Conjugated crosslinking monomer, solid-free drilling fluid thickening agent, and preparation method and application thereof

Abstract

The application discloses a conjugated crosslinking monomer, a solid-phase-free drilling fluid thickening agent, and a preparation method and application thereof. The conjugated crosslinking monomer has a stereoscopic alkyl structure and a conjugated diene structure, and is shown in the following formula. The conjugated crosslinking monomer is prepared by synthesizing an alkenyl compound with an adamantane compound in the presence of a catalyst. The conjugated crosslinking monomer is reacted with an alkenyl amide and an alkenyl sulfonic acid to obtain the solid-phase-free drilling fluid thickening agent. The thickening agent has good temperature resistance and salt resistance, and can improve the suspension and rock carrying performance of a clay-free drilling fluid system in a medium-deep well.

Description

Technical Field

[0001] This invention relates to a conjugated crosslinking monomer, a thickener for solids-free drilling fluids, a method for preparing the thickener for solids-free drilling fluids, and an application of the thickener for solids-free drilling fluids, belonging to the field of petroleum additives technology. Background Technology

[0002] Solids-free drilling fluids, also known as clay-free drilling fluids, are a type of drilling fluid system developed from low-solids drilling fluids to minimize reservoir contamination by foreign solid components. This type of drilling fluid system primarily uses salts (such as NaCl, KCl, KCOOH, etc.) as weighting materials, while using polymers as viscosity modifiers. The polymers play a crucial role in solids-free drilling fluid systems, being key to maintaining the overall suspension and rock-carrying capacity of the system. In solids-free drilling fluid systems, polymers spread and intertwine in the aqueous solution to form a spatial network structure, playing a vital role in maintaining the drilling fluid's rock-carrying capacity. Currently, commonly used viscosity modifiers in solids-free drilling fluid systems mainly include biopolymers and their modified products, such as xanthan gum (XC), high-viscosity carboxymethyl cellulose (HV-CMC), and high-viscosity polyanionic cellulose sodium salt (PAC-HV), as well as synthetic polymer products (such as polyacrylic acid polymers, polyacrylamide polymers, and polyurethane polymers).

[0003] In recent years, to improve the applicability of solids-free drilling fluids in deep formations, solids-free drilling fluid systems with good temperature resistance have emerged. The foundation for constructing solids-free drilling fluids with excellent temperature resistance largely depends on temperature-resistant viscosifiers. For example, in 2015, a master's thesis from Southwest Petroleum University, "Preparation and System Study of Viscosifiers for Formate Solids-Free Drilling Fluids," reported the use of a ternary polymer, PADA, obtained by free radical polymerization with acrylamide (AM), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and methacryloyloxyethyltrimethylammonium chloride (DMC) as monomers, as a viscosifier for solids-free drilling fluids. A 0.6% PADA solution showed a viscosity decrease of only 17% when the temperature increased from 20℃ to 80℃, and the formate solids-free drilling fluid system constructed using it only achieved a temperature resistance of 120℃.

[0004] In addition, Chinese invention patent with publication number CN106349114B discloses a hydrophobic monomer and a thickener for solid-free drilling fluid based on the monomer. The hydrophobic associative polymer formed by polymerizing an alkenyl monomer containing a diphenyl structure with N-vinylpyrrolidone is used as a thickener for solid-free drilling fluid, and its temperature resistance is only up to 150°C.

[0005] As can be seen from the above, hydrophobic associating polymers, especially those with rigid structural units, are commonly used as viscosity improvers for temperature- and salt-resistant solids-free drilling fluids. Currently, benzene rings and cyclohexane are generally chosen as the rigid structural units. Summary of the Invention

[0006] The first objective of this invention is to overcome the problems existing in the prior art and provide a conjugated crosslinking monomer that can be used to prepare hydrophobic associative polymers, which can be used as a thickener in solid-free drilling fluids and have good temperature and salt resistance.

[0007] To solve the above technical problems, the present invention provides a conjugated crosslinking monomer having a stereoalkyl structure and a conjugated diene structure, with the molecular formula of formula I-1 or formula I-2:

[0008]

[0009]

[0010] Preferably, R, R0, R1, R2, and R3 are each -H, C1 to C6 alkyl, or phenyl, respectively.

[0011] Preferably, R1, R2, and R3 are -H, -CH3, or phenyl, R is -H, -CH3, or phenyl, and R0 is -H, -CH3, or -CH2CH3.

[0012] The second objective of this invention is to overcome the problems existing in the prior art and provide a method for preparing a conjugated crosslinking monomer. The prepared conjugated crosslinking monomer can be used to prepare a hydrophobic associative polymer, which can be used as a thickener in solid-free drilling fluids and has good temperature and salt resistance.

[0013] To address the above technical problems, the present invention provides a method for preparing a conjugated crosslinked monomer, wherein an alkenyl compound represented by formula II-1 is reacted with an adamantane compound represented by formula II-2 or formula II-3 in the presence of a catalyst.

[0014]

[0015]

[0016]

[0017] The molar ratio of alkenyl compound to adamantane compound is 1:(1.3 to 1.6), and the reaction yields the conjugated crosslinked monomers shown in Formula I-1 or Formula I-2.

[0018] Preferably, R, R0, R1, R2, and R3 are each -H, C1 to C6 alkyl, or phenyl, respectively.

[0019] Preferably, R1, R2, and R3 are -H, -CH3, or phenyl, R is -H, -CH3, or phenyl, and R0 is -H, -CH3, or -CH2CH3.

[0020] The catalyst is low-valent titanium, and the preparation method of the low-valent titanium includes: dissolving a titanium-containing reagent and a reducing agent in solvent A to carry out a reduction reaction; the solvent A is tetrahydrofuran (THF), and the reduction reaction is carried out under a protective atmosphere, which is nitrogen and / or argon.

[0021] Preferably, the titanium-containing reagent is at least one of TiCl3, TiCl4, or commercial titanium powder; the reducing agent is at least one of K, Li, Na, Zn+CuCl, LiAlH4, Mg, Mg+Hg, Li+Hg, and chlorosilane, and the valence state of the low-valence titanium varies with the reducing activity of the reducing agent and the molar ratio of the reducing agent to the titanium-containing reagent.

[0022] Preferably, the titanium-containing reagent is TiCl4, and its concentration in solvent A is 0.3–0.6 mmol / mL; the reducing agent is Zn and CuCl, wherein the concentration of Zn in solvent A is 0.3–0.6 mmol / mL, the concentration of CuCl in solvent A is 0.05–0.10 mmol / mL, and solvent A is tetrahydrofuran (THF).

[0023] Preferably, activated Zn, CuCl and solvent A are added to the reactor, then cooled and stirred, and TiCl4 is added to carry out the reduction reaction in a reflux manner to obtain the low-valent titanium.

[0024] Preferably, the reflux temperature is 68°C to 76°C, and the reflux is followed by cooling at a temperature of -10°C to 0°C, with a reflux time of 4 to 6 hours; the particle size of the activated Zn is 600 to 1000 mesh.

[0025] Preferably, the alkenyl compound and the adamantane compound are first dissolved in solvent B, and then a low-valent titanium catalyst is mixed in. The synthesis reaction is carried out under stirring and reflux. Solvent B has the same composition as solvent A, and the volume ratio of solvent B to solvent A is 1:(2-4). The concentration of the alkenyl compound in solvent B is 0.3-0.5 mmol / mL.

[0026] Preferably, the temperature of the synthesis reaction is 68–76°C and the time is 2–10 h.

[0027] Preferably, after obtaining the conjugated crosslinked monomer in the synthesis reaction, a quenching agent is added to carry out a quenching reaction. The quenching agent is one or more of alkali metal cyanides, ammonia compounds, boranes, K2CO3, LiAlH4, and NaBH.

[0028] Preferably, the quenching agent is K2CO3, the concentration of the K2CO3 solution is 5wt% to 10wt%, and the volume ratio of the K2CO3 solution to the solvent B is 1:(5 to 10).

[0029] Preferably, after the quenching reaction, filtration is performed to remove the catalyst and collect the filtrate; during the filtration process, diatomaceous earth filter aid, charcoal powder filter aid, activated carbon filter aid, or perlite filter aid is added.

[0030] Preferably, the collected filtrate is rinsed with CH2Cl2 as the rinsing solvent. After rinsing, the rinsing liquid is mixed with the filtrate to obtain a mixture. The mixture is dried with a desiccant, filtered, and then distilled under reduced pressure to remove the solvent, yielding a pale yellow crude product.

[0031] Preferably, the desiccant is an inorganic neutral desiccant, and is one or more of MgSO4, anhydrous Na2SO4, CaSO4, and CaCl2.

[0032] Preferably, the pale yellow crude product is purified by recrystallization using methanol or ethanol to obtain the conjugated crosslinking monomer as a pale yellow paste.

[0033] Preferably, the catalyst is at least one of low-valent tungsten, low-valent molybdenum, low-valent zirconium, low-valent vanadium, or low-valent niobium, which can promote carbonyl coupling to olefins.

[0034] The third objective of this invention is to overcome the problems existing in the prior art and provide a solids-free drilling fluid viscosifier that can be used in solids-free drilling fluids in high-temperature wells with high salinity or salt-gypsum formations, and has good temperature and salt resistance.

[0035] To solve the above technical problems, the present invention provides a solids-free drilling fluid thickener containing alkenylamide A as shown in Formula III, alkenylsulfonic acid B as shown in Formula IV, and the conjugated crosslinking monomer C as described in claim 1.

[0036]

[0037] The molar ratio between the three is A:B:C = (30-60):(10-30):(1-5).

[0038] Preferably, in formula III: R 1 It is -H or a C1 to C6 alkyl group;

[0039] R 2 for

[0040] Among them, R a and R bEach is independently selected from one of -H, C1-C6 alkyl groups, C1-C6 alkyl alcohols, and C1-C8 alkyl ketones;

[0041] R c Selected from -H or C1 to C6 alkyl groups;

[0042] R d Selected from -CH3, -CH2CH3, One of them.

[0043] Preferably, in formula IV: R 3 Selected from -H or C1 to C6 alkyl groups;

[0044] R 4 Selected from

[0045] One of them.

[0046] Preferably, for R 4 A is selected from at least one of H, Na, K, Rb or Cs; j, k, l are integers from 0 to 3; m, n are natural numbers from 4 to 14.

[0047] The fourth objective of this invention is to overcome the problems existing in the prior art and provide a method for preparing a viscosity modifier for solid-free drilling fluids. The prepared viscosity modifier can be used in solid-free drilling fluids in high-temperature wells with high salinity or in salt-gypsum formations, and has good temperature and salt resistance.

[0048] To solve the above technical problems, the present invention provides a method for preparing a solids-free drilling fluid viscosity improver, comprising the following steps:

[0049] S1. The alkenylamide A, alkenyl sulfonic acid B and conjugated crosslinking monomer C described in claim 21 are mixed and stirred in solvent C and heated to a predetermined temperature.

[0050] S2. After purging with nitrogen for 30 minutes, an initiator is added to the above mixed solution, and the reaction continues for 8 to 16 hours to obtain the crude thickener product.

[0051] S3. After precipitation, washing, extraction and vacuum drying of the crude viscosity improver, a solids-free viscosity improver for drilling fluid is obtained.

[0052] Preferably, the molar ratio of the alkenylamide, alkenylsulfonic acid and the above-mentioned three structural conjugated crosslinking monomers is (30-60):(10-30):(1-5), the mass percentage concentration of the three structural conjugated crosslinking monomers in solvent C is 5.0%-15.0%, and the reaction temperature is 44-104°C.

[0053] Preferably, the solvent C is one or more of acetone, tetrahydrofuran, 1,4-dioxane, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

[0054] Preferably, the amount of the initiator added is 0.5% to 1.5% of the total weight of the three structural conjugated crosslinking monomers, and the initiator is one or more of organic peroxide initiators, inorganic peroxide initiators, and oil-soluble redox initiators;

[0055] Alternatively, the initiator may be an azo initiator, specifically one or more of the following: azobisisobutyrazoline hydrochloride, azoisobutyronitrile, azobisisobutyronitrile, azodimethyl N-2-hydroxybutylacrylamide, azobisisovalerate, azobisisovalerate, azobisisobutyronitrile, azobisisobutyronitrile, azobisisobutyronitrile hydrochloride, azobisisopropylimidazoline, azobis(N,N'-cyclobutylisobutyronitrile) hydrate, dimethyl azobisisobutyrate, and 2,2'-azobis(N-cyclohexylisobutyronitrile) hydrochloride.

[0056] The fifth objective of this invention is to overcome the problems existing in the prior art and provide an application of a viscosifier for solid-free drilling fluids. When used in solid-free drilling fluids, it has good temperature and salt resistance, can improve the suspension and rock-carrying performance of clay-free drilling fluid systems in medium and deep wells, and avoids reservoir contamination by foreign solid components.

[0057] To solve the above technical problems, the present invention provides an application of a viscosity modifier for solid-free drilling fluid, wherein the viscosity modifier for solid-free drilling fluid as described in any one of claims 21 to 24 is added to the solid-free drilling fluid, or the viscosity modifier for solid-free drilling fluid prepared by the preparation method according to any one of claims 25 to 28 is added; the amount of the viscosity modifier added is 0.5wt% to 4.0wt% based on the total amount of solid-free drilling fluid.

[0058] Compared with the prior art, the present invention has achieved the following beneficial effects: First, the conjugated crosslinking monomer of the present invention contains a diene structure. The conjugation effect disperses the electron cloud on the molecular double bond, the bond length tends to be averaged, the molecular refractive index increases, the internal energy decreases, the double bond is more easily opened, and the activity of the polymerization reaction increases.

[0059] Secondly, the conjugated crosslinking monomer of the present invention contains a more rigid stereoalkyl structure, which is beneficial to improving the rigidity of the target polymer, increasing the spatial volume and steric hindrance of the polymer molecular chain, reducing the degree of thermal motion of polymer molecules under high temperature conditions, and improving the temperature resistance of polymer molecules.

[0060] Third, the synthesis reaction may contain excess reactants. If the excess reactants continue to react and generate undesirable products, they can be removed from the system by quenching, using a compound that reacts more readily with the excess, thus preventing impurities from appearing in the product.

[0061] Fourth, a viscosity enhancer with good temperature and salt resistance is beneficial for using solids-free drilling fluids in high-temperature wells, high-saltification or salt-gypsum formations, improving the suspension and rock-carrying performance of clay-free drilling fluid systems, and preventing reservoir contamination by foreign solid components. Attached Figure Description

[0062] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The drawings are provided for reference and illustration only and are not intended to limit the present invention.

[0063] Figure 1 As in Embodiment 1 of the present invention 1 H NMR spectrum;

[0064] Figure 2 This is Example 2 of the present invention. 1 H NMR spectrum;

[0065] Figure 3 This is Example 3 of the present invention. 1 H NMR spectrum;

[0066] Figure 4 This is Example 4 of the present invention. 1 H NMR spectrum. Detailed Implementation

[0067] In the following description of the present invention, the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not mean that the device must have a specific orientation.

[0068] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific illustrations.

[0069] 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 invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention.

[0070] Example 1

[0071] Under nitrogen protection, 29.42 g, 450 mmol, 800 mesh activated Zn powder, 7.43 g, 75 mmol CuCl and 1000 mL THF were added to the reactor, cooled to -5 °C, stirred, and 85.36 g, 450 mmol TiCl4 were added. The mixture was heated to 72 °C and refluxed for 5 h, and then cooled to -5 °C again to obtain a low-valent titanium reducing agent.

[0072] 16.82 g (200 mmol) of 3-methyl-3-buten-2-one (where R1 and R2 are H, and R and R3 are CH3) and 49.27 g (300 mmol) of 1-adamantanecarboxaldehyde (where R0 is H) were dissolved in 500 mL of THF and then mixed into a low-valent titanium reducing agent. The mixture was heated to 72 °C and refluxed for 6.5 h under stirring. 60 mL of 8.0 wt% K2CO3 solution was added, and the mixture was filtered through diatomaceous earth. The filtrate was collected, rinsed with CH2Cl2, and the rinse solution was mixed with the filtrate to obtain a mixed solution.

[0073] Add sufficient anhydrous Na₂SO₄ to the mixture, filter, and then distill under reduced pressure to remove THF, yielding a pale yellow crude product. Recrystallize the crude product from methanol to obtain a pale yellow paste, which is the target product, denoted as S1, with a yield of 59.37%.

[0074] The chemical reaction formula is shown below:

[0075]

[0076] The product obtained in Example 1 was characterized by nuclear magnetic resonance [(CD3)2SO, 25°C], and its nuclear 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.

[0077] Example 2

[0078] Under nitrogen protection, 19.614 g, 300 mmol, 1000 mesh activated Zn powder, 7.92 g, 80 mmol CuCl and 1000 mL THF were added to the reactor. The mixture was cooled to -2 °C, stirred, and then 56.90 g, 300 mmol TiCl4 was added. The mixture was heated to 76 °C, refluxed for 6 h, and then cooled to -2 °C again to obtain a low-valent titanium reducing agent.

[0079] 9.91 g (75 mmol) of 2-phenylpropenal (R1, R2, and R are H, R3 is phenyl) and 19.71 g (120 mmol) of 2-adamantanecarboxaldehyde (R0 is H) were dissolved in 250 mL of THF and then mixed into a low-valent titanium reducing agent. The mixture was heated to 76 °C and refluxed for 7.5 h under stirring. After adding 25 mL of 5.0 wt% K₂CO₃ solution, the mixture was filtered through diatomaceous earth. The filtrate was collected and then rinsed with CH₂Cl₂. The rinse solution was mixed with the filtrate to obtain a mixed solution.

[0080] Add sufficient CaSO4 to the mixture, filter, and then distill under reduced pressure to remove THF, yielding a pale yellow crude product. Recrystallize the crude product from methanol to obtain a pale yellow paste, which is the target product, denoted as S2, with a yield of 53.94%.

[0081] The chemical reaction formula is shown below:

[0082]

[0083] The product obtained in Example 2 was characterized by nuclear magnetic resonance [(CD3)2SO, 25°C], and its nuclear 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.

[0084] Example 3

[0085] Under nitrogen protection, 39.23 g, 600 mmol, 600 mesh activated Zn powder, 9.9 g, 100 mmol CuCl and 1000 mL THF were added to the reactor. The mixture was cooled to 0 °C, stirred, and 113.81 g, 600 mmol TiCl4 was added. The mixture was heated to 68 °C and refluxed for 4 h. The mixture was then cooled to 0 °C again to obtain a low-valent titanium reducing agent.

[0086] 11.21g, 200mmol acrolein, R, R 1 R 2 and R 3 All components were H, along with 46.35 g and 260 mmol of 1-adamantane methyl ketone, R0 being CH3, and 400 mL of THF. These were mixed with a low-valent titanium reducing agent, and the mixture was heated to 68 °C and refluxed for 5 h under stirring. After adding 80 mL of a 10.0 wt% K2CO3 solution, the mixture was filtered through diatomaceous earth. The filtrate was collected, then rinsed with CH2Cl2. The rinse solution was mixed with the filtrate to obtain a mixed solution.

[0087] Add sufficient MgSO4 to the mixture, filter, and then distill under reduced pressure to remove THF, yielding a pale yellow crude product. Recrystallize the crude product from ethanol to obtain a pale yellow paste, which is the target product, denoted as S3, with a yield of 61.72%.

[0088] The chemical reaction formula is shown below:

[0089]

[0090] The product obtained in Example 3 was characterized by nuclear magnetic resonance [(CD3)2SO, 25°C], and its nuclear magnetic resonance spectrum was obtained. 1 H NMR such as Figure 3 .according to 1 The H NMR analysis results are consistent with the molecular structure of the target product.

[0091] Example 4

[0092] Under argon protection, 32.69 g, 500 mmol, 750 mesh activated Zn powder, 4.95 g, 50 mmol CuCl and 1000 mL THF were added to the reactor. The mixture was cooled to -10 °C, stirred, and 94.84 g, 500 mmol TiCl4 was added. The mixture was heated to 70 °C and refluxed for 6 h. It was then cooled to -10 °C again to obtain a low-valent titanium reducing agent.

[0093] 21.93 g and 150 mmol of 1-phenyl-2-buten-1-one (R1: H, R2 and R3: CH3, R: phenyl), 37.44 g and 210 mmol of 2-adamantane methyl ketone (R0: CH3), and 360 mL of THF were mixed into a low-valent titanium reducing agent. The mixture was heated to 70 °C and refluxed for 8 h under stirring. After adding 48 mL of 7.5 wt% K2CO3 solution, the mixture was filtered through diatomaceous earth. The filtrate was collected and then rinsed with CH2Cl2. The rinse solution was mixed with the filtrate to obtain a mixed solution.

[0094] Add sufficient CaCl2 to the mixture, filter, and then distill under reduced pressure to remove THF, yielding a pale yellow crude product. Recrystallize the crude product with ethanol to obtain a pale yellow paste, which is the target product, denoted as S4, with a yield of 55.52%.

[0095] The chemical reaction formula is shown below:

[0096]

[0097] The product obtained in Example 4 was characterized by nuclear magnetic resonance [(CD3)2SO, 25°C], and its nuclear magnetic resonance spectrum was obtained. 1 H NMR such as Figure 4 .according to 1 The H NMR analysis results are consistent with the molecular structure of the target product.

[0098] Example 5

[0099] The method of Example 1 was followed, except that 3-methyl-3-buten-2-one was replaced with 2-methylpropenal, and other conditions were the same as in Example 1. The target product was designated as S5, with a yield of 56.15%.

[0100] Example 6

[0101] The method of Example 1 was followed, except that 3-methyl-3-buten-2-one was replaced with 3,4-dimethyl-3-penten-2-one, and the other conditions were the same as in Example 1. The target product was designated as S6, and the yield was 58.28%.

[0102] Example 7

[0103] The method of Example 1 was followed, except that 3-methyl-3-buten-2-one was replaced with 3-methyl-3-penten-2-one, and the other conditions were the same as in Example 1. The target product was designated as S7, and the yield was 60.00%.

[0104] Example 8

[0105] The method of Example 1 was followed, except that 3-methyl-3-buten-2-one was replaced with 3,3-diphenylpropenal, and the other conditions were the same as in Example 1. The target product was designated as S8, and the yield was 61.41%.

[0106] Example 9

[0107] The method of Example 1 was followed, except that 3-methyl-3-buten-2-one was replaced with 3-methyl-2-butenal, and other conditions were the same as in Example 1. The target product was designated as S9, and the yield was 50.64%.

[0108] Example 10

[0109] The method of Example 1 was followed, except that 3-methyl-3-buten-2-one was replaced with 2,3-dimethyl-2-butenal, and other conditions were the same as in Example 1. The target product was designated as S10, with a yield of 53.29%.

[0110] Example 11

[0111] The method of Example 1 was followed, except that 3-methyl-3-buten-2-one was replaced with 3-penten-2-one, and the other conditions were the same as in Example 1. The target product was designated as S11, and the yield was 57.35%.

[0112] Example 12

[0113] The method of Example 1 was followed, except that 3-methyl-3-buten-2-one was replaced with 1,3-diphenyl-2-propenone, and the other conditions were the same as in Example 1. The target product was designated as S12, and the yield was 56.84%.

[0114] Comparative Example 1

[0115] The method of Example 1 was followed, except that 1-adamantane formaldehyde was replaced with lauraldehyde, and other conditions were the same as in Example 1. The target product was designated as D1, with a yield of 53.96%.

[0116] Comparative Example 2

[0117] The method of Example 1 was followed, except that 1-adamantane formaldehyde was replaced with benzaldehyde, and other conditions were the same as in Example 1. The target product was designated as D2, and the yield was 52.11%.

[0118] Comparative Example 3

[0119] The method of Example 1 was followed, except that 1-adamantane formaldehyde was replaced with cyclohexyl formaldehyde, and other conditions were the same as in Example 1. The target product was designated as D3, and the yield was 54.68%.

[0120] Example 13

[0121] This example illustrates the preparation of a thickener.

[0122] In a reactor equipped with a temperature control device, a reflux condenser, and a constant pressure feeding device, 28.43 g and 0.4 mol of acrylamide, 41.45 g and 0.2 mol of 2-acrylamido-2-methylpropanesulfonic acid, and 6.49 g and 0.03 mol of the conjugated crosslinking monomer S1 prepared in Example 1 were sequentially added to 660 mL of dimethyl sulfoxide for mixing and stirring, and the temperature was raised to 67 °C.

[0123] After purging with nitrogen for 30 minutes, 0.76 g of azobis(N,N'-cyclobutylisobutylamididine) hydrate was added to the above mixed solution, and the reaction was continued for 12 hours under stirring to obtain the crude product.

[0124] After adding 600 mL of anhydrous ethanol 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 thickener, denoted as P1.

[0125] Example 14

[0126] This example illustrates the preparation of a thickener.

[0127] In a reactor equipped with a temperature control device, a reflux condenser, and a constant pressure feeding device, 84.61 g and 0.5 mol of diacetone acrylamide, 51.55 g and 0.25 mol of sodium p-styrene sulfonate, and 8.65 g and 0.04 mol of the conjugated crosslinking monomer S1 prepared in Example 1 were sequentially added to 1900 mL of N,N-dimethylacetamide for mixing and stirring, and the temperature was raised to 104 °C.

[0128] After passing N2 for 30 min, 1.6 g of azoisobutylcyanoformamide was added to the above mixed solution, and the reaction was continued for 8 h under stirring to obtain the crude product.

[0129] After adding 1200 mL of anhydrous ethanol 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 thickener, denoted as P2.

[0130] Example 15

[0131] This example illustrates the preparation of a thickener.

[0132] In a reactor equipped with a temperature control device, a reflux condenser, and a constant pressure feeding device, 33.95 g and 0.3 mol of N-isopropylacrylamide, 69.69 g and 0.3 mol of potassium 3-prop-2-enoyloxypropane-1-sulfonate, and 10.82 g and 0.05 mol of the conjugated crosslinking monomer S1 prepared in Example 1 were sequentially added to 1000 mL of 1,4-dioxane for mixing and stirring, and the temperature was raised to 67 °C.

[0133] After purging with nitrogen for 30 minutes, 0.57 g of azobisisovalerate was added to the above mixed solution, and the reaction was continued for 16 hours under stirring to obtain the crude product.

[0134] After adding 600 mL of anhydrous ethanol 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 thickener, denoted as P3.

[0135] Example 16

[0136] This example illustrates the preparation of a thickener.

[0137] In a reactor equipped with a temperature control device, a reflux condenser, and a constant pressure feeding device, 59.48 g and 0.3 mol of N-vinyl-N-methylacetamide, 115.6 g and 0.3 mol of sodium 2-acrylamidooctyl sulfonate, and 10.82 g and 0.01 mol of the conjugated crosslinking monomer S1 prepared in Example 1 were sequentially added to 1065 mL of N,N-dimethylformamide for mixing and stirring, and the temperature was raised to 66 °C.

[0138] After purging with nitrogen for 30 minutes, 2.66 g of dimethyl azobisisobutyrate was added to the above mixed solution, and the reaction was continued for 12 hours under stirring to obtain the crude product.

[0139] After adding 600 mL of anhydrous ethanol 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 thickener, denoted as P4.

[0140] Example 17

[0141] This example illustrates the preparation of a thickener.

[0142] In a reactor equipped with a temperature control device, a reflux condenser, and a constant pressure feeding device, 29.74 g and 0.3 mol of N-ethylacrylamide, 15.82 g and 0.1 mol of sodium methacrylate sulfonate, and 10.82 g and 0.05 mol of the conjugated crosslinking monomer S1 prepared in Example 1 were sequentially added to 1130 mL of N,N-dimethylformamide for mixing and stirring, and the temperature was raised to 86 °C.

[0143] After purging with nitrogen for 30 minutes, 0.45 g of azodimethyl N-2-hydroxybutylacrylamide was added to the above mixed solution, and the reaction was continued for 10.5 h under stirring to obtain the crude product.

[0144] After adding 500 mL of anhydrous ethanol 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 thickener, which was designated as P5.

[0145] Example 18

[0146] This example illustrates the preparation of a thickener.

[0147] In a reactor equipped with a temperature control device, a reflux condenser, and a constant pressure feeding device, 103.93 g and 0.6 mol of N,N-bis(2-hydroxyethyl)methacrylamide, 39.85 g and 0.1 mol of sodium 2-acryloyloxyhexadecyl sulfonate, and 2.64 g and 0.01 mol of the conjugated crosslinking monomer S2 prepared in Example 2 were sequentially added to 3125 mL of tetrahydrofuran for mixing and stirring, and the temperature was raised to 44 °C.

[0148] After passing N2 through for 30 min, 1.2 g of azobisisobutyrazoline hydrochloride was added to the above mixed solution, and the reaction was continued for 16 h under stirring to obtain the crude product.

[0149] After adding 1000 mL of anhydrous ethanol 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 thickener, which was designated as P6.

[0150] Example 19

[0151] This example illustrates the preparation of a thickener.

[0152] In a reactor equipped with a temperature control device, a reflux condenser, and a constant pressure feeding device, 29.79 g and 0.35 mol of N-vinylacetamide, 39.54 g and 0.25 mol of sodium methacrylate sulfonate, and 5.29 g and 0.02 mol of the conjugated crosslinking monomer S2 prepared in Example 2 were sequentially added to 800 mL of dimethyl sulfoxide for mixing and stirring, and the temperature was raised to 52 °C.

[0153] After purging with nitrogen for 30 minutes, 0.8 g of 2,2'-azobis(N-cyclohexylisobutylamidine) hydrochloride was added to the above mixed solution, and the reaction was continued for 15 hours under stirring to obtain the crude product.

[0154] After adding 500 mL of anhydrous ethanol 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 thickener, which was designated as P7.

[0155] Example 20

[0156] This example illustrates the preparation of a thickener.

[0157] In a reactor equipped with a temperature control device, a reflux condenser, and a constant pressure feeding device, 58.12 g and 0.35 mol of N-(2-hydroxypropyl)acrylamide, 44.16 g and 0.18 mol of potassium 2-acrylamido-2-methylpropanesulfonate, and 7.93 g and 0.03 mol of the conjugated crosslinking monomer S2 prepared in Example 2 were sequentially added to 1200 mL of dimethyl sulfoxide for mixing and stirring, and the temperature was raised to 69 °C.

[0158] After purging with nitrogen for 30 minutes, 0.82 g of azodicyanovalerate was added to the above mixed solution, and the reaction was continued for 10 hours under stirring to obtain the crude product.

[0159] After adding 500 mL of anhydrous ethanol 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 thickener, which was designated as P8.

[0160] Example 21

[0161] This example illustrates the preparation of a thickener.

[0162] In a reactor equipped with a temperature control device, a reflux condenser, and a constant pressure feeding device, 60.66 g and 0.6 mol of N-hydroxymethylacrylamide, 43.24 g and 0.3 mol of sodium allyl sulfonate, and 2.02 g and 0.01 mol of the conjugated crosslinking monomer S3 prepared in Example 3 were sequentially added to 860 mL of dimethyl sulfoxide for mixing and stirring, and the temperature was raised to 56 °C.

[0163] After purging with nitrogen for 30 minutes, 0.53 g of azobisisobutylamidine hydrochloride was added to the above mixed solution, and the reaction was continued for 8 hours under stirring to obtain the crude product.

[0164] After adding 800 mL of anhydrous ethanol 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 thickener, which was designated as P9.

[0165] Example 22

[0166] This example illustrates the preparation of a thickener.

[0167] In a reactor equipped with a temperature control device, a reflux condenser, and a constant pressure feeding device, 56.49 g and 0.4 mol of N,N-diethylmethacrylamide, 57.83 g and 0.25 mol of potassium 3-prop-2-enamidopropane-1-sulfonate, and 5.57 g and 0.02 mol of the conjugated crosslinking monomer S4 prepared in Example 4 were sequentially added to 1200 mL of N,N-dimethylacetamide for mixing and stirring, and the temperature was raised to 61 °C.

[0168] After purging with nitrogen for 30 minutes, 0.72 g of azobisisopropylimidazoline was added to the above mixed solution, and the reaction was continued for 12 hours under stirring to obtain the crude product.

[0169] After adding 850 mL of anhydrous ethanol 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 thickener, which was designated as P10.

[0170] Example 23

[0171] The method of Example 13 is followed, except that the conjugated crosslinking monomer S1 is replaced with the conjugated crosslinking monomer S5, and the other conditions are the same as in Example 13. The target product is denoted as P11.

[0172] Example 24

[0173] The method of Example 13 is followed, except that the conjugated crosslinking monomer S1 is replaced with the conjugated crosslinking monomer S6, and other conditions are the same as in Example 13. The target product is denoted as P12.

[0174] Example 25

[0175] The method of Example 13 is followed, except that the conjugated crosslinking monomer S1 is replaced with the conjugated crosslinking monomer S7, and other conditions are the same as in Example 13. The target product is denoted as P13.

[0176] Example 26

[0177] The method of Example 13 is followed, except that the conjugated crosslinking monomer S1 is replaced with the conjugated crosslinking monomer S8, and the other conditions are the same as in Example 13. The target product is denoted as P14.

[0178] Example 27

[0179] The method of Example 13 is followed, except that the conjugated crosslinking monomer S1 is replaced with the conjugated crosslinking monomer S9, and the other conditions are the same as in Example 13. The target product is denoted as P15.

[0180] Example 28

[0181] The method of Example 13 is followed, except that the conjugated crosslinking monomer S1 is replaced with the conjugated crosslinking monomer S10, and other conditions are the same as in Example 13. The target product is denoted as P16.

[0182] Example 29

[0183] The method of Example 13 is followed, except that the conjugated crosslinking monomer S1 is replaced with the conjugated crosslinking monomer S11, and other conditions are the same as in Example 13. The target product is denoted as P17.

[0184] Example 30

[0185] The method of Example 13 is followed, except that the conjugated crosslinking monomer S1 is replaced with the conjugated crosslinking monomer S12, and other conditions are the same as in Example 13. The target product is denoted as P18.

[0186] Comparative Example 4

[0187] The method of Example 13 is followed, except that the conjugated crosslinking monomer S1 is replaced with the conjugated crosslinking monomer D1, and other conditions are the same as in Example 13. The target product is denoted as K1.

[0188] Comparative Example 5

[0189] The method of Example 13 is followed, except that the conjugated crosslinking monomer S1 is replaced with the conjugated crosslinking monomer D2, and other conditions are the same as in Example 13. The target product is denoted as K2.

[0190] Comparative Example 6

[0191] The method of Example 13 is followed, except that the conjugated crosslinking monomer S1 is replaced with the conjugated crosslinking monomer D3, and other conditions are the same as in Example 13. The target product is denoted as K3.

[0192] Test Example 1

[0193] Temperature resistance test

[0194] P1-P18 and K1-K3 were dissolved in water to prepare 0.6% (w / w) viscosity modifier solutions. These solutions were placed in a roller furnace and aged at different temperatures for 16 hours. After cooling to room temperature, they were stirred at 2000 r / min for 5 minutes. The apparent viscosity AV of different experimental slurries was determined using a six-speed rotational viscometer according to the test procedures specified in GB / T 16783.1-2014 "Field Testing of Drilling Fluids Part 1: Water-based Drilling Fluids". The test results are shown in Table 1.

[0195] Table 1. AV (mPa·s) of experimental slurries at different aging temperatures

[0196]

[0197] As can be seen from Table 1, under normal temperature conditions, the AV of each experimental pulp is not much different; as the aging temperature increases, the AV of the experimental pulp gradually decreases; after high-temperature aging, under the same aging temperature conditions, the AV of the experimental pulp containing P1 to P18 is higher than that of the experimental pulp containing K1 to K3, indicating that P1 to P18 have good temperature resistance.

[0198] Test Example 2

[0199] Salt resistance test

[0200] Dissolve P1–P18 and K1–K3 respectively in water or a NaCl solution of a certain concentration to prepare a 0.6% (w / w) thickener solution. Following the test procedures specified in GB 12005.1-89 "Determination of Intrinsic Viscosity of Polyacrylamide", use the one-point method to determine the intrinsic viscosity of different experimental slurries at 30℃. The intrinsic viscosity of the experimental slurry in water is recorded as η0, and the intrinsic viscosity of the experimental slurry in NaCl solution is recorded as η1. Calculate the retention rate Δ of the intrinsic viscosity using the following formula:

[0201]

[0202] The test results are shown in Table 2.

[0203] Table 2. Δ (%) of thickener in NaCl solutions of different concentrations

[0204]

[0205] As shown in Table 2, the Δ value of the experimental pulp decreased continuously with the increase of NaCl concentration. Under the same NaCl concentration conditions, the Δ value of the experimental pulp containing P1 to P18 was higher than that of the experimental pulp containing K1 to K3, indicating that P1 to P18 have good salt resistance.

[0206] There are no particular limitations on the preparation methods not mentioned in this invention. Preparation methods well known to those skilled in the art can be used. These methods will not be elaborated upon here. Specific operations are listed in this invention, but those skilled in the art should not interpret them as limitations on this invention.

[0207] The above description is merely a preferred embodiment of the present invention, showing and describing the basic principles, main features, and advantages of the present invention. It is not intended to limit the scope of patent protection of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. In addition to the above embodiments, the present invention may have other implementations without departing from the spirit and scope of the invention. Various changes and modifications to the present invention are possible, and all technical solutions formed by equivalent substitutions or equivalent transformations fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents. Technical features not described in the present invention can be implemented by or using existing technology, and will not be elaborated here.

Claims

1. A viscosity modifier for solids-free drilling fluids, characterized in that, It is synthesized by polymerization reaction of amide A (represented by formula III), sulfonic acid B (represented by formula IV) and conjugated crosslinking monomer C; The molar ratio of the three is A:B:C = (30-60):(10-30):(1-5); The conjugated crosslinked monomer C has a stereoalkyl structure and a conjugated diene structure, and its molecular formula is formula I-1 or formula I-2: R, R0, R1, R2, and R3 are each -H, C1 to C6 alkyl, or phenyl, respectively; In Formula III: R 1 It is -H or a C1 to C6 alkyl group; R 2 for Among them, 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 to C6 alkyl groups; R d Selected from -CH3, -CH2CH3, One of them; In formula IV: R 3 Selected from -H or C1 to C6 alkyl groups; R 4 Selected from One of them.

2. The thickener for solid-free drilling fluid according to claim 1, characterized in that, For R 4 A is selected from at least one of H, Na, K, Rb or Cs; j, k, l are integers from 0 to 3; m, n are natural numbers from 4 to 14.

3. A method for preparing a thickener for solids-free drilling fluids, characterized in that, The steps are as follows: S1. The amide A, sulfonic acid B and conjugated crosslinking monomer C described in claim 1 are mixed and stirred in solvent C and heated to a predetermined temperature. S2. After purging with nitrogen for 30 minutes, an initiator is added to the above mixed solution, and the reaction continues for 8 to 16 hours to obtain the crude thickener product. S3. After precipitation, washing, extraction and vacuum drying of the crude viscosity improver, a solids-free viscosity improver for drilling fluid is obtained.

4. The method for preparing a thickener for solids-free drilling fluid according to claim 3, characterized in that, The molar ratio of the amide, sulfonic acid, and the above-mentioned conjugated crosslinking monomers for the three structures is (30-60):(10-30):(1-5), the mass percentage concentration of the three conjugated crosslinking monomers in solvent C is 5.0%-15.0%, and the reaction temperature is 44-104℃.

5. The method for preparing a thickener for solids-free drilling fluid according to claim 3, characterized in that, The solvent C is one or more of acetone, tetrahydrofuran, 1,4-dioxane, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

6. The method for preparing a thickener for solids-free drilling fluid according to claim 3, characterized in that, The amount of the initiator added is 0.5% to 1.5% of the total weight of the three structural conjugated crosslinking monomers, and the initiator is one or more of organic peroxide initiators, inorganic peroxide initiators, and oil-soluble redox initiators; Alternatively, the initiator may be an azo initiator, specifically one or more of the following: azobisisobutyrazoline hydrochloride, azoisobutyronitrile, azobisisobutyronitrile, azodimethyl N-2-hydroxybutylacrylamide, azobisisovalerate, azobisisovalerate, azobisisobutyronitrile, azobisisobutyronitrile, azobisisobutyronitrile hydrochloride, azobisisopropylimidazoline, azobis(N,N'-cyclobutylisobutyronitrile) hydrate, dimethyl azobisisobutyrate, and 2,2'-azobis(N-cyclohexylisobutyronitrile) hydrochloride.

7. An application of a viscosity modifier for solids-free drilling fluids, characterized in that, Add the solids-free drilling fluid viscosifier as described in claim 1 or 2, or add the solids-free drilling fluid viscosifier prepared by any one of the preparation methods according to claims 3 to 6; the amount of the viscosifier added is 0.5 wt% to 4.0 wt% based on the total amount of solids-free drilling fluid.

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