Bisulfonate hydrophobic association polymer oil-displacing agent with cyclic structure and preparation method of bisulfonate hydrophobic association polymer oil-displacing agent

Abstract

The invention relates to a bisulfonate hydrophobic associated polymer oil-displacing agent with a cyclic structure and a preparation method thereof. The oil-displacing agent is formed by copolymerization of four monomers, namely acrylamide, sodium 2-allyl methylamino ethanesulfonate, diallyl disulfoethyl betaine and long-chain alkyl dimethyl (p-3-carboxyl acrylamide benzyl) ammonium chloride which is a hydrophobic monomer with a benzene ring structure. The preparation method comprises the following steps: firstly, adding distilled water, then sequentially adding acrylamide, 2-allyl methylamino sodium ethanesulfonate, diallyl disulfoethyl betaine and a hydrophobic monomer long-chain alkyl dimethyl (p-3-carboxyl acrylamide benzyl) ammonium chloride with a benzene ring structure, supplementing water, adjusting the total concentration, introducing N2 to remove oxygen, adding an initiator, and stirring to obtain the water-absorbent polymer. And reacting at a certain temperature to obtain the quadripolymer. The prepared oil-displacing agent has good water solubility, temperature resistance and shearing resistance, shows good salt resistance in saline water with the mineralization degree larger than or equal to 30000 mg / L, shows a good oil-displacing effect in heterogeneous rock cores, and can improve the crude oil recovery rate by 10% or above.

Description

Technical Field

[0001] The present invention relates to an oil recovery auxiliary agent, in particular to a hydrophobically associating polymer oil-displacing agent containing a cyclic sulfonate structure and a benzene ring hydrophobic group, specifically a hydrophobically associating polymer oil-displacing agent having a cyclic structure of a disulfonate. The present invention also relates to a preparation method of the hydrophobically associating polymer oil-displacing agent having a cyclic structure of a disulfonate. Background Art

[0002] After primary and secondary oil recovery, about 60% of the oil cannot be recovered. How to recover more oil from the bottom is a topic of joint research by domestic scholars and experts. Polymer flooding is an important technology for improving oil recovery. Since the 1990s, it has been widely used in oil fields and other fields and has achieved significant water reduction and oil increase effects, playing an important role in stabilizing the production of old oil fields. The partially hydrolyzed polyacrylamide (HPAM) currently used mainly has poor salt resistance, high temperature hydrolysis resistance and shear resistance, making it unsuitable for Class II and Class III high temperature and high salt reservoirs (Zhu Rui. Synthesis and properties of heat-resistant and salt-resistant hydrophobic associating polymer AM / AMPS / OA [D]. 2015). In order to improve the heat and salt resistance of polymers and meet the conditions of high temperature and high salt reservoirs, domestic and foreign scholars have developed many heat and salt resistant polymers in recent years, among which hydrophobic associating polymers are one of the products. Hydrophobically associating water-soluble polymers are water-soluble polymers formed by introducing a very small amount of hydrophobic groups into the hydrophilic main chain of the polymer. Hydrophobically associating polymers show good viscosity enhancement, temperature resistance, salt resistance and shear resistance, making them a water-soluble polymer material with good application prospects (Chen Hong, Li Erxiao, Ye Zhongbin, et al. Interaction between hydrophobically associating polyacrylamide and gemini surfactants [J]. Acta Physico-Chimica Sinica, 2011, 27(3): 671-676). At present, hydrophobically associating polymers have been used in some Class II and Class III reservoirs to a certain extent and have achieved good results.

[0003] Related patent literature: CN105601804A discloses a hydrophobic associating polymer, comprising the following four repeating units; A is a monomer unit of a hydrophobic monomer; the hydrophobic monomer is selected from one or more of N-alkyl substituted acrylamide and its derivatives, alkyl acrylate, alkyl methacrylate, fluorine-substituted alkyl acrylate, allyl alkyl quaternary ammonium salt, acrylamide alkyl sulfonic acid and acrylamide alkyl sulfonate; D is a monomer unit of a functional monomer; the functional monomer is selected from one or more of sulfonic acid derivatives containing terminal alkenyl groups and their sulfonate derivatives and heterocyclic derivatives containing terminal alkenyl groups. Compared with the prior art, the monomer unit of the hydrophobic associating polymer acrylamide in this technology can provide a hydrophilic group; the monomer unit of the hydrophobic monomer can provide a hydrophobic side group to construct a solution network structure; the monomer unit of the acrylic acid ion can improve the solubility of the polymer; the introduction of the monomer unit of the functional monomer can improve the temperature and salt resistance of the polymer. CN103059217A discloses a temperature-resistant and salt-resistant hydrophobic associating polymer oil displacement agent and a preparation method. The preparation scheme is as follows: the mass is in grams, the monomer mass percentage is 57.0-59.8% acrylamide AM, 39.3-40.0% sodium acrylate NaAA, 0.1-0.2% N-allylphenylacetamide NAPA, and 0.1-3.5% N,N-dimethyl-N-allyl hexadecyl ammonium chloride AHAC; the preparation method is to add NAPA, AHAC and an emulsifier into a reactor, add water to emulsify completely; then add NaAA and AM, adjust the pH to 7, add an initiator, and after the reaction, wash, crush, and dry to obtain a polymer product. The polymer has water solubility, high viscosity increasing ability, and heat resistance and shear resistance. The viscosity retention rate of a 0.1wt% solution at 100°C reaches 91.3%, and it can increase the recovery rate of simulated crude oil by 16.6%. CN105199043A discloses a water-soluble hydrophobic associating polymer and a preparation method thereof. The raw material formula of the polymer is as follows: by mass percentage, 16% to 26% acrylamide, 0.08% to 0.1% hydrophobic monomer, 2.6% to 9% hydrophilic monomer, 0.03% to 0.08% persulfate, 3% to 5% sodium dodecyl sulfate, 0.002% to 0.004% defoamer, and 60% to 81.3% deionized water. The water-soluble hydrophobic associating polymer of the invention has better heat resistance, salt resistance and shear resistance than the existing polyacrylamide, and can be used as an tertiary oil recovery oil displacement agent. CN104152130A discloses a water-soluble EOR agent containing an imidazoline structure hydrophobic associating polymer oil displacement agent AM / NaAA / NIDA and a synthesis method thereof.Its technical scheme is as follows: a certain amount of NIDA, OP-10 and deionized water are put into a flask, after being fully stirred and emulsified, AM and AA are added to prepare an aqueous solution with a monomer concentration of 10-20wt%, the pH is adjusted, N2 is passed for 20min and the temperature is raised to 40°C; an initiator (ammonium persulfate and sodium bisulfite have a molar ratio of 1:1) is added, the amount of initiator added is 0.8wt% of the total weight of the monomer, N2 is continued to be passed and the reaction is carried out at a constant temperature (40°C) for 8-12h; it is washed with ethanol, crushed and dried to obtain a white polymer powder. The polymer has good heat resistance, shear resistance and salt resistance, and improves the recovery rate by 13.52% in an indoor simulated core displacement experiment. CN106986965A discloses a hydrophobic associating polymer for oilfield fracturing fluid and improving recovery rate and a preparation method thereof. The preparation method comprises: (1) dissolving 0.2 mol of dibromoethane in acetone, adding 0.1 mol of dimethylaminoethyl methacrylate to the acetone solution under stirring conditions, reacting at room temperature for 4 hours to obtain N,N-dimethylbromoethyl methacryloyloxyethyl ammonium bromide intermediate; (2) adding 0.05 mol of the intermediate and 0.055 mol of erucic acid amide propyl dimethyl tertiary amine to ethanol, reacting at room temperature for 24 hours to obtain a polymerizable hydrophobic monomer; (3) adding the hydrophobic monomer and acrylamide to deionized water, passing nitrogen for half an hour, heating to 45-60°C and adding an initiator, and polymerizing for 6-8 hours to obtain a hydrophobic associative polymer. The associative polymer has good viscosity increasing ability and is simple to prepare, and has good application prospects in oilfield fracturing fluid and enhanced oil recovery.

[0004] The hydrophobic associating polymer synthesized by the above technology has certain temperature and salt resistance, and has good viscosity increasing ability below the mineralization degree of 30000 mg / L, but its salt resistance is poor when the mineralization degree is ≥30000 mg / L. Summary of the invention

[0005] The purpose of the present invention is to provide a hydrophobically associating polymer oil-displacing agent having a cyclic structure and a disulfonate salt, which has good performance, good viscosity increasing ability at high temperature and high salinity, and good shear resistance, can achieve a higher recovery rate, and can meet the technical requirements of a polymer oil-displacing agent with a wide range of uses on the market, thereby ensuring the smooth progress of oil production in high-temperature and high-salinity oil fields, and solving the problems that the existing hydrophobically associating polymer has poor temperature and salt resistance in brine with high salinity (mineralization ≥30000 mg / L), is easily hydrolyzed underground, and has a low crude oil recovery rate.

[0006] To this end, another object of the present invention is to provide a method for preparing a hydrophobically associating polymer oil-displacing agent of a disulfonate salt having a cyclic structure.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0008] A hydrophobic associating polymer oil displacement agent with a cyclic structure of disulfonate, the technical scheme of which is that it is composed of acrylamide AM, 2-allylmethylaminoethylsulfonate sodium AMES-Na, diallyldisulfoethyl betaine DADSBA and a hydrophobic monomer with a benzene ring structure, long-chain alkyl dimethyl (p-3-carboxyacrylamide benzyl) ammonium chloride C n DMCABAC is copolymerized by four monomers, and the structural formula of the polymer oil displacement agent is as follows:

[0009]

[0010] In the above structural formula, x, y, z, and p are the molar percentage ranges of the structural units: x=72% to 83.8%, y=15% to 25%, z=1% to 2%, p=0.2% to 1%, and x+y+z+p=100%. Among them, n=12, 14, 16, or 18.

[0011] In the cyclic disulfonate hydrophobically associated polymer oil-displacing agent, the molar fractions of the monomers are as follows (i.e., the oil-displacing agent is made of the following molar fractions of monomers): 72-83.8 parts of acrylamide AM, 15-25 parts of 2-allylmethylaminoethylsulfonate AMES-Na, 1-2 parts of diallyldisulfoethyl betaine DADSBA, and long-chain alkyl dimethyl (p-3-carboxyacrylamidobenzyl) ammonium chloride C with a benzene ring structure hydrophobic monomer. n DMCABAC 0.2~1.0 parts.

[0012] The preparation method of the above-mentioned 2-allylmethylaminoethanesulfonic acid sodium AMES-Na comprises the following process steps: in a (500mL) three-necked flask equipped with a thermometer, a reflux condenser with a Soxhlet extractor and a magnetic rotor, adding an appropriate amount of anhydrous ethanol as a solvent, adding 65-95g of 2-chloroethylsulfonic acid sodium at room temperature (temperature is 23-25°C), then slowly adding 30-43g of N-methylallylamine under stirring, adding 0.15-0.21g of inhibitor methylhydroquinone, and charging 32-47g of an acid binding agent wrapped with filter paper into the Soxhlet extractor, raising the temperature to reflux, reacting at a constant temperature for 20-25 hours, and removing the solvent and excess N-methylallylamine by reduced pressure distillation using a rotary evaporator to obtain 2-allylmethylaminoethanesulfonic acid sodium AMES-Na.

[0013] The preparation method of the salt-resistant monomer diallyl disulfoethyl betaine DADSBA comprises the following process steps: in a (500 mL) three-necked flask equipped with a thermometer, a reflux condenser with a Soxhlet extractor and a magnetic rotor, adding an appropriate amount of anhydrous ethanol as a solvent, adding 25 to 35 g of diallylamine at room temperature (temperature is 23 to 25° C.), then slowly adding 100 to 130 g of 2-chloroethyl sodium sulfonate under stirring, adding 0.17 to 0.25 g of methyl hydroquinone as an inhibitor, loading (using) 23 to 33 g of an acid binding agent wrapped with filter paper into the Soxhlet extractor, raising the temperature to reflux, reacting at a constant temperature for 20 to 25 hours, removing the solvent by reduced pressure distillation using a rotary evaporator, and recrystallizing using anhydrous ethanol to obtain the salt-resistant monomer diallyl disulfoethyl betaine DADSBA.

[0014] The above hydrophobic monomer with benzene ring structure long chain alkyl dimethyl (p-3-carboxy acrylamide benzyl) ammonium chloride C n The preparation method of DMCABAC comprises the following process steps: (1) adding an appropriate amount of anhydrous ethanol as a solvent to a three-necked flask (500 mL) equipped with a thermometer, a reflux condenser and a magnetic rotor, adding 80 to 120 g of a long-chain alkyl dimethyl tertiary amine at room temperature (temperature of 23 to 25° C.), then slowly adding 40 to 60 g of p-aminobenzyl chloride under stirring, raising the temperature to reflux, reacting at constant temperature for 10 to 15 hours, removing the solvent by reduced pressure distillation using a rotary evaporator, and then recrystallizing using acetone to obtain a long-chain alkyl dimethyl (4-aminobenzyl) ammonium chloride; (2) adding 100 g of anhydrous ethanol as a solvent to a three-necked flask (500 mL) equipped with a thermometer, a reflux condenser and a magnetic rotor, and then slowly adding 100 g of anhydrous ethanol as a solvent to a three-necked flask (500 mL) equipped with a thermometer, a reflux condenser and a magnetic rotor. A (500 mL) three-necked flask is added with an appropriate amount of anhydrous ethanol as a solvent, 60 to 100 g of long-chain alkyl dimethyl (4-aminobenzyl) ammonium chloride is added at room temperature (temperature is 23 to 25° C.), and then 16 to 27 g of maleic anhydride is slowly added under stirring, and the temperature is raised to 60 to 70° C., and the reaction is carried out at a constant temperature for 6 to 8 hours to obtain a reaction solution, and the pH value of the reaction solution is adjusted to neutral using a pH regulator, and then the solvent is removed by reduced pressure distillation using a rotary evaporator, and then separated and purified using anhydrous ethanol to obtain a hydrophobic monomer long-chain alkyl dimethyl (p-3-carboxyacrylamide benzyl) ammonium chloride C with a benzene ring structure. n DMCABAC.

[0015] The preparation method of the cyclic disulfonate hydrophobically associated polymer oil-displacing agent comprises the following process steps: firstly, 1000-1500 mole parts of distilled water are added into a reactor, and then 72-83.8 mole parts of acrylamide AM, 15-25 parts of 2-allylmethylaminoethylsulfonate AMES-Na, 1-2 mole parts of diallyl disulfoethyl betaine DADSBA, long-chain alkyl dimethyl (p-3-carboxyacrylamide benzyl) ammonium chloride C are added in sequence under stirring. n DMCABAC 0.2-1 molar part, and then distilled water is added to control the total mass percentage concentration of the reaction monomers to be between 15% and 30% (the total mass percentage concentration of the reaction monomers is the mass percentage concentration of the above four monomers combined, the same below), and after stirring evenly (stirring the solution until the solution is a nearly transparent homogeneous system), N2 is passed for 30-35 minutes; then an initiator is added, and N2 is continued to be passed, and the reaction is carried out for 4-10 hours under nitrogen protection at 30-60°C; after the reaction, the obtained gel product is washed with anhydrous ethanol, and the product is crushed and dried to obtain AM / AMES / DADSBA / C n The DMCABAC tetrapolymer is a disulfonate hydrophobically associating polymer oil displacement agent having a cyclic structure.

[0016] In the above technical scheme, the preferred technical scheme may be that the amount of the initiator added is 0.05% to 0.2% of the total mass of the four reaction monomers (i.e., the four monomers); the above initiator may be a composite initiator, including an oxidation-reduction system initiator and a water-soluble azo initiator; in the oxidation-reduction system initiator, the oxidant is potassium persulfate or ammonium persulfate, the reductant is sodium bisulfite, and the molar ratio of the oxidant to the reductant is 1:1 to 1.5; the water-soluble azo initiator is one or more of azobisisobutylamidine hydrochloride V-50, azobisisobutylimidazoline hydrochloride VA-044, and azobis(N-2-carboxyethyl-2-methylpropionamidine) hydrate VA-057, and the ratio thereof is arbitrary when combined; in the composite initiator, the mass ratio of the oxidation-reduction system initiator to the water-soluble azo initiator is 1:1 to 2.

[0017] In the above technical solution, the preferred technical solution can also be that the pH value adjuster can be a sodium hydroxide aqueous solution with a mass percentage concentration of 20%. The above hydrophobic monomer with a benzene ring structure, long-chain alkyl dimethyl (p-3-carboxyacrylamide benzyl) ammonium chloride C n In DMCABAC, the long-chain alkyl group may be hexadecyl, in step (1), the long-chain alkyl dimethyl tertiary amine is hexadecyl dimethyl tertiary amine, and in step (2), the final product is hexadecyl dimethyl (p-3-carboxyacrylamidobenzyl) ammonium chloride C with a benzene ring structure.16 DMCABAC, see Example 1.

[0018] In the above technical solution, the preferred technical solution can also be that the hydrophobic monomer with a benzene ring structure, long-chain alkyl dimethyl (p-3-carboxyacrylamide benzyl) ammonium chloride C n In DMCABAC, the long-chain alkyl group can be octadecyl, in step (1), the long-chain alkyl dimethyl tertiary amine is octadecyl dimethyl tertiary amine, and in step (2), the final product is octadecyl dimethyl (p-3-carboxyacrylamidobenzyl) ammonium chloride C with a benzene ring structure. 18 DMCABAC, see Example 2. The acid binding agent may be potassium carbonate or sodium carbonate.

[0019] Among the above technical solutions, a preferred technical solution may also be Embodiment 1 of the present invention.

[0020] The polymer oil displacement agent of the present invention is composed of acrylamide AM, 2-allylmethylaminoethylsulfonate sodium AMES-Na, diallyldisulfoethyl betaine DADSBA and a long-chain alkyl dimethyl (p-3-carboxyacrylamide benzyl) ammonium chloride C with a benzene ring structure hydrophobic monomer. n DMCABAC is copolymerized by four monomers. Preparation method: Add distilled water into the reactor, and then add acrylamide AM, 2-allylmethylaminoethylsulfonate AMES-Na, diallyl disulfoethyl betaine DADSBA and long-chain alkyl dimethyl (p-3-carboxyacrylamide benzyl) ammonium chloride C with a benzene ring structure hydrophobic monomer. n DMCABAC, then add distilled water, stir evenly, pass N2 to deoxygenate, add initiator, react at a certain temperature to obtain AM / AMES / DADSBA / C n The DMCABAC tetrapolymer is the polymer oil-displacing agent. The present invention introduces a hydrophobic chain and a benzene ring structure into the polymer chain to improve the viscosity-increasing ability and temperature resistance of the polymer, and increases the rigidity of the molecular chain by introducing a ring structure, thereby improving the thermal stability and shear resistance of the polymer. Sulfonic acid groups are introduced into the molecular chain to improve the water solubility and salt resistance of the polymer, meeting the actual construction needs of the injection water with a mineralization of ≥30000mg / L on site. The polymer oil-displacing agent prepared by the present invention has good water solubility, shows good temperature and salt resistance in salt water with a mineralization of ≥30000mg / L, and the oil displacement experiment shows a good oil displacement effect, which can increase the crude oil recovery rate by more than 10%.

[0021] Compared with the prior art, the present invention has the following effects: (1) benzene rings are introduced into the hydrophobic monomer, so that the rigidity of the polymer molecular chain is greatly enhanced and the hydrophobic association between copolymer molecules is increased, thereby greatly increasing the viscosity and rheological properties of the polymer and significantly improving the heat resistance of the polymer; (2) diallyl and sulfonic acid groups are introduced to form a ring structure after reaction, thereby improving the water solubility, salt resistance and shear resistance of the polymer; (3) the polymer exhibits good heat resistance, salt resistance and shear thinning resistance, and can effectively improve the oil recovery rate.

[0022] Referring to the experimental (test) part of the present invention below, in summary, the present invention provides a (water-soluble) hydrophobically associating polymer oil-displacing agent having a cyclic structure and a disulfonate salt, which has good performance, good viscosity increasing ability at high temperature and high salinity, and good shear resistance, can achieve a high recovery rate, and meets the technical requirements of polymer oil-displacing agents with a wide range of uses on the market, thereby ensuring the smooth progress of oil production in high-temperature and high-salinity oil fields, and solving the problems of poor temperature and salt resistance of existing hydrophobically associating polymers in brine with high salinity (mineralization ≥ 30000 mg / L), easy hydrolysis underground, and low crude oil recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the infrared spectrum of the copolymer (oil-displacing agent) synthesized (prepared) in Example 1 of the present invention.

[0024] Figure 2 Graph showing the relationship between the apparent viscosity of the copolymer (oil displacing agent) synthesized in Example 1 of the present invention and the change in concentration.

[0025] Figure 3 Graph showing the relationship between the apparent viscosity of the copolymer (oil displacing agent) synthesized in Example 1 of the present invention and the change in temperature.

[0026] Figure 4 The figure is a relationship diagram of the apparent viscosity of the copolymer (oil displacement agent) synthesized in Example 1 of the present invention as a function of the salinity.

[0027] Figure 5 Graph showing the relationship between the apparent viscosity of the copolymer (oil displacing agent) synthesized in Example 1 of the present invention and the shear rate.

[0028] Figure 6 This is a diagram of the oil displacement efficiency of the copolymer (oil displacement agent) synthesized in Example 1 of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described in conjunction with the embodiments below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on this embodiment, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of the present invention.

[0030] Example 1: The (water-soluble) hydrophobically associating polymer oil-displacing agent with a cyclic structure of disulfonate described in the present invention is prepared from the following monomers in molar fractions (copolymerized from four monomers): 78.87 parts of acrylamide AM, 19.37 parts of 2-allylmethylaminoethylsulfonate AMES-Na, 1.35 parts of diallyldisulfoethyl betaine DADSBA, and a long-chain alkyl dimethyl (p-3-carboxyacrylamidobenzyl) ammonium chloride C with a benzene ring structure hydrophobic monomer. n DMCABAC 0.41 parts. The structural formula of the polymer oil displacement agent is as follows:

[0031]

[0032] In the above structural formula, x, y, z, and p are the molar percentage ranges of the structural units: x=78.87%, y=19.37%, z=1.35%, p=0.41%, x+y+z+p=100%, wherein n=12, 14, 16, 18. In this embodiment, n=14.

[0033] The above hydrophobic monomer with benzene ring structure long chain alkyl dimethyl (p-3-carboxy acrylamide benzyl) ammonium chloride C n In DMCABAC, the long-chain alkyl group is hexadecyl, in the following step (1), the long-chain alkyl dimethyl tertiary amine is hexadecyl dimethyl tertiary amine, and in the following step (2), the final product is hexadecyl dimethyl (p-3-carboxyacrylamidobenzyl) ammonium chloride C with a benzene ring structure hydrophobic monomer 16 DMCABAC.

[0034] The preparation method of the above-mentioned 2-allylmethylaminoethanesulfonic acid sodium AMES-Na comprises the following process steps: in a 500mL three-necked flask equipped with a thermometer, a reflux condenser with a Soxhlet extractor and a magnetic rotor, 180mL of anhydrous ethanol is added as a solvent, 75g of sodium 2-chloroethylsulfonate is added at a temperature of 25°C, and then 34g of N-methylallylamine is slowly added under stirring, 0.17g of methylhydroquinone as an inhibitor is added, 37g of potassium carbonate (acid binding agent) wrapped with filter paper is loaded into the Soxhlet extractor, the temperature is raised to reflux, and after isothermal reaction for 23 hours, the solvent and excess N-methylallylamine are removed by reduced pressure distillation using a rotary evaporator to obtain 2-allylmethylaminoethanesulfonic acid sodium AMES-Na.

[0035] The preparation method of the salt-resistant monomer diallyl disulfoethyl betaine DADSBA comprises the following process steps: adding 200 mL of anhydrous ethanol as a solvent to a 500 mL three-necked flask equipped with a thermometer, a reflux condenser with a Soxhlet extractor and a magnetic rotor, adding 30 g of diallylamine at a temperature of 25° C., then slowly adding 110 g of sodium 2-chloroethyl sulfonate under stirring, adding 0.18 g of methyl hydroquinone as an inhibitor, and loading 27 g of potassium carbonate (acid binding agent) wrapped with filter paper into the Soxhlet extractor, raising the temperature to reflux, reacting at a constant temperature for 23 hours, removing the solvent by reduced pressure distillation using a rotary evaporator, and recrystallizing using anhydrous ethanol to obtain the salt-resistant monomer diallyl disulfoethyl betaine DADSBA.

[0036] The above hydrophobic monomer with a benzene ring structure hexadecyl dimethyl (p-3-carboxyacrylamide benzyl) ammonium chloride C 16 The preparation method of DMCABAC comprises the following process steps: (1) adding 200 mL of anhydrous ethanol as a solvent to a 500 mL three-necked flask equipped with a thermometer, a reflux condenser and a magnetic rotor, adding 94 g of hexadecyldimethyl tertiary amine at a temperature of 25° C., and then slowly adding 47 g of p-aminobenzyl chloride under stirring, raising the temperature to reflux, and reacting at a constant temperature for 13 hours, removing the solvent by reduced pressure distillation using a rotary evaporator, and then recrystallizing using acetone to obtain hexadecyldimethyl (4-aminobenzyl) ammonium chloride. (2) In a 500 mL three-necked flask equipped with a thermometer, a reflux condenser and a magnetic rotor, 180 mL of anhydrous ethanol was added as a solvent, 80 g of hexadecyldimethyl (4-aminobenzyl) ammonium chloride was added at a temperature of 25° C., and then 23 g of maleic anhydride was slowly added under stirring, the temperature was raised to 65° C., and the reaction was carried out at a constant temperature for 8 hours to obtain a reaction solution, and the pH value of the reaction solution was adjusted to neutral using a pH adjuster, and the pH adjuster was a sodium hydroxide aqueous solution with a mass percentage concentration of 20%; then the solvent was removed by reduced pressure distillation using a rotary evaporator, and then separated and purified using anhydrous ethanol to obtain a hydrophobic monomer hexadecyldimethyl (p-3-carboxyacrylamide benzyl) ammonium chloride C with a benzene ring structure. 16 DMCABAC.

[0037] The preparation method of the hydrophobically associated polymer oil displacement agent with a cyclic structure of disulfonate (i.e. AM / AMES / DADSBA / C 16The synthesis process of DMCABAC hydrophobic associating polymer oil displacement agent comprises the following process steps: firstly, 1000 mole parts of distilled water are added into a reactor, and 78.87 mole parts of acrylamide AM, 19.37 mole parts of 2-allylmethylaminoethylsulfonic acid sodium AMES-Na, 1.35 mole parts of diallyl disulfoethyl betaine DADSBA and hexadecyl dimethyl (p-3-carboxyacrylamidobenzyl) ammonium chloride C with a benzene ring structure are added in sequence under stirring. 16 DMCABAC 0.41 molar part, and then distilled water was added to control the total mass percentage concentration of the reaction monomers to 25%, and after stirring evenly, N2 was passed for 30 minutes; then 0.1% of the total mass of the four reaction monomers was added initiator, and N2 was continued to be passed, and the reaction was carried out under nitrogen protection at 50°C for 7 hours; after the reaction, the obtained gel product was washed with anhydrous ethanol, and the product was crushed and dried to obtain AM / AMES / DADSBA / C 16 The DMCABAC tetrapolymer is a disulfonate hydrophobically associating polymer oil displacement agent with a cyclic structure.

[0038] The above-mentioned initiator is a composite initiator, including an oxidation-reduction system initiator and a water-soluble azo initiator. In the above-mentioned oxidation-reduction system initiator, the oxidant is potassium persulfate, the reductant is sodium bisulfite, and the molar ratio of the oxidant to the reductant is 1:1. The above-mentioned water-soluble azo initiator is a combination of azobisisobutylimidazoline hydrochloride (VA-044) and azobis(N-2-carboxyethyl-2-methylpropionamidine) hydrate (VA-057), and the mass ratio of VA-044 to VA-057 is 1:1.2. In the composite initiator, the mass ratio of the oxidation-reduction system initiator to the water-soluble azo initiator is 1:1.5.

[0039] Preparation Comparative Example: For the convenience of presentation in the experimental part of the present invention, AM / AMES / DADSBA / C 16 The DMCABAC tetrapolymer is abbreviated as PAADC (ie, the polymer oil displacement agent of the present invention). Under the same conditions, acrylamide AM and acrylic acid AA are used to synthesize partially hydrolyzed polyacrylamide HPAM (comparative example).

[0040] Example 2: The hydrophobically associated polymer oil displacement agent with a cyclic disulfonate salt of the present invention is prepared from the following monomers in molar fractions (copolymerized from four monomers): 76.82 parts of acrylamide AM, 21.31 parts of 2-allylmethylaminoethylsulfonate AMES-Na, 1.53 parts of diallyldisulfoethyl betaine DADSBA, and a hydrophobic monomer with a benzene ring structure, long-chain alkyl dimethyl (p-3-carboxyacrylamidobenzyl) ammonium chloride C nDMCABAC 0.34 parts. The structural formula of the polymer oil displacement agent is the same as that of Example 1.

[0041] In the above structural formula, x, y, z, and p are the molar percentage ranges of the structural units: x=76.82%, y=21.31%, z=1.53%, p=0.34%, x+y+z+p=100%, wherein n=12, 14, 16, 18. In this embodiment, n=16.

[0042] The above hydrophobic monomer with benzene ring structure long chain alkyl dimethyl (p-3-carboxy acrylamide benzyl) ammonium chloride C n In DMCABAC, the long-chain alkyl group is octadecyl, in the following step (1), the long-chain alkyl dimethyl tertiary amine is octadecyl dimethyl tertiary amine, and in the following step (2), the final product is octadecyl dimethyl (p-3-carboxyacrylamidobenzyl) ammonium chloride C with a benzene ring structure hydrophobic monomer 18 DMCABAC.

[0043] The preparation method of the above-mentioned 2-allylmethylaminoethanesulfonic acid sodium AMES-Na comprises the following process steps: in a 500mL three-necked flask equipped with a thermometer, a reflux condenser with a Soxhlet extractor and a magnetic rotor, 190mL of anhydrous ethanol is added as a solvent, 82g of sodium 2-chloroethylsulfonate is added at a temperature of 25°C, and then 37g of N-methylallylamine is slowly added under stirring, 0.18g of methylhydroquinone as an inhibitor is added, 41g of potassium carbonate (acid binding agent) wrapped with filter paper is loaded into the Soxhlet extractor, the temperature is increased to reflux, and after constant temperature reaction for 24 hours, the solvent and excess N-methylallylamine are removed by reduced pressure distillation using a rotary evaporator to obtain 2-allylmethylaminoethanesulfonic acid sodium AMES-Na.

[0044] The preparation method of the salt-resistant monomer diallyl disulfoethyl betaine DADSBA comprises the following process steps: in a 500mL three-necked flask equipped with a thermometer, a reflux condenser with a Soxhlet extractor and a magnetic rotor, 200mL of anhydrous ethanol is added as a solvent, 32g of diallylamine is added at a temperature of 25°C, and then 117g of sodium 2-chloroethyl sulfonate is slowly added under stirring, 0.21g of methyl hydroquinone as an inhibitor is added, 30g of potassium carbonate (acid binding agent) wrapped with filter paper is loaded into the Soxhlet extractor, the temperature is increased to reflux, and after constant temperature reaction for 24 hours, the solvent is removed by reduced pressure distillation using a rotary evaporator, and recrystallization is performed using anhydrous ethanol to obtain the salt-resistant monomer diallyl disulfoethyl betaine DADSBA.

[0045] The above hydrophobic monomer with a benzene ring structure octadecyl dimethyl (p-3-carboxyacrylamide benzyl) ammonium chloride C 18The preparation method of DMCABAC comprises the following process steps: (1) in a 500 mL three-necked flask equipped with a thermometer, a reflux condenser and a magnetic rotor, 200 mL of anhydrous ethanol is added as a solvent, 100 g of octadecyl dimethyl tertiary amine is added at a temperature of 25° C., and then 45 g of p-aminobenzyl chloride is slowly added under stirring, the temperature is raised to reflux, and after constant temperature reaction for 14 hours, the solvent is removed by reduced pressure distillation using a rotary evaporator, and then recrystallization is performed using acetone to obtain octadecyl dimethyl (4-aminobenzyl) ammonium chloride; (2) in a 500 mL three-necked flask equipped with a thermometer, a reflux condenser and a magnetic rotor, 180 mL of anhydrous ethanol was added as a solvent, 85 g of octadecyl dimethyl (4-aminobenzyl) ammonium chloride was added at a temperature of 25° C., and then 22 g of maleic anhydride was slowly added under stirring, the temperature was raised to 70° C., and the reaction was carried out at a constant temperature for 7 hours to obtain a reaction solution, and the pH value of the reaction solution was adjusted to neutral by a pH adjuster, and the pH adjuster was a sodium hydroxide aqueous solution with a mass percentage concentration of 20%; then the solvent was removed by reduced pressure distillation using a rotary evaporator, and then separated and purified using anhydrous ethanol to obtain a hydrophobic monomer octadecyl dimethyl (p-3-carboxyacrylamide benzyl) ammonium chloride C with a benzene ring structure. 18 DMCABAC.

[0046] The preparation method of the hydrophobically associated polymer oil displacement agent with a cyclic structure of disulfonate (i.e. AM / AMES / DADSBA / C 18 The synthesis process of DMCABAC hydrophobic associating polymer oil displacement agent comprises the following process steps: firstly, 1200 mole parts of distilled water are added into a reactor, and 76.82 mole parts of acrylamide AM, 21.31 mole parts of 2-allylmethylaminoethylsulfonic acid sodium AMES-Na, 1.53 mole parts of diallyl disulfoethyl betaine DADSBA and octadecyl dimethyl (p-3-carboxyacrylamidobenzyl) ammonium chloride C with a benzene ring structure are added in sequence under stirring. 18 DMCABAC 0.34 parts, and then distilled water was added to control the total mass percentage concentration of the reaction monomers to 20%, and after stirring evenly, N2 was passed for 30 minutes; then 0.15% of the total mass of the four reaction monomers was added initiator, and N2 was continued to be passed, and the reaction was carried out under nitrogen protection at 45°C for 8 hours; after the reaction, the obtained gel product was washed with anhydrous ethanol, and the product was crushed and dried to obtain AM / AMES / DADSBA / C 18DMCABAC tetrapolymer, the tetrapolymer is a hydrophobically associated polymer oil displacement agent of disulfonate with a cyclic structure. The above-mentioned initiator is a composite initiator, including an oxidation-reduction system initiator and a water-soluble azo initiator. In the above-mentioned oxidation-reduction system initiator, the oxidant is potassium persulfate, the reductant is sodium bisulfite, and the molar ratio of the oxidant to the reductant is 1:1.2. The above-mentioned water-soluble azo initiator is azobisisobutylimidazoline hydrochloride (VA-044). In the composite initiator, the mass ratio of the oxidation-reduction system initiator to the water-soluble azo initiator is 1:1.7.

[0047] The following is the experimental (test) part of the present invention:

[0048] Experiment 1: AM / AMES / DADSBA / C 16 Structural characterization of the DMCABAC tetrapolymer oil-displacing agent (ie, the polymer oil-displacing agent of the present invention).

[0049] The structure of the polymer PAADC (i.e., the polymer oil displacement agent of the present invention) prepared in Example 1 was analyzed as follows: The FTIR spectrum of the polymer is as follows: Figure 1 Shown: 3333cm -1 -NH (antisymmetric) stretching vibration absorption peak; 3196cm -1 is the stretching vibration absorption peak of -NH (symmetrical); 2930cm -1 and 2852cm -1 They are the asymmetric and symmetric stretching vibration absorption peaks of methylene respectively; 1649cm -1 It is -C=O stretching vibration absorption peak; 1606cm -1 Benzene ring skeleton vibration absorption peak; 1451cm -1 The absorption peaks are the in-plane bending vibration absorption peaks of methylene and the vibration absorption peaks of benzene skeleton; 1417 cm -1 1347cm is the absorption peak of amide CN stretching vibration; -1 The stretching vibration absorption peak of tertiary amine and quaternary ammonium salt CN is at 1321cm -1 It is the CO stretching vibration absorption peak of carboxylic acid; 1183cm -1 and 1040cm -1 -SO3 characteristic absorption peak; 851cm -1 It is the absorption peak of the out-of-plane bending vibration of the benzene ring. The infrared spectrum confirms that the product contains structures such as -CONH2, -SO3, -CH2-, -CH3, -COO-, -C6H4-, tertiary amine, and quaternary ammonium salt. From the infrared spectrum data, it can be proved that the target product is AM / AMES / DADSBA / C 16 DMCABAC tetrapolymer (ie, the polymer oil-displacing agent of the present invention).

[0050] Experiment 2: AM / AMES / DADSBA / C 16 Viscosity test experiment of DMCABAC tetrapolymer oil-displacing agent (i.e., polymer oil-displacing agent of the present invention).

[0051] At room temperature (25±1°C), the apparent viscosities of the polymer PAADC and HPAM solutions (prepared with distilled water) prepared in Example 1 with different concentrations were measured using a NDJ-5S digital rotational viscometer to investigate the changes in their apparent viscosities with concentration. Figure 2 .Depend on Figure 2 It can be seen that at 1000 mg / L, the two polymers PAADC and HPAM can reach 43.4 mPa·s and 27.6 mPa·s respectively, at 2000 mg / L, they can reach 227.5 mPa·s and 101.2 mPa·s respectively, and at 4000 mg / L, they can reach 1298 mPa·s and 223.3 mPa·s respectively. The results show that compared with HPAM, when the concentration exceeds 1000 mg / L, the synthesized copolymer exhibits good viscosity-increasing ability.

[0052] Experiment 3: AM / AMES / DADSBA / C 16 Experimental test on the temperature resistance of the DMCABAC tetrapolymer oil-displacing agent (i.e., the polymer oil-displacing agent of the present invention).

[0053] The polymer PAADC (i.e., the polymer oil-displacing agent of the present invention) and HPAM prepared in Example 1 were prepared into a 2000 mg / L aqueous solution using distilled water. The relationship between the apparent viscosity of the PAADC and HPAM solutions and the temperature was measured at 25°C to 90°C. Figure 3 .Depend on Figure 3 It can be seen that the apparent viscosity of the two polymer solutions gradually decreases with the increase of temperature, and PAADC shows better temperature resistance. When the temperature reaches 90℃, the apparent viscosity of PAADC and HPAM solutions are 113.7mPa·s and 34.9mPa·s respectively. Compared with the viscosity at 25℃, the viscosity retention rates of the two polymers are 49.98% and 34.49% respectively; the results show that compared with HPAM, the synthesized polymer shows better temperature resistance.

[0054] Experiment 4: AM / AMES / DADSBA / C 16 Experimental test on the salt resistance of the DMCABAC tetrapolymer oil-displacing agent (i.e., the polymer oil-displacing agent of the present invention).

[0055] PAADC (i.e., the polymer oil-displacing agent of the present invention) and HPAM prepared in Example 1 were prepared into 2000 mg / L aqueous solutions using mixed brine of different concentrations (the ratio of various salts in the mixed brine was NaCl:KCl:CaCl2:MgCl2=7:2:0.6:0.4, mass ratio). The apparent viscosities of the two polymer solutions were measured at 25°C. Figure 4 .Depend on Figure 4 It can be seen that when the mineralization of the brine increases, the apparent viscosity of the two polymers increases first and then decreases. PAADC shows better salt resistance, showing salt thickening phenomenon below the mineralization of 7000mg / L, while HPAM shows salt thickening phenomenon below the mineralization of 1000mg / L. When the content of brine increases to 50000mg / L, the apparent viscosity of PAADC and HPAM solutions are 97.6mPa·s and 13.5mPa·s, respectively, and their viscosity retention rates are 42.90% and 13.34%, respectively; the results show that compared with HPAM, the synthesized polymer shows better salt resistance.

[0056] Experiment 5: AM / AMES / DADSBA / C 16 Shear resistance test experiment of DMCABAC tetrapolymer (i.e., polymer oil displacement agent of the present invention).

[0057] The polymer PAADC (i.e., the polymer oil-displacing agent of the present invention) and HPAM prepared in Example 1 were prepared into a target solution of 2000 mg / L using distilled water, and the polymer solutions were sheared at rotation speeds of 3500 r / min, 7000 r / min, 11500 r / min, 14500 r / min, and 17000 r / min, respectively. The shear resistance of the two polymer solutions was investigated. Figure 5 .Depend on Figure 5 It can be seen that the apparent viscosity of the two polymer solutions decreases with the increase of shear rate. When the shear speed is 3500r / min, the apparent viscosities of the two polymers PAADC and HPAM are 190.1mPa·s and 63.7mPa·s respectively; their viscosity retention rates are 83.56% and 62.94% respectively; when the speed reaches 17000r / min, the apparent viscosities of the two polymers are 91.3mPa·s and 12.5mPa·s respectively, and their viscosity retention rates are 40.13% and 12.35% respectively. The results show that compared with HPAM, the synthesized polymer exhibits better shear resistance.

[0058] Experiment 6: AM / AMES / DADSBA / C 16 Indoor core flooding experiment of DMCABAC tetrapolymer (i.e., polymer oil-displacing agent of the present invention).

[0059] The polymer PAADC prepared in Example 1 (i.e., the polymer oil-displacing agent of the present invention) was prepared into a 2000 mg / L aqueous solution using a mixed brine with a salinity of 30000 mg / L (the ratio of various salts in the mixed brine was NaCl: KCl: CaCl2: MgCl2 = 7:2:0.6:0.4, mass ratio), a simulated reservoir temperature of 70°C, a simulated oil viscosity of 83.1 mPa·s, a three-layer heterogeneous core of 4.5×4.5×30.0 cm, and an average permeability of 1189×10 -3 μm 2 . The core saturated with simulated oil was displaced with brine at an injection rate of 1 mL / min. When the instantaneous water content exceeded 70%, polymer flooding was carried out with an injection volume of 0.3 PV, followed by subsequent water flooding until the three instantaneous water content reached 95%, and the final recovery was calculated. The same method was used for water flooding until the three instantaneous water content reached 95%. The experimental results show that the final recovery rate of water flooding is 30.52%, and the final recovery rate of polymer flooding is 44.18%. Through indoor oil recovery experiments, it was calculated that the polymer can increase the recovery rate by 13.66%. The polymer has a good oil recovery effect under high temperature and high mineralization.

[0060] In summary, the polymer oil-displacing agent prepared by the above embodiments of the present invention has good viscosity increasing property, shows good salt resistance in mixed brine with salinity ≥30000mg / L, shows good oil displacement effect in indoor oil displacement experiment, and improves crude oil recovery by more than 10%. The present invention provides a (water-soluble) hydrophobic associating polymer oil-displacing agent with cyclic structure disulfonate, which has good performance, good viscosity increasing ability under high temperature and high salinity, and good shear resistance, achieves a high recovery rate, and can meet the technical requirements of polymer oil-displacing agents with a wide range of uses on the market, thereby ensuring the smooth progress of oil exploitation in high temperature and high salinity oil fields, and solving the problems of poor temperature and salt resistance of existing hydrophobic associating polymers in saline with high salinity (mineralization ≥30000mg / L), easy hydrolysis underground, and low crude oil recovery rate.

Claims

1. A hydrophobically associating polymer oil-displacing agent having a cyclic structure of disulfonate, characterized in that It is composed of acrylamide AM, 2-allylmethylaminoethylsulfonic acid sodium AMES-Na, diallyldisulfoethyl betaine DADSBA and a hydrophobic monomer with a benzene ring structure, a long-chain alkyl dimethyl (p-3-carboxyacrylamide benzyl) ammonium chloride C n DMCABAC is copolymerized by four monomers, and the structural formula of the polymer oil displacement agent is as follows: In the above structural formula, x, y, z, and p are the molar percentage ranges of the structural units: x=72% to 83.8%, y=15% to 25%, z=1% to 2%, p=0.2% to 1%, x+y+z+p=100%, wherein n=12, 14, 16, or 18.

2. The oil-displacing agent of the disulfonate hydrophobically associating polymer having a cyclic structure according to claim 1, characterized in that The molar fractions of each monomer are as follows: acrylamide AM 72-83.8 parts, 2-allylmethylaminoethylsulfonic acid sodium AMES-Na 15-25 parts, diallyl disulfoethyl betaine DADSBA 1-2 parts, long-chain alkyl dimethyl (p-3-carboxyacrylamide benzyl) ammonium chloride C with a benzene ring structure hydrophobic monomer n DMCABAC 0.2~1.0 parts.

3. The oil-displacing agent of the disulfonate hydrophobically associating polymer having a cyclic structure according to claim 1 or 2, characterized in that The preparation method of 2-allylmethylaminoethanesulfonic acid sodium AMES-Na comprises the following process steps: adding an appropriate amount of anhydrous ethanol as a solvent to a three-necked flask equipped with a thermometer, a reflux condenser with a Soxhlet extractor and a magnetic rotor, adding 65-95 g of sodium 2-chloroethylsulfonate at room temperature, then slowly adding 30-43 g of N-methylallylamine under stirring, adding 0.15-0.21 g of methylhydroquinone as an inhibitor, and charging 32-47 g of an acid binding agent wrapped with filter paper into the Soxhlet extractor, raising the temperature to reflux, reacting at a constant temperature for 20-25 hours, and removing the solvent and excess N-methylallylamine by reduced pressure distillation using a rotary evaporator to obtain 2-allylmethylaminoethanesulfonic acid sodium AMES-Na.

4. The oil-displacing agent of the disulfonate hydrophobically associating polymer having a cyclic structure according to claim 1 or 2, characterized in that The preparation method of the salt-resistant monomer diallyl disulfoethyl betaine DADSBA comprises the following process steps: adding an appropriate amount of anhydrous ethanol as a solvent to a three-necked flask equipped with a thermometer, a reflux condenser with a Soxhlet extractor and a magnetic rotor, adding 25-35g of diallylamine at room temperature, then slowly adding 100-130g of 2-chloroethyl sodium sulfonate under stirring, adding 0.17-0.25g of methyl hydroquinone as an inhibitor, and charging 23-33g of an acid binding agent wrapped with filter paper into the Soxhlet extractor, raising the temperature to reflux, reacting at a constant temperature for 20-25 hours, removing the solvent by reduced pressure distillation using a rotary evaporator, and recrystallizing using anhydrous ethanol to obtain the salt-resistant monomer diallyl disulfoethyl betaine DADSBA.

5. The oil-displacing agent of the disulfonate hydrophobically associating polymer having a cyclic structure according to claim 1 or 2, characterized in that The above hydrophobic monomer with benzene ring structure long chain alkyl dimethyl (p-3-carboxy acrylamide benzyl) ammonium chloride C n The preparation method of DMCABAC comprises the following process steps: (1) adding an appropriate amount of anhydrous ethanol as a solvent to a three-necked flask equipped with a thermometer, a reflux condenser and a magnetic rotor, adding 80-120 g of a long-chain alkyl dimethyl tertiary amine at room temperature, and then slowly adding 40-60 g of p-aminobenzyl chloride under stirring, raising the temperature to reflux, and reacting at a constant temperature for 10-15 hours, removing the solvent by reduced pressure distillation using a rotary evaporator, and then recrystallizing using acetone to obtain a long-chain alkyl dimethyl (4-aminobenzyl) ammonium chloride; (2) adding 10-20 g of a reflux condenser to a three-necked flask equipped with a thermometer, a reflux condenser and a magnetic rotor, and then adding 10-20 g of a reflux condenser to a three-necked flask equipped with a thermometer, a reflux condenser and a magnetic rotor. A three-necked flask is added with an appropriate amount of anhydrous ethanol as a solvent, 60-100 g of long-chain alkyl dimethyl (4-aminobenzyl) ammonium chloride is added at room temperature, and then 16-27 g of maleic anhydride is slowly added under stirring, the temperature is raised to 60-70°C, and the reaction is carried out at a constant temperature for 6-8 hours to obtain a reaction solution, the pH value of the reaction solution is adjusted to neutral by a pH regulator, and then the solvent is removed by reduced pressure distillation using a rotary evaporator, and then separated and purified by anhydrous ethanol to obtain a hydrophobic monomer long-chain alkyl dimethyl (p-3-carboxyacrylamide benzyl) ammonium chloride C with a benzene ring structure. n DMCABAC.

6. The oil-displacing agent of the disulfonate hydrophobically associating polymer having a cyclic structure according to claim 1, characterized in that The preparation method comprises the following process steps: firstly, 1000-1500 mole parts of distilled water are added into a reactor, and then 72-83.8 mole parts of acrylamide AM, 15-25 mole parts of 2-allylmethylaminoethylsulfonate AMES-Na, 1-2 mole parts of diallyl disulfoethyl betaine DADSBA, long-chain alkyl dimethyl (p-3-carboxyacrylamidobenzyl) ammonium chloride C are added in sequence under stirring. n DMCABAC 0.2-1 molar part, and then distilled water is added to control the total mass percentage concentration of the reaction monomers to be between 15% and 30%, and after stirring evenly, N2 is passed for 30-35 minutes; then an initiator is added, and N2 is continued to be passed, and the reaction is carried out under nitrogen protection at 30-60°C for 4-10 hours; after the reaction, the obtained gel product is washed with anhydrous ethanol, and the product is crushed and dried to obtain AM / AMES / DADSBA / C n The DMCABAC tetrapolymer is a disulfonate hydrophobically associating polymer oil displacement agent having a cyclic structure.

7. The oil-displacing agent of the disulfonate hydrophobically associating polymer having a cyclic structure according to claim 6, characterized in that The addition amount of the above-mentioned initiator is 0.05% to 0.2% of the total mass of the four reaction monomers; the above-mentioned initiator is a composite initiator, including an oxidation-reduction system initiator and a water-soluble azo initiator; in the oxidation-reduction system initiator, the oxidant is potassium persulfate or ammonium persulfate, the reductant is sodium bisulfite, and the molar ratio of the oxidant to the reductant is 1:1 to 1.5; the water-soluble azo initiator is one or a combination of azobisisobutylamidine hydrochloride V-50, azobisisobutylimidazoline hydrochloride VA-044, and azobis(N-2-carboxyethyl-2-methylpropionamidine) hydrate VA-057, and the ratio when combined is arbitrary; in the composite initiator, the mass ratio of the oxidation-reduction system initiator to the water-soluble azo initiator is 1:1 to 2.

8. The oil-displacing agent of the disulfonate hydrophobically associating polymer having a cyclic structure according to claim 5, characterized in that The pH value adjusting agent is a sodium hydroxide aqueous solution with a mass percentage concentration of 20%; The above hydrophobic monomer with benzene ring structure long chain alkyl dimethyl (p-3-carboxy acrylamide benzyl) ammonium chloride C n In DMCABAC, the long-chain alkyl group is hexadecyl, in step (1), the long-chain alkyl dimethyl tertiary amine is hexadecyl dimethyl tertiary amine, and in step (2), the final product is hexadecyl dimethyl (p-3-carboxyacrylamidobenzyl) ammonium chloride C with a benzene ring structure. 16 DMCABAC; or, The above hydrophobic monomer with benzene ring structure long chain alkyl dimethyl (p-3-carboxy acrylamide benzyl) ammonium chloride C n In DMCABAC, the long-chain alkyl group is octadecyl, in step (1), the long-chain alkyl dimethyl tertiary amine is octadecyl dimethyl tertiary amine, and in step (2), the final product is octadecyl dimethyl (p-3-carboxyacrylamidobenzyl) ammonium chloride C with a benzene ring structure. 18 DMCABAC.

9. The oil-displacing agent of the disulfonate hydrophobically associating polymer having a cyclic structure according to claim 3 or 4, characterized in that The above acid binding agent is potassium carbonate or sodium carbonate.

10. A method for preparing the oil-displacing agent of the disulfonate hydrophobically associating polymer having a cyclic structure according to claim 1, characterized in that The method comprises the following process steps: firstly, 1000-1500 mole parts of distilled water are added into a reactor, and then 72-83.8 mole parts of acrylamide AM, 15-25 mole parts of 2-allylmethylaminoethylsulfonic acid sodium AMES-Na, 1-2 mole parts of diallyl disulfoethyl betaine DADSBA, long-chain alkyl dimethyl (p-3-carboxyacrylamidobenzyl) ammonium chloride C are added in sequence under stirring. n DMCABAC 0.2-1 molar part, and then distilled water is added to control the total mass percentage concentration of the reaction monomers to be between 15% and 30%, and after stirring evenly, N2 is passed for 30 minutes; then an initiator is added, and N2 is continued to be passed, and the reaction is carried out under nitrogen protection at 30-60°C for 4-10 hours; after the reaction, the obtained gel product is washed with anhydrous ethanol, and the product is crushed and dried to obtain AM / AMES / DADSBA / C n The DMCABAC tetrapolymer is a disulfonate hydrophobically associating polymer oil displacement agent having a cyclic structure.

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