CO2-Responsive Anionic Multicopolymer Materials and Their Preparation Methods and Applications

Abstract

The present invention provides a CO2-responsive anionic multi-block copolymer material, a preparation method thereof and an application thereof. The material is prepared by first subjecting a Pluronic-type block polymer and a chain transfer agent to a reversible addition-fragmentation chain transfer esterification reaction to obtain a RAFT precursor polymer, then subjecting the RAFT precursor polymer to a first addition polymerization reaction with a perfluoroacrylate monomer, and finally subjecting the product of the first addition polymerization reaction to a second addition polymerization reaction with a monomer containing a propanesulfonic acid group; wherein the material includes a Pluronic polymer chain segment structure, a perfluorinated compound chain segment structure and a propanesulfonic acid chain segment structure. The material provided by the present invention is an anionic multi-block copolymer material with adjustable hydrophilicity, lipophilicity and CO2 affinity. The CO2-water-based microfoam and CO2-oil-based microfoam formed thereby have excellent stability under tight sandstone, and at the same time, it has anionic properties, thereby enhancing its colloidal stability in oil.

Description

Technical Field

[0001] The present invention relates to a CO2-responsive anionic multi-component copolymer material, a preparation method thereof and an application thereof, and belongs to the technical field of CCUS-EOR integration technology for oil exploitation and CO2 storage. Background Art

[0002] The contradiction between oil and gas supply and demand in China is becoming increasingly large. The external dependence on oil has exceeded 70%, far higher than the warning line set by the International Energy Agency, and the energy security situation is very serious. How to achieve carbon emission reduction while increasing crude oil production is an inherent requirement for China's energy security and economic transformation, and also an inevitable choice for the development of the oil industry. At the same time, under the background of the current demand for carbon capture, utilization and storage (CCUS) technology, how to combine oil and gas exploitation with CCUS technology has become a new trend. In recent years, low-permeability oil reservoirs have become an important replacement resource for the Chinese oil industry. A large number of studies and practices have shown that supercritical carbon dioxide (scCO2) flooding is not only an effective way to improve oil recovery in such reservoirs, but also can form an integrated CCUS-EOR technology of CO2 flooding and storage in the form of structural, bound, dissolved and mineralized storage in the reservoir. It is an important technology for CCUS to achieve the dual goals of increasing oil production and reducing emissions, and has broad application prospects.

[0003] According to the oil displacement method, the scCO2 flooding of low-permeability tight oil reservoirs used in China mainly uses CO2 miscible flooding technology, supplemented by CO2 immiscible flooding, and at the same time supplemented by water alternating gas (WAG) technology. Generally, it is considered that miscible flooding occurs when the formation pressure is greater than the minimum miscibility pressure, and immiscible flooding occurs when it is less than the minimum miscibility pressure. For example, Chinese Patent Application CN108798614A proposes a method for determining the miscibility degree of CO2 flooding and predicts its oil displacement effect. When CO2 miscible floods, when the crude oil and CO2 reach miscibility, the viscosity ratio of the crude oil and CO2 is greatly reduced, thereby improving the oil displacement efficiency. Generally, the miscible flooding effect is better than the immiscible flooding. Abroad, CO2 flooding mainly uses miscible flooding, with very few immiscible flooding projects.

[0004] However, due to the problem of CO2 precipitation during the migration process, there are generally problems such as low oil displacement efficiency, gas channeling, and viscous fingering in scCO2 flooding. After CO2 enters the formation in a liquid state, most of the CO2 forms a supercritical fluid state and enters the matrix. However, due to environmental factors such as formation temperature changes and formation water salinity, some CO2 will precipitate in the form of gas from the scCO2 flow. The precipitated CO2 cannot enter the matrix at the micro-nano scale and will also form a gas lock in the pore channels to block the subsequent supercritical flow from entering the matrix, thus greatly hindering the CO2 oil displacement efficiency. Regarding gas channeling, Chinese patent application CN111139051A provides a preparation and application method of a CO2 foam plugging agent, which uses the precipitated CO2 to form CO2 foam with a certain strength to plug the large pore channels, maintain the reservoir pressure, and improve the sweep coefficient of scCO2. Specifically, quaternary ammonium salt-type imidazoline molecules and hydroxyethyl cellulose molecules are used to form high-strength foam with CO2 to achieve the purpose of plugging large pore channels. This type of technology intends to use the emulsification method to form water-based foam after a large amount of CO2 precipitates to achieve the purpose of plugging channels. However, it is more difficult for CO2 to enter the matrix after precipitation and form a gas lock in the micro-nano size pores of the matrix, which has a greater impact on scCO2 oil displacement. And currently, there is no good solution to the gas lock formed by the prematurely precipitated CO2 in the micro-nano pores.

[0005] Based on the development principle of high efficiency and low cost, it is urgently necessary to adopt manual control means to effectively prevent and control the CO2 precipitation in the scCO2 flow. At present, most of the research focuses on using the precipitated CO2 to form microfoams with oil and water to achieve the purpose of eliminating the precipitated gas and enhancing oil recovery. Based on this idea, technicians in this field have developed functional surfactants with CO2 affinity, which are mainly divided into oil-soluble surfactants and water-soluble surfactants. For example, Chinese Patent Application CN110317598A and Chinese Patent Application CN114876425A respectively provide two water-soluble surfactants applicable in scCO2 and WAG technologies. The agents used are wettability improvers such as sodium lauryl polyoxyethylene ether sulfate and sodium α-olefin sulfonate, and CO2-philic high molecular polymers such as polyvinylpyrrolidone, in order to further efficiently utilize the precipitated CO2 to form foam for oil displacement. Chinese Patent Application CN111909679A provides an oil-soluble surfactant, aiming to reduce the minimum miscibility pressure of CO2 and crude oil to reduce the CO2 precipitation amount and improve the oil displacement efficiency. However, due to the foam emulsification effect, this technology has the same problem as Technology 1, that is, the technology of using the precipitated CO2 to form CO2 foam with a certain strength to block large pores. These two methods are not applicable to the situation where a large amount of CO2 has already precipitated: ① The contact surface between the surfactant dissolved in oil or water and CO2 is too small, and the efficiency of forming foam is low; ② There is no external force (such as high-speed stirring, ultrasound) to form foam in the formation, and the micro forces such as capillary waves have limited effects. Therefore, when a large amount of CO2 precipitation has occurred, the effect of enhanced oil recovery measures is poor.

[0006] Inspired by the formation mechanism and application bottleneck of CO2 foam in low-permeability tight oil reservoirs, when CO2 is regulated before it precipitates from scCO2, so that the bubble size generated by the nucleation effect during its precipitation is controlled small enough (micro-nano scale) and evenly dispersed in scCO2 or aqueous solution (WAG technology), then while further improving the oil displacement effect of scCO2 or aqueous solution (WAG technology), theoretically, the harm caused by CO2 precipitation can be completely eliminated. To achieve this effect, in the context of CCUS, there is an urgent need to develop an intelligent surfactant with hydrophilicity, lipophilicity and CO2-philicity to precisely control the CO2 bubble size at the moment of CO2 precipitation, so as to solve the CO2 precipitation problem and further improve the integration effect of scCO2 oil displacement and CO2 sequestration. Summary of the Invention

[0007] In order to solve the above-mentioned disadvantages and deficiencies, an object of the present invention is to provide a CO2-responsive anionic multi-block copolymer material.

[0008] Another object of the present invention is also to provide a method for preparing the above-mentioned CO2-responsive anionic multi-block copolymer material.

[0009] Another object of the present invention is also to provide the application of the above-mentioned CO2-responsive anionic multi-block copolymer material in CO2 flooding.

[0010] To achieve the above objects, on the one hand, the present invention provides a CO2-responsive anionic multi-block copolymer material, wherein the CO2-responsive anionic multi-block copolymer material is prepared by first subjecting a Pluronic-type block polymer and a chain transfer agent to a reversible addition-fragmentation chain transfer esterification reaction to obtain a RAFT precursor polymer, then subjecting the RAFT precursor polymer to a first addition polymerization reaction with a perfluoroacrylate monomer, and finally subjecting the product of the first addition polymerization reaction to a second addition polymerization reaction with a monomer containing a propanesulfonic acid group;

[0011] Among them, the CO2-responsive anionic multi-block copolymer material includes a Pluronic polymer chain segment structure, a perfluorinated compound chain segment structure, and a propanesulfonic acid chain segment structure.

[0012] As a specific embodiment of the above-mentioned CO2-responsive anionic multi-block copolymer material of the present invention, the average molecular weight of the CO2-responsive anionic multi-block copolymer material is 5000 Da - 30000 Da.

[0013] As a specific embodiment of the above-mentioned CO2-responsive anionic multi-block copolymer material of the present invention, the Pluronic-type block polymer includes one or a combination of several of Pluronic P-123, Pluronic 17R4, Pluronic F-68, Pluronic F-127, Pluronic L-64, Pluronic P-103, and Pluronic L-121, etc.

[0014] As a specific embodiment of the above-mentioned CO2-responsive anionic multi-block copolymer material of the present invention, the chain transfer agent includes 4-cyano-4-(propylthio)pentanoic acid (CTPPA) and / or S-dodecyl-S'-(α,α'-dimethyl-α''-acetic acid) trithiocarbonate (DDMAT), etc.

[0015] As a specific embodiment of the above-mentioned CO2-responsive anionic multi-block copolymer material of the present invention, the perfluoroacrylate monomer includes 1H,1H,2H,2H-perfluorodecyl acrylate (FDA) and / or hexafluorobutyl methacrylate (HFBMA), etc.

[0016] As a specific embodiment of the above-mentioned CO2-responsive anionic multi-copolymer material of the present invention, among them, the propanesulfonic acid-containing monomers include one or a combination of several of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), modified lignosulfonate monomers, allyloxy sulfonate monomers, etc.

[0017] On the other hand, the present invention also provides a preparation method of the above-mentioned CO2-responsive anionic multi-copolymer material, among which, the preparation method includes:

[0018] Step 1: Dissolve Pluronic block polymer, chain transfer agent and esterification reaction catalyst in organic solvent A to make the Pluronic block polymer and the chain transfer agent undergo a reversible addition-fragmentation chain transfer esterification reaction to obtain a RAFT precursor polymer; among them, based on the total weight of the raw materials (including organic solvent A) in Step 1 being 100%, the dosage of the Pluronic block polymer is 5-15%, the dosage of the chain transfer agent is 0.5-2%, and the dosage of the esterification reaction catalyst is 0.6-1.2%;

[0019] Step 2: Disperse the RAFT precursor polymer, perfluoroacrylate monomer, initiator and emulsifier in organic solvent B and carry out a first addition polymerization reaction; among them, based on the total weight of the raw materials (including organic solvent B) in Step 2 being 100%, the dosage of the RAFT precursor polymer is 2-8%, the dosage of the perfluoroacrylate monomer is 4-15%, the dosage of the initiator is 0.05-0.15%, and the dosage of the emulsifier is 2-15%;

[0020] Step 3: Disperse the first addition polymerization product, propanesulfonic acid-containing monomers, initiator and emulsifier in organic solvent B and carry out a second addition polymerization reaction. After the reaction, a CO2-responsive anionic multi-copolymer material is obtained; among them, based on the total weight of the raw materials (including organic solvent B) in Step 3 being 100%, the dosage of the first addition polymerization product is 1-10%, the dosage of the propanesulfonic acid-containing monomers is 2-10%, the dosage of the initiator is 0.05-0.2%, and the dosage of the emulsifier is 2-15%.

[0021] The present invention first uses a Pluronic block polymer and a chain transfer agent as raw materials to obtain a RAFT precursor polymer through a reversible addition-fragmentation chain transfer reaction (RAFT), and uses it as a grafting body. Then, using perfluoroacrylate monomers and propanesulfonic acid-containing monomers as polymerization monomers, they are respectively subjected to stepwise addition polymerization reactions with the grafting body to prepare the CO2-responsive anionic multi-copolymer material. In actual preparation, the specific materials and dosages of each component can be determined within the scope defined by the claims according to actual needs, so as to precisely control the molar ratio and total chain length of each chain segment structure, etc.

[0022] As a specific embodiment of the above-described preparation method of the present invention, in step one, the reaction is carried out in a nitrogen atmosphere, and the reaction temperature is 50 - 80°C, preferably 65 - 75°C.

[0023] As a specific embodiment of the above-described preparation method of the present invention, in step one, the esterification reaction catalyst includes N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDAC) and / or 4-(dimethylamino)pyridine (DMAP), etc.

[0024] As a specific embodiment of the above-described preparation method of the present invention, in step one, the organic solvent A includes dichloromethane (DCM) or tetrahydrofuran (THF), etc.

[0025] As a specific embodiment of the above-described preparation method of the present invention, in step two, the first polyaddition reaction is carried out in a nitrogen atmosphere, the reaction temperature is 50 - 80°C, and the time is 2 - 10 h. Preferably, the reaction temperature is 75°C and the time is 10 h.

[0026] As a specific embodiment of the above-described preparation method of the present invention, in step three, the second polyaddition reaction is carried out in a nitrogen atmosphere, the reaction temperature is 50 - 80°C, and the time is 2 - 10 h. Preferably, the reaction temperature is 75°C and the time is 10 h.

[0027] As a specific embodiment of the above-described preparation method of the present invention, in steps two and three, the initiator includes 4,4-azobis(4-cyanovaleric acid) (ACPA) and / or azobisisobutyronitrile (AIBN), etc.

[0028] As a specific embodiment of the above-described preparation method of the present invention, in steps two and three, the emulsifier includes one or a combination of several of Triton X-45, Tergitol NP-4, Brij L-4, Brij 72, and Span80, etc.

[0029] As a specific embodiment of the above-described preparation method of the present invention, in steps two and three, the organic solvent B includes cyclohexane (cycC6) or tetrahydrofuran (THF), etc.

[0030] The chemical formulas of CTPPA, DDMAT, EDAC, DMAP, FDA, HFBMA, and AMPS used in the present invention are shown as follows;

[0031]

[0032] On the other hand, the present invention also provides the application of the above-mentioned CO2-responsive anionic multi-block copolymer material in CO2 flooding.

[0033] As a specific embodiment of the above application of the present invention, wherein the CO2 flooding is supercritical CO2 flooding.

[0034] As a specific embodiment of the above application of the present invention, wherein the supercritical CO2 flooding includes CO2 miscible flooding or WAG flooding.

[0035] During the application process, injecting scCO2 (CO2 miscible flooding technology) or injection water (WAG technology) containing the CO2-responsive anionic multi-block copolymer material into a low-permeability reservoir can regulate the microbubble size and colloidal stability when CO2 precipitates, so as to realize the free entry of CO2-water-based microbubbles at the micro-nano scale into the matrix and combine with crude oil to form CO2-oil-based microbubbles during supercritical CO2 flooding, thereby solving the problem of CO2 precipitation while further achieving the goal of integrating oil displacement and CO2 sequestration.

[0036] Compared with the prior art, the beneficial technical effects that can be achieved by the CO2-responsive anionic multi-block copolymer material provided by the present invention include:

[0037] (1) The CO2-responsive anionic multi-block copolymer material provided by the present invention has a Pluronic polymer chain segment structure, a perfluorinated compound chain segment structure, and a propanesulfonic acid chain segment structure at the same time. Among them, the Pluronic polymer chain segment structure has a hydrophilic group (EO) and a lipophilic group (PO), and the lipophilicity and hydrophilicity and the oil-water selectivity of the CO2-responsive anionic multi-block copolymer material can be regulated by adjusting the EO / PO ratio; the perfluorinated compound chain segment structure has the characteristics of being hydrophobic to both oil and water with a CO2-philic group, can fully capture CO2 in the solution to form stable micro-nano scale foams, and there is no chemical reaction in the formation process of the CO2-water-based microbubbles and CO2-oil-based microbubbles and the transformation process between the two kinds of foams, which is a reversible process; in addition to assisting in regulating the hydrophilicity of the CO2-responsive anionic multi-block copolymer material, the propanesulfonic acid chain segment structure can also improve its temperature and salinity tolerance. Therefore, the CO2-responsive anionic multi-block copolymer material provided by the present invention is an anionic multi-block copolymer material with adjustable hydrophilicity, lipophilicity, and CO2-philic properties, and the CO2-water-based microbubbles and CO2-oil-based microbubbles formed by it have excellent stability. At the same time, it has anionic properties, which can enhance its colloidal stability in water, and these two stabilities will promote the transformation between CO2-water-based microbubbles and CO2-oil-based microbubbles.

[0038] (2) The CO2-responsive anionic multi-copolymer material provided by the present invention is used for CO2 miscible flooding or WAG flooding. The CO2-responsive anionic multi-copolymer material can enter the formation with scCO2 or the injected water, and during this period, it presents outer surface structures with different affinities, such as Figure 4a and Figure 4b shown.

[0039] (3) When preparing the CO2-responsive anionic multi-copolymer material provided by the present invention, by selecting Pluronic block polymer with different molecular weights and different EO / PO ratios, the obtained CO2-responsive anionic multi-copolymer material can have the "first lipophilic and then hydrophilic" characteristics required for CO2 flooding, as shown in Table 3 and Figure 5 shown. During the supercritical CO2 injection process, the CO2-responsive anionic multi-copolymer material can capture micro-nano scale CO2 bubbles during the CO2 nucleation process, and form CO2-aqueous microfoams with the precipitated CO2 and then enter the matrix. When the CO2-aqueous microfoams in the matrix encounter crude oil, there will be a "first lipophilic and then hydrophilic" preferential lipophilic selectivity, enabling them to preferentially combine with crude oil to form CO2-oil-based microfoams, completing the transformation from CO2-aqueous microfoams to CO2-oil-based (light alkane) microfoams, enhancing the oil displacement ability. At the same time, this process also enables the precipitated CO2 to enter the matrix containing residual oil, further solving the problem of CO2 precipitation, that is, the CO2-responsive anionic multi-copolymer material provided by the present invention can control CO2 precipitation in a relatively harsh reservoir environment. After the residual oil is completely recovered, the CO2-aqueous microfoams accumulate and disintegrate in the matrix, and the CO2 is sealed in the matrix, further enhancing the effect of CO2 displacing crude oil in the matrix.

[0040] (4) The CO2-responsive anionic multi-copolymer material provided by the present invention is a CO2-sensitive responsive multi-copolymer, which can form micro-nano scale CO2-aqueous microfoams and CO2-oil-based (light alkane) microfoams simultaneously in a relatively harsh complex reservoir environment. After being dissolved in supercritical CO2, it can increase the viscosity of the supercritical CO2 solution to 1.9 mPa·s. Description of the Drawings

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0042] Figure 1 It is the flow chart for preparing the CO2-responsive anionic multi-copolymer material in Embodiment 1 of the present invention.

[0043] Figure 2 This is the infrared spectrum of the CO₂-responsive anionic multi-component copolymer material prepared in Example 1 of the present invention.

[0044] Figure 3 This is a relationship diagram between different concentrations of the CO₂-responsive anionic multi-component copolymer material provided in Example 2 in supercritical CO₂ and the viscosity of the resulting system in Test Example 2 of the present invention.

[0045] Figure 4a This is a schematic diagram of the oil-water selectivity principle when the CO₂-responsive anionic multi-component copolymer material provided by the present invention is used for CO₂ miscible flooding.

[0046] Figure 4b This is a schematic diagram of the oil-water selectivity principle when the CO₂-responsive anionic multi-component copolymer material provided by the present invention is used for WAG flooding.

[0047] Figure 5 This is a schematic diagram of the formation and transfer of microfoams of the CO₂-responsive anionic multi-component copolymer material provided by the present invention.

[0048] Figure 6 This is a comparison of the CO₂ foam stability performance of the CO₂-responsive anionic multi-component copolymer material prepared in Example 1 of the present invention and the copolymer materials provided in Comparative Examples 2 - 3 in water.

[0049] Figure 7 This is a comparison of the CO₂ foam stability performance of the CO₂-responsive anionic multi-component copolymer material prepared in Example 1 of the present invention and the copolymer materials provided in Comparative Examples 2 - 3 in oil. Detailed implementation manners

[0050] It should be noted that the term "including" and any variations thereof in the description and claims of the present invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products or devices.

[0051] The "ranges" disclosed in the present invention are given in the form of a lower limit and an upper limit. There can be one or more lower limits, and one or more upper limits respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower limit and upper limit define the boundaries of a particular range. All ranges defined in this way are combinable, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. Additionally, if the minimum range values listed are 1 and 2, and the maximum range values listed are 3, 4, and 5, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5.

[0052] In the present invention, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where both a and b are real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" are fully listed in the present invention, and "0 - 5" is just an abbreviated representation of these numerical combinations.

[0053] In the present invention, if there is no special instruction, all embodiments and preferred embodiments mentioned in the present invention can be combined with each other to form a new technical solution.

[0054] In the present invention, if there is no special instruction, all technical features and preferred features mentioned in the present invention can be combined with each other to form a new technical solution.

[0055] In the present invention, if not specifically pointed out, the term "two kinds" used in this specification means "at least two kinds".

[0056] In the present invention, if there is no special instruction, all steps mentioned herein can be carried out sequentially or randomly, but preferably sequentially. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out sequentially, or can also include steps (b) and (a) carried out sequentially. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b), and (c), or can also include steps (a), (c), and (b), or can also include steps (c), (a), and (b), etc.

[0057] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the attached table, drawings and examples. The following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention. If the specific conditions are not specified in the embodiments, they are carried out according to the normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0058] Example 1

[0059] This embodiment provides a CO2 responsive anionic multipolymer material, wherein the CO2 responsive anionic multipolymer material is prepared by a preparation method comprising the following specific steps:

[0060] Step 1: Take a 50 mL three-necked flask, add 2.12 g of Pluronic P-123 block polymer, 0.4 g of CTPPA and 0.265 g of EDAC into 24 mL of DCM, stir and disperse them thoroughly, heat at 65° C. under nitrogen protection to carry out esterification reaction, and prepare a RAFT precursor polymer after the reaction is completed. Dry the RAFT precursor polymer for later use.

[0061] Step 2: Take another 100mL three-necked flask, add 3g of the RAFT precursor polymer prepared in step 1, 9g of FDA, 0.06g of ACPA and 6g of Triton X-45 to 60mL of cycC6 solvent, and react at 75°C and 100rpm stirring speed for 8 hours (nitrogen protection). After the reaction, the prepared solid is separated and dried for later use.

[0062] Step 3: Add 3.5 g of the solid prepared in step 2, 6 g of AMPS, 0.1 g of ACPA and 6 g of TritonX-45 to 60 mL of cycC6 solvent, and react at 75 ° C. and 100 rpm stirring speed for 10 hours (nitrogen protection). After the reaction, the prepared solid is separated and dried to obtain the CO2 responsive anionic multipolymer material, whose molecular weight is 10000-20000 Da. The brief process of the preparation process is as follows Figure 1 shown.

[0063] Example 2

[0064] This embodiment provides a CO₂-responsive anionic multi-block copolymer material. Among them, the CO₂-responsive anionic multi-block copolymer material is prepared by a preparation method including the following specific steps:

[0065] Step 1: Take a 50 mL three-necked flask, add 2.12 g of Pluronic 17R4 block polymer, 0.48 g of CTPPA, and 0.38 g of DMAP to 24 mL of DCM, stir and disperse thoroughly, and carry out an esterification reaction by heating at 65 °C under nitrogen protection. After the reaction is completed, a RAFT precursor polymer is prepared. Dry the RAFT precursor polymer for later use.

[0066] Step 2: Take another 100 mL three-necked flask, add 4.8 g of the RAFT precursor polymer prepared in Step 1, 9 g of FDA, 0.06 g of ACPA, 7.2 g of Triton X-45, and 1.2 g of Span80 to 60 mL of cycC6 solvent, and react at 75 °C and a stirring speed of 100 rpm for 8 hours (under nitrogen protection). After the reaction is completed, separate and dry the prepared solid for later use.

[0067] Step 3: Add 3.6 g of the solid prepared in Step 2, 6 g of AMPS, 0.09 g of ACPA, 6 g of Triton X-45, and 1.2 g of Span80 to 60 mL of cycC6 solvent, and react at 75 °C and a stirring speed of 100 rpm for 10 hours (under nitrogen protection). After the reaction is completed, separate and dry the prepared solid to obtain the CO₂-responsive anionic multi-block copolymer material. The molecular weight of this CO₂-responsive anionic multi-block copolymer material is 10,000 - 20,000 Da.

[0068] Example 3

[0069] This embodiment provides a CO₂-responsive anionic multi-block copolymer material. Among them, the CO₂-responsive anionic multi-block copolymer material is prepared by a preparation method including the following specific steps:

[0070] Step 1: Take a 50 mL three-necked flask, add 2.12 g of Pluronic F-127 block polymer, 0.2 g of CTPPA, and 0.38 g of DMAP to 24 mL of DCM, stir and disperse thoroughly, and carry out an esterification reaction by heating at 75 °C under nitrogen protection. After the reaction is completed, a RAFT precursor polymer is prepared. Dry the RAFT precursor polymer for later use.

[0071] Step 2: Take another 250mL three-necked flask, add 4.5g of the RAFT precursor polymer prepared in step 1, 7.2g of FDA, 0.16g of AIBN, 5.4g of Brij L-4 and 3.6g of Span80 into 180mL of THF solvent, and react at 75°C and 150rpm stirring speed for 10 hours (nitrogen protection). After the reaction, separate and dry the prepared solid for later use.

[0072] Step 3: Add 11g of the solid prepared in step 2, 14g of AMPS, 0.18g of AIBN, 5.4g of Brij L-4 and 4.5g of Span80 to 180mL of THF solvent, and react at 75°C and 150rpm stirring speed for 10 hours (nitrogen protection). After the reaction, separate and dry the prepared solid to obtain the CO2 responsive anionic multipolymer material, and the molecular weight of the CO2 responsive anionic multipolymer material is 15000-30000Da.

[0073] Example 4

[0074] This embodiment provides a CO2 responsive anionic multipolymer material, wherein the CO2 responsive anionic multipolymer material is prepared by a preparation method comprising the following specific steps:

[0075] Step 1: Take a 50mL three-necked flask, add 3.8g of Pluronic P-123 block polymer, 1.13g of CTPPA and 0.6g of EDAC into 50mL of DCM, stir and disperse them thoroughly, heat at 65°C under nitrogen protection for esterification reaction, and prepare RAFT precursor polymer after the reaction is completed. Dry the RAFT precursor polymer for later use.

[0076] Step 2: Take another 100mL three-necked flask, add 8g of the RAFT precursor polymer prepared in step 1, 7g of FDA, 0.1g of ACPA and 10g of Triton X-45 to 100mL of cycC6 solvent, and react at 75°C and 100rpm stirring speed for 8 hours (nitrogen protection). After the reaction, separate and dry the prepared solid for later use.

[0077] Step 3: Add 6 g of the solid prepared in step 2, 8 g of AMPS, 0.09 g of ACPA, 10 g of TritonX-45 and 2 g of Span80 to 100 mL of cycC6 solvent, and react at 75°C and 100 rpm stirring speed for 10 hours (nitrogen protection). After the reaction, the prepared solid is separated and dried to obtain the CO2-responsive anionic multipolymer material with a molecular weight of 15,000-30,000 Da.

[0078] Example 5

[0079] This embodiment provides a CO2 responsive anionic multipolymer material, wherein the CO2 responsive anionic multipolymer material is prepared by a preparation method comprising the following specific steps:

[0080] Step 1: Take a 50 mL three-necked flask, add 4.0 g of Pluronic 17R4 block polymer, 0.99 g of CTPPA and 0.66 g of DMAP into 50 mL of DCM, stir and disperse them thoroughly, heat at 65° C. under nitrogen protection for esterification reaction, and prepare a RAFT precursor polymer after the reaction is completed. Dry the RAFT precursor polymer for later use.

[0081] Step 2: Take another 100mL three-necked flask, add 8g of the RAFT precursor polymer prepared in step 1, 12g of FDA, 0.1g of ACPA, 12g of Triton X-45 and 2g of Span80 to 100mL of cycC6 solvent, and react at 75°C and 100rpm stirring speed for 8 hours (nitrogen protection). After the reaction, separate and dry the prepared solid for later use.

[0082] Step 3: Add 6 g of the solid prepared in step 2, 10 g of AMPS, 0.11 g of ACPA, 10 g of Triton X-45 and 2 g of Span80 to 100 mL of cycC6 solvent, and react at 75 ° C and 100 rpm stirring speed for 10 hours (nitrogen protection). After the reaction, the prepared solid is separated and dried to obtain the CO2 responsive anionic multipolymer material with a molecular weight of 5000-15000 Da.

[0083] Example 6

[0084] This embodiment provides a CO2 responsive anionic multipolymer material, wherein the CO2 responsive anionic multipolymer material is prepared by a preparation method comprising the following specific steps:

[0085] Step 1: Take a 50 mL three-necked flask, add 7 g of Pluronic F-127 block polymer, 1.5 g of DDMAT, and 1 g of DMAP to 100 mL of DCM, stir and disperse well, and carry out an esterification reaction at 75 °C under nitrogen protection. After the reaction, the RAFT precursor polymer is prepared. Dry the RAFT precursor polymer for later use.

[0086] Step 2: Take another 250 mL three-necked flask, add 4 g of the RAFT precursor polymer prepared in Step 1, 7 g of HFBMA, 0.1 g of AIBN, 6 g of Brij L-4, and 3 g of Span80 to 100 mL of THF solvent, and react at 75 °C and a stirring speed of 150 rpm for 10 hours (under nitrogen protection). After the reaction, separate and dry the prepared solid for later use.

[0087] Step 3: Add 6 g of the solid prepared in Step 2, 9 g of AMPS, 0.1 g of AIBN, 6 g of Brij L-4, and 2.5 g of Span80 to 100 mL of cycC6 solvent, and react at 75 °C and a stirring speed of 150 rpm for 10 hours (under nitrogen protection). After the reaction, separate and dry the prepared solid to obtain the CO2-responsive anionic multi-copolymer material, whose molecular weight is 15000 - 30000 Da.

[0088] Example 7

[0089] This example provides a CO2-responsive anionic multi-copolymer material, and the difference in its preparation method from Example 1 is only that:

[0090] Pluronic F-127 block polymer is used in Step 1.

[0091] Example 8

[0092] This example provides a CO2-responsive anionic multi-copolymer material, and the difference in its preparation method from Example 1 is only that:

[0093] Pluronic L-64 block polymer is used in Step 1.

[0094] Example 9

[0095] This example provides a CO2-responsive anionic multi-copolymer material, and the difference in its preparation method from Example 1 is only that:

[0096] Pluronic P-103 block polymer is used in Step 1.

[0097] Comparative Example 1

[0098] This comparative example provides a CO2 thickener, which is obtained by a polymerization reaction of the following polymerization monomers under the action of an initiator. The molecular weight of this CO2 thickener is 5000 - 10000 Da:

[0099] Polymerization monomer: FDA (dispersed in THF solvent at a mass concentration of 5%);

[0100] Initiator: AIBN, with a dosage of 0.5% of the total molar amount of the polymerization monomers;

[0101] The temperature of the polymerization reaction is 65 °C, and the reaction time is 24 hours.

[0102] Comparative Example 2

[0103] This comparative example provides a CO2-responsive copolymer, wherein the CO2-responsive copolymerization is prepared by a preparation method including the following specific steps:

[0104] Step 1: Take a 50 mL three-necked flask, add 2.12 g of Pluronic P-123 block polymer, 0.4 g of CTPPA, and 0.265 g of EDAC to 24 mL of DCM, stir and disperse thoroughly, and heat at 65 °C under nitrogen protection for an esterification reaction. After the reaction is completed, prepare the RAFT precursor polymer. Dry the RAFT precursor polymer for later use.

[0105] Step 2: Take another 100 mL three-necked flask, add 3 g of the RAFT precursor polymer prepared in Step 1, 9 g of FDA, 0.06 g of ACPA, and 6 g of Triton X-45 to 60 mL of cycC6 solvent, react at 75 °C and a stirring speed of 100 rpm for 8 hours (under nitrogen protection). After the reaction is completed, separate and dry the prepared solid to obtain the CO2-responsive copolymer, whose molecular weight is 5000 - 15000 Da.

[0106] Comparative Example 3

[0107] This comparative example provides a CO2-responsive copolymer, wherein the CO2-responsive copolymerization is prepared by a preparation method including the following specific steps:

[0108] Step 1: Take a 50 mL three-necked flask, add 2.12 g of Pluronic P-123 block polymer, 0.4 g of CTPPA, and 0.265 g of EDAC to 24 mL of DCM, stir and disperse thoroughly, and heat at 65 °C under nitrogen protection for an esterification reaction. After the reaction is completed, prepare the RAFT precursor polymer. Dry the RAFT precursor polymer for later use.

[0109] Step 2: Add 3.5 g of the solid prepared in Step 1, 6 g of AMPS, 0.6 g of ACPA, and 6 g of TritonX-45 into 60 mL of cycC6 solvent, react at 75 °C with a stirring speed of 100 rpm for 10 hours (under nitrogen protection). After the reaction, separate and dry the prepared solid to obtain the CO2-responsive copolymer with a molecular weight of 5000 - 17000 Da.

[0110] Test Example 1

[0111] In this test example, first, the CO2-responsive anionic multi-copolymer material prepared in Example 1 was pressed into a tablet with KBr, and then its functional groups were analyzed using a Nicolet Nexus 570 infrared spectrometer. The obtained infrared spectrum is as Figure 2 shown. As can be seen from Figure 2 , the peak at 2922 cm -1 is the vibration peak of the C-H bond of methyl and methylene groups, and the peak at 2852 cm -1 is the stretching vibration peak of the C-N bond; the peaks at 1731 cm -1 and 1374 cm -1 are the stretching vibration peaks of the C=O and C-O bonds respectively; the peak at 869 cm -1 is the vibration peak of the C-F bond; the peak at 1177 cm -1 is the stretching vibration peak of the ester group.

[0112] From the infrared analysis results, it can be known that in Example 1 of the present invention, the FDA and AMPS monomers were successfully grafted onto the PEO-b-PPO block polymer, that is, the RAFT precursor polymer, through addition polymerization, thus obtaining the CO2-responsive anionic multi-copolymer material.

[0113] Test Example 2

[0114] In this test example, first, the CO2-responsive anionic multi-copolymer materials provided in Examples 1 - 2 and the CO2 thickener provided in Comparative Example 1 were respectively dissolved uniformly in supercritical CO2 at a temperature of 45 °C, and then the cloud point pressure, viscosity, and solubility (i.e., the dissolved mass of the CO2 thickener in 100 g of supercritical CO2) were measured using a high-temperature and high-pressure viscometer. The obtained experimental data are shown in Table 1 below.

[0115] In addition, this test example also investigated the relationship between the different concentrations of the CO2-responsive anionic multi-copolymer material provided in Example 2 in supercritical CO2 and the viscosity of the obtained system. The relationship between the viscosity and the concentration of the CO2-responsive anionic multi-copolymer material is as Figure 3 shown.

[0116] This test example also measured the dissolution amount of the CO2-responsive anionic multi-component copolymer materials provided in Examples 1-2 in deionized water (i.e., the dissolved mass of the CO2-responsive anionic multi-component copolymer material in 100 g of deionized water) under the temperature condition of 45°C respectively. The experimental data obtained are shown in Table 2 below.

[0117] Table 1

[0118] Cloud point pressure / MPa Viscosity / mPa·s Solubility % Example 1 14 1.9±0.1 1.5 Example 2 14.5 2.3±0.1 1.2 Comparative Example 1 9 0.2 1.1

[0119] Table 2

[0120] Dissolution amount / % Example 1 0.9 Example 2 0.5

[0121] From the above Tables 1-2 and Figure 3 it can be seen that dissolving the CO2-responsive anionic multi-component copolymer materials provided in Examples 1 and 2 of the present invention in supercritical CO2 can increase the viscosities of the supercritical CO2 solutions to 1.9 mPa·s and 2.3 mPa·s respectively, while the viscosity of the CO2 thickener provided in Comparative Example 1 dissolved in supercritical CO2 is only 0.2 mPa·s. At the same time, the solubilities of the CO2-responsive anionic multi-component copolymer materials provided in Examples 1 and 2 dissolved in supercritical CO2 are 1.5% and 1.2% respectively, and the solubilities in deionized water are 0.9% and 0.5% respectively.

[0122] Test Example 3

[0123] This test example measured the CMC values and the wetting angles in kerosene of the CO2-responsive anionic multi-component copolymer materials provided in Examples 1 and 7-9 respectively by using the existing conventional methods in the art. The experimental data obtained in this test example are shown in Table 3 below.

[0124] Table 3

[0125]

[0126] It can be seen from the experimental data in Table 3 above that both the molecular weight of the Pluronic block polymer and the ratio of the lipophilic functional group to the hydrophilic functional group have an impact on the CMC value and the wetting angle of the CO2-responsive anionic multi-component copolymer material prepared in the present invention. The general trend shows that the larger the molecular weight, the greater the solubility in water; the larger the proportion of the PO functional group, the stronger the lipophilicity. Therefore, the present invention can make the obtained CO2-responsive anionic multi-component copolymer material have the "lipophilic first and then hydrophilic" characteristics required for CO2 enhanced oil recovery by screening Pluronic block polymers and adjusting the raw material dosage.

[0127] Test Example 4

[0128] In this test example, the copolymer materials provided in Example 1, Comparative Example 2, and Comparative Example 3 were first dissolved uniformly in deionized water and oil (a mixture of crude oil and diesel from the First Oil Production Plant of Changqing Oilfield in a volume ratio of 1:1) under the temperature condition of 45°C. Then, CO2 gas was introduced into them and saturated for 30 minutes. Next, a high-speed stirrer was used to stir at a speed of 12,400 rpm for 5 minutes. After standing, a Malvern Nano LAB laser particle size analyzer was used to measure the particle size of micro-nano foams. The obtained experimental data are as Figure 6 and Figure 7 shown. It can be seen from Figure 6 and Figure 7 that compared with the copolymer materials provided in Comparative Example 2 and Comparative Example 3, the foam stability of the CO2-responsive anionic multi-copolymer material provided in Example 1 of the present invention is better.

[0129] As described above, the above are only specific embodiments of the present invention and cannot be used to limit the scope of the invention. Therefore, the replacement of equivalent components or equivalent changes and modifications made according to the scope of protection of the present invention should still fall within the scope covered by this patent. In addition, the technical features in the present invention can be freely combined and used between technical features, between technical features and technical inventions, and between technical inventions.

Claims

1. A CO2-responsive anionic multi-copolymer material, characterized in that, The CO2-responsive anionic multi-block copolymer material is prepared by first subjecting a Pluronic-based block polymer to an esterification reaction with a reversible addition-fragmentation chain transfer agent to obtain a RAFT precursor polymer, then subjecting the RAFT precursor polymer to a first addition polymerization reaction with a perfluoroacrylate monomer, and finally subjecting the product of the first addition polymerization reaction to a second addition polymerization reaction with a propanesulfonic acid-containing monomer; Among them, the CO2-responsive anionic multi-block copolymer material includes a Pluronic polymer chain segment structure, a perfluorinated compound chain segment structure, and a propanesulfonic acid chain segment structure.

2. The CO2-responsive anionic multi-block copolymer material according to claim 1, wherein The average molecular weight of the CO2-responsive anionic multi-block copolymer material is 5000 Da - 30000 Da.

3. The CO2-responsive anionic multi-block copolymer material according to claim 1 or 2, characterized in that, The Pluronic-based block polymer includes one or a combination of several of Pluronic P-123, Pluronic 17R4, Pluronic F-68, Pluronic F-127, Pluronic L-64, Pluronic P-103, and Pluronic L-121.

4. The CO2-responsive anionic multi-block copolymer material according to claim 1 or 2, characterized in that, The reversible addition-fragmentation chain transfer agent includes 4-cyano-4-(propylthio)pentanoic acid and / or S-dodecyl-S'-(α,α'-dimethyl-α''-acetic acid)trithiocarbonate.

5. The CO2-responsive anionic multi-copolymer material according to claim 1 or 2, characterized in that, The perfluoroacrylate monomer includes 1H,1H,2H,2H-perfluorodecyl acrylate and / or hexafluorobutyl methacrylate.

6. The CO2-responsive anionic multi-copolymer material according to claim 1 or 2, characterized in that, The propanesulfonic acid-containing monomer includes one or a combination of several of 2-acrylamido-2-methylpropanesulfonic acid, a modified lignosulfonate monomer, and an allyloxy sulfonate monomer.

7. The preparation method of the CO2-responsive anionic multi-block copolymer material according to any one of claims 1-6, characterized in that, The preparation method includes: Step 1: Dissolve the Pluronic-based block polymer, the reversible addition-fragmentation chain transfer agent, and the esterification reaction catalyst in organic solvent A to subject the Pluronic-based block polymer to an esterification reaction with the reversible addition-fragmentation chain transfer agent to obtain a RAFT precursor polymer; among them, based on the total weight of the raw materials in Step 1 being 100%, the dosage of the Pluronic-based block polymer is 5 - 15%, the dosage of the reversible addition-fragmentation chain transfer agent is 0.5 - 2%, and the dosage of the esterification reaction catalyst is 0.6 - 1.2%; Step 2: Disperse the RAFT precursor polymer, the perfluoroacrylate monomer, the initiator, and the emulsifier in organic solvent B and carry out a first addition polymerization reaction; among them, based on the total weight of the raw materials in Step 2 being 100%, the dosage of the RAFT precursor polymer is 2 - 8%, the dosage of the perfluoroacrylate monomer is 4 - 15%, the dosage of the initiator is 0.05 - 0.15%, and the dosage of the emulsifier is 2 - 15%; Step 3: Disperse the primary polyaddition product, the propanesulfonic acid-containing monomer, the initiator, and the emulsifier in organic solvent B and conduct a secondary polyaddition reaction. After the reaction, a CO2-responsive anionic multi-component copolymer material is obtained. Among them, based on the total weight of the raw materials in Step 3 being 100%, the dosage of the primary polyaddition product is 1-10%, the dosage of the propanesulfonic acid-containing monomer is 2-10%, the dosage of the initiator is 0.05-0.2%, and the dosage of the emulsifier is 2-15%.

8. The preparation method according to claim 7, characterized in that, In Step 1, the reaction is carried out in a nitrogen atmosphere, and the reaction temperature is 50-80°C.

9. The preparation method according to claim 7 or 8, characterized in that, In Step 1, the esterification reaction catalyst includes N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride and / or 4-(dimethylamino)pyridine.

10. The preparation method according to claim 7 or 8, characterized in that, In Step 1, the organic solvent A includes dichloromethane or tetrahydrofuran.

11. The preparation method according to claim 7, characterized in that, In Step 2, the primary polyaddition reaction is carried out in a nitrogen atmosphere, the reaction temperature is 50-80°C, and the time is 2-10 h.

12. The preparation method according to claim 7, characterized in that, In Step 3, the secondary polyaddition reaction is carried out in a nitrogen atmosphere, the reaction temperature is 50-80°C, and the time is 2-10 h.

13. The preparation method according to any one of claims 7, 11 - 12, characterized in that, In Step 2 and Step 3, the initiator includes 4,4-azobis(4-cyanovaleric acid) and / or azobisisobutyronitrile.

14. The preparation method according to any one of claims 7, 11-12, characterized in that, In Step 2 and Step 3, the emulsifier includes one or a combination of several of Triton X-45, Tergitol NP-4, Brij L-4, Brij 72, and Span80.

15. The preparation method according to any one of claims 7, 11-12, characterized in that, In Step 2 and Step 3, the organic solvent B includes cyclohexane or tetrahydrofuran.

16. Application of the CO2-responsive anionic multi-component copolymer material according to any one of claims 1-6 in CO2 enhanced oil recovery.

17. The application according to claim 16, characterized in that, The CO2 enhanced oil recovery is supercritical CO2 enhanced oil recovery.

18. The application according to claim 17, wherein The supercritical CO2 enhanced oil recovery includes CO2 miscible flooding or WAG flooding.

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