Polymer fracturing fluid thickening agent with rigid rotation inhibition structure as well as preparation method and application of polymer fracturing fluid thickening agent
By optimizing the molecular structure of water-based fracturing fluid thickeners and adopting rigid spin-blocked polymer fracturing fluid thickeners, the problem of viscosity reduction in high-salinity brine has been solved, achieving efficient and low-cost fracturing effects, reducing reservoir damage, and increasing oil and gas well production.
Patent Information
- Application Number
- CN202511887825.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-15
- Publication Date
- 2026-02-17
AI Technical Summary
Existing water-based fracturing fluid thickeners exhibit a significant decrease in viscosity in high-salinity brine, resulting in low viscosity retention. The use of multiple thickeners increases costs and reservoir damage risks, making it difficult to achieve the fracturing requirements of low damage and high production.
A rigid-rotation-blocking polymer fracturing fluid thickener is adopted. By introducing components such as potassium acrylate, potassium 2-acrylamido-2-methylpropanesulfonate, rotor-blocking cyclic monomers and rigid long carbon chain monomers, the molecular structure is optimized to improve salt resistance and molecular chain rigidity. Combined with perfluorinated surfactants to reduce the interfacial tension of the liquid, a multi-effect thickening effect is achieved with one agent.
It maintains high viscosity in high-salinity brine, is temperature resistant up to 150℃, is shear resistant, reduces reservoir damage, and has anti-swelling and drainage functions, thereby reducing costs and increasing oil and gas well production.
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Figure CN121537573A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to fracturing fluid thickeners in oilfield chemicals, applied in the field of oil and gas field drilling fracturing, especially in the field of water-based fracturing, specifically a rigid spin-blocking polymer fracturing fluid thickener, its preparation method, and its application. Background Technology
[0002] Water-based fracturing is one of the most crucial reservoir stimulation technologies in oil and gas field development. Specifically, it involves injecting a water-based continuous phase fracturing fluid into the oil and gas reservoir using a high-pressure pump system. The high pressure creates artificial fractures in the reservoir, and proppant (such as quartz sand or ceramsite) is then injected into these fractures, ultimately forming highly conductive flow channels and significantly increasing oil and gas well production. In recent years, water-based fracturing has been widely applied not only in conventional oil and gas reservoirs, especially low-permeability and ultra-low-permeability reservoirs, but also in unconventional oil and gas reservoirs such as shale oil and gas reservoirs, tight sandstone oil and gas reservoirs, and coal-fired gas formations. Water-based fracturing fluids offer advantages such as wide availability of water, low cost, high safety, strong reservoir adaptability, good stimulation effects, and adjustable drag reduction and proppant carrying capacity. However, they also present challenges, including difficulties in preparing high-salinity brine and complex water quality solutions, poor high-temperature resistance, reservoir damage risk, high water consumption, and difficulties in treating and utilizing flowback fluids.
[0003] Water-based fracturing fluid thickeners mainly include natural plant gum thickeners, synthetic polymer thickeners, and viscoelastic surfactants. Among them, polymer thickeners have advantages such as precisely designable molecular structures, temperature and salt resistance, low residue, easy degradation, adjustable drag reduction and proppant carrying capacity, and wide application range. When preparing water-based fracturing fluids, thickeners are mainly used to increase the fluid viscosity and proppant carrying capacity. Simultaneously, fracturing additives such as crosslinking agents, breaker agents, anti-swelling agents, and flow aids are added according to the actual situation to exert their respective effects, forming the water-based fracturing fluid. However, when the salinity of the prepared water is high, although polymer thickeners have a certain degree of salt resistance, the viscosity decreases significantly due to the high salt concentration, especially the influence of high-valence ions, resulting in a low viscosity retention rate. Using multiple agents simultaneously increases the overall cost of fracturing materials, equipment, and labor. Furthermore, there is a risk of synergistic failure of various fracturing additives, and excessive residues can exacerbate reservoir damage, leading to a long-term decline in production capacity.
[0004] Based on the above problems, it is urgent to develop super salt-resistant and multi-functional polymer-based fracturing fluid thickeners to improve the salt resistance of polymers themselves and integrate the functions of additives, thereby reducing the types and amounts of additives used. This is to fundamentally solve the problems of high salt resistance and incompatibility conflicts, residual damage, and high costs caused by excessive use of additives, and to achieve the practical needs of fracturing with "less additives, less damage, lower cost, and higher yield". Summary of the Invention
[0005] In view of this, the main objective of this disclosure is to provide a rigid spin-blocking polymer fracturing fluid thickener, its preparation method, and its application, so as to at least partially solve the technical problems existing in the prior art.
[0006] To achieve the above objectives, this disclosure provides a rigid swirl-blocking polymer fracturing fluid thickener, which comprises the following raw material components by mass percentage: 30.2-55.8% deionized water, 2-5% co-solvent, 20-25% acrylamide, 8-12% potassium acrylate, 8-12% potassium 2-acrylamido-2-methylpropanesulfonate, 2-5% swirl-blocking cyclic monomer, 1-3% rigid long-chain monomer, 2-4% perfluorinated surfactant, 1-3% chain transfer agent, 0.1-0.3% azo initiator, and 0.1-0.5% redox initiator.
[0007] In the above scheme, the cosolvent includes any one or a combination of two of glyceryl carbonate, ethylene carbonate, and dimethyl carbonate; the blocked cyclic monomer includes vinylene carbonate and ethylene ethylene carbonate, each accounting for 50% of the mass of the structural monomer; the perfluorinated surfactant is sodium perfluorononenoxybenzenesulfonate and perfluorooctyl polyoxyethylene ether, each accounting for 50% of the mass of the perfluorinated surfactant; the chain transfer agent is any one of potassium formate and potassium acetate; the azo initiator includes azobisisobutylimidazoline hydrochloride and azobisisobutylamidine hydrochloride, each accounting for 50% of the mass of the azo initiator; the redox system initiator includes tert-butyl hydroperoxide and sodium metabisulfite, each accounting for 50% of the mass of the redox system initiator.
[0008] In the above scheme, the rigid long carbon chain monomer is either dodecyloxymethylacrylamide or hexadecyloxymethylacrylamide.
[0009] In the above scheme, the rigid long carbon chain monomer is prepared by the following method:
[0010] Step A: Keep the temperature inside the reactor at 0~5℃, and add dichloromethane 62~74%, dodecyl chloride or hexadecyl chloride 15~20%, pyridine 5~8%, and N-hydroxymethylacrylamide 6~10% by mass percentage, and stir until dissolved;
[0011] Step B: Seal the reactor and stir the reaction at 0~5℃ for 4~6 hours;
[0012] Step C: After the reaction is complete, remove the product and vacuum dry it in a vacuum drying oven at 25~35℃ for 6~8 hours;
[0013] Step D: The obtained yellow solid was purified by pulping with ethyl acetate and then filtered.
[0014] Step E: Take the filter residue and dry it in a vacuum drying oven at 40~50℃ for 2~4 hours. The white solid obtained is dodecyloxymethylacrylamide or hexadecyloxymethylacrylamide.
[0015] This disclosure also provides a method for preparing a rigid spin-blocking polymer fracturing fluid thickener, the method comprising:
[0016] Step S1: Dissolve the cosolvent, acrylamide, potassium acrylate, potassium 2-acrylamido-2-methylpropanesulfonate, blocked cyclic monomer, rigid long carbon chain monomer, perfluorinated surfactant and chain transfer agent in deionized water according to the mass percentages stated above.
[0017] Step S2: Add initiator to initiate multi-stage initiation;
[0018] Step S3: Post-process the polymer block after polymerization to obtain the rigid spin-blocked polymer fracturing fluid thickener.
[0019] In the above scheme, step S1, which involves dissolving the cosolvent, acrylamide, potassium acrylate, potassium 2-acrylamido-2-methylpropanesulfonate, blocked cyclic monomer, rigid long-chain monomer, perfluorinated surfactant, and chain transfer agent in deionized water according to the stated mass percentages, includes: maintaining the temperature inside the reactor at 2-10°C; sequentially adding the formulated amounts of deionized water, cosolvent, acrylamide, potassium acrylate, potassium 2-acrylamido-2-methylpropanesulfonate, blocked cyclic monomer, and rigid long-chain monomer to the reactor, stirring until homogeneous, and maintaining the stirring state; then sequentially adding the formulated amounts of perfluorinated surfactant and chain transfer agent, stirring thoroughly to ensure that all raw material components are completely dissolved in the deionized water.
[0020] In the above scheme, the addition of initiators in step S2 for multi-stage initiation includes: adding the formulated amount of azo initiator and redox system initiator while maintaining stirring to initiate the polymerization reaction; then sealing the reactor and naturally heating it to 60~80℃, and keeping it insulated for 4~8 hours.
[0021] In the above scheme, the post-processing of the polymer block after the polymerization reaction in step S3 includes: after the polymerization reaction is completed, granulating, drying, crushing and packaging the polymer block to obtain the rigid spin-blocking polymer fracturing fluid thickener.
[0022] In the above scheme, the performance of the rigid spin-blocking polymer fracturing fluid thickener was tested, and the test results are as follows:
[0023] A 0.4% by mass thickener, stirred at 600 rpm for 1 min in deionized water, achieves a viscosity ≥ 80 mPa·s.
[0024] A 0.4% (w / w) thickener, when stirred at 600 rpm for 1 min in a standard brine solution, produces a viscosity ≥40 mPa·s (the standard brine has a total mineralization of 85000 mg / L and is formulated as follows: by mass percentage, it contains 2.0% KCl, 5.5% NaCl, 0.45% MgCl2, and 0.55% CaCl2, with the remainder being deionized water).
[0025] A 0.4% (w / w) thickener was stirred at 600 rpm for 2 min in an ultra-high mineralization brine solution until the viscosity reached ≥30 mPa·s (the total mineralization of the ultra-high mineralization brine was 300,000 mg / L, and the formula was: by mass percentage, it contained 2% KCl, 13% NaCl, 2% MgCl2 and 13% CaCl2, with the remainder being deionized water).
[0026] A 0.1% by mass thickener exhibits a drag reduction rate ≥70% in deionized aqueous solutions.
[0027] 0.6% (w / w) deionized water thickener at 150°C for 100 seconds -1 Viscosity ≥ 20 mPa·s after 90 min of shearing.
[0028] This disclosure also provides an application of a rigid swirl-blocking polymer fracturing fluid thickener in the field of oil and gas field drilling fracturing. The rigid swirl-blocking polymer thickener is either the rigid swirl-blocking polymer thickener described above, or a rigid swirl-blocking polymer thickener prepared by the method described above.
[0029] This disclosure also provides an application of a rigid swirl-blocking polymer thickener in the field of water-based fracturing. The rigid swirl-blocking polymer thickener is either the rigid swirl-blocking polymer thickener described above, or a rigid swirl-blocking polymer thickener prepared by the method described above.
[0030] As can be seen from the above technical solution, the rigid spin-blocking polymer fracturing fluid thickener, its preparation method, and its application provided in this disclosure have the following beneficial effects compared to the prior art:
[0031] 1. Ultra-fast dissolution: The thickener incorporates potassium acrylate and potassium 2-acrylamido-2-methylpropanesulfonate. The large number of carboxyl and sulfonic acid groups on the molecular chain can significantly improve the hydrophilicity of the thickener. Furthermore, the addition of chain transfer agents regulates the molecular weight and structural distribution of the polymer and inhibits internal cross-linking. Therefore, it dissolves ultra-fast in water and salt water, with a dissolution time of only 1 to 2 minutes.
[0032] 2. Superior Salt Tolerance: The introduction of potassium 2-acrylamido-2-methylpropanesulfonate into the thickener enhances salt tolerance; the introduced cyclic monomers give the polymer main chain and branches a five-membered ring structure, significantly increasing the resistance to inward rotation within and between molecular chains, thus effectively preventing the molecular chains from rotating inward and contracting; simultaneously, the introduction of rigid long-chain monomers increases the overall rigidity of the molecular chains and enhances the interaction between molecular chains through van der Waals forces. These three salt tolerance mechanisms work synergistically, enabling the thickener to tolerate salt concentrations up to 300,000 mg / L while reducing its sensitivity to high-valence metal ions such as calcium and magnesium ions.
[0033] 3. Temperature and Shear Resistance: The thickener incorporates hindered cyclic monomers to prevent the molecular chains from rotating inward and contracting; simultaneously, rigid long-chain monomers are introduced to improve the overall rigidity of the molecular chains. Therefore, the structure is more stable, resulting in a temperature resistance of up to 150℃ and greater shear resistance.
[0034] 4. Integrated construction for drag reduction and sand carrying: The thickener has a linear main chain and high molecular weight. By adjusting the concentration in real time, it can meet the integrated construction requirements of drag reduction of low-viscosity slickwater and sand addition of high-concentration sand carrying liquid.
[0035] 5. Multifunctional anti-swelling and drainage aid: The two perfluorinated surfactants introduced into the thickener work synergistically to effectively reduce the interfacial tension of the liquid surface and improve drainage aid performance; the potassium ions after the thickener is dissolved form ion-lattice bonds by embedding into the clay lattice voids and neutralize the negative charge on the clay surface, effectively preventing clay particle agglomeration, inhibiting clay swelling and dispersion, and having excellent anti-swelling effect, thus improving anti-swelling performance.
[0036] 6. Low damage and no pollution: The formulated fracturing fluid leaves no residue and has anti-swelling and drainage-aiding effects, which can significantly reduce the damage of the fluid to the formation, thus facilitating a substantial increase in oil and gas production; at the same time, there are no heavy metal residues, and the flowback fluid can be reused, which will not cause environmental pollution and is environmentally friendly. Attached Figure Description
[0037] To gain a more complete understanding of this disclosure and its advantages, reference will now be made to the following description taken in conjunction with the accompanying drawings, wherein:
[0038] Figure 1 This is a flowchart of a method for preparing rigid long-chain monomers according to embodiments of the present disclosure.
[0039] Figure 2 This is a flowchart of a method for preparing a rigid spin-blocked polymer fracturing fluid thickener according to embodiments of the present disclosure. Detailed Implementation
[0040] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.
[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0042] The researchers of this disclosure have discovered the following problems when using fracturing fluid thickeners to prepare water-based fracturing fluids: (1) When the salinity of the water used to prepare the fracturing fluid is high, although the thickener has a certain salt resistance, the viscosity decreases significantly due to the influence of high salt concentration, especially high-valence ions such as calcium and magnesium ions, and the viscosity retention rate is too low; (2) The simultaneous use of multiple agents increases the overall construction material, equipment and labor costs of fracturing, and there is a risk of synergistic failure of various fracturing additives, as well as excessive residues that aggravate reservoir damage, resulting in a long-term decline in production capacity. Therefore, it is necessary to develop super salt-resistant and multi-functional polymer fracturing fluid thickeners to improve the salt resistance of the polymer itself and integrate the functions of additives, reduce the types and amounts of additives, and fundamentally solve the problems of high salt resistance and incompatibility conflicts, residual damage and high costs caused by excessive use of additives, so as to realize the practical needs of fracturing of "less additives, less damage, lower cost and higher production".
[0043] To this end, the researchers of this publication, through in-depth theoretical and experimental research and through molecular design optimization and innovation, have provided a rigid spin-blocking polymer fracturing fluid thickener to meet the higher requirements of water-based fracturing in oil and gas fields.
[0044] To address the aforementioned issues, the R&D team conducted in-depth research on the molecular structure, mechanism of action, and functional integration of fracturing fluid thickeners. They creatively utilized sulfonate monomers, cyclohexane monomers, rigid long-chain monomers, and perfluorinated surfactants, and through continuous improvement of the preparation formula and optimization of the preparation method, successfully prepared a rigid cyclohexane polymer fracturing fluid thickener that meets the requirements of field applications.
[0045] Specifically, in the preparation method, any one or a combination of two of glyceryl carbonate, ethylene carbonate, and dimethyl carbonate are introduced into the rigid-rotation polymer fracturing fluid thickener as a co-solvent; vinylene carbonate and ethylene ethylene carbonate are introduced, each accounting for 50% of the mass of the structural monomer as a rotor-rotated cyclic monomer; any one of dodecyloxymethylacrylamide and hexadecyloxymethylacrylamide is introduced as a rigid long-chain monomer; sodium perfluorononenoxybenzenesulfonate and perfluorooctyl polyoxyethylene ether are introduced, each accounting for 50% of the mass of the perfluorosurfactant as a perfluorosurfactant; any one of potassium formate and potassium acetate is introduced as a chain transfer agent; azobisisobutyrazoline hydrochloride and azobisisobutyramidine hydrochloride are introduced, each accounting for 50% of the mass of the azo initiator as an azo initiator; tert-butyl hydroperoxide and sodium metabisulfite are introduced, each accounting for 50% of the mass of the redox system initiator as a redox system initiator.
[0046] According to embodiments of this disclosure, the rigid spin-blocking polymer fracturing fluid thickener provided in these embodiments comprises the following raw material components by mass percentage: 30.2-55.8% deionized water, 2-5% co-solvent, 20-25% acrylamide, 8-12% potassium acrylate, 8-12% potassium 2-acrylamido-2-methylpropanesulfonate, 2-5% spin-blocking cyclic monomer, 1-3% rigid long-chain monomer, 2-4% perfluorinated surfactant, 1-3% chain transfer agent, 0.1-0.3% azo initiator, and 0.1-0.5% redox system initiator.
[0047] According to embodiments of this disclosure, the cosolvent includes any one or a combination of two of glyceryl carbonate, ethylene carbonate, and dimethyl carbonate;
[0048] According to embodiments of this disclosure, the rotor-blocked cyclic monomer comprises vinylene carbonate and ethylene ethylene carbonate, each accounting for 50% of the structural monomer mass;
[0049] According to embodiments of this disclosure, the perfluorinated surfactant is sodium perfluorononenoxybenzenesulfonate and perfluorooctyl polyoxyethylene ether, each accounting for 50% of the mass of the perfluorinated surfactant;
[0050] According to embodiments of this disclosure, the chain transfer agent is either potassium formate or potassium acetate;
[0051] According to embodiments of this disclosure, the azo initiator includes azobisisobutyrazoline hydrochloride and azobisisobutyramidine hydrochloride, each accounting for 50% of the mass of the azo initiator;
[0052] According to embodiments of this disclosure, the redox system initiator includes tert-butyl hydroperoxide and sodium metabisulfite, each accounting for 50% of the mass of the redox system initiator.
[0053] According to embodiments of this disclosure, the rigid long carbon chain monomer is either dodecyloxymethylacrylamide or hexadecyloxymethylacrylamide.
[0054] Specifically, such as Figure 1 As shown, Figure 1 This is a flowchart of a method for preparing rigid long-chain monomers according to embodiments of the present disclosure, the method comprising:
[0055] Step A: Keep the temperature inside the reactor at 0~5℃, and add dichloromethane 62~74%, dodecyl chloride or hexadecyl chloride 15~20%, pyridine 5~8%, and N-hydroxymethylacrylamide 6~10% by mass percentage, and stir until dissolved;
[0056] Step B: Seal the reactor and stir the reaction at 0~5℃ for 4~6 hours;
[0057] Step C: After the reaction is complete, remove the product and vacuum dry it in a vacuum drying oven at 25~35℃ for 6~8 hours;
[0058] Step D: The obtained yellow solid was purified by pulping with ethyl acetate and then filtered.
[0059] Step E: Take the filter residue and dry it in a vacuum drying oven at 40~50℃ for 2~4 hours. The white solid obtained is dodecyloxymethylacrylamide or hexadecyloxymethylacrylamide.
[0060] Furthermore, based on the rigid swirl-blocking polymer fracturing fluid thickener provided in the embodiments of this disclosure, the embodiments of this disclosure also provide a method for preparing the rigid swirl-blocking polymer fracturing fluid thickener, such as... Figure 2 As shown, Figure 2 This is a flowchart of a method for preparing a rigid spin-blocked polymer fracturing fluid thickener according to embodiments of the present disclosure, the method comprising:
[0061] Step S1: Dissolve the cosolvent, acrylamide, potassium acrylate, potassium 2-acrylamido-2-methylpropanesulfonate, blocked cyclic monomer, rigid long carbon chain monomer, perfluorinated surfactant and chain transfer agent in deionized water according to the mass percentages stated above.
[0062] In this step, maintain the temperature inside the reactor at 2~10℃. Add the prescribed amounts of deionized water, cosolvent, acrylamide, potassium acrylate, potassium 2-acrylamido-2-methylpropanesulfonate, cycloblocked cyclic monomer, and rigid long carbon chain monomer to the reactor in sequence, and stir until homogeneous, maintaining the stirring state. Then add the prescribed amounts of perfluorinated surfactant and chain transfer agent in sequence, and stir thoroughly to ensure that all raw material components are completely dissolved in the deionized water.
[0063] Step S2: Add initiator to initiate multi-stage initiation;
[0064] In this step, while stirring, add the prescribed amounts of azo initiator and redox initiator to initiate the polymerization reaction; then seal the reactor and allow it to heat naturally to 60~80℃, and maintain the temperature for 4~8 hours.
[0065] Step S3: Post-process the polymer block after polymerization to obtain the rigid spin-blocked polymer fracturing fluid thickener;
[0066] In this step, after the polymerization reaction is completed, the glue block is granulated, dried, crushed and packaged to obtain the rigid spin-blocked polymer fracturing fluid thickener.
[0067] Furthermore, the performance of the rigid spin-blocking polymer fracturing fluid thickener was tested, and the test results are as follows:
[0068] A 0.4% by mass thickener, stirred at 600 rpm for 1 min in deionized water, achieves a viscosity ≥ 80 mPa·s.
[0069] A 0.4% (w / w) thickener, when stirred at 600 rpm for 1 min in a standard brine solution, produces a viscosity ≥40 mPa·s (the standard brine has a total mineralization of 85000 mg / L and is formulated as follows: by mass percentage, it contains 2.0% KCl, 5.5% NaCl, 0.45% MgCl2, and 0.55% CaCl2, with the remainder being deionized water).
[0070] A 0.4% (w / w) thickener was stirred at 600 rpm for 2 min in an ultra-high mineralization brine solution until the viscosity reached ≥30 mPa·s (the total mineralization of the ultra-high mineralization brine was 300,000 mg / L, and the formula was: by mass percentage, it contained 2% KCl, 13% NaCl, 2% MgCl2 and 13% CaCl2, with the remainder being deionized water).
[0071] A 0.1% by mass thickener exhibits a drag reduction rate ≥70% in deionized aqueous solutions.
[0072] 0.6% (w / w) deionized water solution of thickener at 150°C for 100 seconds -1 Viscosity ≥ 20 mPa·s after 90 min of shearing.
[0073] Several specific embodiments are given below to illustrate the technical solutions of this disclosure in more detail. In the following embodiments, the reagents and instruments used are all commercially available.
[0074] Example 1
[0075] In this Example 1, dodecyloxymethylacrylamide is used as a rigid long-chain monomer. The preparation method of this rigid long-chain monomer includes the following steps:
[0076] Step A: Keep the temperature inside the reactor at 0°C, and add 219g of dichloromethane, 45g of dodecyl chloride, 18g of pyridine and 18g of N-hydroxymethylacrylamide in sequence, and stir until dissolved;
[0077] Step B: Seal the reactor and stir at 0°C for 6 hours;
[0078] Step C: After the reaction is complete, remove the product and dry it in a vacuum drying oven at 25°C for 8 hours.
[0079] Step D: The obtained yellow solid was purified by pulping with ethyl acetate and then filtered.
[0080] Step E: Take the filter residue and dry it in a vacuum drying oven at 50°C for 2 hours. The resulting white solid is dodecyloxymethylacrylamide.
[0081] In this Example 1, the preparation method of the rigid spin-blocked polymer fracturing fluid thickener specifically includes:
[0082] Step S1: Dissolve each raw material component in deionized water:
[0083] Maintain the temperature inside the reactor at 2°C. Add 123.9g of deionized water, 9g of glyceryl carbonate, 66g of acrylamide, 36g of potassium acrylate, 24g of potassium 2-acrylamido-2-methylpropanesulfonate, 6g of vinylene carbonate, 6g of ethylene carbonate, and 9g of dodecyloxymethylacrylamide to the reactor in sequence. Stir until homogeneous and maintain stirring. Then add 6g of sodium perfluorononenoxybenzenesulfonate, 6g of perfluorooctyl polyoxyethylene ether, and 6g of potassium formate in sequence, stirring thoroughly to ensure complete dissolution of all raw material components in the deionized water.
[0084] Step S2: Add initiator for multi-stage initiation:
[0085] While stirring, add 0.3g of azobisisobutyrazoline hydrochloride, 0.3g of azobisisobutyramidine hydrochloride, 0.75g of tert-butyl hydroperoxide and 0.75g of sodium metabisulfite to initiate the polymerization reaction; then seal the reactor and allow it to heat naturally to 75°C, and maintain the temperature for 6 hours.
[0086] Step S3: Post-processing of the polymerized gel block:
[0087] After the polymerization reaction is completed, the rubber block is granulated, dried, crushed and packaged to obtain the rigid spin-blocked polymer fracturing fluid thickener.
[0088] Furthermore, in this Example 1, the performance of the prepared rigid spin-blocked polymer fracturing fluid thickener was tested, and the test results are as follows:
[0089] A 0.4% by mass thickener, when stirred at 600 rpm for 1 min in deionized water, reached a viscosity of 84 mPa·s.
[0090] A 0.4% (w / w) thickener, when stirred at 600 rpm for 1 min in a standard brine solution, yielded a viscosity of 45 mPa·s (the standard brine solution had a total mineralization of 85,000 mg / L and was formulated to contain 2.0% KCl, 5.5% NaCl, 0.45% MgCl2, and 0.55% CaCl2 by mass percentage, with the remainder being deionized water).
[0091] A 0.4% (w / w) thickener was stirred at 600 rpm for 2 min in an ultra-high mineralization brine solution, resulting in a viscosity of 36 mPa·s (the total mineralization of the ultra-high mineralization brine is 300,000 mg / L, and the formula is: by mass percentage, it contains 2% KCl, 13% NaCl, 2% MgCl2 and 13% CaCl2, with the remainder being deionized water).
[0092] A 0.1% by mass thickener in a deionized aqueous solution reduces drag by 73%.
[0093] A 0.6% by mass thickener was applied to a deionized aqueous solution at 150°C for 100 seconds. -1 The viscosity was 28 mPa·s after 90 min of shearing.
[0094] Example 2
[0095] In this Example 2, hexadecyloxymethylacrylamide is used as a rigid long-chain monomer. The preparation method of this rigid long-chain monomer includes the following steps:
[0096] Step A: Keep the temperature inside the reactor at 3°C, and add 330g of dichloromethane, 90g of hexadecyl chloride, 40g of pyridine and 40g of N-hydroxymethylacrylamide in sequence, and stir until dissolved;
[0097] Step B: Seal the reactor and stir at 3°C for 5 hours;
[0098] Step C: After the reaction is complete, remove the product and dry it in a vacuum drying oven at 35°C for 6 hours.
[0099] Step D: The obtained yellow solid was purified by pulping with ethyl acetate and then filtered.
[0100] Step E: Take the filter residue and dry it in a vacuum drying oven at 40°C for 4 hours. The resulting white solid is hexadecyloxymethylacrylamide.
[0101] In this Example 2, the preparation method of the rigid spin-blocked polymer fracturing fluid thickener specifically includes:
[0102] Step S1: Dissolve each raw material component in deionized water:
[0103] Maintain the temperature inside the reactor at 8°C. Add 206.5g of deionized water, 25g of dimethyl carbonate, 100g of acrylamide, 50g of potassium acrylate, 60g of potassium 2-acrylamido-2-methylpropanesulfonate, 12.5g of vinylene carbonate, 12.5g of ethylene ethylene carbonate, and 5g of hexadecyloxymethylacrylamide to the reactor in sequence. Stir until homogeneous and maintain stirring. Then add 5g of sodium perfluorononenoxybenzenesulfonate, 5g of perfluorooctyl polyoxyethylene ether, and 15g of potassium acetate in sequence. Stir thoroughly to ensure all raw material components are completely dissolved in the deionized water.
[0104] Step S2: Add initiator for multi-stage initiation:
[0105] While stirring, add 0.75g of azobisisobutyrazoline hydrochloride, 0.75g of azobisisobutyramidine hydrochloride, 1g of tert-butyl hydroperoxide and 1g of sodium metabisulfite to initiate the polymerization reaction; then seal the reactor and allow it to heat naturally to 72°C, and maintain the temperature for 4 hours.
[0106] Step S3: Post-processing of the polymerized gel block:
[0107] After the polymerization reaction is completed, the glue block is granulated, dried, crushed and packaged to obtain the rigid spin-blocked polymer fracturing fluid thickener 2.
[0108] Furthermore, in Example 2, the performance of the prepared rigid spin-blocked polymer fracturing fluid thickener was tested, and the test results are as follows:
[0109] A 0.4% by mass thickener, when stirred in deionized water at 600 rpm for 1 min, reached a viscosity of 87 mPa·s.
[0110] A 0.4% (w / w) thickener, when stirred at 600 rpm for 1 min in a standard brine solution, yielded a viscosity of 48 mPa·s (the standard brine solution had a total mineralization of 85,000 mg / L and was formulated to contain, by mass percentage, 2.0% KCl, 5.5% NaCl, 0.45% MgCl2, and 0.55% CaCl2, with the remainder being deionized water).
[0111] A 0.4% (w / w) thickener, when stirred at 600 rpm for 2 min in an ultra-high mineralization brine solution, reached a viscosity of 39 mPa·s (the total mineralization of the ultra-high mineralization brine is 300,000 mg / L, and the formula is: by mass percentage, containing 2% KCl, 13% NaCl, 2% MgCl2 and 13% CaCl2, with the remainder being deionized water).
[0112] A 0.1% by mass thickener in a deionized aqueous solution reduces drag by 75%.
[0113] A 0.6% by mass thickener was applied to a deionized aqueous solution at 150°C for 100 seconds. -1 Viscosity after 90 min shearing: 30 mPa·s.
[0114] Example 3
[0115] In this Example 3, dodecyloxymethylacrylamide is used as a rigid long-chain monomer. The preparation method of this rigid long-chain monomer includes the following steps:
[0116] Step A: Keep the temperature inside the reactor at 5°C, and add 260g of dichloromethane, 80g of dodecyl chloride, 20g of pyridine and 40g of N-hydroxymethylacrylamide in sequence, and stir until dissolved;
[0117] Step B: Seal the reactor and stir at 5°C for 4 hours;
[0118] Step C: After the reaction is complete, remove the product and dry it in a vacuum drying oven at 30°C for 7 hours.
[0119] Step D: The obtained yellow solid was purified by pulping with ethyl acetate and then filtered.
[0120] Step E: Take the filter residue and dry it in a vacuum drying oven at 45°C for 3 hours. The resulting white solid is dodecyloxymethylacrylamide.
[0121] In this Example 3, the preparation method of the rigid spin-blocked polymer fracturing fluid thickener specifically includes:
[0122] Step S1: Dissolve each raw material component in deionized water:
[0123] Maintain the temperature inside the reactor at 5°C. Add 186.8g of deionized water, 8g of ethylene carbonate, 100g of acrylamide, 32g of potassium acrylate, 40g of potassium 2-acrylamido-2-methylpropanesulfonate, 4g of vinylene carbonate, 4g of ethylene ethylene carbonate, and 8g of dodecyloxymethylacrylamide to the reactor in sequence. Stir until homogeneous and maintain stirring. Then add 6g of sodium perfluorononenoxybenzenesulfonate, 6g of perfluorooctyl polyoxyethylene ether, and 4g of potassium acetate in sequence. Stir thoroughly to ensure all raw material components are completely dissolved in the deionized water.
[0124] Step S2: Add initiator for multi-stage initiation:
[0125] While stirring, add 0.2g of azobisisobutyrazoline hydrochloride, 0.2g of azobisisobutyramidine hydrochloride, 0.4g of tert-butyl hydroperoxide and 0.4g of sodium metabisulfite to initiate the polymerization reaction; then seal the reactor and allow it to heat naturally to 65℃, and maintain the temperature for 8 hours.
[0126] Step S3: Post-processing of the polymerized gel block:
[0127] After the polymerization reaction is completed, the glue block is granulated, dried, crushed and packaged to obtain the rigid spin-blocked polymer fracturing fluid thickener 3.
[0128] Furthermore, in Example 3, the performance of the prepared rigid spin-blocked polymer fracturing fluid thickener was tested, and the test results are as follows:
[0129] A 0.4% by mass thickener, when stirred in deionized water at 600 rpm for 1 min, reached a viscosity of 90 mPa·s.
[0130] A 0.4% (w / w) thickener, when stirred at 600 rpm for 1 min in a standard brine solution, yielded a viscosity of 42 mPa·s (the standard brine solution had a total mineralization of 85,000 mg / L and was formulated to contain, by mass percentage, 2.0% KCl, 5.5% NaCl, 0.45% MgCl2, and 0.55% CaCl2, with the remainder being deionized water).
[0131] A 0.4% (w / w) thickener, when stirred at 600 rpm for 2 min in an ultra-high mineralization brine solution, reached a viscosity of 33 mPa·s (the total mineralization of the ultra-high mineralization brine is 300,000 mg / L, and the formula is: by mass percentage, containing 2% KCl, 13% NaCl, 2% MgCl2 and 13% CaCl2, with the remainder being deionized water).
[0132] A 0.1% by mass thickener in a deionized aqueous solution reduces drag by 74%.
[0133] A 0.6% by mass thickener was applied to a deionized aqueous solution at 150°C for 100 seconds. -1 Viscosity after 90 min shearing: 25 mPa·s.
[0134] It should be noted that, based on common knowledge in the art, the various process conditions in the above embodiments can be arbitrarily combined to obtain the preferred embodiments of this disclosure. Furthermore, the reagents and raw materials used in this disclosure are all commercially available.
[0135] Furthermore, this disclosure also provides the application of the rigid swirl-blocking polymer fracturing fluid thickener in the field of oil and gas field drilling fracturing.
[0136] Furthermore, this disclosure also provides the application of the rigid spin-blocking polymer thickener in the field of water-based fracturing.
[0137] The rigid-rotor structure polymer fracturing fluid thickener provided in the above embodiments is applied in the field of oil and gas field drilling fracturing, especially in the field of water-based fracturing. It has beneficial effects such as ultra-fast dissolution, super salt resistance, temperature and shear resistance, drag reduction and sand carrying integration, multi-functional anti-swelling and drainage assistance, and low damage and no pollution. Practice has shown that it has the following significant advantages:
[0138] 1. Ultra-fast dissolution: By introducing potassium acrylate and potassium 2-acrylamido-2-methylpropanesulfonate into the thickener, the carboxyl and sulfonic acid groups on the molecular chain can significantly improve the hydrophilicity of the thickener. Furthermore, by adding a chain transfer agent to regulate the molecular weight and structural distribution of the polymer and inhibit internal cross-linking, it can dissolve ultra-fast in water and salt water, with a dissolution time of only 1~2 minutes.
[0139] 2. Superior Salt Tolerance: The introduction of potassium 2-acrylamido-2-methylpropanesulfonate into the thickener enhances salt tolerance; the introduced cyclic monomers give the polymer main chain and branches a five-membered ring structure, significantly increasing the resistance to inward rotation within and between molecular chains, thus effectively preventing the molecular chains from rotating inward and contracting; simultaneously, the introduction of rigid long-chain monomers increases the overall rigidity of the molecular chains and enhances the interaction between molecular chains through van der Waals forces. These three salt tolerance mechanisms work synergistically, enabling the thickener to tolerate salt concentrations up to 300,000 mg / L while reducing its sensitivity to high-valence metal ions such as calcium and magnesium ions.
[0140] 3. Temperature and Shear Resistance: The thickener incorporates hindered cyclic monomers to prevent the molecular chains from rotating inward and contracting; simultaneously, rigid long-chain monomers are introduced to improve the overall rigidity of the molecular chains. Therefore, the structure is more stable, resulting in a temperature resistance of up to 150℃ and greater shear resistance.
[0141] 4. Integrated construction for drag reduction and sand carrying: The thickener has a linear main chain and high molecular weight. By adjusting the concentration in real time, it can meet the integrated construction requirements of drag reduction of low-viscosity slickwater and sand addition of high-concentration sand carrying liquid.
[0142] 5. Multifunctional anti-swelling and drainage aid: The two perfluorinated surfactants introduced into the thickener work synergistically to effectively reduce the interfacial tension of the liquid surface and improve drainage aid performance; the potassium ions after the thickener is dissolved form ion-lattice bonds by embedding into the clay lattice voids and neutralize the negative charge on the clay surface, effectively preventing clay particle agglomeration, inhibiting clay swelling and dispersion, and having excellent anti-swelling effect, thus improving anti-swelling performance.
[0143] 6. Low damage and no pollution: The formulated fracturing fluid leaves no residue and has anti-swelling and drainage-aiding effects, which can significantly reduce the damage of the fluid to the formation, thus facilitating a substantial increase in oil and gas production; at the same time, there are no heavy metal residues, and the flowback fluid can be reused, which will not cause environmental pollution and is environmentally friendly.
[0144] This disclosure has now been described in detail with reference to the accompanying drawings. Based on the above description, those skilled in the art should have a clear understanding of this disclosure.
[0145] It should be noted that implementations not shown or described in the accompanying drawings or the main text of the specification are all forms known to those skilled in the art and are not described in detail. Furthermore, the definitions of the elements above are not limited to the various specific structures, shapes, or methods mentioned in the embodiments, and those skilled in the art can easily modify or substitute them.
[0146] Although this disclosure has been shown and described with reference to specific exemplary embodiments thereof, various changes in form and detail may be made to this disclosure without departing from the spirit and scope of the disclosure as defined by the appended claims and their equivalents. Therefore, the scope of this disclosure should not be limited to the above-described embodiments, but should be determined not only by the appended claims but also by their equivalents.
Claims
1. A rigid, spin-resistant, structured polymer fracturing fluid viscosifier, characterized in that, The rigid helical structure polymer fracturing fluid thickening agent adopts the following components by mass percentage: deionized water 30.2~55.8%, cosolvent 2~5%, acrylamide 20~25%, potassium acrylate 8~12%, 2-acrylamido-2-methylpropane sulfonic acid potassium 8~12%, helical structure cyclic monomer 2~5%, rigid long carbon chain monomer 1~3%, perfluorinated surfactant 2~4%, chain transfer agent 1~3%, azo initiator 0.1~0.3% and redox system initiator 0.1~0.5%.
2. The rigid helical structure polymer fracturing fluid thickening agent according to claim 1, characterized in that, The cosolvent includes any one or a combination of two of glycerol carbonate, ethylene carbonate and dimethyl carbonate; The helical structure cyclic monomer includes vinylene carbonate and vinyl ethylene carbonate, each accounting for 50% of the mass of the structure monomer; The perfluorinated surfactant is sodium perfluorooctyl polyoxyethylene ether and sodium perfluorooctyl polyoxyethylene ether, each accounting for 50% of the mass of the perfluorinated surfactant; The chain transfer agent is any one of potassium formate and potassium acetate; The azo initiator includes azobisimidozoline hydrochloride and azobisimidozoline hydrochloride, each accounting for 50% of the mass of the azo initiator; The redox system initiator includes tert-butyl hydroperoxide and sodium metabisulfite, each accounting for 50% of the mass of the redox system initiator.
3. The rigid, spin-decreasing, structured polymer fracturing fluid viscosifier of claim 1, wherein, The rigid long carbon chain monomer is any one of dodecyl acryloyl methacrylamide and hexadecyl acryloyl methacrylamide.
4. The rigid, spin-deadly structured polymer fracturing fluid viscosifier of claim 3, wherein, The rigid long carbon chain monomer is prepared by the following method: Step A: keep the temperature in the reaction kettle at 0~5℃, add dichloromethane 62~74%, dodecanoyl chloride or hexadecanoyl chloride 15~20%, pyridine 5~8% and N-hydroxymethyl acrylamide 6~10% by mass percentage, stir to dissolve; Step B: seal the reaction kettle, stir at 0~5℃ for 4~6h; Step C: after the reaction is completed, take it out and dry in a vacuum drying oven at 25~35℃ for 6~8h; Step D: the obtained yellow solid is filtered after being purified with ethyl acetate; Step E: take the filter residue to a vacuum drying oven at 40~50℃ for 2~4h, and the obtained white solid is dodecyl acryloyl methacrylamide or hexadecyl acryloyl methacrylamide.
5. A process for the preparation of the rigid, spin-resistant, structured polymer fracturing fluid viscosifier of any one of claims 1 to 4, characterized in that, The method comprises: Step S1: dissolve the cosolvent, acrylamide, potassium acrylate, 2-acrylamido-2-methylpropane sulfonic acid potassium, helical structure cyclic monomer, rigid long carbon chain monomer, perfluorinated surfactant and chain transfer agent in deionized water according to the mass percentage; Step S2: add the initiator for multi-stage initiation; Step S3: post-treat the gel block after polymerization to obtain the rigid helical structure polymer fracturing fluid thickening agent.
6. The production method according to claim 5, wherein The dissolving of the cosolvent, acrylamide, potassium acrylate, 2-acrylamido-2-methylpropane sulfonic acid potassium, helical structure cyclic monomer, rigid long carbon chain monomer, perfluorinated surfactant and chain transfer agent in deionized water according to the mass percentage in step S1 comprises: The temperature in the reaction kettle is kept at 2-10 DEG C, and the formula amount of deionized water, cosolvent, acrylamide, potassium acrylate, 2-acrylamido-2-methylpropane sulfonic acid potassium, blocking ring monomer and rigid long carbon chain monomer are sequentially added in the reaction kettle, and stirred uniformly, and kept in the stirring state; Then the formula amount of perfluoro surfactant and chain transfer agent is sequentially added, and fully stirred, so that each raw material component is completely dissolved in deionized water.
7. The preparation method according to claim 5, characterized in that, The initiator in step S2 is added for multi-stage initiation, including: The formula amount of azo initiator and redox system initiator is added under the condition of keeping stirring, and the polymerization reaction is initiated; Then the reaction kettle is sealed, and naturally heated to 60-80 DEG C, and the adiabatic heat preservation reaction is carried out for 4-8 h.
8. The preparation method according to claim 5, characterized in that, The gel block after polymerization in step S3 is post-treated, including: after the polymerization reaction, the gel block is granulated, dried, crushed and packaged, and the rigid blocking structure polymer fracturing fluid thickener is obtained.
9. The application of a rigid blocking structure polymer thickener in the field of oil and gas field drilling and fracturing, wherein the rigid blocking structure polymer thickener is the rigid blocking structure polymer thickener according to any one of claims 1-4, or is prepared by the method according to any one of claims 5-8.
10. The application of a rigid blocking structure polymer thickener in the field of water-based fracturing, wherein the rigid blocking structure polymer thickener is the rigid blocking structure polymer thickener according to any one of claims 1-4, or is prepared by the method according to any one of claims 5-8.