Amide polymers, methods of making and using the same, and water-based drilling fluids

Abstract

The application relates to the field of drilling fluids in the petroleum industry, and discloses an amide polymer, which contains structural unit A, structural unit B, structural unit C and structural unit D; the structural unit A is a structural unit with the structure shown in formula (1); the structural unit B is a structural unit with the structure shown in formula (2); the structural unit C is a structural unit with the structure shown in formula (3); and the structural unit D is a structural unit with the structure shown in formula (4). The amide polymer has excellent temperature resistance and calcium resistance, and has excellent filtration reduction performance when applied to drilling fluids.

Description

Technical Field

[0001] This invention relates to the field of drilling in the petroleum industry, specifically to an amide polymer, its preparation method and application, and a water-based drilling fluid. Background Technology

[0002] Compared with conventional drilling fluids containing soil phase, drilling fluids with no or low soil phase have a lower solid content, lower extreme pressure lubrication coefficient, lower circulating pressure loss, larger solid volume, and stronger resistance to environmental pollution. Furthermore, the rheological properties of drilling fluids with no or low soil phase are easier to control at higher densities.

[0003] However, since the drilling fluid system contains no clay or has a very low clay content, it is necessary to select high molecular polymers as thickeners and shearing agents to solve the problem of carrying cuttings and suspended cuttings during drilling, so as to improve the rheological properties of the drilling fluid, enhance its cuttings carrying capacity, thereby ensuring the cleanliness of the wellbore and providing a guarantee for the safety of drilling operations. Therefore, thickeners and shearing agents are the core of the entire low / solids-free drilling fluid treatment agent, and their research has always been a hot topic.

[0004] Currently, thickening and shearing agents can be categorized into modified natural polymer thickeners, synthetic polymer thickeners, and nanomaterial thickening and shearing agents. Modified natural polymer thickeners, depending on the raw materials, can be further divided into modified biopolymers and modified polysaccharides, such as guar gum, xanthan gum, vegan gum, and polysaccharides; synthetic polymer thickeners with high-temperature resistance include polyacrylamide and its related derivatives.

[0005] However, under conditions of high temperature and high calcium, the effects of the above-mentioned thickening and cutting agents are not ideal. Therefore, there is an urgent need to develop a temperature- and calcium-resistant thickening and cutting agent to meet current market demands. Summary of the Invention

[0006] The purpose of this invention is to solve the problem of poor temperature resistance and calcium resistance of existing cutting agents.

[0007] To achieve the above objectives, a first aspect of the present invention provides an amide polymer containing structural unit A, structural unit B, structural unit C, and structural unit D; wherein the molar ratio of the contents of structural unit A, structural unit B, structural unit C, and structural unit D is 1:0.125-10:0.0625-5:0.125-0.5.

[0008] The structural unit A is a structural unit with the structure shown in equation (1); the structural unit B is a structural unit with the structure shown in equation (2); the structural unit C is a structural unit with the structure shown in equation (3); and the structural unit D is a structural unit with the structure shown in equation (4).

[0009]

[0010] In equation (1), each R 1 Each is independently selected from H and C 1-6 Alkyl group; R 2 Selected from C 1-6 alkylene; R 3 Selected from H, C 1-8 Alkyl groups; M1 is selected from H or alkali metal elements;

[0011] In equation (2), each R 4 Each is independently selected from H and C 1-6 Alkyl group; R 5 Selected from H, C 1-6 Alkyl groups;

[0012] In equation (3), each R 6 Each is independently selected from H and C 1-6 Alkyl groups;

[0013] In equation (4), each R 7 Each is independently selected from H and C 1-6 Alkyl group; R 8 Selected from H, C 1-6 Alkyl groups.

[0014] A second aspect of the present invention provides a method for preparing amide polymers, the method comprising:

[0015] (1) In the presence of a solvent and a protective atmosphere, aqueous solutions of monomers D', B, C and A' are first mixed to obtain mixture I; the pH value of the aqueous solution of monomer A' in the initial system of the first mixing is 7-8;

[0016] (2) In the presence of an initiator and a surfactant, the mixture I undergoes a polymerization reaction to obtain the amide polymer;

[0017] The monomer A' is selected from monomers having the structure shown in formula (I); the monomer B' is selected from monomers having the structure shown in formula (II); the monomer C' is selected from monomers having the structure shown in formula (III); the monomer D' is selected from monomers having the structure shown in formula (IV);

[0018] The monomers A', B', C', and D' respectively ensure that the prepared polymer contains structural unit A, structural unit B, structural unit C, and structural unit D, and that the molar ratio of the contents of structural unit A, structural unit B, structural unit C, and structural unit D in the prepared polymer is 1:0.125-10:0.0625-5:0.125-0.5;

[0019] The structural unit A is a structural unit with the structure shown in equation (1); the structural unit B is a structural unit with the structure shown in equation (2); the structural unit C is a structural unit with the structure shown in equation (3); and the structural unit D is a structural unit with the structure shown in equation (4).

[0020]

[0021]

[0022] Among them, R 1 R 2 R 3 R 4 R 5 R 6 R 7 R 8 The definition of M1 is the same as the definition described in the first aspect.

[0023] The third aspect of the present invention provides an amide polymer prepared by the method described in the second aspect.

[0024] The fourth aspect of the present invention provides the application of the amide polymers described in the first and third aspects as cutting agents in drilling fluids.

[0025] The fifth aspect of the present invention provides a water-based drilling fluid containing an effective amount of the amide polymers described in the first and third aspects for thickening and shearing.

[0026] The amide polymers provided by this invention have excellent temperature and calcium resistance, and exhibit excellent filtration loss reduction performance when applied to drilling fluids. Detailed Implementation

[0027] 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.

[0028] The following provides some exemplary explanations for certain functional groups of the present invention. Unless otherwise specified, the unlisted parts are explained with reference to the following exemplary explanations.

[0029] “C 1-6"Alkyl" refers to a straight-chain alkyl or branched alkyl group with a total number of carbon atoms of 1, 2, 3, 4, 5, or 6. Examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, etc.

[0030] “C 1-6 "alkylene" refers to a straight-chain alkyl or branched alkyl with a total number of carbon atoms of 1, 2, 3, 4, 5 or 6; for example, -CH2-, -CH2-CH2-, -CH2-CH2-CH2-, -CH(CH3)-CH2-, -CH2-CH(CH3)-, -CH2-(CH2)2-CH2-, -C(CH3)2-CH2-, -CH2-C(CH3)2-, etc.

[0031] As previously described, a first aspect of the present invention provides an amide polymer containing structural unit A, structural unit B, structural unit C, and structural unit D; wherein the molar ratio of the contents of structural unit A, structural unit B, structural unit C, and structural unit D is 1:0.125-10:0.0625-5:0.125-0.5.

[0032] The structural unit A is a structural unit with the structure shown in equation (1); the structural unit B is a structural unit with the structure shown in equation (2); the structural unit C is a structural unit with the structure shown in equation (3); and the structural unit D is a structural unit with the structure shown in equation (4).

[0033]

[0034] In equation (1), each R 1 Each is independently selected from H and C 1-6 Alkyl group; R 2 Selected from C 1-6 alkylene; R 3 Selected from H, C 1-8 Alkyl groups; M1 is selected from H or alkali metal elements;

[0035] In equation (2), each R 4 Each is independently selected from H and C 1-6 Alkyl group; R 5 Selected from H, C 1-6 Alkyl groups;

[0036] In equation (3), each R 6 Each is independently selected from H and C 1-6 Alkyl groups;

[0037] In equation (4), each R 7 Each is independently selected from H and C 1-6 Alkyl group; R 8 Selected from H, C1-6 Alkyl groups.

[0038] Preferably, in equation (1), each R 1 Each is independently selected from H, -CH3, -CH2CH3, -CH2CH2CH3; R 2 Selected from -CH2-, -CH2-CH2-, -CH2-CH2-CH2-; R 3 Selected from H, -CH3, -CH2CH3, -CH2CH2CH3; M1 is selected from H, K, Na;

[0039] In equation (2), each R 4 Each is independently selected from H, -CH3, -CH2CH3, -CH2CH2CH3; R 5 Selected from H, -CH3, -CH2CH3, -CH2CH2CH3;

[0040] In equation (3), each R 6 Each is independently selected from H, -CH3, -CH2CH3, and -CH2CH2CH3;

[0041] In equation (4), each R 7 Each is independently selected from H, -CH3, -CH2CH3, -CH2CH2CH3; R 8 Selected from H, -CH3, -CH2CH3, -CH2CH2CH3.

[0042] More preferably, the structural unit A is selected from the structure shown in equation (1-1), the structure shown in equation (1-2), the structure shown in equation (1-3), the structure shown in equation (1-4), the structure shown in equation (1-5), the structure shown in equation (1-6), the structure shown in equation (1-7), the structure shown in equation (1-8), the structure shown in equation (1-9), the structure shown in equation (1-10), the structure shown in equation (1-11), the structure shown in equation (1-12), the structure shown in equation (1-13), the structure shown in equation (1-14), and the structure shown in equation (1-15). At least one of the structural units of the structures shown in (1-15), (1-16), (1-17), (1-18), (1-19), (1-20), (1-21), (1-22), (1-23), (1-24), (1-25), (1-26), (1-27), and (1-28);

[0043] The structural unit B is selected from at least one of the structural units shown in formula (2-1), formula (2-2), formula (2-3), formula (2-4), formula (2-5), formula (2-6), formula (2-7), formula (2-8), and formula (2-9);

[0044] The structural unit C is selected from at least one of the structural units shown in formula (3-1), formula (3-2), formula (3-3), formula (3-4), and formula (3-5);

[0045] The structural unit D is selected from at least one of the structural units shown in formula (4-1), formula (4-2), formula (4-3), formula (4-4), formula (4-5), formula (4-6), formula (4-7), formula (4-8), formula (4-9), and formula (4-10).

[0046] Equation (1-1): R 1 Both are H; R 2 -CH2-; R 3 H is H; M1 is H;

[0047] Equation (1-2): R 1 Both are H; R 2 -CH2-; R 3 H is H; M1 is K;

[0048] Equation (1-3): R 1 Both are H; R 2 -CH2-; R 3 M1 is H; M2 is Na;

[0049] Equation (1-4): R 1 Both are H; R 2 -CH2-; R 3 M1 is -CH3; M2 is H;

[0050] Equation (1-5): R 1 Both are H; R 2 -CH2-; R 3 M1 is -CH3; M2 is K;

[0051] Equation (1-6): R 1 Both are H; R 2 -CH2-; R 3 M1 is -CH3; M2 is Na;

[0052] Equation (1-7): R 1 Both are H; R2 -CH2-; R 3 M1 is -CH2CH3; M2 is H;

[0053] Equation (1-8): R 1 Both are H; R 2 -CH2-; R 3 M1 is -CH2CH3; M1 is K;

[0054] Equation (1-9): R 1 Both are H; R 2 -CH2-; R 3 M1 is -CH2CH3; M2 is Na;

[0055] Equation (1-10): R 1 All are -CH3; R 2 -CH2-; R 3 H is H; M1 is H;

[0056] Equation (1-11): R 1 All are -CH3; R 2 -CH2-; R 3 H is H; M1 is K;

[0057] Equation (1-12): R 1 All are -CH3; R 2 -CH2-; R 3 M1 is H; M2 is Na;

[0058] Equation (1-13): R 1 All are -CH3; R 2 -CH2-; R 3 M1 is -CH3; M2 is H;

[0059] Equation (1-14): R 1 All are -CH3; R 2 -CH2-; R 3 M1 is -CH3; M2 is K;

[0060] Equation (1-15): R 1 All are -CH3; R 2 -CH2-; R 3 M1 is -CH3; M2 is Na;

[0061] Equation (1-16): R 1 All are -CH3; R 2 -CH2-; R 3 M1 is -CH2CH3; M2 is H;

[0062] Equation (1-17): R 1All are -CH3; R 2 -CH2-; R 3 M1 is -CH2CH3; M1 is K;

[0063] Equation (1-18): R 1 All are -CH3; R 2 -CH2-; R 3 M1 is -CH2CH3; M2 is Na;

[0064] Equation (1-19): R 1 All are -CH2CH3; R 2 -CH2-; R 3 H is H; M1 is H;

[0065] Equation (1-20): R 1 All are -CH2CH3; R 2 -CH2-; R 3 H is H; M1 is K;

[0066] Equation (1-21): R 1 All are -CH2CH3; R 2 -CH2-; R 3 M1 is H; M2 is Na;

[0067] Equation (1-22): R 1 All are -CH2CH3; R 2 -CH2-; R 3 M1 is -CH3; M2 is H;

[0068] Equation (1-23): R 1 All are -CH2CH3; R 2 -CH2-; R 3 M1 is -CH3; M2 is K;

[0069] Equation (1-24): R 1 All are -CH2CH3; R 2 -CH2-; R 3 M1 is -CH3; M1 is Na; Equation (1-25): R 1 All are -CH2CH3; R 2 -CH2-; R 3 =-CH2CH3; M1 is H; Equation (1-26): R 1 All are -CH2CH3; R 2 -CH2-; R 3 =-CH2CH3; M1 is K; Equation (1-27): R 1 All are -CH2CH3; R 2 -CH2-; R3 M1 is -CH2CH3; M1 is Na; Equation (1-28): Equation (2-1): R 4 Both are H; R 5 For H;

[0070] Equation (2-2): R 4 Both are H; R 5 -CH3;

[0071] Equation (2-3): R 4 Both are H; R 5 It is -CH2CH3;

[0072] Equation (2-4): R 4 All are -CH3; R 5 -CH3;

[0073] Equation (2-5): R 4 All are -CH3; R 5 It is -CH2CH3;

[0074] Equation (2-6): R 4 All are -CH2CH3; R 5 It is -CH2CH3;

[0075] Equation (2-7): R 4 Both are -CH2CH2CH3; R 5 It is -CH2CH3;

[0076] Equation (2-8): R 4 Both are -CH2CH2CH3; R 5 It is -CH2CH2CH3;

[0077] Equation (2-9): Equation (3-1): R 6 All are H;

[0078] Equation (3-2): R 6 All are -CH3;

[0079] Equation (3-3): R 6 All are -CH2CH3;

[0080] Equation (3-4): R 6 All are -CH2CH2CH3;

[0081] Equation (3-5): R 6 All are -CH2CH2CH2CH3;

[0082] Equation (4-1): R 7 Both are H; R7 For H;

[0083] Equation (4-2): R 7 All are -CH3; R 8 For H;

[0084] Equation (4-3): R 7 All are -CH2CH3; R 8 For H

[0085] Equation (4-4): R 7 Both are -CH2CH2CH3; R 8 For H

[0086] Equation (4-5): R 7 All are -CH3; R 8 -CH3;

[0087] Equation (4-6): R 7 All are -CH2CH3; R 8 -CH3;

[0088] Equation (4-7): R 7 All are -CH2CH3; R 8 It is -CH2CH3;

[0089] Equation (4-8): R 7 Both are -CH2CH2CH3; R 8 It is -CH2CH3;

[0090] Equation (4-9): R 7 Both are -CH2CH2CH3; R 8 It is -CH2CH2CH3;

[0091] Equation (4-10):

[0092] In a preferred embodiment, the molar ratio of structural unit A, structural unit B, structural unit C, and structural unit D is 1:0.25-5:0.08-3:0.125-0.3. The inventors have found that, under this preferred embodiment, the amide polymer obtained by this invention exhibits better thickening and shear-enhancing properties, while also showing improved filtration loss reduction due to the thickening effect, resulting in better rheological properties and filtration loss reduction performance when applied to drilling fluids.

[0093] As previously described, a second aspect of the present invention provides a method for preparing amide polymers, the method comprising:

[0094] (1) Under a protective atmosphere, aqueous solutions of monomers D', B, C and A' are first mixed to obtain mixture I; the pH of the aqueous solution of monomer A' in the initial system of the first mixing is 7-8.

[0095] (2) In the presence of an initiator and a surfactant, the mixture I undergoes a polymerization reaction to obtain the amide polymer;

[0096] The monomer A' is selected from monomers having the structure shown in formula (I); the monomer B' is selected from monomers having the structure shown in formula (II); the monomer C' is selected from monomers having the structure shown in formula (III); the monomer D' is selected from monomers having the structure shown in formula (IV);

[0097] The monomers A', B', C', and D' respectively ensure that the prepared polymer contains structural unit A, structural unit B, structural unit C, and structural unit D, and that the molar ratio of the contents of structural unit A, structural unit B, structural unit C, and structural unit D in the prepared polymer is 1:0.125-10:0.0625-5:0.125-0.5;

[0098] The structural unit A is a structural unit with the structure shown in equation (1); the structural unit B is a structural unit with the structure shown in equation (2); the structural unit C is a structural unit with the structure shown in equation (3); and the structural unit D is a structural unit with the structure shown in equation (4).

[0099]

[0100]

[0101] Among them, R 1 R 2 R 3 R 4 R 5 R 6 R 7 R 8 The definition of M1 is the same as the definition described in the first aspect above.

[0102] Preferably, the protective atmosphere is selected from at least one of nitrogen and argon.

[0103] In a preferred embodiment, in step (1), the conditions for the first mixing include: a temperature of 50°C-70°C, a time of 5h-7h, and a stirring speed of 300-350rpm.

[0104] Preferably, the polymerization reaction is carried out under stirring conditions, which include: stirring speed of 300-500 rpm, temperature of 50-70℃, and time of 5-7 h.

[0105] It should be noted that, in this invention, the pH value of the aqueous solution of monomer A' in the initial system of the first mixing process, which is between 7 and 8, can be adjusted using conventional acid-base adjustment methods in the art. These methods will not be elaborated upon here, and those skilled in the art should not interpret them as limitations on this invention.

[0106] In the preferred embodiment, the double bonds of monomers D', B, C, and A' all participate in the polymerization reaction. During the polymerization process, the linear molecules can be linked together to form a cross-linked network structure, which increases the strength and plays a role in regulating the physical properties and improving the chemical stability of the amide polymer.

[0107] In the method described in the second aspect of the present invention, the relevant definitions and types of substituents of the monomers with the structure shown in formula (I), the monomers with the structure shown in formula (III), the monomers with the structure shown in formula (IIV), and the monomers with the structure shown in formula (IV) correspond to the relevant definitions and types of substituents of the present invention as described above. The present invention will not repeat them here, and those skilled in the art should not understand them as limitations on the technical solutions of the present invention.

[0108] In this invention, monomers A', B', C', and D' can be commercially available or synthesized using known methods in the field of organic synthesis based on the structural formula provided by this invention.

[0109] In this invention, it should be noted that the monomer is almost completely converted into the corresponding structural unit contained in the polymer, and the amount of the monomer can be consistent with the content of the corresponding structural unit contained in the polymer.

[0110] Preferably, the initiator is selected from at least one of haloalkanes, 2-ketoglutaric acid, potassium persulfate, cerium ammonium nitrate, and azobisisobutyramidine hydrochloride.

[0111] More preferably, in the aqueous solution of the monomer A', the amount of water used is 100-150 mL relative to 1 mol of the monomer A'.

[0112] Preferably, the amount of the initiator is 0.1-0.2 wt%, based on the total mass of monomers A', B', C' and D'.

[0113] Preferably, the amount of surfactant used is 0.00125-0.05 mol relative to each mol of monomer A'.

[0114] More preferably, the surfactant is selected from at least one of sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfonate (SDBS), and sodium p-styrene sulfonate (SSS).

[0115] It should be noted that the method for preparing gel polymers in this invention also includes conventional post-processing methods, such as drying and pulverizing to the particle size required for application. These will not be described in detail here, and those skilled in the art should not understand them as limitations on this invention.

[0116] As previously stated, a third aspect of the present invention provides an amide polymer prepared by the method described in the second aspect above.

[0117] Preferably, the number-average molecular weight of the amide polymer is 250,000 to 400,000.

[0118] As previously stated, the fourth aspect of the present invention provides the application of the amide polymers described in the first and third aspects above as cutting agents in drilling fluids.

[0119] As mentioned above, the fifth aspect of the present invention provides a water-based drilling fluid containing an effective amount of the amide polymer described in the first and third aspects above for thickening and shearing.

[0120] Preferably, the water-based drilling fluid contains water, amide polymers, filtration reducers, inhibitors, and pH adjusters; optionally, it also contains weighting agents.

[0121] The amide polymer comprises, relative to 300 parts by weight of water, 8-12 parts by weight of water, 24-30 parts by weight of water, 4-8 parts by weight of water, 0-20 parts by weight of water, and 0.5-3 parts by weight of water; the amide polymer is the amide polymer described in the first and third aspects above.

[0122] More preferably, the filtration loss reducing agent is selected from at least one of carboxymethyl cellulose, potassium humate, sulfonated phenolic resin, and carboxymethyl starch; the pH adjuster is NaOH; the inhibitor is selected from at least one of potassium chloride and sodium humate; and the weighting agent is selected from at least one of calcium chloride and calcium carbonate.

[0123] In this invention, there are no particular limitations on the preparation method of the drilling fluid. Preparation methods well known to those skilled in the art can be used, and will not be described in detail here. Furthermore, a specific operation is listed below, which should not be construed as a limitation of this invention.

[0124] The present invention will be described in detail below through examples. Unless otherwise specified, all raw materials and reagents used in the following examples are commercially available products.

[0125] Example 1

[0126] Monomer A': The structure shown in equation (I) is: Among them, M1 is H, CAS number: 15214-89-8, purchased from Beijing Innocare Technology Co., Ltd.;

[0127] Monomer B': Has the structure shown in formula (II), with the following structural formula: The CAS number is 7398-69-8, and it was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0128] Monomer C': Has the structure shown in equation (III), with the following structural formula: The CAS number is 88-12-0, and it was purchased from Shanghai Titan Technology Co., Ltd.

[0129] Monomer D': The structure shown in equation (IV) is: The CAS number is 2680-03-7, purchased from Beijing Xinbaohai Chemical Technology Co., Ltd.

[0130] (1) Dissolve 1 mol of monomer A' in 100 mL of water and adjust the pH to 7 with NaOH; then, under the protection of nitrogen, mix the aqueous solutions of monomer D', monomer B, monomer C and monomer A' to obtain mixture I; the conditions for the first mixing are: temperature 70℃, time 7h, and stirring speed 350rpm.

[0131] (2) The initiator (potassium persulfate), 0.00125 mol of surfactant (sodium dodecyl sulfate) and the mixture I were subjected to a polymerization reaction. The resulting product was dried and pulverized in sequence to obtain amide polymer S1. The conditions for the polymerization reaction were: stirring speed of 350 rpm, temperature of 70°C and time of 7 h.

[0132] Based on the total mass of monomers A', B', C', and D', the amount of initiator is 0.1 wt%.

[0133] The molar ratio of monomer A', monomer B', monomer C', and monomer D' is 1:0.25:0.08:0.125;

[0134] The number-average molecular weight of amide polymer S1 is 400,000;

[0135] Example 2

[0136] Monomer A': Same as in Example 1;

[0137] Monomer B': Same as in Example 1;

[0138] Monomer C': Same as in Example 1;

[0139] Monomer D': The CAS number is 79-06-1, and it was purchased from Beijing Xinbaohai Chemical Technology Co., Ltd.

[0140] (1) Dissolve 1 mol of monomer A' in 150 mL of water and adjust the pH to 8 with NaOH; then, under the protection of nitrogen, mix the aqueous solutions of monomer D', monomer B, monomer C and monomer A' to obtain mixture I; the conditions for the first mixing are: temperature 50℃, time 5h, and stirring speed 300 rpm.

[0141] (2) The initiator (potassium persulfate), 0.05 mol of surfactant (sodium dodecylbenzenesulfonate) and the mixture I were subjected to a polymerization reaction. The resulting product was dried and pulverized in sequence to obtain amide polymer S2. The conditions for the polymerization reaction were: stirring speed of 400 rpm, temperature of 65°C and time of 5 h.

[0142] Based on the total mass of monomers A', B', C', and D', the amount of initiator is 0.2 wt%.

[0143] The molar ratio of monomer A', monomer B', monomer C', and monomer D' is 1:5:3:0.3;

[0144] The number-average molecular weight of amide polymer S2 is 320,000.

[0145] Example 3

[0146] This embodiment follows a similar process to Embodiment 1. The difference is that in this embodiment, the amount of monomer A' is controlled in the same way as in Embodiment 1, but the molar ratio of monomer A', monomer B', monomer C' and monomer D' is 1:8:0.08:0.125.

[0147] Everything else is the same as in Example 1.

[0148] An amide polymer S3 was prepared with a number-average molecular weight of 300,000.

[0149] Example 4

[0150] This embodiment follows a similar process to Embodiment 1. The difference is that in this embodiment, the amount of monomer A' is controlled in the same way as in Embodiment 1, but the molar ratio of monomer A', monomer B', monomer C' and monomer D' is 1:0.25:5:0.125.

[0151] Everything else is the same as in Example 1.

[0152] An amide polymer S4 was prepared with a number-average molecular weight of 350,000.

[0153] Example 5

[0154] This embodiment follows a similar process to Embodiment 1, except that the types of monomers used are different. Specifically:

[0155] Monomer A': Same as in Example 1;

[0156] Monomer B': Product number 20241125, purchased from Shandong Xiya Chemical Co., Ltd.;

[0157] Monomer C': Same as in Example 1;

[0158] Monomer D': Same as in Example 2.

[0159] Everything else is the same as in Example 1.

[0160] An amide polymer S5 was prepared with a number-average molecular weight of 200,000.

[0161] Comparative Example 1

[0162] This comparative example follows a similar process to Example 1, except that monomer A' is not added in this comparative example.

[0163] Everything else is the same as in Example 1.

[0164] Polymer DS1 was prepared.

[0165] Comparative Example 2

[0166] This comparative example follows a similar process to Example 1, except that monomer B' is not added in this comparative example.

[0167] Everything else is the same as in Example 1.

[0168] Polymer DS2 was prepared.

[0169] Comparative Example 3

[0170] This comparative example follows a similar process to Example 1, except that monomer C' is not added in this comparative example.

[0171] Everything else is the same as in Example 1.

[0172] Polymer DS3 was prepared.

[0173] Comparative Example 4

[0174] This comparative example follows a similar process to Example 1, except that monomer D' is not added in this comparative example.

[0175] Everything else is the same as in Example 1.

[0176] Polymer DS4 was prepared.

[0177] Comparative Example 5

[0178] This comparative example follows a similar process to Example 1. The difference is that the amount of monomer A' is controlled in the same way as in Example 1, but the molar ratio of monomer A', monomer B', monomer C' and monomer D' is 1:0.1:6:0.6.

[0179] Everything else is the same as in Example 1.

[0180] Polymer DS5 was prepared.

[0181] Test case

[0182] This test example illustrates the rheological properties of the amide polymers prepared in the above examples before and after aging at 180°C.

[0183] Test method: Take 9g of the amide polymer prepared in the above examples and comparative examples and stir it with 300g of deionized water at 5000rpm for 20min. Measure the changes in its rheological properties before and after aging at 180℃.

[0184] The testing instrument was a six-speed viscometer (model: ZNN-D6B; manufacturer: Qingdao Tongchun Petroleum Instrument Co., Ltd., maximum test range: 300), and the testing standard was GB / T29170-2012.

[0185] The test items included: apparent viscosity (AV(mPa·S)), plastic viscosity (PV(mPa·S)), dynamic shear force (YP(Pa)), and dynamic-plastic ratio. Higher viscosity and dynamic shear force indicate better rock-carrying performance. The test results are shown in Table 1.

[0186] Table 1

[0187]

[0188] As can be seen from the results in Table 1, the amide polymers provided by this invention exhibit better rheological properties before and after aging at 180°C.

[0189] Test Example 2

[0190] This test example is used to exemplify the viscosity changes of the amide polymer S1 provided in Example 1, the amide polymer S4 provided in Example 4, and the polymer DS1 provided in Comparative Example 1 before and after aging at 180°C under different calcium addition amounts.

[0191] Test method: Take 9g of the polymer obtained in the above example and 300g of deionized water and stir at 5000rpm for 15min; then add CaCl2 (the amount added varies in different test systems, see Table 2 for details), change the rotation speed to 1000r / min, and measure the changes in rheological properties before and after aging at 180℃ after 5min; the test items and test standards are the same as in test example 1, and the test results are shown in Table 2.

[0192] Table 2

[0193]

[0194] Table 2 (continued)

[0195]

[0196] Table 2 (continued)

[0197]

[0198] As can be seen from Table 2, the amide polymers provided by this invention have superior thickening and shearing properties, and also better temperature and calcium resistance.

[0199] Test Example 3

[0200] This test example illustrates the changes in the thickening and shearing capacity of the amide polymer S1 provided in Example 1 of the present invention before and after aging at 180℃, 150℃, 120℃, and 100℃ for 16 hours. The test methods and test items are the same as in Test Example 1; the test results are shown in Table 3.

[0201] Table 3

[0202]

[0203] As shown in Table 3, the amide polymer S1 exhibits good temperature resistance; after aging at different temperatures, its six-speed data readings all exceeded the range, with the viscosity exceeding 150. mPa·S， This indicates that it has good thickening ability after aging.

[0204] Test Example 3

[0205] This test example is used to exemplify the viscosity-enhancing, shear-lifting, and filtration loss-reducing performance test of the amide polymer S1 provided in Example 1 of the present invention after being applied to water-based drilling fluid.

[0206] Test method:

[0207] System 1: 300g water + 9g amide polymer S1 + 27g filtration loss reducer (sulfonated phenolic resin) + 6g inhibitor (potassium chloride) + 12g weighting agent (1000 mesh CaCO3) + 1.2g pH adjuster (NaOH).

[0208] System 2: 300g water + 27g filtration loss reducer (sulfonated phenolic resin) + 6g inhibitor (potassium chloride) + 12g weighting agent (1000 mesh CaCO3) + 1.2g pH adjuster (NaOH).

[0209] The thickening, shearing and filtration loss reduction properties of System 1 and System 2 were tested according to GB / T29170-2012. The test results are shown in Table 4.

[0210] Table 4

[0211] System 1 75 55 20.4 0.37 2.8 9.5 System 2 20 15 5.1 0.34 10 55

[0212] As can be seen from Table 4, the amide polymers provided by this invention can improve the rheological properties and reduce filtration loss of the system when applied to drilling fluids.

[0213] 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 method for preparing an amide-based polymer, characterized by, The method includes: (1) Under a protective atmosphere, aqueous solutions of monomers D', B', C' and A' are first mixed to obtain mixture I; the pH of the aqueous solution of monomer A' in the initial system of the first mixing is 7-8; (2) In the presence of an initiator and a surfactant, the mixture I undergoes a polymerization reaction to obtain the amide polymer; the polymerization reaction is carried out under stirring conditions, the stirring speed being 300-500 rpm, the temperature being 50-70°C, and the time being 5-7 h. The monomer A' is selected from monomers having the structure shown in formula (1); the monomer B' is selected from monomers having the structure shown in formula (2); the monomer C' is selected from monomers having the structure shown in formula (ⅠⅠⅠ); the monomer D' is selected from N,N-dimethylacrylamide or acrylamide; The monomers A', B', C', and D' respectively ensure that the prepared polymer contains structural unit A, structural unit B, structural unit C, and structural unit D, and that the molar ratio of the contents of structural unit A, structural unit B, structural unit C, and structural unit D in the prepared polymer is 1:0.25-5:0.08-3:0.125-0.3; The structural unit A is a structural unit provided by a monomer having the structure shown in formula (1); the structural unit B is a structural unit provided by a monomer having the structure shown in formula (2); the structural unit C is a structural unit having the structure shown in formula (3); the structural unit D is a structural unit provided by N,N-dimethylacrylamide or acrylamide. Formula (1): , Formula (2): , (Formula III), (Formula 3); In formula (1), M1is selected from H, K, Na; in formula (3), R 6 are both H; The number-average molecular weight of the amide polymer is 250,000 to 400,000.

2. The method of claim 1, wherein, The initiator is selected from at least one of potassium persulfate, cerium ammonium nitrate, and azobisisobutyramidine hydrochloride.

3. The method according to claim 1 or 2, characterized in that, Based on the total mass of monomers A', B', C', and D', the amount of initiator is 0.1-0.2 wt%. And / or, the amount of the surfactant used is 0.00125-0.05 mol relative to each mol of the monomer A'.

4. An amide polymer prepared by the method according to any one of claims 1-3.

5. The application of the amide polymer of claim 4 as a thickening and shearing agent in drilling fluid.

6. A water-based drilling fluid, characterized by The water-based drilling fluid contains an effective amount of the amide polymer described in claim 4 for thickening and shearing.

7. The water-based drilling fluid of claim 6, wherein, This water-based drilling fluid contains water, amide polymers, filtration reducers, inhibitors, and pH adjusters; optionally, it also contains weighting agents. The amide polymer comprises, relative to 300 parts by weight of water, 8-12 parts by weight of water, 24-30 parts by weight of water, 4-8 parts by weight of water, 0-20 parts by weight of water, and 0.5-3 parts by weight of water; the amide polymer is the amide polymer according to claim 4.

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