Polymer and preparation method therefor and use thereof, and profile control and flooding agent

Abstract

The present invention relates to the technical field of chemical oil displacement agents. Disclosed are a polymer and a preparation method therefor and the use thereof, and a profile control and flooding agent. The polymer comprises at least one structural unit A of formula (1), at least one structural unit B of formula (2) and at least one structural unit C of formula (3), wherein Y is selected from the structure of formula (I), the structure of formula (II), the structure of formula (III) or the structure of formula (IV), a is an integer from 0-22, b is 2, c is 1, d is 2 or 3, R6 is -COO- or -CO-NH-, X is independently halogen, and Z is a residue obtained after dehydroxylation of cyclodextrin; and based on the total mass of the polymer, the content of the structural unit A is 40-65 wt%, the content of the structural unit B is 5-30 wt%, and the content of the structural unit C is 15-40 wt%. The polymer has strong salt resistance, temperature resistance and adsorption resistance.

Description

Polymer, preparation method and application thereof, and displacement agent

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application No. 202310789317.7 filed on June 30, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the technical field of chemical oil displacement agents, and in particular to a polymer, a preparation method and application thereof, and a displacement agent. Background Art

[0004] Polymer flooding is currently one of the key methods for enhancing oil recovery in oilfields. Although partially hydrolyzed polyacrylamide (HPAM) exhibits excellent thickening, viscoelastic, and rheological properties, its viscosity decreases dramatically with increasing temperature and salinity. In practical applications, increasing HPAM concentrations necessitates a significant increase in production costs, limiting its widespread application in high-temperature and high-salinity reservoirs. Therefore, developing temperature- and salt-resistant polymers is crucial for enhancing oil recovery.

[0005] "Improved viscoelasticity of xanthan gum through self-association with surfactant: β-cyclodextrin inclusion complexes for applications in enhanced oil recovery" (L Romero-Zerón, Rodrigue D. Polymer Engineering & Science, 2015, 55(3): 523-532.) cyclodextrin is mixed with xanthan gum and an ionic surfactant to form a self-assembled system with a host-guest network structure for improving oil recovery. However, the above system only has weak interactions and has poor anti-adsorption performance. Based on this, it is urgent to provide a supramolecular polymer with temperature resistance, salt resistance, and adsorption resistance.

[0006] Summary of the Invention

[0007] The purpose of the present invention is to overcome the problems of poor temperature resistance, salt resistance and adsorption resistance of polymers in the prior art, and to provide a polymer, a preparation method and application thereof, and a flooding agent. The polymer has strong salt resistance, temperature resistance and adsorption resistance, and the flooding agent made from the polymer has excellent oil displacement effect.

[0008] In order to achieve the above object, the first aspect of the present invention provides a polymer, wherein the polymer comprises at least one structural unit A represented by formula (1), at least one structural unit B represented by formula (2) and at least one structural unit C represented by formula (3), wherein:

[0009] Wherein, R1 is H, C1-C 18 Alkyl, -R2-SO3H, -R3-COOH or wherein R2 is a C3-C4 straight chain or branched alkyl group, R3 is a C4-C8 straight chain or branched alkyl group, n is an integer from 0 to 2, R4 is H or a C1-C4 straight chain alkyl group, and R5 is H or methyl;

[0010] Y is selected from the structure shown in Formula I, the structure shown in Formula II, the structure shown in Formula III or the structure shown in Formula IV,

[0011] wherein a is an integer from 0 to 22, b is 2, c is 1, d is 2 or 3, R6 is -COO- or -CO-NH-, and X is each independently a halogen;

[0012] Z is the residue after dehydroxylation of cyclodextrin;

[0013] Based on the total mass of the polymer, the content of the structural unit A is 40-65 wt%, the content of the structural unit B is 5-30 wt%, and the content of the structural unit C is 15-40 wt%.

[0014] A second aspect of the present invention provides a method for preparing a polymer, wherein the method comprises: mixing at least one monomer A represented by formula (4), at least one monomer B represented by formula (5), and at least one monomer C represented by formula (6) with water to obtain a monomer mixed solution, adjusting the pH value of the monomer mixed solution, adding an initiator, carrying out a polymerization reaction under a nitrogen atmosphere, and obtaining a polymer through post-treatment;

[0015] Wherein, R1' is H, C1-C 18 Alkyl, -R2'-SO3H, -R3'-COOH or wherein R2' is a C3-C4 straight chain or branched alkyl group, R3' is a C4-C8 straight chain or branched alkyl group, n' is an integer from 0 to 2, R4' is H or a C1-C4 straight chain alkyl group, and R5' is H or methyl;

[0016] Y' is selected from the structure shown in formula I', the structure shown in formula II', the structure shown in formula III' or the structure shown in formula IV',

[0017] wherein a' is an integer from 0 to 22, b' is 2, c' is 1, d' is 2 or 3, R6' is -COO- or -CO-NH-, and X' is each independently a halogen;

[0018] Z' is the residue after dehydroxylation of cyclodextrin;

[0019] Wherein, based on the total weight of the monomer A, monomer B and monomer C, the amount of the monomer A is 40-65 wt %, the amount of the monomer B is 5-30 wt %, and the amount of the monomer C is 15-40 wt %.

[0020] The third aspect of the present invention provides a polymer obtained by the above preparation method.

[0021] A fourth aspect of the present invention provides a use of the above polymer as a displacement agent.

[0022] A fifth aspect of the present invention provides a use of the above polymer as an oily detergent.

[0023] A sixth aspect of the present invention provides a displacement agent, wherein the displacement agent comprises the above-mentioned polymer and water.

[0024] Through the above technical solution, the present invention provides a polymer, a preparation method and application thereof, and a displacement agent having the following beneficial effects:

[0025] The polymer of the present invention comprises a structural unit A represented by formula (1), a structural unit B represented by formula (2) and a structural unit C represented by formula (3), so that the polymer has excellent heat resistance, salt resistance and adsorption resistance. Specifically, through the structural unit C, a cyclodextrin having a rigid structure is introduced into the polymer through a covalent bond, so that the polymer has obvious heat resistance, salt resistance and shear resistance. At 85° C., the viscosity retention rate of the polymer is ≥90%, and it has the characteristics of high temperature resistance, and the temperature resistance reaches above 85° C. At a salinity of 100,000 mg / L, the viscosity retention rate of the polymer is ≥80%, and it has high salt resistance, and the salt resistance can reach a salinity of more than 100,000 mg / L. The introduction of the structural unit B represented by formula (2) makes the polymer have excellent adsorption resistance, and the static adsorption viscosity retention rate of the polymer is ≥85%.

[0026] Furthermore, when the content of each structural unit is within a specific range, the oil-displacing agent made from the polymer has an excellent oil-displacing effect, and its static oil removal rate is ≥90%; the polymer of the present invention is applied to oil-stain detergents. Since the cyclodextrin structure with internal hydrophilicity and external hydrophobicity is introduced into the polymer, it has the properties of a surfactant, so it can exert a washing effect without phase separation, and the oil-stain cleaning rate reaches more than 80%.

[0027] The polymers prepared by using monomers represented by formulas (4) to (6) as raw materials in the polymer preparation process provided by the present invention have excellent heat resistance, salt resistance and anti-adsorption properties; when each monomer is used in a specific amount, the oil displacement agent prepared from the polymer has an excellent oil displacement effect; the present invention uses maleic acid cyclodextrin ester as a raw material, which is environmentally friendly. At the same time, the synthesis conditions of the polymer are easy to control, the reaction process is stable, and it is relatively easy to achieve industrialization. DETAILED DESCRIPTION

[0028] 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.

[0029] The first aspect of the present invention provides a polymer, wherein the polymer comprises at least one structural unit A represented by formula (1), at least one structural unit B represented by formula (2) and at least one structural unit C represented by formula (3), wherein:

[0030] Wherein, R1 is H, C1-C 18 Alkyl, -R2-SO3H, -R3-COOH or wherein R2 is a C3-C4 straight chain or branched alkyl group, R3 is a C4-C8 straight chain or branched alkyl group, n is an integer from 0 to 2, R4 is H or a C1-C4 straight chain alkyl group, and R5 is H or methyl;

[0031] Y is selected from the structure shown in Formula I, the structure shown in Formula II, the structure shown in Formula III or the structure shown in Formula IV,

[0032] wherein a is an integer from 0 to 22, b is 2, c is 1, d is 2 or 3, R6 is -COO- or -CO-NH-, and X is each independently a halogen;

[0033] Z is the residue after dehydroxylation of cyclodextrin;

[0034] Based on the total mass of the polymer, the content of the structural unit A is 40-65 wt%, the content of the structural unit B is 5-30 wt%, and the content of the structural unit C is 15-40 wt%.

[0035] In the present invention, the polymer contains a structural unit A represented by formula (1), a structural unit B represented by formula (2) and a structural unit C represented by formula (3), so that the polymer has excellent temperature resistance, salt resistance and anti-adsorption properties; specifically, through the structural unit C, a cyclodextrin with a rigid structure is introduced into the polymer through a covalent bond, so that the polymer has obvious temperature resistance, salt resistance and shear resistance. At 85°C, the viscosity retention rate of the polymer is ≥90%, and it has the characteristics of high temperature resistance, and the temperature resistance reaches above 85°C. At a mineralization of 100,000 mg / L, the viscosity retention rate of the polymer is ≥80%, and it has high salt resistance, and the salt resistance can reach a mineralization of more than 100,000 mg / L; the introduction of the structural unit B represented by formula (2) makes the polymer have excellent anti-adsorption performance, and the static adsorption viscosity retention rate of the polymer is ≥85%.

[0036] Furthermore, when the content of each structural unit is within a specific range, the oil-displacing agent made from the polymer has an excellent oil-displacing effect, and its static oil removal rate is ≥90%; the polymer of the present invention is applied to oil-stain detergents. Since the cyclodextrin structure with internal hydrophilicity and external hydrophobicity is introduced into the polymer, it has the properties of a surfactant, so it can exert a washing effect without phase separation, and the oil-stain cleaning rate reaches more than 80%.

[0037] In the present invention, the carbon atom in R6 is connected to the carbon atom in formula (2). In the present invention, the sum of the contents of structural unit A, structural unit B and structural unit C is 100wt%. The content of structural unit A can be 40wt%, 41wt%, 42wt%, 43wt%, 44wt%, 45wt%, 46wt%, 47wt%, 48wt%, 49wt%, 50wt%, 51wt%, 52wt%, 53wt%, 54wt%, 55wt%, 56wt%, 57wt%, 58wt%, 59wt%, 60wt%, 61wt%, 62wt%, 63wt%, 64wt%, 65wt%, and the range consisting of any two of the above values. The content of the structural unit B can be 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, 30wt%, and the range consisting of any two of the above values. The content of the structural unit C can be 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, 30wt%, 31wt%, 32wt%, 33wt%, 34wt%, 35wt%, 36wt%, 37wt%, 38wt%, 39wt%, 40wt%, and the range consisting of any two of the above values.

[0038] Further, R1 is H, C3-C 12 Alkyl, -R2-SO3H, -R3-COOH or R1 is preferably C3-C 12 Alkyl, -R2-SO3H, -R3-COOH or Wherein, R2 is isobutyl; R3 is isobutyl, n is 0 or 1, R4 is H or C1-C2 alkyl, and R5 is H.

[0039] Furthermore, a is an integer of 0-18, b is 2, c is 1, d is 2 or 3, R6 is -COO- or -CO-NH-, and X is a chloride ion. In the present invention, a can be any value of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 and 18.

[0040] Furthermore, the cyclodextrin is selected from at least one of α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, 2-hydroxypropyl-β-cyclodextrin, and 2-hydroxypropyl-γ-cyclodextrin. Preferably, the cyclodextrin is selected from at least one of β-cyclodextrin, γ-cyclodextrin, 2-hydroxypropyl-β-cyclodextrin, and 2-hydroxypropyl-γ-cyclodextrin.

[0041] Furthermore, based on the total mass of the polymer, the content of the structural unit A is 45-63 wt%, the content of the structural unit B is 7-29 wt%, and the content of the structural unit C is 18-35 wt%.

[0042] According to the present invention, the structural unit B includes the structure shown in formula (2-1) and the structure shown in formula (2-2);

[0043] In the present invention, when the structure represented by formula (2-1) and the structure represented by formula (2-2) are simultaneously used as structural unit B, a synergistic effect can be produced between the two structures, thereby further improving the temperature resistance, salt resistance and anti-adsorption properties of the polymer.

[0044] According to the present invention, in the structural unit B, the weight ratio of the structure represented by the formula (2-1) to the structure represented by the formula (2-2) is 1-4:1. In the present invention, the weight ratio of the structure represented by the formula (2-1) to the structure represented by the formula (2-2) can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, and a range consisting of any two of the above ratios.

[0045] Furthermore, in the structural unit B, the weight ratio of the structure represented by the formula (2-1) to the structure represented by the formula (2-2) is 1-3.5:1.

[0046] According to the present invention, the viscosity-average relative molecular weight of the polymer is 1,000,000-8,000,000 g / mol.

[0047] Furthermore, the viscosity-average relative molecular weight of the polymer is 1,000,000-6,000,000 g / mol.

[0048] A second aspect of the present invention provides a method for preparing a polymer, wherein the method comprises: mixing at least one monomer A represented by formula (4), at least one monomer B represented by formula (5), and at least one monomer C represented by formula (6) with water to obtain a monomer mixed solution, adjusting the pH value of the monomer mixed solution, adding an initiator, carrying out a polymerization reaction under a nitrogen atmosphere, and obtaining a polymer through post-treatment;

[0049] Wherein, R1' is H, C1-C 18Alkyl, -R2'-SO3H, -R3'-COOH or wherein R2' is a C3-C4 straight chain or branched alkyl group, R3' is a C4-C8 straight chain or branched alkyl group, n' is an integer from 0 to 2, R4' is H or a C1-C4 straight chain alkyl group, and R5' is H or methyl;

[0050] Y' is selected from the structure shown in formula I', the structure shown in formula II', the structure shown in formula III' or the structure shown in formula IV',

[0051] wherein a' is an integer from 0 to 22, b' is 2, c' is 1, d' is 2 or 3, R6' is -COO- or -CO-NH-, and X' is each independently a halogen;

[0052] Z' is the residue after dehydroxylation of cyclodextrin;

[0053] Wherein, based on the total mass of the monomer A, monomer B and monomer C, the amount of the monomer A is 40-65wt%, the amount of the monomer B is 5-30wt%, and the amount of the monomer C is 15-40wt%.

[0054] In the present invention, the polymer prepared by using the monomers represented by formulas (4) to (6) as raw materials in the polymer preparation process has excellent temperature resistance, salt resistance and anti-adsorption properties; when each monomer is used in a specific amount, the oil displacement agent prepared from the polymer has an excellent oil displacement effect; the present invention uses maleic acid cyclodextrin ester as a raw material, which is environmentally friendly. At the same time, the synthesis conditions of the polymer are easy to control, the reaction process is stable, and it is relatively easy to achieve industrialization.

[0055] In the present invention, the maleic acid-cyclodextrin ester can be prepared according to existing methods. Preferably, the preparation method of the maleic acid-cyclodextrin ester comprises: weighing cyclodextrin (α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, 2-hydroxypropyl-β-cyclodextrin, or 2-hydroxypropyl-γ-cyclodextrin) and maleic anhydride in a mass ratio of 1:0.5-1.5, stirring and mixing with N,N-dimethylformamide, and heating the mixture solution at 70-90°C for 8-12 hours. After the reaction is completed, the solution is cooled, chloroform is added, and then washed with acetone and dried.

[0056] In the present invention, the carbon atom in R6' is connected to the carbon atom in formula (6).

[0057] In the present invention, the content of monomer A can be 40wt%, 41wt%, 42wt%, 43wt%, 44wt%, 45wt%, 46wt%, 47wt%, 48wt%, 49wt%, 50wt%, 51wt%, 52wt%, 53wt%, 54wt%, 55wt%, 56wt%, 57wt%, 58wt%, 59wt%, 60wt%, 61wt%, 62wt%, 63wt%, 64wt%, 65wt%, and the range consisting of any two of the above values. The content of the monomer B can be 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, 30wt%, and a range consisting of any two of the above values. The content of the monomer C can be 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, 30wt%, 31wt%, 32wt%, 33wt%, 34wt%, 35wt%, 36wt%, 37wt%, 38wt%, 39wt%, 40wt%, and a range consisting of any two of the above values.

[0058] Further, R1' is H, C3-C 12 Alkyl, -R2'-SO3H, -R3'-COOH or R1' is preferably C3-C 12 Alkyl, -R2'-SO3H, -R3'-COOH or Wherein, R2' is isobutyl; R3' is isobutyl, n' is 0 or 1, R4' is H or C1-C2 alkyl, and R5' is H.

[0059] Furthermore, a' is an integer of 0-18, b' is 2, c' is 1, d' is 2 or 3, R6' is -COO- or -CO-NH-, and X' is a chloride ion. In the present invention, a' can be any value of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, and 18.

[0060] Furthermore, the cyclodextrin is selected from at least one of α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, 2-hydroxypropyl-β-cyclodextrin, and 2-hydroxypropyl-γ-cyclodextrin. Preferably, the cyclodextrin is selected from at least one of β-cyclodextrin, γ-cyclodextrin, 2-hydroxypropyl-β-cyclodextrin, and 2-hydroxypropyl-γ-cyclodextrin.

[0061] Furthermore, based on the total mass of the monomer A, monomer B and monomer C, the amount of the monomer A is 45-63 wt %, the amount of the monomer B is 7-29 wt %, and the amount of the monomer C is 18-35 wt %.

[0062] According to the present invention, the monomer B includes the structure shown in formula (5-1) and the structure shown in formula (5-2);

[0063] In the present invention, when monomer B adopts the above combination, the obtained polymer has high temperature resistance, high salt resistance and high anti-adsorption performance.

[0064] According to the present invention, the ratio of monomer B of the structure represented by formula (5-1) to monomer B of the structure represented by formula (5-2) is 1-4:1 relative to the total amount of monomer B. In the present invention, the ratio of monomer B of the structure represented by formula (5-1) to monomer B of the structure represented by formula (5-2) can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, and a range consisting of any two of the above ratios.

[0065] According to the present invention, the initiator is selected from at least one of sodium bisulfite, sodium thiosulfate, sodium metabisulfite, potassium persulfate, sodium persulfate, hydrogen peroxide, 2,2'-azo[2-(2-imidazolin-2-yl)propane]dihydrochloride, azobis(2,5-dimethyl-6-carboxyl)hexanenitrile and 4,4'-azobis(4-cyanovaleric acid).

[0066] In the present invention, when the above-mentioned initiator is selected, it is more conducive to the polymerization reaction between monomers, so that the polymer has the characteristics of less homopolymer content, and the obtained polymer has excellent temperature resistance, salt resistance and anti-adsorption properties.

[0067] Furthermore, the initiator is an initiator composition of potassium persulfate and sodium bisulfite, or an initiator composition of ammonium persulfate and sodium bisulfite.

[0068] In a preferred embodiment of the present invention, the sodium bisulfite is 20-35 parts by weight relative to 100 parts by weight of the initiator composition. In the present invention, the sodium bisulfite can be 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, 35 parts by weight, and a range consisting of any two parts by weight thereof, relative to 100 parts by weight of the initiator composition.

[0069] According to the present invention, the amount of the initiator added is 0.1-0.6 wt % based on the total mass of the monomers A, B, and C. In the present invention, the amount of the initiator added can be 0.1 wt %, 0.2 wt %, 0.3 wt %, 0.4 wt %, 0.5 wt %, 0.6 wt %, or a range consisting of any two of the above values, based on the total mass of the monomers A, B, and C.

[0070] Furthermore, based on the total mass of the monomer A, monomer B and monomer C, the added amount of the initiator is 0.3-0.6 wt%.

[0071] According to the present invention, the pH value of the monomer mixture solution is adjusted to 6-8.

[0072] In the present invention, the monomer mixed solution is generally acidic, and those skilled in the art can use alkaline solution to control the pH of the monomer mixed solution according to actual conditions. Preferably, the alkaline solution can be sodium hydroxide solution or potassium hydroxide solution.

[0073] According to the present invention, the polymerization reaction temperature is 5-50° C., and the polymerization reaction time is 6-9 hours.

[0074] In the present invention, when the polymerization reaction meets the above conditions, it is more conducive to polymerization between monomers and the reaction process is stable.

[0075] Furthermore, the polymerization reaction temperature is 10-40° C., and the polymerization reaction time is 7-8 hours.

[0076] In the present invention, the post-treatment includes: precipitation with an organic solvent, filtration, drying and pulverization. The organic solvent can be selected from acetone, ethanol or methanol.

[0077] The third aspect of the present invention provides a polymer obtained by the above preparation method.

[0078] According to the present invention, the viscosity-average relative molecular weight of the polymer is 1,000,000-8,000,000 g / mol.

[0079] Furthermore, the viscosity-average relative molecular weight of the polymer is 1,000,000-6,000,000 g / mol.

[0080] A fourth aspect of the present invention provides a use of the above polymer as a displacement agent.

[0081] The polymer of the present invention has excellent heat resistance, salt resistance and adsorption resistance, can adapt to the environment of oil displacement operation, and the prepared displacement agent has excellent oil displacement effect, and its static oil removal rate is ≥90%, which can meet the oil displacement needs of oil fields.

[0082] A fifth aspect of the present invention provides a use of the above polymer as an oily detergent.

[0083] The polymer of the present invention is applied to oily dirt detergents. Since the polymer has a hydrophilic inner and hydrophobic outer cyclodextrin structure, it has surfactant properties and can exert a cleaning effect without phase separation, with an oily dirt cleaning rate of over 80%.

[0084] In the present invention, water and polymer can be mixed according to actual needs to prepare an oily stain detergent. For example, the polymer can be prepared into a 1-3 wt% aqueous solution for use as an oily stain detergent, and the cleaning time can be 10-25 minutes.

[0085] A sixth aspect of the present invention provides a displacement agent, wherein the displacement agent comprises the above-mentioned polymer and water.

[0086] In the present invention, the oil displacement agent has excellent temperature resistance, salt resistance and adsorption resistance, can adapt to the environment of oil displacement operation, and the prepared oil displacement agent has excellent oil displacement effect, and its static oil removal rate is ≥90%.

[0087] According to the present invention, the polymer is present in an amount of 0.1-5 parts by weight, preferably 0.1-2.5 parts by weight, relative to 100 parts by weight of water.

[0088] According to the present invention, the displacement agent further comprises a surfactant.

[0089] In the present invention, the type and amount of the surfactant can be selected conventionally in the art and are not limited thereto. For example, the surfactant is present in an amount of 0.1 to 10 parts by weight relative to 100 parts by weight of water.

[0090] The present invention will be described in detail below through examples.

[0091] The content of each structural unit in the polymer is obtained by the ratio of the peak area of ​​each structural unit in the nuclear magnetic resonance hydrogen spectrum.

[0092] The viscosity-average relative molecular weight of the polymer at 25°C is measured by the intrinsic viscosity in 6.5.2 of SY / T 5862-2020, and then the viscosity-average relative molecular mass is calculated according to formula (13) in 6.5.3 of SY / T5862-2020;

[0093] Among them, M η is the annual average relative molecular mass of the polymer, dimensionless; [η] is the intrinsic viscosity, unit is mL / g; 0.000373 is an empirical constant; 1.515 is an empirical constant.

[0094] Oil removal rate: The test was conducted using a static oil removal experiment at normal pressure. Specifically: (1) Preparation of oil sand: Quartz sand and crude oil (density 0.85 g / cm 3 ) were mixed in a mass ratio of 8:2, and then aged in an oven at 45°C for 24 hours to obtain oil sand; (2) 15g of oil sand was placed in a de-oiling bottle, and the crude oil volume value was the crude oil mass / crude oil density. After the oil sand was compacted, a polymer aqueous solution (polymer solution concentration of 0.01wt%) was injected to the 1mL mark, and then placed in a constant temperature box (45°C). The volume value of the oil output was recorded regularly. The de-oiling rate = (volume value of oil output / volume value of crude oil) × 100%.

[0095] Oil cleaning rate: The polymer is mixed with water to prepare a 2.5wt% polymer aqueous solution, and the cleaning is carried out by immersion.

[0096] S1: Preparation of synthetic oil: Refer to the synthesis method specified in GB / T 23435-2009. In a fume hood, mix 150g of SF 15W / 40 gasoline engine oil and 30g of A100 carbon black powder and add them to a 500mL three-necked flask. Introduce an air flow of 8.5cm3 / min into the flask. Heat the three-necked flask with a constant temperature heating mantle at 240±5℃ for 10h to obtain synthetic oil for use.

[0097] S2: Preparation of artificial oil pollution test plate: Take a 25×5mm cast iron block, polish the entire cast iron block with P150 sandpaper, wipe it with acetone and anhydrous ethanol, bake it in a 120±5℃ oven for 2h, cool it to room temperature, weigh the weight of the hook and the test plate to the nearest 0.1mg, and mark it as m0; dip the artificial synthetic oil with a glass rod, and apply it to both surfaces of the dried cast iron block. Remember to scrape it evenly without exposing the bottom, bake it in a 120±5℃ oven for 2h, cool it to room temperature, weigh the weight of the hook and the test plate to the nearest 0.1mg, and mark it as m1.

[0098] S3: Cleaning rate test: Pour the polymer aqueous solution sample into a 500mL beaker, fix the aged artificial oil test plate with a clamp, start the swing washing machine switch, confirm that the oil test plate will not touch the inner wall of the beaker, and then put the oil test plate into the composite solvent in the beaker, soak for 5 minutes and then swing wash for 5 minutes. Note that the swing washing conditions are a swing washing distance of 50mm and a swing washing speed of 60 times / min. Use an ear washing bulb to blow dry the unvolatile solvent on the oil test plate after swing washing (to avoid the surface temperature of the cast iron block being too low and condensing into dew droplets, causing rust), put it in a 120±5℃ oven and bake for half an hour. After cooling to room temperature in a drying dish, weigh the hook and the test plate to an accuracy of 0.1mg and mark it as m2.

[0099] S4: Calculation of oil cleaning rate: The calculation formula of oil cleaning rate W is: W = (m1-m2) / (m1-m0)×100%, where m0 is the mass of blank test plate and hook, m1 is the mass of test plate and hook after artificial oil stain aging, and m2 is the mass of test plate and hook after artificial oil stain is washed with composite solvent.

[0100] The polymer's salt tolerance was evaluated by preparing 0.01 wt% aqueous solutions of the polymer in clean water and 100,000 mg / L saline solution. The apparent viscosity (in cP) of each solution was measured using a Brookfield viscometer at 25°C and 6 r / min. The viscosity retention rate in the 100,000 mg / L saline solution was calculated as: the ratio of the apparent viscosity of the polymer in the 100,000 mg / L saline solution to the apparent viscosity of the polymer in clean water × 100%.

[0101] To evaluate the polymer's heat resistance, a 0.01 wt% aqueous solution of the polymer was prepared with water. The apparent viscosity (in cP) of each solution was measured at 25°C and 85°C using a Brookfield viscometer at 6 r / min. The viscosity retention at 85°C was calculated as the ratio of the apparent viscosity of the polymer at 85°C to the apparent viscosity of the polymer at 25°C × 100%.

[0102] Evaluation of the anti-adsorption property of the polymer: The anti-adsorption property of the polymer of the present invention is evaluated by the static adsorption viscosity retention rate. The method comprises: (1) washing quartz sand with a particle size range of 0.35-0.5 mm with deionized water and drying at 105°C, repeating twice. The polymer is prepared into a polymer aqueous solution with a mass concentration of 0.01 wt% with clean water, and the apparent viscosity (in cP) of the polymer aqueous solution is measured using a Brookfield viscometer at 75°C and a rotation speed of 6 r / min, which is recorded as η0. (2) 25 g of quartz sand is placed in a 250 mL stoppered bottle, 75 g of the polymer aqueous solution is added, shaken and placed in a constant temperature water bath oscillator with an oscillation frequency of 120 times / min, and reciprocated at 30°C for 24 hours. Take out the sample, centrifuge it and take the supernatant liquid. Preheat the constant temperature water bath, and measure the apparent viscosity (in cP) of the supernatant liquid again at 75°C and a rotation speed of 6 r / min, which is recorded as η1. The static adsorption viscosity retention rate is η1 / η0×100%.

[0103] Maleic anhydride, α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, 2-hydroxypropyl-β-cyclodextrin and 2-hydroxypropyl-γ-cyclodextrin raw materials are all commercial products of Shanghai Aladdin Biochemical Technology Co., Ltd.

[0104] Initiator composition A: the mass ratio of ammonium persulfate and sodium bisulfite is 1:0.5;

[0105] Initiator composition B: the mass ratio of potassium persulfate and sodium bisulfite is 1:0.4;

[0106] Other raw materials used in the examples and comparative examples are all commercially available.

[0107] The room temperature described in the preparation examples is 25°C.

[0108] Preparation Example 1

[0109] Preparation of maleic acid-α-cyclodextrin ester: 9 g of α-cyclodextrin, 9 g of maleic anhydride, and 8 mL of N,N-dimethylformamide were stirred and mixed. The mixture was heated at 80°C for 10 hours. After the reaction was complete, the solution was cooled to room temperature. 60 mL of chloroform was added to obtain a white precipitate, which was then washed with copious amounts of acetone. Finally, the precipitate was dried in a vacuum oven at 80°C. This yielded maleic acid-α-cyclodextrin ester.

[0110] Preparation Example 2

[0111] Preparation of maleic acid-β-cyclodextrin ester: 11 g of β-cyclodextrin, 10 g of maleic anhydride, and 10 mL of N,N-dimethylformamide were stirred and mixed. The mixture was heated at 80°C for 10 hours. After the reaction was complete, the solution was cooled to room temperature. 60 mL of chloroform was added to obtain a white precipitate, which was then washed with copious amounts of acetone. Finally, the precipitate was dried in a vacuum oven at 80°C. This yielded maleic acid-β-cyclodextrin ester.

[0112] Preparation Example 3

[0113] Preparation of maleic acid-γ-cyclodextrin ester: 12 g of γ-cyclodextrin, 11 g of maleic anhydride, and 11 mL of N,N-dimethylformamide were stirred and mixed. The mixture was heated at 80°C for 10 hours. After the reaction was complete, the solution was cooled to room temperature. 60 mL of chloroform was added to obtain a white precipitate, which was then washed with copious amounts of acetone. Finally, the precipitate was dried in a vacuum oven at 80°C. This yielded maleic acid-γ-cyclodextrin ester.

[0114] Preparation Example 4

[0115] Preparation of maleic acid-2-hydroxypropyl-β-cyclodextrin ester: 14 g of 2-hydroxypropyl-β-cyclodextrin, 13 g of maleic anhydride, and 15 mL of N,N-dimethylformamide were stirred and mixed. The mixture was heated at 80°C for 10 hours. After the reaction was complete, the solution was cooled to room temperature. 60 mL of chloroform was added to obtain a white precipitate, which was then washed with a large amount of acetone. Finally, it was dried in a vacuum oven at 80°C. This yielded maleic acid-2-hydroxypropyl-β-cyclodextrin ester.

[0116] Preparation Example 5

[0117] Preparation of maleic acid-2-hydroxypropyl-γ-cyclodextrin ester: 16 g of 2-hydroxypropyl-propyl cyclodextrin, 15 g of maleic anhydride, and 18 mL of N,N-dimethylformamide were stirred and mixed. The mixture was heated at 80°C for 10 hours. After the reaction was complete, the solution was cooled to room temperature. 60 mL of chloroform was added to obtain a white precipitate, which was then washed with a large amount of acetone. Finally, it was dried in a vacuum oven at 80°C. This yielded maleic acid-2-hydroxypropyl-γ-cyclodextrin ester.

[0118] Example 1

[0119] 0.54 g of N-vinylpyrrolidone, 0.16 g of allyltrimethylammonium chloride, 5.3 g of 2-acrylamido-2-methylpropanesulfonic acid, and 3 g of maleic acid-β-cyclodextrin ester were mixed and dissolved in 41 g of deionized water. Nitrogen was then introduced, and the pH of the system was adjusted to 6 with a sodium hydroxide solution. 0.04 g of initiator composition A (ammonium persulfate and sodium bisulfite) was added, and the mixture was reacted at 10°C for 7 hours. The mixture was cooled to room temperature, precipitated with acetone, filtered, dried, and pulverized to obtain a polymer. The polymer test results are shown in Table 1.

[0120] The prepared polymer comprises:

[0121] Structural unit A( Among them, R1 is R4 is H); structural unit B ( and wherein R5 is H and X is a chloride ion); structural unit C( Wherein, Z is the residue after dehydroxylation of β-cyclodextrin);

[0122] Based on the total mass of the polymer, the content of the structural unit A is 58.9wt%, the content of the structural unit B is 7.8wt% (formula (2-1) is 6wt%, formula (2-2) is 1.8wt%, and the weight ratio is 3.3:1), and the content of the structural unit C is 33.3wt%.

[0123] Example 2

[0124] 5.3 g of 2-acrylamido-2-methylpropanesulfonic acid, 0.7 g of allyltrimethylammonium chloride, and 3 g of maleic acid-β-cyclodextrin ester were mixed and dissolved in 41 g of deionized water. Nitrogen was then introduced, and the pH of the system was adjusted to 6 with NaOH solution. 0.04 g of initiator composition A (ammonium persulfate and sodium bisulfite) was added, and the mixture was reacted at 10°C for 7 hours. The system was cooled to room temperature, precipitated with acetone, filtered, dried, and pulverized to obtain a polymer. The polymer test results are shown in Table 1.

[0125] The prepared polymer comprises:

[0126] Structural unit A( Among them, R1 is R4 is H); structural unit B ( Wherein, R5 is H, X is chloride ion); structural unit C ( Wherein, Z is the residue after dehydroxylation of β-cyclodextrin);

[0127] Based on the total mass of the polymer, the content of the structural unit A is 58.9 wt %, the content of the structural unit B is 7.8 wt %, and the content of the structural unit C is 33.3 wt %.

[0128] Example 3

[0129] 5.3 g of 2-acrylamide-2-methylpropanesulfonic acid, 0.7 g of N-vinylpyrrolidone, and 3 g of maleic acid-β-cyclodextrin ester were mixed and dissolved in 41 g of deionized water. Nitrogen was then introduced, and the pH of the system was adjusted to 6 with a NaOH solution. 0.04 g of initiator composition A (ammonium persulfate and sodium bisulfite) was added, and the mixture was reacted at 10°C for 7 hours. The system was cooled to room temperature, precipitated with acetone, filtered, dried, and pulverized to obtain a polymer. The polymer testing results are shown in Table 1.

[0130] The prepared polymer comprises:

[0131] Structural unit A( Among them, R1 is R4 is H); structural unit B ( Wherein, R5 is H); structural unit C( Wherein, Z is the residue after dehydroxylation of β-cyclodextrin);

[0132] Based on the total mass of the polymer, the content of the structural unit A is 58.9 wt %, the content of the structural unit B is 7.8 wt %, and the content of the structural unit C is 33.3 wt %.

[0133] Example 4

[0134] 1.4 g of N-vinyl pyrrolidone, 3.6 g of acrylamide, and 2.5 g of maleic acid-α-cyclodextrin ester were mixed and dissolved in 42.5 g of deionized water. Nitrogen was then introduced, and the pH of the system was adjusted to 6 with NaOH solution. 0.03 g of initiator composition A (ammonium persulfate and sodium bisulfite) was added, and the reaction was allowed to proceed at 10°C for 6 hours. The system was cooled to room temperature, precipitated with acetone, filtered, dried, and pulverized to obtain a polymer. The polymer testing results are shown in Table 1.

[0135] The prepared polymer comprises:

[0136] Structural unit A( Wherein, R1 and R4 are both H); structural unit B ( Wherein, R5 is H, Y is ); structural unit C( Wherein, Z is the residue after dehydroxylation of α-cyclodextrin);

[0137] Based on the total mass of the polymer, the content of the structural unit A is 48 wt %, the content of the structural unit B is 18.7 wt %, and the content of the structural unit C is 33.3 wt %.

[0138] Example 5

[0139] 2.6 g of acryloyloxyethyltrimethylammonium chloride, 4.9 g of N-dodecylacrylamide, and 2.5 g of maleic acid-γ-cyclodextrin ester were mixed and dissolved in 40 g of deionized water. Nitrogen was then introduced, and the pH of the system was adjusted to 8 with NaOH solution. 0.03 g of initiator composition B (potassium persulfate and sodium bisulfite) was added, and the reaction was carried out at 40°C for 8 hours. The system was cooled to room temperature, precipitated with acetone, filtered, dried, and pulverized to obtain a polymer. The polymer test results are shown in Table 1.

[0140] The prepared polymer comprises:

[0141] Structural unit A( Where R1 is C 12 alkyl, R4 is H); structural unit B ( Wherein, R5 is H, Y is ); structural unit C( Wherein, Z is the residue after dehydroxylation of γ-cyclodextrin);

[0142] Based on the total mass of the polymer, the content of the structural unit A is 49 wt %, the content of the structural unit B is 26 wt %, and the content of the structural unit C is 25 wt %.

[0143] Example 6

[0144] 3.1 g of methacryloyloxyethyldimethylbenzyl ammonium chloride, 5.9 g of N-isopropylacrylamide, and 2 g of maleic acid-2-hydroxypropyl-β-cyclodextrin ester were mixed and dissolved in 39 g of deionized water. Nitrogen was then introduced, and the pH of the system was adjusted to 8 with NaOH solution. 0.05 g of initiator composition B (potassium persulfate and sodium bisulfite) was then added. The reaction was continued at 45°C for 8 hours. The system was cooled to room temperature, precipitated with acetone, filtered, dried, and pulverized to obtain a polymer. The polymer test results are shown in Table 1.

[0145] The prepared polymer comprises:

[0146] Structural unit A( Wherein, R1 is isopropyl, R4 is H); structural unit B ( Wherein, R5 is H, Y is ); structural unit C( Wherein, Z is the residue after dehydroxylation of 2-hydroxypropyl-β-cyclodextrin);

[0147] Based on the total mass of the polymer, the content of the structural unit A is 53.6 wt %, the content of the structural unit B is 28.2 wt %, and the content of the structural unit C is 18.2 wt %.

[0148] Example 7

[0149] 2.2 g of (3-acrylamidopropyl)trimethylammonium chloride, 7.8 g of N-hydroxypropyl acrylamide, and 2.5 g of maleic acid-2-hydroxypropyl-γ-cyclodextrin ester were mixed and dissolved in 37.5 g of deionized water. Nitrogen was then introduced, and the pH of the system was adjusted to 8 with a NaOH solution. 0.05 g of initiator composition B (potassium persulfate and sodium bisulfite) was then added. The reaction was continued at 40°C for 9 hours. The system was cooled to room temperature, precipitated with acetone, filtered, dried, and pulverized to obtain a polymer. The polymer test results are shown in Table 1.

[0150] The prepared polymer comprises:

[0151] Structural unit A( Wherein, R1 is hydroxyl group, R4 is H); structural unit B ( Wherein, R5 is H, Y is ); structural unit C( Wherein, Z is the residue after dehydroxylation of 2-hydroxypropyl-γ-cyclodextrin);

[0152] Based on the total mass of the polymer, the content of the structural unit A is 62.4 wt %, the content of the structural unit B is 17.6 wt %, and the content of the structural unit C is 20 wt %.

[0153] Example 8

[0154] 0.6 g of N-vinylpyrrolidone, 0.1 g of allyltrimethylammonium chloride, 5.3 g of 2-acrylamido-2-methylpropanesulfonic acid, and 3 g of maleic acid-β-cyclodextrin ester were mixed and dissolved in 41 g of deionized water. Nitrogen was then introduced, and the pH of the system was adjusted to 6 with a sodium hydroxide solution. 0.04 g of initiator composition A (ammonium persulfate and sodium bisulfite) was added, and the mixture was reacted at 10°C for 7 hours. The mixture was cooled to room temperature, precipitated with acetone, filtered, dried, and pulverized to obtain a polymer. The polymer test results are shown in Table 1.

[0155] The prepared polymer comprises:

[0156] Structural unit A( Among them, R1 is R4 is H); structural unit B ( and wherein R5 is H and X is a chloride ion); structural unit C( Wherein, Z is the residue after dehydroxylation of β-cyclodextrin);

[0157] Based on the total mass of the polymer, the content of the structural unit A is 58.9wt%, the content of the structural unit B is 7.8wt% (formula (2-1) is 6.7wt%, formula (2-2) is 1.1wt%, and the weight ratio is 6.1:1), and the content of the structural unit C is 33.3wt%.

[0158] Comparative Example 1

[0159] 6g of 2-acrylamide-2-methylpropanesulfonic acid and 3g of maleic acid-β-cyclodextrin ester were mixed and dissolved in 41g of deionized water. Nitrogen was then introduced, and the pH of the system was adjusted to 6 with NaOH solution. 0.04g of initiator composition A (ammonium persulfate and sodium bisulfite) was added, and the reaction was carried out at 10°C for 7 hours. The system was cooled to room temperature, precipitated with acetone, filtered, dried, and pulverized to obtain a polymer. The polymer test results are shown in Table 1.

[0160] Structural unit A( Among them, R1 is R4 is H); structural unit C( Wherein, Z is the residue after dehydroxylation of β-cyclodextrin); based on the total mass of the polymer, the content of the structural unit A is 66.7 wt%, and the content of the structural unit C is 33.3 wt%.

[0161] Comparative Example 2

[0162] 8.3 g of 2-acrylamido-2-methylpropanesulfonic acid, 0.54 g of N-vinylpyrrolidone, and 0.16 g of allyltrimethylammonium chloride were mixed and dissolved in 41 g of deionized water. Nitrogen was then introduced, and the pH of the system was adjusted to 6 with a NaOH solution. 0.04 g of initiator composition A (ammonium persulfate and sodium bisulfite) was added, and the mixture was reacted at 10°C for 7 hours. The mixture was cooled to room temperature, precipitated with acetone, filtered, dried, and pulverized to obtain a polymer. The polymer test results are shown in Table 1.

[0163] Structural unit A( Among them, R1 is R4 is H); structural unit B ( and combination, wherein R5 is H and X is chloride ion);

[0164] Based on the total mass of the polymer, the content of the structural unit A is 92.2 wt%, and the content of the structural unit B is 7.8 wt% (Formula (2-1) is 6 wt%, Formula (2-2) is 1.8 wt%, and the weight ratio is 3.3:1).

[0165] Comparative Example 3

[0166] 0.18g of N-vinylpyrrolidone, 0.09g of allyltrimethylammonium chloride, 2.7g of 2-acrylamido-2-methylpropanesulfonic acid, and 6.03g of maleic acid-β-cyclodextrin ester were mixed and dissolved in 40g of deionized water. Nitrogen was then introduced, and the pH of the system was adjusted to 6 with NaOH solution. 0.04g of initiator composition A (ammonium persulfate and sodium bisulfite) was added, and the reaction was carried out at 10°C for 7 hours. The system was cooled to room temperature, precipitated with acetone, filtered, dried, and pulverized to obtain a polymer. The polymer test results are shown in Table 1.

[0167] The prepared polymer comprises:

[0168] Structural unit A( Among them, R1 is R4 is H); structural unit B ( and wherein R5 is H and X is a chloride ion); structural unit C( Wherein, Z is the residue after dehydroxylation of β-cyclodextrin);

[0169] Based on the total mass of the polymer, the content of the structural unit A is 30wt%, the content of the structural unit B is 3wt% (formula (2-1) is 2wt%, formula (2-2) is 1wt%, and the weight ratio is 2:1), and the content of the structural unit C is 67wt%.

[0170] Table 1

[0171] Test Example 1

[0172] The salt resistance of the polymers of the Examples and Comparative Examples was evaluated. The results are shown in Table 2.

[0173] Table 2

[0174] Test Example 2

[0175] The heat resistance of the polymers of the examples and comparative examples was evaluated, and the results are shown in Table 3.

[0176] Table 3

[0177] Test Example 3

[0178] The anti-adsorption properties of the polymers of Examples and Comparative Examples were evaluated, and the results are shown in Table 4.

[0179] Table 4

[0180] The results show that the polymer of the present invention comprises structural unit A represented by formula (1), structural unit B represented by formula (2), and structural unit C represented by formula (3). The resulting polymer has the following characteristics: (1) heat resistance, with a viscosity retention rate of ≥90% at 85°C; (2) excellent salt tolerance, with a viscosity retention rate of ≥80% at a salinity of 100,000 mg / L; and (3) excellent anti-adsorption performance, with a static adsorption viscosity retention rate of ≥85%. Furthermore, when structural unit B of the present invention comprises the specific structure represented by formula (2-1) and the structure represented by formula (2-2), a synergistic effect can be generated, further improving the heat resistance, salt resistance, and anti-adsorption properties of the polymer.

[0181] Test Example 4

[0182] The polymers of the examples and comparative examples were respectively prepared with clean water to obtain a polymer aqueous solution with a mass concentration of 0.01 wt%. 0.1 parts by weight of sodium dodecyl sulfate was added to 100 parts by weight of clean water to prepare a displacement agent. The oil removal rates were tested, and the results are shown in Table 5.

[0183] Test Example 5

[0184] The polymers of the examples and comparative examples were mixed with water to prepare 2.5 wt% aqueous solutions, i.e., oil stain detergents. The oil stain cleaning rates were tested, and the test results are shown in Figure 5.

[0185] Table 5

[0186] As can be seen from Table 5, compared with the comparative example, the oil-displacement agent made from the polymer of the present invention has a superior oil-displacement effect, with a static oil removal rate of ≥90 vol%. Furthermore, when the preferred embodiment is adopted, the oil-displacement effect of the oil-displacement agent of the present invention is even better. The oil-displacement detergent made from the polymer of the present invention has surfactant properties due to the introduction of a cyclodextrin structure that is hydrophilic on the inside and hydrophobic on the outside. Therefore, it can exert a cleaning effect without phase separation, and the oil-displacement cleaning rate reaches over 80%. When using the preferred embodiment of the present invention, the oil-displacement detergent has even stronger cleaning performance.

[0187] 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 polymer, characterized in that The polymer comprises at least one structural unit A represented by formula (1), at least one structural unit B represented by formula (2) and at least one structural unit C represented by formula (3), wherein: Where R1 is H, C1-C 18 Alkyl, -R2-SO3H, -R3-COOH or Wherein, R2 is a C3-C4 straight chain or branched alkyl group, R3 is a C4-C8 straight chain or branched alkyl group, n is an integer of 0-2, R4 is H or a C1-C4 straight chain alkyl group, and R5 is H or methyl; Y is selected from the structure shown in Formula I, the structure shown in Formula II, the structure shown in Formula III or the structure shown in Formula IV, wherein a is an integer of 0-22, b is 2, c is 1, d is 2 or 3, R6 is -COO- or -CO-NH-, and X is each independently a halogen; Z is the residue after dehydroxylation of cyclodextrin; Based on the total weight of the polymer, the content of the structural unit A is 40-65wt%, the content of the structural unit B is 5-30wt%, and the content of the structural unit C is 15-40wt%.

2. The polymer according to claim 1, wherein R1 is H, C3-C 12 Alkyl, -R2-SO3H, -R3-COOH or Wherein, R2 is isobutyl; R3 is isobutyl, n is 0 or 1, R4 is H or C1-C2 alkyl, and R5 is H; Preferably, a is an integer of 0-18, b is 2, c is 1, d is 2 or 3, R6 is -COO- or -CO-NH-, and X is a chloride ion; Preferably, the cyclodextrin is at least one selected from α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, 2-hydroxypropyl-β-cyclodextrin and 2-hydroxypropyl-γ-cyclodextrin.

3. The polymer according to claim 1 or 2, wherein Based on the total weight of the polymer, the content of the structural unit A is 45-63wt%, the content of the structural unit B is 7-29wt%, and the content of the structural unit C is 18-35wt%.

4. The polymer according to any one of claims 1 to 3, wherein The structural unit B includes the structure shown in formula (2-1) and the structure shown in formula (2-2); Preferably, in the structural unit B, the weight ratio of the structure represented by the formula (2-1) to the structure represented by the formula (2-2) is 1-4:

1.

5. The polymer according to any one of claims 1 to 4, wherein The viscosity-average relative molecular weight of the polymer is 1,000,000-8,000,000 g / mol, preferably 1,000,000-6,000,000 g / mol.

6. A method for preparing a polymer, characterized in that: The method comprises: mixing at least one monomer A represented by formula (4), at least one monomer B represented by formula (5) and at least one monomer C represented by formula (6) with water to obtain a monomer mixed solution, adjusting the pH value of the monomer mixed solution, adding an initiator, performing a polymerization reaction under a nitrogen atmosphere, and obtaining a polymer through post-treatment; Wherein, R1' is H, C1-C 18 Alkyl, -R2'-SO3H, -R3'-COOH or wherein R2' is a C3-C4 straight chain or branched alkyl group, R3' is a C4-C8 straight chain or branched alkyl group, n' is an integer of 0-2, R4' is H or a C1-C4 straight chain alkyl group, and R5' is H or methyl; Y' is selected from the structure shown in formula I', the structure shown in formula II', the structure shown in formula III' or the structure shown in formula IV', wherein a' is an integer of 0-22, b' is 2, c' is 1, d' is 2 or 3, R6' is -COO- or -CO-NH-, and X' is each independently a halogen; Z' is the residue after dehydroxylation of cyclodextrin; Wherein, based on the total weight of the monomer A, the monomer B and the monomer C, the amount of the monomer A is 40-65wt%, the amount of the monomer B is 5-30wt%, and the amount of the monomer C is 15-40wt%.

7. The preparation method according to claim 6, wherein: R1' is H, C3-C 12 Alkyl, -R2'-SO3H, -R3'-COOH or Wherein, R2' is isobutyl; R3' is isobutyl, n' is 0 or 1, R4' is H or C1-C2 alkyl, and R5' is H; Preferably, a' is an integer of 0-18, b' is 2, c' is 1, d' is 2 or 3, R6' is -COO- or -CO-NH-, and X' is a chloride ion; Preferably, the cyclodextrin is at least one selected from α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, 2-hydroxypropyl-β-cyclodextrin and 2-hydroxypropyl-γ-cyclodextrin.

8. The preparation method according to claim 6 or 7, wherein: Based on the total weight of the monomer A, the monomer B and the monomer C, the amount of the monomer A is 45-63wt%, the amount of the monomer B is 7-29wt%, and the amount of the monomer C is 18-35wt%.

9. The preparation method according to any one of claims 6 to 8, wherein: The monomer B includes the structure shown in formula (5-1) and the structure shown in formula (5-2); Preferably, relative to the total amount of monomer B used, the amount ratio of monomer B having the structure represented by formula (5-1) to monomer B having the structure represented by formula (5-2) is 1-4:

1.

10. The preparation method according to any one of claims 6 to 9, wherein: The initiator is selected from at least one of sodium bisulfite, sodium thiosulfate, sodium pyrosulfite, potassium persulfate, sodium persulfate, hydrogen peroxide, 2,2'-azo[2-(2-imidazolin-2-yl)propane] dihydrochloride, azobis(2,5-dimethyl-6-carboxyl)hexanenitrile and 4,4'-azobis(4-cyanovaleric acid), preferably an initiator composition of potassium persulfate and sodium bisulfite, or an initiator composition of ammonium persulfate and sodium bisulfite; Preferably, based on the total weight of the monomer A, the monomer B and the monomer C, the added amount of the initiator is 0.1-0.6 wt %, preferably 0.3-0.6 wt %.

11. The preparation method according to any one of claims 6 to 10, wherein: Adjust the pH value of the monomer mixed solution to 6-8; Preferably, the polymerization reaction temperature is 5-50°C, preferably 10-40°C; the polymerization reaction time is 6-9h, preferably 7-8h.

12. A polymer obtained by the preparation method according to any one of claims 6 to 11; Preferably, the viscosity-average relative molecular weight of the polymer is 1,000,000-8,000,000 g / mol, preferably 1,000,000-6,000,000 g / mol.

13. Use of the polymer according to any one of claims 1 to 5 and 12 as a displacement agent.

14. Use of the polymer according to any one of claims 1 to 5 and 12 as an oily dirt detergent.

15. A displacement agent, characterized in that: The displacement agent comprises the polymer according to any one of claims 1 to 5 and 12 and water; Preferably, relative to 100 parts by weight of water, the polymer is 0.1-5 parts by weight, preferably 0.1-2.5 parts by weight; Preferably, the displacement agent further comprises a surfactant.

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