A kind of slippery water fracturing fluid and its preparation process and fracturing process

Abstract

The present application discloses a slippery water fracturing fluid and its preparation process and fracturing process, belonging to the technical field of fracturing fluid for oil fields. The slippery water fracturing fluid is composed of 0.4-0.9% drag reducer, 0.1-0.2% salt, 0.5-1.0% clay stabilizer, 0.05-0.2% bactericide and the balance is water. The slippery water fracturing fluid of the present application adopts a new type of drag reducer, which can improve the salt tolerance of the fracturing fluid, thereby improving the oil displacement rate while improving the drag reduction rate, thereby achieving the purpose of increasing production.

Description

Technical Field

[0001] The present application relates to a slick water fracturing fluid and a preparation process and a fracturing process thereof, belonging to the technical field of fracturing fluid for oil fields. Background Art

[0002] The slickwater fracturing fluid system used abroad mainly includes drag reducers, clay stabilizers and drag reducers. Since the shale gas depth abroad is relatively shallow, the use of slickwater has a better effect on the development of shale oil and gas, and the friction loss of the pipe string is also less. However, the shale oil and gas depth in my country is relatively deep, and the friction loss of the pipe string is relatively large, so a slickwater fracturing fluid with better drag reduction performance is needed.

[0003] Based on this purpose, the development of slick water fracturing fluid for shale oil and gas in my country has gradually transitioned from borrowing foreign technology to independent research and development. Researchers are committed to developing a slick water system with high drag reduction rate and sand carrying ratio. Among them, the most widely used is polyacrylamide drag reducer, which uses acrylamide as the main structural unit, with ionic structural units and functional monomers added to copolymerize. It can effectively reduce drag and reduce damage to the reservoir.

[0004] However, the current slickwater fracturing fluid has poor salt tolerance, so the fracturing performance is unstable, resulting in reduced recovery rate and difficulty in ensuring a good oil recovery effect. Summary of the invention

[0005] In order to solve the above problems, a slippery water fracturing fluid and a preparation process thereof are provided. The slippery water fracturing fluid adopts a new type of drag reducer, which can improve the salt resistance of the fracturing fluid, thereby improving the drag reduction rate and the oil recovery rate at the same time, thereby achieving the purpose of increasing production.

[0006] According to one aspect of the present application, a slick water fracturing fluid is provided, wherein the slick water fracturing fluid is composed, by weight percentage, of 0.4-0.9% drag reducer, 0.1-0.2% salt, 0.5-1.0% clay stabilizer, 0.05-0.2% fungicide, and the balance is water;

[0007] The molecular structure of the drag reducer is shown in Formula I:

[0008] Formula I;

[0009] Wherein, R1 is selected from ethyl, n-propyl, isopropyl, butyl or pentyl, R2 and R3 are independently selected from one of straight chain or branched alkyl groups containing 1 to 3 carbon atoms, R4 is selected from one of straight chain or branched alkyl groups containing 2 to 5 carbon atoms, R5 is selected from one of straight chain or branched alkyl groups containing 2 to 5 carbon atoms, x and y are independently selected from integers between 10 and 20, z is selected from an integer between 5 and 10, n is selected from an integer between 6 and 12, and m is selected from an integer between 1 and 4.

[0010] The drag reducer used in the above-mentioned slick water fracturing fluid has high salt resistance, temperature resistance and shear resistance, so it can improve the drag reduction rate and return rate during fracturing. Due to the presence of the intermediate segment of the R1 group in the drag reducer, the lubrication effect can be increased, the drag reduction rate and return rate can be further improved, the affinity with crude oil can be increased, and the oil displacement effect can be improved. The drag reducer forms micelles in the fracturing fluid, and automatically demulsifies after encountering crude oil, without the need to add additional demulsifiers, thereby improving the convenience of fracturing operations.

[0011] Optionally, R2 and R3 are both selected from methyl, R4 is selected from propyl, and R5 is selected from n-propyl.

[0012] Optionally, R1 is selected from ethyl and m is selected from 3.

[0013] The values ​​of m and z determine the length of the middle segment group with R1 in the drag reducer. The longer the middle segment, the higher the drag reduction rate but the lower the shear resistance, which will cause a decrease in the flowback rate. Therefore, the above values ​​of m and z can obtain the fracturing fluid with the best comprehensive effect.

[0014] Optionally, the clay stabilizer comprises, by weight, 5-6 parts of a bisindolylmethane compound, 5-6 parts of a quinazolinone compound, 10-15 parts of methanol and 80-85 parts of water.

[0015] The combination of the above-mentioned clay stabilizer and drag reducer can improve the sand carrying capacity of the fracturing fluid, and can enhance the adsorption capacity of clay after combining with hydrogen ions in water, effectively achieve a better anti-swelling effect, and reduce the residue after fracturing operation, thereby further reducing damage to the reservoir.

[0016] The preparation and specific structures of the above-mentioned bisindolylmethane compounds and quinazolinone compounds can be referred to patent CN114106795B.

[0017] Optionally, the clay stabilizer further comprises 3-8 parts of a diquaternary ammonium salt, wherein the diquaternary ammonium salt is obtained by reacting N,N,N',N'-tetramethyl-1,4-butanediamine and a halogenated alkane.

[0018] Generally speaking, after the fracturing fluid is prepared, its stability will deteriorate over time, and it is generally used for fracturing while being prepared. However, for fracturing work with a large amount of liquid, in order to smoothly carry out the fracturing work, it generally takes a long time to prepare the fracturing fluid, and the fracturing effect will decrease due to the deterioration of the stability of the fracturing fluid. The diquaternary ammonium salt added to the clay stabilizer in the present application can increase the affinity of the clay stabilizer and the drag reducer, improve the stability of the fracturing fluid, and thus extend the use time of the fracturing fluid. For fracturing work with a large amount of liquid, more fracturing fluid can be pre-configured for use, and the stability of the fracturing fluid in the formation can also be improved, thereby improving the fracturing effect.

[0019] Furthermore, the diquaternary ammonium salt also has a bactericidal effect and can work in conjunction with a bactericide. At the same time, due to the presence of halogenated alkanes in the diquaternary ammonium salt, in conjunction with a drag reducer, it can increase affinity with crude oil, thereby further improving the oil recovery rate.

[0020] Optionally, the halogenated alkane is selected from a straight or branched halogenated alkane containing 1 to 8 carbon atoms, for example, methyl iodide, methyl chloride, methyl bromide, ethyl iodide, ethyl chloride, ethyl bromide, propyl iodide, propyl chloride, propyl bromide, butyl iodide, butyl chloride, butyl bromide, pentyl iodide, pentyl chloride, pentyl bromide, hexyl iodide, hexyl chloride, hexyl bromide, heptyl iodide, heptyl chloride, heptyl bromide, octyl iodide, octyl chloride, and octyl bromide.

[0021] According to another aspect of the present application, a process for preparing the slick water fracturing fluid described in any one of the above is provided, comprising the following steps:

[0022] (1) dissolving the first monomer and the second monomer in a solvent and polymerizing them in the presence of an initiator to obtain a solution containing a prepolymer;

[0023] (2) adding a third monomer to the solution containing the prepolymer to polymerize again, and obtaining a drag reducer after separation;

[0024] (3) adding salt to water and stirring to dissolve, then adding drag reducer and stirring until dissolved, and finally adding clay stabilizer and fungicide to obtain the slick water fracturing fluid;

[0025] The molecular structure of the first monomer is shown in Formula II:

[0026] Formula II;

[0027] The second monomer is selected from polyethylene glycol diacrylate (CAS No.: 26570-48-9), diethylene glycol diacrylate (CAS No.: 4074-88-8), triethylene glycol diacrylate (CAS No.: 1680-21-3), tetraethylene glycol diacrylate (CAS No.: 17831-71-9), tripropylene glycol diacrylate (CAS No.: 42978-66-5), 3-(3-prop-2-enoyloxy) At least one of propylene glycol (CAS No.: 1026700-18-4), trimer (1,3-propylene glycol) diacrylate (CAS No.: 68901-05-3), dodecyl acrylate (CAS No.: 57472-68-1), polybutylene glycol diacrylate (CAS No.: 19485-03-1), and 1,5-pentanediol diacrylate (CAS No.: 36840-85-4);

[0028] The molecular structure of the third monomer is shown in Formula III:

[0029] Formula III.

[0030] Optionally, the reaction temperature of step (1) is 70-90°C and the reaction time is 4-6h.

[0031] Optionally, the reaction temperature of step (2) is 60-100° C., and the reaction time is 2-4 h.

[0032] Optionally, the molar ratio of the first monomer, the second monomer and the third monomer is (1-2): (0.5-1): (1-2).

[0033] The above reaction temperature and the molar ratio of the raw materials can ensure that the drag reducer of the structure of formula I is obtained, so as to improve the synergistic effect of the drag reducer and other components and improve the fracturing effect.

[0034] Optionally, nitrogen is introduced into the reactions of step (1) and step (2) for protection.

[0035] Optionally, the solvent used in step (1) is at least one selected from hexane, benzene, toluene, xylene, dichloromethane, ether and acetone.

[0036] Optionally, the initiator is at least one of an azo initiator, a persulfate initiator and a peroxide initiator.

[0037] Optionally, the amount of the initiator used is 1-2 wt % of the amount of the first monomer used.

[0038] The preparation method of the first monomer is referred to CN113956863B, which is a prior art and will not be described in detail in this application.

[0039] According to another aspect of the present application, a fracturing process is provided, in which the slick water fracturing fluid described in any one of the above items is used for fracturing.

[0040] The beneficial effects of this application include but are not limited to:

[0041] 1. The slickwater fracturing fluid of the present application is more suitable for the development of shale gas at a deeper depth. The drag reducer has good salt resistance and can cooperate with the clay stabilizer to reduce drag and have a good anti-swelling effect, thereby reducing damage to the reservoir and improving the fracturing stability of the fracturing fluid, thereby increasing the oil recovery rate.

[0042] 2. The slickwater fracturing fluid of the present application has a moderate molecular weight of the drag reducer, which can reduce its adsorption in the reservoir, thereby reducing damage to the reservoir and avoiding clogging of the bottom layer, so as to ensure the smooth progress of subsequent fracturing operations.

[0043] 3. The slickwater fracturing fluid of the present application is simple to prepare and can be prepared online at the construction site, reducing the difficulty of construction operation, and can increase the flowback rate, realize the reuse of the fracturing fluid, and reduce the cost of fracturing production. DETAILED DESCRIPTION

[0044] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0045] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0046] Unless otherwise specified, the method used in the embodiments of the present application is a conventional method in the prior art. The solvent used in the reaction of the first monomer and the second monomer in the following embodiments is selected from at least one of hexane, benzene, toluene, xylene, dichloromethane, ether and acetone, and the solvent used in the reaction of synthesizing the diquaternary ammonium salt is at least one of ethanol, acetone and chloroform. The solvent can be replaced according to demand in the following embodiments, as long as the reaction of the raw materials can be achieved, and it does not constitute a limitation to the present application.

[0047] Example 1

[0048] This embodiment relates to the preparation of a drag reducing agent, comprising the following steps:

[0049] (1) dissolving the first monomer and the second monomer in a solvent, and polymerizing them in the presence of an initiator to obtain a solution containing a prepolymer;

[0050] (2) Adding the third monomer to the solution containing the prepolymer to polymerize again, and then separating to obtain the drag reducer.

[0051] The molecular structure of the first monomer is shown in Formula II:

[0052] Formula II;

[0053] The second monomer is selected from at least one of polyethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, 1,3-propylene glycol diacrylate, 3-(3-prop-2-enoyloxypropoxy)prop-2-enoate, trimer (1,3-propylene glycol) diacrylate, lauryl acrylate, polybutylene glycol diacrylate, and 1,5-pentanediol diacrylate;

[0054] The molecular structure of the third monomer is shown in Formula III:

[0055] Formula III.

[0056] Preferably, the reaction temperature of step (1) is 70-90° C. and the reaction time is 4-6 h.

[0057] Preferably, the reaction temperature of step (2) is 60-100° C., and the reaction time is 2-4 h.

[0058] Preferably, the molar ratio of the first monomer, the second monomer and the third monomer is (1-2): (0.5-1): (1-2).

[0059] The following drag reducer was prepared according to the above preparation method, as follows:

[0060] Drag reducer 1#

[0061] The preparation of the first monomer refers to the monomer A synthesized in Example 1 of the patent CN113956863B, and the preparation of the third monomer also refers to the monomer B used in Example 1 of the patent CN113956863B.

[0062] (1) dissolving the first monomer and tetraethylene glycol diacrylate in a solvent, adding azobisisobutyronitrile accounting for 1 wt % of the first monomer, and polymerizing at 70° C. for 6 h to obtain a solution containing a prepolymer;

[0063] (2) Adding the third monomer to the solution containing the prepolymer, the molar ratio of the first monomer, the second monomer and the third monomer is 2:0.5:1, and polymerizing again at 60°C for 4 hours. After column chromatography separation, a drag reducer 1# is obtained, wherein R1 of the drag reducer 1# is selected from ethyl, R2 and R3 are both selected from methyl, R4 is selected from propyl, R5 is selected from n-propyl, x is 20, y is 10, z is 5, n is 8, and m is 4.

[0064] Drag Reducing Agent 2#

[0065] The preparation of the first monomer refers to the monomer A synthesized in Example 1 of the patent CN113956863B, and the preparation of the third monomer also refers to the monomer B used in Example 1 of the patent CN113956863B.

[0066] (1) dissolving the first monomer and 1,5-pentanediol diacrylate in a solvent, adding azobisisobutyronitrile accounting for 1 wt% of the first monomer, and polymerizing at 90° C. for 4 h to obtain a solution containing a prepolymer;

[0067] (2) Adding the third monomer to the solution containing the prepolymer, the molar ratio of the first monomer, the second monomer and the third monomer is 1:0.5:1, and polymerizing again at 100°C for 2 hours. After column chromatography separation, a drag reducer 2# is obtained, wherein R1 of the drag reducer 2# is selected from pentyl, R2 and R3 are both selected from methyl, R4 is selected from propyl, R5 is selected from n-propyl, x is 10, y is 10, z is 5, n is 8, and m is 1.

[0068] Drag Reducing Agent 3#

[0069] The preparation of the first monomer refers to the monomer A synthesized in Example 1 of the patent CN113956863B, and the preparation of the third monomer also refers to the monomer B used in Example 1 of the patent CN113956863B.

[0070] (1) dissolving the first monomer and triethylene glycol diacrylate in a solvent, adding 1 wt% of azobisisobutyronitrile to the first monomer, and polymerizing at 80° C. for 5 h to obtain a solution containing a prepolymer;

[0071] (2) Adding the third monomer to the solution containing the prepolymer, the molar ratio of the first monomer, the second monomer and the third monomer is 1:1:2, and polymerizing again at 80°C for 3 hours. After column chromatography separation, a drag reducer 3# is obtained, wherein R1 of the drag reducer 3# is selected from ethyl, R2 and R3 are both selected from methyl, R4 is selected from propyl, R5 is selected from n-propyl, x is 10, y is 20, z is 10, n is 8, and m is 3.

[0072] Comparison of drag reducer D1#

[0073] The preparation of the first monomer refers to the monomer A synthesized in Example 1 of the patent CN113956863B, and the preparation of the third monomer also refers to the monomer B used in Example 1 of the patent CN113956863B.

[0074] The difference between this comparative drag reducer and drag reducer 3# is that it does not contain the intermediate segment with R1 group obtained from triethylene glycol diacrylate monomer, that is, z is 0. The preparation method is to dissolve the first monomer and the second monomer in a solvent, add azobisisobutyronitrile accounting for 1wt% of the amount of the first monomer, polymerize at 80°C for 8h, and obtain comparative drag reducer D1# after column chromatography separation.

[0075] Comparison of drag reducer D2#

[0076] The difference between this comparative drag reducer and drag reducer 3# is that the molar ratio of the first monomer, the second monomer and the third monomer is 1:2:2, so z of the comparative drag reducer D2# is 20, and the rest is the same as drag reducer 3#.

[0077] Example 2

[0078] The present embodiment relates to a slick water fracturing fluid and a preparation method thereof, wherein the slick water fracturing fluid is composed of 0.4-0.9% drag reducer, 0.1-0.2% salt, 0.5-1.0% clay stabilizer, 0.05-0.2% fungicide and the balance is water, wherein the clay stabilizer comprises 5-6 parts of bisindolylmethane compounds, 5-6 parts of quinazolinone compounds, 10-15 parts of methanol and 80-85 parts of water by weight. The salt is selected from potassium chloride or sodium salicylate, and the fungicide is selected from formaldehyde, glyoxal or dodecyltrimethylammonium chloride.

[0079] The preparation method is: adding salt to water and stirring to dissolve, then adding drag reducer and stirring until dissolved, and finally adding pre-prepared clay stabilizer and fungicide to obtain the slick water fracturing fluid. The following fracturing fluid is prepared according to the above preparation method, as follows:

[0080] Fracturing fluid 1#

[0081] Prepare a clay stabilizer in advance: dissolve 5 parts of a bisindolylmethane compound and 5 parts of a quinazolinone compound in 10 parts of methanol, stir evenly, and then add 80 parts of water to mix. The bisindolylmethane compound refers to bisindolylmethane compound 1# synthesized in patent CN114106795B, and the quinazolinone compound refers to quinazolinone compound 3# synthesized in patent CN114106795B.

[0082] Add 0.1% potassium chloride to water and stir to dissolve, then add 0.4% drag reducer 1# and stir until dissolved, finally add pre-prepared 1.0% clay stabilizer and 0.05% formaldehyde, mix well to obtain fracturing fluid 1#.

[0083] Fracturing fluid 2#

[0084] Prepare a clay stabilizer in advance: dissolve 6 parts of bisindolylmethane compounds and 6 parts of quinazolinone compounds in 15 parts of methanol, stir evenly, add 85 parts of water and mix, wherein the bisindolylmethane compound refers to bisindolylmethane compound 3# synthesized in patent CN114106795B, and the quinazolinone compound refers to quinazolinone compound 4# synthesized in patent CN114106795B.

[0085] Add 0.2% sodium salicylate to water and stir to dissolve, then add 0.9% drag reducer 2# and stir until dissolved, finally add pre-prepared 0.5% clay stabilizer and 0.2% glyoxal, mix well to obtain fracturing fluid 2#.

[0086] Fracturing fluid 3#

[0087] Prepare a clay stabilizer in advance: dissolve 6 parts of a bisindolylmethane compound and 6 parts of a quinazolinone compound in 15 parts of methanol, stir evenly, and then add 85 parts of water to mix. The bisindolylmethane compound refers to bisindolylmethane compound 5# synthesized in patent CN114106795B, and the quinazolinone compound refers to quinazolinone compound 1# synthesized in patent CN114106795B.

[0088] Add 0.2% potassium chloride to water and stir to dissolve, then add 0.8% drag reducer 3# and stir until dissolved, finally add pre-prepared 0.7% clay stabilizer and 0.1% dodecyltrimethylammonium chloride, mix well to obtain fracturing fluid 3#.

[0089] Fracturing fluid 4#

[0090] The difference between this fracturing fluid and fracturing fluid 3# is that the clay stabilizer also contains 3 parts of diquaternary ammonium salt, which is added to methanol together with a bisindolylmethane compound, wherein the diquaternary ammonium salt is prepared by heating N,N,N',N'-tetramethyl-1,4-butanediamine and iodomethane in a solvent for reflux reaction for 20 hours, removing the solvent, extracting it three times with a mixed solvent of ether and acetonitrile in a volume ratio of 1:1, and then drying it, and the rest is the same as fracturing fluid 3#.

[0091] Fracturing fluid 5#

[0092] The difference between this fracturing fluid and fracturing fluid 3# is that the clay stabilizer also contains 8 parts of diquaternary ammonium salt, which is added to methanol together with bisindolylmethane compounds, wherein the diquaternary ammonium salt is prepared by heating N,N,N',N'-tetramethyl-1,4-butanediamine and bromooctane under reflux for 20 hours in a solvent, removing the solvent, extracting it three times with a mixed solvent of ether and acetonitrile in a volume ratio of 1:1, and then drying it, and the rest is the same as fracturing fluid 3#.

[0093] Comparison of fracturing fluid D1#

[0094] The difference between this comparative fracturing fluid and fracturing fluid 3# is that the drag reducer used is comparative drag reducer D1#, and the rest is the same as fracturing fluid 3#.

[0095] Comparison of fracturing fluid D2#

[0096] The difference between this comparative fracturing fluid and fracturing fluid 3# is that the drag reducer used is comparative drag reducer D2#, and the rest is the same as fracturing fluid 3#.

[0097] Comparison of fracturing fluid D3#

[0098] The difference between this comparative fracturing fluid and fracturing fluid 3# is that the amount of drag reducer used is 1.2%, and the rest is the same as fracturing fluid 3#.

[0099] Comparison of fracturing fluid D4#

[0100] The difference between this comparative fracturing fluid and fracturing fluid 3# is that the amount of clay stabilizer used is 0.2%, and the rest is the same as fracturing fluid 3#.

[0101] Test Example 1

[0102] The heat and shear resistance, sand suspension capacity and damage performance of each fracturing fluid prepared in Example 2 were tested. The test results are shown in Table 1. The test method is as follows:

[0103] 1. Temperature and shear resistance: Use a rheometer at 150°C for 170s -1 The viscosity of the fracturing fluid after shearing for 120 minutes was tested at a shear rate of .

[0104] 2. Sand suspension capacity: Take 20.0g of proppant (20-40 mesh ceramsite proppant) at room temperature and add it to 100.0g of fracturing fluid. After stirring evenly, pour it into a measuring cylinder and measure the time it takes for the proppant to settle to the bottom of the measuring cylinder.

[0105] 3. Damage performance: The experiment was conducted using the tight sandstone gas layer of the Shaximiao Formation in southwestern Sichuan. The permeability of the fracturing fluid prepared with the surfactants of the above embodiments and comparative examples before and after passing through the core was tested, and the damage rate of the fracturing fluid to the core permeability was calculated. The calculation formula for the damage rate is: [(permeability before fracturing - permeability after fracturing) / permeability before fracturing] * 100%.

[0106] Table 1

[0107]

[0108] Test Example 2

[0109] The drag reduction rate, surface tension, anti-swelling rate, viscosity reduction efficiency and oil displacement efficiency of each fracturing fluid obtained in Example 2 were tested respectively according to the petroleum and natural gas industry standards SY / T5107-2016, SY / T5370-2018 and SY / T5971-2016. The test results are shown in Table 2.

[0110] Table 2

[0111]

[0112] According to the above test examples, it can be seen that the fracturing fluid prepared in the present application has strong salt resistance, can effectively reduce drag, improve oil recovery efficiency, increase the return flow rate, and reduce damage to the reservoir.

[0113] According to the comparison between fracturing fluids 4#, 5# and 3#, it can be seen that although the addition of diquaternary ammonium salts to the clay stabilizer causes a moderate decrease in the drag reduction rate, it can improve the anti-swelling rate and oil recovery efficiency and reduce the damage rate. This effect is caused by the fact that diquaternary ammonium salts can increase the fracturing stability of the fracturing fluid.

[0114] According to the comparison between fracturing fluid 3# and comparative fracturing fluids D1# and D2#, it can be seen that when the drag reducer does not contain an intermediate segment with an R1 group, the drag reduction rate, anti-swelling rate and oil recovery efficiency of the fracturing fluid prepared therefrom are significantly reduced, the stability of the fracturing fluid is also reduced, and the damage rate to the reservoir is increased; although the drag reduction rate can be improved by increasing the length of the intermediate segment with an R1 group, the shear resistance is reduced, and the flowback rate and oil recovery efficiency of the fracturing fluid are significantly reduced.

[0115] According to the comparison between the pressure fluid 3# and the comparative fracturing fluids D3# and D4#, it can be seen that the content of drag reducer and clay stabilizer in the fracturing fluid affects the overall fracturing effect of the fracturing fluid. It is not the case that the more drag reducers, the higher the drag reduction rate. When the drag reducer of the comparative fracturing fluid D3# is increased from 0.8% to 1.2%, the drag reduction rate decreases instead. It is inferred that the reason may be that the high content of drag reducer has a great effect with the clay stabilizer and other components, which will reduce the drag reduction effect and the oil displacement efficiency at the same time. When the clay stabilizer of the comparative fracturing fluid D4# is reduced from 0.7% to 0.2%, not only the sand suspension capacity and anti-swelling rate are significantly reduced, but also its drag reduction rate, viscosity reduction rate, oil displacement efficiency and shear resistance are reduced to varying degrees, and the damage rate is also increased, which proves that the clay stabilizer can cooperate with the drag reducer to improve the comprehensive fracturing effect of the fracturing fluid.

[0116] The above is only the embodiment of the present application, and the protection scope of the present application is not limited by these specific embodiments, but is determined by the claims of the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the technical ideas and principles of the present application should be included in the protection scope of the present application.

Claims

1. A slick water fracturing fluid, characterized in that: The slick water fracturing fluid consists of 0.4-0.9% drag reducer, 0.1-0.2% salt, 0.5-1.0% clay stabilizer, 0.05-0.2% fungicide and the balance is water, measured by weight percentage; The clay stabilizer comprises, by weight, 5-6 parts of a bisindolylmethane compound, 5-6 parts of a quinazolinone compound, 10-15 parts of methanol and 80-85 parts of water; The preparation process of the slick water fracturing fluid comprises the following steps: (1) dissolving the first monomer and the second monomer in a solvent and polymerizing them in the presence of an initiator to obtain a solution containing a prepolymer; (2) adding the third monomer to the solution containing the prepolymer to polymerize again, and obtaining the drag reducer after separation, wherein the molar ratio of the first monomer, the second monomer and the third monomer is (1-2): (0.5-1): (1-2); (3) adding salt to water and stirring to dissolve, then adding drag reducer and stirring until dissolved, and finally adding clay stabilizer and fungicide to obtain the slick water fracturing fluid; The molecular structure of the first monomer is shown in Formula II: Formula II; The second monomer is selected from at least one of diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, 1,3-propylene glycol diacrylate, 3-(3-prop-2-enoyloxypropoxy)prop-2-enoate, trimer (1,3-propylene glycol) diacrylate, and 1,5-pentanediol diacrylate; The molecular structure of the third monomer is shown in Formula III: Formula III; Wherein, R2 and R3 are independently selected from one of the straight chain or branched alkyl groups containing 1 to 3 carbon atoms, R4 is selected from one of the straight chain or branched alkylene groups containing 2 to 5 carbon atoms, and R5 is selected from one of the straight chain or branched alkylene groups containing 2 to 5 carbon atoms.

2. The slick water fracturing fluid according to claim 1, characterized in that: The clay stabilizer also includes 3-8 parts of diquaternary ammonium salt, which is obtained by reacting N,N,N',N'-tetramethyl-1,4-butanediamine and halogenated alkane.

3. The slick water fracturing fluid according to claim 1, characterized in that: The reaction temperature of step (1) is 70-90°C and the reaction time is 4-6h.

4. The slick water fracturing fluid according to claim 1, characterized in that: The reaction temperature of step (2) is 60-100°C and the reaction time is 2-4h.

5. A fracturing process, characterized in that: The fracturing process uses the slick water fracturing fluid described in any one of claims 1 to 4 for fracturing.

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