A natural biomass-modified thermosensitive clay stabilizer and its preparation method

Abstract

This invention relates to a natural biomass-modified temperature-sensitive clay stabilizer with the following structural formula: where X = H or , and the degree of polymerization n is 300–3000. This clay stabilizer gradually releases multiple small-molecule quaternary ammonium salts as the formation temperature gradually increases, providing long-lasting anti-swelling effects. It also exhibits strong temperature resistance, good biodegradability, and is environmentally friendly. At a concentration of 0.3 wt%, the anti-swelling rate at room temperature can reach over 80%. After high-temperature aging, the anti-swelling performance is effectively improved, reaching over 90% at high temperatures. This product can be used for water injection anti-swelling and fracturing anti-swelling applications in oilfields.

Description

Technical Field

[0001] This invention relates to a natural biomass-modified thermosensitive clay stabilizer and its preparation method, belonging to the field of oilfield chemical additives. Background Technology

[0002] During water injection, acidizing, or fracturing operations in oil and gas fields, clay minerals in the reservoir are prone to hydration, expansion, dispersion, and migration upon contact with injected water. This can cause blockage of formation pores and reduced permeability, severely impacting the effectiveness of water injection or fracturing operations. Therefore, adding clay stabilizers to the wellbore working fluid system is crucial for improving oil recovery.

[0003] Clay stabilizers mainly include inorganic salts, inorganic polymers, cationic surfactants, and organic cationic polymers. While inorganic salt clay stabilizers are simple to prepare and low in cost, they suffer from poor stability and long-term effectiveness, cannot form multi-point adsorption sites, and have poor erosion resistance. Inorganic cationic polymers stabilize clays for a longer period than inorganic salts, but have poor acid resistance and cannot be used in sandstone formations with high carbonate content. Cationic surfactants can adsorb onto the clay surface through electrostatic interactions to inhibit clay hydration and dispersion, but they tend to increase reservoir oleophilicity and reduce oil and gas phase permeability. Organic cationic polymers have the advantages of low dosage, high efficiency, and strong adsorption capacity, but some polymers are prone to decomposition and inactivation at high temperatures, have poor long-term effectiveness, and have large molecular weights that are difficult to degrade, potentially leading to reservoir damage and soil pollution with long-term use.

[0004] Patent CN117777981B discloses a method for preparing a clay stabilizer. This invention grafts cationic quaternary ammonium salts onto cellulose nanofibers and then combines them with inorganic clay stabilizers to improve the anti-swelling performance of the clay stabilizers and the recovery performance of reservoir permeability. However, its preparation steps are relatively complex and its long-term effect is insufficient. Patent CN118894987A discloses a method for preparing and applying a water-resistant anti-swelling agent. This method uses terephthalaldehyde, N-methylethylenediamine, and glycidyl dibromoethane as raw materials to prepare an anti-swelling agent containing a large amount of quaternary ammonium salts and hydroxyl functional groups. This anti-swelling agent has excellent anti-swelling properties, temperature resistance, and water resistance. However, the raw materials used are highly toxic, the reaction process is complex and not environmentally friendly, and the product's anti-swelling effect is insufficient. Summary of the Invention

[0005] The purpose of this invention is to provide a natural biomass-modified thermosensitive clay stabilizer and its preparation method. This clay stabilizer can gradually release multiple small-molecule quaternary ammonium salts as the formation temperature gradually increases, thereby playing a long-term anti-swelling role. It is also resistant to high temperature, has good biodegradability, and is environmentally friendly.

[0006] The natural biomass-modified thermosensitive clay stabilizer of this invention has the following structural formula:

[0007]

[0008] Where X = H or, the degree of polymerization n is 300 to 3000.

[0009] The preparation method of the natural biomass modified thermosensitive clay stabilizer of the present invention includes the following steps:

[0010] 1) Add a certain amount of solvent to the raw material chitosan and stir until it is completely dissolved. After heating in a water bath, add 2,3-epoxypropyltrimethylammonium chloride. After the reaction is completed, after precipitation, washing, filtration and drying, the chitosan quaternized product is obtained and named CTS-A.

[0011] 2) The chitosan quaternized product CTS-A synthesized in step 1) was stirred with an excess sodium hydroxide solution at room temperature. After the reaction was completed, the product was distilled to remove water. A solution of 2-chloroethyl-trimethylammonium chloride in isopropanol was slowly added dropwise to the dehydrated product (named CTS-E). The product was heated in a water bath. After the reaction was completed, the pH of the product was adjusted to neutral. The product was then filtered, washed, vacuum filtered, and dried to obtain the desired thermosensitive clay stabilizer.

[0012] The solvent in step 1) is one of propanol, isopropanol, n-butanol or isobutanol.

[0013] In step 1), the molar ratio of chitosan to 2,3-epoxypropyltrimethylammonium chloride is 1:(1-3).

[0014] The drying conditions in step 1) are drying at 105℃ for 4 to 8 hours.

[0015] In step 1), the water bath heating temperature is 60–100°C, and the reaction time is 6–10 h.

[0016] In step 2), the mass fraction of the sodium hydroxide solution is 40-60%.

[0017] In step 2), the mass ratio of chitosan quaternary ammonium salt CTS-A to sodium hydroxide solution is 1:(10-20), and the reaction time at room temperature is 1-3 hours.

[0018] In step 2), the mass fraction of the 2-chloroethyl-trimethylammonium chloride solution is 30-70%, and the mass ratio of the dehydrated product CTS-E to the 2-chloroethyl-trimethylammonium chloride solution is 1:(10-30).

[0019] In step 2), the water bath heating temperature is 60-80℃, and the reaction time is 8-12h.

[0020] In step 2), the pH of the reaction product is adjusted to neutral using hydrochloric acid, and the drying conditions are drying at 105°C for 4–8 hours.

[0021] The synthetic reaction equation based on the preparation method of the natural biomass-modified thermosensitive clay stabilizer of this invention is as follows:

[0022]

[0023] Where X = H or The degree of polymerization n is 300 to 3000.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The clay stabilizer provided by the present invention is modified with natural biomass chitosan as raw material. This raw material is widely available, non-toxic, and has good biodegradability and biocompatibility, and is environmentally friendly.

[0026] (2) The present invention prepares a thermosensitive clay stabilizer by quaternizing and etherifying chitosan. The resulting clay stabilizer has multiple ether bonds in its molecular structure. After entering the formation, as the formation temperature rises, the ether bonds in the molecule break, releasing multiple positively charged small quaternary ammonium salts that are adsorbed on the clay surface, thereby reducing the electronegativity of the clay particles and effectively inhibiting the hydration and dispersion of clay minerals.

[0027] (3) The clay stabilizer provided by the present invention has excellent anti-swelling performance and strong temperature resistance. The anti-swelling rate of the clay stabilizer at room temperature can reach more than 80% at a concentration of 0.3wt%. After high temperature aging, the anti-swelling performance is improved and the anti-swelling rate can reach more than 90%. Detailed Implementation

[0028] The present invention will now be described in detail with reference to embodiments and comparative examples.

[0029] Example 1

[0030] 10.0 g of chitosan was weighed into a three-necked flask, and 100 mL of isopropanol was added and stirred to dissolve. 9.42 g of 2,3-epoxypropyltrimethylammonium chloride was added under a 60°C water bath and the mixture was reacted for 6 h. After the reaction was complete, acetone was added and the product was precipitated in an ice-water bath. The precipitate was then washed with ethanol solution, filtered, and dried at 105°C for 6 h to obtain the chitosan quaternary ammonium salt, named CTS-A.

[0031] Take 5g of CTS-A and add 50g of 50% sodium hydroxide solution. Stir the mixture at room temperature for 2 hours. Then, distill to remove water to obtain the product, named CTS-E. Take CTS-E in a flask and slowly add a 70% isopropanol solution of 2-chloroethyl-trimethylammonium chloride at a mass ratio of 1:5 using a separatory funnel. Heat in a water bath at 80℃ for 8 hours. After the reaction is complete, adjust the pH to neutral with hydrochloric acid. After filtration, wash three times with dichloromethane, then filter under vacuum and dry at 105℃ for 6 hours to obtain the desired thermosensitive clay stabilizer.

[0032] 0.6g of the synthesized sample was weighed and dissolved in 200mL of deionized water to prepare a 0.3wt% solution. Its anti-swelling rate at room temperature and at different temperatures was tested. The results are shown in Table 1 and Table 2.

[0033] Example 2

[0034] 10.0 g of chitosan was weighed into a three-necked flask, and 100 mL of isopropanol was added and stirred to dissolve. 9.42 g of 2,3-epoxypropyltrimethylammonium chloride was added under a 70°C water bath and the reaction was carried out for 8 h. After the reaction was complete, acetone was added and the product was precipitated in an ice-water bath. The precipitate was then washed with ethanol solution, filtered, and dried at 105°C for 8 h to obtain chitosan quaternary ammonium salt, named CTS-A.

[0035] Take 5g of CTS-A and add 60g of 40% sodium hydroxide solution. Stir and react at room temperature for 2 hours. Then, distill to remove water and name the product CTS-E. Take CTS-E in a flask and slowly add a 60% isopropanol solution of 2-chloroethyl-trimethylammonium chloride at a mass ratio of 1:8 using a separatory funnel. Heat in a water bath at 80℃ for 8 hours. After the reaction is complete, adjust the pH to neutral with hydrochloric acid. After filtration, wash three times with dichloromethane, then filter under vacuum and dry at 105℃ for 8 hours to obtain the desired thermosensitive clay stabilizer.

[0036] 0.6g of the synthesized sample was weighed and dissolved in 200mL of deionized water to prepare a 0.3wt% solution. Its anti-swelling rate at room temperature and at different temperatures was tested. The results are shown in Table 1 and Table 2.

[0037] Example 3

[0038] 10.0 g of chitosan was weighed into a three-necked flask, and 100 mL of propanol was added and stirred to dissolve. 14.13 g of 2,3-epoxypropyltrimethylammonium chloride was added under 80 °C water bath heating conditions, and the reaction was carried out for 8 h. After the reaction was complete, acetone was added to precipitate the product in an ice-water bath, and the product was washed with ethanol solution. After filtration and drying at 105 °C for 6 h, chitosan quaternary ammonium salt was obtained, named CTS-A.

[0039] Take 5g of CTS-A and add 70g of 50% sodium hydroxide solution. Stir and react at room temperature for 2 hours. Then, distill to remove water and name the product CTS-E. Take CTS-E in a flask and slowly add a 50% isopropanol solution of 2-chloroethyl-trimethylammonium chloride at a mass ratio of 1:10 using a separatory funnel. Heat in a water bath at 70℃ for 10 hours. After the reaction is complete, adjust the pH to neutral with hydrochloric acid. After filtration, wash three times with dichloromethane, then filter under vacuum and dry at 105℃ for 6 hours to obtain the desired thermosensitive clay stabilizer.

[0040] 0.6g of the synthesized sample was weighed and dissolved in 200mL of deionized water to prepare a 0.3wt% solution. Its anti-swelling rate at room temperature and at different temperatures was tested. The results are shown in Table 1 and Table 2.

[0041] Example 4

[0042] 10.0 g of chitosan was weighed into a three-necked flask, and 100 mL of propanol was added and stirred to dissolve. 14.13 g of 2,3-epoxypropyltrimethylammonium chloride was added under a 90°C water bath and the reaction was carried out for 10 h. After the reaction was complete, acetone was added and the product was precipitated in an ice-water bath. The precipitate was then washed with ethanol solution, filtered, and dried at 105°C for 4 h to obtain chitosan quaternary ammonium salt, named CTS-A.

[0043] Take 5g of CTS-A and add 80g of 60% sodium hydroxide solution. Stir the reaction at room temperature for 3 hours. Then, distill to remove water and name the product CTS-E. Take CTS-E in a flask and slowly add a 40% isopropanol solution of 2-chloroethyl-trimethylammonium chloride at a mass ratio of 1:15 using a separatory funnel. Heat in a water bath at 60℃ for 8 hours. After the reaction is complete, adjust the pH to neutral with hydrochloric acid. After filtration, wash three times with dichloromethane, then filter under vacuum and dry at 105℃ for 4 hours to obtain the desired thermosensitive clay stabilizer.

[0044] 0.6 g of the synthesized sample was weighed and dissolved in 200 mL of deionized water to prepare a 0.3 wt% solution, and its anti-swelling rate at room temperature was tested. The results are shown in Table 1.

[0045] Example 5

[0046] 10.0 g of chitosan was weighed into a three-necked flask, and 100 mL of n-butanol was added and stirred to dissolve. Then, 16.96 g of 2,3-epoxypropyltrimethylammonium chloride was added under a water bath heating condition at 100 °C and the reaction was carried out for 8 h. After the reaction was completed, acetone was added and the product was precipitated in an ice-water bath. The precipitate was then washed with ethanol solution, filtered, and dried at 105 °C for 5 h to obtain the chitosan quaternary ammonium salt, named CTS-A.

[0047] Take 5g of CTS-A and add 100g of 40% sodium hydroxide solution. Stir the mixture at room temperature for 3 hours. Then, distill to remove water to obtain the product, which is named CTS-E. Take CTS-E in a flask and slowly add a 35% isopropanol solution of 2-chloroethyl-trimethylammonium chloride at a mass ratio of 1:20 using a separatory funnel. Heat in a water bath at 75°C for 9 hours. After the reaction is complete, adjust the pH to neutral with hydrochloric acid. After filtration, wash three times with dichloromethane, then filter under vacuum and dry at 105°C for 5 hours to obtain the desired thermosensitive clay stabilizer.

[0048] Weigh 0.6g of the synthesized sample and dissolve it in 200mL of deionized water to prepare a 0.3wt% solution. The results are shown in Table 1.

[0049] Example 6

[0050] 10.0 g of chitosan was weighed into a three-necked flask, and 100 mL of n-butanol was added and stirred to dissolve. Then, 16.96 g of 2,3-epoxypropyltrimethylammonium chloride was added under a water bath heating condition at 100 °C and the reaction was carried out for 9 h. After the reaction was completed, acetone was added and the product was precipitated in an ice-water bath. The precipitate was then washed with ethanol solution, filtered, and dried at 105 °C for 5 h to obtain the chitosan quaternary ammonium salt, named CTS-A.

[0051] Take 5g of CTS-A and add 75g of 60% sodium hydroxide solution. Stir the mixture at room temperature for 1.5h, then distill to remove water to obtain CTS-E. Take a certain amount of CTS-E in a flask and slowly add a 45% isopropanol solution of 2-chloroethyl-trimethylammonium chloride at a mass ratio of 1:18 using a separatory funnel. Heat in a water bath at 80℃ for 12h. After the reaction is complete, adjust the pH to neutral with hydrochloric acid. After filtration, wash three times with dichloromethane, then filter under vacuum and dry at 105℃ for 5h to obtain the desired thermosensitive clay stabilizer.

[0052] 0.6 g of the synthesized sample was weighed and dissolved in 200 mL of deionized water to prepare a 0.3 wt% solution, and its anti-swelling rate at room temperature was tested. The results are shown in Table 1.

[0053] Example 7

[0054] 10.0 g of chitosan was weighed into a three-necked flask, and 100 mL of isobutanol was added and stirred to dissolve. 18.84 g of 2,3-epoxypropyltrimethylammonium chloride was added under a 90°C water bath and the reaction was carried out for 8 h. After the reaction was complete, acetone was added and the product was precipitated in an ice-water bath. The precipitate was then washed with ethanol solution, filtered, and dried at 105°C for 6 h to obtain the chitosan quaternary ammonium salt, named CTS-A.

[0055] Take 5g of CTS-A and add 80g of 50% sodium hydroxide solution. Stir the mixture at room temperature for 3 hours. Then, distill to remove water and name the product CTS-E. Take CTS-E in a flask and slowly add a 55% isopropanol solution of 2-chloroethyl-trimethylammonium chloride at a mass ratio of 1:16 using a separatory funnel. Heat in a water bath at 70℃ for 10 hours. After the reaction is complete, adjust the pH to neutral with hydrochloric acid. After filtration, wash three times with dichloromethane, then filter under vacuum and dry at 105℃ for 6 hours to obtain the desired thermosensitive clay stabilizer.

[0056] 0.6 g of the synthesized sample was weighed and dissolved in 200 mL of deionized water to prepare a 0.3 wt% solution, and its anti-swelling rate at room temperature was tested. The results are shown in Table 1.

[0057] Example 8

[0058] 10.0 g of chitosan was weighed into a three-necked flask, and 100 mL of isobutanol was added and stirred to dissolve. 23.55 g of 2,3-epoxypropyltrimethylammonium chloride was added under 80°C water bath heating and reacted for 8 h. After the reaction was complete, acetone was added and the product was precipitated in an ice-water bath. The precipitate was then washed with ethanol solution, filtered, and dried at 105°C for 4 h to obtain the chitosan quaternary ammonium salt, named CTS-A.

[0059] Take 5g of CTS-A and add 60g of 60% sodium hydroxide solution. Stir and react at room temperature for 1 hour. Then, distill to remove water and name the product CTS-E. Take CTS-E in a flask and slowly add a 65% isopropanol solution of 2-chloroethyl-trimethylammonium chloride at a mass ratio of 1:14 using a separatory funnel. Heat in a water bath at 65°C for 11 hours. After the reaction is complete, adjust the pH to neutral with hydrochloric acid. After filtration, wash three times with dichloromethane, then filter under vacuum and dry at 105°C for 4 hours to obtain the desired thermosensitive clay stabilizer.

[0060] 0.6 g of the synthesized sample was weighed and dissolved in 200 mL of deionized water to prepare a 0.3 wt% solution, and its anti-swelling rate at room temperature was tested. The results are shown in Table 1.

[0061] Example 9

[0062] 10.0 g of chitosan was weighed into a three-necked flask, and 100 mL of isopropanol was added and stirred to dissolve. 23.55 g of 2,3-epoxypropyltrimethylammonium chloride was added under a 75°C water bath and the reaction was carried out for 7 h. After the reaction was complete, acetone was added and the product was precipitated in an ice-water bath. The precipitate was then washed with ethanol solution, filtered, and dried at 105°C for 7 h to obtain the chitosan quaternary ammonium salt, named CTS-A.

[0063] Take 5g of CTS-A and add 90g of 40% sodium hydroxide solution. Stir the reaction at room temperature for 3 hours. Then, distill to remove water and name the product CTS-E. Take CTS-E in a flask and slowly add a 70% isopropanol solution of 2-chloroethyl-trimethylammonium chloride at a mass ratio of 1:12 using a separatory funnel. Heat in a water bath at 60℃ for 12 hours. After the reaction is complete, adjust the pH to neutral with hydrochloric acid. After filtration, wash three times with dichloromethane, then filter under vacuum and dry at 105℃ for 7 hours to obtain the desired thermosensitive clay stabilizer.

[0064] 0.6 g of the synthesized sample was weighed and dissolved in 200 mL of deionized water to prepare a 0.3 wt% solution, and its anti-swelling rate at room temperature was tested. The results are shown in Table 1.

[0065] Comparative Example 1

[0066] 10.0 g of chitosan was weighed into a three-necked flask, and 100 mL of propanol was added and stirred to dissolve. 9.42 g of 2,3-epoxypropyltrimethylammonium chloride was added under a 50°C water bath and the mixture was reacted for 6 h. After the reaction was complete, acetone was added and the product was precipitated in an ice-water bath. The precipitate was then washed with ethanol solution, filtered, and dried at 105°C for 6 h to obtain the chitosan quaternary ammonium salt, named CTS-A.

[0067] Take 5g of CTS-A and add 40g of 30% sodium hydroxide solution. Stir and react at room temperature for 2 hours. Then, distill to remove water to obtain the product, which is named CTS-E. Take a certain amount of CTS-E in a flask and slowly add a 70% isopropanol solution of 2-chloroethyl-trimethylammonium chloride at a mass ratio of 1:5 using a separatory funnel. Heat in a water bath at 80℃ for 6 hours. After the reaction is complete, adjust the pH to neutral with hydrochloric acid. After filtration, wash three times with dichloromethane, then filter under vacuum and dry at 105℃ for 6 hours to obtain the desired thermosensitive clay stabilizer.

[0068] 0.6 g of the synthesized sample was weighed and dissolved in 200 mL of deionized water to prepare a 0.3 wt% solution, and its anti-swelling rate at room temperature was tested. The results are shown in Table 1.

[0069] Comparative Example 2

[0070] 10.0 g of chitosan was weighed into a three-necked flask, and 100 mL of isopropanol was added and stirred to dissolve. 16.96 g of 2,3-epoxypropyltrimethylammonium chloride was added under a water bath heating condition at 100 °C and the reaction was carried out for 6 h. After the reaction was complete, acetone was added and the product was precipitated in an ice-water bath. The precipitate was then washed with ethanol solution, filtered, and dried at 105 °C for 8 h to obtain the chitosan quaternary ammonium salt, named CTS-A.

[0071] Take 5g of CTS-A and add 75g of 60% sodium hydroxide solution. Stir and react at room temperature for 2 hours. Then, distill to remove water to obtain the product, named CTS-E. Take a certain amount of CTS-E in a flask and slowly add a 50% isopropanol solution of 2-chloroethyl-trimethylammonium chloride at a mass ratio of 1:5 using a separatory funnel. Heat in a water bath at 100℃ for 8 hours. After the reaction is complete, adjust the pH to neutral with hydrochloric acid. After filtration, wash three times with dichloromethane, then filter and dry at 105℃ for 8 hours to obtain the desired thermosensitive clay stabilizer. Weigh 0.6g of the synthesized sample and dissolve it in 200mL of deionized water to prepare a 0.3wt% solution. Test its room temperature anti-swelling rate. The results are shown in Table 1.

[0072] Room temperature anti-swelling rate test method:

[0073] The anti-swelling rate test was conducted according to the "SY / T5971-2016 Performance Evaluation Method of Clay Stabilizer for Fracturing, Acidizing and Water Injection in Oil and Gas Fields". The steps are as follows: Weigh 0.50g of sodium bentonite, add it to a 10mL centrifuge tube, add deionized water to the 10mL mark, shake thoroughly, let stand at room temperature for 2 hours, put it into a centrifuge, and centrifuge at 1500r / min for 15 minutes. Read the volume V2 of sodium bentonite in water. Use the same steps but replace water with a 0.3% clay stabilizer aqueous solution to measure the volume V1 of the soil after centrifugation. Use kerosene instead of water to measure the volume V0 of the soil. The anti-swelling rate calculation formula is as follows:

[0074]

[0075] Where: η—anti-swelling rate, %; V0—volume of sodium bentonite in kerosene, mL; V1—volume of sodium bentonite in clay stabilizer, mL; V2—volume of sodium bentonite in water, mL.

[0076] High-temperature anti-swelling rate test method:

[0077] High-temperature swelling resistance test was conducted according to the "Q / SH125-2017 Technical Requirements for Clay Stabilizers". 3.00g of bentonite powder, accurate to 0.01g, was weighed and placed into a high-temperature, high-pressure closed reactor. 60mL of a 0.3% clay stabilizer solution was added, and the mixture was thoroughly shaken and placed in a rolling furnace heated to the required temperature for 24 hours, followed by cooling to room temperature. The entire clay stabilizer mixture in the high-temperature, high-pressure closed reactor was transferred to a 250mL beaker, thoroughly shaken, and 10mL was quickly added to a glass centrifuge tube. The tube was then placed in a centrifuge with an automatic balancing function and centrifuged at 1500r / min for 15min. The swelling volume V1 of the bentonite was recorded. The swelling resistance calculation formula is as follows:

[0078]

[0079] In the formula: V0 is the expansion volume of bentonite in kerosene; V1 is the expansion volume of bentonite in the clay stabilizer aqueous solution; V2 is the expansion volume of bentonite in water.

[0080] Table 1. Evaluation results of room temperature anti-swelling performance of the examples and comparative samples.

[0081]

[0082]

[0083] Table 2 Evaluation results of anti-swelling performance of the sample in the examples at different temperatures

[0084]

[0085] As can be seen from Tables 1 and 2, the quaternary ammonium-type high-efficiency clay stabilizer provided by the present invention has superior performance. The anti-swelling rate of this product can reach more than 80% at a concentration of 0.3wt%, and the anti-swelling performance of the product is significantly improved with the increase of temperature. When the temperature rises to 120℃, the anti-swelling rate tends to stabilize, and when the temperature is further raised to 200℃, the anti-swelling rate is maintained at more than 90%.

Claims

1. A natural biomass modified temperature-sensitive clay stabilizer, characterized in that, The clay stabilizer has the following structural formula: Where X = H or, the degree of polymerization n is 300 to 3000.

2. The natural biomass-modified temperature-sensitive clay stabilizer of claim 1, wherein Its preparation method includes the following steps: 1) Add the raw material chitosan to the solvent and stir until it is completely dissolved. After heating in a water bath, add 2,3-epoxypropyltrimethylammonium chloride. After the reaction is completed, after precipitation, washing, filtration and drying, chitosan quaternary ammonium salt CTS-A is obtained. 2) The chitosan quaternary ammonium salt CTS-A synthesized in step 1) was stirred and reacted with excess sodium hydroxide solution at room temperature. After the reaction was completed, the product was distilled to remove water. The product obtained after water removal, CTS-E, was slowly added dropwise with an isopropanol solution of 2-chloroethyl-trimethylammonium chloride and heated in a water bath. After the reaction was completed, the pH of the product was adjusted to neutral. Then, the product was filtered, washed, vacuum filtered and dried to obtain the desired thermosensitive clay stabilizer.

3. The method of claim 2, wherein the natural biomass-modified warm-sensitive clay stabilizer is prepared by the steps of: (a) mixing a natural biomass with a clay to obtain a mixture; (b) drying the mixture; (c) calcining the dried mixture; and (d) grinding the calcined mixture. The solvent in step 1) is one of propanol, isopropanol, n-butanol or isobutanol.

4. The method of claim 2, wherein the natural biomass-modified warm-sensitive clay stabilizer is prepared by the steps of: (a) mixing a natural biomass with a clay to obtain a mixture; (b) drying the mixture; (c) calcining the dried mixture; and (d) grinding the calcined mixture. In step 1), the molar ratio of chitosan to 2,3-epoxypropyltrimethylammonium chloride is 1:(1-3).

5. The preparation method of the natural biomass-modified thermosensitive clay stabilizer according to claim 2, characterized in that, The drying conditions in step 1) of the reaction are drying at 105°C for 4–8 hours.

6. The preparation method of the natural biomass-modified thermosensitive clay stabilizer according to claim 2, characterized in that, In reaction step 1), the water bath heating temperature is 60–100°C, and the reaction time is 6–10 h.

7. The preparation method of the natural biomass-modified thermosensitive clay stabilizer according to claim 2, characterized in that, In reaction step 2), the mass fraction of the sodium hydroxide solution is 40-60%.

8. The preparation method of the natural biomass-modified thermosensitive clay stabilizer according to claim 2, characterized in that, In step 2), the mass ratio of chitosan quaternary ammonium salt CTS-A to sodium hydroxide solution is 1:(10-20), and the reaction time is 1-3 hours at room temperature.

9. The method of claim 2, wherein the natural biomass-modified warm-sensitive clay stabilizer is prepared by the steps of: (a) mixing a natural biomass with a clay; (b) drying the mixture; (c) calcining the dried mixture; (d) mixing the calcined mixture with a solvent; and (e) drying the mixture. In step 2), the mass fraction of the 2-chloroethyl-trimethylammonium chloride solution is 30-70%, and the mass ratio of the dehydrated product CTS-E to the 2-chloroethyl-trimethylammonium chloride solution is 1:(10-30).

10. The preparation method of the natural biomass-modified thermosensitive clay stabilizer according to claim 2, characterized in that, In step 2), the water bath heating temperature is 60–80℃, and the reaction time is 8–12 hours.

11. The preparation method of a natural biomass-modified thermosensitive clay stabilizer according to claim 2, characterized in that, In step 2), the pH of the reaction product is adjusted to neutral with hydrochloric acid, and the drying conditions are drying at 105℃ for 4-8 hours.

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