A temperature-resistant and salt-resistant cationic hydrophobic association polymer, a preparation method and application thereof

Abstract

The application relates to the technical field of oilfield chemicals, and discloses a temperature-resistant and salt-resistant cationic hydrophobic association polymer as well as a preparation method and application thereof. Components of the polymer are acrylamide, N,N-dimethyl-N-methyl acryloyloxyethyl-N-2-hydroxy-1-octadecylamino propyl ammonium chloride, ammonium persulfate, sodium bisulfite, a fatty alcohol polyoxyethylene ether and a solvent. The application chemically synthesizes specific amounts of acrylamide, N,N-dimethyl-N-methyl acryloyloxyethyl-N-2-hydroxy-1-octadecylamino propyl ammonium chloride, ammonium persulfate, sodium bisulfite and the fatty alcohol polyoxyethylene ether, and can prepare the polymer with high thickening efficiency. The polymer has good thickening performance, a small critical association concentration, excellent temperature resistance and salt resistance, and can be applied to unconventional oilfields. The product produced by the preparation method has low residual monomer content, the preparation process is simple, the cost is low, the operation is easy, the pollution is small, and the product is easy to be industrially produced.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of oil field chemicals, in particular to a temperature-resistant and salt-resistant cationic polymer and a preparation method and application thereof. BACKGROUND

[0002] In recent years, with the development of the oil and gas field exploitation industry, more and more hydrophobic associated polymers are applied to hydraulic fracturing and tertiary oil recovery. Among them, high molecular weight partially hydrolyzed polyacrylamide is mainly used, but the hydrolyzed polyacrylamide product has a single structure, poor hydrolysis, and high sensitivity to the environment. In a high-temperature and strong-alkali environment, the hydrolysis of the product is accelerated. It is found by researchers that adding an ionic group to the polyacrylamide can well solve the problem of poor temperature resistance and salt resistance.

[0003] For example, the published patent CN101492515A provides an acrylamide modified graft copolymer, the macromonomer of which is randomly distributed in the molecular chain, which not only enhances the rigidity of the entire macromolecular chain, promotes the conformational stretching, is beneficial to viscosity increase and salt resistance, but also effectively separates the hydrophobic functional groups through the macromolecular branches, significantly enhances the intermolecular association. In addition, the large steric hindrance of the molecular branch and the hydrophobic functional group can inhibit the oxidative degradation of the main chain and the hydrolysis of the amide group, thereby improving the temperature resistance and anti-aging performance.

[0004] The application provides a cationic acrylamide modified graft copolymer, which synthesizes a cationic macromonomer and copolymerizes by micellar polymerization, the macromonomer of which is orderly embedded in the polyacrylamide main chain, thereby enhancing the intermolecular association. Not only the temperature resistance and salt resistance of the macromolecular chain are enhanced, but also the process is simple and the cost is low. The application has the same application field as the published patent CN101492515A, but the published patent CN101492515A has problems such as poor temperature resistance and salt resistance when facing high-temperature and high-salinity reservoirs, and the viscosity is greatly reduced. The thickening performance is poor.

[0005] Therefore, the monomer and the acrylamide are synthesized into a temperature-resistant and salt-resistant hydrophobic associated polymer HACM by micellar polymerization, so as to solve the problem of poor temperature resistance and salt resistance of the polymer in the oil field. SUMMARY

[0006] The purpose of the application is to overcome the problem of poor temperature resistance and salt resistance of the polymer in the prior art.

[0007] In order to achieve the above-mentioned purpose, the specific technical scheme of the application is as follows:

[0008] A temperature-resistant and salt-resistant cationic hydrophobic associated polymer, which is formed by polymerization of the following raw materials:

[0009] acrylamide, N,N-dimethyl-N-methyl acryloyloxyethyl-N-2-hydroxy-1-octadecylamino propyl ammonium chloride, ammonium persulfate, sodium bisulfite, fatty alcohol polyoxyethylene ether, solvent;

[0010] , formula (1); , formula (2);

[0011] The N,N-dimethyl-N-methyl acryloyloxyethyl-N-2-hydroxy-1-octadecylamino propyl ammonium chloride has a structure shown in formula (1), and the acrylamide has a structure shown in formula (2).

[0012] In the cationic polymer, the content of the N,N-dimethyl-N-methyl acryloyloxyethyl-N-2-hydroxy-1-octadecylamino propyl ammonium chloride is 0.8 parts by weight, the content of the acrylamide is 6-12 parts by weight, and the content of the fatty alcohol polyoxyethylene ether is 0.3-0.35 parts by weight, relative to 100 parts by weight of the solvent.

[0013] The acrylamide needs to be configured as an aqueous solution with a concentration of 20-25 wt% when mixed.

[0014] The solvent is deionized water.

[0015] The method comprises mixing and reacting the components in the composition.

[0016] The operation of mixing the components in the temperature-resistant and salt-resistant cationic polymer specifically comprises the following steps:

[0017] (1) first mixing the fatty alcohol polyoxyethylene ether and the N,N-dimethyl-N-methyl acryloyloxyethyl-N-2-hydroxy-1-octadecylamino propyl ammonium chloride in the presence of a first portion of the solvent to obtain a first mixed solution, and first contacting the acrylamide solution with a second portion of the solvent to dissolve to obtain solution I;

[0018] (2) second mixing the first mixed solution with the solution I to obtain a second mixed solution, and second contacting ammonium persulfate and sodium bisulfite with a third portion of the solvent to dissolve to obtain solution II;

[0019] (3) contacting and reacting the second mixed solution with the solution II;

[0020] The amount of the first portion of the solvent, the second portion of the solvent, and the third portion of the solvent is in a weight ratio of 4-5:4-5:1.

[0021] The conditions of the first mixing of acrylamide and N,N-dimethyl-N-methyl acryloyloxyethyl-N-2-hydroxy-1-octadecylamino propyl ammonium chloride, and the second mixing of the first mixed solution and the solution I include: the stirring speed is 50-60 rpm, the temperature is 20-30 DEG C, and the time is 5-10 min.

[0022] In step (3), the conditions of the contact reaction include: the temperature is 50-55 DEG C, and the time is 6-7 h.

[0023] The application of the temperature-resistant and salt-resistant cationic polymer in oil and gas development.

[0024] Compared with the prior art, the application has the beneficial effects that:

[0025] A novel temperature-resistant and salt-resistant long carbon chain hydrophobic cationic monomer DMHOAC is designed. The monomer contains long carbon chain, ester group and amide group. The monomer has good salt resistance and temperature resistance.

[0026] The application discloses a high-performance polymer prepared by accurately polymerizing specific amounts of N,N-dimethyl-N-methyl acryloyloxyethyl-N-2-hydroxy-1-octadecylamino propyl ammonium chloride, acrylamide, fatty alcohol polyoxyethylene ether, ammonium persulfate and a solvent. The polymer has high thickening efficiency and excellent thickening performance, and has a small critical association concentration, which means that the polymer can achieve significant thickening effect at a low concentration. In addition, the polymer has excellent temperature resistance and salt resistance, and can meet the application requirements of complex environments such as unconventional oil fields.

[0027] Notably, the preparation method provided by the application has the advantages of simple process, low cost, easy operation and less pollution in the production process. The method ensures that the product has low residual monomer content, thereby improving the purity and performance of the product. These advantages make the polymer more suitable for industrial production, and provide an efficient and environmentally friendly solution for the related industry.

[0028] In conclusion, the application successfully prepares a polymer with high thickening efficiency, excellent thickening performance and excellent temperature resistance and salt resistance by accurate polymerization and optimized preparation process. The polymer has the advantages of simple preparation process, low cost, less pollution and easy industrial production, and has a wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The apparent viscosity results of the salt-resistant test of the embodiment of the application.

[0030] Figure 2 The apparent viscosity results of the embodiment of the application at different temperatures.

[0031] Figure 3 FTIR characterization spectrum of the embodiment of the present application. DETAILED DESCRIPTION

[0032] The endpoints of the ranges of values of the ranges and any values not specifically recited are not limited to the precise values recited. The ranges of values are intended to cover all ranges encompassed by the endpoints, the endpoints of the ranges, and the individual points within the ranges. The endpoints of the ranges of values recited are not to be construed as limiting the ranges of values.

[0033] It should be noted that in the aspects of the present application, the present application is described only once in one aspect for the same component in the aspects and not repeatedly described, and the person skilled in the art should not understand it as a limitation of the present application.

[0034] It should be noted that in the present application, the raw materials not mentioned can be purchased by the general route by the person skilled in the art as needed, and will not be described one by one in the present application.

[0035] In the present application, unless otherwise specified, the room temperature or normal temperature means 25±2℃.

[0036] As described before, the first aspect of the present application provides a temperature and salt resistant cationic polymer, which contains the following components mixedly or independently stored in the polymer:

[0037] N,N-dimethyl-N-methacryloyloxyethyl-N-2-hydroxy-1-octadecylaminopropyl ammonium chloride, acrylamide, fatty alcohol polyoxyethylene ether, ammonium persulfate, solvent;

[0038] , formula (1); , formula (2);

[0039] The N,N-dimethyl-N-methacryloyloxyethyl-N-2-hydroxy-1-octadecylaminopropyl ammonium chloride has the structure shown in formula (1), and the acrylamide has the structure shown in formula (2).

[0040] Preferably, in the temperature and salt resistant cationic polymer, the content of the N,N-dimethyl-N-methacryloyloxyethyl-N-2-hydroxy-1-octadecylaminopropyl ammonium chloride is 1-2 parts by weight, the content of the acrylamide is 19-20 parts by weight, the content of the fatty alcohol polyoxyethylene ether is 0.3-0.35 parts by weight, and the content of the ammonium persulfate and sodium bisulfite is 0.08-0.09 parts by weight, relative to 100 parts by weight of the solvent.

[0041] The inventors have found that, by using the specific implementation method in the preferred case, a polymer with higher thickening performance can be obtained.

[0042] According to a particularly preferred specific implementation, the acrylamide is an acrylamide aqueous solution with a concentration of 20-25wt%.

[0043] According to a particularly preferred specific implementation, the fatty alcohol polyoxyethylene ether has a concentration of 80-90%.

[0044] As described above, the second aspect of the present application provides a method for preparing a temperature-resistant and salt-resistant cationic polymer, which comprises mixing the components in the composition of the first aspect.

[0045] Preferably, the operation of mixing the components in the cationic polymer composition comprises the following steps:

[0046] (1) mixing acrylamide and N,N-dimethyl-N-methyl acryloyloxyethyl-N-2-hydroxy-1-octadecylamino propyl ammonium chloride in the presence of a first portion of solvent to obtain a first mixed solution; and

[0047] contacting fatty alcohol polyoxyethylene ether with a second portion of solvent to dissolve and obtain solution I;

[0048] (2) mixing the first mixed solution with solution I to obtain a second mixed solution; and contacting ammonium persulfate with a third portion of solvent to dissolve and obtain solution II;

[0049] (3) contacting the second mixed solution with solution II for reaction;

[0050] The amount of the first portion of solvent, the second portion of solvent and the third portion of solvent is in a weight ratio of 4-5:4-5:1.

[0051] The present application does not have special requirements for the operation of the first contacting and the second contacting, and only needs to be able to dissolve fatty alcohol polyoxyethylene ether and ammonium persulfate respectively. Exemplarily, the conditions of the first contacting and the second contacting each independently comprise a stirring speed of 50-60 rpm and a temperature of 20-30℃.

[0052] Preferably, the conditions of the first mixing and the second mixing each independently comprise a stirring speed of 50-60 rpm, a temperature of 20-30℃ and a time of 5-10 min.

[0053] Preferably, in step (3), the conditions of the contacting reaction at least comprise a temperature of 50-55℃ and a time of 6-7h.

[0054] As described above, the fourth aspect of the present application provides an application of the cationic polymer of the third aspect in oil and gas development.

[0055] The present application will be described in detail below by way of examples. In the following examples, the various raw materials used are commercially available unless otherwise specified.

[0056] N,N-dimethyl-N-methacryloyloxyethyl-N-2-hydroxy-1-octadecylaminopropyl ammonium chloride: self-made;

[0057] Acrylamide: purchased from BASF;

[0058] Sodium bisulfite: purchased from BASF;

[0059] Fatty alcohol polyoxyethylene ether: purchased from BASF;

[0060] Ammonium persulfate: purchased from BASF;

[0061] In the following examples, the solvent is deionized water.

[0062] Example 1

[0063] The present example provides a preparation method of a cationic polymer, which comprises:

[0064] (1) 20 g of an acrylamide aqueous solution (concentration of 40 wt%) and 20 g of deionized water are added to a reaction kettle at 30°C, followed by the addition of 1 g of N,N-dimethyl-N-methacryloyloxyethyl-N-2-hydroxy-1-octadecylaminopropyl ammonium chloride (concentration of 80 wt%), which is stirred at 50 rpm for 10 min to obtain a first mixed solution; and 0.35 g of fatty alcohol polyoxyethylene ether is dissolved in 20 g of deionized water to obtain solution I;

[0065] (2) The entire first mixed solution and solution I obtained above are stirred at 60 rpm for 5 min at 30°C to obtain a second mixed solution; and 0.012 g of ammonium persulfate and sodium bisulfite with a mass ratio of 1:1 is dissolved in 10 g of deionized water to obtain solution II;

[0066] (3) The entire second mixed solution and solution II obtained above are reacted in a reaction kettle at 55°C for 6 h to obtain a temperature-resistant and salt-resistant cationic polymer H1.

[0067] Example 2

[0068] The present example provides a preparation method of a cationic polymer, which comprises:

[0069] (1) Add 25g of acrylamide aqueous solution (concentration of 40wt%) and 25g of deionized water to a reaction vessel at 30℃, then add 1g of N,N-dimethyl-N-methacryloyloxyethyl-N-2-hydroxy-1-octadecylaminopropylammonium chloride (concentration of 80wt%), stir at 50rpm for 10min to obtain the first mixed solution; and weigh 0.35g of fatty alcohol polyoxyethylene ether and dissolve it in 1g of deionized water to obtain solution I;

[0070] (2) At 30°C, all the first mixed solution and solution I obtained above were stirred at 60 rpm for 8 min to obtain the second mixed solution; and 0.012 g of ammonium persulfate and sodium bisulfite in a mass ratio of 1:1 were dissolved in 10 g of deionized water to obtain solution II;

[0071] (3) React all the second mixed solution and solution II obtained above in a reactor at 55°C for 6 hours to obtain cationic polymer H2.

[0072] Example 3

[0073] This embodiment provides a method for preparing a temperature- and salt-resistant cationic polymer, the method comprising:

[0074] (1) Add 30g of acrylamide aqueous solution (concentration of 40wt%) and 20g of deionized water to a reaction vessel at 30℃, then add 1g of N,N-dimethyl-N-methacryloyloxyethyl-N-2-hydroxy-1-octadecylaminopropylammonium chloride (concentration of 80wt%), stir at 55rpm for 8min to obtain the first mixed solution; and weigh 0.35g of fatty alcohol polyoxyethylene ether and dissolve it in 10g of deionized water to obtain solution I;

[0075] (2) At 30°C, all the first mixed solution and solution I obtained above were stirred at 60 rpm for 5 min to obtain the second mixed solution; and 0.012 g of ammonium persulfate was weighed and dissolved in 10 g of deionized water to obtain solution II;

[0076] (3) React all the second mixed solution and solution II obtained above in a reactor at 55°C for 6 hours to obtain cationic polymer H3.

[0077] Example 4

[0078] In this embodiment, a temperature- and salt-resistant cationic polymer was prepared using a method similar to that in Example 3, except that 0.3 g of fatty alcohol polyoxyethylene ether was used.

[0079] The remaining steps are the same as in Example 3.

[0080] The cationic polymer H4 was obtained.

[0081] Example 5

[0082] This example was prepared in a similar manner to Example 3, except that 0.01 g of ammonium persulfate and sodium bisulfite were used.

[0083] The remaining steps were the same as Example 3.

[0084] Cationic polymer H5 was obtained.

[0085] Comparative Example 1

[0086] This comparative example was prepared in a similar manner to Example 3, except that an equal mass of trimethylbenzene was used in place of acrylamide.

[0087] The remaining steps were the same as Example 3.

[0088] Cationic polymer HA1 was obtained.

[0089] Comparative Example 2

[0090] This comparative example was prepared in a similar manner to Example 3, except that an equal mass of sodium dodecyl sulfate was used in place of fatty alcohol polyoxyethylene ether.

[0091] The remaining steps were the same as Example 3.

[0092] Cationic polymer HA2 was obtained.

[0093] Comparative Example 3

[0094] This comparative example was prepared in a similar manner to Example 3, except that 0.4 g of fatty alcohol polyoxyethylene ether was used.

[0095] The remaining steps were the same as Example 3.

[0096] Cationic polymer HA3 was obtained.

[0097] Comparative Example 4

[0098] This comparative example was prepared in a similar manner to Example 3, except that 35 g of acrylamide was used.

[0099] The remaining steps were the same as Example 3.

[0100] Cationic polymer HA4 was obtained.

[0101] Test Results

[0102] The thickening rate and temperature and salt resistance of the temperature- and salt-resistant cationic polymers prepared in the examples and comparative examples were tested, and the specific results are shown in Table 1.

[0103] Among them, the thickening rate and temperature and salt resistance were tested by the apparent viscosity method in accordance with the standard Q / SY 1750-2014;

[0104] The specific testing method is as follows:

[0105] (1) At room temperature, measure 300 mL of distilled water and pour it into the Wu Yin mixer. Turn on the mixer, adjust the voltage, keep the liquid in a vortex state and see the bottom of the mixer. Then weigh 1.500 g of polymer (the polymerizing agent needs to be dried in an oven at 105℃ for 4 hours or the net mass after deducting water). Slowly and evenly add the polymer (the addition time is less than 30 s). Start timing after the polymer is added. Measure the viscosity of the liquid every 5 minutes using a six-speed rotational viscometer. After the viscosity tends to stabilize, measure its apparent viscosity; obtain its thickening properties.

[0106] Table 1

[0107] Apparent viscosity / mPa s Example 1 67.32 Example 2 69.86 Example 3 70.36 Example 4 68.32 Example 5 26.44 Comparative Example 1 43.25 Comparative Example 2 44.28 Comparative Example 3 42.19 Comparative Example 4 44.32

[0108] As can be seen from Table 1, the temperature- and salt-resistant cationic polymer provided by the present invention can be used to prepare polymers with good thickening properties.

[0109] (2) Prepare a polymer solution with a mass concentration of 0.5% by using 10,000~80,000 mg / L NaCl aqueous solution and 500~5,000 mg / L CaCl2 aqueous solution as solvents. Measure its apparent viscosity at room temperature using a rotational viscometer.

[0110] from Figure 1 As can be seen from the above, the temperature- and salt-resistant cationic polymer provided by the present invention can be used to prepare polymers with good salt resistance.

[0111] (2) Prepare a polymer solution with a mass concentration of 0.5% and measure its apparent viscosity at different temperatures.

[0112] from Figure 2 As can be seen from the above, the heat-resistant and salt-resistant cationic polymer provided by the present invention can be used to prepare polymers with good temperature resistance.

[0113] (3) The polymer was characterized by FTIR, and the product was purified by soaking in anhydrous ethanol. After drying, the product was mixed with potassium bromide at a mass ratio of 1:100, ground, and pressed into tablets for sample preparation.

[0114] from Figure 3wherein the stretching vibration absorption peak of -NH- bond is at 3434 cm -1 wherein the asymmetric stretching vibration absorption peak of -CH2- bond is at 2918 cm -1 wherein the symmetric stretching vibration absorption peak of -CH2- bond is at 2850 cm -1 wherein the stretching vibration absorption peak of C=O bond in ester group is at 1668 cm -1 wherein the in-plane bending vibration absorption peak of N-H bond in amide group is at 1554 cm -1 wherein the stretching vibration absorption peak of C-N bond is at 1406 cm -1 wherein the stretching vibration absorption peak of C-O-C bond is at 1103 cm -1 wherein the out-of-plane bending vibration absorption peak of N-H bond is at 802 cm -1 All groups in the target structure of the polymer are successfully synthesized, and there is no double bond absorption peak in the spectrum, indicating that the polymer synthesis is successful and the structure is stable.

[0115] According to the above results, the temperature-resistant and salt-resistant cationic polymer provided by the present application exhibits significant advantages and superiorities. First, in terms of thickening performance, the apparent viscosity of the polymer prepared in the examples is significantly higher than that of the comparative examples, indicating that the polymer has excellent thickening capacity. This characteristic makes the polymer have significant advantages in applications that require to improve the viscosity of liquids, such as oil and gas field exploitation, water treatment, etc.

[0116] Secondly, the polymer exhibits excellent salt resistance. In aqueous solutions containing high concentrations of NaCl and CaCl2, the polymer can still maintain a relatively high apparent viscosity, showing its strong salt resistance. This is a very important characteristic for applications used in saline-alkali land, seawater or salt-containing water environment.

[0117] In addition, the polymer also has good temperature resistance. The apparent viscosity of the polymer was measured at different temperatures, and the results showed that the polymer can still maintain stable viscosity at high temperature, indicating that it has excellent temperature resistance. This makes the polymer have unique advantages in applications at high temperature, such as the exploitation of high-temperature oil and gas wells.

[0118] Finally, through FTIR characterization, it is confirmed that all groups in the target structure of the polymer are successfully synthesized, and there is no double bond absorption peak in the spectrum, indicating that the polymer synthesis is successful and the structure is stable. This result further proves the reliability of the synthesis method and structure of the polymer, which provides a strong guarantee for its stability and durability in practical applications.

[0119] In summary, the temperature-resistant and salt-resistant cationic polymer not only has excellent thickening performance, but also exhibits excellent salt resistance and temperature resistance, and stable chemical structure. These advantages make the polymer have broad application prospects and unique advantages in many fields, especially in oil and gas field development, water treatment, high temperature environment application, etc.

[0120] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including aggregation of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application and belong to the protection scope of the present application.

Claims

1. A heat and salt resistant cationic hydrophobically associating polymer, characterized in that, The polymer is formed by polymerization of the following raw materials: acrylamide, N,N-dimethyl-N-methyl acryloyloxyethyl-N-2-hydroxy-1-octadecylamino propyl ammonium chloride, ammonium persulfate, sodium bisulfite, fatty alcohol polyoxyethylene ether, solvent; The N,N-dimethyl-N-methyl acryloyloxyethyl-N-2-hydroxy-1-octadecylamino propyl ammonium chloride has a structure shown in formula (1), and the acrylamide has a structure shown in formula (2); In the cationic polymer, the content of the N,N-dimethyl-N-methyl acryloyloxyethyl-N-2-hydroxy-1-octadecylamino propyl ammonium chloride is 0.8 parts by weight, the content of the acrylamide is 6-12 parts by weight, and the content of the fatty alcohol polyoxyethylene ether is 0.3-0.35 parts by weight, relative to 100 parts by weight of the solvent.

2. The polymer of claim 1, wherein The acrylamide needs to be configured as an aqueous solution with a concentration of 20-25 wt% when mixed.

3. The polymer of claim 1 or 2, wherein, The solvent is deionized water.

4. A method for preparing a temperature and salt resistant cationic polymer, characterized by, The method comprises mixing the raw materials used in the polymer of any one of claims 1-3.

5. The method of claim 4, wherein, The operation of mixing the raw materials in the temperature-resistant and salt-resistant cationic polymer comprises the following steps: (1) in the presence of a first portion of the solvent, first mixing the fatty alcohol polyoxyethylene ether and the N,N-dimethyl-N-methyl acryloyloxyethyl-N-2-hydroxy-1-octadecylamino propyl ammonium chloride to obtain a first mixed solution, and first contacting an acrylamide solution with a second portion of the solvent to dissolve to obtain solution I; (2) second mixing the first mixed solution with the solution I to obtain a second mixed solution, and second contacting ammonium persulfate and sodium bisulfite with a mass ratio of 1:1 with a third portion of the solvent to dissolve to obtain solution II; (3) contacting the second mixed solution with the solution II to react; The use amount weight ratio of the first portion of the solvent, the second portion of the solvent and the third portion of the solvent is 4-5:4-5:

1.

6. The method of claim 5, wherein, The conditions for first mixing the acrylamide and the N,N-dimethyl-N-methyl acryloyloxyethyl-N-2-hydroxy-1-octadecylamino propyl ammonium chloride and second mixing the first mixed solution with the solution I include that the stirring speed is 50-60 rpm, the temperature is 20-30℃, and the time is 5-10 min.

7. The method according to claim 5 or 6, characterized in that, In step (3), the conditions for the contacting reaction include that the temperature is 50-55℃, and the time is 6-7 h.

8. Application of the temperature-resistant and salt-resistant cationic polymer of claim 1 in oil and gas development.

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