Ionic liquid demulsifier as well as preparation method and application thereof

Abstract

The invention discloses an ionic liquid demulsifier as well as a preparation method and application thereof. The ionic liquid demulsifier disclosed by the invention has a structure as shown in a formula I, and in the formula I, m is equal to 1-16, n is equal to 3-5, and i is equal to 1-16. The ionic liquid demulsifier has excellent interfacial activity, and can quickly migrate to an oil-water interface to reduce the tension of the oil-water interface, so that an interfacial film composed of asphaltene is destroyed, and the demulsification process is promoted. The ionic liquid demulsifier provided by the invention has the characteristics of simple synthesis steps, small dosage, good acid-base tolerance, low demulsification temperature, high demulsification efficiency and the like, and can be used for demulsification of crude oil emulsion. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to the field of oilfield chemicals, and specifically relates to an ionic liquid demulsifier, a preparation method and application thereof, and a method for demulsifying crude oil emulsion using the same. Background Art

[0002] With the development of tertiary oil recovery technologies in the petroleum extraction industry, a series of methods for improving oil recovery, such as thermal oil displacement, miscible flooding, chemical flooding, and microbial flooding, have been widely applied to actual production. However, the use of these technologies inevitably generates a large amount of oil-water emulsions. An emulsion is a polydisperse system in which one or several liquids are dispersed in the form of droplets in a liquid immiscible with it. The water-in-oil emulsion is an emulsion with water as the dispersed phase and crude oil as the dispersion medium. Compounds such as gum acids, olefin naphthenes, etc. in crude oil and asphaltenes, waxy particles, etc. are the main emulsifiers of such emulsions. The factors affecting the formation and stability of emulsions are as follows: relatively high interfacial tension, formation of the oil-water interfacial film, formation of the diffusion double layer, adsorption of solid particles, production temperature, emulsion pH, and salinity. The existence of oil-water emulsions will not only reduce the service life of pipelines and increase storage and transportation risks, but also cause serious corrosion of production equipment during the crude oil production process. Therefore, it is necessary to demulsify the oil-water emulsion. The chemical demulsification method has received extensive attention in the petroleum industry due to its high efficiency and low dosage characteristics.

[0003] A chemical demulsifier is an amphiphilic compound with both a hydrophilic end and a hydrophobic end, used to decompose emulsions or mixtures of two immiscible substances (such as oil and water). Chemical demulsifiers usually act on the two-phase interface, reduce the interfacial tension between the two liquids, and may replace the emulsifiers located at the two-phase interface, causing the dispersed phase to coalesce and separate. Common crude oil demulsifiers can generally be divided into alkylphenol-formaldehyde resin block polyether demulsifiers and polyoxyethylene-polyoxypropylene demulsifiers. For example, CN115558096A discloses a polyether demulsifier synthesized from cardanol and ethylene oxide-propylene oxide. The synthesis process of this demulsifier requires the use of alkali metal catalysts and high-temperature conditions, and the optimal demulsification efficiency is 82%; CN116103059A synthesizes a demulsifier using propylene oxide, ethylene oxide, and nonylphenol as the main raw materials under high-temperature and high-pressure conditions with formaldehyde potassium hydroxide as the catalyst; CN115124709A discloses a polyether demulsifier with decyltetradecanol as the initiator, mainly using decyltetradecanol, propylene oxide, and ethylene oxide as raw materials, and carrying out polymerization reactions in sequence under high pressure and the action of a catalyst to obtain the polyether demulsifier, and the demulsification efficiency at 80°C is 92.7%. However, the synthesis processes of the above demulsifiers are complex and have certain risks, and there are a series of problems such as a large dosage, poor dehydration rate, and high demulsification temperature. Summary of the Invention

[0004] The object of the present invention is to overcome the problems in existing demulsifiers, such as insufficient acid-base-salt tolerance, flocculation and coalescence ability, and demulsification effect. The present invention provides an ionic liquid demulsifier, its preparation method and application. The ionic liquid demulsifier has good acid-base tolerance, low demulsification temperature, high demulsification efficiency, and excellent interfacial activity. It can quickly migrate to the oil-water interface to reduce the oil-water interfacial tension, thereby destroying the interfacial film composed of asphaltenes and promoting the occurrence of the demulsification process.

[0005] To achieve the above object, in the first aspect of the present invention, an ionic liquid demulsifier is provided. The ionic liquid demulsifier contains the structure shown in Formula I.

[0006]

[0007] In Formula I, m = 1 - 16, n = 3 - 5, and i = 1 - 16.

[0008] In the second aspect of the present invention, a preparation method of an ionic liquid demulsifier is provided, which includes the following steps:

[0009] Perform a first reaction on ethanolamine and polyethylene glycol diglycidyl ether to obtain a first intermediate product.

[0010] Perform a second reaction on the obtained first intermediate product and a primary amine to obtain a second intermediate product.

[0011] Perform an ionization reaction on the obtained second intermediate product and an alkyl halide to obtain the ionic liquid demulsifier.

[0012] In the third aspect of the present invention, an ionic liquid demulsifier prepared by the preparation method described in the second aspect is provided.

[0013] In the fourth aspect of the present invention, the application of the ionic liquid demulsifiers described in the first aspect and the third aspect in the demulsification of crude oil emulsions is provided.

[0014] In the fifth aspect of the present invention, a method for demulsifying crude oil emulsions is provided. The method includes the following steps:

[0015] Dissolve the ionic liquid demulsifiers described in the first aspect and the third aspect in a solvent to obtain a demulsifier solution; then mix the demulsifier solution with the crude oil emulsion and let it stand.

[0016] Through the above technical solutions, the beneficial technical effects obtained by the present invention are as follows:

[0017] The ionic liquid demulsifier provided by the present invention has excellent interfacial activity, can quickly migrate to the oil-water interface to reduce the oil-water interfacial tension, thereby destroying the interfacial film composed of asphaltenes and promoting the occurrence of the demulsification process.

[0018] The demulsifier of ionic liquid provided by the present invention has the characteristics of simple synthesis steps, low dosage, good acid and alkali tolerance, low demulsification temperature, high demulsification efficiency, etc. Description of the Drawings

[0019] Figure 1 It is the infrared spectrogram of the demulsifier prepared in Example 1. Detailed Embodiments

[0020] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0021] The first aspect of the present invention provides a demulsifier of ionic liquid, and the demulsifier of ionic liquid contains the structure shown in Formula I.

[0022]

[0023] In Formula I, m = 1 - 16, n = 3 - 5, i = 1 - 16.

[0024] The demulsifier of ionic liquid provided by the present invention contains the structure shown in Formula I. This structure uses the polyethylene glycol chain segment connected by ethanolamine as the hydrophilic center, with hydrophobic long chains connected at both ends. At the same time, the hydrophilic structure center is modified with hydrophobic long chains and given a cationic active center. The whole structure has the characteristics that the hydrophilic groups are relatively concentrated, the hydrophobic long chains are relatively dispersed, and there is a cationic active center. This demulsifier of ionic liquid has excellent interfacial activity and the ability to reduce interfacial tension, can quickly migrate to the oil-water interface to reduce the oil-water interfacial tension, and then destroy the interfacial film composed of asphaltenes, promoting the demulsification process. In addition, this demulsifier of ionic liquid also has the characteristics of good acid and alkali tolerance, low demulsification temperature, high demulsification efficiency, etc.

[0025] The demulsifier of ionic liquid provided by the present invention has good migration ability, interfacial adsorption ability and interfacial tension reduction ability, which is beneficial to the occurrence of the demulsification process.

[0026] According to the present invention, the value of m is the number of carbon atoms of primary amine minus 2, the value of n is 3 when it is 0.7, 4 when it is 0.8, and the value of i is the number of carbon atoms of halogenated hydrocarbon minus 2.

[0027] In some embodiments of the present invention, in Formula I, m = 5 - 15, n = 3 - 4, i = 5 - 15.

[0028] The second aspect of the present invention provides a preparation method of a demulsifier of ionic liquid, including the following steps:

[0029] React ethanolamine with polyethylene glycol diglycidyl ether in a first reaction to obtain a first intermediate product;

[0030] React the obtained first intermediate product with a primary amine in a second reaction to obtain a second intermediate product;

[0031] React the obtained second intermediate product with an alkyl halide in an ionization reaction to obtain the ionic liquid demulsifier.

[0032] In the present invention, this reaction mainly uses ethanolamine as the structural intermediate. By regulating the addition amount of polyethylene glycol diglycidyl ether, the length of the fatty chains at both ends and in the middle, the hydrophilic-hydrophobic property of the whole molecule is adjusted.

[0033] In the present invention, the epoxy value of polyethylene glycol diglycidyl ether is 0.7 - 0.8 mol / 100 g.

[0034] In the present invention, the molar ratio of the ethanolamine to the polyethylene glycol diglycidyl ether is preferably 1:2; the molar ratio of the first intermediate product to the primary amine is preferably 1:2.

[0035] In some embodiments of the present invention, the primary amine is selected from one or more of n-octylamine, n-decylamine, dodecylamine, tetradecylamine, hexadecylamine, and octadecylamine.

[0036] In some embodiments of the present invention, the alkyl halide is selected from one or more of chloroalkanes, bromoalkanes, and iodoalkanes.

[0037] In some embodiments of the present invention, the chloroalkane is selected from one or more of n-pentyl chloride, n-hexyl chloride, dodecyl chloride, tetradecyl chloride, and octadecyl chloride.

[0038] In some embodiments of the present invention, the bromoalkane is selected from one or more of 1-bromopropane, n-butyl bromide, 1-bromoheptane, dodecyl bromide, tetradecyl bromide, and 1-bromooctadecane.

[0039] In some embodiments of the present invention, the iodoalkane is selected from one or more of isopropyl iodide, n-butyl iodide, and 1-iodopentane.

[0040] In some embodiments of the present invention, the molar amounts of the second intermediate product and the alkyl halide are equal.

[0041] In some embodiments of the present invention, the conditions of the first reaction include: the reaction temperature is 100 - 130 °C, and the reaction time is 4 - 8 h.

[0042] In some embodiments of the present invention, the conditions for the second reaction include: a reaction temperature of 100 to 130 °C and a reaction time of 4 to 10 h.

[0043] In some embodiments of the present invention, the conditions for the ionization reaction include: a reaction temperature of 40 to 80 °C and a reaction time of 6 to 12 h.

[0044] In some embodiments of the present invention, the first reaction is carried out in an organic solvent, and the organic solvent is selected from one or more of N,N-dimethylformamide, toluene, and xylene.

[0045] In the present invention, the organic solvent is added at the beginning of the first reaction.

[0046] In the method of the present invention, the raw materials of the ionic liquid demulsifier are easily available, the preparation conditions are simple, and the hydrophilic-hydrophobic properties of the molecular structure can be adjusted by adjusting the carbon chain length at different positions, so as to achieve the purpose of separating oil and water in different oil-water emulsions.

[0047] In the third aspect of the present invention, there is provided an ionic liquid demulsifier prepared by the preparation method described in the second aspect above.

[0048] The ionic liquid demulsifier provided by the present invention has the characteristics of simple synthesis steps, small dosage, good acid-base tolerance, low demulsification temperature, high demulsification efficiency, etc., and can be used for demulsifying crude oil emulsions.

[0049] In the fourth aspect of the present invention, there is provided the application of the ionic liquid demulsifier described in the first aspect and the third aspect above in demulsifying crude oil emulsions.

[0050] In the fifth aspect of the present invention, there is provided a method for demulsifying crude oil emulsions, and the method includes the following steps:

[0051] Dissolve the ionic liquid demulsifier described in the first aspect and the third aspect above in a solvent to obtain a demulsifier solution; then mix the demulsifier solution with the crude oil emulsion and let it stand.

[0052] After demulsification using the ionic liquid demulsifier of the present invention, the oil-water interface is clear, the water phase is clear, and the water content in the oil phase is small.

[0053] In some embodiments of the present invention, the temperature for standing is 40 to 70 °C and the time is 0.5 h to 4 h.

[0054] In some embodiments of the present invention, the solvent is at least one of water, ethanol, toluene, and xylene.

[0055] In some embodiments of the present invention, the concentration of the ionic liquid demulsifier in the crude oil emulsion is 100 to 500 mg / L.

[0056] The present invention will be described in detail below with reference to examples.

[0057] For the following examples and comparative examples where specific conditions are not indicated, they are carried out under conventional conditions or conditions recommended by the manufacturer. For reagents or instruments whose manufacturers are not indicated, they are all conventional products that can be obtained through commercial channels.

[0058] Demulsification efficiency: It is characterized by measuring its dehydration rate, and the detection method for the performance of crude oil demulsifiers (bottle test method) of the petroleum and natural gas industry standard SY / T 5281 - 2000 of the People's Republic of China is adopted.

[0059] Example 1

[0060] This example provides an ionic liquid demulsifier, and the preparation method of this ionic liquid demulsifier specifically includes the following steps:

[0061] (1) Under a nitrogen atmosphere, 2 mol of polyethylene glycol diglycidyl ether (epoxy value: 0.7 mol / 100 g) was added dropwise to 1 mol of ethanolamine, 10 mL of N,N - dimethylformamide was added and mixed evenly, and the reaction was carried out at 120 °C for 6 h to obtain a first intermediate product;

[0062] (2) The above - obtained first intermediate product was mixed evenly with 2 mol of dodecylamine reagent, and the reaction was carried out at 120 °C for 8 h to obtain a second intermediate product;

[0063] (3) 1 mol of dodecyl bromide was added to the above - obtained second intermediate product, and the reaction was carried out at 60 °C for 10 h. After completion, the solvent N,N - dimethylformamide was removed by vacuum distillation to obtain the ionic liquid demulsifier.

[0064] Figure 1 It is the infrared spectrum of the demulsifier prepared in Example 1. As can be seen from Figure 1 it that the peak at 3344 cm -1 is caused by the stretching vibration of N - H. The peaks at 2925 cm -1 , 2852 cm -1 , and 1378 cm -1 are C - H stretching vibration peaks. The peaks at 1658 cm -1 , 881 cm -1 belong to the bending vibration of N - H. The peaks at 1251 cm -1 and 1099 cm -1 are caused by the stretching vibration of C - O - C. These results indicate that the target product has been successfully synthesized.

[0065] It was detected that the ionic liquid demulsifier obtained in this example contains the structure shown in Formula I, where m = 10, n = 3, and i = 10.

[0066] The above synthesis reaction is specifically as follows:

[0067]

[0068] Example 2

[0069] This example provides an ionic liquid demulsifier. The preparation method of the ionic liquid demulsifier specifically includes the following steps:

[0070] (1) Under a nitrogen atmosphere, 2 mol of polyethylene glycol diglycidyl ether (epoxy value: 0.7 mol / 100 g) was dropped into 1 mol of ethanolamine, 10 mL of N,N-dimethylformamide was added and mixed evenly, and the reaction was carried out at 100 °C for 8 h to obtain a first intermediate product;

[0071] (2) The first intermediate product obtained above was mixed evenly with 2 mol of n-octylamine reagent, and the reaction was carried out at 100 °C for 10 h to obtain a second intermediate product;

[0072] (3) 1 mol of tetradecyl bromide was added to the second intermediate product obtained above, and the reaction was carried out at 40 °C for 12 h. After the reaction was completed, the solvent N,N-dimethylformamide was removed by vacuum distillation to obtain the ionic liquid demulsifier.

[0073] After testing, the ionic liquid demulsifier obtained in this example contains the structure shown in Formula I, where m = 6, n = 3, and i = 12.

[0074] Example 3

[0075] This example provides an ionic liquid demulsifier. The preparation method of the ionic liquid demulsifier specifically includes the following steps:

[0076] (1) Under a nitrogen atmosphere, 2 mol of polyethylene glycol diglycidyl ether (epoxy value: 0.8 mol / 100 g) was dropped into 1 mol of ethanolamine, 10 mL of N,N-dimethylformamide was added and mixed evenly, and the reaction was carried out at 130 °C for 4 h to obtain a first intermediate product;

[0077] (2) The first intermediate product obtained above was mixed evenly with 2 mol of octadecylamine reagent, and the reaction was carried out at 130 °C for 6 h to obtain a second intermediate product;

[0078] (3) 1 mol of tetradecyl bromide was added to the second intermediate product obtained above, and the reaction was carried out at 80 °C for 6 h. After the reaction was completed, the solvent N,N-dimethylformamide was removed by vacuum distillation to obtain the ionic liquid demulsifier.

[0079] After testing, the ionic liquid demulsifier obtained in this example contains the structure shown in Formula I, where m = 16, n = 4, and i = 12.

[0080] Example 4

[0081] This example provides an ionic liquid demulsifier. The preparation method of the ionic liquid demulsifier specifically includes the following steps:

[0082] (1) Under a nitrogen atmosphere, 2 mol of polyethylene glycol diglycidyl ether (epoxy value: 0.8 mol / 100 g) was dropped into 1 mol of ethanolamine, 10 mL of N,N-dimethylformamide was added and mixed evenly, and the reaction was carried out at 120 °C for 4 h to obtain a first intermediate product;

[0083] (2) The first intermediate product obtained above was mixed evenly with 2 mol of n-decylamine, and the reaction was carried out at 120 °C for 10 h to obtain a second intermediate product;

[0084] (3) 1 mol of 1-bromoheptane was added to the second intermediate product obtained above, and the reaction was carried out at 60 °C for 12 h. After the reaction was completed, the solvent N,N-dimethylformamide was removed by distillation under reduced pressure to obtain the ionic liquid demulsifier.

[0085] After testing, the ionic liquid demulsifier obtained in this example contains the structure shown in Formula I, where m = 8, n = 4, and i = 5.

[0086] Example 5

[0087] The ionic liquid demulsifier was prepared according to the method of Example 1, except that in step (3): 1 mol of dodecyl chloride was added to the second intermediate product obtained above, and the reaction was carried out at 60 °C for 12 h. After completion, the solvent N,N-dimethylformamide was removed by distillation under reduced pressure to obtain the ionic liquid demulsifier; the remaining steps were the same as those in Example 1. The results are shown in Table 1.

[0088] Comparative Example 1

[0089] The demulsification effect of the commercial demulsifier PDB 9360 was compared with that of the ionic liquid demulsifier synthesized in Example 1.

[0090] Comparative Example 2

[0091] The demulsification effect of the commercial demulsifier DI 18 was compared with that of the ionic liquid demulsifier synthesized in Example 1.

[0092] Test Example 1

[0093] Based on the ionic liquid demulsifiers prepared in Examples 1 to 5 and Comparative Examples 1 to 2, they were used to characterize the demulsification performance of the ionic liquid demulsifier in crude oil emulsions.

[0094] 150 parts by mass of crude oil (crude oil source: Changqing Oilfield, Yan'an, density at 25 °C: 0.862 g / cm3 ,asphaltene: 14.1 wt%, resin: 6.02 wt%, wax: 15.46%, water: 1.6 wt%) was added to 350 parts by mass of deionized water, stirred and mixed, heated to 70 °C, and then stirred at a speed of 11000 r / min for 20 minutes. This process was repeated three times until a stable water-in-oil emulsion was obtained.

[0095] The demulsifiers of Examples 1 to 5 and Comparative Examples 1 to 2 were added to ethanol to prepare demulsifier solutions with a mass fraction of 0.8%, namely Experimental Groups 1 to 5 and Comparative Groups 1 to 2.

[0096] 1 volume part of the above demulsifier solution was added to 20 volume parts of the crude oil emulsion, and then it was oscillated at 2500 rpm for 2 min with a high-frequency oscillator to make it mix evenly. Then it was transferred to a water bath at 40 °C and left standing for 4 h. The demulsification efficiency was characterized by measuring its dehydration rate (refer to the Petroleum and Natural Gas Industry Standard SY / T 5281 - 2000 of the People's Republic of China). The results are shown in Table 1.

[0097] Table 1 Demulsification results of Experimental Groups 1 to 5 and Comparative Groups 1 to 2

[0098] Group Crude oil demulsifier (mg / L) Demulsification efficiency (%) Experimental group 1 400 100 Experimental group 2 400 96.4 Experimental group 3 400 94.3 Experimental group 4 400 87.5 Experimental group 5 400 100 Control group 1 400 52.6 Control group 2 400 69.7

[0099] Note: "Crude oil demulsifier (mg / L)" in the table refers to the concentration of the ionic liquid demulsifier in the crude oil emulsion.

[0100] As can be seen from Table 1, the ionic liquid demulsifiers prepared in Examples 1 to 5 all have very good demulsification performance. And the demulsification efficiency of Example 1 and Example 5 is the highest.

[0101] Test Example 2

[0102] Based on the ionic liquid demulsifier prepared in Example 1, demulsifier solutions with different concentrations were prepared to characterize the demulsification performance of crude oil demulsifiers with different concentrations in the crude oil emulsion.

[0103] 150 parts by mass of crude oil was added to 350 parts by mass of deionized water, stirred and mixed, heated to 70 °C, and then stirred at a speed of 11000 r / min for 20 minutes. This process was repeated three times until a stable water-in-oil emulsion was obtained to get the crude oil emulsion.

[0104] Different mass parts of the ionic liquid demulsifier prepared in Example 1 were added to ethanol to prepare demulsifier solutions with mass fractions of 1%, 0.8%, 0.6%, 0.4%, and 0.2% respectively. The obtained samples were denoted as Experimental Groups 6 to 10; the blank group was 0%, and the sample was denoted as the blank group.

[0105] Add 1 volume part of the above experimental groups 6 - 10 to 20 volume parts of the crude oil emulsion, then use a high-frequency oscillator to oscillate at 2500 rpm for 2 min to mix evenly, and then transfer it to a water bath at 40 °C and let it stand for 4 h, and measure its dehydration rate. The results are shown in Table 2.

[0106] Table 2 Demulsification results of experimental groups 6 - 10 and the blank group

[0107] Group Crude oil demulsifier (mg / L) Demulsification efficiency (%) Experimental group 6 500 100 Experimental group 7 400 100 Experimental group 8 300 33.1 Experimental group 9 200 10.5 Experimental group 10 100 0 Blank group 0 0

[0108] Note: "Crude oil demulsifier (mg / L)" in the table refers to the concentration of the ionic liquid demulsifier in the crude oil emulsion.

[0109] As can be seen from Table 2, the ionic liquid demulsifier provided by the present invention has good demulsification performance, and a demulsification efficiency of 100% can be achieved with a crude oil demulsifier of 400 mg / L.

[0110] Based on the demulsifier prepared in Example 1, experimental groups 11 - 14 were successively established in Test Example 3 to characterize the demulsification performance of the demulsifier at different temperatures and times.

[0111] Add 150 parts by mass of crude oil to 350 parts by mass of deionized water, stir and mix, heat to 70 °C, then stir at a speed of 11000 r / min for 20 minutes, and repeat this process three times until a stable water-in-oil emulsion is obtained to get the crude oil emulsion.

[0112] Add the ionic liquid demulsifier prepared in Example 1 to ethanol to prepare a demulsifier solution with a mass fraction of 0.8%.

[0113] Add 1 volume part of the above demulsifier solution to 20 volume parts of the crude oil emulsion, then use a high-frequency oscillator to oscillate at 2500 rpm for 2 min to mix evenly, and then transfer it to water baths set at different temperatures respectively and let it stand for 4 h, and measure its dehydration rate. The results are shown in Table 3.

[0114] Table 3 Demulsification results of experimental groups 11 - 14

[0115]

[0116] As can be seen from Table 3: The ionic liquid demulsifier provided by the present invention can reach a demulsification efficiency of 100% in 240 min at 40 °C, and reach 100% demulsification efficiency in 180 min at 60 °C and 70 °C.

[0117] Based on the demulsifier prepared in Example 1, experimental groups 15 - 21 were successively established in Test Example 4 to characterize the demulsification performance of the demulsifier under different pH conditions.

[0118] Add 150 parts by mass of crude oil to 350 parts by mass of deionized water, stir and mix, adjust the pH value by adding hydrochloric acid or sodium hydroxide, heat to 70 °C, then stir at a speed of 11,000 r / min for 20 minutes, and repeat this process three times until a stable water-in-oil emulsion is obtained to get the crude oil emulsion.

[0119] Add the demulsifier prepared in Example 1 to ethanol to prepare a demulsifier solution with a mass fraction of 0.8%.

[0120] Add 1 volume part of the above demulsifier solution to 20 volume parts of crude oil emulsions with different pH values, then use a high-frequency oscillator to oscillate at 2500 rpm for 2 min to mix them evenly, and then transfer them to a 40 °C water bath and let them stand for 4 h respectively, and measure their dehydration rates. The results are shown in Table 4.

[0121] Table 4 Demulsification results of experimental groups 15 - 21

[0122] Group pH Demulsification efficiency (%) Experimental group 15 2 13.9 Experimental group 16 4 90.6 Experimental group 17 6 100 Experimental group 18 7 100 Experimental group 19 8 98.9 Experimental group 20 10 96.4 Experimental group 21 12 91.7

[0123] As can be seen from Table 4: The ionic liquid demulsifier provided by the present invention has a high demulsification efficiency in strong acids and strong alkalis.

[0124] Based on the demulsifier prepared in Example 1, experimental groups 22 - 27 were successively established to characterize the demulsification performance of the demulsifier under salinity conditions.

[0125] Add 150 parts by mass of crude oil to 350 parts by mass of deionized water, stir and mix, adjust the salinity by adding sodium chloride, heat to 70 °C, then stir at a speed of 11,000 r / min for 20 minutes, and repeat this process three times until a stable water-in-oil emulsion is obtained to get the crude oil emulsion.

[0126] Add the crude oil demulsifier prepared in Example 1 to ethanol to prepare a demulsifier solution with a mass fraction of 0.8%.

[0127] Add 1 volume part of the above demulsifier solution to 20 volume parts of crude oil emulsions with different salinities, then use a high-frequency oscillator to oscillate at 2500 rpm for 2 min to mix them evenly, and then transfer them to a 40 °C water bath and let them stand for 4 h respectively, and measure their dehydration rates. The results are shown in Table 5.

[0128] Table 5 Demulsification results of experimental groups 22 - 27

[0129]

[0130]

[0131] As can be seen from Table 5, the demulsifier of ionic liquid provided by the present invention can have a stable demulsification efficiency under high salinity conditions, indicating that the demulsifier has high salt resistance.

[0132] The present invention provides a demulsifier of ionic liquid for low-temperature demulsification, which is applicable to the demulsification of crude oil emulsion, and has the characteristics of simple preparation method, low demulsification temperature and excellent demulsification performance.

[0133] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the technical concept scope of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. An ionic liquid demulsifier, characterized in that, The ionic liquid demulsifier contains the structure shown in Formula I, In Formula I, m = 1 - 16, n = 3 - 5, i = 1 - 16.

2. The demulsifier of ionic liquid according to claim 1, wherein In Formula I, m = 5 - 15, n = 3 - 4, i = 5 - 15.

3. A preparation method of an ionic liquid demulsifier, characterized in that, It includes the following steps: Carry out a first reaction on ethanolamine and polyethylene glycol diglycidyl ether to obtain a first intermediate product; Carry out a second reaction on the obtained first intermediate product and a primary amine to obtain a second intermediate product; Carry out an ionization reaction on the obtained second intermediate product and an alkyl halide to obtain the ionic liquid demulsifier.

4. The preparation method according to claim 3, wherein The primary amine is selected from one or more of n-octylamine, n-decylamine, dodecylamine, tetradecylamine, hexadecylamine and octadecylamine.

5. The preparation method according to claim 3, wherein, The alkyl halide is selected from one or more of chloroalkane, bromoalkane and iodoalkane.

6. The preparation method according to claim 5, wherein, The chloroalkane is selected from one or more of n-pentyl chloride, n-hexyl chloride, dodecyl chloride, tetradecyl chloride and octadecyl chloride; The bromoalkane is selected from one or more of 1-bromopropane, bromo-n-butane, 1-bromoheptane, dodecyl bromide, tetradecyl bromide and 1-bromooctadecane; The iodoalkane is selected from one or more of isopropyl iodide, n-butyl iodide and 1-iodopentane.

7. The preparation method according to any one of claims 3-6, wherein The conditions of the first reaction include: the reaction temperature is 100 - 130 °C, and the reaction time is 4 - 8 h; And / or, the conditions of the second reaction include: the reaction temperature is 100 - 130 °C, and the reaction time is 6 - 10 h.

8. The preparation method according to any one of claims 3-6, wherein, The conditions of the ionization reaction include: the reaction temperature is 40 - 80 °C, and the reaction time is 6 - 12 h; And / or, the first reaction is carried out in an organic solvent, and the organic solvent is selected from one or more of N,N-dimethylformamide, toluene and xylene.

9. An ionic liquid demulsifier prepared by the preparation method according to any one of claims 3 - 8.

10. The application of the ionic liquid demulsifier according to claim 1, 2 or 9 in demulsifying crude oil emulsion.

11. A method for demulsifying crude oil emulsion, characterized in that, The method includes the following steps: Dissolve the ionic liquid demulsifier according to claim 1, 2 or 9 in a solvent to obtain a demulsifier solution; then mix the demulsifier solution and the crude oil emulsion and let it stand.

12. The method according to claim 10, wherein, The temperature of the standing is 40 - 70 °C, and the time is 0.5 h - 4 h; And / or, the solvent is at least one of water, ethanol, toluene and xylene; And / or, the concentration of the ionic liquid demulsifier in the crude oil emulsion is 100 - 500 mg / L.

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