Anionic-nonionic gemini surfactant, its preparation method and application

Abstract

The application discloses an anionic-nonionic gemini surfactant and a preparation method and application thereof. The preparation method comprises the following steps: (1) under the atmosphere of nitrogen or inert gas, a first contact reaction is carried out between 1,2-epoxy long-chain hydrocarbon and diol in the presence of a catalyst, and after the reaction is completed, an intermediate product A is obtained through reduced pressure distillation; (2) under vacuum conditions, in the presence of an alkaline substance, the intermediate product A is first subjected to a first / second polymerization reaction with propylene oxide / ethylene oxide in a high-pressure reaction container, and then subjected to a second / first polymerization reaction with ethylene oxide / propylene oxide to obtain an intermediate product B / intermediate product B'; (3) in the presence of a mixed solvent, the intermediate product B / intermediate product B' is first subjected to a first contact reaction with sodium hydroxide or potassium hydroxide, and then subjected to a second contact reaction with chloroacetic acid, and the anionic-nonionic gemini surfactant is obtained after the reaction is completed.

Description

Technical Field

[0001] This invention belongs to the field of petrochemicals, specifically relating to an anionic nonionic gemini surfactant, its preparation method, and its application. Background Technology

[0002] Currently, the low-permeability reservoirs in Shengli Oilfield have an recovery rate of <15% and an oil production rate of ≤0.42%, placing them in a low-recovery, low-oil-production-rate, and medium-to-high water-cut development stage. This is a key area for water-drive quality improvement and efficiency enhancement. Most of the low-permeability reservoirs in Shengli Oilfield are currently characterized by low permeability, high temperature, high salinity, and low porosity.

[0003] Surfactants possess excellent interfacial activity and emulsifying properties, enabling capillary force control, efficient oil-water replacement, improved seepage, and increased water injection utilization. They address the problem of strong oil / solid interface interactions in water injection development, which hinders crude oil stripping and displacement in reservoirs, thereby improving the overall development effect of the reservoir.

[0004] Currently, indoor research and field tests generally use anionic surfactants, anionic-nonionic surfactants, and compound systems of anionic surfactants and alcohols for displacement experiments, which have achieved significant oil displacement effects and are promising methods to solve the problem of inefficient waterflooding in low-permeability reservoirs.

[0005] Currently, conventional anionic surfactants offer good interfacial properties, lack cloud point, exhibit low adsorption on sandstone surfaces, are inexpensive, and come in a wide variety. However, they suffer from poor temperature and salt resistance, failing to meet the requirements of high-temperature, high-salt, low-permeability reservoirs. Cationic surfactants readily release amines under alkaline conditions, losing their surface activity. While they do have high adsorption on sandstone surfaces, they are relatively expensive and less economical. Nonionic surfactants provide good oil washing effects but exhibit cloud point and poor temperature resistance.

[0006] Gemini surfactants possess advantages such as temperature and salt resistance, and the ability to reduce chromatographic separation effects, making them a promising class of surfactants. However, they are expensive, have limited variety, and are relatively uncommon in oilfield applications.

[0007] Chinese invention patent CN109652048B discloses a composite oil displacement agent, its preparation method, and its application. The composite oil displacement agent comprises a symmetrical alkyl alcohol polyoxyethylene ether sulfonate anionic-non-gemini surfactant, a cationic surfactant, and the balance being water; the molar ratio of the symmetrical alkyl alcohol polyoxyethylene ether sulfonate anionic-non-gemini surfactant to the cationic surfactant is 1:2 to 1:4.

[0008] Chinese invention patent application CN 112226223A relates to a surfactant composition and preparation method for depressurization and injection enhancement in ultra-low permeability reservoirs. It mainly addresses the problems of high concentration, narrow concentration window, slow emulsification rate, low depressurization rate, and poor oil displacement efficiency of surfactants used in existing low-permeability reservoir depressurization and injection enhancement technologies. The method primarily employs a surfactant composition comprising an anionic-non-gemini surfactant and a cationic surfactant, wherein the molar ratio of the anionic-non-gemini surfactant to the cationic surfactant is 1:(0.02~60); wherein the cationic surfactant is selected from quaternary ammonium salts or quaternary ammonium bases. The anionic linker of the anionic-non-gemini surfactant is a group containing a benzene ring and lacks a long hydrophobic carbon chain.

[0009] The doctoral dissertation of Luan Hexin from Northeast Petroleum University, entitled "Synthesis and Performance Study of Anionic and Nonionic Gemini Surfactants," reported the synthesis of a series of anionic and nonionic Gemini surfactants using maleic anhydride, fatty alcohol polyoxyethylene ethers (AEO-3, AEO-5, AEO-7), 1,2-ethylene glycol, 1,3-propanediol, 1,4-butanediol, and sodium bisulfite as raw materials and a self-made carbon-based solid acid as a catalyst. The foaming, detergency, adsorption, and oil displacement properties were evaluated. The master's thesis of Tang Yanli from Southwest Petroleum University, entitled "Synthesis and Oil Displacement Performance Evaluation of Anionic and Nonionic Surfactants," reported the synthesis of highly active anionic and nonionic gemini surfactants using alkylphenol polyoxyethylene ethers as raw materials. The critical micelle concentration, oil-water interface properties, temperature and salt resistance, and adsorption properties of the anionic and nonionic gemini surfactants were investigated.

[0010] For the low-permeability reservoirs in the Shengli Oilfield, existing surfactants have the following shortcomings:

[0011] 1. Due to the complexity of oil reservoirs with low permeability, high temperature, high salt and low porosity, new demands are placed on current oil displacement surfactant systems.

[0012] 2. Conventional anionic surfactants have good interfacial properties, no cloud point, low adsorption on sandstone surfaces, low price, and many types. However, they have the disadvantage of poor temperature and salt resistance, which cannot meet the needs of high-temperature, high-salt, and low-permeability reservoirs in Shengli Oilfield.

[0013] 3. Conventional cationic surfactants are prone to precipitating amines under alkaline conditions, losing their surface activity. Moreover, they have a large adsorption capacity on sandstone surfaces, are relatively expensive, and have poor economic efficiency, which cannot meet the needs of high-temperature, high-salinity, and low-permeability reservoirs in Shengli Oilfield.

[0014] 4. Conventional nonionic surfactants have good oil washing effects, but they have cloud points and poor temperature resistance, which cannot meet the needs of high-temperature, high-salinity, and low-permeability reservoirs in Shengli Oilfield. Summary of the Invention

[0015] Purpose of the invention: The present invention addresses the problems existing in the prior art by disclosing an anionic nonionic gemini surfactant, its preparation method, and its application.

[0016] Technical solution: An anionic nonionic gemini surfactant, the structural formula of which is as follows:

[0017] in:

[0018] M is either Na or K;

[0019] R is a C8-C18 long-chain alkyl or C8-C18 long-chain olefin;

[0020] EO stands for ethylene oxide block, m is an integer, and 1≤m≤30, preferably 10≤m≤30;

[0021] PO is a propylene oxide block, n is an integer, and 1≤n≤30, preferably 10≤n≤30;

[0022] x is a positive integer, and 2≤x≤10, preferably 2≤x≤6.

[0023] A method for preparing anionic nonionic gemini surfactants includes the following steps:

[0024] (1) Under a nitrogen or inert gas atmosphere and in the presence of a catalyst, 1,2-epoxy long-chain hydrocarbons and diols undergo a first contact reaction. After the reaction is completed, intermediate product A is obtained by vacuum distillation.

[0025] (2) Under vacuum conditions and in the presence of alkaline substances, intermediate product A is first reacted with propylene oxide / ethylene oxide in a high-pressure reaction vessel to complete the first / second polymerization reaction, and then reacted with ethylene oxide / propylene oxide to complete the second / first polymerization reaction to obtain intermediate product B / intermediate product B'.

[0026] (3) In the presence of a mixed solvent, the intermediate product B / intermediate product B' first undergoes a first contact reaction with sodium hydroxide or potassium hydroxide, and then undergoes a second contact reaction with chloroacetic acid. After the reaction is completed, an anionic nonionic gemini surfactant is obtained.

[0027] Anionic nonionic gemini surfactants are prepared by any one of the methods described above.

[0028] The above-mentioned anionic nonionic gemini surfactants are used as oil displacement agents in low-permeability, high-temperature, and high-salinity oil reservoirs.

[0029] The anionic nonionic gemini surfactant of the present invention introduces both PO polyether groups (CH2CH2CH2O) and EO polyether groups (CH2CH2O), and arranges the long hydrophobic carbon chain polyether groups and the PO and EO polyether groups on both sides of the linking group, thereby increasing the distribution area of ​​surfactant molecules at the oil-water interface. The larger the distribution area at the oil-water interface, the faster and more stable the oil-water interfacial tension decreases.

[0030] Beneficial Effects: The anionic nonionic gemini surfactant disclosed in this invention, its preparation method, and its application have the following beneficial effects:

[0031] The anionic-nonionic gemini surfactant of the present invention possesses the strong oil-washing, salt-resistant and salt-tolerant properties of anionic-nonionic surfactants, while also having the low critical micelle concentration and complex rheological properties of gemini surfactants, thus meeting the requirements for oil displacement in low-permeability, high-temperature and high-salt reservoirs. Attached Figure Description

[0032] Figure 1 The infrared spectrum of intermediate product B prepared in Example 1.

[0033] Figure 2 The infrared spectrum of the anionic nonionic gemini surfactant prepared in Example 1.

[0034] Figure 3 The infrared spectrum of the anionic nonionic gemini surfactant prepared in Example 4. Detailed Implementation

[0035] The specific embodiments of the present invention are described in detail below.

[0036] The "range" disclosed in this invention is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 10–50 is listed for a specific parameter, it is also expected that ranges of 10–40 and 20–50 are also included. Furthermore, if the minimum range values ​​are 1 and 2, and the maximum range values ​​are 3, 4, and 5, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0–5" means that all real numbers between "0–5" have been listed herein; "0–5" is merely a shortened representation of these numerical combinations.

[0037] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0038] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0039] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0040] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0041] Unless otherwise specified, the reaction will proceed under normal temperature and pressure conditions.

[0042] Unless otherwise specified, all parts or percentages are by weight or by weight percentage.

[0043] In this invention, all the substances used are known substances that can be purchased or synthesized by known methods.

[0044] In this invention, all the devices or equipment used are conventional devices or equipment known in the art and are readily available.

[0045] Synthetic method: This invention first reacts a 1,2-epoxy long-chain hydrocarbon with a diol to generate intermediate A. Then, intermediate A is sequentially reacted with propylene oxide and ethylene oxide to generate intermediate B. Finally, intermediate B reacts with sodium hydroxide or potassium hydroxide and chloroacetic acid to generate anionic nonionic gemini surfactants. The synthetic route is as follows:

[0046] 1,2-Epoxy long-chain hydrocarbon + diol → intermediate product A;

[0047] Intermediate product A + propylene oxide + ethylene oxide → intermediate product B;

[0048] Intermediate product B + sodium / potassium hydroxide + chloroacetic acid → anionic nonionic gemini surfactant.

[0049]

[0050] or:

[0051] This invention involves the reaction of a 1,2-epoxy long-chain hydrocarbon and a diol to generate intermediate A. Intermediate A is then reacted sequentially with ethylene oxide and propylene oxide to generate intermediate B'. Finally, intermediate B' reacts with sodium hydroxide or potassium hydroxide and chloroacetic acid to generate anionic nonionic gemini surfactants. The synthetic route is as follows:

[0052] 1,2-Epoxy long-chain hydrocarbon + diol → intermediate product A;

[0053] Intermediate product A + ethylene oxide + propylene oxide → intermediate product B';

[0054] Intermediate product B' + sodium / potassium hydroxide + chloroacetic acid → anionic nonionic gemini surfactant.

[0055]

[0056] An anionic nonionic gemini surfactant has the following structural formula:

[0057] in:

[0058] M is either Na or K;

[0059] R is a C8-C18 long-chain alkyl or C8-C18 long-chain olefin;

[0060] EO stands for ethylene oxide block, m is an integer, and 1≤m≤30, preferably 10≤m≤30;

[0061] PO is a propylene oxide block, n is an integer, and 1≤n≤30, preferably 10≤n≤30;

[0062] x is a positive integer, and 2≤x≤10, preferably 2≤x≤6.

[0063] A method for preparing anionic nonionic gemini surfactants includes the following steps:

[0064] (1) Under a nitrogen or inert gas atmosphere and in the presence of a catalyst, 1,2-epoxy long-chain hydrocarbons and diols undergo a first contact reaction. After the reaction is completed, intermediate product A is obtained by vacuum distillation.

[0065] (2) Under vacuum conditions and in the presence of alkaline substances, intermediate product A is first reacted with propylene oxide / ethylene oxide in a high-pressure reaction vessel to complete the first / second polymerization reaction, and then reacted with ethylene oxide / propylene oxide to complete the second / first polymerization reaction to obtain intermediate product B / intermediate product B'.

[0066] (3) In the presence of a mixed solvent, the intermediate product B / intermediate product B' first undergoes a first contact reaction with sodium hydroxide or potassium hydroxide, and then undergoes a second contact reaction with chloroacetic acid. After the reaction is completed, an anionic nonionic gemini surfactant is obtained.

[0067] Further, the diol mentioned in step (1) is OH-R'-OH, wherein: R' is a alkyl group with 2-10 carbon atoms, preferably one or more of 1,2-ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol.

[0068] Further, the catalyst mentioned in step (1) is one of potassium, sodium, sodium hydride, sodium methoxide, and / or

[0069] In molar terms, the amount of catalyst added in step (1) is 0.5%-10% of the amount of the diol, preferably 0.5%-5%.

[0070] Further, the 1,2-epoxy long-chain hydrocarbon mentioned in step (1) is a C8-C18 1,2-epoxy long-chain alkane or a C8-C18 1,2-epoxy long-chain olefin, and / or

[0071] The molar ratio of the diol to the 1,2-epoxy long-chain hydrocarbon mentioned in step (1) is 1:(2-4).

[0072] Furthermore, in step (1), the reaction temperature of the first contact reaction is at least 60°C, preferably 60-90°C, and the reaction time is at least 2 hours, preferably 2-8 hours.

[0073] Furthermore, the alkaline substance mentioned in step (2) is one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, and ammonia water, and / or

[0074] The molar ratio of the diol in step (1) to the alkaline substance in step (2) is 1:(0.05-0.2).

[0075] Further, the molar ratio of the diol in step (1) to the propylene oxide and ethylene oxide in step (2) is 1:(2-60):(2-60).

[0076] Furthermore, the reaction temperature of the first polymerization reaction in step (2) is at least 110°C, preferably 110°C-150°C, and the reaction time of the first polymerization reaction in step (2) is at least 10 hours, preferably 10-40 hours.

[0077] Furthermore, the reaction temperature of the second polymerization reaction in step (2) is at least 110°C, preferably 110°C-150°C, and the reaction time of the second polymerization reaction in step (2) is at least 10 hours, preferably 10-20 hours.

[0078] Further, the mixed solvent mentioned in step (3) is a mixture of organic solvent and water, with water accounting for 30%-70% based on the total molar amount of the mixed solvent, and the remainder being organic solvent, and / or

[0079] The organic solvent is one or more of methanol, ethanol, isopropanol, n-propanol, n-butanol, isobutanol, and isoamyl alcohol, and / or

[0080] In molar terms, the amount of the mixed solvent used in step (3) is 10-30 times that of the diol used in step (1).

[0081] Further, the molar ratio of the diol in step (1) to sodium hydroxide or potassium hydroxide and chloroacetic acid in step (3) is 1:(2-3):(3-4).

[0082] Furthermore, the first contact reaction in step (3) is carried out at room temperature, and the reaction time of the first contact reaction in step (3) is at least 2 hours, preferably 2-4 hours.

[0083] Furthermore, in step (3), the reaction temperature of the second contact reaction is at least 60°C, preferably 60°C-110°C, and the reaction time of the second contact reaction in step (3) is at least 4 hours, preferably 4-8 hours.

[0084] Further, in molars, the following steps are included:

[0085] (A) Place a dry reactor (such as a four-necked flask) in a water bath or oil bath, continuously introduce nitrogen or inert gas into the reactor, add 1 part of diol and 0.005-0.1 part of catalyst to the reactor, take 2-4 parts of 1,2-epoxy long-chain hydrocarbon, and slowly add them dropwise to the reactor through a dropping funnel. After the addition is complete, raise the temperature to at least 60°C, preferably 60-90°C, react for 2 hours, preferably 2-8 hours, distill under reduced pressure, and take the residue to obtain intermediate product A;

[0086] (B) Add the intermediate product A obtained in step (A) into a high-pressure reactor, add 0.05 to 0.2 parts of alkaline substance, then evacuate and remove air, heat to at least 110°C, preferably 110°C-150°C, stir, slowly add 2-60 parts of propylene oxide / ethylene oxide and react for 10-40 hours / 10-20 hours, keep the reaction temperature constant, then add 2-60 parts of ethylene oxide / propylene oxide and react for 10-20 hours / 10-40 hours to obtain intermediate product B / B';

[0087] (C) Add 10-30 parts of mixed solvent to a high-pressure reactor, then add 2-3 parts of sodium hydroxide or potassium hydroxide, react at room temperature for at least 2 hours, preferably 2-4 hours, then add 3-4 parts of chloroacetic acid, heat to at least 60°C, preferably 60°C-110°C, stir and react for at least 4 hours, preferably 4-8 hours, and after the reaction is complete, an anionic nonionic gemini surfactant is obtained.

[0088] Anionic nonionic gemini surfactants are prepared by any one of the methods described above.

[0089] The above-mentioned anionic nonionic gemini surfactants are used as oil displacement agents in low-permeability, high-temperature, and high-salinity oil reservoirs.

[0090] In one embodiment:

[0091] An anionic nonionic gemini surfactant has the following structural formula:

[0092] in:

[0093] M is Na;

[0094] R is a C8 long-chain alkyl group;

[0095] EO stands for ethylene oxide block, m is an integer, and m = 1;

[0096] PO represents a propylene oxide block, n is an integer, and n = 30;

[0097] x is a positive integer, and x = 2.

[0098] A method for preparing anionic nonionic gemini surfactants includes the following steps:

[0099] (1) Under a nitrogen atmosphere and in the presence of a catalyst, 1,2-epoxy long-chain hydrocarbons and diols undergo a first contact reaction. After the reaction is completed, intermediate product A is obtained by vacuum distillation.

[0100] (2) Under vacuum conditions and in the presence of alkaline substances, intermediate product A is first polymerized with propylene oxide in a high-pressure reaction vessel, and then polymerized with ethylene oxide to obtain intermediate product B.

[0101] (3) In the presence of a mixed solvent, the intermediate product B first undergoes a first contact reaction with sodium hydroxide, and then undergoes a second contact reaction with chloroacetic acid. After the reaction is completed, an anionic nonionic gemini surfactant is obtained.

[0102] Further, the diol mentioned in step (1) is 1,2-ethylene glycol.

[0103] Further, the catalyst described in step (1) is sodium, and / or

[0104] In molar terms, the amount of catalyst added in step (1) is 0.5% of the amount of the diol used.

[0105] Further, the 1,2-epoxy long-chain hydrocarbon mentioned in step (1) is a C8 1,2-epoxy long-chain alkane, and / or

[0106] The molar ratio of the diol to the 1,2-epoxy long-chain hydrocarbon mentioned in step (1) is 1:2.

[0107] Furthermore, in step (1), the reaction temperature of the first contact reaction is 60°C and the reaction time is 8 hours.

[0108] Further, the alkaline substance mentioned in step (2) is sodium hydroxide, and / or

[0109] The molar ratio of the diol in step (1) to the alkaline substance in step (2) is 1:0.05.

[0110] Furthermore, the molar ratio of the diol in step (1) to the propylene oxide and ethylene oxide in step (2) is 1:60:2.

[0111] Furthermore, the reaction temperature of the first polymerization reaction in step (2) is 110°C, and the reaction time of the first polymerization reaction in step (2) is 40 hours.

[0112] Furthermore, the reaction temperature of the second polymerization reaction in step (2) is 110°C, and the reaction time of the second polymerization reaction in step (2) is 20 hours.

[0113] Further, the mixed solvent mentioned in step (3) is a mixture of organic solvent and water, with water accounting for 30% based on the total molar amount of the mixed solvent, and the remainder being organic solvent, and / or

[0114] The organic solvent is methanol, and / or

[0115] In molar terms, the amount of the mixed solvent used in step (3) is 10 times that of the diol used in step (1).

[0116] Furthermore, the molar ratio of the diol in step (1) to the sodium hydroxide and chloroacetic acid in step (3) is 1:2:3.

[0117] Furthermore, the first contact reaction in step (3) is carried out at room temperature, and the reaction time of the first contact reaction in step (3) is 2 hours.

[0118] Furthermore, the reaction temperature of the second contact reaction in step (3) is 60°C, and the reaction time of the second contact reaction in step (3) is 8 hours.

[0119] In another embodiment, a method for preparing an anionic nonionic gemini surfactant, on a molar basis, includes the following steps:

[0120] (A) Place a dry reactor (such as a four-necked flask) in a water bath and continuously introduce nitrogen gas into the reactor. Add 1 part of diol and 0.005 parts of catalyst to the reactor. Take 2 parts of 1,2-epoxy long-chain hydrocarbon and slowly add them dropwise to the reactor through a dropping funnel. After the addition is complete, raise the temperature to 60°C and react for 8 hours. Distill under reduced pressure and take the residue to obtain intermediate product A.

[0121] (B) Add the intermediate product A obtained in step (A) into a high-pressure reactor, add 0.05 parts of alkaline substance, then evacuate and remove air, heat to 110°C, stir, slowly add 60 parts of propylene oxide and react for 40 hours, keep the reaction temperature constant, then add 2 parts of ethylene oxide and react for 20 hours to obtain intermediate product B.

[0122] (C) Add 10 parts of mixed solvent to a high-pressure reactor, then add 2 parts of sodium hydroxide, react at room temperature for 2 hours, then add 3 parts of chloroacetic acid, heat to 60°C, stir and react for 8 hours, and the anionic nonionic gemini surfactant is obtained after the reaction is completed.

[0123] Anionic nonionic gemini surfactants are prepared by any one of the methods described above.

[0124] The above-mentioned anionic nonionic gemini surfactants are used as oil displacement agents in low-permeability, high-temperature, and high-salinity oil reservoirs.

[0125] In another embodiment:

[0126] An anionic nonionic gemini surfactant has the following structural formula:

[0127] in:

[0128] M is K;

[0129] R is a C18 long-chain alkyl group;

[0130] EO stands for ethylene oxide block, m is an integer, and m = 30;

[0131] PO represents a propylene oxide block, n is an integer, and n = 1;

[0132] x is a positive integer, and x = 10.

[0133] A method for preparing anionic nonionic gemini surfactants includes the following steps:

[0134] (1) Under an argon atmosphere and in the presence of a catalyst, 1,2-epoxy long-chain hydrocarbons and diols undergo a first contact reaction. After the reaction is completed, intermediate product A is obtained by vacuum distillation.

[0135] (2) Under vacuum conditions and in the presence of alkaline substances, intermediate product A is first polymerized with propylene oxide in a high-pressure reaction vessel, and then polymerized with ethylene oxide to obtain intermediate product B.

[0136] (3) In the presence of a mixed solvent, the intermediate product B first undergoes a first contact reaction with potassium hydroxide, and then undergoes a second contact reaction with chloroacetic acid. After the reaction is completed, an anionic nonionic gemini surfactant is obtained.

[0137] Further, the diol mentioned in step (1) is OH-R'-OH, wherein: R' is a 10-carbon alkyl group.

[0138] Further, the catalyst described in step (1) is potassium, and / or

[0139] In molar terms, the amount of catalyst added in step (1) is 10% of the amount of the diol used.

[0140] Further, the 1,2-epoxy long-chain hydrocarbon mentioned in step (1) is a C18 1,2-epoxy long-chain alkane, and / or

[0141] The molar ratio of the diol to the 1,2-epoxy long-chain hydrocarbon mentioned in step (1) is 1:4.

[0142] Furthermore, in step (1), the reaction temperature of the first contact reaction is 90°C and the reaction time is 2 hours.

[0143] Further, the alkaline substance mentioned in step (2) is potassium hydroxide, and / or

[0144] The molar ratio of the diol in step (1) to the alkaline substance in step (2) is 1:0.2.

[0145] Furthermore, the molar ratio of the diol in step (1) to the propylene oxide and ethylene oxide in step (2) is 1:2:60.

[0146] Furthermore, the reaction temperature of the first polymerization reaction in step (2) is 150°C, and the reaction time of the first polymerization reaction in step (2) is 10 hours.

[0147] Furthermore, the reaction temperature of the second polymerization reaction in step (2) is 150°C, and the reaction time of the second polymerization reaction in step (2) is 10 hours.

[0148] Further, the mixed solvent mentioned in step (3) is a mixture of organic solvent and water, with water accounting for 70% based on the total molar amount of the mixed solvent, and the remainder being organic solvent, and / or

[0149] The organic solvent is ethanol, and / or

[0150] In molar terms, the amount of the mixed solvent used in step (3) is 30 times that of the diol used in step (1).

[0151] Furthermore, the molar ratio of the diol in step (1) to the potassium hydroxide and chloroacetic acid in step (3) is 1:3:4.

[0152] Furthermore, the first contact reaction in step (3) is carried out at room temperature, and the reaction time of the first contact reaction in step (3) is 4 hours.

[0153] Furthermore, the reaction temperature of the second contact reaction in step (3) is 110°C, and the reaction time of the second contact reaction in step (3) is 4 hours.

[0154] In other embodiments, a method for preparing an anionic nonionic gemini surfactant, on a molar basis, includes the following steps:

[0155] (A) Place a dry reactor (such as a four-necked flask) in an oil bath and continuously introduce helium gas into the reactor. Add 1 part of diol and 0.1 part of catalyst to the reactor. Take 4 parts of 1,2-epoxy long-chain hydrocarbon and slowly add them dropwise to the reactor through a dropping funnel. After the addition is complete, raise the temperature to 90°C and react for 8 hours. Distill under reduced pressure and take the residue to obtain intermediate product A.

[0156] (B) Add the intermediate product A obtained in step (A) into a high-pressure reactor, add 0.2 parts of alkaline substance, then evacuate and remove air, heat to 150°C, stir, slowly add 2 parts of propylene oxide and react for 10 hours, keep the reaction temperature constant, then add 60 parts of ethylene oxide and react for 10 hours to obtain intermediate product B.

[0157] (C) Add 30 parts of mixed solvent to a high-pressure reactor, then add 3 parts of potassium hydroxide, react at room temperature for 4 hours, then add 4 parts of chloroacetic acid, heat to 110°C, stir and react for 4 hours, and the anionic nonionic gemini surfactant is obtained after the reaction is completed.

[0158] Anionic nonionic gemini surfactants are prepared by any one of the methods described above.

[0159] The above-mentioned anionic nonionic gemini surfactants are used as oil displacement agents in low-permeability, high-temperature, and high-salinity oil reservoirs.

[0160] In yet another embodiment:

[0161] An anionic nonionic gemini surfactant has the following structural formula:

[0162] in:

[0163] M is Na;

[0164] R is a C10 long-chain olefin;

[0165] EO stands for ethylene oxide block, m is an integer, and m = 10;

[0166] PO represents a propylene oxide block, n is an integer, and n = 10;

[0167] x is a positive integer, and x = 6.

[0168] A method for preparing anionic nonionic gemini surfactants includes the following steps:

[0169] (1) Under a helium atmosphere and in the presence of a catalyst, 1,2-epoxy long-chain hydrocarbons and diols undergo a first contact reaction. After the reaction is completed, intermediate product A is obtained by vacuum distillation.

[0170] (2) Under vacuum conditions and in the presence of alkaline substances, intermediate product A is first polymerized with propylene oxide in a high-pressure reaction vessel, and then polymerized with ethylene oxide to obtain intermediate product B.

[0171] (3) In the presence of a mixed solvent, the intermediate product B first undergoes a first contact reaction with sodium hydroxide, and then undergoes a second contact reaction with chloroacetic acid. After the reaction is completed, an anionic nonionic gemini surfactant is obtained.

[0172] Further, the diol mentioned in step (1) is OH-R'-OH, wherein: R' is a 6-carbon alkyl group, that is, the diol mentioned in step (1) is 1,6-hexanediol.

[0173] Further, the catalyst described in step (1) is sodium hydride, and / or

[0174] In molar terms, the amount of catalyst added in step (1) is 5% of the amount of the diol used.

[0175] Further, the 1,2-epoxy long-chain hydrocarbon mentioned in step (1) is a C10 1,2-epoxy long-chain olefin, and / or

[0176] The molar ratio of the diol to the 1,2-epoxy long-chain hydrocarbon mentioned in step (1) is 1:3.

[0177] Furthermore, in step (1), the reaction temperature of the first contact reaction is 70°C and the reaction time is 6 hours.

[0178] Further, the alkaline substance mentioned in step (2) is calcium hydroxide, and / or

[0179] The molar ratio of the diol in step (1) to the alkaline substance in step (2) is 1:0.1.

[0180] Furthermore, the molar ratio of the diol in step (1) to the propylene oxide and ethylene oxide in step (2) is 1:20:20.

[0181] Furthermore, the reaction temperature of the first polymerization reaction in step (2) is 130°C, and the reaction time of the first polymerization reaction in step (2) is 25 hours.

[0182] Furthermore, the reaction temperature of the second polymerization reaction in step (2) is 130°C, and the reaction time of the second polymerization reaction in step (2) is 15 hours.

[0183] Further, the mixed solvent mentioned in step (3) is a mixture of organic solvent and water, with water accounting for 50% based on the total molar amount of the mixed solvent, and the remainder being organic solvent, and / or

[0184] The organic solvent is isopropanol, and / or

[0185] In molar terms, the amount of the mixed solvent used in step (3) is 20 times that of the diol used in step (1).

[0186] Furthermore, the molar ratio of the diol in step (1) to the sodium hydroxide and chloroacetic acid in step (3) is 1:2.5:3.5.

[0187] Furthermore, the first contact reaction in step (3) is carried out at room temperature, and the reaction time of the first contact reaction in step (3) is 3 hours.

[0188] Furthermore, the reaction temperature of the second contact reaction in step (3) is 130°C, and the reaction time of the second contact reaction in step (3) is 6 hours.

[0189] In other embodiments, a method for preparing an anionic nonionic gemini surfactant, on a molar basis, includes the following steps:

[0190] (A) Place a dry reactor (such as a four-necked flask) in an oil bath and continuously introduce argon gas into the reactor. Add 1 part of diol and 0.05 part of catalyst to the reactor. Take 3 parts of 1,2-epoxy long-chain hydrocarbon and slowly add them dropwise to the reactor through a dropping funnel. After the addition is complete, raise the temperature to 70°C and react for 6 hours. Distill under reduced pressure and take the residue to obtain intermediate product A.

[0191] (B) Add the intermediate product A obtained in step (A) into a high-pressure reactor, add 0.1 parts of alkaline substance, then evacuate and remove air, heat to 130°C, stir, slowly add 20 parts of propylene oxide and react for 25 hours, keep the reaction temperature constant, then add 20 parts of ethylene oxide and react for 15 hours to obtain intermediate product B.

[0192] (C) Add 20 parts of mixed solvent to a high-pressure reactor, then add 2.5 parts of sodium hydroxide, react at room temperature for 3 hours, then add 3.5 parts of chloroacetic acid, heat to 90°C, stir and react for 6 hours. After the reaction is complete, an anionic nonionic gemini surfactant is obtained.

[0193] Anionic nonionic gemini surfactants are prepared by any one of the methods described above.

[0194] The above-mentioned anionic nonionic gemini surfactants are used as oil displacement agents in low-permeability, high-temperature, and high-salinity oil reservoirs.

[0195] In one embodiment:

[0196] An anionic nonionic gemini surfactant has the following structural formula:

[0197] in:

[0198] M is K;

[0199] R is a C8 long-chain olefin;

[0200] EO stands for ethylene oxide block, m is an integer, and m = 20;

[0201] PO represents a propylene oxide block, n is an integer, and n = 20;

[0202] x is a positive integer, and x = 5.

[0203] A method for preparing anionic nonionic gemini surfactants includes the following steps:

[0204] (1) Under a nitrogen atmosphere and in the presence of a catalyst, 1,2-epoxy long-chain hydrocarbons and diols undergo a first contact reaction. After the reaction is completed, intermediate product A is obtained by vacuum distillation.

[0205] (2) Under vacuum conditions and in the presence of alkaline substances, intermediate product A is first subjected to a second polymerization reaction with ethylene oxide in a high-pressure reaction vessel, and then subjected to a first polymerization reaction with propylene oxide to obtain intermediate product B'.

[0206] (3) In the presence of a mixed solvent, the intermediate product B' first undergoes a first contact reaction with potassium hydroxide, and then undergoes a second contact reaction with chloroacetic acid. After the reaction is completed, an anionic nonionic gemini surfactant is obtained.

[0207] Further, the diol mentioned in step (1) is 1,5-pentanediol.

[0208] Further, the catalyst mentioned in step (1) is sodium methoxide, and / or

[0209] In molar terms, the amount of catalyst added in step (1) is 3% of the amount of the diol used.

[0210] Further, the 1,2-epoxy long-chain hydrocarbon mentioned in step (1) is a C8 1,2-epoxy long-chain olefin, and / or

[0211] The molar ratio of the diol to the 1,2-epoxy long-chain hydrocarbon mentioned in step (1) is 1:2.

[0212] Furthermore, in step (1), the reaction temperature of the first contact reaction is 60°C and the reaction time is 8 hours.

[0213] Furthermore, the alkaline substance mentioned in step (2) is ammonia water, and / or

[0214] The molar ratio of the diol in step (1) to the alkaline substance in step (2) is 1:0.15.

[0215] Furthermore, the molar ratio of the diol in step (1) to the propylene oxide and ethylene oxide in step (2) is 1:40:40.

[0216] Furthermore, the reaction temperature of the first polymerization reaction in step (2) is 110°C, and the reaction time of the first polymerization reaction in step (2) is 40 hours.

[0217] Furthermore, the reaction temperature of the second polymerization reaction in step (2) is 110°C, and the reaction time of the second polymerization reaction in step (2) is 20 hours.

[0218] Further, the mixed solvent mentioned in step (3) is a mixture of organic solvent and water, with water accounting for 30% based on the total molar amount of the mixed solvent, and the remainder being organic solvent, and / or

[0219] The organic solvent is n-propanol, and / or

[0220] In molar terms, the amount of the mixed solvent used in step (3) is 10 times that of the diol used in step (1).

[0221] Furthermore, the molar ratio of the diol in step (1) to the potassium hydroxide and chloroacetic acid in step (3) is 1:2:3.

[0222] Furthermore, the first contact reaction in step (3) is carried out at room temperature, and the reaction time of the first contact reaction in step (3) is 2 hours.

[0223] Furthermore, the reaction temperature of the second contact reaction in step (3) is 60°C, and the reaction time of the second contact reaction in step (3) is 8 hours.

[0224] In other embodiments, a method for preparing an anionic nonionic gemini surfactant, on a molar basis, includes the following steps:

[0225] (A) Place a dry reactor (such as a four-necked flask) in an oil bath and continuously introduce nitrogen gas into the reactor. Add 1 part of diol and 0.005 parts of catalyst to the reactor. Take 2 parts of 1,2-epoxy long-chain hydrocarbon and slowly add them dropwise to the reactor through a dropping funnel. After the addition is complete, heat the reactor to 60°C and react for 8 hours. Distill under reduced pressure and take the residue to obtain intermediate product A.

[0226] (B) Add the intermediate product A obtained in step (A) into a high-pressure reactor, add 0.05 parts of alkaline substance, then evacuate and remove air, heat to 110°C, stir, slowly add 40 parts of ethylene oxide and react for 10 hours, keep the reaction temperature constant, then add 40 parts of propylene oxide and react for 10 hours to obtain B'.

[0227] (C) Add 10 parts of mixed solvent to a high-pressure reactor, then add 2 parts of potassium hydroxide, react at room temperature for 2 hours, then add 3 parts of chloroacetic acid, heat to 60°C, stir and react for 8 hours, and the anionic nonionic gemini surfactant is obtained after the reaction is completed.

[0228] Anionic nonionic gemini surfactants are prepared by any one of the methods described above.

[0229] The above-mentioned anionic nonionic gemini surfactants are used as oil displacement agents in low-permeability, high-temperature, and high-salinity oil reservoirs.

[0230] In yet another embodiment:

[0231] An anionic nonionic gemini surfactant has the following structural formula:

[0232] in:

[0233] M is K;

[0234] R is a C18 long-chain olefin;

[0235] EO stands for ethylene oxide block, m is an integer, and m = 25;

[0236] PO represents a propylene oxide block, n is an integer, and n = 25;

[0237] x is a positive integer, and x = 3.

[0238] A method for preparing anionic nonionic gemini surfactants includes the following steps:

[0239] (1) Under a nitrogen atmosphere and in the presence of a catalyst, 1,2-epoxy long-chain hydrocarbons and diols undergo a first contact reaction. After the reaction is completed, intermediate product A is obtained by vacuum distillation.

[0240] (2) Under vacuum conditions and in the presence of alkaline substances, intermediate product A is first subjected to a second polymerization reaction with ethylene oxide in a high-pressure reaction vessel, and then subjected to a first polymerization reaction with propylene oxide to obtain intermediate product B'.

[0241] (3) In the presence of a mixed solvent, the intermediate product B' first undergoes a first contact reaction with potassium hydroxide, and then undergoes a second contact reaction with chloroacetic acid. After the reaction is completed, an anionic nonionic gemini surfactant is obtained.

[0242] Further, the diol mentioned in step (1) is 1,3-propanediol.

[0243] Further, the catalyst described in step (1) is potassium, and / or

[0244] In molar terms, the amount of catalyst added in step (1) is 2% of the amount of the diol used.

[0245] Further, the 1,2-epoxy long-chain hydrocarbon mentioned in step (1) is a -C18 1,2-epoxy long-chain olefin, and / or

[0246] The molar ratio of the diol to the 1,2-epoxy long-chain hydrocarbon mentioned in step (1) is 1:4.

[0247] Furthermore, in step (1), the reaction temperature of the first contact reaction is 90°C and the reaction time is 2 hours.

[0248] Further, the alkaline substance mentioned in step (2) is a mixture of sodium hydroxide, potassium hydroxide, calcium hydroxide, and ammonia in equimolar amounts, and / or

[0249] The molar ratio of the diol in step (1) to the alkaline substance in step (2) is 1:1.

[0250] Further, the molar ratio of the diol in step (1) to the propylene oxide and ethylene oxide in step (2) is 1:50:50.

[0251] Furthermore, the reaction temperature of the first polymerization reaction in step (2) is 150°C, and the reaction time of the first polymerization reaction in step (2) is 10 hours.

[0252] Furthermore, the reaction temperature of the second polymerization reaction in step (2) is 150°C, and the reaction time of the second polymerization reaction in step (2) is 10 hours.

[0253] Further, the mixed solvent mentioned in step (3) is a mixture of organic solvent and water, with water accounting for 70% based on the total molar amount of the mixed solvent, and the remainder being organic solvent, and / or

[0254] The organic solvent is n-butanol, and / or

[0255] In molar terms, the amount of the mixed solvent used in step (3) is 30 times that of the diol used in step (1).

[0256] Furthermore, the molar ratio of the diol in step (1) to the potassium hydroxide and chloroacetic acid in step (3) is 1:3:4.

[0257] Furthermore, the first contact reaction in step (3) is carried out at room temperature, and the reaction time of the first contact reaction in step (3) is 4 hours.

[0258] Furthermore, the reaction temperature of the second contact reaction in step (3) is 110°C, and the reaction time of the second contact reaction in step (3) is 4 hours.

[0259] In other embodiments, a method for preparing an anionic nonionic gemini surfactant, on a molar basis, includes the following steps:

[0260] (A) Place a dry reactor (such as a four-necked flask) in an oil bath and continuously introduce nitrogen gas into the reactor. Add 1 part of diol and 0.1 part of catalyst to the reactor. Take 4 parts of 1,2-epoxy long-chain hydrocarbon and slowly add them dropwise to the reactor through a dropping funnel. After the addition is complete, heat the reactor to 90°C and react for 2 hours. Distill under reduced pressure and take the residue to obtain intermediate product A.

[0261] (B) Add the intermediate product A obtained in step (A) into a high-pressure reactor, add 0.2 parts of alkaline substance, then evacuate and remove air, heat to 150°C, stir, slowly add 50 parts of ethylene oxide and react for 20 hours, keep the reaction temperature constant, then add 50 parts of propylene oxide and react for 40 hours to obtain B'.

[0262] (C) Add 30 parts of mixed solvent to a high-pressure reactor, then add 3 parts of potassium hydroxide, react at room temperature for 4 hours, then add 4 parts of chloroacetic acid, heat to 110°C, stir and react for 8 hours, and the anionic nonionic gemini surfactant is obtained after the reaction is completed.

[0263] Anionic nonionic gemini surfactants are prepared by any one of the methods described above.

[0264] The above-mentioned anionic nonionic gemini surfactants are used as oil displacement agents in low-permeability, high-temperature, and high-salinity oil reservoirs.

[0265] In another embodiment:

[0266] An anionic nonionic gemini surfactant has the following structural formula:

[0267] in:

[0268] M is K;

[0269] R is a C12 long-chain alkyl group;

[0270] EO stands for ethylene oxide block, m is an integer, and m = 20;

[0271] PO represents a propylene oxide block, n is an integer, and n = 20;

[0272] x is a positive integer, and x = 4.

[0273] A method for preparing anionic nonionic gemini surfactants includes the following steps:

[0274] (1) Under a nitrogen atmosphere and in the presence of a catalyst, 1,2-epoxy long-chain hydrocarbons and diols undergo a first contact reaction. After the reaction is completed, intermediate product A is obtained by vacuum distillation.

[0275] (2) Under vacuum conditions and in the presence of alkaline substances, intermediate product A is first subjected to a second polymerization reaction with ethylene oxide in a high-pressure reaction vessel, and then subjected to a first polymerization reaction with propylene oxide to obtain intermediate product B'.

[0276] (3) In the presence of a mixed solvent, the intermediate product B' first undergoes a first contact reaction with potassium hydroxide, and then undergoes a second contact reaction with chloroacetic acid. After the reaction is completed, an anionic nonionic gemini surfactant is obtained.

[0277] Further, the diol mentioned in step (1) is 1,4-butanediol.

[0278] Further, the catalyst described in step (1) is sodium, and / or

[0279] In molar terms, the amount of catalyst added in step (1) is 4% of the amount of the diol used.

[0280] Further, the 1,2-epoxy long-chain hydrocarbon mentioned in step (1) is a C12 1,2-epoxy long-chain alkane, and / or

[0281] The molar ratio of the diol to the 1,2-epoxy long-chain hydrocarbon mentioned in step (1) is 1:3.

[0282] Furthermore, in step (1), the reaction temperature of the first contact reaction is 70°C and the reaction time is 6 hours.

[0283] Further, the alkaline substance mentioned in step (2) is potassium hydroxide, and / or

[0284] The molar ratio of the diol in step (1) to the alkaline substance in step (2) is 1:0.1.

[0285] Furthermore, the molar ratio of the diol in step (1) to the propylene oxide and ethylene oxide in step (2) is 1:40:40.

[0286] Furthermore, the reaction temperature of the first polymerization reaction in step (2) is 130°C, and the reaction time of the first polymerization reaction in step (2) is 25 hours.

[0287] Furthermore, the reaction temperature of the second polymerization reaction in step (2) is 130°C, and the reaction time of the second polymerization reaction in step (2) is 15 hours.

[0288] Further, the mixed solvent mentioned in step (3) is a mixture of organic solvent and water, with water accounting for 40% based on the total molar amount of the mixed solvent, and the remainder being organic solvent, and / or

[0289] The organic solvent is isoamyl alcohol. In other embodiments, the organic solvent is a mixture of methanol, ethanol, isopropanol, n-propanol, n-butanol, isobutanol, and isoamyl alcohol in equimolar ratios. In other embodiments, the organic solvent is isobutanol, and / or

[0290] In molar terms, the amount of the mixed solvent used in step (3) is 20 times that of the diol used in step (1).

[0291] Furthermore, the molar ratio of the diol in step (1) to the potassium hydroxide and chloroacetic acid in step (3) is 1:2.5:3.5.

[0292] Furthermore, the first contact reaction in step (3) is carried out at room temperature, and the reaction time of the first contact reaction in step (3) is 3 hours.

[0293] Furthermore, the reaction temperature of the second contact reaction in step (3) is 90°C, and the reaction time of the second contact reaction in step (3) is 6 hours.

[0294] In other embodiments, a method for preparing an anionic nonionic gemini surfactant, on a molar basis, includes the following steps:

[0295] (A) Place a dry reactor (such as a four-necked flask) in a water bath and continuously introduce nitrogen gas into the reactor. Add 1 part of diol and 0.1 part of catalyst to the reactor. Take 3 parts of 1,2-epoxy long-chain hydrocarbon and slowly add them dropwise to the reactor through a dropping funnel. After the addition is complete, raise the temperature to 70°C and react for 4 hours. Distill under reduced pressure and take the residue to obtain intermediate product A.

[0296] (B) Add the intermediate product A obtained in step (A) into a high-pressure reactor, add 0.1 parts of alkaline substance, then evacuate and remove air, heat to 130°C, stir, slowly add 40 parts of ethylene oxide and react for 15 hours, keep the reaction temperature constant, then add 40 parts of propylene oxide and react for 25 hours to obtain B'.

[0297] (C) Add 20 parts of mixed solvent to a high-pressure reactor, then add 2.5 parts of potassium hydroxide, react at room temperature for 3 hours, then add 3.5 parts of chloroacetic acid, heat to 85°C, stir and react for 6 hours. After the reaction is complete, an anionic nonionic gemini surfactant is obtained.

[0298] Anionic nonionic gemini surfactants are prepared by any one of the methods described above.

[0299] The above-mentioned anionic nonionic gemini surfactants are used as oil displacement agents in low-permeability, high-temperature, and high-salinity oil reservoirs.

[0300] Example 1

[0301] A method for preparing anionic nonionic gemini surfactants includes the following steps:

[0302] Step 1: Place a 100ml dry four-necked flask in a water bath and continuously purge nitrogen gas into the flask. Then add 0.3mol (20g) of ethylene glycol and 0.0025mol (0.1g) of potassium. Take 0.64mol (82g) of 1,2-epoxyoctane and slowly add it dropwise to the four-necked flask through a dropping funnel. After the addition is completed in 30 minutes, raise the water bath temperature to 65℃ and react for 3 hours. Then distill under reduced pressure to obtain intermediate product A.

[0303] Step 2: Add intermediate product A to a high-pressure reactor, add 0.025 mol (1 g) of NaOH, then evacuate and remove air, heat to 110℃ and stir, slowly add 0.6 mol (34.8 g) of propylene oxide and react for 10 h, keeping the reaction temperature constant, then add 0.6 mol (26.4 g) of ethylene oxide and react for 10 h to obtain intermediate product B;

[0304] Step 3: Dissolve intermediate product B in a mixed solution (ethanol and water volume ratio of 2:1), add 0.6 mol (24 g) sodium hydroxide to the above high-pressure reactor, react at room temperature for 2 h, then add 0.9 mol (85.05 g) chloroacetic acid, raise the temperature to 75 °C, and react for 4 h to obtain anionic nonionic gemini surfactant.

[0305] Example 2

[0306] A method for preparing anionic nonionic gemini surfactants includes the following steps:

[0307] Step 1: Place a 100ml dry four-necked flask in an oil bath and continuously purge helium into the flask. Add 0.2mol (15.2g) of 1,2-propanediol and 0.00125mol (0.05g) of potassium. Take 0.48mol (75g) of 1,2-epoxydecane and slowly add it dropwise to the four-necked flask through a dropping funnel. After the addition is completed in 30 minutes, raise the water bath temperature to 60℃ and react for 8 hours. Then, distill under reduced pressure to obtain intermediate product A.

[0308] Step 2: Add intermediate product A to a high-pressure reactor, add 0.05 mol (2 g) of NaOH, then evacuate and remove air, heat to 110℃ and stir, slowly add 0.79 mol (46 g) of propylene oxide and react for 40 h, keep the reaction temperature constant, then add 0.79 mol (35 g) of ethylene oxide and react for 20 h to obtain intermediate product B;

[0309] Step 3: Dissolve intermediate product B in a mixed solution (ethanol and water volume ratio of 2:1), add 0.5 mol (20 g) sodium hydroxide to a high-pressure reactor, react at room temperature for 3 h, then add 0.7 mol (66 g) chloroacetic acid, raise the temperature to 75 °C, and react for 6 h to obtain anionic nonionic gemini surfactant.

[0310] Example 3

[0311] A method for preparing anionic nonionic gemini surfactants includes the following steps:

[0312] Step 1: Place a 100ml dry four-necked flask in a water bath and continuously purge the flask with argon gas. Add 0.2mol (18g) of 1,4-butanediol, then add 0.0043mol (0.1g) of sodium. Take 0.8mol (147.2g) of 1,2-epoxydodecane and slowly add 1,2-epoxydodecane dropwise into the four-necked flask through a dropping funnel. After the addition is completed in 30 minutes, raise the water bath temperature to 90℃ and react for 2 hours. Then, distill under reduced pressure to obtain intermediate product A.

[0313] Step 2: Add intermediate product A to a high-pressure reactor, add 0.075 mol (3 g) of NaOH, then evacuate and remove air, heat to 150℃ and stir, slowly add 12 mol (696 g) of propylene oxide and react for 10 h, keep the reaction temperature constant, then add 12 mol (528 g) of ethylene oxide and react for 10 h to obtain intermediate product B;

[0314] Step 3: Dissolve intermediate product B in a mixed solution (ethanol and water volume ratio of 2:1), add 0.6 mol (24 g) sodium hydroxide to the above product solution, react at room temperature for 4 h, then add 0.8 mol (75.6 g) chloroacetic acid, raise the temperature to 110 °C, and react for 4 h to obtain anionic nonionic gemini surfactant.

[0315] Example 4

[0316] An anionic-nonionic twin-type surfactant has the following structural formula:

[0317] in:

[0318] R is an alkane with 14 carbon atoms (C14 straight-chain n-alkane);

[0319] EO stands for ethylene oxide block, m is an integer, and m = 1;

[0320] PO represents a propylene oxide block, n is an integer, and n = 1;

[0321] x is a positive integer, and x = 2.

[0322] A method for preparing anionic nonionic gemini surfactant, comprising the following steps, by weight:

[0323] (1) Place a dry four-necked flask in a water bath, introduce nitrogen gas, add 10g of ethylene glycol, then add 0.2g of sodium and 75g of 1,2-epoxytetradecane. Add the flask slowly through a dropping funnel. After the addition is completed in 30 minutes, raise the water bath temperature to 80°C and react for 3 hours. Distill under reduced pressure and the residue is the intermediate product.

[0324] (2) Add the intermediate product obtained from the reaction to a high pressure vessel, add 2g of NaOH, then evacuate and remove air, heat to 120℃, stir, slowly add 16g of propylene oxide and react for 15 hours, then add 13g of ethylene oxide and react for 10 hours to obtain the intermediate product.

[0325] (3) Add 40g of a mixed solvent of ethanol and water in a volume ratio of 2:1d to a high pressure vessel, then add 12g of sodium hydroxide, react for 2 hours, then add 40g of chloroacetic acid, heat to 80℃ and stir for 4-8 hours. After the reaction is complete, an anionic nonionic gemini surfactant is obtained.

[0326] Example 5

[0327] An anionic nonionic gemini surfactant has the following structural formula:

[0328] in:

[0329] R is an alkane with 16 carbon atoms (C16 straight-chain n-alkanes);

[0330] EO stands for ethylene oxide block, m is an integer, and m = 30;

[0331] PO represents a propylene oxide block, n is an integer, and n = 30;

[0332] x is a positive integer, and x = 6.

[0333] A method for preparing anionic nonionic gemini surfactant, comprising the following steps, by weight:

[0334] (1) Place a dry four-necked flask in a water bath, introduce nitrogen gas, add 20g of ethylene glycol, then add 0.3g of potassium, take 160g of 1,2-epoxyhexadecane, and slowly add it dropwise into the flask through a dropping funnel. After the addition is complete, raise the water bath temperature to 90℃, react for 6 hours, and then distill under reduced pressure. The residue is the intermediate product.

[0335] (2) Add the intermediate product obtained from the reaction to a high pressure vessel, add 5g of alkali, then evacuate and remove air, heat to 140℃, stir, slowly add 32g of propylene oxide and react for 30 hours, then add 25g of ethylene oxide and react for 20 hours to obtain the intermediate product.

[0336] (3) Add 60g of a mixture of isopropanol and water in a volume ratio of 2:1 to a high-pressure reactor, then add 25g of sodium hydroxide and react for 4 hours. Then add 82g of chloroacetic acid, heat to 100℃ and stir for 6 hours. After the reaction is complete, an anionic nonionic gemini surfactant is obtained.

[0337] Example 6

[0338] An anionic-nonionic twin-type surfactant has the following structural formula:

[0339] in:

[0340] R is an alkane with 18 carbon atoms (C18 straight-chain n-alkanes);

[0341] EO stands for ethylene oxide block, m is an integer, and m = 15;

[0342] PO stands for propylene oxide, n is an integer, and n = 15;

[0343] x is a positive integer segment, and x = 2.

[0344] A method for preparing anionic nonionic gemini surfactant, comprising the following steps, by weight:

[0345] (1) Place a dry four-necked flask in a water bath, introduce nitrogen gas, add 10g of ethylene glycol, then add 0.2g of potassium, take 130g of 1,2-epoxyoctadecane, and slowly add it dropwise into the flask through a dropping funnel. After the addition is completed in 1 hour, raise the water bath temperature to 90℃, react for 6 hours, and then distill under reduced pressure. The residue is the intermediate product.

[0346] (2) Add the intermediate product obtained from the reaction to a high pressure vessel, add 5g of alkali, then evacuate and remove air, heat to 140℃, stir, slowly add a certain amount of propylene oxide and react for 30 hours, then add a certain amount of ethylene oxide and react for 20 hours to obtain the intermediate product.

[0347] (3) Add 60g of butanol and water in a volume ratio of 2:1 to the autoclave, then add 18g of sodium hydroxide and react for 4 hours. Then add 54g of chloroacetic acid, heat to 100℃ and stir for 6 hours. After the reaction is complete, an anionic nonionic gemini surfactant is obtained.

[0348] Furthermore, the molar ratio of the diol to the epoxide long-chain hydrocarbon in step (1) is 1:3.

[0349] Furthermore, the alkali mentioned in step (2) is sodium hydroxide.

[0350] Further, in step (2), the molar ratio of the intermediate product obtained in step (1) to propylene oxide and ethylene oxide is 1:30:30.

[0351] Furthermore, in step (3), the molar ratio of the intermediate product obtained in step (2) to sodium hydroxide and sodium chloroacetate is 1:3:4.

[0352] Examples 7-10

[0353] Similar to Example 4, except for the diol and alcohol solution:

[0354] Dihalogenated hydrocarbons Mixed solution Example 7 1,3-Propanediol n-Butanol and water Example 8 1,4-Butanediol n-Propanol and Water Example 9 1,5-Pentanediol Isopropanol and water Example 10 1,6-Hexanediol Isoamyl alcohol and water

[0355] Performance and Testing

[0356] 1. Infrared spectroscopy detection

[0357] The intermediate product B prepared in Example 1 was subjected to infrared spectroscopy, and its infrared spectrum is shown below. Figure 1 As shown. From Figure 1 It can be seen from this that at 3464cm -1 There is a relatively broad absorption peak at 2922 cm⁻¹, which is the stretching vibration peak of OH; while at 2922 cm⁻¹... -1 The multiple peaks at 1748 cm⁻¹ indicate the presence of methyl or methylene groups in the sample; -1 1641cm -1The absorption peak at 1453 cm⁻¹ is likely due to the stretching vibration of C=O in esters; -1 The absorption peak at 1375 cm⁻¹ is due to the in-plane bending vibration of the methyl or methylene group; while the absorption peak at 1375 cm⁻¹ is due to the in-plane bending vibration of the methyl or methylene group. -1 and 1103cm -1 The absorption peak at 931 cm⁻¹ is the stretching vibration peak of the CO bond, representing the formation of the ether bond; -1 The absorption peak at that point is the out-of-plane bending vibration peak of -COH.

[0358] The anionic nonionic gemini surfactant prepared in Example 1 was subjected to infrared spectroscopy, and its infrared spectrum is shown below. Figure 2 As shown. From Figure 2 As can be seen from this, 2875cm -1 The multiple peaks at 1776 cm⁻¹ indicate the presence of methyl or methylene groups in the sample; -1 1633cm -1 The absorption peak at 1414 cm⁻¹ is likely due to the stretching vibration of C=O in esters; -1 The absorption peak at 1068 cm⁻¹ is due to the in-plane bending vibration of the methyl or methylene group; while the absorption peak at 1068 cm⁻¹ is due to the in-plane bending vibration of the methyl or methylene group. -1 The strongest absorption peak in this region is found at 2200 cm⁻¹, indicating the presence of CO bonds in the sample; -1 The absorption peak at 735 cm⁻¹ is the absorption peak of sodium salt, representing the production of sodium carboxylate; -1 The absorption peak at this point is an in-plane rocking peak of the methylene group.

[0359] Infrared spectroscopy was performed on the anionic nonionic gemini surfactant obtained in Example 4, and the results are as follows: Figure 3 As shown. From Figure 3 It can be seen from this that: 3348cm -1 There is a broad, strong absorption peak at 2993 cm⁻¹, which is the absorption peak of the amine group; -1 There is an absorption peak for sodium salts nearby; 2916 cm⁻¹ -1 Nearby, there is a weak absorption multi-peak pattern, which is the stretching vibration peak of the methyl and methylene groups; 1712 cm⁻¹ -1 1622cm -1 The absorption peak at 1408 cm⁻¹ is likely due to the stretching vibration of C=O. -1 The absorption peak at 1063 cm⁻¹ is due to the in-plane bending vibration of the methyl or methylene group; -1 The absorption peak at 688 cm⁻¹ is the stretching vibration peak of CO; while the absorption peak at 688 cm⁻¹ is the stretching vibration peak of CO. -1 The absorption peak at that point may be an in-plane rocking peak of the methylene group.

[0360] 2. Washing rate and surface tension test

[0361] The wash-off rate and surface tension of the anionic-nonionic gemini surfactants prepared in Examples 1-10 were tested using a surface tension meter. The results are shown in Table 1. Table 1 shows that the anionic-nonionic gemini surfactants prepared using this invention exhibit high wash-off rate and low surface tension.

[0362] Table 1. Results of washout rate and surface tension tests for anionic-nonionic gemini surfactants.

[0363]

[0364] The oil washing rate measurement shows that the oil washing rate of the anionic-nonionic gemini surfactant of the present invention is higher than that of conventional surfactants, indicating that the anionic-nonionic gemini surfactant disclosed in the present invention has good oil washing performance and can improve the development effect of oil reservoirs.

[0365] Surface tension measurements after high-temperature treatment revealed that the surface tension of the anionic-nonionic gemini surfactant remained unchanged or showed no significant change after two days of treatment at 150°C, indicating that the anionic-nonionic gemini surfactant of this invention has good temperature resistance and is stable at 150°C.

[0366] Surfactant Name concentration Surface tension (mN / m) Sample prepared in Example 1 0.5％ 30.8

[0367] Surface tension measurements after high-salt treatment revealed that the surface tension of the anionic-nonionic gemini surfactant further decreased in 130,000 mg / L saline solution, indicating that the anionic-nonionic gemini surfactant of this invention has good salt resistance.

[0368] Surfactant Name concentration Surface tension (mN / m) Sample prepared in Example 1 0.5％ 27.6

[0369] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. An anionic nonionic gemini surfactant, characterized in that, Its structural formula is as follows: in: M is either Na or K; R is a C8-C18 long-chain alkyl or C8-C18 long-chain olefin; EO stands for ethylene oxide block, m is an integer, and 1≤m≤30, preferably 10≤m≤30; PO is a propylene oxide block, n is an integer, and 1≤n≤30, preferably 10≤n≤30; x is a positive integer, and 2≤x≤10, preferably 2≤x≤6.

2. A method for preparing the anionic nonionic gemini surfactant according to claim 1, characterized in that, Includes the following steps: (1) Under a nitrogen or inert gas atmosphere and in the presence of a catalyst, 1,2-epoxy long-chain hydrocarbons and diols undergo a first contact reaction. After the reaction is completed, intermediate product A is obtained by vacuum distillation. (2) Under vacuum conditions and in the presence of alkaline substances, intermediate product A is first reacted with propylene oxide / ethylene oxide in a high-pressure reaction vessel to complete the first / second polymerization reaction, and then reacted with ethylene oxide / propylene oxide to complete the second / first polymerization reaction to obtain intermediate product B / intermediate product B'. (3) In the presence of a mixed solvent, the intermediate product B / intermediate product B' first undergoes a first contact reaction with sodium hydroxide or potassium hydroxide, and then undergoes a second contact reaction with chloroacetic acid. After the reaction is completed, an anionic nonionic gemini surfactant is obtained.

3. The method for preparing an anionic nonionic gemini surfactant as described in claim 2, characterized in that, The diol mentioned in step (1) is OH-R'-OH, wherein: R' is a alkyl group with 2-10 carbon atoms, preferably one or more of 1,2-ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol.

4. The method for preparing an anionic nonionic gemini surfactant as described in claim 2, characterized in that, The catalyst mentioned in step (1) is one of potassium, sodium, sodium hydride, sodium methoxide, and / or In molar terms, the amount of catalyst added in step (1) is 0.5%-10% of the amount of the diol, preferably 0.5%-5%.

5. The method for preparing an anionic nonionic gemini surfactant as described in claim 2, characterized in that, The 1,2-epoxy long-chain hydrocarbon mentioned in step (1) is a C8-C18 1,2-epoxy long-chain alkane or a C8-C18 1,2-epoxy long-chain olefin, and / or The molar ratio of the diol to the 1,2-epoxy long-chain hydrocarbon mentioned in step (1) is 1:(2-4).

6. The method for preparing an anionic nonionic gemini surfactant as described in claim 2, characterized in that, In step (1), the reaction temperature of the first contact reaction is at least 60°C, preferably 60-90°C, and the reaction time is at least 2 hours, preferably 2-8 hours.

7. The method for preparing an anionic nonionic gemini surfactant as described in claim 2, characterized in that, The alkaline substance mentioned in step (2) is one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, and ammonia water, and / or The molar ratio of the diol in step (1) to the alkaline substance in step (2) is 1:(0.05-0.2).

8. The method for preparing an anionic nonionic gemini surfactant as described in claim 2, characterized in that, The molar ratio of the diol in step (1) to the propylene oxide and ethylene oxide in step (2) is 1:(2-60):(2-60).

9. The method for preparing an anionic nonionic gemini surfactant as described in claim 2, characterized in that, The reaction temperature of the first polymerization reaction in step (2) is at least 110°C, preferably 110°C-150°C, and the reaction time of the first polymerization reaction in step (2) is at least 10 hours, preferably 10-40 hours.

10. The method for preparing an anionic nonionic gemini surfactant as described in claim 2, characterized in that, The reaction temperature of the second polymerization reaction in step (2) is at least 110°C, preferably 110°C-150°C, and the reaction time of the second polymerization reaction in step (2) is at least 10 hours, preferably 10-20 hours.

11. The method for preparing an anionic nonionic gemini surfactant as described in claim 2, characterized in that, The mixed solvent mentioned in step (3) is a mixture of organic solvent and water, with water accounting for 30%-70% based on the total molar amount of the mixed solvent, and the remainder being organic solvent, and / or The organic solvent is one or more of methanol, ethanol, isopropanol, n-propanol, n-butanol, isobutanol, and isoamyl alcohol, and / or In molar terms, the amount of the mixed solvent used in step (3) is 10-30 times that of the diol used in step (1).

12. The method for preparing an anionic nonionic gemini surfactant as described in claim 2, characterized in that, The molar ratio of the diol in step (1) to sodium hydroxide or potassium hydroxide and chloroacetic acid in step (3) is 1:(2-3):(3-4).

13. The method for preparing an anionic nonionic gemini surfactant as described in claim 2, characterized in that, The first contact reaction in step (3) is carried out at room temperature, and the reaction time of the first contact reaction in step (3) is at least 2 hours, preferably 2-4 hours.

14. The method for preparing an anionic nonionic gemini surfactant as described in claim 2, characterized in that, The reaction temperature of the second contact reaction in step (3) is at least 60°C, preferably 60°C-110°C, and the reaction time of the second contact reaction in step (3) is at least 4 hours, preferably 4-8 hours.

15. The method for preparing an anionic nonionic gemini surfactant as described in claim 2, characterized in that, In molars, the following steps are included: (A) Place a dry reactor (such as a four-necked flask) in a water bath or oil bath, continuously introduce nitrogen or inert gas into the reactor, add 1 part of diol and 0.005-0.1 part of catalyst to the reactor, take 2-4 parts of 1,2-epoxy long-chain hydrocarbon, and slowly add them dropwise to the reactor through a dropping funnel. After the addition is complete, raise the temperature to at least 60°C, preferably 60-90°C, react for 2 hours, preferably 2-8 hours, distill under reduced pressure, and take the residue to obtain intermediate product A; (B) Add the intermediate product A obtained in step (A) into a high-pressure reactor, add 0.05 to 0.2 parts of alkaline substance, then evacuate and remove air, heat to at least 110°C, preferably 110°C-150°C, stir, slowly add 2-60 parts of propylene oxide / ethylene oxide and react for 10-40 hours / 10-20 hours, keep the reaction temperature constant, then add 2-60 parts of ethylene oxide / propylene oxide and react for 10-20 hours / 10-40 hours to obtain intermediate product B / B'; (C) Add 10-30 parts of mixed solvent to a high-pressure reactor, then add 2-3 parts of sodium hydroxide or potassium hydroxide, react at room temperature for at least 2 hours, preferably 2-4 hours, then add 3-4 parts of chloroacetic acid, heat to at least 60°C, preferably 60°C-110°C, stir and react for at least 4 hours, preferably 4-8 hours, and after the reaction is complete, an anionic nonionic gemini surfactant is obtained.

16. An anionic nonionic gemini surfactant, prepared by the method according to any one of claims 2-15.

17. The application of the anionic nonionic gemini surfactant as described in claim 1 or 16 as an oil displacement agent in low-permeability, high-temperature, and high-salinity oil reservoirs.

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