Suspension resistance reducing agent and preparation method and application thereof

Abstract

The invention discloses a suspension resistance reducing agent and a preparation method and application thereof, and belongs to the technical field of oil exploitation. The suspension resistance reducing agent is prepared from the following components in parts by weight: 30 to 40 parts of a mixed copolymer, 1 to 2 parts of a mixed emulsifier, 50 to 60 parts of an oil phase, 0.2 to 0.4 part of nano SiO2, 0.2 to 0.4 part of graphene oxide, 0.5 to 1 part of a stabilizer, 0.5 to 1 part of a surfactant and 0.02 to 0.5 part of a capsule gel breaker. The preparation method comprises the following steps: reacting acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, sodium acrylate and a conjugated compound containing double bonds to obtain a polymer A, mixing the polymer A with a lignin sulfonate-acrylamide copolymer, and drying to obtain a mixed copolymer. Through mutual cooperation of all the components, the suspension resistance reducing agent has temperature resistance, salt resistance, stability, sand carrying, swelling prevention, discharge aiding and resistance reducing performance at the same time, and the convenience of application in a construction site is improved.

Description

TECHNICAL FIELD

[0001] The application relates to a suspension resistance reducer and a preparation method and application thereof, and belongs to the technical field of oil exploitation. BACKGROUND

[0002] At present, during the flow of fluid in a pipeline, certain mechanical energy will be consumed due to the viscosity of the fluid and the formation of eddies. Adding a resistance reducer to the fluid can greatly reduce the resistance during the flow, so that the energy consumption of the pump is greatly reduced. The resistance reducer is the most important additive in the slickwater system, and the slickwater fracturing fluid is the most important liquid system in the shale gas reservoir fracturing operation. Because the fracturing fluid contacts the formation during the fracturing process, the flowback fluid contains a large amount of chloride, organic matter and metal ions Ca 2+ , Mg 2+ , if the flowback fluid is not properly disposed, environmental pollution is easily caused.

[0003] Now many resistance reducers want to achieve the performances of temperature resistance, salt resistance, stability, sand carrying, anti-swelling, cleanup, resistance reduction and the like, and need to be combined with various additives, such as cleanup agents, clay stabilizers, bactericides and crosslinking agents, but the more the types of additives are, the more complex the on-site process is, and the higher the cost is, and compatibility problems may be caused.

[0004] Chinese invention patent CN119432354A discloses a multifunctional free-mixing full-suspension resistance reducer, a preparation method and application thereof, and specifically discloses that the multifunctional free-mixing full-suspension resistance reducer includes the following raw materials in parts by weight: 30-50 parts of partially hydrolyzed polyacrylamide, 35-60 parts of white oil, 2-5 parts of an anionic surfactant, 0-3 parts of a bactericide, 0.5-2 parts of organic clay, 0.5-1.5 parts of an alcohol compound and 1-3 parts of an emulsifier. The full-suspension resistance reducer can realize the functions of salt resistance reduction, sand carrying, anti-swelling, cleanup and sterilization integrally without additional auxiliary agents, and has good application value. However, the resistance reduction rate and the surface viscosity of the multifunctional free-mixing full-suspension resistance reducer obtained by compounding in the above patent are relatively low, the effect of sand carrying is not very ideal due to the low surface viscosity, and the performance and effect of the resistance reducer cannot be well improved only by compounding of various components.

[0005] Therefore, there is an urgent need for a suspension resistance reducer which simultaneously has the performances of temperature resistance, salt resistance, stability, sand carrying, anti-swelling, cleanup and resistance reduction and is easy to be compounded on a construction site. SUMMARY

[0006] In order to solve the above problems, a suspension resistance reducer is provided, the components of which are reasonably compounded, and the suspension resistance reducer simultaneously has the performances of temperature resistance, salt resistance, stability, sand carrying, anti-swelling, cleanup and resistance reduction through mutual cooperation between the components, so that the convenience of application on a construction site is improved.

[0007] According to one aspect of the present application, a suspension resistance reducer is provided, comprising, by weight: 30-40 parts of mixed copolymer, 1-2 parts of mixed emulsifier, 50-60 parts of oil phase, 0.2-0.4 parts of nano-SiO2, 0.2-0.4 parts of graphene oxide, 0.5-1 parts of stabilizer, 0.5-1 parts of surfactant, and 0.02-0.5 parts of capsule breaker; Optionally, the preparation method of the mixed copolymer comprises the following steps: S1: acrylamide, 2-acrylamido-2-methylpropane sulfonic acid, and sodium acrylate are added to deionized water for stirring and mixing to obtain a first mixed solution, a conjugated compound containing a double bond is added to an organic solvent to obtain a second mixed solution, the second mixed solution is added to the first mixed solution, rapid stirring is performed, an initiator is added, the pH is adjusted to neutral, inert gas is introduced, and reaction is performed at 50-70°C for 3-4h, and the polymer A is obtained after removal of the solvent; S2: sodium lignosulfonate is dissolved in water and stirred and mixed uniformly to obtain a sodium lignosulfonate solution, acrylamide and potassium persulfate are added thereto, and reaction is performed at 55-80°C for 4-6h to obtain a sulfonated lignin-acrylamide copolymer; S3: the polymer A is mixed with the sulfonated lignin-acrylamide copolymer, stirring and mixing is performed for 1-2h, and the mixed copolymer is obtained after drying.

[0008] The present application introduces a conjugated structure by reacting 2-acrylamido-2-methylpropane sulfonic acid, acrylamide, sodium acrylate, and a conjugated compound containing a double bond, and then mixing with a sulfonated lignin-acrylamide copolymer to obtain a mixed copolymer. Due to the introduction of the above structure, ion channels can be provided by the sulfonic acid group to improve the conductivity of the mixed copolymer, and electronic transmission can be achieved by the conjugated structure to improve the long-term effectiveness of the resistance reducer. The conjugated system can also enhance the intermolecular interaction, improve the viscosity and stability of the fracturing fluid, reduce the damage of the fracturing fluid to the reservoir, and protect the permeability of the oil and gas layer.

[0009] The introduction of the conjugated structure can also enhance the sand-carrying capacity and temperature resistance of the fracturing fluid, reduce the frictional resistance of the fracturing fluid in the pipeline, and improve the pumping efficiency.

[0010] The sulfonic acid group in the sulfonated lignin-acrylamide copolymer can cooperate with the conjugated structure to conduct electricity when the sulfonated lignin-acrylamide copolymer is mixed with the polymer A.

[0011] Optionally, the weight ratio of the sodium acrylate, acrylamide, 2-acrylamido-2-methylpropane sulfonic acid, and conjugated compound containing a double bond is 1:(20-25):(5-10):(1-2).

[0012] Optionally, the weight ratio of sodium lignosulfonate to acrylamide is 1: (4-8).

[0013] Optionally, the concentration of the sodium lignosulfonate solution is 1-1.5 wt%.

[0014] Optionally, the weight ratio of the polymer A to the sulfonated lignin-acrylamide copolymer is 1: (10-20).

[0015] Mixing the polymer A and the sulfonated lignin-acrylamide copolymer in the above ratio can effectively improve the resistance reduction rate of the resistance reducer, and the sulfonic acid groups in the polymer A and the sulfonated lignin-acrylamide copolymer can also synergistically promote the mixing of the resistance reducer, facilitating the subsequent application of the resistance reducer.

[0016] Optionally, the conjugated compound containing a double bond is a conjugated compound containing a double bond and at least one benzene ring.

[0017] Optionally, the conjugated compound containing a double bond is at least one of 9-vinyl anthracene, 2-vinyl naphthalene, and styrene.

[0018] The conjugated compound containing a double bond can effectively introduce a naphthalene ring, a benzene ring, or an anthracene ring into the resistance reducer system, improve the thermal stability of the resistance reducer, and improve the temperature resistance of the resistance reducer while improving the stability of the resistance reducer, thereby expanding the application range of the resistance reducer.

[0019] Preferably, the initiator is at least one of azobisdimethylammonium diisobutylate hydrochloride, azobisdimethylimidazoline hydrochloride, ammonium persulfate, and sodium bisulfite.

[0020] Optionally, the mixed emulsifier includes sorbitan fatty acid ester and castor oil polyoxyethylene ether in a weight ratio of (1-1.8):(0.2-0.8).

[0021] Optionally, the sorbitan fatty acid ester is S-80, and the castor oil polyoxyethylene ether is EL-40.

[0022] The total HLB value of the mixed emulsifier in the present application is 5-7, which has a certain lipophilicity, so that the emulsifier and the mixed copolymer are better mixed together. The castor oil polyoxyethylene ether has excellent diffusion and protection of colloids, and can prevent monomer aggregation, effectively improve the stability of the resistance reducer, prevent the substances in the system from settling, and improve the quality and effect of the resistance reducer.

[0023] Optionally, the surfactant is selected from ditetradecyl dimethyl ammonium bromide, epoxypropyl triethyl ammonium chloride, and 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium in a weight ratio of 1: (0.4-0.8): (0.2-0.4).

[0024] The ditetradecyl dimethyl ammonium bromide can reduce the surface tension and interfacial tension of the friction reducer as a whole, so that various substances can exist more stably in the friction reducer, and sedimentation can be avoided; the epoxy propyl triethyl ammonium chloride can not only effectively realize the emulsifying effect, but also reduce the anti-swelling rate of the friction reducer as a whole; the sodium 3-allyloxy-2-hydroxy-1-propanesulfonate contains a sodium sulfonate group, which cooperates with a sulfonic acid group in the modified acrylamide polymer, and the cooperation of the two can improve the surface tension and interfacial tension of the emulsion, improve the oil layer wettability, improve the proppant dispersibility, prevent sedimentation, stabilize the oil-water emulsion, and improve the sand carrying efficiency.

[0025] In addition, the long-chain alkyl contained in the surfactant can greatly improve the dispersibility of graphene oxide and nano silicon dioxide in the oil phase, and the castor oil polyoxyethylene ether in the mixed emulsifier can adsorb the surfactant on the surface of graphene oxide and nano silicon dioxide particles through van der Waals force, ionic bond and other covalent forces to form a coating film, and the hydrophilic group head is adsorbed on the particle surface, and the long-chain alkyl group extends into the oil phase, thereby improving the stable dispersion of graphene oxide and nano silicon dioxide in the friction reducer.

[0026] Optionally, the oil phase is one or more of 3# white oil, 5# white oil, 10# white oil, toluene, xylene, hexane, cyclohexane, n-heptane, isomeric alkanes, gasoline, and kerosene.

[0027] Optionally, the stabilizer is one or more of organic bentonite, nano clay, starch, carboxymethyl cellulose, and hydroxymethyl cellulose.

[0028] Optionally, the capsule breaker includes a capsule core and a capsule shell, the capsule core is a mixture of ammonium persulfate, potassium persulfate and chloroform, and the capsule shell is a mixture of gum arabic, polyvinyl alcohol, polyethylene glycol 400 and n-butanol.

[0029] The preparation process of the capsule breaker is as follows: S100: mixing ammonium persulfate, potassium persulfate and chloroform in a weight ratio of 2:4:8 to obtain a capsule core; S200: mixing gum arabic, polyvinyl alcohol, polyethylene glycol 400 and n-butanol in a weight ratio of 2:3:6 to obtain a capsule shell; S300: mixing the capsule core and the capsule shell, adding an emulsifier Tween80 to obtain a mixed solution, and then performing spray drying, in which the liquid is micron-sized droplets under the pressure of 0.2-0.5Mpa, the droplets are in contact with hot air (200℃ at the inlet and 100℃ at the outlet), the solvent is rapidly evaporated, the dried microcapsules are collected by a cyclone separation bag and then cooled to obtain the capsule breaker.

[0030] According to another aspect of the present application, a preparation method of a suspension friction reducer is provided, which includes the following steps: S10: sequentially adding the oil phase, the mixed emulsifier into the reaction kettle, stirring at room temperature to obtain a mixed solution A; S20: sequentially adding the mixed copolymer, nano-SiO2, graphene oxide, and stabilizer into the mixed solution A, stirring and mixing uniformly to obtain a mixed solution B; S30: adding the surfactant and capsule breaker into the mixed solution B, stirring to obtain the suspension friction reducer.

[0031] According to another aspect of the present application, the suspension friction reducer is applied in the fracturing fluid system.

[0032] The beneficial effects of the present application include but are not limited to: 1. The suspension friction reducer according to the present application, the addition of nano-SiO2 and graphene oxide can effectively control the rheological property and thixotropy of the mixed copolymer, effectively prevent sedimentation and thickening, adjust the free flow of the friction reducer, and realize the high stability of the whole friction reducer.

[0033] 2. The suspension friction reducer according to the present application, the addition of the three kinds of compounded surfactants of ditetradecyl dimethyl ammonium bromide, epoxy propyl triethyl ammonium chloride, and 3-allyloxy-2-hydroxy-1-propane sulfonic acid sodium can improve the surface tension and interfacial tension of the emulsion and the anti-swelling rate of the emulsion; the castor oil polyoxyethylene ether can improve the HLB value through ethoxylation, promote the solubility of the suspension friction reducer in water, and better play a role; the sodium sulfonate group in 3-allyloxy-2-hydroxy-1-propane sulfonic acid sodium cooperates with the sulfonic acid group in the mixed copolymer.

[0034] 3. The suspension friction reducer according to the present application has temperature resistance and salt resistance, good shear resistance, large apparent viscosity, strong sand carrying capacity, reduced surface tension and interfacial tension, is convenient for flowback of the friction reducer, and improves the environmental protection effect. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The infrared light scanning spectrum of the polymer A involved in Example 3 of the present application; Figure 2 The temperature resistance and shear resistance graph of the friction reducer involved in Example 2 of the present application; Figure 3 The temperature resistance and shear resistance graph of the friction reducer involved in Example 3 of the present application; Figure 4 The curve graph of the friction reduction rate of the friction reducer involved in Example 3 of the present application. DETAILED DESCRIPTION

[0036] The present application will be described in detail below in combination with examples, but the present application is not limited to these examples.

[0037] The raw materials in the examples and comparative examples of the present application are commercially available unless otherwise specified.

[0038] The methods used in the examples and comparative examples of the present application are conventional methods in the prior art unless otherwise specified.

[0039] Example 1 The present example relates to a suspension drag reducer, comprising by weight: 30 parts of mixed copolymer, 1 part of sorbitan fatty acid ester S-80 and castor oil polyoxyethylene ether EL-40 with a weight ratio of 1:0.2, 50 parts of kerosene, 0.2 parts of nano-SiO2, 0.2 parts of graphene oxide, 0.5 parts of organic bentonite, 0.5 parts of ditetradecyl dimethyl ammonium bromide, epoxy propyl triethyl ammonium chloride, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium with a weight ratio of 1:0.4:0.2, 0.02 parts of capsule breaker.

[0040] The preparation method of the mixed copolymer in the present example comprises the following steps: S1: 1 part of sodium acrylate, 20 parts of acrylamide, and 10 parts of 2-acrylamido-2-methylpropanesulfonic acid are added to 200 parts of deionized water to obtain a first mixed solution. 1 part of 2-vinyl naphthalene is added to 100 parts of ethanol to obtain a second mixed solution. The second mixed solution is added to the first mixed solution, stirred quickly, then 0.5% of azobisdimethylaminoformamide hydrochloride based on the total weight of the system is added, nitrogen is introduced, the pH is adjusted to neutral, and the reaction is carried out at 70°C for 3h. After removing the solvent, polymer A is obtained; S2: 1 part of sodium lignosulfonate is dissolved in 99 parts of distilled water to obtain a 1wt% sodium lignosulfonate solution. 4 parts of acrylamide and 0.3% of potassium persulfate based on the total weight of the system are added, nitrogen is introduced, and the reaction is carried out at 55°C for 4h to obtain a sulfonated lignin-acrylamide copolymer; S3: Polymer A and the sulfonated lignin-acrylamide copolymer are mixed at a weight ratio of 1:10, stirred and mixed for 1h, and then dried to obtain the mixed copolymer.

[0041] The present example relates to a suspension drag reducer, comprising by weight: 30 parts of mixed copolymer, 1 part of sorbitan fatty acid ester S-80 and castor oil polyoxyethylene ether EL-40 with a weight ratio of 1:0.2, 50 parts of kerosene, 0.2 parts of nano-SiO2, 0.2 parts of graphene oxide, 0.5 parts of organic bentonite, 0.5 parts of ditetradecyl dimethyl ammonium bromide, epoxy propyl triethyl ammonium chloride, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium with a weight ratio of 1:0.4:0.2, 0.02 parts of capsule breaker. S10: 50 parts of kerosene, 1 part of sorbitan fatty acid ester S-80 and castor oil polyoxyethylene ether EL-40 with a weight ratio of 1:0.2 are added to a reaction kettle and stirred at room temperature to obtain a mixed solution A; S20: 30 parts of mixed copolymer, 0.2 parts of nano-SiO2, 0.2 parts of graphene oxide, and 0.5 parts of organic bentonite are added to the mixed solution A and stirred to obtain a mixed solution B; S30: 0.5 parts of dodecyl dimethyl ammonium bromide, propyl triethyl ammonium chloride, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt and 0.02 parts of capsule breaker with a weight ratio of 1:0.4:0.2 were added into the mixed solution B, and then stirred to obtain the suspension friction reducer.

[0042] Example 2 The suspension friction reducer of the present example comprises, by weight, 40 parts of mixed copolymer, 2 parts of sorbitan fatty acid ester S-80 and castor oil polyoxyethylene ether EL-40 with a weight ratio of 1.8:0.8, 60 parts of 5# white oil and xylene with a weight ratio of 1:1, 0.4 parts of nano-SiO2, 0.4 parts of graphene oxide, 1 part of nano-clay, 1 part of dodecyl dimethyl ammonium bromide, propyl triethyl ammonium chloride, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt with a weight ratio of 1:0.8:0.4, and 0.5 parts of capsule breaker.

[0043] The preparation method of the mixed copolymer in the present example comprises the following steps: S1: 1 part of sodium acrylate, 25 parts of acrylamide and 5 parts of 2-acrylamido-2-methylpropanesulfonic acid were added into 200 parts of deionized water to obtain a first mixed solution. 2 parts of 2-vinyl naphthalene were added into 100 parts of ethanol to obtain a second mixed solution. The second mixed solution was added into the first mixed solution, followed by adding 0.5% of azobisimidozolin hydrochloride in the total weight of the system, adjusting the pH to neutral, and passing inert gas to react at 30°C for 4h. After removing the solvent, polymer A was obtained; S2: 1.5 parts of sodium lignosulfonate were dissolved in 98.5 parts of distilled water to obtain a 1.5wt% sodium lignosulfonate solution. 8 parts of acrylamide and 0.3% of potassium persulfate in the total weight of the system were added into the solution. Nitrogen was passed, and the reaction was carried out at 80°C for 6h to obtain sulfonated lignin-acrylamide copolymer; S3: polymer A and sulfonated lignin-acrylamide copolymer were mixed with a weight ratio of 1:20, stirred and mixed for 2h, and then dried to obtain the mixed copolymer.

[0044] The preparation method of the suspension friction reducer of the present example comprises the following steps: S10: 60 parts of 5# white oil and xylene with a weight ratio of 1:1 were sequentially added into a reaction kettle, and 2 parts of sorbitan fatty acid ester S-80 and castor oil polyoxyethylene ether EL-40 with a weight ratio of 1.8:0.8 were stirred at room temperature to obtain a mixed solution A; S20: 40 parts of mixed copolymer, 0.4 parts of nano-SiO2, 0.4 parts of graphene oxide and 1 part of nano-clay were sequentially added into the mixed solution A and stirred to obtain a mixed solution B; S30: 1 part by weight of dodecyl dimethyl benzyl ammonium bromide, propylene glycol monostearate, and 0.5 parts of a capsule breaker were added to the mixed solution B, and after stirring, it was obtained.

[0045] Example 3 The present example relates to a suspension resistance reducer, which comprises, by weight: 35 parts of mixed copolymer, 1.5 parts of sorbitan fatty acid ester S-80 and castor oil polyoxyethylene ether EL-40 in a weight ratio of 1.4:0.6, 55 parts of 3# white oil, 0.3 parts of nano-SiO2, 0.3 parts of graphene oxide, 0.8 parts of starch and carboxymethyl cellulose in a weight ratio of 1:1, 0.8 parts of dodecyl dimethyl benzyl ammonium bromide, propylene glycol monostearate, and 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium in a weight ratio of 0.8:0.6:0.3, and 0.1 parts of a capsule breaker.

[0046] The preparation method of the mixed copolymer in the present example comprises the following steps: S1: 1 part of sodium acrylate, 23 parts of acrylamide, and 8 parts of 2-acrylamido-2-methylpropanesulfonic acid were added to 200 parts of deionized water to obtain a first mixed solution. 1.5 parts of styrene was mixed with 100 parts of ethanol to obtain a second mixed solution. Then, 0.5% of azobisdimethylaminoformamide hydrochloride based on the total weight of the system was added, nitrogen was introduced, the pH was adjusted to neutral, and the reaction was carried out at 65°C for 3.5h. After removing the solvent, polymer A was obtained; S2: 1.2 parts of sodium lignosulfonate was dissolved in 98.8 parts of distilled water to obtain a 1.2wt% sodium lignosulfonate solution. 6 parts of acrylamide and 0.3% of potassium persulfate based on the total weight of the system were added, nitrogen was introduced, and the reaction was carried out at 65°C for 5h to obtain sulfonated lignin-acrylamide copolymer; S3: Polymer A and sulfonated lignin-acrylamide copolymer were mixed in a weight ratio of 1:15, stirred for 1.5h, and dried to obtain the mixed copolymer.

[0047] The present example relates to a suspension resistance reducer, which comprises, by weight: 35 parts of mixed copolymer, 1.5 parts of sorbitan fatty acid ester S-80 and castor oil polyoxyethylene ether EL-40 in a weight ratio of 1.4:0.6, 55 parts of 3# white oil, 0.3 parts of nano-SiO2, 0.3 parts of graphene oxide, 0.8 parts of starch and carboxymethyl cellulose in a weight ratio of 1:1, 0.8 parts of dodecyl dimethyl benzyl ammonium bromide, propylene glycol monostearate, and 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium in a weight ratio of 0.8:0.6:0.3, and 0.1 parts of a capsule breaker. S10: 55 parts of 3# white oil, 1.5 parts of sorbitan fatty acid ester S-80 and castor oil polyoxyethylene ether EL-40 in a weight ratio of 1.4:0.6 were added to a reaction kettle and stirred at room temperature to obtain a mixed solution A; S20: 35 parts of mixed polymer, 0.3 parts of nano-SiO2, 0.3 parts of graphene oxide, and 0.8 parts of starch and carboxymethyl cellulose in a weight ratio of 1:1 were added to the mixed solution A and stirred to obtain a mixed solution B; S30: To the mixed solution B, 0.8 parts of dodecyl dimethyl ammonium bromide, glycidyl triethyl ammonium chloride, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium and 0.1 parts of capsule breaker with a weight ratio of 0.8:0.6:0.3 were added, and after stirring, it was obtained.

[0048] Example 4 The difference between this example and Example 3 is that 2-acrylamido-2-methylpropanesulfonic acid in step S1 is replaced by methyl 2-acrylamido-2-methoxyacetate, and the rest is the same as Example 3.

[0049] Example 5 The difference between this example and Example 3 is that the weight ratio of sodium acrylate, acrylamide, and 2-acrylamido-2-methylpropanesulfonic acid is 1:30:5, and the rest is the same as Example 3.

[0050] Example 6 The difference between this example and Example 3 is that 1 part of sodium acrylate, 30 parts of acrylamide, 1 part of 2-acrylamido-2-methylpropanesulfonic acid, and 1 part of a conjugated compound containing a double bond are added in step S1, and the rest is the same as Example 3.

[0051] Example 7 The difference between this example and Example 3 is that sorbitan fatty acid ester S-80 and castor oil polyoxyethylene ether EL-40 with a weight ratio of 1.4:0.6 are replaced by sorbitan fatty acid ester S-80, and the rest is the same as Example 3.

[0052] Example 8 The difference between this example and Example 3 is that sorbitan fatty acid ester S-80 and castor oil polyoxyethylene ether EL-40 with a weight ratio of 1.4:0.6 are replaced by sorbitan fatty acid ester S-80, and the rest is the same as Example 3.

[0053] Example 9 The difference between this example and Example 3 is that dodecyl dimethyl ammonium bromide, glycidyl triethyl ammonium chloride, and 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium with a weight ratio of 0.8:0.6:0.3 are replaced by 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium, and the rest is the same as Example 3.

[0054] Comparative Example 1 The difference between this example and Example 3 is that the mixed copolymer is replaced by polyacrylamide, and the rest is the same as Example 3.

[0055] Comparative Example 2 The difference between this example and Example 3 is that styrene is replaced by ethylene, and the rest is the same as Example 3.

[0056] Comparative Example 3 The difference between this comparative example and Example 3 is that the mixed copolymer is replaced by the polymer A prepared in step S1, and the rest is the same as Example 3.

[0057] Comparative Example 4 The difference between this comparative example and Example 3 is that a common commercially available suspension friction reducer is used.

[0058] Test Example 1 The suspension friction reducers obtained in Examples 1-9 and Comparative Examples 1-4 are tested for physical and chemical properties, and the test methods are as follows, and the results are shown in Table 1.

[0059] a. Friction reduction rate test: 1% suspension friction reducer solution of the friction reducer prepared in Examples 1-9 and Comparative Examples 1-4 is placed in a friction tester, and the friction reduction rate is recorded; b. Apparent viscosity: 1% solution of the friction reducer prepared in Examples 1-9 and Comparative Examples 1-4 is prepared, and the apparent viscosity is measured by a six-speed rotary viscometer, and the viscosity meter reading at a speed of 100 r / min is read and calculated to record the apparent viscosity; c. Anti-swelling rate: 1% suspension friction reducer solution of the friction reducer prepared in Examples 1-9 and Comparative Examples 1-4 is prepared to prepare a breaking fluid, and the anti-swelling rate is evaluated by measuring the volume expansion increment of sodium-based bentonite in the breaking fluid, distilled water and kerosene; d. Surface tension and interfacial tension: 1% suspension friction reducer solution of the friction reducer prepared in Examples 1-9 and Comparative Examples 1-4 is prepared to prepare a breaking fluid, and the surface and interfacial tension is measured by a surface and interfacial tension instrument according to the method of SY / T 5370-2018; e. Temperature and shear resistance: 1% suspension friction reducer solution of the friction reducer prepared in Examples 1-9 and Comparative Examples 1-4 is prepared, and a Hake rheometer is used for shearing at 120℃, 170S -1 , 120min, and the average viscosity value within 1min before reaching the set shearing time is recorded as the temperature and shear resistance at the test temperature.

[0060] Table 1

[0061] The mixed copolymer prepared in Example 3 is purified, and then infrared spectrum detection is performed, and the results are shown in Figure 1 .

[0062] According to the data in Figure 2 , the 1% suspension friction reducer solution of the friction reducer in Example 2 of the present application has high temperature and shear resistance.

[0063] according to Figure 3 The data shows that the drag-reducing agent in Example 3 of this application is prepared into a 1% suspension drag-reducing agent solution, which has high temperature and shear resistance, and is superior to the suspension drag-reducing agent solutions in other examples and comparative examples.

[0064] according to Figure 4 The data shows that the drag-reducing agent in Example 3 of this application is prepared into a 1% suspension drag-reducing agent solution, and the drag reduction rate can reach 78.9%, which is better than the drag reduction effect of other examples and comparative examples.

[0065] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A suspension drag reducer characterized in that, By weight, including: mixed copolymer 30-40 parts, mixed emulsifier 1-2 parts, oil phase 50-60 parts, nano SiO2 0.2-0.4 parts, graphene oxide 0.2-0.4 parts, stabilizer 0.5-1 parts, surfactant 0.5-1 parts, capsule breaker 0.02-0.5 parts; The preparation method of the mixed copolymer comprises the following steps: S1: acrylamide, 2-acrylamido-2-methylpropane sulfonic acid and sodium acrylate are added to deionized water for stirring and mixing to obtain a first mixed solution, a conjugated compound containing double bonds is added to an organic solvent to obtain a second mixed solution, the second mixed solution is added to the first mixed solution, stirred quickly, an initiator is added, the pH is adjusted to neutral, inert gas is introduced, and reaction is carried out at 50-70°C for 3-4h, and after removing the solvent, a polymer A is obtained; S2: sodium lignosulfonate is dissolved in water and stirred and mixed uniformly to obtain a sodium lignosulfonate solution, acrylamide and potassium persulfate are added thereto, and reaction is carried out at 55-80°C for 4-6h to obtain a sulfonated lignin-acrylamide copolymer; S3: the polymer A and the sulfonated lignin-acrylamide copolymer are mixed and stirred and mixed for 1-2h, and after drying, a mixed copolymer is obtained.

2. The suspension drag reducer of claim 1, wherein, The weight ratio of the sodium acrylate, the acrylamide, the 2-acrylamido-2-methylpropane sulfonic acid and the conjugated compound containing double bonds is 1:(20-25):(5-10):(1-2); and or The weight ratio of the sodium lignosulfonate and the acrylamide is 1:(4-8); The concentration of the sodium lignosulfonate solution is 1-1.5wt%.

3. The suspension drag reducer of claim 1, wherein, The weight ratio of the polymer A and the sulfonated lignin-acrylamide copolymer is 1:(10-20).

4. The suspension drag reducer of claim 1, wherein, The conjugated compound containing double bonds is a conjugated compound containing double bonds and at least one benzene ring.

5. The suspension drag reducer of claim 1, wherein, The conjugated compound containing double bonds is at least one of 9-vinylanthracene, 2-vinyl naphthalene and styrene.

6. The suspension de- visser of claim 1, wherein The mixed emulsifier comprises sorbitan fatty acid ester and castor oil polyoxyethylene ether in a weight ratio of (1-1.8):(0.2-0.8).

7. The suspension de- visser of claim 1 wherein, The surfactant is selected from ditetradecyl dimethyl ammonium bromide, epoxypropyl triethyl ammonium chloride and 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium in a weight ratio of 1:(0.4-0.8):(0.2-0.4).

8. The suspension de- visser of claim 1, wherein The oil phase is one or more of 3# white oil, 5# white oil, 10# white oil, toluene, xylene, hexane, cyclohexane, n-heptane, gasoline and kerosene. The stabilizer is one or more of organic bentonite, nano clay, starch, carboxymethyl cellulose and hydroxymethyl cellulose.

9. The method of preparing a suspension drag reducer according to any one of claims 1-8, wherein, The preparation method comprises the following steps: S10: an oil phase and a mixed emulsifier are sequentially added to a reaction kettle, and stirring is carried out at room temperature to obtain a mixed solution A; S20: a mixed copolymer, nano SiO2, graphene oxide and a stabilizer are sequentially added to the mixed solution A and stirred and mixed uniformly to obtain a mixed solution B; S30: a surfactant and a capsule breaker are added to the mixed solution B, and after stirring, the suspension resistance reducer is obtained.

10. The use of the suspension resistance reducer in any one of claims 1-9 in a fracturing fluid system.

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