Copolymer, preparation method therefor, and use thereof

Abstract

A copolymer, a preparation method therefor, and a use thereof. The copolymer contains an olefin backbone, and a sulfonic acid group, an acylamino group, an aminoacyl group, and a tertiary carbonate group, which are bonded to the olefin backbone. By means of a synergistic effect of these functional groups, the hydrolysis rates of the acylamino group and the aminoacyl group can be controlled, and precipitation is inhibited, thereby finally achieving a high hydrolysis rate. The copolymer can be used for profile control and flooding of a high-temperature high-salinity oil reservoir, especially a carbonate rock oil reservoir. The copolymer can be slowly hydrolyzed to release cross-linking sites in the oil reservoir environment, and the cross-linking sites released by hydrolysis can bind with a cross-linking agent to form a profile control and flooding system. After injection into the oil reservoir, initial low viscosity is achieved, and during migration, cross-linking groups are continuously released by means of slow hydrolysis, thereby achieving stepwise tackifying; in addition, the profile control and flooding system maintains certain viscosity and strength, so that deep profile control and flooding, flow channel adjustment, and long-lasting plugging are achieved.

Description

Copolymer and its preparation method and application

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application 202311541152.8 filed on November 17, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the technical field of petroleum extraction, in particular to a copolymer and a preparation method and application thereof. Background Art

[0004] Carbonate reservoirs are mainly fracture-cavity type. Due to their strong heterogeneity, water injection development of the reservoirs is prone to water channeling and low recovery rates. The fluid flow state in carbonate reservoirs is complex, with both seepage and pipe flow. Water channeling and flooding in dominant channels have long plagued oilfield production. Currently, the widely used flooding control technologies include flow control and plugging control. Flow control involves injecting flow control agents into water wells. The fluid to be injected needs to have low viscosity at the time of injection and high viscosity after reaching deep layers. Plugging control involves injecting high-strength plugging agents into oil wells. The fluid to be injected needs to maintain high strength for a long time after reaching deep layers.

[0005] Currently, the commonly used flow control agents and plugging control agents are mostly polymer gels. However, the carbonate reservoir environment is harsh. The temperature of China's carbonate reservoirs is mostly 110-160℃, and the salinity is ≥20×10 4 mg / L, calcium and magnesium ion content ≥1×10 4 The carbonate reservoirs in Abu Dhabi in the Middle East are mostly at temperatures of 115-139°C and have mineralizations of 15×10 4 -20×10 4 Existing gel polymers typically use acrylamide monomers as their primary building blocks. Rapid hydrolysis of the amide groups in the polymers in reservoir environments leads to precipitation when exposed to high calcium and magnesium ions. This causes a sharp drop in viscosity, making it difficult to achieve high viscosity at depth. Alternatively, the significant reduction in amide groups makes it difficult to form a high-strength gel, leading to rapid dehydration and failure of the gel, reducing its flow regulation or plugging control effectiveness.

[0006] Currently, the upper limits of temperature and salinity applicable to flow regulation or plugging gels are far lower than the application environment of carbonate salt reservoirs. Therefore, there is an urgent need to develop new polymers and gel flooding systems that are resistant to temperature, salt, and high calcium and magnesium ions to meet the flow regulation and plugging needs of carbonate reservoirs.

[0007] Summary of the Invention

[0008] The purpose of the present invention is to overcome the problems of the prior art in which the gel formed by the polymer quickly dehydrates and fails in the reservoir environment, making it difficult to achieve high viscosity in deep areas and having poor flow regulation or plugging effect, and to provide a copolymer and its preparation method and application.

[0009] In order to achieve the above object, the first aspect of the present invention provides a copolymer, which comprises a structural unit A shown in formula I, a structural unit B shown in formula II, a structural unit C shown in formula III and a structural unit D shown in formula IV;

[0010] Among them, R1, R7, R8 and R 11 Each is independently H or a C1-C6 alkyl group;

[0011] R2, R9 and R 10 Each is independently H or a C1-C6 alkyl group;

[0012] R3 and R4 are each independently a C1-C6 alkyl group;

[0013] R5 is a C1-C6 alkylene group; R6 is H or an alkali metal element;

[0014] R 12 、R 13 and R 14 are each independently a C1-C6 alkyl group, and R 12 、R 13 and R 14 At least one is a methyl group.

[0015] A second aspect of the present invention provides a copolymer comprising an olefin skeleton and functional groups bonded to the olefin skeleton, wherein the functional groups include sulfonic acid groups, tertiary carbonate groups, amide groups, and amino groups; wherein, based on the total weight of the copolymer, the weight content of the tertiary carbonate groups is 0.06-1.5 weight percent; the weight content of the sulfonic acid groups is not less than 21 weight percent; and the viscosity-average molecular weight of the copolymer is 5 million to 18 million.

[0016] A third aspect of the present invention provides a method for preparing a copolymer, the method comprising: polymerizing an olefinic monomer under solution polymerization conditions in the presence of an initiator; wherein the olefinic monomer comprises monomer A′ represented by formula 1, monomer B′ represented by formula 2, monomer C′ represented by formula 3, and monomer D′ represented by formula 4;

[0017] Among them, R1, R7, R8 and R 11 Each is independently H or a C1-C6 alkyl group;

[0018] R2, R9 and R10 Each is independently H or a C1-C6 alkyl group;

[0019] R3 and R4 are each independently a C1-C6 alkyl group;

[0020] R5 is a C1-C6 alkylene group; R6 is H or an alkali metal element;

[0021] R 12 、R 13 and R 14 are each independently a C1-C6 alkyl group, and R 12 、R 13 and R 14 At least one is a methyl group.

[0022] The fourth aspect of the present invention provides a copolymer prepared by the preparation method described in the third aspect.

[0023] The fifth aspect of the present invention provides a control and displacement system, which contains a cross-linking agent and the copolymer as described above.

[0024] Through the above technical solution, the beneficial technical effects achieved by the present invention are as follows:

[0025] (1) The copolymer of the present invention contains an olefin skeleton and sulfonic acid groups, amide groups, aminoacyl groups and tertiary carbonate groups bonded to the olefin skeleton. Through the synergistic effect of these functional groups, the hydrolysis rates of the amide groups and aminoacyl groups are controlled, so that the copolymer can be slowly hydrolyzed to release cross-linking sites in the reservoir environment, ultimately achieving a higher hydrolysis rate; at the same time, the copolymer has strong hydrolysis resistance and a stable skeleton structure.

[0026] (2) The cross-linking sites released by the copolymer of the present invention under the reservoir environment can be combined with the cross-linking agent to form a flow control system, which achieves initial low viscosity after injection into the reservoir. During the migration process, the cross-linking groups are continuously released through slow hydrolysis, thereby achieving gradual viscosity increase and maintaining a certain viscosity and strength of the flow control system, thereby achieving deep flow control, flow channel adjustment and long-term plugging.

[0027] (a) The copolymer of the present invention can form coordination bonds with a metal cross-linking agent to form a high-viscosity flow control system. The flow control system still has a high viscosity after aging for 60 days at 70-130°C under an environment with a salinity of ≤300,000 mg / L and a calcium and magnesium ion content of ≤10,000 mg / L, and a viscosity increase rate of greater than 200%. Therefore, the system can be used as a flow control agent in carbonate oil reservoirs to achieve flow channel adjustment.

[0028] (b) The copolymer of the present invention can react with phenolic and aldehyde cross-linking agents to form a high-strength flow control system. The flow control system can be stable for at least 90 days at a high temperature of 140-160°C under an environment with a salinity of ≤300,000 mg / L and a calcium and magnesium ion content of ≤10,000 mg / L, while maintaining good viscoelasticity and a low dehydration rate. Therefore, it can be used as a plugging agent in carbonate oil reservoirs to achieve long-term flow control. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG1 is an infrared spectrum of the sulfonic acid copolymer prepared in Example 1;

[0030] FIG2 is an X-ray photoelectron spectrum of the sulfonic acid copolymer obtained in Example 4;

[0031] Figures 3a and 3b are C1s and O1s diagrams of the sulfonic acid copolymer, respectively; wherein 1 is the C1s and O1s diagrams of the sulfonic acid copolymer containing only structural units A and structural units B; 2 is the C1s and O1s diagrams of the sulfonic acid copolymer containing only structural units A, structural units B, and structural units C obtained in Comparative Example D3; 3 is the C1s and O1s diagrams of the sulfonic acid copolymer containing structural units A, structural units B, structural units C, and structural units D obtained in Example 4;

[0032] Curve a in FIG4 is an infrared spectrum of the sulfonic acid copolymer obtained in Example 4; curve b is an infrared spectrum of the sulfonic acid copolymer obtained in Comparative Example D3. DETAILED DESCRIPTION

[0033] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0034] The first aspect of the present invention provides a copolymer comprising a structural unit A represented by formula I, a structural unit B represented by formula II, a structural unit C represented by formula III, and a structural unit D represented by formula IV;

[0035] Among them, R1, R7, R8 and R 11 Each is independently H or a C1-C6 alkyl group;

[0036] R2, R9 and R 10 Each is independently H or a C1-C6 alkyl group;

[0037] R3 and R4 are each independently a C1-C6 alkyl group;

[0038] R5 is a C1-C6 alkylene group; R6 is H or an alkali metal element;

[0039] R 12 、R 13 and R 14 are each independently a C1-C6 alkyl group, and R 12 、R 13 and R 14 At least one is a methyl group.

[0040] According to the present invention, the copolymer comprises structural units A, B, C, and D. The synergistic effect of these structural units controls the hydrolysis rate of the copolymer, allowing the copolymer to slowly hydrolyze and release crosslinking sites in reservoir environments, ultimately achieving a high hydrolysis rate. Specifically, structural units A and D synergistically control the hydrolysis rates of structural units B and C, increasing the stability of the copolymer at high temperatures. Furthermore, structural unit A enables the copolymer to have good solubility in high-mineralization, high-calcium and magnesium ion environments, preventing precipitation.

[0041] According to the present invention, the C1-C6 alkyl group includes, but is not limited to, methyl, ethyl, propyl, butyl, pentyl, and hexyl.

[0042] According to a preferred embodiment of the present invention, R1, R7, R8 and R 11 are each independently H or methyl.

[0043] According to a preferred embodiment of the present invention, R2 is H.

[0044] According to a preferred embodiment of the present invention, R3 and R4 are each independently a methyl group.

[0045] According to a preferred embodiment of the present invention, R5 is methylene; R6 is H or Na.

[0046] According to a preferred embodiment of the present invention, R9 is H.

[0047] According to a preferred embodiment of the present invention, R 10 is H or methyl.

[0048] According to some preferred embodiments of the present invention, R 12 、R 13 and R 14 are each independently methyl.

[0049] According to other preferred embodiments of the present invention, R 12 、R 13 and R 14 One of the substituents is methyl, and the total number of carbon atoms of the remaining two substituents is 6-8; preferably, R12 Methyl, R 13 is n-pentyl, R 14 is methyl; or R 12 Methyl, R 13 is n-hexyl, R 14 It is a methyl group.

[0050] According to a particularly preferred embodiment of the present invention, R1, R7, R8 and R 11 R2 is H; R3 and R4 are each independently methyl; R5 is methylene; R6 is H or Na; R9 is H; R 10 is H or methyl; R 12 、R 13 and R 14 are each independently methyl.

[0051] According to a preferred embodiment of the present invention, based on the total weight of the copolymer, the content of the structural unit D is 0.1-2 weight%, for example, 0.1 weight%, 0.2 weight%, 0.3 weight%, 0.5 weight%, 0.8 weight%, 1 weight%, 1.2 weight%, 1.5 weight%, 1.8 weight%, 2 weight%, and the range formed by any two of the above values ​​and the value within the range.

[0052] According to a preferred embodiment of the present invention, based on the total weight of the copolymer, the content of the structural unit A is not less than 60 weight%, for example, 60 weight%, 65 weight%, 70 weight%, 75 weight%, 80 weight%, 84 weight%, 85 weight%, 88 weight%, 90 weight%, and the range formed by any two of the above values ​​and the value within the range.

[0053] According to a preferred embodiment of the present invention, based on the total weight of the copolymer, the content of the structural unit A is 65-90 weight %; the content of the structural unit B is 5-30 weight %; the content of the structural unit C is 1-8 weight %; and the content of the structural unit D is 0.1-2 weight %.

[0054] According to the present invention, based on the total weight of the copolymer, the content of the structural unit A is 65-90 weight%, for example, 65 weight%, 70 weight%, 75 weight%, 80 weight%, 84 weight%, 85 weight%, 88 weight%, 90 weight%, and the range formed by any two of the above values ​​and the value within the range, preferably 70-84 weight%; the content of the structural unit B is 5-30 weight%, for example, 5 weight%, 10 weight%, 15 weight%, 20 weight%, 25 weight%, 30 weight%, and the range formed by any two of the above values ​​and the value within the range, preferably 12-25 weight%; The content of the structural unit C is 1-8 weight%, for example, 1 weight%, 2 weight%, 3 weight%, 4 weight%, 5 weight%, 6 weight%, 7 weight%, 8 weight%, and the range formed by any two of the above values ​​and the values ​​within the range, preferably 3-6 weight%; the content of the structural unit D is 0.1-2 weight%, for example, 0.1 weight%, 0.2 weight%, 0.3 weight%, 0.5 weight%, 0.8 weight%, 1 weight%, 1.2 weight%, 1.5 weight%, 1.8 weight%, 2 weight%, and the range formed by any two of the above values ​​and the values ​​within the range, preferably 0.2-1 weight%.

[0055] According to the present invention, the method for detecting the structural units contained in the polymer is as follows:

[0056] (1) Prepare extraction solution A: Add 900 g of deionized water to a 2000 mL volumetric flask, pipette 20 mL of ethanol, and dilute to the mark with isopropanol.

[0057] (2) Prepare extraction solution B: Add 500 g of deionized water to a 2000 mL volumetric flask, pipette 20 mL of ethanol, and dilute to the mark with isopropanol.

[0058] (3) Accurately weigh 2 g of polymer powder sample in a vial, add 10 mL of solution A, and place it in a magnetic stirrer for 40 minutes; then add 10 mL of solution B and continue stirring for 40 minutes; take the supernatant and remove isopropanol, ethanol, and water by vacuum distillation to obtain a test sample.

[0059] (4) Qualitative detection of monomers: The obtained test samples are first subjected to liquid chromatography-mass spectrometry analysis to determine the number and structure of monomers; at the same time, the test samples are separated by column chromatography, and the structure of each monomer is determined by nuclear magnetic resonance assisted structure determination.

[0060] (5) Quantitative detection: Use X-ray photoelectron spectrometer (XPS) to scan and analyze the polymer powder to determine the surface elemental composition of C, O, N, S, etc., and then further narrow spectrum scan specific elements to analyze the presence of specific elements and perform quantitative analysis. The feed amount of each monomer is calculated based on the element content obtained by analysis, and then the weight percentage of each structural unit is determined based on the feed amount of each monomer. For example, the structure of structural unit A is determined by the monomer corresponding to element S, and then the weight percentage of structural unit A is determined by the percentage of element S.

[0061] According to the present invention, the molar ratio of the elements C, O, N and S in the polymer measured by XPS method is 8.5-15:4-6:1-3:1.

[0062] According to the present invention, C exists in the form of CC, CN, CS, C═O and COC═O, and the molar ratio of each is 70-950:25-480:5-180:5-280:1.

[0063] According to the present invention, O exists in the form of NC═O, SO 2 —O and OC═O, with the respective molar ratios being 28-390:35-750:1.

[0064] According to the present invention, the infrared spectrum of the polymer contains antisymmetric contraction vibration peaks and symmetric contraction vibration peaks of COC.

[0065] A second aspect of the present invention provides a copolymer comprising an olefin skeleton and functional groups bonded to the olefin skeleton, wherein the functional groups include sulfonic acid groups, tertiary carbonate groups, amide groups, and amino groups; wherein, based on the total weight of the copolymer, the weight content of the tertiary carbonate groups is 0.06-1.5 weight percent; the weight content of the sulfonic acid groups is not less than 21 weight percent; and the viscosity-average molecular weight of the copolymer is 5 million to 18 million.

[0066] According to the present invention, an amide group refers to a group derived from an alkenylamide, for example, -CONH2; an aminoacyl group refers to a group derived from an N-alkenylamide, for example, -NHCOR.

[0067] According to the present invention, after determining the structure and weight percentage of each monomer and each structural unit according to the above-mentioned detection method for the structural units contained in the polymer, the weight percentage of each group is determined through analysis and calculation. For example, the molar content of the corresponding structural unit A is calculated based on the molar content of the S element and the corresponding SO2-O functional group ratio in O1s, and then the weight percentage of the sulfonic acid group is calculated; the weight percentage of the corresponding tertiary carbonate group is calculated based on the functional group ratio of the ester group in O1s and C1s.

[0068] According to the present invention, based on the total weight of the copolymer, the weight content of tertiary carbonate groups is 0.06-1.5 weight %; for example, 0.06 weight %, 0.07 weight %, 0.08 weight %, 0.09 weight %, 0.1 weight %, 0.2 weight %, 0.3 weight %, 0.4 weight %, 0.5 weight %, 0.6 weight %, 0.7 weight %, 0.8 weight %, 0.9 weight %, 1 weight %, 1.1 weight %, 1.2 weight %, 1.3 weight %, 1.4 weight %, 1.5 weight %, and ranges formed by any two of the above values ​​and values ​​within the range, preferably 0.2-1 weight %.

[0069] According to the present invention, based on the total weight of the copolymer, the weight content of sulfonic acid groups is not less than 21 weight %, for example, 21 weight %, 22 weight %, 23 weight %, 24 weight %, 25 weight %, 26 weight %, 27 weight %, 28 weight %, 29 weight %, 30 weight %, 31 weight %, 32 weight %, 33 weight %, 34 weight %, 35 weight %, and ranges formed by any two of the above values, and preferably 25-30 weight %.

[0070] According to the present invention, the viscosity-average molecular weight of the copolymer is 5 million to 18 million, for example, it can be 5 million, 6 million, 7 million, 8 million, 9 million, 10 million, 11 million, 11.6 million, 12 million, 13 million, 14.5 million, 15 million, 16 million, 17 million, 18 million, and the range formed by any two of the above values ​​and the value within the range.

[0071] The copolymer of the present invention contains hydrolyzable structural units, which are structural units that hydrolyze to produce cross-linking groups such as carboxyl groups and amino groups. Under the synergistic effect of the structural units containing sulfonic acid groups and the structural units containing tertiary carbonate groups, the hydrolysis rate of the hydrolyzable structural units in the copolymer can be controlled, thereby increasing the stability of the copolymer at high temperatures. This allows the copolymer to slowly release the cross-linking groups after high-temperature aging. After being injected into an oil reservoir together with a cross-linking agent, the copolymer achieves initial low viscosity. During migration, the cross-linking groups are continuously released through slow hydrolysis, thereby achieving gradual viscosity increase and maintaining a certain viscosity and strength of the gel system, thereby achieving deep profile control and flooding.

[0072] According to the present invention, the cross-linking groups generated after high-temperature hydrolysis refer to the carboxyl groups and amino groups generated after the copolymer is hydrolyzed.

[0073] According to the present invention, the total hydrolysis rate of an aqueous solution of the copolymer with a concentration of 5000 mg / L is not greater than 20% when placed at 130° C. for 15 days, and the total hydrolysis growth rate from 15 days to 60 days is not less than 90%; wherein the total hydrolysis rate refers to the percentage of the total mass of structural units that are hydrolyzed to produce carboxyl groups and amino groups to the initial mass of the copolymer.

[0074] According to the present invention, the hydrolysis rate of the amide group of an aqueous solution of the copolymer with a concentration of 5000 mg / L is no more than 15% when placed at 130° C. for 15 days, and the growth rate of the hydrolysis of the amide group from 15 days to 60 days is no less than 90%; wherein the hydrolysis rate of the amide group refers to the percentage of the mass of the structural unit of the carboxyl group produced by hydrolysis to the initial mass of the copolymer.

[0075] The above-mentioned change in hydrolysis rate indicates that the copolymer can slowly release crosslinking groups after high-temperature aging. In other words, the crosslinking groups generated by structural units B and C in the copolymer after high-temperature aging have a slow-release function. The copolymer achieves an initial low viscosity upon initial injection into the reservoir. During migration, it continuously releases crosslinking groups through hydrolysis to crosslink with the crosslinker, achieving a gradual increase in viscosity while maintaining a certain viscosity and strength for the gel system. After aging at 130°C for 60 days, it still maintains good viscosity and strength, maintaining long-term stability and enabling deep-level flooding. It can be used as a flow control agent and plugging agent in carbonate reservoirs for flow adjustment and plugging.

[0076] According to a preferred embodiment of the present invention, the copolymer glue formed by mixing the copolymer and the metal crosslinking agent has a viscosity increase rate greater than 200% after being placed at 130°C for 60 days, wherein the viscosity increase rate = (viscosity after 60 days - initial viscosity) / initial viscosity × 100%.

[0077] Preparation of copolymer glue: Add the copolymer sample to 900 g of simulated saline, stir at 600 rpm / min until completely dissolved, add 0.5 g of chromium citrate and 0.8 g of chromium lactate, stir until completely dissolved, add 0.8 g of sodium thiosulfate, make up the total weight with simulated saline to 1 kg, and stir evenly to obtain a copolymer glue, wherein the mineralization of the simulated saline is 300,000 mg / L, and the calcium and magnesium ion content is 10,000 mg / L.

[0078] Detection method: Brookfield R / S Rheometer was used to measure the -1 The initial viscosity under shear rate and the viscosity after 60 days of storage are calculated according to the above formula to obtain the viscosity increase rate.

[0079] A third aspect of the present invention provides a method for preparing a copolymer, the method comprising: polymerizing an olefinic monomer under solution polymerization conditions in the presence of an initiator; wherein the olefinic monomer comprises monomer A′ represented by formula 1, monomer B′ represented by formula 2, monomer C′ represented by formula 3, and monomer D′ represented by formula 4;

[0080] Among them, R1, R7, R8 and R 11Each is independently H or a C1-C6 alkyl group;

[0081] R2, R9 and R 10 Each is independently H or a C1-C6 alkyl group;

[0082] R3 and R4 are each independently a C1-C6 alkyl group;

[0083] R5 is a C1-C6 alkylene group; R6 is H or an alkali metal element;

[0084] R 12 、R 13 and R 14 are each independently a C1-C6 alkyl group, and R 12 、R 13 and R 14 At least one is a methyl group.

[0085] According to the present invention, the C1-C6 alkyl group includes, but is not limited to, methyl, ethyl, propyl, butyl, pentyl, hexyl, and the like.

[0086] According to a preferred embodiment of the present invention, R1, R7, R8 and R 11 are each independently H or methyl.

[0087] According to a preferred embodiment of the present invention, R2 is H.

[0088] According to a preferred embodiment of the present invention, R3 and R4 are each independently a methyl group.

[0089] According to a preferred embodiment of the present invention, R5 is methylene; R6 is H or Na.

[0090] According to a preferred embodiment of the present invention, R9 is H.

[0091] According to a preferred embodiment of the present invention, R 10 is H or methyl.

[0092] According to some preferred embodiments of the present invention, R 12 、R 13 and R 14 are each independently methyl.

[0093] According to other preferred embodiments of the present invention, R 12 、R 13 and R 14 One of the substituents is methyl, and the total number of carbon atoms of the remaining two substituents is 6-8; preferably, R 12 Methyl, R 13 is n-pentyl, R 14 is methyl; or R 12 Methyl, R13 is n-hexyl, R 14 It is a methyl group.

[0094] According to a particularly preferred embodiment of the present invention, R1, R7, R8 and R 11 R2 is H; R3 and R4 are each independently methyl; R5 is methylene; R6 is H or Na; R9 is H; R 10 is H or methyl; R 12 、R 13 and R 14 are each independently methyl.

[0095] In some preferred embodiments of the present invention, Formula 1 is 2-acrylamido-2-methylpropanesulfonic acid and / or sodium 2-acrylamido-2-methylpropanesulfonate.

[0096] In some preferred embodiments of the present invention, Formula 2 is acrylamide and / or methacrylamide.

[0097] In some preferred embodiments of the present invention, Formula 3 is N-vinylformamide and / or N-vinylacetamide.

[0098] In some preferred embodiments of the present invention, Formula 4 is preferably at least one of vinyl pivalate, vinyl neononanoate, and vinyl neodecanoate.

[0099] According to a preferred embodiment of the present invention, based on the total weight of the olefinic monomer, the content of the monomer D′ is 0.1-2 weight%, for example, 0.1 weight%, 0.2 weight%, 0.3 weight%, 0.5 weight%, 0.8 weight%, 1 weight%, 1.2 weight%, 1.5 weight%, 1.8 weight%, 2 weight%, and the range formed by any two of the above values ​​and the value within the range.

[0100] According to a preferred embodiment of the present invention, based on the total weight of the olefinic monomer, the content of the monomer A' is not less than 60 weight%, for example, 60 weight%, 65 weight%, 70 weight%, 75 weight%, 80 weight%, 84 weight%, 85 weight%, 88 weight%, 90 weight%, and the range formed by any two of the above values ​​and the value within the range.

[0101] According to a preferred embodiment of the present invention, based on the total weight of the olefinic monomers, the content of monomer A' is 65-90 weight %, the content of monomer B' is 5-30 weight %, the content of monomer C' is 1-8 weight %, and the content of monomer D' is 0.1-2 weight %.

[0102] Based on the total weight of the olefinic monomer, the content of the monomer A' is 65-90 weight%, for example, 65 weight%, 70 weight%, 75 weight%, 80 weight%, 84 weight%, 85 weight%, 88 weight%, 90 weight%, and the range formed by any two of the above values ​​and the value within the range, preferably 70-84 weight%; the content of the monomer B' is 5-30 weight%, for example, 5 weight%, 10 weight%, 15 weight%, 20 weight%, 25 weight%, 30 weight%, and the range formed by any two of the above values ​​and the value within the range, preferably 12-25 weight%; the The content of monomer C' is 1-8 weight%, for example, 1 weight%, 2 weight%, 3 weight%, 4 weight%, 5 weight%, 6 weight%, 7 weight%, 8 weight%, and the range formed by any two of the above values ​​and the values ​​within the range, preferably 3-6 weight%; the content of monomer D' is 0.1-2 weight%, for example, 0.1 weight%, 0.2 weight%, 0.3 weight%, 0.5 weight%, 0.8 weight%, 1 weight%, 1.2 weight%, 1.5 weight%, 1.8 weight%, 2 weight%, and the range formed by any two of the above values ​​and the values ​​within the range, preferably 0.2-1 weight%.

[0103] According to the present invention, the weight ratio of the monomer A', the monomer B', the monomer C' and the monomer D' is 1:(0.01-1):(0.01-0.2):(0.0005-0.06), preferably 1:(0.08-0.6):(0.02-0.15):(0.0008-0.04).

[0104] According to the present invention, the initiator can be selected from various initiators commonly used in the art. For example, the initiator can be selected from azo initiators and / or redox initiators.

[0105] According to the present invention, the azo initiator is preferably a water-soluble azo initiator. The redox initiator comprises an oxidizing agent and a reducing agent, wherein the reducing agent is an inorganic reducing agent and / or an organic reducing agent, and the weight ratio of the oxidizing agent to the reducing agent is (0.1-1):1.

[0106] Preferably, the water-soluble azo initiator is selected from at least one of 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis(2-imidazolinylpropane) dihydrochloride, and 4,4'-azobis(4-cyanovaleric acid). Preferably, the oxidant is selected from at least one of benzoyl peroxide, hydrogen peroxide, tert-butyl hydroperoxide, 2,5-dimethyl-2,5-bis(hydroperoxide)hexane, ammonium persulfate, sodium persulfate, and potassium persulfate. Preferably, the inorganic reducing agent is selected from at least one of ferrous sulfate, ferrous ammonium sulfate, cuprous chloride, potassium sulfite, sodium sulfite, ammonium bisulfite, potassium bisulfite, sodium thiosulfate, potassium thiosulfate, sodium formaldehyde sulfoxylate (rongalite), and sodium bisulfite. Preferably, the organic reducing agent is at least one selected from N,N-dimethylethanolamine, N,N'-dimethylpiperazine, N,N,N',N'-tetramethylurea and N,N,N',N'-tetramethylethylenediamine.

[0107] According to the present invention, the amount of the initiator used may be 0.0003-0.05 wt % of the weight of the olefinic monomer. Preferably, the amount of the azo initiator used is 0.0001-0.1 wt % of the weight of the olefinic monomer. Preferably, the amount of the redox initiator used is 0.0002-0.3 wt % of the weight of the olefinic monomer.

[0108] According to the present invention, the preparation method preferably further comprises an emulsifier, which can better disperse the monomer D' and solubilize the monomer D'. The emulsifier comprises one or more of Tween 60, Tween 80, sodium dodecyl sulfate, and sodium dodecylbenzenesulfonate. The amount of the emulsifier used is 5-30 times the weight of the monomer D', based on the weight of the added monomer D'.

[0109] According to the present invention, the solution polymerization reaction conditions can achieve the viscosity-average molecular weight of the resulting copolymer as described above. Preferably, the solution polymerization reaction conditions include: a polymerization reaction starting temperature of -10°C to 30°C, a polymerization reaction time of 2-12 hours, and a pH value of 4-8. Preferably, the polymerization reaction starting temperature of -5°C to 10°C, a polymerization reaction time of 3-10 hours, and a pH value of 5-7.

[0110] In the present invention, an alkali metal hydroxide (such as sodium hydroxide or potassium hydroxide) can be used to adjust the pH of the polymerization reaction. It is understood that by using an alkali metal hydroxide to adjust the pH, R3 in structural unit A (monomer A') can be converted from H to an alkali metal element (such as Na). Furthermore, by controlling the amount of alkali metal hydroxide used, R3 in structural unit A of the copolymer of the present invention can be made to contain both H and alkali metal elements. In the sulfonic acid copolymer of the present invention, R9 is partially H and partially alkali metal elements.

[0111] According to the present invention, at the start of the solution polymerization reaction, the ratio of the total weight of the olefinic monomer to the total weight of the solvent and the olefinic monomer is (0.3-0.55):1, preferably (0.35-0.5):1.

[0112] According to the present invention, in order to better control the induction period and reduce the inhibition effect of dissolved oxygen, the polymerization reaction is preferably carried out in an inert atmosphere, which can be provided by nitrogen and / or an inert gas.

[0113] According to the present invention, in order to control the foam in the reaction system, the polymerization reaction is carried out in the presence of a defoaming agent. The amount of the defoaming agent can be 0.05-1% by weight of the amount of the olefinic monomer used. The defoaming agent can be selected from various defoaming agents commonly used in the art.

[0114] According to the present invention, the preparation method may further comprise: granulating, drying, crushing and screening the copolymer colloid obtained by the polymerization reaction to obtain a copolymer product.

[0115] According to the present invention, the drying conditions include: a temperature of 40-70° C., preferably, a temperature of 45-65° C. In the present invention, the drying time is not specifically limited, and the product can be dried until the solid content reaches 85-95% by weight, preferably 88-90% by weight. Generally, the drying time is 2-24 hours.

[0116] The fourth aspect of the present invention provides a copolymer prepared by the preparation method described in the third aspect.

[0117] In the present invention, the content of each structural unit in the copolymer can be determined using conventional methods in the prior art, such as infrared spectroscopy and nuclear magnetic resonance. Alternatively, the content of each structural unit in the copolymer can be determined by monomer feed amount. Specifically, the feed ratio of each monomer actually participating in the polymerization can be determined by testing the content of unreacted monomers, thereby determining the content of each structural unit in the copolymer. Furthermore, in the present invention, when the content of each unreacted monomer in the copolymer is less than 0.02% by weight of its own content, it indicates that substantially all monomers have participated in the polymerization reaction. Specifically, the residual monomer content can be determined using liquid chromatography.

[0118] The present invention also provides the use of the copolymer described above in oil reservoir exploitation.

[0119] According to the present invention, the oil reservoir is a high-temperature, high-salinity oil reservoir, preferably a carbonate oil reservoir.

[0120] According to the present invention, the reservoir temperature of the oil reservoir is 60-160° C., preferably 70-160° C.; the mineralization is ≤300,000 mg / L, and the calcium and magnesium ion concentrations are ≤10,000 mg / L.

[0121] Preferably, the carbonate oil reservoir has a reservoir temperature of 70-160° C., a salinity of 1000-300000 mg / L, and a calcium and magnesium ion concentration of 100-10000 mg / L.

[0122] The present invention also provides the use of a flow control system containing a cross-linking agent and the aforementioned sulfonic acid copolymer as a flow control agent or a plugging control agent in oil reservoir exploitation.

[0123] The fifth aspect of the present invention provides a control and displacement system, which contains a cross-linking agent and the copolymer as described above.

[0124] The copolymer of the present invention can slowly release cross-linking groups after high-temperature aging, and achieves initial low viscosity after being injected into the oil reservoir together with the cross-linking agent. During the migration process, the cross-linking groups are continuously released through slow hydrolysis, thereby achieving gradual viscosity increase and maintaining a certain viscosity and strength of the gel system, thereby realizing deep displacement.

[0125] According to the present invention, the cross-linking groups released by high-temperature aging refer to the carboxyl groups and amino groups generated after the copolymer is hydrolyzed.

[0126] According to the present invention, the flow control system is suitable for carbonate oil reservoirs, and is particularly suitable for flow control and plugging in carbonate oil reservoirs.

[0127] According to the present invention, the control and displacement system may further contain a solvent, wherein the solvent is water. The content of the solvent may be 97-99.6 wt %, preferably 98.3-99.1 wt %.

[0128] In some embodiments of the present invention, the control and displacement system comprises a cross-linking agent and the aforementioned sulfonic acid copolymer. The control and displacement system of the present invention is particularly suitable for flow regulation and plugging in carbonate oil reservoirs.

[0129] In the present invention, based on the total weight of the control and displacement system, the content of the sulfonic acid copolymer is preferably 0.3-1.5 wt%, for example, 0.3 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.2 wt%, 1.5 wt%, and ranges formed by any two of the above values, and values ​​within the range, more preferably 0.5-1.2 wt%.

[0130] In the present invention, based on the total weight of the control and displacement system, the content of the cross-linking agent is preferably 0.01-2 weight %, for example, 0.01 weight %, 0.02 weight %, 0.05 weight %, 0.1 weight %, 0.5 weight %, 1 weight %, 1.2 weight %, 1.5 weight %, 1.8 weight %, 2 weight %, and ranges formed by any two of the above values, and values ​​within the range, more preferably 0.02-1.5 weight %.

[0131] In the present invention, the crosslinking agent can be selected from common substances in the art that can crosslink the sulfonic acid copolymer, for example, it can be at least one of an organic metal crosslinking agent, a phenol crosslinking agent, and an aldehyde crosslinking agent.

[0132] According to a more preferred embodiment of the present invention, the organometallic crosslinking agent is a crosslinking agent formed by a metal ion and an organic ligand compound. Preferably, the metal ion is selected from at least one of aluminum, chromium, zirconium, iron, and titanium. Preferably, the organic ligand compound is selected from at least one of an organic acid and an organic amine, more preferably selected from at least one of citric acid, oxalic acid, acetic acid, lactic acid, polyene polyamine, and triethanolamine.

[0133] Further preferably, the organometallic crosslinking agent is selected from at least one of chromium citrate, chromium oxalate, chromium lactate, zirconium citrate, zirconium lactate, n-propyl zirconate, aluminum citrate and aluminum lactate.

[0134] The copolymer of the present invention can be combined with an organic metal cross-linking agent to form a flow control system. The flow control system can be used as a flow control agent in water with a salinity of ≤300,000 mg / L and a calcium and magnesium ion content of ≤10,000 mg / L. After aging at 70-130° C. for 60 days, the system still has good viscosity and excellent stability, and can be used for adjusting flow channels in carbonate oil reservoirs.

[0135] According to the present invention, the phenolic crosslinking agent and the aldehyde crosslinking agent can be provided by the same substance, such as at least one of a water-soluble phenolic resin and a sulfonated phenolic resin, preferably a sulfonated phenolic resin.

[0136] According to a more preferred embodiment of the present invention, the phenolic crosslinking agent is at least one of phenol, cresol (such as o-cresol, m-cresol, p-cresol), hydroquinone, catechol, and resorcinol, more preferably hydroquinone.

[0137] According to a more preferred embodiment of the present invention, the aldehyde-type crosslinking agent is at least one of formaldehyde, acetaldehyde, paraformaldehyde, hexamethylenetetramine (which releases formaldehyde upon heating) and furfural, more preferably hexamethylenetetramine.

[0138] The copolymer of the present invention can form a flooding system with phenol-type and aldehyde-type cross-linking agents. Under an environment where the salinity is ≤300,000 mg / L and the calcium and magnesium ion content is ≤10,000 mg / L, the copolymer has a low dehydration rate after aging at a high temperature of 140-160°C for 90 days and has a high storage modulus, indicating high strength and good thermal stability. The copolymer can be used as a flooding agent for ultra-deep wells in carbonate reservoirs.

[0139] In the present invention, the phenol type crosslinking agent and the aldehyde type crosslinking agent may be provided by different substances. More preferably, the weight ratio of the phenol type crosslinking agent to the aldehyde type crosslinking agent is 1:(0.6-1.5).

[0140] In the present invention, the control and displacement system may further contain an oxygen scavenger. The oxygen scavenger content may be 0.005-0.3% by weight, preferably 0.02-0.25% by weight, based on the total weight of the control and displacement system. The type and amount of the oxygen scavenger may be selected with reference to existing techniques. In the present invention, the oxygen scavenger is preferably at least one of sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium hydrosulfite, isoascorbic acid, and thiourea.

[0141] In the present invention, water is used as the solvent and reaction medium in the copolymer. The present invention does not particularly limit the selection of water. The water can be natural water or artificial water. Natural water can be river, lake, atmospheric water, seawater, groundwater, etc. Artificial water can be tap water, distilled water, deionized water, or heavy water.

[0142] Generally speaking, in actual application, the water used is often the water at the oil field site (field water) or its corresponding simulated brine. Preferably, the water has a salinity of 1000-300000 mg / L and a calcium and magnesium ion content of 100-10000 mg / L.

[0143] The present invention is described in detail below through embodiments and application examples, but the protection scope of the present invention is not limited to the following description.

[0144] In the following examples, application examples, and comparative examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or those recommended by the manufacturer. All reagents or instruments used, if no manufacturer is specified, are commercially available conventional products.

[0145] In the following application examples, simulated brine is prepared according to the applicable reservoir environment. The salinity of the simulated brine is 100,000-300,000 mg / L, and the concentration of calcium and magnesium ions is 5,000-10,000 mg / L (it should be understood that the salinity is an approximate value).

[0146] 2-Acrylamido-2-methylpropanesulfonic acid and sodium 2-acrylamido-2-methylpropanesulfonate in monomer A′ were purchased from Shandong Weifang Jinshi Environmental Protection Technology Co., Ltd.

[0147] Monomer B′ acrylamide was purchased from Dongying Baomo Environmental Engineering Co., Ltd.

[0148] Monomer C′ was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0149] Monomer D' was purchased from Sigma-Aldrich.

[0150] Aluminum citrate, zirconium citrate, and zirconium lactate were purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd.

[0151] Chromium citrate and chromium lactate were purchased from Shandong Shida Oilfield Technology Service Co., Ltd.

[0152] Unless otherwise specified, the reagents and materials used in the following application examples are commercially available. The defoaming agent used is an organosilicon defoamer purchased from Hai'an Petrochemical Plant in Jiangsu Province.

[0153] The test method is as follows:

[0154] 1) Viscosity average molecular weight: German Lauda Proline PVS2.59 was used for testing according to the method specified in GB / T 12005.10-92 "Polyacrylamide Molecular Weight Determination - Viscosity Method".

[0155] 2) Calculation method of hydrolysis rate: According to GB / T 12005.6-1989 "Determination of hydrolysis degree of partially hydrolyzed polyacrylamide" (titration endpoint is pH = 3), the specific steps are as follows:

[0156] (a) A certain mass of the copolymer solution after high temperature aging is titrated according to GB / T 12005.6-1989 "Determination of the degree of hydrolysis of partially hydrolyzed polyacrylamide" (the titration endpoint is pH = 3) to obtain the hydrochloric acid consumption V1 (the total hydrochloric acid consumption of the acrylate and formate (acetate) structural units);

[0157] (b) An equal mass of the high-temperature aged copolymer solution was first purified using a dialysis membrane (molecular weight cut-off: 3500, Solebold brand) to remove sodium formate (or sodium acetate) produced by hydrolysis, and then subjected to rotary evaporation to remove most of the water. The aged copolymer powder sample was freeze-dried and pulverized to obtain an aged copolymer powder sample. The hydrochloric acid consumption V2 (the hydrochloric acid consumption of the acrylic acid group) was then calculated according to GB / T 12005.6-1989 "Determination of the Degree of Hydrolysis of Partially Hydrolyzed Polyacrylamide" (titration endpoint was pH = 3), and the hydrolysis rate of the structural unit B was calculated based on V2;

[0158] (c) The hydrochloric acid consumption of formate or acetate is calculated by V3 = V1 - V2, and the hydrolysis rate of structural unit C after high temperature is calculated with reference to the hydrolysis degree formula in GB / T 12005.6-1989 "Determination of hydrolysis degree of partially hydrolyzed polyacrylamide".

[0159] The hydrolysis rate of the structural unit B containing an amide group in the copolymer refers to the percentage of the mass of the structural unit containing a carboxyl group produced by hydrolysis to the initial mass of the copolymer. The calculation formula is as follows:

[0160] The hydrolysis rate of the structural unit B containing an amide group = the mass of the structural unit corresponding to the carboxyl group / the mass of the copolymer × 100% = C HCl ·V2·71·100 / (1000·m·s+M2·C HCl ·V3-23·C HCl V2); where C HCl is the concentration of the hydrochloric acid standard solution, mol / L; V2 is the hydrochloric acid consumption of the acrylic acid radical produced by hydrolysis, mL; m is the mass of the sample, g; s is the solid content of the sample, weight %; M2 is the difference in the mass of the chain segments of the structural unit C before and after hydrolysis; V3 is the hydrochloric acid consumption of the formate or acetate radical produced by hydrolysis, mL.

[0161] The hydrolysis growth rate of the structural unit containing an amide group=(the hydrolysis rate after aging for 60 days-the hydrolysis rate after aging for 15 days) / the hydrolysis rate after aging for 15 days×100%.

[0162] The calculation formula for the hydrolysis rate of the structural unit C containing an amino acyl group in the copolymer is as follows:

[0163] The hydrolysis rate of the aminoacyl group-containing structural unit C = C HCl ·V3·M1·100 / (1000·m·s+M2·C HCl ·V3-23·C HCl V2); where C HCl is the concentration of the hydrochloric acid standard solution, mol / L; V3 is the hydrochloric acid consumption of formate or acetate produced by hydrolysis, mL; m is the mass of the sample, g; s is the solid content of the sample, weight %; M1 is the solid content of the sample with 1 mL of hydrochloric acid standard solution (C HCl =1.0 mol / L); M2 is the mass of the structural unit C equivalent to the mass before and after hydrolysis of the structural unit C. When X in the structural unit C is NH and R5 is H, M1 is 71 and M2 is 28; when X is NH and R5 is methyl, M1 is 85 and M2 is 42.

[0164] The total hydrolysis rate of the copolymer refers to the percentage of the total mass of the structural units hydrolyzed to produce carboxyl groups and amino groups to the initial mass of the copolymer, and its calculation formula is: total hydrolysis rate = hydrolysis rate of structural unit B + hydrolysis rate of structural unit C = total mass of the structural units corresponding to the carboxyl groups and amino groups / (initial mass of the copolymer) × 100%.

[0165] The total hydrolysis growth rate of the copolymer is calculated as follows: total hydrolysis growth rate = (total hydrolysis rate after aging for 60 days - total hydrolysis rate after aging for 15 days) / total hydrolysis rate after aging for 15 days × 100%.

[0166] 3) Aging viscosity of the control system: The copolymer gel formed by the copolymer and the metal cross-linking agent is placed in a sealed stainless steel reactor, and placed in a constant temperature box at a certain temperature (for example, 130°C) for reaction. After a set time (for example, 60 days), it is taken out of the constant temperature box and the viscosity is measured.

[0167] 4) Viscosity increase of the profile displacement system: measured using a Brookfield R / S Rheometer at 30°C for 7.34 seconds. -1 Viscosity under shear rate; wherein, the viscosity increase rate is calculated as follows: viscosity increase rate = (viscosity after aging - initial viscosity) / initial viscosity × 100%.

[0168] 5) Storage modulus of the profile control and displacement system: The storage modulus of the profile control and displacement system is measured by rheological method to reflect the gel strength of the profile control and displacement system. The measurement method is in accordance with SY / T6296-1997 "Rheological parameter method for determination of gel strength of polymers used in oil production" and the testing instrument is HAAKE RS6000 rheometer.

[0169] 6) Dehydration Rate of the Control and Flooding System: The copolymer gel solution formed by the copolymer and cross-linking agent is placed in a sealed stainless steel reactor and then placed in a thermostat at a certain temperature (e.g., 150°C) for reaction. After a set period of time (e.g., 90 days), the solution is removed from the thermostat and allowed to cool. The mass of the dehydrated water is measured using a scale. The ratio of the mass of the dehydrated water to the mass of the initial gel solution is the dehydration rate. The dehydration rate is used to reflect the thermal stability of the control and flooding system; a lower dehydration rate indicates greater stability.

[0170] Example 1

[0171] (1) Take 86.5g of monomer A', 27.8g of monomer B', 5g of monomer C', and 0.6g of monomer D', wherein monomer A' is sodium 2-acrylamido-2-methylpropanesulfonate; monomer B' is acrylamide; the structural formula of monomer C' is shown in Formula 3, wherein R8, R9 and R 10 are all H; the structural formula of monomer D′ is shown in Formula 4, wherein R 11 H, R 12 、R 13 and R14 are all methyl groups; 9 g of sodium dodecyl sulfate was added and dissolved in 171.1 g of deionized water, and the pH value was adjusted to 6 with sodium hydroxide solution, the starting temperature was controlled at 2°C, 0.3 g of a defoamer was added, and nitrogen was bubbled into the system for 20 minutes to deoxygenate, followed by the addition of 1 g of a 0.25 wt% aqueous solution of 2,2-azobis(2-amidinopropane) dihydrochloride, 2 g of a 0.2 wt% aqueous solution of ammonium persulfate, and 1.5 g of a 0.3 wt% aqueous solution of sodium bisulfite to the system to initiate polymerization. After the system temperature rose by 0.5°C, the nitrogen bubble was stopped and the reaction was continued for 4 hours;

[0172] (2) After the polymerization is completed, the obtained colloid is granulated, dried at 50° C. until the solid content reaches 89% by weight, and then crushed and sieved to obtain a sulfonic acid copolymer dry powder product.

[0173] The viscosity average molecular weight of the dry powder product was determined to be 14.8 million.

[0174] In addition, according to the calculation and determination of the feeding amount, the prepared sulfonic acid type copolymer contains:

[0175] Structural unit A (as shown in formula I, wherein R1 and R2 are both H, R3 and R4 are both methyl, R5 is methylene, and R6 is Na); structural unit B (as shown in formula II, wherein R7 is H); structural unit C (as shown in formula III, wherein R8, R9 and R 10 are H); structural unit D (as shown in formula IV, wherein R 11 H, R 12 、R 13 and R 14 are all methyl groups);

[0176] Wherein, based on the total weight of the sulfonic acid copolymer, the content of the structural unit A is 72.1% by weight, the content of the structural unit B is 23.2% by weight, the content of the structural unit C is 4.2% by weight, and the content of the structural unit D is 0.5% by weight; wherein, in the structural unit A, the molar content of S is 4.9%, and the weight content of the sulfonic acid group is 25.2% by weight; the molar content of CO-CO- in the tertiary carbonate group of the structural unit D accounts for 0.27% of all C chemical bonds, and the weight content of the tertiary carbonate group is 0.39% by weight.

[0177] According to the aforementioned method for detecting structural units contained in the polymer, X-ray photoelectron spectroscopy (XPS) was used to detect the polymer, and the atomic ratio of C, N, O, and S was 11.1:2.5:5.6:1. Based on the total weight of the elements in the sulfonic acid copolymer, the molar content of S in structural unit A was 4.95%, the weight content of sulfonic acid groups was 25.4% by weight, and the molar content of CO-CO- in the tertiary carbonate groups of structural unit D was 0.28% of all carbon bonds, and the weight content of tertiary carbonate groups was 0.41% by weight. As can be seen from the above, the above detection results are similar to those calculated based on the feed amount.

[0178] The sulfonic acid copolymer powder product obtained in step (2) was washed with acetic acid to remove unreacted monomers, and then detected using a TENSOR 27 infrared spectrometer (Bruker, Germany) to obtain an infrared spectrum as shown in FIG1 . As can be seen from FIG1 , 3430 cm -1 The stretching vibration peaks of -NH2 and -NH in structural units B and C are 2980cm -1 and 2920cm -1 The antisymmetric and symmetric contraction vibration peaks of -CH3 and -CH2 in structural units A and D are at 2780cm -1 The stretching vibration peak of CH in the aldehyde group of the structural unit C is 1670 cm -1 -C=O stretching vibration peak of structural unit A, structural unit B, and structural unit C, 1540 cm -1 The characteristic absorption peak of the secondary amide -CONH-C- in the structural unit A is 1450 cm -1 and 1390cm -1 The peak at 1200 cm is the bending vibration peak of the CH of the -CH3 group in the structural unit A. -1 and 1030cm -1 The antisymmetric and symmetric contraction vibration peaks of COC in the structural unit D are at 1110 cm -1 The peak at is the stretching vibration peak of S=O in the structural unit A, confirming that the obtained copolymer is composed of four structural units.

[0179] Example 2

[0180] (1) 95 g of monomer A′, 24 g of monomer B′, 6 g of monomer C′, and 1.2 g of monomer D′ are taken, wherein monomer A′ is sodium 2-acrylamido-2-methylpropanesulfonate; monomer B′ is acrylamide; the structural formula of monomer C′ is shown in Formula 3, wherein R8 and R9 are both H, R 10 is methyl; the structural formula of monomer D' is shown in Formula 4, wherein R 11 H, R 12is methyl, R 13 is n-pentyl, R 14 6.5 g of sodium lauryl sulfate was dissolved in 173.8 g of deionized water, and the pH value was adjusted to 6 with sodium hydroxide solution. The starting temperature was controlled at 8° C., 0.4 g of a defoamer was added, and nitrogen was bubbled into the system for 20 minutes to deoxygenate. Then, 1.4 g of a 0.25 wt % aqueous solution of 2,2-azobis(2-amidinopropane) dihydrochloride, 2 g of a 0.2 wt % aqueous solution of ammonium persulfate, and 1.7 g of a 0.3 wt % aqueous solution of sodium bisulfite were added to the system to initiate polymerization. After the system temperature rose by 0.5° C., the nitrogen bubble was stopped and the reaction was continued for 4 hours.

[0181] (2) After the polymerization is completed, the obtained colloid is granulated, dried at 50° C. until the solid content reaches 89% by weight, and then crushed and sieved to obtain a sulfonic acid copolymer dry powder product.

[0182] The viscosity average molecular weight of the dry powder product was determined to be 12.45 million.

[0183] In addition, according to the calculation and determination of the feeding amount, the prepared sulfonic acid type copolymer contains:

[0184] Structural unit A (same as in Example 1);

[0185] Structural unit B (same as in Example 1);

[0186] Structural unit C (as shown in formula III, wherein R8 and R9 are both H, R 10 is methyl);

[0187] Structural unit D (as shown in formula IV, wherein R 11 H, R 12 is methyl, R 13 is n-pentyl, R 14 is methyl);

[0188] Wherein, based on the total weight of the sulfonic acid copolymer, the content of the structural unit A is 75.3% by weight, the content of the structural unit B is 19.0% by weight, the content of the structural unit C is 4.75% by weight, and the content of the structural unit D is 0.95% by weight; wherein, in the structural unit A, the molar content of S is 5.2%, and the weight content of the sulfonic acid group is 26.3% by weight; the molar content of CO-CO- in the tertiary carbonate group of the structural unit D accounts for 0.35% of all C chemical bonds, and the weight content of the tertiary carbonate group is 0.81% by weight.

[0189] According to the aforementioned method for detecting the structural units contained in the polymer, the polymer was detected using an X-ray photoelectron spectrometer (XPS), and the detection result was close to the result calculated based on the feed amount.

[0190] Example 3

[0191] (1) 91.7 g of monomer A′, 14.8 g of monomer B′ acrylamide, 6.5 g of monomer C′, and 0.3 g of monomer D′ were taken, wherein monomer A′ and monomer B′ were the same as those in Example 1; monomer C′ was the same as that in Example 1; the structural formula of monomer D′ was shown in Formula 4, wherein R 11 H, R 12 is methyl, R 13 is n-hexyl, R 14 6.6 g of Tween 80 was dissolved in 180.1 g of deionized water, and the pH value was adjusted to 6 with sodium hydroxide solution. The initial temperature was controlled at 5° C., 0.2 g of a defoamer was added, and nitrogen was bubbled into the system for 20 minutes to deoxygenate. Then, 1 g of a 0.25 wt % aqueous solution of 2,2-azobis(2-amidinopropane) dihydrochloride, 2 g of a 0.2 wt % aqueous solution of ammonium persulfate, and 1.8 g of a 0.3 wt % aqueous solution of sodium bisulfite were added to the system to initiate polymerization. After the system temperature rose by 0.5° C., the nitrogen bubble was stopped and the reaction was continued for 4 hours.

[0192] (2) After the polymerization is completed, the obtained colloid is granulated, dried at 50° C. until the solid content reaches 89% by weight, crushed and sieved to obtain an acrylamide copolymer dry powder product.

[0193] The viscosity average molecular weight of the dry powder product was determined to be 14.32 million.

[0194] In addition, according to the calculation and determination of the feeding amount, the prepared sulfonic acid type copolymer contains:

[0195] Structural unit A (same as in Example 1); Structural unit B (same as in Example 1);

[0196] Structural unit C (same as in Example 1);

[0197] Structural unit D (as shown in formula IV, wherein R 11 H, R 12 is methyl, R 13 is n-hexyl, R 14 is methyl);

[0198] Wherein, based on the total weight of the sulfonic acid copolymer, the content of the structural unit A is 80.9% by weight, the content of the structural unit B is 13.1% by weight, the content of the structural unit C is 5.7% by weight, and the content of the structural unit D is 0.3% by weight; wherein, in the structural unit A, the molar content of S is 5.6%, and the weight content of the sulfonic acid group is 28.3% by weight; the molar content of CO-CO- in the tertiary carbonate group of the structural unit D accounts for 0.11% of all C chemical bonds, and the weight content of the tertiary carbonate group is 0.26% by weight.

[0199] According to the aforementioned method for detecting the structural units contained in the polymer, the polymer was detected using an X-ray photoelectron spectrometer (XPS), and the detection result was close to the result calculated based on the feed amount.

[0200] Example 4

[0201] (1) 84.9 g of monomer A′ (same as in Example 1), 31.3 g of monomer B′ (methacrylamide), 2.4 g of monomer C′ (same as in Example 1), 1.7 g of monomer D′ (same as in Example 1), and 17 g of sodium lauryl sulfate were dissolved in 162.7 g of deionized water, and the pH value was adjusted to 6 with sodium hydroxide solution. The initial temperature was controlled at 2° C. 0.5 g of a defoamer was added, and nitrogen was bubbled into the system for 20 minutes to remove oxygen. Then, 1.15 g of a 0.25 wt % aqueous solution of 2,2-azobis(2-amidinopropane) dihydrochloride, 2 g of a 0.2 wt % aqueous solution of ammonium persulfate, and 1.5 g of a 0.3 wt % aqueous solution of sodium bisulfite were added to the system to initiate polymerization. After the system temperature rose by 0.5° C., the nitrogen bubble was stopped and the reaction was continued for 4 hours.

[0202] (2) After the polymerization is completed, the obtained colloid is granulated, dried at 50° C. until the solid content reaches 89% by weight, crushed and sieved to obtain an acrylamide copolymer dry powder product.

[0203] The viscosity average molecular weight of the dry powder product was determined to be 17 million.

[0204] In addition, according to the calculation and determination of the feeding amount, the prepared sulfonic acid type copolymer contains:

[0205] Structural unit A (same as in Example 1); structural unit B (as shown in Formula II, wherein R7 is methyl);

[0206] Structural unit C (same as in Example 1); Structural unit D (same as in Example 1);

[0207] Wherein, based on the total weight of the sulfonic acid copolymer, the content of the structural unit A is 70.6% by weight, the content of the structural unit B is 26% by weight, the content of the structural unit C is 2% by weight, and the content of the structural unit D is 1.4% by weight; wherein, in the structural unit A, the molar content of S is 4.8%, and the content of the sulfonic acid group is 24.7% by weight; the molar content of CO-CO- in the tertiary carbonate group of the structural unit D accounts for 0.73% of all C chemical bonds, and the weight content of the tertiary carbonate group is 1.1% by weight.

[0208] According to the aforementioned method for detecting structural units contained in the polymer, the polymer was tested using X-ray photoelectron spectroscopy (XPS). The data are shown in Tables 1-3 and Figures 2, 3a, and 3b. The calculated atomic ratio of C, N, O, and S is 11.3:1.7:4.8:1. Based on the total weight of the elements in the sulfonic acid copolymer, the molar content of S in structural unit A is 4.9%, the content of sulfonic acid groups is 25.2% by weight, the molar content of CO-CO- in the tertiary carbonate groups of structural unit D accounts for 0.78% of all carbon bonds, and the weight content of tertiary carbonate is 1.18% by weight. As can be seen from the above, the test results are similar to those calculated based on the feed amount.

[0209] Example 5

[0210] (1) 100.1 g of monomer A′ (same as in Example 1), 12 g of monomer B′ (same as in Example 1), 7.8 g of monomer C′ (same as in Example 1), 0.1 g of monomer D′ (same as in Example 1), and 1 g of sodium lauryl sulfate were dissolved in 179 g of deionized water, and the pH value was adjusted to 6 with sodium hydroxide solution. The initial temperature was controlled at 2° C. 0.15 g of a defoamer was added, and nitrogen was bubbled into the system for 20 min to remove oxygen. Then, 1.3 g of a 0.25 wt % aqueous solution of 2,2-azobis(2-amidinopropane) dihydrochloride, 2.2 g of a 0.2 wt % aqueous solution of ammonium persulfate, and 1.7 g of a 0.3 wt % aqueous solution of sodium bisulfite were added to the system to initiate polymerization. After the system temperature rose by 0.5° C., the nitrogen bubble was stopped and the reaction was continued for 4 hours.

[0211] (2) After the polymerization is completed, the obtained colloid is granulated, dried at 50° C. until the solid content reaches 89% by weight, and then crushed and sieved to obtain a sulfonic acid copolymer dry powder product.

[0212] The viscosity average molecular weight of the dry powder product was determined to be 11.5 million.

[0213] In addition, according to the calculation and determination of the feeding amount, the prepared sulfonic acid type copolymer contains:

[0214] Structural unit A (same as in Example 1); Structural unit B (same as in Example 1);

[0215] Structural unit C (same as in Example 1); Structural unit D (same as in Example 1);

[0216] Wherein, based on the total weight of the sulfonic acid copolymer, the content of the structural unit A is 83.4% by weight, the content of the structural unit B is 10% by weight, the content of the structural unit C is 6.5% by weight, and the content of the structural unit D is 0.1% by weight; wherein, in the structural unit A, the molar content of S is 5.8%, the content of the sulfonic acid group is 29.1% by weight; the molar content of CO-CO- in the tertiary carbonate group accounts for 0.06% of all C chemical bonds, and the weight content of the tertiary carbonate group is 0.08% by weight.

[0217] According to the aforementioned method for detecting the structural units contained in the polymer, the polymer was detected using an X-ray photoelectron spectrometer (XPS), and the detection result was close to the result calculated based on the feed amount.

[0218] Example 6

[0219] A copolymer was prepared in the same manner as in Example 4, except that the amount of monomer A' added was 71.8 g and the amount of monomer B' added was 42.5 g. The viscosity-average molecular weight of the copolymer was 17.6 million.

[0220] In addition, according to the calculation determined by the feeding amount, the prepared copolymer contains the same structural unit A, structural unit B, structural unit C and structural unit D as in Example 4; based on the total weight of the copolymer, the content of the structural unit A is 60.6% by weight, the content of the structural unit B is 35.9% by weight, the content of the structural unit C is 2.0% by weight, and the content of the structural unit D is 1.4% by weight; wherein, in the structural unit A, the molar content of S is 4.1%, and the content of the sulfonic acid group is 21.2% by weight; the molar content of CO-CO- in the tertiary carbonate group accounts for 0.70% by weight of all C chemical bonds, and the weight content of the tertiary carbonate group is 1.1% by weight.

[0221] According to the aforementioned method for detecting the structural units contained in the polymer, the polymer was detected using an X-ray photoelectron spectrometer (XPS), and the detection result was close to the result calculated based on the feed amount.

[0222] Comparative Example D1

[0223] A copolymer was prepared in the same manner as in Example 4, except that 31.3 g of monomer A' and 84.9 g of monomer B' were added. Monomers C' and D' were omitted. The viscosity-average molecular weight of the copolymer was 18.4 million.

[0224] Furthermore, the prepared copolymer, calculated based on the feed amounts, contained the same structural units A and B as those in Example 4. Based on the total weight of the copolymer, the content of structural unit A was 26.9% by weight, and the content of structural unit B was 73.1% by weight. In structural unit A, the molar content of S was 1.7%, and the content of sulfonic acid groups was 9.4% by weight.

[0225] Comparative Example D2

[0226] A copolymer was prepared in the same manner as in Example 4, except that monomer C' was not added. The viscosity-average molecular weight of the copolymer was 15.26 million.

[0227] In addition, according to the calculation determined by the feed amount, the prepared copolymer contains the same structural unit A, structural unit B, and structural unit D as in Example 4; based on the total weight of the copolymer, the content of the structural unit A is 72.0% by weight, the content of the structural unit B is 26.6% by weight, and the content of the structural unit D is 1.4% by weight; wherein, the molar content of S contained in the structural unit A is 4.9%, the content of the sulfonic acid group is 25.2% by weight, and the content of the tertiary carbonate group is 1.1% by weight.

[0228] Comparative Example D3

[0229] A copolymer was prepared in the same manner as in Example 4, except that monomer D' was not added. The viscosity average molecular weight of the copolymer was 16.2 million.

[0230] Furthermore, the prepared copolymer, calculated based on the feed amounts, contained the same structural units A, B, and C as those in Example 4. Based on the total weight of the copolymer, the content of structural unit A was 71.6% by weight, the content of structural unit B was 26.4% by weight, and the content of structural unit C was 2.0% by weight. The molar content of S in structural unit A was 4.9%, and the content of sulfonic acid groups was 25.0% by weight.

[0231] Comparative Example D4

[0232] A copolymer was prepared in the same manner as in Example 4, except that monomer D' was replaced with vinyl acetate. The viscosity-average molecular weight of the copolymer was 15.65 million.

[0233] In addition, according to the calculation of the feed amount, the prepared copolymer contains the same structural unit A, structural unit B, structural unit C and structural unit derived from vinyl acetate as in Example 4. Based on the total weight of the copolymer, the content of structural unit A was 70.6 wt %, the content of structural unit B was 26 wt %, the content of structural unit C was 2.0 wt %, and the content of structural units derived from vinyl acetate was 1.4 wt %.

[0234] Figure 2 and Table 1 are the X-ray photoelectron spectrum and element contents of the sulfonic acid copolymer obtained in Example 4. As can be seen from Figure 2 and Table 1, the C, N, O, S, and Na obtained by X-ray photoelectron spectroscopy are basically consistent with the feed amount.

[0235] Table 1 Element content of sulfonic acid copolymer obtained in Example 4

[0236] In Figures 3a and 3b, 1 is the C1s and O1s fine spectrum of a sulfonic acid copolymer containing only structural units A and B, 2 is the C1s and O1s fine spectrum of a sulfonic acid copolymer containing only structural units A, B, and C, obtained in Comparative Example D3, and 3 is the C1s and O1s fine spectrum of a sulfonic acid copolymer containing structural units A, B, C, and D, obtained in Example 4. Tables 2 and 3 show the atomic ratios of the corresponding functional groups. As can be seen in Figure 3a, the characteristic peak of the ester group COC=O in structural unit D is clearly visible at a binding energy of 288.84 eV; as can be seen in Figure 3b, the characteristic peak of the ester group OC=O in structural unit D is clearly visible at a binding energy of 532.95 eV.

[0237] Table 2 Atomic ratios of various C-containing functional groups in the C1s spectrum

[0238] Table 3 Atomic ratios of various oxygen-containing functional groups in the O1s spectrum

[0239] Curve a in FIG4 is an infrared spectrum of the sulfonic acid copolymer obtained in Example 4; Curve b is an infrared spectrum of the sulfonic acid copolymer obtained in Comparative Example D3; As can be seen from FIG4, curve b at 1200 cm -1 and 1030cm -1 There are obvious peaks at the center, which are the antisymmetric contraction vibration and symmetric contraction vibration peaks of COC in the structural unit D.

[0240] Test Example 1

[0241] The copolymers prepared in Examples 1-6 and Comparative Examples D1-D4 were prepared into 5000 mg / L copolymer solutions (prepared in deionized water). After being placed at 130° C. for 15-60 days, the total hydrolysis rate and total hydrolysis rate growth rate of the copolymers, as well as the hydrolysis rate and hydrolysis growth rate of structural unit B were measured. The results are shown in Tables A1-A2.

[0242] Table A1 Total hydrolysis rate and total hydrolysis growth rate of copolymers aged at 130°C

[0243] Table A2 Hydrolysis rate and hydrolysis growth rate of the structural units containing amide groups in the copolymer after aging at 130°C

[0244] The results in Tables A1-A2 show that, compared to the comparative examples, the sulfonic acid copolymers prepared in Examples 1-6 of the present invention, which primarily comprise sulfonic acid groups containing long-chain branches as their primary building blocks, exhibit strong hydrolysis resistance at 130°C and a controllable hydrolysis rate. Initially, the crosslinking group release rate is low, with a total hydrolysis rate of no more than 20% over 15 days, particularly for the structural units containing amide groups, which has a 15-day hydrolysis rate of no more than 15%. With increasing aging time, the crosslinking groups are gradually released, with a total hydrolysis rate of no less than 90% from 15 to 60 days, particularly for the structural units containing amide groups, which has a 15-day hydrolysis rate of no less than 90%.

[0245] Application Example 1

[0246] 10 g of the copolymer obtained in Example 1 was added to 900 g of simulated brine and stirred at 600 rpm / min until completely dissolved. 0.5 g of chromium citrate and 0.8 g of chromium lactate were added and stirred until completely dissolved. 0.8 g of sodium thiosulfate was added and the mixture was made up to a total weight of 1 kg with simulated brine. The mixture was stirred evenly to obtain a copolymer flooding system, which can be used as a flow regulating agent for flow channel adjustment.

[0247] Two types of salinity and calcium and magnesium ion contents were selected for the simulated brine. The salinity of the first simulated brine was 300,000 mg / L and the calcium and magnesium ion content was 10,000 mg / L. The salinity of the second simulated brine was 100,000 mg / L and the calcium and magnesium ion content was 5,000 mg / L.

[0248] Profile adjustment and displacement system A1, prepared with simulated brine having a salinity of 300,000 mg / L and a calcium and magnesium ion content of 10,000 mg / L, had an initial viscosity of 680 mPa·s. Aged viscosities after 60 days at 70°C, 95°C, and 130°C were measured, and the results are shown in Table A3. Simultaneously, the initial viscosity, aging viscosity after 60 days at 130°C, and viscosity increase of profile adjustment and displacement system A1 were measured, and the results are shown in Table A4.

[0249] The initial viscosity of the profile control and flooding system A1', prepared with simulated brine having a salinity of 100,000 mg / L and a calcium and magnesium ion content of 5,000 mg / L, was 910 mPa·s. The aging viscosity after 60 days at 70°C, 95°C, and 130°C was measured. The results are shown in Table A3.

[0250] Application Example 2

[0251] 8.5 g of the copolymer obtained in Example 2 was added to 900 g of simulated brine (300,000 mg / L, calcium and magnesium ion content of 10,000 mg / L), and stirred at 600 rpm / min until completely dissolved. 0.5 g of chromium citrate and 0.3 g of zirconium citrate were added and stirred until completely dissolved. 0.4 g of thiourea was added and the mixture was made up to a total weight of 1 kg with simulated brine (300,000 mg / L, calcium and magnesium ion content of 10,000 mg / L). The mixture was stirred evenly to obtain a sulfonic acid copolymer flooding system A2, which can be used as a flow regulating agent for flow channel adjustment.

[0252] The initial viscosity, aged viscosity after 60 days at 130°C, and viscosity increase of the profile control system A2 were measured. The results are shown in Table A4.

[0253] Application Example 3

[0254] 9 g of the copolymer obtained in Example 3 was added to 900 g of simulated brine (300,000 mg / L, calcium and magnesium ion content of 10,000 mg / L), stirred for 1 hour, and then 0.3 g of aluminum citrate, 1 g of chromium lactate, and 0.8 g of sodium bisulfite were added. The mixture was made up to a total weight of 1 kg with simulated brine (300,000 mg / L, calcium and magnesium ion content of 10,000 mg / L), and stirred evenly to obtain a sulfonic acid copolymer flooding system A3. This flooding system can be used as a flow regulating agent for flow channel adjustment.

[0255] The initial viscosity, aged viscosity after 60 days at 130°C, and viscosity increase of the profile control system A3 were measured. The results are shown in Table A4.

[0256] Application Example 4

[0257] 10 g of each copolymer obtained in Examples 4-6 and Comparative Examples D1-D4 was added to 900 g of simulated saline (300,000 mg / L, calcium and magnesium ion content of 10,000 mg / L) and stirred at 600 rpm / min until completely dissolved. 0.5 g of chromium citrate and 0.8 g of chromium lactate were then added and stirred until completely dissolved. 0.8 g of sodium thiosulfate was then added and the mixture was brought to a total weight of 1 kg with simulated saline (300,000 mg / L, calcium and magnesium ion content of 10,000 mg / L). The mixture was then stirred evenly to obtain copolymer adhesive flooding systems A4-A6 and AD1-AD4. The flooding systems obtained above can be used as flow control agents for flow channel adjustment.

[0258] The initial viscosity of the above-obtained profile control systems A4-A6 and AD1-AD4 was measured, and the aged viscosity and viscosity increase rate after being placed at 130°C for 60 days were respectively measured. The results are shown in Table A4.

[0259] Application Example 5

[0260] 9 g of the copolymer prepared in Example 1 was added to 900 g of simulated saline and stirred at 600 rpm / min until completely dissolved. 4 g of hydroquinone and 5 g of hexamethylenetetramine were added and stirred until completely dissolved. 0.8 g of sodium thiosulfate was added and the total weight was made up to 1 kg with simulated saline. The mixture was stirred evenly to obtain a copolymer glue solution adjustment and displacement system B1.

[0261] Two types of salinity and calcium and magnesium ion contents were selected for the simulated brine. The salinity of the first simulated brine was 300,000 mg / L and the calcium and magnesium ion content was 10,000 mg / L. The salinity of the second simulated brine was 100,000 mg / L and the calcium and magnesium ion content was 5,000 mg / L.

[0262] The storage modulus and dehydration rate of the control and displacement system B1, prepared with simulated brine having a salinity of 300,000 mg / L and a calcium and magnesium ion content of 10,000 mg / L, were measured after being stored at 140-160°C for 90 days. The results are shown in Table A5. The storage modulus and dehydration rate of the control and displacement system B1 were also measured after being stored at 150°C for 90 days. The results are shown in Table A6.

[0263] The storage modulus and dehydration rate of the profile control and flooding system B1' prepared with simulated brine having a salinity of 100,000 mg / L and a calcium and magnesium ion content of 5,000 mg / L were measured after being stored at 140-160°C for 90 days. The results are shown in Table A5.

[0264] Application Example 6

[0265] 12 g of the copolymer obtained in Example 2 was added to 900 g of simulated brine (300,000 mg / L, calcium and magnesium ion content of 10,000 mg / L), and stirred at 600 rpm / min until completely dissolved. 5.5 g of catechol and 5 g of hexamethylenetetramine were added and stirred until completely dissolved. 0.9 g of isoascorbic acid was added, and the mixture was made up to a total weight of 1 kg with simulated brine (300,000 mg / L, calcium and magnesium ion content of 10,000 mg / L). The mixture was stirred evenly to obtain a copolymer flooding system B2, which can be used as a plugging agent for water plugging.

[0266] The storage modulus and dehydration rate of the control and flooding system were measured after being placed at 150° C. for 90 days. The results are shown in Table A6.

[0267] Application Example 7

[0268] 11 g of the copolymer obtained in Example 3 was added to 900 g of simulated brine (300,000 mg / L, calcium and magnesium ion content of 10,000 mg / L), and stirred at 600 rpm / min until completely dissolved. Then, 5 g of hydroquinone and 6 g of hexamethylenetetramine were added and stirred until completely dissolved. Then, 0.9 g of thiourea was added and the mixture was made up to a total weight of 1 kg with simulated brine (300,000 mg / L, calcium and magnesium ion content of 10,000 mg / L). The mixture was stirred evenly to obtain a sulfonic acid copolymer flooding system B3, which can be used as a plugging agent for water plugging.

[0269] The storage modulus and dehydration rate of the control and flooding system were measured after being placed at 150° C. for 90 days. The results are shown in Table A6.

[0270] Application Example 8

[0271] 9g of the copolymers prepared in Examples 4-6 and Comparative Examples D1-D4 were added to 900g of simulated brine (mineralization of 300,000 mg / L, calcium and magnesium ion content of 10,000 mg / L) and stirred at 600 rpm / min until completely dissolved. 4g of hydroquinone and 5g of hexamethylenetetramine were added and stirred until completely dissolved. 0.8g of sodium thiosulfate was added and the mixture was made up to a total weight of 1kg with simulated brine (mineralization of 300,000 mg / L, calcium and magnesium ion content of 10,000 mg / L). The mixture was stirred evenly to obtain copolymer glue flooding systems B4-B6 and BD1-BD4. The flooding systems obtained above can be used as plugging agents for water plugging.

[0272] The storage modulus and dehydration rate of the above-obtained flooding systems B4-B6 and BD1-BD4 were measured after being stored at 150°C for 90 days. The results are shown in Table A6.

[0273] Table A3 Viscosity of the profiled flooding systems A1 and A1' after aging for 60 days

[0274] Table A4 Initial viscosity, aging viscosity and viscosity increase rate of the profile displacement system

[0275] The results in Tables A3 and A4 show that profile control and displacement systems A1-A6 exhibit better viscosity-increasing effects and higher viscosity-increasing rates than profile control and displacement systems AD1-AD4. Profile control and displacement systems A1-A6, formed from the sulfonic acid copolymers prepared in Examples 1-6 of the present invention and a metal crosslinker, maintain excellent viscosity and stability after aging for 60 days at 70-130°C in water with a salinity of ≤300,000 mg / L and a calcium and magnesium ion content of ≤10,000 mg / L. These systems exhibit a viscosity-increasing rate exceeding 200%, demonstrating excellent stability and potential for flow channel adjustment in carbonate reservoirs.

[0276] Table A5 Storage modulus and dehydration rate of the flooding systems B1 and B1' after aging for 90 days

[0277] Table A6 Storage modulus and dehydration rate of the flooding system

[0278] The results in Tables A5 and A6 show that controllable-hydrolysis-rate sulfonic acid copolymers prepared in Examples 1-6 of the present invention react with phenolic and aldehyde crosslinkers to form controllable-hydrolysis-rate sulfonic acid copolymers. Copolymer controllable-hydrolysis systems B1-B6 exhibit low dehydration rates and high storage modulus after aging for 90 days at 140-160°C in an environment with a salinity ≤300,000 mg / L and a calcium and magnesium ion content ≤10,000 mg / L. These systems are suitable for use as plugging agents in ultra-deep wells in carbonate reservoirs.

[0279] In summary, the copolymer of the present invention can slowly release crosslinking groups after high-temperature aging. Specifically, the crosslinking groups generated by structural units B and C in the copolymer after high-temperature aging have a slow-release function. This copolymer achieves an initial low viscosity upon initial injection into a reservoir. During migration, it continuously releases crosslinking groups through hydrolysis, crosslinking with a crosslinking agent, achieving gradual viscosity increase and ultimately maintaining a certain viscosity and strength. After high-temperature aging, it retains good viscosity and strength, maintaining long-term stability and enabling deep-level flow control. It can be used as a flow control and plugging agent in carbonate reservoirs for adjusting flow channels and plugging.

[0280] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A copolymer, characterized in that The copolymer comprises a structural unit A shown in formula I, a structural unit B shown in formula II, a structural unit C shown in formula III and a structural unit D shown in formula IV; Among them, R1, R7, R8 and R 11 Each is independently H or a C1-C6 alkyl group; R2, R9 and R 10 Each is independently H or a C1-C6 alkyl group; R3 and R4 are each independently a C1-C6 alkyl group; R5 is a C1-C6 alkylene group; R6 is H or an alkali metal element; R 12 , R 13 and R 14 are each independently a C1-C6 alkyl group, and R 12 , R 13 and R 14 At least one is a methyl group.

2. The copolymer according to claim 1, wherein R1, R7, R8 and R 11 are each independently H or methyl; and / or, R2 is H; and / or, R3 and R4 are each independently methyl; and / or, R5 is methylene; R6 is H or Na; and / or, R9 is H; and / or, R 10 is H or methyl; and / or, R 12 , R 13 and R 14 are each independently methyl; or, R 12 , R 13 and R 14 One of the substituents is methyl, and the total number of carbon atoms of the remaining two substituents is 6-8; preferably, R 12 Methyl, R 13 is n-pentyl, R 14 is methyl; or R 12 Methyl, R 13 is n-hexyl, R 14 It is methyl.

3. The copolymer according to claim 1 or 2, wherein R1, R7, R8 and R 11 R2 is H; R3 and R4 are each independently methyl; R5 is methylene; R6 is H or Na; R9 is H; R 10 is H or methyl; R 12 , R 13 and R 14 are each independently methyl.

4. The copolymer according to any one of claims 1 to 3, wherein Based on the total weight of the copolymer, the content of the structural unit D is 0.1-2 wt %; Preferably, based on the total weight of the copolymer, the content of the structural unit A is not less than 60 wt%.

5. The copolymer according to any one of claims 1 to 4, wherein Based on the total weight of the copolymer, the content of the structural unit A is 65-90 weight %; the content of the structural unit B is 5-30 weight %; the content of the structural unit C is 1-8 weight %; the content of the structural unit D is 0.1-2 weight %; Preferably, based on the total weight of the copolymer, the content of the structural unit A is 70-84 wt %; the content of the structural unit B is 12-25 wt %; the content of the structural unit C is 3-6 wt %; and the content of the structural unit D is 0.2-1 wt %.

6. The copolymer according to any one of claims 1 to 5, wherein The viscosity average molecular weight of the copolymer is 5 million to 18 million, preferably 8 million to 18 million, and more preferably 12 million to 17 million.

7. A copolymer comprising an olefin skeleton and a functional group bonded to the olefin skeleton, characterized in that: The functional groups include sulfonic acid groups, tertiary carbonate groups, amide groups and amino groups; wherein, based on the total weight of the copolymer, the weight content of the tertiary carbonate groups is 0.06-1.5 weight %; the weight content of the sulfonic acid groups is not less than 21 weight %, and the viscosity average molecular weight of the copolymer is 5 million-18 million.

8. A method for preparing a copolymer, characterized in that: The preparation method comprises: under solution polymerization conditions, in the presence of an initiator, allowing an olefinic monomer to undergo a polymerization reaction; wherein the olefinic monomer comprises a monomer Aˊ shown in formula 1, a monomer Bˊ shown in formula 2, a monomer Cˊ shown in formula 3, and a monomer Dˊ shown in formula 4; Wherein, R1, R7, R8 and R11 are each independently H or a C1-C6 alkyl group; R2, R9 and R 10 Each is independently H or a C1-C6 alkyl group; R3 and R4 are each independently a C1-C6 alkyl group; R5 is a C1-C6 alkylene group; R6 is H or an alkali metal element; R 12 , R 13 and R 14 are each independently a C1-C6 alkyl group, and R 12 , R 13 and R 14 At least one is a methyl group.

9. The preparation method according to claim 8, wherein: R1, R7, R8 and R 11 are each independently H or methyl; and / or, R2 is H; and / or, R3 and R4 are each independently methyl; and / or, R5 is methylene; R6 is H or Na; and / or, R9 is H; and / or, R 10 is H or methyl; and / or, R 12 , R 13 and R 14 are each independently methyl; or, R 12 , R 13 and R 14 One of the substituents is methyl, and the total number of carbon atoms of the remaining two substituents is 6-8; preferably, R 12 Methyl, R 13 is n-pentyl, R 14 is methyl; or R 12 Methyl, R 13 is n-hexyl, R 14 It is methyl.

10. The preparation method according to claim 8 or 9, wherein: R1, R7, R8 and R 11 R2 is H; R3 and R4 are each independently methyl; R5 is methylene; R6 is H or Na; R9 is H; R 10 is H or methyl; R 12 , R 13 and R 14 are each independently methyl.

11. The preparation method according to any one of claims 8 to 10, wherein: Based on the total weight of the olefinic monomer, the content of the monomer D is 0.1-2 wt %; Preferably, based on the total weight of the olefinic monomers, the content of the monomer A' is not less than 60 wt%.

12. The preparation method according to any one of claims 8 to 11, wherein: Based on the total weight of the olefinic monomers, the content of the monomer A is 65-90% by weight, the content of the monomer B is 5-30% by weight, the content of the monomer C is 1-8% by weight, and the content of the monomer D is 0.1-2% by weight; Preferably, based on the total weight of the olefinic monomers, the content of the monomer A' is 70-84 wt%, the content of the monomer B' is 12-25 wt%, the content of the monomer C' is 3-6 wt%, and the content of the monomer D' is 0.2-1 wt%.

13. The preparation method according to any one of claims 8 to 12, wherein: The initiator is used in an amount of 0.0003-0.05 wt % of the weight of the ethylenic monomer; And / or, the initiator is selected from azo initiators and / or redox initiators.

14. The preparation method according to any one of claims 8 to 13, wherein: The solution polymerization reaction conditions include: a starting temperature of -10°C to 30°C, a reaction time of 2-12 hours, and a pH value of 4-8.

15. A copolymer obtained by the preparation method according to any one of claims 8 to 14.

16. A control and displacement system, characterized in that: The flooding system contains a crosslinking agent and the copolymer described in any one of claims 1 to 6, 7 and 15.

17. The control and displacement system according to claim 16, wherein: In the displacement system, the content of the copolymer is 0.3-1.5% by weight.

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