions are controllable, and the transition temperature can be adjusted.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) Compared with the existing prefabricated particle gel profile control agents, the hydrogel profile control agent of the present invention has better swelling performance, more intelligent response, and more remarkable salt tolerance. Most of the existing CO 2 responsive gel profile control agents can handle a salinity of 10,000 mg / L, while the profile control agent of the present invention can withstand a salinity of 220,000 mg / L water, has a high divalent ion content, and is suitable for high-salt reservoirs. In the core displacement experiment, the displacement pressure difference of the particles after response is significantly increased compared with that before response.

[0022] (2) The hydrogel profile control agent of the present invention has the characteristics of shrinking in pure water and swelling in salt water, and can cope with the harsh oilfield production environment.

[0023] (3) The process equipment and steps of the present invention are simple, the reaction conditions are convenient, it is easy to industrialize, the system is cheap and easy to obtain, and the cost is saved.

[0024] (4) The present invention solves the environmental pollution problem caused by the direct emission of greenhouse gas CO 2 Resources are reused. While carrying out CO 2 oil displacement, greenhouse gas sequestration is carried out, which is in line with green development.

[0025] (5) The present invention has a dual response mechanism, breaks through the single trigger limit, and adapts to complex formation conditions.

[0026] Other advantages, objectives and features of the present invention will be partially reflected by the following description, and partially will also be understood by those skilled in the art through the research and practice of the present invention. Description of the Drawings

[0027] Figure 1 It is a scanning electron microscope image of the gel profile control agent of Example 1.

[0028] Figure 2 It is the test result of the temperature and salt tolerance aging performance of the profile control agent particles of Example 1.

[0029] Figure 3 It is a comparison diagram of the profile control agent particles of Example 1 before swelling under different salinities. From left to right, they are 5×10 4 mg / L, 10×10 4 mg / L, 15×10 4 mg / L, 22×10 4 mg / L corresponding diagrams.

[0030] Figure 4 It is a comparison chart of the profile control agent particles in Example 1 after swelling at different salinities. From left to right, they are 5×10 4 mg / L, 10×10 4 mg / L, 15×10 4 mg / L, 22×10 4 mg / L corresponding charts.

[0031] Figure 5 It is the result chart of the core migration pressure difference characteristic curve of the profile control agent particles in Example 1. Specific embodiments

[0032] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0033] Example 1

[0034] A temperature / CO 2 Dual-responsive zwitterionic hydrogel profile control agent, and the preparation method is as follows:

[0035] Dissolve 10 g of acrylamide in 90 g of deionized water, then add 1.5 g of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide, 2 mL of 2-(dimethylamino)ethyl methacrylate, and 0.05 g of N,N-methylenebisacrylamide crosslinking agent. After magnetic stirring evenly, disperse evenly in an ultrasonic instrument; pass nitrogen for 30 minutes, then add 0.07 g of potassium persulfate, stir evenly magnetically and react at 60 °C for 12 h. After taking out, cut, dry, and pulverize to obtain the target product hydrogel profile control agent.

[0036] Figure 1 It is the scanning electron microscope image of the gel profile control agent prepared in Example 1.

[0037] Comparative Example 1

[0038] On the basis of Example 1, replace [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide with an equal amount of 2-acrylamido-2-methylpropanesulfonic acid to prepare a profile control agent.

[0039] Comparative Example 2

[0040] On the basis of Example 1, replace [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide with an equal amount of dimethyldiallylammonium chloride to prepare a profile control agent.

[0041] Comparative Example 3

[0042] After dissolving 10 g of acrylamide in 90 g of deionized water, 0.05 g of N,N'-methylenebisacrylamide crosslinking agent was added. After magnetic stirring evenly, it was dispersed evenly in an ultrasonic instrument. Then 0.07 g of potassium persulfate was added. After magnetic stirring evenly, the reaction was carried out at 60 °C for 12 h. After taking out, it was cut, dried, and pulverized to obtain the profile control agent.

[0043] Example 2

[0044] A temperature / CO 2 Dual-responsive zwitterionic hydrogel profile control agent, the preparation method is as follows:

[0045] After dissolving 15 mL of acrylic acid in 85 g of deionized water, 3 g of 2-methacryloyloxyethyl phosphorylcholine, 4.5 mL of dimethylaminopropyl methacrylamide, and 0.075 mL of divinylbenzene crosslinking agent were added. After magnetic stirring evenly, it was dispersed evenly in an ultrasonic instrument, and nitrogen was passed for 30 minutes. Then 0.1 g of ammonium persulfate was added. After magnetic stirring evenly, the reaction was carried out at 60 °C for 12 h. After taking out, it was cut, dried, and pulverized to obtain the hydrogel profile control agent.

[0046] Example 3

[0047] A temperature / CO 2 Dual-responsive zwitterionic hydrogel profile control agent, the preparation method is as follows:

[0048] After dissolving 10 g of 1-vinyl-2-pyrrolidone in 90 g of deionized water, 1 g of 3-((2-(methacryloyloxy)ethyl)dimethylammonio)propionate, 2 mL of polyethyleneimine, and 0.05 g of N,N'-methylenebisacrylamide crosslinking agent were added. After magnetic stirring evenly, it was dispersed evenly in an ultrasonic instrument, and nitrogen was passed for 30 minutes. Then 0.07 g of sodium persulfate was added. After magnetic stirring evenly, the reaction was carried out at 60 °C for 12 h. After taking out, it was cut, dried, and pulverized to obtain the hydrogel profile control agent.

[0049] Experimental Example 1

[0050] The dried profile control agent particles prepared in Examples 1-3 and Comparative Examples 1-3 were respectively placed in pure water and mineralized water (the composition is shown in Table 1) to swell for 24 h, and the swelling performance comparison at room temperature was carried out. The results are shown in Table 2.

[0051] Table 1 Composition of mineralized water

[0052]

[0053] Table 2 Comparison test results of swelling performance (swelling ratio)

[0054]

[0055] From the data comparison in Table 2, it can be seen that the ordinary gel without any salt-resistant and responsive monomers (Comparative Example 3) has a very low swelling ratio in mineralized water and is prone to hydrolysis or salt shrinkage. To solve this problem, a general solution is to add temperature- and salt-resistant monomers with a single ionic property (such as Comparative Example 1 and Comparative Example 2) to improve its swelling ratio in salt water. According to the experimental data, compared with the ordinary gel in Comparative Example 3, although the profile control agents in Comparative Example 1 and 2 have a better swelling ratio in mineralized water, due to the reason of like-charge repulsion, their swelling ratio increases more significantly in pure water. This property is called the polyelectrolyte effect. This property will cause the particulate profile control agent with a single ionic property to only plug the shallow areas with a lower salinity and cannot migrate to the deeper areas with a higher salinity. In view of this situation, the present invention endows the profile control agent with an anti-polyelectrolyte effect by adding zwitterionic monomers. For example, in pure water, due to the amphiphilic attraction of the anionic and cationic monomers, the swelling ratios of the profile control agents in Examples 1-3 are significantly lower than those in Comparative Examples 1-3, and the swelling ratio of Example 2 is the smallest; while in salt water, the swelling ratios of Examples 1-3 are significantly greater than those in Comparative Examples 1-3, and the swelling ratio of Example 2 is the largest. This is because the addition amount of zwitterionic monomers in Example 2 is the largest among the three groups of examples, so its swelling ratio is the lowest in pure water and the highest in salt water among the three groups of examples. This abnormal swelling performance makes the profile control agent of the present invention more suitable for actual profile control operations. After adding zwitterionic monomers, the salt tolerance of the profile control agent of the present invention is significantly improved. The zwitterionic monomers also have UCST and act as both salt-resistant monomers and temperature-responsive monomers at the same time. [2-(Methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide used in Example 1 has a UCST that can be adjusted between 40°C and 80°C, which can cope with formations at different temperatures.

[0056] Experimental Example 2

[0057] Salt tolerance and aging performance test: Put the profile control agent particles in Example 1 into a pressure-resistant bottle, add the same mineralized water as above, adjust the pH of the solution to about 5.5 during this period, simulate CO 2 and introduce it until saturated, age in an aging oven at 70°C for 45 days, and take pictures and record observations at 0d, 5d, 10d, 20d, 30d, and 45d respectively. Evaluate the temperature and salt tolerance stability of the particles, observe whether the appearance of the sample is broken, measure and calculate the swelling ratio, and the test results are as Figure 2 shown.

[0058] Use the visual inspection code method to describe the gel strength during the aging process. In the laboratory, the gel sample strength can be quickly observed by this method. By observing the gel morphology at different aging times and referring to the strength code table, the temperature tolerance performance can be intuitively judged. The specific content of the gel strength code table is shown in Table 3.

[0059] Table 3 Gel Strength Code Standard Table

[0060]

[0061] From the experimental results, it can be seen that the gel profile control agent particles of Example 1 can effectively withstand high temperatures and harsh high-salt environments, and still possess CO 2 and temperature response, and after 45 days of aging, they still remain elastic and do not degrade.

[0062] Experimental Example 3

[0063] Swelling test at different salinities: Take the profile control agent particles of Examples 1-3 and put them into a pressure-resistant bottle, and add 40 mL of mineralized water with different salinities (5×10 4 mg / L, 10×10 4 mg / L, 15×10 4 mg / L, 22×10 4 mg / L). Except for the mineralized water pointed out in Table 1, the other mineralized waters only contain monovalent ions. Put them into an aging oven at 70°C for swelling performance comparison. The results are shown in Tables 4-6. The comparison before and after swelling of Example 1 can be seen in Figure 3 and Figure 4 .

[0064] Table 4 Swelling Comparison Test of Example 1 at Different Salinities at 70°C

[0065] Total Dissolved Solids (mg / L) <![CDATA[5×10 4 > <![CDATA[10×10 4 > <![CDATA[15×10 4 > <![CDATA[22×10 4 > Swelling Ratio (g / g) 28.62 31.16 33.81 35.02

[0066] Table 5 Swelling Comparison Test of Example 2 at Different Salinities at 70°C

[0067] Total Dissolved Solids (mg / L) <![CDATA[5×10 4 > <![CDATA[10×10 4 > <![CDATA[15×10 4 > <![CDATA[22×10 4 > Swelling Ratio (g / g) 28.83 32.52 34.98 36.59

[0068] Table 6 Swelling Comparison Test of Example 3 at Different Salinities at 70°C

[0069] Total Dissolved Solids (mg / L) <![CDATA[5×10 4 > <![CDATA[10×10 4 > <![CDATA[15×10 4 > <![CDATA[22×10 4 > Swelling Ratio (g / g) 27.58 29.85 33.52 34.82

[0070] At the same time, take the particles of Comparative Example 1, Comparative Example 2, and Comparative Example 3 for the same-condition comparison test to illustrate the swelling of the profile control agent particles of the present invention and the particles of the comparative examples at different salinities and compare their salt tolerance. The results are shown in Tables 7, 8, and 9. Table 7 Swelling Comparison Test of Comparative Example 1 at Different Salinities at 70°C

[0071] Total Dissolved Solids (mg / L) <![CDATA[5×10 4 > <![CDATA[10×10 4 > <![CDATA[15×10 4 > <![CDATA[22×10 4 > Swelling Ratio (g / g) 21.98 21.26 19.96 18.59

[0072] Table 8 Swelling Comparison Test of Comparative Example 2 at Different Salinities at 70°C

[0073] Total Dissolved Solids (mg / L) <![CDATA[5×10 4 > <![CDATA[10×10 4 > <![CDATA[15×10 4 > <![CDATA[22×10 4 > Swelling Ratio (g / g) 19.81 18.96 17.08 15.78

[0074] Table 9 Comparative Example 3 Swelling Comparison Test at Different Salinities at 70°C

[0075] Total Dissolved Solids (mg / L) <![CDATA[5×10 4 > <![CDATA[10×10 4 > <![CDATA[15×10 4 > <![CDATA[22×10 4 > Swelling Ratio (g / g) 14.57 14.06 13.67 12.59

[0076] It can also be seen from the swelling test results of each sample at different salinities that the profile control agent of the hydrogel prepared by the present invention has more significant temperature and salt tolerance than the profile control agents of Comparative Examples 1-3, and has better swelling performance in saline water. As the salinity increases, the swelling ratios of Examples 1-3 show an overall upward trend, and the swelling performance is also good under the condition of high salinity water of 220,000 mg / L; while the swelling ratios of Comparative Examples 1-3 show a gradually decreasing trend and cannot tolerate high salinity water.

[0077] Experimental Example 4

[0078] The plugging performance of the profile control agent particles of Example 1 was tested through a core displacement experiment: the core parameters used are shown in Table 10, and the experimental conditions are as follows: the injection pressure is ensured to be higher than 4.5 MPa through a back pressure regulator, the injection rate is 1.5 mL / min, the experimental temperature is room temperature, and the mesh number of the profile control agent particles is 20-40 mesh. To control variables, the core displacement experiments before and after the particle response were carried out in the same core, and the results are as Figure 5 shown. In the core displacement experiment, the displacement pressure difference of the particles after response is significantly increased compared with that before response.

[0079] Table 10 Basic Core Parameters

[0080]

[0081] The above is only a preferred embodiment of the present invention, and it does not impose any form of limitation on the present invention. Although the present invention has been disclosed above with a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to make equivalent embodiments with equivalent changes within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a temperature / CO2 dual-responsive zwitterionic hydrogel profile control agent, characterized in that: Monomer A, monomer B and monomer C are used as raw materials, crosslinking agent and initiator are added, and polymerization reaction is carried out in water medium; The monomer A is selected from any one of acrylamide, acrylic acid, and 1-vinyl-2-pyrrolidone; The monomer B is selected from any one of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, 2-methacryloyloxyethyl phosphorylcholine, and 3-((2-(methacryloyloxy)ethyl)dimethylamino)propionic acid inner salt; The monomer C is selected from any one of 2-(dimethylamino)ethyl methacrylate, dimethylaminopropyl methacrylamide and polyethyleneimine.

2. The method for preparing the temperature / CO2 dual-responsive zwitterionic hydrogel profile control agent according to claim 1, characterized in that: The polymerization reaction temperature is 50-70°C for 10-15h.

3. The method for preparing the temperature / CO2 dual-responsive zwitterionic hydrogel profile control agent according to claim 1, characterized in that: The usage ratio of each raw material is as follows: Monomer A accounts for 10%-30% of the mass of water, monomer B accounts for 5-30% of the mass of monomer A, monomer C accounts for 20-40% of the mass of monomer A, crosslinking agent accounts for 0.5-1% of the mass of monomer A, and initiator accounts for 0.2%-2% of the total mass of the three monomers.

4. The method for preparing the temperature / CO2 dual-responsive zwitterionic hydrogel profile control agent according to claim 3, characterized in that: The crosslinking agent is selected from any one of N,N-methylenebisacrylamide, 1,6-hexanediol diacrylate and divinylbenzene.

5. The method for preparing the temperature / CO2 dual-responsive zwitterionic hydrogel profile control agent according to claim 3, characterized in that: The initiator is selected from any one of potassium persulfate, ammonium persulfate and sodium persulfate.

6. The method for preparing the temperature / CO2 dual-responsive zwitterionic hydrogel profile control agent according to claim 1, characterized in that: Here are the steps: Dissolve monomer A, monomer B and monomer C in water to prepare an aqueous solution, add a crosslinking agent, and disperse evenly in an ultrasonic instrument. After nitrogen is passed through to deoxygenate, add an initiator, stir evenly with a magnetic stirrer, and react at 50-70°C for 10-15h. After the reaction is completed, take out the product, cut, dry and crush it to obtain the target hydrogel profile control agent.

7. The method for preparing the temperature / CO2 dual-responsive zwitterionic hydrogel profile control agent according to claim 6, characterized in that: The polymerization reaction conditions were 60°C for 12 h.

8. A temperature / CO2 dual-responsive zwitterionic hydrogel profile control agent, characterized in that: Prepared by the preparation method according to any one of claims 1 to 7.

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