Gel polymers, their preparation methods and applications, and water-based drilling fluids

Abstract

This invention relates to the field of drilling in the petroleum industry, and discloses a gel polymer, its preparation method and application, and a water-based drilling fluid. The polymer contains structural units A, B, C, and D; structural unit A has the structure shown in formula (1); structural unit B has the structure shown in formula (2); structural unit C has the structure shown in formula (3); and structural unit D has the structure shown in formula (4). The gel polymer provided by this invention can achieve temperature-responsive expansion, and when applied to drilling fluid, it can effectively improve the sealing effect and aging performance of drilling fluid with large pores.

Description

Technical Field

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

[0002] In modern oil drilling engineering, the application of high-temperature water-based drilling fluids is becoming increasingly widespread. These fluids possess excellent rheological and lubricating properties, effectively cooling the drill bit and carrying away cuttings. However, under high-temperature and high-pressure environments, drilling often faces the problem of lost circulation, leading to reduced drilling efficiency and increased costs. With the increasing prevalence of deep wells and high-temperature, high-pressure environments, the use of traditional drilling fluids faces numerous challenges. To address the problem of plugging lost circulation under extreme high-temperature environments, researchers have begun to focus on the application of temperature-responsive materials. Among these, expandable polymer gel-type plugging materials have become an important research direction due to their excellent temperature adaptability and good rheological properties.

[0003] Therefore, developing a highly efficient plugging material is particularly important. Expandable polymer gel-type plugging materials, due to their excellent physicochemical properties, have become an ideal choice for solving this problem. These materials expand rapidly upon contact with water-based drilling fluids, forming a stable gel plugging layer that effectively seals cracks and pores, preventing fluid loss. Their superior high-temperature resistance ensures good plugging performance even under extreme conditions.

[0004] In addition, expanded polymer gel materials generally have a lower environmental impact, meet the requirements of sustainable development, and provide strong support for the safety and environmental protection of the oil and gas extraction industry.

[0005] Currently used sealing materials have poor deformability and cannot form a dense sealing layer for complex cracks of varying sizes.

[0006] Compared to conventional plugging agents, expandable polymer gel materials are not limited by leakage channels and can enter cracks and pores through extrusion deformation, expanding and blocking leakage channels, which has significant advantages. However, common expandable gel plugging materials expand too quickly, with excessively large expansion ratios and uncontrollable expansion, often expanding before reaching the leakage layer, severely reducing the material's migration and sealing capabilities. Existing expandable gel plugging technologies have low success rates in one-time plugging and cannot effectively seal formation pore throats and fractures, resulting in poor performance.

[0007] In summary, there is an urgent need to develop responsive expandable polymer plugging materials that can expand in response to changes in formation temperature, forming a solid plugging layer under extreme operating conditions (200℃) to effectively reduce leakage. This would not only improve drilling efficiency but also effectively reduce costs and risks, which is of great significance for promoting the advancement of oil drilling technology. Summary of the Invention

[0008] The purpose of this invention is to solve the problems of poor sealing effect, poor aging performance, and lack of temperature-responsive expansion in existing polymer gel-type sealing materials.

[0009] To achieve the above objectives, the first aspect of the present invention provides a gel 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 1:0.5-2:0.1-1:0.05-0.5.

[0010] 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).

[0011]

[0012]

[0013] in,

[0014] In equation (1), R 1 Selected from C 1-6 alkylene, -R 10 -O-;R 10 Selected from C 0-6 Alkylene; each R 2 Each is independently selected from H and C. 1-6 Alkyl group; X is a halogen element;

[0015] In equation (2), each R 3 Each is independently selected from H and C 1-6 Alkyl group; M is selected from H or an alkali metal element;

[0016] In equation (3), each R 4 Each is independently selected from H and C. 1-6 Alkyl group; R 5 Selected from C 0-6 alkylene; R 6 Selected from H, C 1-6 Alkyl groups;

[0017] In equation (4), each R 7 Each was independently selected from C 0-6 Alkylene; each R 8 Each is independently selected from H and C. 1-6 Alkyl groups; each R 9Each is independently selected from H, amino, or C. 1-6 Alkyl groups.

[0018] A second aspect of the present invention provides a method for preparing a gel polymer, the method comprising:

[0019] (1) Under solvent and protective atmosphere, monomer B' and monomer A' are first mixed to obtain mixture I;

[0020] (2) In the presence of a surfactant and an initiator, monomers C' and D' are polymerized with the mixture I to obtain the plugging polymer;

[0021] 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);

[0022] 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 1:0.5-2:0.1-1:0.05-0.5;

[0023] 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).

[0024]

[0025]

[0026] The definitions of R1, R2, R3, R4, R5, R6, R7, R8, R9, M, and X are the same as those described in the first aspect.

[0027] The third aspect of the present invention provides a gel polymer prepared by the method described in the second aspect.

[0028] A fourth aspect of the present invention provides the application of the gel polymers described in the first and third aspects as plugging agents in drilling fluids.

[0029] The fifth aspect of the present invention provides a water-based drilling fluid containing an effective amount of the gel polymer described in the first and third aspects for plugging leaks.

[0030] The gel polymer provided by this invention can achieve temperature-responsive expansion, exhibiting a small volume at low temperatures, but its volume increases significantly when the temperature rises to a certain temperature, i.e., the temperature response threshold.

[0031] In particular, the gel polymer provided by this invention can achieve slow expansion within 24 hours; the expansion effect is maintained within 2.5 times below 150°C, the expansion effect reaches more than 19 times at 150°C, and the expansion effect reaches at least 25 times at 200°C; it can expand responsively with changes in formation temperature, and can still achieve effective expansion in extreme operating environments (200°C) to form a solid sealing layer, effectively reducing leakage, greatly improving the success rate of plugging, and also enabling precise operation in specific downhole environments, reducing the difficulty of plugging caused by complex fractures and other leakage channels.

[0032] The gel polymer provided by this invention, when applied to drilling fluids, can effectively improve the sealing effect and aging performance of drilling fluids with large pores; it can effectively improve the sealing ability and compatibility of drilling fluids, and can effectively seal large-sized fractures of 2-4 mm; at the same time, it has the function of maintaining the rheological properties of the drilling fluid system. Furthermore, the gel polymer provided by this invention is simple, safe, and low-cost to use, and is expected to be widely adopted. Attached Figure Description

[0033] Figure 1 These are product morphology diagrams of gel polymer S1 before drying (A) and after drying (B) obtained in Example 1 of the present invention;

[0034] Figure 2 This is a graph showing the relationship between time and expansion factor of the gel polymer obtained in Example 1 of the present invention under different temperature conditions;

[0035] Figure 3 This is a graph showing the relationship between temperature and expansion ratio of the gel polymer obtained in Example 1 of the present invention at different times. Detailed Implementation

[0036] 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.

[0037] 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.

[0038] "Halogen elements" refers to fluorine, chlorine, bromine, and iodine.

[0039] “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.

[0040] “C 0-6 "Alkylene" refers to a straight-chain or branched alkyl group with a total number of carbon atoms of 0, 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-C(CH3)2-, etc., where the total number of carbon atoms is 0, that is, "C0 alkylene" indicates that it does not exist, and the groups at both ends of this group are directly connected; "C 1-6 "alkylene" has a similar definition.

[0041] As previously described, a first aspect of the present invention provides a gel 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 1:0.5-2:0.1-1:0.05-0.5.

[0042] 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).

[0043]

[0044] In equation (1), R 1 Selected from C 1-6 alkylene, -R 10 -O-;R 10 Selected from C 0-6 Alkylene; each R 2 Each is independently selected from H and C. 1-6 Alkyl group; X is a halogen element;

[0045] In equation (2), each R 3 Each is independently selected from H and C 1-6 Alkyl group; M is selected from H or an alkali metal element;

[0046] In equation (3), each R 4 Each is independently selected from H and C.1-6 Alkyl group; R 5 Selected from C 0-6 alkylene; R 6 Selected from H, C 1-6 Alkyl groups;

[0047] In equation (4), each R 7 Each was independently selected from C 0-6 Alkylene; each R 8 Each is independently selected from H and C. 1-6 Alkyl groups; each R 9 Each is independently selected from H, amino, or C. 1-6 Alkyl groups.

[0048] Preferably, in equation (1), R 1 Selected from -CH2-, -R 10 -O-;R 10 Selected from -CH2-, -CH2-CH2-, -CH2-CH2-CH2-; each R 2 Each is independently selected from H, -CH3, -CH2CH3, -CH2CH2CH3; X is selected from Cl, Br, I, F;

[0049] In equation (2), each R 3 Each is independently selected from H, -CH3, -CH2CH3, -CH2CH2CH3; M is selected from H, K, and Na;

[0050] In equation (3), each R 4 Each is independently selected from H, -CH2CH3, and -CH2CH2CH3; R 5 Selected from C0 alkylene groups, -CH2-, -CH2-CH2-; R 6 Selected from H, -CH3;

[0051] In equation (4), each R 7 Each is independently selected from C0 alkylene groups, -CH2-, -CH2-CH2-, -CH2-CH2-CH2-; each R 8 Each is independently selected from H, -CH3, -CH2CH3, -CH2CH2CH3, and each R. 9 Each is independently selected from H, -NH2, -CH3, and -CH2CH3.

[0052] More preferably, the structural unit A is selected from at least one of the structural units shown in formula (1-1), formula (1-2), formula (1-3), formula (1-4), formula (1-5), formula (1-6), formula (1-7), formula (1-8), formula (1-9), formula (1-10), formula (1-11), formula (1-12), formula (1-13), formula (1-14), formula (1-15), formula (1-16), formula (1-17), and formula (18).

[0053] The structural unit B is selected from at least one of the structural units shown in Equation (2-1), Equation (2-2), Equation (2-3), Equation (2-4), Equation (2-5), Equation (2-6), Equation (2-7), Equation (2-8), Equation (2-9), Equation (2-10), Equation (2-11), and Equation (2-12).

[0054] The structural unit C is selected from at least one of the structural units shown in Equation (3-1), Equation (3-2), Equation (3-3), Equation (3-4), Equation (3-5), Equation (3-6), Equation (3-7), Equation (3-8), Equation (3-9), Equation (3-10), Equation (3-11), and Equation (3-12).

[0055] The structural unit D is selected from at least one of the structural units shown in Equation (4-1), Equation (4-2), Equation (4-3), Equation (4-4), Equation (4-5), Equation (4-6), Equation (4-7), Equation (4-8), Equation (4-9), Equation (4-10), Equation (4-11), Equation (4-12), Equation (4-13), Equation (4-14), Equation (4-15), and Equation (4-16).

[0056] Equation (1-1): R 1 For -CH2-, R 2 Both are H, and X is Cl;

[0057] Equation (1-2): R 1 For -CH2-, R 2 Both are H, and X is Br;

[0058] Equation (1-3): R 1 For -CH2-, R 2 Both are H, and X is I;

[0059] Equation (1-4): R 1 For -CH2-, R 2 Both are H, and X is F;

[0060] Equation (1-5): R 1 For -CH2-, R 2 All are -CH3, X is Cl;

[0061] Equation (1-5): R 1 For -CH2-, R 2 All are -CH3, X is Br;

[0062] Equation (1-7): R 1 For -CH2-, R 2 All are -CH3, and X is I;

[0063] Equation (1-8): R 1 For -CH2-, R 2 All are -CH3, X is F;

[0064] Equation (1-9): R 1 For -CH2-, R 2 All are -CH2CH3, and X is Cl;

[0065] Equation (1-10): R 1 For -CH2-, R 2 All are -CH2CH3, and X is Br;

[0066] Equation (1-11): R 1 For -CH2-, R 2 All are -CH2CH3, X is I;

[0067] Equation (1-12): R 1 For -CH2-, R 2 All are -CH2CH3, and X is F;

[0068] Equation (1-13): R 1 For -CH2-, R 2 All are -CH2CH2CH3, and X is Cl;

[0069] Equation (1-14): R 1 For -CH2-, R 2 Both are -CH2CH2CH3, X is Br; Equation (1-15): R 1 For -CH2-, R 2Both are -CH2CH2CH3, X is I; Equation (1-16): R 1 For -CH2-, R 2 All are -CH2CH2CH3, X is F; Equation (1-17): Equation (1-18): Equation (2-1): R 3 Both are H; M is H;

[0070] Equation (2-2): R 3 Both are H; M is K;

[0071] Equation (2-3): R 3 Both are H; M is Na;

[0072] Equation (2-4): R 3 All are -CH3; M is H;

[0073] Equation (2-5): R 3 All are -CH3; M is K;

[0074] Equation (2-6): R 3 Both are -CH3; M is Na;

[0075] Equation (2-7): R 3 Both are -CH2CH3; M is H;

[0076] Equation (2-8): R 3 All are -CH2CH3; M is K;

[0077] Equation (2-9): R 3 Both are -CH2CH3; M is Na;

[0078] Equation (2-10): R 3 Both are -CH2CH2CH3; M is H;

[0079] Equation (2-11): R 3 All are -CH2CH2CH3; M is K;

[0080] Equation (2-12): R 3 Both are -CH2CH2CH3; M is Na;

[0081] Equation (3-1): R 4 Both are H, R 5 It is a C0 alkylene group, R 6 For H;

[0082] Equation (3-2): R 4 Both are H, R 5 For -CH2-, R 6 For H;

[0083] Equation (3-3): R 4 Both are H, R 5 For -CH2-CH2-, R 6 For H;

[0084] Equation (3-4): R 4 Both are H, R 5 It is a C0 alkylene group, R 6 -CH3; Equation (3-5): R 4 Both are H, R 5 For -CH2-, R 6 -CH3;

[0085] Equation (3-6): R 4 Both are H, R 5 For -CH2-CH2-, R 6 -CH3;

[0086] Equation (3-7): R 4 Both are -CH2CH3, R 5 It is a C0 alkylene group, R 6 For H;

[0087] Equation (3-8): R 4 Both are -CH2CH3, R 5 For -CH2-, R 6 For H;

[0088] Equation (3-9): R 4 Both are -CH2CH3, R 5 For -CH2-CH2-, R 6 For H;

[0089] Equation (3-10): R 4 Both are -CH2CH2CH3, R 5 It is a C0 alkylene group, R 6 For H;

[0090] Equation (3-11): R 4 Both are -CH2CH2CH3, R 5 For -CH2-, R 6 For H;

[0091] Equation (3-12): R 4 Both are -CH2CH2CH3, R 5 For -CH2-CH2-, R 6 For H;

[0092] Equation (4-1): R 7 Both are C0 alkylene groups, R8 Both are H, R 9 All are H;

[0093] Equation (4-2): R 7 Both are -CH2-, R 8 Both are H, R 9 All are H;

[0094] Equation (4-3): R 7 Both are -CH2-CH2-, R 8 Both are H, R 9 All are H;

[0095] Equation (4-4): R 7 All are -CH2-CH2-CH2-, R 8 Both are H, R 9 All are H;

[0096] Equation (4-5): R 7 Both are C0 alkylene groups, R 8 Both are -CH3, R 9 All are H;

[0097] Equation (4-6): R 7 Both are -CH2-, R 8 Both are -CH3, R 9 All are H;

[0098] Equation (4-7): R 7 Both are -CH2-CH2-, R 8 Both are -CH3, R 9 All are H;

[0099] Equation (4-8): R 7 All are -CH2-CH2-CH2-, R 8 Both are -CH3, R 9 All are H;

[0100] Equation (4-9): R 7 Both are C0 alkylene groups, R 8 Both are -CH2CH3, R 9 All are H;

[0101] Equation (4-10): R 7 Both are -CH2-, R 8 Both are -CH2CH3, R 9 All are H;

[0102] Equation (4-11): R 7 Both are -CH2-CH2-, R 8 Both are -CH2CH3, R 9All are H;

[0103] Equation (4-12): R 7 All are -CH2-CH2-CH2-, R 8 Both are -CH2CH3, R 9 All are H;

[0104] Equation (4-13): R 7 Both are C0 alkylene groups, R 8 Both are -CH2CH2CH3, R 9 All are H;

[0105] Equation (4-14): R 7 Both are -CH2-, R 8 Both are -CH2CH2CH3, R 9 All are H;

[0106] Equation (4-15): R 7 Both are -CH2-CH2-, R 8 Both are -CH2CH2CH3, R 9 All are H;

[0107] Equation (4-16): R 7 All are -CH2-CH2-CH2-, R 8 Both are -CH2CH2CH3, R 9 All are H.

[0108] In a preferred embodiment, the molar ratio of structural unit A, structural unit B, structural unit C, and structural unit D is 1:0.5-1:0.5-1:0.05-0.1. The inventors have found that, under this preferred embodiment, the gel polymer obtained by this invention exhibits enhanced toughness and thermal stability, enabling it to adapt to higher temperature environments; it achieves more precise water absorption and swelling effects, adapting to the field requirements of different oilfield operations; it improves production efficiency, reduces raw material consumption, and achieves better cost control. When applied to drilling fluids, it exhibits better sealing performance and aging resistance.

[0109] Preferably, the number-average molecular weight of the gel polymer is 0.5 million to 500,000.

[0110] As previously described, a second aspect of the present invention provides a method for preparing a gel polymer, the method comprising:

[0111] (1) Under solvent and protective atmosphere, monomer B' and monomer A' are first mixed to obtain mixture I;

[0112] (2) In the presence of a surfactant and an initiator, monomers C' and D' are polymerized with the mixture I to obtain the gel polymer;

[0113] 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);

[0114] 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 1:0.5-2:0.1-1:0.05-0.5;

[0115] 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).

[0116]

[0117]

[0118] The definitions of R1, R2, R3, R4, R5, R6, R7, R8, R9, M, and X are the same as those described in the first aspect.

[0119] Preferably, the protective atmosphere is selected from at least one of nitrogen and argon.

[0120] In a preferred embodiment, in step (1), the conditions for the first mixing include: a temperature of 25°C-45°C, a time of 0.5-2 hours, and a stirring speed of 300-500 rpm.

[0121] Preferably, the polymerization reaction is carried out under stirring conditions, which include: stirring speed of 400-7000 rpm, temperature of 60-100℃, pH value of 7-9, and time of 6-24h.

[0122] It should be noted that the pH value of 7-9 refers to the initial system in which the polymerization reaction takes place, and the pH value of the initial system is 7-9. The pH value can be adjusted by conventional acid-base adjustment methods in the art, which will not be elaborated here. Those skilled in the art should not understand this as a limitation of the present invention.

[0123] In a preferred embodiment, all double bonds of the monomer D' participate in the polymerization reaction, which enables the linear molecules to link together to form a cross-linked network structure during the polymerization process, thereby increasing the strength and playing a role in regulating the physical properties and improving the chemical stability of the gel polymer.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] Preferably, the initiator is selected from at least one of azo initiators, peroxide initiators, and redox initiators.

[0128] More preferably, the azo initiator is selected from at least one of azobisisobutyramidine hydrochloride, azobisisopropylimidazoline hydrochloride, azobiscyanopentanoic acid, and azobisisopropylimidazoline; the peroxide initiator is selected from at least one of hydrogen peroxide, ammonium persulfate, sodium persulfate, and potassium persulfate; and the redox initiator is selected from at least one of persulfate-sulfite, persulfate-thiourea, and persulfate-organic salt.

[0129] More preferably, the amount of the initiator is 0.02-3 mol% based on the total molar amount of monomers A', B', C', and D'.

[0130] In a preferred embodiment, the solvent is water.

[0131] More preferably, the amount of solvent used is 500-1000 mL, relative to the total molar amount of monomer A', monomer B', monomer C' and monomer D' being 1 mol.

[0132] Preferably, the surfactant is selected from at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and octadecyltrimethylammonium chloride.

[0133] More preferably, the amount of surfactant used is 0.1-1.5% by weight, based on the total weight of monomers A', B', C', and D'.

[0134] 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.

[0135] As previously stated, a third aspect of the present invention provides a gel polymer prepared by the method described in the second aspect.

[0136] As previously stated, the fourth aspect of the present invention provides the application of the gel polymers described in the first and third aspects as plugging agents in drilling fluids.

[0137] As previously described, the fifth aspect of the present invention provides a water-based drilling fluid containing an effective amount of the gel polymer described in the first and third aspects for plugging leaks.

[0138] Preferably, the water-based drilling fluid contains water, gel polymer, organic clay, pH adjuster, viscosity modifier, filtration loss reducer, lubricant, inhibitor, and rigid crosslinking particles;

[0139] In this embodiment, relative to 100 parts by weight of water, the content of the gel polymer is 1-3 parts by weight, the content of the organic soil is 1-6 parts by weight, the content of the pH adjuster is 0.1-1 parts by weight, the content of the thickener is 1-2 parts by weight, the content of the filtration loss reducer is 2-6 parts by weight, the content of the lubricant is 1-3 parts by weight, the content of the inhibitor is 0.5-2 parts by weight, and the content of the rigid crosslinking particles is 1-4 parts by weight; the gel polymer is the gel polymer described in the first aspect and the third aspect.

[0140] More preferably, the organic clay is sodium-based bentonite and / or calcium-based bentonite; the pH adjuster is NaOH; the filtration loss reducer is selected from at least one of carboxymethyl cellulose, potassium humate, sulfonated phenolic resin, and carboxymethyl starch; the lubricant is selected from at least one of polyols and bonded lubricants; the tackifier is selected from at least one of polyanionic cellulose, potassium polyacrylamide, and acrylamide-sodium acrylate copolymer; the inhibitor is selected from at least one of potassium chloride, sodium humate, and inorganic positively charged adhesive; and the rigid crosslinking particles are selected from at least one of fiber, nutshell, mica, or vermiculite.

[0141] 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.

[0142] 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.

[0143] Example 1

[0144] Monomer A': (3-acrylamidopropyl)trimethylammonium chloride, with the structure shown in formula (I), the structural formula is:

[0145] Monomer B': Sodium p-styrene sulfonate, with the structure shown in formula (II), and R 3 Both are H, and M is Na; the structural formula is:

[0146] Monomer C': N-vinylcaprolactam, with the structure shown in formula (III), and R 4 Both are H, R 5 It is a C0 alkylene group, R 6 For H; the structural formula is:

[0147] Monomer D': divinylbenzene, with the structure shown in formula (IV), and R 7 Both are C0 alkylene groups, R 8 Both are H, R 9 All are H; the structural formula is:

[0148] (1) In the presence of nitrogen, monomer B' and 0.5 mol of monomer A' were dissolved in water and mixed for the first time to obtain mixture I; the conditions for the first mixing were: temperature 25℃, time 1h, and stirring speed 500rpm.

[0149] (2) The monomers C', D', initiator (potassium persulfate), surfactant (sodium dodecylbenzenesulfonate) and the mixture I were subjected to a polymerization reaction, and the resulting product was dried to obtain gel polymer S1; the conditions for the polymerization reaction were: stirring speed of 500 rpm, temperature of 70°C, pH value of 7, and time of 12 h.

[0150] Based on the total molar amount of monomer A', monomer B', monomer C' and monomer D', the amount of the initiator is 1 mol%; based on the total weight of monomer A', monomer B', monomer C' and monomer D', the amount of the surfactant is 1 wt%.

[0151] Based on a total molar amount of 1 mol for monomers A', B', C', and D', the amount of solvent used is 500 mL.

[0152] The molar ratio of monomer A', monomer B', monomer C', and monomer D' is 1:0.5:0.5:0.05;

[0153] The number-average molecular weight of gel polymer S1 is 140,000;

[0154] See the product properties of gel polymer S1 before and after drying. Figure 1 (A is before drying, B is after drying).

[0155] Example 2

[0156] Monomer A': Acryloyloxyethyltrimethylammonium bromide; with the structure shown in formula (I), the structural formula is:

[0157] Monomer B': Potassium p-styrenesulfonate; having the structure shown in formula (II), and R 3 Both are H, and M is K; the structural formula is:

[0158] Monomer C': N-vinylcaprolactam; has the structure shown in formula (III), and R 4 Both are H, R 5 It is a C0 alkylene group, R 6 For H; the structural formula is:

[0159] Monomer D': divinylbenzene; having the structure shown in formula (IV), and R 7 Both are C0 alkylene groups, R 8 Both are H, R 9 All are H; the structural formula is:

[0160] (1) In the presence of nitrogen, monomer B' and 1 mol of monomer A' were dissolved in water and mixed for the first time to obtain mixture I; the conditions for the first mixing were: temperature 25℃, time 1h, and stirring speed 500rpm.

[0161] (2) The monomers C', D', initiator (potassium persulfate), surfactant (sodium dodecylbenzenesulfonate) and the mixture I were subjected to a polymerization reaction, and the resulting product was dried to obtain gel polymer S2; the conditions for the polymerization reaction were: stirring speed of 500 rpm, temperature of 70°C, pH value of 7, and time of 12 h.

[0162] Based on the total molar amount of monomer A', monomer B', monomer C' and monomer D', the amount of the initiator is 0.5 mol%; based on the total weight amount of monomer A', monomer B', monomer C' and monomer D', the amount of the surfactant is 0.5 wt%.

[0163] Based on a total molar amount of 1 mol for monomers A', B', C', and D', the amount of solvent used is 500 mL.

[0164] The molar ratio of monomer A', monomer B', monomer C', and monomer D' is 1:1:1:0.1;

[0165] The number-average molecular weight of gel polymer S2 is 350,000.

[0166] Example 3

[0167] This embodiment follows a similar process to Embodiment 1, except that the molar ratio of monomer A', monomer B', monomer C', and monomer D' is 1:2:0.5:0.05.

[0168] Everything else is the same as in Example 1.

[0169] Gel polymer S3 was prepared with a number-average molecular weight of 220,000.

[0170] Example 4

[0171] This embodiment follows a similar process to Embodiment 1, except that the molar ratio of monomer A', monomer B', monomer C', and monomer D' is 1:0.5:0.5:0.5.

[0172] Everything else is the same as in Example 1.

[0173] Gel polymer S4 was prepared with a number-average molecular weight of 170,000.

[0174] Example 5

[0175] This embodiment follows a similar process to Embodiment 1, except that the types of monomers used are different. Specifically:

[0176] Monomer A': Methacryloxyethyltrimethylammonium chloride; with the structure shown in formula (I), the structural formula is:

[0177] Monomer B': Potassium p-styrenesulfonate; having the structure shown in formula (II), and R 3 Both are H, and M is K; the structural formula is:

[0178] Monomer C': N-vinylcaprolactam; has the structure shown in formula (III), and R 4 Both are H, R 5 It is a C0 alkylene group, R 6 For H; the structural formula is:

[0179] Monomer D': 1,4-diamino-2,5-divinylbenzene; having the structure shown in formula (IV), and R 7 Both are C0 alkylene groups, R 8 Both are H, R 9 All are -NH2; the structural formula is:

[0180] Everything else is the same as in Example 1.

[0181] Gel polymer S5 was prepared with a number-average molecular weight of 200,000.

[0182] Comparative Example 1

[0183] This comparative example follows a similar process to Example 1, except that monomer A' is not added in this comparative example.

[0184] Everything else is the same as in Example 1.

[0185] Gel polymer DS1 was prepared.

[0186] Comparative Example 2

[0187] This comparative example follows a similar process to Example 1, except that monomer B' is not added in this comparative example.

[0188] Everything else is the same as in Example 1.

[0189] The gel polymer DS2 was prepared.

[0190] Comparative Example 3

[0191] This comparative example follows a similar process to Example 1, except that monomer C' is not added in this comparative example.

[0192] Everything else is the same as in Example 1.

[0193] The gel polymer DS3 was prepared.

[0194] Comparative Example 4

[0195] This comparative example follows a similar process to Example 1, except that monomer D' is not added in this comparative example.

[0196] Everything else is the same as in Example 1.

[0197] The gel polymer DS4 was prepared.

[0198] Comparative Example 5

[0199] This comparative example follows a similar process to Example 1, except that in this example, the molar ratio of monomer A', monomer B', monomer C', and monomer D' is 1:3:2:0.5.

[0200] Everything else is the same as in Example 1.

[0201] The gel polymer DS5 was prepared.

[0202] Test Example 1

[0203] This test example illustrates the leak-stopping performance of the gel polymer prepared in the above examples.

[0204] The testing method is as follows:

[0205] The above-mentioned gel polymer and corresponding laboratory materials were used to prepare a water-based drilling fluid plugging slurry. After hot rolling at 150℃ and 180℃ for 16 hours, plugging experiments were conducted at instrument temperatures of 150℃ and 180℃. The specific operating steps are as follows:

[0206] Add the plugging slurry to the mud cup, raise the temperature to the set temperature, and then open the upper and lower valves sequentially. Adjust the pressure by controlling the opening and closing of the upper valve. After the lower valve is opened, measure the instantaneous leakage volume V0, and then start timing. Gradually increase the pressure difference between the upper and lower valves to 6 MPa at a rate of 2 min / MPa, and measure the initial cumulative leakage volume V1 during the first pressurization process to complete the routine permeability leakage assessment. Then close the upper and lower valves and reduce the pressure in the mud cup to 1 MPa.

[0207] Under high temperature conditions of 150℃ and 180℃, the gel polymer provided in the above example was added to water-based drilling fluid (blank group), and the plugging effect of the gel polymer was tested by 2-4mm crack plate test.

[0208] The blank group consisted of: water + organic soil + pH adjuster (NaOH) + lubricant (polyethylene glycol) + thickener (potassium polyacrylamide) + filtration loss reducer (carboxymethyl cellulose) + inhibitor (potassium chloride) + rigid crosslinking particles (mica).

[0209] Of which, relative to 100 parts by weight of water, the content of the organic soil is 4 parts by weight, the content of the pH adjuster is 0.5 parts by weight, the content of the thickener is 1.5 parts by weight, the content of the filtration loss reducer is 4 parts by weight, the content of the lubricant is 2 parts by weight, the content of the inhibitor is 1 part by weight, and the content of the rigid cross-linking particles is 2 parts by weight.

[0210] The test results are shown in Table 1.

[0211] Table 1

[0212]

[0213]

[0214]

[0215] As can be seen from the results in Table 1, the gel polymer provided by this invention, when applied to water-based drilling fluid, can achieve a better sealing effect for large-size seam plates.

[0216] Test Example 2

[0217] This test example is used to test the swelling properties of gel polymers under different temperature aging conditions. The test method is as follows:

[0218] Weigh 5g of gel polymer and 200mL of deionized water into a beaker, let stand at room temperature (25℃) for 24h, and record the change in mass of gel polymer before and after.

[0219] Weigh 5g of gel polymer and 200mL of deionized water and place them in a high-temperature reactor. Heat the reactor under high temperature for 24h and record the mass change of the gel polymer before and after.

[0220] The results are shown in Table 2.

[0221] Table 2

[0222]

[0223] As can be seen from the results in Table 2, the gel polymer provided by the present invention can achieve good expansion performance under different temperature conditions.

[0224] The present invention also provides, by way of example, the relationship between time and expansion factor of the gel polymer prepared in Example 1 under different temperature conditions, such as... Figure 2As shown, the gel is suitable for temperatures ranging from 150 to 200℃. Below 150℃, the expansion ratio is small, less than 2.5 times after 24 hours. The expansion effect is not obvious within 4 hours, and the expansion ratio increases slowly afterward, indicating that the particles have good delayed water absorption and expansion properties and a slow expansion effect.

[0225] Furthermore, the present invention also provides, by way of example, the relationship between temperature and expansion ratio of the gel polymer prepared in Example 1 at different times, such as... Figure 3 As shown, the gel is suitable for temperatures ranging from 150 to 200℃. Below 150℃, the expansion ratio is small; between 150℃ and 200℃, the polymer gel exhibits temperature-responsive expansion. After 24 hours of hot rolling, the expansion ratio reaches 19 times at 150℃ and 25 times at 200℃. This meets practical application requirements, providing sufficient time for material addition on-site to achieve the desired penetration into the perforated layer.

[0226] 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. The application of a gel polymer as a plugging agent in drilling fluid, characterized in that, The polymer contains structural unit A, structural unit B, structural unit C, and structural unit D; the molar ratio of structural unit A, structural unit B, structural unit C, and structural unit D is 1:0.5-1:0.5-1:0.05-0.

1. 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). Equation (1), Equation (2), Equation (3), Equation (4); in, In equation (1), R 1 Selected from C 1-6 alkylene, -R 10 -O-;R 10 Selected from C 0-6 Alkylene; each R 2 Each is independently selected from H and C. 1-6 Alkyl group; X is a halogen element; In equation (2), each R 3 Each is independently selected from H and C 1-6 Alkyl group; M is selected from H or an alkali metal element; In equation (3), each R 4 Each is independently selected from H and C. 1-6 Alkyl group; R 5 Selected from C 0-6 alkylene; R 6 Selected from H, C 1-6 Alkyl groups; In equation (4), each R 7 Each was independently selected from C 0-6 Alkylene; each R 8 Each is independently selected from H and C. 1-6 Alkyl groups; each R 9 Each is independently selected from H, amino, or C. 1-6 Alkyl groups.

2. The application according to claim 1, characterized in that, In equation (1), R 1 Selected from -CH2-, -R 10 -O-;R 10 Selected from -CH2-, -CH2-CH2-, -CH2-CH2-CH2-; each R 2 Each is independently selected from H, -CH3, -CH2CH3, -CH2CH2CH3; X is selected from Cl, Br, I, F; In equation (2), each R 3 Each is independently selected from H, -CH3, -CH2CH3, -CH2CH2CH3; M is selected from H, K, and Na; In equation (3), each R 4 Each is independently selected from H, -CH2CH3, and -CH2CH2CH3; R 5 Selected from C0 alkylene groups, -CH2-, -CH2-CH2-; R 6 Selected from H, -CH3; In equation (4), each R 7 Each is independently selected from C0 alkylene groups, -CH2-, -CH2-CH2-, -CH2-CH2-CH2-; each R 8 Each is independently selected from H, -CH3, -CH2CH3, -CH2CH2CH3, and each R. 9 Each is independently selected from H, -NH2, -CH3, and -CH2CH3.

3. The application according to claim 1 or 2, characterized in that, The structural unit A is selected from at least one of the structural units shown in Equation (1-1), Equation (1-2), Equation (1-3), Equation (1-4), Equation (1-5), Equation (1-6), Equation (1-7), Equation (1-8), Equation (1-9), Equation (1-10), Equation (1-11), Equation (1-12), Equation (1-13), Equation (1-14), Equation (1-15), Equation (1-16), Equation (1-17), and Equation (18). The structural unit B is selected from at least one of the structural units shown in Equation (2-1), Equation (2-2), Equation (2-3), Equation (2-4), Equation (2-5), Equation (2-6), Equation (2-7), Equation (2-8), Equation (2-9), Equation (2-10), Equation (2-11), and Equation (2-12). The structural unit C is selected from at least one of the structural units shown in Equation (3-1), Equation (3-2), Equation (3-3), Equation (3-4), Equation (3-5), Equation (3-6), Equation (3-7), Equation (3-8), Equation (3-9), Equation (3-10), Equation (3-11), and Equation (3-12). The structural unit D is selected from at least one of the structural units shown in Equation (4-1), Equation (4-2), Equation (4-3), Equation (4-4), Equation (4-5), Equation (4-6), Equation (4-7), Equation (4-8), Equation (4-9), Equation (4-10), Equation (4-11), Equation (4-12), Equation (4-13), Equation (4-14), Equation (4-15), and Equation (4-16). Equation (1-1): R 1 For -CH2-, R 2 Both are H, and X is Cl; Equation (1-2): R 1 For -CH2-, R 2 Both are H, and X is Br; Equation (1-3): R 1 For -CH2-, R 2 Both are H, and X is I; Equation (1-4): R 1 For -CH2-, R 2 Both are H, and X is F; Equation (1-5): R 1 For -CH2-, R 2 All are -CH3, X is Cl; Equation (1-5): R 1 For -CH2-, R 2 All are -CH3, X is Br; Equation (1-7): R 1 For -CH2-, R 2 All are -CH3, and X is I; Equation (1-8): R 1 For -CH2-, R 2 All are -CH3, X is F; Equation (1-9): R 1 For -CH2-, R 2 All are -CH2CH3, and X is Cl; Equation (1-10): R 1 For -CH2-, R 2 All are -CH2CH3, and X is Br; Equation (1-11): R 1 For -CH2-, R 2 All are -CH2CH3, X is I; Equation (1-12): R 1 For -CH2-, R 2 All are -CH2CH3, and X is F; Equation (1-13): R 1 For -CH2-, R 2 All are -CH2CH2CH3, and X is Cl; Equation (1-14): R 1 For -CH2-, R 2 Both are -CH2CH2CH3, and X is Br; Equation (1-15): R 1 For -CH2-, R 2 All are -CH2CH2CH3, X is I; Equation (1-16): R 1 For -CH2-, R 2 All are -CH2CH2CH3, and X is F; Equation (1-17): ; Equation (1-18): ; Equation (2-1): R 3 Both are H; M is H; Equation (2-2): R 3 Both are H; M is K; Equation (2-3): R 3 Both are H; M is Na; Equation (2-4): R 3 All are -CH3; M is H; Equation (2-5): R 3 All are -CH3; M is K; Equation (2-6): R 3 Both are -CH3; M is Na; Equation (2-7): R 3 Both are -CH2CH3; M is H; Equation (2-8): R 3 All are -CH2CH3; M is K; Equation (2-9): R 3 Both are -CH2CH3; M is Na; Equation (2-10): R 3 Both are -CH2CH2CH3; M is H; Equation (2-11): R 3 All are -CH2CH2CH3; M is K; Equation (2-12): R 3 Both are -CH2CH2CH3; M is Na; Equation (3-1): R 4 Both are H, R 5 It is a C0 alkylene group, R 6 For H; Equation (3-2): R 4 Both are H, R 5 For -CH2-, R 6 For H; Equation (3-3): R 4 Both are H, R 5 For -CH2-CH2-, R 6 For H; Equation (3-4): R 4 Both are H, R 5 It is a C0 alkylene group, R 6 -CH3; Equation (3-5): R 4 Both are H, R 5 For -CH2-, R 6 -CH3; Equation (3-6): R 4 Both are H, R 5 For -CH2-CH2-, R 6 -CH3; Equation (3-7): R 4 Both are -CH2CH3, R 5 It is a C0 alkylene group, R 6 For H; Equation (3-8): R 4 Both are -CH2CH3, R 5 For -CH2-, R 6 For H; Equation (3-9): R 4 Both are -CH2CH3, R 5 For -CH2-CH2-, R 6 For H; Equation (3-10): R 4 Both are -CH2CH2CH3, R 5 It is a C0 alkylene group, R 6 For H; Equation (3-11): R 4 Both are -CH2CH2CH3, R 5 For -CH2-, R 6 For H; Equation (3-12): R 4 Both are -CH2CH2CH3, R 5 For -CH2-CH2-, R 6 For H; Equation (4-1): R 7 Both are C0 alkylene groups, R 8 Both are H, R 9 All are H; Equation (4-2): R 7 Both are -CH2-, R 8 Both are H, R 9 All are H; Equation (4-3): R 7 Both are -CH2-CH2-, R 8 Both are H, R 9 All are H; Equation (4-4): R 7 All are -CH2-CH2-CH2-, R 8 Both are H, R 9 All are H; Equation (4-5): R 7 Both are C0 alkylene groups, R 8 Both are -CH3, R 9 All are H; Equation (4-6): R 7 Both are -CH2-, R 8 Both are -CH3, R 9 All are H; Equation (4-7): R 7 Both are -CH2-CH2-, R 8 Both are -CH3, R 9 All are H; Equation (4-8): R 7 All are -CH2-CH2-CH2-, R 8 Both are -CH3, R 9 All are H; Equation (4-9): R 7 Both are C0 alkylene groups, R 8 Both are -CH2CH3, R 9 All are H; Equation (4-10): R 7 Both are -CH2-, R 8 Both are -CH2CH3, R 9 All are H; Equation (4-11): R 7 Both are -CH2-CH2-, R 8 Both are -CH2CH3, R 9 All are H; Equation (4-12): R 7 All are -CH2-CH2-CH2-, R 8 Both are -CH2CH3, R 9 All are H; Equation (4-13): R 7 Both are C0 alkylene groups, R 8 Both are -CH2CH2CH3, R 9 All are H; Equation (4-14): R 7 Both are -CH2-, R 8 Both are -CH2CH2CH3, R 9 All are H; Equation (4-15): R 7 Both are -CH2-CH2-, R 8 Both are -CH2CH2CH3, R 9 All are H; Equation (4-16): R 7 All are -CH2-CH2-CH2-, R 8 Both are -CH2CH2CH3, R 9 All are H.

4. The application according to claim 1 or 2, characterized in that, The gel polymer is prepared by a method comprising the following steps: (1) Under solvent and protective atmosphere, monomer B' and monomer A' are first mixed to obtain mixture I; (2) In the presence of a surfactant and an initiator, monomers C' and D' are polymerized with the mixture I to obtain the gel polymer; 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). 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 1:0.5-1:0.5-1:0.05-0.1; 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). Formula (I), Equation (II), Formula (III) Formula (IV), Equation (1), Equation (2), Equation (3), Equation (4); The definitions of R1, R2, R3, R4, R5, R6, R7, R8, R9, M, and X are the same as those in any one of claims 1-3.

5. The application according to claim 4, characterized in that, The polymerization reaction is carried out under stirring conditions, which include: stirring speed of 400-7000 rpm, temperature of 60-100℃, pH value of 7-9, and time of 6-24h. And / or, the initiator is selected from at least one of azo initiators, peroxide initiators, and redox initiators.

6. The application according to claim 5, characterized in that, The azo initiator is selected from at least one of azobisisobutyramidine hydrochloride, azobisisopropylimidazoline hydrochloride, azobisisovalerate, and azobisisopropylimidazoline. The peroxide initiator is selected from at least one of hydrogen peroxide, ammonium persulfate, sodium persulfate, and potassium persulfate; The redox initiator is selected from at least one of persulfate-sulfite, persulfate-thiourea, and persulfate-organic salt; And / or, the solvent is water.

7. The application according to claim 6, characterized in that, Based on the total molar amount of monomer A', monomer B', monomer C' and monomer D', the amount of initiator is 0.02-3 moles.

8. The application according to claim 4, characterized in that, The surfactant is selected from at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and octadecyltrimethylammonium chloride.

9. The application according to claim 8, characterized in that, Based on the total weight of monomers A', B', C' and D', the amount of surfactant used is 0.1-1.5 by weight.

10. A water-based drilling fluid, characterized in that, The water-based drilling fluid contains an effective amount of the gel polymer described in any one of claims 1-3 for plugging purposes.

11. The water-based drilling fluid according to claim 10, characterized in that, This water-based drilling fluid contains water, gel polymer, organic clay, pH adjuster, viscosity modifier, filtration loss reducer, lubricant, inhibitor, and rigid crosslinking particles; The gel polymer comprises, relative to 100 parts by weight of water, 1-3 parts by weight of the organic soil, 1-6 parts by weight of the pH adjuster, 0.1-1 parts by weight of the thickener, 1-2 parts by weight of the filtrate reducer, 2-6 parts by weight of the lubricant, 0.5-2 parts by weight of the inhibitor, and 1-4 parts by weight of the rigid crosslinking particles; the gel polymer is the gel polymer described in any one of claims 1-3.

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