Carbon quantum dot oil-displacing agent with slow release function and preparation method of carbon quantum dot oil-displacing agent

Abstract

The invention discloses a carbon quantum dot oil displacement agent with a slow release function and a preparation method thereof, and relates to the technical field of petrochemical industry. The carbon quantum dot oil displacement agent with the slow release function is marked as a solution C, the solution C comprises a solution A and a solution B, the solution A comprises glucose, lauryl amine and deionized water, the solution B comprises a polylactic acid-glycolic acid copolymer and dichloromethane, and the solution C is prepared by stirring and distilling the solution A and the solution B, and the solution C also internally comprises nonylphenol polyoxyethylene ether and a glutaraldehyde solution. According to the carbon quantum dot oil displacement agent, the interfacial activity and nano permeability of the carbon quantum dots are combined with the slow release and protection functions of the microcapsules, the advantages of high stability, slow release and controlled release, efficient oil displacement and environment friendliness are achieved, the carbon quantum dot oil displacement agent can adapt to complex oil reservoir conditions, the oil displacement efficiency and the recovery efficiency can be improved, and the oil displacement effect is good. The method has remarkable technical advantages and wide application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of petrochemical engineering, and specifically relates to a carbon quantum dot oil-displacing agent with a slow-release function and a preparation method thereof. Background Art

[0002] With the continuous growth of energy demand, oil, as one of the main energy sources, has attracted increasing attention for its extraction technology. Especially for difficult-to-extract oil reservoirs such as tight oil and shale oil, traditional secondary and tertiary oil recovery technologies can no longer meet the oil recovery needs. Therefore, developing new oil displacement agents to improve oil field recovery has become an important research direction in the field of oil field extraction.

[0003] As a new type of nanomaterial, carbon quantum dots have been widely used in many fields due to their unique physical and chemical properties, such as high specific surface area, good optical and electrical properties, and low toxicity. In oilfield development, carbon quantum dots can be used as part of the oil displacement agent, which can improve the oil recovery effect of the reservoir by changing the interfacial tension of the fluid and enhancing the permeability of the fluid. However, the application of carbon quantum dots in oilfield recovery still faces some challenges, such as the difficulty in the efficient use of monomeric carbon quantum dots at the oil-water interface and the insufficient slow release effect in long-term operations.

[0004] As an effective controlled release technology, microencapsulation technology is widely used in drug delivery, agricultural fertilizers, food and other fields. Microcapsules can effectively encapsulate active substances and control their release rate, thereby prolonging their effectiveness and enhancing their stability. Combining microencapsulation technology with carbon quantum dots can improve the stability of carbon quantum dots in oil reservoirs, prolong the duration of their oil recovery effect, and effectively control the release rate of carbon quantum dots at the oil-water interface, avoiding premature release of carbon quantum dots, thereby improving oil recovery efficiency. Summary of the invention

[0005] The object of the present invention is to provide a carbon quantum dot oil-displacing agent with a sustained-release function and a preparation method thereof, so as to solve the problems raised in the above-mentioned background technology.

[0006] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0007] The present invention provides a carbon quantum dot oil-displacing agent with a sustained-release function, wherein the carbon quantum dot oil-displacing agent is recorded as a C solution, wherein the C solution comprises an A solution and a B solution, wherein the A solution comprises glucose, dodecylamine and deionized water, and the B solution comprises a polylactic acid-glycolic acid copolymer and dichloromethane.

[0008] The C solution is prepared by stirring and distilling the A solution and the B solution, and the C solution also includes nonylphenol polyoxyethylene ether and glutaraldehyde solution.

[0009] As a preferred embodiment of the present invention, the mass ratio of glucose to dodecylamine is 1:(1-1.2), and the added amount of deionized water is 8-10 times the total mass of glucose and dodecylamine.

[0010] As a preferred embodiment of the present invention, the added amount of dichloromethane is 20 to 30 times the mass of the polylactic acid-glycolic acid copolymer.

[0011] As a preferred embodiment of the present invention, the mass ratio of solution A to solution B is 1:(10-15).

[0012] As a preferred embodiment of the present invention, the addition amount of the nonylphenol polyoxyethylene ether is 2-4% of the total mass of the C solution.

[0013] As a preferred embodiment of the present invention, the mass concentration of the glutaraldehyde solution is 1-2%, and the added amount of the glutaraldehyde solution is 5-8% of the mass of the B solution.

[0014] The present invention also provides a method for preparing a carbon quantum dot oil-displacing agent with a sustained-release function, comprising the following steps:

[0015] S1. Dissolve a certain amount of glucose and dodecylamine in deionized water and adjust the pH to 6-7. Place the solution in a high-pressure reactor and react at 160-200°C for 5-7 hours to obtain a carbon quantum dot solution. Use a 0.22 μm filter membrane to remove large particle impurities, and a dialysis bag to remove small molecule precursors. Collect the purified carbon quantum dot solution and record it as solution A.

[0016] S2, dissolving a certain amount of poly(lactic acid-glycolic acid) copolymer in dichloromethane to form a microcapsule wall material solution, which is referred to as solution B;

[0017] S3. Slowly pour a certain amount of the above-mentioned A solution into the B solution, add an appropriate amount of nonylphenol polyoxyethylene ether thereto, ultrasonicate for 30 to 60 minutes, and stir vigorously for emulsification to ensure that the carbon quantum dots are evenly dispersed in the emulsion. Under stirring, continue to drop a certain amount of glutaraldehyde solution to promote cross-linking between the wall material molecules to form the shell of the microcapsule. Remove the organic solvent in the emulsion by vacuum distillation, and the wall material condenses into microcapsules to wrap the carbon quantum dots. Continue stirring until the microcapsules are completely solidified to form a carbon quantum dot oil-displacing agent with a sustained release function, which is recorded as C solution.

[0018] As a preferred embodiment of the present invention, in S1, the molecular weight cutoff range of the dialysis bag is 3000-3500Da.

[0019] Compared with the prior art, the present invention provides a carbon quantum dot oil-displacing agent with a sustained-release function and a preparation method thereof, wherein carbon quantum dots are prepared using glucose and dodecylamine, a microcapsule wall material solution is prepared using PLGA as a wall material, and then the carbon quantum dots are wrapped with microcapsules to form a carbon quantum dot oil-displacing agent with a sustained-release function.

[0020] One or more of the above technical solutions have the following beneficial effects:

[0021] 1. In the carbon quantum dot oil displacement agent with slow-release function and its preparation method, first of all, it has good amphiphilicity and can effectively reduce the oil-water interfacial tension. Secondly, it has a small particle size and belongs to nanoscale materials, which can enter the tiny pores in the oil reservoir and effectively penetrate into low-permeability oil reservoirs and shale oil reservoirs and other difficult-to-develop areas. Finally, the use of microcapsules to encapsulate carbon quantum dots can achieve the slow release of carbon quantum dots in the oil reservoir, expand the sweep efficiency, and effectively isolate the complex external environment (such as high temperature, high salt and strong acid and alkali, etc.), prevent carbon quantum dots from agglomerating, dissolving or degrading, and significantly improve the stability and service life of carbon quantum dots in the oil reservoir environment;

[0022] 2. In the carbon quantum dot oil displacement agent with slow-release function and its preparation method, the interfacial activity and nano-permeability of carbon quantum dots are combined with the slow-release and protection functions of microcapsules, achieving the advantages of high stability, slow-release and controlled release, efficient oil displacement and environmental friendliness. It can not only adapt to complex reservoir conditions, but also improve oil displacement efficiency and recovery rate, with significant technical advantages and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0024] Figure 1 This is a diagram of the sustained release mechanism of the carbon quantum dot oil displacement agent of the present invention;

[0025] Figure 2 This is a graph showing the change of the interfacial tension of the carbon quantum dot oil displacement agent solution prepared by the present invention over time;

[0026] Figure 3 This is a transmission electron microscope image of the carbon quantum dot oil displacement agent solution prepared by the present invention;

[0027] Figure 4 is a raw material composition diagram of the carbon quantum dot oil displacement agent solution prepared in Example 1 of the present invention;

[0028] Figure 5 is a raw material composition diagram of the carbon quantum dot oil displacement agent solution prepared in Example 2 of the present invention;

[0029] Figure 6 is a raw material composition diagram of the carbon quantum dot oil displacement agent solution prepared in Example 3 of the present invention;

[0030] Figure 7 is a raw material composition diagram of the carbon quantum dot oil displacement agent solution prepared in Example 4 of the present invention;

[0031] Figure 8 is a raw material composition diagram of the carbon quantum dot oil displacement agent solution prepared in Example 5 of the present invention;

[0032] Fig. 9 This is a raw material composition diagram of the carbon quantum dot oil displacement agent solution prepared in Example 6 of the present invention. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0034] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0035] Herein, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0036] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0037] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0038] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0039] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0040] See also Figure 1-Figure 9 The present invention discloses a carbon quantum dot oil displacement agent with a sustained release function, and the specific preparation steps are as follows:

[0041] S1: Dissolve a certain amount of glucose and dodecylamine in deionized water and adjust the pH to 6-7. Place the solution in a high-pressure reactor and react at 160-200°C for 5-7 hours to obtain a carbon quantum dot solution. Use a 0.22μm filter membrane to remove large particle impurities, a dialysis bag to remove small molecule precursors, and collect the purified carbon quantum dot solution, which is recorded as solution A. Among them, the mass ratio of glucose to dodecylamine is 1: (1-1.2), the amount of deionized water added is 8-10 times the total mass of glucose and dodecylamine, and the molecular weight cutoff range of the dialysis bag is 3000-3500Da.

[0042] S2: a certain amount of poly(lactic acid-co-glycolic acid) (PLGA) is dissolved in dichloromethane to form a microcapsule wall material solution, which is referred to as solution B. The amount of dichloromethane added is 20 to 30 times the mass of PLGA.

[0043] S3: Slowly pour a certain amount of the above-mentioned A solution into the B solution, then add an appropriate amount of nonylphenol polyoxyethylene ether thereto, ultrasonicate for 30 to 60 minutes, and stir vigorously for emulsification to ensure that the carbon quantum dots are evenly dispersed in the emulsion. Under stirring, continue to drip a certain amount of glutaraldehyde solution to promote cross-linking between the wall material molecules to form the shell of the microcapsule. The organic solvent in the emulsion is removed by vacuum distillation, and the wall material condenses into microcapsules to wrap the carbon quantum dots. Continue stirring until the microcapsules are completely solidified to form a carbon quantum dot oil displacement agent with a sustained release function. Among them, the mass ratio of A solution to B solution is 1: (10 to 15), the amount of nonylphenol polyoxyethylene ether added is 2 to 4% of the total mass of A solution and B solution, the mass concentration of glutaraldehyde solution is 1 to 2%, and the amount of glutaraldehyde solution added is 5 to 8% of the mass of B solution.

[0044] The present invention will be further described below in conjunction with specific embodiments:

[0045] Example 1, specific reference Figure 4 ,

[0046] S1: Dissolve 2g of glucose and 2g of dodecylamine in 40g of deionized water and adjust the pH to 7. Place the solution in a high-pressure reactor and react at 160°C for 7h to obtain a carbon quantum dot solution. Use a 0.22μm filter membrane to remove large particle impurities, use a dialysis bag with a molecular weight cutoff of 3000Da to remove small molecule precursors, and collect the purified carbon quantum dot solution, which is recorded as solution A.

[0047] S2: 2 g of poly(lactic acid-co-glycolic acid) (PLGA) was dissolved in 40 g of dichloromethane to form a microcapsule wall material solution, which was recorded as solution B.

[0048] S3: Slowly pour 2g of the above-mentioned solution A into 20g of solution B, then add 0.44g of nonylphenol polyoxyethylene ether, ultrasonicate for 60min, and stir vigorously for emulsification to ensure that the carbon quantum dots are evenly dispersed in the emulsion. While stirring, continue to drip 1g of 1% mass concentration of glutaraldehyde solution to promote cross-linking between wall material molecules to form the shell of the microcapsule. Remove the organic solvent in the emulsion by vacuum distillation, and the wall material condenses into microcapsules to wrap the carbon quantum dots. Continue stirring until the microcapsules are completely solidified to form a carbon quantum dot oil displacement agent with sustained release function.

[0049] Example 2, specific reference Figure 5 ,

[0050] S1: Dissolve 2g of glucose and 2.4g of dodecylamine in 35.2g of deionized water and adjust the pH to 6. Place the solution in a high-pressure reactor and react at 200°C for 5h to obtain a carbon quantum dot solution. Use a 0.22μm filter membrane to remove large particle impurities, use a dialysis bag with a molecular weight cutoff of 3500Da to remove small molecule precursors, and collect the purified carbon quantum dot solution, which is recorded as solution A.

[0051] S2: 2 g of poly(lactic acid-co-glycolic acid) (PLGA) was dissolved in 60 g of dichloromethane to form a microcapsule wall material solution, which was recorded as solution B.

[0052] S3: Slowly pour 2g of the above-mentioned solution A into 30g of solution B, then add 1.28g of nonylphenol polyoxyethylene ether, ultrasonicate for 30min, and stir vigorously for emulsification to ensure that the carbon quantum dots are evenly dispersed in the emulsion. While stirring, continue to drip 2.4g of glutaraldehyde solution with a mass concentration of 2% to promote cross-linking between the wall material molecules to form the shell of the microcapsule. The organic solvent in the emulsion is removed by vacuum distillation, and the wall material condenses into microcapsules to wrap the carbon quantum dots. Continue stirring until the microcapsules are completely solidified to form a carbon quantum dot oil displacement agent with a sustained release function.

[0053] Example 3, specific reference Figure 6 ,

[0054] S1: Dissolve 2g of glucose and 2.2g of dodecylamine in 40g of deionized water and adjust the pH to 7. Place the solution in a high-pressure reactor and react at 180°C for 6h to obtain a carbon quantum dot solution. Use a 0.22μm filter membrane to remove large particle impurities, use a dialysis bag with a molecular weight cutoff of 3500Da to remove small molecule precursors, and collect the purified carbon quantum dot solution, which is recorded as solution A.

[0055] S2: 2 g of poly(lactic acid-co-glycolic acid) (PLGA) was dissolved in 50 g of dichloromethane to form a microcapsule wall material solution, which was recorded as solution B.

[0056] S3: Slowly pour 2g of the above-mentioned A solution into 25g of B solution, then add 0.8g of nonylphenol polyoxyethylene ether, ultrasonicate for 60min, and stir vigorously for emulsification to ensure that the carbon quantum dots are evenly dispersed in the emulsion. While stirring, continue to drip 1.5g of glutaraldehyde solution with a mass concentration of 2% to promote cross-linking between the wall material molecules to form the shell of the microcapsule. The organic solvent in the emulsion is removed by vacuum distillation, and the wall material condenses into microcapsules to wrap the carbon quantum dots. Continue stirring until the microcapsules are completely solidified to form a carbon quantum dot oil displacement agent with a sustained release function.

[0057] Example 4, specific reference Figure 7 ,

[0058] S1: Dissolve 2g of glucose and 2.1g of dodecylamine in 35g of deionized water and adjust the pH to 6. Place the solution in a high-pressure reactor and react at 180°C for 5h to obtain a carbon quantum dot solution. Use a 0.22μm filter membrane to remove large particle impurities, use a dialysis bag with a molecular weight cutoff of 3000Da to remove small molecule precursors, and collect the purified carbon quantum dot solution, which is recorded as solution A.

[0059] S2: 2 g of poly(lactic acid-co-glycolic acid) (PLGA) was dissolved in 45 g of dichloromethane to form a microcapsule wall material solution, which was recorded as solution B.

[0060] S3: Slowly pour 2g of the above-mentioned solution A into 24g of solution B, then add 0.8g of nonylphenol polyoxyethylene ether, ultrasonicate for 40min, and stir vigorously for emulsification to ensure that the carbon quantum dots are evenly dispersed in the emulsion. While stirring, continue to drip 1.6g of glutaraldehyde solution with a mass concentration of 1.5% to promote cross-linking between the wall material molecules to form the shell of the microcapsule. The organic solvent in the emulsion is removed by vacuum distillation, and the wall material condenses into microcapsules to wrap the carbon quantum dots. Continue stirring until the microcapsules are completely solidified to form a carbon quantum dot oil displacement agent with a sustained release function.

[0061] Example 5, specific reference Figure 8 ,

[0062] S1: Dissolve 2g of glucose and 2.3g of dodecylamine in 35g of deionized water and adjust the pH to 6. Place the solution in a high-pressure reactor and react at 160°C for 6h to obtain a carbon quantum dot solution. Use a 0.22μm filter membrane to remove large particle impurities, use a dialysis bag with a molecular weight cutoff of 3000Da to remove small molecule precursors, and collect the purified carbon quantum dot solution, which is recorded as solution A.

[0063] S2: 2 g of poly(lactic acid-co-glycolic acid) (PLGA) was dissolved in 40 g of dichloromethane to form a microcapsule wall material solution, which was recorded as solution B.

[0064] S3: Slowly pour 2g of the above-mentioned A solution into 22g of B solution, then add 1.1g of nonylphenol polyoxyethylene ether, ultrasonicate for 30min, and stir vigorously for emulsification to ensure that the carbon quantum dots are evenly dispersed in the emulsion. While stirring, continue to drop 1.5g of 1% mass concentration of glutaraldehyde solution to promote cross-linking between wall material molecules to form the shell of the microcapsule. The organic solvent in the emulsion is removed by vacuum distillation, and the wall material condenses into microcapsules to wrap the carbon quantum dots. Continue stirring until the microcapsules are completely solidified to form a carbon quantum dot oil displacement agent with sustained release function.

[0065] Example 6, specific reference Fig. 9 ,

[0066] S1: Dissolve 2g of glucose and 2.4g of dodecylamine in 40g of deionized water and adjust the pH to 7. Place the solution in a high-pressure reactor and react at 200°C for 7h to obtain a carbon quantum dot solution. Use a 0.22μm filter membrane to remove large particle impurities, use a dialysis bag with a molecular weight cutoff of 3500Da to remove small molecule precursors, and collect the purified carbon quantum dot solution, which is recorded as solution A.

[0067] S2: 2 g of poly(lactic acid-co-glycolic acid) (PLGA) was dissolved in 42 g of dichloromethane to form a microcapsule wall material solution, which was recorded as solution B.

[0068] S3: Slowly pour 2g of the above-mentioned solution A into 20g of solution B, then add 0.8g of nonylphenol polyoxyethylene ether, ultrasonicate for 60min, and stir vigorously for emulsification to ensure that the carbon quantum dots are evenly dispersed in the emulsion. While stirring, continue to drip 1.2g of glutaraldehyde solution with a mass concentration of 2% to promote cross-linking between the wall material molecules to form the shell of the microcapsule. The organic solvent in the emulsion is removed by vacuum distillation, and the wall material condenses into microcapsules to wrap the carbon quantum dots. Continue stirring until the microcapsules are completely solidified to form a carbon quantum dot oil displacement agent with a sustained release function.

[0069] Performance Characterization

[0070] In order to evaluate the sustained-release function of the carbon quantum dot oil-displacing agent with sustained-release function, 0.2 g of the carbon quantum dot oil-displacing agent prepared in Example 3 was dispersed in 50 g of deionized water and placed in an oven at 60° C. for different periods of time to test its interfacial tension. The results are as follows: Figure 2 As shown. Figure 2 It can be seen that as time goes by, PLGA gradually absorbs water and swells, some carbon quantum dot oil displacement agents begin to slowly release and diffuse, and the oil-water interfacial tension gradually decreases. When the time is 100h, the oil-water interfacial tension reaches an ultra-low (10-3), which can effectively improve the crude oil recovery rate. The carbon quantum dot oil displacement agent solution after 100h is dropped onto the ultra-thin carbon film and observed using a transmission electron microscope. The results are as follows: Figure 3 As shown. Figure 3 It can be seen that its particle size is less than 10nm, which can penetrate into the nanopore area that conventional oil displacement agents cannot reach, sweeping more residual oil, and has great application potential.

[0071] Without limitation, any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent substitutions or changes according to the technical solution and inventive concept of the present invention, should be covered by the protection scope of the present invention.

Claims

1. A carbon quantum dot oil-displacing agent with a sustained-release function, characterized in that: The carbon quantum dot oil displacement agent is recorded as C solution, and the C solution includes A solution and B solution, the A solution includes glucose, dodecylamine and deionized water, and the B solution includes polylactic acid-glycolic acid copolymer and dichloromethane. The C solution is prepared by stirring and distilling the A solution and the B solution, and the C solution also includes nonylphenol polyoxyethylene ether and glutaraldehyde solution.

2. The carbon quantum dot oil-displacing agent with sustained-release function according to claim 1, characterized in that: The mass ratio of the glucose to dodecylamine is 1:(1-1.2), and the added amount of the deionized water is 8-10 times the total mass of the glucose and dodecylamine.

3. The carbon quantum dot oil-displacing agent with sustained-release function according to claim 1, characterized in that: The added amount of the dichloromethane is 20 to 30 times the mass of the polylactic acid-glycolic acid copolymer.

4. The carbon quantum dot oil-displacing agent with sustained-release function according to claim 1, characterized in that: The mass ratio of the A solution to the B solution is 1:(10-15).

5. The carbon quantum dot oil-displacing agent with sustained-release function according to claim 1, characterized in that: The addition amount of the nonylphenol polyoxyethylene ether is 2-4% of the total mass of the C solution.

6. The carbon quantum dot oil-displacing agent with sustained-release function according to claim 1, characterized in that: The mass concentration of the glutaraldehyde solution is 1-2%, and the added amount of the glutaraldehyde solution is 5-8% of the mass of the B solution.

7. A method for preparing a carbon quantum dot oil-displacing agent with a sustained-release function, characterized in that: The following steps are involved: S1. Dissolve a certain amount of glucose and dodecylamine in deionized water and adjust the pH to 6 to 7. Place the solution in a high-pressure reactor and react at 160 to 200° C. for 5 to 7 hours to obtain a carbon quantum dot solution. A 0.22 μm filter membrane was used to remove large particle impurities, and a dialysis bag was used to remove small molecule precursors. The purified carbon quantum dot solution was collected and recorded as solution A. S2, dissolving a certain amount of poly(lactic acid-glycolic acid) copolymer in dichloromethane to form a microcapsule wall material solution, which is referred to as solution B; S3. Slowly pour a certain amount of the above-mentioned A solution into the B solution, add an appropriate amount of nonylphenol polyoxyethylene ether thereto, ultrasonicate for 30 to 60 minutes, and stir vigorously for emulsification to ensure that the carbon quantum dots are evenly dispersed in the emulsion. Under stirring, continue to drop a certain amount of glutaraldehyde solution to promote cross-linking between the wall material molecules to form the shell of the microcapsule. Remove the organic solvent in the emulsion by vacuum distillation, and the wall material condenses into microcapsules to wrap the carbon quantum dots. Continue stirring until the microcapsules are completely solidified to form a carbon quantum dot oil-displacing agent with a sustained release function, which is recorded as C solution.

8. The method for preparing a carbon quantum dot oil-displacing agent with a sustained-release function according to claim 7, characterized in that: In S1, the molecular weight cutoff range of the dialysis bag is 3000-3500Da.

Images