Sulfonated lignite applied to drilling fluid and preparation method thereof

Abstract

The application relates to the technical field of petroleum drilling fluid treating agents, and discloses sulfonated lignite applied to drilling fluid and a preparation method thereof, the preparation method being as follows: modified lignite and modified 4,4'-diamino diphenyl ether are mixed, the temperature is increased to 120-140 DEG C, and stirring reaction is carried out for 1-2 hours, then modified diethanolamine is slowly added dropwise, and the reaction is continuously carried out for 0.5-1 hour, the reaction mixture is poured into a mold, the temperature is increased to 160-180 DEG C, and the temperature is kept under 10-20 MPa for 2-4 hours, and sulfonated lignite applied to drilling fluid is obtained after crushing. The sulfonated lignite prepared by the application has good high-temperature stability and salt resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of petroleum drilling fluid treatment agents, in particular to a sulfonated lignite applied to drilling fluid and a preparation method thereof. BACKGROUND

[0002] During deep well drilling, the bottom hole temperature is high, the pressure is high, the formation structure is complex, and during the drilling process, complex formations such as high-pressure oil and gas layers, gypsolite and high-pressure brine layers are often encountered. During the drilling operation, problems such as soft mudstone and gypsolite creep, high-pressure brine intrusion, wellbore instability, etc. may occur, thereby causing downhole complex accidents such as sticking, drilling fluid pollution, wellbore collapse, overflow, etc., which brings great difficulty and risk to drilling operations. Conventional drilling fluids have poor high-temperature stability and insufficient filtration loss control. Lignite is rich in humic acid and has adsorption and dispersion properties, but direct application has poor water solubility, weak salt and calcium resistance, etc. Therefore, how to avoid this phenomenon is the key to solving the problem. For example, patent CN120248367A discloses an anti-high-temperature lignite resin and a preparation method thereof. The lignite resin has good high-temperature resistance, but the salt resistance needs to be improved. SUMMARY

[0003] (I) Technical problems solved

[0004] In view of the deficiencies of the prior art, the present application provides a sulfonated lignite applied to drilling fluid and a preparation method thereof. The sulfonated lignite prepared by the present application has good high-temperature stability and salt resistance.

[0005] (II) Technical solutions

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions: a sulfonated lignite applied to drilling fluid, comprising the following weight components: 30-35 parts by weight of modified lignite, 4-6 parts by weight of modified 4,4'-diamino diphenyl ether, and 1-3 parts by weight of modified diethanolamine.

[0007] Further, the preparation method of the modified lignite is as follows: the lignite is crushed to 80-100 mesh, the particle size is 0.15-0.18 mm, the impurities are removed by acid washing with 5-10% dilute sulfuric acid, sodium sulfite is added, and the reaction is carried out at 110-130℃ for 2-3h, then sodium dichromate is added to the system, and the reaction is carried out at 80-90℃ under alkaline conditions for 1-2h for chromium salt crosslinking, finally 0.8-2.2mol / L of dilute hydrochloric acid is added to adjust the pH to 6-7, the reaction is terminated, and spray drying is carried out at an inlet temperature of 180-200℃ to obtain the modified lignite.

[0008] Further, the lignite, dilute sulfuric acid, sodium sulfite, sodium dichromate, dilute hydrochloric acid are used in a ratio of 3.41-3.45 g: 20-22 mL: 1.12-1.18 g: 0.3-0.5 g: 1.2-1.4 mL.

[0009] Further, the preparation method of the modified 4,4'-diamino diphenyl ether is:

[0010] Step one: 4,4'-diamino diphenyl ether is added to anhydrous ethanol solvent, stirred and mixed, warmed to 65-75°C, and epichlorohydrin is added dropwise. After refluxing for 40-50 h, the reaction is naturally cooled to room temperature, column chromatography is used for purification, and drying is performed to obtain intermediate 1.

[0011] Step two: Under the protection of nitrogen gas, intermediate 1 and 3-aminopropyl triethoxysilane are added to N,N-dimethylformamide solvent, stirred and mixed, then triethylamine is added, and the reaction is performed at 75-90°C for 4-6 h. After the reaction is completed, filtration, washing and drying are performed to obtain intermediate 2.

[0012] Step three: 4.21-4.25 g of nano silicon dioxide is dispersed in 25-30 mL of anhydrous ethanol, ultrasonic treatment is performed for 25-30 min, vacuum drying is performed at 100-110°C for 2-3 h, then 2.08-2.11 g of intermediate 2 and 0.3-0.5 mL of acetic acid are added, stirring and mixing are performed, refluxing is performed at 60-75°C for 6-12 h under the protection of nitrogen gas, and after the reaction is completed, centrifugation, washing and drying are performed to obtain modified 4,4'-diamino diphenyl ether.

[0013] Further, the ethanol, 4,4'-diamino diphenyl ether and epichlorohydrin in step one are used in a ratio of 15-20 mL: 2.12-2.16 g: 5.04-5.08 g.

[0014] Further, the N,N-dimethylformamide, intermediate 1, 3-aminopropyl triethoxysilane and triethylamine in step two are used in a ratio of 20-22 mL: 1.83-1.85 g: 3.73-3.78 g: 0.03-0.04 g.

[0015] Further, the preparation method of the modified diethanolamine is:

[0016] S1: Under the protection of nitrogen gas, diethanolamine and 3-mercaptopropionic acid are added to dichloromethane solvent, stirring and mixing are performed, then 4-dimethylaminopyridine is added, and the reaction is performed at 35-40°C for 12-16 h. After the reaction is completed, the solvent is removed by rotary evaporation, and drying is performed to obtain intermediate 3.

[0017] S2: under the protection of nitrogen gas, adding intermediate 3, methacryloyloxyethyl trimethyl ammonium chloride into ethanol solvent, stirring and mixing, then adding 2,2-dimethoxy-2-phenylacetophenone photoinitiator, irradiating under 365nm ultraviolet light at 25-40℃ for 2-4h, after the end, centrifugal separation, washing and drying, obtaining intermediate 4;

[0018] S3: under the protection of nitrogen gas, adding 3.12-3.16g of intermediate 4, 0.03-0.05g of triethylamine into 25-30mL of N,N-dimethylformamide solvent, stirring at 55-60℃ for 25-30min, then slowly adding 2.66-2.68g of 1-chlorododecane, heating to 75-80℃, refluxing for 24-48h, after the reaction is completed, cooling to room temperature, precipitating and drying, obtaining modified diethanolamine.

[0019] Further, the amount ratio of dichloromethane, diethanolamine, 3-mercaptopropionic acid and 4-dimethylaminopyridine in S1 is 15-18mL:1.62-1.66g:2.44-2.48g:0.12-0.15g.

[0020] Further, the amount ratio of ethanol, intermediate 3, methacryloyloxyethyl trimethyl ammonium chloride and 2,2-dimethoxy-2-phenylacetophenone in S2 is 22-25mL:2.23-2.26g:3.64-3.67g:0.04-0.06g.

[0021] Further, the preparation method of the sulfonated lignite applied to drilling fluid is: mixing modified lignite and modified 4,4'-diamino diphenyl ether, heating to 120-140℃, stirring and reacting for 1-2h, then slowly adding modified diethanolamine, continuing to react for 0.5-1h, pouring the reaction mixture into a mold, heating to 160-180℃, keeping at 10-20MPa for 2-4h, after crushing, obtaining sulfonated lignite applied to drilling fluid.

[0022] (III) Beneficial technical effects

[0023] The present application can improve the high-temperature stability of lignite by introducing sulfonic acid groups into lignite through sulfonation treatment, and the sulfonic acid groups can still be ionized at high temperature to avoid the failure caused by the degradation of lignite at high temperature. The thickened hydration film on the surface of the lignite particles after sulfonation can effectively block the pores in the filter cake and reduce the permeation of water to the formation, thereby reducing the fluid loss. 4,4'-diamino diphenyl ether has a rigid aromatic ring structure, which can inhibit the high-temperature depolymerization of the molecular chain of sulfonated lignite. 3-aminopropyl triethoxysilane and nano silicon dioxide are modified, and silicon hydroxyl groups are introduced, which can form hydrogen bonds or condensation bonds with sulfonated lignite to construct a three-dimensional network structure, inhibit the degradation of lignite molecules at high temperature, and improve the high-temperature resistance of the fluid loss additive. The hydroxyl and amine groups of diethanolamine can form a soluble complex with metal ions, reducing the flocculation of high-valence metal ions on sulfonated lignite and improving the salt tolerance of the fluid loss additive. The methyl acryloyl oxyethyl trimethyl ammonium chloride is modified, and a quaternary ammonium salt group is introduced. The quaternary ammonium salt group can be adsorbed on the surface of clay through electrostatic action to inhibit hydration expansion, and can also neutralize the negative charge of clay to enhance the salt resistance of the fluid loss additive. The long-chain alkyl is grafted onto the lignite molecule to impart hydrophobicity. The hydrophobic lignite can form a denser mud cake on the well wall to reduce the fluid loss. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a synthetic reaction formula of intermediate 2.

[0025] Figure 2 is a synthetic reaction formula of modified diethanolamine. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application is described clearly and completely. Obviously, the described embodiments are part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0027] In order to better understand the above technical scheme, the above technical scheme will be described in detail in combination with the drawings and specific embodiments in the specification.

[0028] Embodiment 1

[0029] (1) 3.41 g of lignite was crushed to 80 mesh, 0.15 mm in particle size, washed with 20 mL of 5% mass fraction dilute sulfuric acid to remove impurities, 1.12 g of sodium sulfite was added, reacted at 110°C for 2 h, then 0.3 g of sodium dichromate was added to the system, reacted at 80°C for 1 h under alkaline conditions for chromium salt crosslinking, finally 1.2 mL of 0.8 mol / L dilute hydrochloric acid was added to adjust the pH to 6, and the reaction was terminated, and spray drying was carried out at an inlet temperature of 180°C to obtain modified lignite;

[0030] (2) 2.12 g of 4,4'-diamino diphenyl ether was added to 15 mL of anhydrous ethanol solvent, stirred and mixed, warmed to 65°C, 5.04 g of epichlorohydrin was added dropwise, refluxed for 40 h, after the reaction was completed, it was naturally cooled to room temperature, purified by column chromatography, and dried to obtain intermediate 1;

[0031] (3) Under nitrogen gas protection, 1.83 g of intermediate 1, 3.73 g of 3-aminopropyl triethoxysilane was added to 20 mL of N,N-dimethylformamide solvent, stirred uniformly, then 0.03 g of triethylamine was added, reacted at 75°C for 4 h, after the reaction was completed, it was filtered, washed and dried to obtain intermediate 2;

[0032] (4) 4.21 g of nano silicon dioxide was dispersed in 25 mL of anhydrous ethanol, ultrasonically treated for 25 min, vacuum dried at 100°C for 2 h, then 2.08 g of intermediate 2, 0.3 mL of acetic acid was added, stirred and mixed, under nitrogen gas protection, refluxed at 60°C for 6 h, after the reaction was completed, it was centrifuged, washed and dried to obtain modified 4,4'-diamino diphenyl ether;

[0033] (5) Under nitrogen gas protection, 1.62 g of diethanolamine, 2.44 g of 3-mercaptopropionic acid was added to 15 mL of dichloromethane solvent, stirred and mixed, then 0.12 g of 4-dimethylamino pyridine was added, reacted at 35°C for 12 h, after the reaction was completed, the solvent was removed by rotary evaporation, and dried to obtain intermediate 3;

[0034] (6) Under nitrogen gas protection, 2.23 g of intermediate 3, 3.64 g of methacryloyloxyethyl trimethyl ammonium chloride was added to 22 mL of ethanol solvent, stirred and mixed, then 0.04 g of 2,2-dimethoxy-2-phenyl phenylacetophenone photoinitiator was added, irradiated with 365 nm ultraviolet light at 25°C for 2 h, after the reaction was completed, it was centrifuged, washed and dried to obtain intermediate 4;

[0035] (7) Under the protection of nitrogen gas, 3.12 g of intermediate 4, 0.03 g of triethylamine was added to 25 mL of N,N-dimethylformamide solvent, stirred at 55°C for 25 min, then 2.66 g of 1-chlorododecane was slowly added dropwise, the temperature was raised to 75°C, and refluxed for 24 h. After the reaction was completed, it was cooled to room temperature, precipitated, and dried to obtain modified diethanolamine;

[0036] (8) 30 parts by weight of modified lignite and 4 parts by weight of modified 4,4'-diamino diphenyl ether were mixed, the temperature was raised to 120°C, and stirred for 1 h, then 1 part by weight of modified diethanolamine was slowly added dropwise, and the reaction was continued for 0.5 h. The reaction mixture was poured into a mold, the temperature was raised to 160°C, and maintained at 10 MPa for 2 h. After crushing, sulfonated lignite for drilling fluid was obtained.

[0037] Example 2

[0038] (1) 3.45 g of lignite was crushed to 100 mesh, the particle size was 0.18 mm, and impurities were removed by acid washing with 22 mL of 10% dilute sulfuric acid. 1.18 g of sodium sulfite was added, and the reaction was carried out at 130°C for 3 h. Then 0.5 g of sodium dichromate was added to the system, and the reaction was carried out under alkaline conditions at 90°C for 2 h for chromium salt crosslinking. Finally, 1.4 mL of 2.2 mol / L dilute hydrochloric acid was added to adjust the pH to 7, and the reaction was terminated. Spray drying was carried out at an inlet temperature of 200°C to obtain modified lignite;

[0039] (2) 2.16 g of 4,4'-diamino diphenyl ether was added to 20 mL of anhydrous ethanol solvent, stirred and mixed, the temperature was raised to 75°C, and 5.08 g of epichlorohydrin was added dropwise. The reaction was refluxed for 50 h. After the reaction was completed, it was naturally cooled to room temperature, purified by column chromatography, and dried to obtain intermediate 1;

[0040] (3) Under the protection of nitrogen gas, 1.85 g of intermediate 1, 3.78 g of 3-aminopropyl triethoxysilane was added to 22 mL of N,N-dimethylformamide solvent, stirred uniformly, then 0.04 g of triethylamine was added, and the reaction was carried out at 90°C for 6 h. After the reaction was completed, it was filtered, washed and dried to obtain intermediate 2;

[0041] (4) 4.25 g of nano silicon dioxide was dispersed in 30 mL of anhydrous ethanol, ultrasonic treated for 30 min, vacuum dried at 110°C for 3 h, then 2.11 g of intermediate 2, 0.5 mL of acetic acid was added, stirred and mixed, and the reaction was carried out at 75°C under the protection of nitrogen gas for 12 h. After the reaction was completed, it was centrifuged, washed and dried to obtain modified 4,4'-diamino diphenyl ether;

[0042] (5) Under the protection of nitrogen gas, 1.66 g of diethanolamine, 2.48 g of 3- mercaptopropionic acid were added to 18 mL of dichloromethane solvent, stirred and mixed, then 0.15 g of 4-dimethylaminopyridine was added, reacted at 40℃ for 16 h, after the reaction was completed, the solvent was removed by rotary evaporation, and dried to obtain intermediate 3;

[0043] (6) Under the protection of nitrogen gas, 2.26 g of intermediate 3, 3.67 g of methacryloyloxyethyl trimethylammonium chloride were added to 25 mL of ethanol solvent, stirred and mixed, then 0.06 g of 2,2-dimethoxy-2-phenylacetophenone photoinitiator was added, irradiated with 365 nm ultraviolet light at 40℃ for 4 h, after the end, centrifugal separation, washing and drying to obtain intermediate 4;

[0044] (7) Under the protection of nitrogen gas, 3.16 g of intermediate 4, 0.05 g of triethylamine were added to 30 mL of N,N-dimethylformamide solvent, stirred at 60℃ for 30 min, then 2.68 g of 1-chlorododecane was slowly added dropwise, warmed to 80℃, refluxed for 48 h, after the reaction was completed, cooled to room temperature, precipitated and dried to obtain modified diethanolamine;

[0045] (8) 35 parts by weight of modified lignite and 6 parts by weight of modified 4,4'-diamino diphenyl ether were mixed, warmed to 140℃, stirred and reacted for 2 h, then 3 parts by weight of modified diethanolamine was slowly added dropwise, and the reaction was continued for 1 h, the reaction mixture was poured into a mold, warmed to 180℃, and kept at 20 MPa for 4 h, after crushing, sulfonated lignite for drilling fluid was obtained.

[0046] Example 3

[0047] (1) 3.43 g of lignite was crushed to 90 mesh, the particle size was 0.16 mm, and the impurities were removed by acid washing with 21 mL of 5% mass fraction dilute sulfuric acid, 1.15 g of sodium sulfite was added, reacted at 120℃ for 2.5 h, then 0.4 g of sodium dichromate was added to the system, reacted at 85℃ under alkaline conditions for 1.5 h for chromium salt crosslinking, finally 1.3 mL of 1.5 mol / L molar concentration dilute hydrochloric acid was added to adjust the pH to 6, and the reaction was terminated, and spray drying was carried out at an inlet temperature of 190℃ to obtain modified lignite;

[0048] (2) 2.14 g of 4,4'-diamino diphenyl ether was added to 18 mL of anhydrous ethanol solvent, stirred and mixed, warmed to 70℃, and 5.06 g of epichlorohydrin was added dropwise, refluxed for 45 h, after the reaction was completed, naturally cooled to room temperature, purified by column chromatography, and dried to obtain intermediate 1;

[0049] (3) Under nitrogen gas protection, 1.84 g of intermediate 1, 3.75 g of 3- aminopropyltriethoxysilane were added into 21 mL of N,N-dimethylformamide solvent, stirred uniformly, then 0.03 g of triethylamine was added, reacted at 80°C for 5 h, after the reaction was completed, filtration, washing and drying were performed to obtain intermediate 2;

[0050] (4) 4.23 g of nano-silica was dispersed in 28 mL of anhydrous ethanol, ultrasonic treatment was performed for 28 min, vacuum drying was performed at 105°C for 2.5 h, then 2.1 g of intermediate 2, 0.4 mL of acetic acid were added, stirring was performed, under nitrogen gas protection, 70°C reflux was performed for 9 h, after the reaction was completed, centrifugation, washing and drying were performed to obtain modified 4,4'-diamino diphenyl ether;

[0051] (5) Under nitrogen gas protection, 1.64 g of diethanolamine, 2.46 g of 3- mercaptopropionic acid were added into 16 mL of dichloromethane solvent, stirring was performed, then 0.13 g of 4-dimethylaminopyridine was added, reacted at 38°C for 14 h, after the reaction was completed, rotary evaporation was performed to remove the solvent, drying was performed to obtain intermediate 3;

[0052] (6) Under nitrogen gas protection, 2.25 g of intermediate 3, 3.65 g of methacryloyloxyethyl trimethyl ammonium chloride were added into 23 mL of ethanol solvent, stirring was performed, then 0.05 g of 2,2-dimethoxy-2-phenylacetophenone photoinitiator was added, irradiation was performed under 365 nm ultraviolet light at 30°C for 3 h, after the reaction was completed, centrifugal separation, washing and drying were performed to obtain intermediate 4;

[0053] (7) Under nitrogen gas protection, 3.14 g of intermediate 4, 0.04 g of triethylamine were added into 28 mL of N,N-dimethylformamide solvent, stirring was performed at 58°C for 28 min, then 2.67 g of 1-chlorododecane was slowly added dropwise, the temperature was increased to 78°C, reflux was performed for 36 h, after the reaction was completed, the temperature was cooled to room temperature, precipitation, drying were performed to obtain modified diethanolamine;

[0054] (8) 32 parts by weight of modified lignite and 5 parts by weight of modified 4,4'-diamino diphenyl ether were mixed, the temperature was increased to 130°C, stirring was performed for 1.5 h, then 2 parts by weight of modified diethanolamine was slowly added dropwise, the reaction was continuously performed for 0.75 h, the reaction mixture was poured into a mold, the temperature was increased to 170°C, 3 h was maintained under 15 MPa, after crushing, sulfonated lignite for drilling fluid was obtained.

[0055] Example 4

[0056] (1) 3.42 g of lignite was crushed to 85 mesh, 0.17 mm in particle size, washed with 20 mL of 5% mass fraction dilute sulfuric acid to remove impurities, 1.13 g of sodium sulfite was added, and reacted at 115°C for 2 h. Then 0.3 g of sodium dichromate was added to the system, and reacted at 82°C for 1 h under alkaline conditions for chromium salt crosslinking. Finally, 1.2 mL of 1.2 mol / L dilute hydrochloric acid was added to adjust the pH to 6, and the reaction was terminated. Spray drying was carried out at an inlet temperature of 185°C to obtain modified lignite;

[0057] (2) 2.13 g of 4,4'-diamino diphenyl ether was added to 16 mL of anhydrous ethanol solvent, stirred and mixed, and warmed to 68°C. 5.05 g of epichlorohydrin was added dropwise, and refluxed for 42 h. After the reaction was completed, it was naturally cooled to room temperature, purified by column chromatography, and dried to obtain intermediate 1;

[0058] (3) Under nitrogen gas protection, 1.83 g of intermediate 1, 3.74 g of 3-aminopropyl triethoxysilane, and 0.03 g of triethylamine were added to 20 mL of N,N-dimethylformamide solvent, stirred uniformly, and then reacted at 78°C for 4 h. After the reaction was completed, it was filtered, washed, and dried to obtain intermediate 2;

[0059] (4) 4.22 g of nano-silicon dioxide was dispersed in 26 mL of anhydrous ethanol, ultrasonically treated for 26 min, vacuum dried at 102°C for 2 h, and then 2.09 g of intermediate 2 and 0.3 mL of acetic acid were added, stirred and mixed, and refluxed at 65°C for 8 h under nitrogen gas protection. After the reaction was completed, it was centrifuged, washed, and dried to obtain modified 4,4'-diamino diphenyl ether;

[0060] (5) Under nitrogen gas protection, 1.63 g of diethanolamine and 2.45 g of 3-mercaptopropionic acid were added to 16 mL of dichloromethane solvent, stirred and mixed, and then 0.13 g of 4-dimethylamino pyridine was added. The reaction was carried out at 36°C for 13 h. After the reaction was completed, the solvent was removed by rotary evaporation, and dried to obtain intermediate 3;

[0061] (6) Under nitrogen gas protection, 2.24 g of intermediate 3 and 3.64 g of methacryloyloxyethyl trimethyl ammonium chloride were added to 23 mL of ethanol solvent, stirred and mixed, and then 0.04 g of 2,2-dimethoxy-2-phenyl phenylacetone photoinitiator was added. The reaction was carried out at 30°C under 365 nm ultraviolet light irradiation for 2 h. After the reaction was completed, it was centrifuged, washed, and dried to obtain intermediate 4;

[0062] (7) Under the protection of nitrogen gas, 3.13 g of intermediate 4, 0.03 g of triethylamine was added to 26 mL of N,N-dimethylformamide solvent, stirred at 56°C for 26 min, then 2.66 g of 1-chlorododecane was slowly added dropwise, the temperature was raised to 76°C, and refluxed for 30 h. After the reaction was completed, it was cooled to room temperature, precipitated, and dried to obtain modified diethanolamine;

[0063] (8) 31 parts by weight of modified lignite and 4 parts by weight of modified 4,4'-diamino diphenyl ether were mixed, the temperature was raised to 125°C, and stirred for 1 h, then 1 part by weight of modified diethanolamine was slowly added dropwise, and the reaction was continued for 0.6 h. The reaction mixture was poured into a mold, the temperature was raised to 165°C, and maintained at 12 MPa for 2 h. After crushing, sulfonated lignite for drilling fluid was obtained.

[0064] Example 5

[0065] (1) 3.44 g of lignite was crushed to 95 mesh, 0.18 mm in particle size, and washed with 22 mL of 10% dilute sulfuric acid to remove impurities. 1.16 g of sodium sulfite was added, and the reaction was carried out at 125°C for 3 h. Then 0.5 g of sodium dichromate was added to the system, and the reaction was carried out at 88°C under alkaline conditions for 2 h for chromium salt crosslinking. Finally, 1.4 mL of 2 mol / L dilute hydrochloric acid was added to adjust the pH to 7, and the reaction was terminated. Spray drying was carried out at an inlet temperature of 180-200°C to obtain modified lignite;

[0066] (2) 2.15 g of 4,4'-diamino diphenyl ether was added to 19 mL of anhydrous ethanol solvent, stirred and mixed, the temperature was raised to 72°C, 5.07 g of epichlorohydrin was added dropwise, and refluxed for 48 h. After the reaction was completed, it was naturally cooled to room temperature, purified by column chromatography, and dried to obtain intermediate 1;

[0067] (3) Under the protection of nitrogen gas, 1.85 g of intermediate 1, 3.77 g of 3-aminopropyl triethoxysilane was added to 22 mL of N,N-dimethylformamide solvent, stirred uniformly, then 0.04 g of triethylamine was added, and the reaction was carried out at 85°C for 5 h. After the reaction was completed, it was filtered, washed and dried to obtain intermediate 2;

[0068] (4) 4.24 g of nano-silicon dioxide was dispersed in 28 mL of anhydrous ethanol, ultrasonic treated for 28 min, vacuum dried at 108°C for 3 h, then 2.1 g of intermediate 2, 0.5 mL of acetic acid was added, stirred and mixed, and refluxed at 72°C for 10 h under the protection of nitrogen gas. After the reaction was completed, it was centrifuged, washed and dried to obtain modified 4,4'-diamino diphenyl ether;

[0069] (5) Under nitrogen gas protection, 1.65 g of diethanolamine, 2.47 g of 3- mercaptopropionic acid were added to 17 mL of dichloromethane solvent, stirred and mixed, then 0.14 g of 4-dimethylaminopyridine was added, reacted at 38°C for 15 h, after the reaction was completed, the solvent was removed by rotary evaporation, and dried to obtain intermediate 3;

[0070] (6) Under nitrogen gas protection, 2.25 g of intermediate 3, 3.66 g of methacryloyloxyethyl trimethylammonium chloride were added to 24 mL of ethanol solvent, stirred and mixed, then 0.06 g of 2,2-dimethoxy-2-phenylacetophenone photoinitiator was added, irradiated with 365 nm ultraviolet light at 35°C for 4 h, after the end, centrifugal separation, washing and drying were carried out to obtain intermediate 4;

[0071] (7) Under nitrogen gas protection, 3.15 g of intermediate 4, 0.05 g of triethylamine were added to 28 mL of N,N-dimethylformamide solvent, stirred at 58°C for 28 min, then 2.68 g of 1-chlorododecane was slowly added dropwise, warmed to 78°C, refluxed for 40 h, after the reaction was completed, cooled to room temperature, precipitated and dried to obtain modified diethanolamine;

[0072] (8) 34 parts by weight of modified lignite and 6 parts by weight of modified 4,4'-diamino diphenyl ether were mixed, warmed to 135°C, stirred and reacted for 2 h, then 3 parts by weight of modified diethanolamine was slowly added dropwise, and the reaction was continued for 0.8 h, the reaction mixture was poured into a mold, warmed to 175°C, and kept at 20 MPa for 4 h, after crushing, sulfonated lignite for drilling fluid was obtained.

[0073] Comparative Example 1

[0074] This comparative example is different from Example 5 in that no modified 4,4'-diamino diphenyl ether is added.

[0075] Comparative Example 2

[0076] This comparative example is different from Example 5 in that no modified diethanolamine is added.

[0077] Performance test:

[0078] The sulfonated lignite prepared in Examples 1-5 and Comparative Examples 1-2 was subjected to performance test.

[0079] (1) The high temperature resistance test method is as follows: according to SY / T 5490-2019 “Drilling fluid material high temperature and high pressure performance evaluation method”, the drilling fluid base slurry is configured, and the specific configuration method is as follows: 1000 mL of distilled water is taken, 4% bentonite is added, high-speed stirring is carried out at 11000 rpm for 20 min, and the system is left to stand at room temperature for 24 h to obtain the base slurry, the base slurry is divided into seven parts, and the sulfonated lignite prepared by examples 1-5 and comparative examples 1-2 is added, high-speed stirring is continued for 30 min, 400 mL of each is taken, and the system is left to stand at 3.5 MPa and different temperatures for 24 h, and the API filtration loss of the drilling fluid is measured. The test results are shown in Table 1.

[0080] Table 1: High temperature resistance test table.

[0081]

[0082] As can be seen from Table 1, the sulfonated lignite drilling fluid base slurry prepared by examples 1-5 can maintain a lower filtration loss under high temperature conditions compared with the sulfonated lignite drilling fluid base slurry prepared by comparative examples 1-2, and has good high temperature resistance.

[0083] (2) The salt resistance test method is as follows: according to SY / T 5621-2016 “Drilling fluid test procedure”, the drilling fluid base slurry is configured, and the specific configuration method is as follows: 1000 mL of distilled water is taken, 4% bentonite is added, high-speed stirring is carried out at 11000 rpm for 20 min, different contents of sodium chloride are added to the system, and the system is left to stand at room temperature for 24 h to obtain the base slurry, the base slurry is divided into seven parts, and the sulfonated lignite prepared by examples 1-5 and comparative examples 1-2 is added, high-speed stirring is continued for 30 min, 400 mL of each is taken, and the system is left to stand at 3.5 MPa and room temperature for 24 h, and the API filtration loss of the drilling fluid is measured. The test results are shown in Table 2.

[0084] Table 2: Salt resistance test table.

[0085]

[0086] As can be seen from Table 2, the sulfonated lignite drilling fluid base slurry prepared by examples 1-5 can maintain a lower filtration loss under high salt conditions compared with the sulfonated lignite drilling fluid base slurry prepared by comparative examples 1-2, and has good high temperature resistance.

[0087] It should be noted that, in the present document, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the recited element.

[0088] The above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for some technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

[0089] Those skilled in the art should understand that the above only describes some specific embodiments of the present application, rather than all embodiments. It should be noted that many modifications and improvements can be made by those skilled in the art, and all modifications and improvements that do not exceed the scope of the claims should be considered as the protection scope of the present application.

Claims

1. A sulfonated lignite for use in drilling fluids, characterized in that, It includes the following components by weight: 30-35 parts by weight of modified lignite, 4-6 parts by weight of modified 4,4'-diaminodiphenyl ether, and 1-3 parts by weight of modified diethanolamine; The modified 4,4'-diaminodiphenyl ether is prepared by: Step 1: Add 4,4'-diaminodiphenyl ether to anhydrous ethanol solvent, stir and mix, heat to 65-75℃, add epichlorohydrin dropwise, reflux for 40-50h, after the reaction is completed, cool naturally to room temperature, purify by column chromatography, dry, and obtain intermediate 1; Step 2: Under nitrogen protection, add intermediate 1,3-aminopropyltriethoxysilane to N,N-dimethylformamide solvent, stir until homogeneous, then add triethylamine, and react at 75-90℃ for 4-6 hours. After the reaction is complete, filter, wash and dry to obtain intermediate 2. Step 3: Disperse 4.21-4.25g of nano-silica in 25-30mL of anhydrous ethanol, sonicate for 25-30min, vacuum dry at 100-110℃ for 2-3h, then add 2.08-2.11g of intermediate 2 and 0.3-0.5mL of acetic acid, stir and mix, reflux at 60-75℃ for 6-12h under nitrogen protection. After the reaction is complete, centrifuge, wash and dry to obtain modified 4,4'-diaminodiphenyl ether. The modified diethanolamine is prepared by: S1: Under nitrogen protection, diethanolamine and 3-mercaptopropionic acid were added to dichloromethane solvent and stirred and mixed. Then 4-dimethylaminopyridine was added and reacted at 35-40℃ for 12-16 h. After the reaction was completed, the solvent was removed by rotary evaporation and dried to obtain intermediate 3. S2: Under nitrogen protection, intermediate 3 and methacryloyloxyethyltrimethylammonium chloride were added to ethanol solvent and stirred. Then, 2,2-dimethoxy-2-phenylacetophenone photoinitiator was added and irradiated with 365nm ultraviolet light at 25-40℃ for 2-4 hours. After the irradiation, the mixture was centrifuged, washed and dried to obtain intermediate 4. S3: Under nitrogen protection, add 3.12-3.16 g of intermediate 4 and 0.03-0.05 g of triethylamine to 25-30 mL of N,N-dimethylformamide solvent. Stir at 55-60 °C for 25-30 min, then slowly add 2.66-2.68 g of 1-chlorododecane. Heat to 75-80 °C and reflux for 24-48 h. After the reaction is complete, cool to room temperature, precipitate, and dry to obtain modified diethanolamine.

2. The sulfonated lignite for use in drilling fluid according to claim 1, characterized in that, The modified lignite is prepared as follows: lignite is pulverized to 80-100 mesh with a particle size of 0.15-0.18 mm, and impurities are removed by acid washing with 5-10% dilute sulfuric acid. Sodium sulfite is added, and the reaction is carried out at 110-130℃ for 2-3 hours. Then, sodium dichromate is added to the system, and the reaction is carried out at 80-90℃ under alkaline conditions for 1-2 hours to crosslink the chromium salt. Finally, dilute hydrochloric acid with a molar concentration of 0.8-2.2 mol / L is added to adjust the pH to 6-7 to terminate the reaction. The mixture is then spray-dried at an inlet temperature of 180-200℃ to obtain the modified lignite.

3. The sulfonated lignite used in drilling fluid according to claim 2, characterized in that, The ratio of lignite, dilute sulfuric acid, sodium sulfite, sodium dichromate, and dilute hydrochloric acid is 3.41-3.45g: 20-22mL: 1.12-1.18g: 0.3-0.5g: 1.2-1.4mL.

4. The sulfonated lignite used in drilling fluid according to claim 1, characterized in that, In step one, the ratio of ethanol, 4,4'-diaminodiphenyl ether, and epichlorohydrin is 15-20 mL: 2.12-2.16 g: 5.04-5.08 g.

5. The sulfonated lignite for use in drilling fluid according to claim 1, characterized in that, In step two, the ratio of N,N-dimethylformamide, intermediate 1,3-aminopropyltriethoxysilane, and triethylamine is 20-22 mL: 1.83-1.85 g: 3.73-3.78 g: 0.03-0.04 g.

6. The sulfonated lignite for use in drilling fluid according to claim 1, characterized in that, The ratio of dichloromethane, diethanolamine, 3-mercaptopropionic acid, and 4-dimethylaminopyridine in S1 is 15-18 mL: 1.62-1.66 g: 2.44-2.48 g: 0.12-0.15 g.

7. The sulfonated lignite for use in drilling fluid according to claim 1, characterized in that, The ratio of ethanol, intermediate 3, methacryloyloxyethyltrimethylammonium chloride, and 2,2-dimethoxy-2-phenylacetophenone in S2 is 22-25 mL: 2.23-2.26 g: 3.64-3.67 g: 0.04-0.06 g.

8. A sulfonated lignite for use in drilling fluids as described in any one of claims 1-7, characterized in that, The method for preparing sulfonated lignite for drilling fluid is as follows: Modified lignite and modified 4,4'-diaminodiphenyl ether are mixed, heated to 120-140℃, and stirred for 1-2 hours. Then, modified diethanolamine is slowly added dropwise, and the reaction continues for 0.5-1 hours. The reaction mixture is poured into a mold, heated to 160-180℃, and maintained at 10-20 MPa for 2-4 hours. After pulverization, sulfonated lignite for drilling fluid is obtained.

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