High-efficiency bactericide for oil field and preparation method of high-efficiency bactericide

Abstract

The invention relates to the technical field of oil field water treatment, and discloses an efficient bactericide for an oil field and a preparation method thereof.The bactericide comprises, by mass, 15%-30% of chitosan grafted quaternary ammonium quaternary phosphonium salt, 20%-35% of ethyl alcohol, 2%-10% of D-amino acid, 3%-5% of alkyl glycoside, 2%-5% of sodium chloride and the balance water. Wherein the chitosan grafted quaternary ammonium quaternary phosphonium salt is obtained by carrying out quaternization reaction on bromopropyl triphenyl phosphonium bromide and quinoline-4-carboxylic acid and then condensing carboxyl in the structure with amino of chitosan; the prepared efficient bactericide for the oil field has good synergism, is suitable for sterilization of sulfate reducing bacteria and also suitable for sterilization of saprophytic bacteria and iron bacteria, is high in sterilization rate and has excellent corrosion inhibition performance, the corrosion resistance is improved, meanwhile, the dosage of a corrosion inhibitor and the bactericide is effectively reduced, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield water treatment, in particular to a high-efficiency fungicide for oilfields and a preparation method thereof. Background Art

[0002] During oilfield exploitation, as the reservoir pressure gradually decreases, in order to ensure the stable output of crude oil, a large amount of water needs to be injected into the formation. However, since the injected water is recycled, the composition of the water becomes more and more complex over time, which provides a breeding ground for various bacteria such as sulfate-reducing bacteria (SRB), saprophytic bacteria (TGB) and iron bacteria (FB). At the same time, excessive reproduction and growth of bacteria will not only cause corrosion and damage to drilling equipment and injection pipelines, but also lead to blockage of pipelines and injection wells, reduce the pore permeability of the oil layer, hinder water injection and oil production, thereby increasing the injection pressure and directly affecting crude oil production. Therefore, in order to reduce the corrosion of bacteria on water pipelines, it is very important to efficiently kill bacteria attached to the scale layer of the pipeline.

[0003] To address this problem, sterilization treatment before wastewater reinjection is essential. However, the types of fungicides currently used in oilfield produced water are relatively single. Long-term use will not only cause bacteria to develop certain drug resistance, but also significantly reduce the effectiveness of the agents. Among the existing fungicide technologies, most of the currently used ones are quaternary ammonium salts, such as alkyl-modified quaternary ammonium salt fungicides, which have shown certain bactericidal effects. However, due to long-term use, bacteria have developed drug resistance, the efficacy has continued to decline, the amount of input has continued to increase, and the production costs have increased year by year, causing pollution to the environment. In addition, oilfield injection water contains many suspended particles, emulsified oil droplets and other negatively charged substances, which will interact with quaternary ammonium salts, making it unable to produce electrostatic attraction with cell walls, thereby reducing its bactericidal activity or even rendering it ineffective. Therefore, finding and developing an oilfield bactericide with high efficiency, broad spectrum, low dosage and high bactericidal efficiency has become a technical problem that needs to be solved urgently.

[0004] In view of this, the high-efficiency fungicide for oil fields prepared by the present invention aims to solve various problems existing in existing fungicides; the high-efficiency oilfield fungicide not only has a broad-spectrum bactericidal effect through specific components and preparation processes, but also can simultaneously achieve excellent corrosion inhibition function, thereby effectively reducing production costs and avoiding the problem of different system reagents affecting each other caused by adding fungicides and corrosion inhibitors separately. In addition, the preparation method of the present invention is simple, easy to operate, convenient for industrial application, and can achieve green and safe large-scale production, providing a new technical solution for solving the sterilization problem in oilfield wastewater treatment. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a high-efficiency fungicide for oil fields and a preparation method thereof, which has the characteristics of high fungicidal efficiency, simple components and good corrosion inhibition performance.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for preparing a high-efficiency fungicide for oil fields is carried out according to the following steps:

[0008] Step (1), chitosan is uniformly dispersed in distilled water, quaternary ammonium quaternary phosphonium quinoline intermediate, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide are added, and after stirring, the pH is adjusted to 5-6 with a hydrochloric acid aqueous solution, and the reaction is stirred. After the reaction is completed, the pH is adjusted to 8-9 with a sodium hydroxide aqueous solution. After the product is completely precipitated, it is dialyzed in distilled water for 5-7 days, and freeze-dried to obtain chitosan grafted quaternary ammonium quaternary phosphonium salt.

[0009] Step (2), adding 15-30% by mass of chitosan grafted quaternary ammonium quaternary phosphonium salt and 20-35% by mass of ethanol into a stirring kettle, stirring at 800-1000 r / min for 5-10 minutes, then adding 2-10% of D-amino acid, 3-5% of alkyl glycoside and 2-5% of sodium chloride, continuing to stir for 3-8 minutes, adding distilled water to 100%, stirring evenly, and obtaining a high-efficiency fungicide for oil fields.

[0010] Furthermore, in step (1), the mass ratio of chitosan, quaternary ammonium quaternary phosphonium quinoline intermediate, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, and N-hydroxysuccinimide is 100:20-30:5-8:2-4.

[0011] Furthermore, in step (1), the reaction temperature is 35-50° C. and the reaction time is 12-24 h.

[0012] Furthermore, in step (1), the mass fraction of the hydrochloric acid aqueous solution is 15-25%, and the mass fraction of the sodium hydroxide aqueous solution is 10-20%.

[0013] Furthermore, in step (2), the D-amino acid is any one of D-tyrosine, D-tryptophan or D-valine.

[0014] Furthermore, the preparation method of the quaternary ammonium quaternary phosphonium quinoline intermediate in step (1) is carried out according to the following steps: under a nitrogen atmosphere, bromopropyltriphenylphosphonium bromide and a solvent are added to a reaction flask, and after stirring evenly, quinoline-4-carboxylic acid is added, and the reaction is stirred. After the reaction is completed, the mixture is distilled under reduced pressure, and a mixed solution of ethyl acetate and ethanol is recrystallized to obtain a quaternary ammonium quaternary phosphonium quinoline intermediate.

[0015] Furthermore, the solvent is any one of N,N-dimethylformamide, N-methylpyrrolidone or cyclohexanone.

[0016] Furthermore, the mass ratio of bromopropyltriphenylphosphonium bromide to quinoline-4-carboxylic acid is 100:40-45.

[0017] Furthermore, the reaction temperature is 110-130°C, and the reaction time is 8-16h.

[0018] By adopting the above technical solution, the beneficial effects of the present invention are:

[0019] The present application firstly performs a quaternization reaction between bromopropyltriphenylphosphonium bromide and quinoline-4-carboxylic acid to obtain a quaternary ammonium quaternary phosphonium quinoline intermediate, then utilizes the carboxyl group in the structure to produce condensation with the amino group of chitosan to obtain chitosan-grafted quaternary ammonium quaternary phosphonium salt, and finally compounds it with D-amino acid, alkyl glycoside, etc. to obtain a high-efficiency fungicide for oil fields, which not only has good synergy, but also effectively reduces the amount of corrosion inhibitor and fungicide while improving the anti-corrosion performance, thereby reducing the production cost.

[0020] The positively charged organic cations in quaternary phosphonium salt compounds can be selectively adsorbed by negatively charged bacteria, hindering the semi-permeability of the cell membrane, entering the interior of the cell through osmosis and diffusion, inactivating the cell enzymes, preventing the production of protein enzymes, and thus denaturing the proteins, thereby achieving the purpose of killing bacterial cells; quaternary ammonium salt molecules are positively charged and can be adsorbed to the surface of negatively charged bacteria, and through interactions such as electrostatic forces and hydrogen bonds, they penetrate the cell wall and accumulate on the cell membrane; the stronger adsorption capacity of quaternary phosphonium salts helps to bring more quaternary ammonium salts to the bacterial surface, thereby enhancing the penetration ability and bactericidal effect of quaternary ammonium salts and promoting cell membrane damage: when quaternary ammonium salts and quaternary phosphonium salts act together on the bacterial cell membrane, they may produce a stronger cell membrane damage effect, leading to more leakage of intracellular substances and cell death, playing a synergistic bactericidal role; D-amino acids, as signal molecules, can bind to bacterial proteins, causing large-scale shedding of bacterial biofilms. At the same time, the lipophilic groups in D-amino acids can enter the bacterial cell membrane, destroy the cell wall, and denature bacterial proteins. This destructive effect can cause the internal substances of bacteria to leak out, affecting the normal metabolism and growth of bacteria, thereby achieving a bactericidal effect. Therefore, when D-amino acids are compounded with quaternary ammonium and quaternary phosphonium salt bactericides, the bactericidal rate can be significantly improved and the corrosion rate can be reduced.

[0021] Chitosan contains a large amount of S, O, N and other elements. The empty orbits of metal elements will form coordination bonds with their internal arc pairs of electrons, reducing the anodic reaction. Chitosan can also combine with ions on the surface of the substrate to form an outer protective film. At the same time, after chitosan is chemically grafted with quaternary ammonium quaternary phosphonium quinoline intermediates, the cations in its structure are easily electrostatically attracted to the negative charges on the metal surface, which improves the adsorption of chitosan and strengthens the formation of a protective film, thereby slowing down the corrosion of carbon steel coupons. D-amino acids can interact with the metal surface to form a protective film that can isolate the metal from direct contact with the corrosive medium, thereby reducing the corrosion rate. At the same time, they can also combine with Fe2+ on the metal surface to form an outer protective film, which can reduce the negative charge on the metal surface, reduce the reaction activity between the metal and the corrosive medium, and further improve the corrosion inhibition performance of the fungicide. DETAILED DESCRIPTION

[0022] For ease of understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive. Unless otherwise stated, the raw materials and reagents used in this application are all commercially available products, or can be prepared by known methods.

[0023] Preparation of bromopropyltriphenylphosphonium bromide: 1,3-dibromopropane and triphenylphosphine were mixed evenly in a molar ratio of 1:1.8, 20 mL of xylene was added, and the mixture was stirred and reacted at 100-140°C for 12-24 h under nitrogen protection, and the xylene was removed by filtration and vacuum drying. The crude product was dissolved in 140 mL of distilled water, and extracted twice with an equal volume of petroleum ether. The aqueous phase was rotary evaporated, and the solid product was recrystallized with a mixed solution (ethanol and acetone volume ratio of 3:2), and vacuum dried at room temperature to obtain bromopropyltriphenylphosphonium bromide (structural formula: ).

[0024] Quinoline-4-carboxylic acid, CAS number is 486-74-8.

[0025] Chitosan (viscosity 200-400 mPa·S), deacetylation degree 90%, was purchased from Shanghai Maikaier Biochemical Technology Co., Ltd.

[0026] Example 1

[0027] (1) Under nitrogen atmosphere, 35 g of bromopropyltriphenylphosphonium bromide and 210 mL of N,N-dimethylformamide were added to a reaction flask, stirred evenly, and then 14.7 g of quinoline-4-carboxylic acid was added. The mixture was reacted at 120° C. for 12 h, and distilled under reduced pressure. The mixture was recrystallized from a mixture of ethyl acetate and ethanol to obtain a quaternary ammonium quaternary phosphonium quinoline intermediate. The preparation reaction formula is as follows:

[0028]

[0029] (2) 100 g of chitosan was evenly dispersed in distilled water, 20 g of quaternary ammonium quaternary phosphonium quinoline intermediate, 6 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 3 g of N-hydroxysuccinimide were added, and the mixture was stirred evenly. The pH value was adjusted to 6 with a 20% by mass aqueous solution of hydrochloric acid, and the mixture was reacted at 40° C. for 16 h. The pH value was adjusted to 9 with a 15% by mass aqueous solution of sodium hydroxide. After the product was completely precipitated, it was dialyzed in distilled water for 6 days and freeze-dried to obtain chitosan grafted quaternary ammonium quaternary phosphonium salt.

[0030] (3) 15% by weight of chitosan grafted quaternary ammonium quaternary phosphonium salt and 30% by weight of ethanol are added to a stirring kettle and stirred at 900 r / min for 8 min. Then, 2% of D-tyrosine, 4% of alkyl glycoside and 3% of sodium chloride are added and stirred for 5 min. Then, 46% of distilled water is added to 100% and stirred evenly to obtain a highly effective fungicide for oil fields.

[0031] Example 2

[0032] (1) Under nitrogen atmosphere, 60 g of bromopropyltriphenylphosphonium bromide and 300 mL of N-methylpyrrolidone were added to a reaction flask, and after stirring, 24 g of quinoline-4-carboxylic acid was added, and the mixture was reacted at 130° C. for 8 h. The mixture was distilled under reduced pressure, and recrystallized from a mixture of ethyl acetate and ethanol to obtain a quaternary ammonium quaternary phosphonium quinoline intermediate.

[0033] (2) 100 g of chitosan was evenly dispersed in distilled water, 23 g of quaternary ammonium quaternary phosphonium quinoline intermediate, 5 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 2 g of N-hydroxysuccinimide were added, and the mixture was stirred evenly. The pH value was adjusted to 5 with a 25% by mass aqueous solution of hydrochloric acid, and the mixture was reacted at 50° C. for 12 h. The pH value was adjusted to 8 with a 20% by mass aqueous solution of sodium hydroxide. After the product was completely precipitated, it was dialyzed in distilled water for 7 days and freeze-dried to obtain chitosan grafted quaternary ammonium quaternary phosphonium salt.

[0034] (3) 18% by weight of chitosan grafted quaternary ammonium quaternary phosphonium salt and 20% by weight of ethanol are added to a stirring kettle and stirred at 1000 r / min for 5 min. Then, 4% of D-tyrosine, 3% of alkyl glycoside and 2% of sodium chloride are added and stirred for 3 min. Then, 53% of distilled water is added to 100% and stirred evenly to obtain a highly effective fungicide for oil fields.

[0035] Example 3

[0036] (1) Under a nitrogen atmosphere, 25 g of bromopropyltriphenylphosphonium bromide and 200 mL of cyclohexanone were added to a reaction flask, stirred evenly, and then 11.25 g of quinoline-4-carboxylic acid was added. The mixture was reacted at 110° C. for 16 h, and distilled under reduced pressure. The mixture was recrystallized from a mixture of ethyl acetate and ethanol to obtain a quaternary ammonium quaternary phosphonium quinoline intermediate.

[0037] (2) 100 g of chitosan was evenly dispersed in distilled water, 26 g of quaternary ammonium quaternary phosphonium quinoline intermediate, 8 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 4 g of N-hydroxysuccinimide were added, and the mixture was stirred evenly. The pH value was adjusted to 6 with a 15% by mass aqueous solution of hydrochloric acid, and the mixture was reacted at 35° C. for 24 h. The pH value was adjusted to 9 with a 10% by mass aqueous solution of sodium hydroxide. After the product was completely precipitated, it was dialyzed in distilled water for 5 days and freeze-dried to obtain chitosan grafted quaternary ammonium quaternary phosphonium salt.

[0038] (3) Add 22% by mass of chitosan grafted quaternary ammonium quaternary phosphonium salt and 35% by mass of ethanol into a stirring kettle, stir at 800 r / min for 10 min, then add 6% of D-valine, 5% of alkyl glycoside and 5% of sodium chloride, continue stirring for 8 min, add 27% of distilled water to 100%, stir evenly, and obtain a high-efficiency fungicide for oil fields.

[0039] Example 4

[0040] (1) Under nitrogen atmosphere, 40 g of bromopropyltriphenylphosphonium bromide and 280 mL of N,N-dimethylformamide were added to a reaction flask, stirred evenly, and then 16.4 g of quinoline-4-carboxylic acid was added. The mixture was reacted at 125° C. for 15 h, and distilled under reduced pressure. The mixture was recrystallized from a mixture of ethyl acetate and ethanol to obtain a quaternary ammonium quaternary phosphonium quinoline intermediate.

[0041] (2) 100 g of chitosan was evenly dispersed in distilled water, 28 g of quaternary ammonium quaternary phosphonium quinoline intermediate, 7 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 3 g of N-hydroxysuccinimide were added, and the mixture was stirred evenly. The pH value was adjusted to 6 with a 22% by mass aqueous solution of hydrochloric acid, and the mixture was reacted at 45° C. for 18 h. The pH value was adjusted to 8 with a 15% by mass aqueous solution of sodium hydroxide. After the product was completely precipitated, it was dialyzed in distilled water for 7 days and freeze-dried to obtain chitosan grafted quaternary ammonium quaternary phosphonium salt.

[0042] (3) Add 26% by mass of chitosan grafted quaternary ammonium quaternary phosphonium salt and 24% by mass of ethanol into a stirring kettle, stir at 850 r / min for 9 min, then add 8% of D-tyrosine, 4% of alkyl glycoside and 3% of sodium chloride, continue stirring for 7 min, add 35% of distilled water to 100%, stir evenly, and obtain a high-efficiency fungicide for oil fields.

[0043] Example 5

[0044] (1) Under nitrogen atmosphere, 15 g of bromopropyltriphenylphosphonium bromide and 102 mL of N-methylpyrrolidone were added to a reaction flask, stirred evenly, and then 6.6 g of quinoline-4-carboxylic acid was added. The mixture was reacted at 115° C. for 10 h, and distilled under reduced pressure. The mixture was recrystallized from a mixture of ethyl acetate and ethanol to obtain a quaternary ammonium quaternary phosphonium quinoline intermediate.

[0045] (2) 100 g of chitosan was evenly dispersed in distilled water, 30 g of quaternary ammonium quaternary phosphonium quinoline intermediate, 8 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 2 g of N-hydroxysuccinimide were added, and the mixture was stirred evenly. The pH value was adjusted to 5 with a 20% by mass aqueous solution of hydrochloric acid, and the mixture was reacted at 40° C. for 15 h. The pH value was adjusted to 9 with a 12% by mass aqueous solution of sodium hydroxide. After the product was completely precipitated, it was dialyzed in distilled water for 6 days and freeze-dried to obtain chitosan grafted quaternary ammonium quaternary phosphonium salt.

[0046] (3) Add 30% by mass of chitosan grafted quaternary ammonium quaternary phosphonium salt and 25% by mass of ethanol into a stirring kettle, stir at 1000 r / min for 10 min, then add 10% of D-tryptophan, 3% of alkyl glycoside and 2% of sodium chloride, continue stirring for 5 min, add 30% of distilled water to 100%, stir evenly, and obtain a high-efficiency fungicide for oil fields.

[0047] Comparative Example 1

[0048] 15% by mass of bromopropyltriphenylphosphonium bromide (prepared in Example 1) and 30% by mass of ethanol are added into a stirring kettle and stirred at 900 r / min for 8 min. Then, 2% of D-tyrosine, 4% of alkyl glycoside and 3% of sodium chloride are added and stirred for 5 min. Then, 46% of distilled water is added to 100% and stirred evenly to obtain a fungicide for oil fields.

[0049] Comparative Example 2

[0050] (1) 100 g of chitosan was evenly dispersed in distilled water, 20 g of quinoline-4-carboxylic acid, 6 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 3 g of N-hydroxysuccinimide were added, and the mixture was stirred evenly. The pH value was adjusted to 6 with a 20% aqueous hydrochloric acid solution, and the mixture was reacted at 40° C. for 16 h. The pH value was adjusted to 9 with a 15% aqueous sodium hydroxide solution. After the product was completely precipitated, the mixture was dialyzed in distilled water for 6 days and freeze-dried to obtain chitosan grafted quinoline.

[0051] (2) 15% by mass of chitosan grafted quinoline and 30% by mass of ethanol are added to a stirring kettle and stirred at 900 r / min for 8 min. Then, 2% of D-tyrosine, 4% of alkyl glycoside and 3% of sodium chloride are added and stirred for 5 min. Then, 46% of distilled water is added to 100% and stirred evenly to obtain a fungicide for oil fields.

[0052] Comparative Example 3

[0053] (3) Add 30% by mass of ethanol into a stirring kettle, stir at 900 r / min for 8 min, then add 4% of alkyl glycoside and 3% of sodium chloride, continue stirring for 5 min, add 63% of distilled water to 100%, stir evenly, and obtain a fungicide for oil fields.

[0054] Bactericidal performance test: The bactericide performance was evaluated using the bactericidal bottle method. The "Bactericide Performance Evaluation Method" and "Recommended Indicators and Analysis Methods for Water Quality of Clastic Reservoirs" were used as reference standards. Sulfate-reducing bacteria (SRB) strains were obtained from an oil production plant in Daqing Oilfield. The produced water from Dagang Oilfield was selected for the preparation of bacterial suspension. The bacteria and bactericide were in contact for 2 hours at 50°C. Iron bacteria (FB) and heterotrophic bacteria (TGB) strains were extracted from the circulating water on site of a chemical plant. The blank bacterial counts of TGB, SRB, and FB were 1.6×10 7 , 5×10 5 / mL and 7×10 4 / mL; the circulating water of the plant contains 28.6mg / L of Mg 2+ , 854 mg / L Cl - , 180mg / L HCO3 - , 270mg / L Ca 2+ , 220mg / L SO4 2- , 285mg / L of Na + The bacterial suspension was obtained by diluting the bacterial strain and the water sample at a volume ratio of 1:100.

[0055] Table 1 Bactericidal performance test

[0056]

[0057] It can be seen from the test results in the above table that with the increase of the content of chitosan grafted quaternary ammonium quaternary phosphonium salt and D-amino acid, the killing ability of the high-efficiency bactericide for oil fields prepared by the present invention on sulfate-reducing bacteria, saprophytes and iron bacteria is gradually enhanced, and can reach up to 100%. This is because on the one hand, the positively charged organic cations in the quaternary phosphonium salt compounds can be selectively adsorbed by negatively charged bacteria, hindering the semi-permeability of the cell membrane, entering the interior of the cell through penetration and diffusion, passivating the cell enzyme, and preventing the production of protein enzymes, thereby denaturing the protein and achieving the purpose of killing bacterial cells; the quaternary ammonium salt molecules are positively charged and can be adsorbed to the negatively charged bacterial surface, through electrostatic The quaternary ammonium salts interact with each other through forces such as hydrogen bonding and penetrating cell walls and accumulating on the cell membrane; the stronger adsorption capacity of quaternary phosphonium salts helps to bring more quaternary ammonium salts to the surface of bacteria, thereby enhancing the penetration ability and bactericidal effect of quaternary ammonium salts and promoting cell membrane damage: when quaternary ammonium salts and quaternary phosphonium salts act together on the bacterial cell membrane, they may produce a stronger cell membrane damage effect, leading to more leakage of intracellular substances and cell death, playing a synergistic bactericidal role; on the other hand, D-amino acids, as signal molecules, can bind to bacterial proteins, causing large-scale shedding of bacterial biofilms, and at the same time, the lipophilic groups in D-amino acids can enter the bacterial cell membrane, destroy the cell wall, and denature bacterial proteins. This destructive effect can cause the leakage of internal substances of bacteria, affect the normal metabolism and growth of bacteria, and thus achieve a bactericidal effect. Therefore, when D-amino acids are compounded with quaternary ammonium and quaternary phosphonium salt bactericides, they can significantly improve the bactericidal rate and reduce the corrosion rate.

[0058] Comparative Example 1 contains only quaternary phosphonium salt, and has limited bactericidal effect; Comparative Example 2 does not contain quaternary phosphonium quaternary ammonium salt, but contains D-amino acid and quinoline groups, and has certain bactericidal ability; Comparative Example 3 does not contain bactericidal groups, only contains alkyl glycoside, and has the weakest bactericidal performance.

[0059] Corrosion inhibition performance test: According to SY / T 5273-2014 "Performance Indicators and Evaluation Methods of Corrosion Inhibitors for Oilfield Produced Water Treatment", the coupon test was carried out: In order to fully simulate the local conditions, the coupons used in the test were all local reinjection water pipe steel models. First, the cleaned No. 20 carbon steel coupons were hung in 500mL simulated oilfield aqueous solution (where Na + 68000mg / L, Ca 2+ 11500mg / L, Mg 2+ 940mg / L, Cl - 128000mg / L, SO4 2- 100mg / L, HCO3 -is 100 mg / L), and the fungicide prepared in the embodiment and the comparative example is added, and then sealed and placed at 50°C for insulation for 3 days; after the test is completed, the solid corrosion products on the surface of the coupon are brushed off with a brush, and then rust is removed with 500 mL of 35% concentrated hydrochloric acid, 500 mL of deionized water and 3.5 g of hexamethylenetetramine, rinsed with distilled water, washed with alcohol and blown dry, and then placed in a dryer to be fully dried, and weighed with a precision electronic balance, and the corrosion rate and corrosion inhibition rate are calculated according to the mass change of the coupon in each group of tests before and after the test.

[0060] Table 2 Corrosion inhibition performance test

[0061]

[0062]

[0063] It can be seen from the test results in the above table that with the increase of the content of chitosan grafted quaternary ammonium quaternary phosphonium salt and D-amino acid, the corrosion rate of the high-efficiency fungicide for oil field prepared by the present invention on carbon steel at 50°C gradually decreases, and the corrosion inhibition rate is significantly improved. This is because, on the one hand, since chitosan contains a large amount of S, O, N and other elements, the empty orbits of the metal elements will form coordination bonds with the electrons of the internal arc, reducing the anodic reaction, and chitosan can be combined with the surface ions of the substrate to form an outer protective film. At the same time, after chitosan is chemically grafted with the quaternary ammonium quaternary phosphonium quinoline intermediate, the cations in its structure are easy to generate electrostatic attraction with the negative charge on the metal surface, thereby improving the adsorption of chitosan and strengthening the formation of the protective film, thereby slowing down the corrosion of the carbon steel hanging piece; on the other hand, the D-amino acid can interact with the metal surface to form a protective film, which can isolate the metal from direct contact with the corrosive medium, thereby reducing the corrosion rate, and can also be combined with Fe2+ on the metal surface to form an outer protective film, which can reduce the negative charge on the metal surface and reduce the reaction activity between the metal and the corrosive medium.

[0064] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for preparing a high-efficiency fungicide for oil fields, characterized in that: The preparation method is carried out according to the following steps: Step (1), chitosan is uniformly dispersed in distilled water, quaternary ammonium quaternary phosphonium quinoline intermediate, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide are added, and after stirring, the pH is adjusted to 5-6 with a hydrochloric acid aqueous solution, and the reaction is stirred. After the reaction is completed, the pH is adjusted to 8-9 with a sodium hydroxide aqueous solution. After the product is completely precipitated, it is dialyzed in distilled water for 5-7 days, and freeze-dried to obtain chitosan grafted quaternary ammonium quaternary phosphonium salt; Step (2), adding 15-30% by mass of chitosan grafted quaternary ammonium quaternary phosphonium salt and 20-35% by mass of ethanol into a stirring kettle, stirring at 800-1000 r / min for 5-10 minutes, then adding 2-10% of D-amino acid, 3-5% of alkyl glycoside and 2-5% of sodium chloride, continuing to stir for 3-8 minutes, adding distilled water to 100%, stirring evenly, and obtaining a high-efficiency fungicide for oil fields.

2. The method for preparing a high-efficiency fungicide for oil fields according to claim 1, characterized in that: In the step (1), the mass ratio of chitosan, quaternary ammonium quaternary phosphonium quinoline intermediate, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide is 100:20-30:5-8:2-4.

3. The method for preparing a high-efficiency fungicide for oil fields according to claim 1, characterized in that: In the step (1), the reaction temperature is 35-50° C. and the reaction time is 12-24 h.

4. The method for preparing a high-efficiency fungicide for oil fields according to claim 1, characterized in that: In the step (1), the mass fraction of the hydrochloric acid aqueous solution is 15-25%, and the mass fraction of the sodium hydroxide aqueous solution is 10-20%.

5. The method for preparing a high-efficiency fungicide for oil fields according to claim 1, characterized in that: In the step (2), the D-amino acid is any one of D-tyrosine, D-tryptophan or D-valine.

6. The method for preparing a high-efficiency fungicide for oil fields according to claim 1, characterized in that: The preparation method of the quaternary ammonium quaternary phosphonium quinoline intermediate in step (1) is carried out according to the following steps: under a nitrogen atmosphere, bromopropyltriphenylphosphonium bromide and a solvent are added to a reaction flask, and after stirring, quinoline-4-carboxylic acid is added, and the reaction is stirred. After the reaction is completed, vacuum distillation is performed, and a mixed solution of ethyl acetate and ethanol is recrystallized to obtain a quaternary ammonium quaternary phosphonium quinoline intermediate.

7. The method for preparing a high-efficiency fungicide for oil fields according to claim 6, characterized in that: The solvent is any one of N,N-dimethylformamide, N-methylpyrrolidone or cyclohexanone.

8. The method for preparing a high-efficiency fungicide for oil fields according to claim 6, characterized in that: The mass ratio of the bromopropyltriphenylphosphonium bromide to quinoline-4-carboxylic acid is 100:40-45.

9. The method for preparing a high-efficiency fungicide for oil fields according to claim 6, characterized in that: The reaction temperature is 110-130° C., and the reaction time is 8-16 hours.

10. A highly effective fungicide for oil fields, characterized in that: Obtained by the preparation method according to any one of claims 1 to 9.

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