Molybdenum-based nano surfactant for composite flooding and preparation method thereof

Abstract

The application relates to the technical field of petroleum additives, and is a molybdenum-based nano surfactant for composite oil displacement and a preparation method thereof.The molybdenum-based nano surfactant for composite oil displacement is obtained by the following method: mixing deionized water, nano molybdenum disulfide, acrylamide, 3-methyl acryloyloxy-2-hydroxypropyl sodium sulfonate, allyl phenyl sulfone, 1-vinyl-3-ethyl imidazole bromide salt, allyl alcohol polyoxyethylene ether, sorbitan monostearate and buffer salt to obtain a mixed solution, and then adding an initiator into the mixed solution to react and obtain the molybdenum-based nano surfactant for composite oil displacement.The molybdenum-based nano surfactant for composite oil displacement not only has ultralow surface tension and interfacial tension, but also has high viscosity reduction effect.In addition, the molybdenum-based nano surfactant for composite oil displacement is synthesized by using a one-pot method, raw materials are easy to obtain, the synthesis process is simple, there is no byproduct, and the synthesis is safe and environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of petroleum additive technology, specifically to a composite molybdenum-based nanosurfactant for oil displacement and its preparation method. Background Technology

[0002] Currently, most oil reservoirs have entered the late stage of high water-cut development. The proportion of oil reservoirs that are difficult to exploit, such as those with high temperature and high salinity, high water cut and high production, and low permeability, is increasing year by year. It is very difficult to develop them using secondary oil recovery methods. Therefore, it is urgent to develop new extraction technologies to significantly improve the recovery rate of old oilfields and the utilization rate of proven resources.

[0003] In recent years, research on nano-chemical enhanced oil recovery (EOR) technology has attracted considerable attention. Nano-displacement agents represent a significant breakthrough in the application of nanotechnology in oilfields, and have demonstrated good results and gained acceptance in low-permeability reservoirs, gradually becoming a new direction for enhanced oil recovery (EOR) technology development. Synthesized from nanomaterials through complex reactions, these agents use aqueous solutions as the transport medium, forming small particles ranging from several to hundreds of nanometers in water. These particles exhibit good interfacial activity, reversing rock wettability, reducing capillary resistance and injection pressure, and facilitating the removal of crude oil by the displacing fluid, thereby improving oil and gas recovery. Simultaneously, the nano-displacement agent has a temporary blocking effect on the micropores of the formation rock, expanding the swept volume and thus significantly enhancing the recovery rate.

[0004] However, further in-depth research on nanomaterials and their mechanisms of action is still needed to further explore the organic integration points between nanomaterials and chemical flooding, ultimately achieving the goal of significantly improving oil recovery. Existing oil displacement agents, such as the nano-type oil displacement agent disclosed in Chinese patent document CN101210174B, can be used synergistically or co-injected with high-temperature fluids to microcrystallize asphaltenes, gums, and wax crystal structures, effectively solving the problem of oil reservoir emulsification and blockage. However, its application is mainly in the field of thermal oil recovery.

[0005] For example, Chinese patent document CN116254100A discloses a composite surfactant and its preparation method. The surfactant prepared by this method has advantages such as good compatibility, good salt resistance, especially good resistance to calcium and magnesium ions, and high interfacial activity. It can achieve ultra-low interfacial tension under alkali-free and high-mineralization conditions. However, its sulfonating agent is selected from at least one of concentrated sulfuric acid, fuming sulfuric acid, and sulfur trioxide, resulting in certain hazards in the preparation process and failing to meet green and environmental protection requirements. In summary, currently available oil displacement agents have poor viscosity-reducing effects, complex synthesis processes, and do not meet green and environmental protection requirements. Summary of the Invention

[0006] This invention provides a molybdenum-based nanosurfactant for composite oil displacement and its preparation method, which overcomes the shortcomings of the prior art and can effectively solve the problems of poor viscosity reduction effect, complex synthesis and non-compliance with green and environmental protection requirements of existing oil displacement agents.

[0007] One of the technical solutions of this invention is achieved through the following measures: a composite molybdenum-based nano-surfactant for oil displacement, the raw materials of which include acrylamide, sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, allyl phenyl sulfone, 1-vinyl-3-ethylimidazolium bromide, allyl alcohol polyoxyethylene, nano-molybdenum disulfide and an initiator; wherein, the molar ratio of acrylamide, sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, allyl phenyl sulfone, 1-vinyl-3-ethylimidazolium bromide and allyl alcohol polyoxyethylene ether is 1:(0.1 to 0.3):(0.2 to 0.6):(0.1 to 0.3):(0.05 to 0.2); the weight ratio of nano-molybdenum disulfide, initiator and acrylamide is (0.1 to 0.3):(0.1 to 0.2):1.

[0008] The following are further optimizations and / or improvements to one of the above-mentioned inventive technical solutions:

[0009] The aforementioned initiator is one of a redox agent and an azo compound.

[0010] The above-mentioned redox agent is composed of persulfate and sulfite in a weight ratio of (1.5 to 3.0):1. The persulfate is one of potassium persulfate, sodium persulfate and ammonium persulfate, and the sulfite is sodium sulfite or potassium sulfite.

[0011] The aforementioned azo compounds are azobisisobutyronitrile or azobisisoheptanenitrile.

[0012] The above-mentioned raw materials also include deionized water, dehydrated sorbitan monooctadecyl ester and buffer salt, and the weight ratio of deionized water, dehydrated sorbitan monooctadecyl ester, buffer salt and acrylamide is (8 to 10): (0.05 to 0.2): (0.05 to 0.2): 1.

[0013] The buffer salt mentioned above is one of sodium dihydrogen phosphate, potassium dihydrogen phosphate, ammonium dihydrogen phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, and diammonium hydrogen phosphate.

[0014] The buffer salt mentioned above is one of sodium dihydrogen phosphate, potassium dihydrogen phosphate, and ammonium dihydrogen phosphate.

[0015] The above-mentioned composite oil displacement molybdenum-based nanosurfactant was obtained by the following method:

[0016] First, under a nitrogen atmosphere, the required amount of deionized water and nano-molybdenum disulfide were added to the reactor and stirred under programmed stirring. Then, the required amounts of acrylamide, sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, allyl sulfone, 1-vinyl-3-ethylimidazolium bromide, allyl alcohol polyoxyethylene ether, dehydrated sorbitan monooctadecyl ester and buffer salt were added to the reactor and stirred until homogeneous. After adjusting the pH value, a mixed solution was obtained.

[0017] The second step involves adding an initiator solution to a reactor containing the mixed solution and stirring the reaction. Then, the pH value is adjusted to obtain a composite molybdenum-based nano-surfactant for oil displacement.

[0018] In the first step above, the stirring program first stirs at a speed of 1200 rpm to 1500 rpm for 5 to 10 minutes, and then stirs at a speed of 200 rpm to 300 rpm.

[0019] In the first step above, the pH of the mixed solution is adjusted to 7 to 8 using sodium hydroxide solution.

[0020] In the second step above, the pH value of the high-viscosity polymer is adjusted to 7 to 8 using ammonia water with a mass concentration of 10% to 15%.

[0021] The second technical solution of the present invention is achieved through the following measures: a method for preparing a molybdenum-based nano-surfactant for composite oil displacement, which is carried out according to the following method:

[0022] First, under a nitrogen atmosphere, the required amount of deionized water and nano-molybdenum disulfide were added to the reactor and stirred under programmed stirring. Then, the required amounts of acrylamide, sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, allyl sulfone, 1-vinyl-3-ethylimidazolium bromide, allyl alcohol polyoxyethylene ether, dehydrated sorbitan monooctadecyl ester and buffer salt were added to the reactor and stirred until homogeneous. After adjusting the pH value, a mixed solution was obtained.

[0023] The second step involves adding an initiator solution to a reactor containing the mixed solution and stirring the reaction. Then, the pH value is adjusted to obtain a composite molybdenum-based nano-surfactant for oil displacement.

[0024] The molybdenum-based nanosurfactant for composite oil displacement of this invention not only possesses ultra-low surface tension and interfacial tension, but also achieves a surface tension of 26 mN / m and an interfacial tension of 10 mN / m at a concentration of 500 mg / L. -4Below mN / m, it also has a high viscosity reduction effect, with a viscosity reduction rate of over 98% at a concentration of 2000 mg / L. In addition, the synthesis of the molybdenum-based nano surfactant for composite oil displacement in this invention adopts a one-pot method, the raw materials are readily available, the synthesis process is simple, there are no by-products, and it is safe and environmentally friendly. It effectively solves the problems of poor viscosity reduction effect, complex synthesis and non-compliance with green and environmental protection requirements of existing oil displacement agents. Detailed Implementation

[0025] This invention is not limited to the following embodiments, and specific implementation methods can be determined according to the technical solutions and actual conditions of this invention. Unless otherwise specified, all chemical reagents and chemicals mentioned in this invention are well-known and commonly used chemical reagents and chemicals in the prior art; unless otherwise specified, all percentages in this invention are mass percentages; unless otherwise specified, all solutions in this invention are aqueous solutions with water as the solvent, for example, hydrochloric acid solution is an aqueous solution of hydrochloric acid; room temperature in this invention generally refers to a temperature between 15°C and 25°C, generally defined as 25°C.

[0026] The present invention will be further described below with reference to embodiments:

[0027] Example 1: The composite oil displacement molybdenum-based nano surfactant comprises acrylamide, sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, allyl phenyl sulfone, 1-vinyl-3-ethylimidazolium bromide, allyl alcohol polyoxyethylene, nano molybdenum disulfide, and an initiator; wherein the molar ratio of acrylamide, sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, allyl phenyl sulfone, 1-vinyl-3-ethylimidazolium bromide, and allyl alcohol polyoxyethylene ether is 1:(0.1 to 0.3):(0.2 to 0.6):(0.1 to 0.3):(0.05 to 0.2); and the weight ratio of nano molybdenum disulfide, initiator, and acrylamide is (0.1 to 0.3):(0.1 to 0.2):1.

[0028] Example 2: As an optimization of the above example, the initiator is one of a redox agent and an azo compound.

[0029] Example 3: As an optimization of the above example, the redox agent is composed of persulfate and sulfite in a weight ratio of (1.5 to 3.0):1, wherein the persulfate is one of potassium persulfate, sodium persulfate and ammonium persulfate, and the sulfite is sodium sulfite or potassium sulfite.

[0030] Example 4: As an optimization of the above examples, the azo compound is azobisisobutyronitrile or azobisisoheptanenitrile.

[0031] Example 5: As an optimization of the above example, the raw materials also include deionized water, dehydrated sorbitan monooctadecyl ester and buffer salt, and the weight ratio of deionized water, dehydrated sorbitan monooctadecyl ester, buffer salt and acrylamide is (8 to 10): (0.05 to 0.2): (0.05 to 0.2): 1.

[0032] Example 6: As an optimization of the above examples, the buffer salt is one of sodium dihydrogen phosphate, potassium dihydrogen phosphate, ammonium dihydrogen phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, and diammonium hydrogen phosphate.

[0033] Example 7: As an optimization of the above examples, the buffer salt is one of sodium dihydrogen phosphate, potassium dihydrogen phosphate, and ammonium dihydrogen phosphate.

[0034] Example 8: As an optimization of the above examples, a molybdenum-based nanosurfactant for composite oil displacement was obtained by the following method:

[0035] First, under a nitrogen atmosphere, the required amount of deionized water and nano-molybdenum disulfide were added to the reactor and stirred under programmed stirring. Then, the required amounts of acrylamide, sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, allyl sulfone, 1-vinyl-3-ethylimidazolium bromide, allyl alcohol polyoxyethylene ether, dehydrated sorbitan monooctadecyl ester and buffer salt were added to the reactor and stirred until homogeneous. After adjusting the pH value, a mixed solution was obtained.

[0036] The second step involves preparing an initiator solution with a mass concentration of 10% to 20% using a solvent. The initiator solution is then added to a reactor containing the mixed solution and stirred to react. The pH value is then adjusted to obtain a composite molybdenum-based nano-surfactant for oil displacement. The solvent used is deionized water or methanol.

[0037] Example 9: As an optimization of the above example, in the first step, the stirring program is to first stir at a speed of 1200 rpm to 1500 rpm for 5 min to 10 min, and then stir at a speed of 200 rpm to 300 rpm.

[0038] Example 10: As an optimization of the above example, in the first step, the pH of the mixed solution is adjusted to 7 to 8 using sodium hydroxide solution.

[0039] Example 11: As an optimization of the above example, in the second step, the pH value of the high viscosity polymer is adjusted to 7 to 8 using ammonia water with a mass concentration of 10% to 15%.

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0041] Firstly, in the molybdenum-based nano surfactant raw material for composite oil displacement of the present invention, nano molybdenum disulfide, as an inorganic component, exists in the system of molybdenum-based nano surfactant for composite oil displacement of the present invention in the form of an emulsion, which can significantly improve the viscosity and strength of molybdenum-based nano surfactant for composite oil displacement of the present invention.

[0042] Secondly, in the molybdenum-based nano-surfactant raw material for composite oil displacement of this invention, acrylamide, sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, allyl sulfone, 1-vinyl-3-ethylimidazolium bromide, and allyl alcohol polyoxyethylene ether are used as organic components. Among these, sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, 1-vinyl-3-ethylimidazolium bromide, and allyl alcohol polyoxyethylene ether belong to sulfonic acid anionic surfactants, imidazolium cationic surfactants, and polyether nonionic surfactants, respectively. Due to the presence of these functional groups, the molybdenum-based nano-surfactant for composite oil displacement of this invention can change the wetting angle of the rock, transforming it from oleophilic to hydrophilic. This significantly reduces the interfacial tension between oil and water, improves interfacial activity, and allows the oil-water system to form a low-viscosity oil-in-water emulsion under low-energy conditions. This emulsifies crude oil of different compositions, allowing crude oil to be stripped from the rock with less energy, significantly reducing the difficulty of crude oil extraction. Furthermore, the presence of allyl sulfone increases the viscoelasticity of the system, enhancing the oil displacement effect.

[0043] In summary, the molybdenum-based nano-surfactant for composite oil displacement of this invention has a small molecular size, which makes it easy to enter the nanopore throat, significantly increasing the oil displacement sweep volume, easily breaking water lock, indirectly improving core permeability, and increasing crude oil conductivity, thereby improving oil recovery. The molybdenum-based nano-surfactant for composite oil displacement of this invention has diverse mechanisms and simple synthesis methods. While ensuring ultra-low interfacial tension and high viscosity reduction rate, it also takes into account functions such as high temperature resistance, high salinity resistance, and wettability modification.

[0044] Example 12:

[0045] The molybdenum-based nano-surfactant for composite oil displacement was obtained by the following method:

[0046] The first step involved purging the reactor with nitrogen gas, maintaining a nitrogen environment throughout the synthesis process. 568g of deionized water and 7.1g of nano-molybdenum disulfide were added to the reactor. After stirring at high speed (1200 rpm) for 5 minutes, the mixture was then stirred at low speed (200 rpm) to keep the nano-molybdenum disulfide in suspension. Next, 1 mol of acrylamide, 0.1 mol of sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, 0.2 mol of allyl sulfone, 0.1 mol of 1-vinyl-3-ethylimidazolium bromide, 0.05 mol of allyl alcohol polyoxyethylene ether, 3.55g of dehydrated sorbitan monooctadecanoate (span60), and 3.55g of sodium dihydrogen phosphate were added sequentially to the reactor and stirred until homogeneous. The pH was adjusted to 7 with sodium hydroxide solution to obtain a mixed solution.

[0047] The second step involves preparing an initiator (6.3g potassium persulfate and 4.2g sodium sulfite) into a 10% aqueous solution. While stirring, the aqueous solution is slowly added dropwise to a reactor containing the mixed solution. During the addition, the system automatically heats up. After the addition is complete, stirring and maintaining the temperature for 30 minutes is continued, followed by heating to 55°C and stirring for another 60 minutes to form a high-viscosity polymer. The pH of the high-viscosity polymer is adjusted to 7 using 11% ammonia solution, and then the temperature is lowered to below 40°C to obtain a composite molybdenum-based nanosurfactant for oil displacement.

[0048] Example 13:

[0049] The molybdenum-based nano-surfactant for composite oil displacement was obtained by the following method:

[0050] The first step involved purging the reactor with nitrogen gas, maintaining a nitrogen environment throughout the synthesis process. 614 g of deionized water and 9.2 g of nano-molybdenum disulfide were added to the reactor. After stirring at high speed (1300 rpm) for 10 min, the mixture was then stirred at low speed (230 rpm) to keep the nano-molybdenum disulfide in suspension. Next, 1 mol of acrylamide, 0.14 mol of sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, 0.33 mol of allyl phenyl sulfone, 0.18 mol of 1-vinyl-3-ethylimidazolium bromide, 0.08 mol of allyl alcohol polyoxyethylene ether, 4.8 g of dehydrated sorbitan monooctadecanoate (span60), and 6.6 g of sodium dihydrogen phosphate were added sequentially to the reactor and stirred until homogeneous. The pH was adjusted to 7 with sodium hydroxide solution to obtain a mixed solution.

[0051] The second step involves preparing an initiator (6g potassium persulfate and 3.3g potassium sulfite) into a 12% aqueous solution. While stirring, the aqueous solution is slowly added dropwise to a reactor containing the mixed solution. During the addition, the system automatically heats up. After the addition is complete, stirring and maintaining the temperature for 32 minutes is continued. The temperature is then raised to 60°C and stirred for another 120 minutes to form a high-viscosity polymer. The pH of the high-viscosity polymer is adjusted to 7 using 14% ammonia water, and then the temperature is lowered to below 40°C to obtain a composite molybdenum-based nanosurfactant for oil displacement.

[0052] Example 14:

[0053] The molybdenum-based nano-surfactant for composite oil displacement was obtained by the following method:

[0054] The first step involved purging the reactor with nitrogen gas, maintaining a nitrogen environment throughout the synthesis process. 596g of deionized water and 11.4g of nano-molybdenum disulfide were added to the reactor. After high-speed stirring at 1500 rpm for 6 minutes, the mixture was then stirred at low speed at 280 rpm to keep the nano-molybdenum disulfide in suspension. Next, 1 mol of acrylamide, 0.18 mol of sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, 0.28 mol of allyl phenyl sulfone, 0.12 mol of 1-vinyl-3-ethylimidazolium bromide, 0.2 mol of allyl alcohol polyoxyethylene ether, 6.4g of dehydrated sorbitan monooctadecanoate (span60), and 7.8g of sodium dihydrogen phosphate were added sequentially to the reactor and stirred until homogeneous. The pH was adjusted to 7 with sodium hydroxide solution to obtain a mixed solution.

[0055] The second step involves preparing an initiator (8.3g potassium persulfate and 3.4g sodium sulfite) into a 15% aqueous solution. While stirring, the aqueous solution is slowly added dropwise to a reactor containing the mixed solution. During the addition, the system automatically heats up. After the addition is complete, stirring and maintaining the temperature continues for 35 minutes. The temperature is then raised to 59°C and stirred for another 120 minutes to form a high-viscosity polymer. The pH of the high-viscosity polymer is adjusted to 7 using 10% ammonia water, and then the temperature is lowered to below 40°C to obtain a composite molybdenum-based nano-surfactant for oil displacement.

[0056] Example 15:

[0057] The molybdenum-based nano-surfactant for composite oil displacement was obtained by the following method:

[0058] The first step involved purging the reactor with nitrogen gas, maintaining a nitrogen environment throughout the synthesis process. 655g of deionized water and 12.8g of nano-molybdenum disulfide were added to the reactor. After high-speed stirring at 1200 rpm for 7 minutes, the mixture was then stirred at low speed at 270 rpm to keep the nano-molybdenum disulfide in suspension. Next, 1 mol of acrylamide, 0.2 mol of sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, 0.45 mol of allyl phenyl sulfone, 0.15 mol of 1-vinyl-3-ethylimidazolium bromide, 0.15 mol of allyl alcohol polyoxyethylene ether, 8.8g of dehydrated sorbitan monooctadecanoate (span60), and 14.2g of sodium dihydrogen phosphate were added sequentially to the reactor and stirred until homogeneous. The pH was adjusted to 7 with sodium hydroxide solution to obtain a mixed solution.

[0059] The second step involves preparing an initiator (7.2g sodium persulfate and 3.3g potassium sulfite) into a 16% aqueous solution. While stirring, the aqueous solution is slowly added dropwise to a reactor containing the mixed solution. During the addition, the system automatically heats up. After the addition is complete, stirring and maintaining the temperature continues for 36 minutes. The temperature is then raised to 58°C and stirred for another 90 minutes to form a high-viscosity polymer. The pH of the high-viscosity polymer is adjusted to 7 using 12% ammonia solution, and then the temperature is lowered to below 40°C to obtain a composite molybdenum-based nano-surfactant for oil displacement.

[0060] Example 16:

[0061] The molybdenum-based nano-surfactant for composite oil displacement was obtained by the following method:

[0062] The first step involved purging the reactor with nitrogen gas, maintaining a nitrogen environment throughout the synthesis process. 710g of deionized water and 13.5g of nano-molybdenum disulfide were added to the reactor. After stirring at high speed (1500 rpm) for 8 minutes, the mixture was then stirred at low speed (260 rpm) to keep the nano-molybdenum disulfide in suspension. Next, 1 mol of acrylamide, 0.3 mol of sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, 0.46 mol of allyl phenyl sulfone, 0.2 mol of 1-vinyl-3-ethylimidazolium bromide, 0.14 mol of allyl alcohol polyoxyethylene ether, 7.6g of dehydrated sorbitan monooctadecanoate (span60), and 13.6g of sodium dihydrogen phosphate were added sequentially to the reactor and stirred until homogeneous. The pH was adjusted to 8 with sodium hydroxide solution to obtain a mixed solution.

[0063] The second step involves preparing an initiator (9.4g ammonium persulfate and 4.5g sodium sulfite) into an aqueous solution with a mass concentration of 18%. Under stirring, the aqueous solution of the initiator is slowly added dropwise to a reactor containing the mixed solution. During the dropwise addition, the system automatically heats up. After the dropwise addition is complete, stirring and maintaining the temperature for 40 minutes are continued. Then, the temperature is raised to 57°C and stirring is continued for 60 minutes to form a high-viscosity polymer. The pH value of the high-viscosity polymer is adjusted to 8 with a 15% ammonia solution, and then the temperature is lowered to below 40°C to obtain a composite molybdenum-based nano-surfactant for oil displacement.

[0064] Example 17:

[0065] The molybdenum-based nano-surfactant for composite oil displacement was obtained by the following method:

[0066] The first step involved purging the reactor with nitrogen gas, maintaining a nitrogen environment throughout the synthesis process. 688g of deionized water and 16.8g of nano-molybdenum disulfide were added to the reactor. After high-speed stirring at 1400 rpm for 9 minutes, the mixture was then stirred at low speed at 220 rpm to keep the nano-molybdenum disulfide in suspension. Next, 1 mol of acrylamide, 0.2 mol of sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, 0.38 mol of allyl phenyl sulfone, 0.2 mol of 1-vinyl-3-ethylimidazolium bromide, 0.15 mol of allyl alcohol polyoxyethylene ether, 6.5g of dehydrated sorbitan monooctadecanoate (span60), and 12.6g of sodium dihydrogen phosphate were added sequentially to the reactor and stirred until homogeneous. The pH was adjusted to 8 with sodium hydroxide solution to obtain a mixed solution.

[0067] The second step involves preparing an initiator (9.9g potassium persulfate and 3.3g sodium sulfite) into a 17% aqueous solution. While stirring, the aqueous solution is slowly added dropwise to a reactor containing the mixed solution. During the addition, the system automatically heats up. After the addition is complete, stirring and maintaining the temperature for 37 minutes is continued, followed by heating to 56°C and stirring for another 90 minutes to form a high-viscosity polymer. The pH of the high-viscosity polymer is adjusted to 8 using 10% ammonia solution, and then the temperature is lowered to below 40°C to obtain a composite molybdenum-based nanosurfactant for oil displacement.

[0068] Example 18:

[0069] The molybdenum-based nano-surfactant for composite oil displacement was obtained by the following method:

[0070] The first step involved purging the reactor with nitrogen gas, maintaining a nitrogen environment throughout the synthesis process. 666g of deionized water and 19.6g of nano-molybdenum disulfide were added to the reactor. After high-speed stirring at 1400 rpm for 10 minutes, the mixture was then stirred at low speed at 250 rpm to keep the nano-molybdenum disulfide in suspension. Next, 1 mol of acrylamide, 0.25 mol of sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, 0.52 mol of allyl phenyl sulfone, 0.18 mol of 1-vinyl-3-ethylimidazolium bromide, 0.15 mol of allyl alcohol polyoxyethylene ether, 9.9g of dehydrated sorbitan monooctadecanoate (span60), and 10.3g of sodium dihydrogen phosphate were added sequentially to the reactor and stirred until homogeneous. The pH was adjusted to 8 with sodium hydroxide solution to obtain a mixed solution.

[0071] The second step involves preparing a 20% methanol solution of initiator (7.1g azobisisobutyronitrile). Under stirring, the methanol solution of initiator is slowly added dropwise to a reactor containing the mixed solution. The system automatically heats up during the dropwise addition. After the dropwise addition is complete, stirring and maintaining the temperature for 35 minutes is continued. Then, the temperature is raised to 60°C and stirring is continued for 100 minutes to form a high-viscosity polymer. The pH value of the high-viscosity polymer is adjusted to 8 with 13% ammonia water, and then the temperature is lowered to below 40°C to obtain a molybdenum-based nano-surfactant for composite oil displacement.

[0072] Example 19:

[0073] The molybdenum-based nano-surfactant for composite oil displacement was obtained by the following method:

[0074] The first step involved purging the reactor with nitrogen gas, maintaining a nitrogen environment throughout the synthesis process. 645g of deionized water and 18.4g of nano-molybdenum disulfide were added to the reactor. After stirring at high speed (1300 rpm) for 6 minutes, the mixture was then stirred at low speed (300 rpm) to keep the nano-molybdenum disulfide in suspension. Next, 1 mol of acrylamide, 0.27 mol of sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, 0.55 mol of allyl phenyl sulfone, 0.28 mol of 1-vinyl-3-ethylimidazolium bromide, 0.13 mol of allyl alcohol polyoxyethylene ether, 12.4g of dehydrated sorbitan monooctadecanoate (span60), and 9.6g of sodium dihydrogen phosphate were added sequentially to the reactor and stirred until homogeneous. The pH was adjusted to 8 with sodium hydroxide solution to obtain a mixed solution.

[0075] The second step involves preparing a 15% methanol solution of initiator (14.2g azobisisobutyronitrile). Under stirring, the methanol solution of initiator is slowly added dropwise to a reactor containing the mixed solution. The system automatically heats up during the dropwise addition. After the dropwise addition is complete, stirring and maintaining the temperature for 40 minutes are continued. Then, the temperature is raised to 55°C and stirring is continued for 80 minutes to form a high-viscosity polymer. The pH value of the high-viscosity polymer is adjusted to 8 with 15% ammonia water, and then the temperature is lowered to below 40°C to obtain a composite molybdenum-based nano-surfactant for oil displacement.

[0076] Example 20:

[0077] The molybdenum-based nano-surfactant for composite oil displacement was obtained by the following method:

[0078] The first step involved purging the reactor with nitrogen gas, maintaining a nitrogen environment throughout the synthesis process. 657g of deionized water and 21.3g of nano-molybdenum disulfide were added to the reactor. After high-speed stirring at 1300 rpm for 5 minutes, the mixture was then stirred at low speed at 200 rpm to keep the nano-molybdenum disulfide in suspension. Next, 1 mol of acrylamide, 0.29 mol of sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, 0.58 mol of allyl phenyl sulfone, 0.25 mol of 1-vinyl-3-ethylimidazolium bromide, 0.09 mol of allyl alcohol polyoxyethylene ether, 14.2g of dehydrated sorbitan monooctadecanoate (span60), and 10.4g of sodium dihydrogen phosphate were added sequentially to the reactor and stirred until homogeneous. The pH was adjusted to 8 with sodium hydroxide solution to obtain a mixed solution.

[0079] The second step involves preparing a 13% methanol solution of initiator (10.3g azobisisobutyronitrile). Under stirring, the methanol solution of initiator is slowly added dropwise to a reactor containing the mixed solution. The system automatically heats up during the dropwise addition. After the dropwise addition is complete, stirring and maintaining the temperature for 38 minutes are continued. Then, the temperature is raised to 55°C and stirring is continued for 90 minutes to form a high-viscosity polymer. The pH value of the high-viscosity polymer is adjusted to 8 with 10% ammonia water, and then the temperature is lowered to below 40°C to obtain a molybdenum-based nano-surfactant for composite oil displacement.

[0080] Example 21:

[0081] The molybdenum-based nano-surfactant for composite oil displacement was obtained by the following method:

[0082] The first step involved purging the reactor with nitrogen gas, maintaining a nitrogen environment throughout the synthesis process. 692g of deionized water and 21.3g of nano-molybdenum disulfide were added to the reactor. After high-speed stirring at 1500 rpm for 7 minutes, the mixture was then stirred at low speed at 300 rpm to keep the nano-molybdenum disulfide in suspension. Next, 1 mol of acrylamide, 0.3 mol of sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, 0.6 mol of allyl sulfone, 0.3 mol of 1-vinyl-3-ethylimidazolium bromide, 0.11 mol of allyl alcohol polyoxyethylene ether, 10.1g of dehydrated sorbitan monooctadecanoate (span60), and 8.8g of sodium dihydrogen phosphate were added sequentially to the reactor and stirred until homogeneous. The pH was adjusted to 8 with sodium hydroxide solution to obtain a mixed solution.

[0083] The second step involves preparing a 20% methanol solution of initiator (11.8g azobisisobutyronitrile). Under stirring, the methanol solution of initiator is slowly added dropwise to a reactor containing the mixed solution. The system automatically heats up during the dropwise addition. After the dropwise addition is complete, stirring and maintaining the temperature for 33 minutes are continued. Then, the temperature is raised to 60°C and stirring is continued for 110 minutes to form a high-viscosity polymer. The pH value of the high-viscosity polymer is adjusted to 8 with 12% ammonia water, and then the temperature is lowered to below 40°C to obtain a molybdenum-based nano-surfactant for composite oil displacement.

[0084] Example 22: The performance of the molybdenum-based nanosurfactant for composite oil displacement of the present invention was tested according to the methods specified in SY / T 5370-2018 "Methods for Determination of Surface and Interfacial Tension" and Q / SH1020 1519-2016 "General Technical Conditions for Heavy Oil Viscosity Reducers". The performance tests included surface tension, interfacial tension, and viscosity reduction rate. The crude oil used in this experiment was an oil sample from the Shengli Oilfield block, with an initial viscosity of 12000 mPa∙s at 50°C. The test method was as follows: the molybdenum-based nanosurfactant for composite oil displacement prepared in Examples 12 to 21 of the present invention was prepared into solutions with concentrations of 500 mg / L and 2000 mg / L, respectively. Meanwhile, the sulfonate SL-3 for oil displacement from Shengli Chemical Plant was used as a control.

[0085] The test results are shown in Table 1. As can be seen from Table 1, at a concentration of 500 mg / L, the surface tension of the composite oil displacement molybdenum-based nanosurfactants prepared in Examples 12 to 21 of this invention is all below 26 mN / m, with the lowest surface tension being 24.8 mN / m in Example 20. In contrast, the surface tension of the existing oil displacement sulfonate SL-3 is 29.7 mN / m, which is significantly higher than that of the composite oil displacement molybdenum-based nanosurfactant of this invention.

[0086] At a concentration of 500 mg / L, the interfacial tension of the composite oil displacement molybdenum-based nanosurfactants prepared in Examples 12 to 21 of this invention is all below 10. -4 mN / m, wherein the interfacial tension of Example 20 is the lowest at 5×10 mN / m. -5 mN / m; while the interfacial tension of the existing oil displacement sulfonate SL-3 is 1500×10 mN / m. -3 mN / m, which is significantly higher than that of the molybdenum-based nano surfactant used in the composite oil displacement of this invention;

[0087] At a concentration of 2000 mg / L, the viscosity reduction rates of the composite oil displacement molybdenum-based nanosurfactants prepared in Examples 12 to 21 of this invention are all greater than 98%, with the viscosity reducer in Example 20 reaching the highest at 99%. In contrast, the viscosity reduction rate of the existing oil displacement sulfonate SL-3 is 92.1%, significantly lower than that of the composite oil displacement molybdenum-based nanosurfactant of this invention. In summary, compared to existing oil displacement agents, the composite oil displacement molybdenum-based nanosurfactant of this invention exhibits lower surface tension, lower interfacial tension, and better viscosity reduction effect.

[0088] In summary, the molybdenum-based nanosurfactant for composite oil displacement of this invention not only possesses ultra-low surface tension and interfacial tension, but also achieves a surface tension of 26 mN / m and an interfacial tension of 10 mN / m at a concentration of 500 mg / L. -4 Below mN / m, it also has a high viscosity reduction effect, with a viscosity reduction rate of over 98% at a concentration of 2000 mg / L. In addition, the synthesis of the molybdenum-based nano surfactant for composite oil displacement in this invention adopts a one-pot method, the raw materials are readily available, the synthesis process is simple, there are no by-products, and it is safe and environmentally friendly.

[0089] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

[0090]

Claims

1. A molybdenum-based nanosurfactant for composite oil displacement, characterized in that... The raw materials include acrylamide, sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, allyl phenyl sulfone, 1-vinyl-3-ethylimidazolium bromide, allyl alcohol polyoxyethylene ether, nano molybdenum disulfide, and an initiator; wherein the molar ratio of acrylamide, sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, allyl phenyl sulfone, 1-vinyl-3-ethylimidazolium bromide, and allyl alcohol polyoxyethylene ether is 1:0.1 to 0.3:0.2 to 0.6:0.1 to 0.3:0.05 to 0.2; and the weight ratio of nano molybdenum disulfide, initiator, and acrylamide is 0.1 to 0.3:0.1 to 0.2:

1.

2. The molybdenum-based nanosurfactant for composite oil displacement according to claim 1, characterized in that... The initiator is one of the following: a redox agent and an azo compound.

3. The molybdenum-based nanosurfactant for composite oil displacement according to claim 2, characterized in that... The redox agent is composed of a combination of persulfate and sulfite in a weight ratio of 1.5 to 3.0:

1. The persulfate is one of potassium persulfate, sodium persulfate, and ammonium persulfate, and the sulfite is sodium sulfite or potassium sulfite.

4. The molybdenum-based nanosurfactant for composite oil displacement according to claim 2 or 3, characterized in that... The azo compound is azobisisobutyronitrile or azobisisoheptanenitrile.

5. The molybdenum-based nanosurfactant for composite oil displacement according to claim 4, characterized in that... The raw materials also include deionized water, dehydrated sorbitan monooctadecyl ester and buffer salt, with the weight ratio of deionized water, dehydrated sorbitan monooctadecyl ester, buffer salt and acrylamide being 8 to 10: 0.05 to 0.2: 0.05 to 0.2:

1.

6. The molybdenum-based nanosurfactant for composite oil displacement according to claim 5, characterized in that... The buffer salt is one of sodium dihydrogen phosphate, potassium dihydrogen phosphate, ammonium dihydrogen phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, and diammonium hydrogen phosphate.

7. The composite oil displacement molybdenum-based nanosurfactant according to claim 1, 2, 3, 5, or 6, characterized in that... Obtained using the following method: First, under a nitrogen atmosphere, the required amount of deionized water and nano-molybdenum disulfide were added to the reactor and stirred under programmed stirring. Then, the required amounts of acrylamide, sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, allyl sulfone, 1-vinyl-3-ethylimidazolium bromide, allyl alcohol polyoxyethylene ether, dehydrated sorbitan monooctadecyl ester and buffer salt were added to the reactor and stirred until homogeneous. After adjusting the pH value, a mixed solution was obtained. The second step involves adding an initiator solution to a reactor containing the mixed solution and stirring the reaction. Then, the pH value is adjusted to obtain a composite molybdenum-based nano-surfactant for oil displacement.

8. The molybdenum-based nanosurfactant for composite oil displacement according to claim 7, characterized in that... In the first step, the stirring program is to first stir at a speed of 1200 rpm to 1500 rpm for 5 to 10 minutes, and then stir at a speed of 200 rpm to 300 rpm; or / and, in the first step, the pH of the mixed solution is adjusted to 7 to 8 with sodium hydroxide solution.

9. The molybdenum-based nanosurfactant for composite oil displacement according to claim 8, characterized in that... In the second step, the pH value is adjusted to 7 to 8 using ammonia water with a mass concentration of 10% to 15%.

10. A method for preparing a composite oil displacement molybdenum-based nanosurfactant according to any one of claims 1 to 6, 8 to 9, characterized in that... Perform the following steps: First, under a nitrogen atmosphere, the required amount of deionized water and nano-molybdenum disulfide were added to the reactor and stirred under programmed stirring. Then, the required amounts of acrylamide, sodium 3-methacryloyloxy-2-hydroxypropylsulfonate, allyl sulfone, 1-vinyl-3-ethylimidazolium bromide, allyl alcohol polyoxyethylene ether, dehydrated sorbitan monooctadecyl ester and buffer salt were added to the reactor and stirred until homogeneous. After adjusting the pH value, a mixed solution was obtained. The second step involves adding an initiator solution to a reactor containing the mixed solution and stirring the reaction. Then, the pH value is adjusted to obtain a composite molybdenum-based nano-surfactant for oil displacement.

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