A shale oil breaker and its preparation process

Abstract

The present invention relates to the field of petrochemical technology, and discloses a shale oil breaker and a preparation process thereof. The present invention reacts cellulose with bis[4-(2-formyl chloride benzamide) phenoxy] dimethylsilane, etc., and cross-links cellulose gel with organosilicon, then adsorbs and coats ammonium persulfate, and freeze-dries to obtain a microcapsule sustained-release breaker with cellulose aerogel as a capsule wall and ammonium persulfate as a capsule core. The present invention introduces siloxane and a benzene ring structure into a cellulose matrix, improves the thermal decomposition temperature and water contact angle of the cellulose gel, has good water-proof and high temperature resistance, can avoid the microcapsule breaker from rapidly dissolving and releasing ammonium persulfate when encountering water, is conducive to achieving the effect of slowly releasing the ammonium persulfate breaker, and simultaneously the high temperature resistance can meet the application of the microcapsule breaker in a high-temperature fracturing fluid system.

Description

Technical Field

[0001] The present invention relates to the technical field of petrochemical industry, in particular to a gel breaker for shale oil and a preparation process thereof. Background Art

[0002] Fracturing technology is an effective method for increasing shale oil production. Guar gum jelly fracturing fluid is a common fracturing fluid used in shale oil production. During actual reservoir development, gel fracturing fluids require the addition of breakers such as ammonium persulfate. This degrades the jelly structure of the fracturing fluid, reducing its viscosity and enhancing fluidity. This facilitates post-fracture flowback and reduces reservoir damage. If the ammonium persulfate breaker dosage is too low, the breaking effect is poor within a short period of time. However, if the dosage is too high, the fracturing fluid jelly breaks rapidly, causing a rapid decrease in viscosity and impairing the fluid's sand-carrying capacity.

[0003] Using a capsule wall to coat ammonium persulfate to produce a microcapsule-type sustained-release breaker can effectively solve the above problems. Common capsule wall materials include paraffin, vinyl copolymers, aerogels, etc., which are required to have good water-proofing, heat resistance, and sustained-release properties. Chinese patent CN112852401B discloses a highly suspended and dispersible capsule breaker and its preparation method. The persulfate capsule breaker prepared using thiophene or aniline as the shell membrane material and an organic bentonite suspending agent has good suspension and dispersibility. However, the capsule breaker in this patent does not improve water-proofing, heat resistance, and other properties, nor does it improve the sustained-release breaking performance of the breaker. Summary of the Invention

[0004] The invention solves the problems of poor waterproof, water-isolating and heat-resistant properties and poor breaking performance of existing microcapsule breakers.

[0005] Technical solution: A process for preparing a shale oil breaker, comprising:

[0006] S1: Add cellulose to a sodium hydroxide aqueous solution, heat and stir, filter, wash with deionized water, and dry; then add cellulose to N,N-dimethylacetamide, stir, and then add pyridine, bis[4-(2-chlorobenzamide)phenoxy]dimethylsilane, and 1,4-dioxane as a cosolvent in a nitrogen atmosphere, and control the mass ratio of cellulose, pyridine, and bis[4-(2-chlorobenzamide)phenoxy]dimethylsilane to be 100:(150-350):(230-520); stir the reaction, filter, wash with deionized water, ethanol, and dichloromethane in sequence, and dry to obtain a silicone cross-linked cellulose gel.

[0007] S2: adding organosilicon cross-linked cellulose gel to an aqueous solution of ammonium persulfate having a mass concentration of (100-400) g / L, stirring, freezing the solution with liquid nitrogen, and then freeze-drying it in a freeze dryer, washing it with water, and then drying it to obtain a gel breaker for shale oil.

[0008] The mass fraction of the sodium hydroxide aqueous solution in S1 is 20-40%.

[0009] The temperature during heating and stirring in S1 is 30-40° C. and the time is 1-2 h; the temperature during stirring reaction is 15-30° C. and the time is 3-6 h.

[0010] The volume ratio of N,N-dimethylacetamide to 1,4-dioxane in S1 is 100:(30-50).

[0011] The ratio of the ammonium persulfate aqueous solution to the organosilicon cross-linked cellulose gel in S2 is 1L: (3-10) g.

[0012] The stirring temperature in S2 is 15-40°C and the stirring time is 12-18 hours; the freeze-drying temperature is -50°C to -60°C and the freezing time is 48-72 hours.

[0013] Wherein, the preparation process of bis[4-(2-chloroformylbenzamide)phenoxy]dimethylsilane is as follows:

[0014] (1) Add bis(4-aminophenoxy)dimethylsilane and phthalic anhydride to N,N-dimethylacetamide, stir and react at 15-30℃ for 12-18h, add deionized water to dilute, extract with dichloromethane, distill the organic phase under reduced pressure, wash with acetone, and dry. Add the product to thionyl chloride, controlling the molar ratio of bis(4-aminophenoxy)dimethylsilane, phthalic anhydride, and thionyl chloride to be 1:(2-2.2):(12-16); condense and reflux at 65-75℃ for 4-6h, distill under reduced pressure, and dry to obtain bis[4-(2-chlorobenzylamino)phenoxy]dimethylsilane. The reaction formula is:

[0015] .

[0016] The beneficial technical effects of the present invention are as follows: the present invention utilizes the acyl chloride group of bis[4-(2-chloroformylbenzamide)phenoxy]dimethylsilane to react with cellulose to generate a cellulose cross-linked gel, which is then adsorbed and coated with ammonium persulfate, and finally freeze-dried to obtain a microcapsule sustained-release gel breaker with the cellulose aerogel as the capsule wall and the ammonium persulfate as the capsule core.

[0017] The bis[4-(2-chloroformylbenzamide)phenoxy]dimethylsilane of the present invention contains heat-resistant, hydrophobic siloxane and a multi-phenyl ring structure. After undergoing an esterification cross-linking reaction with cellulose, the siloxane and benzene ring structure are introduced into the cellulose matrix, significantly increasing the thermal decomposition temperature and water contact angle of the cellulose gel. The bis[4-(2-chloroformylbenzamide)phenoxy]dimethylsilane has excellent water-insulating and high-temperature resistance, preventing the microcapsule breaker from rapidly dissolving and releasing ammonium persulfate upon contact with water, thereby facilitating the slow release of the ammonium persulfate breaker. Furthermore, the high-temperature resistance satisfies the microcapsule breaker's application in high-temperature fracturing fluid systems.

[0018] The present invention adds a gel breaker to the water-based gel fracturing fluid. After a long period of shearing, the fracturing fluid still maintains a relatively high viscosity, has a good slow-release gel-breaking effect, and is conducive to overcoming the problem that the viscosity of the gel fracturing fluid drops rapidly after gel breaking, resulting in poor sand carrying capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the infrared spectrum of bis[4-(2-chloroformylbenzamide)phenoxy]dimethylsilane.

[0020] Figure 2 This is the infrared spectrum of silicone cross-linked cellulose gel. DETAILED DESCRIPTION

[0021] The embodiments described below are only some of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0022] The following celluloses, with an effective substance content of 99%, were purchased from Jinan Hongyu Chemical Co., Ltd. Hydroxypropyl guar gum, with an effective substance content of 99%, was purchased from Shandong Guangpu Biotechnology Co., Ltd. Drainage aid model LX-2009 was purchased from Shaanxi Lanxin Chemical Co., Ltd. Organoboron crosslinker model DB-2000 was purchased from Shaanxi Lanxin Chemical Co., Ltd.

[0023] Example 1

[0024] (1) Add 30 mmol of bis(4-aminophenoxy)dimethylsilane and 60 mmol of phthalic anhydride to 80 mL of N,N-dimethylacetamide, stir and react at 30°C for 12 h, add 200 mL of deionized water to dilute, extract with dichloromethane, distill the organic phase under reduced pressure, wash with acetone, and dry. Add the product to 360 mmol of thionyl chloride, condense and reflux at 75°C for 5 h, distill under reduced pressure, and dry to obtain bis[4-(2-chloroformylbenzamide)phenoxy]dimethylsilane. Figure 1 In the infrared spectrum, 2930 cm -1It is the stretching vibration peak of methyl CH in Si-CH3 of bis[4-(2-chloroformylbenzamide)phenoxy]dimethylsilane, 1050 cm -1 It is the characteristic peak of Si-O-Si. 1789cm -1 It is the absorption peak of the acyl chloride group C=O, 1685cm -1 It is the absorption peak of amide bond C=O.

[0025] (2) Add 2 g of cellulose to 120 mL of 40% sodium hydroxide aqueous solution, heat to 30 °C, stir for 2 h, filter, wash with deionized water, and dry; then add cellulose to 60 mL of N,N-dimethylacetamide, stir, and then add 4.2 g of pyridine, 6.5 g of bis[4-(2-formylchlorobenzamide)phenoxy]dimethylsilane, and 25 mL of 1,4-dioxane cosolvent in a nitrogen atmosphere. Stir and react at 15 °C for 6 h, filter, wash with deionized water, ethanol, and dichloromethane in sequence, and dry to obtain silicone cross-linked cellulose gel. Figure 2 Medium 1633cm -1 It is the absorption peak of ester group C=O, and the absorption peak of acyl chloride group C=O is 1789cm -1 The hydroxyl group of cellulose and the acyl chloride group of bis[4-(2-chloroformylbenzamide)phenoxy]dimethylsilane undergo esterification to form ester groups. -1 The stretching vibration peak of the methyl CH in Si-CH3 is 1041 cm -1 It is the characteristic peak of Si-O-Si, 1698cm -1 It is the absorption peak of amide bond C=O, indicating that bis[4-(2-chloroformylbenzamide)phenoxy]dimethylsilane is grafted into the cellulose matrix.

[0026] (3) 0.3 g of organosilicon cross-linked cellulose gel was added to 100 mL of an aqueous solution of ammonium persulfate with a mass concentration of 100 g / L, and the mixture was stirred at 25 °C for 12 h. The solution was frozen with liquid nitrogen and then freeze-dried in a freeze dryer at -50 °C for 72 h. The mixture was washed with water and dried to obtain a shale oil breaker.

[0027] Example 2

[0028] (1) Add 30 mmol of bis(4-aminophenoxy)dimethylsilane and 66 mmol of phthalic anhydride to 100 mL of N,N-dimethylacetamide, stir and react at 25°C for 18 h, add 200 mL of deionized water to dilute, extract with dichloromethane, distill the organic phase under reduced pressure, wash with acetone, and dry. Add the product to 480 mmol of thionyl chloride, condense and reflux at 65°C for 6 h, distill under reduced pressure, and dry to obtain bis[4-(2-chloroformylbenzamide)phenoxy]dimethylsilane.

[0029] (2) Add 2 g of cellulose to 150 mL of a 30% sodium hydroxide aqueous solution, heat to 30°C, stir for 2 h, filter, wash with deionized water, and dry; then add the cellulose to 60 mL of N,N-dimethylacetamide, stir, and then add 7 g of pyridine, 10.4 g of bis[4-(2-formylchlorobenzamide)phenoxy]dimethylsilane (prepared in Example 1), and 30 mL of 1,4-dioxane cosolvent in a nitrogen atmosphere. Stir and react at 20°C for 6 h, filter, wash with deionized water, ethanol, and dichloromethane in sequence, and dry to obtain a silicone cross-linked cellulose gel.

[0030] (3) 0.5 g of organosilicon cross-linked cellulose gel was added to 100 mL of an aqueous solution of ammonium persulfate with a mass concentration of 200 g / L, and the mixture was stirred at 40 °C for 12 h. The solution was frozen with liquid nitrogen and then freeze-dried in a freeze dryer at -60 °C for 48 h. The mixture was washed with water and dried to obtain a shale oil breaker.

[0031] Example 3

[0032] (1) Add 30 mmol of bis(4-aminophenoxy)dimethylsilane and 66 mmol of phthalic anhydride to 100 mL of N,N-dimethylacetamide, stir and react at 15°C for 18 h, add 200 mL of deionized water to dilute, extract with dichloromethane, distill the organic phase under reduced pressure, wash with acetone, and dry. Add the product to 420 mmol of thionyl chloride, condense and reflux at 75°C for 4 h, distill under reduced pressure, and dry to obtain bis[4-(2-chloroformylbenzamide)phenoxy]dimethylsilane.

[0033] (2) Add 2 g of cellulose to 12 mL of 30% sodium hydroxide aqueous solution, heat to 30 ° C, stir for 2 h, filter, wash with deionized water, and dry; then add cellulose to 60 mL of N, N-dimethylacetamide, stir, and then add 3 g of pyridine, 4.6 g of bis[4-(2-formylchlorobenzamide)phenoxy]dimethylsilane, and 18 mL of 1,4-dioxane cosolvent in a nitrogen atmosphere. Stir and react at 20 ° C for 4 h, filter, wash with deionized water, ethanol, and dichloromethane in sequence, and dry to obtain silicone cross-linked cellulose gel.

[0034] (3) 0.75 g of organosilicon cross-linked cellulose gel was added to 100 mL of an aqueous solution of ammonium persulfate with a mass concentration of 300 g / L, and the mixture was stirred at 15 °C for 18 h. The solution was frozen with liquid nitrogen and then freeze-dried in a freeze dryer at -50 °C for 72 h. The mixture was washed with water and dried to obtain a shale oil breaker.

[0035] Example 4

[0036] (1) Add 2 g of cellulose to 150 mL of 20% sodium hydroxide aqueous solution, heat to 40 °C, stir for 1 h, filter, wash with deionized water, and dry; then add cellulose to 60 mL of N,N-dimethylacetamide, stir, and then add 5.6 g of pyridine, 8.6 g of bis[4-(2-formylchlorobenzamide)phenoxy]dimethylsilane, and 30 mL of 1,4-dioxane cosolvent in a nitrogen atmosphere. Stir and react at 30 °C for 4 h, filter, wash with deionized water, ethanol, and dichloromethane in sequence, and dry to obtain silicone cross-linked cellulose gel.

[0037] (2) Add 1 g of organosilicon cross-linked cellulose gel to 100 mL of an aqueous solution of ammonium persulfate with a mass concentration of 400 g / L, stir at 30 °C for 18 h, freeze the solution with liquid nitrogen, and then freeze-dry it in a freeze dryer at -50 °C for 72 h. Wash with water and then dry to obtain a shale oil breaker.

[0038] Comparative Example 1

[0039] (2) Add 2 g of cellulose to 120 mL of 40% sodium hydroxide aqueous solution, heat to 30 °C, stir for 2 h, filter, wash with deionized water, and dry; then add cellulose to 60 mL of N,N-dimethylacetamide, stir, and then add 4.2 g of pyridine, 6.5 g of adipic acid chloride, and 25 mL of 1,4-dioxane cosolvent in a nitrogen atmosphere. Stir and react at 15 °C for 6 h, filter, wash with deionized water, ethanol, and dichloromethane in sequence, and dry to obtain a cross-linked cellulose gel.

[0040] (3) 0.3 g of cross-linked cellulose gel was added to 100 mL of an aqueous solution of ammonium persulfate with a mass concentration of 100 g / L, and the mixture was stirred at 25 °C for 12 h. The solution was frozen with liquid nitrogen and then freeze-dried in a freeze dryer at -50 °C for 72 h. The mixture was washed with water and dried to obtain a shale oil breaker.

[0041] Comparative Example 2

[0042] (1) Add 30 mmol of 4,4-diaminodiphenyl ether and 60 mmol of phthalic anhydride to 80 mL of N,N-dimethylacetamide, stir and react at 30°C for 12 hours, add 200 mL of deionized water to dilute, extract with dichloromethane, distill the organic phase under reduced pressure, wash with acetone, and dry. Add the product to 360 mmol of thionyl chloride, condense and reflux at 75°C for 5 hours, distill under reduced pressure, and dry to obtain 4,4-bis(2-chlorobenzamide). The structural formula is .

[0043] (2) Add 2 g of cellulose to 120 mL of 40% sodium hydroxide aqueous solution, heat to 30 °C, stir for 2 h, filter, wash with deionized water, and dry; then add cellulose to 60 mL of N,N-dimethylacetamide, stir, and then add 4.2 g of pyridine, 6.5 g of 4,4-bis(2-formylchlorobenzamide)diphenyl ether, and 25 mL of 1,4-dioxane cosolvent in a nitrogen atmosphere. Stir and react at 15 °C for 6 h, filter, wash with deionized water, ethanol, and dichloromethane in sequence, and dry to obtain a cross-linked cellulose gel.

[0044] (3) 0.3 g of cross-linked cellulose gel was added to 100 mL of an aqueous solution of ammonium persulfate with a mass concentration of 100 g / L, and the mixture was stirred at 25 °C for 12 h. The solution was frozen with liquid nitrogen and then freeze-dried in a freeze dryer at -50 °C for 72 h. The mixture was washed with water and dried to obtain a shale oil breaker.

[0045] Comparative Example 3

[0046] (1) Add 30 mmol of 1.3-bis(3-carboxylpropyl)tetramethyldisiloxane to 360 mmol of thionyl chloride, reflux under condensation at 75°C for 5 h, distill under reduced pressure, and dry to obtain 1.3-bis(3-acyl chloride propyl)tetramethyldisiloxane. The structural formula is .

[0047] (2) Add 2 g of cellulose to 120 mL of 40% sodium hydroxide aqueous solution, heat to 30 °C, stir for 2 h, filter, wash with deionized water, and dry; then add cellulose to 60 mL of N,N-dimethylacetamide, stir, and then add 4.2 g of pyridine, 6.5 g of 1.3-bis(3-chloropropyl)tetramethyldisiloxane, and 25 mL of 1,4-dioxane as a cosolvent in a nitrogen atmosphere. Stir and react at 15 °C for 6 h, filter, wash with deionized water, ethanol, and dichloromethane in sequence, and dry to obtain a cross-linked cellulose gel.

[0048] (3) 0.3 g of cross-linked cellulose gel was added to 100 mL of an aqueous solution of ammonium persulfate with a mass concentration of 100 g / L, and the mixture was stirred at 25 °C for 12 h. The solution was frozen with liquid nitrogen and then freeze-dried in a freeze dryer at -50 °C for 72 h. The mixture was washed with water and dried to obtain a shale oil breaker.

[0049] Thermogravimetric analysis of the cellulose gel was performed using a thermogravimetric analyzer. Nitrogen atmosphere was used as the test atmosphere, the heating rate was 10°C / min, and the temperature range was 25-700°C.

[0050] The water contact angle of cellulose gel was measured using a contact angle meter. Deionized water was added to the gel surface through a syringe, and the water contact angles at 5 different positions were measured and the average value was taken.

[0051] Table 1 Cellulose gel performance test

[0052] Temperature at which mass loss is 5% (°C) Water contact angle (°) Example 1 258.7 98.6 Example 2 269.1 113.5 Example 3 254.0 92.3 Example 4 263.8 107.9 Comparative Example 1 236.4 76.7 Comparative Example 2 251.3 84.6 Comparative Example 3 244.9 87.2

[0053] After testing, the thermal decomposition temperature and water contact angle of the organosilicon cross-linked cellulose gel of Examples 1-4 are higher, and have better high temperature resistance and hydrophobic water-isolating properties. This is mainly because bis[4-(2-chloroformylbenzamide)phenoxy]dimethylsilane contains heat-resistant, hydrophobic siloxane and multi-phenyl ring structure. After esterification and cross-linking reaction with cellulose, the siloxane and benzene ring structure are introduced into the cellulose matrix, which significantly improves the thermal decomposition temperature and water contact angle of the cellulose gel, can meet the requirements of microcapsule breaker for water resistance, water isolation, high temperature resistance and other properties, and is conducive to achieving the effect of slowly releasing ammonium persulfate breaker.

[0054] The adipoyl chloride of Comparative Example 1 lacks the heat-resistant, hydrophobic siloxane and benzene ring structures. After esterification and cross-linking with cellulose, the resulting cellulose gel has a low thermal decomposition temperature and water contact angle, resulting in poor heat resistance and hydrophobic water barrier properties. The 4,4-bis(2-formylchlorobenzamide)diphenyl ether of Comparative Example 2 lacks the heat-resistant, hydrophobic siloxane structure, and the 1,3-bis(3-chloropropyl)tetramethyldisiloxane of Comparative Example 3 lacks the heat-resistant, hydrophobic polyphenyl ring structure. Both exhibit low thermal decomposition temperatures and water contact angles, resulting in poor heat resistance and hydrophobic water barrier properties.

[0055] To 100 mL of deionized water, 0.6 g of hydroxypropyl guar gum, 0.2 g of drainage aid, 0.13 g of organic boron cross-linking agent, and 0.06 g of shale oil breaker were added and stirred for 2 minutes to prepare a simulated water-based gel fracturing fluid.

[0056] The simulated water-based gel fracturing fluid was heated at 90℃ for 170s. -1 Shearing was performed at a rate of 0.05, and the viscosity was measured at shearing times of 3 min and 120 min, and the viscosity retention rate was calculated.

[0057] Table 2 Gel breaking performance test

[0058]

[0059] After testing, compared with comparative examples 1-3, the viscosity retention rate of the gel fracturing fluid of Examples 1-4 can reach 38.30-45.67% after shearing for 120 minutes, and has a good slow-release gel-breaking effect.

[0060] To 100 mL of deionized water, 0.6 g of hydroxypropyl guar gum, 0.2 g of drainage aid, 0.13 g of organic boron crosslinking agent, and 0.06-0.12 g of shale oil breaker (prepared in Example 3) were added and stirred for 2 minutes to prepare a simulated water-based gel fracturing fluid.

[0061] The simulated water-based gel fracturing fluid was heated at 90℃ for 170s. -1 Shearing was performed at a rate of 0.05, and the viscosity was measured at shearing times of 3 min and 120 min, and the viscosity retention rate was calculated.

[0062] Table 3 Gel breaking performance test of different shale oil breaker dosages

[0063] Gel breaker dosage (g) Shear time 3min viscosity (mPa·s) Viscosity after shearing time 120 min (mPa·s) Viscosity retention rate (%) 0.06 387.8 177.1 45.67 0.08 388.1 186.4 48.03 0.1 389.7 197.5 50.68 0.12 389.3 199.8 51.32 0.14 389.0 201.9 51.90

[0064] After testing, when the dosage of shale oil breaker is 0.06-0.14g, the viscosity retention rate reaches 45.67-51.90% after 120 minutes of shearing, effectively achieving a sustained-release breaking effect.

[0065] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A process for preparing a shale oil breaker, characterized in that: The preparation process comprises: S1: Add cellulose to a sodium hydroxide aqueous solution, heat and stir, filter, wash with deionized water, and dry; then add cellulose to N,N-dimethylacetamide, stir, add pyridine, bis[4-(2-chloroformylbenzamide)phenoxy]dimethylsilane, and 1,4-dioxane cosolvent in a nitrogen atmosphere, stir for reaction, filter, wash, and dry to obtain a silicone cross-linked cellulose gel; The mass ratio of cellulose, pyridine, and bis[4-(2-chloroformylbenzamide)phenoxy]dimethylsilane in S1 is 100:(150-350):(230-520); The structural formula of the bis[4-(2-chloroformylbenzamide)phenoxy]dimethylsilane is: , The preparation process of the bis[4-(2-chloroformylbenzamide)phenoxy]dimethylsilane is as follows: bis(4-aminophenoxy)dimethylsilane and phthalic anhydride are added to N,N-dimethylacetamide, stirred and reacted at 15-30° C. for 12-18 hours, diluted with deionized water, extracted with dichloromethane, distilled the organic phase under reduced pressure, washed, and dried, and the product is added to thionyl chloride, condensed and refluxed at 65-75° C. for 4-6 hours, distilled under reduced pressure, and dried to obtain bis[4-(2-chloroformylbenzamide)phenoxy]dimethylsilane, wherein the molar ratio of the bis(4-aminophenoxy)dimethylsilane, phthalic anhydride, and thionyl chloride is 1:(2-2.2):(12-16); S2: adding organosilicon cross-linked cellulose gel to an aqueous solution of ammonium persulfate, stirring, freezing the solution with liquid nitrogen, freeze-drying it in a freeze dryer, washing it with water, and drying it to obtain a shale oil breaker; The ratio of the ammonium persulfate aqueous solution to the organosilicon cross-linked cellulose gel in S2 is 1L: (3-10) g; the mass concentration of the ammonium persulfate aqueous solution is (100-400) g / L; To 100 mL of deionized water, 0.6 g of hydroxypropyl guar gum, 0.2 g of drainage aid, 0.13 g of organic boron crosslinking agent, and 0.06 g of the shale oil breaker were added and stirred for 2 min to prepare a simulated water-based gel fracturing fluid. The simulated water-based gel fracturing fluid was heated at 90 ° C for 170 s. -1 The shearing was carried out at a rate of 0.05, and the viscosity retention rate reached 38.30-45.67% after a shearing time of 120 min.

2. The preparation process of the shale oil breaker according to claim 1, characterized in that: The mass fraction of the sodium hydroxide aqueous solution in S1 is 20-40%.

3. The preparation process of the shale oil breaker according to claim 1, characterized in that: The temperature during heating and stirring in S1 is 30-40° C. and the time is 1-2 h; the temperature during stirring reaction is 15-30° C. and the time is 3-6 h.

4. The preparation process of the shale oil breaker according to claim 1, characterized in that: The volume ratio of N,N-dimethylacetamide to 1,4-dioxane in S1 is 100:(30-50).

5. The preparation process of the shale oil breaker according to claim 1, characterized in that: The temperature during stirring in S2 is 15-40° C. and the time is 12-18 h; the temperature for freeze drying is -50° C. to -60° C. and the time is 48-72 h.

6. A gel breaker for shale oil obtained by the preparation process according to any one of claims 1 to 5.

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