Residue-free slickwater fracturing fluid and preparation method thereof

Abstract

The invention belongs to the technical field of oil and gas exploitation, and discloses a residue-free slickwater fracturing fluid and a preparation method thereof.The preparation method comprises the steps that an anionic monomer, a cationic monomer and a nonionic monomer are added into water according to the proportion; adjusting the pH value of the solution to obtain an aqueous solution; adding an emulsifier and a co-emulsifier into oil in proportion to obtain an oil solution; mixing the aqueous solution and the oil solution in proportion, introducing nitrogen, and heating to 45-96 DEG C; and adding an initiator, stopping introducing nitrogen after initiation, and reacting to obtain the emulsion polymerization stock solution. The residue-free slickwater fracturing fluid prepared by the invention can be quickly dissolved and quickly adhered, has high drag reduction rate, is thorough in gel breaking, is residue-free and easy to flow back, and reduces the damage to the stratum. And large-scale continuous liquid preparation on a fracturing site can be realized, and the requirement of compact low-permeability reservoir volume fracturing on liquid is met.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas extraction, and relates to a residue-free slickwater fracturing fluid and a preparation method thereof. Background Art

[0002] my country's oil and gas fields are rich in low-permeability strata, and fracturing technology is a key measure for increasing production in mid- and late-stage oilfield development. However, with the development of low- and ultra-low-permeability reservoirs, reservoir lithology has become more complex, physical properties have deteriorated, and reservoir types have become more diverse, making fracturing increasingly challenging. High-efficiency, factory-based fracturing for large-scale horizontal wells is becoming the mainstream technology for cost-effective development. However, fracturing fluid residue is often the main cause of post-fracturing pore blockage. Conventional guar gum fracturing fluids have high concentrations, high residue damage, and low drag reduction. These fracturing fluids require pre-mixing at the mixing station, making them incapable of the continuous mixing required for horizontal well fracturing. Conventional polypropylene fracturing fluids lack rapid viscosity development, have high residue levels, and can clog the formation, hindering the development of ultra-low-permeability reservoirs. Therefore, for horizontal well fracturing in ultra-low-permeability reservoirs, a fracturing fluid that can be continuously mixed, rapidly viscosifies, and is residue-free is required to improve the conductivity of low-permeability reservoirs.

[0003] Invention patent CN201510143592.7, "Drag reducer for slick water fracturing fluid system with high efficiency, fast dissolution and low friction resistance without oil solution," discloses a drag reducer for slick water fracturing fluid system with high efficiency, fast dissolution and low friction resistance without oil solution, belonging to the technical field of application of engineering chemical agents in oil and gas fields. The drag reducer is characterized in that the drag reducer is obtained by precipitation polymerization of a water-soluble monomer A, a hydrophobic monomer B, a mutual solvent C, and a free radical initiator E in an aqueous solution D containing a surfactant / dispersant and an inorganic salt; the weight percentages of the components are as follows: water-soluble monomer A: 5-40%; hydrophobic monomer B: 0.1-30%; mutual solvent C: 1-50%; surfactant / dispersant in the aqueous solution D: 0.1-10%; inorganic salt in the aqueous solution D: 10-50%; free radical initiator E: 0.000001-0.1%; and water: the balance. This invention, a high-efficiency, fast-dissolving, low-friction drag reducer for slickwater fracturing fluids, does not contain an oil solution. It retains the high-efficiency, fast-dissolving, and highly effective drag-reducing properties of existing drag reducers, achieving a drag-reduction efficiency of 70% during hydraulic fracturing. Furthermore, the introduction of hydrophobic groups reduces the affinity between the drag reducer molecules and with the reservoir rock, improving post-fracture drainage and reservoir protection. However, this slickwater fracturing fluid system suffers from a high residue content, limiting its application in volume fracturing of tight, low-permeability reservoirs. Summary of the Invention

[0004] In order to solve the above technical problems, one purpose of the present invention is to provide a residue-free slickwater fracturing fluid, which has the characteristics of being able to continuously mix liquid, quickly build viscosity, and being residue-free, thereby improving the conductivity of low-permeability oil reservoirs and meeting the requirements for liquid in volume fracturing of tight low-permeability reservoirs.

[0005] Another object of the present invention is to provide a method for preparing the residue-free slickwater fracturing fluid, wherein an emulsion polymer stock solution is synthesized by inverse emulsion polymerization, and then the emulsion polymer stock solution and other additives are uniformly mixed in a certain proportion to obtain the residue-free slickwater fracturing fluid for volume fracturing of tight low-permeability reservoirs.

[0006] To achieve the above technical objectives, on the one hand, the present invention provides a residue-free slickwater fracturing fluid, wherein the method comprises preparing an emulsion polymer stock solution and an additive in a certain proportion to obtain the residue-free slickwater fracturing fluid.

[0007] The present invention provides an emulsion polymer fracturing fluid stock solution, wherein the method comprises obtaining the emulsion polymer stock solution of the residue-free fracturing fluid by using an aqueous solution and an oil solution under the action of an initiator.

[0008] Furthermore, the emulsion polymer aqueous solution of the residue-free fracturing fluid comprises anionic monomers, cationic monomers, nonionic monomers, and water; the emulsion polymer oil solution of the residue-free fracturing fluid comprises oil, emulsifier, and co-emulsifier;

[0009] Furthermore, the aqueous solution containing anionic monomers, cationic monomers, and nonionic monomers, with its total weight being 100%, comprises:

[0010] Anionic monomer 0.3%~11%

[0011] Cationic monomer 0.4%~10.5%

[0012] Nonionic monomer 3% to 7%

[0013] and the balance of water;

[0014] Furthermore, the oil solution containing the emulsifier and the co-emulsifier, with its total weight being 100%, comprises:

[0015] Emulsifier 0.3% to 3%

[0016] Co-emulsifier 0.05%~2.5%

[0017] and the remaining oil;

[0018] Wherein, the anionic monomer is one or more of sodium acrylate, sodium dodecylbenzenesulfonate, and sodium p-vinylbenzenesulfonate.

[0019] Wherein, the cationic monomer is one or more of hexadecyldimethylammonium chloride, dodecyltrimethylammonium bromide, and 2,3-epoxypropyltrimethylammonium chloride.

[0020] Wherein, the nonionic monomer is one or more of N-hydroxymethyl acrylamide, octadecyl methacrylate, and dimethylaminoethyl methacrylate;

[0021] Wherein, the emulsifier is a mixture of one or more of N-methyldiethanolamine, sorbitan monostearate, polyglycerol fatty acid ester, and polypropylene glycol.

[0022] Wherein, the auxiliary emulsifier is a mixture of one or more of polyethylene glycol, oleic acid diethanolamide, tetradecyl alcohol polyoxyethylene ether, and sodium cocoyl isethionate.

[0023] The oil is a mixture of one or more of diesel, gasoline, white oil and kerosene.

[0024] Wherein, the initiator is a mixture of one or more of ammonium persulfate, sodium bisulfite, potassium thiosulfate, hydrogen peroxide, and potassium permanganate.

[0025] In the above-mentioned residue-free fracturing fluid emulsion polymer stock solution, preferably, the anionic monomer is a mixture of one or more of sodium dodecylbenzenesulfonate and sodium p-vinylbenzenesulfonate.

[0026] In the above-mentioned residue-free fracturing fluid emulsion polymer stock solution, preferably, the cationic monomer is a mixture of one or more of hexadecyldimethylammonium chloride and 2,3-epoxypropyltrimethylammonium chloride.

[0027] In the above-mentioned residue-free fracturing fluid emulsion polymer stock solution, preferably, the nonionic monomer is a mixture of one or more of N-hydroxymethyl acrylamide and octadecyl methacrylate.

[0028] In the above-mentioned residue-free fracturing fluid emulsion polymer stock solution, preferably, the emulsifier is a mixture of one or more of sorbitan monostearate and polyglycerol fatty acid ester.

[0029] In the above-mentioned residue-free fracturing fluid emulsion polymer stock solution, preferably, the co-emulsifier is a mixture of one or more of polyethylene glycol and sodium cocoyl isethionate.

[0030] In the above-mentioned residue-free fracturing fluid emulsion polymer stock solution, preferably, the oil is a mixture of one or more of white oil and kerosene.

[0031] In the above-mentioned residue-free fracturing fluid emulsion polymer stock solution, preferably, the initiator is a mixture of one or more of potassium thiosulfate and potassium permanganate.

[0032] In another aspect, the present invention provides a method for preparing a residue-free fracturing fluid emulsion polymer stock solution, wherein the method comprises the following steps:

[0033] (1) adding the anionic monomer, cationic monomer, and nonionic monomer to water in proportion; adjusting the pH value of the solution to obtain an aqueous solution;

[0034] (2) adding the emulsifier and the co-emulsifier to the oil in proportion to obtain an oil solution;

[0035] (3) The aqueous solution and the oil solution are mixed in proportion, nitrogen is introduced, and the temperature is raised to 45-96°C;

[0036] (4) Add initiator, stop nitrogen flow after initiation, and react to obtain emulsion polymerization stock solution.

[0037] According to some specific embodiments of the present invention, step (1) is to adjust the pH value of the solution to 6.5-8.

[0038] The pH value of the solution in step (1) is adjusted according to conventional operations in the art, such as adding an acidic regulator or an alkaline regulator. According to some specific embodiments of the present invention, the acidic regulator can be selected from 2% hydrochloric acid or 5% citric acid; the alkaline regulator can be selected from sodium hydroxide, sodium carbonate, or sodium bicarbonate.

[0039] According to some specific embodiments of the present invention, step (2) is to dropwise add the emulsifier and the co-emulsifier into the oil and mix them uniformly.

[0040] According to some specific embodiments of the present invention, step (3) is to mix steps (1) and (2) under inert atmosphere and at a temperature of 45-96°C.

[0041] According to some specific embodiments of the present invention, in step (4), the temperature is raised to 90° C. for at least 45 minutes in step (3), followed by stirring for 30 minutes, and then adding the initiator. After stopping the nitrogen flow, the reaction is continued for 2-20 hours to obtain the acidic slickwater stock solution.

[0042] It is preferred that the reaction is carried out for 7-8 hours after the nitrogen is stopped to obtain the residue-free fracturing fluid emulsion polymer stock solution.

[0043] The present invention also provides additives, wherein the additives are composed of a fracturing drainage agent, an anti-swelling agent, and a gel breaker.

[0044] Furthermore, the fracturing drainage agent is one or more of a fluorocarbon drainage agent, a polyether-modified polysiloxane, and sodium dodecylbenzene sulfonate.

[0045] Furthermore, the anti-swelling agent is one or more of 3-chloro-2-hydroxypropyltrimethylammonium chloride, behenyltrimethylammonium chloride, 2,3-epoxypropyltrimethylammonium chloride, and polydimethyldiallylammonium chloride;

[0046] Furthermore, the fracturing breaker is one or more of ammonium persulfate, sodium persulfate, and potassium persulfate;

[0047] Among the above-mentioned drainage aids, preferably, the drainage aid is one or more of polyether-modified polysiloxane and sodium dodecylbenzene sulfonate.

[0048] Among the above-mentioned anti-swelling agents, preferably, the anti-swelling agent is one or more of behenyltrimethylammonium chloride and 2,3-epoxypropyltrimethylammonium chloride;

[0049] Among the above-mentioned breakers, preferably, the breakers are ammonium persulfate, potassium persulfate or one or more;

[0050] According to a specific embodiment of the present invention, in another aspect, the present invention also provides a residue-free slickwater fracturing fluid prepared by the method. The residue-free slickwater fracturing fluid composition of the present invention, based on 100% by total weight, comprises the following components:

[0051] Emulsion polymerization stock solution: 0.2%-0.8%;

[0052] Fracturing aid: 1.5%-9%;

[0053] Anti-swelling agent: 1.2%-6.8%;

[0054] Gel breaker: 0.02%-0.08%

[0055] Water: Balance.

[0056] According to some specific embodiments of the present invention, the residue-free slickwater fracturing fluid is composed of an emulsion polymer, an acid solution, and an additive. The residue-free slickwater fracturing fluid can dissolve quickly, quickly dissolve and become sticky, has a high drag reduction rate, and improves conductivity. Therefore, it can meet the requirements of large-scale continuous fluid preparation on-site for volume fracturing of tight low-permeability reservoirs and improve the fracturing effect.

[0057] In summary, the present invention provides a residue-free slickwater fracturing fluid and its preparation and application.

[0058] The residue-free slickwater fracturing fluid of the present invention has the following advantages:

[0059] 1. The residue-free slickwater fracturing fluid prepared by the present invention can dissolve quickly, quickly build viscosity, has a high drag reduction rate, breaks gel thoroughly, has no residue, is easy to flow back, and reduces damage to the formation.

[0060] 2. The residue-free slickwater fracturing fluid prepared by the present invention can realize large-scale continuous fluid preparation at the fracturing site, meeting the requirements for fluid in volume fracturing of tight low-permeability reservoirs. DETAILED DESCRIPTION

[0061] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solutions of the present invention are described in detail below with reference to specific embodiments. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In the embodiments, all raw materials are commercially available, and the experimental methods without specifying specific conditions are conventional methods and conventional conditions well known in the art, or according to the conditions recommended by the instrument manufacturer.

[0062] Example 1:

[0063] The residue-free slickwater fracturing fluid for volume fracturing in this embodiment, wherein the aqueous solution and oil solution of the emulsion polymer stock solution are as follows:

[0064] Table 1 Aqueous solution composition of emulsion polymer stock solution (by weight percentage)

[0065] Sodium dodecylbenzenesulfonate 0.3％ Hexadecyldimethylammonium chloride 10.5％ N-hydroxymethyl acrylamide 3％ 5% citric acid to adjust pH 6.5 The balance is water

[0066] Table 2 Composition of oil solution of emulsion polymer stock solution (by weight percentage)

[0067] Sorbitan monostearate 0.3％ polyethylene glycol 2.5％ The balance is white oil

[0068] Table 3 Composition of residue-free slickwater fracturing fluid (by weight percentage)

[0069] Emulsion polymer stock solution 0.2％ Fracturing aid: polyether modified polysiloxane 9％ Anti-swelling agent: behenyltrimethylammonium chloride 1.2％ Gel breaker: ammonium persulfate 0.08％

[0070] An aqueous solution and an oil solution were prepared according to the proportions in Tables 1 and 2, respectively; the aqueous solution and the oil solution were mixed in a mass ratio of 4:3, nitrogen gas with a purity of 99.99% was introduced, and the temperature was raised to 96° C. for at least 50 minutes. After stirring for 30 minutes, potassium thiosulfate as an initiator was added. The nitrogen gas was stopped and the reaction was allowed to proceed for 8 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain an emulsion polymer stock solution with a solid content of approximately 35%.

[0071] The above-obtained emulsion polymer stock solution and additives were mixed in a certain ratio to obtain the acidic slickwater for volume fracturing, as shown in Table 3.

[0072] 0.2% of the residue-free slickwater fracturing fluid concentrate, 9.0% of the fracturing drainage agent, 1.2% of the anti-swelling agent, and 0.08% of the gel breaker are uniformly dissolved in water and stirred to obtain the residue-free slickwater fracturing fluid for volume fracturing.

[0073] Table 4 Performance test data of residue-free slickwater fracturing fluid

[0074] Adhesion time 5S Drag reduction rate 85％ Gel breaking effect Viscosity 0mPa.s

[0075] As can be seen from Table 4, the residue-free slickwater fracturing fluid can quickly build viscosity, completely break gel, has no residue, is easy to flow back, has low damage to the formation, and does not require advance fluid preparation, meeting the requirements of continuous mixing on-site volume fracturing construction in tight low-permeability reservoirs.

[0076] Example 2:

[0077] The residue-free slickwater fracturing fluid for volume fracturing in this embodiment, wherein the aqueous solution and oil solution of the emulsion polymer stock solution are as follows:

[0078] Table 5 Aqueous solution composition of emulsion polymer stock solution (by weight percentage)

[0079] Sodium p-vinylbenzenesulfonate 11％ 2,3-Epoxypropyltrimethylammonium chloride 0.4％ Octadecyl methacrylate 7％ Sodium hydroxide to adjust pH 7 The balance is water

[0080] Table 6 Composition of oil solution of emulsion polymer stock solution (by weight percentage)

[0081] Sorbitan monostearate 3％ Sodium Cocoyl Isethionate 0.05％ The balance is diesel

[0082] Table 7 Composition of Residue-Free Slickwater Fracturing Fluid (by Weight Percentage)

[0083] Emulsion polymer stock solution 0.8％ Fracturing aid: sodium dodecylbenzenesulfonate 1.5％ Anti-swelling agent: 2,3-epoxypropyltrimethylammonium chloride 6.8％ Gel breaker: potassium persulfate 0.02％

[0084] An aqueous solution and an oil solution were prepared according to the proportions in Tables 4 and 5, respectively; the aqueous solution and the oil solution were mixed in a mass ratio of 3:4, nitrogen gas with a purity of 99.99% was introduced, and the temperature was raised to 45° C. for at least 45 minutes. After stirring for 20 minutes, potassium permanganate as an initiator was added. After stopping the introduction of the inert gas, the reaction was allowed to proceed for 7 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain an emulsion polymer stock solution with a solid content of approximately 32%.

[0085] By adding the above-obtained emulsion polymer stock solution and conventional additives in different proportions, a residue-free slickwater fracturing fluid for horizontal well volume fracturing can be obtained, as shown in Table 7.

[0086] 0.8% of the residue-free slickwater fracturing fluid concentrate, 1.5% of the fracturing drainage agent, 6.8% of the anti-swelling agent, and 0.02% of the gel breaker are uniformly dissolved in water and stirred to obtain the residue-free slickwater fracturing fluid for volume fracturing.

[0087] Table 8 Performance test data of residue-free slickwater fracturing fluid (by weight percentage)

[0088] Adhesion time 4S Drag reduction rate 79％ Gel breaking effect 0mpa.s

[0089] As can be seen from Table 8, the residue-free slickwater fracturing fluid can quickly build viscosity, completely break gel, has no residue, is easy to flow back, has low damage to the formation, and does not require advance fluid preparation, meeting the requirements of continuous mixing on-site for volume fracturing construction in tight low-permeability reservoirs.

[0090] Example 3:

[0091] The residue-free slickwater fracturing fluid for volume fracturing in this embodiment, wherein the aqueous solution and oil solution of the emulsion polymer stock solution are as follows:

[0092] Table 9 Aqueous solution composition of emulsion polymer stock solution (by weight percentage)

[0093] Sodium dodecylbenzenesulfonate 11％ Hexadecyldimethylammonium chloride 0.4％ N-hydroxymethyl acrylamide 7％ 5% citric acid to adjust pH 7 The balance is water

[0094] Table 10 Composition of oil solution of emulsion polymer stock solution (by weight percentage)

[0095] Sorbitan monostearate 3％ polyethylene glycol 0.05％ The balance is diesel

[0096] Table 11 Composition of Residue-Free Slickwater Fracturing Fluid (by Weight Percentage)

[0097] Emulsion polymer stock solution 0.8％ Fracturing aid: polyether modified polysiloxane 1.5％ Anti-swelling agent: behenyltrimethylammonium chloride 6.8％ Gel breaker: ammonium persulfate 0.02％

[0098] An aqueous solution and an oil solution were prepared according to the proportions in Tables 9 and 10, respectively; the aqueous solution and the oil solution were mixed in a mass ratio of 2:5, 99.99% pure nitrogen was introduced, and the temperature was raised to 78° C. for at least 38 minutes. After stirring for 35 minutes, potassium permanganate as an initiator was added. The nitrogen was stopped and the reaction was allowed to proceed for 7 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain an emulsion polymer stock solution with a solid content of approximately 40%.

[0099] The above-obtained emulsion polymer stock solution and additives were mixed in a certain ratio to obtain the acidic slickwater for volume fracturing, as shown in Table 11.

[0100] 0.8% of the residue-free slickwater fracturing fluid concentrate, 1.5% of the fracturing drainage agent, 6.8% of the anti-swelling agent, and 0.02% of the gel breaker are uniformly dissolved in water and stirred to obtain the residue-free slickwater fracturing fluid for volume fracturing.

[0101] Table 12 Performance test data of residue-free slickwater fracturing fluid.

[0102] Adhesion time 8S Drag reduction rate 82％ Gel breaking effect 0mpa.s

[0103] As can be seen from Table 12, the residue-free slickwater fracturing fluid can quickly build viscosity, completely break gel, has no residue, is easy to flow back, has low damage to the formation, and does not require advance fluid preparation, meeting the requirements of continuous mixing on-site for volume fracturing construction in tight low-permeability reservoirs.

[0104] Example 4:

[0105] The residue-free slickwater fracturing fluid for volume fracturing in this embodiment, wherein the aqueous solution and oil solution of the emulsion polymer stock solution are as follows:

[0106] Table 13 Aqueous solution composition of emulsion polymer stock solution (by weight percentage)

[0107] Sodium p-vinylbenzenesulfonate 0.3％ 2,3-Epoxypropyltrimethylammonium chloride 10.5％ Octadecyl methacrylate 3％ Sodium hydroxide to adjust pH 8 The balance is water

[0108] Table 14 Composition of oil solution of emulsion polymer stock solution (by weight percentage)

[0109] Sorbitan monostearate 0.3％ Sodium Cocoyl Isethionate 2.5％ The balance is white oil

[0110] Table 15 Residue-free slickwater fracturing fluid composition (by weight percentage)

[0111] Emulsion polymer stock solution 0.2％ Fracturing aid: sodium dodecylbenzenesulfonate 9.0％ Anti-swelling agent: 2,3-epoxypropyltrimethylammonium chloride 1.2％ Gel breaker: potassium persulfate 0.08％

[0112] An aqueous solution and an oil solution were prepared according to the proportions in Tables 13 and 14, respectively; the aqueous solution and the oil solution were mixed in a mass ratio of 5:2, 99.99% pure nitrogen was introduced, and the temperature was raised to 96° C. for at least 34 minutes. After stirring for 29 minutes, potassium thiosulfate as an initiator was added. After stopping the nitrogen introduction, the reaction was allowed to proceed for 7.5 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain a fracturing fluid emulsion with a solid content of approximately 36%.

[0113] The above-obtained emulsion stock solution and additives were mixed in a certain ratio to obtain the acidic slickwater for volume fracturing, as shown in Table 15.

[0114] 0.2% of the residue-free slickwater fracturing fluid concentrate, 9% of the fracturing drainage agent, 1.2% of the anti-swelling agent and 0.08% of the gel breaker are uniformly dissolved in water and stirred to obtain the residue-free slickwater fracturing fluid for volume fracturing.

[0115] Table 16 Performance test data of residue-free slickwater fracturing fluid

[0116] Adhesion time 3S Drag reduction rate 88％ Gel breaking effect 0mpa.s

[0117] As can be seen from Table 16, the residue-free slickwater fracturing fluid can quickly build viscosity, completely break gel, has no residue, is easy to flow back, has low damage to the formation, and does not require advance fluid preparation, meeting the requirements of continuous mixing on-site for volume fracturing construction in tight low-permeability reservoirs.

[0118] The above-described embodiments are only preferred embodiments of the present invention, and are not intended to be all feasible embodiments of the present invention. Any obvious modifications made by a person skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. A residue-free slickwater fracturing fluid, characterized in that: Including anionic monomers, cationic monomers, nonionic monomers, water, oil, emulsifiers, co-emulsifiers, fracturing aids, anti-swelling agents, and gel breakers.

2. The residue-free slickwater fracturing fluid according to claim 1, characterized in that: The aqueous solution containing anionic monomers, cationic monomers and nonionic monomers, with the total weight thereof being 100%, comprises: Anionic monomer 0.3%~11% Cationic monomer 0.4%~10.5% Nonionic monomer 3% to 7% and the remainder of water.

3. The residue-free slickwater fracturing fluid according to claim 1, characterized in that: The oil solution containing emulsifier and co-emulsifier, with its total weight as 100%, includes: Emulsifier 0.3% to 3% Co-emulsifier 0.05%~2.5% and the remaining oil.

4. The residue-free slickwater fracturing fluid according to claim 1, characterized in that: The anionic monomer is one or more of sodium acrylate, sodium dodecylbenzenesulfonate, and sodium p-vinylbenzenesulfonate.

5. The residue-free slickwater fracturing fluid according to claim 1, characterized in that: The cationic monomer is one or more of hexadecyldimethylammonium chloride, dodecyltrimethylammonium bromide, and 2,3-epoxypropyltrimethylammonium chloride.

6. The residue-free slickwater fracturing fluid according to claim 1, characterized in that: The nonionic monomer is one or more of N-hydroxymethyl acrylamide, octadecyl methacrylate, and dimethylaminoethyl methacrylate.

7. The residue-free slickwater fracturing fluid according to claim 1, characterized in that: The emulsifier is a mixture of one or more of N-methyldiethanolamine, sorbitan monostearate, polyglycerol fatty acid ester, and polypropylene glycol.

8. The residue-free slickwater fracturing fluid according to claim 1, characterized in that: The auxiliary emulsifier is a mixture of one or more of polyethylene glycol, oleic acid diethanolamide, tetradecyl alcohol polyoxyethylene ether, and sodium cocoyl isethionate.

9. The residue-free slickwater fracturing fluid according to claim 1, characterized in that: The oil is a mixture of one or more of diesel, gasoline, white oil and kerosene.

10. The residue-free slickwater fracturing fluid according to claim 1, characterized in that: The fracturing drainage agent is one or more of a fluorocarbon drainage agent, a polyether-modified polysiloxane, and sodium dodecylbenzene sulfonate.

11. The residue-free slickwater fracturing fluid according to claim 1, characterized in that: The anti-swelling agent is one or more of 3-chloro-2-hydroxypropyltrimethylammonium chloride, behenyltrimethylammonium chloride, 2,3-epoxypropyltrimethylammonium chloride, and polydimethyldiallyl ammonium chloride.

12. The residue-free slickwater fracturing fluid according to claim 1, characterized in that: The fracturing breaker is one or more of ammonium persulfate, sodium persulfate, and potassium persulfate.

13. The residue-free slickwater fracturing fluid according to claim 1, characterized in that: The drainage aid is one or more of polyether modified polysiloxane and sodium dodecylbenzene sulfonate.

14. A method for preparing a residue-free fracturing fluid emulsion polymer solution, characterized in that: The steps include: (1) adding anionic monomers, cationic monomers, and nonionic monomers to water in proportion; adjusting the pH value of the solution to obtain an aqueous solution; (2) adding an emulsifier and a co-emulsifier to the oil in proportion to obtain an oil solution; (3) The aqueous solution and the oil solution are mixed in proportion, nitrogen is introduced, and the temperature is raised to 45-96°C; (4) Add initiator, stop nitrogen flow after initiation, and react to obtain emulsion polymerization stock solution.

15. The method for preparing a residue-free fracturing fluid emulsion polymer stock solution according to claim 14, characterized in that: Step (1) is to adjust the pH value of the solution to 6.5-8.

16. The method for preparing a residue-free fracturing fluid emulsion polymer stock solution according to claim 14, characterized in that: Step (4) is to heat the mixture to 90° C. in step (3) for at least 45 minutes, stir the mixture for 30 minutes, add the initiator, stop the nitrogen flow, and react for 2-20 hours to obtain the acidic slick water stock solution.

17. The method for preparing a residue-free fracturing fluid emulsion polymer stock solution according to claim 14, characterized in that: The initiator is a mixture of one or more of ammonium persulfate, sodium bisulfite, potassium thiosulfate, hydrogen peroxide, and potassium permanganate.