A carboxyl-phenyl ring-carbon chain modified nanocellulose, its preparation method and application

Abstract

The present invention relates to the technical field of petrochemical engineering, and particularly relates to a carboxyl-benzene ring-carbon chain modified nanocellulose and its preparation method and application. By introducing carboxyl groups, benzene rings and carbon chains onto the surface of the nanocellulose, the present invention improves the temperature and salt tolerance of the nanocellulose; when the carboxyl-benzene ring-carbon chain modified nanocellulose is used to prepare a viscosifier, after aging at high temperature and high salinity, its viscosity retention rate is greater than 75%, and the thickening effect is remarkable.

Description

Technical Field

[0001] The present invention relates to the technical field of petrochemical engineering, and particularly relates to a carboxyl-benzene ring-carbon chain modified nanocellulose, a preparation method thereof, and an application thereof. Background Art

[0002] At present, chemical flooding is one of the main technical measures for improving the oil recovery factor in tertiary oil recovery. Chemical flooding includes alkali flooding, surfactant flooding, polymer flooding, and composite flooding. Among them, the polymer is one of the key chemical agents for implementing chemical flooding technology. It is required that the polymer can increase the viscosity of the displacing fluid, reduce the viscosity difference between the displacing fluid and the crude oil, and improve the sweep efficiency of the displacing fluid, so as to achieve the purpose of improving the oil recovery factor. At present, tertiary oil recovery technologies such as polymer flooding and composite flooding have been widely applied in major oil fields such as Shengli, Daqing, and Liaohe, and significant economic benefits have been achieved. Partially hydrolyzed polyacrylamide (HPAM) is the most commonly used polymer in oil fields at present, but HPAM has problems such as salt sensitivity effect, chemical degradation, and shear degradation, and is particularly sensitive to divalent ions. This greatly limits the application of HPAM in high-temperature and high-salinity reservoirs. At the same time, as an artificial synthetic polymer, HPAM also has certain harm to the environment. Therefore, developing a temperature and salt-resistant biopolymer as a viscosifier has great research value.

[0003] Chinese Patent Application CN112239656A (publication date: January 19, 2021) discloses a high-temperature resistant viscosity-increasing agent for drilling fluid and a preparation method thereof, which is a nanofiber-nano calcium carbonate composite. The viscosity-increasing agent includes the following components by mass percentage: cationic nanocellulose 28-30%, dispersant 6-8%, nano calcium carbonate 48-49%, and stearate 15-16%. Under normal temperature conditions, after the nanofiber-nano calcium carbonate composite is added to the base slurry, its apparent viscosity increases significantly, and its apparent viscosity only decreases slightly after aging. Nanocellulose has certain temperature resistance, but its salt resistance is poor. Summary of the Invention

[0004] The main purpose of the present invention is to provide a carboxyl-benzene ring-carbon chain modified nanocellulose, a preparation method thereof, and an application thereof. By introducing carboxyl, benzene ring, and carbon chain onto the surface of nanocellulose, the temperature and salt resistance of nanocellulose are improved; when the carboxyl-benzene ring-carbon chain modified nanocellulose is used to prepare a viscosifier, after aging at high temperature and high salinity, its viscosity retention rate is greater than 75%, and the viscosity-increasing effect is significant.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] The present invention provides a preparation method of a carboxyl-benzene ring-carbon chain modified nanocellulose, comprising the following steps:

[0007] The nanocellulose is subjected to oxidation treatment to obtain carboxylated nanocellulose; the carboxylated nanocellulose is subjected to benzene ring modification; the nanocellulose after benzene ring modification is subjected to carbon chain modification to obtain nanocellulose modified with benzene ring-carbon chain; the nanocellulose modified with benzene ring-carbon chain is subjected to oxidation treatment to obtain nanocellulose modified with carboxyl-benzene ring-carbon chain group.

[0008] Further, the method for subjecting nanocellulose to oxidation treatment: The nanocellulose is uniformly dispersed in water, tetramethylpiperidine oxide, sodium bromide, and sodium hypochlorite solution are added, the pH value of the solution is adjusted to 9-11, and the reaction is carried out for 10-16 h. After washing, dialysis, and centrifugation, carboxylated nanocellulose is obtained.

[0009] Furthermore, the dosage of each raw material is as follows: 3-5 parts by weight of nanocellulose, 0.1-0.3 parts by weight of tetramethylpiperidine oxide, 6-13 parts by weight of sodium bromide, and 30-60 parts by weight of sodium hypochlorite solution with a mass concentration of 5%-8%.

[0010] Further, the method for subjecting carboxylated nanocellulose to benzene ring modification includes the following steps:

[0011] The carboxylated nanocellulose is dispersed in water, the pH value of the solution is adjusted to 4-5, 1-ethyl-(3-dimethylaminopropyl)carbodiimide is added, and the mixture is stirred evenly; then N-hydroxysuccinimide is added and stirred evenly; the pH value of the solution is adjusted to 8-8.5, and then diphenylpropylamine is added, and the pH value of the solution is maintained at 8-8.5 for reaction for 24-36 h. After washing, dialysis, and centrifugation, nanocellulose modified with benzene ring is obtained.

[0012] Furthermore, the dosage of each raw material is as follows: 1-5 parts by weight of carboxylated nanocellulose, 0.1-0.6 parts by weight of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 0.07-0.3 parts by weight of N-hydroxysuccinimide, and 0.01-0.03 parts by weight of diphenylpropylamine.

[0013] Further, the method for subjecting the nanocellulose after benzene ring modification to carbon chain modification includes the following steps: The nanocellulose after benzene ring modification is dispersed in water, the pH value of the solution is adjusted to 4-5, 1-ethyl-(3-dimethylaminopropyl)carbodiimide is added, and the mixture is stirred evenly; then N-hydroxysuccinimide is added and stirred evenly; the pH value of the solution is adjusted to 8-8.5, and then alkylamine is added, and the pH of the solution is maintained at 8-8.5 for reaction for 24-36 h. After washing, dialysis, and centrifugation, nanocellulose modified with benzene ring-carbon chain is obtained.

[0014] Furthermore, the amounts of each raw material are as follows: 1-5 parts by weight of nanocellulose modified with a benzene ring, 0.1-0.6 parts by weight of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 0.07-0.3 parts by weight of N-hydroxysuccinimide, and 0.01-0.03 parts by weight of alkylamine.

[0015] The present invention also provides the application of the carboxyl-benzene ring-carbon chain modified nanocellulose described above, and the carboxyl-benzene ring-carbon chain modified nanocellulose prepared by the method described above, in the preparation of a viscosifier for oil recovery.

[0016] The present invention also provides a viscosifier for oil recovery, which comprises the carboxyl-benzene ring-carbon chain modified nanocellulose described above.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] By introducing carboxyl, benzene ring and carbon chain onto the surface of nanocellulose, the present invention improves the temperature and salt tolerance and amphiphilic properties of nanocellulose; when the carboxyl-benzene ring-carbon chain modified nanocellulose is used to prepare a viscosifier, after aging at high temperature and high salinity, its viscosity retention rate is greater than 75%, the thickening effect is significant, and it can effectively improve the oil recovery rate. Using the carboxyl-benzene ring-carbon chain modified nanocellulose to prepare a viscosifier is environmentally friendly and pollution-free.

[0019] The preparation method of the carboxyl-benzene ring-carbon chain modified nanocellulose of the present invention is simple, environmentally friendly, and easy to promote and apply. Description of the Drawings

[0020] Figure 1 It is the infrared spectrum of the carboxyl-benzene ring-carbon chain modified nanocellulose prepared by the method described in Example 1 of the present invention;

[0021] Figure 2 It is the curve graph of the changes in oil recovery rate, pressure and water cut. Detailed Description of the Invention

[0022] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0023] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, and / or combinations thereof.

[0024] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0025] The average degree of polymerization of the nanocellulose used in the following examples is between 8000 and 10000.

[0026] Example 1

[0027] A preparation method of carboxyl-benzene ring-carbon chain modified nanocellulose is as follows:

[0028] (1) Take 3 g of nanocellulose and stir it to disperse in 300 mL of deionized water, then add 0.124 g of TEMPO (2,2,6,6-tetramethylpiperidine oxide), 1.27 g of sodium bromide, and 45 g of sodium hypochlorite solution with a mass concentration of 8%. Adjust the pH of the solution to 10 and react at room temperature for 10 h. After washing, dialysis, and centrifugation with a large amount of deionized water, the oxidized carboxyl nanocellulose is obtained.

[0029] (2) Take 2 g of the oxidized carboxyl nanocellulose and disperse it in 200 mL of deionized water. Adjust the pH to 4.5, add 0.172 g of EDC (1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride) and stir for 15 min, then add 0.068 g of NHS (N-hydroxysuccinimide) and stir for 15 min. Adjust the pH of the solution to 8.5, then add 0.01 g of diphenylpropylamine, maintain the pH of the solution at 8.5, and stir and react at room temperature for 24 h. After washing, dialysis, and centrifugation with a large amount of deionized water, the benzene ring-modified nanocellulose (B-CNF) is obtained.

[0030] (3) Take 2 g of the oxidized B-CNF and disperse it in 200 mL of deionized water. Adjust the pH to 4.5, add 0.172 g of EDC (1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride) and stir for 30 min, then add 0.068 g of NHS (N-hydroxysuccinimide) and stir for 30 min. Adjust the pH of the solution to 8.5, then add 0.01 g of dodecylamine, maintain the pH of the solution at 8.5, and stir and react at room temperature for 24 h. After washing, dialysis, and centrifugation with a large amount of deionized water, the benzene ring-carbon chain modified nanocellulose (BC-CNF) is further obtained.

[0031] (4) Weigh 2 g of BC-CNF and disperse it in 200 mL of deionized water. Then add 0.124 g of TEMPO (2,2,6,6-tetramethylpiperidine oxide), 1.27 g of sodium bromide, and 45 g of sodium hypochlorite solution with a mass concentration of 8%. Adjust the pH of the solution to 10 and react at room temperature for 16 h. After washing with a large amount of deionized water, dialysis, and centrifugation, carboxyl-phenyl-ring-carbon-chain modified nanocellulose is obtained.

[0032] Fourier transform infrared spectroscopy (FTIR) tests were carried out on the nanocellulose and the carboxyl-phenyl-ring-carbon-chain modified nanocellulose prepared in Example 1 ( Figure 1 ). It can be seen that many new peaks appear in the spectrum of the carboxyl-phenyl-ring-carbon-chain modified nanocellulose. The peaks at 2930 cm -1 and 2850 cm -1 are due to the stretching vibration of methylene -CH2. The peak at 1730 cm -1 is due to the vibration of CO-NH, indicating that diphenylpropylamine and dodecylamine were successfully grafted onto the nanocellulose through the amidation reaction of amino and carboxyl groups. The peak at 1667 cm -1 is due to the stretching vibration of the C=O bond, indicating that the carboxyl group was successfully modified on the surface of the nanocellulose.

[0033] Example 2

[0034] A preparation method of carboxyl-phenyl-ring-carbon-chain modified nanocellulose. Compared with Example 1, the difference is that in steps (1) and (4), 30 g of sodium hypochlorite solution with a mass concentration of 8% is added and the reaction time is 16 h; in step (3), tetradecylamine is added, and other steps are the same as in Example 1.

[0035] Example 3

[0036] A preparation method of carboxyl-phenyl-ring-carbon-chain modified nanocellulose. Compared with Example 2, the difference is that in steps (2) and (3), the addition amount of EDC is 0.344 g, the addition amount of NHS is 0.136 g, and the addition amount of diphenylpropylamine is 0.03 g; in steps (1) and (4), 60 g of sodium hypochlorite solution with a mass concentration of 8% is added. Other steps are the same as in Example 1.

[0037] Example 4

[0038] A preparation method of carboxyl-phenyl-ring-carbon-chain modified nanocellulose. Compared with Example 3, the difference is that in steps (2) and (3), the addition amount of EDC is 0.516 g, the addition amount of NHS is 0.204 g, and the addition amount of dodecylamine is 0.03 g; in steps (1) and (4), 30 g of sodium hypochlorite solution with a mass concentration of 5% is added. Other steps are the same as in Example 1.

[0039] Example 5

[0040] A preparation method of carboxyl - benzene ring - carbon chain modified nanocellulose. Compared with Example 4, the difference of this method lies in that in steps (1) and (4), the addition amount of TEMPO is 0.248 g, 60 g of sodium hypochlorite solution with a mass concentration of 5% is added, and the reaction time is 24 h. Other steps are the same as those in Example 1.

[0041] The carboxyl - benzene ring - carbon chain modified nanocellulose prepared in Examples 1 - 5 was respectively formulated into an aqueous solution with a mass concentration of 0.1% using sodium chloride solutions with different concentrations, placed at 90 °C for 60 days, and then the viscosity before and after aging was measured using a Broookfield DV - II + PRO rotational viscometer at a rotational speed of 6 r / min. The viscosity retention rates at each salinity are shown in Table 1. And the following controls were set:

[0042] Control 1: Nanocellulose, that is, the nanocellulose used in step (1) of each example;

[0043] Control 2: Partially hydrolyzed polyacrylamide with a relative molecular mass of 16 million, a hydrolysis degree of 20%, and a solid content of 90%.

[0044] Control 3: The hydrophobically associating polymer reported in Patent 201910606703.1, whose structure is shown in the following formula (II), the carbon number of R is 12, m is about 1%, and n is about 99%.

[0045]

[0046] Control 4: Carboxyl nanocellulose, whose structure is shown in the following formula (III), m = 8000 - 10000.

[0047]

[0048] Table 1 Viscosity retention rates of the products in each example and comparative example after aging at different salinities

[0049]

[0050]

[0051] As can be seen from Table 1, nanocellulose has a good viscosity-increasing effect, and its viscosity-increasing effect does not decrease significantly after modification. The original nanocellulose has a certain temperature resistance, but its salt tolerance is poor. After high salinity and high temperature aging, its viscosity retention rate is only 32.4%. The temperature and salt tolerance of HPAM is very poor, and its viscosity is almost lost after high salinity and high temperature aging. Hydrophobically associating polymers can significantly improve the temperature and salt tolerance of polymers. The carboxyl-benzene ring-carbon chain nanocellulose provided by the present invention exhibits the most excellent temperature and salt tolerance. After high salinity and high temperature aging, its viscosity retention rate is greater than 75%.

[0052] Therefore, the carboxyl-benzene ring-carbon chain modified nanocellulose prepared in Examples 1-5 is used to prepare a viscosity-increasing agent in tertiary oil recovery, and the viscosity-increasing effect is significant, and it can effectively improve the oil recovery rate. The carboxyl-benzene ring-carbon chain modified nanocellulose prepared in Example 5 with the best viscosity-increasing effect was used for an indoor oil displacement test at a concentration of 0.1%, and was prepared with brine with a sodium chloride concentration of 20,000 mg / L. The selected artificial core has a diameter of 2.5 cm, a length of 10 cm, and a permeability of 300×10 -3 μm 2 or so. The experimental temperature is 90 °C. The original oil saturation is 68.3%. After water flooding until the water cut is greater than 98%, a 0.5 PV brine solution of Example 5 is injected, and then water flooding is continued until the water cut is greater than 98%. The experiment shows that under the conditions of high salinity and high temperature, the carboxyl-benzene ring-carbon chain modified nanocellulose can effectively increase the oil recovery rate by more than 18.8%. The curves of oil recovery rate, pressure and water cut are as Figure 2 shown.

[0053] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A preparation method of carboxyl-benzene ring-carbon chain modified nanocellulose, characterized in that, It includes the following steps: Oxidize nanocellulose to obtain carboxyl nanocellulose; perform benzene ring modification on the carboxyl nanocellulose; perform carbon chain modification on the benzene ring-modified nanocellulose to obtain benzene ring-carbon chain-modified nanocellulose; oxidize the benzene ring-carbon chain-modified nanocellulose to obtain carboxyl-benzene ring-carbon chain group-modified nanocellulose; The method for oxidizing nanocellulose: Uniformly disperse nanocellulose in water, add tetramethylpiperidine oxide, sodium bromide, and sodium hypochlorite solution, adjust the pH value of the solution to 9-11, react for 10-16 h, and obtain carboxyl nanocellulose through washing, dialysis, and centrifugation; The method for performing benzene ring modification on carboxyl nanocellulose includes the following steps: Disperse carboxyl nanocellulose in water, adjust the pH value of the solution to 4-5, add 1-ethyl-(3-dimethylaminopropyl)carbodiimide, and stir evenly; then add N-hydroxysuccinimide and stir evenly; adjust the pH value of the solution to 8-8.5, then add diphenylpropylamine, maintain the pH value of the solution at 8-8.5 and react for 24-36 h, and obtain benzene ring-modified nanocellulose through washing, dialysis, and centrifugation; The method for performing carbon chain modification on the benzene ring-modified nanocellulose includes the following steps: Disperse the benzene ring-modified nanocellulose in water, adjust the pH value of the solution to 4-5, add 1-ethyl-(3-dimethylaminopropyl)carbodiimide, and stir evenly; then add N-hydroxysuccinimide and stir evenly; adjust the pH value of the solution to 8-8.5, then add alkylamine, maintain the pH of the solution at 8-8.5, and react for 24-36 h, and obtain benzene ring-carbon chain-modified nanocellulose through washing, dialysis, and centrifugation.

2. The preparation method according to claim 1, characterized in that, The dosage of each raw material is as follows: 3-5 parts by weight of nanocellulose, 0.1-0.3 parts by weight of tetramethylpiperidine oxide, 6-13 parts by weight of sodium bromide, and 30-60 parts by weight of sodium hypochlorite solution with a mass concentration of 5%-8%.

3. The preparation method according to claim 1, characterized in that, The dosage of each raw material is as follows: 1-5 parts by weight of carboxyl nanocellulose, 0.1-0.6 parts by weight of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 0.07-0.3 parts by weight of N-hydroxysuccinimide, and 0.01-0.03 parts by weight of diphenylpropylamine.

4. The preparation method according to claim 1, characterized in that, The dosage of each raw material is as follows: 1-5 parts by weight of benzene ring-modified nanocellulose, 0.1-0.6 parts by weight of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 0.07-0.3 parts by weight of N-hydroxysuccinimide, and 0.01-0.03 parts by weight of alkylamine.

5. Application of the carboxyl-benzene ring-carbon chain group-modified nanocellulose prepared by the method for preparing carboxyl-benzene ring-carbon chain group-modified nanocellulose as described in claim 1 in the preparation of a viscosifier for oil production.

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