Preparation method of silicon-based quantum dot tracer

Abstract

The invention discloses a preparation method of a silicon-based quantum dot tracer. The silicon-based quantum dot tracer agent disclosed by the invention is prepared by taking 3-aminopropyltrimethoxysilane, sodium citrate, urea and deionized water as raw materials and adopting a hydrothermal synthesis method. The silicon-based quantum dot tracer agent is synthesized by using 3-aminopropyltrimethoxysilane as a silicon source and using the synergistic effect of double reducing agents of sodium citrate and urea, the synthesized silicon-based quantum dot tracer agent can overcome the influence of temperature and environment on the silicon-based quantum dot tracer agent, the fluorescence lifetime is prolonged, and the silicon-based quantum dot tracer agent has a relatively small particle size and can be used for preparing the quantum dot tracer agent. And inter-well tracer testing and single-well chemical testing technology research of an on-site oil field are facilitated.

Description

Technical Field

[0001] The invention relates to the field of horizontal well drilling and development devices, and in particular to a method for preparing a silicon-based quantum dot tracer. Background Art

[0002] At present, most of the domestic oil fields in my country have entered the middle and late stages of development. The comprehensive water content of the oil fields has increased year by year, and the difficulty of increasing and stabilizing production has gradually increased. The development of unconventional oil and gas resources with large geological reserves is still in the development stage and cannot completely replace conventional oil and gas resources. Therefore, how to efficiently develop oil and gas resources has become one of the most important issues in the industry. Since the water content of most oil fields is relatively high, and the annual comprehensive water content of some oil fields has reached more than 80%, long-term water injection development will cause the flow channels to become larger due to erosion, and the flow channels between injection and production wells tend to transform into large-pore channels, resulting in uneven production profiles of production wells, thereby reducing crude oil recovery. In order to improve the interlayer relationship, prevent and inhibit the intrusion of injected water and the ridge advance of edge and bottom water, and improve the ultimate recovery of the reservoir, it is often necessary to adopt comprehensive management measures such as injection well profile adjustment, oil well water plugging, periodic water injection, deep flow diversion, and AICD intelligent water control for the oil field. However, these production-increasing measures are costly and difficult to operate. To achieve the desired effect, it is also necessary to have a correct and clear understanding of the basic reservoir information of the reservoir. At present, the types of monitoring in the development of oil and gas fields are divided into oil well production monitoring and reservoir monitoring. Among them, production monitoring mainly monitors the permeability, porosity, oil layer thickness, fracturing effect, horizontal well production profile, horizontal section water production identification and other information of the near-well reservoir through production logging methods; reservoir monitoring usually monitors the lithology, physical properties, properties of fluids in pores, determination of active layers, non-active layers, residual oil distribution, fluid interface, inter-well connectivity, etc. of the formation in the target reservoir. There is an urgent need for a low-cost, high-efficiency method that can quantitatively describe the movement state of the fluid and intuitively understand the reservoir characteristics between injection and production wells. Summary of the invention

[0003] In view of the above problems, the present invention provides a method for preparing a silicon-based quantum dot tracer.

[0004] The invention provides a method for preparing a silicon-based quantum dot tracer, which uses 3-aminopropyltrimethoxysilane, sodium citrate, urea and deionized water as raw materials and adopts a hydrothermal synthesis method to prepare the silicon-based quantum dot tracer. The particle size of the silicon-based quantum dot tracer is 7-10 nm.

[0005] The present invention provides a method for preparing a silicon-based quantum dot tracer, comprising the following steps:

[0006] S1: Take a certain amount of sodium citrate and put it into deionized water and stir;

[0007] S2: adding 3-aminopropyltrimethoxysilane to the solution of sodium citrate and deionized water and continuing to stir;

[0008] S3: adding urea to the solution containing 3-aminopropyltrimethoxysilane, sodium citrate and deionized water and continuing to stir;

[0009] S4: placing a solution containing 3-aminopropyltrimethoxysilane, urea, sodium citrate and deionized water into a high-temperature reactor for hydrothermal reaction;

[0010] S5: transferring the reacted solution into a dialysis bag for dialysis;

[0011] S6: Finally, the dialyzed solution is dried to obtain a silicon-based quantum dot tracer.

[0012] In the step of taking a certain amount of sodium citrate and putting it into deionized water and stirring it in the method for preparing the silicon-based quantum dot tracer, 1.85 g of sodium citrate is weighed and put into 15 ml of deionized water and stirred.

[0013] In the step of adding 3-aminopropyltrimethoxysilane to a solution of sodium citrate and deionized water and continuing to stir in the preparation method of the silicon-based quantum dot tracer, 4 ml of 3-aminopropyltrimethoxysilane is added to the solution of sodium citrate and deionized water and continued to stir for 30 minutes.

[0014] In the step of adding urea to a solution containing 3-aminopropyltrimethoxysilane, sodium citrate and deionized water and continuing to stir in the preparation method of a silicon-based quantum dot tracer, 0.75 g of urea is added to the solution containing 3-aminopropyltrimethoxysilane, sodium citrate and deionized water and continued to stir for 30 minutes.

[0015] In the preparation method of the silicon-based quantum dot tracer, a solution containing 3-aminopropyltrimethoxysilane, urea, sodium citrate and deionized water is placed in a high-temperature reactor for hydrothermal reaction. The hydrothermal reaction temperature is 150° C. and the reaction time is 5 hours.

[0016] In the preparation method of the silicon-based quantum dot tracer, the solution after the reaction is transferred to a dialysis bag for a dialysis step, the molecular weight cutoff of the dialysis bag is 1000mD, and the dialysis time is 8-10h.

[0017] In the preparation method of the silicon-based quantum dot tracer, the dialyzed solution is finally dried. In the step of obtaining the silicon-based quantum dot tracer, the dialyzed solution is placed in a drying oven at 70-80° C. for drying to finally obtain the silicon-based quantum dot tracer.

[0018] The present invention has the following beneficial effects compared with the prior art:

[0019] 1. The silicon-based quantum dot tracer of the present invention is highly environmentally friendly, mainly composed of silicon elements, and is not doped with metal elements; the silicon-based quantum dot tracer of the present invention has a small particle size and good fluidity; the fluorescence performance of the silicon-based quantum dot tracer of the present invention is relatively stable.

[0020] 2. The preparation method of the silicon-based quantum dot tracer of the present invention has a simple synthesis process and low synthesis cost, is conducive to the use of on-site oil fields, and can meet the needs of refined monitoring of water production in multi-layer sections. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art description are briefly introduced below. Obviously, the drawings described below are only drawings required for use in some embodiments of the present invention or the prior art description. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work, and they all belong to the protection scope of the present invention.

[0022] Figure 1 This is a flow chart of a method for preparing a silicon-based quantum dot tracer according to an embodiment of the present invention;

[0023] Figure 2 The fluorescence spectra of the silicon-based quantum dot tracer described in the embodiment of the present invention under excitation at different wavelengths;

[0024] Figure 3 The fluorescence spectrum of the silicon-based quantum dot tracer described in the embodiment of the present invention under the excitation wavelength of 380nm;

[0025] Figure 4 is the fluorescence intensity of the silicon-based quantum dot tracer described in the embodiment of the present invention after irradiation with 360nm ultraviolet light;

[0026] Figure 5 is the fluorescence intensity of calcium chloride at different concentrations of the silicon-based quantum dot tracer described in the embodiment of the present invention; DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The silicon-based quantum dot tracer of the invention is prepared by a hydrothermal synthesis method using 3-aminopropyltrimethoxysilane, sodium citrate, urea and deionized water as raw materials.

[0029] The present invention provides a method for preparing a silicon-based quantum dot tracer, comprising the following steps:

[0030] S1: Take a certain amount of sodium citrate and put it into deionized water and stir;

[0031] S2: adding 3-aminopropyltrimethoxysilane to the solution of sodium citrate and deionized water and continuing to stir;

[0032] S3: adding urea to the solution containing 3-aminopropyltrimethoxysilane, sodium citrate and deionized water and continuing to stir;

[0033] S4: placing a solution containing 3-aminopropyltrimethoxysilane, urea, sodium citrate and deionized water into a high-temperature reactor for hydrothermal reaction;

[0034] S5: transferring the reacted solution into a dialysis bag for dialysis;

[0035] S6: Finally, the dialyzed solution is dried to obtain a silicon-based quantum dot tracer.

[0036] The specific preparation method is as follows (the preparation flow chart is as follows Figure 1 shown):

[0037] 1.85 g of sodium citrate was weighed and put into 15 ml of deionized water and stirred, and then 4 ml of 3-aminopropyltrimethoxysilane was added to the mixed solution of sodium citrate and deionized water, and the stirring was continued for 30 minutes. 0.75 g of urea was added to the solution containing 3-aminopropyltrimethoxysilane, sodium citrate and deionized water, and the stirring was continued for 30 minutes. The solution containing 3-aminopropyltrimethoxysilane, urea, sodium citrate and deionized water was put into a high-temperature reactor for hydrothermal reaction, the hydrothermal reaction temperature was 150° C., and the reaction time was 5 hours. After the reaction was completed, the solution after the reaction was transferred to a dialysis bag for dialysis, the molecular weight cutoff of the dialysis bag was 1000 mD, and the dialysis time was 8-10 hours. Finally, the dialyzed solution was placed in a drying oven at 70-80° C. for drying to obtain a silicon-based quantum dot tracer.

[0038] Figure 2 The fluorescence spectra of silicon-based quantum dot tracers under different wavelengths of excitation are shown in the figure. As can be seen from the figure, when the excitation wavelength increases from 350nm to 400nm, the emission wavelength hardly changes, indicating that the particle size distribution of silicon-based quantum dot tracers is relatively uniform; the fluorescence intensity increases first and then decreases, and the fluorescence is strongest when excited at a wavelength of 380nm, indicating that the maximum excitation wavelength is 370nm.

[0039] Figure 3The fluorescence spectrum of the silicon-based quantum dot tracer under 380nm wavelength excitation. As can be seen from the figure, when excited at 380nm wavelength, the maximum emission wavelength is 510nm, indicating that the synthesized silicon-based quantum dots have a strong fluorescence intensity.

[0040] Figure 4 is the fluorescence intensity of the silicon-based quantum dot tracer after irradiation with 360nm ultraviolet light. In order to better detect the stability of the silicon-based quantum dot tracer, the embodiment of the present invention uses 360nm ultraviolet light to continuously irradiate the silicon-based quantum dot tracer aqueous solution. After irradiation for 1min / 5min / 10min / 30min / 60min respectively, the fluorescence spectrum is measured with a fluorescence spectrometer and the fluorescence intensity value is recorded. Figure 4 It can be seen that the fluorescence intensity of the silicon-based quantum dot tracer has almost no change during the observation time, indicating that the prepared silicon-based quantum dot tracer has good photostability.

[0041] Figure 5 The fluorescence intensity of silicon-based quantum dots containing different concentrations of calcium chloride. In order to better detect the salt stability of the silicon-based quantum dot tracer, 300 μl of 0.05M, 0.1M, 0.25M, 0.5M, 0.1M, and 1.5M calcium chloride aqueous solutions were added to the aqueous solution, mixed evenly, and the fluorescence intensity value was recorded using a fluorescence spectrometer. As can be seen from the figure, the fluorescence intensity value of the silicon-based quantum dot tracer has hardly changed, which shows that calcium chloride does not affect the fluorescence performance of the silicon-based quantum dot tracer, indicating that the synthesized silicon-based quantum dot tracer has good salt stability and still has good fluorescence performance under high salt ion concentration conditions.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a silicon-based quantum dot tracer, characterized in that: The silicon-based quantum dot tracer is prepared by a hydrothermal synthesis method using 3-aminopropyltrimethoxysilane, sodium citrate, urea and deionized water as raw materials.

2. The method for preparing a silicon-based quantum dot tracer according to claim 1, characterized in that: The particle size of the silicon-based quantum dot tracer is 7-10 nm.

3. The method for preparing a silicon-based quantum dot tracer according to claim 1, characterized in that: The following steps are involved: S1: Take a certain amount of sodium citrate and put it into deionized water and stir; S2: adding 3-aminopropyltrimethoxysilane to the solution of sodium citrate and deionized water and continuing to stir; S3: adding urea to the solution containing 3-aminopropyltrimethoxysilane, sodium citrate and deionized water and continuing to stir; S4: placing a solution containing 3-aminopropyltrimethoxysilane, urea, sodium citrate and deionized water into a high-temperature reactor for hydrothermal reaction; S5: transferring the reacted solution into a dialysis bag for dialysis; S6: Finally, the dialyzed solution is dried to obtain a silicon-based quantum dot tracer.

4. The method for preparing a silicon-based quantum dot tracer according to claim 3, characterized in that: In the step of taking a certain amount of sodium citrate and putting it into deionized water and stirring, 1.85 g of sodium citrate is weighed and put into 15 ml of deionized water and stirred.

5. The method for preparing a silicon-based quantum dot tracer according to claim 3, characterized in that: In the step of adding 3-aminopropyltrimethoxysilane to the mixed solution of sodium citrate and deionized water and continuing to stir, 4 ml of 3-aminopropyltrimethoxysilane is added to the mixed solution of sodium citrate and deionized water and continued to stir for 30 minutes.

6. The method for preparing a silicon-based quantum dot tracer according to claim 3, characterized in that: In the step of adding urea to the solution containing 3-aminopropyltrimethoxysilane, sodium citrate and deionized water and continuing to stir, 0.75 g of urea is added to the solution containing 3-aminopropyltrimethoxysilane, sodium citrate and deionized water and continued to stir for 30 minutes.

7. The method for preparing a silicon-based quantum dot tracer according to claim 3, characterized in that: In the step of placing a solution containing 3-aminopropyltrimethoxysilane, urea, sodium citrate and deionized water into a high-temperature reactor for hydrothermal reaction, the hydrothermal reaction temperature is 150° C. and the reaction time is 5 hours.

8. The method for preparing a silicon-based quantum dot tracer according to claim 3, characterized in that: In the step of transferring the reacted solution to a dialysis bag for dialysis, the molecular weight cutoff of the dialysis bag is 1000 mD and the dialysis time is 8-10 hours.

9. The method for preparing a silicon-based quantum dot tracer according to claim 3, characterized in that: In the step of finally drying the dialyzed solution to obtain the silicon-based quantum dot tracer, the dialyzed solution is placed in a drying oven at 70-80° C. for drying to finally obtain the silicon-based quantum dot tracer.

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