Preparation method of temperature-resistant sodium carboxymethyl cellulose

Abstract

The present application relates to the field of oil drilling aids, and provides a preparation method of temperature-resistant sodium carboxymethyl cellulose, characterized in that a long-chain dichloro compound is introduced to react in the interior of cellulose under alkaline conditions to form a crosslinked structure, thereby improving the temperature resistance of the sodium carboxymethyl cellulose. The crosslinked sodium carboxymethyl cellulose can improve the high-temperature viscosity retention rate of the mud to 50% or more under a 1% addition amount, and can significantly reduce the fluid loss of the mud after high-temperature aging, and has a very broad application prospect.

Description

Technical Field

[0001] This invention relates to a heat-resistant sodium carboxymethyl cellulose, belonging to the field of oilfield chemical technology. Background Technology

[0002] Cellulose, as a natural polymer, is widely used in chemical production due to its advantages of being environmentally friendly, inexpensive, and easy to process. Its chemical structure consists of numerous D-glucopyranoside molecules linked by β-(1,4) glycosidic bonds, forming a linear polymer. The presence of three exposed hydroxyl groups in the glucose molecule provides the chemical mechanism for the deep processing of cellulose. Carboxymethyl cellulose, a water-soluble anionic cellulose ether, is prepared from natural fibers such as cotton through refining, alkalization, and etherification processes. Its sodium salt is widely used in coatings, drilling, and construction as a thickener, binder, water-retaining agent, and dispersant, utilizing its thickening, dispersing, film-forming, adhesive, and protective colloid properties in aqueous solutions.

[0003] Sodium carboxymethyl cellulose (CMC) is commonly used as a filtration loss reducer in oil drilling, improving mud cake quality, controlling filtration loss, and regulating the rheological properties of drilling fluids. However, because the natural cellulose backbone is linked by β-(1,4) glycosidic bonds, these bonds are prone to oxidative breakage at temperatures exceeding 120°C, leading to a decrease in molecular weight and consequently reduced viscosity and filtration loss reduction, thus limiting the application of CMC in drilling. This work aims to improve the temperature resistance of CMC by introducing a dichloro compound as a crosslinking agent during preparation. This enhances the bonds between the cellulose backbone without compromising its water solubility, thereby improving its temperature resistance and potentially expanding its application in drilling.

[0004] CN105566500A discloses a method for preparing granular sodium carboxymethyl cellulose, which prepares granular sodium carboxymethyl cellulose by controlling the spraying and drying process, thus solving the problem of high dust levels during the production and storage of sodium carboxymethyl cellulose.

[0005] CN104448010A discloses a method for preparing fast-dissolving sodium carboxymethyl cellulose (CCMC). This method improves the dispersibility of CCMC in water by adding glyoxal to crosslink CCMC during the synthesis process, overcoming the problem of "fish-eye" formation during dissolution. While this method improves the relevant properties of CCMC, it does not enhance its temperature resistance, and its application remains limited by formation temperature. Therefore, further improving the temperature resistance of CCMC and expanding its application in oilfields is highly beneficial for the green and economical development of oil wells. Summary of the Invention

[0006] This invention utilizes long-chain dichloro compounds as crosslinking agents to form crosslinked structures within cellulose under alkaline catalysis, thereby enhancing the strength of cellulose molecular chains and improving the temperature resistance of sodium carboxymethyl cellulose. This effectively improves the performance of drilling fluids at high temperatures and has high application prospects.

[0007] The present invention discloses a method for preparing heat-resistant sodium carboxymethyl cellulose, characterized in that the preparation process includes the following steps: refined cotton is alkalized in an organic solvent and then cross-linked with a long-chain dichloro compound as a cross-linking agent, and then reacted with an etherifying agent, followed by neutralization, washing, filtration and drying to obtain the final product.

[0008] The heat-resistant sodium carboxymethyl cellulose described in this invention uses refined cotton with a degree of polymerization in the range of 500-2300 during the reaction process.

[0009] The heat-resistant sodium carboxymethyl cellulose of this invention can be produced by using one or more organic solvents selected from ethanol, isopropanol, n-butanol, toluene, and benzene as the organic solvent during the reaction process.

[0010] The heat-resistant sodium carboxymethyl cellulose of the present invention can be reacted with one or more of the following bases: NaOH, KOH, ammonia, and solid base catalyst.

[0011] The heat-resistant sodium carboxymethyl cellulose of this invention uses one or more of the following as crosslinking agents during the reaction process: 1,4-dichlorobutane, 1,6-dichlorohexane, 1,8-dichlorooctane, and 1,10-dichlorodecane.

[0012] The heat-resistant sodium carboxymethyl cellulose of this invention uses a long-chain dichloro compound in a mass ratio of 1:5 to 1:100 with refined cotton.

[0013] The present invention discloses a heat-resistant sodium carboxymethyl cellulose with a crosslinking reaction temperature of 40~80℃.

[0014] The heat-resistant sodium carboxymethyl cellulose of the present invention can be etherified using chloroacetic acid, sodium chloroacetate, or a mixture thereof.

[0015] This invention discloses a method for preparing heat-resistant sodium carboxymethyl cellulose (CMC). By introducing a long-chain dichloro compound under alkaline conditions to react within the cellulose to form a cross-linked structure, the heat resistance of CMC is improved. This cross-linked CMC, at a dosage of 1%, can increase the high-temperature viscosity retention rate of slurry to over 50% and significantly reduce the water loss of slurry after high-temperature aging, demonstrating broad application prospects. Detailed Implementation

[0016] The present invention will now be described in detail with reference to embodiments.

[0017] Example 1

[0018] Weigh 5.0 g of refined cotton with a degree of polymerization of 500-800, 100 g of isopropanol, and 7.5 g of 45% NaOH aqueous solution into a four-necked flask and stir at room temperature for 1 hour. Then, heat to 50°C and add 0.25 g of 1,6-dichlorohexane, continuing the reaction for another hour. Next, add 4.0 g of chloroacetic acid and continue the reaction at 50°C and 75°C for 1 hour each. After the reaction is complete and the product cools, add a small amount of acetic acid to adjust the system to neutral, filter the product, wash it several times with 95% ethanol aqueous solution, filter again, and dry to obtain cross-linked modified sodium carboxymethyl cellulose.

[0019] Example 2

[0020] Weigh 5.0 g of refined cotton with a degree of polymerization of 1000-1600, 100 g of isopropanol, and 7.5 g of 45% NaOH aqueous solution into a four-necked flask and stir at room temperature for 1 hour. Then, heat to 50°C and add 0.25 g of 1,6-dichlorohexane and continue the reaction for 1 hour. Next, add 4.0 g of chloroacetic acid and continue the reaction at 50°C and 75°C for 1 hour each. After the reaction is complete and the product cools, add a small amount of acetic acid to adjust the system to neutral, filter the product, wash it several times with 95% ethanol aqueous solution, filter again, and dry to obtain cross-linked modified sodium carboxymethyl cellulose.

[0021] Example 3

[0022] 5.0 g of refined cotton with a degree of polymerization of 2000-2300, 100 g of isopropanol, and 7.5 g of 45% NaOH aqueous solution were weighed into a four-necked flask and stirred at room temperature for 1 hour. Then, the temperature was raised to 50°C and 0.25 g of 1,6-dichlorohexane was added, and the reaction was continued for another hour. Next, 4.0 g of chloroacetic acid was added, and the reaction was continued at 50°C and 75°C for 1 hour each. After the reaction was completed and the product was cooled, a small amount of acetic acid was added to adjust the system to neutrality. The product was then filtered and washed several times with 95% ethanol aqueous solution, filtered again, and dried to obtain cross-linked modified sodium carboxymethyl cellulose.

[0023] Example 4

[0024] 5.0 g of refined cotton with a degree of polymerization of 500-800, 100 g of toluene, and 7.5 g of 45% NaOH aqueous solution were weighed into a four-necked flask and stirred at room temperature for 1 hour. Then, the temperature was raised to 50°C and 0.25 g of 1,6-dichlorohexane was added, and the reaction was continued for another hour. Next, 4.0 g of chloroacetic acid was added, and the reaction was continued at 50°C and 75°C for 1 hour each. After the reaction was completed and the product was cooled, a small amount of acetic acid was added to adjust the system to neutrality. The product was then filtered and washed several times with 95% ethanol aqueous solution, filtered again, and dried to obtain cross-linked modified sodium carboxymethyl cellulose.

[0025] Example 5

[0026] Weigh 5.0 g of refined cotton with a degree of polymerization of 500-800, 100 g of isopropanol, and 7.5 g of 45% NaOH aqueous solution into a four-necked flask and stir at room temperature for 1 hour. Then, heat to 50°C and add 0.25 g of 1,6-dichlorohexane and continue the reaction for 1 hour. Next, add 5.5 g of sodium chloroacetate and continue the reaction at 50°C and 75°C for 1 hour each. After the reaction is complete and the product cools, add a small amount of acetic acid to adjust the system to neutral, filter the product, wash it several times with 95% ethanol aqueous solution, filter again, and dry to obtain cross-linked modified sodium carboxymethyl cellulose.

[0027] Example 6

[0028] 10.0 g of refined cotton with a degree of polymerization of 500-800, 200 g of isopropanol, and 15.0 g of 45% NaOH aqueous solution were weighed into a four-necked flask and stirred at room temperature for 1 hour. Then, the temperature was raised to 50°C and 0.1 g of 1,6-dichlorohexane was added, and the reaction was continued for another hour. Next, 8.0 g of chloroacetic acid was added, and the reaction was continued at 50°C and 75°C for 1 hour each. After the reaction was completed and the product was cooled, a small amount of acetic acid was added to adjust the system to neutrality. The product was then filtered and washed several times with 95% ethanol aqueous solution, filtered again, and dried to obtain cross-linked modified sodium carboxymethyl cellulose.

[0029] Example 7

[0030] Weigh 5.0 g of refined cotton with a degree of polymerization of 500-800, 100 g of isopropanol, and 7.5 g of 45% NaOH aqueous solution into a four-necked flask and stir at room temperature for 1 hour. Then, heat to 50°C and add 1.0 g of 1,6-dichlorohexane and continue the reaction for 1 hour. Next, add 4.0 g of chloroacetic acid and continue the reaction at 50°C and 75°C for 1 hour each. After the reaction is complete and the product cools, add a small amount of acetic acid to adjust the system to neutral, filter the product, wash it several times with 95% ethanol aqueous solution, filter again, and dry to obtain cross-linked modified sodium carboxymethyl cellulose.

[0031] Example 8

[0032] Weigh 5.0 g of refined cotton with a degree of polymerization of 500-800, 100 g of isopropanol, and 7.5 g of 45% NaOH aqueous solution into a four-necked flask and stir at room temperature for 1 hour. Then, heat to 50°C and add 0.25 g of 1,8-dichlorooctane, continuing the reaction for another hour. Next, add 4.0 g of chloroacetic acid and continue the reaction at 50°C and 75°C for 1 hour each. After the reaction is complete and the product cools, add a small amount of acetic acid to adjust the system to neutral, filter the product, wash it several times with 95% ethanol aqueous solution, filter again, and dry to obtain cross-linked modified sodium carboxymethyl cellulose.

[0033] Example 9

[0034] Weigh 5.0 g of refined cotton with a degree of polymerization of 500-800, 100 g of isopropanol, and 7.5 g of 45% NaOH aqueous solution into a four-necked flask and stir at room temperature for 1 hour. Then, heat to 40°C and add 0.25 g of 1,4-dichlorobutane and continue the reaction for 1 hour. Next, add 4.0 g of chloroacetic acid and continue the reaction at 50°C and 75°C for 1 hour each. After the reaction is complete and the product cools, add a small amount of acetic acid to adjust the system to neutral, filter the product, wash it several times with 95% ethanol aqueous solution, filter again, and dry to obtain cross-linked modified sodium carboxymethyl cellulose.

[0035] Example 10

[0036] Weigh 5.0 g of refined cotton with a degree of polymerization of 500-800, 100 g of isopropanol, and 7.5 g of 45% NaOH aqueous solution into a four-necked flask and stir at room temperature for 1 hour. Then, heat to 80℃ and add 0.5 g of 1,6-dichlorohexane and continue the reaction for 1 hour. Next, add 4.0 g of chloroacetic acid and continue the reaction at 50℃ and 75℃ for 1 hour each. After the reaction is complete and the product cools, add a small amount of acetic acid to adjust the system to neutral, filter the product, wash it several times with 95% ethanol aqueous solution, filter again, and dry to obtain cross-linked modified sodium carboxymethyl cellulose.

[0037] Comparative Example 1

[0038] 5.0 g of refined cotton with a degree of polymerization of 500-800, 100 g of isopropanol, and 7.5 g of 45% NaOH aqueous solution were weighed into a four-necked flask and stirred at room temperature for 1 hour. Then, 4.0 g of chloroacetic acid was added, and the reaction was continued at 50℃ and 75℃ for 1 hour each. After the reaction was completed and the product was cooled, a small amount of acetic acid was added to adjust the system to neutrality. The product was then filtered and washed several times with 95% ethanol aqueous solution, filtered again, and dried to obtain cross-linked modified sodium carboxymethyl cellulose.

[0039] Comparative Example 2

[0040] 5.0 g of refined cotton with a degree of polymerization of 2000-2300, 100 g of isopropanol, and 7.5 g of 45% NaOH aqueous solution were weighed into a four-necked flask and stirred at room temperature for 1 hour. Then, 4.0 g of chloroacetic acid was added, and the reaction was continued at 50℃ and 75℃ for 1 hour each. After the reaction was completed and the product cooled, a small amount of acetic acid was added to adjust the system to neutrality. The product was then filtered and washed several times with 95% ethanol aqueous solution, filtered again, and dried to obtain cross-linked modified sodium carboxymethyl cellulose.

[0041] Prepare a 4% concentration evaluation base slurry according to SY / T5490-2016, and age it at room temperature for at least 24 hours before use. Take 400.0g of the aged base slurry, add 4.0g of the synthesized samples from Examples 1-10 and Comparative Examples 1-2, and stir at 12000r / min for 20min. Then, measure the Φ of the slurry using a rotational viscometer. 600 The value was then determined by hot rolling the mud containing the sample at 150°C for 16 hours, followed by cooling to room temperature and measuring the Φ value using a rotational viscometer. 600 The filtrate loss of the slurry after hot rolling was evaluated using a medium-pressure filtrate loss meter at 690 kPa.

[0042] (Equation 1)

[0043] (Equation 2)

[0044] V1 represents the filtration loss of the mud in a medium-pressure filtration meter over a period of 7.5 min to 30 min.

[0045] Table 1 Performance Evaluation Tests of Clay Stabilizers

[0046] sample Viscosity retention rate / % Filtration loss after hot rolling at 150℃ / mL Example 1 52 14.8 Example 2 43 15.0 Example 3 35 14.4 Example 4 50 14.0 Example 5 51 15.6 Example 6 36 16.8 Example 7 46 18.4 Example 8 45 14.0 Example 9 42 14.8 Example 10 50 15.6 Comparative Example 1 25 28 Comparative Example 2 12 20

[0047] As can be seen from the above examples and comparative examples, the cross-linked sodium carboxymethyl cellulose prepared by the present invention can significantly improve the temperature resistance of the system after dissolving in mud. After hot rolling at 150°C, the viscosity of the system is significantly improved and the filtration loss is reduced.

Claims

1. A method for preparing heat-resistant sodium carboxymethyl cellulose, characterized in that... The process includes the following steps: refined cotton is alkalized in an organic solvent and then crosslinked with a long-chain dichloro compound. After reacting with an etherifying agent, the mixture is neutralized, washed, filtered, and dried to obtain the final product. The degree of polymerization of the refined cotton used in the reaction is in the range of 500-1600. The long-chain dichloro compound used as the crosslinking agent in the reaction is one or a mixture of 1,4-dichlorobutane, 1,6-dichlorohexane, 1,8-dichlorooctane, and 1,10-dichlorodecane. The crosslinking reaction temperature is 40-80℃.

2. The preparation method according to claim 1, characterized in that... The organic solvent used in the reaction is one or a mixture of ethanol, isopropanol, n-butanol, toluene, and benzene.

3. The preparation method according to claim 1, characterized in that... The alkali used in the alkali treatment is one or more of NaOH, KOH, and ammonia water.

4. The preparation method according to claim 1, characterized in that... The mass ratio of long-chain dichloro compounds to refined cotton is 1:5 to 1:

100.

5. The preparation method according to claim 1, characterized in that... The etherifying agent is one of chloroacetic acid, sodium chloroacetate, or a mixture thereof.