A high-temperature and high-salt resistant polymer and its preparation and application

Abstract

This invention discloses a high-temperature, high-salt resistant polymer and its preparation and application, belonging to the field of oilfield chemistry. The preparation method of the high-temperature, high-salt resistant polymer includes the following steps: copolymerizing acrylamide (AM) and 2-acrylamide-2-methylpropanesulfonic acid (AMPS) using a redox initiation system to obtain the high-temperature, high-salt resistant polymer; wherein the redox initiation system includes a phosphazene compound as a reducing agent and a peroxide as an oxidizing agent. The polymer of this invention exhibits high viscosity under high-temperature, high-salt conditions and can be used as an oil displacement agent in high-temperature, high-salt crude oil reservoirs, thereby further improving oil recovery.

Description

Technical Field

[0001] This invention belongs to the field of oilfield chemistry, specifically relating to a high-temperature and high-salt resistant polymer and its preparation and application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Currently, the temperature of developed crude oil reservoirs is between 50℃ and 85℃, and the salinity is between 5000 and 30000 mg / L, resulting in high crude oil recovery rates and significant economic benefits. However, with continuous crude oil extraction, undeveloped reservoirs face the challenge of higher temperatures (85-120℃) and higher salinity (30000-100000 mg / L). Current oil displacement agents, especially polyacrylamide-based agents, undergo severe hydrolysis under these high-temperature conditions, subsequently forming strong complexes with calcium and magnesium ions at high salinity, even leading to precipitation. The extreme coiling of molecular chains under high salinity conditions also results in significant viscosity loss, negating the high viscoelasticity required of an oil displacement agent. Furthermore, current oil displacement agents also suffer from poor long-term thermal stability under high-temperature conditions, reducing the sweep efficiency of the displacement polymer and thus significantly decreasing crude oil recovery rates. Therefore, their effectiveness in oil displacement under high-temperature and high-salinity conditions is extremely limited. To improve the temperature resistance of polymers, high contents of 2-acrylamide-2-methylpropanesulfonic acid (AMPS) are often introduced to copolymerize with acrylamide (AM). As disclosed in "Synthesis and Properties of Temperature and Salt Resistant Acrylamide Copolymers", current initiators are suitable for copolymerization with low AMPS content, but cannot be used for polymerization with a content of more than 40%, or the products after initiation polymerization are difficult to obtain high viscosity under high temperature and high salt conditions, thus restricting the progress of chemical oil displacement technology.

[0004] Phosphazene compounds, also known as phosphazene bases, are organic compounds containing the p=n group. They are commonly used as basic catalysts in the polymerization of cyclic ester monomers, cyclosiloxanes, isocyanates, epoxides, and acrylates, achieving excellent results. These reactions require stringent anhydrous and oxygen-free polymerization conditions, necessitating strict dehydration of all monomers. This complex process makes them unsuitable for the production of cost-sensitive oil displacement polymers, significantly limiting the application range of phosphazene compounds. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a high-temperature and high-salt resistant polymer, its preparation, and its application. The invention describes a method for preparing a water-soluble, high-temperature and high-salt resistant polymer by copolymerizing acrylamide (AM) and 2-acrylamide-2-methylpropanesulfonic acid (AMPS) in an aqueous solution using a redox system composed of phosphazene compounds and peroxides. The polymer of this invention exhibits high viscosity under high-temperature and high-salt conditions and can be used as an oil displacement agent in high-temperature and high-salt crude oil reservoirs, thereby further improving oil recovery.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing a high-temperature and high-salt resistant polymer, comprising the following steps:

[0008] A high-temperature and high-salt resistant polymer was prepared by copolymerizing acrylamide (AM) and 2-acrylamide-2-methylpropanesulfonic acid (AMPS) using a redox initiation system; wherein the redox initiation system includes a phosphazene compound as a reducing agent and a peroxide as an oxidizing agent.

[0009] Secondly, a high-temperature and high-salt resistant polymer is obtained by the above preparation method.

[0010] The structural formula of the high-temperature and high-salt resistant polymer is as follows:

[0011]

[0012] In the formula, x and y represent the degree of aggregation.

[0013] Thirdly, the present invention provides the application of the above-mentioned high-temperature and high-salt resistant polymer in oil fields.

[0014] Fourthly, an oil displacement agent for crude oil reservoirs includes the aforementioned high-temperature and high-salt resistant polymer.

[0015] One or more of the above technical solutions have the following advantages or beneficial effects:

[0016] (1) This invention provides a redox initiation system composed of a phosphazene compound rich in nitrogen-methyl groups and a peroxide. The P=N bond alters the electron configuration of the nitrogen-methyl groups, making it easier for phosphazene molecules to generate free radicals. Furthermore, the presence of multiple nitrogen-methyl groups on a single molecule effectively increases the molecular weight of the polymer, ensuring high viscosity at high temperatures. Simultaneously, it expands the polymer molecule volume, making it less prone to curling under high salinity conditions, thus ensuring the polymer's viscoelasticity and consequently guaranteeing a high oil recovery rate. This initiation system operates under mild reaction conditions; simple deoxygenation in water can effectively initiate the copolymerization of up to 80% AMPS and AM. The polymer exhibits high viscosity and long-term thermal stability under high temperature and high salinity conditions, while the reaction conditions are extremely relaxed, making it perfectly suitable for current industrial production and possessing promising prospects for industrialization.

[0017] (2) The redox initiation system based on phosphazene compounds and peroxides described in this invention can obtain copolymers with an AMPS content of up to 80%. The polymerization system has simple synthesis conditions, low equipment requirements, is suitable for current production conditions, and is easy to industrialize.

[0018] (3) The redox initiation system based on phosphazene compounds and peroxides provided by the present invention exhibits higher viscosity under low concentration and high mineralization conditions compared with traditional initiation systems (such as redox initiation system composed of potassium persulfate and sodium bisulfite, and azobisisobutylamidine hydrochloride initiator).

[0019] (4) The copolymer prepared by the present invention exhibits high viscosity under high temperature and high salinity conditions, and its high viscoelasticity can effectively improve the oil recovery rate of the reservoir. In the case of Shengli Oilfield, an 8% increase in recovery rate could increase reserves by more than 56 million tons, demonstrating broad application prospects. Therefore, polymer products prepared using the redox initiation system formed by the phosphazene compound and peroxide described in this invention can drive industrial upgrading in the oilfield chemicals industry, expand the application scope of phosphazene compounds, reduce the stringent conditions required for the reaction, promote the transformation of old and new growth drivers, increase crude oil production, and reduce extraction costs. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 The infrared spectrum of copolymer 11# prepared in Example 11 of this invention;

[0022] Figure 2 The NMR spectrum of copolymer 11# prepared in Example 11 of this invention;

[0023] Figure 3 The relationship between apparent viscosity and concentration in a mineralized aqueous solution of copolymer 10# prepared in Example 10 of the present invention at room temperature and 58002 mg / L.

[0024] Figure 4 The apparent viscosity of copolymers 10#, 11# and 12# prepared in Examples 10, 11 and 12 of this invention is shown as the relationship between temperature and the apparent viscosity of the copolymers 10#, 11# and 12# prepared in a 58002 mg / L mineralized aqueous solution.

[0025] Figure 5 The copolymer 11# prepared in Example 11 of this invention was subjected to a temperature of 40°C and a shear rate of 6 s. -1 Viscosity of pure aqueous solutions of different concentrations;

[0026] Figure 6 This invention illustrates the effect of the AMPS ratio in the copolymer prepared in Comparative Example 1 on the apparent viscosity of the product aqueous solution. Detailed Implementation

[0027] In view of the problems in the existing technology, such as the difficulty in obtaining high viscosity under high temperature and high salinity conditions, or the inability to achieve high content AMPS polymerization under high temperature resistance, the present invention proposes a method for preparing water-soluble temperature and salt resistant polymers by using a redox system composed of phosphazene compounds and peroxides to initiate the copolymerization of acrylamide (AM) and 2-acrylamide-2-methylpropanesulfonic acid (AMPS). The prepared polymer has high viscosity under high temperature and high salinity conditions and can be used as an oil displacement agent for Class III to Class V crude oil reservoirs, thereby further improving the oil recovery rate.

[0028] A typical embodiment of the present invention provides a method for preparing a high-temperature and high-salt resistant polymer, comprising the following steps:

[0029] A high-temperature and high-salt resistant polymer was prepared by copolymerizing acrylamide (AM) and 2-acrylamide-2-methylpropanesulfonic acid (AMPS) using a redox initiation system; wherein the redox initiation system includes a phosphazene compound as a reducing agent and a peroxide as an oxidizing agent.

[0030] In some embodiments of this implementation, the phosphazene compound is selected from... One or more of the following;

[0031] Preferably, the phosphazene compound is When R1 is R2 and R3 are each independently -NH2. Besides the groups R2 and R3, R4 can also be any one of hydrogen, a benzene ring, methyl, ethyl, or -C6H4-4-OCH3, that is, R4 is selected from -NH2, Hydrogen, benzene ring, methyl, ethyl or -C6H4-4-OCH3.

[0032] Preferably, the phosphazene compound is When R is

[0033] More preferably, the phosphazene compound is

[0034] In some embodiments of this implementation, a co-solvent is also added. Preferably, the co-solvent is urea, sodium formate, isopropanol, or sodium hypophosphite, and the amount added is 0 to 5% of the total mass of acrylamide (AM) and 2-acrylamide-2-methylpropanesulfonic acid (AMPS) monomers, preferably 0.2 to 1%.

[0035] In some embodiments of this implementation, the amount of redox initiation system added is 0.001 to 0.05% of the total mass of acrylamide and 2-acrylamide-2-methylpropanesulfonic acid monomers.

[0036] In some embodiments of this implementation, the oxidant is a peroxide selected from hydrogen peroxide, sodium persulfate, potassium persulfate, or ammonium persulfate, and the proportion of the oxidant is 30-70% of the redox initiation system.

[0037] In some embodiments of this implementation, the mass ratio of monomer acrylamide to monomer 2-acrylamide-2-methylpropanesulfonic acid is (1-8):(1-8), preferably (2-6):(4-8), and more preferably (4-6):(4-6).

[0038] In some embodiments of this implementation, the preparation method specifically includes:

[0039] (1) Dissolve monomer acrylamide and monomer 2-acrylamide-2-methylpropanesulfonic acid in water to prepare an aqueous solution, and adjust the pH;

[0040] (2) Add a reducing agent to the aqueous solution of (1), then add a co-solvent and stir until homogeneous;

[0041] (3) Adjust the temperature of the aqueous solution to the reaction temperature, and evacuate to remove oxygen or use inert gas for protection;

[0042] (4) Add an oxidant to the aqueous solution of (2) and stir evenly. Remove oxygen by vacuum or protect with inert gas and react to obtain polymer blocks.

[0043] (5) After cutting, granulating, drying and crushing the rubber block, a granular polymer product P (AM / AMPS) is obtained, which is the high temperature and high salt resistant polymer.

[0044] In some embodiments of this implementation, steps (1) and (2) may also be:

[0045] (1) Dissolve the monomer acrylamide and the monomer 2-acrylamide-2-methylpropanesulfonic acid in water to prepare an aqueous solution, add a co-solvent, and adjust the pH;

[0046] (2) Add reducing agent to the aqueous solution of (1) and stir until homogeneous.

[0047] In some embodiments of this implementation, in step (1), the pH is adjusted using an alkaline solution to a pH of 6-10, preferably 6-7.

[0048] The concentration of the aqueous solution is 10-40%, expressed as the total mass percentage of the monomers acrylamide and 2-acrylamide-2-methylpropanesulfonic acid.

[0049] In some embodiments of this implementation, the reaction temperature in step (3) is controlled between 10 and 60°C.

[0050] In some embodiments of this implementation, in steps (3) and (4), the vacuum deoxygenation is carried out at 25-45°C for 6-10 hours.

[0051] In some embodiments of this implementation, in steps (3) and (4), the inert gas is one or more of argon, nitrogen, and carbon dioxide.

[0052] In step (3), the inert gas protection is to move the device into the heat insulation unit after the temperature drops to 10-15℃ and purge it with inert gas for 15-60 minutes.

[0053] In step (4), the inert gas protection is to continuously ventilate for 5-60 minutes and gradually cool down for 0.5-3 hours to obtain polymer blocks.

[0054] In a preferred embodiment, steps (3) and (4) are performed under inert gas protection, which has a better apparent viscosity than copolymers prepared under vacuum deoxygenation conditions.

[0055] Another typical embodiment of the present invention provides a high-temperature and high-salt resistant polymer obtained by the above preparation method.

[0056] The structural formula of the high-temperature and high-salt resistant polymer is as follows:

[0057]

[0058] In the formula, x and y represent the degree of aggregation, and x and y are greater than 0.

[0059] The high-temperature and high-salt resistant polymer was tested at a rotor shear rate of 7.34 s. -1 When the sample concentration is 2000 mg / L, the mineralization is 58002 mg / L, and the temperature is 25℃, the apparent viscosity is 19-50 mPa·s, preferably 30-50 mPa·s; when the temperature is 95℃, the apparent viscosity is 9-25 mPa·s, preferably 15-25 mPa·s.

[0060] The third typical embodiment of the present invention provides the application of the above-mentioned high-temperature and high-salt resistant polymer in oil fields.

[0061] A fourth typical embodiment of the present invention provides an oil displacement agent for crude oil reservoirs, comprising the above-mentioned high-temperature and high-salt resistant polymer.

[0062] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0063] Example 1

[0064] Add 20g of acrylamide and 20g of 2-acrylamide-2-methylpropanesulfonic acid to a reaction flask, add 160mL of deionized water to prepare an aqueous solution, then add sodium hydroxide to adjust the pH to 7. During stirring, add 0.1% by weight of [a specific ingredient / component]. 5.86 mL of hexa(tetramethylguanidine)cyclotriphosphazene (HTGCP) aqueous solution and 0.2 g of urea were stirred evenly, and then 1.73 mL of 0.1% by weight ammonium persulfate aqueous solution was added. The mixture was then placed in a vacuum drying oven and reacted under vacuum at 40°C for 8 hours to obtain polymer blocks. The blocks were cut, granulated, dried, and pulverized to obtain granular product - copolymer 1#.

[0065] Example 2

[0066] Add 20g of acrylamide and 20g of 2-acrylamide-2-methylpropanesulfonic acid to a reaction flask, add 160mL of deionized water to prepare an aqueous solution, then add sodium hydroxide to adjust the pH to 7. During stirring, add 0.1% by weight of [a specific ingredient / component]. 5.03 mL of PNX aqueous solution and 0.2 g of urea were mixed thoroughly, and then 2.96 mL of 0.1% by weight ammonium persulfate aqueous solution was added. The mixture was then placed in a vacuum drying oven and reacted under vacuum at 40°C for 8 hours to obtain polymer blocks. The blocks were then cut, granulated, dried, and crushed to obtain granular product - copolymer 2#.

[0067] Example 3

[0068] 20g of acrylamide and 20g of 2-acrylamide-2-methylpropanesulfonic acid were added to a reaction flask, and 160mL of deionized water was added to prepare an aqueous solution. Sodium hydroxide was added to adjust the pH to 7. During stirring, 6.01mL of 0.1% HTGCP aqueous solution and 0.2g of urea were added. After stirring evenly, 1.98mL of 0.1% potassium persulfate aqueous solution was added. The mixture was then placed in a vacuum drying oven and reacted under vacuum at 25°C for 8 hours to obtain polymer blocks. The blocks were cut, granulated, dried, and pulverized to obtain the granular product – copolymer 3#.

[0069] Example 4

[0070] 20g of acrylamide and 20g of 2-acrylamide-2-methylpropanesulfonic acid were added to a reaction flask, and 160mL of deionized water was added to prepare an aqueous solution. Sodium hydroxide was then added to adjust the pH to 7. During stirring, 5.06mL of 0.1% PNX aqueous solution and 0.2g of urea were added. After stirring until homogeneous, 2.93mL of 0.1% potassium persulfate aqueous solution was added. The mixture was then placed in a vacuum drying oven and reacted under vacuum at 40℃ for 8 hours to obtain polymer blocks. The blocks were cut, granulated, dried, and pulverized to obtain the granular product – copolymer 4#.

[0071] Example 5

[0072] Add 20g of acrylamide and 20g of 2-acrylamide-2-methylpropanesulfonic acid to a reaction flask, add 160mL of deionized water to prepare an aqueous solution, then add sodium hydroxide to adjust the pH to 7. During stirring, add 0.1% by weight of [a specific ingredient / component]. 4.71 mL of (NMe2)3P=NH aqueous solution and 0.2 g of urea were stirred evenly, and then 3.28 mL of 0.1% by weight potassium persulfate aqueous solution was added. The mixture was then placed in a vacuum drying oven and reacted under vacuum at 40°C for 8 hours to obtain polymer blocks. The blocks were cut, granulated, dried, and pulverized to obtain granular product - copolymer 5#.

[0073] Example 6

[0074] Add 20g of acrylamide and 20g of 2-acrylamide-2-methylpropanesulfonic acid to a reaction flask, add 160mL of deionized water to prepare an aqueous solution, then add sodium hydroxide to adjust the pH to 7. During stirring, add 0.1% by weight of [a specific ingredient / component]. 3.16 mL of [(NMe2)3P=N)]3P=NH aqueous solution and 0.2 g of urea were stirred evenly, and then 1.84 mL of 0.1% by weight potassium persulfate aqueous solution was added. The mixture was then placed in a vacuum drying oven and reacted under vacuum at 40°C for 8 hours to obtain polymer blocks. The blocks were cut, granulated, dried, and pulverized to obtain granular product - copolymer 6#.

[0075] Example 7

[0076] 20g of acrylamide and 20g of 2-acrylamide-2-methylpropanesulfonic acid were added to a reaction flask, and 160mL of deionized water was added to prepare an aqueous solution. Sodium hydroxide was then added to adjust the pH to 7. During stirring, 3.80mL of 0.1% PNX aqueous solution and 0.2g of urea were added. After stirring until homogeneous, 2.20mL of 0.1% potassium persulfate aqueous solution was added. The mixture was then placed in a vacuum drying oven and reacted under vacuum at 40℃ for 8 hours to obtain polymer blocks. The blocks were cut, granulated, dried, and pulverized to obtain the granular product – copolymer 7#.

[0077] Example 8

[0078] 20g of acrylamide and 20g of 2-acrylamide-2-methylpropanesulfonic acid were added to a reaction flask, and 160mL of deionized water was added to prepare an aqueous solution. Sodium hydroxide was added to adjust the pH to 7. While stirring, 5.70mL of 0.1% PNX aqueous solution and 0.2g of urea were added. After stirring evenly, 3.30mL of 0.1% potassium persulfate aqueous solution was added. The mixture was then placed in a vacuum drying oven and reacted under vacuum at 40℃ for 8 hours to obtain polymer blocks. The blocks were cut, granulated, dried, and pulverized to obtain the granular product – copolymer 8#.

[0079] Example 9

[0080] 24g of acrylamide and 16g of 2-acrylamide-2-methylpropanesulfonic acid were added to a reaction flask, and 160mL of deionized water was added to prepare an aqueous solution. Sodium hydroxide was then added to adjust the pH to 7. While stirring, 2.53mL of 0.1% PNX aqueous solution and 0.2g of urea were added. After stirring evenly, 1.47mL of 0.1% potassium persulfate aqueous solution was added. The mixture was then placed in a vacuum drying oven and reacted under vacuum at 40℃ for 8 hours to obtain polymer blocks. The blocks were cut, granulated, dried, and pulverized to obtain the granular product – copolymer 9#.

[0081] Example 10

[0082] 20g of acrylamide and 20g of 2-acrylamide-2-methylpropanesulfonic acid were added to a reaction flask, and 160mL of deionized water was added to prepare an aqueous solution. Sodium hydroxide was added to adjust the pH to 7. During stirring, 2.53mL of 0.1% PNX aqueous solution and 0.2g of urea were added. After stirring evenly, 1.46mL of 0.1% potassium persulfate aqueous solution was added. The mixture was then placed in a vacuum drying oven and reacted under vacuum at 40℃ for 8 hours to obtain polymer blocks. The blocks were cut, granulated, dried, and pulverized to obtain the granular product – copolymer 10#.

[0083] Example 11

[0084] 90g of acrylamide and 90g of 2-acrylamide-2-methylpropanesulfonic acid were added to a beaker, and 478mL of deionized water was added to prepare an aqueous solution. Potassium hydroxide was then added to adjust the pH to 7. While stirring, 24.05mL of 0.1% PNX aqueous solution and 0.9g of urea were added. After the temperature dropped to 10℃, the mixture was transferred to an insulated cup. Argon gas was passed through for 20 minutes, and then 11.95mL of 0.1% potassium persulfate aqueous solution was added. Argon gas was continued for 10 minutes. After decreasing the temperature from the highest point for 1 hour, a polymer block was obtained. The block was cut, granulated, dried, and pulverized to obtain the granular product – copolymer 11#.

[0085] Example 12

[0086] 72g of acrylamide and 108g of 2-acrylamide-2-methylpropanesulfonic acid were added to a beaker, and 464mL of deionized water was added to prepare an aqueous solution. 0.9g of urea was added, and potassium hydroxide was added to adjust the pH to 7. During stirring, 29.31mL of 0.1% PNX aqueous solution was added. After the temperature dropped to 10℃, the mixture was transferred to an insulated cup and purged with argon gas for 20 minutes. Then, 15.69mL of 0.1% potassium persulfate aqueous solution (oxidant) was added, and argon gas was continuously purged for 10 minutes. After decreasing the temperature from the highest point for 1 hour, a polymer block was obtained. The block was cut, granulated, dried, and crushed to obtain the granular product - copolymer 12#.

[0087] Example 13

[0088] 90g of acrylamide and 90g of 2-acrylamide-2-methylpropanesulfonic acid were added to a beaker, and 487mL of deionized water was added to prepare an aqueous solution. 0.9g of urea was added, and potassium hydroxide was added to adjust the pH to 7. During stirring, 17.59mL of 0.1% PNX aqueous solution was added. After the temperature dropped to 14℃, the mixture was transferred to an insulated cup and purged with argon gas for 20 minutes. Then, 9.41mL of 0.1% potassium persulfate aqueous solution (an oxidant) was added, and argon gas was continuously purged for 10 minutes. After decreasing the temperature from the highest point for 1 hour, a polymer block was obtained. The block was cut, granulated, dried, and crushed to obtain the granular product - copolymer 13#.

[0089] Example 14

[0090] Unlike Example 10, copolymer 14# was prepared by using a monomer with a high content of 80% 2-acrylamide-2-methylpropanesulfonic acid (AMPS) under vacuum deoxygenation conditions.

[0091] Example 15

[0092] Unlike Example 11, copolymer 15# was prepared under inert gas protection conditions, with the monomer containing up to 80% 2-acrylamide-2-methylpropanesulfonic acid (AMPS).

[0093] Comparative Example 1

[0094] Existing literature (Jin Zhiyuan, Shan Guorong, Pan Pengju. Preparation and temperature and salt resistance properties of AM / AMPS / SSS terpolymers [J]. Journal of Chemical Industry and Engineering, 2023, 74(02): 916-923) discloses that the redox system used is the traditional potassium persulfate and sodium bisulfite. A series of samples with different AMPS contents (AM to AMPS mass ratio of 5:5, 6:4, 7:3, 8:2, 9:1) were obtained at a polymerization temperature of 40℃ and an initiator mass ratio of KPS:NaHSO3 = 4:1, an initiator concentration of 0.15 wt% of monomer, a monomer concentration of 20 wt%, a solution pH of 7, and a polymerization temperature of 40℃. The shear rate at 40℃ was 6 s⁻¹. -1 Viscosity under the conditions such as Figure 6 As shown.

[0095] Obviously, under the same temperature and shear rate conditions, the viscosity of copolymer 11# prepared in Example 11 at different concentrations of pure aqueous solution is as follows: Figure 5 As shown, copolymer 11# achieved a viscosity of 206 mPa·s at a concentration of 800 mg / L, exceeding the viscosity of less than 150 mPa·s at 2000 mg / L in Comparative Example 1. At 2000 mg / L, it reached 477 mPa·s, demonstrating the significant advantages of the novel initiator. Furthermore, the AMPS content in this example was 50%, while the traditional redox system in Comparative Example 1 could not produce a sample with high viscosity at a high AMPS content.

[0096] Comparative Example 2

[0097] Existing literature (Yang H, Zhang J, Jiang H, et al. Study on the rheologicalproperties and salt resistance mechanism of an amphiphilic polymer with twin-tailed group[J]. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2024,700:134748. Page 4 of the text, Figure 5The paper discloses that a P(AM-AMPS) copolymer obtained by copolymerizing AM with AM at a mass content of 24.5% AM using azobisisobutylamidine hydrochloride (AIBA, V-50 initiator) has a viscosity of approximately 20 mPa·s in a solution with a concentration of 2200 mg / L and a mineralization of 98558 mg / L at 25°C.

[0098] The copolymer 11# prepared in Example 11 of this invention has a viscosity of 33.3 mPa·s in a solution with a concentration of 2000 mg / L and a mineralization of 1160048 mg / L at 25°C. Obviously, Example 11 exhibits a higher viscosity than Comparative Example 2 under low concentration and high mineralization conditions.

[0099] Test Example 1

[0100] The high-temperature and high-salt resistant polymers obtained in the examples were prepared into aqueous solutions of 2000 mg / L, and the apparent viscosity of each aqueous solution was measured. The test results are shown in Table 1.

[0101] The testing instrument was a Hacker rheometer, with temperatures of 25℃ and 95℃, and a rotor shear rate of 7.34 s⁻¹. -1 The sample concentration was 2000 mg / L, the mineralization was 58002 mg / L, the NaCl concentration was 53360 mg / L, the CaCl2 concentration was 1213 mg / L, the MgCl2 concentration was 3429 mg / L, and the calcium and magnesium ion concentration was 1542 mg / L.

[0102] Table 1

[0103]

[0104]

[0105] As can be seen from the results in Table 1, the high-temperature and high-salt resistant polymer provided by this invention exhibits very high apparent viscosity at temperatures of 25℃ and 95℃ and a mineralization of 58002 mg / L. Figure 4 It can be seen that this product exhibits excellent high-temperature and high-salt resistance. Among them, under vacuum deoxygenation conditions, copolymer 10# prepared in Example 10 has better apparent viscosity at 25°C and 95°C. Under inert gas protection conditions, Examples 11-13 have better apparent viscosity than under vacuum deoxygenation conditions, with copolymer 11# prepared in Example 11 being the best.

[0106] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a high-temperature, high-salt resistant polymer, characterized in that, Includes the following steps: A high-temperature and high-salt resistant polymer was prepared by copolymerizing acrylamide and 2-acrylamide-2-methylpropanesulfonic acid using a redox initiation system; wherein the redox initiation system comprises a phosphazene compound as a reducing agent and a peroxide as an oxidizing agent. The phosphazene compound is selected from and One or more of the following; The phosphazene compound is When R1 is , , or R2 and R3 are independently -NH2, , , , , or R4 is -NH2, , , , , , , hydrogen, benzene ring, methyl, ethyl or -C6H4-4-OCH3; The phosphazene compound is When R is , , or ; The amount of redox initiation system added is 0.001~0.05 wt% of the total mass of acrylamide and 2-acrylamido-2-methylpropanesulfonic acid monomers; The proportion of oxidant in the redox initiation system is 30-70%; The mass ratio of monomer acrylamide to monomer 2-acrylamide-2-methylpropanesulfonic acid is (1-8):(1-8).

2. The preparation method according to claim 1, characterized in that, The phosphazene compound is , , or .

3. The preparation method according to claim 1, characterized in that, A cosolvent was also added.

4. The preparation method according to claim 3, characterized in that, The co-solvent is urea, sodium formate, isopropanol, or sodium hypophosphite, and the amount added is 0-5% of the total mass of acrylamide and 2-acrylamide-2-methylpropanesulfonic acid monomers.

5. The preparation method according to claim 1, characterized in that, The oxidant is a peroxide, selected from hydrogen peroxide, sodium persulfate, potassium persulfate, or ammonium persulfate.

6. The preparation method according to claim 1, characterized in that, The mass ratio of monomer acrylamide to monomer 2-acrylamide-2-methylpropanesulfonic acid is (2-6):(4-8).

7. The preparation method according to claim 1, characterized in that, The preparation method specifically includes: (1) Dissolve the monomers acrylamide and 2-acrylamide-2-methylpropanesulfonic acid in water to prepare an aqueous solution, and adjust the pH; (2) Add a reducing agent to the aqueous solution of (1), then add a co-solvent and stir until homogeneous; (3) Adjust the temperature of the aqueous solution to the reaction temperature, and apply a vacuum to remove oxygen or use an inert gas for protection; (4) Add an oxidant to the aqueous solution of (2) and stir until homogeneous. Remove oxygen by vacuum or protect with an inert gas and react to obtain polymer blocks. (5) After cutting, granulating, drying and crushing the rubber block, granular polymer is obtained, which is the high temperature and high salt resistant polymer.

8. The preparation method according to claim 1, characterized in that, The specific preparation method includes: (1) Dissolve the monomer acrylamide and the monomer 2-acrylamide-2-methylpropanesulfonic acid in water to prepare an aqueous solution, add a co-solvent, and adjust the pH; (2) Add a reducing agent to the aqueous solution of (1) and stir until homogeneous; (3) Adjust the temperature of the aqueous solution to the reaction temperature, and apply a vacuum to remove oxygen or use an inert gas for protection; (4) Add an oxidant to the aqueous solution of (2) and stir until homogeneous. Remove oxygen by vacuum or protect with an inert gas and react to obtain polymer blocks. (5) After cutting, granulating, drying and crushing the rubber block, granular polymer is obtained, which is the high temperature and high salt resistant polymer.

9. The preparation method according to claim 7 or 8, characterized in that, In step (1), the pH is adjusted using an alkaline solution to a pH of 6-10.

10. The preparation method according to claim 7 or 8, characterized in that, The concentration of the aqueous solution is 10-40%, expressed as the total mass percentage of the monomers acrylamide and 2-acrylamide-2-methylpropanesulfonic acid.

11. The preparation method according to claim 7 or 8, characterized in that, In step (3), the reaction temperature is controlled at 10~60℃.

12. The preparation method according to claim 7 or 8, characterized in that, In steps (3) and (4), the vacuum deoxygenation is carried out at 25-45℃ for 6-10 hours.

13. The preparation method according to claim 7 or 8, characterized in that, In steps (3) and (4), the inert gas is one or more of argon, nitrogen, and carbon dioxide.

14. The preparation method according to claim 7 or 8, characterized in that, In step (3), the inert gas protection is to move the device into the heat insulation device after the temperature drops to 10-15℃ and pass inert gas for 15-60 minutes.

15. The preparation method according to claim 7 or 8, characterized in that, In step (4), the inert gas protection is to continuously ventilate for 5-60 minutes and gradually cool down for 0.5-3 hours to obtain polymer blocks.

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