A permeability-enhancing betaine surfactant and its preparation method and application

Abstract

The invention discloses a permeability-enhancing betaine surfactant and a preparation method and application thereof, belonging to the technical field of oil and gas resource exploitation. The preparation method comprises the following steps: adding a long-chain primary amine, allyl polyoxyethylene ether and sodium allyl sulfonate to a solvent, adding an alkali catalyst, mixing them evenly to carry out a Michael addition reaction to obtain a product intermediate; mixing the product intermediate with a quaternary ammonium agent evenly to carry out a substitution reaction; and after the substitution reaction is completed, post-processing is carried out to obtain a permeability-enhancing betaine surfactant. The surfactant has the advantages of being heat-resistant, acid-alkali-resistant, salt-resistant, highly water-soluble, having a low critical micelle concentration, and having a strong ability to reduce interfacial tension. The prepared surfactant structure does not contain an aromatic ring structure, is easy to biodegrade, has good environmental performance, and has a short synthetic process route, a high yield, and the chemical raw materials used are cheap and easy to obtain, and the cost is low. It is a green and environmentally friendly surfactant suitable for chemical oil recovery in high-temperature, high-salt, and high-hardness oil reservoirs.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas resource exploitation, and specifically relates to a permeability-enhancing betaine surfactant and a preparation method and application thereof. Background Art

[0002] For the tertiary oil recovery technology of high-temperature, high-salt and high-hardness reservoirs, the development of chemical oil displacement agents with temperature resistance, salt resistance and calcium and magnesium ion resistance is the key to improving crude oil recovery. The more mature oil displacement technologies in tertiary oil recovery are mainly: alkali / surfactant / polymer (ASP). Polymer displacement has problems of thermal degradation and salt sensitivity, as well as chemical degradation and shear degradation, and viscosity reduction; alkali displacement has the problem that the produced fluid is prone to W / O type emulsion, which has a high viscosity, not only affecting the production capacity of the oil well, but also increasing the difficulty of demulsification. Alkali displacement will also cause scaling of the oil layer and oil well, which has a great impact on production. Anionic surfactants, which are widely used in surfactant displacement, have poor salt tolerance and are easy to combine with calcium and magnesium ions to form precipitation; the composition of the oil displacement agent will change significantly when the composite system is advanced in the formation, which ultimately weakens the oil displacement effect. In the process of exploitation of unconventional oil and gas reservoirs, drilling, self-flowing, water injection and other oil recovery operations are usually used, but after a period of production, the formation pressure decreases and oil can no longer be produced. In fact, only 30% of the original reserves are recovered, and the rest are mostly in the form of small droplets or patches in the delayed gaps. Studies have found that various chemical components such as surfactants are often added during the fracturing process, and surfactants play a great role in improving the imbibition efficiency of oil reservoirs.

[0003] CN106800520A discloses an alkyl amidopropyl betaine surfactant and its preparation. The preparation method of the betaine type amphoteric surfactant comprises the following steps: (1) amidation reaction: natural oil acid and 3-dimethylaminopropylamine are subjected to amidation reaction under the action of a catalyst, and the water generated by the reaction is promptly removed using a 4A molecular sieve to obtain an alkyl amidopropyl dimethyl tertiary amine; (2) quaternization reaction: alkyl amidopropyl dimethyl tertiary amine and sodium chloroacetate are subjected to quaternization reaction in a solvent to obtain a betaine type amphoteric surfactant. However, the amidation acid value is difficult to reduce, resulting in a low yield and high production cost. Moreover, most of the mixed oil acid is used as the production raw material, which contains more impurities, is unstable in nature, and the production raw material price is relatively expensive, resulting in a low content of active substances in the obtained product.

[0004] CN109894050A discloses an aryl ether sulfobetaine surfactant and its preparation, using 2,6-dimethylphenol as a raw material, and synthesizing the aryl ether sulfobetaine surfactant through Williamson etherification reaction, chloromethylation reaction and quaternization reaction. The method of introducing benzene ring in the preparation scheme of CN109894050A has the problems of long synthesis steps, high reactant cost, and low toxicity and difficulty in degradation of aromatic ring compounds. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a penetration-enhancing betaine surfactant and a preparation method and application thereof. The penetration-enhancing betaine surfactant does not contain an aromatic ring structure, is easily biodegradable, and has good environmental performance. The preparation method has good stability, a wide range of cheap raw material sources, mild reaction conditions, a simple preparation process and a single product.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a penetration-enhancing betaine surfactant, the structural formula of the penetration-enhancing betaine surfactant is as follows:

[0008]

[0009] Wherein, R is a normal or isomeric alkyl group of C12 to 18; n is 10 to 50; and X is CH2COONa, CH2CH3 or CHOHCH2COONa.

[0010] The present invention provides a method for preparing the penetration-enhancing betaine surfactant, comprising the following steps:

[0011] S1: adding a long-chain primary amine, allyl polyoxyethylene ether and sodium allyl sulfonate to a solvent, and adding a base catalyst, mixing them evenly to carry out a Michael addition reaction to obtain a product intermediate;

[0012] S2: uniformly mixing the product intermediate and the quaternary ammonium reagent to carry out a substitution reaction;

[0013] S3: After the substitution reaction is completed, distillation, drying, washing, suction filtration and recrystallization are performed to obtain a penetration-enhancing betaine surfactant.

[0014] The present invention further comprises that in S1, the molar ratio of the long-chain primary amine, allyl polyoxyethylene ether and sodium allyl sulfonate is 1:(1-1.5):(1-1.5).

[0015] The present invention further states that in S1, the general structural formula of the long-chain primary amine is as follows:

[0016] R-NH2

[0017] Wherein, R is a C12-18 normal or isomeric alkyl group.

[0018] The present invention further discloses that in S1, the solvent is one of ethanol aqueous solution, tetrahydrofuran, and 1,4-dioxane; and the base catalyst is one of sodium ethoxide, sodium hydroxide, and potassium hydroxide.

[0019] The present invention further comprises that in S1, the water bath temperature of the Michael addition reaction is 75-90° 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.

[0020] The present invention further discloses that in S2, the quaternizing agent is one of sodium chloroacetate, sodium bromoacetate, ethyl chloride, ethyl bromide, and sodium 3-chloro-2-hydroxypropane sulfonate.

[0021] The present invention further comprises that in S2, the molar ratio of the product intermediate to the quaternary ammonium agent is 1:(2-2.5).

[0022] The present invention further comprises that in S2, the temperature of the substitution reaction is 50-80° C., the time of the substitution reaction is 2-5 h, and the stirring speed of the substitution reaction is 300-500 rpm.

[0023] The present invention provides application of the permeability-enhancing betaine surfactant, wherein the permeability-enhancing betaine surfactant is used as a permeability-enhancing agent in the fracturing process of oil and gas resource exploitation.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention provides a permeation-enhancing betaine surfactant, wherein the molecular structure of the permeation-enhancing betaine surfactant simultaneously contains three hydrophilic groups of ethoxy, quaternary ammonium salt group and sulfonic acid group and a hydrophobic hydrocarbon group, and has the dual excellent surface activity of nonionic and negative surfactants. The permeation-enhancing betaine surfactant of the present invention has the advantages of temperature resistance, acid and alkali resistance, salt resistance, strong water solubility, low critical micelle concentration, and strong ability to reduce interfacial tension. The permeation-enhancing betaine surfactant does not contain an aromatic ring structure in the molecule, is easy to biodegrade, has good environmental performance, and has a short synthetic process route, high yield, and the chemical raw materials used are cheap and easy to obtain, and the cost is low. It is a green and environmentally friendly surfactant suitable for chemical oil recovery in high-temperature, high-salt, and high-hardness oil reservoirs.

[0026] The invention provides a preparation method of a permeation-enhancing betaine surfactant, wherein the hydrophilicity and salt resistance of the surfactant are increased by introducing an ethoxy unit; the introduction of a sulfonic acid group increases the high temperature resistance of the molecule, thereby greatly improving the activity of the surfactant, and the surfactant is suitable for a wider range of applications; the product prepared by the Michael addition reaction has a high conversion rate and good stability, and the raw material source is widely inexpensive, the reaction conditions are mild, the preparation process is simple, and the product is single. The obtained surfactant has more hydrophilic groups and lipophilic groups than traditional surfactants, and the product structure combines the common advantages of nonionic and anionic surfactants.

[0027] The penetration-enhancing betaine surfactant of the present invention has many excellent properties and can be applied to the exploitation of high-mineralization oil reservoirs, and plays an important role in tertiary oil recovery. DETAILED DESCRIPTION

[0028] 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.

[0029] 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.

[0030] 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).

[0031] 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.”

[0032] 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.

[0033] The invention provides a permeability-enhancing betaine surfactant and a preparation method and application thereof.

[0034] 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.

[0035] 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.

[0036] The present invention discloses a permeation-enhancing betaine surfactant, the structural formula of which is as follows:

[0037]

[0038] Wherein R is a normal or isomeric alkyl group of C12 to 18, n is 10 to 50, and X is CH2COONa or CH2CH3 or CHOHCH2COONa.

[0039] The synthetic process of the penetration-enhancing betaine surfactant is as follows:

[0040]

[0041] The present invention discloses a method for preparing the penetration-enhancing betaine surfactant, comprising the following steps:

[0042] S1: adding a long-chain primary amine, allyl polyoxyethylene ether and sodium allyl sulfonate to a solvent, and adding a base catalyst, mixing them evenly to carry out a Michael addition reaction to obtain a product intermediate;

[0043] S2: The product intermediate is mixed evenly with the quaternary ammonium reagent to carry out a substitution reaction;

[0044] S3: After the substitution reaction is completed, distillation, drying, washing, suction filtration and recrystallization are performed to obtain a penetration-enhancing betaine surfactant.

[0045] As an optional solution, the molar ratio of the long-chain primary amine, allyl polyoxyethylene ether and sodium allyl sulfonate is 1:(1-1.5):(1-1.5), preferably 1:1:1.

[0046] As an optional solution, the molar ratio of the product intermediate to the quaternary ammonium agent is 1:(2-2.5), preferably 1:2.

[0047] As an optional solution, the water bath temperature of the Michael addition reaction is 75-90° 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.

[0048] More preferably, the temperature is 80 to 90° C., the reaction time is 3 to 4 hours, and the stirring speed is 200 to 300 rpm.

[0049] As an optional solution, the temperature of the substitution reaction is 50-80° C., the time of the substitution reaction is 2-5 h, and the stirring speed of the substitution reaction is 300-500 rpm.

[0050] More preferably, the temperature of the substitution reaction is 50 to 70° C., the reaction time is 3 to 4 hours, and the stirring speed is 350 to 400 rpm.

[0051] As an optional scheme, the distillation is vacuum distillation; the washing is performed 2 to 3 times; petroleum ether is used for washing; the recrystallization is performed 3 to 5 times, and one of acetone, ethanol and methanol is used for purification.

[0052] As an optional solution, the drying is vacuum drying, and the drying temperature is 90-100°C.

[0053] As an optional solution, the solvent is one of ethanol, tetrahydrofuran and 1,4-dioxane.

[0054] As an optional solution, the alkaline catalyst is one of sodium ethoxide, sodium hydroxide and potassium hydroxide.

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

[0056] According to a more specific preferred embodiment, the preparation method of the penetration-enhancing betaine surfactant specifically comprises the following steps:

[0057] In a 250mL three-necked flask equipped with a reflux condenser, a thermometer, and a stirrer, long-chain primary amine, allyl polyoxyethylene ether, and sodium allyl sulfonate were added and mixed evenly, wherein sodium ethoxide was used as a base catalyst and ethanol was used as a solvent, and the reaction was carried out at a reaction temperature of 70-85°C and refluxed for 3-5 hours to obtain a product intermediate, which was then subjected to a substitution reaction with a quaternary ammonium agent.

[0058] After the substitution reaction is completed, ethanol, water and residual primary amine are removed by vacuum distillation; the product is then 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.

[0059] The crude product is recrystallized to obtain a white powdery solid substance - a penetration-enhancing betaine surfactant.

[0060] The invention also discloses the application of the permeability-enhancing betaine surfactant, wherein the permeability-enhancing betaine surfactant is used as a chemical agent in the fracturing process of oil and gas resource exploitation.

[0061] The surfactant prepared by the invention is used as a penetration enhancer in the process of oil and gas resource exploitation.

[0062] Example 1

[0063] (1) Add 0.1 mol of dodecyl primary amine, 0.1 mol of allyl polyoxyethylene ether and 0.1 mol of sodium allyl sulfonate to a 250 mL three-necked flask equipped with a reflux condenser, a thermometer and a stirrer, and mix them evenly. Sodium ethoxide is used as a base catalyst and ethanol is used as a solvent. The reaction is carried out at a reaction temperature of 80° C. and refluxed for 3 hours to obtain a product intermediate. Then, sodium chloroacetate is added in a molar ratio of 1:2, and the reaction is carried out at a reaction temperature of 50° C. and refluxed for 3 hours. After the reaction is completed, ethanol, water and residual primary amine are removed by vacuum distillation.

[0064] (2) The product was dried under vacuum at 90°C until the mass no longer decreased, washed twice with an appropriate amount of petroleum ether, dissolved in anhydrous ethanol, filtered while hot to remove inorganic salt ions, and the filtrate was cooled to obtain a crude product.

[0065] (3) Recrystallize for 4 more times to obtain a white powdery solid substance - a penetration-enhancing betaine surfactant.

[0066] Example 2

[0067] (1) Add 0.1 mol of tetradecyl primary amine, 0.1 mol of allyl polyoxyethylene ether and 0.1 mol of sodium allyl sulfonate to a 250 mL three-necked flask equipped with a reflux condenser, a thermometer and a stirrer, and mix them evenly. Sodium ethoxide is used as a base catalyst and ethanol is used as a solvent. The reaction is carried out at a reaction temperature of 83° C. and reflux for 3.5 hours to obtain a product intermediate. Then, sodium chloroacetate is added in a molar ratio of 1:2, and the reaction is carried out at a reaction temperature of 52° C. and reflux for 3.5 hours. After the reaction is completed, ethanol, water and residual primary amine are removed by reduced pressure distillation.

[0068] (2) The product was dried under vacuum at 92°C until the mass no longer decreased, washed three times with an appropriate amount of petroleum ether, dissolved in anhydrous ethanol, filtered while hot to remove inorganic salt ions, and the filtrate was cooled to obtain a crude product.

[0069] (3) Recrystallize 5 more times to obtain a white powdery solid substance - a penetration-enhancing betaine surfactant.

[0070] Example 3

[0071] (1) Add 0.1 mol of hexadecyl primary amine, 0.1 mol of allyl polyoxyethylene ether and 0.1 mol of sodium allyl sulfonate to a 250 mL three-necked flask equipped with a reflux condenser, a thermometer and a stirrer, and mix them evenly. Sodium ethoxide is used as a base catalyst and ethanol is used as a solvent. The reaction is carried out at a reaction temperature of 84° C. and refluxed for 4 hours to obtain a product intermediate. Then, sodium chloroacetate is added in a molar ratio of 1:2, and the reaction is carried out at a reaction temperature of 55° C. and refluxed for 4 hours. After the reaction is completed, ethanol, water and residual primary amine are removed by vacuum distillation.

[0072] (2) The product was dried under vacuum at 94°C until the mass no longer decreased, washed twice with an appropriate amount of petroleum ether, dissolved in anhydrous ethanol, filtered while hot to remove inorganic salt ions, and the filtrate was cooled to obtain a crude product.

[0073] (3) Recrystallize three more times to obtain a white powdery solid substance - a penetration-enhancing betaine surfactant.

[0074] Example 4

[0075] (1) Add 0.1 mol of octadecyl primary amine, 0.1 mol of allyl polyoxyethylene ether and 0.1 mol of sodium allyl sulfonate to a 250 mL three-necked flask equipped with a reflux condenser, a thermometer and a stirrer, and mix them evenly. Sodium ethoxide is used as a base catalyst and ethanol is used as a solvent. The reaction is carried out at a reaction temperature of 86° C. and refluxed for 4.5 hours to obtain a product intermediate. Then, sodium chloroacetate is added in a molar ratio of 1:2, and the reaction is carried out at a reaction temperature of 56° C. and refluxed for 4.5 hours. After the reaction is completed, ethanol, water and residual primary amine are removed by reduced pressure distillation.

[0076] (2) The product was dried under vacuum at 95°C until the mass no longer decreased, washed three times with an appropriate amount of petroleum ether, dissolved in anhydrous ethanol, filtered while hot to remove inorganic salt ions, and the filtrate was cooled to obtain a crude product.

[0077] (3) Recrystallize for 4 more times to obtain a white powdery solid substance - a penetration-enhancing betaine surfactant.

[0078] Example 5

[0079] (1) Add 0.1 mol of dodecyl primary amine and 0.2 mol of sodium allyl sulfonate to a 250 mL three-necked flask equipped with a reflux condenser, a thermometer, and a stirrer, and mix them evenly. Sodium ethoxide is used as a base catalyst and ethanol is used as a solvent. The reaction is carried out at a reaction temperature of 87° C. and refluxed for 5 hours to obtain a product intermediate. Then, sodium chloroacetate is added at a molar ratio of 1:2, and the reaction is carried out at a reaction temperature of 58° C. and refluxed for 5 hours. After the reaction is completed, ethanol, water, and residual primary amine are removed by vacuum distillation.

[0080] (2) The product was dried under vacuum at 98°C until the mass no longer decreased, washed three times with an appropriate amount of petroleum ether, dissolved in anhydrous ethanol, filtered while hot to remove inorganic salt ions, and the filtrate was cooled to obtain a crude product.

[0081] (3) Recrystallize three more times to obtain a white powdery solid substance - a penetration-enhancing betaine surfactant.

[0082] Example 6

[0083] (1) Add 0.1 mol of dodecyl primary amine and 0.2 mol of allyl polyoxyethylene ether to a 250 mL three-necked flask equipped with a reflux condenser, a thermometer, and a stirrer, and mix them evenly. Sodium ethoxide is used as a base catalyst and ethanol is used as a solvent. The reaction is carried out at a reaction temperature of 89° C. and refluxed for 4 hours to obtain a product intermediate. Then, sodium chloroacetate is added in a molar ratio of 1:2, and the reaction is carried out at a reaction temperature of 59° C. and refluxed for 3 hours. After the reaction is completed, ethanol, water and residual primary amine are removed by reduced pressure distillation.

[0084] (2) The product was dried under vacuum at 100°C until the mass no longer decreased, washed twice with an appropriate amount of petroleum ether, dissolved in anhydrous ethanol, filtered while hot to remove inorganic salt ions, and the filtrate was cooled to obtain a crude product.

[0085] (3) Recrystallize 5 more times to obtain a white powdery solid substance - a penetration-enhancing betaine surfactant.

[0086] In Examples 1 to 4, the permeation-enhancing betaine surfactant reactant was changed to different chain length alkyl primary amines reacted at the same molar ratio; further, in Examples 5 and 6, dodecyl primary amine was reacted with allyl sulfonic acid and allyl polyoxyethylene ether at a molar ratio of 1:2, respectively, and the surface activities of the respective double addition products were studied and compared with those of the products of Examples 1 to 4.

[0087] By comparison, it is found that the increase in the number of ethoxy groups will significantly increase the hydrophilicity of the surfactant, which is conducive to its dissolution in water; in terms of environmental protection, the penetration-enhancing betaine surfactant is synthesized using fatty amines, which have a wide source and are affordable; the penetration-enhancing betaine surfactant contains only one straight-chain alkane, has no benzene ring structure, and is easily biodegradable. The surfactant has low pollution to the environment after use, which meets the current environmental protection requirements.

[0088] Example 7

[0089] (1) 0.1 mol of dodecyl primary amine, 0.15 mol of allyl polyoxyethylene ether and 0.15 mol of sodium allyl sulfonate were added to a 250 mL three-necked flask equipped with a reflux condenser, a thermometer and a stirrer, and the mixture was uniformly mixed, wherein sodium hydroxide was used as a base catalyst and tetrahydrofuran was used as a solvent, and the mixture was reacted at a reaction temperature of 75° C. and refluxed for 5 hours to obtain a product intermediate. Then, sodium chloroacetate was added at a molar ratio of 1:2.5, and the mixture was reacted at a reaction temperature of 50° C. and refluxed for 5 hours. After the reaction was completed, ethanol, water and residual primary amine were removed by vacuum distillation.

[0090] (2) The product was dried under vacuum at 90°C until the mass no longer decreased, washed twice with an appropriate amount of petroleum ether, dissolved in anhydrous ethanol, filtered while hot to remove inorganic salt ions, and the filtrate was cooled to obtain a crude product.

[0091] (3) Recrystallize for 4 more times to obtain a white powdery solid substance - a penetration-enhancing betaine surfactant.

[0092] Example 8

[0093] (1) Add 0.1 mol of tetradecyl primary amine, 0.15 mol of allyl polyoxyethylene ether and 0.15 mol of sodium allyl sulfonate to a 250 mL three-necked flask equipped with a reflux condenser, a thermometer and a stirrer, and mix them evenly. Potassium hydroxide is used as a base catalyst and 1,4-dioxane is used as a solvent. The reaction is carried out at a reaction temperature of 90° C. and refluxed for 3.5 hours to obtain a product intermediate. Then, sodium chloroacetate is added in a molar ratio of 1:2.5, and the reaction is carried out at a reaction temperature of 80° C. and refluxed for 2 hours. After the reaction is completed, ethanol, water and residual primary amine are removed by vacuum distillation.

[0094] (2) The product was dried under vacuum at 92°C until the mass no longer decreased, washed three times with an appropriate amount of petroleum ether, dissolved in anhydrous ethanol, filtered while hot to remove inorganic salt ions, and the filtrate was cooled to obtain a crude product.

[0095] (3) Recrystallize 5 more times to obtain a white powdery solid substance - a penetration-enhancing betaine surfactant.

[0096] Example 9

[0097] (1) Add 0.1 mol hexadecyl primary amine, 0.15 mol allyl polyoxyethylene ether and 0.15 mol sodium allyl sulfonate to a 250 mL three-necked flask equipped with a reflux condenser, a thermometer and a stirrer, and mix them evenly. Sodium ethoxide is used as a base catalyst and ethanol is used as a solvent. The reaction is carried out at a reaction temperature of 90° C. and refluxed for 5 hours to obtain a product intermediate. Then, sodium chloroacetate is added in a molar ratio of 1:2, and the reaction is carried out at a reaction temperature of 55° C. and refluxed for 5 hours. After the reaction is completed, ethanol, water and residual primary amine are removed by vacuum distillation.

[0098] (2) The product was dried under vacuum at 94°C until the mass no longer decreased, washed twice with an appropriate amount of petroleum ether, dissolved in anhydrous ethanol, filtered while hot to remove inorganic salt ions, and the filtrate was cooled to obtain a crude product.

[0099] (3) Recrystallize three more times to obtain a white powdery solid substance - a penetration-enhancing betaine surfactant.

[0100] The penetration-enhancing betaine surfactant of the present invention contains sulfonic acid groups and can show good performance in high temperature, high mineralization, strong acidity and alkalinity extreme environments, so it has broad application prospects in tertiary oil recovery and washing industries.

[0101] test

[0102] The H NMR spectrum data of a permeability-enhancing betaine surfactant obtained in Example 1 are shown below:

[0103] 1H NMR (300MHz, DMSO): δ4.18 (s, 2H), 4.18 (s, 2H), 3.54 (t, 4H), 3.37-3.41 (m, 4H), 3.24 (t, 6H), 2.29 (m, 2H), 1.90 (m, 2H), 1.73 (m, 2H), 1.29-13.3 (m, 20H), 0.96 (t, 3H)ppm.

[0104] It can be seen from the hydrogen nuclear magnetic spectrum that the penetration-enhancing betaine surfactant of the present invention contains a sulfonic acid group and a polyoxyethylene ether structure.

[0105] Performance Characterization

[0106] In order to characterize the effect of the concentration of the permeability-enhancing betaine surfactant on the self-imbibition height, the self-imbibition height of the permeability-enhancing betaine surfactant of different concentrations synthesized in Example 1 was tested. The results showed that when the configuration concentration of the permeability-enhancing betaine surfactant was 0.1%, the self-imbibition height was 23 mm, and when the concentration was 0.3%, the self-imbibition height was 26 mm. In summary, as the configuration concentration of the surfactant increases, the self-imbibition height of the surfactant increases.

[0107] In order to characterize the various properties of the permeability-enhancing betaine surfactant, the water solubility, surface tension, interfacial tension, wetting properties, self-imbibition ability, oil washing efficiency and core permeability of the permeability-enhancing betaine surfactant synthesized in Examples 1 to 6 were tested. The results are shown in Table 1.

[0108] As can be seen from Table 1, the permeability-enhancing betaine surfactant of the present invention improves its hydrophilic-lipophilic balance by adjusting the molecular structure, obtains high water solubility, and avoids the situation that the surfactant is insoluble in high-mineralization water or the surfactant solution undergoes phase separation. The ethoxy chain is embedded in the molecular structure, making it more water-soluble. The solubility of the permeability-enhancing betaine surfactant is increased by more than 10 times compared with ordinary surfactants.

[0109] As shown in Table 1, the surface tension of the surfactant increases with the proportion of embedded ethoxy groups in the penetration-enhancing betaine surfactant of the present invention, because the ethoxy groups increase the lipophilicity of the molecule. However, the overall surface tension of the present invention is small and the surface activity is good.

[0110] The permeability-enhancing betaine surfactant of the present invention has a low interfacial tension and can play a wetting role. The molecules of the permeability-enhancing betaine surfactant interact with the surface components of the sandstone and are adsorbed at the solid / liquid interface, causing a significant change in the wettability of the rock surface, from oil wetting to water wetting, thereby facilitating the stripping of crude oil, significantly improving the recovery rate, and having a certain oil washing function.

[0111] The test reference standards are:

[0112] Water solubility: Determination of water solubility of surfactants according to GB / T 11275-2007 (Use UV-visible spectrophotometer to measure the transmittance T (%) of surfactant aqueous solution at visible light wavelength (600nm), and measure the change of transmittance of aqueous solutions of different concentrations at visible light wavelength (600nm) with concentration);

[0113] Surface tension refers to GB / T 22237-2008 Determination of surface tension of surfactants (hanging ring method);

[0114] The interfacial tension refers to GB / T 38722-2020 Determination of interfacial tension of surfactants (pulling liquid film method);

[0115] The wettability test refers to GB / T 11983-2008 Determination of the wetting power of surfactants (immersion method);

[0116] The self-priming capacity refers to JB / T 6664.3-2004 Self-priming Pump Part 3: Self-priming Performance Test Method;

[0117] The oil washing efficiency refers to GB / T 24217-2009 oil washing;

[0118] The core permeability refers to SY / T5802-1993 dense rock permeability determination method (steady-state method).

[0119] Table 1 Performance of permeability-enhancing betaine surfactants

[0120]

[0121]

[0122] As shown in Table 1, the permeability-enhancing betaine surfactant adopts normal long-chain primary amine as a reactant, which not only reduces the cost loss of the product, but also has good non-toxic degradation performance of the reaction product; by introducing an oxyethyl unit, the hydrophilicity and salt resistance of the surfactant are increased, and the introduction of a sulfonic acid unit increases the high temperature resistance of the molecule, so that the activity of the surfactant is greatly improved, and it has the advantages of good water solubility, small surface tension, low interfacial tension, good wetting performance, strong self-absorption ability, high oil washing efficiency, high core permeability, etc.

[0123] 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 penetration-enhancing betaine surfactant, It is characterized in that The structural formula of the penetration-enhancing betaine surfactant is as follows: Wherein, R is a C12-18 normal or isomeric alkyl group; n is 10-50; X is CH 2 COONa, CH 2 CH 3 or CHOHCH 2 COONa.

2. A method for preparing the penetration-enhancing betaine surfactant according to claim 1, It is characterized in that The following steps are involved: S1: adding a long-chain primary amine, allyl polyoxyethylene ether and sodium allyl sulfonate to a solvent, and adding a base catalyst, mixing them evenly to carry out a 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, distillation, drying, washing, suction filtration and recrystallization are performed to obtain a penetration-enhancing betaine surfactant.

3. The preparation method of the penetration-enhancing betaine surfactant according to claim 2, It is characterized in that In S1, the molar ratio of the long-chain primary amine, allyl polyoxyethylene ether and sodium allyl sulfonate is 1:(1-1.5):(1-1.5).

4. The method for preparing the penetration-enhancing betaine surfactant according to claim 2, It is characterized in that In S1, the general structural formula of the long-chain primary amine is as follows: R-NH 2 Wherein, R is a C12-18 normal or isomeric alkyl group.

5. The method for preparing the penetration-enhancing betaine surfactant according to claim 2, It is characterized in that In S1, the solvent is one of ethanol aqueous solution, tetrahydrofuran, and 1,4-dioxane; and the base catalyst is one of sodium ethoxide, sodium hydroxide, and potassium hydroxide.

6. The method for preparing the penetration-enhancing betaine surfactant according to claim 2, It is characterized in that In S1, the water bath temperature of the Michael addition reaction is 75-90° 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 method for preparing the penetration-enhancing betaine surfactant according to claim 2, It is characterized in that In S2, the quaternizing agent is one of sodium chloroacetate, sodium bromoacetate, ethyl chloride, ethyl bromide, and sodium 3-chloro-2-hydroxypropane sulfonate.

8. The method for preparing the penetration-enhancing betaine surfactant according to claim 2, It is characterized in that In S2, the molar ratio of the product intermediate to the quaternary ammonium agent is 1:(2-2.5).

9. The method for preparing the penetration-enhancing betaine surfactant according to claim 2, It is characterized in that In S2, the temperature of the substitution reaction is 50-80°C, the time of the substitution reaction is 2-5 hours, and the stirring speed of the substitution reaction is 300-500 rpm.

10. Use of a penetration-enhancing betaine surfactant according to claim 1, It is characterized in that The permeability-enhancing betaine surfactant is used as a permeability-enhancing agent in the fracturing process of oil and gas resource exploitation.

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