Multifunctional fluorine-containing self-crosslinking viscosifier for fracturing and preparation method thereof

Abstract

The present application relates to oil and gas exploitation technology field, it is a kind of multifunctional fracturing fluorine-containing self-crosslinking thickening agent and its preparation method, white oil, Span 80 and Tween 80 are mixed and stirred uniformly, obtain the first mixed solution;Acrylamide, acrylic acid, styrene sulfonic acid, fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X are simultaneously added to deionized water to obtain the second mixed solution;Sodium bisulfite is added to the second mixed solution, then sodium hydroxide is added dropwise into the first mixed solution, and nitrogen is introduced, to obtain mixed emulsion;Ammonium persulfate is added to the mixed emulsion, continuous stirring and nitrogen is introduced and reacted, to obtain multifunctional fracturing fluorine-containing self-crosslinking thickening agent.The present application is simple in operation, reaction is easy to control, the yield of product obtained is high, and it is multifunctional environment-friendly thickening agent, has strong thickening performance, temperature resistance and salt resistance, wetting performance, cleanup performance, and can be mixed on line, realizes slickwater glue liquid integration.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas exploitation, and is a multifunctional fracturing fluorine-containing self-crosslinking thickening agent and a preparation method thereof. BACKGROUND

[0002] The volume reconstruction process requires that the fracturing fluid has low friction and high sand-carrying performance to maximize the complexity of the fracture and the reconstruction volume. However, guanidium gum thickening agents account for about 90% of the total amount of water-based fracturing fluid thickening agents, but their prices fluctuate greatly due to factors such as production and origin, and the natural plant gum fracturing fluid has poor shear resistance and high pumping friction.

[0003] Polymer fracturing fluid has poor shear recovery and poor sand-carrying performance; hydrophobic associated polyacrylamide (HAPAM) has attracted great attention due to its excellent comprehensive performance, but its water solubility, viscosity and temperature resistance need to be further improved when used as a fracturing fluid.

[0004] In the preparation of HAPAM, selecting a suitable hydrophobic monomer is crucial to synthesizing HAPAM with excellent performance. The conventional hydrophobic monomer for hydrophobic modification of HAPAM mainly focuses on carbon-hydrogen hydrophobic monomers. Currently, the hydrophobic monomers mainly include long-chain cationic, long-chain anionic and long-chain nonionic monomers. These monomers are mainly synthesized in the laboratory, and have unstable yield and performance and high cost, which increases the difficulty of industrial production of the product.

[0005] Compared with conventional hydrophobic monomers, fluorine-containing hydrophobic monomers have stronger hydrophobicity, and the synthesized polymers have stronger hydrophobic association. Currently, the synthesis of fluorine-containing hydrophobic associated polyacrylamide (FAPAM) is complicated, and the commonly used fluorocarbon raw materials perfluorooctyl carboxylic acid and perfluorooctyl sulfonic acid have long fluorocarbon chains, which causes degradation difficulty and persistent biological accumulation, limiting their application in oilfields. SUMMARY

[0006] The present application provides a multifunctional fracturing fluorine-containing self-crosslinking thickening agent and a preparation method thereof, which overcomes the shortcomings of the prior art and effectively solves the problems of complicated preparation process, long fluorocarbon chain causing degradation difficulty and persistent biological accumulation of the existing fracturing fluid thickening agent.

[0007] One of the technical solutions of the present application is achieved by the following measures: a multifunctional fracturing fluorine-containing self-crosslinking thickening agent, the chemical structural formula of which is

[0008] .

[0009] The following is a further optimization or / and improvement of the above-mentioned one of the technical solutions:

[0010] The above preparation method is as follows: First, mix and stir the required amounts of white oil, Span 80, and Tween 80 to obtain a first mixed solution; Second, simultaneously add 40% to 50% acrylamide, 40% to 50% acrylic acid, 5% to 15% styrene sulfonic acid, and 0.2% to 0.5% fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X to deionized water, mix and stir to obtain a second mixed solution; Third, add the required amount of sodium bisulfite to the second mixed solution, stir to obtain a second mixed solution, then add sodium hydroxide to adjust the pH to 7.0, add it dropwise to the first mixed solution, and purge with nitrogen to obtain a uniform mixed emulsion; Fourth, add the required amount of ammonium persulfate to the mixed emulsion, continue stirring and purging with nitrogen, and react at a reaction temperature of 50°C for 3 to 4 hours to obtain a multifunctional fracturing fluorinated self-crosslinking thickener.

[0011] In the first step above, the mass ratio of white oil, Span 80, and Tween 80 is 40:4:1.

[0012] In the first step above, the stirring rate is 1000 r / min and the stirring time is 10 min to 15 min.

[0013] In the second step above, the mass percentage of the monomer in the second mixed solution is 20% to 30%; or / and in the third step, the mass percentage of sodium bisulfite is 0.02%; or / and in the fourth step, the mass percentage of ammonium persulfate is 0.15%.

[0014] The chemical structural formula of the above-mentioned fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X is as follows: .

[0015] The above-mentioned fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X was prepared according to the following steps: First, a mixture of N,N-dimethylpropylenediamine and diethyl ether was added to a container, and then perfluorohexanoic acid was slowly added to the container using acetone-ethanol as a solvent. Nitrogen gas was then introduced to obtain a mixed solution. Second, the mixed solution was reacted at 28°C to 32°C for 2.5 to 3.5 hours to obtain a first reaction solution. Third, when the first reaction solution was heated to 75°C to 85°C, a required amount of allyl chloride was added dropwise, and the reaction was continued for 3.5 to 4.5 hours to obtain a second reaction solution. Fourth, the solvent in the second reaction solution was evaporated to obtain the fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X.

[0016] The molar ratio of the above-mentioned N-dimethylpropanediamine to perfluorohexanoic acid is 1:1.

[0017] The second technical scheme of the present application is realized through the following measures: a preparation method of a multifunctional fluorine-containing self-crosslinking thickening agent for fracturing, which is carried out according to the following steps: first, a required amount of white oil, Span 80 and Tween 80 are mixed and stirred uniformly to obtain a first mixed solution; second, a molar fraction of 40% to 50% of acrylamide, a molar fraction of 40% to 50% of acrylic acid, a molar fraction of 5% to 15% of styrene sulfonic acid and a molar fraction of 0.2% to 0.5% of fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X are simultaneously added to deionized water, and after being mixed and stirred uniformly, a second mixed solution is obtained; third, a required amount of sodium bisulfite is added to the second mixed solution, after being stirred uniformly, sodium hydroxide is added, and when the pH value is adjusted to 7.0, it is added dropwise into the first mixed solution, and nitrogen is introduced to obtain a uniform mixed emulsion; fourth, a required amount of ammonium persulfate is added to the mixed emulsion, continuous stirring and nitrogen introduction are carried out, and under the condition that the reaction temperature is 50 DEG C, the reaction is carried out for 3h to 4h to obtain a multifunctional fluorine-containing self-crosslinking thickening agent for fracturing.

[0018] The following is a further optimization or / and improvement of the above-mentioned second technical scheme of the application:

[0019] In the above-mentioned first step, the mass ratio of white oil, Span 80 and Tween 80 is 40:4:1; or / and, in the first step, the stirring rate is 1000r / min, and the stirring time is 10min to 15min; or / and, in the second step, the mass concentration of the second mixed solution is 20% to 30%.

[0020] The above-mentioned fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X is prepared according to the following steps: first, a mixture of a required amount of N,N-dimethylpropylenediamine and ether is added to a three-necked flask, then a slow addition of perfluorohexanoic acid is carried out in the three-necked flask with acetone-ethanol as the solvent, and then nitrogen is introduced to obtain a mixed solution, wherein the mass ratio of N-dimethylpropylenediamine to perfluorohexanoic acid is 1:1; second, the mixed solution is reacted at 28 DEG C to 32 DEG C for 2.5h to 3.5h to obtain a first reaction liquid; third, the first reaction liquid is warmed to 75 DEG C to 85 DEG C, a required amount of chloropropene is added dropwise, and after continuous reaction for 3.5h to 4.5h, a second reaction liquid is obtained; fourth, a rotary evaporator is used to remove the solvent in the second reaction liquid to obtain the fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X; or / and, in the third step, the mass percentage content of sodium bisulfite is 0.02%; or / and, in the fourth step, the mass percentage content of ammonium persulfate is 0.15%.

[0021] The present application is simple to operate, the reaction is easy to control, the yield of the obtained product is high, and the product is a multifunctional environment-friendly thickening agent, which has strong thickening performance, temperature resistance, salt resistance, wetting performance and cleanup performance, and can be mixed online to realize the integration of slick water glue, and has the following advantages:

[0022] (1) The fluorocarbon hydrophobic monomer synthesized in this invention has less than 6 carbon atoms, which is non-polluting to the environment and organisms and is an environmentally friendly product.

[0023] (2) The present invention introduces anions and cations into the polymer at the same time, which makes the polymer molecular chain more extended and improves the salt resistance of the polymer. The introduction of quaternary ammonium salt improves the anti-swelling performance, and the introduction of benzene ring structure improves viscoelasticity and temperature resistance.

[0024] (3) The introduction of fluorinated hydrophobic monomers in this invention enhances the hydrophobic association between macromolecular chains, exhibiting obvious viscosity and elasticity, and further enhancing its salt resistance.

[0025] (4) The present invention improves the solubility of the self-crosslinking thickener by increasing the content of acrylic monomer.

[0026] (5) By introducing acrylamide monomers, the present invention releases more hydrophobic groups, which is beneficial to the linear increase of viscosity of self-crosslinking fracturing fluid and can meet the process conditions of real-time pumping and continuous mixing in field applications.

[0027] (6) The fluorocarbon chain in the multifunctional fracturing fluorine self-crosslinking thickener of the present invention has small intermolecular forces. Through the synergistic effect of the two with the hydrocarbon hydrophobic groups, the wettability of the solution is improved, and the oil-water interfacial tension is further reduced. The interfacial tension of the broken gel is low, the backflow rate is high, and there is no need to add additional backflow surfactant.

[0028] (7) The multifunctional fracturing fluorine-containing self-crosslinking thickener of the present invention has multiple functions such as drag reduction, sand carrying and drainage assistance. It is a multi-effect agent, simple to prepare, can be quickly hydrated and thickened, can meet the requirements of online mixing, and can seamlessly switch between slippery water and glue, thereby improving the fracturing construction efficiency. Attached Figure Description

[0029] Appendix Figure 1 The diagram shows the rheological curve of the fracturing fluid, wherein the mass percentage of the multifunctional fracturing fluorine-containing self-crosslinking thickener obtained in Example 11 of this invention is 0.4%.

[0030] Appendix Figure 2 The graph shows the effect of mineralization on the apparent viscosity of the fracturing fluid. In this fracturing fluid, the mass percentage of the multifunctional fracturing fluorine-containing self-crosslinking thickener obtained in Example 11 of this invention is 0.4%.

[0031] Appendix Figure 3 The diagram shows the rheological curve of the fracturing fluid, wherein the mass percentage of the multifunctional fracturing fluorine-containing self-crosslinking thickener obtained in Example 12 of this invention is 0.5%.

[0032] Appendix Figure 4Figure 2 is a graph showing the effect of salinity on the apparent viscosity of a fracturing fluid containing 0.5% by mass of the multifunctional fluorine-containing self-crosslinking thickening agent obtained in Example 12. DETAILED DESCRIPTION

[0033] The present application is not limited by the following examples, and the specific embodiments can be determined according to the technical solutions of the present application and the actual situation. The various chemical reagents and chemical products mentioned in the present application are commonly known and used in the prior art unless otherwise specified. The percentages in the present application are mass percentages unless otherwise specified. The solutions in the present application are aqueous solutions with water as the solvent unless otherwise specified. For example, a hydrochloric acid solution is an aqueous hydrochloric acid solution. The normal temperature and room temperature in the present application generally refer to a temperature of 15°C to 25°C, which is generally defined as 25°C.

[0034] The present application will be further described below in conjunction with examples:

[0035] Example 1: The multifunctional fluorine-containing self-crosslinking thickening agent is characterized by the chemical structural formula

[0036] .

[0037] Example 2: As an optimization of the above-mentioned examples, it is prepared according to the following method: In the first step, the required amount of white oil, Span 80 and Tween 80 are mixed and stirred uniformly to obtain a first mixed solution; in the second step, a molar fraction of 40% to 50% of acrylamide, a molar fraction of 40% to 50% of acrylic acid, a molar fraction of 5% to 15% of styrene sulfonic acid, and a molar fraction of 0.2% to 0.5% of fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X are simultaneously added to deionized water, and after being mixed and stirred uniformly, a second mixed solution is obtained; in the third step, the required amount of sodium bisulfite is added to the second mixed solution, stirred uniformly, and then sodium hydroxide is added, and when the pH value is adjusted to 7.0, it is added dropwise into the first mixed solution, and nitrogen is introduced to obtain a uniform mixed emulsion; in the fourth step, the required amount of ammonium persulfate is added to the mixed emulsion, and continuous stirring and nitrogen introduction are carried out under the condition of a reaction temperature of 50°C for 3h to 4h to obtain the multifunctional fluorine-containing self-crosslinking thickening agent for fracturing.

[0038] In the present application, the molar fraction of acrylamide, acrylic acid, styrene sulfonic acid and fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X added refers to the molar fraction of acrylamide, acrylic acid, styrene sulfonic acid and fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X in the total monomer amount of the mixture of acrylamide, acrylic acid, styrene sulfonic acid and fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X.

[0039] Example 3: As an optimization of the above-mentioned examples, in the first step, the mass ratio of white oil, Span 80 and Tween 80 is 40:4:1.

[0040] Example 4: As an optimization of the above-mentioned examples, in the first step, the stirring rate is 1000 r / min, and the stirring time is 10 min to 15 min.

[0041] Example 5: As an optimization of the above-mentioned examples, in the second step, the mass percentage of the monomer in the second mixed solution is 20% to 30%; or / and, in the third step, the mass percentage of sodium bisulfite is 0.02%; or / and, in the fourth step, the mass percentage of ammonium persulfate is 0.15%.

[0042] Example 6: The chemical structural formula of the fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X is .

[0043] Example 7: As an optimization of the above-mentioned examples, the fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X is prepared according to the following steps: in the first step, a three-necked flask is added with a mixture of a required amount of N, N-dimethylpropylene diamine and diethyl ether, then a required amount of perfluorohexanoic acid is slowly added to the three-necked flask with acetone-ethanol as the solvent, and nitrogen is introduced to obtain a mixed solution; in the second step, the mixed solution is reacted at 28°C to 32°C for 2.5 h to 3.5 h to obtain a first reaction solution; in the third step, the first reaction solution is heated to 75°C to 85°C, a required amount of chloropropene is added dropwise, and the reaction is continued for 3.5 h to 4.5 h to obtain a second reaction solution; in the fourth step, a rotary evaporator is used to remove the solvent in the second reaction solution to obtain the fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X.

[0044] Example 8: As an optimization of the above-mentioned examples, the molar ratio of N-dimethylpropylene diamine to perfluorohexanoic acid is 1:1.

[0045] Embodiment 9: the preparation method of the multifunctional fluorine-containing self-crosslinking thickening agent for fracturing is carried out according to the following steps: in the first step, a required amount of white oil, Span 80 and Tween 80 are mixed and stirred uniformly to obtain a first mixed solution; in the second step, acrylamide with a mole fraction of 40% to 50%, acrylic acid with a mole fraction of 40% to 50%, styrene sulfonic acid with a mole fraction of 5% to 15% and fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X with a mole fraction of 0.2% to 0.5% are simultaneously added into deionized water, and a second mixed solution is obtained after uniform mixing and stirring; in the third step, 0.02% of sodium bisulfite is added into the second mixed solution, and after uniform stirring, sodium hydroxide is added, and when the pH value is adjusted to 7.0, it is added dropwise into the first mixed solution, and nitrogen is introduced to obtain a uniform mixed emulsion; in the fourth step, 0.15% of ammonium persulfate is added into the mixed emulsion, and stirring and nitrogen introduction are continuously carried out, and the reaction is carried out at a reaction temperature of 50 ℃ for 3 h to 4 h to obtain the multifunctional fluorine-containing self-crosslinking thickening agent for fracturing.

[0046] Embodiment 10: the preparation method of the multifunctional fluorine-containing self-crosslinking thickening agent for fracturing is carried out according to the following steps: in the first step, a required amount of white oil, Span 80 and Tween 80 are mixed and stirred uniformly to obtain a first mixed solution; in the second step, acrylamide with a mole fraction of 40% or 50%, acrylic acid with a mole fraction of 40% or 50%, styrene sulfonic acid with a mole fraction of 5% or 15% and fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X with a mole fraction of 0.2% or 0.5% are simultaneously added into deionized water, and a second mixed solution is obtained after uniform mixing and stirring; in the third step, 0.02% of sodium bisulfite is added into the second mixed solution, and after uniform stirring, sodium hydroxide is added, and when the pH value is adjusted to 7.0, it is added dropwise into the first mixed solution, and nitrogen is introduced to obtain a uniform mixed emulsion; in the fourth step, 0.15% of ammonium persulfate is added into the mixed emulsion, and stirring and nitrogen introduction are continuously carried out, and the reaction is carried out at a reaction temperature of 50 ℃ for 3 h or 4 h to obtain the multifunctional fluorine-containing self-crosslinking thickening agent for fracturing.

[0047] The multifunctional fluorine-containing self-crosslinking thickening agent for fracturing obtained according to the present application can be prepared according to the existing known preparation method of fracturing fluid with a mass percentage of 0.4% to 0.5%, and a multifunctional fracturing fluid with salt resistance, temperature resistance, reservoir wettability change and cleanup aid can be obtained.

[0048] Embodiment 11: The multifunctional fluorine-containing self-crosslinking thickening agent for fracturing is prepared by the following method: in the first step, white oil, Span 80 and Tween 80 are mixed in a mass ratio of 40:4:1 and stirred uniformly to obtain a first mixed solution; in the second step, acrylamide with a mole fraction of 50%, acrylic acid with a mole fraction of 40%, styrene sulfonic acid with a mole fraction of 9.6%, and fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X with a mole fraction of 0.4% are simultaneously added into deionized water, and after being mixed and stirred uniformly, a second mixed solution is obtained, wherein the mass percentage content of the fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X in the second mixed solution is 30%; in the third step, 0.02% of sodium bisulfite is added into the second mixed solution, and after being stirred uniformly, sodium hydroxide is added, and when the pH value is adjusted to 7.0, it is added dropwise into the first mixed solution, and nitrogen is introduced to obtain a uniform mixed emulsion; in the fourth step, 0.15% of ammonium persulfate is added into the mixed emulsion, and stirring and nitrogen introduction are continuously performed, and the reaction is performed at a reaction temperature of 50℃ for 4h to obtain the multifunctional fluorine-containing self-crosslinking thickening agent for fracturing, wherein the fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X is prepared by the following steps: in the first step, a mixture of N,N-dimethylpropylenediamine and ethyl ether is added into a three-necked flask with stirring and condensing devices, then full-fluorohexanoic acid is slowly added into the three-necked flask with acetone-ethanol as a solvent, and then nitrogen is introduced to obtain a mixed solution, wherein the molar ratio of N,N-dimethylpropylenediamine to full-fluorohexanoic acid is 1:1; in the second step, the mixed solution is reacted at 30℃ for 3h to obtain a first reaction liquid; in the third step, the first reaction liquid is heated to 80℃, and a required amount of chloropropene is added dropwise, and after being continuously reacted for 4h, a second reaction liquid is obtained; in the fourth step, a rotary evaporator is used to remove the solvent in the second reaction liquid to obtain the fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X.

[0049] The multifunctional fluorine-containing self-crosslinking thickening agent for fracturing obtained according to Embodiment 11 of the present application has a rheological property as shown in Table 1, wherein the multifunctional fracturing fluid is prepared according to a conventional preparation method of a fracturing fluid in the prior art, the mass percentage content of the multifunctional fluorine-containing self-crosslinking thickening agent for fracturing is 0.4%, and the rheological property is measured at 100℃ and 170s -1 Figure 1 Figure 2 Figure 1 Figure 2 ​​​​It can be seen that the apparent viscosity is maintained at 60 m Pa·s after shearing for 120 min; and the apparent viscosity is greater than 55 m Pa·s within the salinity of 5000 mg / L. Meanwhile, the static sand suspension experiment is conducted on the fracturing fluid prepared by using the multifunctional fluorine-containing self-crosslinking thickening agent for fracturing, and the result shows that there is no obvious sedimentation for 2 h; the viscosity of the broken gel is 2.0 m Pa·s after adding 0.05% of ammonium persulfate; and the surface tension and the interfacial tension of the broken gel are 23.0 mN / m and 1.021 mN / m respectively.

[0050] In the embodiment 12, the multifunctional fluorine-containing self-crosslinking thickening agent for fracturing is prepared by the following method: in the first step, white oil, Span 80 and Tween 80 are mixed and stirred uniformly at a mass ratio of 40:4:1 to obtain a first mixed solution; in the second step, acrylamide with a mole fraction of 40%, acrylic acid with a mole fraction of 50%, styrene sulfonic acid with a mole fraction of 9.6% and fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X with a mole fraction of 0.4% are simultaneously added into deionized water, and a second mixed solution is obtained after uniform mixing, wherein the mass percentage of the fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X in the second mixed solution is 30%; in the third step, 0.02% of sodium bisulfite is added into the second mixed solution, and after uniform stirring, sodium hydroxide is added, and then the first mixed solution is added dropwise when the pH value is adjusted to 7.0, and nitrogen is introduced to obtain a uniform mixed emulsion; in the fourth step, 0.15% of ammonium persulfate is added into the mixed emulsion, and the stirring and nitrogen introduction are continuously conducted, and the reaction is conducted at a reaction temperature of 50℃ for 4 h to obtain the multifunctional fluorine-containing self-crosslinking thickening agent for fracturing, wherein the fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X is prepared by the following steps: in the first step, a mixture of N, N-dimethylpropylene diamine and ether is added into a three-necked flask with stirring and condensing device, then full-fluorohexanoic acid is slowly added into the three-necked flask with acetone-ethanol as a solvent, and then nitrogen is introduced to obtain a mixed solution, wherein the amount-of-substance ratio of N, N-dimethylpropylene diamine to full-fluorohexanoic acid is 1:1; in the second step, the mixed solution is reacted at 30℃ for 3 h to obtain a first reaction liquid; in the third step, the first reaction liquid is heated to 80℃, and then a required amount of chloropropene is added dropwise, and the reaction is continuously conducted for 4 h to obtain a second reaction liquid; in the fourth step, a rotary evaporator is used to remove the solvent in the second reaction liquid to obtain the fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X.

[0051] According to the multifunctional fluorine-containing self-crosslinking thickening agent for fracturing obtained in the embodiment 12, the multifunctional fracturing fluid is prepared according to the conventional preparation method of the fracturing fluid in the prior art, and the multifunctional fracturing fluid is subjected to the shear test at 100℃ and 170 s -1 Figure 3 and​Figure 4 The apparent viscosity is kept at 75 mPa·s after shearing for 120 min; and the apparent viscosity is greater than 65 mPa·s within the salinity of 5000 mg / L. Figure 3 and Figure 4 It can be seen that the apparent viscosity is kept at 75 mPa·s after shearing for 120 min; and the apparent viscosity is greater than 65 mPa·s within the salinity of 5000 mg / L. Meanwhile, the static sand suspension experiment is conducted on the fracturing fluid prepared by the multifunctional fluorine-containing self-crosslinking thickening agent, and the result shows that there is no obvious settlement for 2 h; the viscosity of the gel breaking fluid is 2.1 mPa·s after adding 0.05% ammonium persulfate; and the surface tension and the interfacial tension of the gel breaking fluid are 23.0 mN / m and 1.022 mN / m respectively.

[0052] In summary, the present application has the advantages of simple operation, easy control of reaction, high yield of product, and the obtained product is a multifunctional environment-friendly thickening agent with strong thickening performance, temperature resistance, salt resistance, wetting performance, cleanup performance, and online mixing, realizing the integration of slick water and gel.

[0053] The above technical features constitute the embodiments of the present application, which have strong adaptability and implementation effect, and can increase or decrease unnecessary technical features according to actual needs to meet the needs of different situations.

Claims

1. A multifunctional fluorinated self-crosslinking environmentally friendly thickener for fracturing, characterized in that... The chemical structural formula is ， The solution was prepared according to the following method: First, white oil, Span 80, and Tween 80 were mixed and stirred until homogeneous to obtain a first mixed solution; Second, 40% to 50% acrylamide, 40% to 50% acrylic acid, 5% to 15% styrene sulfonic acid, and 0.2% to 0.5% fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X were simultaneously added to deionized water and stirred until homogeneous to obtain a second mixed solution; Third, sodium bisulfite was added to the second mixed solution and stirred until homogeneous, then sodium hydroxide was added to adjust the pH to 7.0 and added dropwise to the first mixed solution, while nitrogen gas was introduced to obtain a homogeneous mixed emulsion; The fourth step involves adding ammonium persulfate to the mixed emulsion, continuously stirring and introducing nitrogen gas, and reacting at a reaction temperature of 50°C for 3 to 4 hours to obtain a multifunctional fracturing fluorine-containing self-crosslinking environmentally friendly thickener.

2. The multifunctional fluorinated self-crosslinking environmentally friendly thickener for fracturing according to claim 1, characterized in that... In the first step, the mass ratio of white oil, Span 80, and Tween 80 is 40:4:

1.

3. The multifunctional fluorinated self-crosslinking environmentally friendly thickener for fracturing according to claim 1 or 2, characterized in that... In the first step, the stirring rate is 1000 r / min and the stirring time is 10 min to 15 min.

4. The multifunctional fracturing fluorine-containing self-crosslinking environmentally friendly thickener according to claim 3, characterized in that... In the second step, the monomer content in the second mixed solution is 20% to 30% by mass; or / and in the third step, the sodium bisulfite content is 0.02% by mass; or / and in the fourth step, the ammonium persulfate content is 0.15% by mass.

5. The multifunctional fluorinated self-crosslinking environmentally friendly thickener for fracturing according to claim 1, 2, or 4, characterized in that... The chemical structural formula of the fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X is as follows: 。 6. The multifunctional fracturing fluorine-containing self-crosslinking environmentally friendly thickener according to claim 5, characterized in that... The hydrophobic monomer CF-1X of fluorocarbon cationic quaternary ammonium salt was prepared according to the following steps: First, a mixture of N,N-dimethylpropylenediamine and diethyl ether was added to a container, and then perfluorohexanoic acid was slowly added to the container using acetone-ethanol as a solvent. Nitrogen gas was then introduced to obtain a mixed solution. Second, the mixed solution was reacted at 28°C to 32°C for 2.5 to 3.5 hours to obtain a first reaction solution. Third, when the first reaction solution was heated to 75°C to 85°C, allyl chloride was added dropwise, and the reaction was continued for 3.5 to 4.5 hours to obtain a second reaction solution. Fourth, the solvent in the second reaction solution was evaporated to obtain the hydrophobic monomer CF-1X of fluorocarbon cationic quaternary ammonium salt.

7. The multifunctional fluorinated self-crosslinking environmentally friendly thickener for fracturing according to claim 6, characterized in that... The molar ratio of N,N-dimethylpropanediamine to perfluorohexanoic acid is 1:

1.

8. A method for preparing a multifunctional fluorinated self-crosslinking environmentally friendly thickener for fracturing according to any one of claims 1 to 7, characterized in that... The following steps are performed: First, mix and stir the white oil, Span 80, and Tween 80 to obtain a first mixed solution; Second, simultaneously add 40% to 50% acrylamide, 40% to 50% acrylic acid, 5% to 15% styrene sulfonic acid, and 0.2% to 0.5% fluorocarbon cationic quaternary ammonium salt hydrophobic monomer CF-1X to deionized water, mix and stir to obtain a second mixed solution; Third, add sodium bisulfite to the second mixed solution, stir to obtain a uniform emulsion, then add sodium hydroxide to adjust the pH to 7.0, add it dropwise to the first mixed solution, and purge with nitrogen gas to obtain a uniform mixed emulsion. The fourth step involves adding ammonium persulfate to the mixed emulsion, continuously stirring and introducing nitrogen gas, and reacting at a reaction temperature of 50°C for 3 to 4 hours to obtain a multifunctional fracturing fluorine-containing self-crosslinking environmentally friendly thickener.

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