Fluorescent tracing type nitrogen-doped carbon quantum dot oil displacement agent and preparation method thereof

Abstract

The invention discloses a fluorescent tracing type nitrogen-doped carbon quantum dot oil displacement agent and a preparation method thereof, and relates to the technical field of petrochemical industry. The fluorescent tracing type nitrogen-doped carbon quantum dot oil displacement agent is prepared from humic acid, urea, deionized water, absolute ethyl alcohol, cetyltrimethylammonium bromide and triethylamine, a mixed solution of the humic acid, the urea and the deionized water is marked as a carbon quantum dot solution, and the mixed solution of the carbon quantum dot solution and the absolute ethyl alcohol is marked as a fluorescent tracing type nitrogen-doped carbon quantum dot oil displacement agent. The carbon quantum dot solution is prepared into carbon quantum dot particles through freeze drying. The fluorescent tracing type nitrogen-doped carbon quantum dot oil-displacing agent disclosed by the invention not only improves the oil-displacing efficiency and has fluorescent tracing performance, but also has the environmental protection property of green synthesis and the simplicity and convenience of a synthesis process, is beneficial to improving the recovery efficiency, reducing the cost and reducing the environmental influence in the oilfield exploitation process, and has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of petrochemical industry, and in particular relates to a fluorescent tracer type nitrogen-doped carbon quantum dot oil displacement agent and a preparation method thereof. Background Art

[0002] With the continuous growth of global energy demand, the exploitation of oil and gas resources faces increasing challenges. Especially in the exploitation process of conventional oil fields, as the degree of oil production increases, the recovery rate gradually decreases, and conventional oil recovery technology can no longer meet the needs of efficient development. Therefore, finding new and efficient oil recovery technology has become an important topic in oil field development research. In recent years, the application of nanomaterials in oil field development has gradually emerged, especially carbon quantum dots as a new type of nanomaterials, with its excellent optical and chemical properties, it has become an important direction in oil recovery agent research.

[0003] Carbon quantum dots are a type of nanomaterial with fluorescent properties, which are widely used in sensors, imaging, catalysis, drug delivery and other fields. Due to their high specific surface area, rich surface functional groups and good biocompatibility, the potential of carbon quantum dots as oil displacement agents in oilfield exploitation has received widespread attention. By functionalizing their surface, their force at the oil-water interface can be increased, thereby improving the oil recovery efficiency. Although there have been studies on oil displacement agents based on carbon quantum dots in the prior art, traditional carbon quantum dots often have the following problems: the surface functional groups are unstable, and the surface functional groups of carbon quantum dots that have not been fully modified or doped are prone to change, thereby affecting their oil recovery effect. During use, existing oil displacement agents often lack effective monitoring methods, making it difficult to monitor the fluid dynamics during the oil recovery process in real time, resulting in the inability to optimize the oil recovery strategy. Therefore, the development of carbon quantum dot oil displacement agents with strong fluorescent tracing functions and excellent oil recovery performance has become an urgent need in current technology. Summary of the invention

[0004] The object of the present invention is to provide a fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0005] In order to achieve the above-mentioned invention object, the present invention adopts the following technical scheme:

[0006] The present invention provides a fluorescent tracer nitrogen-doped carbon quantum dot oil-displacing agent, which comprises humic acid, urea, deionized water, anhydrous ethanol, hexadecyltrimethylammonium bromide and triethylamine.

[0007] The mixed solution of humic acid, urea and deionized water is referred to as carbon quantum dot solution, and the carbon quantum dot solution is prepared into carbon quantum dot particles by freeze drying.

[0008] As a preferred embodiment of the present invention, the mass ratio of humic acid, urea and deionized water is 1:(0.5-0.6):(10-20).

[0009] As a preferred embodiment of the present invention, the mass of the deionized water is 20 to 30 times the total mass of humic acid and urea.

[0010] As a preferred embodiment of the present invention, the mass ratio of the carbon quantum dot particles to anhydrous ethanol is 1:(50-80).

[0011] As a preferred embodiment of the present invention, the amount of hexadecyltrimethylammonium bromide added is 2 to 3 times the mass of the carbon quantum dot particles.

[0012] As a preferred embodiment of the present invention, the amount of triethylamine added is 1 to 1.5 times that of the carbon quantum dot particles.

[0013] The present invention also provides a method for preparing a fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent, comprising the following steps:

[0014] S1. Dissolve a certain amount of humic acid and urea in deionized water and disperse them by ultrasonic for 30 to 60 minutes. Place the mixed solution in a microwave reactor to react for 8 to 10 minutes, and then cool it to room temperature;

[0015] S2, dissolving the product obtained in S1 in deionized water, ultrasonically dispersing for 5 to 10 minutes, using a filter membrane with a pore size of 0.45 μm to remove particles with larger particle sizes, using a dialysis bag to remove small molecular impurities to obtain a carbon quantum dot solution, and then freeze-drying to obtain carbon quantum dot particles;

[0016] S3, dissolving a certain amount of carbon quantum dot particles obtained in S2 in anhydrous ethanol, and then adding a certain amount of hexadecyltrimethylammonium bromide. Under nitrogen protection, adding a certain amount of catalyst to promote the reaction, the temperature is controlled at 60-80°C, the reaction time is 4-6h, and after the reaction is completed, the anhydrous ethanol is removed by a rotary evaporator to obtain the fluorescent tracer type nitrogen-doped carbon quantum dot oil displacement agent.

[0017] As a preferred embodiment of the present invention, in S2, the molecular weight cutoff range of the dialysis bag is 3000-3500Da.

[0018] Compared with the prior art, the present invention provides a fluorescent tracer type nitrogen-doped carbon quantum dot oil-displacing agent and a preparation method thereof, which utilizes humic acid as a carbon source and urea as a nitrogen source to prepare nitrogen-doped carbon quantum dot particles by a microwave method, and then grafts hexadecyltrimethylammonium bromide onto the surface thereof to form a carbon quantum dot oil-displacing agent with a fluorescent tracer function.

[0019] One or more of the above technical solutions have the following beneficial effects:

[0020] 1. In the fluorescent tracer nitrogen-doped carbon quantum dot oil-displacing agent and its preparation method, humic acid is modified to enhance its compatibility with the oil-water phase. Nitrogen doping increases the hydrophilicity of carbon quantum dots, further improving their dispersibility and stability in the water phase, thereby improving oil recovery efficiency. Carbon quantum dot oil-displacing agents have excellent penetration ability. Due to their small particle size, oil-displacing agents can more easily penetrate into the micropores of oil reservoirs, thereby helping oil fields to improve recovery in complex environments;

[0021] 2. In the fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent and its preparation method, the carbon quantum dot oil displacement agent also has good fluorescence properties, which can be used as a tracer to monitor the fluid flow in real time during the oil displacement process, providing effective data support for oil field development. Humic acid is a type of organic substance widely present in nature, and urea is a common nitrogen source. Both are low in price and have good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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.

[0023] Figure 1 This is a particle size distribution diagram of the fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent of the present invention;

[0024] Figure 2 This is a graph showing the interfacial tension variation of the fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent prepared by the present invention at different concentrations;

[0025] Figure 3 It is a fluorescence spectrum of the fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent prepared by the present invention;

[0026] Figure 4 This is a raw material composition diagram of the fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent prepared in Example 1 of the present invention;

[0027] Figure 5 This is a raw material composition diagram of the fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent prepared in Example 2 of the present invention;

[0028] Figure 6 This is a raw material composition diagram of the fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent prepared in Example 3 of the present invention;

[0029] Figure 7 This is a raw material composition diagram of the fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent prepared in Example 4 of the present invention;

[0030] Figure 8This is a raw material composition diagram of the fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent prepared in Example 5 of the present invention;

[0031] Fig. 9 This is a raw material composition diagram of the fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent prepared in Example 6 of the present invention. DETAILED DESCRIPTION

[0032] 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.

[0033] 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.

[0034] 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).

[0035] 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.”

[0036] 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.

[0037] 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.

[0038] 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.

[0039] See also Figure 1-Figure 9 The present invention discloses a fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent, and the specific preparation steps are as follows:

[0040] S1: After a certain amount of humic acid and urea are dissolved in deionized water, ultrasonic dispersion is performed for 30 to 60 minutes. The mixed solution is placed in a microwave reactor for reaction for 8 to 10 minutes, and then cooled to room temperature. The mass ratio of humic acid, urea and deionized water is 1: (0.5 to 0.6): (10 to 20).

[0041] S2: The product obtained in S1 is dissolved in deionized water, ultrasonically dispersed for 5 to 10 minutes, a filter membrane with a pore size of 0.45 μm is used to remove particles with larger particle sizes, a dialysis bag is used to remove small molecular impurities to obtain a carbon quantum dot solution, and then freeze-dried to obtain carbon quantum dot particles. Among them, the mass of deionized water is 20 to 30 times the total mass of humic acid and urea in S1, and the molecular weight cutoff range of the dialysis bag is 3000-3500Da.

[0042] S3: Dissolve a certain amount of carbon quantum dot particles obtained in S2 in anhydrous ethanol, and then add a certain amount of hexadecyltrimethylammonium bromide. Under nitrogen protection, add a certain amount of catalyst to promote the reaction. The temperature is controlled at 60-80°C, and the reaction time is 4-6h. After the reaction is completed, the anhydrous ethanol is removed by a rotary evaporator to obtain the fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent. Among them, the mass ratio of carbon quantum dot particles to anhydrous ethanol is 1: (50-80), the amount of hexadecyltrimethylammonium bromide added is 2-3 times the mass of carbon quantum dot particles, the catalyst is triethylamine, and the amount of catalyst added is 1-1.5 times the mass of carbon quantum dot particles.

[0043] The present invention will be further described below in conjunction with specific embodiments:

[0044] Example 1, specific reference Figure 4 ,

[0045] S1: 2 g of humic acid and 1 g of urea were dissolved in 40 g of deionized water, and then ultrasonically dispersed for 30 min. The mixed solution was placed in a microwave reactor for reaction for 10 min, and then cooled to room temperature.

[0046] S2: The product obtained in S1 was dissolved in 60 g of deionized water, ultrasonically dispersed for 5 min, a filter membrane with a pore size of 0.45 μm was used to remove particles with larger particle size, and a dialysis bag with a molecular weight cutoff of 3000 Da was used to remove small molecular impurities to obtain a carbon quantum dot solution, which was then freeze-dried to obtain carbon quantum dot particles.

[0047] S3: Dissolve 1g of the carbon quantum dot particles obtained in S2 in 50g of anhydrous ethanol, and then add 2g of hexadecyltrimethylammonium bromide. Under nitrogen protection, add 1g of triethylamine to promote the reaction. The temperature is controlled at 60°C and the reaction time is 6h. After the reaction is completed, the anhydrous ethanol is removed by a rotary evaporator to obtain the fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent.

[0048] Example 2, specific reference Figure 5 ,

[0049] S1: 2 g of humic acid and 1.2 g of urea were dissolved in 20 g of deionized water, and then ultrasonically dispersed for 60 min. The mixed solution was placed in a microwave reactor for reaction for 8 min, and then cooled to room temperature.

[0050] S2: The product obtained in S1 was dissolved in 96 g of deionized water, ultrasonically dispersed for 10 min, a filter membrane with a pore size of 0.45 μm was used to remove particles with larger particle sizes, and a dialysis bag with a molecular weight cutoff of 3500 Da was used to remove small molecular impurities to obtain a carbon quantum dot solution, which was then freeze-dried to prepare carbon quantum dot particles.

[0051] S3: Dissolve 1g of the carbon quantum dot particles obtained in S2 in 80g of anhydrous ethanol, and then add 3g of hexadecyltrimethylammonium bromide. Under nitrogen protection, add 1.5g of triethylamine to promote the reaction. The temperature is controlled at 80°C and the reaction time is 4h. After the reaction is completed, the anhydrous ethanol is removed by a rotary evaporator to obtain the fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent.

[0052] Example 3, specific reference Figure 6 ,

[0053] S1: 2 g of humic acid and 1.1 g of urea were dissolved in 30 g of deionized water, and then ultrasonically dispersed for 40 min. The mixed solution was placed in a microwave reactor for reaction for 8 min, and then cooled to room temperature.

[0054] S2: The product obtained in S1 was dissolved in 80 g of deionized water, ultrasonically dispersed for 8 min, a filter membrane with a pore size of 0.45 μm was used to remove particles with larger particle size, and a dialysis bag with a molecular weight cutoff of 3500 Da was used to remove small molecular impurities to obtain a carbon quantum dot solution, which was then freeze-dried to obtain carbon quantum dot particles.

[0055] S3: Dissolve 1g of the carbon quantum dot particles obtained in S2 in 60g of anhydrous ethanol, and then add 2.4g of hexadecyltrimethylammonium bromide. Under nitrogen protection, add 1.2g of triethylamine to promote the reaction. The temperature is controlled at 80°C and the reaction time is 6h. After the reaction is completed, the anhydrous ethanol is removed by a rotary evaporator to obtain the fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent.

[0056] Example 4, specific reference 7,

[0057] S1: 2 g of humic acid and 1 g of urea were dissolved in 35 g of deionized water, and then ultrasonically dispersed for 40 min. The mixed solution was placed in a microwave reactor for reaction for 8 min, and then cooled to room temperature.

[0058] S2: The product obtained in S1 was dissolved in 70 g of deionized water, ultrasonically dispersed for 10 min, a filter membrane with a pore size of 0.45 μm was used to remove particles with larger particle sizes, and a dialysis bag with a molecular weight cutoff of 3000 Da was used to remove small molecular impurities to obtain a carbon quantum dot solution, which was then freeze-dried to prepare carbon quantum dot particles.

[0059] S3: Dissolve 1g of the carbon quantum dot particles obtained in S2 in 70g of anhydrous ethanol, and then add 2.8g of hexadecyltrimethylammonium bromide. Under nitrogen protection, add 1.3g of triethylamine to promote the reaction. The temperature is controlled at 60°C and the reaction time is 6h. After the reaction is completed, the anhydrous ethanol is removed by a rotary evaporator to obtain the fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent.

[0060] Example 5, specific reference Figure 8 ,

[0061] S1: 2 g of humic acid and 1.2 g of urea were dissolved in 30 g of deionized water, and then ultrasonically dispersed for 60 min. The mixed solution was placed in a microwave reactor for reaction for 10 min, and then cooled to room temperature.

[0062] S2: The product obtained in S1 was dissolved in 90 g of deionized water, ultrasonically dispersed for 10 min, a filter membrane with a pore size of 0.45 μm was used to remove particles with larger particle size, and a dialysis bag with a molecular weight cutoff of 3500 Da was used to remove small molecular impurities to obtain a carbon quantum dot solution, which was then freeze-dried to obtain carbon quantum dot particles.

[0063] S3: Dissolve 1g of the carbon quantum dot particles obtained in S2 in 70g of anhydrous ethanol, and then add 2.5g of hexadecyltrimethylammonium bromide. Under nitrogen protection, add 1.5g of triethylamine to promote the reaction. The temperature is controlled at 80°C and the reaction time is 4h. After the reaction is completed, the anhydrous ethanol is removed by a rotary evaporator to obtain the fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent.

[0064] Example 6, specific reference Fig. 9 ,

[0065] S1: 2 g of humic acid and 1.1 g of urea were dissolved in 35 g of deionized water, and then ultrasonically dispersed for 50 min. The mixed solution was placed in a microwave reactor for reaction for 8 min, and then cooled to room temperature.

[0066] S2: The product obtained in S1 was dissolved in 70 g of deionized water, ultrasonically dispersed for 10 min, a filter membrane with a pore size of 0.45 μm was used to remove particles with larger particle sizes, and a dialysis bag with a molecular weight cutoff of 3000 Da was used to remove small molecular impurities to obtain a carbon quantum dot solution, which was then freeze-dried to prepare carbon quantum dot particles.

[0067] S3: Dissolve 1g of the carbon quantum dot particles obtained in S2 in 60g of anhydrous ethanol, and then add 2.2g of hexadecyltrimethylammonium bromide. Under nitrogen protection, add 1.1g of triethylamine to promote the reaction. The temperature is controlled at 60°C and the reaction time is 6h. After the reaction is completed, the anhydrous ethanol is removed by a rotary evaporator to obtain the fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent.

[0068] Performance Characterization

[0069] In order to evaluate the relevant performance of the carbon quantum dot oil-displacing agent with sustained-release function, the carbon quantum dot oil-displacing agent prepared in Example 3 was prepared into a 1 mg / mL solution, and its particle size was analyzed using a nanoparticle size potentiometer. The results are as follows: Figure 1 As shown. Figure 1 It can be seen that the particle size of the nitrogen-doped carbon quantum dot oil displacement agent prepared by the present invention is within 1 to 10 nm, which is an important feature of the carbon quantum dot material. The carbon quantum dot oil displacement agent prepared in Example 3 was prepared into solutions of different concentrations, and its interfacial tension was tested using a rotating interfacial tension meter. Figure 3 It can be seen that the carbon quantum dot oil displacement agent prepared by the present invention can significantly reduce the oil-water interfacial tension and has excellent application prospects. The carbon quantum dot oil displacement agent prepared in Example 3 was prepared into a 1 mg / mL solution, and its fluorescence characteristics were tested using a fluorescence spectrometer. Figure 3 It can be seen that the optimal emission wavelength of the oil displacing agent is 510 nm, which means that the oil displacing agent has a strong fluorescence intensity at this wavelength, which helps to obtain clear tracing signals in complex oilfield environments.

[0070] 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 fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent, characterized in that: The fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent comprises humic acid, urea, deionized water, anhydrous ethanol, hexadecyltrimethylammonium bromide and triethylamine. The mixed solution of humic acid, urea and deionized water is referred to as carbon quantum dot solution, and the carbon quantum dot solution is prepared into carbon quantum dot particles by freeze drying.

2. A fluorescent tracer nitrogen-doped carbon quantum dot oil-displacing agent according to claim 1, characterized in that: The mass ratio of the humic acid, urea and deionized water is 1:(0.5-0.6):(10-20).

3. A fluorescent tracer nitrogen-doped carbon quantum dot oil-displacing agent according to claim 1, characterized in that: The mass of the deionized water is 20 to 30 times the total mass of the humic acid and urea.

4. A fluorescent tracer nitrogen-doped carbon quantum dot oil-displacing agent according to claim 1, characterized in that: The mass ratio of the carbon quantum dot particles to anhydrous ethanol is 1:(50-80).

5. A fluorescent tracer nitrogen-doped carbon quantum dot oil-displacing agent according to claim 1, characterized in that: The added amount of the hexadecyltrimethylammonium bromide is 2 to 3 times the mass of the carbon quantum dot particles.

6. A fluorescent tracer nitrogen-doped carbon quantum dot oil-displacing agent according to claim 1, characterized in that: The added amount of the triethylamine is 1 to 1.5 times that of the carbon quantum dot particles.

7. A method for preparing a fluorescent tracer nitrogen-doped carbon quantum dot oil displacement agent, characterized in that: The following steps are involved: S1. Dissolve a certain amount of humic acid and urea in deionized water and disperse them by ultrasonic for 30 to 60 minutes. Place the mixed solution in a microwave reactor for 8 to 10 minutes and then cool it to room temperature. S2, dissolving the product obtained in S1 in deionized water, ultrasonically dispersing for 5 to 10 minutes, using a filter membrane with a pore size of 0.45 μm to remove particles with larger particle sizes, using a dialysis bag to remove small molecular impurities to obtain a carbon quantum dot solution, and then freeze-drying to obtain carbon quantum dot particles; S3, dissolving a certain amount of carbon quantum dot particles obtained in S2 in anhydrous ethanol, and then adding a certain amount of hexadecyltrimethylammonium bromide. Under nitrogen protection, adding a certain amount of catalyst to promote the reaction, the temperature is controlled at 60-80°C, the reaction time is 4-6h, and after the reaction is completed, the anhydrous ethanol is removed by a rotary evaporator to obtain the fluorescent tracer type nitrogen-doped carbon quantum dot oil displacement agent.

8. The method for preparing a fluorescent tracer nitrogen-doped carbon quantum dot oil-displacing agent according to claim 7, characterized in that: In S2, the molecular weight cutoff range of the dialysis bag is 3000-3500Da.

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