A clean drag reducer for fracturing and preparation method thereof
By combining bacterial cellulose with itaconic acid, a high-temperature resistant, shear-resistant, environmentally friendly clean drag reducer was prepared, which solved the problems of existing drag reducers such as large environmental pollution and poor temperature resistance, and improved the drag reduction effect and reservoir protection ability.
Patent Information
- Application Number
- CN202510796810.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-16
- Publication Date
- 2025-09-30
- Estimated Expiration
- 2045-06-16
AI Technical Summary
Existing drag reducers cause serious environmental pollution, have poor high temperature resistance, poor shear resistance, poor drag reduction performance under high salinity, and cause great damage to reservoirs.
A clean drag reducer for fracturing was prepared by combining bacterial cellulose with itaconic acid through carbonization and modification. The nano-network structure of bacterial cellulose and the biodegradability of itaconic acid were utilized to improve the temperature resistance, shear resistance and environmental friendliness of the drag reducer.
It maintains good drag reduction effect under high temperature, high salt and high shear rate conditions, reduces environmental pollution, reduces friction resistance, improves recovery rate and reduces damage to the core.
Smart Images
Figure CN120329498B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of petroleum extraction, and particularly relates to a clean drag reducer for fracturing and a preparation method thereof. Background Art
[0002] Slickwater fracturing is the primary technical means for achieving efficient development of shale reservoirs. Fracturing fluid, the "blood" of fracturing, determines the success or failure of fracturing operations. The high volume and high displacement characteristics of slickwater fracturing fluid create significant frictional resistance in the wellbore. To overcome this high frictional resistance and effectively reduce pumping costs, drag reducers, which offer high drag reduction efficiency at low concentrations, are widely used as core additives for slickwater fracturing. These drag reducers significantly improve the fluidity of the fracturing fluid, reduce frictional resistance, and thus enhance shale gas recovery.
[0003] Currently, most drag reducers are acrylamide copolymers. For example, patent application number 2023108679077 discloses a drag reducer for fracturing and its preparation method. These agents offer excellent drag reduction, require relatively low dosage, and exhibit strong adaptability, achieving excellent results in both indoor evaluations and field applications. However, several issues remain: the use of relatively high levels of pollutants can significantly damage reservoirs and the environment, and they also suffer from poor high-temperature and shear resistance, as well as poor drag reduction performance at high salinity levels. In line with the requirements for developing green and environmentally friendly drag reducers, a green, environmentally friendly, and high-performance drag reducer remains an urgent need. Summary of the Invention
[0004] In response to the current technical problems, the present invention provides a clean drag reducer for fracturing and a preparation method thereof. The bacterial cellulose used in the drag reducer has a high specific surface area, good stability, high temperature resistance and good shear resistance, and is environmentally friendly. By combining the bacterial cellulose with acrylamide and itaconic acid, the drag reduction effect of the drag reducer is effectively improved, and the stabilizer, salt resistance and temperature resistance of the drag reducer are improved. The use of bacterial cellulose and other substances such as itaconic acid has good biodegradability, and also has antibacterial, clean and scale-inhibiting effects, with little pollution to the environment and little damage to the core.
[0005] The technical solutions of the present invention are as follows:
[0006] A clean drag reducer for fracturing, comprising, by weight, 1-10 parts of carbonized bacterial cellulose, 30-40 parts of acrylamide, 20-35 parts of itaconic acid, 0.1-0.4 parts of an initiator, 1-3 parts of a surfactant, and 50-70 parts of deionized water.
[0007] Preferably, the preparation method of carbonized bacterial cellulose is as follows:
[0008] (1) freeze-drying the bacterial cellulose dispersion to obtain freeze-dried bacterial cellulose;
[0009] (2) carbonizing the freeze-dried bacterial cellulose in an inert atmosphere to obtain carbonized bacterial cellulose;
[0010] The solid content of bacterial cellulose dispersion is 1 ~ 20%, the diameter is 50 ~ 100nm, and the length is less than 50μm.
[0011] More preferably, the freezing temperature is -60~0°C, the heating rate of the carbonization treatment is 3~8°C, the holding temperatures are 200~300°C, 400~600°C and 800~1000°C, and the corresponding holding time is 30min~3h.
[0012] Preferably, the carbonized bacterial cellulose is used after being activated and modified. The specific method is as follows: adding the carbonized bacterial cellulose to a mixed solution of sulfuric acid and hydrogen peroxide, activating it for a period of time, immersing the activated carbonized bacterial cellulose in a silane coupling agent solution, stirring it, then taking it out, and curing it to obtain modified carbonized bacterial cellulose.
[0013] More preferably, the amount of sulfuric acid is 30-40 wt %, the amount of hydrogen peroxide is 15-20 wt %, and the activation is carried out at 95-105° C. for 1-1.5 h.
[0014] Further preferably, the silane coupling agent is a silane coupling agent containing an unsaturated double bond, the mass ratio of carbonized bacterial cellulose to the silane coupling agent solution is 10-20:100, and the mass fraction of the silane coupling agent solution is 20-30%.
[0015] More preferably, the silane coupling agent containing an unsaturated double bond is one of vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane and allyltriethoxysilane.
[0016] More preferably, the stirring condition is: stirring at room temperature for 70-100 min; and the curing condition is curing at 50-80° C. for 3-12 h.
[0017] Preferably, the surfactant is one or more of sodium α-olefin sulfonate, dodecyl dimethyl betaine, and lauryl amidopropyl betaine. Further preferably, sodium α-olefin sulfonate is used in combination with dodecyl dimethyl betaine or lauryl amidopropyl betaine, which has an excellent effect of dispersing the modified carbonized bacterial cellulose and the polymer.
[0018] Preferably, the initiator is one of azobiscyclohexylcarbonitrile and azobisisoheptanenitrile.
[0019] Preferably, itaconic acid has a good antibacterial effect. However, due to the variability of actual conditions, 0.01-0.02 parts of a biocide, such as benzalkonium chloride, can be added to the drag reducer according to actual needs.
[0020] A preparation method of a clean drag reducer for fracturing comprises the following specific preparation steps: mixing acrylamide, itaconic acid and water, stirring, adding carbonized bacterial cellulose, a surfactant and an initiator, heating and stirring for 10-30 minutes to obtain the drag reducer.
[0021] The present invention creatively uses bacterial cellulose, which is a natural biological material with a unique three-dimensional nano-network structure. The bacterial cellulose has nanofiber micropores and mesoporous structures, and has high porosity and crystallinity. Its degradability is better than that of traditional materials that increase heat resistance and shear resistance. Introducing it into the fracturing fluid system can partially replace components that pollute the environment, which is in line with the development trend of green fracturing fluid. After a specific carbonization treatment process, the bacterial cellulose after carbonization still has a high specific surface area and porous structure, and it still has excellent thermal stability and mechanical strength, which can hinder the close stacking of particles, reduce the tendency of agglomeration, and reduce random agglomeration; it has high mechanical strength and is also conducive to maintaining structural stability under shear conditions; the special structure of bacterial cellulose increases the heat transfer path, further avoiding the destruction of the drag reducer at high temperature; and the special structure of the carbonized bacterial cellulose has a certain adsorption effect, which can adsorb particles, impurities, and pollutants, and has a good cleaning effect.
[0022] In the present invention, the carbonized bacterial cellulose is first activated and then modified using a silane coupling agent containing an unsaturated bond. The modified carbonized bacterial cellulose is more conducive to subsequent operations.
[0023] Itaconic acid is used as a monomer in the present invention. Itaconic acid is mainly produced by a biological fermentation method. The raw materials are mainly renewable resources such as corn, sucrose and straw. It has significant bio-based characteristics and is biodegradable. Due to the wide availability of raw materials, dependence on petroleum resources is reduced. Itaconic acid is an environmentally friendly chemical substance. Itaconic acid also has scale inhibition and stabilization effects, preventing particle aggregation in the fracturing fluid and prolonging the stability of the system. Itaconic acid also has an antibacterial effect and can bind to metal particles, organic pollution, etc., which is conducive to cleaning and environmental protection, and reduces environmental pollution.
[0024] The present invention is prepared by modifying carbonized bacterial cellulose, acrylamide, itaconic acid, etc.; wherein the modified carbonized bacterial cellulose is beneficial to improving temperature resistance, stability and shear resistance; acrylamide (AM) as a main chain monomer has a linear long chain structure and is easy to form a high molecular weight polymer through free radical polymerization, providing excellent drag reduction effect; using itaconic acid to introduce two carboxyl groups into acrylamide, it is helpful to improve the dispersion of the polymer in water, more easily form a stable solution, and facilitate on-site preparation and transportation; and itaconic acid has antibacterial, scale inhibition and stabilizing effects, is environmentally friendly, and can reduce The carbonized bacterial cellulose modified by acrylamide and itaconic acid can still maintain viscosity under high temperature, high salt and high shear rate conditions, reduce the internal friction of fluid flow, and thus improve the drag reduction effect. Due to the increase in viscosity, it helps to better carry the proppant into the ground fracture, increase its sand carrying performance, improve the conductivity of the fracture, improve the pumping efficiency of the fracturing fluid, and greatly reduce energy consumption. After the fracturing operation is completed, the drag reducer with good stability can also reduce problems in the backflow process, help to better recover the fracturing fluid, reduce environmental pollution and improve resource utilization.
[0025] The present invention provides a drag reducer for shale oil fracturing and a preparation method thereof. The drag reducer effectively improves the drag reduction effect and stability of the drag reducer by introducing bacterial cellulose and itaconic acid. The drag reducer still has a good drag reduction effect under high temperature, high salt and high shear rate conditions, has excellent high temperature resistance, salt resistance and shear resistance, and is environmentally friendly. At the same time, the drag reducer also has scale inhibition, cleaning and antibacterial effects, thereby reducing environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 This is a SEM image of the carbonized bacterial cellulose prepared in Example 1;
[0027] Figure 2 This is the XRD pattern of the carbonized bacterial cellulose prepared in Example 1. DETAILED DESCRIPTION
[0028] The present invention will be further described below with reference to specific embodiments, but is not limited thereto.
[0029] The experimental methods described in the examples are conventional methods unless otherwise specified, and the reagents and materials used are commercially available unless otherwise specified.
[0030] The diameter of the bacterial cellulose described below is 50 to 100 nm and the length is less than 50 μm. The stirring described below uses ultrasonic vibration to ensure uniform mixing of the substances.
[0031] Example 1
[0032] A method for preparing carbonized bacterial cellulose:
[0033] (1) Freeze-drying the bacterial cellulose dispersion (solid content 15%) and freezing it at -50°C with liquid nitrogen to obtain freeze-dried bacterial cellulose;
[0034] (2) The freeze-dried bacterial cellulose was carbonized in an inert atmosphere (Ar) at a heating rate of 3°C / min, at 300°C for 2 h, at 400°C for 2 h, and at 800°C for 1 h to obtain carbonized bacterial cellulose;
[0035] (3) The carbonized bacterial cellulose is placed in water, and the carbonized bacterial cellulose is evenly dispersed in the water by ultrasonic dispersion, and then dried for later use.
[0036] SEM image of carbonized bacterial cellulose prepared by the above method ( Figure 1 ),pass Figure 1 As shown, the carbonized bacterial cellulose still shows the structure of bacterial cellulose; the XRD pattern of the carbonized bacterial cellulose prepared by the above method ( Figure 2 ),pass Figure 2 As shown in Figure 3, the broad diffraction peak of carbonized bacterial cellulose near 25° comes from the (002) crystal plane of graphite, indicating that the bacterial cellulose has been graphitized.
[0037] Example 2
[0038] A method for preparing modified carbonized bacterial cellulose:
[0039] (1) 30 g of the carbonized bacterial cellulose prepared in Example 1 was added to a mixed solution of 100 g of 40 wt% H2SO4 and 20 g of 20 wt% H2O2, and activated at 10°C for 1 h to obtain activated carbonized bacterial cellulose;
[0040] (2) 13 g of activated carbonized bacterial cellulose was immersed in 100 g of 4 wt% vinyltriethoxysilane coupling agent solution, stirred at room temperature for 100 min, then taken out and cured at 55 °C for 10 h to obtain modified carbonized bacterial cellulose.
[0041] Example 3
[0042] A clean drag reducer for fracturing, comprising, by weight, 3 parts of carbonized bacterial cellulose (prepared in Example 1), 30 parts of acrylamide, 25 parts of itaconic acid, 0.2 parts of an initiator (azobisisoheptonitrile), 1 part of a surfactant (sodium α-olefin sulfonate), and 55 parts of deionized water;
[0043] The specific preparation method is as follows:
[0044] Acrylamide, itaconic acid and water were mixed and stirred, carbonized bacterial cellulose, surfactant and initiator were added, and the temperature was raised and stirred for 10 minutes to obtain a drag reducer.
[0045] Example 4
[0046] The difference from Example 3 is that modified carbonized bacterial cellulose (prepared in Example 2) is used, and the rest is the same as Example 3.
[0047] Example 5
[0048] A clean drag reducer for fracturing, comprising, by weight, 5 parts of modified carbonized bacterial cellulose (prepared in Example 2), 35 parts of acrylamide, 20 parts of itaconic acid, 0.2 parts of an initiator (azobisisoheptonitrile), 2 parts of a surfactant (sodium α-olefin sulfonate and dodecyl dimethyl betaine in a mass ratio of 3:4), and 55 parts of deionized water;
[0049] The specific preparation method is as follows:
[0050] Acrylamide, itaconic acid and water were mixed and stirred, carbonized bacterial cellulose, surfactant and initiator were added, and the temperature was raised and stirred for 15 minutes to obtain a drag reducer.
[0051] Example 6
[0052] A clean drag reducer for fracturing, comprising, by weight, 9 parts of modified carbonized bacterial cellulose (prepared in Example 2), 40 parts of acrylamide, 35 parts of itaconic acid, 0.3 parts of an initiator (azobisisoheptonitrile), 3 parts of a surfactant (sodium α-olefin sulfonate and laurylamidopropyl betaine in a mass ratio of 3:4), and 70 parts of deionized water;
[0053] The specific preparation method is as follows:
[0054] Acrylamide, itaconic acid and water were mixed and stirred, carbonized bacterial cellulose, surfactant and initiator were added, and the temperature was raised and stirred for 30 minutes to obtain a drag reducer.
[0055] Comparative Example 1
[0056] A method for preparing carbonized bacterial cellulose:
[0057] (1) Freeze-drying the bacterial cellulose dispersion (solid content 15%) and freezing it at -50°C with liquid nitrogen to obtain freeze-dried bacterial cellulose;
[0058] (2) The freeze-dried bacterial cellulose was carbonized in an inert atmosphere (Ar) at a heating rate of 5°C / min and kept at 800°C for 4 h to obtain carbonized bacterial cellulose;
[0059] (3) The carbonized bacterial cellulose is placed in water, and the carbonized bacterial cellulose is evenly dispersed in the water by ultrasonic dispersion, and then dried for later use.
[0060] Comparative Example 2
[0061] The difference from Example 2 is that the carbonized bacterial cellulose prepared in Comparative Example 1 is used, and the other conditions are the same as those in Example 2.
[0062] Comparative Example 3
[0063] The difference from Example 5 is that the modified carbonized bacterial cellulose prepared in Comparative Example 2 is used, and the other conditions are the same as those in Example 5.
[0064] Comparative Example 4
[0065] The difference from Example 5 is that the amount of modified carbonized bacterial cellulose added is 0, and the rest is the same as Example 5.
[0066] Comparative Example 5
[0067] The difference from Example 5 is that crotonic acid is used instead of itaconic acid, and the rest is the same as Example 5.
[0068] Comparative Example 6
[0069] The difference from Example 5 is that sorbitol polyoxyethylene ether is used to replace the surfactant, and the other steps are the same as Example 5.
[0070] Comparative Example 7
[0071] Common commercially available polyacrylamide drag reducers.
[0072] Test example
[0073] The drag reducer prepared above was prepared into a 1 wt% solution.
[0074] Test Example 1: Temperature resistance and shear resistance test
[0075] Shear resistance test
[0076] The rheometer was used to measure the -1 , continuously shear the solution for 2 h, measure the apparent viscosity with a viscometer, and calculate the viscosity retention rate (%).
[0077] Heat resistance test
[0078] At 150℃ and 170s -1 , continuously shear the solution for 2 h, measure the apparent viscosity, and calculate the viscosity retention rate (%).
[0079] Viscosity retention rate (%) = (apparent viscosity η1 at the time of measurement - apparent viscosity η0 in the initial state) / apparent viscosity η0 in the initial state × 100%; the results are shown in Table 1.
[0080] Table 1 is the test data of Examples 3-6 and Comparative Examples 3-7
[0081]
[0082] It can be clearly seen from the above data that the temperature resistance and shear resistance of Examples 3-6 are significantly higher than those of Comparative Examples 3-7; the product of Comparative Example 3 uses the modified carbonized bacterial cellulose prepared in Comparative Example 2 relative to Example 5, so that the temperature resistance and shear resistance of the prepared drag reducer are significantly poorer. It can be seen that the bacterial cellulose treated by different carbonization methods has a greater influence on the retention of the bacterial cellulose structure. The carbonization method of Example 1 obtains carbonized bacterial cellulose, which retains the special structure of bacterial cellulose to the greatest extent, and the prepared drag reducer significantly improves the temperature resistance and shear resistance; Comparative Example 4 does not use modified carbonized bacterial cellulose relative to Example 5, and its shear resistance and temperature resistance are significantly poor, which effectively proves the mechanical strength, high temperature resistance and other characteristics of bacterial cellulose. And the unique structure plays a very critical role in the heat resistance and shear resistance of the drag reducer; Comparative Example 5 replaces itaconic acid with respect to Example 5, and the heat resistance and shear resistance become worse, because itaconic acid can improve the water solubility of the polymer, and can make the bacterial cellulose more evenly dispersed in water. If the dispersion is uneven, the stability of the drag reducer will be significantly reduced. At the same time, itaconic acid also has the function of a stabilizer, which can improve the stability of the system. Therefore, if itaconic acid is not added, the heat resistance and shear resistance will be affected; Comparative Example 6 uses different surfactants relative to Example 5. Different surfactants have different dispersing effects, which will affect the heat resistance and shear resistance; the drag reducer prepared by the present invention has significantly improved heat resistance and shear resistance compared to the product of Comparative Example 7, and the present invention has achieved significant progress.
[0083] Test Example 2 Salt resistance test
[0084] The drag reduction rate was measured and calculated according to the method specified in "SY / T 6376-2008 General Technical Conditions for Fracturing Fluids". The drag reduction rate was first tested in clean water, and then the drag reduction rate of the fracturing fluid drag reducer was tested in a 2wt% KCl solution to characterize the salt resistance. The drag reduction rate refers to the ratio of the friction resistance reduced when the fluid with the drag reducer is added to the original fluid without the drag reducer when flowing under the same conditions. The drag reduction rate reflects the ability of the drag reducer to reduce the flow resistance of the fluid. A higher drag reduction rate means smoother flow of the fluid in the pipeline and higher transportation efficiency. Salt resistance refers to the ability of the drag reducer to maintain its performance at different salt concentrations. In applications such as oil well fracturing, the fluid usually contains a high concentration of salt. Therefore, salt resistance is a key indicator for evaluating the performance of the drag reducer. In high-salinity environments, drag reducers with good salt resistance can maintain stable performance and ensure the flow efficiency of the fluid under complex geological conditions.
[0085] The data obtained by testing the drag reducers prepared in Examples 3-6 and Comparative Examples 3-7 are shown in Table 2:
[0086] Table 2 shows the drag reduction rate data of Examples 3-6 and Comparative Examples 3-7
[0087]
[0088] The data of drag reduction rates of the above-mentioned Examples 3-6 and Comparative Examples 3-7 show that the drag reduction rate of the products of Examples 3-7 is higher than that of Comparative Examples 3-6; Comparative Example 3, relative to Example 5, uses modified carbonized bacterial cellulose prepared by different carbonization methods, and the drag reduction rate in clean water and 2wt% KCl solution is significantly lower than that of Example 5, because different carbonization methods will affect the special structure of bacterial cellulose. The carbonization method of Comparative Example 1 damages the structure of bacterial cellulose, affecting mechanical properties, temperature resistance and other properties, while the carbonization method of Example 1 ensures that the carbonized bacterial cellulose has a more complete structure, resulting in better drag reduction effect and better salt resistance; Comparative Example 4, relative to Example 5, does not use modified carbonized bacterial cellulose, and its drag reduction rate drops significantly, and the bacterial cellulose has a greater impact on the drag reduction rate; Comparative Example 5 replaces The drag reduction rate decreases when itaconic acid is added, because itaconic acid has the effect of stabilizer. Itaconic acid can increase the water solubility of the polymer, improve the dispersibility, and is more conducive to improving the drag reduction effect. The drag reduction rate of the drag reducer in clear water is quite different from that in 2wt% KCl solution, because itaconic acid can combine with calcium, magnesium and other metal ions to improve salt resistance and has a good scale inhibition effect; Comparative Example 6 uses sorbitol polyoxyethylene ether as a surfactant relative to Example 5. The drag reduction effect of Comparative Example 6 is significantly lower than that of Example 5, which can effectively prove that the composite surfactant used in the present invention and the single surfactant have better dispersing effect than sorbitol polyoxyethylene ether, and are more conducive to improving salt resistance; the drag reducer prepared by the present invention has significantly improved drag reduction efficiency compared with the product with low ratio 7, and the drag reduction effect is very little affected by the high concentration KCl solution, and has a very good salt resistance effect.
[0089] Test Example 3
[0090] With reference to the standard SY / T 7627-2021 "Technical Requirements for Water-Based Fracturing Fluids", the damage rates of the drag reducers prepared in Examples 3-6 of the present invention and Comparative Examples 3-7 on the cores were tested respectively. The results are shown in Table 3 below.
[0091] Table 3 Test data of Examples 3-6 and Comparative Examples 3-7
[0092]
[0093] From the above data, it can be clearly seen that the drag reducer prepared by the present invention greatly reduces the damage to the core, promotes environmental protection, and reduces environmental pollution compared with the drag reducers of Comparative Examples 3-7.
[0094] The present invention provides a drag reducer for shale oil fracturing and a preparation method thereof. The drag reducer effectively improves the drag reduction effect and stability of the drag reducer by introducing bacterial cellulose and itaconic acid. The drag reducer still has a good drag reduction effect under high temperature, high salt and high shear rate conditions, has excellent high temperature resistance, salt resistance and shear resistance, is pollution-free and environmentally friendly. By utilizing the combination of bacterial cellulose and itaconic acid, the scale inhibition, cleaning and antibacterial effects are greatly improved, environmental pollution is reduced, and damage to the core is reduced.
[0095] In this specification, references to the same or similar parts between the various embodiments can be made to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.
[0096] The foregoing is merely an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the present application.
Claims
1. A clean drag reducer for fracturing, characterized in that: The raw materials include, by weight, 1-10 parts of carbonized bacterial cellulose, 30-40 parts of acrylamide, 20-35 parts of itaconic acid, 0.1-0.4 parts of initiator, 1-3 parts of surfactant, and 50-70 parts of deionized water; The surfactant is one or more of sodium α-olefin sulfonate, dodecyl dimethyl betaine, and lauryl amide propyl betaine; The preparation method of the carbonized bacterial cellulose is as follows: (1) freeze-drying the bacterial cellulose dispersion to obtain freeze-dried bacterial cellulose; (2) carbonizing the freeze-dried bacterial cellulose in an inert atmosphere to obtain carbonized bacterial cellulose; The bacterial cellulose dispersion has a solid content of 1 to 20%, a diameter of 50 to 100 nm, and a length of less than 50 μm; The freezing temperature is -60~0°C, the heating rate of the carbonization treatment is 3~8°C, the insulation temperatures are 200~300°C, 400~600°C and 800~1000°C, and the corresponding insulation time is 30min~3h.
2. A clean drag reducer for fracturing according to claim 1, characterized in that: The carbonized bacterial cellulose is used after being activated and modified. The specific method is as follows: adding the carbonized bacterial cellulose to a mixed solution of sulfuric acid and hydrogen peroxide, activating it for a period of time, immersing the activated carbonized bacterial cellulose in a silane coupling agent solution, stirring it, then taking it out, and curing it to obtain modified carbonized bacterial cellulose.
3. A clean drag reducer for fracturing according to claim 2, characterized in that: The sulfuric acid is 30-40wt% and the hydrogen peroxide is 15-20wt%, and the mixture is activated at 95-105°C for 1-1.5h.
4. The clean drag reducer for fracturing according to claim 2, characterized in that: The silane coupling agent is a silane coupling agent containing an unsaturated double bond, the mass ratio of carbonized bacterial cellulose to the silane coupling agent solution is 10-20:100, and the mass fraction of the silane coupling agent solution is 20-30%.
5. The clean drag reducer for fracturing according to claim 2, characterized in that: The stirring condition is: stirring at room temperature for 70-100 minutes; the curing condition is: curing at 50-80° C. for 3-12 hours.
6. The clean drag reducer for fracturing according to claim 1, characterized in that: The initiator is one of azobiscyclohexylcarbonitrile and azobisisoheptanenitrile.
7. The method for preparing a clean drag reducer for fracturing according to any one of claims 1 to 6, characterized in that: The specific preparation steps are as follows: acrylamide, itaconic acid and water are mixed and stirred, carbonized bacterial cellulose, a surfactant and an initiator are added, and the mixture is heated and stirred for 10-30 minutes to obtain a drag reducer.