CN115304708A - Multi-branch fracturing fluid thickening agent and preparation method thereof - Google Patents
Multi-branch fracturing fluid thickening agent and preparation method thereof Download PDFInfo
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- CN115304708A CN115304708A CN202211231552.4A CN202211231552A CN115304708A CN 115304708 A CN115304708 A CN 115304708A CN 202211231552 A CN202211231552 A CN 202211231552A CN 115304708 A CN115304708 A CN 115304708A
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- 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
- C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
- C08F220/52—Amides or imides
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- C08F220/56—Acrylamide; Methacrylamide
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- C09K8/60—Compositions for stimulating production by acting on the underground formation
- C09K8/62—Compositions for forming crevices or fractures
- C09K8/66—Compositions based on water or polar solvents
- C09K8/68—Compositions based on water or polar solvents containing organic compounds
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- 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
- C09K8/84—Compositions based on water or polar solvents
- C09K8/86—Compositions based on water or polar solvents containing organic compounds
- C09K8/88—Compositions based on water or polar solvents containing organic compounds macromolecular compounds
- C09K8/882—Compositions based on water or polar solvents containing organic compounds macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
Abstract
The invention relates to a multi-branch fracturing fluid thickening agent and a preparation method thereof, belonging to the technical field of oil and gas field development. The method comprises the following steps: reacting 3-butene-1,2-diol, epoxypropanol and potassium ethoxide to obtain an intermediate, and reacting the intermediate with 3,7-dimethyl-6-octenoic acid to obtain a multi-branch prepolymer; uniformly mixing acrylamide, multi-branch prepolymer, oleate double-chain monomer, dissolution accelerator, thiourea stabilizer and water to obtain a mixed solution, introducing nitrogen to remove oxygen, and adding chain transfer agent and initiator to react to obtain a polymer rubber block; then granulating, drying, grinding and sieving to prepareTo obtain the multi-branch fracturing fluid thickening agent. The thickening agent of the invention can resist high-speed shearing and is 511s at 150 DEG C ‑1 The viscosity restoration rate can reach more than 81 percent after shearing for 40min, and the product has excellent temperature resistance, and the temperature is 200 ℃ and 170s ‑1 The viscosity can be maintained at 175 mPas or more after 120min of shear-down.
Description
Technical Field
The invention relates to the technical field of oil and gas field development, in particular to a multi-branch fracturing fluid thickening agent and a preparation method thereof.
Background
The hydraulic fracturing technology is a necessary technology for exploiting shale gas. The hydraulic fracturing technology is that a high-pressure pump set is adopted on the ground to inject high-displacement fracturing fluid into a target rock stratum along a shaft by utilizing the principle of liquid pressure transmission. When the pressure in the well is high enough, it can blow up between the target formations in a direction perpendicular to the wellbore to form a fracture. The hydraulic fracturing technology requires that an oil discharge or exhaust channel with high flow conductivity can be formed, and the purpose of fracturing yield increase is achieved.
In the hydraulic fracturing process, a pumping device injects fracturing fluid into an artificial fracture through a ground pipeline, a shaft and perforation holes at a high pumping speed. At the well bore and perforations, the fracturing fluid is subjected to high shear, which diminishes as the fracturing fluid flows into the fracture. When the conventional fracturing fluid thickening agent is used, under the action of high-speed shearing, the internal reticular structure of the fracturing fluid containing the conventional thickening agent is irreversibly damaged, the viscosity is greatly reduced, so that the propping agent cannot be conveyed to a preset position, and the hydraulic fracturing construction effect is seriously influenced. Therefore, research and development of fracturing fluid with self-repairing performance is urgent, the self-repairing performance can ensure that the viscosity of the fracturing fluid can be quickly recovered after the fracturing fluid enters an artificial crack under high-speed shearing, and a propping agent is pressed to a preset position, so that the hydraulic fracturing effect is ensured.
Huang Zhiyu aiming at the problem that the conventional gel fracturing fluid is difficult to resist high temperature and shear at the same time, a self-repairing fracturing fluid based on dynamic covalent bonds is designed, and the synthesized fracturing fluid is 170s -1 Under the condition of room temperature, the viscosity retention rate can reach 97.6 percent after 3 times of continuous shearing for 3min, but the viscosity retention rate can reach 511s under high shearing -1 Under the condition of continuous 3 times of shearingThe viscosity retention after 2min is only 65.7%; although the self-repairing fracturing fluid is at the temperature of 120 ℃ for 170s -1 The viscosity can reach 174.4 mPa.s after shearing for 2h, but the self-repairing fracturing fluid can keep a certain viscosity after being crosslinked, and the temperature and shear resistance of the self-repairing fracturing fluid under the conditions of higher temperature and higher shear is poor (see: huang Zhiyu, zheng Cunchuan. Preparation of self-repairing fracturing fluid based on dynamic covalent bonds and performance thereof [ J]Oil field chemistry, 2020).
At present, for a thickening agent product which is not further crosslinked, the temperature resistance of the thickening agent product is difficult to reach more than 180 ℃, and the high-temperature resistance and the shear resistance of the thickening agent product are poor; for example, the Chinese patent application CN201310063673.7 synthesizes a thickening agent for fracturing fluid, and when the addition of the prepared thickening agent in water-based fracturing fluid is 0.35 percent, the apparent viscosity is 140 mPa.s, and is 170s -1 And at 95 ℃, continuously shearing for 30min, wherein the viscosity retention rate is only over 60 percent.
In view of the above, it is very desirable to provide a multi-branched fracturing fluid thickening agent and a preparation method thereof.
Disclosure of Invention
The invention provides a multi-branch fracturing fluid thickening agent and a preparation method thereof, aiming at solving one or more technical problems in the prior art.
The invention provides a preparation method of a multi-branched fracturing fluid thickening agent in a first aspect, which comprises the following steps:
(1) 3-butene-1,2-diol, epoxy propanol and potassium ethoxide are used as raw materials to react to obtain an intermediate, and then the intermediate reacts with 3,7-dimethyl-6-octenoic acid to obtain a multi-branch prepolymer;
(2) Uniformly mixing acrylamide, a multi-branch prepolymer, an oleic acid ester double-chain monomer, a dissolution promoter, a thiourea stabilizer and water to obtain a mixed solution, introducing nitrogen into the mixed solution to remove oxygen, and adding a chain transfer agent and an initiator to perform copolymerization reaction to obtain a polymer rubber block;
(3) And sequentially granulating, drying, grinding and sieving the polymer gel block to obtain the multi-branch fracturing fluid thickening agent.
Preferably, in the step (2), before the nitrogen is introduced into the mixed solution to remove oxygen, a flexible monomer is further added into the mixed solution and uniformly mixed; the flexible monomer is 4-hydroxybutyl vinyl ether.
Preferably, the molar ratio of the 3-butene-1,2-diol to the epoxypropanol is 1: (4~6); and/or the mass ratio of the intermediate to the 3,7-dimethyl-6-octenoic acid is 5:2.
Preferably, step (1) comprises the sub-steps of:
(a) Uniformly mixing 3-butene-1,2-diol and potassium ethoxide, introducing nitrogen to remove oxygen, adding epoxy propanol under the protection of inert gas to react, and washing and drying to obtain an intermediate;
(b) And uniformly mixing the intermediate, the organic solvent and the catalyst, introducing nitrogen to remove oxygen, adding 3,7-dimethyl-6-octenoic acid under the protection of inert gas to react, and performing centrifugal separation and drying to obtain the multi-branch prepolymer.
Preferably, in the step (a), the temperature of the reaction is 75 to 85 ℃, and the time of the reaction is 2 to 4 hours; in the step (a), the dosage of the potassium ethoxide is 0.5 to 1.5 percent of the sum of the mass dosages of the 3-butene-1,2-diol and the epoxypropanol; in the step (a), acetone is adopted for washing, and the using amount of the acetone is 45-60% of the sum of the mass using amounts of the 3-butene-1,2-diol and the epoxypropanol; in the step (b), the reaction temperature is 45 to 55 ℃, and the reaction time is 2 to 4 hours; in step (b), the organic solvent is tetrahydrofuran and the catalyst is 4-dimethylaminopyridine; in the step (b), the dosage of the organic solvent is 25 to 40 percent of the sum of the mass dosages of the intermediate and 3,7-dimethyl-6-octenoic acid; and/or in the step (b), the dosage of the catalyst is 1 to 1.5 percent of the sum of the mass dosages of the intermediate and 3,7-dimethyl-6-octenoic acid.
Preferably, the oleate double-chain monomer is cis-9-octadecenoic acid methyl ester and/or cis-9-octadecenoic acid ethyl ester; the cosolvent is tetradecanol polyoxyethylene ether dimethyl hexadecyl ammonium bromide and/or hexadecyl polyoxyethylene ether dimethyl octyl ammonium bromide; the thiourea stabilizer is thiosemicarbazide and/or 4-methyl thiosemicarbazide; the chain transfer agent is one or more of sodium formate, sodium hypophosphite and sodium hypophosphite; and/or the initiator comprises an azodicarboxylate initiator, an organic peroxide oxidant and a reducing agent, wherein the azodicarboxylate initiator is one or more of diisopropyl azodicarboxylate, dibenzyl azodicarboxylate, di-2-methoxyethyl azodicarboxylate and bis (4-chlorobenzyl) azodicarboxylate, the organic peroxide oxidant is tert-butyl hydroperoxide and/or tert-amyl hydroperoxide, and the reducing agent is sodium dithionate and/or sodium formaldehyde sulfoxylate.
Preferably, in the step (2), the mass ratio of the usage amounts of the acrylamide, the multi-branch prepolymer and the oleate double-chain monomer is (80-120): (10 to 20): (20 to 40); and/or the raw materials for preparing the multi-branch fracturing fluid thickening agent comprise, by weight, 80-120 parts of acrylamide, 10-20 parts of a multi-branch prepolymer, 20-40 parts of an oleic acid ester double-chain monomer, 3238 parts of a dissolution promoter, 3238 parts of a thiourea stabilizer, 3262 parts of zxft, 750-840 parts of water, 0.01-0.05 part of a chain transfer agent and 0.8-1.6 parts of an initiator.
Preferably, each raw material for preparing the multi-branch fracturing fluid thickening agent further comprises a flexible monomer, and the mass ratio of the flexible monomer to the acrylamide is (30 to 50): (80 to 120); and/or the initiator comprises an azodicarboxylate initiator, an organic peroxide oxidant and a reducing agent, wherein the mass ratio of the azodicarboxylate initiator to the organic peroxide oxidant to the reducing agent is (0.4-0.8): (0.2 to 0.4): 0.3.
preferably, in step (2): introducing nitrogen to remove oxygen for 10 to 40min; and/or the initiation temperature of the copolymerization reaction is 20 to 22 ℃.
In a second aspect, the present invention provides a multilimbed fracturing fluid thickener obtainable by the process of the invention described in the first aspect.
Compared with the prior art, the invention at least has the following beneficial effects:
(1) The invention designs the multi-branchThe thickening agent synthesized by the multi-branch prepolymer has a multi-branch network structure; meanwhile, the adopted oleate double-chain monomer has the physical characteristic of hydrophobic association and forms a multi-branch association network structure, so that the structure of the multi-branch fracturing fluid thickening agent can be recovered after the multi-branch fracturing fluid thickening agent is damaged by high-speed shearing, the performance of the multi-branch fracturing fluid thickening agent can be recovered to the level before the damage to a certain extent, and the multi-branch fracturing fluid thickening agent can be recovered to the level before the damage at the temperature of 150 ℃ for 511s -1 The viscosity repairing rate can reach more than 81% under the condition of shearing for 40min, and the polymer can keep good self-repairing performance under the condition of high shearing rate.
(2) The multi-branch fracturing fluid thickening agent has excellent temperature resistance, and the temperature is 200 ℃ for 170s -1 After shearing for 120min, the viscosity can be kept above 175 mPa.s, which is much higher than the requirement of industry standard.
(3) The multi-branch fracturing fluid thickening agent synthesized by the invention is exposed to 511s at 150 DEG C -1 The viscosity of the thickening agent is still over 130mPa & s under the condition of shearing for 40min, so that the thickening agent can be ensured to have higher viscosity and excellent sand carrying performance in the whole process of entering a stratum from a fracturing pipeline through a shaft and a hole, the propping agent can be ensured to be conveyed to a preset position, the fracturing operation effect is improved, the advantage is more prominent in the large-discharge-volume fracturing process, the high-temperature deep well and large-discharge-volume fracturing construction operation can be realized, the operation safety is ensured, the operation time can be saved, and the construction cost is saved.
Drawings
FIG. 1 shows the multi-branched fracturing fluid densifier prepared in example 1 of the present invention at a temperature of 150 ℃ and a shear rate of 170s -1 Lower rheological profile;
FIG. 2 shows the multi-branched fracturing fluid densifier prepared in example 1 of the present invention at a temperature of 150 ℃ and a shear rate of 511s -1 Lower rheological profile;
FIG. 3 shows the multi-branched fracturing fluid densifier prepared in example 1 of the present invention at a temperature of 200 deg.C and a temperature of 170s -1 Temperature resistance rheological graph.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
The invention provides a preparation method of a multi-branched fracturing fluid thickening agent in a first aspect, which comprises the following steps:
(1) 3-butene-1,2-diol, epoxy propanol and potassium ethoxide are used as raw materials to react to obtain an intermediate, and then the intermediate reacts with 3,7-dimethyl-6-octenoic acid to obtain a multi-branch prepolymer;
(2) Uniformly mixing acrylamide, a multi-branch prepolymer, an oleic acid ester double-chain monomer, a dissolution promoter, a thiourea stabilizer and water to obtain a mixed solution, introducing nitrogen into the mixed solution to remove oxygen, and adding a chain transfer agent and an initiator to perform copolymerization reaction to obtain a polymer rubber block;
(3) Sequentially granulating, drying, grinding and sieving the polymer gel block to obtain a multi-branch fracturing fluid thickening agent; the conditions for granulating, drying, grinding and sieving are not particularly limited, and the granulation can be carried out under conventional conditions.
The invention provides a preparation method of a multi-branch fracturing fluid thickening agent aiming at the problems of low shear viscosity retention rate under ultrahigh temperature or low viscosity retention rate under high shear condition of the existing fracturing fluid thickening agent, and the prepared multi-branch fracturing fluid thickening agent can self-repair the fracturing fluid thickening agent, so that a polymer not only has excellent shear resistance, but also has outstanding temperature resistance; the thickening agent prepared by the invention has a multi-branch association network structure, so that the fracturing fluid thickening agent can recover the structure after being damaged by high-speed shearing, and the temperature is 150 ℃ and 511 seconds -1 The viscosity repairing rate can reach more than 81 percent under the condition of shearing for 40min, the polymer can keep good self-repairing performance under the condition of high shearing rate, and the thickening agent has excellent temperature resistance, and the temperature of the thickening agent is 170s at 200 DEG C -1 Lower scissorsAfter 120min of cutting, the viscosity can be kept above 175 mPa.s, which is far higher than the requirement of industrial standard, and the multi-branch fracturing fluid thickening agent has excellent temperature resistance and shear resistance.
According to some preferred embodiments, in the step (2), before the nitrogen is introduced into the mixed solution to remove oxygen, a flexible monomer is further added into the mixed solution and mixed uniformly; the flexible monomer is 4-hydroxybutyl vinyl ether.
According to some preferred embodiments, the molar ratio of the 3-butene-1,2-diol to the epoxypropanol is 1: (4~6) (e.g. 3562, 1; and/or the mass ratio of the intermediate to the 3,7-dimethyl-6-octenoic acid is 5:2; in the present invention, it is preferred that the molar ratio of the 3-butene-1,2-diol to the epoxypropanol is 1: (4~6) and the mass ratio of the intermediate to the 3,7-dimethyl-6-octenoic acid is 5:2, so that the multi-branched fracturing fluid thickening agent which has more excellent high temperature resistance and better structure recovery capability after being damaged by high-speed shearing can be obtained.
According to some preferred embodiments, in the step (1), 3-butylene-1,2-diol, epoxy propanol and potassium ethoxide are used as raw materials and are reacted for 2 to 4 hours at 75 to 85 ℃; and/or the dosage of the potassium ethoxide is 0.5 to 1.5 percent of the sum of the mass dosages of the 3-butene-1,2-diol and the epoxypropanol.
According to some preferred embodiments, step (1) comprises the following sub-steps:
(a) Uniformly mixing 3-butene-1,2-diol and potassium ethoxide, introducing nitrogen to remove oxygen, adding epoxy propanol under the protection of inert gas to react, and washing and drying to obtain an intermediate; in the step (a), the time for introducing nitrogen to remove oxygen is, for example, 10 to 40min, and for example, epoxypropanol is added dropwise under the protection of nitrogen to react;
(b) Uniformly mixing the intermediate, an organic solvent and a catalyst, introducing nitrogen to remove oxygen, adding 3,7-dimethyl-6-octenoic acid under the protection of inert gas to react, and performing centrifugal separation and drying to obtain a multi-branch prepolymer; in the step (b), the time for introducing nitrogen to remove oxygen is, for example, 10 to 40min, and for example, 3,7-dimethyl-6-octenoic acid is added dropwise under the protection of nitrogen to carry out the reaction; the operation conditions for the washing, drying and centrifugal separation are not particularly limited, and conventional operations can be adopted.
According to some preferred embodiments, in step (a), the temperature of the reaction is from 75 to 85 ℃ (e.g. 75 ℃, 80 ℃ or 85 ℃) and the time of the reaction is from 2 to 4h (e.g. 2, 3 or 4 h); in step (a), the amount of the potassium ethoxide is 0.5 to 1.5% (e.g., 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4% or 1.5%) of the sum of the mass amounts of the 3-butene-1,2-diol and the epoxypropanol, preferably 1%; in step (a), the washing is performed with acetone, and the amount of acetone is 45 to 60% (for example, 45%, 48%, 50%, 52%, 55%, 58% or 60%) of the sum of the mass amounts of the 3-butene-1,2-diol and the epoxypropanol, and is preferably 50%; in step (b), the temperature of the reaction is 45 to 55 ℃ (for example, 45 ℃, 50 ℃ or 55 ℃), and the time of the reaction is 2 to 4h (for example, 2, 3 or 4 h); in step (b), the organic solvent is tetrahydrofuran and the catalyst is 4-dimethylaminopyridine; in step (b), the amount of the organic solvent is 25 to 40% (e.g., 25%, 28%, 30%, 32%, 35%, 38% or 40%) of the sum of the mass amounts of the intermediate and the 3,7-dimethyl-6-octenoic acid, preferably 30%; and/or in step (b), the amount of the catalyst is 1 to 1.5% (e.g. 1, 1.1%, 1.2%, 1.3%, 1.4% or 1.5%) of the sum of the mass amounts of the intermediate and the 3,7-dimethyl-6-octenoic acid, preferably 1.2%.
In the invention, preferably in the step (a), the reaction temperature is 75-85 ℃, the reaction time is 2-4 h, and preferably the dosage of the potassium ethoxide is 0.5-1.5% of the sum of the mass dosages of the 3-butene-1,2-diol and the epoxypropanol, the reaction temperature, the reaction time and the dosage of the potassium ethoxide in the step (a) have an influence on the structure and the conversion rate of an intermediate, so that the structure of the multi-branch prepolymer is influenced, for example, side reactions and the like can be caused when the reaction temperature is too high, the conversion rate is low when the dosage of the potassium ethoxide is too low, and the like, and the preferable early-stage reaction condition is favorable for synthesizing the multi-branch fracturing fluid thickening agent with better performance because the structure of the multi-branch prepolymer has important influence on the structure of the fracturing fluid thickening agent.
According to some embodiments, the preparation of the multi-branched prepolymer comprises:
(a) Preparing an intermediate: adding 3-butene-1,2-diol and potassium ethoxide into a four-neck flask with a stirrer and a thermometer, introducing nitrogen to remove oxygen for 10min, controlling the system temperature to be 75-85 ℃, dropwise adding epoxy propanol under the protection of the nitrogen, reacting for 3h, adding acetone to wash, and then carrying out vacuum drying to obtain an intermediate; in some embodiments of the invention, it is preferred that the molar ratio of the 3-butene-1,2-diol to the epoxypropanol is 1:5, for example as shown in formula I:
(b) Preparing a multi-branch prepolymer: adding the intermediate, tetrahydrofuran and a catalyst into a four-neck flask with a stirrer and a thermometer, introducing nitrogen to remove oxygen for 10 minutes, controlling the system temperature to be 45-55 ℃, dropwise adding 3,7-dimethyl-6-octenoic acid under the protection of nitrogen, reacting for 3 hours, centrifugally separating out a product serving as a solid phase, and drying in vacuum to obtain a multi-branch prepolymer; in the present invention, the reaction of the intermediate with the 3,7-dimethyl-6-octenoic acid is represented by formula II, for example:
in formula II, RCOOH represents 3,7-dimethyl-6-octenoic acid wherein R has the formula shown in formula III below:
according to some preferred embodiments, the oleate-type double-chain monomer is cis-9-octadecenoic acid methyl ester and/or cis-9-octadecenoic acid ethyl ester (alternative name: cis-9-octadecenoic acid ethyl ester); and/or the cosolvent is tetradecanol polyoxyethylene ether dimethyl hexadecyl ammonium bromide and/or hexadecyl polyoxyethylene ether dimethyl octyl ammonium bromide; in the invention, preferably, the dissolution promoter is tetradecanol polyoxyethylene ether-based dimethylhexadecyl ammonium bromide and/or hexadecanol polyoxyethylene ether-based dimethyloctyl ammonium bromide, the dissolution promoter can promote the dissolution and dispersion of the multi-branch prepolymer, and can improve the distribution condition of the multi-branch prepolymer in a molecular chain, so that the multi-branch prepolymer can be uniformly distributed in a block manner in the molecular chain, and the dissolution performance and the shearing resistance of the prepared multi-branch fracturing fluid thickening agent are influenced; the present invention is not particularly limited in the source of tetradecanol polyoxyethylene ether-based dimethylhexadecyl ammonium bromide and hexadecyl polyoxyethylene ether-based dimethyloctyl ammonium bromide, and any of the commercially available products can be used or synthesized by the existing method, for example, the product available from Zhengzhou easy and fine chemicals Co.
According to some preferred embodiments, the thiourea-based stabilizer is thiosemicarbazide (alternative name: thiosemicarbazide) and/or 4-methyl thiosemicarbazide; the chain transfer agent is one or more of sodium formate, sodium hypophosphite and sodium hypophosphite; and/or the initiator comprises an azodicarboxylate initiator, an organic peroxide oxidant and a reducing agent, wherein the azodicarboxylate initiator is one or more of diisopropyl azodicarboxylate, dibenzyl azodicarboxylate, di-2-methoxyethyl azodicarboxylate (such as methyl di-2-methoxyethyl azodicarboxylate) and bis (4-chlorobenzyl) azodicarboxylate, the organic peroxide oxidant is tert-butyl hydroperoxide and/or tert-amyl hydroperoxide, and the reducing agent is sodium dithionate and/or sodium formaldehyde sulfoxylate. In the invention, preferably, an azodicarbonic acid ester initiator, an organic peroxy oxidant and sodium dithionate and/or sodium formaldehyde sulfoxylate are/is adopted as a reducing agent to form a high-efficiency initiation system, the initiation system can effectively initiate a monomer with lower reaction activity, compared with a conventional initiation system, the initiation system can more effectively initiate the monomer with lower reaction activity, the conversion rate is higher, and the grafting rate of the conventional initiation system to the monomer with lower activity is lower.
In the present invention, the appearance of "and/or" between a plurality of technical features means that the technical features are connected in the "and/or" relationship, and means that any one of the technical features or a combination of any two or more of the technical features can be used.
According to some preferred embodiments, in the step (2), the mass ratio of the usage amounts of the acrylamide, the multi-branch prepolymer and the oleate double-chain monomer is (80-120): (10 to 20): (20 to 40). In the invention, the mass ratio of the usage amounts of the acrylamide, the multi-branch prepolymer and the oleate double-chain monomer is preferably (80-120): (10 to 20): (20-40), so that the multi-branch fracturing fluid thickening agent which has more excellent high-temperature resistance and better structure recovery capability after high-speed shearing failure is obtained.
According to some preferred embodiments, each raw material for preparing the multi-branch fracturing fluid thickening agent comprises, by weight, 80 to 120 parts (e.g., 80, 82, 85, 88, 90, 92, 95, 98, 100, 102, 105, 108, 110, 112, 115, 118 or 120 parts) of acrylamide, 10 to 20 parts (e.g., 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 parts) of a multi-branch prepolymer, 20 to 40 parts (e.g., 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 or 40 parts) of an oleate double-chain monomer, 3238 parts (e.g., 5, 6, 7 or 8 parts) of a dissolution promoter, 3238 parts (e.g., 5, 6, 7 or 8 parts) of a thiourea stabilizer 3262 parts (e.g., 3, 3.5, 4, 4.5 or 5 parts) of water, 32840 parts (e.g., 780, 7 or 8 parts) of a thiourea stabilizer, 3202 parts (e.g., 3.g., 3.05, 1.05, 0.05, 0.1.0, 0, 0.05, or 0.0 parts of an initiator, 0.1.0.05 parts (e.0.0.0.05 parts) of a chain transfer agent, 0.0.0.0.0.05 parts of an initiator, 0.0.0.0.0.0 parts of a chain transfer agent, 0 parts of a chain transfer agent, and 10 parts of an initiator, 10 parts of a 15 parts of a 10 parts of the like.
In the present invention, "parts" means "parts by weight", and in the specific examples and comparative examples, the units of parts by weight may be unified, for example, into the units by weight such as "g" or "kg".
According to some preferred embodiments, each raw material for preparing the multi-branched fracturing fluid thickening agent further comprises a flexible monomer, and the mass ratio of the flexible monomer to the acrylamide is (30-50): (80 to 120), more preferably, the mass ratio of the dosage of the acrylamide, the multi-branch prepolymer, the oleic acid ester double-chain monomer and the flexible monomer is (80 to 120): (10 to 20): (20 to 40): (30-50), so that the high temperature resistance and the high-speed shearing resistance of the multi-branch fracturing fluid thickening agent can be further improved.
According to some specific embodiments, each raw material for preparing the multi-branched fracturing fluid thickening agent further comprises 35 to 50 parts by weight of a flexible monomer.
According to some preferred embodiments, the initiator comprises an azodicarboxylate initiator, an organic peroxy oxidizing agent and a reducing agent, and the mass ratio of the azodicarboxylate initiator to the organic peroxy oxidizing agent to the reducing agent is (0.4 to 0.8): (0.2 to 0.4): 0.3.
according to some specific embodiments, the raw materials for preparing the multi-branch fracturing fluid densifier comprise, by weight, 80 to 120 parts of acrylamide, 10 to 20 parts of a multi-branch prepolymer, 20 to 40 parts of an oleate double-chain monomer, 5~8 parts of a dissolution promoter, 35 to 50 parts of a flexible monomer, 3~5 parts of a thiourea stabilizer, 750 to 840 parts of water, 0.01 to 0.05 part of a chain transfer agent, 0.4 to 0.8 part of an azodicarboxylate initiator, 0.2 to 0.4 part of an organic peroxide oxidant and 0.3 part of a reducing agent.
According to some preferred embodiments, in step (2): the time for introducing nitrogen to remove oxygen is 10 to 40min (for example, 10, 15, 20, 25, 30, 35 or 40 min); and/or the initiation temperature of the copolymerization reaction is 20 to 22 ℃; in the invention, after the copolymerization reaction is initiated at 20-22 ℃, the temperature of the reaction system naturally rises until the reaction system naturally rises to the peak temperature, and the reaction is finished after the temperature of the reaction system is kept unchanged.
In a second aspect, the present invention provides a multilimbed fracturing fluid thickener obtainable by the process of the first aspect of the invention.
The invention will be further illustrated by way of example, but the scope of protection is not limited to these examples.
In the invention, the preparation of the multi-branch prepolymer A comprises the following steps:
(a) The raw materials for preparing the intermediate are as follows: 88 parts of 3-butene-1,2-diol, 370.5 parts of epoxy propanol, 4.6 parts of potassium ethoxide and 229 parts of acetone; the preparation method comprises the following steps: adding 3-butene-1,2-diol and potassium ethylate into a four-neck flask with a stirrer and a thermometer, introducing nitrogen to remove oxygen for 10min, controlling the system temperature to be 80 ℃, dropwise adding epoxy propanol under the protection of nitrogen, reacting for 3h, adding acetone to wash, and performing vacuum drying to obtain an intermediate;
(b) The raw materials for preparing the multi-branch prepolymer are as follows: 350 parts of an intermediate, 140 parts of 3,7-dimethyl-6-octenoic acid, 147 parts of tetrahydrofuran and 5.9 parts of a catalyst (4-dimethylaminopyridine); the preparation method comprises the following steps: adding the intermediate, tetrahydrofuran and a catalyst into a four-neck flask with a stirrer and a thermometer, introducing nitrogen to remove oxygen for 10 minutes, controlling the system temperature to be 50 ℃, dropwise adding 3,7-dimethyl-6-octenoic acid under the protection of nitrogen, reacting for 3 hours, performing centrifugal separation, and performing vacuum drying to obtain the multi-branch prepolymer A.
In the invention, the preparation of the multi-branch prepolymer B comprises the following steps:
(a) The raw materials for preparing the intermediate are as follows: 88 parts of 3-butene-1,2-diol, 296.3 parts of epoxy propanol, 3.8 parts of potassium ethoxide and 192 parts of acetone; the preparation method comprises the following steps: adding 3-butene-1,2-diol and potassium ethylate into a four-neck flask with a stirrer and a thermometer, introducing nitrogen to remove oxygen for 10min, controlling the system temperature to be 80 ℃, dropwise adding epoxy propanol under the protection of nitrogen, reacting for 3h, adding acetone to wash, and performing vacuum drying to obtain an intermediate;
(b) The raw materials for preparing the multi-branch prepolymer are as follows: 300 parts of an intermediate, 3,7-dimethyl-6-octenoic acid 120 parts, tetrahydrofuran 126 parts and a catalyst (4-dimethylaminopyridine) 5 parts; the preparation method comprises the following steps: adding the intermediate, tetrahydrofuran and a catalyst into a four-neck flask with a stirrer and a thermometer, introducing nitrogen to remove oxygen for 10 minutes, controlling the system temperature to be 50 ℃, dropwise adding 3,7-dimethyl-6-octenoic acid under the protection of nitrogen, reacting for 3 hours, performing centrifugal separation, and performing vacuum drying to obtain a multi-branch prepolymer B.
In the invention, the preparation of the multi-branch prepolymer C comprises the following steps:
(a) The raw materials for preparing the intermediate are as follows: 88 parts of 3-butene-1,2-diol, 444.5 parts of epoxy propanol, 5.3 parts of potassium ethoxide and 266 parts of acetone; the preparation method comprises the following steps: adding 3-butene-1,2-diol and potassium ethylate into a four-neck flask with a stirrer and a thermometer, introducing nitrogen to remove oxygen for 10min, controlling the system temperature to be 80 ℃, dropwise adding epoxy propanol under the protection of nitrogen, reacting for 3h, adding acetone to wash, and performing vacuum drying to obtain an intermediate;
(b) The raw materials for preparing the multi-branch prepolymer are as follows: 400 parts of an intermediate, 160 parts of 3,7-dimethyl-6-octenoic acid, 168 parts of tetrahydrofuran and 6.7 parts of a catalyst (4-dimethylaminopyridine); the preparation method comprises the following steps: adding the intermediate, tetrahydrofuran and a catalyst into a four-neck flask with a stirrer and a thermometer, introducing nitrogen to remove oxygen for 10 minutes, controlling the system temperature to be 50 ℃, dropwise adding 3,7-dimethyl-6-octenoic acid under the protection of nitrogen, reacting for 3 hours, performing centrifugal separation, and performing vacuum drying to obtain the multi-branch prepolymer C.
In the invention, the preparation of the multi-branch prepolymer D is as follows:
(a) The raw materials for preparing the intermediate are as follows: 88 parts of 3-butene-1,2-diol, 222.2 parts of epoxy propanol, 3.1 parts of potassium ethoxide and 155 parts of acetone; the preparation method comprises the following steps: adding 3-butene-1,2-diol and potassium ethylate into a four-neck flask with a stirrer and a thermometer, introducing nitrogen to remove oxygen for 10min, controlling the system temperature to be 80 ℃, dropwise adding epoxy propanol under the protection of nitrogen, reacting for 3h, adding acetone to wash, and performing vacuum drying to obtain an intermediate;
(b) The raw materials for preparing the multi-branch prepolymer are as follows: 250 parts of an intermediate, 71.5 parts of 3,7-dimethyl-6-octenoic acid, 96 parts of tetrahydrofuran and 3.9 parts of a catalyst (4-dimethylaminopyridine); the preparation method comprises the following steps: adding the intermediate, tetrahydrofuran and a catalyst into a four-neck flask with a stirrer and a thermometer, introducing nitrogen to remove oxygen for 10 minutes, controlling the system temperature to be 50 ℃, dropwise adding 3,7-dimethyl-6-octenoic acid under the protection of nitrogen, reacting for 3 hours, performing centrifugal separation, and performing vacuum drying to obtain a multi-branch prepolymer D.
Example 1
The raw materials for preparing the multi-branch fracturing fluid thickening agent comprise: 80 parts of acrylamide, 10 parts of a multi-branch prepolymer A, 20 parts of cis-9-octadecenoic acid methyl ester, 5 parts of tetradecanol polyoxyethylene ether dimethyl hexadecyl ammonium bromide, 35 parts of 4-hydroxybutyl vinyl ether, 3 parts of thiosemicarbazide, 840 parts of water, 0.02 part of sodium formate, 0.4 part of diisopropyl azodicarboxylate, 0.3 part of tert-butyl hydroperoxide and 0.3 part of sodium dithionate; the preparation method comprises the following steps: uniformly mixing acrylamide, multi-branch prepolymer A, cis-9-octadecenoic acid methyl ester, tetradecanol polyoxyethylene ether dimethyl hexadecyl ammonium bromide, 4-hydroxybutyl vinyl ether, thiosemicarbazide and water to obtain a mixed solution, adjusting the temperature of the mixed solution to 20 ℃, blowing nitrogen to remove oxygen for 30min, adding sodium formate, diisopropyl azodicarboxylate, tert-butyl hydroperoxide and sodium dithionate to initiate a reaction (the initiation temperature is 20 ℃) to carry out copolymerization reaction to obtain a polymer gel block, and granulating, drying, grinding and sieving the polymer gel block to obtain the multi-branch fracturing fluid densifier.
Example 2
The raw materials for preparing the multi-branch fracturing fluid thickening agent comprise: 100 parts of acrylamide, 15 parts of a multi-branch prepolymer A, 30 parts of cis-9-octadecenoic acid ethyl ester, 6 parts of cetyl polyoxyethylene ether-based dimethyl octyl ammonium bromide, 40 parts of 4-hydroxybutyl vinyl ether, 4 parts of 4-methyl thiosemicarbazide, 800 parts of water, 0.03 part of sodium hypophosphite, 0.6 part of dibenzyl azodicarboxylate, 0.3 part of tert-amyl hydroperoxide and 0.3 part of sodium formaldehyde sulfoxylate; the preparation method comprises the following steps: uniformly mixing acrylamide, multi-branch prepolymer A, cis-9-ethyl octadecenoate, cetyl polyoxyethylene ether dimethyl octyl ammonium bromide, 4-hydroxybutyl vinyl ether, 4-methyl thiosemicarbazide and water to obtain a mixed solution, adjusting the temperature of the mixed solution to 21 ℃, blowing nitrogen to remove oxygen for 30min, adding sodium hypophosphite, dibenzyl azodicarboxylate, tert-amyl hydroperoxide and sodium formaldehyde sulfoxylate to initiate a reaction (the initiation temperature is 21 ℃) to carry out copolymerization reaction to obtain a polymer gel block, and granulating, drying, grinding and sieving the polymer gel block to obtain the multi-branch fracturing fluid thickening agent.
Example 3
The raw materials for preparing the multi-branch fracturing fluid thickening agent comprise: 120 parts of acrylamide, 20 parts of a multi-branch prepolymer A, 40 parts of cis-9-octadecenoic acid methyl ester, 8 parts of cetyl alcohol polyoxyethylene ether dimethyl octyl ammonium bromide, 50 parts of 4-hydroxybutyl vinyl ether, 5 parts of thiosemicarbazide, 750 parts of water, 0.05 part of sodium hypophosphite, 0.8 part of di-2-methoxyethyl azodicarbonic acid methyl ester, 0.4 part of tert-butyl hydroperoxide and 0.3 part of formaldehyde sodium sulfoxylate; the preparation method comprises the following steps: uniformly mixing acrylamide, multi-branch prepolymer A, cis-9-octadecenoic acid methyl ester, cetyl polyoxyethylene ether dimethyl octyl ammonium bromide, 4-hydroxybutyl vinyl ether, thiosemicarbazide and water to obtain a mixed solution, adjusting the temperature of the mixed solution to 22 ℃, blowing nitrogen to remove oxygen for 30min, adding sodium hypophosphite, di-2-methoxyethyl azodicarboxylate, tert-butyl hydroperoxide and sodium formaldehyde sulfoxylate to initiate a reaction (the initiation temperature is 22 ℃) to carry out copolymerization reaction to obtain a polymer gel block, and granulating, drying, grinding and sieving the polymer gel block to obtain the multi-branch fracturing fluid densifier.
Example 4
Example 4 is essentially the same as example 1, except that:
experiments were carried out using a multi-branch prepolymer B instead of the multi-branch prepolymer A.
Example 5
Example 5 is essentially the same as example 1, except that:
the experiment was carried out by replacing the multi-branch prepolymer A with the multi-branch prepolymer C.
Example 6
Example 6 is essentially the same as example 1, except that:
and (3) replacing the multi-branch prepolymer A with the multi-branch prepolymer D to carry out experiments.
Example 7
Example 7 is essentially the same as example 1, except that:
the raw material for preparing the multi-branch fracturing fluid thickening agent does not contain flexible monomer 4-hydroxybutyl vinyl ether, and the 4-hydroxybutyl vinyl ether is not added in the process of preparing the multi-branch fracturing fluid thickening agent.
Example 8
The raw materials for preparing the multi-branch fracturing fluid thickening agent comprise: 130 parts of acrylamide, 8 parts of a multi-branch prepolymer A, 15 parts of cis-9-octadecenoic acid methyl ester, 5 parts of tetradecanol polyoxyethylene ether dimethyl hexadecyl ammonium bromide, 25 parts of 4-hydroxybutyl vinyl ether, 3 parts of thiosemicarbazide, 807 parts of water, 0.02 part of sodium formate, 0.4 part of diisopropyl azodicarboxylate, 0.3 part of tert-butyl hydroperoxide and 0.3 part of sodium dithionate; the preparation method comprises the following steps: uniformly mixing acrylamide, multi-branch prepolymer A, cis-9-octadecenoic acid methyl ester, tetradecanol polyoxyethylene ether dimethyl hexadecyl ammonium bromide, 4-hydroxybutyl vinyl ether, thiosemicarbazide and water to obtain a mixed solution, adjusting the temperature of the mixed solution to 20 ℃, blowing nitrogen to remove oxygen for 30min, adding sodium formate, diisopropyl azodicarboxylate, tert-butyl hydroperoxide and sodium dithionate to initiate a reaction (the initiation temperature is 20 ℃) to carry out copolymerization reaction to obtain a polymer gel block, and granulating, drying, grinding and sieving the polymer gel block to obtain the multi-branch fracturing fluid densifier.
Example 9
The raw materials for preparing the multi-branch fracturing fluid thickening agent comprise: 70 parts of acrylamide, 25 parts of a multi-branch prepolymer A, 45 parts of cis-9-octadecenoic acid methyl ester, 5 parts of tetradecanol polyoxyethylene ether dimethyl hexadecyl ammonium bromide, 60 parts of 4-hydroxybutyl vinyl ether, 3 parts of thiosemicarbazide, 785 parts of water, 0.02 part of sodium formate, 0.4 part of diisopropyl azodicarboxylate, 0.3 part of tert-butyl hydroperoxide and 0.3 part of sodium dithionate; the preparation method comprises the following steps: uniformly mixing acrylamide, multi-branch prepolymer A, cis-9-octadecenoic acid methyl ester, tetradecanol polyoxyethylene ether dimethyl hexadecyl ammonium bromide, 4-hydroxybutyl vinyl ether, thiosemicarbazide and water to obtain a mixed solution, adjusting the temperature of the mixed solution to 20 ℃, blowing nitrogen to remove oxygen for 30min, adding sodium formate, diisopropyl azodicarboxylate, tert-butyl hydroperoxide and sodium dithionate to initiate a reaction (the initiation temperature is 20 ℃) to carry out copolymerization reaction to obtain a polymer gel block, and granulating, drying, grinding and sieving the polymer gel block to obtain the multi-branch fracturing fluid densifier.
The product prepared by the embodiment has poor solubility, and when the injected water of the Changqing oilfield is selected as the water for testing and the liquid to be tested with the mass concentration of 6 per mill for testing is prepared, all the particles are small undissolved particles, so that the related performance test is not carried out.
Example 10
The raw materials for preparing the multi-branch fracturing fluid thickening agent comprise: 80 parts of acrylamide, 10 parts of a multi-branch prepolymer A, 20 parts of cis-9-octadecenoic acid methyl ester, 5 parts of tetradecanol polyoxyethylene ether dimethyl hexadecyl ammonium bromide, 35 parts of 4-hydroxybutyl vinyl ether, 3 parts of thiosemicarbazide, 840 parts of water, 0.02 part of sodium formate, 0.4 part of azodiisobutyl amidine hydrochloride, 0.3 part of ammonium persulfate and 0.3 part of sodium bisulfite; the preparation method comprises the following steps: uniformly mixing acrylamide, multi-branch prepolymer A, cis-9-octadecenoic acid methyl ester, tetradecanol polyoxyethylene ether dimethyl hexadecyl ammonium bromide, 4-hydroxybutyl vinyl ether, thiosemicarbazide and water to obtain a mixed solution, adjusting the temperature of the mixed solution to 20 ℃, blowing nitrogen to remove oxygen for 30min, adding sodium formate, azodiisobutylamine hydrochloride, ammonium persulfate and sodium bisulfite to initiate a reaction (the initiation temperature is 20 ℃) to carry out copolymerization reaction to obtain a polymer gel block, and granulating, drying, grinding and sieving the polymer gel block to obtain the multi-branch fracturing fluid thickening agent.
Comparative example 1
Comparative example 1 is substantially the same as example 1 except that:
the raw materials for preparing the multi-branch fracturing fluid thickening agent do not contain the multi-branch prepolymer A, and the multi-branch prepolymer A is not added in the process of preparing the multi-branch fracturing fluid thickening agent.
Comparative example 2
Comparative example 2 is substantially the same as example 1 except that:
the raw material for preparing the multi-branch type fracturing fluid thickening agent does not contain cis-9-octadecenoic acid methyl ester, and the cis-9-octadecenoic acid methyl ester is not added in the process of preparing the multi-branch type fracturing fluid thickening agent.
Comparative example 3
Comparative example 3 is substantially the same as example 1 except that:
the raw materials for preparing the multi-branch fracturing fluid thickening agent do not contain a solvent tetradecanol polyoxyethylene ether dimethyl hexadecyl ammonium bromide, and the solvent tetradecanol polyoxyethylene ether dimethyl hexadecyl ammonium bromide is not added in the process of preparing the multi-branch fracturing fluid thickening agent.
The product of this comparative example was poorly soluble and not suitable for use as a fracturing fluid densifier, and the product of comparative example 3 was not tested for performance.
Comparative example 4
Comparative example 4 is substantially the same as example 1 except that:
the raw material for preparing the multi-branch fracturing fluid thickening agent does not contain thiosemicarbazide, and the thiosemicarbazide is not added in the process of preparing the multi-branch fracturing fluid thickening agent.
Comparative example 5
Comparative example 5 is substantially the same as example 1 except that:
carrying out experiments by using an intermediate to replace the multi-branch prepolymer A;
the preparation of the intermediate is as follows: the raw materials for preparing the intermediate are as follows: 88 parts of 3-butene-1,2-diol, 370.5 parts of epoxy propanol, 4.6 parts of potassium ethoxide and 229 parts of acetone; the preparation method comprises the following steps: adding 3-butene-1,2-diol and potassium ethylate into a four-neck flask with a stirrer and a thermometer, introducing nitrogen to remove oxygen for 10min, controlling the system temperature to be 80 ℃, dropwise adding epoxy propanol under the protection of nitrogen, reacting for 3h, adding acetone to wash, and then carrying out vacuum drying to obtain an intermediate.
And (3) comparing and evaluating the fracturing fluid thickening agents prepared in the examples and the various proportions, and respectively detecting the temperature resistance and the shear resistance of the fracturing fluid thickening agent products prepared in the examples and the various proportions.
The shear resistance test method comprises the following steps: the fracturing fluid thickening agents in the examples and the comparative examples are prepared into a to-be-tested fluid with the fracturing fluid thickening agent mass concentration (mass fraction) of 6 per mill by using injection water of the Changqing oil field as test water, and the following tests are carried out:
by usingHaake MARS 40 high temperature rheometer, with a shear rate of 170s at 150 ℃ C -1 Testing the viscosity of the liquid to be tested; two methods are respectively adopted to investigate the shear resistance of the fracturing fluid densifier: the first method is that the Haake MARS 40 type high temperature rheometer is heated to 150 ℃, the temperature is kept for 10min, and then the shear rate is 170s -1 Shearing for 2min, the viscosity being set at 170s -1 Initial viscosity, standing for 1min at a shear rate of 170s -1 Shearing for 10min, standing for 3min, and shearing for 10min, wherein the measured viscosity is 170s -1 Lower rheological viscosity, results are shown in table 1; the second method is that the Haake MARS 40 type high temperature rheometer is heated to 150 ℃, and after the temperature is kept for 10min, the shearing rate is 511s -1 Shearing for 2min, at which time the viscosity is set at 511s -1 Initial viscosity, standing for 1min at a shear rate of 511s -1 Shearing for 10min, standing for 3min, and shearing for 10min, wherein the measured viscosity is 511s -1 Lower rheological viscosity, results are shown in table 2; the shear resistance of the fracturing fluid densifier was tested by the two methods described above; in the present invention, 170s in Table 1 -1 Lower viscosity repair rate, 170s, for example -1 The lower viscosity repair rate is 170s -1 Lower rheological viscosity and 170s -1 Ratio of lower initial viscosity.
Testing temperature resistance: adopting Haake MARS 40 type high temperature rheometer to test the temperature of the liquid to be tested at 200 ℃ and the shear rate of 170s -1 The viscosity after 120min of downshearing, i.e. the rheological viscosity at 200 ℃, is shown in table 2.
Table 1: the fracturing fluid thickening agent in each example and comparative example is 170s -1 Shear resistance at
Table 2: the fracturing fluid densifier in each of the examples and comparative examples is 511s -1 Shear resistance and temperature resistance
In tables 1 and 2, the symbol "-" indicates that the performance index was not tested.
As can be seen from the data in tables 1 and 2, the multi-branched fracturing fluid thickening agent prepared by the invention not only has excellent shearing resistance, but also has outstanding temperature resistance, and in some more preferred embodiments of the invention, the viscosity recovery rate is more than 80% at different shearing rates, and the viscosity recovery rate is more than 150 ℃ and 170s -1 The viscosity restoration rate can reach more than 95% under the condition of shearing for 40min, and the viscosity restoration rate can reach 511s at 150 DEG C -1 The viscosity repairing rate can reach more than 81% under the condition of shearing for 40min, and the viscosity repairing rate can reach 170s at 200 DEG C -1 After shearing for 120min, the viscosity is kept above 175 mPas, which is much higher than the industrial standard requirement.
The invention has not been described in detail and is in part known to those of skill in the art.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A preparation method of a multi-branch fracturing fluid thickening agent is characterized by comprising the following steps:
(1) 3-butylene-1,2-diol, epoxy propanol and potassium ethoxide are taken as raw materials to react to obtain an intermediate, and then the intermediate is reacted with 3,7-dimethyl-6-octenoic acid to obtain a multi-branch prepolymer;
(2) Uniformly mixing acrylamide, a multi-branch prepolymer, an oleic acid ester double-chain monomer, a dissolution promoter, a thiourea stabilizer and water to obtain a mixed solution, introducing nitrogen into the mixed solution to remove oxygen, and adding a chain transfer agent and an initiator to perform copolymerization reaction to obtain a polymer rubber block;
(3) And sequentially granulating, drying, grinding and sieving the polymer gel block to obtain the multi-branch fracturing fluid thickening agent.
2. The method of claim 1, wherein:
in the step (2), before introducing nitrogen into the mixed solution to remove oxygen, adding a flexible monomer into the mixed solution and uniformly mixing;
the flexible monomer is 4-hydroxybutyl vinyl ether.
3. The method of claim 1, wherein:
the molar ratio of the 3-butene-1,2-diol to the epoxypropanol is 1: (4~6); and/or
The mass ratio of the intermediate to the 3,7-dimethyl-6-octenoic acid is 5:2.
4. The method for preparing according to claim 1, wherein the step (1) comprises the substeps of:
(a) Uniformly mixing 3-butene-1,2-diol and potassium ethoxide, introducing nitrogen to remove oxygen, adding epoxy propanol under the protection of inert gas to react, and washing and drying to obtain an intermediate;
(b) And uniformly mixing the intermediate, the organic solvent and the catalyst, introducing nitrogen to remove oxygen, adding 3,7-dimethyl-6-octenoic acid under the protection of inert gas to react, and performing centrifugal separation and drying to obtain the multi-branch prepolymer.
5. The method of claim 4, wherein:
in the step (a), the reaction temperature is 75-85 ℃, and the reaction time is 2-4 h;
in the step (a), the dosage of the potassium ethoxide is 0.5 to 1.5 percent of the sum of the mass dosages of the 3-butene-1,2-diol and the epoxypropanol;
in the step (a), acetone is adopted for washing, and the using amount of the acetone is 45-60% of the sum of the mass using amounts of the 3-butene-1,2-diol and the epoxypropanol;
in the step (b), the reaction temperature is 45 to 55 ℃, and the reaction time is 2 to 4 hours;
in step (b), the organic solvent is tetrahydrofuran and the catalyst is 4-dimethylaminopyridine;
in the step (b), the dosage of the organic solvent is 25 to 40 percent of the sum of the mass dosages of the intermediate and 3,7-dimethyl-6-octenoic acid; and/or
In the step (b), the dosage of the catalyst is 1 to 1.5 percent of the sum of the mass dosages of the intermediate and the 3,7-dimethyl-6-octenoic acid.
6. The production method according to claim 1, characterized in that:
the oleic acid ester double-chain monomer is cis-9-octadecenoic acid methyl ester and/or cis-9-octadecenoic acid ethyl ester;
the cosolvent is tetradecanol polyoxyethylene ether dimethyl hexadecyl ammonium bromide and/or hexadecyl polyoxyethylene ether dimethyl octyl ammonium bromide;
the thiourea stabilizer is thiosemicarbazide and/or 4-methyl thiosemicarbazide;
the chain transfer agent is one or more of sodium formate, sodium hypophosphite and sodium hypophosphite; and/or
The initiator comprises an azodicarboxylate initiator, an organic peroxide oxidant and a reducing agent, wherein the azodicarboxylate initiator is one or more of diisopropyl azodicarboxylate, dibenzyl azodicarboxylate, di-2-methoxyethyl azodicarboxylate and bis (4-chlorobenzyl) azodicarboxylate, the organic peroxide oxidant is tert-butyl hydroperoxide and/or tert-amyl hydroperoxide, and the reducing agent is sodium dithionate and/or sodium formaldehyde sulfoxylate.
7. The production method according to any one of claims 1 to 6, characterized in that:
in the step (2), the mass ratio of the usage amounts of the acrylamide, the multi-branch prepolymer and the oleate double-chain monomer is (80-120): (10 to 20): (20 to 40); and/or
The raw materials for preparing the multi-branch fracturing fluid densifier comprise, by weight, 80-120 parts of acrylamide, 10-20 parts of a multi-branch prepolymer, 20-40 parts of an oleic acid ester double-chain monomer, 3238 parts of a dissolution promoter, 3262 parts of a thiourea stabilizer, 3262 parts of water, 750-840 parts of water, 0.01-0.05 part of a chain transfer agent and 0.8-1.6 parts of an initiator.
8. The method for producing according to claim 7, characterized in that:
the raw materials for preparing the multi-branch fracturing fluid thickening agent further comprise a flexible monomer, and the mass ratio of the flexible monomer to the acrylamide is (30-50): (80 to 120); and/or
The initiator comprises an azodicarbonic acid ester initiator, an organic peroxide oxidant and a reducing agent, wherein the mass ratio of the azodicarbonic acid ester initiator to the organic peroxide oxidant to the reducing agent is (0.4-0.8): (0.2 to 0.4): 0.3.
9. the production method according to any one of claims 1 to 6, characterized in that, in step (2):
introducing nitrogen to remove oxygen for 10 to 40min; and/or
The initiation temperature of the copolymerization reaction is 20 to 22 ℃.
10. A multilimbed fracturing fluid thickener obtainable by the process of any of claims 1 to 9.
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| WO2014183495A1 (en) * | 2013-05-16 | 2014-11-20 | 西南石油大学 | Associative non-crosslinked fracturing fluid and preparation method therefor |
| CN112521560A (en) * | 2020-12-07 | 2021-03-19 | 西安长庆化工集团有限公司 | Efficient salt-resistant one-agent dual-purpose thickening agent and preparation method and application thereof |
| CN113929801A (en) * | 2021-12-07 | 2022-01-14 | 东营宝莫环境工程有限公司 | Preparation method of thickening agent for ultrahigh-temperature acidizing and fracturing |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2014183495A1 (en) * | 2013-05-16 | 2014-11-20 | 西南石油大学 | Associative non-crosslinked fracturing fluid and preparation method therefor |
| CN112521560A (en) * | 2020-12-07 | 2021-03-19 | 西安长庆化工集团有限公司 | Efficient salt-resistant one-agent dual-purpose thickening agent and preparation method and application thereof |
| CN113929801A (en) * | 2021-12-07 | 2022-01-14 | 东营宝莫环境工程有限公司 | Preparation method of thickening agent for ultrahigh-temperature acidizing and fracturing |
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