Amino polymer filtrate reducer for drilling fluid and preparation method thereof
The hyperbranched amine polymer filtration reducer, prepared by using raw materials such as acrylamide, itaconic acid, cationic monomers and hyperbranching modifiers, solves the problem of unstable performance of drilling fluid under high temperature and high salinity conditions, and improves the rheological stability and safety of drilling fluid.
Patent Information
- Application Number
- CN202411123325.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-15
- Publication Date
- 2026-03-03
AI Technical Summary
Existing amine-based filtration reducers for drilling fluids exhibit unstable performance under high temperature and high salinity conditions, resulting in large fluctuations in the rheological properties of drilling fluids, making them difficult to use in high-density drilling fluids.
Using raw materials such as acrylamide, itaconic acid, cationic monomers, and hyperbranching modifiers, an amine polymer filtration reducer with a hyperbranched structure was prepared through free radical polymerization and crosslinking reaction. Rigid naphthalene rings and sulfonic acid groups were introduced to enhance its temperature and salt resistance.
The prepared filtration loss reducer exhibits good rheological stability under high temperature and high salinity conditions, effectively reducing filtration loss and improving the safety and performance of drilling fluid.
Smart Images
Figure CN121591964A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of drilling fluid technology, and specifically relates to an amine polymer filtration reducer for drilling fluid and its preparation method. Background Technology
[0002] Due to the rapid increase in my country's demand for oil and natural gas resources and the increasing depletion of shallow-stratum oil and gas energy, the development of deep-stratum oil and gas energy is the main way out for the future development of my country's petroleum industry. Deep well and ultra-deep well drilling technology is indispensable in this process. High-temperature water-based drilling fluid technology is a key technology for drilling high-temperature deep wells and has always been a global challenge. During deep well drilling, due to the geothermal gradient, the temperature inside the lower wellbore increases with depth. In addition, the residence and circulation time of the drilling fluid downhole is also prolonged. Therefore, drilling fluid treatment must maintain good performance at high temperatures. Polymer-based filtration reducers often have a high molecular weight, and their use in low-density drilling fluids has little impact on the rheological properties of the drilling fluid. However, when used in high-density drilling fluids, the high solids content, coupled with the presence of shale formations, makes it difficult to incorporate amine polymer filtration reducers. Even with the addition of small amounts, the viscosity and shear stress of the drilling fluid increase significantly, leading to large fluctuations in its rheological properties, ultimately rendering these filtration reducers unusable. Therefore, researching amine-based filtration reducers for high-temperature drilling fluids has urgent practical significance. Summary of the Invention
[0003] To address the problem of poor temperature and salt resistance of conventional filtration loss reducers, this invention provides an amine polymer filtration loss reducer for drilling fluids and its preparation method.
[0004] An amine polymer-based filtration reducer for drilling fluids, comprising the following components by weight: 40-50 parts acrylamide, 10-15 parts itaconic acid, 5-10 parts cationic monomer, 3-5 parts hyperbranched modifier, 0.1-0.3 parts initiator, and 60-80 parts deionized water.
[0005] The cationic monomer is a quaternized polyoxyethylene ether derivative linked by amine ester bonds.
[0006] The quaternized polyoxyethylene ether derivative is selected from one of polyacrylamide, dodecylamine polyoxyethylene ether, and quaternized polyethyleneimine.
[0007] The hyperbranched modifier contains rigid naphthalene rings, sulfonic acid functional groups, and unsaturated alkenyl functional groups.
[0008] Furthermore, the preparation method of the hyperbranching modifier includes the following steps:
[0009] Step 1: Prepare the precursor fluid
[0010] N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid was mixed with tetrahydrofuran to prepare a precursor solution with a mass fraction of 20-30%.
[0011] Step 2: Preparation of hyperbranched modifier precursor
[0012] 1,4,5,8-naphthalenetetracarboxylic anhydride and tetrahydrofuran were added sequentially to the polymerization reactor. Nitrogen gas was introduced into the reactor to purge the air. The dropping rate was controlled at 2-3 mL / min. The precursor liquid was added to the polymerization reactor under continuous stirring. After the addition was complete, the mixture was stirred at room temperature for 2-4 hours. Then, the solvent was removed by vacuum evaporation. The resulting product was the hyperbranched modifier precursor.
[0013] Specifically, the 1,4,5,8-naphthalenetetracarboxylic anhydride structure contains highly active anhydride groups, which can condense with the hydroxyl groups in the N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid structure at room temperature. By controlling the dropping rate of the raw materials, the continuous linkage reaction between the two can be controlled to form a block-structured polyester hyperbranched modifier precursor.
[0014] Step 3: Preparation of hyperbranching modifier
[0015] The hyperbranching modifier precursor is added to toluene and stirred to form a homogeneous solution. Then, the alkenylating agent is added to the homogeneous solution, the temperature is raised to 60-70℃, and the phase transfer catalyst is added to the homogeneous solution. After the addition is complete and the mixture is stirred, the mixture is stirred for 1-3 hours. The solvent is removed by vacuum distillation, the material is cooled and discharged, and the obtained product is the hyperbranching modifier.
[0016] Since the precursor of the hyperbranched modifier contains a large number of carboxyl active groups generated by the condensation reaction, it can be modified by using a phase transfer catalyst and an alkenylating agent to introduce a large number of unsaturated alkenyl substituents into its structure, thereby forming a hyperbranched modifier.
[0017] Furthermore, in step three, the alkenylating agent is glycidyl methacrylate or 2,3-epoxypropyl acrylate.
[0018] Furthermore, in step three, the phase transfer catalyst is at least one of tetrabutylammonium bisulfate, tetrabutylammonium bromide, or tetramethylammonium bromide.
[0019] Furthermore, the preparation method of the cationic monomer is as follows:
[0020] Under nitrogen protection, 4-hydroxybutylvinyl polyoxyethylene ether, choline chloride and toluene are mixed evenly to form a mixture, which is then poured into a polymerization reactor. The bridging reagent and catalyst are then added to the mixture, stirred and dissolved, and the temperature is raised. When the temperature is maintained at 60-70℃, stirring is continued for 3-6 hours to evaporate and remove the solvent. The mixture is then cooled and discharged, and vacuum dried to obtain the cationic monomer.
[0021] Specifically, by utilizing the active isocyanate groups in the bridging reagent structure, 4-hydroxybutylvinyl polyoxyethylene ether is linked with choline chloride to form a quaternized polyoxyethylene ether derivative linked by amine ester bonds, i.e., a cationic monomer.
[0022] Furthermore, the 4-hydroxybutyl vinyl polyoxyethylene ether has a double bond retention rate of ≥90% and a number average molecular weight of 2000-3000.
[0023] Further, the bridging reagent is any one of toluene diisocyanate, isophenyl diisocyanate, terephthalic diisocyanate, toluene-2,4-diisocyanate, isophorone diisocyanate, 4,4'-methylenebis(phenyl isocyanate) or 4,4'-diisocyanate dicyclohexylmethane.
[0024] Furthermore, the catalyst is at least one of stannous octoate, dibutyltin diacetate, or dibutyltin dilaurate.
[0025] Furthermore, the initiator is a free radical initiator selected from ammonium persulfate, potassium persulfate, or sodium persulfate, and other substances known in the art as such reagents may also be used.
[0026] A process for manufacturing an amine polymer-based filtration reducer for drilling fluids includes the following steps:
[0027] Step 1: Preparation of linear prepolymer
[0028] Half the weight of acrylamide, itaconic acid and cationic monomer are added to deionized water and stirred until a homogeneous solution is formed. Then, the initiator is added to the homogeneous solution. Under nitrogen protection, the temperature is raised to 60-70℃ and polymerization is carried out for 2-4 hours to form a linear prepolymer.
[0029] Specifically, since acrylamide, itaconic acid, and cationic monomers all contain unsaturated active alkenyl substituents in their structures, they can undergo free radical polymerization with each other under the action of an initiator to form linear prepolymers with a straight-chain structure.
[0030] Step 2: Preparation of Filtration Loss Reducing Agent
[0031] Lower the temperature to 40-50℃, add the remaining acrylamide, itaconic acid and cationic monomer to the linear prepolymer, and add hyperbranching modifier at the same time. After the addition is complete, stir well, control the temperature at 70-80℃, and polymerize for 8-12 hours. Then cool down and discharge the material. Dry and pulverize the product to obtain the filtration loss reducer.
[0032] Adding a hyperbranching modifier to a linear prepolymer can form a cross-linked copolymer amine polymer filtration reducer with the hyperbranching modifier as the cross-linking core and the linear prepolymer as the branch chain, exhibiting a hyperbranched dendritic structure. Optimal solution
[0033] Compared with the prior art, the innovation and beneficial effects of the technical solution provided by this invention are as follows:
[0034] 1. This invention uses acrylamide and cationic monomers as raw materials to prepare a filtration loss reducing agent. Therefore, the molecular chain of the filtration loss reducing agent contains a large number of amide groups, ammonium cations, amine ester groups, and ether bonds. These structures can generate strong electrostatic adsorption and hydrogen bonding interactions with negatively charged clay particles, thereby adsorbing onto the surface of the clay particles. This results in a very strong interaction between the filtration loss reducing agent and the clay particles, which can effectively promote the multi-level dispersion of clay particles, make the colloidal particles more stable, and ultimately form a denser mud cake, thereby achieving a highly efficient filtration loss reducing effect.
[0035] 2. This invention utilizes a structure containing a rigid naphthalene ring and sulfonic acid functional groups. On one hand, the presence of the rigid naphthalene ring enables the filtration loss reducer to exhibit strong rigidity, resulting in good temperature resistance. On the other hand, the branched structure restricts the free movement of molecular chains, minimizing volume change of the molecular chains under high-temperature conditions, thereby further enhancing the temperature resistance of the filtration loss reducer. Furthermore, the extensive introduction of sulfonic acid groups significantly increases the filtration loss reducer's sensitivity to salt, enabling it to maintain stable performance under high-salt conditions and exhibiting excellent salt resistance.
[0036] 3. The hyperbranched structure of the filtration loss reducer prepared by this invention can avoid entanglement between molecular chains, greatly reduce the thickening effect, keep the performance of drilling fluid stable, reduce mine accidents, improve drilling safety, and is beneficial for practical use. Attached Figure Description
[0037] Figure 1 This is the FT-IR spectrum of the hyperbranched modifier precursor.
[0038] Figure 2 This is the FT-IR spectrum of the cationic monomer. Detailed Implementation
[0039] Example 1:
[0040] Preparation of hyperbranched modifiers:
[0041] Step 1: Prepare the precursor fluid
[0042] N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid was mixed with tetrahydrofuran to prepare a precursor solution with a mass fraction of 25%.
[0043] Step 2: Preparation of hyperbranched modifier precursor
[0044] 1.6 g of 1,4,5,8-naphthalenetetracarboxylic anhydride and tetrahydrofuran were added sequentially to the polymerization reactor. Nitrogen gas was introduced into the reactor to remove air. The dropping rate was controlled at 2 mL / min. Under continuous stirring, 6 mL of precursor liquid was added to the polymerization reactor. After the addition was complete, the mixture was stirred at room temperature for 3 h. Then, the solvent was removed by vacuum evaporation. The resulting product was the hyperbranched modifier precursor.
[0045] Figure 1 The image shows the Fourier Transform Infrared (FT-IR) spectrum of the hyperbranched modifier precursor. Analysis revealed a value at 3328 cm⁻¹. -1 The characteristic absorption peak at 3084 cm⁻¹ is attributed to the hydroxyl group OH. -1 The characteristic absorption peak at 1753 cm⁻¹ is attributed to CH on the naphthalene ring skeleton. -1 The characteristic absorption peak at 1705 cm⁻¹ is attributed to the ester group C=O produced by the condensation reaction; -1 The characteristic absorption peak at 1387 cm⁻¹ is attributed to the carboxyl group (C=O) produced by the condensation reaction. -1 The characteristic absorption peak appearing at 1202 cm⁻¹ is attributed to the S=O group of the sulfonic acid group; -1 The characteristic absorption peak appearing at this location is attributed to CN.
[0046] Step 3: Preparation of hyperbranching modifier
[0047] Add 1.5g of the hyperbranched modifier precursor to toluene and stir to form a homogeneous solution. Then add 0.4g of glycidyl methacrylate to the homogeneous solution, raise the temperature to 65℃, and continue to add 0.1g of tetramethylammonium bromide to the homogeneous solution. After the addition is complete, stir well and continue stirring for 2 hours. Remove the solvent by vacuum distillation, cool down and discharge the material. The result is the hyperbranched modifier.
[0048] The infrared spectrum of the hyperbranched modifier is as follows: Figure 1 As shown, 3424cm -1 A hydroxyl stretching vibration peak, attributed to the ring-opening reaction, appeared at 3008 cm⁻¹. -1 A new CH stretching vibration peak, at 1737 cm⁻¹, was observed, attributed to the unsaturated carbon-carbon double bond. -1A new C=O stretching vibration peak belonging to the ester group appeared at 1705 cm⁻¹, which was originally attributed to the peak at 1705 cm⁻¹. -1 The stretching vibration peak of the carboxyl group C=O disappeared.
[0049] Example 2:
[0050] Preparation of cationic monomers:
[0051] Under nitrogen protection, 4-hydroxybutylvinyl polyoxyethylene ether, choline chloride, and toluene are mixed evenly to form a mixture, which is then poured into a polymerization reactor. Toluene-2,4-diisocyanate and dibutyltin dilaurate are then added to the mixture and stirred until dissolved. The temperature is then raised and maintained at 60-70°C. After stirring continuously for 3-6 hours, the solvent is evaporated and removed. The mixture is then cooled and discharged, and vacuum dried to obtain the cationic monomer.
[0052] The double bond retention rate of 4-hydroxybutylvinyl polyoxyethylene ether is 93%, and the number average molecular weight is 3000.
[0053] Figure 2 The following is the (FT-IR) infrared spectrum of the cationic monomer. Analysis showed that the value at 3289 cm⁻¹... -1 The characteristic absorption peak at 1679 cm⁻¹ is attributed to the NH group of the amine ester bond; -1 The characteristic absorption peak at 1422 cm⁻¹ is attributed to the C=O of the amine ester bond. -1 The characteristic absorption peak appearing at 1104 cm⁻¹ is attributed to CN of the quaternary ammonium salt functional group. -1 The characteristic absorption peak appearing at this point is attributed to the ether bond CO.
[0054] Example 3:
[0055] An amine polymer-based fluid loss reducer for drilling fluids comprises, by weight, the following components: 40 parts acrylamide, 10 parts itaconic acid, 5 parts cationic monomer, 3 parts hyperbranching modifier, 0.1 parts potassium persulfate initiator, and 60 parts deionized water.
[0056] The preparation method of the filtration loss reducing agent includes the following steps:
[0057] Step 1: Preparation of linear prepolymer
[0058] Half the weight of acrylamide, itaconic acid and cationic monomer are added to deionized water and stirred until a homogeneous solution is formed. Then, potassium persulfate initiator is added to the homogeneous solution. Under nitrogen protection, the temperature is raised to 60°C and polymerization is carried out for 2 hours to form a linear prepolymer.
[0059] Step 2: Preparation of Filtration Loss Reducing Agent
[0060] Lower the temperature to 40℃, add the remaining acrylamide, itaconic acid and cationic monomer to the linear prepolymer, and add hyperbranching modifier at the same time. After the addition is complete, stir well, control the temperature at 70℃, and polymerize for 8 hours. Then cool down and discharge the material. Dry and pulverize the product to obtain the filtration loss reducer.
[0061] Example 4:
[0062] An amine polymer-based filtration reducer for drilling fluids comprises, by weight, the following components: 45 parts acrylamide, 12 parts itaconic acid, 8 parts cationic monomer, 4 parts hyperbranched modifier, 0.2 parts potassium persulfate initiator, and 70 parts deionized water.
[0063] The preparation method of the filtration loss reducing agent includes the following steps:
[0064] Step 1: Preparation of linear prepolymer
[0065] Half the weight of acrylamide, itaconic acid and cationic monomer are added to deionized water and stirred until a homogeneous solution is formed. Then, potassium persulfate initiator is added to the homogeneous solution. Under nitrogen protection, the temperature is raised to 65°C and polymerization is carried out for 3 hours to form a linear prepolymer.
[0066] Step 2: Preparation of Filtration Loss Reducing Agent
[0067] Lower the temperature to 45℃, add the remaining acrylamide, itaconic acid and cationic monomer to the linear prepolymer, and add hyperbranching modifier at the same time. After the addition is complete, stir well, control the temperature at 75℃, and polymerize for 9 hours. Then cool down and discharge the material. Dry and pulverize the product to obtain the filtration loss reducer.
[0068] Example 5:
[0069] An amine polymer-based fluid loss reducer for drilling fluids comprises, by weight, the following components: 50 parts acrylamide, 15 parts itaconic acid, 10 parts cationic monomer, 5 parts hyperbranched modifier, 0.3 parts potassium persulfate initiator, and 80 parts deionized water.
[0070] The preparation method of the filtration loss reducing agent includes the following steps:
[0071] Step 1: Preparation of linear prepolymer
[0072] Half the weight of acrylamide, itaconic acid and cationic monomer are added to deionized water and stirred until a homogeneous solution is formed. Then, potassium persulfate initiator is added to the homogeneous solution. Under nitrogen protection, the temperature is raised to 70°C and polymerization is carried out for 4 hours to form a linear prepolymer.
[0073] Step 2: Preparation of Filtration Loss Reducing Agent
[0074] Lower the temperature to 50℃, add the remaining acrylamide, itaconic acid and cationic monomer to the linear prepolymer, and add hyperbranching modifier at the same time. After the addition is complete, stir well, control the temperature at 80℃, polymerize for 12 hours, cool down and discharge the material, dry and pulverize the product to obtain the filtration loss reducer.
[0075] Comparative Example 1:
[0076] An amine polymer-based fluid loss reducer for drilling fluids comprises, by weight, the following components: 45 parts acrylamide, 12 parts itaconic acid, 8 parts cationic monomer, 0.2 parts potassium persulfate initiator, and 70 parts deionized water.
[0077] The preparation method of the filtration loss reducing agent includes the following steps:
[0078] Acrylamide, itaconic acid, and cationic monomers are added to deionized water and stirred until a homogeneous solution is formed. Then, potassium persulfate, the initiator, is added to the homogeneous solution. Under nitrogen protection, the temperature is raised to 70°C and polymerization is carried out for 9 hours to obtain the filtration loss reducer.
[0079] Comparative Example 2:
[0080] An amine polymer-based fluid loss reducer for drilling fluids comprises, by weight, the following components: 45 parts acrylamide, 12 parts itaconic acid, 4 parts hyperbranching modifier, 0.2 parts potassium persulfate initiator, and 70 parts deionized water.
[0081] The preparation method of the filtration loss reducing agent includes the following steps:
[0082] Step 1: Preparation of linear prepolymer
[0083] Half the weight of acrylamide and itaconic acid were added to deionized water and stirred until a homogeneous solution was formed. Then, potassium persulfate, the initiator, was added to the homogeneous solution. Under nitrogen protection, the temperature was raised to 65°C and polymerization was carried out for 3 hours to form a linear prepolymer.
[0084] Step 2: Preparation of Filtration Loss Reducing Agent
[0085] Lower the temperature to 45℃, add the remaining acrylamide and itaconic acid to the linear prepolymer, and add the hyperbranching modifier at the same time. After the addition is complete, stir well, control the temperature at 75℃, and polymerize for 9 hours. Then, cool down and discharge the material. Dry and pulverize the product to obtain the filtration loss reducer.
[0086] Experimental Example 1:
[0087] According to the national standard GB / T 16783.1-2006, the temperature and salt resistance properties of the filtration loss reducing agents prepared in Examples 3-5 and Comparative Examples 1 and 2 were tested. The preparation method for the freshwater-based slurry was as follows: 18g bentonite, 1g sodium carbonate, and 15g filtration loss reducing agent were added to 500g water, mixed at a stirring rate of 1000r / min for 20min, and then allowed to stand for 24h. After curing, the slurry was ready. The preparation method for the brine-based slurry was as follows: 18g bentonite, 1g sodium carbonate, 120g sodium chloride, and 15g filtration loss reducing agent were added to 500g water, mixed at a stirring rate of 1000r / min for 20min, and then allowed to stand for 24h. After curing, the slurry was ready.
[0088] The test results are recorded in Table 1:
[0089] Table 1 Test Results
[0090]
[0091] Analysis and test results show that the filtration loss reducer prepared using hyperbranched modifier and cationic monomer as raw materials has a significantly better filtration loss reduction effect and excellent temperature and salt resistance.
[0092] In contrast, Comparative Example 1, due to the absence of hyperbranched modifiers as raw materials, resulted in the preparation of a filtration loss reducer that did not contain rigid naphthalene rings and sulfonic acid groups and exhibited a straight-chain structure. Therefore, its resistance to temperature and salt was poor. However, due to the addition of cationic monomers, its filtration loss reduction effect in freshwater-based slurry was acceptable.
[0093] Comparative Example 2 did not add a cationic monomer, resulting in the absence of quaternary ammonium cations in the structure of the prepared filtration loss reducer. Although it exhibited good temperature and salt resistance, its filtration loss reduction effect was only average.
Claims
1. An amine polymer filtration reducer for drilling fluids, characterized in that, It is made from the following components in parts by weight: Acrylamide 40-50 parts, itaconic acid 10-15 parts, cationic monomer 5-10 parts, hyperbranching modifier 3-5 parts, initiator 0.1-0.3 parts, deionized water 60-80 parts.
2. The drilling fluid amine polymer filtration reducer according to claim 1, characterized in that, By weight, the acrylamide is preferably 43-47 parts, the itaconic acid is preferably 11.5-13.5 parts, the cationic monomer is preferably 6.5-8.5 parts, the hyperbranching modifier is preferably 3.5-4.5 parts, the initiator is preferably 0.15-0.25 parts, and the deionized water is preferably 65-75 parts.
3. The drilling fluid amine polymer filtration reducer according to claim 1 or 2, characterized in that, The cationic monomer is a quaternized polyoxyethylene ether derivative linked by an amine ester bond.
4. The drilling fluid amine polymer filtration reducer according to claim 1 or 3, characterized in that, The quaternized polyoxyethylene ether derivative is selected from one of polyacrylamide, dodecylamine polyoxyethylene ether, and quaternized polyethyleneimine.
5. The drilling fluid amine polymer filtration reducer according to claim 1, characterized in that, The preparation method of the hyperbranched modifier includes the following steps: SS1: Mix N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid with tetrahydrofuran to prepare a precursor solution with a mass fraction of 20-30%. SS2: Under inert gas protection, the precursor liquid is added dropwise to a mixture of 1,4,5,8-naphthalenetetracarboxylic anhydride and tetrahydrofuran for reaction, and the solvent is removed to obtain the hyperbranched modifier precursor. SS3: The hyperbranched modifier precursor is added to toluene to form a homogeneous solution. The alkenylating agent is added to the homogeneous solution, and a phase transfer catalyst is added to carry out the reaction. The solvent is removed to obtain the hyperbranched modifier.
6. The drilling fluid amine polymer filtration reducer according to claim 5, characterized in that, The SS3 alkenylating agent is one of glycidyl methacrylate and 2,3-epoxypropyl acrylate.
7. The drilling fluid amine polymer filtration reducer according to claim 5 or 6, characterized in that, The SS3 phase transfer catalyst is at least one of tetrabutylammonium bisulfate, tetrabutylammonium bromide, and tetramethylammonium bromide.
8. The drilling fluid amine polymer filtration reducer according to claim 1, characterized in that, The initiator is ammonium persulfate, potassium persulfate, or sodium persulfate.
9. The method for preparing the drilling fluid amine polymer filtration reducer according to any one of claims 1-8, characterized in that, Includes the following steps: S1: Add half the weight of acrylamide, itaconic acid and cationic monomer to deionized water, mix well and then add initiator. React under inert gas protection to obtain linear prepolymer. S2: Add the remaining acrylamide, itaconic acid and cationic monomer to the linear prepolymer, add hyperbranching modifier to react, and obtain the filtration loss reducer.
10. The method for preparing the drilling fluid amine polymer filtration reducer according to claim 9, characterized in that, The preparation method of the S1 cationic monomer includes the following steps: under the protection of an inert gas, 4-hydroxybutylvinyl polyoxyethylene ether, choline chloride and toluene are mixed evenly, bridging reagent and catalyst are added to the mixture to react, solvent is removed, and cationic monomer is obtained.
11. The method for preparing the drilling fluid amine polymer filtration reducer according to claim 9 or 10, characterized in that, The 4-hydroxybutyl vinyl polyoxyethylene ether has a double bond retention rate of ≥90% and a number average molecular weight of 2000-3000.
12. The method for preparing the drilling fluid amine polymer filtration reducer according to claim 9 or 10, characterized in that, The bridging reagent is any one of toluene diisocyanate, isophenyl diisocyanate, terephthalic diisocyanate, toluene-2,4-diisocyanate, isophorone diisocyanate, 4,4'-methylenebis(phenyl isocyanate), and 4,4'-diisocyanate dicyclohexylmethane.
13. The method for preparing the drilling fluid amine polymer filtration reducer according to claim 9 or 10, characterized in that, The catalyst is at least one of stannous octoate, dibutyltin diacetate, and dibutyltin dilaurate.