Functional monomer for preparing hyperbranched filtrate reducer for drilling fluid, hyperbranched filtrate reducer for drilling fluid as well as preparation method and application of hyperbranched filtrate reducer

Abstract

The invention discloses a functional monomer for preparing a hyperbranched filtrate reducer for a drilling fluid, the hyperbranched filtrate reducer for the drilling fluid as well as a preparation method and application of the hyperbranched filtrate reducer, and belongs to the field of petroleum additives. The preparation method of the hyperbranched filtrate reducer comprises the following steps: by taking a boryl compound as a reducing agent, introducing an alkenyl group into hyperbranched polyethyleneimine molecules to generate a functional monomer, and then copolymerizing with alkenyl amide and alkenyl sulfonic acid to obtain a crude product of the hyperbranched filtrate reducer; and precipitating, washing, extracting and vacuum-drying the crude product to obtain the hyperbranched filtrate reducer for the drilling fluid. The hyperbranched structure of the hyperbranched filtrate reducer improves the molecular rigidity, reduces the thermal motion degree of molecules under a high temperature condition and the molecular chain curling degree caused by high calcium ion concentration, and shows good temperature and calcium resistance.

Description

Technical Field

[0001] This invention relates to the field of petroleum additives, and more particularly to a functional monomer for preparing hyperbranched filtration loss reducers for drilling fluids, the hyperbranched filtration loss reducer for drilling fluids, its preparation method, and its application. Background Technology

[0002] During drilling, drilling fluids possess properties such as carrying and suspending rock cuttings, cooling and lubricating the drill bit, maintaining wellbore stability, and transmitting geological information. With the depletion of conventional oil and gas resources and the increasing deployment of deep and ultra-deep wells, ensuring the effectiveness of drilling fluids in complex bottomhole environments such as high temperature, high pressure, high salinity, and high calcium content significantly impacts drilling efficiency. Filtration performance is one of the most important performance indicators of drilling fluids, directly affecting wellbore stability, reservoir protection, rate of drilling (ROD), cementing, and logging. Filtration reducers are key agents for improving the filtration and wellbore-building properties of drilling fluids.

[0003] Currently, drilling fluid filtration reducers mainly include naturally modified products (such as modified starch and modified cellulose) and synthetic polymers. Considering temperature resistance, synthetic polymer filtration reducers are more widely used in deep wells and are also the most extensively studied type of filtration reducer. For example, the article "Preparation and Performance Study of High-Temperature Resistant Filtration Reducers" published in Volume 35, Issue 6 of "Drilling Fluids and Completion Fluids" in 2018 introduced a drilling fluid filtration reducer PAANS with a benzene ring structure in the molecular backbone, prepared by using acrylamide (AM), 2-methyl-2-acrylamidopropanesulfonic acid (AMPS), N-vinylpyrrolidone (NVP), and sodium 4-hydroxybenzenesulfonate (SHBS) as monomers and horseradish peroxidase (HRP) as a catalyst via an enzymatic reaction method. At an addition of 2.0%, after aging at 220℃ for 16 hours, the high-temperature and high-pressure filtration loss of the drilling fluid was only 24.0 mL, and it also had certain salt and calcium resistance.

[0004] The journal "Drilling Fluids and Completion Fluids" published an article titled "Preparation and Application of High-Temperature and High-Calcium Comb-Type Filtration Loss Reducer" in Volume 39, Issue 4, 2022. The article introduces a comb-type polymer filtration loss reducer, WA-1, which is synthesized using AMPS, dimethyl diallyl ammonium chloride (DMDAAC), NVP, and N,N-dimethylacrylamide (DMAA) as monomers and potassium persulfate as an initiator. It is resistant to temperatures up to 180℃ and can control the filtration loss of 2.0% CaCl2-based slurry at room temperature under medium pressure to within 11.2 mL, exhibiting superior filtration performance compared to linear polymer filtration loss reducers.

[0005] This shows that increasing the branching degree of polymer-based filtration loss reducers can increase molecular rigidity, reduce the degree of molecular chain entanglement and coiling, promote the extension of regular macromolecular chains to have a larger hydrodynamic volume and repulsive effect, and effectively improve their filtration loss reduction effect under high temperature and high calcium conditions.

[0006] Current trends in the development of improved polymer-based fluid loss reducers show that product modification and upgrading primarily focus on optimizing the combination of functional groups in linear polymer molecules. Research on improving temperature and calcium resistance by increasing the hyperbranching degree of polymer-based fluid loss reducer molecules is relatively limited. Therefore, this invention, based on the unique structure and properties of hyperbranched polymers, aims to prepare a fluid loss reducer suitable for drilling fluids. Summary of the Invention

[0007] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, and such simplifications or omissions should not be construed as limiting the scope of the invention.

[0008] The primary objective of this invention is to overcome the problem of weak calcium resistance in existing drilling fluid filtration reducers under high-temperature conditions, and to provide a functional monomer for preparing hyperbranched filtration reducers for drilling fluids. The hyperbranched structure improves molecular rigidity, reduces the degree of thermal motion of molecules under high-temperature conditions and the degree of molecular chain coiling caused by high calcium ion concentration, and exhibits good temperature and calcium resistance.

[0009] To address the above technical problems, this invention provides a functional monomer for preparing hyperbranched filtration reduction agents for drilling fluids. The central group of its molecular structure is a hyperbranched polyethyleneimine group, and the ends of the molecular structure include -NH2 and the structure shown in formula i.

[0010]

[0011] In formula i, R1, R2, and R3 are independently selected from H, C1-C6 alkyl, and cycloalkyl;

[0012] In formula i, n represents the number of CH2- structural units, which is a natural number from 0 to 18.

[0013] Furthermore, n is a natural number from 0 to 6.

[0014] Furthermore, n can be 0, 1, 2, or 3.

[0015] The second objective of this invention is to overcome the problem that existing drilling fluid filtration reducers have weak calcium resistance under high temperature conditions, and to provide a method for preparing a functional monomer for preparing a hyperbranched filtration reducer for drilling fluid. The hyperbranched structure of the functional monomer improves molecular rigidity, reduces the degree of thermal motion of molecules under high temperature conditions and the degree of molecular chain curling caused by high calcium ion concentration, and exhibits good temperature and calcium resistance.

[0016] To address the above technical problems, this invention provides a method for preparing a functional monomer for a hyperbranched filtration reduction agent used in drilling fluids, which is synthesized using hyperbranched polyethyleneimine and an aldehyde compound of formula ii as raw materials.

[0017]

[0018] The synthesis method includes: reacting hyperbranched polyethyleneimine and an aldehyde compound of formula ii in the presence of a reducing agent to obtain a functional monomer for preparing a hyperbranched filtration reducer for drilling fluids;

[0019] In formula ii, R 1 R 2 R 3 It is independently selected from one of H, C1-C6 alkyl, and cycloalkyl;

[0020] In equation ii, n represents the number of CH2- structural units, which is a natural number from 0 to 18.

[0021] Furthermore, n is a natural number from 0 to 6.

[0022] Furthermore, n can be 0, 1, 2, or 3.

[0023] Furthermore, the relative molecular mass M of the hyperbranched polyethyleneimine is 1500–25000 g / mol.

[0024] Furthermore, the relative molecular mass M of the hyperbranched polyethyleneimine is 2000–10000 g / mol.

[0025] Furthermore, the relative molecular mass M of the hyperbranched polyethyleneimine is 2041 g / mol, 8754 g / mol, 9980 g / mol, 2875 g / mol, 5077 g / mol, or 6892 g / mol.

[0026] Furthermore, the structural formula of the hyperbranched polyethyleneimine is shown in I':

[0027]

[0028] Furthermore, as shown in Formula I', the relative molecular mass of the hyperbranched polyethyleneimine is 2041 g / mol, and the ratio of primary amine: secondary amine: tertiary amine in the molecule is 20:10:18. This means that the number of primary amine groups, i.e., terminal amine groups, in the single molecule of the hyperbranched polyethyleneimine is 20, the number of secondary amine groups is 10, and the number of tertiary amine groups is 18.

[0029] Furthermore, the steps are as follows:

[0030] Step 1: Mix hyperbranched polyethyleneimine, aldehyde compound of formula ii and solvent evenly, and control the temperature to 10-50℃ to obtain reaction solution A;

[0031] Step 2: In a protective atmosphere, add a pH adjuster to adjust the pH value to 2-6 in reaction solution A, then add a reducing agent. The reaction is carried out at a controlled temperature of 10-50℃ for 16-60 hours to obtain reaction solution B.

[0032] Step 3: Post-process the reaction solution B, which includes adding saturated sodium bicarbonate to adjust the pH to 8.5 under ventilation, removing the reducing agent, and then performing vacuum distillation, dialysis to remove impurities, and recrystallization to obtain the functional monomer for preparing the hyperbranched filtration reducer for drilling fluid.

[0033] Furthermore, in step 1:

[0034] The molar ratio of the hyperbranched polyethyleneimine to the aldehyde compound shown in Formula ii is 1:(0.2~2), wherein the molar amount of the hyperbranched polyethyleneimine is calculated based on the molar amount of its molecular structure terminal -NH2.

[0035] The total mass percentage of hyperbranched polyethyleneimine and aldehyde compounds of formula ii in the solvent is 2% to 20%.

[0036] The solvent is selected from organic solvents, and is at least one of methanol, ethanol, N,N-dimethylformamide or N,N-dimethylacetamide.

[0037] Furthermore, in step 1: the total mass percentage of the hyperbranched polyethyleneimine and the aldehyde compound of formula ii in the solvent is 5% to 10%.

[0038] The molar ratio of the hyperbranched polyethyleneimine to the aldehyde compound shown in Formula ii is 1:(0.3 to 0.7).

[0039] Furthermore, in step 2:

[0040] The pH adjuster is an organic acid, used to adjust the pH value to 3-4;

[0041] The reducing agent is selected from borohydrides, and the molar ratio of the reducing agent to the aldehyde compound shown in formula (ii) is (1-2.5):1; the reaction is carried out at a controlled temperature of 20-30°C for a reaction time of 20-40 h.

[0042] Furthermore, in step 2:

[0043] The pH adjuster is acetic acid, and the reducing agent is NaBH4 or NaBH3CN; the molar ratio of the reducing agent to the aldehyde compound shown in formula (ii) is (1-1.5):1.

[0044] Furthermore, in step 3: the crude product obtained after vacuum distillation is added to a dialysis bag to remove the reducing agent and unreacted substances. The molecular weight cutoff of the dialysis bag is 200-1800 Da.

[0045] The dialysis to remove impurities is performed in ethanol for 24–48 hours;

[0046] The specific steps of recrystallization include: adding the crude product to methanol, dissolving it at 60°C to prepare a 20% solution, cooling it to -16°C to precipitate the solid, filtering, washing, and drying to constant weight.

[0047] Furthermore, in step 3: the molecular weight cutoff of the dialysis bag used is 400-800 Da.

[0048] The third objective of this invention is to overcome the problem that existing drilling fluid filtration reducers have weak calcium resistance under high temperature conditions, and to provide a hyperbranched filtration reducer for drilling fluids. The hyperbranched structure improves molecular rigidity, reduces the degree of thermal motion of molecules under high temperature conditions and the degree of molecular chain curling caused by high calcium ion concentration, and exhibits good temperature and calcium resistance.

[0049] To solve the above technical problems, the present invention provides a hyperbranched filtration reducer for drilling fluid, which contains structural unit A shown in Formula I, structural unit B shown in Formula II, and a third structural unit C.

[0050]

[0051] The third structural unit C is the functional monomer for preparing hyperbranched filtration reduction agent for drilling fluid as described in claim 1;

[0052] The molar ratio of structural unit A, structural unit B, and structural unit C is (20–50):(10–25):(8–15); the molar amount of structural unit C is determined by the molecular end of its structure. Molarity meter;

[0053] In Formula I, R1 is selected from H or C1-C6 alkyl groups;

[0054] R2 is selected from in,

[0055] R a and R b Each is independently selected from one of -H, C1-C6 alkyl groups, C1-C6 alkyl alcohols, and C1-C8 alkyl ketones;

[0056] R c Selected from -H or C1-C6 alkyl groups;

[0057] R d Selected from —CH3, —CH2CH3, One of them;

[0058] In Formula II, R3 is selected from -H or C1-C6 alkyl groups; R4 is selected from... One of them.

[0059] Furthermore, for R4: A is selected from at least one of H, Na, K, Rb or Cs, j, k, l are independently selected as integers from 0 to 3; m, n are natural numbers from 4 to 14.

[0060] The fourth objective of this invention is to overcome the problem that existing drilling fluid filtration reducers have weak calcium resistance under high temperature conditions, and to provide a method for preparing a hyperbranched filtration reducer for drilling fluids. The hyperbranched structure improves molecular rigidity, reduces the degree of thermal motion of molecules under high temperature conditions and the degree of molecular chain curling caused by high calcium ion concentration, and exhibits good temperature and calcium resistance.

[0061] To solve the above technical problems, the present invention provides a method for preparing a hyperbranched filtration loss reducing agent for drilling fluids, comprising the following steps in sequence:

[0062] Step 1: Mix and stir structural unit A, structural unit B and third structural unit C in a solvent in sequence and heat to a predetermined temperature of 40-105℃;

[0063] Step 2: After purging with nitrogen for 30 minutes, add the initiator to the above mixed solution and continue the reaction under stirring for 12-24 hours to obtain the crude product of the filtration loss reducer.

[0064] Step 3: The crude product is subjected to precipitation, washing, extraction, and vacuum drying to obtain the finished product of hyperbranched filtration reducer for drilling fluid.

[0065] Furthermore, the mass percentage concentrations of the monomers of structural unit A, structural unit B, and third structural unit C in the solvent are 8.0% to 16.0%.

[0066] The solvent is one or more of the following: water, acetone, butanone, chloroform, dichloromethane, 1,1-dichloroethane, 1,2-dichloroethane, methyl ethyl ketone, tetrahydrofuran, petroleum ether, diethyl ether, acetonitrile, ethyl acetate, benzene, toluene, m-xylene, cyclohexane, ethylene glycol dimethyl ether, nitromethane, 1,4-dioxane, pyridine, morpholine, 4-methyl-2-pentanone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

[0067] The predetermined temperature in step 1 is 44–104°C;

[0068] The initiator in step 2 is one or more of the following: azo initiators, organic peroxide initiators, inorganic peroxide initiators, and oil-soluble redox initiators; the amount of initiator added is 0.5% to 2.0% of the total weight of the three monomers.

[0069] Furthermore, the azo initiator is one or more of the following: azobisisobutyrazoline hydrochloride, azoisobutyronitrile, azobisisobutyronitrile, azobiscarboxyethyl-2-isobutylamidine hydrate, azodimethyl N-2-hydroxybutylacrylamide, azobiscyclohexylformitrile, azobisisovaleritrile, azobisisoheptanenitrile, azobiscyanopentanoic acid, azobisisobutyronitrile hydrochloride, azobisisopropylimidazoline, azobisN-hydroxyisobutylamidine hydrate, azobisN,N'-cyclobutylisobutylamidine hydrate, dimethyl azobisisobutyrate, and 2,2'-azobis(N-cyclohexylisobutylamidine) hydrochloride.

[0070] The fifth objective of this invention is to overcome the problem that existing drilling fluid filtration reducers have weak calcium resistance under high temperature conditions, and to provide an application of a hyperbranched filtration reducer for drilling fluids. The hyperbranched structure improves molecular rigidity, reduces the degree of thermal motion of molecules under high temperature conditions and the degree of molecular chain curling caused by high calcium ion concentration, and exhibits good temperature and calcium resistance.

[0071] To solve the above technical problems, the present invention provides an application of a hyperbranched filtration reducer for drilling fluids. The hyperbranched filtration reducer is applied to water-based drilling fluids in the petroleum engineering field, with the dosage of the hyperbranched filtration reducer being 0.2 wt% to 2.0 wt%. The water-based drilling fluid is a bentonite drilling fluid system, a potassium amine-based drilling fluid system, a polymer anti-collapse drilling fluid system, a sulfonated drilling fluid system, a polysulfonated drilling fluid system, a KCl drilling fluid system, a brine drilling fluid system, or a silicate drilling fluid system.

[0072] Compared to the prior art, the advantages or beneficial effects of the embodiments of this application include at least the following:

[0073] 1. Hyperbranched structural units can more effectively improve the rigidity of polymer molecular chains, reduce the degree of thermal motion of molecules under high temperature conditions, and improve the hydrodynamic volume and steric hindrance of the filtration loss reducer molecular chains, thereby helping to improve the filtration loss reduction effect under high temperature conditions.

[0074] 2. The hyperbranched filtration loss reducer provided in this application has a hyperbranched network structure that can effectively reduce Ca2+ filtration loss. 2+ The degree of molecular chain coiling caused by ions plays a positive role in improving the filtration loss reduction effect of filtration loss reducers in high-calcium drilling fluids.

[0075] 3. The hyperbranched filtration reducer applied to water-based drilling fluids exhibits superior calcium resistance at 160℃ compared to conventional linear polymer filtration reducers. Attached Figure Description

[0076] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The drawings are provided for reference and illustration only and are not intended to limit the present invention.

[0077] in:

[0078] Figure 1 It is the functional monomer obtained in Example 1 1 H NMR spectrum;

[0079] Figure 2 It is the hyperbranched filtration reducer obtained in Example 11. 1 H NMR spectrum. Detailed Implementation

[0080] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0081] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0082] Substances and parameters not specified in this application may be selected based on existing technology and are considered conventional technical means in this field.

[0083] In this application, C1 to C6 refer to the number of carbon atoms contained in the group.

[0084] In this application, the term "alkyl" refers to a group formed by the loss of any one hydrogen atom from an alkane molecule.

[0085] In this application, the term "cyclic group" refers to a cyclic group formed by the loss of one hydrogen atom from each end of an alkane compound molecular chain and their subsequent bonding.

[0086] In this application, the term "phenyl" refers to a group with a benzene ring as its functional group.

[0087] The present application is further described below with reference to embodiments. However, the present application is not limited to these embodiments.

[0088] Unless otherwise specified, the reactors, vacuum distillation apparatuses, etc. used in the embodiments of this application are all commercially available products.

[0089] Unless otherwise specified, all chemical reagents used in the embodiments of this application are commercially available products.

[0090] The functional monomer monomolecule structure in the embodiments of this application The quantity is determined by the following method: First, the quantity of -NH2 at the end of the monomolecular structure is determined by potentiometric titration (the result is rounded to the nearest integer), which gives the quantity of -NH2 at the end of the monomolecular structure that has not been reduced. Then, the quantity of -NH2 at the end of the monomolecular structure that has not been reduced is obtained by subtracting the quantity of -NH2 at the end of the monomolecular structure from the quantity of -NH2 at the end of the hyperbranched polyethyleneimine monomolecular structure.

[0091] In this embodiment of the application, the yield calculation formula for the functional monomer is as follows:

[0092] Wherein, R—the yield of the functional monomer;

[0093] H0—Theoretical mass of the functional monomer;

[0094] H1 — Measured mass of the functional monomer (mass of the functional monomer after recrystallization).

[0095] In the following examples, hyperbranched polyethyleneimine is used This indicates that —NH2 represents the amino group at the end of the hyperbranched polyethyleneimine molecule.

[0096] For example, 0.2 mol of hyperbranched polyethyleneimine (with 20 amino groups at the monomolecular end), 2.4 mol of the aldehyde compound shown in formula (ii), and the molar ratio of hyperbranched polyethyleneimine to the aldehyde compound shown in formula (ii) is 1:0.6.

[0097] For example, 0.3 mol of alkenylamide, 0.15 mol of alkenylsulfonic acid, and 0.01 mol of functional monomer (monoterminal) The number of alkenylamides, alkenylsulfonic acids and functional monomers is 10, and the molar ratio of alkenylamides, alkenylsulfonic acids and functional monomers is 30:15:10.

[0098] Example 1:

[0099] Preparation of functional monomers

[0100] 408.2 g (0.2 mol) of hyperbranched polyethyleneimine (M = 2041 g / mol, primary amine: secondary amine: tertiary amine = 20:10:18) and 235.56 g (2.4 mol) of 4-methyl-3-pentenal (R) were added to the reactor. 1 and R 2 Both are CH3, R 3 The reaction mixture (H, n=1) and 10000 mL of methanol were stirred and heated to 25 °C. Under N2 protection, HAc was added to the above reaction solution until the pH reached 3.5, followed by the addition of 188.52 g (3 mol) of NaBH3CN. The reaction was continued for 24 h with stirring. Under ventilation, saturated sodium bicarbonate was added to adjust the pH to 8.5 to remove the reducing agent. The methanol was removed by vacuum distillation, and the mixture was placed in a dialysis bag (molecular weight cutoff 600 Da) and purified by dialyzing in ethanol solution for 36 h to obtain the crude product.

[0101] The crude product was dissolved in methanol at 60°C to prepare a 20% solution. The solution was then cooled to -16°C for recrystallization, resulting in the precipitation of a pale yellow solid. This solid was filtered, rinsed with acetone and methanol respectively, and dried to constant weight; this was the functional monomer, denoted as G1, the unimolecular terminator. The number was 10, and the yield was 75.92%.

[0102] The chemical reaction formula is shown below:

[0103]

[0104] G1 was characterized by nuclear magnetic resonance [(CD3)2SO, 25℃], and its magnetic resonance spectrum was obtained. 1 H NMR) such as Figure 1 .according to 1 The H NMR analysis results are consistent with the molecular structure of the target product.

[0105] Example 2:

[0106] Preparation of functional monomers

[0107] 875.4 g (0.1 mol) of hyperbranched polyethyleneimine (M = 8754 g / mol, primary amine: secondary amine: tertiary amine = 50:17:29) and 441.7 g (3.5 mol) of 5-methyl-5-heptenal (R) were added to the reactor. 1 For H, R 2 and R 3 The reaction mixture (all CH3, n=3) and 12500 mL DMF were stirred and heated to 30 °C. Under N2 protection, HAc was added to the above reaction solution until the pH reached 3, followed by the addition of 263.928 g (4.2 mol) NaBH3CN. The reaction was continued for 20 h with stirring. Under aeration, saturated sodium bicarbonate was added to adjust the pH to 8.5 to remove the reducing agent. The mixture was then distilled under reduced pressure to remove DMF, and the solution was placed in a dialysis bag (molecular weight cutoff 800 Da) and purified by dialysis in ethanol solution for 24 h to obtain the crude product.

[0108] The crude product was dissolved in methanol at 60°C to prepare a 20% solution. The solution was then cooled to -16°C for recrystallization, resulting in the precipitation of a pale yellow solid. This solid was filtered, rinsed with acetone and methanol respectively, and dried to constant weight; this was the functional monomer, denoted as G2, unimolecularly terminal. The number was 28, and the yield was 71.03%.

[0109] The chemical reaction formula is shown below:

[0110]

[0111] Example 3:

[0112] Preparation of functional monomers

[0113] 998 g (0.1 mol) of hyperbranched polyethyleneimine (M = 9980 g / mol, primary amine: secondary amine: tertiary amine = 60:21:44) and 100.908 g (1.8 mol) of acrolein (R) were added to the reactor. 1 R 2 and R 3 The reaction mixture (all H, n=0) and 22280 mL of DMA were stirred and the temperature was controlled at 20 °C. Under N2 protection, HAc was added to the above reaction solution until the pH was 4, and then 113.112 g (1.8 mol) of NaBH3CN was added. The reaction was continued for 40 h under stirring. Under ventilation, saturated sodium bicarbonate was added to adjust the pH to 8.5 to remove the reducing agent. The DMA was removed by vacuum distillation, and the mixture was placed in a dialysis bag (molecular weight cutoff 800 Da) and purified by dialyzing in ethanol solution for 48 h to obtain the crude product.

[0114] The crude product was dissolved in methanol and prepared into a 20% solution at 60°C. The solution was then cooled to -16°C for recrystallization, resulting in the precipitation of a pale yellow solid. The solid was filtered, rinsed with acetone and methanol respectively, and dried to constant weight. This solid was the functional monomer, denoted as G3. The number of -CH2-CH=CH2 terminals on the monomer was 16, and the yield was 67.85%.

[0115] The chemical reaction formula is shown below:

[0116]

[0117] Example 4:

[0118] Preparation of functional monomers

[0119] 287.5 g (0.1 mol) of hyperbranched polyethyleneimine (M = 2875 g / mol, primary amine: secondary amine: tertiary amine = 24:12:21) and 151.44 g (1.2 mol) of 4-methyl-4-hexenal (R) were added to the reactor. 1 R 2 and R 3 The mixture consisted of CH3 (n=2) and 6000 mL of ethanol. The temperature was controlled at 24°C with stirring. Under N2 protection, HAc was added to the reaction solution until the pH reached 3, followed by the addition of 113.112 g (1.8 mol) of NaBH3CN. The reaction was continued for 32 h with stirring. Under aeration, saturated sodium bicarbonate was added to adjust the pH to 8.5 to remove the reducing agent. The solution was then distilled under reduced pressure to remove the ethanol. The solution was placed in a dialysis bag (molecular weight cutoff 400 Da) and purified by dialyzing in ethanol solution for 32 h to obtain the crude product.

[0120] The crude product was dissolved in methanol at 60°C to prepare a 20% solution. The solution was then cooled to -16°C for recrystallization, resulting in the precipitation of a pale yellow solid. This solid was filtered, rinsed with acetone and methanol respectively, and dried to constant weight; this was the functional monomer, denoted as G4, the unimolecular terminator. The number is 10, and the yield is 73%.

[0121] The chemical reaction formula is shown below:

[0122]

[0123] Example 5:

[0124] Preparation of functional monomers

[0125] 507.7 g (0.1 mol) of hyperbranched polyethyleneimine (M = 5077 g / mol, primary amine: secondary amine: tertiary amine = 34:15:35) and 168.24 g (2 mol) of 3-methyl-3-butenal (R) were added to the reactor. 1 and R2 Both are H, R 3 The reaction mixture (CH3, n=1) was reacted with 5000 mL of methanol and 5000 mL of DMF, and the temperature was controlled at 27 °C under stirring. Under N2 protection, HAc was added to the above reaction solution to bring the pH to 3.5, followed by the addition of 169.668 g (2.7 mol) of NaBH3CN. The reaction was continued for 28 h under stirring. Under aeration, saturated sodium bicarbonate was added to bring the pH to 8.5 to remove the reducing agent. The mixture was then distilled under reduced pressure to remove methanol and DMF. The solution was placed in a dialysis bag (molecular weight cutoff 500 Da) and purified by dialyzing in ethanol solution for 28 h to obtain the crude product.

[0126] The crude product was dissolved in methanol at 60°C to prepare a 20% solution. The solution was then cooled to -16°C for recrystallization, resulting in the precipitation of a pale yellow solid. This solid was filtered, rinsed with acetone and methanol respectively, and dried to constant weight; this was the functional monomer, denoted as G5, the unimolecular terminator. The number was 16, and the yield was 72.5%.

[0127] The chemical reaction formula is shown below:

[0128]

[0129] Example 6:

[0130] Preparation of functional monomers

[0131] 689.2 g (0.1 mol) of hyperbranched polyethyleneimine (M = 6892 g / mol, primary amine: secondary amine: tertiary amine = 45:26:39) and 227.124 g (2.7 mol) of 3-methyl-2-butenal (R) were added to the reactor. 1 and R 2 Both are CH3, R 3 The reaction mixture (H, n=0) was prepared with 7500 mL of ethanol and 7500 mL of DMA, and the temperature was controlled at 28 °C under stirring. Under N2 protection, HAc was added to the above reaction solution until the pH reached 3, and then 237.5352 g (3.78 mol) of NaBH3CN was added. The reaction was continued for 35 h under stirring. Under aeration, saturated sodium bicarbonate was added to adjust the pH to 8.5 to remove the reducing agent. The mixture was then distilled under reduced pressure to remove ethanol and DMF, and the solution was placed in a dialysis bag (molecular weight cutoff 600 Da) and purified by dialyzing in ethanol solution for 40 h to obtain the crude product.

[0132] The crude product was dissolved in methanol at 60°C to prepare a 20% solution. The solution was then cooled to -16°C for recrystallization, resulting in the precipitation of a pale yellow solid. This solid was filtered, rinsed with acetone and methanol respectively, and dried to constant weight; this was the functional monomer, denoted as G6, unimolecularly terminal. The number was 24, and the yield was 71.13%.

[0133] The chemical reaction formula is shown below:

[0134]

[0135] Example 7

[0136] Following the method of Example 1, except that 2.4 mol of 4-methyl-3-pentenal was replaced with 6 mol of 4-methyl-3-pentenal, with other conditions remaining the same as in Example 1, a functional monomer, denoted as G7, was obtained, with the unimolecular terminus... The number was 10, and the yield was 37.96%.

[0137] Example 8

[0138] Following the method of Example 1, except that 10000 mL of methanol was replaced with 6000 mL of methanol, while other conditions remained the same as in Example 1, a functional monomer, denoted as G8, was obtained, with a single molecule terminal. The number was 8, and the yield was 41.36%.

[0139] Example 9

[0140] Following the method of Example 1, except that the temperature control temperature of 25°C was replaced with a temperature control temperature of 40°C, while other conditions remained the same as in Example 1, a functional monomer, denoted as G9, was obtained, with a single molecule terminal. The number was 7, and the yield was 22.4%.

[0141] Example 10

[0142] Following the method of Example 1, except that adding HAc to pH 3.5 was replaced with adding HAc to pH 5, while other conditions remained the same as in Example 1, the functional monomer, denoted as G10, was obtained. The number was 5, and the yield was 20.26%.

[0143] Example 11:

[0144] Preparation of hyperbranched filtration loss reducers

[0145] In a reactor equipped with a temperature control device, a reflux condenser, and a constant pressure feeding device, 21.3237 g (0.3 mol) of acrylamide, 30.9286 g (0.15 mol) of sodium p-styrene sulfonate, and 28.6281 g (0.01 mol) of G1 were sequentially added to 600 mL of DMF for mixing and stirring, and the temperature was raised to 67 °C.

[0146] After passing N2 for 30 minutes, 0.8 g of azobisisovalerate was added to the above mixed solution, and the reaction was continued for 18 hours to obtain the crude product of the hyperbranched filtration loss reducer.

[0147] After adding 600 mL of anhydrous methanol to precipitate, the product was filtered. The product was washed three times with acetone. Then, the product was extracted with a Soxhlet extractor for 24 h using a 3:2 glacial acetic acid-ethylene glycol mixed solvent as the extractant. The product was then vacuum dried at 25 °C to constant weight to obtain the hyperbranched filtration loss reducer, denoted as S1.

[0148] S1 was characterized by nuclear magnetic resonance [(CD3)2SO, 25℃], and its magnetic resonance spectrum was obtained. 1 H NMR) such as Figure 2 .according to 1 The H NMR analysis results are consistent with the molecular structure of the target product.

[0149] Example 12:

[0150] Preparation of hyperbranched filtration loss reducers

[0151] In a reactor equipped with a temperature control device, a reflux condenser, and a constant pressure feeding device, 67.6896 g (0.4 mol) of diacetone acrylamide (DAAM), 46.4592 g (0.2 mol) of potassium 3-prop-2-enoxypropane-1-sulfonate and 34.3537 g (0.012 mol) of G1 were sequentially added to 1280 mL of 1,4-dioxane for mixing and stirring, and the temperature was raised to 56 °C.

[0152] After passing N2 for 30 minutes, 1.18 g of azobis(N-hydroxyisobutylamidine) hydrate was added to the above mixed solution, and the reaction was continued for 16 hours to obtain the crude product of the hyperbranched filtration loss reducer.

[0153] After adding 800 mL of anhydrous methanol to precipitate, the product was filtered. The product was washed three times with acetone. Then, the product was extracted with a Soxhlet extractor for 24 h using a 3:2 glacial acetic acid-ethylene glycol mixed solvent as the extractant. The product was then vacuum dried at 25 °C to constant weight to obtain the hyperbranched filtration loss reducer, denoted as S2.

[0154] Example 13:

[0155] Preparation of hyperbranched filtration loss reducers

[0156] In a reactor equipped with a temperature control device, a reflux condenser, and a constant pressure feeding device, 49.5656 g (0.5 mol) of N-ethylacrylamide, 51.811 g (0.25 mol) of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and 22.9025 g (0.008 mol) of G1 were sequentially added to 1299 mL of dimethyl sulfoxide (DMSO).

[0157] The mixture is stirred and heated to 66°C.

[0158] After passing N2 for 30 minutes, 1.18 g of dimethyl azobisisobutyrate was added to the above mixed solution, and the reaction was continued for 20 hours to obtain the crude product of the hyperbranched filtration loss reducer.

[0159] After adding 800 mL of anhydrous methanol to precipitate, the product was filtered. The product was washed three times with acetone. Then, the product was extracted with a Soxhlet extractor for 24 h using a 3:2 glacial acetic acid-ethylene glycol mixed solvent as the extractant. The product was then vacuum dried at 25 °C to constant weight to obtain the hyperbranched filtration loss reducer, denoted as S3.

[0160] Example 14:

[0161] Preparation of hyperbranched filtration loss reducers

[0162] In a reactor equipped with a temperature control device, a reflux condenser, and a constant pressure feeding device, 20.221 g (0.2 mol) of N-hydroxymethylacrylamide (HAM), 15.8151 g (0.1 mol) of sodium methacrylate sulfonate (SMAS), and 42.9422 g (0.015 mol) of G1 were sequentially added to 443 mL of DMA for mixing and stirring, and the temperature was raised to 64 °C.

[0163] After passing N2 for 30 minutes, 1.26 g of azobisisobutyronitrile was added to the above mixed solution, and the reaction was continued for 24 hours to obtain the crude product of the hyperbranched filtration loss reducer.

[0164] After adding 400 mL of anhydrous methanol to precipitate, the product was filtered. The product was washed three times with acetone. Then, the product was extracted with a Soxhlet extractor for 24 h using a 3:2 glacial acetic acid-ethylene glycol mixed solvent as the extractant. The product was then vacuum dried at 25 °C to constant weight to obtain the hyperbranched filtration loss reducer, denoted as S4.

[0165] Example 15:

[0166] Preparation of hyperbranched filtration loss reducers

[0167] In a reactor equipped with a temperature control device, a reflux condenser, and a constant pressure feeding device, 49.5665 g (0.5 mol) of N-vinyl-N-methylacetamide (VMA), 14.412 g (0.1 mol) of sodium allyl sulfonate (SAS) and 36.7824 g (0.003 mol) of G2 were sequentially added to 1000 mL of water, mixed and stirred, and the temperature was raised to 67 °C.

[0168] After passing N2 for 30 minutes, 0.5038 g of azobis(N,N'-cyclobutylisobutylamididine) hydrate was added to the above mixed solution, and the reaction was continued for 24 hours to obtain the crude product of the hyperbranched filtration loss reducer.

[0169] After adding 800 mL of anhydrous methanol to precipitate, the product was filtered. The product was washed three times with acetone. Then, the product was extracted with a Soxhlet extractor for 24 h using a 3:2 glacial acetic acid-ethylene glycol mixed solvent as the extractant. The product was then vacuum dried at 25 °C to constant weight to obtain the hyperbranched filtration loss reducer, denoted as S5.

[0170] Example 16:

[0171] Preparation of hyperbranched filtration loss reducers

[0172] In a reactor equipped with a temperature control device, a reflux condenser, and a constant pressure feeding device, 34.6424 g (0.2 mol) of N,N-bis(2-hydroxyethyl)methacrylamide, 61.5796 g (0.25 mol) of potassium 2-acryloyloxy-2-methylpropanesulfonate (AOPS-K) and 54.3086 g (0.005 mol) of G3 were sequentially added to 1060 mL of 1,4-dioxane for mixing and stirring, and the temperature was raised to 56 °C.

[0173] After passing N2 for 30 min, 3.01 g of 2,2'-azobis(N-cyclohexylisobutylamidine) hydrochloride was added to the above mixed solution, and the reaction was continued for 12 h to obtain the crude product of hyperbranched filtration loss reducer.

[0174] After adding 800 mL of anhydrous methanol to precipitate, the product was filtered. The product was washed three times with acetone. Then, the product was extracted with a Soxhlet extractor for 24 h using a 3:2 glacial acetic acid-ethylene glycol mixed solvent as the extractant. The product was then vacuum dried at 25 °C to constant weight to obtain the hyperbranched filtration loss reducer, denoted as S6.

[0175] Example 17:

[0176] Preparation of hyperbranched filtration loss reducers

[0177] In a reactor equipped with a temperature control device, a reflux condenser, and a constant pressure feeding device, 45.2057 g (0.35 mol) of N-(2-hydroxypropyl)acrylamide, 46.6142 g (0.19 mol) of potassium 2-acrylamido-2-methylpropanesulfonate (AMPS-K) and 45.4017 g (0.011 mol) of G4 were sequentially added to 960 mL of DMSO for mixing and stirring, and the temperature was raised to 104 °C.

[0178] After passing N2 for 30 minutes, 2.5 g of azoisobutyl cyanoformamide was added to the above mixed solution, and the reaction was continued for 12 hours to obtain the crude product of hyperbranched filtration loss reducer.

[0179] After adding 800 mL of anhydrous methanol to precipitate, the product was filtered. The product was washed three times with acetone. Then, the product was extracted with a Soxhlet extractor for 24 h using a 3:2 glacial acetic acid-ethylene glycol mixed solvent as the extractant. The product was then vacuum dried at 25 °C to constant weight to obtain the hyperbranched filtration loss reducer, denoted as S7.

[0180] Example 18:

[0181] Preparation of hyperbranched filtration loss reducers

[0182] In a reactor equipped with a temperature control device, a reflux condenser, and a constant pressure feeding device, 36.2112 g (0.32 mol) of N-isopropylacrylamide (NIPAM), 69.3601 g (0.18 mol) of sodium 2-acrylamidooctyl sulfonate and 44.8531 g (0.007 mol) of G5 were sequentially added to 1200 mL of DMF for mixing and stirring, and the temperature was raised to 44 °C.

[0183] After passing N2 for 30 minutes, 3g of azobisisobutyrazoline hydrochloride was added to the above mixed solution, and the reaction was continued for 24 hours to obtain the crude product of the hyperbranched filtration loss reducer.

[0184] After adding 800 mL of anhydrous methanol to precipitate, the product was filtered. The product was washed three times with acetone. Then, the product was extracted with a Soxhlet extractor for 24 h using a 3:2 glacial acetic acid-ethylene glycol mixed solvent as the extractant. The product was then vacuum dried at 25 °C to constant weight to obtain the hyperbranched filtration loss reducer, denoted as S8.

[0185] Example 19:

[0186] Preparation of hyperbranched filtration loss reducers

[0187] In a reactor equipped with a temperature control device, a reflux condenser, and a constant pressure feeding device, 22.9786 g (0.27 mol) of N-vinylacetamide (NMVA), 63.7654 g (0.16 mol) of sodium 2-acryloyloxyhexadecyl sulfonate and 44.4394 g (0.005 mol) of G6 were sequentially added to 1200 mL of DMA for mixing and stirring, and the temperature was raised to 88 °C.

[0188] After passing N2 for 30 minutes, 1.25 g of azobiscyclohexylformonitrile was added to the above mixed solution, and the reaction was continued for 15 hours to obtain the crude product of hyperbranched filtration loss reducer.

[0189] After adding 800 mL of anhydrous methanol to precipitate, the product was filtered. The product was washed three times with acetone. Then, the product was extracted with a Soxhlet extractor for 24 h using a 3:2 glacial acetic acid-ethylene glycol mixed solvent as the extractant. The product was then vacuum dried at 25 °C to constant weight to obtain the hyperbranched filtration loss reducer, denoted as S9.

[0190] Example 20:

[0191] Preparation of hyperbranched filtration loss reducers

[0192] In a reactor equipped with a temperature control device, a reflux condenser, and a constant pressure feeding device, 35.3035 g (0.25 mol) of N,N-diethylmethacrylamide, 34.6967 g (0.15 mol) of potassium 3-prop-2-enamidopropane-1-sulfonate and 53.3273 g (0.006 mol) of G6 were sequentially added to 1200 mL of DMSO for mixing and stirring, and the temperature was raised to 69 °C.

[0193] After passing N2 for 30 minutes, 1.5 g of azodicyanovalerate was added to the above mixed solution, and the reaction was continued for 16 hours to obtain the crude product of the hyperbranched filtration loss reducer.

[0194] After adding 800 mL of anhydrous methanol to precipitate, the product was filtered. The product was washed three times with acetone. Then, the product was extracted with a Soxhlet extractor for 24 h using a 3:2 glacial acetic acid-ethylene glycol mixed solvent as the extractant. The product was then vacuum dried at 25 °C to constant weight to obtain the hyperbranched filtration loss reducer, denoted as S10.

[0195] Example 21:

[0196] The method of Example 11 was followed, except that 0.3 mol acrylamide was replaced with 0.3 mol N-hydroxyethyl acrylamide, 0.15 mol sodium p-styrene sulfonate was replaced with 0.15 mol potassium 2-acrylamidodecyl sulfonate, and 0.8 g azobisisovalerate was replaced with 0.8 g azobisisobutylamidine hydrochloride. Other conditions were the same as in Example 1, and a hyperbranched filtration loss reducer was obtained, denoted as S11.

[0197] Example 22:

[0198] The method of Example 11 was followed, except that 0.3 mol acrylamide was replaced with 0.3 mol N-(2-hydroxypropyl)acrylamide, 0.15 mol sodium p-styrenesulfonate was replaced with 0.15 mol sodium 2-acryloyloxydodecylsulfonate, and 0.8 g azobisisovalerate was replaced with 0.8 g azobisisopropylimidazoline. Other conditions were the same as in Example 1, and a hyperbranched filtration loss reducer was obtained, denoted as S12.

[0199] Comparative Example 1:

[0200] Following the method of Example 11, except that 0.01 mol G1 was replaced with 0.1 mol 4-methyl-3-pentenal, and other conditions were the same as in Example 1, a hyperbranched filtration loss reducing agent was obtained, denoted as D1.

[0201] Comparative Examples 2-5:

[0202] Following the method of Example 11, except that G1 was replaced with equimolar amounts of G7, G8, G9 and G10, and other conditions were the same as in Example 1, resulting in hyperbranched filtration loss reducing agents, denoted as D2, D3, D4 and D5.

[0203] Test Example 1:

[0204] Filtration performance evaluation

[0205] Test method: Refer to GB / T 16783.1-2014: Field testing of drilling fluids for the oil and gas industry - Part 1: Water-based drilling fluids.

[0206] Freshwater-based slurry: Add 400 mL of tap water to a high-speed stirring cup, and add 16.0 g of calcium bentonite and 0.8 g of Na2CO3 in a measured amount while stirring continuously. Stir for 20 min, stopping at least twice during this period to scrape off the bentonite adhering to the container wall, and cure in a sealed container for 24 h.

[0207] CaCl2 brine-based slurry: Add 400 mL of tap water to a high-speed stirring cup, and quantitatively add CaCl2, 16 g of calcium bentonite, and 0.8 g of Na2CO3 while continuously stirring. Stir for 20 min, stopping at least twice during this period to scrape off the bentonite adhering to the container wall, and cure in a sealed container for 24 h.

[0208] Freshwater / CaCl2 brine drilling fluid system: Weigh 8g of the hyperbranched filtration reducers S1-S12 and D1-D5 prepared in Examples 11-22 and Comparative Examples 1-5, respectively, and add them to 400mL of freshwater-based slurry or CaCl2 brine-based slurry. After thorough stirring, cure in a sealed container for 24h. After hot rolling at different aging temperatures for 16h, measure the high-temperature and high-pressure filtration loss (FL) of the drilling fluid using a high-temperature and high-pressure filtration analyzer. HTHP The test temperature was the same as the aging temperature, and the measurement results are shown in Tables 1, 2 and 3.

[0209] Table 1 Effect of aging temperature on FL HTHP Impact (freshwater drilling fluid system)

[0210]

[0211]

[0212] Note: / indicates "total loss", the same applies below.

[0213] Table 2 Temperature effect on FL HTHP The impact (CaCl2 brine drilling fluid system)

[0214]

[0215]

[0216] Note: The mass percentage concentration of CaCl2 in the CaCl2 brine drilling fluid system is 0.5%.

[0217] Table 3. Effects of CaCl2 on FL HTHP The impact (CaCl2 brine drilling fluid system)

[0218]

[0219]

[0220] Note: The aging temperature is 160℃.

[0221] As can be seen from Tables 1 and 2, with the increase of aging temperature, the FL of drilling fluid systems containing S1-S12 and D1-D5 increases. HTHP The continuously increasing FL indicates that the aging temperature has a significant negative impact on the filtration and wall-building performance of the drilling fluid. Under the same aging temperature conditions, the FL of a freshwater / CaCl2 brine drilling fluid system with added S1-S12 and D2... HTHP The FL level is significantly lower than that of freshwater / CaCl2 brine drilling fluid systems with added D1, D3-D5. HTHP This indicates that the hyperbranched filtration loss reducing agent provided by the present invention has a strong filtration loss and wall-building ability under high temperature conditions; the difference of G7 prepared by using a non-preferred range of molar ratio of hyperbranched polyethyleneimine to aldehyde compound is mainly reflected in the yield of G7.

[0222] As shown in Table 3, with the increase of CaCl2 concentration, the FL of the freshwater / CaCl2 brine drilling fluid system with added S1~S12 and D2... HTHP The filtration efficiency increased slightly, but no uncontrolled filtration performance was observed. In contrast, the freshwater / CaCl2 brine drilling fluid system with added D1 remained in a state of total filtration loss, while the freshwater / CaCl2 brine drilling fluid system with added D3-D5 showed a higher filtration efficiency. HTHP The upward trend is quite obvious.

[0223] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A functional monomer for preparing hyperbranched filtration loss reducers for drilling fluids, characterized in that, Its central group is a hyperbranched polyethyleneimine group, and the ends of the molecular structure include -NH2 and the structure shown in formula i: In formula i, R 1 R 2 R 3 It is independently selected from one of H, C1-C6 alkyl, and cycloalkyl; In formula i, n represents the number of CH2- structural units, which is a natural number from 0 to 18.

2. The functional monomer for preparing hyperbranched filtration loss reducers for drilling fluids according to claim 1, characterized in that: n is a natural number from 0 to 6.

3. The functional monomer for preparing hyperbranched filtration loss reducers for drilling fluids according to claim 2, characterized in that: n is 0, 1, 2, or 3.

4. A method for preparing a functional monomer for preparing a hyperbranched filtration loss reducer for drilling fluids, characterized in that: The synthesis was carried out using hyperbranched polyethyleneimine and aldehyde compounds of formula ii as raw materials. The synthesis method includes: reacting hyperbranched polyethyleneimine and an aldehyde compound of formula ii in the presence of a reducing agent to obtain a functional monomer for preparing a hyperbranched filtration reducer for drilling fluids; In formula ii, R 1 R 2 R 3 It is independently selected from one of H, C1-C6 alkyl, and cycloalkyl; In equation ii, n represents the number of CH2- structural units, which is a natural number from 0 to 18.

5. The method for preparing the functional monomer for preparing hyperbranched filtration loss reducers for drilling fluids according to claim 4, characterized in that: n is a natural number from 0 to 6.

6. The method for preparing the functional monomer for preparing hyperbranched filtration loss reducers for drilling fluids according to claim 5, characterized in that: n is 0, 1, 2, or 3.

7. The method for preparing the functional monomer for preparing hyperbranched filtration loss reducers for drilling fluids according to claim 4, characterized in that: The relative molecular mass M of the hyperbranched polyethyleneimine is 1500–25000 g / mol.

8. The method for preparing the functional monomer for preparing hyperbranched filtration loss reducers for drilling fluids according to claim 7, characterized in that: The relative molecular mass M of the hyperbranched polyethyleneimine is 2000–10000 g / mol.

9. The method for preparing the functional monomer for preparing hyperbranched filtration loss reducers for drilling fluids according to claim 8, characterized in that: The relative molecular mass M of the hyperbranched polyethyleneimine is 2041 g / mol, 8754 g / mol, 9980 g / mol, 2875 g / mol, 5077 g / mol, or 6892 g / mol.

10. The method for preparing the functional monomer for preparing hyperbranched filtration loss reducers for drilling fluids according to claim 4, characterized in that: The structural formula of the hyperbranched polyethyleneimine is shown in I':

11. The method for preparing the functional monomer for preparing hyperbranched filtration reduction agents for drilling fluids according to claim 10, characterized in that: For example, the relative molecular mass of hyperbranched polyethyleneimine in formula I' is 2041 g / mol. In the molecule, the ratio of primary amine: secondary amine: tertiary amine is 20:10:18, which means that the number of primary amine groups, i.e., terminal amine groups, in a single molecule of hyperbranched polyethyleneimine is 20, the number of secondary amine groups is 10, and the number of tertiary amine groups is 18.

12. The method for preparing the functional monomer for preparing hyperbranched filtration loss reducers for drilling fluids according to claim 4, characterized in that, The steps are as follows: Step 1: Mix hyperbranched polyethyleneimine, aldehyde compound of formula ii and solvent evenly, and control the temperature to 10-50℃ to obtain reaction solution A; Step 2: In a protective atmosphere, add a pH adjuster to adjust the pH value to 2-6 in reaction solution A, then add a reducing agent. The reaction is carried out at a controlled temperature of 10-50℃ for 16-60 hours to obtain reaction solution B. Step 3: Post-process the reaction solution B, which includes adding saturated sodium bicarbonate to adjust the pH to 8.5 under ventilation, removing the reducing agent, and then performing vacuum distillation, dialysis to remove impurities, and recrystallization to obtain the functional monomer for preparing the hyperbranched filtration reducer for drilling fluid.

13. The method for preparing the functional monomer for preparing hyperbranched filtration loss reducers for drilling fluids according to claim 12, characterized in that, In step 1: The molar ratio of the hyperbranched polyethyleneimine to the aldehyde compound shown in Formula ii is 1:(0.2~2), wherein the molar amount of the hyperbranched polyethyleneimine is calculated based on the molar amount of its molecular structure terminal -NH2. The total mass percentage of hyperbranched polyethyleneimine and aldehyde compounds of formula ii in the solvent is 2% to 20%. The solvent is selected from organic solvents, and is at least one of methanol, ethanol, N,N-dimethylformamide or N,N-dimethylacetamide.

14. The method for preparing the functional monomer for preparing hyperbranched filtration loss reducers for drilling fluids according to claim 13, characterized in that, In step 1: the total mass percentage of hyperbranched polyethyleneimine and the aldehyde compound of formula ii in the solvent is 5% to 10%. The molar ratio of the hyperbranched polyethyleneimine to the aldehyde compound shown in Formula ii is 1:(0.3 to 0.7).

15. The method for preparing the functional monomer for preparing hyperbranched filtration loss reducers for drilling fluids according to claim 12, characterized in that, In step 2: The pH adjuster is an organic acid, used to adjust the pH value to 3-4; The reducing agent is selected from borohydrides, and the molar ratio of the reducing agent to the aldehyde compound shown in formula (ii) is (1-2.5):1; the reaction is carried out at a controlled temperature of 20-30°C for a reaction time of 20-40 h.

16. The method for preparing the functional monomer for preparing hyperbranched filtration loss reducers for drilling fluids according to claim 15, characterized in that, In step 2: The pH adjuster is acetic acid, and the reducing agent is NaBH4 or NaBH3CN; the molar ratio of the reducing agent to the aldehyde compound shown in formula (ii) is (1-1.5):

1.

17. The method for preparing the functional monomer for preparing hyperbranched filtration loss reducers for drilling fluids according to claim 12, characterized in that, In step 3: the crude product obtained after vacuum distillation is added to a dialysis bag to remove the reducing agent and unreacted substances. The molecular weight cutoff of the dialysis bag is 200-1800 Da. The dialysis to remove impurities is performed in ethanol for 24–48 hours; The specific steps of recrystallization include: adding the crude product to methanol, dissolving it at 60°C to prepare a 20% solution, cooling it to -16°C to precipitate the solid, filtering, washing, and drying to constant weight.

18. The method for preparing the functional monomer for preparing hyperbranched filtration loss reducers for drilling fluids according to claim 17, characterized in that, In step 3: the molecular weight cutoff of the dialysis bag used is 400-800 Da.

19. A hyperbranched filtration reducer for drilling fluids, characterized in that, The hyperbranched filtration reduction agent contains structural unit A as shown in Formula I, structural unit B as shown in Formula II, and a third structural unit C; The third structural unit C is the functional monomer for preparing hyperbranched filtration reduction agent for drilling fluid as described in claim 1; The molar ratio of structural unit A, structural unit B, and structural unit C is (20–50):(10–25):(8–15); the molar amount of structural unit C is determined by the molecular end of its structure. Molarity meter; In Formula I, R1 is selected from H or C1-C6 alkyl groups; R2 is selected from in, R a and R b Each is independently selected from one of -H, C1-C6 alkyl groups, C1-C6 alkyl alcohols, and C1-C8 alkyl ketones; R c Selected from -H or C1-C6 alkyl groups; R d Selected from —CH3, —CH2CH3, One of them; In Formula II, R3 is selected from -H or C1-C6 alkyl groups; R4 is selected from... One of them.

20. The hyperbranched filtration reducer for drilling fluids according to claim 19, characterized in that, For R4: A is selected from at least one of H, Na, K, Rb or Cs, j, k, l are independently selected as integers from 0 to 3; m, n are natural numbers from 4 to 14.

21. A method for preparing a hyperbranched filtration reducer for drilling fluids, characterized in that, The steps are as follows: Step 1: Structural unit A, structural unit B and third structural unit C of claim 19 are mixed and stirred in a solvent and heated to a predetermined temperature of 40-105°C. Step 2: After purging with nitrogen for 30 minutes, add the initiator to the above mixed solution and continue the reaction under stirring for 12-24 hours to obtain the crude product of the filtration loss reducer. Step 3: The crude product is subjected to precipitation, washing, extraction, and vacuum drying to obtain the finished product of hyperbranched filtration reducer for drilling fluid.

22. The method for preparing the hyperbranched filtration reducer for drilling fluid according to claim 21, characterized in that, The mass percentage concentrations of the monomers of structural unit A, structural unit B, and third structural unit C in the solvent are 8.0% to 16.0%. The solvent is one or more of the following: water, acetone, butanone, chloroform, dichloromethane, 1,1-dichloroethane, 1,2-dichloroethane, methyl ethyl ketone, tetrahydrofuran, petroleum ether, diethyl ether, acetonitrile, ethyl acetate, benzene, toluene, m-xylene, cyclohexane, ethylene glycol dimethyl ether, nitromethane, 1,4-dioxane, pyridine, morpholine, 4-methyl-2-pentanone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide. The predetermined temperature in step 1 is 44–104°C; The initiator in step 2 is one or more of the following: azo initiators, organic peroxide initiators, inorganic peroxide initiators, and oil-soluble redox initiators; the amount of initiator added is 0.5% to 2.0% of the total weight of the three monomers.

23. The method for preparing the hyperbranched filtration reducer for drilling fluid according to claim 22, characterized in that, The azo initiator is one or more of the following: azobisisobutyrazoline hydrochloride, azoisobutyronitrile, azobisisobutyronitrile, azobiscarboxyethyl-2-isobutylamidine hydrate, azodimethyl N-2-hydroxybutylacrylamide, azobiscyclohexylformitrile, azobisisovaleritrile, azobisisoheptanenitrile, azobiscyanopentanoic acid, azobisisobutyronitrile hydrochloride, azobisisopropylimidazoline, azobisN-hydroxyisobutylamidine hydrate, azobisN,N'-cyclobutylisobutylamidine hydrate, dimethyl azobisisobutyrate, and 2,2'-azobis(N-cyclohexylisobutylamidine) hydrochloride.

24. The application of a hyperbranched filtration loss reducer for drilling fluids, characterized in that, The hyperbranched filtration reducer for drilling fluids according to claim 19 is applied to water-based drilling fluids in the field of petroleum engineering, wherein the amount of hyperbranched filtration reducer added is 0.2wt% to 2.0wt%; the water-based drilling fluid is a bentonite drilling fluid system, a potassium amine-based drilling fluid system, a polymer anti-collapse drilling fluid system, a sulfonated drilling fluid system, a polysulfonated drilling fluid system, a KCl drilling fluid system, a brine drilling fluid system, or a silicate drilling fluid system.

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