Intelligent profile control system and preparation method thereof

Abstract

The invention discloses an intelligent profile control system and a preparation method thereof.The preparation method comprises the steps that refined cotton is soaked in an alkaline aqueous solution at a first preset temperature for a first preset time, and a first mixed solution is obtained; squeezing the first mixed solution, crushing and curing to obtain a solid-liquid mixture; adding the solid-liquid mixture into a reaction kettle, adding epoxypropane and chloromethane, reacting at a second preset temperature for a second preset time, and reacting at a third preset temperature for a third preset time to obtain a reaction product; and carrying out post-treatment on the reaction product to obtain the temperature-sensitive polymer. The problem of fluid channeling in steam injection can be effectively solved, the preparation method is simple, the temperature resistance of the obtained temperature-sensitive gel system is remarkably improved, the phase change temperature is adjustable, the temperature-sensitive gel system can be specifically used under different working conditions, and the adopted raw materials are wide in source and low in price.

Description

Technical Field

[0001] The present invention relates to the technical field of oil production, and in particular to an intelligent profile control system and a preparation method thereof. Background Art

[0002] Steam injection development is one of the main development methods for heavy oil at present. However, due to large mobility differences and other influences, steam channeling phenomena are serious, and the problem of "high cycle and low efficiency" is prominent, seriously affecting the development effect. Traditional steam channeling control methods mostly focus on single plugging systems such as cement, gel, and foam. Cement is difficult to migrate deeply, has a short curing time, and high risks. Gel has poor high-temperature resistance and high costs. Foam has poor stability, short validity period, and complex processes, restricting the efficient control of heavy oil steam channeling.

[0003] In the gel plugging system for heavy oil thermal recovery, temperature-responsive plugging materials, as a kind of "intelligent fluid", after being driven by pressure into the formation, undergo phase transitions during the deep migration process with the change of formation temperature, and have broad application prospects. Thermosensitive reversible gels can achieve one-time injection and multi-round plugging effects. The Massachusetts Institute of Technology discovered the phase transition of the polymer network structure during the research on polypropylene gels, and through experiments, it was found that the change of external conditions greatly affects the gel volume. Through the research on the basic theory model of gel shrinkage-swelling, the physical mechanism of the critical state of gel phase transition, the interaction force, the synthesis method, and the establishment of the basic theory by researchers, temperature-sensitive intelligent gels have developed rapidly.

[0004] The domestic use of temperature-sensitive polymers for steam flooding in heavy oil reservoirs mainly focuses on cellulose ethers after cellulose modification processing, which have lower costs and good effects, and are applied in Liaohe Oilfield, Daqing Oilfield in the northeast of China, Karamay Oilfield and Tahe Oilfield in the west, and Bohai Oilfield. At present, the temperature-sensitive intelligent gel system urgently needs to solve the problem of high-temperature resistance to improve its applicability in oil reservoirs.

[0005] Based on this, the existing technology still needs to be improved. Summary of the Invention

[0006] To solve the above technical problems, an embodiment of the present invention provides an intelligent profile control system and a preparation method thereof to solve the technical problem that the high-temperature resistance of the existing temperature-sensitive intelligent gel system cannot meet the production requirements.

[0007] To solve the above technical problems, some embodiments of the present invention disclose an intelligent profile control system, which, by mass percentage, includes:

[0008] 0.2 - 0.4% of thermosensitive polymer, 0.5 - 2% of reinforcing agent, 1 - 5% of inorganic regulator, 1 - 5% of organic regulator, 0.2 - 0.8% of solubilizer, 0.02 - 0.15% of deoxidizer, 1 - 5% of urea, and the balance is water.

[0009] The embodiment of the present invention also discloses a preparation method of the above intelligent profile control system, including:

[0010] Step 1: Dissolve the thermosensitive polymer in 100 parts of deionized water according to the ratio, and stir and disperse it under heating conditions;

[0011] Step 2: After the dispersion is completed, cool it to room temperature and carry out aging treatment under airtight conditions;

[0012] Step 3: Add the proportioned amounts of reinforcing agent, inorganic regulator, organic regulator, solubilizer, deoxidizer and urea to the aged solution obtained after the aging treatment and stir well to obtain a mixed solution;

[0013] Step 4: Age the mixed solution in a sealed container at room temperature to obtain an intelligent profile control system.

[0014] Further, in Step 1, the heating temperature is 20 - 60 °C, the rotation speed of the magnetic stirrer used for stirring and dispersing is 300 - 500 r / min, and the stirring time is 30 - 50 min.

[0015] Further, in Step 2, the aging time is 24 - 36 h.

[0016] Further, in Step 3, the reinforcing agent is one or more of nano-silica and montmorillonite.

[0017] Further, the inorganic regulator is one or more of NaCl, CaCl2, and MgCl2.

[0018] Further, the organic regulator is one or more of ethanol, ethylene glycol, glycerol, sorbitol, sucrose, and polyethylene glycol.

[0019] Further, the solubilizer is one or more of benzyl alcohol, ethanol, propylene glycol, polysorbate 80, and cyclodextrin.

[0020] Further, the deoxidizer is one or more of thiourea and sodium sulfite.

[0021] Further, in Step 3, when stirring well, the rotation speed of the magnetic stirrer is 300 - 500 r / min, and the stirring time is 30 - 60 min.

[0022] Further, in Step 4, the aging time is 24 - 36 h.

[0023] Further, the preparation method of the thermosensitive polymer includes:

[0024] Step 1: Soak refined cotton in an alkaline aqueous solution at a first predetermined temperature for a first predetermined time to obtain a first mixture;

[0025] Step 2: Perform pressing treatment on the first mixture and crush and ripen it to obtain a solid-liquid mixture;

[0026] Step 3: Add the solid-liquid mixture to a reaction kettle, and add propylene oxide and methyl chloride, react at a second predetermined temperature for a second predetermined time, and react at a third predetermined temperature for a third predetermined time to obtain a reaction product;

[0027] Step 4: Perform post-treatment on the reaction product to obtain a thermosensitive polymer.

[0028] Further, by mass, in Step 1 of the preparation method of the thermosensitive polymer, the addition ratio of the refined cotton to the alkaline aqueous solution is 1:(25 - 40);

[0029] And, the mass fraction of the alkaline aqueous solution is 30% - 40%.

[0030] Further, in the preparation method of the thermosensitive polymer, the first predetermined temperature is 25°C - 30°C, and the first predetermined time is 90 - 120 min.

[0031] Further, in Step 2 of the preparation method of the thermosensitive polymer, the pressing ratio during the pressing treatment is 2.8 - 3.5.

[0032] Further, the ripening time for the crushing and ripening is 1 - 8 h.

[0033] Further, by mass, in Step 3 of the preparation method of the thermosensitive polymer, the ratio of the added amounts of propylene oxide, methyl chloride and refined cotton is (100 - 350):(600 - 1200):100.

[0034] Further, in Step 3 of the preparation method of the thermosensitive polymer, the second predetermined temperature is 30 - 60°C, and the second predetermined time is 1 - 3 h;

[0035] The third predetermined temperature is 75 - 85°C, and the third predetermined time is 1 - 2 h.

[0036] Further, in Step 4 of the preparation method of the thermosensitive polymer, the post-treatment of the reaction product includes: distilling the reaction product to remove the excess etherifying agent, neutralizing, washing, centrifuging and dehydrating, and drying at 100°C for 24 h to obtain a crude thermosensitive polymer.

[0037] Further, in the preparation method of the thermosensitive polymer, the post-treatment of the reaction product further includes: dissolving the crude thermosensitive polymer in water and heating it, and performing flocculation purification at a fourth temperature to remove water-soluble impurities, thereby obtaining a thermosensitive gel solution;

[0038] After heating and dehydrating the thermosensitive gel solution, perform centrifugal separation, drying, and pulverization to obtain thermosensitive polymer powder.

[0039] Adopting the above technical solution, the present invention has at least the following beneficial effects:

[0040] An intelligent profile control system and its preparation method provided by the present invention can effectively solve the channeling problem in steam injection. Its preparation method is simple, the obtained thermosensitive gel system has significantly improved temperature resistance, and the phase transition temperature is adjustable, enabling targeted use under different working conditions. The raw materials used have a wide source and low price. Description of the Drawings

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0042] Figure 1 It is an experimental chart of the dehydration rate of a comparative example of an intelligent profile control system disclosed in some embodiments of the present invention;

[0043] Figure 2 It is an experimental chart of the apparent viscosity of a comparative example of an intelligent profile control system disclosed in some embodiments of the present invention. Detailed Embodiments

[0044] Some embodiments of the present invention disclose an intelligent profile control system and its preparation method. The main component of the intelligent profile control system is a thermosensitive polymer, and the thermosensitive polymer can be prepared by the following preparation method:

[0045] Step 1: Immerse refined cotton in an alkaline aqueous solution at a temperature of 25 °C for 90 - 120 min;

[0046] Preferably, in Step 1, the refined cotton is 100 parts, and the alkaline aqueous solution is 2500 - 4000 parts;

[0047] Preferably, in Step 1, the alkaline aqueous solution is a KOH or NaOH aqueous solution with a mass fraction of 30% - 40%;

[0048] Step 2: Squeeze out the excess alkaline solution and pulverize it using a pulverizer;

[0049] Preferably, in step 2, the pressing ratio is about 2.8 - 3.5, and the ripening time of the crusher is controlled within 1 - 8 h;

[0050] Step 3: Place the crushed solid - liquid mixture in a high - temperature and high - pressure reactor, and inject a certain amount of propylene oxide and methyl chloride;

[0051] Preferably, in step 3, inject a certain amount of propylene oxide and methyl chloride, wherein, 100 - 350 parts of propylene oxide and 600 - 1200 parts of methyl chloride;

[0052] Step 4: Raise the temperature of the high - temperature and high - pressure reactor to 30 - 60 °C, and control the reaction time to be 1 - 3 h;

[0053] Step 5: Adjust the temperature to 75 - 85 °C, continue the etherification reaction, and control the reaction time to be 1 - 2 h;

[0054] Step 6: Remove the reaction product, distill to remove the excess etherifying agent, neutralize, wash, and then centrifuge to dehydrate, and dry at 100 °C for 24 h to obtain the crude product of the temperature - sensitive polymer;

[0055] Step 7: Dissolve the temperature - sensitive polymer in step 6 in water, raise the temperature to 80 °C, and remove the water - soluble impurities through multiple flocculation and purification processes;

[0056] Step 8: Close - heat the temperature - sensitive gel solution in step 7 to 120 °C to dehydrate the temperature - sensitive gel, and then through centrifugal separation, drying, and pulverization, the purified temperature - sensitive gel powder can be obtained;

[0057] The present invention also provides a preparation method and application of a temperature - sensitive gel system (intelligent profile control system).

[0058] A temperature - sensitive gel system, namely an intelligent profile control system, disclosed in some embodiments of the present invention, can be composed of the following components:

[0059] 0.2 - 0.4% temperature - sensitive polymer, 0.5 - 2% enhancer, 1 - 5% inorganic regulator, 1 - 5% inorganic regulator, 0.2 - 0.8% solubilizer, 0.02 - 0.15% deoxidizer, 1 - 5% urea, and the balance is water.

[0060] The preparation method is as follows:

[0061] Step 1: Take 0.12 - 0.4 parts of the prepared temperature - sensitive polymer and place it in 100 parts of deionized water, and use a magnetic stirrer to fully disperse it under heating conditions;

[0062] Preferably, in step 1, the rotation speed of the magnetic stirrer is 300 - 500 r / min, the temperature is controlled at 20 - 60 °C, and the stirring time is 30 - 50 min;

[0063] Step 2: Cool the well-dispersed solution in Step 1 to room temperature and fully cure it under airtight conditions;

[0064] Step 3: Take out the cured solution in Step 2, add 0.5 - 3 parts of reinforcing agent, 1 - 5 parts of inorganic regulator, 1 - 5% parts of inorganic regulator, 0.2 - 0.8 parts of solubilizer, 0.02 - 0.2 parts of deoxidizer, and 1 - 5 parts of urea, and stir well;

[0065] Preferably, in Step 32, the curing time is 24 - 36 h;

[0066] Preferably, in Step 3, the reinforcing agent is one or more of nano-silica and montmorillonite;

[0067] Preferably, in Step 3, the inorganic regulator is one or more of NaCl, CaCl2, and MgCl2;

[0068] Preferably, in Step 3, the organic regulator is one or more of ethanol, ethylene glycol, glycerol, sorbitol, sucrose, and polyethylene glycol;

[0069] Preferably, in Step 3, the solubilizer is one or more of benzyl alcohol, ethanol, propylene glycol, polysorbate 80, and cyclodextrin;

[0070] Preferably, in Step 3, the rotational speed of the magnetic stirrer is 300 - 500 r / min, and the stirring time is 30 - 60 min;

[0071] Step 4: Place the well-dispersed product in Step 13 in a sealed container and cure it again at room temperature;

[0072] Preferably, in Step 4, the curing time is 24 - 36 h.

[0073] In the above gel system, the highly branched topology of silica nanoparticles and montmorillonite forms a large specific surface area, which can form strong hydrogen bonds with polymers. Due to its unique topological structure and abundant surface hydroxyl groups, the increase in the specific surface area of each particle enhances the crosslinking density of the polymer;

[0074] In the above gel system, adding organic additives with the same functional groups (-OH) as methyl-based thermosensitive polymers, the addition of ethanol, propylene glycol, and polyethylene glycol will increase the gel point temperature of the system to a certain extent, while the addition of glycerol, sucrose, sorbitol, and inorganic compounds will cause the gel point temperature of the system to decrease, enabling the phase transition temperature to be adjustable.

[0075] In the above gel system, the addition of solubilizer promotes the formation of microemulsions, reduces electrostatic repulsion, and helps the formation of micelles;

[0076] In the above gel system, urea can undergo a certain degree of cross-linking reaction with methyl-based thermosensitive polymers under high temperature and high pressure conditions, thereby improving the stability of the gel. At the same time, it will not affect the gel point temperature of the thermosensitive polymer aqueous solution system and the thermosensitive reversible performance in the gel system, and to a certain extent, it can reduce the viscosity of the system under low temperature conditions and enhance the injection performance of the system.

[0077] Example 1:

[0078] Soak 100 parts of refined cotton in 3000 parts of an aqueous NaOH solution with a mass fraction of 30% at a temperature of 25 °C for 90 min, then press to remove the excess alkali solution, and use a pulverizer to pulverize it; place the pulverized solid-liquid mixture in a high-temperature and high-pressure reaction kettle, and inject 200 parts of propylene oxide and 800 parts of methyl chloride; raise the temperature of the high-temperature and high-pressure reaction kettle to 50 °C, and the etherification reaction time is 3 h; adjust the temperature to 80 °C and continue the etherification reaction for 2 h, remove the reaction product, distill to remove the excess etherifying agent, neutralize, wash, and then centrifuge to dehydrate, and dry at 100 °C for 24 h to obtain a crude thermosensitive polymer; dissolve the crude thermosensitive polymer in water, raise the temperature to 80 °C, and remove the water-soluble impurities through 3 times of flocculation purification; dissolve the thermosensitive polymer in water, seal and heat to 120 °C to dehydrate the thermosensitive gel, and then through centrifugal separation, drying, and pulverization, the purified thermosensitive gel powder can be obtained;

[0079] Example 2:

[0080] Take the thermosensitive polymer prepared in Example 1, the rotation speed of the magnetic stirrer is 300 - 500 r / min, the temperature is controlled at 30 °C, and the stirring time is 40 min; prepare aqueous solutions with mass fractions of 0.1%, 0.2%, 0.3%, and 0.4%, and the viscosities at 30 °C for 4 h are shown in Table 1.

[0081] According to the test results in Table 1, to improve the injectability of the gel, a thermosensitive polymer mass fraction of 0.3% is selected.

[0082] Table 1 Viscosity test of thermosensitive gels with different concentrations at 30 °C

[0083] Concentration / wt% 0.1％ 0.2％ 0.3％ 0.4％ Viscosity / mPa·s 26 77 221 643

[0084] Example 3:

[0085] Take 100 mL of the 0.3% thermosensitive polymer solution prepared in Example 2 and place it in a wide-mouth bottle. Conduct a 12-hour gelation experiment in an oven at temperatures of 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, and 140 °C. Observe the results as shown in Table 2. Conduct apparent viscosity and dehydration rate tests. From Tables 3 and 4, it can be obtained that at 90 - 140 °C, as the temperature increases, the apparent viscosity of the gel system gradually decreases, and the dehydration rate gradually increases. At 120 °C, the viscosity of the gel system drops rapidly, and the dehydration rate increases rapidly. Therefore, the temperature resistance of this gel system is 120 °C.

[0086] Table 2 Gelation states of thermosensitive gels under different temperature conditions

[0087]

[0088] Table 3 Apparent viscosities of thermosensitive gels under different temperature conditions

[0089] Temperature / °C 90℃ 100℃ 110℃ 120℃ 130℃ 140℃ Apparent viscosity / mPa·s 142 126 113 106 72 66

[0090] Table 4 Dehydration rates of thermosensitive gels under different temperature conditions

[0091] Temperature / °C 90℃ 100℃ 110℃ 120℃ 130℃ 140℃ Dehydration rate / % 8 14 20 36 63 72

[0092] Example 4:

[0093] Take 0.3 parts of the prepared thermosensitive polymer and place it in 100 parts of deionized water. Use a magnetic stirrer under heating conditions at 300 - 500 r / min, control the temperature at 35 °C, and stir for 30 min. Cool the solution to room temperature and conduct sufficient aging for 24 h under closed conditions; take out the aged solution in step 2, add 1% reinforcing agent nano-silica, 2% NaCl, 1.5% CaCl2 inorganic regulators, 3% organic regulator polyethylene glycol, 0.4% solubilizer benzyl alcohol, 0.1% deoxidizer sodium sulfite, and 3% urea, with the balance being water. The rotational speed of the magnetic stirrer is 300 - 500 r / min. After stirring for 40 min, place it in a closed container at room temperature and conduct aging for 24 h again to obtain the preferred intelligent profile control system.

[0094] Conduct a 12-hour gelation experiment on the system in Example 2 and this system in an oven at temperatures of 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, and 160 °C. Observe the results as Figure 1 、 2As shown in the figure, by conducting apparent viscosity and dehydration rate tests, it can be obtained that at 90 - 160 °C, as the temperature increases, the apparent viscosity of the optimized gel system gradually decreases, and the dehydration rate gradually increases. However, at 160 °C, the gel system still maintains a relatively high viscosity and a relatively low dehydration rate. Therefore, the temperature resistance of this gel system can be increased to 140 - 160 °C.

[0095] Example 5:

[0096] Take the intelligent profile control system obtained in Example 4 and place it in a colorimetric tube. Conduct gelation stability experiments for different periods in an oven at temperature conditions of 90 °C, 100 °C, 110 °C, 120 °C, 140 °C, and 160 °C.

[0097] As can be seen from Table 5, compared with the single - formula system in Example 3, the stability of the gel system obtained by this method is further enhanced. In the temperature range of 140 - 160 °C, the stable period of this system can be controlled at about 14 days.

[0098] Table 5 Gelation states of intelligent gels under different temperature conditions

[0099]

[0100]

[0101] Example 6:

[0102] As shown in Table 6, take formation aqueous solutions from different blocks to prepare a thermosensitive gel solution with a mass fraction of 0.3%. The steps are the same as in Example 4. Take 100 mL and place it in an oven at 140 °C. After 12 days, the gel is white, in an opaque jelly - like and non - flowing state, and shows good visco - elasticity during the pouring process, indicating that this thermosensitive gel has good tolerance to salinity and is suitable for reservoirs with different salinities.

[0103] Table 6 Gelation states of intelligent gels with different salinities

[0104]

[0105] Example 7

[0106] The formation water of the NM oilfield was used to prepare a thermosensitive gel solution with a mass fraction of 0.3% and placed in an intermediate piston container. An artificial sand-packed core with a size of φ2.5 cm × 15 cm was used to simulate the formation. After the core tube was evacuated for 8 h, it was saturated with deionized water. Deionized water was injected at a rate of 2 mL / min and then placed in an incubator at 80 °C to measure the permeability of the sand-packed tube. After the sand-packed tube was cooled below 50 °C, 0.2 PV of the thermosensitive gel solution in Example 4 above was injected at an injection rate of 2 mL / min, and then 0.05 PV was displaced with deionized water. After being kept at a constant temperature of 140 °C in the sand-packed tube for 1 h, the permeability of the sand-packed tube was measured after displacing 1 PV with deionized water.

[0107] As shown in Table 7, the plugging ability of the thermosensitive gel was determined by measuring the pressure difference at both ends of the sand-packed tube, E = (P 堵后 −P 堵前 ) / P 堵后 × 100%. The plugging rates of the cores with original permeabilities of 2468 mD and 3046 mD were 99.63% and 98.26% respectively. It can be seen that under high-temperature conditions, this thermosensitive gel has a high plugging strength and can effectively plug the channeling channels under thermal recovery conditions.

[0108] Table 7 Core plugging experiment

[0109] Core number Original permeability / mD Original permeability / mD Blocking rate / % #1 2468 18.76 99.63 #2 3046 32.14 98.26

[0110] Example 8

[0111] This example provides an example of the application of an intelligent gel profile control agent in the profile control of production wells in deep high-temperature reservoirs.

[0112] Taking Well 25-12 in the J oilfield as an example, the steam absorption of this well is uneven and the steam channeling phenomenon is serious. There are high-permeability channels in the formation, and the production effect has been deteriorating year by year. In order to effectively control the adverse effects caused by the steam channeling phenomenon, the thermosensitive gel profile control agent prepared in Example 4 was used to implement deep profile control measures on this well to improve the production effect and increase the utilization degree.

[0113] The designed profile control radius of this well is 20 m, and the profile control dosage is 820 m 3 , and the displacement is 15 - 25 m 3 / h. Before construction, the injection indicator curve and pressure drop curve were tested. According to the inflection point pressure of the injection indicator curve, the maximum injection pressure for profile control was determined. The injection displacement was controlled at 2 - 4 m3 / h, the designed ramp pressure ≤ 3 MPa, and the maximum construction pressure ≤ 15 MPa. After the measures, the steam injection pressure of this well increased by 2.1 MPa after 3 rounds of steam injection, the average water cut decreased from 96.2% to 82.6%, and the cumulative oil production increased by 2413.2 t, with obvious oil production increase effect.

Claims

1. An intelligent profile control system, characterized in that, By mass percentage, it includes: 0.2 - 0.4% of thermosensitive polymer, 0.5 - 2% of reinforcing agent, 1 - 5% of inorganic regulator, 1 - 5% of organic regulator, 0.2 - 0.8% of solubilizer, 0.02 - 0.15% of deoxidizer, 1 - 5% of urea, and the balance is water.

2. A preparation method of the intelligent profile control system according to claim 1, characterized in that, It includes: Step 1: Dissolve the thermosensitive polymer in 100 parts of deionized water according to the ratio, and stir and disperse it under heating conditions. Step 2: After the dispersion is completed, cool it to room temperature and carry out aging treatment under airtight conditions. Step 3: Add the proportioned amounts of reinforcing agent, inorganic regulator, organic regulator, solubilizer, deoxidizer and urea to the aged solution obtained after the aging treatment and stir well to obtain a mixed solution. Step 4: Age the mixed solution in a closed container at room temperature to obtain an intelligent profile control system.

3. According to the preparation method described in claim 2, characterized in that, In Step 1, the heating temperature is 20 - 60°C, the rotation speed of the magnetic stirrer used for stirring and dispersing is 300 - 500 r / min, and the stirring time is 30 - 50 min.

4. According to the preparation method described in claim 2, characterized in that, In Step 2, the aging time is 24 - 36 h.

5. According to the preparation method described in claim 2, characterized in that, In Step 3, the reinforcing agent is one or more of nano-silica and montmorillonite.

6. According to the preparation method described in claim 2, characterized in that, In Step 3, the inorganic regulator is one or more of NaCl, CaCl2, and MgCl2.

7. According to the preparation method described in claim 2, characterized in that, In Step 3, the organic regulator is one or more of ethanol, ethylene glycol, glycerol, sorbitol, sucrose, and polyethylene glycol.

8. According to the preparation method described in claim 2, characterized in that, In Step 3, the solubilizer is one or more of benzyl alcohol, ethanol, propylene glycol, polysorbate 80, and cyclodextrin.

9. According to the preparation method described in claim 2, characterized in that, In Step 3, the deoxidizer is one or more of thiourea and sodium sulfite.

10. According to the preparation method described in claim 2, characterized in that, In Step 3, when stirring well, the rotation speed of the magnetic stirrer is 300 - 500 r / min, and the stirring time is 30 - 60 min.

11. According to the preparation method described in claim 2, characterized in that, In Step 4, the aging time is 24 - 36 h.

12. According to the preparation method described in claim 2, characterized in that, The preparation method of the thermosensitive polymer includes: Step 1: Soak the refined cotton in an alkaline aqueous solution at a first predetermined temperature for a first predetermined time to obtain a first mixed solution. Step 2: Carry out pressing treatment on the first mixed solution and crush and age it to obtain a solid-liquid mixture. Step 3: Add the solid-liquid mixture to a reaction kettle, and add propylene oxide and chloromethane, react at a second predetermined temperature for a second predetermined time, and react at a third predetermined temperature for a third predetermined time to obtain a reaction product. Step 4: Carry out post-treatment on the reaction product to obtain a thermosensitive polymer.

13. According to the preparation method described in claim 12, characterized in that, In Step 1 of the preparation method of the thermosensitive polymer by mass, the addition ratio of the refined cotton to the alkaline aqueous solution is 1:(25 - 40). Moreover, the mass fraction of the alkaline aqueous solution is 30% - 40%.

14. According to the preparation method described in claim 12 or 13, characterized in that, In the preparation method of the thermosensitive polymer, the first predetermined temperature is 25°C - 30°C, and the first predetermined time is 90 - 120 min.

15. According to the preparation method described in claim 12, characterized in that, In Step 2 of the preparation method of the thermosensitive polymer, the pressing ratio during the pressing treatment is 2.8 - 3.

5.

16. The preparation method according to claim 12, wherein In Step 2 of the preparation method of the thermosensitive polymer, the aging time of the crushing and aging is 1 - 8 h.

17. The preparation method according to claim 12, wherein In step three of the preparation method of the thermosensitive polymer, by mass, the ratio of the addition amounts of propylene oxide, chloromethane and refined cotton is (100 - 350):(600 - 1200):

100.

18. The preparation method according to claim 12 or 14, wherein In step three of the preparation method of the thermosensitive polymer, the second predetermined temperature is 30 - 60 °C, and the second predetermined time is 1 - 3 h; The third predetermined temperature is 75 - 85 °C, and the third predetermined time is 1 - 2 h.

19. The preparation method according to claim 12, wherein In step four of the preparation method of the thermosensitive polymer, the post-treatment of the reaction product includes: distilling the reaction product to remove the excess etherifying agent, neutralizing, washing, centrifuging to dehydrate, and drying at 100 °C for 24 h to obtain the crude thermosensitive polymer.

20. The preparation method according to claim 12, wherein In the preparation method of the thermosensitive polymer, the post-treatment of the reaction product further includes: dissolving the crude thermosensitive polymer in water and heating, performing flocculation purification at the fourth temperature to remove water-soluble impurities to obtain a thermosensitive gel solution; After heating and dehydrating the thermosensitive gel solution, centrifuging, drying and pulverizing are carried out to obtain the thermosensitive polymer powder.

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