Fracturing fluid thickening agent, preparation method thereof, fracturing fluid and application

Abstract

The invention relates to the technical field of shale oil fracturing, in particular to a fracturing fluid thickening agent, a preparation method thereof, fracturing fluid and application. The invention provides a fracturing fluid thickening agent. The fracturing fluid thickening agent is prepared from the following raw materials: acrylic acid, acrylamide, N-alkyl-N-alkenyl pyrrolidone, p-phenyl alkenyl sulfonate, alkyl alkenyl acyloxy alkyl trialkyl ammonium chloride, an initiator and water. According to the invention, by controlling the composition of the thickening agent, the hydrolysis degree of the fracturing fluid thickening agent prepared by the invention is 12%-14%, the intrinsic viscosity is 850mL / g-900mL / g, and the viscosity average molecular weight is 360 * 10 < 4 > g / mol-390 * 10 < 4 > g / mol. When the thickening agent provided by the invention is applied to the fracturing fluid and used under the condition of 200 DEG C, the thickening agent has the advantages of good anti-shearing performance, strong sand-carrying capacity, quick adhesion in water and very good tackifying effect. The invention solves the technical problems that the anti-shearing capability of the fracturing fluid thickening agent of the existing system is insufficient when the temperature exceeds 170 DEG C, and the sand-carrying capability is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of shale oil fracturing, and in particular to a fracturing fluid thickener and a preparation method thereof, a fracturing fluid and applications thereof. Background Art

[0002] Shale oil and gas resources occupy a very important position among unconventional oil and gas resources. Shale oil and gas development is a very hot topic at present. Research on various technologies surrounding shale oil and gas development is also very popular. The burial depth of Shengli shale oil reservoirs is usually more than 3,000 meters, or even more than 5,000 meters, and the reservoir temperature exceeds 170°C, with a maximum of more than 200°C. The reservoir pressure is high, the degree of evolution is low, the density is high, the fluidity is poor, and the development is difficult, which brings great challenges to the fracturing transformation of such reservoirs. Therefore, Shengli shale oil fracturing requires that the fracturing fluid thickener has good shear resistance and sand carrying performance at high temperatures, and must have excellent friction reduction performance.

[0003] The heat resistance and shear resistance of the currently used fracturing fluid thickener will be significantly reduced when the temperature exceeds 170°C, and the sand carrying capacity is insufficient at this time, and the construction risk is high. Therefore, the development and research of a fracturing fluid thickener with high temperature resistance is a technical problem that needs to be solved urgently in the prior art. Summary of the invention

[0004] In order to solve the above problems in the prior art, the present invention provides a fracturing fluid thickener and a preparation method thereof, a fracturing fluid and applications thereof.

[0005] In a first aspect, the present invention provides a fracturing fluid thickener. The raw materials for preparing the fracturing fluid thickener include: acrylic acid, acrylamide, N-alkyl-N-alkenyl pyrrolidone, p-phenylene sulfonate, alkyl alkenyl acyloxyalkyl trialkyl ammonium chloride, an initiator and water.

[0006] As a specific embodiment of the present invention, the fracturing fluid thickener has a hydrolysis degree of 12% to 14%, an intrinsic viscosity of 850 mL / g to 900 mL / g, and a viscosity average molecular weight of 360×10 4 g / mol~390×10 4 g / mol.

[0007] As a specific embodiment of the present invention, the sum of the mass of acrylic acid, acrylamide, N-alkyl-N-alkenyl pyrrolidone, p-phenylene sulfonate and alkylene acyloxyalkyl trialkyl ammonium chloride is 20% to 30% of the mass of the fracturing fluid thickener. Specifically, the sum of the mass of acrylic acid, acrylamide, N-alkyl-N-alkenyl pyrrolidone, p-phenylene sulfonate and alkylene acyloxyalkyl trialkyl ammonium chloride can be 22%, 25%, 27%, 29% of the mass of the fracturing fluid thickener.

[0008] As a specific embodiment of the present invention, the mass of the initiator is 0.03% to 0.06% of the mass of the fracturing fluid thickener. Specifically, the mass of the initiator is 0.04% or 0.05% of the mass of the fracturing fluid thickener.

[0009] As a specific embodiment of the present invention, the mass ratio of acrylic acid, acrylamide, N-alkyl-N-alkenyl pyrrolidone, p-phenylene sulfonate, and alkyl alkenyl acyloxyalkyl trialkylammonium chloride is (25-35):(100-110):(2-2.8):(1-1.5):(1-1.5).

[0010] As a specific embodiment of the present invention, the mass ratio of acrylic acid, acrylamide, N-alkyl-N-alkenyl pyrrolidone, p-phenylene sulfonate, and alkylene acyloxyalkyl trialkylammonium chloride is (28-32):(102-107):(2.2-2.7):(1.1-1.3):(1.1-1.3).

[0011] As a specific embodiment of the present invention, the initiator includes: persulfate, thiosulfate and azobisisobutylamidine hydrochloride;

[0012] As a specific embodiment of the present invention, the mass ratio of persulfate, thiosulfate and azobisisobutylamidine hydrochloride is (0.05-0.12):(0.05-0.12):(0.05-0.12).

[0013] Preferably, the mass ratio of persulfate, thiosulfate and azobisisobutylamidine hydrochloride is (0.06

[0014] ~0.10):(0.06~0.10):(0.06~0.10).

[0015] Specifically, the initiator in the present invention can be composed of potassium persulfate, sodium thiosulfate and azobisisobutylamidine hydrochloride. When the initiator is potassium persulfate, sodium thiosulfate and azobisisobutylamidine hydrochloride, the initiator is added in a manner of first adding azobisisobutylamidine hydrochloride, then adding potassium persulfate 5 minutes later, and then adding sodium thiosulfate 5 minutes later.

[0016] Specifically, the initiator in the present invention may be composed of ammonium persulfate, potassium thiosulfate and azobisisobutylamidine hydrochloride.

[0017] When the initiator is composed of ammonium persulfate, potassium thiosulfate and azobisisobutylamidine hydrochloride, the initiator can be added by first adding azobisisobutylamidine hydrochloride, then adding ammonium persulfate after 5 minutes, and then adding potassium thiosulfate after another 5 minutes; or first adding azobisisobutylamidine hydrochloride, and then adding ammonium persulfate and potassium thiosulfate at the same time.

[0018] Initiators are compounds that are easily decomposed into free radicals (i.e., primary free radicals) by heat, and can be used to initiate free radical polymerization and copolymerization of olefinic and diene monomers, and can also be used for crosslinking and curing of unsaturated polyesters and crosslinking reactions of polymers. In the present invention, the fracturing fluid thickener is prepared by initiating the reaction of acrylic acid, acrylamide, N-alkyl-N-alkenyl pyrrolidone, p-phenylene sulfonate, and alkylene acyloxyalkyl trialkyl ammonium chloride with an initiator.

[0019] As a specific embodiment of the present invention, the alkyl group in N-alkyl-N-alkenyl pyrrolidone is selected from C 1-16 The alkyl group is preferably selected from C 1～6 alkyl; specifically, methyl, ethyl, propyl, etc.

[0020] The alkenyl group in N-alkyl-N-alkenyl pyrrolidone is selected from C 1～8 The alkenyl group is preferably selected from C 1～3 Specifically, it can be vinyl, propenyl, butene, etc.

[0021] As a specific embodiment of the present invention, the alkenyl group in the p-phenylene sulfonate is selected from C 1～12 The alkenyl group is preferably selected from C 1～8 Specifically, it can be vinyl, propenyl, butene, etc.

[0022] Preferably, the p-phenylene sulfonate is sodium p-phenylene sulfonate or potassium p-phenylene sulfonate; specifically, it may be sodium p-phenylene sulfonate, potassium p-phenylene sulfonate, sodium p-phenylene sulfonate, and the like.

[0023] As a specific embodiment of the present invention, the alkyl groups in the alkyl alkenyl acyloxyalkyl trialkyl ammonium chloride are independently selected from C 1-16 The alkyl group is preferably selected from C 1～6 alkyl; specifically, methyl, ethyl, propyl, etc.

[0024] The alkenyl group in the alkyl alkenyl acyloxy alkyl trialkyl ammonium chloride is selected from C 1～8 The alkenyl group is preferably selected from C 1～3 Specifically, it can be vinyl, propenyl, butene, etc.

[0025] In the present invention, the alkyl group in the N-alkyl-N-alkenyl pyrrolidone and the alkyl group in the alkyl alkenyl acyloxyalkyl trialkylammonium chloride may be the same as or different from each other.

[0026] In the present invention, the alkenyl group in N-alkyl-N-alkenyl pyrrolidone, the alkenyl group in p-phenylene sulfonate and the alkenyl group in alkyl alkenyl acyloxyalkyl trialkyl ammonium chloride may be the same or different.

[0027] In a second aspect, the present invention provides a method for preparing the fracturing fluid thickener provided in the first aspect of the present invention, comprising the following steps:

[0028] (1) mixing acrylic acid, acrylamide, N-alkyl-N-alkenyl pyrrolidone, p-phenylene sulfonate, alkylene acyloxyalkyl trialkyl ammonium chloride and water to obtain a mixed solution;

[0029] (2) The mixed liquid is placed under an inert atmosphere, an initiator is added to the mixed liquid, and the reaction is performed to obtain a fracturing fluid thickener.

[0030] As a specific embodiment of the present invention, the inert atmosphere may be a nitrogen atmosphere.

[0031] As a specific embodiment of the present invention, in step (1), the pH value of the mixed solution is adjusted to 6.0-7.0. In the present invention, the pH value of the mixed solution can be adjusted with an alkali, and specifically, sodium hydroxide can be used to adjust the pH value of the mixed solution.

[0032] As a specific embodiment of the present invention, in step (2), the temperature of the mixed liquid is first reduced to -7 to 0°C and then placed under inert gas conditions.

[0033] As a specific embodiment of the present invention, in step (2), the reaction conditions include: temperature of -7 to 0°C and time of 2 to 5 hours.

[0034] In a third aspect, the present invention provides a fracturing fluid, which comprises the fracturing fluid thickener provided in the first aspect of the present invention or the fracturing fluid thickener prepared by the preparation method provided in the second aspect of the present invention.

[0035] Preferably, the fracturing fluid thickener is 0.1% to 1.0% of the mass of the fracturing fluid.

[0036] In a fourth aspect, the present invention provides an application of the fracturing fluid thickener provided in the first aspect of the present invention, the fracturing fluid thickener prepared by the preparation method provided in the second aspect of the present invention, or the fracturing fluid provided in the third aspect of the present invention in shale oil fracturing.

[0037] Specifically, the fracturing fluid thickener provided by the present invention can be added to the fracturing fluid and used for slick water (pre-fluid) and sand-carrying fluid in the fracturing process of high-temperature and ultra-high-temperature deep-well shale oil and gas reservoirs, or can also be used in other oil field operations where the viscosity of the working fluid needs to be increased, such as increasing the viscosity of the drilling fluid in drilling operations.

[0038] The fracturing fluid thickener prepared by the present invention is a polymer. In the test process of the embodiments and comparative examples of the present invention, the hydrolysis degree, intrinsic viscosity and viscosity-average molecular weight of the prepared fracturing fluid thickener were tested. The hydrolysis degree, intrinsic viscosity and viscosity-average molecular weight are all product parameters of the polymer itself. However, the hydrolysis degree, intrinsic viscosity and viscosity-average molecular weight of the fracturing fluid thickener determine the viscosity starting time, viscosity and temperature resistance of the thickener when the polymer is used as a fracturing fluid thickener. Generally speaking, when the hydrolysis degree of the fracturing fluid thickener is 12% to 14%, the intrinsic viscosity is 850 mL / g to 900 mL / g, and the viscosity-average molecular weight is 360×10 4 g / mol~390×10 4 g / mol, it means that its temperature resistance can be as high as 200℃, that is, when used at 200℃, the viscosity-increasing speed in the fracturing fluid meets the use requirements, and it has a good viscosity-increasing effect while still maintaining excellent shear resistance and sand carrying capacity.

[0039] Compared with the prior art, the present invention has the following beneficial effects.

[0040] By controlling the composition of the thickener, the thickener provided by the present invention can have good anti-shear performance and strong sand carrying capacity when used in the fracturing fluid at 200°C, and can quickly become sticky in water, thus having a good thickening effect. The technical problem in the prior art that the anti-shear capacity of the fracturing fluid thickener is insufficient and the sand carrying capacity is reduced when the temperature exceeds 170°C is solved.

[0041] The fracturing fluid thickener prepared in the present invention can be used normally at high temperatures, greatly reducing construction risks. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with specific embodiments, but they do not constitute any limitation to the present invention.

[0043] The raw materials used in the examples and comparative examples are all commercially available.

[0044] The hydrolysis degree, intrinsic viscosity and viscosity-average molecular weight of the fracturing fluid thickeners in the examples and comparative examples were measured according to GB / T12005.6, GB / T12005.1 and GB / T12005.10, respectively.

[0045] Example 1

[0046] Dissolve 28.0 g of acrylic acid, 104.5 g of acrylamide, 2.3 g of N-methyl-N-vinyl pyrrolidone, 1.2 g of sodium p-styrene sulfonate, and 1.2 g of methacryloyloxyethyltrimethylammonium chloride in 487.1 g of water, and adjust the pH to 7.0 with sodium hydroxide to obtain a mixed solution; refrigerate the mixed solution, and when the temperature drops to -6°C, place the mixed solution in a thermos bottle.

[0047] After nitrogen was continuously passed through the thermos for 30 minutes, 0.06 g of azobisisobutylamidine hydrochloride, 0.06 g of potassium persulfate and 0.08 g of sodium thiosulfate were added, and a rubber block was obtained after reaction for 3 hours. The obtained rubber block was cut into pieces, dried at 60°C, crushed and sieved to obtain a fracturing fluid thickener.

[0048] The prepared fracturing fluid thickener was tested, and the performance parameters of the fracturing fluid thickener were as follows: hydrolysis degree: 12.3%; intrinsic viscosity: 852.2 mL / g; viscosity average molecular weight: 365.8×10 4 g / mol.

[0049] Example 2

[0050] Dissolve 28.8 g of acrylic acid, 105.3 g of acrylamide, 2.2 g of N-ethyl-N-acryl pyrrolidone, 1.3 g of sodium p-phenylene sulfonate, and 1.3 g of ethyl acryloyloxyethyl triethyl ammonium chloride in 417.3 g of water, and adjust the pH to 6.0 with sodium hydroxide to obtain a mixed solution; refrigerate the mixed solution, and when the temperature drops to -5°C, place the mixed solution in a thermos bottle.

[0051] After nitrogen was continuously passed through the thermos for 30 minutes, 0.06 g of azobisisobutylamidine hydrochloride, 0.06 g of potassium persulfate and 0.08 g of sodium thiosulfate were added, and a rubber block was obtained after reaction for 4 hours. The obtained rubber block was cut into pieces, dried at 70°C, crushed and sieved to obtain a fracturing fluid thickener.

[0052] The prepared fracturing fluid thickener was tested, and the performance parameters of the fracturing fluid thickener were as follows: hydrolysis degree: 12.8%; intrinsic viscosity: 860.6 mL / g; viscosity average molecular weight: 371.69×10 4 g / mol.

[0053] Example 3

[0054] Dissolve 29.6 g of acrylic acid, 104.8 g of acrylamide, 2.3 g of N-isopropyl-N-vinyl pyrrolidone, 1.1 g of potassium p-styrenesulfonate, and 1.3 g of methacryloyloxyethyl triethylammonium chloride in 376.6 g of water, and adjust the pH to 6.0 with sodium hydroxide to obtain a mixed solution; refrigerate the mixed solution, and when the temperature drops to -7°C, add the mixed solution into a thermos bottle.

[0055] After nitrogen was continuously passed through the thermos for 30 minutes, 0.06 g of azobisisobutylamidine hydrochloride, 0.06 g of potassium persulfate and 0.08 g of sodium thiosulfate were added, and a rubber block was obtained after reaction for 4 hours. The obtained rubber block was cut into pieces, dried at 60°C, crushed and sieved to obtain a fracturing fluid thickener.

[0056] The prepared fracturing fluid thickener was tested, and the performance parameters of the fracturing fluid thickener were as follows: hydrolysis degree: 13.2%; intrinsic viscosity: 866.4 mL / g; viscosity average molecular weight: 375.82×10 4 g / mol.

[0057] Example 4

[0058] Dissolve 30.7 g of acrylic acid, 105.7 g of acrylamide, 2.2 g of N-n-butyl-N-vinyl pyrrolidone, 1.1 g of sodium p-phenylene isobutylene sulfonate, and 1.1 g of methacryloyloxyethyl tri-n-pentyl ammonium chloride in 345.2 g of water, and adjust the pH to 6.0 with sodium hydroxide to obtain a mixed solution; refrigerate the mixed solution, and when the temperature drops to 0°C, add the mixed solution into a thermos bottle.

[0059] After nitrogen was continuously passed through the thermos for 30 minutes, 0.06 g of azobisisobutylamidine hydrochloride, 0.06 g of ammonium persulfate and 0.08 g of potassium thiosulfate were added, and a rubber block was obtained after reaction for 5 hours. The obtained rubber block was cut into pieces, dried at 60°C, crushed and sieved to obtain a fracturing fluid thickener.

[0060] The prepared fracturing fluid thickener was tested, and the performance parameters of the fracturing fluid thickener were as follows: hydrolysis degree: 13.5%; intrinsic viscosity: 879.1 mL / g; viscosity average molecular weight: 380.6×10 4 g / mol.

[0061] Example 5

[0062] 32.0 g of acrylic acid, 106.7 g of acrylamide, 2.0 g of N-n-hexyl-N-isooctenyl pyrrolidone, 1.3 g of sodium terephthalene sulfonate, and 1.1 g of n-hexylacryloyloxyethyl tri(undecyl)ammonium chloride were dissolved in 350.8 g of water, and the pH was adjusted to 7.0 with sodium hydroxide to obtain a mixed solution; the mixed solution was refrigerated and when the temperature dropped to -1°C, the mixed solution was added into a thermos bottle.

[0063] After nitrogen was continuously passed through the thermos for 30 minutes, 0.06 g of azobisisobutylamidine hydrochloride, 0.06 g of ammonium persulfate and 0.08 g of potassium thiosulfate were added, and a rubber block was obtained after reaction for 5 hours. The obtained rubber block was cut into pieces, dried at 60°C, crushed and sieved to obtain a fracturing fluid thickener.

[0064] The prepared fracturing fluid thickener was tested, and the performance parameters of the fracturing fluid thickener were as follows: degree of hydrolysis: 14.0%; intrinsic viscosity: 899.8 mL / g; viscosity average molecular weight: 390.0×10 4 g / mol.

[0065] Comparative Example 1

[0066] Dissolve 25.0 g of acrylic acid, 84.0 g of acrylamide, 3.3 g of N-methyl-N-vinyl pyrrolidone, 2.5 g of sodium p-styrene sulfonate, and 3.0 g of methacryloyloxyethyltrimethylammonium chloride in 354.0 g of water, and adjust the pH to 6.0 with sodium hydroxide to obtain a mixed solution; refrigerate the mixed solution, and when the temperature drops to -5°C, add the mixed solution into a thermos bottle.

[0067] After nitrogen was continuously passed through the thermos for 30 minutes, 0.06 g of azobisisobutylamidine hydrochloride, 0.06 g of potassium persulfate and 0.08 g of sodium thiosulfate were added, and a rubber block was obtained after reaction for 6 hours. The obtained rubber block was cut into pieces, dried at 70°C, crushed and sieved to obtain a fracturing fluid thickener.

[0068] The prepared fracturing fluid thickener was tested, and the performance parameters of the fracturing fluid thickener were as follows: hydrolysis degree: 11.1%; intrinsic viscosity: 823.6 mL / g; viscosity average molecular weight: 330.36×10 4 g / mol.

[0069] The hydrolysis degree, intrinsic viscosity and viscosity-average molecular weight of the fracturing fluid thickener in Comparative Example 1 did not reach the target range, and its temperature resistance was 167°C. When used at high temperatures, the shear force and sand carrying capacity were reduced. It was slow to become sticky in water, and the viscosity-increasing effect was poor. The construction risk was high during the construction process.

[0070] Comparative Example 2

[0071] Dissolve 38.0 g of acrylic acid, 115.0 g of acrylamide, 1.5 g of N-isopropyl-N-vinyl pyrrolidone, 1.0 g of potassium p-styrenesulfonate, and 1.0 g of methacryloyloxyethyl triethylammonium chloride in 383.6 g of water, and adjust the pH to 6.0 with sodium hydroxide to obtain a mixed solution; refrigerate the mixed solution, and when the temperature drops to -5°C, add the mixed solution into a thermos bottle.

[0072] After nitrogen was continuously passed through the thermos for 30 minutes, 0.06 g of azobisisobutylamidine hydrochloride, 0.06 g of potassium persulfate and 0.08 g of sodium thiosulfate were added, and a rubber block was obtained after reaction for 6 hours. The obtained rubber block was cut into pieces, dried at 70°C, crushed and sieved to obtain a fracturing fluid thickener.

[0073] The prepared fracturing fluid thickener was tested, and the performance parameters of the fracturing fluid thickener were as follows: degree of hydrolysis: 18.8%; intrinsic viscosity: 977.3 mL / g; viscosity-average molecular weight: 425.12×10 g / mol.

[0074] The hydrolysis degree, intrinsic viscosity and viscosity-average molecular weight of the fracturing fluid thickener in Comparative Example 2 all exceed the target range, and its temperature resistance is 148°C. When used at high temperatures, the shear force and sand carrying capacity cannot meet the use requirements. Moreover, the viscosity increases significantly faster in water, and the viscosity increases too quickly. The construction risk is high during the construction process.

[0075] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A fracturing fluid thickener, characterized in that: The raw materials for preparing the fracturing fluid thickener include: acrylic acid, acrylamide, N-alkyl-N-alkenyl pyrrolidone, p-phenylene sulfonate, alkylene acyloxyalkyl trialkyl ammonium chloride, initiator and water.

2. The fracturing fluid thickener according to claim 1, characterized in that: The fracturing fluid thickener has a hydrolysis degree of 12% to 14%, an intrinsic viscosity of 850 mL / g to 900 mL / g, and a viscosity-average molecular weight of 360×10 4 g / mol~390×10 4 g / mol.

3. The fracturing fluid thickener according to claim 1 or 2, characterized in that: The sum of the mass of acrylic acid, acrylamide, N-alkyl-N-alkenyl pyrrolidone, p-phenylene sulfonate and alkylene acyloxyalkyl trialkyl ammonium chloride is 20% to 30% of the mass of the fracturing fluid thickener.

4. The fracturing fluid thickener according to any one of claims 1 to 3, characterized in that: The mass of the initiator is 0.03% to 0.06% of the mass of the fracturing fluid thickener.

5. The fracturing fluid thickener according to any one of claims 1 to 4, characterized in that: The mass ratio of the acrylic acid, the acrylamide, the N-alkyl-N-alkenyl pyrrolidone, the p-phenylene sulfonate, and the alkylene acyloxyalkyl trialkylammonium chloride is 25-35:100-110:2-2.8:1-1.5:1-1.5; Preferably, the mass ratio of the acrylic acid, the acrylamide, the N-alkyl-N-alkenyl pyrrolidone, the p-phenylene sulfonate, and the alkylene acyloxyalkyl trialkylammonium chloride is 28-32:102-107:2.2-2.7:1.1-1.3:1.1-1.3; and / or, the initiator comprises persulfate, thiosulfate and azobisisobutylamidine hydrochloride; Preferably, the mass ratio of the persulfate, the thiosulfate and azobisisobutylamidine hydrochloride is 0.05-0.12:0.05-0.12:0.05-0.12; Preferably, the mass ratio of the persulfate, the thiosulfate and azobisisobutylamidine hydrochloride is 0.06-0.10:0.06-0.10:0.06-0.

10.

6. The fracturing fluid thickener according to any one of claims 1 to 5, characterized in that: The alkyl group in the N-alkyl-N-alkenyl pyrrolidone is selected from C 1～16 The alkyl group Preferably selected from C 1～6 The alkyl group; The alkenyl group in the N-alkyl-N-alkenyl pyrrolidone is selected from C 1～8 The alkenyl group, Preferably selected from C 1～3 The alkenyl group; And / or, the alkenyl group in the p-phenylene sulfonate is selected from C 1～12 The alkenyl group, Preferably selected from C 1～8 The alkenyl group; Preferably, the p-phenylene sulfonate is sodium p-phenylene sulfonate or potassium p-phenylene sulfonate; And / or, the alkyl groups in the alkyl alkenyl acyloxyalkyl trialkyl ammonium chloride are each independently selected from C 1～16 The alkyl group; Preferably selected from C 1～6 The alkyl group; The alkenyl group in the alkyl alkenyl acyloxy alkyl trialkyl ammonium chloride is selected from C 1～8 The alkenyl group, Preferably selected from C 1～3 The alkenyl group.

7. A method for preparing the fracturing fluid thickener according to any one of claims 1 to 6, characterized in that: The steps include: (1) mixing acrylic acid, acrylamide, N-alkyl-N-alkenyl pyrrolidone, p-phenylene sulfonate, alkylene acyloxyalkyl trialkyl ammonium chloride and water to obtain a mixed solution; (2) placing the mixed liquid under an inert atmosphere, adding an initiator to the mixed liquid for reaction, and obtaining a fracturing fluid thickener.

8. The preparation method according to claim 7, characterized in that: In step (1), the pH value of the mixed solution is adjusted to 6.0-7.0; And / or, in step (2), the temperature of the mixed solution is first reduced to -7 to 0°C and then placed under inert gas conditions; And / or, in step (2), the reaction conditions include: temperature of -7 to 0°C and time of 2 to 5 hours.

9. A fracturing fluid, characterized in that: The fracturing fluid comprises the fracturing fluid thickener according to any one of claims 1 to 6 or the fracturing fluid thickener prepared by the preparation method according to any one of claims 7 to 8; preferably, the fracturing fluid thickener accounts for 0.1% to 1.0% of the mass of the fracturing fluid.

10. Use of the fracturing fluid thickener according to any one of claims 1 to 6, or the fracturing fluid thickener prepared by the preparation method according to any one of claims 7 to 8, or the fracturing fluid according to claim 9 in shale oil fracturing.