Anti-dispersion cement slurry system drag reducer and preparation and application thereof

Abstract

The invention discloses an anti-dispersion cement paste system drag reducer, the pH value of the anti-dispersion cement paste system drag reducer is 3.2-4.2, and the anti-dispersion cement paste system drag reducer is formed by polymerizing 15-25 parts of 3-methyl-3-butene-1-alcohol, 1.11-2.59 parts of formaldehyde, 170-230 parts of polyethylene glycol, 30-50 parts of 2-acrylamido-2-methylpropanesulfonic acid, 10-30 parts of maleic anhydride and 50-70 parts of unsaturated organic acid. The invention also discloses a preparation method thereof. The anti-dispersion cement slurry system drag reducer provided by the invention is applied to an anti-dispersion cement slurry system, can significantly improve the rheological property of anti-dispersion cement slurry and retain the anti-dispersion capability of the anti-dispersion cement slurry, reduces the initial consistency of the anti-dispersion cement slurry on the premise of ensuring the sedimentation stability, and improves the anti-dispersion performance of the anti-dispersion cement slurry. The influence on the development speed of the strength of the anti-dispersion cement slurry is not obvious, and technical and safety guarantee can be provided for application of the anti-dispersion cement slurry in well cementation construction.

Description

Technical Field

[0001] This invention relates to a drag-reducing agent for anti-dispersion cement slurry systems, its preparation, and its application. Technical Background

[0002] Currently, crude oil production largely relies on the potential development of older oilfields. Due to long-term water injection operations, these older oilfields suffer from problems such as underground pressure imbalance, increased water content, and the expansion of high-pressure aquifers. Water intrusion is a common problem encountered during well location adjustments and cementing operations in water-injection development areas. Damage to the cement sheath and decreased sealing quality become significant obstacles to cementing effectiveness. Particularly in oilfields with dense oil-water distribution and active underlying aquifers, water intrusion directly leads to poor cementing results, affects oil-water isolation, increases water cut during trial production, and weakens the well's production capacity. Solving this complex cementing technical problem has become a pressing technical challenge for many older oilfields.

[0003] To address this challenge, researchers developed an anti-dispersion cement slurry system to combat water intrusion and effectively seal oil, gas, and water layers. However, this system requires the use of polymeric additives such as polyacrylamide, which significantly increases the initial consistency of the slurry, hindering pumping and tubing displacement. Therefore, drag-reducing agents need to be added to the system to improve the rheological properties of the slurry, reduce friction, and enhance fluidity. However, the compatibility of drag-reducing agents with anti-dispersion agents remains a consideration. Summary of the Invention

[0004] In view of the above problems, the present invention is proposed to provide a drag-reducing agent and its preparation method to overcome or at least partially solve the above problems. The drag-reducing agent provided by the present invention is applied to an anti-dispersion cement slurry system to reduce the initial consistency of the anti-dispersion cement slurry while ensuring settling stability.

[0005] As one aspect of the present invention, a drag-reducing agent for anti-dispersion cement slurry systems is disclosed, the drag-reducing agent having a pH value of 3.2 to 4.2, and being polymerized from 15 to 25 parts of 3-methyl-3-buten-1-ol, 1.11 to 2.59 parts of formaldehyde, 170 to 230 parts of polyethylene glycol, 30 to 50 parts of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 10 to 30 parts of maleic anhydride, and 50 to 70 parts of unsaturated organic acid.

[0006] In a specific implementation, the molecular weight of the polyethylene glycol is 1000-4000; the unsaturated organic acid is itaconic acid, fumaric acid, or any combination thereof.

[0007] In a specific embodiment, the drag-reducing agent is polymerized from 15-25 parts of 3-methyl-3-buten-1-ol, 1.11-2.59 parts of formaldehyde, 170-230 parts of polyethylene glycol, 30-50 parts of 2-acrylamido-2-methylpropanesulfonic acid, 10-30 parts of maleic anhydride and 50-70 parts of unsaturated organic acid, using persulfate as an initiator.

[0008] As another aspect of the present invention, a method for preparing the above-mentioned drag-reducing agent for the anti-dispersion cement slurry system is provided, the method comprising:

[0009] (1) 15-25 parts of 3-methyl-3-buten-1-ol, 1.11-2.59 parts of formaldehyde, 170-230 parts of polyethylene glycol, 30-50 parts of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 10-30 parts of maleic anhydride and 50-70 parts of unsaturated organic acid are added to water;

[0010] (2) Under stirring conditions, heat to 60-80℃ and add 2-3 parts of initiator;

[0011] (3) Cool to 45-55℃ and adjust the pH value to 3.2-4.2.

[0012] In a specific implementation, the molecular weight of the polyethylene glycol is 1000 to 4000;

[0013] The unsaturated organic acid is itaconic acid, fumaric acid, or any combination thereof.

[0014] In a specific implementation, the initiator is one of sodium persulfate and ammonium persulfate, or any combination thereof.

[0015] In a specific implementation, step (2) is preferably carried out in a nitrogen atmosphere.

[0016] In a specific implementation, step (3) preferably uses sodium hydroxide to adjust the pH value.

[0017] As another aspect of the present invention, there is a dispersible cement slurry system comprising the above-mentioned drag-reducing agent for the dispersible cement slurry system.

[0018] The drag-reducing agent provided by this invention has at least the following advantages:

[0019] 1. The drag-reducing agent provided by this invention can significantly improve the rheological properties of anti-dispersion cement slurry;

[0020] 2. The drag-reducing agent provided by the present invention can retain the anti-dispersion ability of the anti-dispersion cement slurry. Detailed Implementation

[0021] Unless otherwise specified, the raw materials used in the embodiments are all included in the publicly available prior art. These materials can be purchased directly or prepared according to publicly available prior art methods.

[0022] Reagents used in Examples 1-10:

[0023] 3-Methyl-3-buten-1-ol is selected from Maclean's;

[0024] The formaldehyde solution is a 37 wt% formaldehyde solution, selected from Maclean's.

[0025] The polyethylene glycol was selected from Linyi Lusen;

[0026] 2-Acrylamido-2-methylpropanesulfonic acid (AMPS) is selected from Aladdin;

[0027] Maleic anhydride was selected from Aladdin;

[0028] Fumaric acid is selected from Chinese medicine.

[0029] Sodium persulfate and ammonium persulfate are selected from Chinese pharmaceutical companies;

[0030] Sodium hydroxide is selected from traditional Chinese medicine.

[0031] Unless otherwise stated, parts referred to in this application are parts by mass, and percentages are percentages by mass.

[0032] Example 1

[0033] Preparation of drag-reducing agents:

[0034] (1) 20 parts of 3-methyl-3-buten-1-ol, 5 parts of formaldehyde solution (1.85 parts of formaldehyde), 200 parts of polyethylene glycol, 50 parts of acrylamide-2-methylpropanesulfonic acid (AMPS), 10 parts of maleic anhydride and 60 parts of fumaric acid were added to 250 parts of water and stirred evenly to obtain a mixed solution.

[0035] (2) Under nitrogen atmosphere and stirring, maintain at 70°C for 2 hours; add 2 parts of sodium persulfate (sodium persulfate is dissolved in water before addition to prepare a 10% sodium persulfate aqueous solution), and maintain at 70°C for 3 hours;

[0036] (3) Cool to 50°C, add sodium hydroxide to adjust the pH to 3.6, and obtain drag-reducing agent.

[0037] The polyethylene glycol has a molecular weight of 4000 (Mw~4000).

[0038] Example 2

[0039] Preparation of drag-reducing agents:

[0040] (1) 20 parts of 3-methyl-3-buten-1-ol, 7 parts of formaldehyde solution (2.59 parts of formaldehyde), 200 parts of polyethylene glycol (Mw~2000), 40 parts of acrylamide-2-methylpropanesulfonic acid (AMPS), 20 parts of maleic anhydride and 60 parts of itaconic acid were added to 250 parts of water and stirred evenly to obtain a mixed solution;

[0041] (2) Under nitrogen atmosphere and stirring, maintain at 70°C for 2 hours; add 2 parts of sodium persulfate (sodium persulfate is dissolved in water before addition to prepare a 10% sodium persulfate aqueous solution), and maintain at 70°C for 3 hours.

[0042] (3) Cool to 50°C, add sodium hydroxide to adjust the pH to 3.6, and obtain drag-reducing agent.

[0043] Example 3

[0044] Preparation of drag-reducing agents:

[0045] (1) 20 parts of 3-methyl-3-buten-1-ol, 3 parts of formaldehyde solution (1.11 parts of formaldehyde), 200 parts of polyethylene glycol (Mw~1000), 30 parts of acrylamide-2-methylpropanesulfonic acid (AMPS), 20 parts of maleic anhydride and 70 parts of fumaric acid are added to 250 parts of water and stirred evenly to obtain a mixed solution.

[0046] (2) Under nitrogen atmosphere and stirring, maintain at 70°C for 2 hours; add 2 parts of sodium persulfate (sodium persulfate is dissolved in water before addition to prepare a 10% sodium persulfate aqueous solution), and maintain at 70°C for 3 hours.

[0047] (3) Cool to 50°C, add sodium hydroxide to adjust the pH to 3.6, and obtain drag-reducing agent.

[0048] Example 4

[0049] Preparation of drag-reducing agents:

[0050] (1) 20 parts of 3-methyl-3-buten-1-ol, 5 parts of formaldehyde solution (1.85 parts of formaldehyde), 200 parts of polyethylene glycol (Mw~6000), 50 parts of acrylamide-2-methylpropanesulfonic acid (AMPS), 30 parts of maleic anhydride and 40 parts of fumaric acid were added to 250 parts of water and stirred evenly to obtain a mixed solution.

[0051] (2) Under nitrogen atmosphere and stirring, keep at 50°C for 2 hours; add 2 parts of sodium persulfate (sodium persulfate is dissolved in water before addition to prepare a 10% sodium persulfate aqueous solution), and keep at 50°C for 3 hours.

[0052] (3) Cool to 40°C, add sodium hydroxide to adjust the pH to 3.0, and obtain drag-reducing agent.

[0053] Example 5

[0054] Preparation of drag-reducing agents:

[0055] (1) 20 parts of 3-methyl-3-buten-1-ol, 5 parts of formaldehyde solution (1.85 parts of formaldehyde), 200 parts of polyethylene glycol (Mw~800), 40 parts of acrylamide-2-methylpropanesulfonic acid (AMPS), 40 parts of maleic anhydride and 30 parts of fumaric acid were added to 250 parts of water and stirred evenly to obtain a mixed solution.

[0056] (2) Under nitrogen atmosphere and stirring, maintain at 90°C for 2 hours; add 2 parts of sodium persulfate (sodium persulfate is dissolved in water before addition to prepare a 10% sodium persulfate aqueous solution), and maintain at 90°C for 3 hours.

[0057] (3) Cool to 50°C, add sodium hydroxide to adjust the pH to 4.4, and obtain drag-reducing agent.

[0058] Example 6

[0059] Preparation of drag-reducing agents:

[0060] (1) 20 parts of 3-methyl-3-buten-1-ol, 7 parts of formaldehyde solution (2.59 parts of formaldehyde), 170 parts of polyethylene glycol (Mw~2000), 40 parts of acrylamide-2-methylpropanesulfonic acid (AMPS), 30 parts of maleic anhydride and 50 parts of itaconic acid were added to 250 parts of water and stirred evenly to obtain a mixed solution.

[0061] (2) Under nitrogen atmosphere and stirring, keep at 70°C for 2 hours; 2.5 parts of sodium persulfate (sodium persulfate is dissolved in water before being added to prepare a 10% sodium persulfate aqueous solution), keep at 70°C for 2 hours;

[0062] (3) Cool to 45°C, add sodium hydroxide to adjust the pH to 3.2, and obtain drag-reducing agent.

[0063] Example 7

[0064] Preparation of drag-reducing agents:

[0065] (1) 20 parts of 3-methyl-3-buten-1-ol, 7 parts of formaldehyde solution (2.59 parts of formaldehyde), 230 parts of polyethylene glycol (Mw~2000), 30 parts of acrylamide-2-methylpropanesulfonic acid (AMPS), 20 parts of maleic anhydride and 60 parts of itaconic acid were added to 250 parts of water and stirred evenly to obtain a mixed solution;

[0066] (2) Under nitrogen atmosphere and stirring, the reaction was maintained at 70°C for 2 hours; 3 parts of sodium persulfate were added (sodium persulfate was dissolved in water before addition to prepare a 10% sodium persulfate aqueous solution), and the reaction was maintained at 70°C for 2 hours.

[0067] (3) Cool to 55°C, add sodium hydroxide to adjust the pH to 4.2, and obtain drag-reducing agent.

[0068] Example 8

[0069] Preparation of drag-reducing agents:

[0070] (1) Take 20 parts of 3-methyl-3-buten-1-ol, 7 parts of formaldehyde solution (2.59 parts of formaldehyde), 200 parts of polyethylene glycol (Mw~2000), 30 parts of acrylamide-2-methylpropanesulfonic acid (AMPS), 20 parts of maleic anhydride and 60 parts of itaconic acid and add them to 250 parts of water, stir evenly to obtain a mixed solution;

[0071] (2) Under nitrogen atmosphere and stirring, maintain at 60°C for 2 hours; add 2 parts of sodium persulfate (sodium persulfate is dissolved in water before addition to prepare a 10% sodium persulfate aqueous solution), and maintain at 60°C for 2 hours.

[0072] (3) Cool to 50°C, add sodium hydroxide to adjust the pH to 3.6, and obtain drag-reducing agent.

[0073] Example 9

[0074] Preparation of drag-reducing agents:

[0075] (1) Take 15 parts of 3-methyl-3-buten-1-ol, 7 parts of formaldehyde solution (2.59 parts of formaldehyde), 200 parts of polyethylene glycol (Mw~2000), 30 parts of acrylamide-2-methylpropanesulfonic acid (AMPS), 20 parts of maleic anhydride and 60 parts of itaconic acid and add them to 250 parts of water, stir evenly to obtain a mixed solution;

[0076] (2) Under nitrogen atmosphere and stirring, maintain at 80°C for 2 hours; add 2 parts of sodium persulfate (sodium persulfate is dissolved in water before addition to prepare a 10% sodium persulfate aqueous solution), and maintain at 80°C for 2 hours.

[0077] (4) Cool to 50°C, add sodium hydroxide to adjust the pH to 3.6, and obtain drag-reducing agent.

[0078] Example 10

[0079] Preparation of drag-reducing agents:

[0080] (1) Take 25 parts of 3-methyl-3-buten-1-ol, 7 parts of formaldehyde solution (2.59 parts of formaldehyde), 200 parts of polyethylene glycol (Mw~2000), 30 parts of acrylamide-2-methylpropanesulfonic acid (AMPS), 20 parts of maleic anhydride and 60 parts of itaconic acid and add them to 250 parts of water, stir evenly to obtain a mixed solution;

[0081] (2) Under nitrogen atmosphere and stirring, maintain at 70°C for 2 hours; add 2 parts of sodium persulfate (sodium persulfate is dissolved in water before addition to prepare a 10% sodium persulfate aqueous solution), and maintain at 70°C for 2 hours.

[0082] (3) Cool to 50°C, add sodium hydroxide to adjust the pH to 3.6, and obtain drag-reducing agent.

[0083] Performance tests of the drag-reducing agents prepared in Examples 1-10:

[0084] Cement slurry was prepared in accordance with the People's Republic of China National Standard GB / T 19139-2012 "Test Methods for Cement in Oil Wells".

[0085] In the preparation of cement slurry, the G-grade oil well cement is Shengwei Cement;

[0086] The retarder is BH-R102L, produced and sold by PetroChina Bohai Drilling Engineering Co., Ltd., which is an organophosphonate retarder.

[0087] The defoamer is BZXP-1, produced and sold by PetroChina Bohai Drilling Engineering Company. It is a tributyl phosphate defoamer.

[0088] The anti-dispersant, code-named BH-KF, was prepared in-house by the laboratory of PetroChina Bohai Drilling Engineering Company. It is a polyacrylamide flocculant, and its preparation method is as follows:

[0089] Step 1: Add 50 parts acrylic acid to the water;

[0090] Step 2: Add 0.4 wt% sodium hydroxide solution to the system formed in Step 1 to adjust the pH to 4;

[0091] Step 3: Add 10 parts of N,N-dimethylacrylamide to the system formed in step 2 and stir until dissolved;

[0092] Step 4: Add 35 parts of acrylamide to the system formed in step 3 and stir until dissolved;

[0093] Step 5: Add 4 parts of N-vinylpyrrolidone to the system formed in step 4 and stir until dissolved;

[0094] Step 6: Add 1 part of disodium ethylenediaminetetraacetate to the system formed in step 5 and stir until dissolved;

[0095] Step 7: Introduce nitrogen into the system formed in step 6 to remove oxygen for 20 minutes, and place it in a constant temperature water bath at 30°C;

[0096] Step 8: Add 0.3 parts of initiator azomethylpropyl imidium hydrochloride to the system formed in step 7, stir until dissolved, and place in a 30°C constant temperature water bath;

[0097] Step 9: Add 0.3 parts potassium persulfate and 0.3 parts sodium bisulfite to the system formed in step 8, stir until dissolved, and place in a constant temperature water bath at 30°C;

[0098] Step 10: Seal the system formed in step 9 and keep it at 30°C for 4 hours to obtain the anti-dispersant.

[0099] The cement slurry formulation (based on 100% of the mass of G-grade oil well cement) is as follows: G-grade oil well cement + 3% anti-dispersant BH-KF + 0%–1.5% drag-reducing agent prepared in the embodiments of this invention + 0.1% defoamer BZXP-1 + 41%–43% water, with a cement slurry density of 1.90 g / cm³. 3 .

[0100] The blank control is cement slurry without the addition of the drag-reducing agent prepared in the embodiments of the present invention.

[0101] Method for measuring solid phase loss of cement slurry: First, prepare a 1000 ml beaker and add 600 ml of distilled water. Next, slowly pour in 680 g of cement slurry that has been stirred for 20 minutes at 80°C under normal pressure, ensuring that the slurry flows evenly from the mouth of the beaker into the lower container within 2 minutes, and wait for 5 minutes. Afterward, gently tilt the container to remove the top 600 ml of solution. After thoroughly stirring and homogenizing, use a digital liquid density meter to test its density. The calculation method is as follows: multiply the measured density value by the volume of 600 ml, and then subtract the mass of the same volume of water (600 g). This gives the total weight of the solid phase particles in the top 600 ml of water due to the impact of water during the pouring process. The results of the cement slurry solid phase loss measurement are shown in Table 1.

[0102] Method for determining the pH value of cement slurry: Similarly, prepare a 1000 ml beaker and pour in 600 ml of distilled water. Slowly pour 680 g of cement slurry, which has been stirred at 80 degrees Celsius for 20 minutes, into the beaker, ensuring that the slurry falls steadily into the container within 2 minutes, and let it stand for 5 minutes. Then, within 30 seconds, use a pipette to draw 10 ml of sample solution from the top of the beaker and test the pH value using precise pH test paper. Since the pH value of cement slurry is usually high, while the pH value of pure water is neutral, if the cement slurry mixes with water during the falling process, causing the cement particles to disperse, the pH value of the solution will rise significantly, indicating the degree of mixing between the cement particles and water. The results of the cement slurry pH value determination are shown in Table 1.

[0103] Table 1

[0104]

[0105]

[0106] According to the requirements of the "Test Procedure for Underwater Non-Dispersible Concrete" (DL / T5117-2000), the anti-dispersibility specification for anti-dispersible cement paste is a cement loss of less than 1.5% and a pH value of less than 12. Therefore, it can be seen that Example 5 only meets the performance requirements when the addition amount is no more than 1%, which means that the addition amount of Example 5 must be strictly controlled during use. In contrast, Example 4, even with an addition amount of 0.5% to 1.5%, did not reduce its consistency to below 30 Bc, indicating that even after adding Example 4, its pumpability remains weak and cannot meet the construction requirements.

[0107] According to GB / T19139 standard, the rheological properties and sedimentation stability of the anti-dispersion cement slurry added to each embodiment were tested at room temperature. The test results are shown in Table 2.

[0108] The cement slurry formulation (based on 100% of the mass of Grade G oil well cement) is as follows: Grade G oil well cement + 3% anti-dispersant BH-KF + 0.5% drag reducer prepared in the embodiments of this invention + 0.2% retarder BH-R102L + 0.1% defoamer BZXP-1 + 41%~43% water, with a cement slurry density of 1.90 g / cm³. 3 .

[0109] The blank control is cement slurry without the addition of the drag-reducing agent prepared in the embodiments of the present invention.

[0110] Table 2

[0111]

[0112] Table 2 shows that the drag-reducing agent prepared in each example significantly reduced the six-speed values ​​of the cement slurry added to all examples, indicating that the drag-reducing agent in the examples has a significant effect. However, in Example 5, the n value is less than 0.7, the K value is greater than 2, and the settlement stability is 0.02 g / cm³. 3 The density difference indicates that the drag-reducing agent prepared in Example 5 is unlikely to meet the requirements.

[0113] According to SY / T5504.3-2018, the influence of drag-reducing agents on the strength development of cement stone was analyzed, and the test results are shown in Table 3.

[0114] The cement slurry formulation (based on 100% of the mass of Grade G oil well cement) is as follows: Grade G oil well cement + 3% anti-dispersant BH-KF + 0.5% drag reducer prepared in the embodiments of this invention + 0.2% BH-R102L + 0.1% defoamer BZXP-1 + 41%~43% water, with a cement slurry density of 1.90 g / cm³. 3 The experimental conditions were: curing at 67℃ for 24 hours.

[0115] The blank control is cement slurry without the addition of the drag-reducing agent prepared in the embodiments of the present invention.

[0116] Table 3

[0117] Example Compressive strength (MPa) ratio of compressive strength Blank control 21.1 -- Example 1 20.7 0.98 Example 2 20.3 0.96 Example 3 20.4 0.97 Example 6 19.8 0.94 Example 7 20.2 0.96 Example 8 20.0 0.95 Example 9 19.8 0.94 Example 10 20.2 0.96

[0118] As shown in Table 3, the drag-reducing agents prepared in Examples 1-3 and Examples 6-10 have little effect on the strength development of cement stone.

[0119] As can be seen from the comparison of Examples 1-10, the drag-reducing agents prepared in Examples 1-3 and 6-10, when applied to the anti-dispersion cement slurry system, not only have good rheological properties, but also retain the anti-dispersion ability, and have no significant impact on the strength development rate of water-indispersible cement slurry. They can provide technical and safety guarantees for the application of anti-dispersion cement slurry in well cementing construction.

[0120] The preparation methods of Examples 1-3 and 6-10 can be summarized as follows:

[0121] (1) 15-25 parts of 3-methyl-3-buten-1-ol, 1.11-2.59 parts of formaldehyde, 170-230 parts of polyethylene glycol, 30-50 parts of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 10-30 parts of maleic anhydride and 50-70 parts of unsaturated organic acid are added to water;

[0122] (2) Under stirring conditions, heat to 60-80℃ and add 2-3 parts of initiator;

[0123] (3) Cool to 45-55℃ and adjust the pH value to 3.2-4.2.

[0124] The molecular weight of the polyethylene glycol is 1000 to 4000.

[0125] The unsaturated organic acid is itaconic acid, fumaric acid, or any combination thereof;

[0126] The initiator is one of sodium persulfate and ammonium persulfate or any combination thereof;

[0127] Step (2) is preferably performed under a nitrogen atmosphere;

[0128] Step (3) preferably uses sodium hydroxide to adjust the pH value.

Claims

1. A drag-reducing agent for anti-dispersion cement slurry systems, characterized in that, The drag-reducing agent has a pH of 3.2–4.2 and is polymerized from 15–25 parts of 3-methyl-3-buten-1-ol, 1.11–2.59 parts of formaldehyde, 170–230 parts of polyethylene glycol, 30–50 parts of 2-acrylamido-2-methylpropanesulfonic acid, 10–30 parts of maleic anhydride, and 50–70 parts of unsaturated organic acid.

2. The drag-reducing agent for anti-dispersion cement slurry system according to claim 1, characterized in that, The polyethylene glycol has a molecular weight of 1000-4000, and the unsaturated organic acid is itaconic acid, fumaric acid, or any combination thereof.

3. The drag-reducing agent for anti-dispersion cement slurry system according to claim 1, characterized in that, The drag-reducing agent is polymerized from 15-25 parts of 3-methyl-3-buten-1-ol, 1.11-2.59 parts of formaldehyde, 170-230 parts of polyethylene glycol, 30-50 parts of 2-acrylamido-2-methylpropanesulfonic acid, 10-30 parts of maleic anhydride and 50-70 parts of unsaturated organic acid, using persulfate as an initiator.

4. A method for preparing drag-reducing agents for anti-dispersion cement slurry systems, characterized in that, The method includes: (1) 15-25 parts of 3-methyl-3-buten-1-ol, 1.11-2.59 parts of formaldehyde, 170-230 parts of polyethylene glycol, 30-50 parts of 2-acrylamido-2-methylpropanesulfonic acid, 10-30 parts of maleic anhydride and 50-70 parts of unsaturated organic acid are added to water; (2) Under stirring conditions, heat to 60-80℃ and add 2-3 parts of initiator; (3) Cool to 45-55℃ and adjust the pH value to 3.2-4.

2.

5. The method according to claim 4, characterized in that, The molecular weight of the polyethylene glycol is 1000 to 4000.

6. The method according to claim 4, characterized in that, The unsaturated organic acid is itaconic acid, fumaric acid, or any combination thereof.

7. The method according to claim 4, characterized in that, The initiator is one of sodium persulfate and ammonium persulfate, or any combination thereof.

8. The method according to claim 4, characterized in that, Step (2) is carried out in a nitrogen atmosphere.

9. The method according to claim 4, characterized in that, Step (3) Use sodium hydroxide to adjust the pH value.

10. An anti-dispersion cement slurry system, characterized in that, The anti-dispersion cement slurry system contains the anti-dispersion cement slurry system drag-reducing agent according to any one of claims 1-3 or the anti-dispersion cement slurry system drag-reducing agent prepared by any one of claims 4-9.

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