A corrosion inhibitor and bactericide for oil fields and its preparation method

Abstract

The application relates to the oil field chemical technology field, and particularly discloses an oil field corrosion and bactericidal treatment agent and a preparation method thereof, the preparation method comprises the following steps: (1) reacting epichlorohydrin, a long-chain alkyl tertiary amine and a nitroimidazole compound to obtain an imidazole heterocyclic double quaternary ammonium salt; (2) dissolving the imidazole heterocyclic double quaternary ammonium salt in an organic solvent to form an organic phase, dispersing quercetin-ovophospholipid in water to form an aqueous phase, mixing the organic phase and the aqueous phase, adding a composite emulsifier, uniformly stirring and obtaining the oil field corrosion and bactericidal treatment agent. The imidazole heterocyclic double quaternary ammonium salt is wrapped by quercetin-ovophospholipid to form a core-shell structure, the bactericidal performance of the agent is improved, and the oil field corrosion and bactericidal treatment agent is endowed with long-acting performance.

Description

Technical Field

[0001] This application relates to the field of oilfield chemical technology, and more specifically, it relates to an oilfield corrosion inhibitor and bactericide and its preparation method. Background Technology

[0002] With the continuous exploitation of oil fields, the corrosion caused by wastewater has become a major obstacle to production. Replacing pipelines and equipment results in production stoppages and material losses. Wastewater corrosion in oil fields is generally caused by harmful media such as chlorides in the water. - HCO3 - Corrosion is caused by salt ions, as well as CO2, H2S, O2, and bacteria (sulfate-reducing bacteria, iron bacteria, saprophytic bacteria, etc., with sulfate-reducing bacteria being the main culprit). Therefore, oilfields can effectively and economically achieve corrosion prevention and bacterial control by adding corrosion inhibitors and bactericides to produced fluids and reinjection water. As a result, adding corrosion inhibitors and bactericides has become an essential procedure in many domestic oilfields.

[0003] Currently, commonly used corrosion inhibitors in oilfield oil-water treatment include quaternary ammonium salts, amides, imidazolines, and other organic compounds containing N, P, and S, as well as a few inorganic corrosion inhibitors. Commonly used bactericides include quaternary ammonium salts, bisquaternary ammonium salts, polyquaternary ammonium salts, quaternary phosphonium salts, aldehydes, and some heterocyclic compounds. Dodecyl dimethyl benzyl ammonium chloride (1227) is the most commonly used and is economical and efficient. However, due to resistance and other reasons, the usage of this type of bactericide in offshore oilfields is gradually increasing. Other commonly used bactericides also have similar problems. Therefore, further technological improvements are needed, such as introducing functional groups or compounding new substances to improve effectiveness and reduce resistance.

[0004] Patent application CN110250194A discloses a composite bactericide and corrosion inhibitor for oilfields and its preparation method. The composite bactericide and corrosion inhibitor comprises, by mass: 18-35 parts of an intermediate, 10-20 parts of glutaraldehyde, 2-8 parts of thiourea, 5-10 parts of an alcohol solvent, and the remainder being water. The intermediate is prepared by adding oleic acid, naphthenic acid, and diethylenetriamine into a reaction vessel in a certain proportion. The oilfield uses a compound bactericide and corrosion inhibitor, which is based on oleic acid imidazoline quaternary ammonium salt, introduces naphthenic acid imidazoline acetate, and then combines it with thiourea, glutaraldehyde, etc. to form a compound bactericide. Thiourea is added, and although thiourea, as a sulfur-containing compound, has a strong corrosion inhibition and bactericidal effect, it will produce harmful gases and wastes during use, causing certain environmental pollution and limiting its application in offshore oilfields. At the same time, glutaraldehyde itself is flammable, toxic, has a strong irritating odor, can corrode the skin, is easily ignited and explosive when in contact with flammable materials, and is volatile and does not have a long-lasting effect. Summary of the Invention

[0005] In order to improve the environmental friendliness and long-lasting effect of corrosion inhibitors and bactericides, this application provides a corrosion inhibitor and bactericide for oil fields and its preparation method.

[0006] In a first aspect, this application provides a method for preparing a corrosion inhibitor and bactericide for oilfield use, employing the following technical solution:

[0007] A method for preparing a corrosion inhibitor and bactericide for oilfield use includes the following steps:

[0008] (1) Epichlorohydrin, long-chain alkyl tertiary amines and nitroimidazole compounds are reacted to obtain bis-quaternary ammonium salts containing imidazole heterocycles;

[0009] (2) The imidazole heterocyclic quaternary ammonium salt is dissolved in an organic solvent to form an organic phase, and quercetin-lecithin is dispersed in water to form an aqueous phase. The organic phase and the aqueous phase are mixed and a composite emulsifier is added to obtain an oilfield corrosion inhibitor-bactericidal treatment agent.

[0010] By adopting the above technical solution, this application combines a bis-quaternary ammonium salt bactericide with a nitroimidazole compound to form an imidazole heterocyclic bis-quaternary ammonium salt. The nitrogen atom on the imidazole ring reacts with an active quaternizing agent and a long-chain alkyl group to generate the bis-quaternary ammonium salt, improving its water solubility without destroying the imidazole ring structure. Introducing a nitrogen-containing heterocyclic group into the bis-quaternary ammonium salt not only retains the bactericidal properties of the imidazole ring but also significantly enhances its corrosion inhibition performance. This design, in addition to improving the water solubility, surface activity, and bactericidal properties of the imidazole ring compound, also endows the novel bis-quaternary ammonium salt compound with excellent corrosion inhibition capabilities, achieving a multi-purpose, low-dosage, and excellent bactericidal and corrosion-inhibiting effect. Furthermore, it does not contain thiourea or other sulfur-containing substances, reducing the corrosion risk during crude oil refining. It is particularly suitable for bacterial control and corrosion prevention in oil fields (especially offshore oil fields).

[0011] In addition, quercetin-lecithin has excellent antibacterial activity. This application forms a core-shell structure by encapsulating imidazole heterocyclic bisquaternary ammonium salt, which not only improves the bactericidal performance of the agent, but also buffers the release of imidazole heterocyclic bisquaternary ammonium salt, reduces its release rate, and prolongs the action time, thereby giving the corrosion-inhibiting and bactericidal treatment agent a long-lasting effect.

[0012] Preferably, the preparation method of the imidazole heterocyclic bis-quaternary ammonium salt includes the following steps:

[0013] Epichlorohydrin was heated to 75-85℃ and maintained at a constant temperature. A long-chain alkyl tertiary amine was added dropwise to the epichlorohydrin. After the addition was complete, the reaction was stirred. After the reaction was completed, the mixture was cooled to room temperature to obtain an intermediate. Acetonitrile was added to the intermediate and the mixture was heated to reflux with acetonitrile. Then, a nitroimidazole compound was added. After the nitroimidazole compound dissolved, the mixture was refluxed for 6-10 hours. The mixture was cooled to room temperature, and the mixture was distilled under reduced pressure, washed with acetone, filtered, and dried to obtain a bis-quaternary ammonium salt containing an imidazole heterocyclic ring.

[0014] The molar ratio of epichlorohydrin, long-chain alkyl tertiary amine, and nitroimidazole compound is 2:(1-1.2):(1-1.3).

[0015] The mass ratio of epichlorohydrin, acetonitrile and acetone is 1:(2.7-6):(3-5).

[0016] Preferably, the long-chain alkyl tertiary amine is one or more of dodecyl dimethyl tertiary amine, tetradecyl dimethyl tertiary amine, hexadecyl dimethyl tertiary amine, and dodecyl benzyl methyl tertiary amine.

[0017] Preferably, the nitroimidazole compound is one of metronidazole, tinidazole, and ornidazole, and more preferably ornidazole.

[0018] By adopting the above technical solution, the nitroimidazole compounds are solids, while the selected quaternizing reagents are all liquids. At the same time, the first step in the preparation of the target product is to generate a solid quaternary ammonium salt. If there is no solvent to dissolve the nitroimidazole compounds, the next step of the reaction will be difficult to proceed. Therefore, it is necessary to select a suitable solvent. Acetonitrile, as a polarizing agent, can not only dissolve quaternary ammonium salts and nitroimidazole compounds, but also is miscible with the quaternizing reagent, thereby enhancing the activity of the quaternizing reagent and promoting the quaternization reaction.

[0019] Since the σ bond in nitroimidazole compounds consists of two electrons and lacks aromaticity, it is relatively unstable and prone to ring-opening at excessively high temperatures or strong alkalinity. Therefore, the reaction temperature should not be too high, and it is more suitable to control it at around 80℃.

[0020] Epichlorohydrin, as a linker, has its hydroxyl functional groups participating in the reaction, which accelerates the reaction rate.

[0021] Ornidazole is a third-generation nitroimidazole derivative following metronidazole and tinidazole, and has superior bactericidal properties.

[0022] Preferably, the preparation method of the oilfield corrosion inhibitor-bactericide includes the following steps:

[0023] (1) Epichlorohydrin, long-chain alkyl tertiary amines and nitroimidazole compounds were reacted to obtain bisquaternary ammonium compounds containing imidazole heterocycles;

[0024] (2) The imidazole heterocyclic bisquaternary ammonium salt and pyridine quaternary ammonium salt are dissolved in an organic solvent to form an organic phase, and quercetin-lecithin is dispersed in water to form an aqueous phase. The organic phase and the aqueous phase are mixed and a composite emulsifier is added to obtain an oilfield corrosion inhibitor-bactericidal treatment agent.

[0025] By adopting the above technical solution, since nitroimidazole compounds are prone to ring-opening at excessively high temperatures, the corrosion inhibition and bactericidal effect of the imidazole heterocyclic bisquaternary ammonium salt formed at temperatures exceeding 90°C deteriorates. Since pyridine is aromatic, has good stability and high temperature resistance, the formed pyridine quaternary ammonium salt has the typical characteristics of cationic surfactants (such as hydrophilic-lipophilic balance, low critical micelle concentration, high surface activity and good compatibility), and also has unique positive charge characteristics and bactericidal properties. Therefore, this application found that after combining pyridine quaternary ammonium salt with it, not only can the applicable temperature range of the obtained corrosion inhibitor and bactericide be broadened, but it also has a better corrosion inhibition and bactericidal effect compared with adding it alone.

[0026] Preferably, the mass ratio of the imidazole heterocyclic bisquaternary ammonium salt to the pyridine quaternary ammonium salt is 1:(1-3).

[0027] Preferably, the method for preparing the pyridine quaternary ammonium salt includes the following steps:

[0028] At 0°C, bromoalkane and lithium metal were added to anhydrous diethyl ether and the reaction was stirred while maintaining the low temperature. Then, pyridine and toluene solution were added, the temperature was raised to 110-120°C, and the mixture was refluxed for 6-12 hours to synthesize α-alkylpyridine.

[0029] α-alkylpyridine and dibromohalane were mixed in ethanol or propanol solvent, heated to reflux, cooled to crystallize, filtered and dried to obtain pyridine quaternary ammonium salt;

[0030] The molar ratio of the bromoalkane to lithium metal is 1:(1-3).

[0031] The molar ratio of the dibromohaloalkane to α-alkylpyridine is 1:(2-3).

[0032] By adopting the above technical solution, the preparation method of this application is convenient to operate, has fewer steps and mild reaction conditions. The obtained pyridine quaternary ammonium salt not only has high surface activity and low critical micelle concentration, but also has excellent bactericidal and corrosion-inhibiting properties.

[0033] Preferably, the composite emulsifier is a mixture of emulsifier and emulsifying aid in a mass ratio of (2-3):1; the emulsifier is a mixture of Span-80 and Tween-80 in a ratio of (1-3):(7-9).

[0034] By adopting the above technical solution, Span-80 and Tween-80 have complementary characteristics. Both are nonionic surfactants. The combination of Span-80 and Tween-80 can form a more stable emulsion system, improving the dispersibility and emulsification effect of the system. At the same time, a suitable ratio can maximize the respective characteristics of both, so that they can achieve the best effect in use.

[0035] The combination of emulsifiers and emulsifying aids produces a synergistic effect, which can not only reduce surface tension, but also act as a corrosion inhibitor and bactericide, further enhancing the corrosion inhibition and bactericidal properties of corrosion inhibitor and bactericide treatment agents. It can also work synergistically with imidazole heterocyclic quaternary ammonium salts and pyridine quaternary ammonium salts to exert multiple corrosion inhibition and bactericidal effects.

[0036] Preferably, the emulsifying agent is one or more of dodecyltrimethylammonium bromide and tetradecyltrimethylammonium bromide; further, the emulsifying agent is a mixture of dodecyltrimethylammonium bromide and tetradecyltrimethylammonium bromide in a mass ratio of (5-7):(3-5).

[0037] By adopting the above technical solution, when studying the corrosion inhibition and bactericidal effect of emulsifying agents on oil fields, the corrosion inhibition and bactericidal film layer formed by imidazole heterocyclic bis-quaternary ammonium salt and pyridine quaternary ammonium salt has a large number of defects: when compounded with dodecyltrimethylammonium bromide, due to its relatively small steric hindrance, it can fill the defects of the film layer more fully, making the film layer denser; when compounded with tetradecyltrimethylammonium bromide, because the latter has a larger steric hindrance, its ability to fill defects is limited, resulting in larger voids in the film layer and poor compounding effect. Therefore, when the two are compounded, due to their difference in steric hindrance, they can fill the defects of the corrosion inhibition and bactericidal film layer formed by imidazole heterocyclic bis-quaternary ammonium salt and pyridine quaternary ammonium salt in a staggered manner, jointly improving corrosion inhibition and bactericidal properties, showing a good synergistic effect.

[0038] Preferably, the organic solvent is one of N,N-dimethylformamide, N-methylpyrrolidone, acetone, or dimethylacetamide.

[0039] Secondly, this application provides a corrosion inhibitor and bactericide for oilfield use, employing the following technical solution:

[0040] The corrosion inhibitor and bactericide for oil fields was prepared using the above-mentioned method.

[0041] In summary, this application has the following beneficial effects:

[0042] 1. This application effectively combines a bis-quaternary ammonium salt bactericide with nitroimidazole compounds to form an imidazole heterocyclic bis-quaternary ammonium salt. This not only achieves multiple uses with a single agent, but also requires a small dosage and exhibits excellent bactericidal and corrosion-inhibiting properties. Furthermore, it does not contain thiourea or other sulfur-containing substances, reducing the risk of corrosion during crude oil refining. Simultaneously, due to the excellent antibacterial effect of quercetin-lecithin, the core-shell structure formed by encapsulating the imidazole heterocyclic bis-quaternary ammonium salt with quercetin-lecithin not only improves the bactericidal activity of the agent, but also buffers the release of the imidazole heterocyclic bis-quaternary ammonium salt, reducing its release rate and extending its service life. This results in a long-lasting corrosion-inhibiting and bactericidal treatment agent.

[0043] 2. This application combines pyridine quaternary ammonium salt with imidazole heterocyclic bisquaternary ammonium salt, which not only improves the applicable temperature range of the resulting corrosion-inhibiting and bactericidal treatment agent, but also has a better corrosion-inhibiting and bactericidal effect compared with adding it alone.

[0044] 3. This application achieves a synergistic effect by combining emulsifiers and emulsifying aids, which can not only reduce surface tension, but also enhance corrosion inhibition and bactericidal properties as an aid, thereby further enhancing the bactericidal and corrosion inhibition properties of the corrosion inhibition and bactericidal treatment agent.

[0045] 4. The emulsifying agent used in this application is a combination of dodecyltrimethylammonium bromide and tetradecyltrimethylammonium bromide. Due to the steric hindrance difference between the two, they can fill the defects in the bactericidal-corrosion-inhibiting film layer formed by imidazole heterocyclic quaternary ammonium salt and pyridine quaternary ammonium salt, thus improving the corrosion inhibition and bactericidal properties and having a good synergistic effect. Detailed Implementation

[0046] The present application will be further described in detail below with reference to the embodiments. All raw materials involved in the present application can be obtained commercially.

[0047] Preparation Examples 1-3: Imidazole Heterocyclic Biquaternary Ammonium Salts

[0048] Preparation Example 1

[0049] This preparation example discloses a method for preparing an imidazole heterocyclic bis-quaternary ammonium salt. The specific process is as follows: 0.2 mol of epichlorohydrin is added to a four-necked flask, and the temperature is slowly raised to 80°C. While stirring, 0.1 mol of tetradecyl dimethyl tertiary amine is slowly added dropwise to the epichlorohydrin. The addition is completed in about 3 hours, and then the heating is stopped. After the solution is cooled, 50 g of acetonitrile is added, and the temperature is raised to 82°C to reflux the acetonitrile. Then, 0.1 mol of ornidazole is added to the reaction solution in three portions. After the ornidazole dissolves, the solution is refluxed for 8 hours. The solution gradually changes from yellow to reddish-brown. After cooling, the solvent and unreacted raw materials are removed by vacuum evaporation at room temperature to obtain a crude product. The crude product is then washed and filtered with 55.5 g of acetone to obtain a brown waxy solid product, which is the imidazole heterocyclic bis-quaternary ammonium salt.

[0050] Preparation Example 2

[0051] This preparation example discloses a method for preparing an imidazole heterocyclic bis-quaternary ammonium salt. The specific process is as follows: 0.2 mol of epichlorohydrin is added to a four-necked flask, and the temperature is slowly raised to 80°C. While stirring, 0.11 mol of tetradecyl dimethyl tertiary amine is slowly added dropwise to the epichlorohydrin. The addition is completed in about 3 hours, and the heating is stopped. After the solution is cooled, 83.3 g of acetonitrile is added, and the temperature is raised to reflux with acetonitrile. Then, 0.115 mol of ornidazole is added to the reaction solution in three portions. After the ornidazole dissolves, the reaction is refluxed for 8 hours. The solution gradually changes from yellow to reddish-brown. After cooling, the solvent and unreacted raw materials are removed by vacuum evaporation at room temperature to obtain a crude product. The crude product is then washed with 74 g of acetone and filtered to obtain a brown waxy solid product, which is the imidazole heterocyclic bis-quaternary ammonium salt.

[0052] Preparation Example 3

[0053] This preparation example discloses a method for preparing an imidazole heterocyclic bis-quaternary ammonium salt. The specific process is as follows: 0.2 mol of epichlorohydrin is added to a four-necked flask, and the temperature is slowly raised to 80°C. While stirring, 0.12 mol of tetradecyl dimethyl tertiary amine is slowly added dropwise to the epichlorohydrin. The addition is completed in about 3 hours, and then the heating is stopped. After the solution is cooled, 111 g of acetonitrile is added, and the temperature is raised to reflux with acetonitrile. Then, 0.13 mol of ornidazole is added to the reaction solution in three portions. After the ornidazole dissolves, the reaction is refluxed for 8 hours. The solution gradually changes from yellow to reddish-brown. After cooling, the solvent and unreacted raw materials are removed by vacuum evaporation at room temperature to obtain a crude product. The crude product is then washed and filtered with 92.5 g of acetone to obtain a brown waxy solid product, which is the imidazole heterocyclic bis-quaternary ammonium salt.

[0054] Preparation Examples 4-6: Pyridine Quaternary Ammonium Salts

[0055] Preparation Example 4

[0056] This preparation example discloses a method for preparing pyridine quaternary ammonium salt, the specific steps of which are as follows:

[0057] After rinsing the three-necked flask with nitrogen, 100 mL of anhydrous diethyl ether and 0.4 mol of lithium were added. While stirring, a mixture of 0.2 mol of bromododecane and 50 mL of anhydrous diethyl ether was added dropwise. The reaction was allowed to proceed for 1 h to ensure complete lithium reaction. The reaction temperature was controlled near the freezing point. 0.26 mol of pyridine and 50 mL of toluene were added dropwise. After reacting for 2 h, the temperature was raised to 110 °C and refluxed for 3 h. The mixture was then separated, washed, and dried. The low-boiling-point compounds were evaporated, and the corresponding fractions were collected by vacuum distillation. The fractions were then subjected to column chromatography (eluent: petroleum ether: ethyl acetate = 4:1) to obtain α-alkylpyridine.

[0058] 2.4 mol of α-alkylpyridine and 1 mol of 1,4-dibromobutane were dissolved in anhydrous ethanol and refluxed at 80 °C for 48 h. The anhydrous ethanol was evaporated, and then anhydrous acetone was added and the mixture was recrystallized twice under freeze to obtain a white solid. The solid was dried under reduced pressure at room temperature for 24 h in the presence of phosphorus pentoxide to obtain pyridine quaternary ammonium salt.

[0059] Preparation Example 5

[0060] This preparation example discloses a method for preparing pyridine quaternary ammonium salt, the specific steps of which are as follows:

[0061] After purging the three-necked flask with nitrogen, 50 mL of anhydrous diethyl ether and 0.2 mol of lithium were added. While stirring, a mixture of 0.2 mol of bromododecane and 50 mL of anhydrous diethyl ether was added dropwise. The reaction was allowed to proceed for 1 h to ensure complete lithium reaction. The reaction temperature was controlled near the freezing point. 0.26 mol of pyridine and 50 mL of toluene were added dropwise. After reacting for 2 h, the temperature was raised to 110 °C and refluxed for 3 h. The mixture was then separated, washed, and dried. The low-boiling-point compounds were evaporated, and the corresponding fractions were collected by vacuum distillation. The fractions were then subjected to column chromatography (eluent: petroleum ether: ethyl acetate = 4:1) to obtain α-alkylpyridine.

[0062] 2 mol of α-alkylpyridine and 1 mol of 1,4-dibromobutane were dissolved in anhydrous ethanol and refluxed at 80 °C for 48 h. The anhydrous ethanol was evaporated, and then anhydrous acetone was added and the mixture was recrystallized twice under freeze to obtain a white solid. The solid was dried under reduced pressure at room temperature for 24 h in the presence of phosphorus pentoxide to obtain pyridine quaternary ammonium salt.

[0063] Preparation Example 6

[0064] This preparation example discloses a method for preparing pyridine quaternary ammonium salt, the specific steps of which are as follows:

[0065] After rinsing the three-necked flask with nitrogen, add 150 mL of anhydrous diethyl ether and 0.6 mol of lithium. While stirring, add a mixture of 0.2 mol of bromododecane and 50 mL of anhydrous diethyl ether dropwise. React for 1 h to ensure complete lithium reaction. Control the reaction temperature near the freezing point, then add 0.26 mol of pyridine and 50 mL of toluene dropwise. After reacting for 2 h, raise the temperature to 110 °C and reflux for 3 h. Separate the liquid, wash, and dry the product sequentially. Evaporate the low-boiling-point compounds, collect the corresponding fractions by vacuum distillation, and then perform column chromatography (eluent: petroleum ether: ethyl acetate = 4:1) to obtain α-alkylpyridine.

[0066] 3 mol of α-alkylpyridine and 1 mol of 1,4-dibromobutane were dissolved in anhydrous ethanol and refluxed at 80 °C for 48 h. The anhydrous ethanol was evaporated, and then anhydrous acetone was added and the mixture was recrystallized twice under freeze to obtain a white solid. The solid was dried under reduced pressure at room temperature for 24 h in the presence of phosphorus pentoxide to obtain pyridine quaternary ammonium salt.

[0067] Example 1

[0068] This embodiment provides a method for preparing a corrosion inhibitor and bactericide for oilfield use, comprising the following steps:

[0069] (1) Dissolve 100g of imidazole heterocyclic quaternary ammonium salt in 600g of N,N-dimethylformamide to form an organic phase;

[0070] (2) Dissolve 500g of quercetin-lecithin in 1L of methanol, place it in a flask, evaporate to obtain a uniform lipid dry film, add 2L of distilled water, and sonicate in a water bath for 30min to form an aqueous phase;

[0071] (3) After mixing the organic phase and the aqueous phase, stir and intermittently sonicate in a water bath (2 min each time, 30 s interval, 10 cycles). After stopping sonication, stir for 2 h and then filter through a 0.5 μm microporous membrane to obtain sustained-release nanospheres.

[0072] (4) Add 200g of slow-release nanospheres to 10g of composite emulsifier and homogenize at room temperature for 1h under a pressure of 40MPa to obtain an oilfield corrosion inhibitor and bactericide.

[0073] The preparation method of quercetin-lecithin is as follows: 0.0488g of lecithin is dissolved in 50mL of tetrahydrofuran to obtain a pale yellow clear solution. Then, 0.0244g of quercetin is added and fully dissolved. The solution is refluxed in a water bath for 4 hours at a temperature controlled at 55℃. After the reaction is completed, the solution is distilled under reduced pressure and methanol is added. The solution is filtered, and the filtrate is distilled under reduced pressure and hexane is added to obtain a precipitate. The precipitate is filtered, washed with hexane, and dried in a vacuum drying oven at 40℃ for 3 hours to obtain quercetin-lecithin.

[0074] The composite emulsifier consists of 0.7g Span-80, 6g Tween-80, and 1g dodecyltrimethylammonium bromide.

[0075] The imidazole heterocyclic quaternary ammonium salt was prepared from Example 1.

[0076] Example 2

[0077] The difference between this embodiment and Example 1 is that the imidazole heterocyclic quaternary ammonium salt is derived from Preparation Example 2.

[0078] Everything else is the same as in Example 1.

[0079] Example 3

[0080] The difference between this embodiment and Example 1 is that the imidazole heterocyclic quaternary ammonium salt is derived from Preparation Example 3.

[0081] Everything else is the same as in Example 1.

[0082] Example 4

[0083] This embodiment provides a method for preparing a corrosion inhibitor and bactericide for oilfield use, comprising the following steps:

[0084] (1) Dissolve 50g of imidazole heterocyclic quaternary ammonium salt and 50g of pyridine quaternary ammonium salt in 600g of N,N-dimethylformamide to form an organic phase;

[0085] (2) Dissolve 500g of quercetin-lecithin in 1L of methanol, place it in a flask, evaporate to obtain a uniform lipid dry film, add 2L of distilled water, and sonicate in a water bath for 30min to form an aqueous phase;

[0086] (3) After mixing the organic phase and the aqueous phase, stir and intermittently sonicate in a water bath (2 min each time, 30 s interval, 10 cycles). After stopping sonication, stir for 2 h and then filter through a 0.5 μm microporous membrane to obtain sustained-release nanospheres.

[0087] (4) Add 200g of slow-release nanospheres to 10g of composite emulsifier and homogenize at room temperature for 1h under a pressure of 40MPa to obtain an oilfield corrosion inhibitor and bactericide.

[0088] The composite emulsifier consists of 0.7g Span-80, 6g Tween-80, and 1g dodecyltrimethylammonium bromide.

[0089] The imidazole heterocyclic quaternary ammonium salt was prepared in Example 2, and the pyridine quaternary ammonium salt was prepared in Example 4.

[0090] Example 5

[0091] The difference between this embodiment and Example 1 is that the pyridine quaternary ammonium salt is derived from Preparation Example 5.

[0092] The rest is the same as in Example 4.

[0093] Example 6

[0094] The difference between this embodiment and Example 1 is that the pyridine quaternary ammonium salt is derived from Preparation Example 6.

[0095] The rest is the same as in Example 4.

[0096] Example 7

[0097] The difference between this embodiment and Example 5 is that: (1) 33g of imidazole heterocyclic quaternary ammonium salt and 67g of pyridine quaternary ammonium salt are dissolved in 600g of N,N-dimethylformamide to form an organic phase;

[0098] The rest is the same as in Example 5.

[0099] Example 8

[0100] The difference between this embodiment and embodiment 5 is that: (2) 25g of imidazole heterocyclic quaternary ammonium salt and 75g of pyridine quaternary ammonium salt are dissolved in 600g of N,N-dimethylformamide to form an organic phase.

[0101] The rest is the same as in Example 5.

[0102] Example 9

[0103] This embodiment provides a method for preparing a corrosion inhibitor and bactericide for oilfield use, comprising the following steps:

[0104] (1) Dissolve 33g of imidazole heterocyclic quaternary ammonium salt and 67g of pyridine quaternary ammonium salt in 600g of N,N-dimethylformamide to form an organic phase;

[0105] (2) Dissolve 500g of quercetin-lecithin in 1L of methanol, place it in a flask, evaporate to obtain a uniform lipid dry film, add 2L of distilled water, and sonicate in a water bath for 30min to form an aqueous phase;

[0106] (3) After mixing the organic phase and the aqueous phase, stir and intermittently sonicate in a water bath (2 min each time, 30 s interval, 10 cycles). After stopping sonication, stir for 2 h and then filter through a 0.5 μm microporous membrane to obtain sustained-release nanospheres.

[0107] (4) Add 200g of slow-release nanospheres to 10g of composite emulsifier and homogenize at room temperature for 1h under a pressure of 40MPa to obtain an oilfield corrosion inhibitor and bactericide.

[0108] The composite emulsifier is a mixture of 0.7g Span-80, 6g Tween-80 and 1g tetradecyltrimethylammonium bromide.

[0109] The imidazole heterocyclic quaternary ammonium salt was prepared in Example 2, and the pyridine quaternary ammonium salt was prepared in Example 4.

[0110] Example 10

[0111] The difference between this embodiment and Embodiment 9 is that the composite emulsifier is 0.7g Span-80, 6g Tween-80, 0.5g dodecyltrimethylammonium bromide and 0.5g tetradecyltrimethylammonium bromide.

[0112] The rest is the same as in Example 9.

[0113] Example 11

[0114] The difference between this embodiment and Embodiment 9 is that the composite emulsifier is 0.7g Span-80, 6g Tween-80, 0.6g dodecyltrimethylammonium bromide and 0.4g tetradecyltrimethylammonium bromide.

[0115] The rest is the same as in Example 9.

[0116] Example 12

[0117] The difference between this embodiment and Embodiment 9 is that the composite emulsifier is 0.7g Span-80, 6g Tween-80, 0.7g dodecyltrimethylammonium bromide and 0.3g tetradecyltrimethylammonium bromide.

[0118] The rest is the same as in Example 9.

[0119] Example 13

[0120] The difference between this embodiment and Example 9 is that the composite emulsifier is 1.43g Span-80, 5.71g Tween-80, 1.72g dodecyltrimethylammonium bromide and 1.14g tetradecyltrimethylammonium bromide.

[0121] The rest is the same as in Example 9.

[0122] Example 14

[0123] The difference between this embodiment and Embodiment 9 is that the composite emulsifier is 2.25g Span-80, 5.25g Tween-80, 1.5g dodecyltrimethylammonium bromide and 1g tetradecyltrimethylammonium bromide.

[0124] The rest is the same as in Example 9.

[0125] Comparative Example 1

[0126] The oilfield corrosion inhibitor and bactericide used in this comparative example is an imidazole heterocyclic bis-quaternary ammonium salt, which is derived from Preparation Example 1.

[0127] Comparative Example 2

[0128] The oilfield corrosion inhibitor and bactericide used in this comparative example is pyridine quaternary ammonium salt, which is derived from preparation example 4.

[0129] Comparative Example 3

[0130] The oilfield corrosion inhibitor and bactericide used in this comparative example is a mixture of imidazole heterocyclic quaternary ammonium salt and pyridine quaternary ammonium salt in a mass ratio of 1:1, wherein the imidazole heterocyclic quaternary ammonium salt is from Preparation Example 1 and the pyridine quaternary ammonium salt is from Preparation Example 4.

[0131] Performance testing

[0132] The corrosion-inhibiting and bactericidal agents prepared in each embodiment and comparative example were diluted 1000 times with distilled water to obtain the agent.

[0133] (1) Sterilization test

[0134] The water used was injection water from a polymer injection station in an oilfield. Sulfate-reducing bacteria (SRB), saprophytic bacteria (TGB), and iron bacteria (FB) were laboratory-cultured as experimental strains. The bactericidal rate was evaluated according to Q / SY 17049-2020. 30 mg / L of the agent was added, and the test results are shown in Table 1.

[0135] (2) Corrosion inhibition experiment

[0136] The water is the injection water of a polymer injection station in an oilfield. The corrosion inhibition rate was evaluated according to Q / SY 17126-2019. 50 mg / L of reagent was added. Corrosion inhibition rate % = (corrosion rate without added corrosion inhibitor - corrosion rate) / corrosion rate without added corrosion inhibitor. The test results are shown in Table 1.

[0137] (3) Sustained-release experiment

[0138] With a corrosion inhibition efficiency of over 80%, the corrosion inhibition cycle time of the oilfield corrosion-inhibiting and bactericidal treatment agents prepared in each embodiment and comparative example was tested based on corrosion inhibition experiments.

[0139] Table 1 Performance test data of Examples 1-14 and Comparative Examples 1-3

[0140]

[0141] As can be seen from Example 1 and Comparative Example 1 or Example 4 and Comparative Example 3 and Table 1, the bactericidal effect of the corrosion-inhibiting and bactericidal treatment agents prepared in the examples is better than that of the comparative examples, and the agents have a long-lasting effect. This indicates that by forming a core-shell structure between the imidazole heterocyclic bisquaternary ammonium salt and quercetin-lecithin, this application utilizes the antibacterial effect of quercetin-lecithin itself to improve the bactericidal activity of the prepared agent. Moreover, after quercetin-lecithin encapsulates the imidazole heterocyclic bisquaternary ammonium salt, it can reduce the release rate of the imidazole heterocyclic bisquaternary ammonium salt and prolong its service life, thereby making the corrosion-inhibiting and bactericidal treatment agent have a long-lasting effect.

[0142] As can be seen from Examples 1 and 4 or Comparative Examples 1-3, this application improves the bactericidal and corrosion-inhibiting properties of the obtained corrosion-inhibiting and bactericidal treatment agent by compounding imidazole heterocyclic bis-quaternary ammonium salt and pyridine quaternary ammonium salt. Since nitroimidazole compounds are prone to ring-opening at excessively high temperatures, the corrosion-inhibiting effect of the imidazole heterocyclic bis-quaternary ammonium salt formed at temperatures exceeding 90°C deteriorates. Due to pyridine's aromaticity and good stability, it exhibits excellent high-temperature resistance, resulting in pyridine quaternary ammonium salt with high surface activity and good compounding properties. Compounding with pyridine quaternary ammonium salt not only expands the applicable temperature range of the obtained corrosion-inhibiting and bactericidal agent but also provides better corrosion-inhibiting and bactericidal effects compared to adding a single substance.

[0143] As can be seen from Examples 7, 9 and 10, the emulsifying agent used in this application is a mixture of dodecyltrimethylammonium bromide and tetradecyltrimethylammonium bromide, which can further improve the bactericidal and corrosion-inhibiting properties of the obtained corrosion-inhibiting and bactericidal treatment agent. The bactericidal-corrosion-inhibiting film formed by imidazole heterocyclic quaternary ammonium salts and pyridine quaternary ammonium salts has a large number of defects. When compounded with dodecyltrimethylammonium bromide, the relatively small steric hindrance of dodecyltrimethylammonium bromide allows it to fill the defects of the bactericidal-corrosion-inhibiting film formed by imidazole heterocyclic quaternary ammonium salts and pyridine quaternary ammonium salts more effectively, resulting in a denser film. When imidazole heterocyclic quaternary ammonium salts and pyridine quaternary ammonium salts are compounded with tetradecyltrimethylammonium bromide, the tetradecyltrimethylammonium bromide is larger than the dodecyltrimethylammonium bromide, limiting its ability to fill defects and creating larger voids in the film, leading to a poor compounding effect. However, when dodecyltrimethylammonium bromide and tetradecyltrimethylammonium bromide are compounded, due to their steric hindrance difference, they can fill the defects of the bactericidal-corrosion-inhibiting film formed by imidazole heterocyclic quaternary ammonium salts and pyridine quaternary ammonium salts through staggered filling, thus improving both corrosion inhibition and bactericidal properties, exhibiting a good synergistic effect.

[0144] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing an oilfield corrosion and bactericidal treatment agent, characterized in that, The method comprises the following steps: (1) reacting epichlorohydrin, long-chain alkyl tertiary amine and nitroimidazole compound to obtain imidazole heterocyclic double quaternary ammonium salt; (2) dissolving the imidazole heterocyclic double quaternary ammonium salt and pyridine quaternary ammonium salt in an organic solvent to form an organic phase, dissolving quercetin- lecithin in methanol, placing in a flask, evaporating to obtain a uniform lipid dry film, adding distilled water, ultrasonicating in a water bath, forming an aqueous phase; mixing the organic phase and the aqueous phase, stirring and intermittently ultrasonicating in a water bath, stopping ultrasonicating, filtering through a microporous filter after stirring to obtain slow-release nanometer microspheres; adding the slow-release nanometer microspheres into a composite emulsifier, homogenizing at room temperature under a pressure of 40Mpa to obtain an oilfield corrosion and sterilization treatment agent; The composite emulsifier is a mixture of an emulsifier and an emulsifying aid in a mass ratio of (2-3):1; The emulsifying aid is one or more of dodecyltrimethylammonium bromide and tetradecyltrimethylammonium bromide. The nitroimidazole compound is one of metronidazole, tinidazole and ornidazole. The preparation method of the quercetin- lecithin comprises the following steps:

2. The method for preparing the oilfield corrosion and bacteria inhibition treatment agent according to claim 1, characterized in that, The preparation method of the imidazole heterocyclic double quaternary ammonium salt comprises the following steps: The epichlorohydrin is heated to 75-85℃ and maintained at constant temperature, the long-chain alkyl tertiary amine is added dropwise into the epichlorohydrin, after the dropwise addition is completed, the reaction is stirred, after the reaction is completed, the intermediate is cooled to room temperature; acetonitrile is added into the intermediate and heated to acetonitrile reflux, then the nitroimidazole compound is added, after the nitroimidazole compound is dissolved, the reflux reaction is carried out for 6-10h, the temperature is cooled to room temperature, the imidazole heterocyclic double quaternary ammonium salt is obtained by distillation under reduced pressure, acetone washing, filtration and drying; The molar ratio of the epichlorohydrin, the long-chain alkyl tertiary amine and the nitroimidazole compound is 2:(1-1.2):(1-1.3); The mass ratio of the epichlorohydrin, acetonitrile and acetone is 1:(2.7-6):(3-5).

3. The method for preparing the corrosion and bactericidal treatment agent for oil field according to claim 2, characterized in that, The long-chain alkyl tertiary amine is one or more of dodecyl dimethyl tertiary amine, tetradecyl dimethyl tertiary amine, hexadecyl dimethyl tertiary amine and dodecyl benzyl methyl tertiary amine.

4. The method for preparing the corrosion and bacteria inhibition treatment agent for oilfields according to claim 1, characterized in that, The preparation method of the pyridine quaternary ammonium salt comprises the following steps: At 0℃, bromoalkane and metallic lithium are added into anhydrous ether, the mixture is stirred at low temperature, then pyridine and toluene solution are added, the temperature is increased to 110-120℃, and the mixture is refluxed for 6-12h to synthesize α-alkyl pyridine; After the α-alkyl pyridine and dibromo halogenated alkane are mixed in ethanol or propanol solvent and heated to reflux, the mixture is cooled to crystallize, filtered and dried to obtain the pyridine quaternary ammonium salt; The molar ratio of the bromoalkane and the metallic lithium is 1:(1-3). The molar ratio of the dibromo-haloalkane and the alpha-alkylpyridine is 1: (2-3).

5. The method for preparing the corrosion and bacteria inhibition treatment agent for oilfields according to claim 1, characterized in that, The emulsification aid is a mixture of dodecyltrimethylammonium bromide and tetradecyltrimethylammonium bromide with a mass ratio of (5-7):(3-5).

6. The method for preparing the corrosion and bacteria inhibition treatment agent for oilfields according to claim 1, characterized in that, The organic solvent is one of N,N-dimethylformamide, N-methylpyrrolidone, acetone or dimethylacetamide.

7. Oilfield corrosion-inhibiting-bactericidal treatment agent, characterized in that, The oilfield corrosion and bactericidal treatment agent is prepared by the preparation method of any one of claims 1-6.

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