Carbon dioxide pollution resistant filtrate reducer for water-based drilling fluid and preparation method thereof
By preparing a novel amphoteric polymer containing components such as sodium p-styrene sulfonate and N-vinylpyrrolidone, the problem of uncontrolled filtration performance of drilling fluid under carbon dioxide pollution was solved, and the temperature resistance, salt resistance and calcium resistance of drilling fluid were improved, thereby reducing the cost of drilling fluid.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CNPC BOHAI DRILLING ENG
- Filing Date
- 2024-11-11
- Publication Date
- 2026-05-12
AI Technical Summary
Existing drilling fluids exhibit uncontrolled filtration performance under carbon dioxide contamination, leading to failure of the drilling fluid's rheological properties and filtration reduction capabilities, posing a risk of wellbore collapse. Existing solutions are either costly or have significant performance impacts.
A novel amphoteric polymer with large side groups, cationic monomers, and a rigid structure was used to prepare a carbon dioxide pollution-resistant filtration reducer for water-based drilling fluids by introducing components such as sodium p-styrene sulfonate and N-vinylpyrrolidone. This enhances the charge attraction to clay particles, competitively adsorbs carbonate and bicarbonate ions, and strengthens the carbon dioxide holding threshold of the drilling fluid.
It effectively improves the filtration performance of drilling fluid under carbon dioxide pollution, reduces the risk of drilling fluid contamination by carbon dioxide, and has good resistance to temperature, salt and calcium, thus reducing the cost of drilling fluid.
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Figure CN122011256A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of filtration loss reducers for water-based drilling fluids, and relates to a method for preparing a filtration loss reducer that resists carbon dioxide pollution. Specifically, it relates to a filtration loss reducer for water-based drilling fluids that resists carbon dioxide pollution and its preparation method. Background Technology
[0002] With the continuous development of oil and gas exploration, the problem of carbon dioxide pollution during drilling has become increasingly prominent. Specifically, carbon dioxide affects the function of filtration control agents used in drilling fluids. Because filtration control agents have strong surface activity, they can adsorb onto clay particles. The conversion products of carbon dioxide (such as carbonate and bicarbonate ions) also easily adsorb onto the surface of clay particles, competing with the filtration control agents for adsorption sites. This affects the effective adsorption of filtration control agents by clay particles, leading to a thinning of the hydration film on the surface of clay particles, increased flocculation, and loss of control over the rheology and filtration control performance of the drilling fluid. This can result in stuck tripping, increased pump pressure, difficulty starting the pump, and in severe cases, the risk of wellbore collapse, making drilling operations difficult to carry out smoothly.
[0003] Currently, solutions to the problem of carbon dioxide contamination in drilling fluids include prevention and post-contamination treatment. Preventive measures include using brine drilling fluid systems and pressure balancing methods. While the former, using brine slurry, has stronger anti-contamination capabilities, it is more expensive and its performance is difficult to control during use. With the pressure balancing method, if gas logging readings are suppressed, oil and gas reservoirs cannot be detected. The most common post-contamination treatment method is to supplement calcium ions, causing them to precipitate with carbonate ions; however, this method has a significant impact on drilling fluid performance.
[0004] In addition, raising the threshold for carbon dioxide tolerance is also an effective way to solve the problem of carbon dioxide pollution in drilling fluids. For example, Chinese invention patent application CN114292632A discloses a carbon dioxide complexing agent for drilling fluids, its preparation method and application. However, the mass fraction of carbon dioxide it can complex is only 0.25%, and the carbon dioxide complexing agent has a single function, which also increases the cost of drilling fluids when used. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention aims to provide a carbon dioxide contamination-resistant filtration reducer for water-based drilling fluids. By introducing large side groups, cationic monomers, rigid structures, and sulfonic acid groups, a novel amphoteric polymer with strong adsorption is prepared. This enhances the charge attraction to negatively charged bentonite layers, making it more competitive than bicarbonate groups when adsorbing clay particles. This increases the threshold for carbon dioxide capacity in drilling fluids and solves the problem of uncontrolled filtration performance after carbon dioxide contamination.
[0006] Another object of the present invention is to provide a method for preparing the above-mentioned anti-carbon dioxide contamination filtration loss reducer for water-based drilling fluids.
[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0008] A water-based drilling fluid anti-carbon dioxide contamination and filtration reduction agent, the raw materials of which include: Solution I, alkaline solution and initiator;
[0009] As a limitation of the present invention
[0010] The solutes in solution I include monomers N'N-dimethylacrylamide, sodium p-styrenesulfonate, dimethyl diallyl ammonium chloride, N-vinylpyrrolidone, and 2-acrylamide-2-methylpropanesulfonic acid in a molar ratio of 5:(3-8):(1-5):(0-4):(1-6).
[0011] Further, N'N-dimethylacrylamide: sodium p-styrenesulfonate: dimethyldiallylammonium chloride: N-vinylpyrrolidone: 2-acrylamide-2-methylpropanesulfonic acid = 5:(6~7):(2~3):(1~2):(4~5).
[0012] As a further limitation of the present invention, the alkaline solution is a sodium hydroxide solution.
[0013] As a further limitation of the present invention, the initiator is added under stirring conditions at 70°C to 80°C.
[0014] As a further limitation of the present invention, the initiator is a mixture of ammonium persulfate and sodium bisulfite in a molar ratio of 1:1.
[0015] The present invention also provides a method for preparing the above-mentioned anti-carbon dioxide contamination filtration reduction agent for water-based drilling fluids, comprising the following steps performed sequentially:
[0016] S1. Add the monomers N'N-dimethylacrylamide, sodium p-styrenesulfonate, dimethyldiallylammonium chloride, N-vinylpyrrolidone and 2-acrylamide-2-methylpropanesulfonic acid in a molar ratio of 5:(3~8):(1~5):(0~4):(1~6) to water in sequence, and after complete dissolution, prepare solution I.
[0017] S2. Add the alkaline solution to solution I, adjust the pH, and add deionized water to obtain solution II;
[0018] S3. After heating solution II, an initiator is added under stirring. After reacting for 1.5 to 3 hours, solution IV is obtained.
[0019] S4. After drying and pulverizing solution IV, an anti-carbon dioxide pollution filtration loss reducer is obtained.
[0020] As a limitation of the present invention, the pH adjustment is 5 to 6.
[0021] As another limitation of the present invention, in step S2, when adding water, the water is added until the sum of the masses of the monomers accounts for 20% to 30% of the total mass of solution II.
[0022] As a third limitation of the present invention, ammonium persulfate from the initiator is first added to solution II to obtain solution III; then sodium bisulfite dissolved in deionized water is uniformly added dropwise to solution III to obtain solution IV. As another limitation of the present invention, the drying process is carried out at 60–100°C.
[0023] By adopting the above-described technical solution, the beneficial effects achieved by this invention compared to the prior art are as follows:
[0024] (1) The water-based drilling fluid anti-carbon dioxide pollution filtration reduction agent provided by the present invention adopts an inseparable filtration reduction agent system composed of monomers N'N-dimethylacrylamide, sodium p-styrenesulfonate, dimethyl diallyl ammonium chloride, N-vinylpyrrolidone and 2-acrylamido-2-methylpropanesulfonic acid. While each component performs its own function, they work synergistically with each other. Among them, N'N-dimethylacrylamide and dimethyl diallyl ammonium chloride provide large monomer steric hindrance, sodium p-styrenesulfonate and N-vinylpyrrolidone provide rigid structure, dimethyl diallyl ammonium chloride provides cationic monomer, and 2-acrylamido-2-methylpropanesulfonic acid provides sulfonic acid group. When used, each component forms a novel amphoteric polymer with strong adsorption. This novel amphoteric polymer has a strong charge attraction to the negatively charged bentonite layer and can compete with carbonate and bicarbonate for adsorption, thereby increasing the carbon dioxide holding threshold and thus improving the drilling fluid performance and reducing the risk of uncontrolled filtration performance after the drilling fluid is contaminated by carbon dioxide.
[0025] (2) The water-based drilling fluid anti-carbon dioxide pollution filtration reduction agent provided by the present invention utilizes the rigid polycyclic ring structure of sodium styrene sulfonate and N-vinylpyrrolidone to improve the high temperature resistance of the polymer.
[0026] (3) The water-based drilling fluid anti-carbon dioxide contamination filtration reducer provided by the present invention utilizes the sulfonate structure of sodium styrene sulfonate to improve the calcium and salt resistance of the filtration reducer and further enhance its temperature resistance. In a base slurry with added calcium ions, the medium-pressure filtration loss with the added filtration reducer is only 10% of that without the added filtration reducer; and in a brine slurry, the medium-pressure filtration loss is within 10 mL, and no uncontrolled filtration loss occurs, demonstrating its excellent anti-carbon dioxide contamination performance.
[0027] (4) The preparation process of this invention is simple, and the synthesis temperature and time are easy to control.
[0028] In summary, this invention is applicable to the preparation of a carbon dioxide contamination-resistant filtration-reducing agent for water-based drilling fluids. Attached Figure Description
[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.
[0030] Figure 1 The infrared spectrum analysis diagram is shown for ZSNJ-1, the anti-carbon dioxide pollution filtration reduction agent prepared in Example 2 of the present invention. Detailed Implementation
[0031] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustrative and understanding purposes only and are not intended to limit the scope of the invention.
[0032] Example 1
[0033] This embodiment is a water-based drilling fluid anti-carbon dioxide pollution and filtration reduction agent. The raw materials include: solution I, sodium hydroxide solution, and an initiator made of ammonium persulfate and sodium bisulfite in a molar ratio of 1:1.
[0034] Solution I was prepared by dissolving the monomers N'N-dimethylacrylamide, sodium p-styrenesulfonate, dimethyldiallylammonium chloride, N-vinylpyrrolidone and 2-acrylamido-2-methylpropanesulfonic acid in deionized water in a molar ratio of 5:7:2:1:4.
[0035] Example 2
[0036] This embodiment describes a method for preparing a carbon dioxide contamination-resistant filtration reduction agent for water-based drilling fluids, comprising the following steps performed sequentially:
[0037] S1. Preparation of Solution I
[0038] With a molar ratio of 5:7:2:1:4, 0.2 mol N'N-dimethylacrylamide, 0.28 mol sodium p-styrenesulfonate, 0.08 mol dimethyldiallylammonium chloride, 0.04 mol N-vinylpyrrolidone, and 0.16 mol 2-acrylamide-2-methylpropanesulfonic acid were sequentially added to a beaker containing 200 mL of deionized water and dissolved completely to obtain solution I.
[0039] S2. Preparation of Solution II
[0040] Add sodium hydroxide solution to solution I, adjust its pH to 5, and then add a certain amount of deionized water. After adding deionized water, the total mass of the monomers accounts for 30% of the total mass of solution II, thus obtaining solution II.
[0041] S3. Preparation of Solution III
[0042] Place the beaker containing solution II on a water bath and heat it to 80°C. Maintain this temperature and add 0.25% (by weight) of the monomer as an initiator while stirring. First, add 0.22g of ammonium persulfate directly to solution II to obtain solution III.
[0043] S4. Preparation of Solution IV
[0044] Dissolve 0.11g of sodium bisulfite in 10mL of deionized water and add it dropwise evenly to solution III. Start timing from the time the sodium bisulfite is added. After 3 hours of reaction, a viscous solution is obtained, which is solution IV.
[0045] S5. Preparation of Filtration Loss Reducing Agent
[0046] After drying solution IV at 60°C, it is pulverized to obtain a white or light yellow powder, which is the anti-carbon dioxide pollution filtration reduction agent, denoted as ZSNJ-1.
[0047] like Figure 1 As shown, the chemical structure of the carbon dioxide pollution filtration reducer ZSNJ-1 prepared in this embodiment was determined using Fourier transform infrared spectroscopy.
[0048] The results showed that 2932cm -1 The peak at 1412 cm⁻¹ is the asymmetric stretching vibration peak of -CH₂ on the main chain; -1 and 1457cm -1 The peak at 627 cm⁻¹ is the bending vibration peak of CN in N'N-dimethylacrylamide; -1 and 1040cm -1 The peaks at 1672 cm⁻¹ are the stretching vibration peaks of -CS and -SO₃ in 2-acrylamido-2-methylpropanesulfonic acid, respectively; -1 The peak at 3435 cm⁻¹ represents the stretching vibration peak of the -C=O group in the amide. It can be seen that the position of the -C=O group shifted to some extent due to the addition of N-vinylpyrrolidone. -1 The peak at 1546 cm⁻¹ is the stretching vibration peak of -NH. -1 The peak at that location is in dimethyl diallyl ammonium chloride with the -CN content. + Characteristic peaks. Additionally, at 1600-1640 cm⁻¹. -1 The absence of a characteristic peak for C=C within the range indicates that the monomer has reacted completely and ZSNJ-1 has been successfully prepared.
[0049] Example 3
[0050] This embodiment describes a method for preparing a carbon dioxide pollution-resistant filtration reduction agent for water-based drilling fluids. The specific preparation steps are the same as in Example 2, except that the only differences are the molar ratio of each solute in solution I and the reaction time for preparing solution IV.
[0051] In this embodiment, the molar ratio of solutes in solution I is 5:6:2:1:5, of which N'N-dimethylacrylamide is 0.2 mol, and the other components can be calculated based on their molar ratios. When preparing solution IV, after adding the sodium bisulfite solution, a viscous solution was obtained after reacting for 1.5 hours. After drying and pulverizing, the carbon dioxide pollution-resistant filtration loss reducer ZSNJ-2 was obtained.
[0052] Example 4
[0053] This embodiment describes a method for preparing a carbon dioxide pollution-resistant filtration reduction agent for water-based drilling fluids. The specific preparation steps are the same as in Example 3, except for the molar ratio of each solute in solution I, the volume of solution II, the stirring temperature for preparing solution III, and the reaction time for preparing solution IV.
[0054] In this embodiment, the molar ratio of solutes in solution I is 5:6:3:2:4, with N'N-dimethylacrylamide at 0.2 mol. The other components can be calculated based on their molar ratios. Deionized water is added to make the volume of solution II 295 mL. Solution III is prepared by heating in a water bath to 70°C and then stirring. Solution IV is prepared by adding sodium bisulfite solution dropwise and reacting for 3 hours to obtain a viscous solution. After drying and pulverizing, the carbon dioxide pollution-resistant filtration loss reducer ZSNJ-3 is obtained.
[0055] Example 5
[0056] This embodiment describes a method for preparing a carbon dioxide pollution-resistant filtration reduction agent for water-based drilling fluids. The specific preparation steps are the same as in Example 4, except for the molar ratio of each solute in solution I, the volume of solution II, and the reaction time for preparing solution IV.
[0057] In this embodiment, the molar ratio of solutes in solution I is 5:6.5:2.5:1.5:4.5, of which N'N-dimethylacrylamide is 0.2 mol. The other components can be calculated based on their molar ratios. Deionized water is added to make the volume of solution II 310 mL. When preparing solution IV, after adding sodium bisulfite solution, the reaction is allowed to proceed for 1.5 h to obtain a viscous solution. After drying and pulverizing, the carbon dioxide pollution-resistant filtration loss reducer ZSNJ-4 is obtained.
[0058] Example 6
[0059] This embodiment describes a method for preparing a carbon dioxide pollution-resistant filtration reduction agent for water-based drilling fluids. The specific preparation steps are the same as in Example 5, except for the molar ratio of each solute in Solution I, the volume of Solution II, and the mass of the initiator added.
[0060] In this embodiment, the molar ratio of solutes in solution I is 5:7:3:2:5, with N'N-dimethylacrylamide at 0.2 mol. The other components can be calculated based on their molar ratios. Deionized water is added to make the volume of solution II 335 mL. When preparing solution III, 0.25 g of ammonium persulfate initiator is added; when preparing solution IV, 0.12 g of sodium bisulfite initiator is added. After drying and pulverizing, the carbon dioxide pollution-resistant filtration loss reducer ZSNJ-5 is obtained.
[0061] The filtration loss reduction performance of the anti-carbon dioxide pollution filtration loss reducers (ZSNJ-1, ZSNJ-2, ZSNJ-3, ZSNJ-4) prepared in Examples 2 to 5 above was evaluated.
[0062] All percentages mentioned below are mass fractions.
[0063] A base slurry was prepared by adding 0.2% anhydrous sodium carbonate and 4% bentonite to 400 mL of water. 1% of the sample was added to the base slurry, and then the basic properties were determined after aging at 180℃ for 16 hours. Wherein, AV represents apparent viscosity, PV represents plastic viscosity, YP represents dynamic shear force, and FL... API The result represents the medium-pressure filtration loss, as shown in Table 1.
[0064] Table 1. Filtration reduction performance of different polymeric filtration reducers in base slurry
[0065] sample AV(mPa·s) PV (mPa·s) YP(Pa) <![CDATA[FL API (mL)]]> Base slurry + 1% ZSNJ-1 32 22 10 8.5 Base slurry + 1% ZSNJ-2 26.5 20 6.5 9.4 Base slurry + 1% ZSNJ-3 37.5 25 12.5 9.0 Base slurry + 1% ZSNJ-4 30 21 8 9.1 Base slurry + 1% ZSNJ-5 33.5 24 9.5 9.2
[0066] As can be seen from Table 1, the four anti-carbon dioxide pollution filtration loss reducing agents prepared in Examples 2 to 6 all have good filtration loss reduction ability after aging at 180°C in the base slurry. Among them, ZSNJ-1 has the best filtration loss reduction ability.
[0067] ZSNJ-1 was selected as the filtration loss reducer. Further evaluation of its resistance to salt, calcium ion contamination, and carbon dioxide contamination was conducted by setting up a control group, as detailed below:
[0068] (1) Determination of salt resistance
[0069] Three groups of samples containing ZSNJ-1 and different salt concentrations were prepared, and their salt resistance was tested. Specifically, 2% ZSNJ-1 was added to the base slurry for the first group of samples, and 15% and 30% sodium chloride were added to the first group of samples, respectively. After aging at 180℃ for 16 hours, their salt resistance was measured. The results are shown in Table 2.
[0070] Table 2 Salt resistance properties of filtration loss reducer ZSNJ-1
[0071] sample AV(mPa·s) PV (mPa·s) YP(Pa) <![CDATA[FL API (mL)]]> Base slurry + 2% ZSNJ-1 63.5 44 19.5 6.5 Base slurry + 2% ZSNJ-1 + 15% NaCl 19.5 16 3.5 7.8 Base slurry + 2% ZSNJ-1 + 30% NaCl 32 14 18 10.4
[0072] As can be seen from Table 2, ZSNJ-1 has good salt resistance and can resist 30% salt contamination at a dosage of 2%.
[0073] (2) Determination of resistance to calcium ion contamination performance
[0074] Two groups of samples containing ZSNJ-1 and calcium ions were prepared, and their resistance to calcium ion contamination was tested. Specifically, calcium ions were provided by calcium chloride. For the first group of samples, 5000 ppm of calcium ions were added directly to the base slurry. For the second group of samples, 2% ZSNJ-1 was added to the base slurry first, and then 5000 ppm of calcium ions were added. After aging at 180℃ for 16 hours, the basic properties were measured. The results are shown in Table 3.
[0075] Table 3. Anti-calcium ion fouling performance of filtration loss reducer ZSNJ-1
[0076]
[0077] As can be seen from Table 3, ZSNJ-1 has good resistance to calcium ion fouling. The medium-pressure filtration loss of the base slurry with ZSNJ-1 is only 10% of that of the base slurry without ZSNJ-1.
[0078] (3) Determining the resistance to carbon dioxide pollution
[0079] The performance of filtration loss reducer ZSNJ-1 against carbon dioxide contamination in freshwater and brine slurries was investigated by adding bicarbonate ions. The specific test procedure is as follows:
[0080] Sodium bicarbonate was used to provide bicarbonate. The first three groups of freshwater slurry samples were first treated with 2% ZSNJ-1, followed by 5000 ppm, 7500 ppm and 10000 ppm of bicarbonate, respectively. After aging at 180℃ for 16 hours, the basic properties were measured. The latter three groups of brine slurry samples were first treated with 2% ZSNJ-1 and 15% sodium chloride, followed by 5000 ppm, 7500 ppm and 10000 ppm of bicarbonate, respectively. After aging at 180℃ for 16 hours, the basic properties were measured. The results are shown in Table 4.
[0081] Table 4. Anti-carbon dioxide pollution performance of filter loss reducer ZSNJ-1
[0082]
[0083] As can be seen from Table 4, whether in freshwater slurry or brine slurry, ZSNJ-1, after being contaminated with 10,000 ppm of bicarbonate, had a medium-pressure filtration loss of less than 10 mL, and there was no runaway filtration loss, demonstrating its good resistance to carbon dioxide contamination.
[0084] In summary, the carbon dioxide pollution-resistant filtration reducer prepared by this invention has excellent resistance to salt, calcium, and carbon dioxide pollution.
[0085] Examples 7-8
[0086] Examples 7 and 8 describe a method for preparing a carbon dioxide contamination-resistant filtration reducer for water-based drilling fluids. The specific preparation steps are the same as in Example 1, except that the pH value is adjusted when preparing solution II. In Example 7, the pH is adjusted to 5.5; in Example 8, the pH is adjusted to 6.
[0087] Examples 9-10
[0088] Examples 9 and 10 describe a method for preparing a carbon dioxide contamination-resistant filtration reducer for water-based drilling fluids. The specific preparation steps are the same as in Example 1, except for the drying temperature of the filtration reducer. The drying temperature in Example 9 is 80°C; the drying temperature in Example 10 is 100°C.
[0089] Examples 11-12
[0090] Examples 11-12 are methods for preparing a water-based drilling fluid anti-carbon dioxide pollution filtration reduction agent. The specific preparation steps are the same as in Example 2, except that the only differences are the molar ratio of each solute in solution I and the amount of water added.
[0091] Example 11: Without adding N-vinylpyrrolidone, solution I contains monomers N'N-dimethylacrylamide, sodium p-styrenesulfonate, dimethyldiallylammonium chloride, and 2-acrylamide-2-methylpropanesulfonic acid in a ratio of 5:3:1:1, wherein N'N-dimethylacrylamide is 0.2 mol, and the other components are calculated based on the molar ratio.
[0092] In Example 12, solution I contained N'N-dimethylacrylamide, sodium p-styrenesulfonate, dimethyldiallylammonium chloride, N-vinylpyrrolidone, and 2-acrylamido-2-methylpropanesulfonic acid in a ratio of 5:8:5:4:6, with N'N-dimethylacrylamide at 0.2 mol. The other components were calculated based on their molar ratios. The filtration loss reduction performance of Examples 7-12 was determined using the above method. The medium-pressure filtration loss was consistently below 10 mL, indicating that the prepared samples possessed good filtration loss reduction capabilities.
[0093] After adding deionized water, the total mass of the monomers in Examples 11 and 12 accounted for 25% and 30% of the total mass of their solution II, respectively.
[0094] Comparative Example
[0095] This comparative study selected commercially available fluid loss reducers JD-6, TCJ-3, and Redul-1 as comparative products to examine the anti-fouling performance of drilling fluids formulated with each product against 10,000 ppm bicarbonate.
[0096] One filtration loss reducer was added to each of the three base slurries, and 10,000 ppm of bicarbonate was added. After aging at 180°C for 16 hours, the basic properties were measured, and the results are shown in Table 5.
[0097] Table 5. Carbon dioxide pollution resistance performance of existing products
[0098]
[0099]
[0100] As shown in Table 5, the drilling fluid prepared from three commercially available filtration loss reducers exhibited a significantly higher medium-pressure filtration loss after high-temperature aging under 10,000 ppm bicarbonate contamination conditions than the product prepared in this invention. This resulted in uncontrolled filtration loss and performance failure of the drilling fluid, indicating that the existing product has very low resistance to carbon dioxide contamination. It should be noted that the above descriptions are merely preferred embodiments of this invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions described in the above embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.
Claims
1. A water-based drilling fluid anti-carbon dioxide contamination filtration reduction agent, characterized in that: The raw materials used to make its active ingredient include: Solution I, alkaline solution, and initiator; The solutes in solution I include monomers N'N-dimethylacrylamide, sodium p-styrenesulfonate, dimethyl diallyl ammonium chloride, N-vinylpyrrolidone, and 2-acrylamide-2-methylpropanesulfonic acid in a molar ratio of 5:(3~8):(1~5):(0~4):(1~6).
2. The water-based drilling fluid anti-carbon dioxide contamination and filtration loss reducing agent according to claim 1, characterized in that: The alkaline solution is a sodium hydroxide solution.
3. The water-based drilling fluid anti-carbon dioxide contamination filtration reduction agent according to claim 2, characterized in that: The initiator is added under stirring conditions at 70℃~80℃.
4. The water-based drilling fluid anti-carbon dioxide contamination and filtration loss reducing agent according to claim 3, characterized in that: The initiator is a mixture of ammonium persulfate and sodium bisulfite in a molar ratio of 1:
1.
5. A method for preparing a water-based drilling fluid anti-carbon dioxide contamination filtration loss reducer according to any one of claims 1 to 4, characterized in that, This includes the following steps performed sequentially: S1. Add the monomers N'N-dimethylacrylamide, sodium p-styrenesulfonate, dimethyldiallylammonium chloride, N-vinylpyrrolidone and 2-acrylamide-2-methylpropanesulfonic acid in a molar ratio of 5:(3~8):(1~5):(0~4):(1~6) to water in sequence, and after complete dissolution, prepare solution I. S2. Add the alkaline solution to solution I, adjust the pH, and add water to obtain solution II; S3. After heating solution II, an initiator is added under stirring. After reacting for 1.5 to 3 hours, solution IV is obtained. S4. After drying and pulverizing solution IV, an anti-carbon dioxide pollution filtration loss reducer is obtained.
6. The preparation method of the anti-carbon dioxide pollution filtration reduction agent for water-based drilling fluid according to claim 5, characterized in that: The pH is adjusted to 5-6.
7. The preparation method of the water-based drilling fluid anti-carbon dioxide pollution filtration reduction agent according to claim 6, characterized in that: In step S2, when adding water, the total mass of the monomers is 20% to 30% of the total mass of solution II.
8. The preparation method of the water-based drilling fluid anti-carbon dioxide pollution filtration reduction agent according to claim 7, characterized in that: First, add ammonium persulfate from the initiator to solution II to obtain solution III; then take sodium bisulfite dissolved in deionized water and add it dropwise evenly to solution III to obtain solution IV.
9. The method for preparing the anti-carbon dioxide contamination filtration loss reducer for water-based drilling fluids according to any one of claims 6 to 8, characterized in that: The drying process is carried out at 60~100℃.