Preparation and application of amphiphilic tungsten disulfide nano material

Abstract

The invention relates to the technical field of materials, in particular to preparation of an amphiphilic tungsten disulfide nano material and application of the amphiphilic tungsten disulfide nano material in preparation of an oil displacement agent. The oil-displacing agent prepared from the amphiphilic tungsten disulfide nano material can reduce the interfacial tension of an oil-water interface, and can be quickly adsorbed to the oil-water interface to layer oil and water; the surface wettability of the rock is changed, the lipophilicity of the rock is changed into weak hydrophilicity, and the pore throat cannot be blocked due to excessive hydrophilicity while the oil phase is stripped. The nano oil-displacing agent disclosed by the invention can still have an enough stable use effect after being frozen at a low temperature and then unfrozen.

Description

Technical Field

[0001] This invention relates to the field of materials technology, specifically to the preparation and application of amphiphilic tungsten disulfide nanomaterials. Background Technology

[0002] With the continuous growth of energy demand, the extraction of oil and gas resources is becoming increasingly difficult, especially the proportion of low-permeability reservoirs and complex oil and gas reservoirs that are difficult to extract. The limitations of traditional chemical flooding agents (such as polymers, surfactants, and alkaline flooding agents) are becoming increasingly apparent. Nano-flooding agents, due to their synergistic mechanism, including wettability reversal, interfacial tension reduction, and structural lubrication effect, are becoming a new development trend.

[0003] Existing molybdenum disulfide nano-displacement agents are not very effective in cold regions after being frozen and then re-dissolved. Furthermore, the preparation of molybdenum disulfide nanosheets releases hydrogen sulfide gas, which is harmful to the environment and human health.

[0004] Chinese patent document CN117050738A discloses the application of tungsten disulfide nanomaterials as an oil displacement agent in oil recovery. Chinese patent document CN118146781A discloses an amino acid-based amphoteric / anionic surfactant oil displacement system, its preparation method, and its application. Chinese patent document CN113292981A discloses a temperature-resistant and salt-resistant heterogeneous nanocomposite oil displacement system, its preparation method, and its application. Chinese patent document CN116952774A discloses a screening method for polymer oil displacement systems suitable for medium-permeability oil reservoirs. However, the preparation and application of an amphiphilic tungsten disulfide nanomaterial have not yet been reported. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a tungsten disulfide nanomaterial that reduces environmental pollution. This nanomaterial is then modified to possess amphiphilic properties, enabling its application as a nano-displacement agent in oil recovery. By modifying the tungsten disulfide nanomaterial with a surfactant to achieve amphiphilicity, the prepared nano-displacement agent maintains sufficient stability even after cryogenic freezing and thawing.

[0006] In a first aspect, the present invention provides an amphiphilic tungsten disulfide nanomaterial, the preparation method of which includes the following steps:

[0007] (A) Preparation of hydrophilic tungsten disulfide nanomaterials: tungsten source, sulfur source, and reducing agent were reacted by hydrothermal reaction at 160°C-240°C for 12-48 hours in a molar ratio of 1:2:2-1:10:10.

[0008] The hydrophilic tungsten disulfide nanomaterial is a 1T-type hydrophilic nanomaterial. It is a two-dimensional sheet-like nanomaterial with an interlayer spacing of 0.5 nm-2 nm and a width of 50 nm-500 nm.

[0009] (B) Preparation of amphiphilic tungsten disulfide nanomaterials: The surfactant and the hydrophilic tungsten disulfide nanomaterials from step (A) are reacted at 20°C-60°C for 12-20 hours in a molar ratio of 1:1-10:1.

[0010] Furthermore, the tungsten source is a type of tungstate, wherein the cation is one of cobalt, iron, zinc, ammonium, lead, copper, or aluminum, and the tungstate ion is [WO4]. 2- [W4O] 16 ] 8- [W5O] 16 ] 2- [W6O] 19 ] 2- [W7O] 24 ] 6- [W] 10 O 32 ] 4- [W] 12 O 40 ] 8- [W] 12 O 42 ] 12- One of them. Furthermore, the tungsten source is ammonium paratungstate.

[0011] Furthermore, the sulfur source is one of thioacetamide, thiourea, sodium sulfide, elemental sulfur, L-cysteine, sodium thiosulfate, sodium thiocyanate, and sodium sulfonate. Even more specifically, the sulfur source is thiourea.

[0012] Furthermore, the reducing agent is one of ascorbic acid, hydrazine hydrate, oxalic acid dihydrate, glucose, thioacetamide, citric acid, sodium borohydride, formic acid, and hydroxylamine. Even more specifically, the reducing agent is oxalic acid dihydrate.

[0013] Further, the surfactant is one of the following: a mercaptosilane coupling agent (e.g., γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, 3-mercaptopropyltriethoxysilane, etc.), a polyetheramine (e.g., polyoxypropylene diamine, aliphatic polyether diamine, etc.), an alkylamine (e.g., dodecylamine, hexadecylamine, octadecylamine, etc.), a perfluorooctyl sulfonate, rhamnolipid, or sulfobetaine. Even further, the surfactant is octadecylamine.

[0014] Furthermore, the reaction solvent in steps (A) and (B) is one or more of deionized water, tetrahydrofuran, N,N-dimethylformamide, and anhydrous ethanol.

[0015] A second aspect of the present invention provides a method for preparing amphiphilic tungsten disulfide nanomaterials, comprising the following steps:

[0016] S1. Dissolve the tungsten source, sulfur source, and reducing agent in deionized water;

[0017] S2. Pour the above solution into a hydrothermal reactor and react it in an oven at 220°C for 24 hours to obtain a solution with a black precipitate;

[0018] S3. After the reaction is complete, remove the hydrothermal reactor and cool it to room temperature. Wash the precipitate with deionized water and anhydrous ethanol alternately, and then freeze-dry it at -50°C for 24 hours to obtain a black powder, namely hydrophilic tungsten disulfide nanomaterials.

[0019] S4. The black powder obtained above, surfactant, and anhydrous ethanol are mixed, and hydrochloric acid is added to adjust the pH to about 2. The mixture is stirred at 450 rpm at 30°C for 16 h. After stirring, the precipitate is washed alternately with deionized water and anhydrous ethanol, and then freeze-dried at -50°C for 24 h to obtain the black powder, i.e., amphiphilic tungsten disulfide nanomaterial.

[0020] In a preferred embodiment of the present invention, the method for preparing the amphiphilic tungsten disulfide nanomaterial includes the following steps:

[0021] S1. Dissolve ammonium paratungstate, thiourea, and oxalic acid dihydrate in deionized water;

[0022] S2. Pour the above solution into a hydrothermal reactor and react it in an oven at 220°C for 24 hours to obtain a solution with a black precipitate;

[0023] S3. After the reaction is complete, remove the hydrothermal reactor and cool it to room temperature. Wash the precipitate with deionized water and anhydrous ethanol alternately, and then freeze-dry it at -50°C for 24 hours to obtain a black powder, namely 1T type hydrophilic tungsten disulfide nanomaterial.

[0024] S4. Mix the black powder obtained above, octadecylamine, and anhydrous ethanol, add hydrochloric acid to adjust the pH to about 2, and stir at 450 rpm for 16 h at 30°C. After stirring, wash the precipitate alternately with deionized water and anhydrous ethanol, and then freeze-dry at -50°C for 24 h to obtain the black powder, i.e., amphiphilic tungsten disulfide nanomaterial.

[0025] A third aspect of the present invention provides the application of the amphiphilic tungsten disulfide nanomaterials described above in the preparation of oil displacement agents.

[0026] In a fourth aspect, the present invention provides a nano-oil displacement agent, which is obtained by ultrasonically dispersing a mixture of the above-described amphiphilic tungsten disulfide nanomaterials, a dialysis agent, and a solvent in a mass ratio of 1:5:1000-1:15:50000.

[0027] The dialysis agent is one or more of the following: fatty alcohol polyoxyethylene ether (e.g., AEO-5, AEO-7, MOA4), methanol, ethanol, deionized water, phosphate (e.g., sodium phosphate, potassium phosphate), sulfate (e.g., sodium sulfate, potassium sulfate), sulfonate (e.g., sodium dodecylbenzenesulfonate, sodium naphthalenesulfonate, sodium perfluorononenoxybenzenesulfonate), and hexamethyldisiloxane;

[0028] The solvent is one or more of deionized water, tetrahydrofuran, N,N-dimethylformamide, and anhydrous ethanol.

[0029] The advantages of this invention are:

[0030] 1. The amphiphilic tungsten disulfide nanomaterials of the present invention have small sheet diameter and thin thickness, making them more suitable for low-permeability reservoirs with small pore size, thereby improving oil recovery.

[0031] 2. The amphiphilic tungsten disulfide nanomaterials of the present invention generate less hydrogen sulfide gas during the synthesis process, resulting in less environmental pollution.

[0032] 3. The surface sulfur vacancy density of molybdenum disulfide nanosheets is 3 × 10⁻⁶. 13 cm -2 The surface sulfur vacancy density of tungsten disulfide is 5 × 10⁻⁶. 13 cm -2 It is significantly higher than that of molybdenum disulfide, so it can graft more surfactants during surfactant modification, thereby improving the effect of the modification.

[0033] 4. The coefficient of thermal expansion of molybdenum disulfide nanosheets is 8.3 × 10⁻⁶. -6 K -1 The coefficient of thermal expansion of tungsten disulfide is 4.5 × 10⁻⁶. -6 K -1 Therefore, tungsten disulfide is better able to maintain structural stability after being frozen and thawed at low temperatures.

[0034] 5. The amphiphilic tungsten disulfide nanomaterial of the present invention has the following effects: the prepared oil displacement agent working fluid can reduce the interfacial tension of the oil-water interface, and at the same time quickly adsorb to the oil-water interface to separate oil and water into layers; it changes the wettability of the rock surface, changing its oleophilicity to weak hydrophilicity, and will not block the pore throat due to excessive hydrophilicity while stripping the oil phase.

[0035] 6. The amphiphilic tungsten disulfide nanosheets of this invention exhibit good dispersibility, and the agglomeration problem is improved after surfactant modification. Therefore, the mass concentration used in the oil displacement agent is 0.005%-0.05%. In comparison, the surfactant compound system used in Chinese patent document CN118146781A has a mass concentration of 0.3%; the nanocomposite oil displacement agent used in Chinese patent document CN113292981A has a mass concentration of 0.2%-0.3%; and the polymer system used in Chinese patent document CN116952774A for oil displacement has a polymer concentration range of 500-2500 mg / L. Attached Figure Description

[0036] Figure 1 , 2 This is an SEM image of the hydrophilic tungsten disulfide from Example 1.

[0037] Figure 3 This is a Raman image of the hydrophilic tungsten disulfide in Example 1.

[0038] Figure 4 These are infrared test images of tungsten disulfide before and after modification in Example 1.

[0039] Figure 5 , 6 This is an image of the interfacial adsorption test of the nano-oil displacement agent working fluid in Example 2.

[0040] Figure 7 This is an image of the wettability flipping test of the nano-oil displacement agent working fluid in Example 2. Detailed Implementation

[0041] The specific implementation methods provided by the present invention will be described in detail below with reference to the embodiments.

[0042] Example 1:

[0043] The amphiphilic tungsten disulfide nanomaterials are made from the raw materials shown in Table 1:

[0044] Table 1

[0045]

[0046] The preparation method of the aforementioned amphiphilic tungsten disulfide nanomaterial includes the following steps:

[0047] S1. Dissolve ammonium paratungstate, thiourea, and oxalic acid dihydrate in deionized water.

[0048] S2. Pour the above solution into a hydrothermal reactor and react it in an oven at 220°C for 24 hours to obtain a solution with a black precipitate.

[0049] S3. After the reaction is complete, remove the hydrothermal reactor and cool it to room temperature. Wash the precipitate with deionized water and anhydrous ethanol alternately, and then freeze-dry it at -50°C for 24 hours to obtain a black powder, namely 1T type tungsten disulfide nanosheets.

[0050] S4. The black powder obtained above, octadecylamine, and anhydrous ethanol were mixed, and hydrochloric acid was added to adjust the pH to approximately 2. The mixture was stirred at 30°C and 450 rpm for 16 h. After stirring, the precipitate was washed alternately with deionized water and anhydrous ethanol, and then freeze-dried at -50°C for 24 h to obtain the black powder, i.e., amphiphilic tungsten disulfide nanosheets.

[0051] Example 2:

[0052] The amphiphilic tungsten disulfide nano-displacement agent is prepared from the dialysis agent raw materials shown in Table 2, the amphiphilic tungsten disulfide nanosheets obtained in Example 1, and a solvent:

[0053] Table 2

[0054]

[0055] The preparation method of the amphiphilic tungsten disulfide nano-oil displacement agent is as follows: the amphiphilic tungsten disulfide nanosheets obtained in Example 1 are mixed with the dialysis agent (raw material composition is shown in Table 2) and the solvent (deionized water) in a mass ratio of 1:5:10000 and then ultrasonically dispersed for 10 min.

[0056] Example 3: Performance Testing Experiment

[0057] 1. The 1T-type tungsten disulfide nanosheets prepared in Example 1 were observed under an electron microscope, and the results are as follows: Figure 1 and Figure 2 As shown, tungsten disulfide nanosheets have a flexible structure, thus they can be effectively adsorbed at the oil-water interface and stabilize the emulsion.

[0058] 2. Raman spectroscopy was performed on the tungsten disulfide nanosheets prepared in Example 1, and the results are as follows: Figure 3 As shown, 126.7cm -1 and 258.2cm -1 The appearance of the peak indicates that it is of the 1T type.

[0059] 3. Infrared spectroscopy was performed on the tungsten disulfide nanosheets prepared in Example 1 before and after modification. The results are as follows: Figure 4 As shown, the image of unmodified tungsten disulfide nanosheets is at 541.2 cm⁻¹. -1 and 457cm -1 The peak appearing at 3121.9 cm⁻¹ corresponds to the vibrational mode of the WS bond, and no obvious peaks appear in other regions; the modified tungsten disulfide nanosheets show a peak at 3121.9 cm⁻¹. -1and 1402.3cm -1 The peak appearing at 1595.2 cm⁻¹ corresponds to the vibrational mode of the CH bond. -1 The peak appearing at this point corresponds to the vibrational mode of the NH bond. This indicates that the grafting of octadecylamine was successful.

[0060] 4. The interfacial adsorption test was performed on the amphiphilic tungsten disulfide nano-oil displacement agent prepared in Example 2, and the results are as follows: Figure 5 As shown, when the oil displacement agent and kerosene are mixed in a 7:3 ratio and shaken, the nanofluid is rapidly adsorbed at the oil-water interface. After freezing the oil displacement agent at -20°C for 48 hours and thawing it, it is mixed with kerosene again in a 7:3 ratio, and the results are as follows. Figure 6 As shown, it still has a good adsorption effect.

[0061] 5. Simulated rock wettability alteration experiment: Three quartz plates were treated with silicone oil for 24 hours. One plate was left untreated, while the other two were treated for 24 hours each with the amphiphilic tungsten disulfide nano-displacing agent prepared in Example 2 and the displacing agent that had undergone freeze-thaw cycles (frozen at -20°C for 48 hours and then thawed). After drying, contact angle tests were performed, and the results are as follows: Figure 7 As shown, the surface of the quartz sheet without oil displacement agent is oleophilic, but after treatment, it can remain weakly hydrophilic, thus avoiding pore and throat blockage due to excessive hydrophilicity while stripping the oil phase.

[0062] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A tungsten disulfide amphiphilic nanomaterial, characterized in that, Its preparation method includes the following steps: (A) Preparation of hydrophilic tungsten disulfide nanomaterials: tungsten source, sulfur source, and reducing agent were reacted by hydrothermal reaction at 160°C-240°C for 12-48 hours in a molar ratio of 1:2:2-1:10:

10. (B) Preparation of amphiphilic tungsten disulfide nanomaterials: The surfactant and the hydrophilic tungsten disulfide nanomaterials from step (A) are reacted at 20°C-60°C for 12-20 hours in a molar ratio of 1:1-10:

1. The tungsten source is a type of tungstate, wherein the cation is one of cobalt, iron, zinc, ammonium, lead, copper, or aluminum, and the tungstate ion is [WO4]. 2- [W4O] 16 ] 8- [W5O] 16 ] 2- [W6O] 19 ] 2- [W7O] 24 ] 6- [W] 10 O 32 ] 4- [W] 12 O 40 ] 8- [W] 12 O 42 ] 12- One of them; The sulfur source is one of the following: thioacetamide, thiourea, sodium sulfide, elemental sulfur, L-cysteine, sodium thiosulfate, sodium thiocyanate, and sodium sulfonate. The reducing agent is one of the following: ascorbic acid, hydrazine hydrate, oxalic acid dihydrate, glucose, thioacetamide, citric acid, sodium borohydride, formic acid, and hydroxylamine. The surfactant is one of the following: mercaptosilane coupling agent, polyetheramine, alkylamine, perfluorooctyl sulfonate, rhamnolipid, and sulfobetaine.

2. The amphiphilic tungsten disulfide nanomaterial according to claim 1, characterized in that, The reaction solvent in steps (A) and (B) is one or more of deionized water, tetrahydrofuran, N,N-dimethylformamide, and anhydrous ethanol.

3. A method for preparing amphiphilic tungsten disulfide nanomaterials as described in claim 1 or 2, characterized in that, Includes the following steps: S1. Dissolve the tungsten source, sulfur source, and reducing agent in deionized water; S2. Pour the above solution into a hydrothermal reactor and react it in an oven at 220°C for 24 hours to obtain a solution with a black precipitate; S3. After the reaction is complete, remove the hydrothermal reactor and cool it to room temperature. Wash the precipitate with deionized water and anhydrous ethanol alternately, and then freeze-dry it at -50°C for 24 hours to obtain a black powder, namely hydrophilic tungsten disulfide nanomaterials. S4. The black powder obtained above, surfactant, and anhydrous ethanol are mixed, and hydrochloric acid is added to adjust the pH to about 2. The mixture is stirred at 450 rpm at 30°C for 16 h. After stirring, the precipitate is washed alternately with deionized water and anhydrous ethanol, and then freeze-dried at -50°C for 24 h to obtain the black powder, i.e., amphiphilic tungsten disulfide nanomaterial.

4. The application of the amphiphilic tungsten disulfide nanomaterial as described in claim 1 or 2 in the preparation of oil displacement agents.

5. A nano-oil displacement agent, obtained by ultrasonic dispersion of the amphiphilic tungsten disulfide nanomaterial as described in claim 1 or 2, a dialysis agent, and a solvent in a mass ratio of 1:5:1000-1:15:50000; The dialysis agent is one or more of the following: fatty alcohol polyoxyethylene ether, methanol, ethanol, deionized water, phosphate, sulfate, sulfonate, and hexamethyldisiloxane; The solvent is one or more of deionized water, tetrahydrofuran, N,N-dimethylformamide, and anhydrous ethanol.

6. The application of the amphiphilic tungsten disulfide nanomaterial as described in claim 1 or 2 in oil extraction.

7. The application of the nano-displacement agent as described in claim 5 in oil extraction.

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