Molybdenum disulfide nanoplatelets modified urea-formaldehyde / melamine resin and preparation and application thereof

Abstract

The application discloses a kind of molybdenum disulfide nanosheet modified urea formaldehyde / melamine resin and its preparation and application, the preparation method of the molybdenum disulfide nanosheet modified urea formaldehyde / melamine resin includes the following steps: (1) using hydrothermal synthesis method to make sulfur source and molybdenum source into molybdenum disulfide nanosheet;(2) the surface functional group modifier is used to the surface functional group modification of the molybdenum disulfide nanosheet;(3) aldehyde, the polyamine group compound containing with the surface functional group modified molybdenum disulfide nanosheet in the step (2) is carried out copolymerization, and molybdenum disulfide nanosheet urea formaldehyde / melamine resin is obtained;(4) using silane coupling agent to the molybdenum disulfide nanosheet urea formaldehyde / melamine resin is modified, and molybdenum disulfide nanosheet modified urea formaldehyde / melamine resin is obtained.The method of the application grafts polymer copolymerization to molybdenum disulfide nanosheet, effectively solves the problem of insufficient temperature resistance of urea formaldehyde / melamine resin, and the problem of poor compression resistance after consolidating core.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of molybdenum disulfide nanosheet modified urea formaldehyde / melamine resin and its preparation and application. BACKGROUND

[0002] About 70% of the world's oil resources are located in the reservoir with poor consolidation degree, which are usually relatively young in geological age, and have not been consolidated by mineral deposition in the natural process, so many reservoirs are prone to sand production. Sand production is particularly evident under the conditions of stress change, high oil production rate, hole collapse and formation water. Production of sand brings high cost and many troubles to the oil industry, such as it may cause damage to downhole and surface equipment, resulting in serious safety problems including blowout and shutdown; sand production also reduces the oil production of production well, which requires more wells to achieve stable total production, resulting in increased cost.

[0003] Various sand consolidation methods are used in oil production site to reduce sand production during production process, such as resin-coated particle solid filling formation, resin cementing loose sand, etc. Resin cementing loose sand has the advantages of short well site preparation time and low injection pressure, and the resins commonly used in sand consolidation process at present include epoxy resin, polyester resin, phenolic resin, urea formaldehyde resin, furan resin, etc. However, the resins used at present have the following defects at high temperature: (1) curing speed is too fast, which has been cured before injection into the formation; (2) compressive strength is low, which cannot meet the demand of sand consolidation under high liquid production rate; (3) poor resistance to formation fluid; (4) low permeability retention rate.

[0004] Studies have shown that adding nano materials to resin sand consolidation agent can improve the temperature resistance of resin sand consolidation agent, because nano materials participate in the curing reaction with resin sand consolidation agent. However, nano materials are not easy to disperse in polymers, and even can accelerate the agglomeration speed of nano materials. At the same time, due to the van der Waals force between nano materials and polymers, chromatographic separation will occur at high temperature, resulting in agglomeration of nano materials. SUMMARY

[0005] In order to improve the temperature resistance and thermodynamic properties of urea formaldehyde / melamine resin by using molybdenum disulfide nanosheet, and at the same time improve the dispersity of molybdenum disulfide nanosheet in urea formaldehyde / melamine resin, the present application is made.

[0006] As a first aspect of the present application, a preparation method of molybdenum disulfide nanosheet modified urea formaldehyde / melamine resin is provided, comprising the following steps:

[0007] (1) using hydrothermal synthesis method to prepare molybdenum disulfide nanosheet from sulfur source and molybdenum source;

[0008] (2) surface functional group modification of the molybdenum disulfide nanosheets by using a surface functional group modifier;

[0009] (3) copolymerization of aldehydes, polyamine-containing compounds and the molybdenum disulfide nanosheets surface functional group modified in step (2) to obtain molybdenum disulfide nanosheet urea-formaldehyde / melamine resin;

[0010] (4) modification of the molybdenum disulfide nanosheet urea-formaldehyde / melamine resin by using a silane coupling agent to obtain molybdenum disulfide nanosheet modified urea-formaldehyde / melamine resin.

[0011] In one or some optional embodiments, the step (1) specifically comprises:

[0012] A molybdenum source and a sulfur source in a molar ratio of 1:5-1:15 are added into a 30% isopropanol aqueous solution and stirred for 10-20 minutes; then the mixed solution is subjected to hydrothermal reaction at 160-200°C for 12-24 hours; and the product after the hydrothermal reaction is washed with deionized water to obtain molybdenum disulfide nanosheets.

[0013] In one or some optional embodiments, the molybdenum source comprises one or a combination of two or more of molybdenum trioxide, molybdenum pentachloride and sodium molybdate; more preferably, the molybdenum source is molybdenum trioxide.

[0014] In one or some optional embodiments, the sulfur source comprises one or a combination of two or more of thiourea, potassium thiocyanate, potassium sulfide and thioformamide.

[0015] In one or some preferred embodiments, the temperature of the hydrothermal reaction is 180°C and the reaction time is 20 hours.

[0016] In one or some optional embodiments, the step (2) specifically comprises:

[0017] The molybdenum disulfide nanosheets and the surface modification functional group agent are added into deionized water, stirred and reacted, then the product obtained after the reaction is washed with deionized water to remove the unreacted surface modification functional group agent, and dried to obtain the surface modification functional group molybdenum disulfide nanosheets.

[0018] In one or some optional embodiments, the size of the molybdenum disulfide nanosheets is 100-500 nm, preferably 100-200 nm.

[0019] In one or some optional embodiments, the mass ratio of the molybdenum disulfide nanosheets and the surface modification functional group agent is 1:1-1:10, preferably 1:1.

[0020] In one or some preferred embodiments, the surface modification functional group agent is urea.

[0021] In one or some optional embodiments, the stirring reaction refers to ultrasonic treatment at room temperature for 5-15 min, preferably 10 min, and then stirring reaction at 60°C for 6-12 h, preferably 10 h.

[0022] In one or some optional embodiments, the ultrasonic power is 10-25 Hz, preferably 19.2 Hz, and the stirring speed is 500-1500 rpm, preferably 1000 rpm.

[0023] In one or some optional embodiments, the drying temperature is 50-90°C, preferably 50°C.

[0024] In one or some optional embodiments, the step (3) specifically comprises the following steps:

[0025] (301) adding aldehyde and the first batch of compound containing polyamine group into a four-necked flask, adjusting the pH value of the solution to 8-9.5 with 40% sodium hydroxide solution, and reacting at 80-90°C for 20-45 min;

[0026] (302) adding the second batch of compound containing polyamine group and the surface-modified functional group of molybdenum disulfide nanosheet, adjusting the pH value to 4.5-5.5 with 40% formic acid solution, and reacting at 80-90°C until the system is viscous;

[0027] (303) reducing the reaction temperature to 50-70°C, adjusting the pH value of the solution to 7.0-8.5 with 40% sodium hydroxide solution, adding the third batch of compound containing polyamine group, and cooling to room temperature after reacting for 15-30 min to obtain molybdenum disulfide nanosheet urea / formaldehyde / melamine resin.

[0028] In one or some optional embodiments, the molar ratio of the compound containing polyamine group to aldehyde is 1:1-1:3.

[0029] In one or some optional embodiments, the mass ratio of aldehyde and compound containing polyamine group to surface-modified functional group of molybdenum disulfide nanosheet is 200:1-10:1, preferably 100:1-50:1.

[0030] In one or some optional embodiments, the aldehyde is selected from one or a combination of two of formaldehyde, methenamine, and paraformaldehyde.

[0031] In one or some optional embodiments, the compound containing polyamine group is selected from one or a combination of two of urea and melamine.

[0032] In one or some optional embodiments, the first batch of polyamine-containing compounds accounts for 30-50% of the total mass; the second batch of polyamine-containing compounds accounts for 30-40% of the total mass; and the third batch of polyamine-containing compounds accounts for 10-40% of the total mass.

[0033] In one or some optional embodiments, the step (4) specifically comprises the following steps:

[0034] The molybdenum disulfide nanosheet urea-formaldehyde / melamine resin is dissolved in acetone, then a silane coupling agent is added, and the mixture is reacted at 80-95℃ for 3-5h, and then the organic solvent is removed under reduced pressure to obtain the molybdenum disulfide nanosheet modified urea-formaldehyde / melamine resin.

[0035] In one or some optional embodiments, the mass ratio of the molybdenum disulfide nanosheet urea-formaldehyde / melamine resin to the silane coupling agent is 1:5-1:30, preferably 1:10-1:15.

[0036] In one or some optional embodiments, the silane coupling agent is selected from one or more than two combinations of γ-ethylenediamine propyl methyl dimethoxy silane, γ-aminopropyl triethoxysilane, γ-aminopropyl trimethoxysilane, N-β-(aminoethyl)-γ-aminopropyl methyl dimethoxy silane and N-β-(aminoethyl)-γ-aminopropyl trimethoxysilane.

[0037] As a second aspect of the present application, the molybdenum disulfide nanosheet modified urea-formaldehyde / melamine resin prepared by the above method is provided.

[0038] As a third aspect of the present application, the use of the above molybdenum disulfide nanosheet modified urea-formaldehyde / melamine resin in oil field sand prevention is provided.

[0039] In the method provided by the present application, the molybdenum disulfide nanosheet can be prepared by controlling the hydrothermal synthesis temperature and the molybdenum-sulfur ratio, so that the crystal structure of the obtained molybdenum disulfide nanosheet is in the 1T form, and then the surface of the molybdenum disulfide nanosheet is modified with a functional group, which improves the dispersion of the molybdenum disulfide nanosheet in the polymer and increases the stability of the nanosheet material. The urea-formaldehyde / melamine resin is physically or chemically adsorbed on the surface of the sand and gravel to consolidate multiple sand and gravel together, but the linear chain is in a curled shape in the solution and has limited adsorption on the surface of the sand and gravel. After linking the urea-formaldehyde / melamine resin to the molybdenum disulfide nanosheet, there are multiple strong adsorption sites on the surface of the nanosheet, so that the combination with the sand and gravel is stronger, and the cementation strength is greatly enhanced.

[0040] The preparation method provided by the present application increases the rigidity strength of the polymer by copolymerization grafting of the polymer to the molybdenum disulfide nanosheet, thereby increasing the temperature resistance of the polymer. In addition, the multi-gripping structure can increase the compressive strength while maintaining high permeability retention rate. The preparation method effectively solves the problems of insufficient temperature resistance of urea-formaldehyde / melamine resin and poor compressive resistance after the consolidation of the core. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 Flow chart for preparing the molybdenum disulfide nanosheet modified urea-formaldehyde / melamine resin;

[0042] Figure 2 SEM image of the molybdenum disulfide nanosheet prepared in Example 1;

[0043] Figure 3 SEM image of the molybdenum disulfide nanosheet prepared in Example 2;

[0044] Figure 4 SEM image of the molybdenum disulfide nanosheet prepared in Comparative Example 4;

[0045] Figure 5 Permeability retention rate experimental data graph of different examples and comparative examples;

[0046] Figure 6 Compressive strength experimental data graph of different examples and comparative examples;

[0047] Figure 7 Infrared spectrum of the molybdenum disulfide nanosheet modified urea-formaldehyde resin synthesized in Example 1;

[0048] Figure 8 Infrared spectrum of the molybdenum disulfide nanosheet modified melamine resin synthesized in Example 2. DETAILED DESCRIPTION

[0049] The following detailed description of the embodiments of the present application is given on the premise of the technical solution of the present application, and detailed implementation modes and processes are given, but the protection scope of the present application is not limited to the following examples, and the process parameters not specified in the following examples are usually according to the conventional conditions.

[0050] The endpoints of the ranges and any values disclosed in the present application are not limited to the precise values stated. The ranges or values should be interpreted as being approximate. The endpoints of the ranges of values, the values of the ranges, and the values of individual points can be combined with one another to form new ranges or points, which are also within the scope of the present application.

[0051] The inventor implements the related technical scheme according to the literature "Wu Lin, Ouyang Zhaohui, Cao Shuchao, Yi Delian, Qin Xiaorong, Wang Yan. Research on coal tar modified phenolic resin [J]. Chemical Industry and Engineering, 2005 (04): 17-19.", and finds that the coal tar modified phenolic resin can improve the temperature resistance of the phenolic resin, but the polycyclic aromatic hydrocarbon compound in the coal tar is not high in activity, and the addition amount of the coal tar is not easy to control.

[0052] Based on the above, the inventor has not achieved the expected result, and therefore makes the present application.

[0053] The present application embodiment refers to the flow chart for preparing the molybdenum disulfide nanosheet modified urea formaldehyde / melamine resin shown in the drawing, and the molybdenum disulfide nanosheet modified urea formaldehyde / melamine resin is prepared, and the steps are as follows: Figure 1

[0054] (1) The sulfur source and the molybdenum source are mixed and then subjected to a hydrothermal reaction to obtain 1T molybdenum disulfide nanosheets;

[0055] (2) The 1T molybdenum disulfide nanosheets are subjected to surface functional group modification by using urea as a surface functional group modifier;

[0056] (3) The aldehyde, the polyamine group-containing compound and the 1T molybdenum disulfide nanosheets subjected to surface functional group modification in step (2) are subjected to a copolymerization reaction to obtain molybdenum disulfide nanosheet urea formaldehyde / melamine resin;

[0057] (4) The molybdenum disulfide nanosheet urea formaldehyde / melamine resin is modified by using a silane coupling agent to obtain molybdenum disulfide nanosheet modified urea formaldehyde / melamine resin.

[0058] Embodiment 1

[0059] The present embodiment prepares molybdenum disulfide nanosheet modified urea formaldehyde resin, and the steps are as follows:

[0060] (1) 3g of molybdenum trioxide powder and 7.92g of thiourea are added to 100mL of 30% isopropanol solution, stirred for 10min, and then the mixed solution is poured into a hydrothermal reaction kettle and reacted at 180℃ for 20 hours. Then, the molybdenum disulfide nanosheets are obtained by washing with deionized water.

[0061] (2) The synthesized molybdenum disulfide nanosheets and urea are added to deionized water in a mass ratio of 1:1, ultrasonically treated at room temperature for 10min, and then stirred at 60℃ and 1000rpm for 10 hours. Then, the unreacted urea is removed by washing with deionized water, and the molybdenum disulfide nanosheets with surface modified functional groups are obtained after drying at 50℃.

[0062] ​(3) Add 2g of urea and 7.5g of formaldehyde to a four-necked flask, adjust the pH to 9 with 40% sodium hydroxide solution, and react at 90℃ for 30min; add 2g of urea and 0.25g of molybdenum disulfide nanosheets with surface-modified functional groups to a reaction vessel, and adjust the pH to 4.5 with 40% formic acid solution, and react until the system becomes viscous; cool to 60℃, adjust the pH to 8 with 40% sodium hydroxide solution, and then add 1g of urea again, react for 15min and then cool to room temperature to obtain molybdenum disulfide nanosheet urea-formaldehyde resin.

[0063] (4) Dissolve 1g of molybdenum disulfide nanosheet urea-formaldehyde resin in acetone, add 5g of γ-aminopropyltriethoxysilane, react at 85°C for 5 hours, and then remove the organic solvent under reduced pressure to obtain molybdenum disulfide nanosheet modified urea-formaldehyde resin.

[0064] The SEM image of the molybdenum disulfide nanosheets modified urea-formaldehyde resin is shown below. Figure 2 As shown, by Figure 2 As can be seen, the molybdenum disulfide nanosheets exhibit uniform and stable morphology, clear boundaries, and a complete sheet-like structure. The infrared spectrum of the urea-formaldehyde resin modified with these molybdenum disulfide nanosheets is shown below. Figure 7 As shown, 3405cm -1 It is the stretching vibration peak of -OH; 2952 cm⁻¹ -1 CH stretching vibration of methyl group; 1666 cm⁻¹ -1 The stretching vibration of C=O, i.e., the phthalamide I band, is 1564 cm⁻¹. -1 The phthalamide n-band originates from the coupling of in-plane bending vibrations of the NH bond and partial stretching vibrations of the CN bond; at 1405 cm⁻¹ -1 This is a CH stretching vibration; 1133 cm -1 The stretching vibrations of CO and CN bonds in the aliphatic ether bonds of phthalamide II; 1001 cm⁻¹ -1 This is the deformation vibration of CO on hydroxymethyl; 842 cm -1 The CO stretching vibration of the methylene ether bond is located at 626 cm⁻¹. -1 This represents the stretching vibration of Mo-S.

[0065] Example 2

[0066] The steps for preparing molybdenum disulfide nanosheets modified melamine resin in this embodiment are as follows:

[0067] (1) Add 5g of sodium molybdate and 23.55g of potassium thiocyanate to 100mL of 30% isopropanol solution and stir for 10min; then pour the mixed solution into a hydrothermal reactor and react at 160℃ for 24 hours. Then wash with deionized water to obtain molybdenum disulfide nanosheets.

[0068] (2) The synthesized molybdenum disulfide nanosheets and urea were added into deionized water in a mass ratio of 1:4 and ultrasonicated at room temperature for 15 min; then, under the condition of 60°C and 500 rpm, stirring was performed for 10 hours. Then, the unreacted urea was removed by washing with deionized water, and the molybdenum disulfide nanosheets with surface-modified functional groups were obtained after drying at 60°C.

[0069] (3) 6 g of melamine and 16.67 g of urotropin were added into a four-necked flask, and the pH value was adjusted to 8.5 by using a 40% sodium hydroxide solution, and the reaction was performed at 85°C for 45 min; 6 g of melamine and 0.69 g of the molybdenum disulfide nanosheets with surface-modified functional groups were added into the reaction kettle, and the pH value was adjusted to 5 by using a 40% formic acid solution, and the reaction was performed until the system became viscous; the temperature was lowered to 50°C, and the pH value was adjusted to 8 by using a 40% sodium hydroxide solution, and then 3 g of urea was added again, and the reaction was performed for 15 min, and then the system was cooled to room temperature, to obtain the molybdenum disulfide nanosheet melamine resin.

[0070] (4) 1 g of the molybdenum disulfide nanosheet melamine resin was dissolved in acetone, 15 g of N-β-(aminoethyl)-γ-aminopropyl trimethoxysilane was added, and the reaction was performed at 95°C for 3 hours, and then the organic solvent was removed under reduced pressure, to obtain the molybdenum disulfide nanosheet modified melamine resin.

[0071] The SEM image of the molybdenum disulfide nanosheet modified melamine resin prepared in this example is shown in FIG. 1. Figure 3 As can be seen from FIG. 1, the molybdenum disulfide nanosheets are uniform, stable, and have clear boundaries, and present a complete sheet structure. Figure 3 The infrared spectrum of the molybdenum disulfide nanosheet modified urea-formaldehyde resin is shown in FIG. 2. Figure 8 As can be seen from FIG. 2, 3356 cm-1 is the stretching vibration peak of -OH; 2958 cm-1 is the CH stretching vibration of methyl; 1561 cm-1 is the coupling of the in-plane bending vibration of NH bond and the stretching vibration of part of C-N bond; 1444 cm-1 is the C-H bending vibration of methylene; 1393 cm-1 is the CH stretching vibration; 1202 is the characteristic absorption peak of Si-C; 1133 cm-1 is the C-O and C-N stretching vibration of the fatty ether bond in phthalamide II; 987 cm-1 is the deformation vibration of C-O on the hydroxymethyl; 812 cm-1 is the characteristic peak of triazine ring; and 626 cm-1 is the stretching vibration of Mo-S. -1 -1 -1 -1 -1 -1 -1 -1 -1

[0072] Example 3

[0073] ​​​​​​​​​The embodiment prepares a molybdenum disulfide nanosheet modified urea formaldehyde / melamine resin, and the steps are as follows:

[0074] (1) 5 g of molybdenum trioxide and 21.18 g of thioformamide were added to 100 mL of 30% isopropanol solution and stirred for 10 min; then the mixed solution was poured into a hydrothermal reaction kettle and reacted at 200°C for 24 hours. Then it was washed with deionized water to obtain molybdenum disulfide nanosheets.

[0075] (2) The synthesized molybdenum disulfide nanosheets were added to deionized water at a mass ratio of 1:5 with urea, and ultrasonic treatment was performed at room temperature for 10 min, then stirring was performed at 60°C and 1000 rpm for 10 hours. Then it was washed with deionized water to remove unreacted urea, and dried at 50°C to obtain molybdenum disulfide nanosheets with surface modified functional groups.

[0076] (3) 5 g of urea and 18.57 g of formaldehyde were added to a four-necked flask, and the pH value was adjusted to 9 with 40% sodium hydroxide solution, and reacted at 90°C for 45 min; 5 g of melamine and 1.119 g of molybdenum disulfide nanosheets with surface modified functional groups were added to the reaction kettle, and the pH value was adjusted to 4.5 with 40% formic acid solution, and the reaction was continued until the system became viscous; the temperature was lowered to 70°C, and the pH value was adjusted to 8 with 40% sodium hydroxide solution, then 5 g of urea was added again, and the reaction was continued for 20 min, and then cooled to room temperature to obtain a molybdenum disulfide nanosheet urea formaldehyde / melamine resin.

[0077] (4) 1 g of molybdenum disulfide nanosheet urea formaldehyde / melamine resin was dissolved in acetone, 10 g of γ-aminopropyl triethoxysilane was added, and the reaction was carried out at 95°C for 3 hours, then the organic solvent was removed under reduced pressure to obtain a molybdenum disulfide nanosheet modified urea formaldehyde / melamine resin.

[0078] Comparative Example 1

[0079] The comparative example prepares a modified urea formaldehyde resin, which is compared with Example 1, and the steps are as follows:

[0080] (1) 2 g of urea and 7.5 g of formaldehyde were added to a four-necked flask, and the pH value was adjusted to 9 with 40% sodium hydroxide solution, and reacted at 90°C for 30 min.

[0081] (2) 2 g of urea was added to the reaction kettle, and the pH value was adjusted to 4.5 with 40% formic acid solution, and the reaction was continued until the system became viscous.

[0082] (3) The temperature was lowered to 60°C, and the pH value was adjusted to 8 with 40% sodium hydroxide solution, then 1 g of urea was added again, and the reaction was continued for 15 min, and then cooled to room temperature to obtain a urea formaldehyde resin.

[0083] (4) The urea-formaldehyde resin was dissolved in acetone, 5 g of γ- aminopropyl triethoxysilane was added, and the mixture was reacted at 85°C for 5 hours. The organic solvent was removed under reduced pressure to obtain the modified urea-formaldehyde resin.

[0084] Comparative Example 2

[0085] This example prepared a modified melamine resin, which was compared with Example 2, and the steps were as follows:

[0086] (1) 6 g of melamine and 10.72 g of formaldehyde were added to a four-necked flask, and the pH value was adjusted to 8.5 with a 40% sodium hydroxide solution. The mixture was reacted at 85°C for 45 min.

[0087] (2) 6 g of melamine was added to the reaction kettle, and the pH value was adjusted to 5 with a 40% formic acid solution. The reaction was continued until the system became viscous.

[0088] (3) The temperature was lowered to 50°C, the pH value was adjusted to 8 with a 40% sodium hydroxide solution, and then 3 g of urea was added again. The mixture was reacted for 15 min and then cooled to room temperature to obtain the melamine resin.

[0089] (4) 1 g of the melamine resin was dissolved in acetone, 15 g of N-β- (aminoethyl) -γ-aminopropyl trimethoxysilane was added, and the mixture was reacted at 95°C for 3 hours. The organic solvent was removed under reduced pressure to obtain the modified melamine resin.

[0090] Comparative Example 3

[0091] This example prepared a modified urea-formaldehyde / melamine resin, and the steps were as follows:

[0092] (1) 5 g of urea and 18.57 g of formaldehyde were added to a four-necked flask, and the pH value was adjusted to 9 with a 40% sodium hydroxide solution. The mixture was reacted at 90°C for 45 min.

[0093] (2) 5 g of melamine was added to the reaction kettle, and the pH value was adjusted to 4.5 with a 40% formic acid solution. The reaction was continued until the system became viscous.

[0094] (3) The temperature was lowered to 70°C, the pH value was adjusted to 8 with a 40% sodium hydroxide solution, and then 5 g of urea was added again. The mixture was reacted for 20 min and then cooled to room temperature to obtain the urea-formaldehyde / melamine resin.

[0095] (4) 1 g of the urea-formaldehyde / melamine resin was dissolved in acetone, 10 g of γ-aminopropyl triethoxysilane was added, and the mixture was reacted at 95°C for 3 hours. The organic solvent was removed under reduced pressure to obtain the modified urea-formaldehyde / melamine resin.

[0096] Comparative Example 4

[0097] 3g of molybdenum trioxide powder and 3g of thiourea were added to 100mL of 30% isopropanol solution and stirred for 10min. The mixture was then poured into a hydrothermal reactor and reacted at 180℃ for 20 hours. The solution was then washed with deionized water to obtain molybdenum disulfide nanosheets, as shown in the SEM image below. Figure 4 As shown, from Figure 4 It can be seen that the method in this comparative example cannot obtain molybdenum disulfide nanosheets with suitable size and complete structure.

[0098] Test Example 1

[0099] The resins synthesized in Examples 1-3 and Comparative Examples 1-3 were subjected to permeability retention tests. The experimental method followed the Chinese petroleum and natural gas industry standard SY / T 6572-2003, "Performance Evaluation Method of Resins for Sand Control," and the steps were as follows:

[0100] (1) Core preparation before cementation: Quartz sand with a particle size of 0.4-0.8 mm is loaded into a stainless steel core tube, and a copper wire mesh is placed on the inside of the outlet end of the core tube. The sand sample is filled and compacted to a constant sand surface, then a small amount of water is added for saturation, and the other end is sealed with copper wire mesh.

[0101] (2) Preparation of cemented core: ① Weigh 150g of quartz sand into a 500mL beaker and soak it in 50mL of pretreatment solution for 20min. ② Weigh 6% of resin and mix it evenly with the quartz sand soaked in the pretreatment solution. ③ Pour the pre-cemented sand into a glass tube with a perforated rubber stopper at one end in three batches. A copper wire mesh is placed on the perforated rubber stopper. Vibrate vertically each time until the sand surface is constant. Then pour in 80mL of sewage to seal the rubber stopper hole. Place the tube in a constant temperature water bath and cure it at 60℃ for 48h. ④ Take out the core and prepare cores with lengths of 2.5cm and 13cm.

[0102] (3) Place the sample (including samples before and after cementation) into the core holder and adjust the ring pressure to 0.14–0.35 MPa. Then, pass a 2% KCl aqueous solution through the core to expel air. After the flow stabilizes, calculate the permeability of the sample before and after cementation. Calculate using the formula:

[0103]

[0104] Where: η is the permeability retention rate, %; K1 is the core permeability after consolidation, mD; K0 is the core permeability before consolidation, mD.

[0105] (4) Experimental data on permeability retention rates of Examples 1-3 and Comparative Examples 1-3 are shown in the figure below. Figure 5 As shown, by Figure 5It can be seen that the permeability retention rate of the molybdenum disulfide nanosheet-modified urea-formaldehyde / melamine resin prepared in Example 1 is 85%, that in Example 2 is 79%, and that in Example 3 is 81%, while that in Comparative Example 1 is 65%, that in Comparative Example 2 is 61%, and that in Comparative Example 3 is 56%. Without molybdenum disulfide nanosheets as the core-shell structure, the permeability retention rate is generally around 60%. After adding molybdenum disulfide nanosheets, the permeability retention rate is generally around 80%.

[0106] Test Example 2

[0107] The compressive strength of the resins synthesized in Examples 1-3 and Comparative Examples 1-3 was tested, and the steps were as follows:

[0108] (1) Preparation of cemented core according to the Chinese petroleum and natural gas industry standard SY / T 6572-2003, which evaluates the performance of resin for sand control: ① Weigh 150g of quartz sand into a 500mL beaker and soak it in 50mL of pretreatment solution for 20min. ② Weigh 6% of the resin and mix it evenly with the quartz sand soaked in the pretreatment solution. ③ Pour the pre-cemented sand into a glass tube with a perforated rubber stopper at one end in three batches. A copper wire mesh is placed on the perforated rubber stopper. Each time, the sand surface is vertically vibrated until it is constant. Then, 80mL of sewage is injected to seal the rubber stopper hole. The tube is placed in a constant temperature water bath and cured at 60℃ for 48h. ④ The core is taken out and cores with lengths of 2.5cm and 13cm are prepared.

[0109] (2) The compressive strength was tested in accordance with the Chinese petroleum and natural gas industry standard SY / T 5276-2000 for the determination of flexural strength, compressive strength and gas permeability of chemical sand control artificial rock core.

[0110] (3) The compressive strength test data of Examples 1-3 and Comparative Examples 1-3 are shown in the figure. Figure 6 As shown, by Figure 6 It can be seen that the compressive strength of the molybdenum disulfide nanosheet-modified urea-formaldehyde / melamine resin prepared in Example 1 is 9.5 MPa, that in Example 2 is 10 MPa, and that in Example 3 is 9.3 MPa, while that in Comparative Example 1 is 4 MPa, Comparative Example 2 is 4.5 MPa, and Comparative Example 3 is 4.3 MPa. The addition of molybdenum disulfide nanosheets significantly improves the compressive strength of the resin. The molybdenum disulfide nanosheet-modified urea-formaldehyde / melamine resin has higher compressive strength and better sand-fixing effect. In contrast, the strength of the comparative examples is very low, and they cannot effectively fix sand.

[0111] Although specific embodiments of the invention have been described in detail, those skilled in the art will understand that various modifications and substitutions can be made to those details based on all the teachings disclosed, and all such changes are within the scope of protection of this invention. The full scope of this invention is given by the appended claims and any equivalents thereof.

Claims

1. A method for preparing a molybdenum disulfide nanoplatelet-modified urea-formaldehyde / melamine resin, characterized by, Includes the following steps: (1) Molybdenum disulfide nanosheets were prepared by hydrothermal synthesis of sulfur source and molybdenum source; (2) The molybdenum disulfide nanosheets are modified with surface functional group modifiers; (3) The aldehydes, polyamine compounds and the molybdenum disulfide nanosheets modified with surface functional groups in step (2) are copolymerized to obtain molybdenum disulfide nanosheet urea-formaldehyde / melamine resin. (4) The molybdenum disulfide nanosheet urea-formaldehyde / melamine resin was modified with a silane coupling agent to obtain molybdenum disulfide nanosheet modified urea-formaldehyde / melamine resin. In step (2), the surface functional group modifier is urea; Step (3) specifically includes the following steps: (301) Add the aldehydes and the first batch of polyamine compounds into a four-necked flask, adjust the pH of the solution to 8~9.5 with 40% sodium hydroxide solution, and react at 80~90℃ for 20~45 min; (302) Add a second batch of compounds containing polyamine groups and molybdenum disulfide nanosheets with the surface-modified functional groups, and adjust the pH value to 4.5~5.5 with 40% formic acid solution, and react at 80~90℃ until the system becomes viscous; (303) Reduce the reaction temperature to 50~70℃, adjust the pH of the solution to 7.0~8.5 with 40% sodium hydroxide solution, add the third batch of polyamine-containing compounds, react for 15~30 min and then cool to room temperature to obtain molybdenum disulfide nanosheet urea-formaldehyde / melamine resin.

2. The method of claim 1, wherein, Step (1) specifically includes: A molybdenum source and a sulfur source with a molar ratio of 1:5 to 1:15 were added to a 30% isopropanol aqueous solution and stirred for 10-20 minutes. The mixed solution was then subjected to a hydrothermal reaction at 160-200℃ for 12-24 hours. The product after the hydrothermal reaction was completed was washed with deionized water to obtain molybdenum disulfide nanosheets.

3. The method of claim 2, wherein, The molybdenum source includes one or more of molybdenum trioxide, molybdenum pentachloride, and sodium molybdate.

4. The method of claim 3, wherein, The molybdenum source is molybdenum trioxide.

5. The method of claim 2, wherein, The sulfur source includes one or more of thiourea, potassium thiocyanate, potassium sulfide, and thioformamide.

6. The method of claim 2, wherein, The hydrothermal reaction was carried out at a temperature of 180°C for 20 hours.

7. The method of claim 1, wherein, Step (2) specifically includes: Molybdenum disulfide nanosheets and surface functional group modifiers were added to deionized water, stirred and reacted, and then the product was washed with deionized water to remove unreacted surface functional group modifiers. After drying, molybdenum disulfide nanosheets with surface-modified functional groups were obtained.

8. The method of claim 7, wherein, The size of the molybdenum disulfide nanosheets is 100~500 nm.

9. The method of claim 8, wherein, The size of the molybdenum disulfide nanosheets is 100~200 nm.

10. The method of claim 7, wherein, The mass ratio of the molybdenum disulfide nanosheets to the surface functional group modifier is 1:1 to 1:

10.

11. The method of claim 10, wherein, The mass ratio of the molybdenum disulfide nanosheets to the surface functional group modifier is 1:

1.

12. The method of claim 7, wherein, The stirring reaction refers to: first, sonicating at room temperature for 5-15 minutes; then, stirring at 60°C for 6-12 hours.

13. The method of claim 12, wherein, The stirring reaction refers to: first, sonicating at room temperature for 10 minutes; then stirring at 60°C for 10 hours.

14. The method of claim 12, wherein, The ultrasonic power is 10~25 Hz; the stirring speed is 500~1500 rpm.

15. The method of claim 14, wherein, The ultrasonic power is 19.2 Hz; the stirring speed is 1000 rpm.

16. The method of claim 7, wherein, The drying temperature is 50~90℃.

17. The method of claim 16, wherein, The drying temperature is 50°C.

18. The method of claim 1, wherein, The molar ratio of the polyamine-containing compound to the aldehyde is 1:1 to 1:

3.

19. The method of claim 1, wherein, The mass ratio of the aldehydes and polyamine-containing compounds to the molybdenum disulfide nanosheets with surface-modified functional groups is 200:1 to 10:

1.

20. The method of claim 19, wherein, The mass ratio of the aldehydes and polyamine-containing compounds to the molybdenum disulfide nanosheets with surface-modified functional groups is 100:1 to 50:

1.

21. The method of claim 1, wherein, The aldehydes are selected from one or a combination of two of formaldehyde, hexamethylenetetramine, and paraformaldehyde.

22. The method of claim 1, wherein, The polyamine-containing compound is selected from one or a combination of two of urea and melamine.

23. The method as described in claim 1, characterized in that, The first batch of polyamine-containing compounds accounts for 30-50% of the total mass; the second batch of polyamine-containing compounds accounts for 30-40% of the total mass; and the third batch of polyamine-containing compounds accounts for 10-40% of the total mass.

24. The method as described in claim 1, characterized in that, Step (4) specifically includes the following steps: Molybdenum disulfide nanosheets modified urea-formaldehyde / melamine resin were dissolved in acetone, and then a silane coupling agent was added. The mixture was reacted at 80-95°C for 3-5 hours, and then the organic solvent was removed under reduced pressure to obtain the molybdenum disulfide nanosheets modified urea-formaldehyde / melamine resin.

25. The method as described in claim 24, characterized in that, The mass ratio of the molybdenum disulfide nanosheet urea-formaldehyde / melamine resin to the silane coupling agent is 1:5 to 1:

30.

26. The method as described in claim 25, characterized in that, The mass ratio of the molybdenum disulfide nanosheet urea-formaldehyde / melamine resin to the silane coupling agent is 1:10 to 1:

15.

27. The method as described in claim 24, characterized in that, The silane coupling agent is selected from one or more of γ-diethylenetriaminepropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane.

28. Molybdenum disulfide nanosheet modified urea-formaldehyde / melamine resin prepared by the method according to any one of claims 1 to 27.

29. The application of the molybdenum disulfide nanosheet modified urea-formaldehyde / melamine resin according to claim 28 in oilfield sand control.

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