Ionic liquid demulsifier and preparation method therefor and use thereof

Abstract

Disclosed in the present invention are an ionic liquid demulsifier and a preparation method therefor and a use thereof. The ionic liquid demulsifier of the present invention has a structure as shown in formula I, wherein in formula (I), m=1-16, n=3-5, and i=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 as to destroy an interface film composed of asphaltenes, and promote occurrence of a demulsification process. 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 and the like, and can be used for demulsifying crude oil emulsions.

Description

Ionic liquid demulsifier and its preparation method and application

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application No. 202410027802.5 filed on January 8, 2024, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the field of oilfield chemicals, in particular to an ionic liquid demulsifier, a preparation method and application thereof, and a method for demulsifying crude oil emulsion using the ionic liquid demulsifier. Background Art

[0004] With the development of tertiary oil recovery (TER) technologies in the oil and gas industry, a series of enhanced oil recovery methods, such as thermal flooding, miscible flooding, chemical flooding, and microbial flooding, have been widely applied in practical production. However, the use of these technologies inevitably generates large amounts of oil-water emulsions. An emulsion is a polydisperse system consisting of one or more liquids dispersed in a mutually immiscible liquid in the form of droplets. Oil-in-water emulsions are characterized by water as the dispersed phase and crude oil as the dispersion medium. Compounds such as colloidal acids, olefins and cycloalkanes in the crude oil, as well as asphaltenes and waxy particles, serve as the primary emulsifiers in these emulsions. Factors influencing the formation and stability of emulsions include high interfacial tension, the formation of an oil-water interfacial film, the formation of a diffuse double layer, the adsorption of solid particles, production temperature, emulsion pH, and salinity. The presence of oil-water emulsions not only reduces pipeline life and increases storage and transportation risks, but also leads to severe corrosion of production equipment during crude oil production. Therefore, demulsification of oil-water emulsions is necessary. Chemical demulsification methods have attracted widespread attention in the oil and gas industry due to their high efficiency and low production volume.

[0005] Chemical demulsifiers are amphiphilic compounds with both hydrophilic and hydrophobic ends, used to break down emulsions or mixtures of two immiscible liquids (such as oil and water). They typically act at the interface between the two liquids, reducing the interfacial tension between them. They may also displace the emulsifier at the interface, causing the dispersed phases to coalesce and separate. Common crude oil demulsifiers are generally categorized as alkylphenol-formaldehyde resin block polyether demulsifiers and polyoxyethylene-polyoxypropylene demulsifiers. For example, CN115558096A discloses a polyether demulsifier synthesized from cardanol, ethylene oxide, and propylene oxide. This demulsifier synthesis process requires the use of an alkali metal catalyst and high temperature conditions, resulting in an optimal demulsification efficiency of 82%. CN116103059A uses propylene oxide, ethylene oxide, and nonylphenol as the main raw materials and potassium formaldehyde hydroxide as a catalyst to synthesize a demulsifier under high temperature and high pressure conditions. CN115124709A discloses a polyether demulsifier using decyltetradecanol as an initiator. This polyether demulsifier is obtained by sequentially polymerizing decyltetradecanol, propylene oxide, and ethylene oxide under high pressure and a catalyst, achieving a demulsification efficiency of 92.7% at 80°C. However, the synthesis processes of these demulsifiers are complex and risky, with a series of problems such as large addition amounts, poor dehydration rates, and high demulsification temperatures.

[0006] Summary of the Invention

[0007] The purpose of the present invention is to overcome the problems of acid, alkali and salt tolerance, flocculation and agglomeration ability, and demulsification effect of demulsifiers in the prior art, and to provide an ionic liquid demulsifier and its preparation method and application. The ionic liquid demulsifier has the characteristics of good acid and alkali tolerance, low demulsification temperature, high demulsification efficiency, etc., and also 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 asphaltene, and promoting the occurrence of the demulsification process.

[0008] In order to achieve the above object, the first aspect of the present invention provides an ionic liquid demulsifier, wherein the ionic liquid demulsifier comprises a structure shown in Formula I,

[0009] In formula I, m=1-16, n=3-5, i=1-16.

[0010] A second aspect of the present invention provides a method for preparing an ionic liquid demulsifier, comprising the following steps:

[0011] performing a first reaction between ethanolamine and polyethylene glycol diglycidyl ether to obtain a first intermediate product;

[0012] The obtained first intermediate product is subjected to a second reaction with a primary amine to obtain a second intermediate product;

[0013] The obtained second intermediate product is subjected to an ionization reaction with an alkyl halide to obtain the ionic liquid demulsifier.

[0014] The third aspect of the present invention provides an ionic liquid demulsifier prepared by the preparation method described in the second aspect.

[0015] The fourth aspect of the present invention provides use of the ionic liquid demulsifier described in the first and third aspects in demulsifying crude oil emulsions.

[0016] A fifth aspect of the present invention provides a method for demulsifying a crude oil emulsion, the method comprising the following steps:

[0017] The ionic liquid demulsifiers described in the first and third aspects are dissolved in a solvent to obtain a demulsifier solution; the demulsifier solution is then mixed with a crude oil emulsion and allowed to stand.

[0018] Through the above technical solution, the beneficial technical effects achieved by the present invention are as follows:

[0019] The ionic liquid demulsifier provided by the present invention has excellent interfacial activity and can quickly migrate to the oil-water interface to reduce the oil-water interfacial tension, thereby destroying the interfacial film composed of asphaltene and promoting the occurrence of the demulsification process.

[0020] The ionic liquid demulsifier provided by the present invention has the characteristics of simple synthesis steps, small dosage, good acid and alkali tolerance, low demulsification temperature, high demulsification efficiency, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is an infrared spectrum of the demulsifier prepared in Example 1. DETAILED DESCRIPTION

[0022] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0023] The first aspect of the present invention provides an ionic liquid demulsifier, wherein the ionic liquid demulsifier comprises a structure shown in Formula I,

[0024] In formula I, m=1-16, n=3-5, i=1-16.

[0025] The ionic liquid demulsifier provided by the present invention contains the structure shown in Formula I, which uses a polyethylene glycol segment connected by ethanolamine as a hydrophilic center, with hydrophobic long chains connected at both ends. At the same time, the hydrophilic structure center is modified with a hydrophobic long chain and endowed with a cationic active center. The entire structure has relatively concentrated hydrophilic groups, relatively dispersed hydrophobic long chains, and has the characteristics of a cationic active center. The ionic liquid demulsifier has excellent interfacial activity and interfacial tension reduction ability, can quickly migrate to the oil-water interface to reduce the oil-water interfacial tension, and then destroy the interfacial film composed of asphaltene, promoting the demulsification process. In addition, the ionic liquid demulsifier also has the characteristics of good acid and alkali tolerance, low demulsification temperature, and high demulsification efficiency.

[0026] The ionic liquid demulsifier provided by the present invention has good migration ability, interface adsorption ability and interfacial tension reduction ability, which is conducive to the occurrence of the demulsification process.

[0027] According to the present invention, m in Formula I is derived from a primary amine, and its value is the carbon number of the primary amine minus 2. n is derived from polyethylene glycol diglycidyl ether and corresponds to the degree of polymerization of polyethylene glycol diglycidyl ether. Furthermore, the value of n is also related to the epoxy value of polyethylene glycol diglycidyl ether. Different epoxy values ​​correspond to the proportion of ethylene oxide groups in polyethylene glycol diglycidyl ether. An n value of 0.7 is 4, and 0.8 is 3, meaning that when the epoxy value of polyethylene glycol diglycidyl ether is 0.7 mol / 100 g, n is 4; when the epoxy value of polyethylene glycol diglycidyl ether is 0.8 mol / 100 g, n is 3. i is derived from the alkyl halide, and its value is the carbon number of the alkyl halide minus 2.

[0028] In some embodiments of the present invention, in Formula I, m=5-15, n=3-4, and i=5-15.

[0029] In some embodiments of the present invention, in Formula I, X is a halogen, selected from one or more of Cl, Br, and I.

[0030] A second aspect of the present invention provides a method for preparing an ionic liquid demulsifier, comprising the following steps:

[0031] performing a first reaction between ethanolamine and polyethylene glycol diglycidyl ether to obtain a first intermediate product;

[0032] The obtained first intermediate product is subjected to a second reaction with a primary amine to obtain a second intermediate product;

[0033] The obtained second intermediate product is subjected to an ionization reaction with an alkyl halide to obtain the ionic liquid demulsifier.

[0034] In the present invention, the reaction mainly uses ethanolamine as a structural intermediate, and the hydrophilicity and hydrophobicity of the entire molecule are adjusted by regulating the amount of polyethylene glycol diglycidyl ether added and the length of the fatty chains at both ends and in the middle of the structure.

[0035] In the present invention, the epoxy value of polyethylene glycol diglycidyl ether is 0.7-0.8 mol / 100g.

[0036] In the present invention, the degree of polymerization of polyethylene glycol diglycidyl ether is 3-5, preferably 3-4. The degree of polymerization of polyethylene glycol diglycidyl ether refers to the number of ethylene glycol repeating units in its molecule. When the epoxy value of polyethylene glycol diglycidyl ether is 0.7-0.8 mol / 100g, the degree of polymerization of polyethylene glycol diglycidyl ether is 3-4.

[0037] In the present invention, the molar ratio of ethanolamine to polyethylene glycol diglycidyl ether is 1:1.5-2.5, preferably 1:2; the molar ratio of the first intermediate product to the primary amine is 1:1.5-2.5, preferably 1:2.

[0038] In the present invention, the amount of primary amine used in the second reaction can also be added based on the molar amount of ethanolamine in the first reaction. Preferably, the molar ratio of ethanolamine to primary amine is 1:1.5-2.5, preferably 1:2.

[0039] 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. In the present invention, the primary amine is further preferably a linear primary amine.

[0040] In some embodiments of the present invention, the alkyl halide is selected from one or more of alkyl chloride, alkyl bromide and alkyl iodide. Preferably, the alkyl halide is a linear alkyl halide, wherein the halogen in the linear alkyl halide is substituted at the terminal group, and the number of substitutions is 1.

[0041] In some embodiments of the present invention, the chloroalkane is selected from one or more of n-pentane chloride, n-hexane chloride, dodecane chloride, tetradecane chloride and octadecane chloride.

[0042] In some embodiments of the present invention, the brominated alkane is selected from one or more of 1-bromopropane, n-butyl bromide, 1-bromoheptane, brominated dodecane, brominated tetradecane, and 1-bromooctadecane.

[0043] In some embodiments of the present invention, the iodinated alkyl is selected from one or more of iodinated isopropyl, iodinated n-butane, and 1-iodopentan.

[0044] In some embodiments of the present invention, the molar ratio of the second intermediate product to the alkyl halide is 1:1.5-2.5, preferably the molar amounts are equal.

[0045] In some embodiments of the present invention, the amount of alkyl halide used in the ionization reaction can also be added based on the molar amount of ethanolamine in the first reaction. Preferably, the molar ratio of ethanolamine to alkyl halide is 1:1.5-2.5, preferably equal in molar amount.

[0046] In some embodiments of the present invention, the conditions of the first reaction include: reaction temperature of 100-130° C., and reaction time of 4-8 h.

[0047] In some embodiments of the present invention, the conditions of the second reaction include: reaction temperature of 100-130° C., and reaction time of 4-10 h.

[0048] In some embodiments of the present invention, the conditions of the ionization reaction include: a reaction temperature of 40-80° C. and a reaction time of 6-12 h.

[0049] 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.

[0050] In the present invention, the organic solvent is added at the beginning of the first reaction. That is, in the present invention, the first reaction is carried out in the organic solvent. Based on 1 mol of ethanolamine, the amount of organic solvent added is 500-1500 mL, preferably 1000 mL.

[0051] In the present invention, after the first reaction is completed, the product separation is not required, and the primary amine can be directly added to carry out the second reaction. After the second reaction is completed, the product separation is also not required, and the alkyl halide can be directly added to carry out the ionization reaction.

[0052] In the method of the present invention, the raw materials of the ionic liquid demulsifier are easily available and the preparation conditions are simple. The hydrophilicity and hydrophobicity of the molecular structure can be adjusted by adjusting the carbon chain length at different positions, thereby achieving the purpose of oil-water separation for different oil-water emulsions.

[0053] The third aspect of the present invention provides an ionic liquid demulsifier prepared by the preparation method described in the second aspect.

[0054] The ionic liquid demulsifier provided by the present invention has the characteristics of simple synthesis steps, small dosage, good acid and alkali tolerance, low demulsification temperature, high demulsification efficiency, etc., and can be used for demulsification of crude oil emulsions.

[0055] The fourth aspect of the present invention provides use of the ionic liquid demulsifier described in the first and third aspects in demulsifying crude oil emulsions.

[0056] A fifth aspect of the present invention provides a method for demulsifying a crude oil emulsion, the method comprising the following steps:

[0057] The ionic liquid demulsifiers described in the first and third aspects are dissolved in a solvent to obtain a demulsifier solution; the demulsifier solution is then mixed with a crude oil emulsion and allowed to stand.

[0058] After the ionic liquid demulsifier of the present invention is used for demulsification, the oil-water interface is clear, the water phase is clear, and the water content in the oil phase is low.

[0059] In some embodiments of the present invention, the standing temperature is 40-70° C., and the standing time is 0.5 h-4 h.

[0060] In some embodiments of the present invention, the solvent is at least one of water, ethanol, toluene and xylene.

[0061] In some embodiments of the present invention, the concentration of the ionic liquid demulsifier in the crude oil emulsion is 100-500 mg / L, preferably 400-500 mg / L.

[0062] The present invention will be described in detail below through examples.

[0063] In the following examples and comparative examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or those recommended by the manufacturer. All reagents and instruments used, if no manufacturer is specified, are commercially available conventional products.

[0064] Demulsification efficiency: characterized by measuring its dehydration rate, using the People's Republic of China Petroleum and Natural Gas Industry Standard SY / T 5281-2000 Crude Oil Demulsifier Performance Test Method (Bottle Test Method).

[0065] Example 1

[0066] This embodiment provides an ionic liquid demulsifier, and the preparation method of the ionic liquid demulsifier specifically includes the following steps:

[0067] (1) Under nitrogen atmosphere, 2 mol of polyethylene glycol diglycidyl ether (epoxy value: 0.8 mol / 100 g, degree of polymerization: 3) was added dropwise to 1 mol of ethanolamine, and 1000 mL of N,N-dimethylformamide was added and mixed evenly. The mixture was reacted at 120° C. for 6 h to obtain a first intermediate product;

[0068] (2) The first intermediate product obtained above was mixed evenly with 2 mol of dodecylamine reagent, and reacted at 120° C. for 8 h to obtain a second intermediate product;

[0069] (3) Add 1 mol of bromododecane to the second intermediate product obtained above, and react at 60° C. for 10 h. After the reaction, remove the solvent N,N-dimethylformamide by distillation under reduced pressure to obtain an ionic liquid demulsifier.

[0070] Figure 1 is an infrared spectrum of the ionic liquid demulsifier prepared in Example 1. As shown in Figure 1, at 3344 cm -1 The peak at 2925cm is caused by the stretching vibration of NH. -1 , 2852cm -1 , 1378cm -1 The peak at 1658cm is the CH stretching vibration peak. -1 , 881cm -1 The peak at 1251 cm is attributed to NH bending vibration. -1 and 1099cm -1 The peak at is caused by the stretching vibration of C-O-C. These results indicate that the target product was successfully synthesized.

[0071] After testing, the ionic liquid demulsifier obtained in this example contains the structure shown in Formula I, wherein m=10, n=3, i=1, and X is Br.

[0072] The above synthesis reaction is specifically as follows:

[0073] Example 2

[0074] This embodiment provides an ionic liquid demulsifier, and the preparation method of the ionic liquid demulsifier specifically includes the following steps:

[0075] (1) Under nitrogen atmosphere, 2 mol of polyethylene glycol diglycidyl ether (epoxy value: 0.8 mol / 100 g, degree of polymerization: 3) was added dropwise to 1 mol of ethanolamine, and 1000 mL of N,N-dimethylformamide was added and mixed evenly. The mixture was reacted at 100° C. for 8 h to obtain the first intermediate product;

[0076] (2) The first intermediate product obtained above was mixed evenly with 2 mol of n-octylamine reagent, and reacted at 100° C. for 10 h to obtain a second intermediate product;

[0077] (3) Add 1 mol of bromotetradecane to the second intermediate product obtained above and react at 40° C. for 12 h. After the reaction is completed, the solvent N,N-dimethylformamide is removed by distillation under reduced pressure to obtain an ionic liquid demulsifier.

[0078] After testing, the ionic liquid demulsifier obtained in this example contains the structure shown in Formula I, wherein m=6, n=3, i=12, and X is Br.

[0079] Example 3

[0080] This embodiment provides an ionic liquid demulsifier, and the preparation method of the ionic liquid demulsifier specifically includes the following steps:

[0081] (1) Under nitrogen atmosphere, 2 mol of polyethylene glycol diglycidyl ether (epoxy value: 0.7 mol / 100 g, degree of polymerization: 4) was added dropwise to 1 mol of ethanolamine, and 1000 mL of N,N-dimethylformamide was added and mixed evenly. The mixture was reacted at 130° C. for 4 h to obtain the first intermediate product;

[0082] (2) The first intermediate product obtained above was mixed evenly with 1 mol of octadecylamine reagent, and reacted at 130° C. for 6 h to obtain a second intermediate product;

[0083] (3) Add 1 mol of bromotetradecane to the second intermediate product obtained above, react at 80° C. for 6 h, and remove the solvent N,N-dimethylformamide by distillation under reduced pressure after the reaction to obtain an ionic liquid demulsifier.

[0084] After testing, the ionic liquid demulsifier obtained in this example contains the structure shown in Formula I, wherein m=16, n=4, i=12, and X is Br.

[0085] Example 4

[0086] This embodiment provides an ionic liquid demulsifier, and the preparation method of the ionic liquid demulsifier specifically includes the following steps:

[0087] (1) Under nitrogen atmosphere, 2 mol of polyethylene glycol diglycidyl ether (epoxide value 0.7 mol / 100 g, degree of polymerization 4) was added dropwise to 1 mol of ethanolamine, and 1000 mL of N,N-dimethylformamide was added and mixed uniformly. The mixture was reacted at 120° C. for 4 h to obtain the first intermediate product;

[0088] (2) The first intermediate product obtained above was mixed evenly with 2 mol of n-decylamine, and the mixture was reacted at 120° C. for 10 h to obtain a second intermediate product;

[0089] (3) Add 1 mol of 1-bromoheptane to the second intermediate product obtained above and react at 60° C. for 12 h. After the reaction is completed, remove the solvent N,N-dimethylformamide by distillation under reduced pressure to obtain the ionic liquid demulsifier.

[0090] After testing, the ionic liquid demulsifier obtained in this example contains the structure shown in Formula I, wherein m=8, n=4, i=5, and X is Br.

[0091] Example 5

[0092] An ionic liquid demulsifier was prepared according to the method of Example 1, except that, in step (3), 1 mol of chlorododecane was added to the second intermediate product obtained above, and the reaction was carried out at 60° C. for 12 h. After the reaction, the solvent N,N-dimethylformamide was removed by distillation under reduced pressure to obtain an ionic liquid demulsifier; the remaining steps were the same as those of Example 1.

[0093] After testing, the ionic liquid demulsifier obtained in this example contains the structure shown in Formula I, wherein m=10, n=3, i=10, and X is Cl.

[0094] Comparative Example 1

[0095] The demulsification effects of the commercial demulsifier PDB 9360 and the ionic liquid demulsifier synthesized in Example 1 were compared.

[0096] Comparative Example 2

[0097] The demulsification effects of the commercial demulsifier DI 18 and the ionic liquid demulsifier synthesized in Example 1 were compared.

[0098] Test Example 1

[0099] The ionic liquid demulsifiers prepared in Examples 1-5 and the commercial demulsifiers in Comparative Examples 1-2 were used to characterize the demulsification performance of the ionic liquid demulsifiers in crude oil emulsions.

[0100] 150 parts by mass of crude oil (source: Changqing Oilfield, Yan'an, density at 25°C: 0.862 g / cm 3 , asphaltenes: 14.1 wt %, colloids: 6.02 wt %, waxes: 15.46 %, and water: 1.6 wt %) were added to 350 parts by mass of deionized water, stirred and mixed, heated to 70° C., and then stirred at a speed of 11,000 r / min for 20 minutes. This process was repeated three times until a stable water-in-oil emulsion, i.e., a crude oil emulsion, was obtained.

[0101] The ionic liquid demulsifiers prepared in Examples 1-5 and the demulsifiers in Comparative Examples 1-2 were added to ethanol to prepare demulsifier solutions with a mass fraction of 0.8%, namely, experimental groups 1-5 and comparative groups 1-2.

[0102] One part by volume of the above demulsifier solution was added to 20 parts by volume of the crude oil emulsion, and then shaken at 2500 rpm for 2 minutes using a high-frequency shaker to mix evenly. The mixture was then transferred to a 40°C water bath and allowed to stand for 4 hours. The demulsification efficiency was characterized by measuring its dehydration rate (referring to the Petroleum and Natural Gas Industry Standard SY / T5281-2000 of the People's Republic of China). The results are shown in Table 1.

[0103] Table 1 Demulsification results of experimental groups 1-5 and comparative groups 1-2

[0104] Note: "Crude oil demulsifier (mg / L)" in the table refers to the concentration of ionic liquid demulsifier in crude oil emulsion.

[0105] As shown in Table 1, the ionic liquid demulsifiers prepared in Examples 1-5 all have very good demulsification performance, and Example 1 and Example 5 have the highest demulsification efficiency.

[0106] Test Example 2

[0107] Based on the ionic liquid demulsifier prepared in Example 1, demulsifier solutions of different concentrations were prepared to characterize the demulsification performance of crude oil demulsifiers of different concentrations in crude oil emulsions.

[0108] 150 parts by mass of crude oil were added to 350 parts by mass of deionized water, stirred and mixed, heated to 70° C., and then stirred at a speed of 11,000 r / min for 20 minutes. This process was repeated three times until a stable water-in-oil emulsion was obtained, thereby obtaining a crude oil emulsion.

[0109] Different mass fractions 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 recorded as experimental groups 6-10; the blank group was 0%, and the samples were recorded as blank group.

[0110] One part by volume of the experimental groups 6-10 was added to 20 parts by volume of the crude oil emulsion, and then shaken at 2500 rpm for 2 minutes using a high-frequency shaker to mix evenly. The mixture was then transferred to a 40°C water bath and allowed to stand for 4 hours. The dehydration rate was measured, and the results are shown in Table 2.

[0111] Table 2 Demulsification results of experimental groups 6-10 and blank group

[0112] Note: "Crude oil demulsifier (mg / L)" in the table refers to the concentration of ionic liquid demulsifier in crude oil emulsion.

[0113] It can be seen from Table 2 that the ionic liquid demulsifier provided by the present invention has good demulsification performance. When the dosage of the crude oil demulsifier is 400 mg / L, the demulsification efficiency can reach 100%.

[0114] Test Example 3 Based on the demulsifier prepared in Example 1, experimental groups 11-14 were established in sequence to characterize the demulsification performance of the demulsifier at different temperatures and times.

[0115] 150 parts by mass of crude oil were added to 350 parts by mass of deionized water, stirred and mixed, heated to 70° C., and then stirred at a speed of 11,000 r / min for 20 minutes. This process was repeated three times until a stable water-in-oil emulsion was obtained, thereby obtaining a crude oil emulsion.

[0116] The ionic liquid demulsifier prepared in Example 1 was added to ethanol to prepare a demulsifier solution with a mass fraction of 0.8%.

[0117] One part by volume of the above demulsifier solution was added to 20 parts by volume of the crude oil emulsion, and then shaken at 2500 rpm for 2 minutes using a high-frequency shaker to mix evenly. The mixture was then transferred to water baths set at different temperatures and allowed to stand for 4 hours. The dehydration rates were measured, and the results are shown in Table 3.

[0118] Table 3 Demulsification results of experimental groups 11-14

[0119] As shown in Table 3, the ionic liquid demulsifier provided by the present invention can achieve 100% demulsification efficiency at 40°C in 240 minutes, 100% demulsification efficiency at 60°C in 180 minutes, and 100% demulsification efficiency at 70°C in 150 minutes.

[0120] Test Example 4 Based on the demulsifier prepared in Example 1, experimental groups 15-21 were established in sequence to characterize the demulsification performance of the demulsifier under different pH conditions.

[0121] 150 parts by mass of crude oil are added to 350 parts by mass of deionized water and stirred to mix. The pH value is adjusted by adding hydrochloric acid or sodium hydroxide, and the mixture is heated to 70° C. and then stirred at a speed of 11,000 r / min for 20 minutes. This process is repeated three times until a stable water-in-oil emulsion is obtained, thereby obtaining a crude oil emulsion.

[0122] The demulsifier prepared in Example 1 was added to ethanol to prepare a demulsifier solution with a mass fraction of 0.8%.

[0123] One part by volume of the above demulsifier solution was added to 20 parts by volume of crude oil emulsions of different pH values. The mixture was then shaken at 2500 rpm for 2 minutes using a high-frequency shaker to mix them evenly. The mixture was then transferred to a 40°C water bath and allowed to stand for 4 hours. The dehydration rates were measured, and the results are shown in Table 4.

[0124] Table 4 Demulsification results of experimental groups 15-21

[0125] It can be seen from Table 4 that the ionic liquid demulsifier provided by the present invention can have a high demulsification efficiency in a strong acid or strong base environment with a pH of 4-12.

[0126] Test Example 5 Based on the demulsifier prepared in Example 1, experimental groups 22-27 were established in sequence to characterize the demulsification performance of the demulsifier under salinity conditions.

[0127] 150 parts by mass of crude oil were added to 350 parts by mass of deionized water and stirred. The salinity was adjusted by adding sodium chloride, heated to 70° C., and then stirred at a speed of 11,000 r / min for 20 minutes. This process was repeated three times until a stable water-in-oil emulsion was obtained, thereby obtaining a crude oil emulsion.

[0128] The crude oil demulsifier prepared in Example 1 was added to ethanol to prepare a demulsifier solution with a mass fraction of 0.8%.

[0129] One part by volume of the above demulsifier solution was added to 20 parts by volume of crude oil emulsions of different salinities. The mixture was then shaken at 2500 rpm for 2 minutes to mix evenly. The mixture was then transferred to a 40°C water bath and allowed to stand for 4 hours. The dehydration rate was measured, and the results are shown in Table 5.

[0130] Table 5 Demulsification results of experimental groups 22-27

[0131] It can be seen from Table 5 that the ionic liquid demulsifier provided by the present invention can have a stable demulsification efficiency under high salinity (30000-50000 mg / L) conditions, indicating that the demulsifier has high salt resistance.

[0132] The invention provides an ionic liquid demulsifier for low-temperature demulsification, which is suitable for demulsification of crude oil emulsions and has the characteristics of simple preparation method, low demulsification temperature, excellent demulsification performance, etc.

[0133] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection 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 between ethanolamine and polyethylene glycol diglycidyl ether to obtain a first intermediate; Carry out a second reaction between the obtained first intermediate and a primary amine to obtain a second intermediate; Carry out an ionization reaction between the obtained second intermediate and a haloalkane 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 haloalkane is selected from one or more of chloroalkanes, bromoalkanes, and iodoalkanes.

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, n-butyl bromide, 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 claim 3, 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 claim 3, 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. Use of the ionic liquid demulsifier according to claim 1, 2, or 9 in demulsifying crude oil emulsions.

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 with the crude oil emulsion and let it stand.

12. The method according to claim 10, wherein, The temperature for 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.

Images