Fluorine-containing imidazolium salt as well as preparation method and application thereof

Abstract

The invention discloses fluorine-containing imidazolium salt as well as a preparation method and application thereof, and belongs to the technical field of oil and gas field reservoir protection. The fluorine-containing imidazolium salt has a structure as shown in a formula I; the invention also discloses a preparation method of the fluorine-containing imidazolium salt and application of the fluorine-containing imidazolium salt in oil and gas exploitation. The synthesis method of the fluorine-containing imidazolium salt is simple, the raw materials are easy to obtain, and the prepared fluorine-containing imidazolium salt can be used in acidizing, fracturing and water injection working solutions and has multiple effects.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field reservoir protection, and specifically relates to a fluorine-containing imidazolium salt and a preparation method and application thereof. Background Art

[0002] Clay is a mineral widely found in oil and gas reservoirs, including kaolinite, montmorillonite, illite and chlorite. Because clay minerals are highly water-sensitive, during the implementation of oil and gas production, such as water injection, acidification and hydraulic fracturing, water-based working fluids entering the formation can easily cause hydration and expansion of clay minerals, dispersion and migration, resulting in pore blockage in the reservoir, reduced permeability, and damage to the formation, which in turn causes a significant drop in oil well production or even shutdown. In order to inhibit the reduction of oil and gas layer permeability, prevent reservoir damage, and achieve high and stable production of oil and gas fields, clay stabilizers are widely used. Generally, the molecules of clay stabilizers contain positively charged groups that can be adsorbed on the surface of clay, prevent water molecules from entering the clay layers, and prevent the movement of particles through bridging and cross-linking, thereby protecting the clay. Since the last century, researchers in this field have conducted relevant research on clay stabilizers. Commonly used clay stabilizers include inorganic salts of potassium, sodium, calcium and ammonium, natural polymers, quaternary ammonium salts, ethylene glycol and surfactants. Each of the above clay stabilizers has many advantages, but also has some limitations, such as low thermal stability, low salt tolerance, low lubricity effect on rheology, and high usage concentration.

[0003] How to produce a multifunctional, environmentally friendly, thermally stable, anti-swelling and surface tension-reducing clay stabilizer for use in oil and gas reservoir protection to increase flowback and eliminate water lock damage is one of the current hot topics in oil and gas research. Summary of the invention

[0004] The problem to be solved by the present invention is to provide a fluorine-containing imidazolium salt and a preparation method and application thereof, so as to solve the problem that the existing clay stabilizer has insufficient temperature resistance and single performance.

[0005] The technical solution adopted to solve the technical problem is as follows: provide a fluorine-containing imidazolium salt, the compound having a structure as shown in Formula I: ; Where: n is 0, 1, 2, 3, 4, 5, 6 or 7; X is halogen.

[0006] The beneficial effects of the above technical scheme adopted in the present invention are as follows: the molecular structure of the fluorinated imidazolium salt of the present invention contains a positively charged imidazolium salt group and a fluorinated tail chain group; wherein the positively charged imidazolium salt group in the fluorinated imidazolium salt structure can generate electrostatic attraction with the negatively charged clay mineral, thereby stabilizing the clay mineral; the fluorinated tail chain group in the fluorinated imidazolium salt structure can adjust the surface / interfacial tension of the working fluid, and adjust the wettability of the pore surface after adsorbing on the pore surface.

[0007] Preferably, n is 0, 1, 3, 5 or 7.

[0008] Preferably, X is chlorine, bromine or iodine.

[0009] Preferably, the specific structural formula of the fluorine-containing imidazolium salt is as follows:

[0010] .

[0011] More preferably, the specific structural formula of the fluorine-containing imidazolium salt is as follows: .

[0012] More preferably, the specific structural formula of the fluorine-containing imidazolium salt is as follows: .

[0013] The preparation method of the above-mentioned fluorine-containing imidazolium salt comprises the following steps: N-methylimidazole and 2-halogenated ethyl perfluoroalkane are dissolved in an organic solvent, and a substitution reaction is carried out to obtain a fluorine-containing imidazolium salt, i.e., a compound of formula I; the synthesis route is as follows: .

[0014] Preferably, the method for preparing the fluorine-containing imidazolium salt comprises the following steps: S1, adding N-methylimidazole and 2-haloethylperfluoroalkane to a reactor with a reflux device, and then adding an organic solvent to the reactor, stirring and mixing, to obtain a mixture A; S2, performing a substitution reaction on the mixture A to obtain a mixture B; S3, filter the mixture B and take out the solid, wash and vacuum dry to obtain the fluorine-containing imidazolium salt.

[0015] Preferably, the molar ratio of N-methylimidazole to 2-haloethylperfluoroalkane is 1 to 3:1.

[0016] Preferably, the organic solvent is toluene and / or acetonitrile.

[0017] More preferably, the organic solvent is toluene, acetonitrile or a mixed solution of toluene and acetonitrile in a volume ratio of 1:1.

[0018] More preferably, the volume ratio of the total mass of N-methylimidazole and 2-halogenated ethyl perfluoroalkane to the organic solvent is 1 g:1.8-10 mL.

[0019] More preferably, the 2-halogenated ethyl perfluoroalkane is 1-bromo-1H,1H,2H,2H-perfluoropropane, 1-chloro-1H,1H,2H,2H-perfluoropropane, 1-iodo-1H,1H,2H,2H-perfluoropropane, 4-bromo-1,1,1,2,2-pentafluorobutane, 4-chloro-1,1,1,2,2-pentafluorobutane, 4-iodo-1,1,1,2 ,2-pentafluorobutane, 1-bromo-1H,1H,2H,2H-perfluoropentane, 1-chloro-1H,1H,2H,2H-perfluoropentane, 1-iodo-1H,1H,2H,2H-perfluoropentane, 1-bromo-1H,1H,2H,2H-perfluorohexane, 1-chloro-1H,1H,2H,2H-perfluorohexane, 1-iodo-1H,1H,2H,2H- Perfluorohexane, 1-bromo-1H,1H,2H,2H-perfluoroheptane, 1-chloro-1H,1H,2H,2H-perfluoroheptane, 1-iodo-1H,1H,2H,2H-perfluoroheptane, 1-bromo-1H,1H,2H,2H-perfluorooctane, 1-chloro-1H,1H,2H,2H-perfluorooctane, 1-iodo-1H,1H,2H,2H-perfluoro octane, 1-bromo-1H,1H,2H,2H-perfluorononane, 1-chloro-1H,1H,2H,2H-perfluorononane, 1-iodo-1H,1H,2H,2H-perfluorononane, 1-bromo-1H,1H,2H,2H-perfluorodecane, 1-chloro-1H,1H,2H,2H-perfluorodecane or 1-iodo-1H,1H,2H,2H-perfluorodecane.

[0020] More preferably, the 2-halogenated ethyl perfluoroalkane is 1-bromo-1H,1H,2H,2H-perfluoropropane, 1-chloro-1H,1H,2H,2H-perfluoropropane, 1-iodo-1H,1H,2H,2H-perfluoropropane, 4-bromo-1,1,1,2,2-pentafluorobutane, 4-chloro-1,1,1,2,2-pentafluorobutane, 4-iodo-1,1,1,2,2-pentafluorobutane, 1-bromo-1H,1H,2H,2H-perfluorohexane, 1-chloro-1 1-bromo-1H,1H,2H,2H-perfluorooctane, 1-chloro-1H,1H,2H,2H-perfluorooctane, 1-iodo-1H,1H,2H,2H-perfluorooctane, 1-bromo-1H,1H,2H,2H-perfluorodecane, 1-chloro-1H,1H,2H,2H-perfluorodecane or 1-iodo-1H,1H,2H,2H-perfluorodecane.

[0021] More preferably, the 2-haloethylperfluoroalkane is 1-iodo-1H,1H,2H,2H-perfluoropropane, 4-bromo-1,1,1,2,2-pentafluorobutane, 4-chloro-1,1,1,2,2-pentafluorobutane, 1-iodo-1H,1H,2H,2H-perfluorohexane, 1-iodo-1H,1H,2H,2H-perfluorooctane or 1-iodo-1H,1H,2H,2H-perfluorodecane.

[0022] Preferably, the substitution reaction temperature is 90-120°C and the reaction time is 12-48 h.

[0023] More preferably, washing is performed with a mixed solvent for 3 to 5 times; the mixed solvent is a mixture of petroleum ether and toluene or diethyl ether in a volume ratio of 1 to 3:1.

[0024] More preferably, the volume of the mixed solvent used in the washing process is 2 to 4 times the mass of the solid.

[0025] The invention also provides application of the fluorine-containing imidazolium salt in oil and gas production.

[0026] Preferably, the fluorine-containing imidazolium salt is used as a clay stabilizer in the preparation of acidizing and cracking working fluids in oil and gas production, as a water-locking agent in the near-well zone of oil or gas wells, or as a plugging remover in the preparation of pressure-reducing and injection-increasing working fluids for water injection wells.

[0027] The beneficial effects of the above technical scheme adopted in the present invention are as follows: the first application of the fluorinated imidazolium salt is as a clay stabilizer for acidizing and fracturing working fluids. The fluorinated imidazolium salt can interact with negatively charged clay minerals to effectively inhibit the hydration expansion and dispersion migration of reservoir clay minerals, thereby avoiding reservoir damage during the construction process; the second application of the fluorinated imidazolium salt is as a water-locking agent for water-locking and plugging-removing working fluids in the near-wellbore zone of oil / gas production wells. The fluorinated long chain of the fluorinated imidazolium salt can reduce the surface tension between oil / water or gas / water, reduce the capillary resistance of oil drainage and gas drainage, and is conducive to unlocking the water-locked area; the third application of the fluorinated imidazolium salt is as a plugging-removing agent for the pressure-reducing and injection-increasing working fluid of water injection wells. After the plugging-removing agent is adsorbed on the pore surface, the hydration capacity of the hydrophilic surface is weakened, the thickness of the water film on the inner wall of the pore is reduced, the effective pore diameter is increased, and the pressure-reducing and injection-increasing effect is facilitated.

[0028] The present invention has the following beneficial effects: (1) The fluorine-containing imidazolium salt of the present invention can be used in acidification, fracturing and water injection working fluids, and has a one-dose, multi-effect effect.

[0029] (2) When the fluorinated imidazolium salt of the present invention acts on the formation, there is an electrostatic attraction between the imidazolium salt groups therein and the negatively charged pore surface, which can cooperate with the waterproof layer constructed by the fluorinated tail chain, so that the fluorinated imidazolium salt is stably adsorbed and not easily decomposed and adsorbed by subsequent working fluids or formation water, thereby achieving a high efficiency and long-lasting effect.

[0030] (3) The fluorine-containing imidazolium salt provided by the present invention is simple to synthesize, the raw materials are readily available, and it can be produced on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is an infrared characterization diagram of the fluorine-containing imidazolium salt of the present invention; Figure 2 The DSC curve of the montmorillonite treated with the fluorine-containing imidazolium salt after moisture absorption of the present invention is shown in FIG. DETAILED DESCRIPTION

[0032] The following examples are only used to explain the present invention and are not intended to limit the scope of the present invention. If no specific conditions are specified in the examples, the conditions are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially. The following examples used 1-iodo-1H,1H,2H,2H-perfluoropropane, CAS No. 460-32-2; 4-bromo-1,1,1,2,2-pentafluorobutane, CAS No. 52671-70-2; 4-chloro-1,1,1,2,2-pentafluorobutane, CAS No. 149329-38-4; 1-iodo-1H,1H,2H,2H-perfluorohexane, CAS No. 2043-55-2; 1-iodo-1H,1H,2H,2H-perfluorooctane, CAS No. 2043-57-4; 1-iodo-1H,1H,2H,2H-perfluorodecane, CAS No. 2043-53-0; and tetramethylammonium chloride, analytical grade, was obtained from Chengdu Huaxia Chemical Reagent Co., Ltd.

[0033] Example 1 A fluorine-containing imidazolium salt having a structure shown in the following formula I-12, marked as Cmim-FC1: .

[0034] The preparation process of the fluorine-containing imidazolium salt Cmim-FC1 in this embodiment is as follows:

[0035] S1. Place 8.21 g of N-methylimidazole and 22.40 g of 1-iodo-1H,1H,2H,2H-perfluoropropane (molar ratio 1:1) into a 500 mL round-bottom flask, add 300 mL of toluene, and stir at room temperature until completely dissolved to obtain a mixture A. S2. Connect a reflux device to the round-bottom flask, place the round-bottom flask containing mixture A in an oil-water pot, heat it to 90 °C, and react at this temperature for 12 h to obtain mixture B; S3, the mixture B was allowed to stand and cool to room temperature, so that a light yellow precipitate was precipitated in the mixture B, and 26.35 g of solid was obtained after filtration and drying; S4. The solid obtained in S3 was washed three times with 53 mL of a mixed solvent of petroleum ether and toluene (volume ratio of 1:1), and dried in a vacuum oven to remove the solvent to obtain the product Cmim-FC1 (yield 87.34%).

[0036] The fluorinated imidazolium salt Cmim-FC1 prepared in this example was characterized by Fourier infrared spectroscopy. The specific method was as follows: 20 mg of the fluorinated imidazolium salt Cmim-FC1 was mixed with 1 g of spectrally pure KBr and then pressed into tablets. The FT-IR spectrometer (WQF-520 FTIR) was used for FT-IR characterization. The results were as follows: Figure 1 As shown. Figure 1 It can be seen that 3110~3207 cm -1 The three peaks at 2921 cm-1 are attributed to the stretching vibration peaks of CH on the imidazole ring. -1 The peak at 1568 cm is attributed to the stretching vibration peak of methyl and methylene CH. -1 The peak at 1423 cm -1 The peak at 1288 cm-1 is attributed to the CH bending vibration peak of methyl and methylene. -1 The peak at 1150 cm-1 is attributed to the CN stretching vibration peak. -1 The peak near 940 cm-1 is attributed to the stretching vibration of the CF bond. -1 and 840 cm -1 The two peaks are attributed to the external bending vibration of the imidazole ring CH, 748 cm -1 and 664 cm -1 The two groups of peaks are attributed to the external bending vibration of the CH of the imidazole ring.

[0037] The fluorinated imidazolium salt Cmim-FC1 prepared in this example was characterized by nuclear magnetic resonance. The specific method was as follows: 20 mg of the fluorinated imidazolium salt Cmim-FC1 was dissolved in 0.5 mL of deuterated chloroform, and a 400 MHz nuclear magnetic resonance spectrometer was used to analyze the H spectrum and C spectrum of the sample. The results were as follows: 1 H NMR (400 MHz, Chloroform-d) δ 9.65(s, 1H), 7.81(d, J = 7.3 Hz,1H), 7.35(d, J = 7.3 Hz, 1H), 4.52(t, J = 8.1 Hz, 2H), 3.82(s, 3H), 3.13(m,2H). 13 C NMR (100 MHz, Chloroform-d) δ 143.42, 131.37, 124.62, 123.94, 43.72, 36.80, 31.43. The FT-IR and NMR characterization results show that the synthesis of fluorinated imidazolium salt Cmim-FC1 is completed.

[0038] Example 2 A fluorine-containing imidazolium salt having a structure shown in the following formula I-2, marked as Cmim-FC2: .

[0039] The preparation process of the fluorine-containing imidazolium salt Cmim-FC2 in this embodiment is as follows:

[0040] S1. Place 16.42 g of N-methylimidazole and 22.70 g of 4-bromo-1,1,1,2,2-pentafluorobutane (molar ratio 2:1) into a 500 mL round-bottom flask, add 200 mL of acetonitrile, and stir at room temperature until completely dissolved to obtain a mixture A. S2. Connect a reflux device to the round-bottom flask, place the round-bottom flask containing mixture A in an oil-water pot, heat it to 105°C, and react at this temperature for 36 hours to obtain mixture B; S3, the mixture B was allowed to stand and cool to room temperature, so that a light yellow precipitate was precipitated in the mixture B, and 28.07 g of solid was obtained after filtration and drying; S4. The solid obtained in S3 was washed four times with 84 mL of a mixed solvent of petroleum ether and diethyl ether (volume ratio of 3:1), and dried in a vacuum oven to remove the solvent to obtain the product Cmim-FC2 (yield 85.19%).

[0041] The fluorinated imidazolium salt Cmim-FC2 prepared in this example was characterized by Fourier infrared spectroscopy. The specific method was as follows: 20 mg of the fluorinated imidazolium salt Cmim-FC2 was mixed with 1 g of spectrally pure KBr and then pressed into tablets. The FT-IR spectrometer (WQF-520 FTIR) was used for FT-IR characterization. The results were as follows: Figure 1 As shown. Figure 1 It can be seen that 3110~3207 cm -1 The three peaks at 2921 cm-1 are attributed to the stretching vibration peaks of CH on the imidazole ring. -1 and 2852 cm -1 The peak at 1568 cm is attributed to the stretching vibration peak of methyl and methylene CH. -1 The peak at 1423 cm -1 The peak at 1288 cm-1 is attributed to the CH bending vibration peak of methyl and methylene. -1 The peak at 1095-1200 cm-1 is attributed to the CN stretching vibration peak. -1 The peak at 940 cm-1 is attributed to the stretching vibration of the CF bond. -1 and 840 cm -1 The two peaks are attributed to the external bending vibration of the imidazole ring CH, 748 cm -1and 664 cm -1 The two groups of peaks are attributed to the external bending vibration of the CH of the imidazole ring.

[0042] The fluorinated imidazolium salt Cmim-FC2 prepared in this example was characterized by nuclear magnetic resonance. The specific method was as follows: 20 mg of the fluorinated imidazolium salt Cmim-FC2 was dissolved in 0.5 mL of deuterated chloroform, and a 400 MHz nuclear magnetic resonance spectrometer was used to analyze the H spectrum and C spectrum of the sample. The results were as follows: 1 H NMR (400 MHz, Chloroform-d) δ 9.71(s, 1H), 7.91(d, J = 7.2 Hz,1H), 7.45(d, J = 7.2 Hz, 1H), 4.59(t, J = 8.2 Hz, 2H), 3.85(s, 3H), 3.53(m,2H). 13 C NMR (100 MHz, Chloroform-d) δ 141.08, 121.57, 122.13, 121.92, 114.57,45.43, 35.85, 31.29. From the FT-IR and NMR characterization results, it can be seen that the synthesis of fluorinated imidazolium salt Cmim-FC2 is completed.

[0043] Example 3 A fluorine-containing imidazolium salt having a structure shown in the following formula I-21, marked as Cmim-FC2-1: .

[0044] The preparation process of the fluorine-containing imidazolium salt Cmim-FC2-1 in this embodiment is as follows:

[0045] S1. Place 24.63 g of N-methylimidazole and 18.25 g of 4-chloro-1,1,1,1,2,2-pentafluorobutane (molar ratio 3:1) into a 500 mL round-bottom flask, add 214 mL of a mixed solvent of toluene and acetonitrile (volume ratio 1:1), and stir at room temperature until completely dissolved to obtain a mixture A; S2. Connect a reflux device to the round-bottom flask, place the round-bottom flask containing mixture A in an oil-water pot, heat it to 120°C, and react at this temperature for 48 hours to obtain mixture B. S3, the mixture B was allowed to stand and cool to room temperature, so that a light yellow precipitate was precipitated in the mixture B, and 23.89 g of solid was obtained after filtration and drying; S4. The solid obtained in S3 was washed four times with 72 mL of a mixed solvent of petroleum ether and diethyl ether (volume ratio of 2:1), and dried in a vacuum oven to remove the solvent to obtain the product Cmim-FC2-1 (yield 76.95%).

[0046] The fluorinated imidazolium salt Cmim-FC2-1 prepared in this example was characterized by nuclear magnetic resonance. The specific method was as follows: 20 mg of the fluorinated imidazolium salt Cmim-FC2-1 was dissolved in 0.5 mL of deuterated chloroform, and a 400 MHz nuclear magnetic resonance spectrometer was used to analyze the H spectrum and C spectrum of the sample. The results were as follows: 1 H NMR (400 MHz, Chloroform-d) δ 9.72(s, 1H), 7.92(d, J = 7.2 Hz,1H), 7.44(d, J = 7.2 Hz, 1H), 4.58(t, J = 8.2 Hz, 2H), 3.84(s, 3H), 3.52(m,2H). 13 C NMR (100 MHz, Chloroform-d) δ 141.07, 121.58, 122.14, 121.94, 114.56, 45.42, 35.84, 31.28. From the NMR characterization results, it can be seen that the synthesis of the fluorinated imidazolium salt Cmim-FC2-1 is completed.

[0047] Example 4 A fluorine-containing imidazolium salt having a structure shown in the following formula I-42, marked as Cmim-FC4: .

[0048] The preparation process of the fluorine-containing imidazolium salt Cmim-FC4 in this embodiment is as follows:

[0049] S1. Place 6.57 g of N-methylimidazole and 29.92 g of 1-iodo-1H,1H,2H,2H-perfluorohexane (molar ratio 1:1) into a 500 mL round-bottom flask, add 300 mL of toluene, and stir at room temperature until completely dissolved to obtain a mixture A. S2. Connect a reflux device to the round-bottom flask, place the round-bottom flask containing mixture A in an oil-water pot, heat it to 90 °C, and react at this temperature for 24 h to obtain mixture B; S3, the mixture B was allowed to stand and cool to room temperature, so that a light yellow precipitate was precipitated in the mixture B, and 32.42 g of solid was obtained after filtration and drying; S4. The solid obtained in S3 was washed three times with 97 mL of a mixed solvent of petroleum ether and toluene (volume ratio of 2:1), and dried in a vacuum oven to remove the solvent to obtain the product Cmim-FC4 (yield 83.92%).

[0050] The fluorinated imidazolium salt Cmim-FC4 prepared in this example was characterized by Fourier infrared spectroscopy. The specific method was as follows: 20 mg of the fluorinated imidazolium salt Cmim-FC4 was mixed with 1 g of spectrally pure KBr and then pressed into tablets. The FT-IR spectrometer (WQF-520 FTIR) was used for FT-IR characterization. The results were as follows: Figure 1 As shown. Figure 1 It can be seen that 3110~3207 cm -1 The three peaks at 2921 cm-1 are attributed to the stretching vibration peaks of CH on the imidazole ring. -1 and 2852 cm -1 The peak at 1568 cm is attributed to the stretching vibration peak of methyl and methylene CH. -1 The peak at 1423 cm -1 The peak at 1288 cm-1 is attributed to the CH bending vibration peak of methyl and methylene. -1 The peak at 1095-1200 cm-1 is attributed to the CN stretching vibration peak. -1 The peak at 940 cm-1 is attributed to the stretching vibration of the CF bond. -1 and 840 cm -1 The two peaks are attributed to the external bending vibration of the imidazole ring CH, 748 cm -1 and 664 cm -1 The two groups of peaks are attributed to the external bending vibration of the CH of the imidazole ring.

[0051] The fluorinated imidazolium salt Cmim-FC4 prepared in this example was characterized by nuclear magnetic resonance. The specific method was as follows: 20 mg of the fluorinated imidazolium salt Cmim-FC4 was dissolved in 0.5 mL of deuterated chloroform, and a 400 MHz nuclear magnetic resonance spectrometer was used to analyze the H spectrum and C spectrum of the sample. The results were as follows: 1 H NMR (400 MHz, Chloroform-d) δ 10.25(s, 1H), 8.38(d, J = 7.3 Hz, 1H),8.29(d, J = 7.3 Hz, 1H), 4.61(t, J = 8.2 Hz, 2H), 3.80(s, 3H), 3.33 (m, 2H). 13CNMR (100 MHz, Chloroform-d) δ 141.88, 123.62, 122.53, 121.95, 120.25, 109.76,116.83, 45.19, 36.18, 33.55. The FT-IR and NMR characterization results show that the synthesis of fluorinated imidazolium salt Cmim-FC4 is completed.

[0052] Example 5 A fluorine-containing imidazolium salt having a structure shown in the following formula I-62, marked as Cmim-FC6: .

[0053] The preparation process of the fluorine-containing imidazolium salt Cmim-FC6 in this embodiment is as follows:

[0054] S1. Place 4.11 g of N-methylimidazole and 23.70 g of 1-iodo-1H,1H,2H,2H-perfluorooctane (molar ratio 1:1) into a 500 mL round-bottom flask, add 55 mL of toluene, and stir at room temperature until completely dissolved to obtain mixture A. S2. Connect a reflux device to the round-bottom flask, place the round-bottom flask containing mixture A in an oil-water pot, heat it to 95 °C, and react at this temperature for 24 h to obtain mixture B; S3, the mixture B was allowed to stand and cool to room temperature, so that a light yellow precipitate was precipitated in the mixture B, and 25.02 g of solid was obtained after filtration and drying; S4. The solid obtained in S3 was washed three times with 100 mL of a mixed solvent of petroleum ether and toluene (volume ratio of 2:1), and dried in a vacuum oven to remove the solvent to obtain the product Cmim-FC6 (yield 81.57%).

[0055] The fluorinated imidazolium salt Cmim-FC6 prepared in this example was characterized by Fourier infrared spectroscopy. The specific method was as follows: 20 mg of the fluorinated imidazolium salt Cmim-FC6 was mixed with 1 g of spectrally pure KBr and then pressed into tablets. The FT-IR spectrometer (WQF-520 FTIR) was used for FT-IR characterization. The results were as follows: Figure 1 As shown. Figure 1 It can be seen that 3110~3207 cm -1 The three peaks at 2921 cm-1 are attributed to the stretching vibration peaks of CH on the imidazole ring. -1 and 2852 cm -1 The peak at 1568 cm is attributed to the stretching vibration peak of methyl and methylene CH. -1The peak at 1423 cm -1 The peak at 1288 cm-1 is attributed to the CH bending vibration peak of methyl and methylene. -1 The peak at 1095-1200 cm-1 is attributed to the CN stretching vibration peak. -1 The peak at 940 cm-1 is attributed to the stretching vibration of the CF bond. -1 and 840 cm -1 The two peaks are attributed to the external bending vibration of the imidazole ring CH, 748 cm -1 and 664 cm -1 The two groups of peaks are attributed to the external bending vibration of the CH of the imidazole ring.

[0056] The fluorinated imidazolium salt Cmim-FC6 prepared in this example was characterized by nuclear magnetic resonance. The specific method was as follows: 20 mg of the fluorinated imidazolium salt Cmim-FC6 was dissolved in 0.5 mL of deuterated chloroform, and a 400 MHz nuclear magnetic resonance spectrometer was used to analyze the H spectrum and C spectrum of the sample. The results were as follows: 1 H NMR (400 MHz, Chloroform-d) δ 10.16(s, 1H), 8.38(d, J = 7.3 Hz, 1H),8.28(d, J = 7.3 Hz, 1H), 4.51(t, J = 8.0 Hz, 2H), 3.85(s, 3H), 3.33(m, 2H). 13 C NMR(100 MHz, Chloroform-d) δ 143.07, 122.94, 122.62, 119.05, 118.71, 116.74,113.86, 112.13, 111.52, 43.97, 36.30, 31.05. From the FT-IR and NMR characterization results, it can be seen that the synthesis of fluorinated imidazolium salt Cmim-FC6 is completed.

[0057] Example 6 A fluorine-containing imidazolium salt having a structure shown in the following formula I-82, marked as Cmim-FC8: .

[0058] The preparation process of the fluorine-containing imidazolium salt Cmim-FC8 in this embodiment is as follows:

[0059] S1. Place 4.11 g of N-methylimidazole and 28.79 g of 1-iodo-1H,1H,2H,2H-perfluorodecane (molar ratio 1:1) into a 250 mL round-bottom flask, add 65 mL of toluene, and stir at room temperature until completely dissolved to obtain a mixture A. S2. Connect a reflux device to the round-bottom flask, place the round-bottom flask containing mixture A in an oil-water pot, heat it to 100 °C, and react at this temperature for 24 h to obtain mixture B; S3, the mixture B was allowed to stand and cool to room temperature, so that a light yellow precipitate was precipitated in the mixture B, and 30.19 g of solid was obtained after filtration and drying; S4. The solid obtained in S3 was washed three times with 121 mL of a mixed solvent of petroleum ether and toluene (volume ratio of 3:1), and dried in a vacuum oven to remove the solvent to obtain the product Cmim-FC8 (yield 80.91%).

[0060] The fluorinated imidazolium salt Cmim-FC8 prepared in this example was characterized by Fourier infrared spectroscopy. The specific method was as follows: 20 mg of the fluorinated imidazolium salt Cmim-FC8 was mixed with 1 g of spectrally pure KBr and then pressed into tablets. The FT-IR spectrometer (WQF-520 FTIR) was used for FT-IR characterization. The results were as follows: Figure 1 As shown. Figure 1 It can be seen that 3110~3207 cm -1 The three peaks at 2921 cm-1 are attributed to the stretching vibration peaks of CH on the imidazole ring. -1 and 2852 cm -1 The peak at 1568 cm is attributed to the stretching vibration peak of methyl and methylene CH. -1 The peak at 1423 cm -1 The peak at 1288 cm-1 is attributed to the CH bending vibration peak of methyl and methylene. -1 The peak at 1095-1200 cm-1 is attributed to the CN stretching vibration peak. -1 The peak at 940 cm-1 is attributed to the stretching vibration of the CF bond. -1 and 840 cm -1 The two peaks are attributed to the external bending vibration of the imidazole ring CH, 748 cm -1 and 664 cm -1 The two groups of peaks are attributed to the external bending vibration of the CH of the imidazole ring.

[0061] The fluorinated imidazolium salt Cmim-FC8 prepared in this example was characterized by nuclear magnetic resonance. The specific method was as follows: 20 mg of the fluorinated imidazolium salt Cmim-FC8 was dissolved in 0.5 mL of deuterated chloroform, and a 400 MHz nuclear magnetic resonance spectrometer was used to analyze the H spectrum and C spectrum of the sample. The results were as follows: 1 H NMR (400 MHz, Chloroform-d) δ 10.11(s, 1H), 8.39(d, J = 7.3 Hz, 1H),8.29 (d, J = 7.3 Hz, 1H), 4.51 (t, J = 8.2 Hz, 2H), 3.89 (s, 3H), 3.33(m, 2H). 13 CNMR (100 MHz, Chloroform-d) δ 141.18, 122.62, 122.44, 118.89, 117.84, 117.74,114.06, 113.53, 110,14, 109.81, 109.61, 44.61, 36.05, 30.09. The FT-IR and NMR characterization results show that the synthesis of fluorinated imidazolium salt Cmim-FC8 is completed.

[0062] Example 7 Test on the anti-swelling performance of fluorinated imidazolium salt as clay stabilizer The preparation principle of the fluorine-containing imidazolium salt in the present invention is the reaction of halogenated hydrocarbons with methylimidazole, and similar technical effects can be produced when the halogen atom is Br, I or Cl.

[0063] The fluorinated imidazolium salts prepared in the above Examples 1 to 6 were used as clay stabilizers to perform anti-swelling performance tests. The fluorinated imidazolium salt samples prepared in Examples 1 to 6 were selected, and the evaluation standard was based on SY / T5971-2016 "Performance Evaluation Method for Clay Stabilizers for Oil and Gas Field Fracturing Acidification and Water Injection". The anti-swelling rate of the fluorinated imidazolium salts was tested by centrifugation, and the specific operation was as follows: S1. Take a clay stabilizer, add 100 g of distilled water and shake well to obtain a clay stabilizer solution with a concentration of 125 mmol / L; S2. Weigh 0.50 g of sodium bentonite to an accuracy of 0.01 g, place it in a 10 mL centrifuge tube, add 10 mL of clay stabilizer solution, shake well, place at room temperature for 2 h, place in a centrifuge, centrifuge at 1500 r / min for 15 min, and read the volume of the sodium bentonite after expansion. V 1 ; S3. Replace the clay stabilizer solution with distilled water, and the volume of sodium bentonite after expansion V 2 ; S4. Replace the clay stabilizer solution with kerosene, and the volume of sodium bentonite after expansion V0 ; S5. Calculate the anti-swelling rate of the clay stabilizer solution according to the following formula (1): Formula (1) Where: B —Anti-swelling rate of anti-swelling agent on bentonite (%); V 0 —Volume of bentonite after swelling in kerosene (mL); V 1 — is the amount of bentonite solution in the sample after swelling (mL); V 2 —Volume of bentonite after swelling in distilled water (mL).

[0064] Taking tetramethylammonium chloride (TMC), an organic cationic clay stabilizer commonly used in oil fields, as a control, the anti-swelling rate test results of fluorine-containing imidazolium salt as a clay stabilizer are shown in Table 1.

[0065] Table 1 Anti-swelling rate test results of clay stabilizer

[0066] It can be seen from Table 1 that when the concentration is 125 mmol / L, the fluorine-containing imidazolium salt Cmim-FC X (X=1, 2, 4, 6, 8) as clay stabilizers, their anti-swelling rates are all greater than 90%, with Cmim-FC4 reaching a maximum of 91.48%; while the anti-swelling rate of TMC, a commonly used product on the market, is less than 85%. Therefore, the anti-swelling rates of the invented clay stabilizers are all greater than similar commercial products.

[0067] Example 8 Evaluation of the water washability of fluorinated imidazolium salts as clay stabilizers The fluorinated imidazolium salt samples prepared in Examples 1 to 6 and the commercially available inorganic salt clay stabilizer TMC were selected to measure the water washability of the fluorinated imidazolium salt as a clay stabilizer. The specific operation is as follows: S1. Take a clay stabilizer, add 100 g of distilled water and shake well to obtain a clay stabilizer solution with a concentration of 125 mmol / L; S2. Weigh 0.50 g of sodium bentonite to an accuracy of 0.01 g and place it in a 10 mL centrifuge tube. Then add 10 mL of clay stabilizer solution, shake well, let stand at room temperature for 2 h, place it in a centrifuge, and centrifuge it at 1500 r / min for 15 min. Take the precipitate and add 10 mL of distilled water. After shaking well, let stand for 2 h, place it in a centrifuge and centrifuge it at 1500 r / min for 15 min. Repeat the above operation twice. Read the volume of the sodium bentonite after expansion. The calculation method is the same as formula (1) in Example 7.

[0068] Taking TMC, an organic cationic clay stabilizer commonly used in oil fields, as a control, the test results of the water washability of the clay stabilizer are shown in Table 2.

[0069] Table 2 Test results of water washability of clay stabilizer

[0070] As can be seen from Table 2, the fluorine-containing imidazolium salt Cmim-FC of the present invention X (X=1, 2, 4, 6, 8) as clay stabilizers, their anti-swelling rates after three washings were all greater than 85%, with the highest reaching 91.09%; among them, the clay stabilizers Cmim-FC corresponding to X=4 and 8 X After three water washings, the anti-swelling rate decreased by less than 1%. However, the anti-swelling rate of TMC, a commonly used product on the market, was only 73.95% (lower than 80%) after three water washings, and the anti-swelling rate decreased by 10.34% after water washing. Therefore, the water washing resistance of the fluorine-containing imidazolium salt of the present invention as a clay stabilizer is better than that of similar commercial products.

[0071] Example 9 Evaluation of the ability of fluorinated imidazolium salts to weaken the surface hydration of clay minerals For the fluorine-containing imidazolium salts prepared in Examples 1 to 6, the anion is Cl - Br - or I - The corresponding compounds have similar effects, so the compounds prepared in Examples 1, 2, 4, 5, and 6 were selected to evaluate the ability of fluorine-containing imidazolium salts to weaken the surface hydration of clay minerals. The specific operation is as follows: S1. Take the fluorine-containing imidazolium salt Cmim-FC X Add 100 g of deionized water, stir and shake to prepare a compound solution with a concentration of 125 mmol / L; S2, weigh 1.0 g sodium bentonite and 20 mL compound solution, mix them evenly, and let them stand for 2 h until the compound is fully adsorbed on the surface of montmorillonite; S3, using centrifugation to separate solid and liquid to obtain treated montmorillonite; then washing the surface of the montmorillonite with deionized water to wash away excess compounds; S4. The treated montmorillonite was dried at 105 °C to constant weight, and then ground into 300-500 meshes using a mortar. S5. Weigh 0.2 g of montmorillonite treated with fluorine-containing imidazolium salt and place it in a constant temperature and humidity environment (25 °C, relative humidity 100%) until the montmorillonite fully absorbs water vapor; S6. Use differential scanning calorimeter (DSC823) to test the DSC curve of hygroscopic montmorillonite; the test conditions are: nitrogen atmosphere, heating range 10~200 ℃, heating rate 10 ℃ / min; The DSC curve of the fully hygroscopic montmorillonite treated with fluorinated imidazolium salt and hygroscopic montmorillonite is shown in Figure 2. Figure 2 shown.

[0072] from Figure 2 It can be seen that after the original montmorillonite absorbs moisture, there are two obvious peaks at 109 °C and 132 °C, which are the endothermic peaks of the vaporization of free water and bound water on the surface of montmorillonite. After passing through the fluorinated imidazolium salt, the two groups of peaks move to low temperature and the intensity is significantly weakened, which indicates that the fluorinated imidazolium salt has a significant weakening effect on the hydration of the montmorillonite surface. When the fluorinated imidazolium salt acts on the formation, it will help to weaken the water film thickness on the pore surface and increase the effective pore radius and pore connectivity.

[0073] The present invention has been described according to the above embodiments. It should be understood that the above embodiments do not limit the present invention in any form. Any technical solutions obtained by equivalent replacement or equivalent transformation shall fall within the scope of the present invention.

Claims

1. A fluorine-containing imidazolium salt, characterized in that: The fluorine-containing imidazolium salt has a structure as shown in Formula I: ； Where: n is 0, 1, 2, 3, 4, 5, 6 or 7; X is halogen.

2. The fluorine-containing imidazolium salt according to claim 1, characterized in that The X is chlorine, bromine or iodine.

3. The fluorine-containing imidazolium salt according to claim 2, characterized in that: The specific structural formula is as follows: 。 4. The method for preparing a fluorine-containing imidazolium salt according to any one of claims 1 to 3, characterized in that: N-methylimidazole and 2-halogenated ethyl perfluoroalkane are dissolved in an organic solvent, and a substitution reaction is carried out to obtain a fluorine-containing imidazolium salt, i.e., a compound of formula I; the synthesis route is as follows: 。 5. The method for preparing a fluorine-containing imidazolium salt according to claim 4, characterized in that: The molar ratio of the N-methylimidazole to the 2-halogenated ethyl perfluoroalkane is 1 to 3:

1.

6. The method for preparing a fluorine-containing imidazolium salt according to claim 4, characterized in that: The organic solvent is toluene and / or acetonitrile.

7. The method for preparing a fluorine-containing imidazolium salt according to claim 6, characterized in that: The volume ratio of the total mass of the N-methylimidazole and the 2-halogenated ethyl perfluoroalkane to the organic solvent is 1 g:1.8-10 mL.

8. The method for preparing a fluorine-containing imidazolium salt according to claim 4, characterized in that: The substitution reaction temperature is 90-120°C and the reaction time is 12-48 h.

9. Use of the fluorine-containing imidazolium salt according to any one of claims 1 to 3 in oil and gas production.

10. The use according to claim 9, characterized in that The fluorine-containing imidazolium salt is used as a clay stabilizer when preparing acidizing and cracking working fluids in oil and gas production, as a water-locking agent in the vicinity of oil or gas production wells, or as a plugging remover when preparing pressure-reducing and injection-increasing working fluids in water injection wells.

Images