Hydrophobic association polymer resistance reducing agent and preparation method thereof

Abstract

The invention relates to the technical field of oil and gas well reservoir transformation, in particular to a hydrophobic association polymer resistance reducing agent and a preparation method thereof, and aims to solve the problems of long dissolution time, poor tackifying effect and poor structural stability of a macromolecular polymer of the existing resistance reducing agent. The preparation method of the hydrophobically associating polymer resistance reducing agent provided by the invention starts from a practical angle, aims at dissolution time, salt tolerance and shear resistance, starts from molecular structure design, reduces monomer types, highlights the functionality of a single monomer and simplifies synthesis steps, and the hydrophobically associating polymer resistance reducing agent provided by the invention is short in dissolution time, low in cost and high in stability. The tackifying effect is good, and the molecular structure is stable.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas well reservoir transformation, and in particular to a hydrophobic associating polymer drag reducing agent and a preparation method thereof. Background Art

[0002] At present, shale gas fracturing mainly uses acrylamide polymers as drag reducers, which are divided into emulsion type, suspension type and powder. In order to facilitate construction, the drag reducer is required to have a short dissolution time and can be mixed online, and it is required to be able to switch freely between slippery water, linear gel and frozen gel. In addition, shale gas construction often uses backflow fluid to reduce environmental pollution, which puts higher requirements on the salt resistance of the drag reducer. In the Sichuan Basin, deep shale gas with a vertical depth of 4000m to 4500m accounts for 56.5%, which is the direction of future development.

[0003] To meet the above requirements, the current common practice is to introduce functional groups, such as sulfonic acid groups, into the polyacrylamide macromolecular chain to improve the salt resistance and temperature resistance of the macromolecule; introduce cyclic structure monomers to improve the rigidity of the macromolecule, and at the same time, due to the imidization effect, the degradation of the main chain can be delayed, thereby improving the stability of the macromolecule; introduce hydrophobic groups to form a reversible spatial network structure through association, thereby improving the shear resistance of the macromolecule.

[0004] Patent CN 111363092 B discloses a drag reducer for fracturing, whose monomers are maleic anhydride, butyl acrylate, and vinyl acetate, and the target product is obtained by emulsion polymerization. The drag reduction rate of clear water can reach 55.0%-60.0%, and the viscosity of 1% solution is 82.0-88.0mPa.s. At the same time, its viscosity after shearing at 120℃ for 2h is 63.0-66.0mPa·s, and its viscosity after shearing at 150℃ for 2h is 62.0-65.0mPa·s, and the dissolution time of 1.0% solution is 10-15s. Its short dissolution time can meet the requirements of online mixing, and its stability is good. The viscosity retention rate after shearing is high, which can meet the requirements of deep and ultra-deep construction. However, its drag reduction rate is low because there are no long-chain groups in the molecular chain and the macromolecular chain is not stretched enough.

[0005] Patent CN 109867746B uses inverse emulsion polymerization to synthesize a drag reducer polymer with high apparent viscosity at high salinity using acrylic acid, acrylamide and octadecyl methacrylate as monomers. The apparent viscosity of the system under salinity of 30,000 ppm was tested. The patent result has a low resistance to salinity and is difficult to meet the requirements of high salinity preparation construction on site.

[0006] At present, the macromolecular polymers of drag reducing agents still have shortcomings such as long dissolution time, poor viscosity-increasing effect and poor structural stability. Summary of the invention

[0007] The purpose of the present invention is to provide a hydrophobic associating polymer drag reducing agent and a preparation method thereof, so as to solve the problems of long dissolution time, poor viscosity increasing effect and poor structural stability of the current drag reducing agent macromolecular polymer.

[0008] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0009] In a first aspect, the present invention provides a method for preparing a hydrophobically associating polymer drag reducing agent, comprising the following preparation steps:

[0010] Step 1: synthesizing the multifunctional monomer, adding anhydrous ethanol into a three-necked flask, adding long-chain alkylphenol and N-hydroxymethyl acrylamide into the three-necked flask under electric stirring, fully stirring until completely dissolved, heating the mixed solution to 30-40° C., dropping concentrated sulfuric acid as a reaction catalyst, heating and stirring the reaction to end, vacuum filtering to obtain a crude product of the multifunctional monomer, and recrystallizing the crude product with anhydrous ethanol to obtain a high-purity multifunctional monomer;

[0011] Step 2: synthesize a hydrophobic associating polymer, dissolve acrylamide, anionic monomer and solubilizer in distilled water, dissolve the multifunctional monomer in ethanol, mix the two and stir them thoroughly, adjust the pH value of the mixed solution to 7 by dropping NaOH, add the mixed solution into a three-necked flask equipped with a stirring device, add a catalyst, react under constant temperature conditions, add anhydrous ethanol to the product, stir thoroughly until a precipitate is precipitated, repeatedly soak and wash the precipitate, and dry to obtain the target polymer.

[0012] Furthermore,

[0013] The long-chain alkylphenols are dodecylphenol, tetradecylphenol, hexadecylphenol, octadecylphenol, isomeric dodecylphenol, isomeric tetradecylphenol, isomeric hexadecylphenol and isomeric octadecylphenol.

[0014] Furthermore,

[0015] The anionic monomers are acrylic acid, methacrylic acid, 2-acrylamide-2-methylpropane sulfonic acid, sodium propylene sulfonate, sodium methpropylene sulfonate, and vinylbenzene sulfonic acid.

[0016] Furthermore,

[0017] The solubilizer is one or more of sodium dodecyl sulfate, sodium octyl sulfonate, sodium octylbenzene sulfonate, octanol polyoxyethylene ether, octylphenyl polyoxyethylene ether, dodecylphenol polyoxyethylene ether, and nonylphenol polyoxyethylene ether.

[0018] Furthermore,

[0019] The catalyst in step 2 is one or more of azobisisobutyronitrile, azobisisobutylamidine hydrochloride, azobisisoheptanenitrile, dimethyl azobisisobutyrate, ammonium persulfate, potassium persulfate, benzoyl peroxide, and tert-butyl benzoyl peroxide.

[0020] Furthermore,

[0021] In step 2, the molar ratio of acrylamide, anionic monomer and multifunctional monomer is 68.5-82.5:15.5-30.5:1-2.

[0022] Furthermore,

[0023] In step 2, the total solid content of acrylamide, anionic monomer and multifunctional monomer is 25-35%.

[0024] Furthermore,

[0025] The mass ratio of ethanol to distilled water in the mixed solvent is 1:10 to 1:5.

[0026] Furthermore,

[0027] The amount of the solubilizer added is 1.5 to 3% of the mass of distilled water.

[0028] In a second aspect, the present invention provides a hydrophobically associating polymer drag reducing agent prepared using the method for preparing the hydrophobically associating polymer drag reducing agent.

[0029] Based on the above technical solutions, the technical effects that can be achieved by the present invention are:

[0030] The preparation method of the hydrophobically associating polymer drag reducing agent provided by the present invention is based on practicality, takes dissolution time, salt resistance and shear resistance as targets, starts with molecular structure design, reduces monomer types, highlights the functionality of individual monomers, and simplifies the synthesis steps. The hydrophobically associating polymer drag reducing agent provided by the present invention has a short dissolution time, good viscosity increasing effect and a stable molecular structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 This is the rheological curve of the product of Example 8 after cross-linking;

[0033] Figure 2 This is the rheological curve of the product in Example 12 after cross-linking. DETAILED DESCRIPTION

[0001] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments.

[0002] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0003] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the reagents, materials, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels.

[0004] The present invention provides a high-stability and high-salt-resistant hydrophobic associating polymer suitable for deep and ultra-deep shale gas fracturing, and a preparation method of the hydrophobic associating polymer drag reducing agent. The specific synthesis method is as follows:

[0005] 1. Synthesis of multifunctional monomers

[0006] Add 500mL of anhydrous ethanol to a three-necked flask, add 2mol of long-chain alkylphenol and 1mol of N-hydroxymethyl acrylamide to the three-necked flask under electric stirring, and stir thoroughly until completely dissolved. Heat the mixed solution to 30-40°C, add 20mL of concentrated sulfuric acid as a reaction catalyst, and heat and stir the reaction for 72 hours before the reaction is completed. The synthesis device also includes a condensation reflux device. Vacuum filtration is performed to obtain a crude product of the multifunctional monomer. The crude product is recrystallized with anhydrous ethanol to obtain a high-purity multifunctional monomer.

[0007] Among them, long-chain alkylphenols include dodecylphenol, tetradecylphenol, hexadecylphenol, octadecylphenol, isomeric dodecylphenol, isomeric tetradecylphenol, isomeric hexadecylphenol, isomeric octadecylphenol and the like.

[0008] The synthetic reaction formula of the multifunctional monomer is as follows: (taking octadecylphenol as an example for long-chain alkylphenol)

[0009] 2. Synthesis of Hydrophobic Associating Polymers

[0010] Dissolve a certain amount of acrylamide, anionic monomer and solubilizer in distilled water, and dissolve a certain amount of multifunctional monomer in ethanol. Mix the two and stir them thoroughly, and adjust the pH value of the mixed solution to 7 by dropping 1 mol / L NaOH. Add the mixed solution to a three-necked flask equipped with a stirring device, add a catalyst, and react at a constant temperature of 70°C for 5 hours. Add anhydrous ethanol to the product, stir thoroughly until a precipitate is precipitated, soak and wash the precipitate repeatedly, and dry it to obtain the target polymer.

[0011] The anionic monomers include acrylic acid, methacrylic acid, 2-acrylamide-2-methylpropane sulfonic acid, sodium propylene sulfonate, sodium methpropylene sulfonate, vinylbenzene sulfonic acid and the like.

[0012] The solubilizer includes one or more of sodium dodecyl sulfate, sodium octyl sulfonate, sodium octylbenzene sulfonate, octanol polyoxyethylene ether, octylphenyl polyoxyethylene ether, dodecylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether and the like.

[0013] The catalyst is one or more of azobisisobutyronitrile, azobisisobutylamidine hydrochloride, azobisisoheptanenitrile, dimethyl azobisisobutyrate, ammonium persulfate, potassium persulfate, benzoyl peroxide, tert-butyl benzoyl peroxide, etc.

[0014] The molar ratio of acrylamide, anionic monomer and multifunctional monomer is 68.5-82.5:15.5-30.5:1-2.

[0015] The total solid content of the three reactants, acrylamide, anionic monomer and multifunctional monomer, is 25-35%, and the mass ratio of ethanol to distilled water in the mixed solvent is 1:10-1:5.

[0016] The amount of the solubilizer added is 1.5 to 3% of the mass of the distilled water.

[0017] The synthetic reaction formula of the hydrophobic associating polymer is as follows: (wherein the reactants are: acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, and the multifunctional monomer in the above reaction formula, wherein m, n, and p are all integers)

[0018] 1. Examples and Comparative Examples

[0019] According to the synthesis ideas and the selected monomer types, the effects of monomer types, molar ratios, and alkyl chain lengths on dissolution time, slippery water drag reduction, linear adhesive viscosity, and adhesive viscosity are compared. The examples listed in this patent are based on the core synthesis method and are not intended to limit the synthesis ideas of this patent.

[0020] Example 1

[0021] (1) Synthesis of multifunctional monomers

[0022] Add 500mL of anhydrous ethanol to a three-necked flask, add 2mol of octadecylphenol and 1mol of N-hydroxymethyl acrylamide to the three-necked flask under electric stirring, and stir thoroughly until completely dissolved. Heat the mixed solution to 30-40°C, add 20mL of concentrated sulfuric acid as a reaction catalyst, and heat and stir the reaction for 72 hours before the reaction is completed. The synthesis device also includes a condensation reflux device. Vacuum filtration is performed to obtain a crude product of the multifunctional monomer. The crude product is recrystallized with anhydrous ethanol to obtain a high-purity multifunctional monomer.

[0023] (2) Synthesis of hydrophobic associating polymers

[0024] Dissolve a certain amount of acrylamide, anionic monomer and sodium dodecyl sulfate in distilled water, and dissolve a certain amount of multifunctional monomer in ethanol. Mix the two and stir them thoroughly, and adjust the pH value of the mixed solution to 7 by dropping 1 mol / L NaOH. Add the mixed solution to a three-necked flask equipped with a stirring device, add azobisisobutyronitrile as a catalyst, and react at a constant temperature of 70°C for 5 hours. Add anhydrous ethanol to the product, stir thoroughly until a precipitate is precipitated, soak and wash the precipitate repeatedly, and dry it to obtain the target polymer.

[0025] The molar ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid and multifunctional monomer is 69.5:29.5:1. The total solid content of the three monomers is 30%, and the mass ratio of ethanol to distilled water in the mixed solvent is 1:10. The amount of solubilizer added is 2% of the mass of distilled water.

[0026] Example 2

[0027] (1) Synthesis of multifunctional monomers

[0028] Add 500mL of anhydrous ethanol to a three-necked flask, add 2mol of octadecylphenol and 1mol of N-hydroxymethyl acrylamide to the three-necked flask under electric stirring, and stir thoroughly until completely dissolved. Heat the mixed solution to 30-40°C, add 20mL of concentrated sulfuric acid as a reaction catalyst, and heat and stir the reaction for 72 hours before the reaction is completed. The synthesis device also includes a condensation reflux device. Vacuum filtration is performed to obtain a crude product of the multifunctional monomer. The crude product is recrystallized with anhydrous ethanol to obtain a high-purity multifunctional monomer.

[0029] (2) Synthesis of hydrophobic associating polymers

[0030] Dissolve a certain amount of acrylamide, anionic monomer and sodium dodecyl sulfate in distilled water, and dissolve a certain amount of multifunctional monomer in ethanol. Mix the two and stir them thoroughly, and adjust the pH value of the mixed solution to 7 by dropping 1 mol / L NaOH. Add the mixed solution to a three-necked flask equipped with a stirring device, add azobisisobutyronitrile as a catalyst, and react at a constant temperature of 70°C for 5 hours. Add anhydrous ethanol to the product, stir thoroughly until a precipitate is precipitated, soak and wash the precipitate repeatedly, and dry it to obtain the target polymer.

[0031] The molar ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid and multifunctional monomer is 75.5:23.5:1. The total solid content of the three monomers is 30%, and the mass ratio of ethanol and distilled water in the mixed solvent is 1:10. The amount of solubilizer added is 2% of the mass of distilled water.

[0032] Example 3

[0033] (1) Synthesis of multifunctional monomers

[0034] Add 500mL of anhydrous ethanol to a three-necked flask, add 2mol of octadecylphenol and 1mol of N-hydroxymethyl acrylamide to the three-necked flask under electric stirring, and stir thoroughly until completely dissolved. Heat the mixed solution to 30-40°C, add 20mL of concentrated sulfuric acid as a reaction catalyst, and heat and stir the reaction for 72 hours before the reaction is completed. The synthesis device also includes a condensation reflux device. Vacuum filtration is performed to obtain a crude product of the multifunctional monomer. The crude product is recrystallized with anhydrous ethanol to obtain a high-purity multifunctional monomer.

[0035] (2) Synthesis of hydrophobic associating polymers

[0036] Dissolve a certain amount of acrylamide, anionic monomer and sodium dodecyl sulfate in distilled water, and dissolve a certain amount of multifunctional monomer in ethanol. Mix the two and stir them thoroughly, and adjust the pH value of the mixed solution to 7 by dropping 1 mol / L NaOH. Add the mixed solution to a three-necked flask equipped with a stirring device, add azobisisobutyronitrile as a catalyst, and react at a constant temperature of 70°C for 5 hours. Add anhydrous ethanol to the product, stir thoroughly until a precipitate is precipitated, soak and wash the precipitate repeatedly, and dry it to obtain the target polymer.

[0037] The molar ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid and multifunctional monomer is 83.5:15.5:1. The total solid content of the three monomers is 30%, and the mass ratio of ethanol and distilled water in the mixed solvent is 1:10. The amount of solubilizer added is 2% of the mass of distilled water.

[0038] Example 4

[0039] (1) Synthesis of multifunctional monomers

[0040] Add 500mL of anhydrous ethanol to a three-necked flask, add 2mol of octadecylphenol and 1mol of N-hydroxymethyl acrylamide to the three-necked flask under electric stirring, and stir thoroughly until completely dissolved. Heat the mixed solution to 30-40°C, add 20mL of concentrated sulfuric acid as a reaction catalyst, and heat and stir the reaction for 72 hours before the reaction is completed. The synthesis device also includes a condensation reflux device. Vacuum filtration is performed to obtain a crude product of the multifunctional monomer. The crude product is recrystallized with anhydrous ethanol to obtain a high-purity multifunctional monomer.

[0041] (2) Synthesis of hydrophobic associating polymers

[0042] Dissolve a certain amount of acrylamide, anionic monomer and sodium dodecyl sulfate in distilled water, and dissolve a certain amount of multifunctional monomer in ethanol. Mix the two and stir them thoroughly, and adjust the pH value of the mixed solution to 7 by dropping 1 mol / L NaOH. Add the mixed solution to a three-necked flask equipped with a stirring device, add azobisisobutyronitrile as a catalyst, and react at a constant temperature of 70°C for 5 hours. Add anhydrous ethanol to the product, stir thoroughly until a precipitate is precipitated, soak and wash the precipitate repeatedly, and dry it to obtain the target polymer.

[0043] The molar ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid and multifunctional monomer is 68.5:30.5:1. The total solid content of the three monomers is 30%, and the mass ratio of ethanol and distilled water in the mixed solvent is 1:10. The amount of solubilizer added is 2% of the mass of distilled water.

[0044] Example 5

[0045] (1) Synthesis of multifunctional monomers

[0046] Add 500mL of anhydrous ethanol to a three-necked flask, add 2mol of octadecylphenol and 1mol of N-hydroxymethyl acrylamide to the three-necked flask under electric stirring, and stir thoroughly until completely dissolved. Heat the mixed solution to 30-40°C, add 20mL of concentrated sulfuric acid as a reaction catalyst, and heat and stir the reaction for 72 hours before the reaction is completed. The synthesis device also includes a condensation reflux device. Vacuum filtration is performed to obtain a crude product of the multifunctional monomer. The crude product is recrystallized with anhydrous ethanol to obtain a high-purity multifunctional monomer.

[0047] (2) Synthesis of hydrophobic associating polymers

[0048] Dissolve a certain amount of acrylamide, anionic monomer and sodium dodecyl sulfate in distilled water, and dissolve a certain amount of multifunctional monomer in ethanol. Mix the two and stir them thoroughly, and adjust the pH value of the mixed solution to 7 by dropping 1 mol / L NaOH. Add the mixed solution to a three-necked flask equipped with a stirring device, add azobisisobutyronitrile as a catalyst, and react at a constant temperature of 70°C for 5 hours. Add anhydrous ethanol to the product, stir thoroughly until a precipitate is precipitated, soak and wash the precipitate repeatedly, and dry it to obtain the target polymer.

[0049] The molar ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid and multifunctional monomer is 75:23.5:1.5. The total solid content of the three monomers is 30%. The mass ratio of ethanol and distilled water in the mixed solvent is 1:10. The amount of solubilizer added is 2% of the mass of distilled water.

[0050] Example 6

[0051] (1) Synthesis of multifunctional monomers

[0052] Add 500mL of anhydrous ethanol to a three-necked flask, add 2mol of octadecylphenol and 1mol of N-hydroxymethyl acrylamide to the three-necked flask under electric stirring, and stir thoroughly until completely dissolved. Heat the mixed solution to 30-40°C, add 20mL of concentrated sulfuric acid as a reaction catalyst, and heat and stir the reaction for 72 hours before the reaction is completed. The synthesis device also includes a condensation reflux device. Vacuum filtration is performed to obtain a crude product of the multifunctional monomer. The crude product is recrystallized with anhydrous ethanol to obtain a high-purity multifunctional monomer.

[0053] (2) Synthesis of hydrophobic associating polymers

[0054] Dissolve a certain amount of acrylamide, anionic monomer and sodium dodecyl sulfate in distilled water, and dissolve a certain amount of multifunctional monomer in ethanol. Mix the two and stir them thoroughly, and adjust the pH value of the mixed solution to 7 by dropping 1 mol / L NaOH. Add the mixed solution to a three-necked flask equipped with a stirring device, add azobisisobutyronitrile as a catalyst, and react at a constant temperature of 70°C for 5 hours. Add anhydrous ethanol to the product, stir thoroughly until a precipitate is precipitated, soak and wash the precipitate repeatedly, and dry it to obtain the target polymer.

[0055] The molar ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid and multifunctional monomer is 81.5:17.5:1. The total solid content of the three monomers is 30%, and the mass ratio of ethanol and distilled water in the mixed solvent is 1:10. The amount of solubilizer added is 2% of the mass of distilled water.

[0056] Example 7

[0057] (1) Synthesis of multifunctional monomers

[0058] Add 500mL of anhydrous ethanol to a three-necked flask, add 2mol of octadecylphenol and 1mol of N-hydroxymethyl acrylamide to the three-necked flask under electric stirring, and stir thoroughly until completely dissolved. Heat the mixed solution to 30-40°C, add 20mL of concentrated sulfuric acid as a reaction catalyst, and heat and stir the reaction for 72 hours before the reaction is completed. The synthesis device also includes a condensation reflux device. Vacuum filtration is performed to obtain a crude product of the multifunctional monomer. The crude product is recrystallized with anhydrous ethanol to obtain a high-purity multifunctional monomer.

[0059] (2) Synthesis of hydrophobic associating polymers

[0060] Dissolve a certain amount of acrylamide, anionic monomer and sodium dodecyl sulfate in distilled water, and dissolve a certain amount of multifunctional monomer in ethanol. Mix the two and stir them thoroughly, and adjust the pH value of the mixed solution to 7 by dropping 1 mol / L NaOH. Add the mixed solution to a three-necked flask equipped with a stirring device, add azobisisobutyronitrile as a catalyst, and react at a constant temperature of 70°C for 5 hours. Add anhydrous ethanol to the product, stir thoroughly until a precipitate is precipitated, soak and wash the precipitate repeatedly, and dry it to obtain the target polymer.

[0061] The molar ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid and multifunctional monomer is 78.5:20.5:1. The total solid content of the three monomers is 30%, and the mass ratio of ethanol and distilled water in the mixed solvent is 1:10. The amount of solubilizer added is 2% of the mass of distilled water.

[0062] Example 8

[0063] (1) Synthesis of multifunctional monomers

[0064] Add 500mL of anhydrous ethanol to a three-necked flask, add 2mol of octadecylphenol and 1mol of N-hydroxymethyl acrylamide to the three-necked flask under electric stirring, and stir thoroughly until completely dissolved. Heat the mixed solution to 30-40°C, add 20mL of concentrated sulfuric acid as a reaction catalyst, and heat and stir the reaction for 72 hours before the reaction is completed. The synthesis device also includes a condensation reflux device. Vacuum filtration is performed to obtain a crude product of the multifunctional monomer. The crude product is recrystallized with anhydrous ethanol to obtain a high-purity multifunctional monomer.

[0065] (2) Synthesis of hydrophobic associating polymers

[0066] Dissolve a certain amount of acrylamide, anionic monomer and sodium dodecyl sulfate in distilled water, and dissolve a certain amount of multifunctional monomer in ethanol. Mix the two and stir them thoroughly, and adjust the pH value of the mixed solution to 7 by dropping 1 mol / L NaOH. Add the mixed solution to a three-necked flask equipped with a stirring device, add azobisisobutyronitrile as a catalyst, and react at a constant temperature of 70°C for 5 hours. Add anhydrous ethanol to the product, stir thoroughly until a precipitate is precipitated, soak and wash the precipitate repeatedly, and dry it to obtain the target polymer.

[0067] The molar ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid and multifunctional monomer is 74.5:23.5:2. The total solid content of the three monomers is 30%. The mass ratio of ethanol and distilled water in the mixed solvent is 1:10. The amount of solubilizer added is 2% of the mass of distilled water.

[0068] Example 9

[0069] (1) Synthesis of multifunctional monomers

[0070] Add 500mL of anhydrous ethanol to a three-necked flask, add 2mol of octadecylphenol and 1mol of N-hydroxymethyl acrylamide to the three-necked flask under electric stirring, and stir thoroughly until completely dissolved. Heat the mixed solution to 30-40°C, add 20mL of concentrated sulfuric acid as a reaction catalyst, and heat and stir the reaction for 72 hours before the reaction is completed. The synthesis device also includes a condensation reflux device. Vacuum filtration is performed to obtain a crude product of the multifunctional monomer. The crude product is recrystallized with anhydrous ethanol to obtain a high-purity multifunctional monomer.

[0071] (2) Synthesis of hydrophobic associating polymers

[0072] Dissolve a certain amount of acrylamide, anionic monomer and sodium dodecyl sulfate in distilled water, and dissolve a certain amount of multifunctional monomer in ethanol. Mix the two and stir them thoroughly, and adjust the pH value of the mixed solution to 7 by dropping 1 mol / L NaOH. Add the mixed solution to a three-necked flask equipped with a stirring device, add azobisisobutyronitrile as a catalyst, and react at a constant temperature of 70°C for 5 hours. Add anhydrous ethanol to the product, stir thoroughly until a precipitate is precipitated, soak and wash the precipitate repeatedly, and dry it to obtain the target polymer.

[0073] The molar ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid and multifunctional monomer is 82.5:15.5:2. The total solid content of the three monomers is 30%. The mass ratio of ethanol and distilled water in the mixed solvent is 1:10. The amount of solubilizer added is 2% of the mass of distilled water.

[0074] Example 10

[0075] (1) Synthesis of multifunctional monomers

[0076] Add 500mL of anhydrous ethanol to a three-necked flask, add 2mol of octadecylphenol and 1mol of N-hydroxymethyl acrylamide to the three-necked flask under electric stirring, and stir thoroughly until completely dissolved. Heat the mixed solution to 30-40°C, add 20mL of concentrated sulfuric acid as a reaction catalyst, and heat and stir the reaction for 72 hours before the reaction is completed. The synthesis device also includes a condensation reflux device. Vacuum filtration is performed to obtain a crude product of the multifunctional monomer. The crude product is recrystallized with anhydrous ethanol to obtain a high-purity multifunctional monomer.

[0077] (2) Synthesis of hydrophobic associating polymers

[0078] Dissolve a certain amount of acrylamide, anionic monomer and sodium dodecyl sulfate in distilled water, and dissolve a certain amount of multifunctional monomer in ethanol. Mix the two and stir them thoroughly, and adjust the pH value of the mixed solution to 7 by dropping 1 mol / L NaOH. Add the mixed solution to a three-necked flask equipped with a stirring device, add azobisisobutyronitrile as a catalyst, and react at a constant temperature of 70°C for 5 hours. Add anhydrous ethanol to the product, stir thoroughly until a precipitate is precipitated, soak and wash the precipitate repeatedly, and dry it to obtain the target polymer.

[0079] The molar ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, acrylic acid and multifunctional monomer is 74:18:6:2. The total solid content of the three monomers is 30%. The mass ratio of ethanol and distilled water in the mixed solvent is 1:10. The amount of solubilizer added is 2% of the mass of distilled water.

[0080] Embodiment 11

[0081] (1) Synthesis of multifunctional monomers

[0082] Add 500mL of anhydrous ethanol to a three-necked flask, add 2mol of octadecylphenol and 1mol of N-hydroxymethyl acrylamide to the three-necked flask under electric stirring, and stir thoroughly until completely dissolved. Heat the mixed solution to 30-40°C, add 20mL of concentrated sulfuric acid as a reaction catalyst, and heat and stir the reaction for 72 hours before the reaction is completed. The synthesis device also includes a condensation reflux device. Vacuum filtration is performed to obtain a crude product of the multifunctional monomer. The crude product is recrystallized with anhydrous ethanol to obtain a high-purity multifunctional monomer.

[0083] (2) Synthesis of hydrophobic associating polymers

[0084] Dissolve a certain amount of acrylamide, anionic monomer and sodium dodecyl sulfate in distilled water, and dissolve a certain amount of multifunctional monomer in ethanol. Mix the two and stir them thoroughly, and adjust the pH value of the mixed solution to 7 by dropping 1 mol / L NaOH. Add the mixed solution to a three-necked flask equipped with a stirring device, add azobisisobutyronitrile as a catalyst, and react at a constant temperature of 70°C for 5 hours. Add anhydrous ethanol to the product, stir thoroughly until a precipitate is precipitated, soak and wash the precipitate repeatedly, and dry it to obtain the target polymer.

[0085] The molar ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, acrylic acid and multifunctional monomer is 74:16:8:2. The total solid content of the three monomers is 30%. The mass ratio of ethanol and distilled water in the mixed solvent is 1:10. The amount of solubilizer added is 2% of the mass of distilled water.

[0086] Example 12

[0087] (1) Synthesis of multifunctional monomers

[0088] Add 500mL of anhydrous ethanol to a three-necked flask, add 2mol of octadecylphenol and 1mol of N-hydroxymethyl acrylamide to the three-necked flask under electric stirring, and stir thoroughly until completely dissolved. Heat the mixed solution to 30-40°C, add 20mL of concentrated sulfuric acid as a reaction catalyst, and heat and stir the reaction for 72 hours before the reaction is completed. The synthesis device also includes a condensation reflux device. Vacuum filtration is performed to obtain a crude product of the multifunctional monomer. The crude product is recrystallized with anhydrous ethanol to obtain a high-purity multifunctional monomer.

[0089] (2) Synthesis of hydrophobic associating polymers

[0090] Dissolve a certain amount of acrylamide, anionic monomer and sodium dodecyl sulfate in distilled water, and dissolve a certain amount of multifunctional monomer in ethanol. Mix the two and stir them thoroughly, and adjust the pH value of the mixed solution to 7 by dropping 1 mol / L NaOH. Add the mixed solution to a three-necked flask equipped with a stirring device, add azobisisobutyronitrile as a catalyst, and react at a constant temperature of 70°C for 5 hours. Add anhydrous ethanol to the product, stir thoroughly until a precipitate is precipitated, soak and wash the precipitate repeatedly, and dry it to obtain the target polymer.

[0091] The molar ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, acrylic acid and multifunctional monomer is 74:12:12:2. The total solid content of the three monomers is 30%. The mass ratio of ethanol and distilled water in the mixed solvent is 1:10. The amount of solubilizer added is 2% of the mass of distilled water.

[0092] Example 13

[0093] (1) Synthesis of multifunctional monomers

[0094] Add 500mL of anhydrous ethanol to a three-necked flask, add 2mol of hexadecylphenol and 1mol of N-hydroxymethyl acrylamide to the three-necked flask under electric stirring, and stir thoroughly until completely dissolved. Heat the mixed solution to 30-40°C, add 20mL of concentrated sulfuric acid as a reaction catalyst, and heat and stir the reaction for 72 hours before the reaction is completed. The synthesis device also includes a condensation reflux device. The crude product of the multifunctional monomer is obtained by vacuum filtration. The crude product is recrystallized with anhydrous ethanol to obtain a high-purity multifunctional monomer.

[0095] (2) Synthesis of hydrophobic associating polymers

[0096] Dissolve a certain amount of acrylamide, anionic monomer and sodium dodecyl sulfate in distilled water, and dissolve a certain amount of multifunctional monomer in ethanol. Mix the two and stir them thoroughly, and adjust the pH value of the mixed solution to 7 by dropping 1 mol / L NaOH. Add the mixed solution to a three-necked flask equipped with a stirring device, add azobisisobutyronitrile as a catalyst, and react at a constant temperature of 70°C for 5 hours. Add anhydrous ethanol to the product, stir thoroughly until a precipitate is precipitated, soak and wash the precipitate repeatedly, and dry it to obtain the target polymer.

[0097] The molar ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid and multifunctional monomer is 74:24:2. The total solid content of the three monomers is 30%. The mass ratio of ethanol and distilled water in the mixed solvent is 1:10. The amount of solubilizer added is 2% of the mass of distilled water.

[0098] Embodiment 14

[0099] (1) Synthesis of multifunctional monomers

[0100] Add 500mL of anhydrous ethanol to a three-necked flask, add 2mol of tetradecylphenol and 1mol of N-hydroxymethyl acrylamide to the three-necked flask under electric stirring, and stir thoroughly until completely dissolved. Heat the mixed solution to 30-40°C, add 20mL of concentrated sulfuric acid as a reaction catalyst, and heat and stir the reaction for 72 hours before the reaction is completed. The synthesis device also includes a condensation reflux device. Vacuum filtration is performed to obtain a crude product of the multifunctional monomer. The crude product is recrystallized with anhydrous ethanol to obtain a high-purity multifunctional monomer.

[0101] (2) Synthesis of hydrophobic associating polymers

[0102] Dissolve a certain amount of acrylamide, anionic monomer and sodium dodecyl sulfate in distilled water, and dissolve a certain amount of multifunctional monomer in ethanol. Mix the two and stir them thoroughly, and adjust the pH value of the mixed solution to 7 by dropping 1 mol / L NaOH. Add the mixed solution to a three-necked flask equipped with a stirring device, add azobisisobutyronitrile as a catalyst, and react at a constant temperature of 70°C for 5 hours. Add anhydrous ethanol to the product, stir thoroughly until a precipitate is precipitated, soak and wash the precipitate repeatedly, and dry it to obtain the target polymer.

[0103] The molar ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid and multifunctional monomer is 74:24:2. The total solid content of the three monomers is 30%. The mass ratio of ethanol and distilled water in the mixed solvent is 1:10. The amount of solubilizer added is 2% of the mass of distilled water.

[0104] Embodiment 15

[0105] (1) Synthesis of multifunctional monomers

[0106] Add 500mL of anhydrous ethanol to a three-necked flask, add 2mol of dodecylphenol and 1mol of N-hydroxymethyl acrylamide to the three-necked flask under electric stirring, and stir thoroughly until completely dissolved. Heat the mixed solution to 30-40°C, add 20mL of concentrated sulfuric acid as a reaction catalyst, and heat and stir the reaction for 72 hours before the reaction is completed. The synthesis device also includes a condensation reflux device. The crude product of the multifunctional monomer is obtained by vacuum filtration. The crude product is recrystallized with anhydrous ethanol to obtain a high-purity multifunctional monomer.

[0107] (2) Synthesis of hydrophobic associating polymers

[0108] Dissolve a certain amount of acrylamide, anionic monomer and sodium dodecyl sulfate in distilled water, and dissolve a certain amount of multifunctional monomer in ethanol. Mix the two and stir them thoroughly, and adjust the pH value of the mixed solution to 7 by dropping 1 mol / L NaOH. Add the mixed solution to a three-necked flask equipped with a stirring device, add azobisisobutyronitrile as a catalyst, and react at a constant temperature of 70°C for 5 hours. Add anhydrous ethanol to the product, stir thoroughly until a precipitate is precipitated, soak and wash the precipitate repeatedly, and dry it to obtain the target polymer.

[0109] The molar ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid and multifunctional monomer is 74:24:2. The total solid content of the three monomers is 30%. The mass ratio of ethanol and distilled water in the mixed solvent is 1:10. The amount of solubilizer added is 2% of the mass of distilled water.

[0110] Comparative Example

[0111] Two commercially available hydrophobic associating polyacrylamide drag reducing agent products (product models AP-C1 and GRF) were selected for comparison. The product dissolution time, drag reduction rate and viscosity are shown in Table 1.

[0112] 2. Implement product performance evaluation

[0113] Examples 1 to 9 investigated the effect of the monomer molar ratio on product performance, and the mixing water was simulated mineralized water with a mineralization degree of 50,000 ppm. When the anionic monomer was only 2-acrylamide-2-methylpropanesulfonic acid (AMPS), the dissolution time of the product was less than 50 seconds, which could meet the requirements of on-site online mixing. The drag reduction rate of slippery water was greater than 74%, showing good drag reduction performance. The viscosity of the linear glue was greater than 30 mPa·s. The viscosity of the glue solution increases with the increase of the molar ratio of the multifunctional monomer in the macromolecular chain. This is because after the hydrophobic associating polymer exceeds the critical concentration (CAC), the molecules form aggregates, which leads to a significant increase in viscosity.

[0114] Table 1 Performance evaluation of examples and comparative examples

[0115] Examples 10 to 12 investigate the performance of products obtained by polymerization of two anionic monomers (2-acrylamide-2-methylpropanesulfonic acid and acrylic acid). As shown in Table 1, the performance of products obtained by different ratios of the two anions is similar. Research staff can select anionic monomers containing different functional groups for polymerization according to actual production needs, and further improve the performance of the product based on the core synthesis idea of ​​this scheme.

[0116] Examples 13 to 15 investigate the effects of multifunctional monomers with different carbon chain lengths on product performance. As shown in Table 1, as the carbon chain length decreases, the dissolution time of the product is shortened and the viscosity of the glue solution is reduced. This is because the aggregation morphology of the hydrophobic associating polymer is affected by the carbon chain length.

[0117] The comparative examples are two commercially available hydrophobically associated polyacrylamide drag reducing agents. The dissolution time is longer than that of the examples, the drag reducing performance is lower than that of the examples, and the viscosity of the linear glue and the glue solution is close to that of the examples. By comparison, it can be seen that the product synthesis method proposed in the present invention is superior to the two commercially available hydrophobically associated polyacrylamide drag reducing agent products.

[0118] In order to further expand product demand, the rheological curve of the product after cross-linking was tested, such as Figure 1 and Figure 2 As shown in the figure, in 170S -1After 60 minutes of shearing under the same conditions, the apparent viscosity of the two products remained above 150mPa·s, showing good shear resistance. The products have a short dissolution time, good viscosity-increasing effect and stable molecular structure. The reason is that the macromolecular chain includes both long-chain alkyl hydrophobic groups and cyclic rigid groups, which improves the shear resistance and temperature resistance of the products while ensuring the solubility of the products.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a hydrophobically associating polymer drag reducing agent, characterized in that: The method comprises the following preparation steps: Step 1: synthesizing the multifunctional monomer, adding anhydrous ethanol into a three-necked flask, adding long-chain alkylphenol and N-hydroxymethyl acrylamide into the three-necked flask under electric stirring, fully stirring until completely dissolved, heating the mixed solution to 30-40° C., dropping concentrated sulfuric acid as a reaction catalyst, heating and stirring the reaction to end, vacuum filtering to obtain a crude product of the multifunctional monomer, and recrystallizing the crude product with anhydrous ethanol to obtain a high-purity multifunctional monomer; Step 2: synthesize a hydrophobic associating polymer, dissolve acrylamide, anionic monomer and solubilizer in distilled water, dissolve the multifunctional monomer in ethanol, mix the two and stir them thoroughly, adjust the pH value of the mixed solution to 7 by dropping NaOH, add the mixed solution into a three-necked flask equipped with a stirring device, add a catalyst, react under constant temperature conditions, add anhydrous ethanol to the product, stir thoroughly until a precipitate is precipitated, repeatedly soak and wash the precipitate, and dry to obtain the target polymer.

2. The method for preparing the hydrophobically associating polymer drag reducing agent according to claim 1, characterized in that: The long-chain alkylphenols are dodecylphenol, tetradecylphenol, hexadecylphenol, octadecylphenol, isomeric dodecylphenol, isomeric tetradecylphenol, isomeric hexadecylphenol and isomeric octadecylphenol.

3. The method for preparing the hydrophobically associating polymer drag reducing agent according to claim 1, characterized in that: The anionic monomers are acrylic acid, methacrylic acid, 2-acrylamide-2-methylpropane sulfonic acid, sodium propylene sulfonate, sodium methpropylene sulfonate, and vinylbenzene sulfonic acid.

4. The method for preparing the hydrophobically associating polymer drag reducing agent according to claim 1, characterized in that: The solubilizer is one or more of sodium dodecyl sulfate, sodium octyl sulfonate, sodium octylbenzene sulfonate, octanol polyoxyethylene ether, octylphenyl polyoxyethylene ether, dodecylphenol polyoxyethylene ether, and nonylphenol polyoxyethylene ether.

5. The method for preparing the hydrophobically associating polymer drag reducing agent according to claim 1, characterized in that: The catalyst in step 2 is one or more of azobisisobutyronitrile, azobisisobutylamidine hydrochloride, azobisisoheptanenitrile, dimethyl azobisisobutyrate, ammonium persulfate, potassium persulfate, benzoyl peroxide, and tert-butyl benzoyl peroxide.

6. The method for preparing the hydrophobically associating polymer drag reducing agent according to claim 1, characterized in that: In step 2, the molar ratio of acrylamide, anionic monomer and multifunctional monomer is 68.5-82.5:15.5-30.5:1-2.

7. The method for preparing the hydrophobically associating polymer drag reducing agent according to claim 1, characterized in that: In step 2, the total solid content of acrylamide, anionic monomer and multifunctional monomer is 25-35%.

8. The method for preparing the hydrophobically associating polymer drag reducing agent according to claim 1, characterized in that: The mass ratio of ethanol to distilled water in the mixed solvent is 1:10 to 1:

5.

9. The method for preparing the hydrophobically associating polymer drag reducing agent according to claim 1, characterized in that: The amount of the solubilizer added is 1.5 to 3% of the mass of distilled water.

10. A hydrophobically associating polymer drag reducing agent prepared by the method for preparing a hydrophobically associating polymer drag reducing agent according to any one of claims 1 to 9.

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