Sophorolipid composition for slickwater fracturing fluid as well as preparation method and application of sophorolipid composition

Abstract

The invention discloses a sophorolipid composition for a slickwater fracturing fluid as well as a preparation method and application of the sophorolipid composition, and relates to the technical field of slickwater fracturing fluids. The main component of the sophorolipid composition for the slick water fracturing fluid is sophorolipid produced by fermentation of Candida bombycla, and the sophorolipid composition also comprises a thickening agent, a drag reducer and a clay stabilizer. The slick water fracturing fluid is simple in preparation method and low in use cost, main active ingredients are biologically sourced, and drag reduction, temperature and salt resistance, emulsifying activity and environmental protection requirements are considered, so that the drag reduction rate is increased, the recovery efficiency is increased, and the slick water fracturing fluid has a wide application prospect in oil field hydraulic fracturing.

Description

Technical Field

[0001] This invention relates to the field of slickwater fracturing fluid technology, specifically to a sophorolipid composition for slickwater fracturing fluid, its preparation method, and its application. Background Technology

[0002] The recoverable reserves of traditional oil and gas resources are gradually decreasing, and the extraction difficulty is constantly increasing. my country is rich in unconventional oil and gas resources, represented by shale oil and gas. It is predicted that after 2050, unconventional oil and gas will become my country's most strategic and realistic alternative resources. With the growth of energy demand, strengthening the development of unconventional oil and gas resources is of great significance for stabilizing the energy supply base and ensuring energy security.

[0003] Compared to conventional oil reservoirs, unconventional oil and gas reservoirs are characterized by low permeability, low porosity, and complex geological structures, making them difficult to effectively exploit using conventional techniques. To improve recovery rates, fracturing technology has become one of the key technologies for developing unconventional oil and gas fields. The basic principle of fracturing technology is to inject fracturing fluid into the oil and gas reservoir under high pressure. This fracturing alters the reservoir, causing the reservoir rock to fracture and form a fracture network, increasing the flow channels for oil and gas, improving permeability, and thus increasing the efficiency of oil and gas resource extraction. For fracturing operations, fracturing fluid is crucial for successful fracturing. Water-based fracturing fluids dominate the fracturing fluid system. Currently, guar gum fracturing fluid systems are commonly used in hydraulic fracturing. However, guar gum systems suffer from complex construction processes, long preparation times, and problems such as raw material waste and incomplete gel breaking during preparation.

[0004] Slippery water fracturing fluid is a novel fracturing fluid system used for hydraulic fracturing of unconventional oil and gas reservoirs. Compared to traditional fracturing fluids, slippery water fracturing fluid has a lower viscosity, which helps reduce frictional losses during fluid injection and equipment wear, and also facilitates efficient fluid transport. Slippery water fracturing fluid operations are typically large-scale, high-volume, and high-displacement operations, requiring not only low pump friction but also low cost and environmental friendliness. Slippery water fracturing fluid systems are over 97% water, with chemical additives primarily consisting of drag reducers, bactericides, clay stabilizers, and surfactants. Polyacrylamide, due to its low price and good drag-reducing effect, has become the mainstream drag reducer for slippery water fracturing both domestically and internationally. However, polyacrylamide-treated slippery water has poor salt resistance, leading to unstable fracturing performance and difficulty in ensuring good enhanced oil recovery. Furthermore, polyacrylamide poses significant environmental hazards, hindering the green development of oilfields. Using biodegradable agents to replace or reduce the use of chemical additives can reduce the environmental impact of slickwater fracturing fluid.

[0005] Currently, slickwater fracturing fluids are limited by factors such as drag reduction, temperature and salt resistance, economic efficiency, and environmental requirements. There is a need to develop slickwater fracturing fluids that can balance drag reduction, temperature and salt resistance, and economic and environmental benefits. With technological advancements, it is crucial to develop more environmentally friendly and efficient additives to improve the performance of slickwater fracturing fluids while simultaneously enhancing their economic and environmental benefits.

[0006] Biosurfactants can alter reservoir properties, reduce oil / water interfacial tension, emulsify crude oil, and improve crude oil flowability within the reservoir. Research on the compounding of biosurfactants with other fracturing agents, exploring the organic integration of biosurfactants and fracturing technology, holds promise for achieving long-term stable production and enhanced oil recovery in oilfield development. Sophorolipids are glycolipid biosurfactants produced by yeast fermentation, boasting high yield and relatively low production costs. Compared to traditional chemical surfactants, sophorolipids offer advantages such as high activity, biodegradability, green production processes, and no secondary pollution after use, meeting the needs of green development in oilfields. This invention develops a sophorolipid composition for slickwater fracturing fluid based on sophorolipids produced by microbial fermentation, providing a novel slickwater fracturing fluid for hydraulic fracturing technology. Summary of the Invention

[0007] To overcome the aforementioned problems in the prior art, this invention provides a sophorolipid composition for slickwater fracturing fluid, its preparation method, and its application. This invention uses sophorolipid produced by microbial fermentation as the main active ingredient, adds environmentally friendly additives, and balances drag reduction, temperature and salt resistance, emulsifying activity, and environmental requirements to develop a sophorolipid composition for slickwater fracturing fluid. This slickwater fracturing fluid is easy to prepare, has a significant drag reduction effect, dissolves quickly, and exhibits good temperature and salt resistance stability.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A sophorolipid composition for use in slickwater fracturing fluid, with sophorolipid as the main active ingredient and a sophorolipid concentration ≥0.03wt%.

[0009] The sophorolipid is *Candida albicans* (a bumblebee fungus). Candida bombicola The product obtained from fermentation contains ≥80% lactone-type sophorolipids (16% acid-type sophorolipids and 84% lactone-type sophorolipids); the sophorolipid composition also contains thickeners, drag reducers and clay stabilizers.

[0010] The sophorolipid composition for slickwater fracturing fluid comprises the following raw materials in parts by weight: 0.03-0.3 wt% sophorolipid, 0.05-0.25 wt% thickener, 0.1-0.25 wt% drag reducer, 0.5-2.0 wt% clay stabilizer, and the remainder being water.

[0011] The sophorolipid composition used in slickwater fracturing fluid is in liquid form, with the pH adjusted to 7.5-9.5.

[0012] The sophorolipid composition for slickwater fracturing fluid is an aqueous solution containing sophorolipid, thickener, drag reducer and clay stabilizer, or a liquid prepared by adding thickener, drag reducer and clay stabilizer to sophorolipid fermentation supernatant, or a diluted solution of the above liquids.

[0013] The thickener in the sophorolipin composition for slickwater fracturing fluid is one or more of xanthan gum, sodium carboxymethyl cellulose, and sodium alginate.

[0014] The drag-reducing agent in the sophorolipid composition for slickwater fracturing fluid is one or more of sodium dodecylbenzenesulfonate, polyethylene oxide, and Tween 80.

[0015] The clay stabilizer in the sophorolipid composition for slickwater fracturing fluid is one or both of potassium chloride and ammonium chloride.

[0016] The sophorolipid composition used in slickwater fracturing fluid has a surface tension ≤30 mN / m and an interfacial tension ≤3 mN / m.

[0017] The sophorolipid composition for use in slickwater fracturing fluid has a viscosity of 15-50 mPa·s and a kinematic viscosity ≤10 mm⁻¹. 2 / s.

[0018] The drag reduction rate of the sophorolipid composition used in slickwater fracturing fluid is ≥60%.

[0019] This invention also discloses a method for preparing a sophorolipid composition for slickwater fracturing fluid, comprising the following steps: (1) Bumblebee Candida albicans ( Candida bombicola (1) Ferment to produce sophorolipids and obtain a sophorolipid-containing fermentation broth; (2) Remove insoluble substances such as bacteria and residual oil in the fermentation broth to obtain a sophorolipid fermentation supernatant; or after removing insoluble substances such as bacteria and residual oil from the fermentation broth, further remove impurities by acid precipitation and alkali dissolution treatment to obtain a sophorolipid extract; (3) Dilute the fermentation supernatant with water to the required sophorolipid concentration, add thickener, drag reducer and clay stabilizer according to the amount, stir to dissolve and mix, and prepare a sophorolipid composition; or take the sophorolipid extract, thickener, drag reducer and clay stabilizer according to the amount, add water, stir to dissolve and mix, and prepare a sophorolipid composition.

[0020] The present invention also discloses the application of the sophorolipid composition as a slickwater fracturing fluid in oilfield hydraulic fracturing.

[0021] The beneficial effects of this invention are as follows: The sophorolipid composition of this invention has a significant drag-reducing effect, a fast dissolution rate, and good temperature and salt stability. It can be used in slickwater fracturing fluid. It can be prepared with clean water or reservoir produced water, and can be prepared at room temperature or low temperature in winter. It has high production efficiency and meets the huge demand for fracturing fluid in fracturing operations.

[0022] Compared with other technologies, this invention features simple preparation, low concentration, low cost, and wide applicability. It balances drag reduction, temperature and salt resistance, emulsifying activity, and environmental requirements, thereby improving oil recovery while simultaneously increasing drag reduction. It has broad application prospects in hydraulic fracturing of oil reservoirs. Sophorolipids also possess natural antibacterial properties, preventing fracturing fluid spoilage and associated economic losses due to microbial contamination. The sophorolipid composition for slickwater fracturing fluids in this invention requires no additional bactericides. Detailed Implementation

[0023] The present invention will be described in detail below with reference to specific embodiments to enable those skilled in the art to more fully understand the invention, but this does not limit the invention in any way. In the following embodiments, unless otherwise specified, the materials and reagents used can be purchased from biochemical reagent material companies.

[0024] Example 1: Fermentation production of sophorolipids Prepare liquid YM medium according to the following formula: 5 g / L peptone, 10 g / L glucose, 3 g / L malt extract, and 3 g / L yeast extract. Weigh the required reagents, dissolve them in distilled water, and adjust the pH to 6.2. Weigh the required reagents separately to prepare the fermentation medium for the production of sophorolipids. The fermentation medium formula is as follows: 100 g / L glucose, 100 g / L soybean oil, 5 g / L yeast extract, 2.5 g / L peptone, 1.5 g / L ammonium chloride, 0.5 g / L sodium chloride, 1.0 g / L potassium dihydrogen phosphate, 1.0 g / L magnesium sulfate heptahydrate, and 0.2 g / L calcium chloride dihydrate. Autoclave the dispensed YM medium and fermentation medium at 115℃ for 30 min. Allow the medium to cool to room temperature before use.

[0025] In this embodiment, the production strain used for fermentation to produce sophorolipids is *Candida bacillus* (bumblebee). Candida bombicola(ATCC 22214) Glycerol inoculum taken from a -80°C freezer was thawed at room temperature and inoculated into a 500 mL shake flask containing 150 mL of YM medium. The flask was incubated at 30°C and 200 rpm for 2 days to prepare a seed culture of *Candida bacillus*. The *Candida bacillus* seed culture was inoculated at a rate of 5% (v / v) into a 6 L fermenter containing 2.5 L of fermentation medium and incubated at 30°C, 500 rpm, and 1 vvm aeration for 8 days to produce sophorolipids. During fermentation, 20 g / L soybean oil and 20 g / L glucose were added on days 3 and 5. After fermentation, a fermentation broth containing sophorolipids was obtained.

[0026] Example 2: Treatment and extraction of sophorolipid fermentation broth The fermentation broth was filtered using filter paper to remove residual oils and other insoluble substances, and the filtrate was collected. The filtrate was centrifuged at 10,000 r / min for 10 min to remove the bacterial cells, obtaining the sophorolipid fermentation supernatant. The sophorolipid content in the supernatant was determined to be 85.0 ± 4.1 g / L using the anthrone-sulfuric acid method.

[0027] Dilute hydrochloric acid solution was added to the fermentation supernatant of sophorolipids to adjust the pH to 1.0, promoting the precipitation of sophorolipids and obtaining an acidified solution. The acidified solution was centrifuged at 10000 r / min for 10 min, and most of the upper liquid was discarded. Dilute sodium hydroxide solution was added to the precipitate to adjust the pH to 8.0, promoting the dissolution of sophorolipids and obtaining the sophorolipid extract. The sophorolipid content in the extract was determined to be 305.9 ± 3.2 g / L using the anthrone-sulfuric acid method. Liquid chromatography showed that the sophorolipids in the product were mainly lactone-type sophorolipids, and the ratio of acidic to lactone-type sophorolipids in the product was approximately 3:17 based on peak area integration.

[0028] Example 3: Preparation of Sophorolipid Composition This example prepares a sophorolipid composition for slickwater fracturing fluid, including the following steps: (1) Bumblebee Candida albicans ( Candida bombicola (1) Fermentation of ATCC 22214 to obtain a fermentation broth containing sophorolipids (Example 1); (2) Remove insoluble substances such as bacteria and residual oils from the fermentation broth to obtain a sophorolipid fermentation supernatant; (3) Dilute the fermentation supernatant with water to the required sophorolipid concentration, add thickener, drag reducer and clay stabilizer in the required amount, stir to dissolve and mix, and prepare a sophorolipid composition.

[0029] The supernatant from the sophorolipid fermentation in Example 2 was diluted with water to a final sophorolipid concentration of 1.0 g / L and a total volume of 1 L. Then, xanthan gum and polyethylene oxide were added to a final concentration of 1.2 g / L, and potassium chloride was added to a final concentration of 10 g / L. The mixture was stirred to dissolve and mix well to obtain a solution. The pH of the solution was then adjusted to 8.5 with dilute hydrochloric acid and dilute sodium hydroxide solution to obtain sophorolipid composition A for use in slickwater fracturing fluid.

[0030] The supernatant from the sophorolipid fermentation in Example 2 was diluted with water to a final concentration of 1.0 g / L and a total volume of 1 L. Then, xanthan gum, sodium carboxymethyl cellulose, and sodium alginate were added at a final concentration of 0.4 g / L, polyethylene oxide, sodium dodecylbenzene sulfonate, and Tween 80 were added at a final concentration of 0.4 g / L, and potassium chloride and ammonium chloride were added at a final concentration of 5 g / L. The mixture was stirred to dissolve and mix to obtain a solution. The pH of the solution was then adjusted to 8.5 with dilute hydrochloric acid and dilute sodium hydroxide solution to obtain sophorolipid composition B for use in slickwater fracturing fluid.

[0031] Example 4: Preparation of Sophorolipid Composition This example prepares a sophorolipid composition for slickwater fracturing fluid, including the following steps: (1) Bumblebee Candida albicans ( Candida bombicola (1) ATCC 22214 fermentation to obtain a fermentation broth containing sophorolipids (Example 1); (2) After removing insoluble substances such as bacteria and residual oil from the fermentation broth, further remove impurities by acid precipitation and alkali dissolution treatment to obtain sophorolipid extract; (3) Take the sophorolipid extract, thickener, drag reducer and clay stabilizer according to the amount, add water, stir to dissolve and mix to prepare sophorolipid composition.

[0032] The sophorolipid fermentation extract from Example 2 was measured at a dosage of 1.0 g. 1.2 g xanthan gum, 1.2 g polyethylene oxide, and 10 g potassium chloride were weighed and added to the same container. 1 L of water was added, and the mixture was stirred to dissolve and mix to obtain a solution. Then, the pH of the solution was adjusted to 8.5 with dilute hydrochloric acid and dilute sodium hydroxide solution to obtain sophorolipid composition C for use in slickwater fracturing fluid.

[0033] The sophorolipid fermentation extract from Example 2 was measured at a dosage of 1.0 g. 0.4 g each of xanthan gum, sodium carboxymethyl cellulose, and sodium alginate, 0.4 g each of polyethylene oxide, sodium dodecylbenzene sulfonate, and Tween 80, and 5 g each of potassium chloride and ammonium chloride were weighed. All these substances were added to the same container. 1 L of water was added, and the mixture was stirred to dissolve and mix, yielding a solution. The pH of the solution was then adjusted to 8.5 using dilute hydrochloric acid and dilute sodium hydroxide solution to obtain sophorolipid composition D for use in slickwater fracturing fluid.

[0034] Example 5 This embodiment evaluates the characteristics of different samples by testing their surface tension, interfacial tension, viscosity, kinematic viscosity, drag reduction rate, and emulsification index.

[0035] Take the fermentation supernatant of sophorolipid from Example 2, dilute it with water to 1 g / L, and adjust the pH to 8.5 to obtain sophorolipid solution CK1. Take the sophorolipid extract from Example 2, prepare a 1 g / L sophorolipid solution with water, and adjust the pH to 8.5 to obtain sophorolipid solution CK2.

[0036] Add xanthan gum to a final concentration of 1.2 g / L, add polyethylene oxide to a final concentration of 1.2 g / L, and add potassium chloride to a final concentration of 10 g / L; add water, stir to dissolve and mix well, and adjust the pH to 8.5 to obtain mixture solution Mix1. Add xanthan gum, sodium carboxymethyl cellulose, and sodium alginate to a final concentration of 0.4 g / L, add polyethylene oxide, sodium dodecylbenzene sulfonate, and Tween 80 to a final concentration of 0.4 g / L, and add potassium chloride and ammonium chloride to a final concentration of 5 g / L; add water, stir to dissolve and mix well, and adjust the pH to 8.5 to obtain mixture solution Mix2.

[0037] The samples used in this embodiment include the four sophorolipid compositions A, B, C and D prepared in Examples 3 and 4, as well as the sophorolipid solutions CK1 and CK2 and the mixed solutions Mix1 and Mix2.

[0038] The tension values ​​of eight samples were measured using a fully automated surface / interfacial tensiometer at a temperature of 28℃. Surface tension was measured using the platinum plate method and interfacial tension was measured using the platinum ring method. The results are shown in Table 1.

[0039] The viscosity of eight samples was determined using a rotational viscometer at 30℃. The kinematic viscosity of the eight samples was determined using a capillary viscometer with an inner diameter of 0.6 mm and a flow time ranging from 200 s to 500 s. A dry, clean capillary was used to draw in the samples, and the temperature was maintained at 25℃ for 15 min. The time taken for the lowest point of the sample's meniscus to pass through the upper and lower marks of the timing sphere was measured and recorded as t. The formula for calculating kinematic viscosity is: v =C t, where v This is the kinematic viscosity of the sample, in mm. 2 / s; C This is the capillary viscometer coefficient, in mm. 2 / s 2 t is the time it takes for the sample to flow through the upper and lower markings, in seconds. The results are shown in Table 1.

[0040] The drag reduction rate (DR) of eight samples was determined using a pipe friction analyzer. A liquid flowing through a pipe of a certain length and diameter at a certain velocity will generate a certain pressure difference. The drag reduction rate of the sample is calculated based on the difference between the sample and the pressure difference of clean water, and the ratio of the sample's pressure difference to the clean water pressure difference. The measurement method is as follows: Turn on the pipe friction analyzer, add the required amount of clean water to the storage tank, and slowly adjust the speed of the power pump to fill the entire test pipe with the test liquid. Start the system and circulate at low speed. Adjust the speed of the power pump to reach the set linear velocity of 10 mm / s. Read the pressure difference of the clean water at this linear velocity from the instrument. If the pressure difference changes by less than 1% within 1 minute, take the average value of the pressure difference within 1 minute as the clean water friction pressure difference. ΔP 0 Replace the water in the storage tank with the test sample. After the tube is completely filled with the test liquid, follow the same operating steps as the water test described above, and record the frictional pressure difference as the test sample passes through the test tube. ΔP 1 ). Drag reduction ratio DR=( ΔP 0 - ΔP 1 ) / ΔP 0 100%. The results are shown in Table 1.

[0041] Emulsification Index (EI) 24 The emulsifying activity of eight samples on crude oil was characterized. In this example, the crude oil used had a viscosity of 33.6 mPa·s and a density of 0.913 g / cm³. 3 Add 3 mL of sample to a 25 mL transparent colorimetric tube, then add 3 mL of crude oil. Vortex the tube for 2 min, allow it to stand at room temperature for 24 hours, and then measure the height (mm) of the oil and water phases. Record the data. Emulsification index (EI) 24 The value is equal to the oil phase height divided by the total phase height and then multiplied by 100%. The sophorolipid composition of this invention is a solution system and does not undergo emulsification itself, but it exhibits excellent emulsifying activity towards crude oil. The results are shown in Table 1.

[0042] Table 1: Parameter data for different samples The results in Table 1 show that the composition system prepared by adding sophorolipids, thickeners, drag reducers and clay stabilizers has better surface / interfacial activity, drag reduction effect and emulsifying activity compared with the liquid system containing only sophorolipids and the mixed solution system containing only thickeners, drag reducers and clay stabilizers.

[0043] The results show that the sophorolipid composition of the present invention used in slickwater fracturing fluid has a certain viscosity, which helps to improve the sand carrying capacity; it has a low surface / interfacial tension, which helps to reduce the resistance of the fracturing fluid system in the reservoir, thus facilitating the flowback of the fracturing fluid; it has excellent drag reduction effect and crude oil emulsification activity, which helps to develop hydraulic fracturing in oil reservoirs and improve oil recovery.

[0044] Example 6 In this embodiment, four sophorolipid compositions A, B, C, and D prepared in Examples 3 and 4 were used as test samples to evaluate their temperature and salt resistance.

[0045] Four sophorolipid compositions were heat-treated in an 80°C water bath for 1 hour. After cooling to room temperature, the interfacial tension and emulsification index of the samples were measured according to the method in Example 5. The results showed that the interfacial tension of the four sophorolipid compositions A, B, C, and D was still less than 3 mN / m, and the emulsification index of crude oil was still greater than 80%. This indicates that the sophorolipid compositions of the present invention have good temperature resistance.

[0046] Sodium chloride was added to the four sophorolipid compositions until the final sodium chloride concentration was 100 g / L. The mixture was stirred to dissolve and allowed to stand at room temperature for 1 hour. The interfacial tension and emulsification index of the samples were then measured according to the method in Example 5. The results showed that the interfacial tension of the four sophorolipid compositions A, B, C, and D remained less than 3 mN / m, and the emulsification index for crude oil remained greater than 80%. This indicates that the sophorolipid compositions of the present invention have good salt resistance.

[0047] This invention develops a sophorolipid composition for use in slickwater fracturing fluids, using sophorolipids produced by microbial fermentation as the main active ingredient. Compared with other technologies, the sophorolipid composition of this invention is simple to prepare, economical, and environmentally friendly, taking into account drag reduction, temperature and salt resistance, emulsifying activity, and environmental protection requirements. It helps to improve oil recovery while increasing drag reduction, and has application value in hydraulic fracturing development of oil reservoirs.

Claims

1. A sophorolipid composition for use in slickwater fracturing fluid, characterized in that: The main active ingredient of the composition is sophorolipid, with a sophorolipid concentration ≥0.03wt%; the sophorolipid is derived from *Candida albicans* (a bumblebee yeast). Candida bombicola The product obtained from fermentation contains ≥80% lactone-type sophorolipids (16% acid-type sophorolipids and 84% lactone-type sophorolipids); the sophorolipid composition also contains thickeners, drag reducers and clay stabilizers.

2. The sophorolipid composition for slickwater fracturing fluid according to claim 1, characterized in that, The raw material composition includes the following parts by weight: 0.05~0.3wt% sophorolipid, 0.05~0.25wt% thickener, 0.1~0.25wt% drag reducer, 0.5~2.0wt% clay stabilizer, and the remainder is water.

3. The sophorolipid composition for slickwater fracturing fluid according to claim 1, characterized in that: The composition is in liquid form, and the pH value is adjusted to 7.5~9.

5.

4. The sophorolipid composition for slickwater fracturing fluid according to claims 1-3, characterized in that: The composition is an aqueous solution containing sophorolipid, thickener, drag reducer and clay stabilizer, or a liquid prepared by adding thickener, drag reducer and clay stabilizer to sophorolipid fermentation supernatant, or a diluted solution of the above liquid.

5. The sophorolipid composition for slickwater fracturing fluid according to claims 1-2, characterized in that: The thickener in the composition is one or more of xanthan gum, sodium carboxymethyl cellulose, and sodium alginate.

6. The sophorolipid composition for slickwater fracturing fluid according to claims 1-2, characterized in that: The drag-reducing agent in the composition is one or more of sodium dodecylbenzenesulfonate, polyethylene oxide, and Tween 80.

7. The sophorolipid composition for slickwater fracturing fluid according to claims 1-2, characterized in that: The clay stabilizer in the composition is one or both of potassium chloride and ammonium chloride.

8. The sophorolipid composition for slickwater fracturing fluid according to claim 2, characterized in that: The surface tension of the composition is ≤30 mN / m and the interfacial tension is ≤3 mN / m.

9. The sophorolipid composition for slickwater fracturing fluid according to claim 2, characterized in that: The viscosity of the composition is 15~50 mPa·s, and the kinematic viscosity is ≤10 mm. 2 / s.

10. The sophorolipid composition for slickwater fracturing fluid according to claim 2, characterized in that: The drag reduction rate of the composition is ≥60%.

11. The method for preparing the sophorolipid composition for slickwater fracturing fluid according to claims 1-4, characterized in that, Includes the following steps: (1) Bumblebee Candida albicans ( Candida bombicola (1) Ferment to produce sophorolipids and obtain a sophorolipid-containing fermentation broth; (2) Remove insoluble substances such as bacteria and residual oil in the fermentation broth to obtain a sophorolipid fermentation supernatant; or after removing insoluble substances such as bacteria and residual oil from the fermentation broth, further remove impurities by acid precipitation and alkali dissolution treatment to obtain a sophorolipid extract; (3) Dilute the fermentation supernatant with water to the required sophorolipid concentration, add thickener, drag reducer and clay stabilizer according to the amount, stir to dissolve and mix, and prepare a sophorolipid composition; or take the sophorolipid extract, thickener, drag reducer and clay stabilizer according to the amount, add water, stir to dissolve and mix, and prepare a sophorolipid composition.

12. The application of the sophorolipid composition according to claim 1 as a slickwater fracturing fluid in oilfield hydraulic fracturing.

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