Dicationic surfactants, methods of making and using the same

Abstract

The application relates to the technical field of oil field chemistry, and relates to a dicationic surfactant as well as a preparation method and application thereof, the method comprises the following steps: step one, aromatic dialdehyde and 3-dimethylaminopropylamine are added into a reaction solvent, reflux reaction is carried out, and a Schiff base intermediate solution is obtained; step two, halogenated hydrocarbon is added into the Schiff base intermediate solution, stirring reaction is carried out, and the dicationic surfactant is obtained. The application provides a dicationic surfactant and a preparation method thereof, the preparation method principle is reliable, the operation is simple, the reaction condition is mild, and the product yield is high; the dicationic surfactant can efficiently kill harmful microorganisms such as sulfate-reducing bacteria and the like as an oil field bactericide, the dicationic surfactant is not prone to causing drug resistance of the harmful microorganisms, and has a wide market application prospect.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemical technology, specifically a dicationic surfactant, its preparation method, and its application. Background Technology

[0002] During oilfield extraction, the reservoir environment is rich in nutrients such as water, carbon, and nitrogen, and the temperature and pressure conditions are suitable for microbial growth and reproduction. Common harmful microorganisms in oilfields include sulfate-reducing bacteria (SRB), saprophytic bacteria (TGB), and iron bacteria. The metabolic activities of these microorganisms can cause a series of serious problems: sulfate-reducing bacteria reduce sulfate to produce hydrogen sulfide, which not only corrodes metal equipment such as oil pipes and casings but also reduces crude oil quality and endangers the health of workers; the slime produced by saprophytic bacteria can clog oil layer pores and oil production channels, leading to a decrease in crude oil production; iron bacteria oxidize ferrous ions to produce ferric hydroxide precipitate, accelerating equipment corrosion and further exacerbating formation blockage. Therefore, efficient and stable bactericides for oilfields are one of the key additives for ensuring normal oilfield extraction and reducing production costs.

[0003] Currently, commonly used bactericides in oilfields are mainly divided into two categories: inorganic bactericides and organic bactericides. Inorganic bactericides, such as hypochlorite and chlorine dioxide, while having a fast bactericidal speed, suffer from drawbacks such as short action time, strong corrosiveness, susceptibility to organic interference, and poor environmental compatibility, making long-term stable use difficult. Among organic bactericides, quaternary ammonium salts have become mainstream products due to their broad bactericidal spectrum, ease of use, and lower cost. However, traditional single-chain quaternary ammonium salts are prone to inducing microbial resistance with long-term use, leading to a continuous decline in bactericidal efficiency. Furthermore, their insufficient temperature and salt resistance result in reduced solubility and loss of effective components in high-temperature, high-salinity oilfield water environments, and they may even form precipitates with calcium and magnesium ions, severely limiting their application in complex reservoir conditions. While quaternary phosphonium salt bactericides have shown improvements in bactericidal activity and stability, they suffer from complex synthesis routes, high raw material costs, and insufficient industrial economics. In addition, aldehydes and heterocyclic bactericides often have drawbacks such as high toxicity, poor compatibility, and significant environmental risks.

[0004] To address the aforementioned issues, researchers both domestically and internationally have conducted extensive research and development on bactericides. For example, Chinese patent document CN121824542A discloses a bactericide for water injection in oil and gas fields and its preparation method. This involves synthesizing an epoxy quaternary ammonium salt from 1,4-butanediol diglycidyl ether and N-methyl-N-dodecylbenzylamine, and then attaching caffeine to the epoxy quaternary ammonium salt to obtain a bis-quaternary ammonium salt. This technical solution attempts to reduce the risk of microbial resistance by introducing a functional group from caffeine and utilizing its purine ring structure to interfere with bacterial DNA replication. However, this solution still has several shortcomings: First, caffeine belongs to the xanthine heterocyclic compound class. Although it has a certain synergistic bactericidal effect, it poses potential environmental and ecological risks, and its biodegradability and environmental safety require systematic evaluation. Second, the synthetic route is relatively long, requiring two-step reactions and multiple extractions and recrystallization processes, resulting in high production costs and significant environmental pressure. Third, the patent does not provide specific data on temperature and salt resistance performance, raising doubts about its practical application in high-salinity, high-temperature formation water.

[0005] In summary, existing oilfield bactericide systems suffer from several drawbacks: traditional inorganic bactericides are highly corrosive and damage formations; conventional quaternary ammonium salts are prone to developing resistance and have poor temperature resistance; while improved dicationic bactericides have shown some improvement in bactericidal activity, they still generally suffer from insufficient molecular structure stability, poor temperature and salt resistance, complex synthesis processes, high raw material costs, and room for improvement in environmental compatibility. They cannot simultaneously meet multiple field requirements such as high-temperature resistance, resistance to high salinity, inhibition of microbial resistance, low cost, and broad compatibility with adjuvants. The industry urgently needs a novel dicationic surfactant-based oilfield microbial bactericide that can simultaneously address these multiple shortcomings. Summary of the Invention

[0006] This invention provides a dual-cationic surfactant and its preparation method, which overcomes the shortcomings of the prior art and can effectively solve the problems of insufficient bactericidal efficiency, easy development of drug resistance, poor temperature resistance and high cost of existing bactericides.

[0007] One of the technical solutions of this invention is achieved through the following measures: a dicationic surfactant having the following chemical structure: Where n is an integer from 10 to 16; X is the element chlorine and / or bromine.

[0008] The following are further optimizations and / or improvements to one of the above-mentioned technical solutions: The aforementioned dicationic surfactants are used as bactericides in oil fields.

[0009] The above-mentioned dicationic surfactant was prepared according to the following steps: Step 1: Aromatic dialdehyde and 3-dimethylaminopropylamine are added to the reaction solvent and refluxed to obtain a Schiff base intermediate solution. Step 2: Add a haloalkane to the Schiff base intermediate solution and stir to react, thus obtaining a dicationic surfactant.

[0010] The aforementioned aromatic dialdehyde is one or more of terephthalaldehyde, o-phthalaldehyde, and iso-phthalaldehyde.

[0011] The molar ratio of the above-mentioned aromatic dialdehyde, 3-dimethylaminopropylamine and haloalkanes is 1.0 to 1.2:2.0:1.8 to 2.0.

[0012] The solvent used in the above reaction was anhydrous ethanol.

[0013] In step one above, the reflux reaction is carried out under inert gas protection.

[0014] In step one above, the reaction temperature is 60℃ to 80℃, and the reaction time is 4h to 12h.

[0015] In step two above, the reaction temperature is 70℃ to 90℃, and the reaction time is 8h to 24h.

[0016] The second technical solution of the present invention is achieved through the following measures: a method for preparing a dicationic surfactant, comprising the following steps: Step 1: Aromatic dialdehyde and 3-dimethylaminopropylamine are added to the reaction solvent and refluxed to obtain a Schiff base intermediate solution. Step 2: Add a haloalkane to the Schiff base intermediate solution and stir to react, thus obtaining a dicationic surfactant.

[0017] The third technical solution of the present invention is achieved through the following measures: the application of a dicationic surfactant as a bactericide for oil fields.

[0018] This invention provides a dicationic surfactant and its preparation method. The preparation method is reliable in principle, simple to operate, mild in reaction conditions, and has a high product yield. As a bactericide for oil fields, this dicationic surfactant can effectively kill harmful microorganisms such as sulfate-reducing bacteria and is not prone to causing drug resistance, thus having broad market application prospects. Detailed Implementation

[0019] This invention is not limited to the following embodiments, and specific implementation methods can be determined according to the technical solutions and actual conditions of this invention. Unless otherwise specified, all chemical reagents and chemicals mentioned in this invention are well-known and commonly used chemical reagents and chemicals in the prior art; unless otherwise specified, all percentages in this invention are mass percentages; unless otherwise specified, all solutions in this invention are aqueous solutions with water as the solvent, for example, hydrochloric acid solution is an aqueous solution of hydrochloric acid; room temperature in this invention generally refers to a temperature between 15°C and 25°C, generally defined as 25°C.

[0020] The present invention will be further described below with reference to embodiments: Example 1: This dicationic surfactant has the following chemical structure: Where n is an integer from 10 to 16; X is the element chlorine and / or bromine.

[0021] Example 2: As an optimization of the above example, the dual cationic surfactant is used as a bactericide for oil fields.

[0022] Example 3: As an optimization of the above examples, the dicationic surfactant was prepared according to the following steps: Step 1: Aromatic dialdehyde and 3-dimethylaminopropylamine are added to the reaction solvent and refluxed to obtain a Schiff base intermediate solution. Step 2: Add a haloalkane to the Schiff base intermediate solution and stir to react, thus obtaining a dicationic surfactant.

[0023] Example 4: As an optimization of the above examples, the aromatic dialdehyde is one or more of terephthalaldehyde, o-phthalaldehyde, and iso-phthalaldehyde.

[0024] Example 5: As an optimization of the above examples, the molar ratio of aromatic dialdehyde, 3-dimethylaminopropylamine and haloalkanes is 1.0 to 1.2:2.0:1.8 to 2.0.

[0025] Example 6: As an optimization of the above examples, the reaction solvent is anhydrous ethanol.

[0026] Example 7: As an optimization of the above example, in step one, the reflux reaction is carried out under the protection of an inert gas.

[0027] Example 8: As an optimization of the above example, in step one, the reaction temperature is 60°C to 80°C and the reaction time is 4h to 12h.

[0028] Example 9: As an optimization of the above example, in step two, the reaction temperature is 70°C to 90°C and the reaction time is 8h to 24h.

[0029] Example 10: Application of this dual-cationic surfactant as a bactericide for oil fields.

[0030] To address the performance deficiencies of existing oilfield bactericides, this invention provides a dual-cationic surfactant, prepared from aromatic dialdehyde, 3-dimethylaminopropylamine, and haloalkanes via a two-step reaction involving aldehyde-amine condensation and quaternization. Its molecular structure contains active groups such as a benzene ring, two long-chain alkyl groups, two Schiff bases, and a dual-quaternary ammonium salt. The chemical reaction process is shown below: Where n is an integer from 10 to 16; X is the element chlorine and / or bromine.

[0031] As a bactericide for oil fields, this dual-cationic surfactant has excellent inhibitory and killing effects on common harmful microorganisms in oil fields, such as sulfate-reducing bacteria and saprophytic bacteria.

[0032] Example 11: The preparation process of this dicationic surfactant is as follows: Step 1: In a 250 mL reaction vessel equipped with a stirrer, a reflux condenser, and a nitrogen inlet tube, add 0.11 mol of terephthalaldehyde and 100 mL of anhydrous ethanol, stir until homogeneous, and slowly add 0.2 mol of 3-dimethylaminopropylamine dropwise at room temperature; purge with nitrogen for 15 min to remove oxygen, raise the temperature to 80 °C, reflux and stir for 12 h to obtain a Schiff base intermediate solution.

[0033] Step 2: Slowly add 0.2 mol of bromododecane dropwise to the Schiff base intermediate solution; after the addition is complete, heat to 90°C and reflux with stirring for 12 h. Cool to room temperature, and recover anhydrous ethanol by vacuum distillation to obtain the dicationic surfactant.

[0034] Example 12: The preparation process of this dicationic surfactant is as follows: Step 1: In a 250 mL reaction vessel equipped with a stirrer, a reflux condenser, and a nitrogen inlet tube, add 0.10 mol of o-phthalaldehyde and 100 mL of anhydrous ethanol, stir until homogeneous, slowly add 0.2 mol of 3-dimethylaminopropylamine dropwise at room temperature, purge with nitrogen for 15 min to remove oxygen, raise the temperature to 70 °C, and reflux and stir for 8 h to obtain a Schiff base intermediate solution.

[0035] Step 2: 0.19 mol of tetradecyl chloride was slowly added dropwise to the Schiff base intermediate solution. After the addition was complete, the temperature was raised to 80°C, and the mixture was refluxed and stirred for 18 hours. The mixture was then cooled to room temperature, and anhydrous ethanol was recovered by vacuum distillation to obtain the dicationic surfactant.

[0036] Example 13: The preparation process of this dicationic surfactant is as follows: Step 1: In a 250 mL reaction vessel equipped with a stirrer, a reflux condenser, and a nitrogen inlet tube, add 0.12 mol of isophthalaldehyde and 100 mL of anhydrous ethanol, stir until homogeneous, slowly add 0.2 mol of 3-dimethylaminopropylamine dropwise at room temperature, purge with nitrogen for 15 min to remove oxygen, raise the temperature to 60 °C, and reflux and stir for 10 h to obtain the Schiff base intermediate.

[0037] Step two: 0.20 mol of hexadecane bromide was slowly added dropwise to the above Schiff base intermediate solution. After the addition was complete, the temperature was raised to 85°C, and the mixture was refluxed and stirred for 20 h. After cooling to room temperature, anhydrous ethanol was recovered by vacuum distillation to obtain the dicationic surfactant.

[0038] Example 14: The preparation process of this dicationic surfactant is as follows: Step 1: In a 250 mL reaction vessel equipped with a stirrer, a reflux condenser, and a nitrogen inlet tube, add 0.10 mol of terephthalaldehyde, 0.02 mol of o-phthalaldehyde, and 100 mL of anhydrous ethanol, stir until homogeneous, slowly add 0.2 mol of 3-dimethylaminopropylamine dropwise at room temperature, purge with nitrogen for 15 min to remove oxygen, raise the temperature to 75 °C, and reflux and stir for 9 h to obtain the Schiff base intermediate.

[0039] Step two: 0.18 mol of hexadecane bromide was slowly added dropwise to the above Schiff base intermediate solution. After the addition was complete, the temperature was raised to 90°C, and the mixture was refluxed and stirred for 12 hours. After cooling to room temperature, anhydrous ethanol was removed by vacuum distillation to obtain the dicationic surfactant.

[0040] Test Example 1: Sterilization Performance Test According to the standard "Q / SY 49-2010 Technical Requirements for Bactericides Used in Oilfields", relevant bactericidal tests were conducted. Reinjected water from a certain area of ​​an oilfield was used as the test subject, and the conventional oilfield bactericide 1227 (dodecyl dimethyl benzyl ammonium chloride) was used as a comparison. The dosage of the dual-cationic surfactant prepared in Examples 11 to 14 and the conventional bactericide 1227 was 50 mg / L. The bactericidal performance was evaluated, and the results are shown in Table 1 (SRB is sulfate-reducing bacteria, TGB is saprophytic bacteria, and FB is iron bacteria).

[0041] Table 1 .

[0042] As shown in Table 1, the dual-cationic surfactants prepared in Examples 11 to 14 of this invention achieved a bactericidal rate of over 99.9% against three common harmful bacteria in oilfields: SRB, TGB, and FB. This indicates that the synergistic effect of multiple active groups in the molecular structure, including the benzene ring, two long-chain alkyl groups, two Schiff bases, and the bisquaternary ammonium salt, results in significant bactericidal efficacy. At a usage concentration of 50 mg / L, the dual-cationic surfactant of this invention significantly outperforms conventional 1227. This means that to achieve the same bactericidal effect, the usage concentration of the product of this invention can be significantly reduced, thereby reducing the amount of on-site reagents and lowering operating costs.

[0043] Test Example 2: Evaluation of Temperature Resistance The experimental samples were prepared into 1000 mg / L solutions with distilled water, heat-treated at 120℃ for 24 h, and cooled to room temperature. The sterilization rate was determined according to the above-mentioned sterilization effect evaluation method, and the temperature resistance was evaluated. The results are shown in Table 2.

[0044] The dicationic surfactants prepared in Examples 11 to 14 and conventional bactericide 1227 were respectively prepared into 1000 mg / L solutions using distilled water. The solutions were then heat-treated at 120 °C for 24 h, and the bactericidal effect of each sample after 24 h of heat treatment was tested to evaluate the temperature resistance of the bactericide. The results are shown in Table 2 (SRB is sulfate-reducing bacteria, TGB is saprophytic bacteria, and FB is iron bacteria).

[0045] Table 2 .

[0046] As shown in Table 2, after heat treatment at 120℃ for 24 hours, the bactericidal rate of conventional bactericide 1227 decreased significantly. The bactericidal rate of the dicationic surfactants prepared in Examples 11 to 14 remained above 96.8%, demonstrating excellent temperature resistance and adaptability to high-temperature reservoir environments, meeting the bactericidal requirements under high-temperature conditions in oilfields. This is because the dicationic surfactant molecules of this invention contain a rigid benzene ring structure, a Schiff base conjugated system, and bisquaternary ammonium salt groups. The intramolecular chemical bonds have high bond energies and stable structures, making them less prone to decomposition and inactivation under high-temperature conditions, thus maintaining good bactericidal activity.

[0047] In summary, this invention provides a dual-cationic surfactant and its preparation method. This dual-cationic surfactant contains multiple active groups including a benzene ring, two long-chain alkyl groups, two Schiff bases, and two quaternary ammonium salts. It achieves a bactericidal rate of over 99.9% against SRB, TGB, and FB oilfield harmful bacteria, and maintains a bactericidal rate of over 96.8% even after high-temperature heat treatment, demonstrating outstanding temperature resistance. Its preparation requires only two steps: aldehyde-amine condensation and quaternization. The method is reliable in principle, simple to operate, and operates under mild conditions, possessing broad market application prospects and suitable for complex working conditions such as high-temperature oil reservoirs.

[0048] The above technical features constitute various embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

Claims

1. A dual-cationic surfactant, characterized in that... It has the following chemical structure: Where n is an integer from 10 to 16; X is the element chlorine or bromine.

2. The dual-cationic surfactant according to claim 1, characterized in that... The dual-cationic surfactant is used as a bactericide in oil fields.

3. The dual-cationic surfactant according to claim 2, characterized in that... The dicationic surfactant was prepared according to the following steps: Step 1: Aromatic dialdehyde and 3-dimethylaminopropylamine are added to the reaction solvent and refluxed to obtain a Schiff base intermediate solution. Step 2: Add a haloalkane to the Schiff base intermediate solution and stir to react, thus obtaining a dicationic surfactant.

4. The dual-cationic surfactant according to claim 3, characterized in that... Aromatic dialdehyde is one of terephthalaldehyde, o-phthalaldehyde, and iso-phthalaldehyde.

5. The dual-cationic surfactant according to claim 3 or 4, characterized in that... The molar ratio of aromatic dialdehyde, 3-dimethylaminopropylamine and haloalkanes is 1.0 to 1.2:2.0:1.8 to 2.

0.

6. The dual-cationic surfactant according to claim 3 or 4, characterized in that... The reaction solvent is anhydrous ethanol.

7. The dual-cationic surfactant according to claim 3 or 4, characterized in that... In step one, the reflux reaction is carried out under inert gas protection.

8. The dual-cationic surfactant according to claim 3 or 4, characterized in that... In step one, the reaction temperature is 60℃ to 80℃, and the reaction time is 4h to 12h.

9. The dual-cationic surfactant according to claim 3 or 4, characterized in that... In step two, the reaction temperature is 70℃ to 90℃, and the reaction time is 8h to 24h.

10. A method for preparing a dicationic surfactant according to any one of claims 1 to 9, characterized in that... Includes the following steps: Step 1: Aromatic dialdehyde and 3-dimethylaminopropylamine are added to the reaction solvent and refluxed to obtain a Schiff base intermediate solution. Step 2: Add a haloalkane to the Schiff base intermediate solution and stir to react, thus obtaining a dicationic surfactant.

11. The application of a dicationic surfactant according to any one of claims 1 to 9 as a bactericide for oil fields.

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