Plugging agent as well as preparation method and application thereof

Abstract

The invention relates to a plugging agent as well as a preparation method and application thereof, and belongs to the technical field of oil field chemicals. The preparation method of the plugging agent comprises the following steps: firstly, compounding flaky carbon nitride and molybdenum disulfide to obtain a carbon nitride-molybdenum disulfide compound; then the carbon nitride-molybdenum disulfide compound is subjected to active group modification, and finally phenolic resin is filled between sheet layers of the active group modified composite material. The plugging agent prepared by the preparation method of the plugging agent has good plugging performance, heat resistance, lubricating performance and loading capacity.

Description

Technical Field

[0001] The present invention relates to a plugging agent and its preparation method and application, belonging to the technical field of oilfield chemicals. Background Art

[0002] With the continuous increase in global oil demand, oil drilling has gradually shifted from shallow to deep layers. Since the difficulty of oil extraction in deep wells or ultra-deep wells has gradually increased, the requirements for drilling technology have become more stringent. As one of the core technologies, the plugging technology has been widely studied in the field of drilling engineering. Drilling workers at home and abroad have developed a series of polymer-based plugging materials and supporting plugging processes from the perspectives of chemistry and materials science. However, for fractured and cavernous losses, the current plugging materials cannot meet the above plugging requirements. In addition, in order to improve the heat resistance, a large amount of plugging materials need to be used. After adding a large amount of plugging materials to the plugging slurry, the solid content of the plugging slurry will be very high, often resulting in difficult pumping, or difficult lifting of the drill string after the plugging slurry reaches the well. This requires the plugging materials to have good heat resistance, rheology, and lubricity.

[0003] Therefore, there is an urgent need to develop a plugging agent with good heat resistance, rheology, and lubricity to meet the plugging requirements of unstable and collapsing shale formations. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of a plugging agent, which can solve the problem that the currently prepared plugging agent has poor heat resistance, rheology, and lubricity and cannot meet the plugging requirements of unstable and collapsing shale formations.

[0005] The second purpose of the present invention is to provide a plugging agent, which can solve the problem that the current plugging agent has poor heat resistance, rheology, and lubricity.

[0006] The third purpose of the present invention is to provide an application of a plugging agent in drilling fluid, which can solve the problem that the current plugging agent has poor heat resistance, rheology, and lubricity when used in drilling fluid.

[0007] In order to achieve the above purposes, the technical solution adopted by the preparation method of the plugging agent of the present invention is as follows:

[0008] A preparation method of a plugging agent, comprising the following steps:

[0009] (1) Mix flaky carbon nitride and molybdenum disulfide precursor in an organic solvent, and then carry out a solvothermal reaction to obtain a carbon nitride-molybdenum disulfide composite;

[0010] (2) The obtained carbon nitride-molybdenum disulfide composite is modified with active groups by using a modifying substance to obtain an active-group-modified carbon nitride-molybdenum disulfide composite, and the active groups are selected from one or any combination of hydroxyl groups, carboxyl groups, and amino groups;

[0011] (3) The active-group-modified carbon nitride-molybdenum disulfide composite, a phenolic compound, an aldehyde compound, and a catalyst are mixed and reacted in a solvent to in-situ synthesize a phenolic resin on the active-group-modified carbon nitride-molybdenum disulfide composite to obtain a phenolic-resin-modified composite material;

[0012] (4) The phenolic-resin-modified composite material and m-alkynylphenyl diazonium salt are subjected to a coupling reaction in an alkaline liquid phase environment below 0 °C to obtain a plugging agent.

[0013] In the preparation method of the plugging agent of the present invention, first, sheet-like carbon nitride and molybdenum disulfide are compounded to obtain a carbon nitride-molybdenum disulfide composite; then, the carbon nitride-molybdenum disulfide composite is modified with active groups, and finally, a phenolic resin is filled between the layers of the active-group-modified composite material. The plugging agent prepared by the preparation method of the plugging agent of the present invention has good plugging performance, heat resistance, lubricating performance, and pressure-bearing capacity, and has a wide size distribution range and controllable morphology, which is beneficial to adapting to plugging of cracks with different widths, and has good biodegradability, has no impact on the environment, and is non-toxic and pollution-free. Among them, carbon nitride has good heat resistance, a low friction coefficient, and excellent lubricating performance; molybdenum disulfide has the characteristics of high strength and easy shear, and has an extremely low friction coefficient and excellent lubricating performance, which can improve the self-lubricity of the plugging agent; using carbon nitride and molybdenum disulfide as the matrix of the plugging agent can endow the plugging agent with good heat resistance, lubricating performance, and pressure-bearing capacity. In the preparation method of the plugging agent of the present invention, the purpose of modifying the carbon nitride-molybdenum disulfide composite with active groups is to improve the in-situ growth ability of the heteroaromatic resin between the layers of the active-group-modified carbon nitride-molybdenum disulfide composite. The phenolic resin can improve the toughness, pressure-bearing capacity, and compatibility performance with the drilling fluid of the plugging agent, and can endow the drilling fluid with good rheological properties.

[0014] Preferably, the molybdenum disulfide precursor is ammonium thiomolybdate.

[0015] Preferably, in step (1), the organic solvent is selected from one or any combination of N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, and N,N-diethylacetamide.

[0016] Preferably, in step (1), the mass ratio of the sheet-like carbon nitride, the molybdenum disulfide precursor, and the organic solvent is 200:(10-20):100.

[0017] Preferably, in step (1), the temperature of the solvothermal reaction is 160 - 200 °C, and the time of the solvothermal reaction is 8 - 10 h.

[0018] Preferably, in step (2), the modifying substance includes an active substance and a water-soluble sulfate; the active substance is an alkaline compound, an acidic compound, urea or a water-soluble cyanide salt. Modifying the carbon nitride-molybdenum disulfide composite with the modifying substance to introduce active groups such as hydroxyl, carboxyl, amino, etc. on the carbon nitride-molybdenum disulfide composite can improve the binding ability between the carbon nitride-molybdenum disulfide composite and the resin. In the present invention, when an alkaline compound or a water-soluble cyanide salt is used for modification, a carbon nitride-molybdenum disulfide composite modified with active groups can be obtained; when an acidic compound is used for modification, a carbon nitride-molybdenum disulfide composite modified with carboxyl groups can be obtained; when urea is used for modification, a carbon nitride-molybdenum disulfide composite modified with amino groups can be obtained.

[0019] Preferably, the alkaline compound is an alkali metal hydroxide; the acidic compound is a carboxylic acid compound; the water-soluble cyanide salt is sodium cyanide or potassium cyanide; the water-soluble sulfate is sodium sulfate or potassium sulfate. Preferably, the carboxylic acid compound is a water-soluble carboxylic acid compound. Preferably, the carboxylic acid compound is formic acid, acetic acid or propionic acid.

[0020] Preferably, in step (2), the method for modifying the active groups includes the following steps: allowing the carbon nitride-molybdenum disulfide composite and the modifying substance to undergo a static reaction in water under sealed conditions.

[0021] Preferably, in step (2), the mass ratio of the carbon nitride-molybdenum disulfide composite, the active substance, the water-soluble sulfate and water is 100:(10 - 16):(15 - 20):100. If the amounts of the active substance and the water-soluble sulfate are too small, the modification effect will be poor and the binding ability between the carbon nitride-molybdenum disulfide composite and the resin cannot be effectively improved; if the amounts of the active substance and the water-soluble sulfate are too large, the reaction is more likely to produce gel, resulting in poor stability of the product.

[0022] Preferably, in step (2), the temperature of the static reaction for active group modification is 100 - 120 °C, and the time is 8 - 10 h.

[0023] Preferably, in step (3), the phenolic compound is selected from one or any combination of cardanol, bisphenol A, resorcinol, hydroquinone; the aldehyde compound is paraformaldehyde and / or formaldehyde; the catalyst is an acidic catalyst; the solvent includes an alcohol solvent and water.

[0024] Preferably, in step (3), the mass ratio of the alcohol solvent and water is 100:(1 - 5).

[0025] It is understandable that the acidic catalysts used in the preparation of phenolic resins are all applicable to the present invention. Preferably, the acidic catalyst is p-toluenesulfonic acid. Preferably, in step (3), the alcohol solvent is n-propanol, isopropanol, n-butanol, or isobutanol.

[0026] Preferably, in step (3), the mass ratio of the active group-modified carbon nitride-molybdenum disulfide composite, phenolic compound, and aldehyde compound is 100:20:(10 - 40). Further preferably, in step (3), the mass ratio of the active group-modified carbon nitride-molybdenum disulfide composite, phenolic compound, and aldehyde compound is 100:20:(20 - 30). If the amount of paraformaldehyde is too much or too little, the reaction cannot proceed smoothly.

[0027] Preferably, in step (3), the mass ratio of the active group-modified carbon nitride-molybdenum disulfide composite, phenolic compound, aldehyde compound, solvent, and catalyst is 100:20:(10 - 40):(101 - 105):(0.4 - 0.6).

[0028] Preferably, in step (3), the method of the mixed reaction includes the following steps: Mix the active group-modified carbon nitride-molybdenum disulfide composite, phenolic compound, aldehyde compound, and catalyst in a solvent and react at 60 - 70 °C for 10 - 30 min, then raise the temperature to 85 - 95 °C and continue the mixed reaction for 6 - 8 h. Further preferably, the time for the continued mixed reaction is 7.5 - 8 h.

[0029] Preferably, in step (4), the mass ratio of the phenolic resin-modified composite material and m-alkynylphenyl diazonium salt is 40:(1.5 - 6). Further preferably, in step (4), the mass ratio of the phenolic resin-modified composite material and m-alkynylphenyl diazonium salt is 40:(4.5 - 6). The role of the m-alkynylphenyl diazonium salt-modified phenolic resin-modified composite material is to improve the thermal stability and rigidity of the resin part in the plugging agent. If the amount of m-alkynylphenyl diazonium salt is too much, it will hinder the reaction between the phenolic resin-modified composite material and the m-alkynylphenyl diazonium salt. If the amount of m-alkynylphenyl diazonium salt is too little, the performance of the plugging agent will not be significantly improved.

[0030] Preferably, in step (4), the m-alkynylphenyl diazonium salt is used in the form of an m-alkynylphenyl diazonium salt solution.

[0031] The meta-alkynyl phenyl diazonium salt can be prepared by itself. For example, it can be prepared according to the method in Chinese Patent Document CN104558533B. Preferably, in step (4), the meta-alkynyl phenyl diazonium salt solution is prepared by a method including the following steps: adding m-aminophenylacetylene to hydrochloric acid, then adding a water-soluble nitrite, and then mixing and reacting at 0 °C for not less than 2 h to obtain a meta-alkynyl phenyl diazonium salt solution. Preferably, the water-soluble nitrite is sodium nitrite or potassium nitrite. Preferably, the water-soluble nitrite is used in the form of a solution. Preferably, the mass ratio of m-aminophenylacetylene, water-soluble nitrite and hydrochloric acid is 15:(0.2 - 0.4):(80 - 120). Preferably, the water-soluble nitrite is used in the form of a water-soluble nitrite solution. Preferably, the mass fraction of the water-soluble nitrite solution is 1 - 5%.

[0032] Preferably, in step (4), the alkaline liquid phase environment is mainly composed of an alkaline compound and an alcohol solvent; the alkaline compound in the alkaline liquid phase environment is an alkali metal hydroxide. Preferably, the alcohol solvent in the alkaline liquid phase environment is ethanol or propanol.

[0033] Preferably, in step (4), the mass ratio of the phenolic resin modified composite material, alkaline compound and alcohol solvent is 40:(5 - 10):(150 - 200).

[0034] Preferably, the coupling reaction time is not less than 3 h.

[0035] Preferably, the flaky carbon nitride is prepared by heating melamine to 550 - 600 °C in an inert atmosphere and holding for not less than 2 h followed by grinding. Preferably, the heating rate of the heating is 5 - 10 °C / min. Preferably, the inert atmosphere is selected from one or any combination of nitrogen, argon, and helium.

[0036] The technical solution adopted by the plugging agent of the present invention is as follows:

[0037] A plugging agent prepared by the preparation method of the above-mentioned plugging agent.

[0038] The plugging agent of the present invention has good plugging performance, heat resistance, lubricating performance and pressure-bearing capacity.

[0039] The technical solution adopted by the application of the plugging agent of the present invention in drilling fluid is as follows:

[0040] The application of the plugging agent prepared by the preparation method of the plugging agent as described above in drilling fluid.

[0041] Using the plugging agent of the present invention in drilling fluid can meet the plugging requirements of easily unstable and collapsing shale formations and is suitable for plugging fractured and karst leakage. Description of the Drawings

[0042] Figure 1 Schematic flow chart of the preparation method of the plugging agent in Embodiment 1 of the present invention;

[0043] Figure 2 Infrared spectra of the flaky carbon nitride, carbon nitride-molybdenum disulfide composite prepared in Embodiment 1 of the present invention, and commercially available molybdenum disulfide;

[0044] Figure 3 XRD spectra of the flaky carbon nitride, carbon nitride-molybdenum disulfide composite prepared in Embodiment 1 of the present invention, and commercially available molybdenum disulfide;

[0045] Figure 4 Morphology diagram of the plugging agent prepared in Embodiment 1 of the present invention;

[0046] Figure 5 Appearance diagram of the dispersion liquid prepared by adding the plugging agent prepared in Embodiment 1 of the present invention to oil-based mud and standing at room temperature for 1 h. Detailed implementation manners

[0047] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0048] I. The specific embodiments of the preparation method of the plugging agent of the present invention are as follows:

[0049] Embodiment 1

[0050] The preparation method of the plugging agent in this embodiment is as Figure 1 shown, and specifically includes the following steps:

[0051] (1) Preparation of flaky carbon nitride

[0052] Put melamine into a reactor, then heat it to 550 °C at a heating rate of 5 °C / min under a nitrogen atmosphere, keep it warm for 2 h, cool it to room temperature and then grind it to obtain flaky carbon nitride;

[0053] (2) Grafting molybdenum disulfide

[0054] Add the flaky carbon nitride, ammonium thio molybdate and N,N-dimethylformamide prepared in step (1) (the mass ratio of flaky carbon nitride, ammonium thio molybdate and N,N-dimethylformamide is 200:20:100) to a reactor, ultrasonicate for 3 h, then stir at room temperature for 1 h until ammonium thio molybdate is completely dissolved, then transfer the materials in the reactor to a high-pressure autoclave lined with polytetrafluoroethylene, heat the materials in the high-pressure autoclave to 200 °C, stand and react for 8 h, then filter the reaction system, and then wash the filtered solid with ethanol and dry it to obtain a carbon nitride-molybdenum disulfide composite;

[0055] (3) Active group modification

[0056] Add the carbon nitride-molybdenum disulfide composite prepared in step (2), sodium hydroxide, sodium sulfate and deionized water (the mass ratio of the carbon nitride-molybdenum disulfide composite, sodium hydroxide, sodium sulfate and deionized water is 100:10:15:100) into the reactor, stir at room temperature for 1 h until sodium hydroxide and sodium sulfate are completely dissolved, then transfer the materials in the reactor to an autoclave with a polytetrafluoroethylene liner, and then heat the materials in the autoclave to 120 °C, let it stand and react for 8 h, then filter the reaction system, and then wash the obtained solid by centrifugation with ethanol, and then dry the centrifugally washed solid at 60 °C to obtain the carbon nitride-molybdenum disulfide composite modified with active groups;

[0057] (4) Resin modification

[0058] Add 100 parts by weight of the carbon nitride-molybdenum disulfide composite modified with active groups prepared in step (3) and 100 parts by weight of n-butanol into a three-necked flask, heat it to 65 °C under stirring to make the materials in the three-necked flask into a stable suspension; then add 20 parts by weight of cardanol into the three-necked flask, and then stir the materials in the three-necked flask at 65 °C for 1 h, then add 10 parts by weight of paraformaldehyde, 1 part by weight of distilled water and 0.5 part by weight of p-toluenesulfonic acid into the three-necked flask in sequence, continue to stir the materials in the three-necked flask at 65 °C for 30 min for addition reaction, then heat the materials in the three-necked flask to 90 °C, continue to stir for 6 h for polycondensation reaction, and then carry out vacuum distillation on the reaction system to remove volatile substances such as the solvent n-butanol, water and unreacted paraformaldehyde to obtain a resin-modified composite material;

[0059] (5) m-Aminophenylacetylene modification

[0060] S1. Add 80 parts by weight of hydrochloric acid (mass fraction 36%) into a three-necked flask, then slowly add 15 parts by weight of m-aminophenylacetylene dropwise to the three-necked flask while stirring, after dropping, heat the materials in the three-necked flask to 60 °C, and stir and react at a constant temperature for 1 h; then cool the materials in the three-necked flask to 0 °C, and then slowly add dropwise a sodium nitrite aqueous solution containing 0.2 part by weight of sodium nitrite (the mass fraction of the sodium nitrite aqueous solution is 1%) to the three-necked flask, stir and react at a constant temperature at 0 °C for 2 h, and then filter the reaction system, and the obtained filtered liquid is the m-alkynylphenyl diazonium salt solution;

[0061] S2. Add 40 parts by weight of the resin-modified composite material prepared in step (4), 5 parts by weight of sodium hydroxide, and 150 parts by weight of absolute ethanol into a three-necked flask. Then stir the materials in the three-necked flask, and then cool the materials in the three-necked flask to 0 °C. Under stirring conditions, gradually add a solution of m-alkynylphenyl diazonium salt dropwise to the three-necked flask (the weight fraction of m-alkynylphenyl diazonium salt contained in the m-alkynylphenyl diazonium salt solution is 3 parts). After the addition is complete, stir and react at a constant temperature of 0 °C for 3 h. After the reaction is completed, gradually add hydrochloric acid dropwise to the three-necked flask to neutralize until the pH of the materials in the three-necked flask is 7. Then perform suction filtration, and then successively wash the filtered solid by centrifugation with absolute ethanol and distilled water. Then dry the washed solid at 60 °C to obtain a plugging agent.

[0062] Example 2

[0063] The preparation method of the plugging agent in this example specifically includes the following steps:

[0064] (1) Prepare flaky carbon nitride

[0065] Put melamine into a reactor, and then heat it to 550 °C at a heating rate of 5 °C / min under a nitrogen atmosphere, keep it warm for 2 h, cool it to room temperature and then grind it to obtain flaky carbon nitride;

[0066] (2) Graft molybdenum disulfide

[0067] Add the flaky carbon nitride, ammonium thiomolybdate and N,N-dimethylformamide prepared in step (1) (the mass ratio of flaky carbon nitride, ammonium thiomolybdate and N,N-dimethylformamide is 200:10:100) into a reactor, ultrasonicate for 3 h and then stir at room temperature for 1 h until ammonium thiomolybdate is completely dissolved. Then transfer the materials in the reactor to an autoclave with a polytetrafluoroethylene liner, and heat the materials in the autoclave to 180 °C, let it stand and react for 9 h. Then filter the reaction system, and then wash the filtered solid with ethanol and dry it to obtain a carbon nitride-molybdenum disulfide composite;

[0068] (3) Modify active groups

[0069] Add the carbon nitride-molybdenum disulfide composite prepared in step (2), sodium hydroxide, sodium sulfate, and deionized water (the mass ratio of the carbon nitride-molybdenum disulfide composite, sodium hydroxide, sodium sulfate, and deionized water is 100:16:20:100) into a reactor, stir at room temperature for 1 h until sodium hydroxide and sodium sulfate are completely dissolved, then transfer the materials in the reactor to an autoclave with a polytetrafluoroethylene liner, and then heat the materials in the autoclave to 100 °C, let it stand and react for 10 h, then filter the reaction system, and then wash the obtained solid by centrifugation with ethanol, and then dry the centrifugally washed solid at 60 °C to obtain a carbon nitride-molybdenum disulfide composite modified with active groups;

[0070] (4) Resin modification

[0071] Add 100 parts by weight of the carbon nitride-molybdenum disulfide composite modified with active groups prepared in step (3) and 100 parts by weight of n-butanol into a three-necked flask, heat it to 65 °C under stirring to make the materials in the three-necked flask into a stable suspension; then add 20 parts by weight of cardanol into the three-necked flask, and then stir the materials in the three-necked flask at 65 °C for 1 h, then sequentially add 10 parts by weight of paraformaldehyde, 1 part by weight of distilled water, and 0.4 part by weight of p-toluenesulfonic acid into the three-necked flask, continue to stir the materials in the three-necked flask at 60 °C for 30 min for an addition reaction, then heat the materials in the three-necked flask to 85 °C, and continue to stir for 6 h for a polycondensation reaction, and then carry out vacuum distillation on the reaction system to remove volatile substances such as the solvent n-butanol, water, and unreacted paraformaldehyde to obtain a resin-modified composite material;

[0072] (5) m-Aminophenylacetylene modification

[0073] S1, add 100 parts by weight of hydrochloric acid (mass fraction is 37%) into a three-necked flask, then slowly add 15 parts by weight of m-aminophenylacetylene dropwise to the three-necked flask while stirring, after the addition is completed, heat the materials in the three-necked flask to 60 °C, and keep stirring and reacting for 1 h; then cool the materials in the three-necked flask to 0 °C, and then slowly add dropwise a sodium nitrite aqueous solution containing 0.2 part by weight of sodium nitrite (the mass fraction of the sodium nitrite aqueous solution is 1%) to the three-necked flask, keep stirring and reacting at 0 °C for 2 h, and then filter the reaction system, and the filtered liquid is the m-alkynylphenyl diazonium salt solution;

[0074] S2, Add 40 parts by weight of the resin-modified composite material prepared in step (4), 10 parts by weight of sodium hydroxide, and 200 parts by weight of absolute ethanol into a three-necked flask. Then stir the materials in the three-necked flask, and cool the materials in the three-necked flask to 0 °C. Dropwise add a solution of m-ethynylphenyl diazonium salt (the weight fraction of m-ethynylphenyl diazonium salt contained in the m-ethynylphenyl diazonium salt solution is 3 parts) into the three-necked flask under stirring conditions. After the addition is completed, stir and react at a constant temperature of 0 °C for 3 h. After the reaction is completed, dropwise add hydrochloric acid into the three-necked flask for neutralization until the pH of the materials in the three-necked flask is 7. Then perform suction filtration, and successively centrifuge and wash the filtered solid with absolute ethanol and distilled water. Then dry the washed solid at 60 °C to obtain a plugging agent.

[0075] Example 3

[0076] The preparation method of the plugging agent in this example specifically includes the following steps:

[0077] (1) Prepare flaky carbon nitride

[0078] Put melamine into a reactor, then heat it to 550 °C at a heating rate of 5 °C / min under a nitrogen atmosphere, keep it warm for 2 h, cool it to room temperature and then grind it to obtain flaky carbon nitride;

[0079] (2) Graft molybdenum disulfide

[0080] Add the flaky carbon nitride prepared in step (1), ammonium thiomolybdate, and N,N-dimethylformamide (the mass ratio of flaky carbon nitride, ammonium thiomolybdate, and N,N-dimethylformamide is 200:15:100) into a reactor. After ultrasonic treatment for 3 h, stir at room temperature for 1 h until ammonium thiomolybdate is completely dissolved. Then transfer the materials in the reactor to an autoclave with a polytetrafluoroethylene liner, heat the materials in the autoclave to 160 °C, stand and react for 10 h. Then filter the reaction system, and wash the filtered solid with ethanol and dry it to obtain a carbon nitride-molybdenum disulfide composite;

[0081] (3) Modify active groups

[0082] Add the carbon nitride-molybdenum disulfide composite prepared in step (2), sodium hydroxide, sodium sulfate and deionized water (the mass ratio of the carbon nitride-molybdenum disulfide composite, sodium hydroxide, sodium sulfate and deionized water is 100:13:18:100) into a reactor, stir at room temperature for 1 h until sodium hydroxide and sodium sulfate are completely dissolved, then transfer the materials in the reactor to an autoclave with a polytetrafluoroethylene liner, and then heat the materials in the autoclave to 110 °C, let it stand and react for 9 h, then filter the reacted system, and then wash the obtained solid by centrifugation with ethanol, and then dry the centrifuged and washed solid at 60 °C to obtain a carbon nitride-molybdenum disulfide composite modified with active groups;

[0083] (4) Resin modification

[0084] Add 100 parts by weight of the carbon nitride-molybdenum disulfide composite modified with active groups prepared in step (3) and 100 parts by weight of n-butanol into a three-necked flask, heat up to 65 °C under stirring to make the materials in the three-necked flask into a stable suspension; then add 20 parts by weight of cardanol into the three-necked flask, and then stir the materials in the three-necked flask at 65 °C for 1 h, then add 10 parts by weight of paraformaldehyde, 1 part by weight of distilled water and 0.6 part by weight of p-toluenesulfonic acid into the three-necked flask in sequence, continue to stir the materials in the three-necked flask at 70 °C for 30 min for an addition reaction, then heat the materials in the three-necked flask to 95 °C, continue to stir for 6 h for a polycondensation reaction, and then carry out vacuum distillation on the reacted system to remove volatile substances such as the solvent n-butanol, water and unreacted paraformaldehyde to obtain a resin-modified composite material;

[0085] (5) m-Aminophenylacetylene modification

[0086] S1, add 120 parts by weight of hydrochloric acid (mass fraction is 36%) into a three-necked flask, then slowly add 15 parts by weight of m-aminophenylacetylene dropwise to the three-necked flask while stirring, after the dropping is completed, heat up the materials in the three-necked flask to 60 °C, and stir and react at a constant temperature for 1 h; then cool down the materials in the three-necked flask to 0 °C, and then slowly add dropwise a sodium nitrite aqueous solution containing 0.2 part by weight of sodium nitrite (the mass fraction of the sodium nitrite aqueous solution is 1%) to the three-necked flask, stir and react at a constant temperature at 0 °C for 2 h, and then filter the reacted system, and the obtained filtered liquid is the m-alkynylphenyl diazonium salt solution;

[0087] S2, add 40 parts by weight of the resin-modified composite material prepared in step (4), 8 parts by weight of sodium hydroxide, and 180 parts by weight of absolute ethanol into a three-necked flask. Then stir the materials in the three-necked flask, and cool the materials in the three-necked flask to 0 °C. Dropwise add a solution of m-ethynylphenyl diazonium salt (the weight fraction of m-ethynylphenyl diazonium salt contained in the solution of m-ethynylphenyl diazonium salt is 3 parts) into the three-necked flask under stirring conditions. After the addition is completed, stir and react at a constant temperature of 0 °C for 3 h. After the reaction is completed, dropwise add hydrochloric acid into the three-necked flask for neutralization until the pH of the materials in the three-necked flask is 7. Then perform suction filtration, and successively centrifuge and wash the filtered solid with absolute ethanol and distilled water. Then dry the washed solid at 60 °C to obtain a plugging agent.

[0088] Example 4

[0089] The difference between the preparation method of the plugging agent in this example and the preparation method of the plugging agent in Example 1 is only that in step (3) of the preparation method of the plugging agent in this example, the mass ratio of carbon nitride-molybdenum disulfide composite to sodium hydroxide is adjusted from 100:10 to 100:12, and the mass of the carbon nitride-molybdenum disulfide composite remains unchanged.

[0090] Example 5

[0091] The difference between the preparation method of the plugging agent in this example and the preparation method of the plugging agent in Example 1 is only that in step (3) of the preparation method of the plugging agent in this example, the mass ratio of carbon nitride-molybdenum disulfide composite to sodium hydroxide is adjusted from 100:10 to 100:14, and the mass of the carbon nitride-molybdenum disulfide composite remains unchanged.

[0092] Example 6

[0093] The difference between the preparation method of the plugging agent in this example and the preparation method of the plugging agent in Example 1 is only that in step (3) of the preparation method of the plugging agent in this example, the mass ratio of carbon nitride-molybdenum disulfide composite to sodium hydroxide is adjusted from 100:10 to 100:16, and the mass of the carbon nitride-molybdenum disulfide composite remains unchanged.

[0094] Example 7

[0095] The difference between the preparation method of the plugging agent in this example and the preparation method of the plugging agent in Example 1 is only that in step (3) of the preparation method of the plugging agent in this example, sodium hydroxide is replaced by acetic acid.

[0096] Example 8

[0097] The difference between the preparation method of the plugging agent in this example and that in Example 1 is only that in step (3) of the preparation method of the plugging agent in this example, sodium hydroxide is replaced by urea.

[0098] Example 9

[0099] The difference between the preparation method of the plugging agent in this example and that in Example 1 is only that in step (3) of the preparation method of the plugging agent in this example, sodium hydroxide is replaced by potassium cyanide.

[0100] Example 10

[0101] The difference between the preparation method of the plugging agent in this example and that in Example 1 is only that in step (4) of the preparation method of the plugging agent in this example, the weight portion of paraformaldehyde is adjusted from 10 parts to 20 parts.

[0102] Example 11

[0103] The difference between the preparation method of the plugging agent in this example and that in Example 1 is only that in step (4) of the preparation method of the plugging agent in this example, the weight portion of paraformaldehyde is adjusted from 10 parts to 30 parts.

[0104] Example 12

[0105] The difference between the preparation method of the plugging agent in this example and that in Example 1 is only that in step (4) of the preparation method of the plugging agent in this example, the weight portion of paraformaldehyde is adjusted from 10 parts to 40 parts.

[0106] Example 13

[0107] The difference between the preparation method of the plugging agent in this example and that in Example 1 is only that in step (4) of the preparation method of the plugging agent in this example, cardanol is replaced by bisphenol A.

[0108] Example 14

[0109] The difference between the preparation method of the plugging agent in this example and that in Example 1 is only that in step (4) of the preparation method of the plugging agent in this example, cardanol is replaced by resorcinol.

[0110] Example 15

[0111] The difference between the preparation method of the plugging agent in this example and that in Example 1 is only that in step (4) of the preparation method of the plugging agent in this example, cardanol is replaced by hydroquinone.

[0112] Example 16

[0113] The difference between the preparation method of the plugging agent in this example and that in Example 1 is only that in step (4) of the preparation method of the plugging agent in this example, 10 parts by weight of paraformaldehyde is replaced with a formaldehyde solution containing 10 parts by weight of formaldehyde (the mass fraction of the formaldehyde solution is 37%).

[0114] Example 17

[0115] The difference between the preparation method of the plugging agent in this example and that in Example 1 is only that in step (4) of the preparation method of the plugging agent in this example, the time of the addition reaction is adjusted from 30 min to 10 min.

[0116] Example 18

[0117] The difference between the preparation method of the plugging agent in this example and that in Example 1 is only that in step (4) of the preparation method of the plugging agent in this example, the time of the addition reaction is adjusted from 30 min to 20 min.

[0118] Example 19

[0119] The difference between the preparation method of the plugging agent in this example and that in Example 1 is only that in step (4) of the preparation method of the plugging agent in this example, the time of the polycondensation reaction is adjusted from 6 h to 6.5 h.

[0120] Example 20

[0121] The difference between the preparation method of the plugging agent in this example and that in Example 1 is only that in step (4) of the preparation method of the plugging agent in this example, the time of the polycondensation reaction is adjusted from 6 h to 7 h.

[0122] Example 21

[0123] The difference between the preparation method of the plugging agent in this example and that in Example 1 is only that in step (4) of the preparation method of the plugging agent in this example, the time of the polycondensation reaction is adjusted from 6 h to 7.5 h.

[0124] Example 22

[0125] The difference between the preparation method of the plugging agent in this example and that in Example 1 is only that in step (4) of the preparation method of the plugging agent in this example, the time of the polycondensation reaction is adjusted from 6 h to 8 h.

[0126] Example 23

[0127] The preparation method of the plugging agent in this example is only different from the preparation method of the plugging agent in Example 1 in that in step (5) of the preparation method of the plugging agent in this example, the sodium nitrite aqueous solution containing 0.2 parts by weight of sodium nitrite is adjusted to an equal-concentration sodium nitrite aqueous solution containing 0.3 parts by weight of sodium nitrite.

[0128] Example 24

[0129] The preparation method of the plugging agent in this example is only different from the preparation method of the plugging agent in Example 1 in that in step (5) of the preparation method of the plugging agent in this example, the sodium nitrite aqueous solution containing 0.2 parts by weight of sodium nitrite is adjusted to an equal-concentration sodium nitrite aqueous solution containing 0.4 parts by weight of sodium nitrite.

[0130] Example 25

[0131] The preparation method of the plugging agent in this example is only different from the preparation method of the plugging agent in Example 1 in that in step (5) of the preparation method of the plugging agent in this example, the mass of the m-alkynylphenyl diazonium salt solution is increased so that the weight fraction of m-alkynylphenyl diazonium salt in the added m-alkynylphenyl diazonium salt solution is 1.5 parts.

[0132] Example 26

[0133] The preparation method of the plugging agent in this example is only different from the preparation method of the plugging agent in Example 1 in that in step (5) of the preparation method of the plugging agent in this example, the mass of the m-alkynylphenyl diazonium salt solution is increased so that the weight fraction of m-alkynylphenyl diazonium salt in the added m-alkynylphenyl diazonium salt solution is 4.5 parts.

[0134] Example 27

[0135] The preparation method of the plugging agent in this example is only different from the preparation method of the plugging agent in Example 1 in that in step (5) of the preparation method of the plugging agent in this example, the mass of the m-alkynylphenyl diazonium salt solution is increased so that the weight fraction of m-alkynylphenyl diazonium salt in the added m-alkynylphenyl diazonium salt solution is 6 parts.

[0136] Comparative Example 1

[0137] The preparation method of the plugging agent in this comparative example is only different from the preparation method of the plugging agent in Example 1 in that in the preparation method of the plugging agent in this comparative example, step (2) is omitted, that is, instead of grafting molybdenum disulfide onto the flaky carbon nitride, the flaky carbon nitride is directly subjected to active group modification and then the plugging agent is prepared.

[0138] Comparative Example 2

[0139] The difference between the preparation method of the plugging agent in this comparative example and that of the plugging agent in Example 1 is only that in the preparation method of the plugging agent in this comparative example, steps (1) and (2) are omitted, and the flaky molybdenum disulfide (the flake diameter of the flaky molybdenum disulfide is the same as that of the flaky carbon nitride prepared in Example 1) is directly subjected to active group modification, and then the plugging agent is prepared.

[0140] Comparative Example 3

[0141] The difference between the preparation method of the plugging agent in this comparative example and that of the plugging agent in Example 1 is only that in the preparation method of the plugging agent in this comparative example, m-aminophenylacetylene is replaced by aniline in step (5).

[0142] II. Specific examples of the plugging agent of the present invention are as follows:

[0143] The plugging agent of this example is prepared by the preparation method of any one of the plugging agents in Examples 1-3, which will not be elaborated here.

[0144] III. Specific examples of the application of the plugging agent of the present invention in drilling fluid are as follows:

[0145] The plugging agent prepared by the preparation method of the plugging agents in Examples 1-3 can be used in the drilling fluid.

[0146] Experimental Example 1

[0147] To verify whether the flaky carbon nitride and the carbon nitride-molybdenum disulfide composite are successfully synthesized, the infrared spectra and XRD spectra of the flaky carbon nitride prepared in step (1) of Example 1, the carbon nitride-molybdenum disulfide composite prepared in step (2), and commercially available molybdenum disulfide were tested, and the results are respectively as Figures 2 - 3 shown. Figure 2 In, g-C 3 N 4 represents the infrared spectrum of flaky carbon nitride, MoS 2 represents the infrared spectrum of molybdenum disulfide, MoS 2 / g-C 3 N 4 represents the infrared spectrum of the carbon nitride-molybdenum disulfide composite. Figure 3 In, g-C 3 N 4 represents the XRD spectrum of flaky carbon nitride, MoS 2 represents the XRD spectrum of molybdenum disulfide, MoS 2 / g-C 3 N 4 represents the XRD spectrum of the carbon nitride-molybdenum disulfide composite.

[0148] To characterize the structure of the plugging agent, the morphology of the plugging agent prepared in Example 1 was tested by transmission electron microscopy, and the results are asFigure 4 as shown Figure 4 a and Figure 4 b respectively represent the morphological diagrams of the plugging agent observed from different angles.

[0149] Experimental Example 2

[0150] To test the dispersion stability of the plugging agent, the plugging agents prepared in Examples 1-27 and Comparative Examples 1-3 were tested for the oil absorption expansion rate. The test method for the oil absorption expansion rate is as follows: Measure 300 mL of white oil with a stoppered graduated cylinder, weigh 30 g of the plugging agent and pour it into the stoppered graduated cylinder, and let it stand for 30 min. After all the plugging agent sinks to the bottom and the liquid phase becomes clear, read the initial volume V 0 mL, then let it stand for 16 h, and then read the volume V of the mixture in the stoppered graduated cylinder 1 mL. Finally, calculate the oil absorption expansion rate. The oil absorption expansion rate = (V 1 - V 0 ) mL / 30 g. The oil absorption expansion rates of the plugging agents prepared in Examples 1-27 and Comparative Examples 1-3 are shown in Table 1.

[0151] Table 1 Oil absorption expansion rates of the plugging agents prepared in Examples 1-27 and Comparative Examples 1-3

[0152] Plugging agent Oil absorption expansion ratio (mL / g) Plugging agent Oil absorption expansion ratio (mL / g) Example 1 3 Example 16 3.4 Example 2 3.1 Example 17 3.2 Example 3 3.1 Example 18 3.3 Example 4 3.1 Example 19 3.6 Example 5 3.0 Example 20 3.5 Example 6 3.3 Example 21 3.7 Example 7 3.2 Example 22 3.2 Example 8 3.0 Example 23 3.1 Example 9 3.2 Example 24 3.5 Example 10 3.8 Example 25 3.8 Example 11 3.5 Example 26 3.4 Example 12 3.6 Example 27 3.0 Example 13 3.5 Comparative Example 1 3.9 Example 14 3.0 Comparative Example 2 3.8 Example 15 3.2 Comparative Example 3 3.9

[0153] Experimental Example 3

[0154] To test the dispersion stability of the plugging agent in the drilling fluid, the plugging agents prepared in Examples 1-27 were added to the oil-based mud (the mass of the plugging agent is 3% of the mass of the oil-based mud), stirred evenly to obtain a dispersion, and then the dispersion performance of the plugging agent in the dispersion was observed. The appearance diagram of the dispersion prepared by adding the plugging agent prepared in Example 1 to the oil-based mud when it was placed at room temperature for 1 h is as Figure 5 shown. The results show that the plugging agents prepared in Examples 1-27 can be evenly dispersed in the oil-based mud.

[0155] To evaluate the plugging performance and heat resistance of the plugging agents prepared in Examples 1-27 and Comparative Examples 1-3, the plugging agents prepared in Examples 1-27 and Comparative Examples 1-3 were respectively added to the oil-based mud (the mass of the plugging agent is 3% of the mass of the oil-based mud) to obtain oil-based drilling fluids, and then the plugging performance of each oil-based drilling fluid and the plugging performance of each oil-based drilling fluid after hot rolling at 120 °C for 12 h were tested.

[0156] The oil-based mud used in this experimental example is composed of barite powder and the following components by mass fraction: 2% main emulsifier + 2.4% auxiliary emulsifier + 2.5% organophilic clay + 3% alkaline regulator + 2% wetting agent + 4% fluid loss reducer (oxidized asphalt) + 20% calcium chloride aqueous solution (mass fraction of 25%), and the balance is a mixed solvent composed of diesel and water with a volume ratio of 4:1. The density of the oil-based mud is 1.4 g / cm 3 ; the main emulsifier is sodium hydroxysulfopropyl methacrylate, the auxiliary emulsifier is allyloxynonylphenol polyoxyethylene ether, the alkaline regulator is calcium oxide, and the wetting agent is sodium allyloxyhydroxypropylsulfonate.

[0157] The test method for the plugging performance is as follows: Add the plugging agent to the oil-based mud to obtain an oil-based drilling fluid, and then use a non-permeable drilling fluid filter loss instrument developed and produced by Qingdao Haitongda Special Instrument Factory for testing. The specific operation is as follows: Ensure that the instrument is clean before use. Pour 40-60 mesh sand into a graduated plexiglass container, and then add the oil-based drilling fluid until the oil-based drilling fluid reaches the 500 mL graduation line. Place the measuring cylinder under the plexiglass. Open the air source handle and slowly turn the pressure reducing valve handle clockwise. Observe the pressure gauge indication and make it stable at 0.7 MPa; Mark the initial intrusion depth (L 1 ) of the oil-based drilling fluid before opening the control switch; While marking the initial intrusion depth, slowly turn the control handle clockwise and observe the pressure gauge indication at the same time. A slight instantaneous drop in the pressure gauge (or hearing the sound of air intake in the cylinder) indicates completion; Record the depth of the oil-based drilling fluid invading the sand bed every ten minutes. When the test time reaches 30 minutes, turn the control handle counterclockwise to loosen it, and at this time, cut off the air source path; Finally, record the depth (L 2 ) of the oil-based drilling fluid invading the sand bed at the end of the experiment.

[0158] The test results of the plugging performance and heat resistance of the plugging agents prepared in Examples 1-27 and Comparative Examples 1-3 are shown in Table 2.

[0159] Table 2 Plugging performance and heat resistance of the plugging agents prepared in Examples 1-27 and Comparative Examples 1-3

[0160]

[0161]

Claims

1. A method for preparing a plugging agent, characterized in that: The following steps are involved: (1) mixing a flaky carbon nitride and a molybdenum disulfide precursor in an organic solvent, and then performing a solvothermal reaction to obtain a carbon nitride-molybdenum disulfide composite; (2) using a modifying substance to modify the active groups of the carbon nitride-molybdenum disulfide composite to obtain an active group-modified carbon nitride-molybdenum disulfide composite, wherein the active groups are selected from one or any combination of hydroxyl, carboxyl, and amino groups; (3) mixing the active group-modified carbon nitride-molybdenum disulfide composite, a phenolic compound, an aldehyde compound and a catalyst in a solvent to react so as to in-situ synthesize a phenolic resin on the active group-modified carbon nitride-molybdenum disulfide composite to obtain a phenolic resin-modified composite material; (4) performing a coupling reaction between the phenolic resin modified composite material and meta-alkynylphenyl diazonium salt in an alkaline liquid environment at a temperature below 0° C. to obtain a plugging agent.

2. The method for preparing a plugging agent according to claim 1, characterized in that: In step (1), the mass ratio of the flaky carbon nitride, the molybdenum disulfide precursor and the organic solvent is 200:(10-20):100; in step (1), the temperature of the solvent thermal reaction is 160-200° C., and the time of the solvent thermal reaction is 8-10 hours.

3. The method for preparing a leak plugging agent according to claim 1 or 2, characterized in that: The molybdenum disulfide precursor is ammonium thiomolybdate; in step (1), the organic solvent is selected from one or any combination of N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, and N,N-diethylacetamide.

4. The method for preparing the plugging agent according to claim 1, characterized in that: In step (2), the modified substance includes an active substance and a water-soluble sulfate; the active substance is an alkaline compound, an acidic compound, urea or a water-soluble cyanide salt; in step (2), the method for modifying the active group includes the following steps: allowing the carbon nitride-molybdenum disulfide complex and the modified substance to react in water under sealed conditions; the temperature of the static reaction for the modification of the active group is 100 to 120° C., and the time is 8 to 10 hours.

5. The method for preparing the plugging agent according to claim 4, characterized in that: The alkaline compound is an alkali metal hydroxide; the acidic compound is a carboxylic acid compound; the water-soluble cyanide salt is sodium cyanide or potassium cyanide; the water-soluble sulfate salt is sodium sulfate or potassium sulfate; in step (2), the mass ratio of the carbon nitride-molybdenum disulfide complex, the active substance, the water-soluble sulfate salt and water is 100:(10-16):(15-20):

100.

6. The method for preparing the plugging agent according to claim 1, characterized in that: In step (3), the phenolic compound is selected from one or any combination of cardanol, bisphenol A, resorcinol, and hydroquinone; the aldehyde compound is paraformaldehyde and / or formaldehyde; the catalyst is an acidic catalyst; the solvent includes an alcohol solvent and water; and the mass ratio of the active group-modified carbon nitride-molybdenum disulfide complex, the phenolic compound, and the aldehyde compound is 100:20:(10-40).

7. The method for preparing the plugging agent according to claim 1 or 6, characterized in that: In step (3), the mixing reaction method comprises the following steps: mixing the active group-modified carbon nitride-molybdenum disulfide complex, phenolic compound, aldehyde compound and catalyst in a solvent at 60-70° C. for 10-30 min, then heating to 85-95° C. and continuing the mixing reaction for 6-8 h.

8. The method for preparing a leak-proof agent according to claim 1, characterized in that: In step (4), the mass ratio of the phenolic resin modified composite material to the meta-alkynylphenyl diazonium salt is 40:(1.5-6); and the coupling reaction time is not less than 3 hours.

9. A plugging agent prepared by the method for preparing a plugging agent according to any one of claims 1 to 8.

10. Use of a plugging agent prepared by the method for preparing a plugging agent according to any one of claims 1 to 8 in drilling fluid.

Images