CN111303322A - Preparation method of thickening agent, fracturing fluid and application - Google Patents

Preparation method of thickening agent, fracturing fluid and application Download PDF

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Publication number
CN111303322A
CN111303322A CN202010305651.7A CN202010305651A CN111303322A CN 111303322 A CN111303322 A CN 111303322A CN 202010305651 A CN202010305651 A CN 202010305651A CN 111303322 A CN111303322 A CN 111303322A
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fracturing fluid
thickening agent
stirring
thickener
trichloromethane
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张烨
王彦玲
巩锦程
蒙春
贺培
高磊
蔡永志
陆朝晖
张健强
张义
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Chongqing Institute of Geology and Mineral Resources
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Chongqing Institute of Geology and Mineral Resources
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F118/00—Homopolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an acyloxy radical of a saturated carboxylic acid, of carbonic acid or of a haloformic acid
    • C08F118/02—Esters of monocarboxylic acids
    • C08F118/04—Vinyl esters
    • C08F118/08—Vinyl acetate
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F2/00—Processes of polymerisation
    • C08F2/38—Polymerisation using regulators, e.g. chain terminating agents, e.g. telomerisation
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
    • C09K8/60—Compositions for stimulating production by acting on the underground formation
    • C09K8/62—Compositions for forming crevices or fractures
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
    • C09K8/60—Compositions for stimulating production by acting on the underground formation
    • C09K8/62—Compositions for forming crevices or fractures
    • C09K8/70—Compositions for forming crevices or fractures characterised by their form or by the form of their components, e.g. foams
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids

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  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
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  • General Life Sciences & Earth Sciences (AREA)
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Abstract

The invention discloses a preparation method of a thickening agent, the thickening agent, fracturing fluid and application, and belongs to the technical field of fracturing. The preparation method of the thickening agent comprises the following steps: under the atmosphere of protective gas, pentaerythritol and pyridine are dissolved in trichloromethane, and are stirred, 2-bromopropionyl bromide is slowly added for reaction, and then the filtering and drying treatment is carried out, so as to obtain a brominated precursor; dissolving a bromination precursor in trichloromethane, stirring, adding potassium ethylxanthate for reaction, and filtering and drying to obtain a chain transfer agent; carrying out polymerization reaction on the chain transfer agent, a polymer monomer and an initiator to obtain a reaction product; the reaction product is treated with acetic acidDissolving ethyl ester, precipitating with n-hexane, volatilizing the solvent, and drying to obtain the thickening agent. The thickener is nontoxic and environment-friendly, and can greatly improve supercritical CO when being used as a cosolvent with ethanol2Viscosity of the fracturing fluid.

Description

Preparation method of thickening agent, fracturing fluid and application
Technical Field
The invention relates to the technical field of fracturing, in particular to a preparation method of a thickening agent, the thickening agent, a fracturing fluid and application.
Background
Along with the increasing of the exploration and development of oil and gas fields, unconventional oil and gas resources become hot spots of development at home and abroad at present. Unconventional oil and gas resources are clean and high-quality energy sources, and unconventional natural gas such as dense gas, shale gas and the like has huge exploitation potential.
In addition, hydraulic fracturing is an important means for exploiting shale gas, but for the characteristics of poor physical property and low permeability of a shale gas reservoir, the conventional fracturing fluid has the problem of incomplete gel breaking, so that pores are easy to block. And supercritical CO2The fracturing fluid has been gradually raised as a novel fracturing fluid, and has the following advantages: no water phase, water source saving; the environment-friendly fertilizer has the advantages of less chemical additives, less flowback liquid and no residue, and can play an environmental protection role in effectively reducing pollution to soil and underground water; the surface tension of the fracturing fluid is almost 0, and the fracturing fluid can enter more pore spaces to increase the formation energy for crack propagation; the adsorption force is far greater than CH4Can replace CH4Displacing the natural gas to improve the yield of the natural gas; CO 22Can be retained in stratum in a large amount in an adsorption and dissolution mode, and relieves the greenhouse effect.
However, due to supercritical CO2The fracturing fluid has the problem of low viscosity, so the fracturing fluid generally needs to be added with thickeningAgents to increase viscosity. Although, in the prior art, the supercritical CO can be obtained by selecting fluorine-based and silicon-based polymers2However, fluorine is toxic, and fluorine-and silicon-containing polymers are expensive and difficult to degrade, and are likely to cause serious damage to the formation environment. Therefore, there is a need to research a supercritical CO that can achieve environmental protection, economy, and thickening efficiency2A fracturing fluid thickener.
Disclosure of Invention
An object of an embodiment of the present invention is to provide a method for preparing a thickener, so as to solve the problems suggested in the background art.
In order to achieve the above purpose, the embodiments of the present invention provide the following technical solutions:
a preparation method of the thickening agent comprises the following steps:
according to parts by weight, under a protective gas atmosphere, dissolving 3-5 parts of pentaerythritol and 6-10 parts of pyridine in 50-70 parts of trichloromethane to obtain a mixed solution;
stirring the mixed solution, slowly adding 20-40 parts of 2-bromopropionyl bromide into the mixed solution for reaction, and then filtering and drying to obtain a bromination precursor;
dissolving 8-12 parts of the brominated precursor in 120-180 parts of trichloromethane to obtain a trichloromethane solution of the brominated precursor;
stirring the trichloromethane solution of the brominated precursor, adding 10-15 parts of potassium ethyl xanthate into the trichloromethane solution of the brominated precursor for reaction, and then filtering and drying to obtain a chain transfer agent;
placing the chain transfer agent, a polymer monomer and an initiator in a mass ratio of (10-20) to (40-60) to (10-20) in an oil bath at the temperature of 60-70 ℃ for polymerization reaction to obtain a reaction product;
and dissolving the reaction product by using ethyl acetate, precipitating by using n-hexane, and then volatilizing and drying the solvent to obtain the thickening agent.
In a preferable embodiment of the present invention, in the step of stirring the mixed solution, the temperature of the stirring is 3 to 8 ℃, and the rotation speed of the stirring is 1000 to 1500 rpm.
In another preferable embodiment of the invention, in the step of stirring the chloroform solution of the bromination precursor, the temperature of the stirring is 20 to 30 ℃, and the rotation speed of the stirring is 800 to 1200 rpm.
As another preferable scheme of the embodiment of the invention, the polymer monomers are vinyl acetate and ethyl acetate; the mass ratio of the vinyl acetate to the ethyl acetate is (2-6) to (4-8).
As another preferable mode of the embodiment of the present invention, the initiator is azobisisobutyronitrile.
Another object of the embodiments of the present invention is to provide a thickener prepared by the above preparation method.
Another object of an embodiment of the present invention is to provide a use of the above thickener in preparation of a fracturing fluid.
It is another object of an embodiment of the present invention to provide a fracturing fluid, which contains the above-mentioned thickening agent.
As another preferable scheme of the embodiment of the invention, the fracturing fluid also comprises supercritical CO2The mass ratio of the absolute ethyl alcohol to the thickening agent is (5-8): 100; the weight percentage of the thickening agent in the fracturing fluid is 1-2%.
Another object of an embodiment of the present invention is to provide an application of the above fracturing fluid in shale gas exploitation.
Compared with the prior art, the embodiment of the invention has the beneficial effects that:
(1) the thickening agent prepared by the embodiment of the invention is polyvinyl acetate with a multi-arm topological structure, belongs to a non-fluorine thickening agent, is non-toxic, has small harm to the stratum, is easy to flowback and degrade, is beneficial to environmental protection, and can be used for treating supercritical CO when being used as a cosolvent with ethanol2The fracturing fluid has a large thickening effect.
(2) The raw materials adopted in the preparation method of the thickening agent provided by the embodiment of the invention are all substances which are easy to purchase and have lower price on the market, and the preparation process is simple and convenient, so that the production cost of the thickening agent can be greatly reduced.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The embodiment provides a thickener and a preparation method thereof, wherein the preparation method of the thickener comprises the following steps:
(1) under a nitrogen atmosphere, 3g of pentaerythritol and 6g of pyridine were dissolved in 50g of chloroform to obtain a mixed solution.
(2) Performing magnetic stirring treatment on the mixed solution, and simultaneously slowly adding 20g of 2-bromopropionyl bromide into the mixed solution for full reaction, and then performing filtration and drying treatment to obtain a bromination precursor; wherein the temperature of the stirring treatment in the step is 3 ℃, and the rotating speed of the stirring treatment is 1000 rpm.
(3) 8g of the above-mentioned brominated precursor was dissolved in 120g of chloroform to obtain a chloroform solution of the brominated precursor.
(4) Performing magnetic stirring treatment on the trichloromethane solution of the bromination precursor, adding 10g of potassium ethyl xanthate into the trichloromethane solution of the bromination precursor to react for 72 hours, then performing filtration and drying treatment, and removing residual trichloromethane by using a rotary evaporator to obtain a chain transfer agent; wherein the temperature of the stirring treatment in the step is 20 ℃, and the rotating speed of the stirring treatment is 800 rpm.
(5) Placing the chain transfer agent, a polymer monomer and an initiator in a mass ratio of 20:60:20 in an oil bath at 60 ℃ for polymerization reaction to obtain a reaction product; specifically, vinyl acetate and ethyl acetate are added into a reaction vessel according to the mass ratio of 2:8, the reaction vessel is placed in an oil bath at 60 ℃ under the nitrogen atmosphere, and the chain transfer agent and the azobisisobutyronitrile are simultaneously added for full polymerization reaction, so that a reaction product can be obtained.
(6) Dissolving the reaction product with ethyl acetate, precipitating with n-hexane, performing solvent volatilization for multiple times, and drying at 45 ℃ for 48h to obtain the thickening agent, wherein the thickening agent is polyvinyl acetate with a four-arm topological structure.
Mixing the above 10g thickener, 0.5g anhydrous ethanol and 89.5g supercritical CO at 25MPa and 40 deg.C2And mixing the solvents to obtain the fracturing fluid.
Example 2
The embodiment provides a thickener and a preparation method thereof, wherein the preparation method of the thickener comprises the following steps:
(1) 5g of pentaerythritol and 10g of pyridine were dissolved in 70g of chloroform under a nitrogen atmosphere to obtain a mixed solution.
(2) Under the protective gas atmosphere of nitrogen, carrying out magnetic stirring treatment on the mixed solution, meanwhile, slowly adding 40g of 2-bromopropionyl bromide into the mixed solution for full reaction, and then carrying out filtration and drying treatment to obtain a bromination precursor; wherein the temperature of the stirring treatment in the step is 8 ℃, and the rotating speed of the stirring treatment is 1500 rpm.
(3) 12g of the above-mentioned brominated precursor was dissolved in 180g of chloroform under a nitrogen atmosphere to obtain a chloroform solution of the brominated precursor.
(4) Under the atmosphere of nitrogen protective gas, magnetically stirring the trichloromethane solution of the bromination precursor, adding 15g of potassium ethylxanthate into the trichloromethane solution of the bromination precursor to react for 72 hours, filtering and drying, and removing residual trichloromethane by using a rotary evaporator to obtain a chain transfer agent; wherein the temperature of the stirring treatment in the step is 30 ℃, and the rotating speed of the stirring treatment is 1200 rpm.
(5) Placing the chain transfer agent, a polymer monomer and an initiator in a mass ratio of 10:50:10 in an oil bath at 70 ℃ for polymerization reaction to obtain a reaction product; specifically, vinyl acetate and ethyl acetate are added into a reaction vessel according to the mass ratio of 6:4, the reaction vessel is placed in an oil bath at 70 ℃ under the nitrogen atmosphere, and the chain transfer agent and the azobisisobutyronitrile are simultaneously added for full polymerization reaction, so that a reaction product can be obtained.
(6) Dissolving the reaction product with ethyl acetate, precipitating with n-hexane, performing solvent volatilization for multiple times, and drying at 45 ℃ for 48h to obtain the thickening agent, wherein the thickening agent is polyvinyl acetate with a four-arm topological structure.
Mixing the above 20g thickener, 1.6g anhydrous ethanol and 78.4g supercritical CO at 25MPa and 40 deg.C2And mixing the solvents to obtain the fracturing fluid.
As another preferable scheme of the embodiment of the invention, the fracturing fluid also comprises supercritical CO2The mass ratio of the absolute ethyl alcohol to the thickening agent is (5-8): 100; the weight percentage of the thickening agent in the fracturing fluid is 1-2%.
Example 3
The embodiment provides a thickener and a preparation method thereof, wherein the preparation method of the thickener comprises the following steps:
(1) in a nitrogen atmosphere, 3g of pentaerythritol and 6g of pyridine were dissolved in 60g of chloroform to obtain a mixed solution.
(2) Under the atmosphere of nitrogen protection gas, carrying out magnetic stirring treatment on the mixed solution, meanwhile, slowly adding 30g of 2-bromopropionyl bromide into the mixed solution for full reaction, and then carrying out filtration and drying treatment to obtain a bromination precursor; wherein the temperature of the stirring treatment in the step is 5 ℃, and the rotating speed of the stirring treatment is 1200 rpm.
(3) 10g of the above-mentioned brominated precursor was dissolved in 150g of chloroform under a nitrogen atmosphere to obtain a chloroform solution of the brominated precursor.
(4) Under the atmosphere of nitrogen protective gas, magnetically stirring the trichloromethane solution of the bromination precursor, adding 10g of potassium ethylxanthate into the trichloromethane solution of the bromination precursor to react for 72 hours, filtering and drying, and removing residual trichloromethane by using a rotary evaporator to obtain a chain transfer agent; wherein the temperature of the stirring treatment in the step is 25 ℃, and the rotating speed of the stirring treatment is 1000 rpm.
(5) Placing the chain transfer agent, a polymer monomer and an initiator in a mass ratio of 15:60:20 in an oil bath at 65 ℃ for polymerization reaction to obtain a reaction product; specifically, vinyl acetate and ethyl acetate are added into a reaction vessel according to the mass ratio of 2:8, the reaction vessel is placed in an oil bath at 65 ℃ under the nitrogen atmosphere, and the chain transfer agent and the azobisisobutyronitrile are simultaneously added for full polymerization reaction, so that a reaction product can be obtained.
(6) Dissolving the reaction product with ethyl acetate, precipitating with n-hexane, performing solvent volatilization for multiple times, and drying at 45 ℃ for 48h to obtain the thickening agent, wherein the thickening agent is polyvinyl acetate with a four-arm topological structure.
Mixing the above 15g thickener, 0.9g anhydrous ethanol and 84.1g supercritical CO at 25MPa and 40 deg.C2And mixing the solvents to obtain the fracturing fluid.
Example 4
The embodiment provides a thickener and a preparation method thereof, wherein the preparation method of the thickener comprises the following steps:
(1) 4g of pentaerythritol and 8g of pyridine were dissolved in 60g of chloroform under a nitrogen atmosphere to obtain a mixed solution.
(2) Under the atmosphere of nitrogen protection gas, carrying out magnetic stirring treatment on the mixed solution, meanwhile, slowly adding 30g of 2-bromopropionyl bromide into the mixed solution for full reaction, and then carrying out filtration and drying treatment to obtain a bromination precursor; wherein the temperature of the stirring treatment in the step is 5 ℃, and the rotating speed of the stirring treatment is 1200 rpm.
(3) 10g of the above-mentioned brominated precursor was dissolved in 150g of chloroform under a nitrogen atmosphere to obtain a chloroform solution of the brominated precursor.
(4) Under the atmosphere of nitrogen protective gas, magnetically stirring the trichloromethane solution of the bromination precursor, adding 12g of potassium ethylxanthate into the trichloromethane solution of the bromination precursor for reacting for 72 hours, filtering and drying, and removing residual trichloromethane by using a rotary evaporator to obtain a chain transfer agent; wherein the temperature of the stirring treatment in the step is 25 ℃, and the rotating speed of the stirring treatment is 1000 rpm.
(5) Placing the chain transfer agent, a polymer monomer and an initiator in a mass ratio of 10:45:15 in an oil bath at 60 ℃ for polymerization reaction to obtain a reaction product; specifically, vinyl acetate and ethyl acetate are added into a reaction vessel according to the mass ratio of 4:6, the reaction vessel is placed in an oil bath at 60 ℃ under the nitrogen atmosphere, and the chain transfer agent and the azobisisobutyronitrile are simultaneously added for full polymerization reaction, so that a reaction product can be obtained.
(6) Dissolving the reaction product with ethyl acetate, precipitating with n-hexane, performing solvent volatilization for multiple times, and drying at 45 ℃ for 48h to obtain the thickening agent, wherein the thickening agent is polyvinyl acetate with a four-arm topological structure.
Mixing the above 15g thickener, 0.9g anhydrous ethanol and 84.1g supercritical CO at 25MPa and 40 deg.C2And mixing the solvents to obtain the fracturing fluid.
Example 5
The embodiment provides a thickener and a preparation method thereof, wherein the preparation method of the thickener comprises the following steps:
(1) 5g of pentaerythritol and 10g of pyridine were dissolved in 60g of chloroform under a nitrogen atmosphere to obtain a mixed solution.
(2) Under the atmosphere of nitrogen protection gas, carrying out magnetic stirring treatment on the mixed solution, meanwhile, slowly adding 30g of 2-bromopropionyl bromide into the mixed solution for full reaction, and then carrying out filtration and drying treatment to obtain a bromination precursor; wherein the temperature of the stirring treatment in the step is 5 ℃, and the rotating speed of the stirring treatment is 1200 rpm.
(3) 10g of the above-mentioned brominated precursor was dissolved in 150g of chloroform under a nitrogen atmosphere to obtain a chloroform solution of the brominated precursor.
(4) Under the atmosphere of nitrogen protective gas, magnetically stirring the trichloromethane solution of the bromination precursor, adding 15g of potassium ethylxanthate into the trichloromethane solution of the bromination precursor to react for 72 hours, filtering and drying, and removing residual trichloromethane by using a rotary evaporator to obtain a chain transfer agent; wherein the temperature of the stirring treatment in the step is 25 ℃, and the rotating speed of the stirring treatment is 1000 rpm.
(5) Placing the chain transfer agent, a polymer monomer and an initiator in a mass ratio of 20:55:15 in an oil bath at 70 ℃ for polymerization reaction to obtain a reaction product; specifically, vinyl acetate and ethyl acetate are added into a reaction vessel according to the mass ratio of 3:7, the reaction vessel is placed in an oil bath at 70 ℃ under the nitrogen atmosphere, and the chain transfer agent and the azobisisobutyronitrile are simultaneously added for full polymerization reaction, so that a reaction product can be obtained.
(6) Dissolving the reaction product with ethyl acetate, precipitating with n-hexane, performing solvent volatilization for multiple times, and drying at 45 ℃ for 48h to obtain the thickening agent, wherein the thickening agent is polyvinyl acetate with a four-arm topological structure.
Mixing the above 15g thickener, 0.9g anhydrous ethanol and 84.1g supercritical CO at 25MPa and 40 deg.C2And mixing the solvents to obtain the fracturing fluid.
Example 6
The embodiment provides a thickener and a preparation method thereof, wherein the preparation method of the thickener comprises the following steps:
(1) 5g of pentaerythritol and 8g of pyridine were dissolved in 60g of chloroform under a nitrogen atmosphere to obtain a mixed solution.
(2) Under the atmosphere of nitrogen protection gas, carrying out magnetic stirring treatment on the mixed solution, meanwhile, slowly adding 30g of 2-bromopropionyl bromide into the mixed solution for full reaction, and then carrying out filtration and drying treatment to obtain a bromination precursor; wherein the temperature of the stirring treatment in the step is 5 ℃, and the rotating speed of the stirring treatment is 1200 rpm.
(3) 10g of the above-mentioned brominated precursor was dissolved in 150g of chloroform under a nitrogen atmosphere to obtain a chloroform solution of the brominated precursor.
(4) Under the atmosphere of nitrogen protective gas, magnetically stirring the trichloromethane solution of the bromination precursor, adding 14g of potassium ethylxanthate into the trichloromethane solution of the bromination precursor to react for 72 hours, filtering and drying, and removing residual trichloromethane by using a rotary evaporator to obtain a chain transfer agent; wherein the temperature of the stirring treatment in the step is 25 ℃, and the rotating speed of the stirring treatment is 1000 rpm.
(5) Placing the chain transfer agent, a polymer monomer and an initiator in a mass ratio of 12:60:18 in an oil bath at 65 ℃ for polymerization reaction to obtain a reaction product; specifically, vinyl acetate and ethyl acetate are added into a reaction vessel according to the mass ratio of 6:4, the reaction vessel is placed in an oil bath at 65 ℃ under the nitrogen atmosphere, and the chain transfer agent and the azobisisobutyronitrile are simultaneously added for full polymerization reaction, so that a reaction product can be obtained.
(6) Dissolving the reaction product with ethyl acetate, precipitating with n-hexane, performing solvent volatilization for multiple times, and drying at 45 ℃ for 48h to obtain the thickening agent, wherein the thickening agent is polyvinyl acetate with a four-arm topological structure.
Mixing the above 15g thickener, 0.9g anhydrous ethanol and 84.1g supercritical CO at 25MPa and 40 deg.C2And mixing the solvents to obtain the fracturing fluid.
Comparative example 1
The fracturing fluids obtained in examples 1 to 6 were mixed with supercritical CO without the thickener2Performing viscosity comparison on the fracturing fluid, and comparing the fracturing fluid with supercritical CO without the thickening agent2The viscosity ratio of the fracturing fluid is recorded as the thickening amplitude of the thickener and compared with the thickening effect of the commercial thickener. The commercially available thickener is a silicone polymer.
The results of the tests of the thickening ranges of the thickeners provided in examples 1 to 6 and the commercially available thickeners are shown in table 1 below.
TABLE 1
Test items Commercially available thickeners Example 1 Example 2 Example 3 Example 4 Example 5 Example 6
Magnitude of thickening (%) 18 31 52 36 41 47 51
As can be seen from Table 1 above, the thickeners prepared in the examples of the present invention are characterized by supercritical CO compared to commercially available thickeners2The fracturing fluid has a good thickening effect.
Comparative example 2
The fracturing fluids obtained in examples 1 to 6 were mixed with supercritical CO without the thickener2Performing viscosity comparison on the fracturing fluid, and comparing the fracturing fluid with supercritical CO without the thickening agent2The viscosity ratio of the fracturing fluid is recorded as the thickening amplitude of the thickener and compared with the thickening effect of polyvinyl acetate of a common structure. The results of the above examples 1 to 6 and the conventional polyvinyl acetate for the thickening range are shown in the following table 2.
TABLE 2
Figure BDA0002455700800000091
As can be seen from the above Table 2, the four-arm topological structure thickener prepared by the embodiment of the invention is compared with the thickener with a common structure to supercritical CO2The thickening effect of the fracturing fluid is greatly improved.
In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims (10)

1. A preparation method of a thickening agent is characterized by comprising the following steps:
according to parts by weight, under a protective gas atmosphere, dissolving 3-5 parts of pentaerythritol and 6-10 parts of pyridine in 50-70 parts of trichloromethane to obtain a mixed solution;
stirring the mixed solution, slowly adding 20-40 parts of 2-bromopropionyl bromide into the mixed solution for reaction, and then filtering and drying to obtain a bromination precursor;
dissolving 8-12 parts of the brominated precursor in 120-180 parts of trichloromethane to obtain a trichloromethane solution of the brominated precursor;
stirring the trichloromethane solution of the brominated precursor, adding 10-15 parts of potassium ethyl xanthate into the trichloromethane solution of the brominated precursor for reaction, and then filtering and drying to obtain a chain transfer agent;
placing the chain transfer agent, a polymer monomer and an initiator in a mass ratio of (10-20) to (40-60) to (10-20) in an oil bath at the temperature of 60-70 ℃ for polymerization reaction to obtain a reaction product;
and dissolving the reaction product by using ethyl acetate, precipitating by using n-hexane, and then volatilizing and drying the solvent to obtain the thickening agent.
2. The method for preparing a thickener according to claim 1, wherein in the step of stirring the mixed solution, the temperature of the stirring is 3 to 8 ℃ and the rotation speed of the stirring is 1000 to 1500 rpm.
3. The method for preparing a thickener according to claim 1, wherein the step of stirring the chloroform solution of the brominated precursor is performed at a temperature of 20 to 30 ℃ and at a rotation speed of 800 to 1200 rpm.
4. The method of claim 1, wherein the polymer monomer is selected from the group consisting of vinyl acetate and ethyl acetate; the mass ratio of the vinyl acetate to the ethyl acetate is (2-6) to (4-8).
5. The method of claim 1, wherein the initiator is azobisisobutyronitrile.
6. A thickener obtained by the production method according to any one of claims 1 to 5.
7. Use of the thickener of claim 6 in the preparation of a fracturing fluid.
8. A fracturing fluid comprising the thickener of claim 6.
9. The fracturing fluid of claim 7, further comprising supercritical CO2The mass ratio of the absolute ethyl alcohol to the thickening agent is (5-8): 100; the weight percentage of the thickening agent in the fracturing fluid is 1-2%.
10. Use of a fracturing fluid according to claim 8 or 9 in shale gas recovery.
CN202010305651.7A 2020-04-17 2020-04-17 Preparation method of thickening agent, fracturing fluid and application Pending CN111303322A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116874789A (en) * 2023-08-03 2023-10-13 西南石油大学 Supercritical carbon dioxide thickener with branched structure and preparation method thereof

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Application publication date: 20200619