Preparation Method and Application of a Temperature-Resistant Modified Carboxymethyl Hydroxypropyl Guar Gum

Abstract

The present invention relates to the technical field of petrochemical engineering, and discloses a preparation method and application of a temperature-resistant modified carboxymethyl hydroxypropyl guar gum. In the present invention, carboxymethyl hydroxypropyl guar gum, sodium hydroxide, 2-chloro-4-cashew phenol quaternary ammonium salt-6-phenyl-s-triazine, etc. are reacted to obtain the temperature-resistant modified carboxymethyl hydroxypropyl guar gum. In the present invention, quaternary ammonium salt cations are introduced into carboxymethyl hydroxypropyl guar gum, which can form electrostatic interactions with the carboxylate anions of itself, thereby improving the intermolecular chain interaction force between guar gums, which can play a role in increasing viscosity and improving the apparent viscosity. At the same time, alkyl long chains are introduced, and a physical cross-linked network is formed through hydrophobic association, further improving the apparent viscosity. The temperature-resistant modified carboxymethyl hydroxypropyl guar gum of the present invention has the advantages of high apparent viscosity and good thickening effect, and excellent temperature resistance and shear resistance, and has good practical applications in fracturing fluid thickeners.

Description

Technical Field

[0001] The present invention relates to the technical field of petrochemical engineering, and specifically to a preparation method and application of a temperature-resistant modified carboxymethyl hydroxypropyl guar gum. Background Art

[0002] Fracturing fluid is a working fluid used for the fracturing and reconstruction of oil and gas reservoirs, which can play roles such as transmitting pressure, transporting proppants, and improving the fluid flow in the reservoir, thereby increasing the oil well production. The thickener is one of the main additives of the fracturing fluid. By increasing the viscosity of the fracturing fluid, the fracturing fluid can better carry proppants into the fractures. Guar gum is a natural polysaccharide polymer, which is inexpensive, easily available, green and pollution-free, and has wide applications in fracturing fluid thickeners. During the development of oil and gas fields, complex geological conditions such as high temperature and high pressure are encountered, which also pose higher requirements for the temperature resistance and other properties of the fracturing fluid thickener. However, the traditional guar gum thickener for fracturing fluid has disadvantages such as poor shear resistance and poor temperature resistance.

[0003] In order to improve the comprehensive performance of the guar gum thickener, it is necessary to modify the guar gum. Reacting guar gum with chloroacetic acid, propylene oxide, 3-chloro-2-hydroxypropyltrimethylammonium chloride, epichlorohydrin, etc. can obtain products with different properties such as carboxymethyl guar gum, hydroxypropyl guar gum, and cationic guar gum. Chinese Patent with Publication No. CN114149513B discloses a carboxymethyl dihydroxypropyl modified guar gum and its preparation method and application. Reacting guar gum with anionic etherifying agents, non-ionic etherifying agents, etc., the carboxymethyl dihydroxypropyl modified guar gum for fracturing fluid thickener obtained has properties such as rapid viscosity increase and low usage amount. However, this patent does not solve the problems of poor temperature resistance, shear resistance, etc. of the guar gum thickener. Summary of the Invention

[0004] The present invention solves the problems of poor temperature resistance, shear resistance, etc. of the guar gum thickener.

[0005] Technical Solution: A preparation method of a temperature-resistant modified carboxymethyl hydroxypropyl guar gum: Add deionized water and 100 parts by weight of carboxymethyl hydroxypropyl guar gum to tetrahydrofuran, add sodium hydroxide to adjust the pH to 7 - 7.5, then add an additional 4 - 18 parts by weight of sodium hydroxide, stir and activate, then add 15 - 60 parts by weight of 2-chloro-4-cashew phenol quaternary ammonium salt-6-phenyl-s-triazine, stir and react, add methanol to dilute the solution, filter, wash with methanol, and dry at 70°C for 6 h to obtain the temperature-resistant modified carboxymethyl hydroxypropyl guar gum.

[0006] Among them, the volume ratio of tetrahydrofuran to deionized water is 100:(10 - 30).

[0007] Among them, when stirring and activating, control the temperature at 40 - 50°C and the time at 30 - 60 min.

[0008] Among them, during the stirring reaction, the temperature is controlled at 80 - 90 °C and the time is 6 - 10 h.

[0009] Among them, the preparation method of 2-chloro-4-cashew phenol quaternary ammonium salt-6-phenyl-s-triazine is as follows: Add cashew phenol quaternary ammonium salt and sodium ethoxide to tetrahydrofuran, stir at 15 - 25 °C for 1 - 2 h, then add 2,4-dichloro-6-phenyl-1,3,5-triazine (CAS registration number is 1700-02-3), where the molar ratio of cashew phenol, sodium ethoxide, and 2,4-dichloro-6-phenyl-1,3,5-triazine is 1:(1 - 1.05):(1 - 1.2), continue to react for 2 - 3 h, rotary evaporate, wash with water and acetone, and recrystallize the product in a mixed solution of tetrahydrofuran and petroleum ether to obtain 2-chloro-4-cashew phenol quaternary ammonium salt-6-phenyl-s-triazine. The reaction formula is:

[0010]

[0011] Among them, the temperature-resistant modified carboxymethyl hydroxypropyl guar gum is applied in the fracturing fluid thickener.

[0012] The beneficial technical effects of the present invention: React the active triazine ring chlorine atom of 2-chloro-4-cashew phenol quaternary ammonium salt-6-phenyl-s-triazine with the hydroxyl group of carboxymethyl hydroxypropyl guar gum to obtain the temperature-resistant modified carboxymethyl hydroxypropyl guar gum, thereby introducing quaternary ammonium salt cations, alkyl long chains, and multiple benzene ring structures into the molecular chain of guar gum.

[0013] The present invention introduces quaternary ammonium salt cations into carboxymethyl hydroxypropyl guar gum, which can form electrostatic interactions with the carboxylate anions of guar gum itself, thereby improving the intermolecular chain interaction force between guar gums, playing a thickening role, and increasing the apparent viscosity.

[0014] The present invention introduces alkyl long chains into carboxymethyl hydroxypropyl guar gum, forms a physical cross-linked network through hydrophobic association, which is beneficial to increasing the apparent viscosity. And when the shearing action is eliminated, the alkyl long chains restore the hydrophobic association and re-form the physical cross-linked network, still showing a high apparent viscosity and excellent shear resistance.

[0015] The present invention introduces multiple heat-resistant benzene ring structures into carboxymethyl hydroxypropyl guar gum, which can improve the heat resistance and structural stability of guar gum, is not easily thermally decomposed. After high-temperature thermal aging, the guar gum still has a very high apparent viscosity and excellent temperature resistance. The prepared temperature-resistant modified carboxymethyl hydroxypropyl guar gum has the advantages of high apparent viscosity and good thickening effect, and excellent temperature resistance and shear resistance, and has good practical applications in the fracturing fluid thickener. Specific embodiments

[0016] To make the technical solutions of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely below. It should be noted that the following embodiments are only used to better understand the technical solutions of the present invention and should not be construed as a limitation of the present invention.

[0017] The following carboxymethyl hydroxypropyl guar gum has the model number GP-101 and is purchased from Shandong Guangpu Biotechnology Co., Ltd.

[0018] According to the method in the journal "China Surfactant Detergent & Cosmetics", in June 2013, Vol. 43, No. 3, "Synthesis and Surface Activity of Cardanol Quaternary Ammonium Salt Surfactants", using cardanol and 2,3-epoxypropyltrimethylammonium chloride as raw materials, cardanol quaternary ammonium salt is prepared, and the structural formula is: , where a is 25 - 31.

[0019] Example 1

[0020] (1) Add 40 mmol of cardanol quaternary ammonium salt and 40 mmol of sodium ethoxide to 150 mL of tetrahydrofuran, stir at 15 °C for 2 h, then add 48 mmol of 2,4-dichloro-6-phenyl-1,3,5-triazine, continue to react for 3 h, rotary evaporate, wash with water and acetone, and recrystallize the product in a mixed solution of tetrahydrofuran and petroleum ether with a volume ratio of 2:1 to obtain 2-chloro-4-cardanol quaternary ammonium salt-6-phenyl-s-triazine.

[0021] (2) Add 15 mL of deionized water and 10 g of carboxymethyl hydroxypropyl guar gum to 150 mL of tetrahydrofuran, adjust the pH to 7 with sodium hydroxide, then add an additional 0.4 g of sodium hydroxide, raise the temperature to 45 °C, stir and activate for 30 min, then add 1.5 g of 2-chloro-4-cardanol quaternary ammonium salt-6-phenyl-s-triazine, raise the temperature to 80 °C, stir and react for 10 h, condense and reflux during the reaction, dilute the solution with methanol, filter and wash with methanol, and dry at 70 °C for 6 h to obtain the temperature-resistant modified carboxymethyl hydroxypropyl guar gum.

[0022] Example 2

[0023] (1) Add 40 mmol of cardanol quaternary ammonium salt and 42 mmol of sodium ethoxide to 200 mL of tetrahydrofuran, stir at 25 °C for 1 h, then add 40 mmol of 2,4-dichloro-6-phenyl-1,3,5-triazine, continue to react for 2 h, rotary evaporate, wash with water and acetone, and recrystallize the product in a mixed solution of tetrahydrofuran and petroleum ether with a volume ratio of 3:1 to obtain 2-chloro-4-cardanol quaternary ammonium salt-6-phenyl-s-triazine.

[0024] (2) Add 20 mL of deionized water and 10 g of carboxymethyl hydroxypropyl guar gum to 150 mL of tetrahydrofuran. Add sodium hydroxide to adjust the pH to 7.5, then add an additional 0.7 g of sodium hydroxide. Heat the mixture to 40 °C and stir for activation for 60 min. Then add 2.5 g of 2-chloro-4-cashew phenol quaternary ammonium salt-6-phenyl-s-triazine, heat the mixture to 85 °C, and stir for reaction for 10 h. During the reaction, use a condenser for reflux. Dilute the solution with methanol, filter, wash with methanol, and dry at 80 °C for 5 h to obtain temperature-resistant modified carboxymethyl hydroxypropyl guar gum.

[0025] Example 3

[0026] (1) Add 20 mL of deionized water and 10 g of carboxymethyl hydroxypropyl guar gum to 150 mL of tetrahydrofuran. Add sodium hydroxide to adjust the pH to 7.5, then add an additional 1.1 g of sodium hydroxide. Heat the mixture to 50 °C and stir for activation for 30 min. Then add 3.6 g of 2-chloro-4-cashew phenol quaternary ammonium salt-6-phenyl-s-triazine (prepared in Example 1), heat the mixture to 90 °C, and stir for reaction for 6 h. During the reaction, use a condenser for reflux. Dilute the solution with methanol, filter, wash with methanol, and dry at 70 °C for 6 h to obtain temperature-resistant modified carboxymethyl hydroxypropyl guar gum.

[0027] Example 4

[0028] (1) Add 20 mL of deionized water and 10 g of carboxymethyl hydroxypropyl guar gum to 150 mL of tetrahydrofuran. Add sodium hydroxide to adjust the pH to 7, then add an additional 1.4 g of sodium hydroxide. Heat the mixture to 40 °C and stir for activation for 60 min. Then add 4.8 g of 2-chloro-4-cashew phenol quaternary ammonium salt-6-phenyl-s-triazine (prepared in Example 1), heat the mixture to 85 °C, and stir for reaction for 10 h. During the reaction, use a condenser for reflux. Dilute the solution with methanol, filter, wash with methanol, and dry at 70 °C for 6 h to obtain temperature-resistant modified carboxymethyl hydroxypropyl guar gum.

[0029] Example 5

[0030] (1) Add 30 mL of deionized water and 10 g of carboxymethyl hydroxypropyl guar gum to 150 mL of tetrahydrofuran. Add sodium hydroxide to adjust the pH to 7, then add an additional 1.8 g of sodium hydroxide. Heat the mixture to 50 °C and stir for activation for 40 min. Then add 6 g of 2-chloro-4-cashew phenol quaternary ammonium salt-6-phenyl-s-triazine (prepared in Example 1), heat the mixture to 90 °C, and stir for reaction for 8 h. During the reaction, use a condenser for reflux. Dilute the solution with methanol, filter, wash with methanol, and dry at 80 °C for 5 h to obtain temperature-resistant modified carboxymethyl hydroxypropyl guar gum.

[0031] Comparative Example 1

[0032] Use carboxymethyl hydroxypropyl guar gum as a fracturing fluid thickener.

[0033] Comparative Example 2

[0034] (1) Add 10 g of carboxymethyl hydroxypropyl guar gum to 25 mL of ethanol, stir and heat to 70 °C, add 1.5 g of 3-chloro-2-hydroxypropyl trimethyl ammonium chloride, stir and react for 4 h. During the reaction, continuously add an ethanol solvent of sodium hydroxide with a mass concentration of 3 g / L to control the pH of the reaction solution to be maintained at 11. After filtration, wash with ethanol and dry at 70 °C for 6 h to obtain cationic modified carboxymethyl hydroxypropyl guar gum.

[0035] Comparative Example 3

[0036] (1) According to the method of the master's thesis of Shenzhen University, "Design, Synthesis of Antibacterial Finishing Agents and Their Applications in Textiles", using N,N-dimethylethanolamine, 1-bromohexadecane, and cyanuric chloride as raw materials, prepare a triazine-based quaternary ammonium salt compound with the structural formula .

[0037] (2) Add 15 mL of deionized water and 10 g of carboxymethyl hydroxypropyl guar gum to 150 mL of tetrahydrofuran, add sodium hydroxide to adjust the pH to 7, then add an additional 0.4 g of sodium hydroxide, heat to 45 °C, stir and activate for 30 min, then add 1.5 g of the triazine-based quaternary ammonium salt compound, heat to 80 °C, stir and react for 10 h. During the reaction, carry out condensation reflux. Add methanol to dilute the solution, filter and wash with methanol, and dry at 70 °C for 6 h to obtain modified carboxymethyl hydroxypropyl guar gum.

[0038] Comparative Example 4

[0039] (1) Add 40 mmol of cardanol and 40 mmol of sodium ethoxide to 150 mL of tetrahydrofuran, stir at 15 °C for 2 h, then add 48 mmol of 2,4-dichloro-6-phenyl-1,3,5-triazine, continue to react for 3 h, perform rotary evaporation, wash with water and acetone, and recrystallize the product in a mixed solution of tetrahydrofuran and petroleum ether with a volume ratio of 2:1 to obtain 2-chloro-4-cardanol-6-phenyl-s-triazine. The structural formula is , where a is 25 - 31.

[0040] (2) Add 15 mL of deionized water and 10 g of carboxymethyl hydroxypropyl guar gum to 150 mL of tetrahydrofuran, add sodium hydroxide to adjust the pH to 7, then add an additional 0.4 g of sodium hydroxide, heat to 45 °C, stir and activate for 30 min, then add 1.5 g of 2-chloro-4-cardanol-6-phenyl-s-triazine, heat to 80 °C, stir and react for 10 h. During the reaction, carry out condensation reflux. Add methanol to dilute the solution, filter and wash with methanol, and dry at 70 °C for 6 h to obtain modified carboxymethyl hydroxypropyl guar gum.

[0041] Add modified carboxymethyl hydroxypropyl guar gum to deionized water to prepare a solution with a mass concentration of 2 - 8 g / L, shear for 2 min, and measure the apparent viscosity at room temperature using a viscometer.

[0042] Table 1 Apparent Viscosity Test of Guar Gum

[0043]

[0044] Add modified carboxymethyl hydroxypropyl guar gum to deionized water to prepare a solution with a mass concentration of 5 g / L, and shear at a rotational speed of 170 s -1 for 30 min, and measure the apparent viscosity at room temperature using a viscometer.

[0045] Table 2 Shear Resistance Performance Test of Guar Gum

[0046]

[0047] Place guar gum in an oven at 150 °C for thermal aging for 72 h, take it out and cool it to room temperature, add it to deionized water to prepare a solution with a mass concentration of 5 g / L, shear for 2 min, and measure the apparent viscosity at room temperature using a viscometer.

[0048] Table 3 Temperature Resistance Performance Test of Guar Gum

[0049]

[0050] As can be seen from Tables 1 - 3, in Comparative Example 1, carboxymethyl hydroxypropyl guar gum is used as a fracturing fluid thickener, its apparent viscosity is relatively low, and after high-speed shearing for 30 min, the decrease in apparent viscosity is relatively large, the retention rate is low, the shear resistance performance is poor, and after high-temperature thermal aging, the decrease in apparent viscosity is also relatively large, and the temperature resistance performance is not good.

[0051] In Example 1, the active triazine ring chlorine atom of 2-chloro-4-cashew phenol quaternary ammonium salt-6-phenyl-s-triazine reacts with the hydroxyl group of carboxymethyl hydroxypropyl guar gum to obtain a temperature-resistant modified carboxymethyl hydroxypropyl guar gum. Quaternary ammonium salt cations, alkyl long chains and multiple benzene ring structures are introduced into the molecular chain of guar gum. The quaternary ammonium salt cations form electrostatic interactions with the carboxylate anions in guar gum, improving the intermolecular chain interaction force between guar gums, which can play a thickening role and increase the apparent viscosity. At the same time, there is a hydrophobic association effect between the alkyl long chains, forming a physical cross-linked network, further increasing the apparent viscosity. And when the shearing effect is eliminated, the alkyl long chains of guar gum restore the hydrophobic association effect and re-form a physical cross-linked network, still showing a relatively high apparent viscosity and excellent shear resistance performance. And guar gum contains multiple heat-resistant benzene ring structures, which can improve the heat resistance and structural stability of guar gum, is not easily thermally decomposed, and after high-temperature thermal aging, guar gum still has a very high apparent viscosity and excellent temperature resistance performance.

[0052] In Comparative Example 2, the chlorine atom of 3-chloro-2-hydroxypropyltrimethylammonium chloride reacts with the hydroxyl group of carboxymethylhydroxypropyl guar gum to introduce a quaternary ammonium cation into the guar gum molecular chain, forming an electrostatic interaction with the carboxylate anion of guar gum, enhancing the intermolecular chain interaction between guar gums, which can play a role in increasing viscosity and improving the apparent viscosity. However, it does not contain an alkyl long chain and cannot form a hydrophobic association, and also does not contain a heat-resistant benzene ring structure, resulting in poor shear resistance and temperature resistance of the guar gum.

[0053] In Comparative Example 3, the active triazine ring chlorine atom of the triazine quaternary ammonium salt compound reacts with the hydroxyl group of carboxymethylhydroxypropyl guar gum. Since the guar gum does not contain a heat-resistant benzene ring structure, after high-temperature thermal aging, the surface viscosity decreases significantly, and the temperature resistance is poor.

[0054] In Comparative Example 4, the active triazine ring chlorine atom of 2-chloro-4-cashew phenol-6-phenyl-s-triazine reacts with the hydroxyl group of carboxymethylhydroxypropyl guar gum. It does not contain a quaternary ammonium cation and cannot form an electrostatic interaction with the carboxylate anion, making it difficult to enhance the intermolecular chain interaction between guar gums, resulting in poor thickening effect and low apparent viscosity.

Claims

1. A preparation method of a temperature-resistant modified carboxymethyl hydroxypropyl guar gum, characterized in that, The preparation method includes: adding deionized water and 100 parts by weight of carboxymethyl hydroxypropyl guar gum to tetrahydrofuran, adding sodium hydroxide to adjust the pH, and then adding an additional 4 - 18 parts by weight of sodium hydroxide. After stirring and activation, 15 - 60 parts by weight of 2 - chloro - 4 - cashew phenol quaternary ammonium salt - 6 - phenyl - 1,3,5 - triazine is added. After stirring and reacting, methanol is added to the solution for dilution, followed by filtration, washing, and drying to obtain the temperature - resistant modified carboxymethyl hydroxypropyl guar gum; The reaction is to react the active triazine ring chlorine atom of 2 - chloro - 4 - cashew phenol quaternary ammonium salt - 6 - phenyl - 1,3,5 - triazine with the hydroxyl group of carboxymethyl hydroxypropyl guar gum; The structural formula of the 2 - chloro - 4 - cashew phenol quaternary ammonium salt - 6 - phenyl - 1,3,5 - triazine is as follows: , where a is any integer from 25 to 31.

2. The preparation method of the temperature-resistant modified carboxymethyl hydroxypropyl guar gum according to claim 1, wherein, The volume ratio of the tetrahydrofuran to the deionized water is 100:(10 - 30).

3. The preparation method of the temperature-resistant modified carboxymethyl hydroxypropyl guar gum according to claim 1, wherein Adding sodium hydroxide to adjust the pH to 7 - 7.

5.

4. The preparation method of the temperature-resistant modified carboxymethyl hydroxypropyl guar gum according to claim 1, characterized in that, When stirring and activating, the temperature is controlled at 40 - 50 °C and the time is 30 - 60 min.

5. The preparation method of the temperature-resistant modified carboxymethyl hydroxypropyl guar gum according to claim 1, characterized in that, When stirring and reacting, the temperature is controlled at 80 - 90 °C and the time is 6 - 10 h.

6. The preparation method of the temperature-resistant modified carboxymethyl hydroxypropyl guar gum according to claim 1, characterized in that, The preparation method of the 2 - chloro - 4 - cashew phenol quaternary ammonium salt - 6 - phenyl - 1,3,5 - triazine is: adding cashew phenol quaternary ammonium salt and sodium ethoxide to tetrahydrofuran, stirring at 15 - 25 °C for 1 - 2 h, then adding 2,4 - dichloro - 6 - phenyl - 1,3,5 - triazine, continuing the reaction for 2 - 3 h, rotary evaporation, washing with water and acetone, and recrystallizing the product in a mixed solution of tetrahydrofuran and petroleum ether to obtain 2 - chloro - 4 - cashew phenol quaternary ammonium salt - 6 - phenyl - 1,3,5 - triazine.

7. The preparation method of the temperature-resistant modified carboxymethyl hydroxypropyl guar gum according to claim 6, characterized in that, The molar ratio of the cashew phenol, sodium ethoxide, and 2,4 - dichloro - 6 - phenyl - 1,3,5 - triazine is 1:(1 - 1.05):(1 - 1.2).

8. Application of the temperature - resistant modified carboxymethyl hydroxypropyl guar gum obtained by the preparation method according to any one of claims 1 - 7 as a thickening agent for fracturing fluid.

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