A disulfonic acid betaine viscoelastic surfactant and its preparation method and application

Abstract

The invention discloses a disulfonic acid betaine viscoelastic surfactant and a preparation method and application thereof, belonging to the technical field of viscoelastic surfactants. The preparation method comprises the following steps: adding sodium allyl sulfonate and a long-chain primary amine to a solvent, adding an alkali catalyst, mixing evenly, and performing a Michael addition reaction to obtain a product intermediate; mixing the product intermediate and a quaternary ammonium agent evenly to perform a substitution reaction; cooling and adjusting the pH value after the substitution reaction, and then refluxing to obtain a transparent liquid; distilling the transparent liquid to obtain a viscous substance, drying, washing, filtering and recrystallizing the viscous substance to obtain a disulfonic acid betaine type surfactant. The surfactant has good chemical stability, acid and alkali resistance, high temperature resistance and salt resistance, and also maintains the advantage of the surfactant being biodegradable, and is a green surfactant for enhanced oil recovery.

Description

Technical Field

[0001] The invention belongs to the technical field of viscoelastic surfactants, and in particular relates to a disulfonic acid betaine viscoelastic surfactant and a preparation method and application thereof. Background Art

[0002] Amphoteric surfactants refer to surfactants that contain both anionic and cationic hydrophilic groups in the molecule. They have good emulsification, dispersibility, antistatic, bactericidal, biodegradability and other properties, and have good stability to acids, alkalis and various metal ions. Betaine amphoteric surfactants refer to surfactants with surface activity and a structure similar to betaine. The biggest difference from traditional amphoteric surfactants is that they contain quaternary ammonium nitrogen in their molecular structure, have a wide isoelectric point range, have good surface activity, and have the advantages of good compatibility, low toxicity, low irritation, and high biodegradability. Among them, sulfobetaine has unique advantages such as resistance to high concentrations of acid, alkali, and salt, and most of them can be used in harsh oil reservoirs with high temperature and high mineralization. It has been used in daily chemical industry, oil recovery and other fields, and through development and promotion, in medicine, textiles, washing and other fields.

[0003] Among the synthetic sulfobetaine surfactants, the best reaction is between long-chain alkyl tertiary amines and propane sultone, but propane sultone is difficult to apply on a large scale in industrial production due to its high price and explosiveness. Hydroxyl-containing sulfobetaine is more water-soluble than general betaine without hydroxyl groups, but it has many isomers, which is not conducive to separation and purification.

[0004] CN101549266A discloses the preparation and application of a di-long-chain alkyl betaine surfactant, which is prepared by reacting a di-long-chain alkyl methyl tertiary amine with chloroacetic acid, and is an amphoteric surfactant. By compounding it with other surfactants, it is used as an alkali-free oil displacement agent. CN102977873A discloses a diamide betaine surfactant and a preparation method thereof, which is prepared by reacting a diamide alkyl methyl tertiary amine with an amphoteric reagent such as sodium chloroacetate or sodium chloro(bromo)ethyl sulfonate or propane(butane) sultone or sodium 3-chloro-2-hydroxypropane sulfonate. By compounding it with other surfactants, it can be used as an alkali-free oil displacement agent. The price of the raw material tertiary amine in the preparation schemes of CN101549266A and CN102977873A is relatively expensive, the solubility, calcium saponification dispersibility and wettability of the di-long-chain alkyl and diamide betaine surfactants are not as good as those of the sulfonic acid surfactants, and the amide surfactants have poor stability in strong acid and strong alkali solutions, which limits the application of this type of surfactant to a certain extent.

[0005] CN101618302A discloses a long-chain sulfonic acid betaine surfactant and its preparation, starting from a long-chain fatty acid, firstly a long-chain fatty acid chloride is obtained by a halogenation reaction, and then the long-chain fatty acid chloride is amidated with a diamine to generate a tertiary amine intermediate (AnBm), and finally the intermediate is reacted with a quaternary ammonium reagent 1,3-propane sulfonated lactone to generate a long-chain sulfonic acid betaine surfactant. The preparation scheme has the problems of complex synthesis process of pure products, huge solvent consumption, difficulty in recovery, and easy environmental pollution. Summary of the invention

[0006] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a disulfonic acid betaine viscoelastic surfactant and a preparation method and application thereof. The surfactant has good chemical stability, acid and alkali resistance, high temperature resistance and salt resistance, and also maintains the advantage of biodegradability of the surfactant, and is a green surfactant for enhanced oil recovery.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] The present invention provides a bissulfonate betaine viscoelastic surfactant, the structural formula of the bissulfonate betaine viscoelastic surfactant is as follows:

[0009]

[0010] Wherein, R is a normal or isomeric alkyl group of C12 to 18, and X is CH2COONa, CH2CH3 or CHOHCH2COONa.

[0011] The present invention provides a method for preparing the disulfonic acid betaine viscoelastic surfactant, comprising the following steps:

[0012] S1: adding sodium allyl sulfonate and long-chain primary amine into a solvent, and adding a base catalyst, mixing them evenly to carry out Michael addition reaction to obtain a product intermediate;

[0013] S2: uniformly mixing the product intermediate and the quaternary ammonium reagent to carry out a substitution reaction;

[0014] S3: After the substitution reaction is completed, the reaction is cooled and the pH value is adjusted, and then refluxed to obtain a transparent liquid;

[0015] S4: distilling the transparent liquid to obtain a viscous substance, drying, washing, filtering and recrystallizing the viscous substance to obtain a disulfonic acid betaine type surfactant.

[0016] The present invention further discloses that in S1, the molar ratio of the sodium allyl sulfonate to the long-chain primary amine is (2-2.5):1.

[0017] The present invention further states that in S1, the general structural formula of the long-chain primary amine is as follows:

[0018] R-NH2

[0019] Wherein, R is a C12-18 normal or isomeric alkyl group.

[0020] The present invention further discloses that in S1, the solvent is one of isopropanol aqueous solution, tetrahydrofuran or 1,4-dioxane; and the base catalyst is one of sodium ethoxide, sodium hydroxide and potassium hydroxide.

[0021] The present invention further comprises that in S1, the water bath temperature of the Michael addition reaction is 70-85° C., the reaction time of the Michael addition reaction is 3-5 h, and the stirring speed of the Michael addition reaction is 100-300 rpm.

[0022] The present invention further discloses that in S2, the quaternizing agent is one of sodium chloroacetate, sodium bromoacetate, ethyl chloride, ethyl bromide or sodium 3-chloro-2-hydroxypropane sulfonate.

[0023] The present invention further comprises that in S2, the molar ratio of the product intermediate to the quaternary ammonium agent is 1:(1-1.5).

[0024] The present invention further comprises that in S3, the cooling temperature is below 50°C; and the pH value is 8-9.

[0025] The application of the disulfonate betaine viscoelastic surfactant is used as an oil displacement agent or fracturing fluid in oil reservoir development.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The invention provides a disulfonic acid betaine viscoelastic surfactant. Dihydrophilic sulfonic acid group and monohydrophobic long-chain alkyl group betaine are synthesized by taking low-priced primary amine and sodium allyl sulfonate as main raw materials, and a sulfonic acid functional group (disulfonic acid group) is introduced to improve the temperature resistance, salt resistance and water solubility of the surfactant. The surfactant has good chemical stability, acid and alkali resistance, high temperature resistance and salt resistance, and also maintains the advantage of biodegradability of the surfactant. The surfactant is a green surfactant for enhanced oil recovery.

[0028] The present invention provides a method for preparing a disulfonic acid betaine viscoelastic surfactant, wherein cheap raw materials are selected, a Michael addition reaction occurs under mild conditions, and a novel temperature-resistant, acid-resistant, alkali-resistant and salt-resistant surfactant is synthesized by a one-step synthesis method, and the preparation process is simple, the pollution is small, and the cost is low. The present invention synthesizes a highly hydrophilic surfactant by changing the raw materials and the synthetic process route, and the surfactant adds two hydrophilic sulfonic acid groups on the basis of alkyl betaine, so that the salt resistance and chemical stability of the surfactant are improved, the reaction conditions are mild, and it can be used for industrial large-scale production.

[0029] The disulfonic acid betaine viscoelastic surfactant of the present invention can be used in oil layers with high mineralization and high temperature in tertiary oil recovery. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0031] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0032] Herein, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0033] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0034] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0035] The invention provides a disulfonic acid betaine viscoelastic surfactant and a preparation method and application thereof.

[0036] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0037] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0038] The present invention discloses a disulfonic acid betaine viscoelastic surfactant, the structural formula of the viscoelastic surfactant is:

[0039]

[0040] Wherein R is a C12-18 normal or isomeric alkyl group, and X is CH2COONa or CH2CH3 or CHOHCH2COONa, preferably a C12-18 normal alkyl group.

[0041] The synthesis process of the disulfonic acid betaine viscoelastic surfactant is as follows:

[0042]

[0043] The invention discloses a method for preparing a disulfonic acid betaine viscoelastic surfactant, comprising the following steps:

[0044] S1: adding sodium allyl sulfonate and long-chain primary amine into a solvent, and adding a base catalyst, mixing them evenly to carry out Michael addition reaction to obtain a product intermediate;

[0045] S2: uniformly mixing the product intermediate and the quaternary ammonium reagent to carry out a substitution reaction;

[0046] S3: After the substitution reaction is completed, the reaction is cooled and the pH value is adjusted, and then the reaction is refluxed for a set time to obtain a transparent liquid;

[0047] S4: distilling the transparent liquid to obtain a viscous substance, drying, washing, filtering and recrystallizing the viscous substance to obtain a disulfonic acid betaine type surfactant.

[0048] As an alternative, the general structural formula of the long-chain primary amine is as follows:

[0049] R-NH2

[0050] Wherein, R is a C12-18 normal or isomeric alkyl group, and further, R is a C12-18 normal alkyl group

[0051] As an optional solution, the solvent is one of isopropanol aqueous solution, tetrahydrofuran, and 1,4-dioxane.

[0052] As an optional solution, the alkaline catalyst is one of sodium ethoxide, sodium hydroxide and potassium hydroxide.

[0053] As an optional solution, the molar ratio of the long-chain primary amine to sodium allyl sulfonate is 1:(2-2.5), more preferably 1:2.

[0054] The water bath temperature of the Michael addition reaction is 70-85°C, the reaction time of the Michael addition reaction is 3-5h, the stirring speed of the Michael addition reaction is 100-300rpm, and more preferably, the temperature is 70-80°C, the reaction time is 3-4h, and the stirring speed is 200-300rpm.

[0055] As an optional solution, the quaternizing agent is one of sodium chloroacetate, sodium bromoacetate, ethyl chloride, ethyl bromide or sodium 3-chloro-2-hydroxypropane sulfonate.

[0056] As an optional solution, the molar ratio of the product intermediate to the quaternary ammonium agent is 1:(1-1.5), more preferably 1:1.

[0057] As an optional solution, the temperature of the substitution reaction is 50-80°C, the reaction time is 2-5h, and the stirring speed is 300-500rpm, more preferably the temperature is 50-70°C, the reaction time is 3-4h, and the stirring speed is 350-400rpm.

[0058] As an optional solution, the cooling temperature is below 50°C; and the pH value is 8-9.

[0059] As an optional scheme, the distillation is vacuum distillation; the washing is performed 2 to 3 times; petroleum ether is used for washing and then dissolved in anhydrous ethanol; the recrystallization is performed 3 to 5 times and one of acetone, ethanol and methanol is used for purification.

[0060] As an optional solution, the drying is carried out by vacuum drying at a drying temperature of 90-100°C.

[0061] According to a more specific preferred embodiment, the preparation method of the viscoelastic surfactant specifically comprises the following steps:

[0062] (1) Sodium allyl sulfonate is added to a mixed solution of a solvent and a base catalyst in a 250 mL three-necked flask equipped with a reflux condenser, a thermometer, and a stirrer, and stirred until completely dissolved. After the reaction temperature reaches 70-85°C, an alkyl primary amine is slowly added dropwise using a constant pressure funnel, and the reaction is refluxed for 3-5 hours to obtain a product intermediate, which is then subjected to a substitution reaction with a quaternary ammonium agent.

[0063] (2) The reactants are then cooled to below 50°C, the pH value is adjusted to between 8 and 9, and the reflux reaction is continued for a certain period of time to obtain a transparent liquid. After completion, the isopropanol, water and residual primary amine are removed by vacuum distillation to obtain a viscous substance (or waxy substance).

[0064] (3) The product is vacuum dried until the mass no longer decreases, washed with an appropriate amount of petroleum ether, dissolved in anhydrous ethanol, filtered while hot to remove inorganic salt ions, and the filtrate is cooled to obtain a crude product.

[0065] (4) After recrystallization, a white powdery solid substance - a disulfonic acid betaine type surfactant is obtained.

[0066] The viscoelastic surfactant of the present invention is used as an oil displacement agent or fracturing fluid in oil reservoir development. Furthermore, the surfactant prepared by the present invention is applied to the field of tertiary oil recovery as an oil displacement agent.

[0067] Example 1

[0068] (1) Add 0.2 mol of sodium allyl sulfonate to a mixed solution of 100 mL of isopropanol aqueous solution and sodium ethoxide in a 250 mL three-necked flask equipped with a reflux condenser, a thermometer, and a stirrer, and stir until completely dissolved. After the reaction temperature reaches 80°C, slowly add 0.1 mol of dodecyl primary amine dropwise using a constant pressure funnel, and react under reflux for 3 hours to obtain a product intermediate, which is then added with ethyl bromide at a molar ratio of 1:1 to undergo quaternization reaction.

[0069] (2) The reactants are then cooled to below 50°C, the pH value is adjusted to 8, and the reflux reaction is continued for a certain period of time to obtain a transparent liquid. After completion, the isopropanol, water and residual primary amine are removed by vacuum distillation to obtain a viscous substance (or waxy substance).

[0070] (3) The product was dried under vacuum at 90°C until the mass no longer decreased, washed with an appropriate amount of petroleum ether, dissolved in anhydrous ethanol and washed twice, filtered while hot to remove inorganic salt ions, and the filtrate was cooled to obtain a crude product.

[0071] (4) Recrystallize three more times to obtain a white powdery solid substance - a disulfonic acid betaine type surfactant.

[0072] Example 2

[0073] (1) Add 0.2 mol sodium allyl sulfonate to 100 mL of a mixed solution of 1,4-dioxane and sodium hydroxide in a 250 mL three-necked flask equipped with a reflux condenser, a thermometer, and a stirrer, and stir until completely dissolved. After the reaction temperature reaches 81°C, slowly add 0.1 mol tetradecyl primary amine dropwise using a constant pressure funnel, and react under reflux for 3.5 hours to obtain a product intermediate, which is then added with ethyl chloride at a molar ratio of 1:1 to undergo quaternization reaction.

[0074] (2) The reactants are then cooled to below 50°C, the pH value is adjusted to 8, and the reflux reaction is continued for a certain period of time to obtain a transparent liquid. After completion, the isopropanol, water and residual primary amine are removed by vacuum distillation to obtain a viscous substance (or waxy substance).

[0075] (3) The product was dried under vacuum at 93°C until the mass no longer decreased, then washed with an appropriate amount of petroleum ether, dissolved in anhydrous ethanol and washed three times, filtered while hot to remove inorganic salt ions, and the filtrate was cooled to obtain a crude product.

[0076] (4) Recrystallize four more times to obtain a white powdery solid substance - a disulfonic acid betaine type surfactant.

[0077] Example 3

[0078] (1) Add 0.2 mol sodium allyl sulfonate to a mixed solution of 100 mL tetrahydrofuran and potassium hydroxide in a 250 mL three-necked flask equipped with a reflux condenser, a thermometer, and a stirrer, and stir until completely dissolved. After the reaction temperature reaches 83°C, slowly add 0.1 mol hexadecyl primary amine dropwise using a constant pressure funnel, and react under reflux for 4 hours to obtain a product intermediate, which is then added with sodium bromoacetate at a molar ratio of 1:1 to undergo quaternization reaction.

[0079] (2) The reactants are then cooled to below 53°C, the pH value is adjusted to 9, and the reflux reaction is continued for a certain period of time to obtain a transparent liquid. After completion, the isopropanol, water and residual primary amine are removed by vacuum distillation to obtain a viscous substance (or waxy substance).

[0080] (3) The product was dried under vacuum at 95°C until the mass no longer decreased, washed with an appropriate amount of petroleum ether, dissolved in anhydrous ethanol and washed twice, filtered while hot to remove inorganic salt ions, and the filtrate was cooled to obtain a crude product.

[0081] (4) Recrystallize 5 more times to obtain a white powdery solid substance - a disulfonic acid betaine type surfactant.

[0082] Example 4

[0083] (1) Add 0.2 mol sodium allyl sulfonate to a mixed solution of 100 mL isopropanol aqueous solution and sodium ethoxide in a 250 mL three-necked flask equipped with a reflux condenser, a thermometer, and a stirrer, and stir until completely dissolved. After the reaction temperature reaches 85°C, slowly add 0.1 mol octadecyl primary amine dropwise using a constant pressure funnel, and react under reflux for 5 hours to obtain a product intermediate, which is then added with sodium chloroacetate at a molar ratio of 1:1 to undergo quaternization reaction.

[0084] (2) The reactants are then cooled to below 50°C, the pH value is adjusted to 9, and the reflux reaction is continued for a certain period of time to obtain a transparent liquid. After completion, the isopropanol, water and residual primary amine are removed by vacuum distillation to obtain a viscous substance (or waxy substance).

[0085] (3) The product was vacuum dried at 100°C until the mass no longer decreased, then washed with an appropriate amount of petroleum ether, dissolved in anhydrous ethanol and washed three times, filtered while hot to remove inorganic salt ions, and the filtrate was cooled to obtain a crude product.

[0086] (4) Recrystallize three more times to obtain a white powdery solid substance - a disulfonic acid betaine type surfactant.

[0087] Example 5

[0088] (1) Add 0.25 mol of sodium allyl sulfonate to a mixed solution of 100 mL of tetrahydrofuran and sodium ethoxide in a 250 mL three-necked flask equipped with a reflux condenser, a thermometer, and a stirrer, and stir until completely dissolved. After the reaction temperature reaches 70°C, slowly add 0.1 mol of dodecyl primary amine dropwise using a constant pressure funnel, and react under reflux for 5 hours to obtain a product intermediate, which is then added with ethyl bromide at a molar ratio of 1:1.5 to undergo quaternization reaction.

[0089] (2) The reactants are then cooled to below 50°C, the pH value is adjusted to 9, and the reflux reaction is continued for a certain period of time to obtain a transparent liquid. After completion, the isopropanol, water and residual primary amine are removed by vacuum distillation to obtain a viscous substance (or waxy substance).

[0090] (3) The product was dried under vacuum at 95°C until the mass no longer decreased, washed with an appropriate amount of petroleum ether, dissolved in anhydrous ethanol and washed twice, filtered while hot to remove inorganic salt ions, and the filtrate was cooled to obtain a crude product.

[0091] (4) Recrystallize twice to obtain a white powdery solid substance - a disulfonic acid betaine type surfactant.

[0092] Example 6

[0093] (1) Add 0.25 mol sodium allyl sulfonate to a mixed solution of 100 mL isopropanol aqueous solution and sodium ethoxide in a 250 mL three-necked flask equipped with a reflux condenser, a thermometer, and a stirrer, and stir until completely dissolved. After the reaction temperature reaches 85°C, slowly add 0.1 mol octadecyl primary amine dropwise using a constant pressure funnel, and react under reflux for 5 hours to obtain a product intermediate, which is then added with sodium chloroacetate at a molar ratio of 1:1.5 to undergo quaternization reaction.

[0094] (2) The reactants are then cooled to below 50°C, the pH value is adjusted to 9, and the reflux reaction is continued for a certain period of time to obtain a transparent liquid. After completion, the isopropanol, water and residual primary amine are removed by vacuum distillation to obtain a viscous substance (or waxy substance).

[0095] (3) The product was vacuum dried at 100°C until the mass no longer decreased, then washed with an appropriate amount of petroleum ether, dissolved in anhydrous ethanol and washed three times, filtered while hot to remove inorganic salt ions, and the filtrate was cooled to obtain a crude product.

[0096] (4) Recrystallize three more times to obtain a white powdery solid substance - a disulfonic acid betaine type surfactant.

[0097] Test Case

[0098] The H-NMR spectrum data of a disulfonic acid betaine viscoelastic surfactant obtained in Example 1 are as follows:

[0099] 1H NMR (300MHz, DMSO): δ4.18 (s, 2H), 3.41 (t, 4H), 3.24 (t, 6H), 2.29 (m, 4H), 1.73 (m, 2H), 1.25~1.37 (m, 18H), 0.96 (t, 3H)ppm.

[0100] In order to characterize the effects of the synthetic products of different amine lengths of the disulfonic acid betaine viscoelastic surfactant on the surface, interface, cmc, and oil displacement efficiency, the disulfonic acid betaine viscoelastic surfactants with different amine lengths synthesized in Examples 1 to 4 were tested for surface, interface, cmc, and oil displacement efficiency. The results are shown in Table 1.

[0101] Table 1 Tests of various properties of surfactants

[0102]

[0103] As shown in Table 1, the molar ratio of the reactants in Examples 1 to 4 remains unchanged, and the reactants are changed to primary amines with different alkyl chain lengths. The experimental results show that the cmc value and surface tension of the prepared surfactants gradually decrease with the increase of the alkyl chain length. This is because as the carbon chain grows, the hydrophobic effect of the surfactant increases, and the surfactant is more likely to aggregate into micelles, so the cmc will decrease.

[0104] For the surface tension corresponding to cmc, due to the enhanced hydrophobic effect, the surfactant molecules are arranged more closely on the interface, and thus the ability to reduce the surface tension is also enhanced.

[0105] The surface tension of the surfactant was determined by the drop volume method to obtain its critical micelle concentration and critical surface tension. The results showed that the critical micelle concentration of the disulfonate betaine surfactant was 10-20 times lower than that of the sulfonate betaine surfactant, and the surface tension of the surfactant was less than 30mN / m. The results showed that the prepared surfactant had high activity.

[0106] At the same time, as the length of the carbon chain increases, the hydrophobicity of the disulfonic acid betaine surfactant molecules increases, the interaction between the hydrophobic group and the oil phase increases, the interaction between the oil-water interface and the oil phase and the water phase is no longer balanced, the hydrophobic force increases, and thus the interfacial tension increases accordingly.

[0107] The present invention synthesizes a class of betaine-type surfactants with disulfonic acid groups by a one-step method, thereby increasing the hydrophilicity of the amphoteric surfactant. The invention has a simple preparation process, low raw material cost, and can keep the interfacial tension at an ultra-low 10 -3 mN / m order of magnitude, and can give full play to the viscoelastic effect of the polymer to achieve an ideal chemical flooding effect.

[0108] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A disulfonic acid betaine viscoelastic surfactant, characterized in that: The structural formula of the bissulfonic acid betaine viscoelastic surfactant is as follows: Wherein, R is a normal or isomeric alkyl group of C12 to 18, and X is CH2COONa, CH2CH3 or CHOHCH2COONa.

2. A method for preparing the bissulfonate betaine viscoelastic surfactant according to claim 1, characterized in that: The following steps are involved: S1: adding sodium allyl sulfonate and long-chain primary amine into a solvent, and adding a base catalyst, mixing them evenly to carry out Michael addition reaction to obtain a product intermediate; S2: uniformly mixing the product intermediate and the quaternary ammonium reagent to carry out a substitution reaction; S3: After the substitution reaction is completed, the reaction is cooled and the pH value is adjusted, and then refluxed to obtain a transparent liquid; S4: distilling the transparent liquid to obtain a viscous substance, drying, washing, filtering and recrystallizing the viscous substance to obtain a disulfonic acid betaine type surfactant.

3. The preparation method according to claim 2, characterized in that: In S1, the molar ratio of the sodium allyl sulfonate to the long-chain primary amine is (2-2.5):

1.

4. The preparation method according to claim 2, characterized in that: In S1, the general structural formula of the long-chain primary amine is as follows: R-NH2 Wherein, R is a C12-18 normal or isomeric alkyl group.

5. The preparation method according to claim 2, characterized in that: In S1, the solvent is one of isopropanol aqueous solution, tetrahydrofuran or 1,4-dioxane; and the base catalyst is one of sodium ethoxide, sodium hydroxide and potassium hydroxide.

6. The preparation method according to claim 2, characterized in that: In S1, the water bath temperature of the Michael addition reaction is 70-85° C., the reaction time of the Michael addition reaction is 3-5 h, and the stirring speed of the Michael addition reaction is 100-300 rpm.

7. The preparation method according to claim 2, characterized in that: In S2, the quaternizing agent is one of sodium chloroacetate, sodium bromoacetate, ethyl chloride, ethyl bromide or sodium 3-chloro-2-hydroxypropane sulfonate.

8. The preparation method according to claim 2, characterized in that: In S2, the molar ratio of the product intermediate to the quaternary ammonium agent is 1:(1-1.5).

9. The preparation method according to claim 2, characterized in that: In S3, the cooling temperature is below 50°C; and the pH value is 8-9.

10. The use of a disulfonic acid betaine viscoelastic surfactant according to claim 1, characterized in that: The disulfonic acid betaine viscoelastic surfactant is used as an oil displacement agent or fracturing fluid in oil reservoir development.

Images