Anti-scaling and corrosion-inhibiting polymer fracturing fluid and preparation method thereof

Abstract

This invention discloses a scale-inhibiting and corrosion-inhibiting polymer fracturing fluid and its preparation method, belonging to oilfield chemicals. It comprises a multifunctional copolymer thickener, a modified strontium-barium dual-ion imprinted polymer, a crosslinking agent, a breaker, and deionized water. The multifunctional copolymer thickener is obtained by polymerizing acrylamide, a polymerizable corrosion inhibitor, and a polymerizable scale inhibitor. The polymerizable scale inhibitor is a polymerizable compound formed by the amidation reaction of polyaspartic acid and N-(3-aminopropyl)methacrylamide. The modified strontium-barium dual-ion imprinted polymer comprises a strontium-barium dual-ion imprinted polymer core and a polyethylene glycol derivative loaded with an alkyl glycoside nonionic surfactant. The polyethylene glycol derivative loaded with the alkyl glycoside nonionic surfactant is attached to the outer surface of the strontium-barium dual-ion imprinted polymer core. This invention improves the selective adsorption of strontium-barium through the strontium-barium dual-ion imprinted polymer, preventing the formation of insoluble scale by strontium-barium and anions.

Description

Technical Field

[0001] This invention belongs to the field of oilfield chemicals and relates to a scale-inhibiting and corrosion-inhibiting polymer fracturing fluid and its preparation method. Background Technology

[0002] Fracturing is a crucial method for enhancing oil and gas production and injection. As the core working fluid in fracturing operations, the performance of fracturing fluid directly impacts the fracturing effect and the productivity of oil and gas wells. Polymer fracturing fluids, due to their excellent thickening and proppant-carrying properties and low residue damage, have become one of the most widely used fracturing fluid systems.

[0003] When fracturing fluid mixes with formation water, changes in temperature and pressure, as well as ion incompatibility, easily lead to the deposition of inorganic scale such as calcium carbonate, calcium sulfate, strontium sulfate, and barium sulfate. Strontium and barium scale (strontium sulfate and barium sulfate), in particular, are extremely difficult to remove once formed due to their very low solubility, clogging formation pores and fractures and severely impacting fracturing production. Existing general-purpose corrosion and scale inhibitors lack selectivity for strontium and barium, readily competing with calcium ions for their absorption, resulting in low scale inhibition efficiency for barium and strontium scale. Summary of the Invention

[0004] The purpose of this invention is to provide a scale and corrosion inhibitor polymer fracturing fluid and its preparation method, which solves the problem that existing general-purpose scale and corrosion inhibitors are not selective for strontium and barium, and easily compete with calcium ions for consumption, resulting in low scale inhibition efficiency for barium and strontium scale.

[0005] The technical solution adopted in this invention is as follows: A scale and corrosion inhibitor polymer fracturing fluid includes a multifunctional copolymer thickener, a modified strontium-barium dual-ion imprinted polymer, a crosslinking agent, a breaker, and deionized water; The multifunctional copolymer thickener is obtained by polymerizing acrylamide, a polymerizable corrosion inhibitor, and a polymerizable scale inhibitor. The polymerizable scale inhibitor is a polymerizable compound formed by an amidation reaction of polyaspartic acid and N-(3-aminopropyl)methacrylamide. The modified strontium barium dual-ion imprinted polymer comprises a strontium barium dual-ion imprinted polymer core and a polyethylene glycol derivative loaded with an alkyl glycoside nonionic surfactant. The polyethylene glycol derivative loaded with an alkyl glycoside nonionic surfactant is attached to the outer surface of the strontium barium dual-ion imprinted polymer core. The polymerizable corrosion inhibitor is a polymerizable compound with corrosion inhibition function. The polymerizable corrosion inhibitor includes compound A and compound B. Compound A is a compound obtained by esterification reaction of dicarboxyl-terminated polyoxyethylene ether macromonomer and hydroxyl-polyethylene glycol-dithiopyridine disulfide. Compound B is a compound obtained by esterification reaction of imidazoline containing carboxylic acid group and hydroxyethyl methacrylate.

[0006] Furthermore, the mass ratio of compound A to compound B in the polymerizable corrosion inhibitor is 1:2; Compound A is a compound obtained by esterification reaction of dicarboxylate-terminated polyoxyethylene ether macromonomer and hydroxyl-polyethylene glycol-dithiopyridine disulfide in a mass ratio of 1:1. Compound B is a compound obtained by esterification of imidazoline containing a carboxylic acid group and hydroxyethyl methacrylate in a mass ratio of 3:1.

[0007] Further, the polymerizable scale inhibitor compound is prepared by the following method: polyaspartic acid is dissolved in N,N-dimethylformamide, stirred evenly, and then N-(3-aminopropyl)methacrylamide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and N-hydroxysuccinimide are added, wherein the molar ratio of polyaspartic acid to N-(3-aminopropyl)methacrylamide is 1:1.2; the reaction is carried out under nitrogen protection at room temperature with stirring for 24 hours. After the reaction is completed, the reaction solution is slowly poured into excess anhydrous ethanol to precipitate the precipitate, filtered, and the precipitate is repeatedly washed with anhydrous ethanol and dried under vacuum to constant weight to obtain the polymerizable scale inhibitor compound.

[0008] Furthermore, the polyethylene glycol derivative loaded with alkyl glycoside nonionic surfactant is prepared by the following method: polyethylene glycol diglycidyl ether is dispersed in deionized water, alkyl glycoside nonionic surfactant and sodium carbonate are added, wherein the amount of alkyl glycoside nonionic surfactant added is 15% of the weight of polyethylene glycol diglycidyl ether, the reaction is carried out at a constant temperature of 45°C with stirring for 2.5 hours, and after concentration and drying, the polyethylene glycol derivative loaded with alkyl glycoside nonionic surfactant is obtained.

[0009] Furthermore, in the modified strontium-barium dual-ion imprinted polymer, strontium ions and barium ions are used as dual templates, vinylphosphonic acid and acrylic acid are used as bifunctional monomers, and dimethacrylate-terminated polylactic acid-glycolic acid copolymer is used as a crosslinking agent. After polymerization and elution of template ions, the core of the strontium-barium dual-ion imprinted polymer is obtained.

[0010] Further, the modified strontium-barium dual-ion imprinted polymer was prepared by the following method: strontium chloride and barium chloride, vinylphosphonic acid and acrylic acid were dissolved in a dimethyl sulfoxide / acetonitrile mixed solvent, with a volume ratio of dimethyl sulfoxide to acetonitrile of 1:4. The mixture was stirred for 1-2 hours, and then dimethacrylate-terminated polylactic acid-glycolic acid copolymer and azobisisobutyronitrile were added. The molar ratio of strontium chloride, barium chloride, vinylphosphonic acid, acrylic acid and dimethacrylate-terminated polylactic acid-glycolic acid copolymer was 0.5:0.5:(2-3):(1-2):15, and the amount of azobisisobutyronitrile added was 0.9% of the total mass of vinylphosphonic acid, acrylic acid and dimethacrylate-terminated polylactic acid-glycolic acid copolymer. After deoxygenation by purging with nitrogen, the mixture was reacted at 65-70°C for 20-24 hours, filtered, and a polymer precipitate containing template ions was obtained. 0.1 The polymer precipitate was repeatedly washed with mol / L hydrochloric acid solution until no strontium and barium ions were detected in the washing solution. Then it was washed with water until neutral to obtain the strontium-barium dual-ion imprinted polymer core. The core of the strontium-barium biionic polymer was dispersed in deionized water, and 20% by weight of a polyethylene glycol derivative loaded with an alkyl glycoside nonionic surfactant was added to the core. Triethylamine was added dropwise to adjust the pH to 8-9, and the reaction was carried out at 55-60℃ for 8-10 hours. After the reaction was completed, the polymer was purified to obtain the modified strontium-barium biionic polymer.

[0011] Furthermore, the mass ratio of acrylamide, polymerizable corrosion inhibitor, and polymerizable scale inhibitor is 45:2:3.

[0012] Furthermore, the scale-inhibiting and corrosion-inhibiting polymer fracturing fluid, by mass fraction, comprises 0.5% multifunctional copolymer thickener, 0.26%~0.28% modified strontium barium dual-ion imprinted polymer, 0.15% crosslinking agent, 0.06% breaker, and the balance being deionized water; wherein the crosslinking agent is an organozirconium crosslinking agent; and the breaker is a capsule breaker.

[0013] A method for preparing a scale-inhibiting and corrosion-inhibiting polymer fracturing fluid includes the following steps: S1. Preparation of base solution: Add the multifunctional copolymer thickener to deionized water, stir and dissolve at 1500~2000 rpm, then add the modified strontium barium dual ion imprinted polymer, and ultrasonically disperse for 10~15 minutes to obtain the base solution; S2, cross-linking to form a gel: Add an organozirconium cross-linking agent to the base liquid under low-speed stirring, stir evenly, and let stand at 25°C for 30~40 minutes to form a gel solution; S3. Add capsule breaker to the glue solution and mix well to obtain scale and corrosion inhibitor polymer fracturing fluid.

[0014] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. A scale and corrosion inhibitor polymer fracturing fluid, while providing corrosion inhibition and basic calcium ion scale inhibition, introduces ion imprinting technology, which improves the selective adsorption of strontium barium through strontium barium dual ion imprinted polymer, thereby blocking the formation of insoluble scale by strontium barium and anions. 2. This invention modifies the strontium-barium dual-ion imprinted polymer, enabling it to be uniformly dispersed in the fracturing fluid system, avoiding spontaneous sedimentation and agglomeration, and facilitating its return with the rupture fluid, thus reducing residual amounts. This invention also introduces polylactic acid segments into the strontium-barium dual-ion imprinted polymer, making it biodegradable and reducing the risk of permanent formation blockage caused by residual strontium-barium dual-ion imprinted polymer. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort, wherein:

[0016] Figure 1 Here is a photograph of the fracturing fluid prepared in Example 1 of this invention;

[0017] Figure 2 This is a TEM image of the modified barium strontium dual-ion imprinted polymer. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0020] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0021] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0022] The following embodiments of the present invention provide a scale and corrosion inhibitor polymer fracturing fluid, comprising a multifunctional copolymer thickener, a modified strontium barium dual-ion imprinted polymer, a crosslinking agent, a breaker, and deionized water;

[0023] The multifunctional copolymer thickener is obtained by polymerizing acrylamide, a polymerizable corrosion inhibitor, and a polymerizable scale inhibitor.

[0024] The polymerizable scale inhibitor is a polymerizable compound formed by an amidation reaction of polyaspartic acid and N-(3-aminopropyl)methacrylamide.

[0025] The modified strontium-barium dual-ion imprinted polymer comprises a strontium-barium dual-ion imprinted polymer core and a polyethylene glycol derivative loaded with an alkyl glycoside nonionic surfactant. The polyethylene glycol derivative loaded with the alkyl glycoside nonionic surfactant is attached to the outer surface of the strontium-barium dual-ion imprinted polymer core.

[0026] In the following embodiments, the polymerizable corrosion inhibitor compound includes compound A and compound B; the mass ratio of compound A to compound B is 1:2.

[0027] Compound A is a compound obtained by esterification of a dicarboxylated end-capped polyoxyethylene ether macromonomer and a hydroxyl-polyethylene glycol-dithiopyridine disulfide at a mass ratio of 1:1. It was prepared by the following method: using HPEG and trimalonic acid in a molar ratio of 1:1.05 as raw materials and DMAP as a catalyst, a dicarboxylated end-capped polyoxyethylene ether macromonomer was prepared by esterification. The optimized conditions for the esterification reaction were a temperature of 115℃, a time of 5 h, and a DMAP catalyst dosage of 1.50 wt% of the raw materials. 20.0 g of the dicarboxylated end-capped polyoxyethylene ether macromonomer and 20.0 g of hydroxyl-polyethylene glycol-dithiopyridine disulfide (HO-PEG2000-SPDP, commercially available) were dissolved in 400 mL of anhydrous dichloromethane, stirred until homogeneous, and then 0.24 g of 4-dimethylaminopyridine (DMAP) and 2.30 g of... 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC·HCl) was reacted with stirring at room temperature for 24 hours under nitrogen protection. After the reaction was completed, the mixture was washed successively with 0.1 mol / L dilute hydrochloric acid, saturated sodium bicarbonate solution, and saturated sodium chloride solution. The organic phase was dried over anhydrous sodium sulfate, filtered, and distilled under reduced pressure. The crude product was precipitated with anhydrous diethyl ether, filtered, and dried under vacuum to constant weight to give compound A.

[0028] Compound B is a compound obtained by esterification of imidazoline containing a carboxylic acid group and hydroxyethyl methacrylate at a mass ratio of 3:1; and is prepared by the following method: 39.0 g of imidazoline (YM4313) containing a carboxylic acid group and 13.0 g of hydroxyethyl methacrylate were dissolved in 300 mL of toluene, and 0.86 g of p-toluenesulfonic acid and 0.11 g of hydroquinone were added; the mixture was heated to 115 °C under nitrogen protection and refluxed for 7 hours to remove water; after the reaction was completed, the mixture was cooled to room temperature, washed successively with saturated sodium bicarbonate solution and deionized water, the organic phase was dried over anhydrous sodium sulfate and filtered, and distilled under reduced pressure to obtain compound B.

[0029] In the following examples, the polymerizable scale inhibitor compound was prepared by the following method: polyaspartic acid was dissolved in N,N-dimethylformamide, stirred until homogeneous, and then N-(3-aminopropyl)methacrylamide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and N-hydroxysuccinimide were added, wherein the molar ratio of polyaspartic acid to N-(3-aminopropyl)methacrylamide was 1:1.2; the reaction was carried out under nitrogen protection and stirred at room temperature for 24 hours. After the reaction was completed, the reaction solution was slowly poured into excess anhydrous ethanol to precipitate the precipitate, filtered, and the precipitate was repeatedly washed with anhydrous ethanol and dried under vacuum to constant weight to obtain the polymerizable scale inhibitor compound. The specific preparation method of the polymerizable scale inhibitor compound in the following examples is as follows: 0.1 mol of polyaspartic acid (weight-average relative molecular mass of 4000) was dissolved in 200 mL of anhydrous DMF, stirred evenly, and then 0.12 mol of N-(3-aminopropyl)methacrylamide, 0.12 mol of EDC·HCl and 0.12 mol of NHS were added sequentially; the reaction was carried out under nitrogen protection at room temperature for 24 hours with stirring. After the reaction was completed, the reaction solution was slowly poured into excess anhydrous ethanol to precipitate the precipitate, filtered, and the precipitate was repeatedly washed with anhydrous ethanol (200 mL each time, 3 times). The precipitate was then dried under vacuum to constant weight to obtain the polymerizable scale inhibitor compound.

[0030] In the following examples, the polyethylene glycol derivative loaded with alkyl glycoside nonionic surfactant was prepared by the following method: 100g of polyethylene glycol diglycidyl ether (polyethylene glycol diglycidyl ether model HS-215) was dispersed in 300mL of deionized water, 15g of alkyl glycoside nonionic surfactant and 0.3g of sodium carbonate were added, and the mixture was stirred at 45°C for 2.5 hours. After the reaction was completed, the mixture was evaporated, concentrated, and dried to obtain the polyethylene glycol derivative loaded with alkyl glycoside nonionic surfactant.

[0031] In the following examples, the modified strontium-barium dual-ion imprinted polymer uses strontium and barium ions as dual templates, vinylphosphonic acid and acrylic acid as bifunctional monomers, and dimethacrylate-terminated polylactic acid-glycolic acid copolymer as a crosslinking agent. After polymerization and elution of template ions, the core of the strontium-barium dual-ion imprinted polymer is obtained.

[0032] In the following examples, the modified strontium-barium dual-ion imprinted polymer was prepared by the following method: strontium chloride and barium chloride, vinylphosphonic acid and acrylic acid were dissolved in a dimethyl sulfoxide / acetonitrile mixed solvent, with a volume ratio of dimethyl sulfoxide to acetonitrile of 1:4. The mixture was stirred for 2 hours. Then, dimethacrylate-terminated polylactic acid-glycolic acid copolymer (MA-PLGA15K-MA) and azobisisobutyronitrile were added, wherein the molar ratio of strontium chloride, barium chloride, vinylphosphonic acid, acrylic acid and dimethacrylate-terminated polylactic acid-glycolic acid copolymer was 0.5:0.5:2.5:1.5:15, and the amount of azobisisobutyronitrile added was 0.9% of the total mass of vinylphosphonic acid, acrylic acid and dimethacrylate-terminated polylactic acid-glycolic acid copolymer. After deoxygenation by purging with nitrogen, the mixture was reacted at 70°C for 24 hours, filtered, and a polymer precipitate containing template ions was obtained. 0.1 The polymer precipitate was repeatedly washed with mol / L hydrochloric acid solution until no strontium and barium ions were detected in the washing solution. Then it was washed with water until neutral to obtain the strontium-barium dual-ion imprinted polymer core.

[0033] The core of a strontium-barium biionic polymer was dispersed in deionized water. 20% (by weight) of a polyethylene glycol derivative loaded with an alkyl glycoside nonionic surfactant was added to the core. Triethylamine was added dropwise to adjust the pH to 8.5. The reaction was carried out at 60°C for 9 hours. After the reaction, the mixture was purified to obtain the modified strontium-barium biionic polymer. Its TEM image is shown below. Figure 2 As shown.

[0034] In the following examples, the mass ratio of acrylamide, polymerizable corrosion inhibitor, and polymerizable scale inhibitor in the multifunctional copolymer thickener is 45:2:3. The multifunctional copolymer thickener is prepared by the following method: 45.0 g of acrylamide, 0.67 g of compound A, 1.33 g of compound B, and 3.0 g of polymerizable scale inhibitor are sequentially added to a three-necked flask containing 180 mL of deionized water. The mixture is stirred at 300 r / min at room temperature until completely dissolved to obtain a reaction solution. The pH of the reaction solution is adjusted to 6.5-7.0 using 1 mol / L NaOH solution. Deionized water is added to the above reaction solution until the total mass of the reaction system is 250 g. High-purity nitrogen is introduced, and the mixture is bubbled to remove oxygen for 30 minutes with stirring. Subsequently, 0.15 g of ammonium persulfate and 0.15 g of sodium bisulfite are dissolved in 5 mL of water. mL of deionized water was added dropwise to the reaction system under nitrogen protection; the reaction system was heated to 40°C and reacted at a constant temperature for 6 hours; after the reaction was completed, the mixture was dried at 60°C for 12 hours and then pulverized to obtain the multifunctional copolymer thickener.

[0035] Example 1

[0036] A preferred embodiment of the present invention provides a scale and corrosion inhibitor polymer fracturing fluid, comprising, by mass fraction, 0.5% multifunctional copolymer thickener, 0.27% modified strontium barium dual-ion imprinted polymer, 0.15% crosslinking agent, 0.06% breaker, and the balance being deionized water; wherein the crosslinking agent is an organozirconium crosslinking agent; the breaker is an ammonium persulfate capsule breaker; and it is prepared by the following method:

[0037] S1. Preparation of base solution: Add the multifunctional copolymer thickener to deionized water, stir and dissolve at 1800 rpm, then add the amphiphilic modified strontium barium dual-ion imprinted polymer, and ultrasonically disperse for 15 minutes to obtain the base solution;

[0038] S2, Crosslinking and Gel Formation: Add the organozirconium crosslinking agent to the base liquid while stirring at 200 r / min. After stirring evenly, let it stand at 25℃ for 40 minutes to form a gel solution; (e.g.) Figure 1 As shown, a homogeneous gelling system was obtained;

[0039] S3. Add capsule breaker to the glue solution and mix well to obtain scale and corrosion inhibitor polymer fracturing fluid.

[0040] Example 2

[0041] This embodiment, based on Example 1, provides a scale and corrosion inhibitor polymer fracturing fluid, comprising, by mass fraction, 0.5% multifunctional copolymer thickener, 0.26% modified strontium barium dual-ion imprinted polymer, 0.15% crosslinking agent, 0.06% breaker, and the balance being deionized water; wherein the crosslinking agent is an organozirconium crosslinking agent; and the breaker is an ammonium persulfate capsule breaker. All other components are identical.

[0042] Example 3

[0043] This embodiment, based on Example 1, provides a scale and corrosion inhibitor polymer fracturing fluid, comprising, by mass fraction, 0.5% multifunctional copolymer thickener, 0.28% modified strontium barium dual-ion imprinted polymer, 0.15% crosslinking agent, 0.06% breaker, and the balance being deionized water; wherein the crosslinking agent is an organozirconium crosslinking agent; and the breaker is an ammonium persulfate capsule breaker. All other components are identical.

[0044] Comparative Example 1

[0045] Based on Example 1, the difference from Example 1 is that this comparative example provides a scale and corrosion inhibitor polymer fracturing fluid, which does not include the modified strontium barium dual-ion imprinted polymer; all other aspects are the same.

[0046] Comparative Example 2

[0047] Based on Example 1, the difference between this comparative example and Example 1 is that the strontium-barium dual-ion imprinted polymer added to the scale-inhibiting and corrosion-inhibiting polymer fracturing fluid was not modified in any way; the strontium-barium dual-ion imprinted polymer core was directly added. All other aspects were the same. The fracturing fluid prepared in this comparative example showed stratification after standing at 60°C for 2 hours; this phenomenon did not occur in the other experimental groups.

[0048] Comparative Example 3

[0049] Based on Example 1, but unlike Example 1, this comparative example provides a scale and corrosion inhibitor polymer fracturing fluid. The polymerizable corrosion inhibitory compound in the multifunctional copolymer thickener does not include compound A, but is all compound B; the rest are the same.

[0050] Comparative Example 4

[0051] Based on Example 1, but unlike Example 1, this comparative example provides a scale and corrosion inhibitor polymer fracturing fluid. The polymerizable corrosion inhibitory compound in the multifunctional copolymer thickener does not include compound B, but is all compound A; the rest are the same.

[0052] Comparative Example 5

[0053] Based on Example 1, the difference from Example 1 is that this comparative example provides a scale and corrosion inhibitor polymer fracturing fluid, and the multifunctional copolymer thickener does not include polymerizable corrosion inhibitory compounds; all other aspects are the same.

[0054] Comparative Example 6

[0055] Based on Example 1, the difference from Example 1 is that this comparative example provides a scale-inhibiting and corrosion-inhibiting polymer fracturing fluid, and the multifunctional copolymer thickener does not include polymerizable scale-inhibiting compounds; all other aspects are the same.

[0056] Comparative Example 7

[0057] This comparative example utilizes existing technology to provide a scale-inhibiting and corrosion-inhibiting polymer fracturing fluid: by mass fraction, it is based on 0.5% polyacrylamide thickener, with 0.04% imidazolinamide corrosion inhibitor (provided by Gansu Provincial Chemical Research Institute) and 0.06% polyaspartic acid scale inhibitor (provided by Desay Chemical, model 40T) added respectively. The crosslinking agent and breaker are the same as in Example 1, and the balance is deionized water; the preparation method is the same as in Example 1.

[0058] Experimental Example 1

[0059] The performance of the fracturing fluids prepared in Examples 1-3 and Comparative Examples 1-7 was tested, and the results are shown in Table 1.

[0060] Fracturing fluid viscosity: Take 350 ml of fracturing fluid sample heated to 30°C and measure the viscosity over 170 seconds using a Fann-35 viscometer. -1Apparent viscosity at shear rate and temperature of 30℃, in mPa·s; average value of three parallel tests.

[0061] Breaking performance: Refer to standard SY / T 5107 to determine the viscosity of the breaking fluid after breaking. The unit of viscosity of the breaking fluid is mPa·s. Take the average value of three parallel tests. If the viscosity of the fracturing fluid after breaking is less than 5 mPa·s, it meets the general industry standard requirements.

[0062] Filtration coefficient: Refer to standard SY / T 5107, which is used to test the filtration coefficient of fracturing fluid, with units of m / min. 1 / 2 The average value of three parallel tests should be taken; the filtration loss coefficient should be ≤5×10. -4 ;

[0063] Temperature and shear resistance: Referring to standard SY / T 5107, the fracturing fluid was tested at 120℃ with a shear rate of 170 s⁻¹. -1 Apparent viscosity after 2 hours of shearing, in mPa·s; average value of three parallel tests.

[0064] Scale inhibition: Simulated mixed water sample: 200 mg / L Ca 2+ 100mg / LSr 2+ 100mg / LBa 2+ 300mg / LHCO3 - 200mg / LSO4 2- 5000 mg / L NaCl; Blank group 1: Take 100.0 mL of simulated mixed water sample into an Erlenmeyer flask, add 1.0 mL of deionized water (volume compensation), shake well, and keep at 80℃ for 10 hours as the blank baseline for scale inhibition rate calculation; Take 100.0 mL of simulated scale-forming water sample into an Erlenmeyer flask, add 1.0 mL of fracturing fluid samples prepared in Examples 1-3 and Comparative Examples 1-7 respectively, and heat at constant temperature under the same conditions; C0 is the ion concentration corresponding to the blank group, and C1 is the ion concentration corresponding to the experimental group; Scale inhibition rate (%) of corresponding ion (calcium or barium or strontium) = (C0 - C1) / C0 × 100%; Take the average value of the three parallel tests;

[0065] Corrosion Inhibition: Blank Group 2: This blank group provides a polymer fracturing fluid, which, by mass fraction, is mainly composed of 0.5% polyacrylamide thickener, with crosslinking agent and breaker as in Example 1, and the remainder being deionized water; the preparation method is the same as in Example 1; referring to standard SY / T 5273, N80 steel sheets (50 mm × 10 mm × 3 mm) were successively polished with 240#, 400#, and 800# sandpaper, ultrasonically cleaned with anhydrous ethanol, and dried with cold air, and then suspended in 500 mL of fracturing fluid samples prepared in Examples 1-3, Comparative Examples 1-7, and Blank Group 2. Potassium chloride, accounting for 2 wt% of the fracturing fluid sample mass, was added to the fracturing fluid samples prepared in Examples 1-3, Comparative Examples 1-7, and Blank Group 2. The corrosion rate (mm / a) was measured using the rotating plate method, with the rotation speed set at 75 ± 5 r / min, the temperature constant at 60℃, and the test time at 10 days; the corrosion inhibition rate was obtained by measuring the corrosion rate. ; The corrosion rate of blank group 2, The corrosion rate of the test group is given; the average value of the three parallel samples is taken.

[0066] Table 1. Results of fracturing fluid performance tests

[0067]

[0068] This invention provides a scale and corrosion inhibitor polymer fracturing fluid that integrates thickening, corrosion inhibition, and scale inhibition functions through the synergistic effect of a multifunctional copolymer thickener and a modified strontium barium dual-ion imprinted polymer.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A scale-inhibiting and corrosion-inhibiting polymer fracturing fluid, characterized in that: It includes a multifunctional copolymer thickener, a modified strontium barium dual-ion imprinted polymer, a crosslinking agent, a depolymerizer, and deionized water; The multifunctional copolymer thickener is obtained by polymerizing acrylamide, a polymerizable corrosion inhibitor, and a polymerizable scale inhibitor. The polymerizable scale inhibitor is a polymerizable compound formed by an amidation reaction of polyaspartic acid and N-(3-aminopropyl)methacrylamide. The modified strontium barium dual-ion imprinted polymer comprises a strontium barium dual-ion imprinted polymer core and a polyethylene glycol derivative loaded with an alkyl glycoside nonionic surfactant. The polyethylene glycol derivative loaded with an alkyl glycoside nonionic surfactant is attached to the outer surface of the strontium barium dual-ion imprinted polymer core. The polymerizable corrosion inhibitor is a polymerizable compound with corrosion inhibition function. The polymerizable corrosion inhibitor includes compound A and compound B. Compound A is a compound obtained by esterification reaction of dicarboxyl-terminated polyoxyethylene ether macromonomer and hydroxyl-polyethylene glycol-dithiopyridine disulfide. Compound B is a compound obtained by esterification reaction of imidazoline containing carboxylic acid group and hydroxyethyl methacrylate.

2. The scale-inhibiting and corrosion-inhibiting polymer fracturing fluid according to claim 1, characterized in that: The polymerizable corrosion inhibitor compound has a mass ratio of compound A to compound B of 1:2; compound A is a compound obtained by esterification reaction of dicarboxylate-terminated polyoxyethylene ether macromonomer and hydroxyl-polyethylene glycol-dithiopyridine disulfide at a mass ratio of 1:1; compound B is a compound obtained by esterification reaction of imidazoline containing carboxylic acid groups and hydroxyethyl methacrylate at a mass ratio of 3:

1.

3. The scale-inhibiting and corrosion-inhibiting polymer fracturing fluid according to claim 1, characterized in that: The polymerizable scale inhibitor compound was prepared by the following method: polyaspartic acid was dissolved in N,N-dimethylformamide, stirred evenly, and then N-(3-aminopropyl)methacrylamide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and N-hydroxysuccinimide were added, wherein the molar ratio of polyaspartic acid to N-(3-aminopropyl)methacrylamide was 1:1.2; the reaction was carried out under nitrogen protection and stirred at room temperature for 24 hours. After the reaction was completed, the reaction solution was slowly poured into excess anhydrous ethanol to precipitate the precipitate, filtered, and the precipitate was repeatedly washed with anhydrous ethanol and dried under vacuum to constant weight to obtain the polymerizable scale inhibitor compound.

4. The scale-inhibiting and corrosion-inhibiting polymer fracturing fluid according to claim 1, characterized in that: The polyethylene glycol derivative loaded with alkyl glycoside nonionic surfactant was prepared by the following method: polyethylene glycol diglycidyl ether was dispersed in deionized water, and alkyl glycoside nonionic surfactant and sodium carbonate were added, wherein the amount of alkyl glycoside nonionic surfactant added was 15% of the weight of polyethylene glycol diglycidyl ether. The reaction was carried out at a constant temperature of 45°C with stirring for 2.5 hours, and after concentration and drying, the polyethylene glycol derivative loaded with alkyl glycoside nonionic surfactant was obtained.

5. The scale-inhibiting and corrosion-inhibiting polymer fracturing fluid according to claim 1, characterized in that: In the modified strontium-barium dual-ion imprinted polymer, strontium and barium ions are used as dual templates, vinylphosphonic acid and acrylic acid are used as bifunctional monomers, and dimethacrylate-terminated polylactic acid-glycolic acid copolymer is used as a crosslinking agent. After polymerization and elution of template ions, the core of the strontium-barium dual-ion imprinted polymer is obtained.

6. The scale-inhibiting and corrosion-inhibiting polymer fracturing fluid according to claim 1, characterized in that: The modified strontium-barium dual-ion imprinted polymer was prepared by the following method: strontium chloride and barium chloride, vinylphosphonic acid and acrylic acid were dissolved in a dimethyl sulfoxide / acetonitrile mixed solvent, with a volume ratio of dimethyl sulfoxide to acetonitrile of 1:

4. The mixture was stirred for 1-2 hours, and then dimethacrylate-terminated polylactic acid-glycolic acid copolymer and azobisisobutyronitrile were added. The molar ratio of strontium chloride, barium chloride, vinylphosphonic acid, acrylic acid and dimethacrylate-terminated polylactic acid-glycolic acid copolymer was 0.5:0.5:(2-3):(1-2):15, and the amount of azobisisobutyronitrile added was 0.9% of the total mass of vinylphosphonic acid, acrylic acid and dimethacrylate-terminated polylactic acid-glycolic acid copolymer. After deoxygenation by purging with nitrogen, the mixture was reacted at 65-70℃ for 20-24 hours, filtered, and a polymer precipitate containing template ions was obtained. 0.1 The polymer precipitate was repeatedly washed with mol / L hydrochloric acid solution until no strontium and barium ions were detected in the washing solution. Then it was washed with water until neutral to obtain the strontium-barium dual-ion imprinted polymer core. The core of the strontium-barium biionic polymer was dispersed in deionized water, and 20% by weight of a polyethylene glycol derivative loaded with an alkyl glycoside nonionic surfactant was added to the core. Triethylamine was added dropwise to adjust the pH to 8-9, and the reaction was carried out at 55-60℃ for 8-10 hours. After the reaction was completed, the polymer was purified to obtain the modified strontium-barium biionic polymer.

7. The scale-inhibiting and corrosion-inhibiting polymer fracturing fluid according to claim 1, characterized in that: The mass ratio of acrylamide, polymerizable corrosion inhibitor, and polymerizable scale inhibitor is 45:2:

3.

8. The scale-inhibiting and corrosion-inhibiting polymer fracturing fluid according to claim 1, characterized in that: By mass fraction, it includes 0.5% multifunctional copolymer thickener, 0.26%~0.28% modified strontium barium dual-ion imprinted polymer, 0.15% crosslinking agent, 0.06% decapsulator, and the balance is deionized water; wherein, the crosslinking agent is an organozirconium crosslinking agent; and the decapsulator is a capsule decapsulator.

9. A method for preparing a scale-inhibiting and corrosion-inhibiting polymer fracturing fluid according to any one of claims 1-8, characterized in that: Includes the following steps: S1. Preparation of base solution: Add the multifunctional copolymer thickener to deionized water, stir and dissolve at 1500~2000 rpm, then add the modified strontium barium dual ion imprinted polymer, and ultrasonically disperse for 10~15 minutes to obtain the base solution; S2, cross-linking to form a gel: Add an organozirconium cross-linking agent to the base liquid under low-speed stirring, stir evenly, and let stand at 25°C for 30~40 minutes to form a gel solution; S3. Add capsule breaker to the glue solution and mix well to obtain scale and corrosion inhibitor polymer fracturing fluid.

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