Five-component hydrophobic associating modified acrylamide polymer and preparation method thereof, suspension thickener and fracturing fluid

Abstract

The present invention discloses a five-element hydrophobic associating modified acrylamide polymer and a preparation method thereof, a suspension thickener and a fracturing fluid. The fracturing fluid includes the following components in mass percentage: a suspension thickener 90% to 95%, a metal ion masking agent 1% to 2%, a drainage aid 1% to 2%, and a clay stabilizer 1% to 2%. The five-element hydrophobic associating modified acrylamide polymer of the present application is copolymerized by acrylamide, acrylic acid, sodium p-styrene sulfonate, 4-acryloylmorpholine and hexadecyl methacrylate, and mixed with a dispersant and an organic solvent to form a suspension thickener, and then mixed with a metal ion masking agent, a drainage aid, and a clay stabilizer to form a fracturing fluid for deep coal seam flowback reuse. The fracturing fluid system of the present invention has multiple functions such as high tolerance to mineralization, rapid viscosity increase, high flowback efficiency, and clay stability, and has broad application prospects and good economic benefits in the field of deep coal seam flowback reuse.

Description

Technical Field

[0001] The invention relates to the field of fracturing fluid, and in particular to a five-component hydrophobic associating modified acrylamide polymer and a preparation method thereof, a suspension thickener and a fracturing fluid. Background Art

[0002] my country has abundant reserves of coalbed methane resources. The Ordos Basin is the area with the largest proven recoverable reserves of coalbed methane. More than 90% of its recoverable reserves are deep coal seams, which are difficult to develop. Large-scale volume fracturing can achieve economical and effective development of deep coalbed methane. Water resources are scarce in the eastern Hubei region. With the large-scale fracturing operations in onshore oil and gas fields, a large amount of fracturing flowback fluid has become difficult to handle, which seriously restricts the scale and timeliness of large-scale volume fracturing operations. The deep coal seam fracturing flowback fluid has the characteristics of complex components, high mineralization, and high calcium and magnesium ion content. The development of a salt-resistant fracturing fluid system suitable for deep coal seam fracturing flowback fluid is an important guarantee for the reuse of flowback fluid.

[0003] Polymer thickeners have become an important direction for the development of salt-resistant fracturing fluid systems because of their easy modification, rapid dissolution, and no mixing. Functional monomers can be introduced during the polymerization of acrylamide and acrylic acid to improve the thickener's tolerance to mineralization and calcium and magnesium ions, and metal ion masking agents, drainage aids, clay stabilizers, etc. can be used to form an integrated fracturing fluid system. In oil and gas field fracturing operations, the commonly used fracturing fluid thickener is a quaternary hydrophobic associating polymer, which refers to a water-soluble polymer with a small amount of hydrophobic functional monomers on the polymer molecular chain. However, it still has the disadvantages of poor salt resistance and weak shear resistance during the reuse of deep coal seam flowback fluids. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a five-component hydrophobically associated modified acrylamide polymer and a preparation method thereof, a suspension thickener and a fracturing fluid.

[0005] In a first aspect, the present invention provides a five-membered hydrophobic associating modified acrylamide polymer, which is achieved by adopting the following technical solution.

[0006] A five-membered hydrophobically associating modified acrylamide polymer, the structural formula of which is as follows:

[0007]

[0008] Among them, a, b, c, d, and e are the molar percentages of monomers, wherein a is 60% to 70%, b is 25% to 35%, c is 1% to 5%, d is 1% to 5%, and e is 1% to 5%.

[0009] In a second aspect, the present invention provides a method for preparing a five-membered hydrophobic associating modified acrylamide polymer, which is achieved by adopting the following technical scheme.

[0010] A method for preparing a five-component hydrophobically associating modified acrylamide polymer comprises the following steps:

[0011] S1. acrylamide, acrylic acid, sodium p-styrene sulfonate, 4-acryloylmorpholine, and hexadecyl methacrylate are prepared into an aqueous solution of a certain mass concentration in a mass ratio of (8-10):(4-6):1:1:(2-4);

[0012] S2. Sodium dodecyl sulfate was added to the aqueous solution, mixed thoroughly, and then nitrogen was introduced for deoxygenation;

[0013] S3. Continue to add redox initiator and water-soluble azo initiator to the aqueous solution, under nitrogen environment and temperature conditions, continue stirring, and conduct multi-stage initiation copolymerization reaction;

[0014] S4. After the reaction is completed, the obtained five-membered copolymer product is collected by filtration, dried and solidified, sheared and crushed, soaked and washed with anhydrous ethanol, filtered, dried and crushed again to obtain a five-membered hydrophobically associated modified acrylamide polymer.

[0015] Furthermore, in step S1, the total mass concentration of the mixture in the aqueous solution is 35% to 45%.

[0016] Furthermore, in step S2, the amount of sodium dodecyl sulfate added is 1% to 2% of the mass of hexadecyl methacrylate.

[0017] Furthermore, in step S3, the redox initiator is selected from one of ammonium persulfate / sodium bisulfite, tert-butyl hydroperoxide ferrous sulfate / sodium sulfite, and sodium chlorate / sodium sulfite, and the amount of the redox initiator added is 0.2% to 0.5% of the mass of acrylamide added to the system.

[0018] Furthermore, in step S3, the water-soluble azo initiator is selected from one of dimethyl azobisisobutyrate, azobisisobutylimidazoline hydrochloride, azobisisobutylimidazole hydrochloride, and azoisobutylcyanamide, and the amount of the water-soluble azo initiator added is 0.6% to 0.9% of the mass of acrylamide added to the system.

[0019] Furthermore, in step S3, the reaction temperature of the copolymerization reaction is 80°C to 100°C, and the reaction time is 8h to 10h.

[0020] In a third aspect, the present invention provides a suspension-type thickener, which is achieved by adopting the following technical solution.

[0021] A suspension thickener comprises the following components in percentage by mass: 44% to 60% of the above-mentioned five-component hydrophobic associating modified acrylamide polymer, 1% to 2% of a dispersant, and 39% to 54% of an organic solvent.

[0022] Furthermore, the dispersant is selected from one of Span 40, Span 60, Span 80, Tween 60, Tween 80, AEO-7, and AEO-9.

[0023] Furthermore, the organic solvent is selected from one of diesel, kerosene, white oil and lubricating oil.

[0024] In a fourth aspect, the present invention provides a fracturing fluid for reuse of deep coal seam flowback fluid, which is achieved by adopting the following technical solution.

[0025] A fracturing fluid for recycling deep coal seam flowback fluid comprises the following components in percentage by mass: 90% to 95% of the above-mentioned suspension thickener, 1% to 4% of a metal ion masking agent, 1% to 4% of a drainage aid, and 1% to 2% of a clay stabilizer.

[0026] Furthermore, the metal ion masking agent is selected from one of ethylenediaminetetraacetic acid, oxalate, citric acid and tartaric acid.

[0027] Furthermore, the drainage aid is selected from one of long-chain fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, fatty acid polyoxyethylene ester, and polyoxyethylene alkyl alcohol amide.

[0028] Furthermore, the long-chain fatty alcohol polyoxyethylene ether is selected from one of polyoxyethylene cetyl ether and lauryl alcohol polyoxyethylene ether; the alkylphenol polyoxyethylene ether is selected from one of nonylphenol polyoxyethylene ether and octylphenol polyoxyethylene ether; the fatty acid polyoxyethylene ester is selected from one of polyoxyethylene laurate and polyoxyethylene stearate; and the polyoxyethylene alkyl alcohol amide is selected from lauroyl diethanolamine.

[0029] Furthermore, the clay stabilizer is selected from one of potassium iodide, ammonium chloride, dimethyldiallyl ammonium chloride and trimethylallyl ammonium chloride.

[0030] In a fifth aspect, the present invention provides a method for preparing a fracturing fluid for reuse of deep coal seam flowback fluid, which is achieved by adopting the following technical scheme.

[0031] A method for preparing a fracturing fluid for reuse of deep coal seam flowback fluid comprises the following steps:

[0032] The five-component hydrophobically associated modified acrylamide polymer is added to an organic solvent, supplemented with a dispersant, to prepare a uniform suspension system, and then a metal ion masking agent, a drainage aid and a clay stabilizer are added in sequence.

[0033] During the liquid preparation process, the reactor speed is 100r / min~120r / min, and the temperature is set to 50℃~80℃.

[0034] This application has the following beneficial effects.

[0035] The fracturing fluid system of the present invention has multiple functions such as high tolerance to mineralization, rapid viscosity increase, high flowback efficiency, clay stability, etc., and is particularly suitable for the preparation of fracturing flowback fluid for reuse in deep coal seams with high calcium and magnesium content and high mineralization. DETAILED DESCRIPTION

[0036] The present patent application is further described below in conjunction with embodiments.

[0037] Unless otherwise specified, the experimental methods used in the following preparation examples and examples are all conventional methods; the materials, reagents, etc. used in the following preparation examples and examples are all commercially available unless otherwise specified.

[0038] Example 1

[0039] Acrylamide, acrylic acid, sodium p-styrene sulfonate, 4-acryloylmorpholine, and hexadecyl methacrylate were prepared in a mass ratio of 8:4:1:1:2 to form an aqueous solution with a total mass concentration of 40%. Sodium dodecyl sulfate was added to the aqueous solution in an amount of 1% of the mass of hexadecyl methacrylate. After thorough mixing, nitrogen was introduced for deoxygenation. Ammonium sulfate / sodium bisulfite and dimethyl azobisisobutyrate were continued to be added to the aqueous solution in an amount of 0.2% and 0.6% of the mass of acrylamide added to the system, respectively. Under nitrogen environment and temperature conditions of 80°C, stirring was continued to carry out multi-stage initiation copolymerization reaction for 8 hours. After the reaction was completed, the obtained five-component copolymer product was filtered and collected, dried and solidified, sheared and crushed, soaked and washed with anhydrous ethanol, filtered, dried, and crushed again to obtain the target modified acrylamide polymer. The modified acrylamide polymer was evenly dispersed in diesel, supplemented with Span 60 to form a suspension thickener, in which the modified acrylamide polymer was 44%, the dispersant was 2%, and the solvent oil was 54%.

[0040] The speed of the reactor was set to 100 r / min, the reaction temperature was set to 50°C, ethylenediaminetetraacetic acid, polyoxyethylene hexadecyl ether, and dimethyldiallyl ammonium chloride were added, and the mixture was fully mixed. Among them, the mass proportion of the suspension thickener was 94%, the mass proportion of the metal ion masking agent was 2%, the mass proportion of the drainage agent was 2%, and the mass proportion of the clay stabilizer was 2%.

[0041] Example 2

[0042] Acrylamide, acrylic acid, sodium p-styrene sulfonate, 4-acryloylmorpholine, and hexadecyl methacrylate were prepared into an aqueous solution with a total mass concentration of 40% in a mass ratio of 8:4:1:1:2. Sodium dodecyl sulfate was added to the aqueous solution in an amount of 2% of the mass of hexadecyl methacrylate. After thorough mixing, nitrogen was introduced for deoxygenation. Tert-butyl hydroperoxide ferrous sulfate / sodium sulfite and dimethyl azobisisobutyrate were continued to be added to the aqueous solution in an amount of 0.5% and 0.9% of the mass of acrylamide added to the system, respectively. Under nitrogen environment and temperature conditions of 100°C, stirring was continued to carry out multi-stage initiation copolymerization reaction for 10 hours. After the reaction was completed, the obtained five-component copolymer product was collected by filtration, dried and solidified, sheared and crushed, soaked and washed with anhydrous ethanol, filtered, dried, and crushed again to obtain the target modified acrylamide polymer. The modified acrylamide polymer is uniformly dispersed in diesel, supplemented with Span 80 to form a suspension thickener, in which the modified acrylamide polymer is 48%, the dispersant is 2%, and the solvent oil is 50%.

[0043] The speed of the reactor was set to 100 r / min, the reaction temperature was set to 50°C, ethylenediaminetetraacetic acid, nonylphenol polyoxyethylene ether and ammonium chloride were added and mixed thoroughly to obtain the product. Among them, the mass proportion of the suspension thickener was 95%, the mass proportion of the metal ion masking agent was 2%, the mass proportion of the drainage agent was 2%, and the mass proportion of the clay stabilizer was 1%.

[0044] Example 3

[0045] Acrylamide, acrylic acid, sodium p-styrene sulfonate, 4-acryloylmorpholine, and hexadecyl methacrylate were prepared in a mass ratio of 10:4:1:1:2 to form an aqueous solution with a total mass concentration of 40%. Sodium dodecyl sulfate was added to the aqueous solution in an amount of 2% of the mass of hexadecyl methacrylate. After thorough mixing, nitrogen was introduced for deoxygenation. Sodium chlorate / sodium sulfite and azobisisobutylimidazoline hydrochloride were continued to be added to the aqueous solution in an amount of 0.4% and 0.8% of the mass of acrylamide added to the system, respectively. Under nitrogen environment and temperature conditions of 80°C, stirring was continued to carry out multi-stage initiation copolymerization reaction for 10 hours. After the reaction was completed, the obtained five-component copolymer product was collected by filtration, dried and solidified, sheared and crushed, soaked and washed with anhydrous ethanol, filtered, dried, and crushed again to obtain the target modified acrylamide polymer. The modified acrylamide polymer is evenly dispersed in diesel, supplemented with AEO-7 to form a suspension thickener, which contains 47% of modified acrylamide polymer, 1% of dispersant and 52% of solvent oil.

[0046] The speed of the reactor was set to 120r / min, the reaction temperature was set to 80°C, and tartaric acid, polyoxyethylene laurate, and potassium iodide were added and mixed thoroughly to obtain the product. Among them, the mass proportion of the suspension thickener was 95%, the mass proportion of the metal ion masking agent was 2%, the mass proportion of the drainage agent was 1%, and the mass proportion of the clay stabilizer was 2%.

[0047] Example 4

[0048] Acrylamide, acrylic acid, sodium p-styrene sulfonate, 4-acryloylmorpholine, and hexadecyl methacrylate were prepared in a mass ratio of 10:4:1:1:2 to form an aqueous solution with a total mass concentration of 40%. Sodium dodecyl sulfate was added to the aqueous solution in an amount of 2% of the mass of hexadecyl methacrylate. After thorough mixing, nitrogen was introduced for deoxygenation. Ammonium sulfate / sodium bisulfite and azobisisobutylamine hydrochloride were continued to be added to the aqueous solution in an amount of 0.4% and 0.8% of the mass of acrylamide added to the system, respectively. Under nitrogen environment and temperature conditions of 80°C, stirring was continued to carry out multi-stage initiation copolymerization reaction for 10 hours. After the reaction was completed, the obtained five-component copolymer product was collected by filtration, dried and solidified, sheared and crushed, soaked and washed with anhydrous ethanol, filtered, dried, and crushed again to obtain the target modified acrylamide polymer. The modified acrylamide polymer was evenly dispersed in diesel, supplemented with Span 60 to form a suspension thickener, in which the modified acrylamide polymer was 48%, the dispersant was 2%, and the solvent oil was 50%.

[0049] The speed of the reactor was set to 120r / min, the reaction temperature was set to 80°C, and ethylenediaminetetraacetic acid, lauroyl diethanolamine, and trimethylallyl ammonium chloride were added and mixed thoroughly to obtain the product. The mass proportion of the suspension thickener was 95%, the mass proportion of the metal ion masking agent was 2%, the mass proportion of the drainage agent was 2%, and the mass proportion of the clay stabilizer was 1%.

[0050] Performance Testing

[0051] After flocculation and multi-media filtration, the water quality of the flowback fluid from a tight gas block in a gas field in Northwest China is shown in Table 1. The flowback fluid after simple treatment is used as the water source, and a 0.9% fracturing fluid solution is prepared according to the site requirements. The prepared fracturing fluid is heated at 80°C (formation temperature) and 170s -1 Shearing was performed under the same conditions for 2 hours, and the apparent viscosity of the solution was measured. The temperature was kept constant at 80°C, and 0.2% ammonium persulfate was added to the fracturing fluid solution for 2 hours to break the gel, and the surface tension and interfacial tension of the solution after breaking the gel were measured. The experimental results are shown in Table 2.

[0052] Table 1 Water quality data of the treated fracturing flowback fluid in a tight gas block of a gas field in Northwest China

[0053] Table 2 Performance evaluation experimental results

[0054] The fracturing fluid used on-site in a tight gas block of a gas field in the northwest requires an apparent viscosity of ≥60mPa.S, and the surface tension of the fracturing fluid breaker is ≤28mN / m and the interfacial tension is ≤2mN / m as specified in "SY / T6376-2008 General Technical Conditions for Fracturing Fluids". The fracturing fluids prepared in Examples 1-4 can meet the above requirements, while conventional fracturing fluids on-site cannot meet these indicators. It can be seen that the fracturing fluid system of the present invention is a fracturing fluid system specifically for reuse of deep coal seam flowback fluid after simple treatment. Under the same conditions, the performance indicators are better than those of conventional fracturing fluid systems.

[0055] The embodiments of this specific implementation method are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A five-membered hydrophobically associating modified acrylamide polymer, characterized in that: The structural formula is as follows: Wherein, a, b, c, d, and e are the molar percentages of monomers, wherein a is 60% to 70%, b is 25% to 35%, c is 1% to 5%, d is 1% to 5%, and e is 1% to 5%; The preparation method of the five-membered hydrophobic associating modified acrylamide polymer comprises the following steps: S1. acrylamide, acrylic acid, sodium p-styrene sulfonate, 4-acryloylmorpholine, and hexadecyl methacrylate are prepared in a mass ratio of (8-10):(4-6):1:1:(2-4) to form an aqueous solution of a certain mass concentration; S2. Sodium dodecyl sulfate was added to the aqueous solution, mixed thoroughly, and then nitrogen was introduced for deoxygenation; S3. Continue to add redox initiator and water-soluble azo initiator to the aqueous solution, under nitrogen environment and temperature conditions, continue stirring, and conduct multi-stage initiation copolymerization reaction; S4. After the reaction is completed, the obtained five-membered copolymer product is collected by filtration, dried and solidified, sheared and crushed, soaked and washed with anhydrous ethanol, filtered, dried and crushed again to obtain a five-membered hydrophobically associated modified acrylamide polymer.

2. A method for preparing the five-membered hydrophobically associating modified acrylamide polymer according to claim 1, characterized in that: The following steps are involved: S1. acrylamide, acrylic acid, sodium p-styrene sulfonate, 4-acryloylmorpholine, and hexadecyl methacrylate are prepared in a mass ratio of (8-10):(4-6):1:1:(2-4) to form an aqueous solution of a certain mass concentration; S2. Sodium dodecyl sulfate was added to the aqueous solution, mixed thoroughly, and then nitrogen was introduced for deoxygenation; S3. Continue to add redox initiator and water-soluble azo initiator to the aqueous solution, under nitrogen environment and temperature conditions, continue stirring, and conduct multi-stage initiation copolymerization reaction; S4. After the reaction is completed, the obtained five-membered copolymer product is collected by filtration, dried and solidified, sheared and crushed, soaked and washed with anhydrous ethanol, filtered, dried and crushed again to obtain a five-membered hydrophobically associated modified acrylamide polymer.

3. The method for preparing a five-membered hydrophobically associating modified acrylamide polymer according to claim 2, characterized in that: In step S1, the total mass concentration of the mixture in the aqueous solution is 35% to 45%.

4. The method for preparing a five-membered hydrophobically associating modified acrylamide polymer according to claim 2, characterized in that: In step S2, the amount of sodium dodecyl sulfate added is 1% to 2% of the mass of hexadecyl methacrylate.

5. The method for preparing a five-membered hydrophobically associating modified acrylamide polymer according to claim 2, characterized in that: In step S3, the reaction temperature of the copolymerization reaction is 80°C to 100°C.

6. A suspension thickener, characterized in that: The invention comprises the following components in percentage by mass: 44% to 60% of the five-component hydrophobically associated modified acrylamide polymer according to claim 1, 1% to 2% of a dispersant, and 39% to 54% of an organic solvent.

7. A fracturing fluid for recycling deep coal seam flowback fluid, characterized in that: The invention comprises the following components in percentage by mass: 90% to 95% of the suspension thickener as claimed in claim 6, 1% to 4% of a metal ion masking agent, 1% to 4% of a drainage aid, and 1% to 2% of a clay stabilizer.

8. The fracturing fluid for reuse of deep coal seam flowback fluid according to claim 7, characterized in that: The metal ion masking agent is selected from one of ethylenediaminetetraacetic acid, oxalate, citric acid and tartaric acid.

9. The fracturing fluid for recycling deep coal seam flowback fluid according to claim 7, characterized in that: The drainage aid is selected from one of long-chain fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, fatty acid polyoxyethylene ester and polyoxyethylene alkyl alcohol amide.

10. The fracturing fluid for recycling deep coal seam flowback fluid according to claim 7, characterized in that: The clay stabilizer is selected from one of potassium iodide, ammonium chloride, dimethyldiallyl ammonium chloride and trimethylallyl ammonium chloride.

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