A fluorine-containing imidazolium salt, its preparation method and application

Abstract

The present invention discloses a fluorinated imidazolium salt, a preparation method thereof and an application thereof, belonging to the technical field of reservoir protection in oil and gas fields. The fluorinated imidazolium salt has a structure shown in Formula I; the present invention also discloses a preparation method of the fluorinated imidazolium salt and its application in oil and gas exploitation. The synthesis method of the fluorinated imidazolium salt provided by the present invention is simple, the raw materials are easily available, and the obtained fluorinated imidazolium salt can be used in acidizing, fracturing and water injection working fluids, having the effect of multiple functions with one agent.

Description

Technical Field

[0001] The present invention belongs to the technical field of reservoir protection in oil and gas fields, and particularly relates to a fluorinated imidazolium salt, a preparation method thereof, and an application thereof. Background Art

[0002] Clay is a kind of mineral widely existing in oil and gas reservoir formations, and its types include kaolinite, montmorillonite, illite, chlorite, etc. Due to the high water sensitivity of clay minerals, during oil and gas production operations such as water injection, acidification, and hydraulic fracturing, water-based working fluids entering the formation are likely to cause hydration swelling, dispersion, and migration of clay minerals, resulting in blockage of reservoir pores, reduction of permeability, damage to the formation, and thus a significant decrease in the oil well production, or even shut-in. To inhibit the reduction of oil and gas layer permeability and prevent reservoir damage, while achieving high and stable production in oil and gas fields, clay stabilizers are widely used. Usually, the molecules of clay stabilizers contain positively charged groups, which can adsorb on the surface of clay, prevent water molecules from entering the interlayer of clay, and prevent particle movement through bridging and crosslinking effects, thereby playing a role in protecting clay. Since the last century, researchers in this field have conducted relevant studies 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 at the same time, there are also some limitations, such as low thermal stability, low salt tolerance, low lubricity and its influence on rheology, and high use concentration.

[0003] How to obtain a multifunctional, environmentally friendly, clay stabilizer with good thermal stability, excellent anti-swelling effect, and capable of reducing surface tension for reservoir protection in oil and gas production to achieve effects such as increasing flowback and eliminating water lock damage is one of the current research hotspots in oil and gas. Summary of the Invention

[0004] The problem to be solved by the present invention is to provide a fluorinated imidazolium salt, a preparation method thereof, and an application thereof to solve the problems of insufficient temperature resistance and single performance of existing clay stabilizers.

[0005] The technical solution adopted to solve its technical problems is as follows: Provide a fluorinated imidazolium salt, and this compound has a structure shown in Formula I:

[0006] ;

[0007] In the formula:

[0008] n is 0, 1, 2, 3, 4, 5, 6 or 7; X is a halogen.

[0009] The beneficial effects of the present invention adopting the above technical solutions are as follows: The molecular structure of the fluorinated imidazolium salt in the present invention contains a positively charged imidazolium salt group and a fluorinated tail chain group; among them, the positively charged imidazolium salt group in the fluorinated imidazolium salt structure can undergo electrostatic attraction with the negatively charged clay mineral, achieving the effect of stabilizing the clay mineral; the fluorinated tail chain group in the fluorinated imidazolium salt structure can adjust the surface / interface tension of the working fluid and, after adsorption on the pore surface, adjust the wettability of the pore surface.

[0010] Preferably, n is 0, 1, 3, 5 or 7.

[0011] Preferably, X is chlorine, bromine or iodine.

[0012] Preferably, the specific structural formula of the fluorinated imidazolium salt is as follows:

[0013]

[0014] 。

[0015] More preferably, the specific structural formula of the fluorinated imidazolium salt is as follows:

[0016] 。

[0017] More preferably, the specific structural formula of the fluorinated imidazolium salt is as follows:

[0018] 。

[0019] The preparation method of the above-mentioned fluorinated imidazolium salt includes the following steps:

[0020] Dissolve N-methylimidazole and 2-haloethyl perfluoroalkane in an organic solvent, and carry out a substitution reaction to obtain the fluorinated imidazolium salt, i.e., the compound of formula I; its synthetic route is as follows:

[0021] 。

[0022] Preferably, the preparation method of the fluorinated imidazolium salt includes the following steps:

[0023] S1. Add N-methylimidazole and 2-haloethyl perfluoroalkane to a reactor equipped with a reflux device, and then add an organic solvent to the reactor, stir and mix evenly to obtain a mixture A;

[0024] S2. Carry out a substitution reaction on the mixture A to obtain a mixture B;

[0025] S3. Filter the mixture B and take the solid, wash and dry it under vacuum to obtain the fluorinated imidazolium salt.

[0026] Preferably, the molar ratio of N-methylimidazole to 2-haloethyl perfluoroalkane is 1 to 3:1.

[0027] Preferably, the organic solvent is toluene and / or acetonitrile.

[0028] More preferably, the organic solvent is toluene, acetonitrile or a mixed solution of toluene and acetonitrile mixed in a volume ratio of 1:1.

[0029] More preferably, the volume ratio of the total mass of N-methylimidazole and 2-haloethyl perfluoroalkane to the organic solvent is 1 g: 1.8 to 10 mL.

[0030] More preferably, the 2-haloethyl 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-perfluorooctane, 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.

[0031] More preferably, the 2-haloethyl 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-1H,1H,2H,2H-perfluorohexane, 1-iodo-1H,1H,2H,2H-perfluorohexane, 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.

[0032] More preferably, the 2-haloethyl perfluoroalkane 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.

[0033] Preferably, the substitution reaction temperature is 90-120 °C and the time is 12-48 h.

[0034] More preferably, the washing is carried out with a mixed solvent for 3-5 times; the mixed solvent is composed of petroleum ether and toluene or ether mixed at a volume ratio of 1-3:1.

[0035] More preferably, the volume of the mixed solvent used during washing is 2-4 times the mass of the solid.

[0036] The present invention also provides the application of the fluorinated imidazolium salt in oil and gas exploitation.

[0037] Preferably, the application of the fluorinated imidazolium salt in oil and gas exploitation is as a clay stabilizer when preparing acidification and cracking working fluids, as a water block remover in the near-wellbore area of oil production wells or gas production wells, or as a plug remover when preparing pressure reduction and injection enhancement working fluids for injection wells.

[0038] The beneficial effects of the present invention adopting the above technical solutions are as follows: The first application of the fluorinated imidazolium salt is as a clay stabilizer for acidizing and fracturing working fluids. This fluorinated imidazolium salt can interact with negatively charged clay minerals, effectively inhibiting the hydration swelling, dispersion and migration of reservoir clay minerals, and avoiding reservoir damage during the construction process; The second application of the fluorinated imidazolium salt is as a water-lock breaker for the water-lock removal working fluid in the near-wellbore area of oil / gas production wells. The fluorinated long chain of this 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 beneficial to unlocking the water-lock area; The third application of the fluorinated imidazolium salt is as a plugging removal agent for the pressure reduction and injection increase working fluid of injection wells. After the plugging removal agent adsorbs on the pore surface, it weakens the hydration ability of the hydrophilic surface, reduces the water film thickness on the inner wall of the pores, increases the effective pore diameter, and helps to reduce pressure and increase injection.

[0039] The present invention has the following beneficial effects:

[0040] (1) The fluorinated imidazolium salt of the present invention can be used in acidizing, fracturing and injection working fluids, and has the effect of multiple functions with one agent.

[0041] (2) When the fluorinated imidazolium salt of the present invention acts on the formation, there is an electrostatic attraction between the imidazolium salt group therein and the negatively charged pore surface, and it can cooperate with the waterproof layer constructed by the fluorinated tail chain, so that the fluorinated imidazolium salt is stably adsorbed and is not easily hydrolyzed and adsorbed by subsequent working fluids or the formation, thereby achieving high efficiency and long-term effects.

[0042] (3) The fluorinated imidazolium salt provided by the present invention is simple to synthesize, the raw materials are easy to obtain, and it can be produced on a large scale. Description of the Drawings

[0043] Figure 1 It is the infrared characterization diagram of the fluorinated imidazolium salt of the present invention;

[0044] Figure 2 It is the DSC curve diagram of montmorillonite treated with the fluorinated imidazolium salt of the present invention after moisture absorption. Detailed Embodiments

[0045] The following examples are only used to explain the present invention and are not intended to limit the scope of the present invention. For those without specific conditions noted in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments without the manufacturer noted, they are all conventional products that can be obtained by purchasing in the market. In the following examples, 1-iodo-1H,1H,2H,2H-perfluoropropane with CAS number 460-32-2; 4-bromo-1,1,1,2,2-pentafluorobutane with CAS number 52671-70-2; 4-chloro-1,1,1,2,2-pentafluorobutane with CAS number 149329-38-4; 1-iodo-1H,1H,2H,2H-perfluorohexane with CAS number 2043-55-2; 1-iodo-1H,1H,2H,2H-perfluorooctane with CAS number 2043-57-4; 1-iodo-1H,1H,2H,2H-perfluorodecane with CAS number 2043-53-0; and tetramethylammonium chloride, of analytical purity, sourced from Chengdu Huaxia Chemical Reagent Co., Ltd.

[0046] Example 1

[0047] A fluorinated imidazolium salt has the structure shown in Formula I-12 below, denoted as Cmim-FC1:

[0048] 。

[0049] The preparation process of the fluorinated imidazolium salt Cmim-FC1 in this example is as follows:

[0050]

[0051] S1. Put 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 mixture A;

[0052] S2. Connect a reflux device to the round-bottom flask, place the round-bottom flask containing mixture A in an oil-water bath and heat it to 90 °C, and react at a constant temperature for 12 h to obtain mixture B;

[0053] S3. Let mixture B stand and cool to room temperature, so that a light yellow precipitate precipitates in mixture B. After filtration and drying, 26.35 g of solid is obtained;

[0054] S4. Wash the solid obtained in S3 three times with a mixed solvent of 53 mL of petroleum ether and toluene (volume ratio 1:1), and dry it in a vacuum box to remove the solvent, thus obtaining the product Cmim-FC1 (yield 87.34%).

[0055] The Fourier infrared characterization of the fluorinated imidazolium salt Cmim-FC1 prepared in this example was carried out as follows: 20 mg of the fluorinated imidazolium salt Cmim-FC1 was mixed evenly with 1 g of spectroscopically pure KBr and pressed into a tablet. FT-IR characterization was carried out using a Fourier transform infrared spectrometer (WQF-520 FTIR). The results are as Figure 1 shown. It can be seen from Figure 1 that the three groups of peaks at 3110 - 3207 cm -1 are attributed to the stretching vibration peaks of C-H on the imidazole ring. The peak at 2921 cm -1 is attributed to the stretching vibration peaks of C-H of methyl and methylene groups. The peak at 1568 cm -1 is attributed to the skeletal vibration peak of the imidazole ring. The peak at 1423 cm -1 is attributed to the bending vibration peaks of C-H of methyl and methylene groups. The peak at 1288 cm -1 is attributed to the C-N stretching vibration peak. The peaks near 1150 cm -1 are attributed to the stretching vibration of the C-F bond. The two groups of peaks at 940 cm -1 and 840 cm -1 are attributed to the out-of-plane bending vibration of C-H on the imidazole ring. The two groups of peaks at 748 cm -1 and 664 cm -1 are attributed to the out-of-plane bending vibration of C-H on the imidazole ring.

[0056] The nuclear magnetic characterization of the fluorinated imidazolium salt Cmim-FC1 prepared in this example was carried out as follows: 20 mg of the fluorinated imidazolium salt Cmim-FC1 was dissolved in 0.5 mL of deuterated chloroform. A 400 MHz nuclear magnetic resonance spectrometer was used to obtain the H spectrum and C spectrum of the sample. The results are as follows:

[0057] 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.

[0058] It can be seen from the results of FT-IR and nuclear magnetic characterization that the synthesis of the fluorinated imidazolium salt Cmim-FC1 is completed.

[0059] Example 2

[0060] A fluorinated imidazolium salt has the structure shown in Formula I-2 below and is labeled as Cmim-FC2:

[0061] .

[0062] The preparation process of the fluorinated imidazolium salt Cmim-FC2 in this example is as follows:

[0063]

[0064] S1. Put 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 mixture A;

[0065] S2. Connect a reflux device to the round-bottom flask, place the round-bottom flask containing mixture A in an oil-water bath, heat it to 105 °C, and react at a constant temperature for 36 h to obtain mixture B;

[0066] S3. Let mixture B stand and cool to room temperature, so that a light yellow precipitate precipitates in mixture B. After filtration and drying, 28.07 g of solid is obtained;

[0067] S4. Wash the solid obtained in S3 4 times with a mixed solvent of 84 mL of petroleum ether and ether (volume ratio 3:1), and dry it in a vacuum box to remove the solvent, thus obtaining the product Cmim-FC2 (yield 85.19%).

[0068] Perform Fourier transform infrared characterization on the fluorinated imidazolium salt Cmim-FC2 prepared in this example. The specific method is as follows: Take 20 mg of the fluorinated imidazolium salt Cmim-FC2 and mix it evenly with 1 g of spectroscopic pure KBr, and then press it into a tablet. Use a Fourier transform infrared spectrometer (WQF-520 FTIR) to perform FT-IR characterization. The results are as Figure 1 shown. It can be seen from Figure 1 that the three groups of peaks at 3110~3207 cm -1 are attributed to the stretching vibration peaks of C-H on the imidazole ring, and the peaks at 2921 cm -1 and 2852 cm -1 are attributed to the stretching vibration peaks of C-H of methyl and methylene groups. The peak at 1568 cm -1 is attributed to the imidazole ring skeletal vibration peak, the peak at 1423 cm -1 is attributed to the C-H bending vibration peak of methyl and methylene groups, the peak at 1288 cm -1 is attributed to the C-N stretching vibration peak, and the peaks at 1095~1200 cm -1The peak at [specific position] is attributed to the stretching vibration of the C-F bond, 940 cm -1 and 840 cm -1 Two sets of peaks are attributed to the out-of-plane bending vibration of C-H in the imidazole ring, 748 cm -1 and 664 cm -1 Two sets of peaks are attributed to the out-of-plane bending vibration of C-H in the imidazole ring.

[0069] For the fluorinated imidazolium salt Cmim-FC2 prepared in this example, nuclear magnetic resonance (NMR) characterization was carried out. The specific method is 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 obtain the 1H spectrum and 13C spectrum of the sample. The results are as follows:

[0070] 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.

[0071] From the results of FT-IR and NMR characterization, it can be seen that the synthesis of the fluorinated imidazolium salt Cmim-FC2 is completed.

[0072] Example 3

[0073] A fluorinated imidazolium salt has the structure shown in Formula I-21 below, labeled as Cmim-FC2-1:

[0074] .

[0075] The preparation process of the fluorinated imidazolium salt Cmim-FC2-1 in this example is as follows:

[0076]

[0077] S1. 24.63 g of N-methylimidazole and 18.25 g of 4-chloro-1,1,1,1,2,2-pentafluorobutane (molar ratio 3:1) were added to a 500 mL round-bottom flask, and 214 mL of a mixed solvent of toluene and acetonitrile (volume ratio 1:1) was added. The mixture was stirred at room temperature until completely dissolved to obtain mixture A;

[0078] S2. Connect a reflux device to the round-bottom flask, place the round-bottom flask containing mixture A in an oil-water bath, heat it to 120 °C, and react at a constant temperature for 48 h to obtain mixture B;

[0079] S3. Let mixture B stand and cool to room temperature, so that a pale yellow precipitate precipitates in mixture B. After filtration and drying, 23.89 g of solid is obtained;

[0080] S4. Wash the solid obtained in S3 4 times with a mixed solvent of 72 mL of petroleum ether and ether (volume ratio 2:1), and dry it in a vacuum box to remove the solvent, thus obtaining the product Cmim-FC2-1 (yield 76.95%).

[0081] Perform NMR characterization on the fluorinated imidazolium salt Cmim-FC2-1 prepared in this example. The specific method is as follows: Take 20 mg of the fluorinated imidazolium salt Cmim-FC2-1 and dissolve it in 0.5 mL of deuterated chloroform. Use a 400 MHz nuclear magnetic resonance spectrometer to obtain the H spectrum and C spectrum of the sample. The results are as follows:

[0082] 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.

[0083] It can be seen from the NMR characterization results that the synthesis of the fluorinated imidazolium salt Cmim-FC2-1 is completed.

[0084] Example 4

[0085] A fluorinated imidazolium salt has the structure shown in Formula I-42 below, denoted as Cmim-FC4:

[0086] .

[0087] The preparation process of the fluorinated imidazolium salt Cmim-FC4 in this example is as follows:

[0088]

[0089] S1. Put 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 mixture A;

[0090] S2. Connect a reflux device to the round-bottom flask, place the round-bottom flask containing mixture A in an oil-water bath, heat it to 90 °C, and react at a constant temperature for 24 h to obtain mixture B;

[0091] S3. Let mixture B stand and cool to room temperature, so that a pale yellow precipitate precipitates in mixture B. After filtration and drying, 32.42 g of solid is obtained;

[0092] S4. Wash the solid obtained in S3 three times with a mixed solvent of 97 mL of petroleum ether and toluene (volume ratio 2:1), and dry it in a vacuum box to remove the solvent, thus obtaining the product Cmim-FC4 (yield 83.92%).

[0093] Perform Fourier infrared characterization on the fluorinated imidazolium salt Cmim-FC4 prepared in this example. The specific method is as follows: Take 20 mg of the fluorinated imidazolium salt Cmim-FC4 and mix it evenly with 1 g of spectroscopic pure KBr, then press it into a tablet, and perform FT-IR characterization using a Fourier transform infrared spectrometer (WQF-520 FTIR). The results are as Figure 1 shown. It can be seen from Figure 1 that the three groups of peaks at 3110 - 3207 cm -1 are attributed to the stretching vibration peaks of C-H on the imidazole ring, the peaks at 2921 cm -1 and 2852 cm -1 are attributed to the stretching vibration peaks of C-H of methyl and methylene, the peak at 1568 cm -1 is attributed to the skeletal vibration peak of the imidazole ring, the peak at 1423 cm -1 is attributed to the bending vibration peak of C-H of methyl and methylene, the peak at 1288 cm -1 is attributed to the C-N stretching vibration peak, the peaks at 1095 - 1200 cm -1 are attributed to the stretching vibration of the C-F bond, the two groups of peaks at 940 cm -1 and 840 cm -1 are attributed to the out-of-plane bending vibration of C-H on the imidazole ring, and the two groups of peaks at 748 cm -1 and 664 cm -1 are attributed to the out-of-plane bending vibration of C-H on the imidazole ring.

[0094] The nuclear magnetic resonance (NMR) characterization of the fluorinated imidazolium salt Cmim-FC4 prepared in this example was carried out as follows: 20 mg of the fluorinated imidazolium salt Cmim-FC4 was dissolved in 0.5 mL of deuterated chloroform, and the 1H and 13C spectra of the sample were measured using a 400 MHz nuclear magnetic resonance spectrometer. The results are as follows:

[0095] 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). 13 C NMR (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.

[0096] From the results of FT-IR and NMR characterization, it can be seen that the synthesis of the fluorinated imidazolium salt Cmim-FC4 is completed.

[0097] Example 5

[0098] A fluorinated imidazolium salt having the structure shown in Formula I-62 below, denoted as Cmim-FC6:

[0099] 。

[0100] The preparation process of the fluorinated imidazolium salt Cmim-FC6 in this example is as follows:

[0101]

[0102] S1. 4.11 g of N-methylimidazole and 23.70 g of 1-iodo-1H,1H,2H,2H-perfluorooctane (molar ratio 1:1) were added to a 500 mL round-bottom flask, 55 mL of toluene was added, and the mixture was stirred at room temperature until completely dissolved to obtain mixture A;

[0103] S2. A reflux device was connected to the round-bottom flask, and the round-bottom flask containing mixture A was placed in an oil-water bath and heated to 95 °C and kept at a constant temperature for 24 h to obtain mixture B;

[0104] S3. Mixture B was allowed to stand and cool to room temperature, and a pale yellow precipitate was formed in mixture B. After filtration and drying, 25.02 g of solid was obtained.

[0105] S4. Wash the solid obtained in S3 three times with a mixed solvent of 100 mL of petroleum ether and toluene (volume ratio 2:1), and dry it in a vacuum oven to remove the solvent, thus obtaining the product Cmim-FC6 (yield 81.57%).

[0106] Perform Fourier transform infrared (FT-IR) characterization on the fluorinated imidazolium salt Cmim-FC6 prepared in this example. The specific method is as follows: Mix 20 mg of the fluorinated imidazolium salt Cmim-FC6 with 1 g of spectroscopic pure KBr evenly and press them into a tablet. Then, use a Fourier transform infrared spectrometer (WQF-520 FTIR) to perform FT-IR characterization. The results are as Figure 1 shown. As can be seen from Figure 1 , the three groups of peaks at 3110 - 3207 cm -1 are attributed to the stretching vibration peaks of C-H on the imidazole ring. The peaks at 2921 cm -1 and 2852 cm -1 are attributed to the stretching vibration peaks of C-H of methyl and methylene groups. The peak at 1568 cm -1 is attributed to the skeletal vibration peak of the imidazole ring. The peak at 1423 cm -1 is attributed to the bending vibration peak of C-H of methyl and methylene groups. The peak at 1288 cm -1 is attributed to the stretching vibration peak of C-N. The peaks at 1095 - 1200 cm -1 are attributed to the stretching vibration of the C-F bond. The two groups of peaks at 940 cm -1 and 840 cm -1 are attributed to the out-of-plane bending vibration of C-H on the imidazole ring. The two groups of peaks at 748 cm -1 and 664 cm -1 are attributed to the out-of-plane bending vibration of C-H on the imidazole ring.

[0107] Perform nuclear magnetic resonance (NMR) characterization on the fluorinated imidazolium salt Cmim-FC6 prepared in this example. The specific method is as follows: Dissolve 20 mg of the fluorinated imidazolium salt Cmim-FC6 in 0.5 mL of deuterated chloroform. Use a 400 MHz nuclear magnetic resonance spectrometer to obtain the H spectrum and C spectrum of the sample. The results are as follows:

[0108] 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 13C 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.

[0109] From the FT-IR and NMR characterization results, it can be seen that the fluorinated imidazolium salt Cmim-FC6 has been synthesized successfully.

[0110] Example 6

[0111] A fluorinated imidazolium salt has the structure shown in Formula I-82 below, denoted as Cmim-FC8:

[0112] .

[0113] The preparation process of the fluorinated imidazolium salt Cmim-FC8 in this example is as follows:

[0114]

[0115] S1. Put 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 mixture A;

[0116] S2. Connect a reflux device to the round-bottom flask, place the round-bottom flask containing mixture A in an oil-water bath and heat it to 100 °C, and react at a constant temperature for 24 h to obtain mixture B;

[0117] S3. Let mixture B stand and cool to room temperature, so that a pale yellow precipitate precipitates in mixture B. After filtration and drying, 30.19 g of solid is obtained;

[0118] S4. Wash the solid obtained in S3 three times with a mixed solvent of 121 mL of petroleum ether and toluene (volume ratio 3:1), and dry it in a vacuum box to remove the solvent, thus obtaining the product Cmim-FC8 (yield 80.91%).

[0119] Perform Fourier transform infrared (FT-IR) characterization on the fluorinated imidazolium salt Cmim-FC8 prepared in this example. The specific method is as follows: Take 20 mg of the fluorinated imidazolium salt Cmim-FC8 and mix it evenly with 1 g of spectroscopic pure KBr, then press it into a tablet, and use a Fourier transform infrared spectrometer (WQF-520 FTIR) for FT-IR characterization. The results are as Figure 1 shown. It can be seen from Figure 1 that in the range of 3110~3207 cm -1The three groups of peaks at [position] are attributed to the stretching vibration peaks of C-H on the imidazole ring, 2921 cm -1 and the peaks at 2852 cm -1 are attributed to the stretching vibration peaks of C-H of methyl and methylene groups, the peak at 1568 cm -1 is attributed to the skeletal vibration peak of the imidazole ring, the peak at 1423 cm -1 is attributed to the C-H bending vibration peaks of methyl and methylene groups, the peak at 1288 cm -1 is attributed to the C-N stretching vibration peak, the peaks at 1095 - 1200 cm -1 are attributed to the stretching vibration of the C-F bond, the peaks at 940 cm -1 and 840 cm -1 The two groups of peaks are attributed to the out-of-plane bending vibration of C-H on the imidazole ring, the peaks at 748 cm -1 and 664 cm -1 The two groups of peaks are attributed to the out-of-plane bending vibration of C-H on the imidazole ring.

[0120] The nuclear magnetic resonance characterization of the fluorinated imidazolium salt Cmim-FC8 prepared in this example was carried out. 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 obtain the H spectrum and C spectrum of the sample. The results are as follows:

[0121] 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 C NMR (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.

[0122] It can be seen from the results of FT-IR and nuclear magnetic resonance characterization that the synthesis of the fluorinated imidazolium salt Cmim-FC8 is completed.

[0123] Example 7 Swelling prevention performance test of fluorinated imidazolium salt as a clay stabilizer

[0124] In the present invention, the preparation principle of the fluorinated imidazolium salt is that the halogenated hydrocarbon reacts with methylimidazole, and similar technical effects can be produced when the halogen atom is Br, I or Cl.

[0125] The anti-swelling performance of the fluorinated imidazolium salts prepared in the above Examples 1 to 6 was tested as a clay stabilizer. The fluorinated imidazolium salt samples prepared in Examples 1 to 6 were selected, and the evaluation standard referred to SY / T5971-2016 "Performance Evaluation Method for Clay Stabilizers Used in Oil and Gas Field Fracturing Acidizing and Water Injection". The anti-swelling rate of the fluorinated imidazolium salt was tested by the centrifugation method. The specific operation is as follows:

[0126] S1. Add the clay stabilizer to 100 g of distilled water and shake well to obtain a clay stabilizer solution with a concentration of 125 mmol / L;

[0127] S2. Weigh 0.50 g of sodium bentonite, accurate to 0.01 g, put it into a 10 mL centrifuge tube, then add 10 mL of the clay stabilizer solution, shake well, let it stand at room temperature for 2 h, put it into the centrifuge, and centrifuge at a speed of 1500 r / min for 15 min, and read the volume of the sodium bentonite after swelling; V 1 ;

[0128] S3. Replace the clay stabilizer solution with distilled water, and measure the volume of the sodium bentonite after swelling; V 2 ;

[0129] S4. Replace the clay stabilizer solution with kerosene, and measure the volume of the sodium bentonite after swelling; V 0 ;

[0130] S5. Calculate the anti-swelling rate of the clay stabilizer solution according to the following formula (1):

[0131] Formula (1)

[0132] In the formula: B —The anti-swelling rate of the anti-swelling agent to bentonite (%);

[0133] V 0 —The volume of the bentonite after swelling in kerosene (mL);

[0134] V 1 —The volume of the solution after swelling in the bentonite sample (mL);

[0135] V 2 —The volume of the bentonite after swelling in distilled water (mL).

[0136] Taking the commonly used organic cationic clay stabilizer tetramethylammonium chloride (TMC) in oilfield field as a control, the anti-swelling rate test results of the fluorinated imidazolium salt as a clay stabilizer are shown in Table 1.

[0137] Table 1 Anti-swelling rate test results of clay stabilizers

[0138]

[0139] As can be seen from Table 1, when the use concentration is 125 mmol / L, the fluorinated imidazolium salt Cmim-FC X (X = 1, 2, 4, 6, 8) as a clay stabilizer, its anti-swelling rate is greater than 90%, and the highest of Cmim-FC4 reaches 91.48%; while the anti-swelling rate of the commonly used product TMC in the market is less than 85%. Therefore, the anti-swelling rates of the invented clay stabilizers are all greater than those of similar commercially available products.

[0140] Example 8 Evaluation of the water-washing resistance of the fluorinated imidazolium salt as a clay stabilizer

[0141] Select the fluorinated imidazolium salt samples prepared in Examples 1-6 and the commercially available inorganic salt clay stabilizer TMC, and measure the water-washing resistance of the fluorinated imidazolium salt as a clay stabilizer. The specific operations are as follows:

[0142] S1. Add the clay stabilizer to 100 g of distilled water and shake well to obtain a clay stabilizer solution with a concentration of 125 mmol / L;

[0143] S2. Weigh 0.50 g of sodium bentonite, accurate to 0.01 g, put it into a 10 mL centrifuge tube, then add 10 mL of the clay stabilizer solution, shake well, place it at room temperature for 2 h, put it into a centrifuge, centrifuge at a speed of 1500 r / min for 15 min, take the precipitated part, add 10 mL of distilled water, shake well, let it stand for 2 h, then put it into a centrifuge and centrifuge at a speed of 1500 r / min for 15 min. Repeat the above operation 2 times, read the volume of the swollen sodium bentonite, and the calculation method is the same as formula (1) in Example 7.

[0144] Taking the commonly used organic cationic clay stabilizer TMC in oilfield field as a control, the water-washing resistance test results of the clay stabilizer are shown in Table 2.

[0145] Table 2 Water-washing resistance test results of clay stabilizers

[0146]

[0147] As can be seen from Table 2, the fluorinated imidazolium salt Cmim-FC of the present invention X(X = 1, 2, 4, 6, 8)as a clay stabilizer, the anti-swelling rate after 3 washes with water is greater than 85%, and the highest reaches 91.09%; among them, the clay stabilizers Cmim-FC corresponding to X = 4 and 8 X After 3 washes with water, the decrease in anti-swelling rate < 1%. For the commonly used product TMC in the market, the anti-swelling rate after 3 washes with water is only 73.95% (lower than 80%), and the anti-swelling rate decreases by 10.34% after washing. Therefore, the water resistance of the fluorinated imidazolium salt of the present invention as a clay stabilizer is better than that of similar commercially available products.

[0148] Example 9 Evaluation of the ability of fluorinated imidazolium salt to weaken the surface hydration ability of clay minerals

[0149] For the fluorinated imidazolium salts prepared in Examples 1 - 6, where the anion is Cl - , Br - or I - The corresponding compounds have similar effects. Therefore, the compounds prepared in Examples 1, 2, 4, 5, and 6 are selected to evaluate the ability of the fluorinated imidazolium salt to weaken the surface hydration ability of clay minerals. The specific operations are as follows:

[0150] S1. Take the fluorinated imidazolium salt Cmim-FC X Add it to 100 g of deionized water, stir well, and prepare a compound solution with a concentration of 125 mmol / L;

[0151] S2. Weigh 1.0 g of sodium bentonite and mix it evenly with 20 mL of the compound solution, and let it stand for 2 h until the compound is fully adsorbed on the montmorillonite surface;

[0152] S3. Use the centrifugation method for solid-liquid separation to obtain the treated montmorillonite; then rinse the surface of the montmorillonite with deionized water to elute the excess compound;

[0153] S4. The treated montmorillonite is dried at 105 °C until it reaches a constant weight; then it is ground fine to 300 - 500 mesh with a mortar;

[0154] S5. Weigh 0.2 g of the montmorillonite treated with the fluorinated imidazolium salt, place it in a constant temperature and humidity environment (25 °C, relative humidity of 100%), and wait for the montmorillonite to fully adsorb water vapor;

[0155] S6. Use a differential scanning calorimeter (DSC823 type) to measure the DSC curve of the moisture-absorbed montmorillonite; the test conditions are: nitrogen atmosphere, temperature rise range 10 - 200 °C, temperature rise rate 10 °C / min;

[0156] Taking the fully moisture-absorbed original montmorillonite as the control group, the DSC curve of the montmorillonite treated with the fluorinated imidazolium salt and moisture-absorbed is as Figure 2 shown.

[0157] 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 vapor on the surface of montmorillonite. After the fluorinated imidazolium salt, the two groups of peaks shift to lower temperatures and the intensity decreases significantly, indicating that the fluorinated imidazolium salt significantly weakens the hydration effect on the surface of montmorillonite. When the fluorinated imidazolium salt acts on the formation, this will be beneficial to weakening the thickness of the water film on the pore surface and increasing the effective pore radius and pore connectivity.

[0158] 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 solution obtained by using equivalent substitution or equivalent transformation falls within the scope of the present invention.

Claims

1. Application of a fluorine-containing imidazolium salt in oil and gas production, 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; 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 use of the fluorine-containing imidazolium salt in oil and gas production according to claim 1, characterized in that: The X is chlorine, bromine or iodine.

3. The use of the fluorine-containing imidazolium salt in oil and gas production according to claim 2, characterized in that: The specific structural formula of the fluorine-containing imidazolium salt is as follows: 。

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