A Visual Detection Method for Generating Free Radicals in Microdroplets at the Hydrocarbon-Water Interface under High Temperature and High Pressure

Abstract

The present invention belongs to the technical field of high-temperature and high-pressure free radical in-situ analysis, and provides a visualization detection method for the generation of free radicals in micro-droplets at the hydrocarbon-water interface under high temperature and high pressure. The method of the present invention comprises the following steps: preparing an aqueous solution of a free radical fluorescent indicator, loading a fused silica capillary, performing a visualization simulation experiment, and analyzing the free radical fluorescence phenomenon. Based on the temperature and pressure range of the actual formation burial conditions, through a visualization fused silica capillary thermal simulation experiment, the fluorescence phenomenon of micro-droplets at the interface between an aqueous solution of a free radical fluorescent indicator and a hydrocarbon liquid under high temperature and high pressure is observed, and the fluorescence characteristics of a laser confocal microscope are used for detection, and a method for in-situ online detection of whether free radicals are generated during the high-temperature and high-pressure process is comprehensively obtained; the problem that free radicals in micro-droplets cannot be directly detected under high temperature and high pressure is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of in-situ analysis of free radicals under high temperature and high pressure, and particularly to a visualization detection method for the generation of free radicals in micro-droplets at the hydrocarbon-water interface under high temperature and high pressure. Background Art

[0002] Compared with the bulk water in nature, water micro-droplets have different physical and chemical properties. The latest research shows that under normal temperature conditions, there is a strong electric field inside and outside the water micro-droplets, which can cause H + and OH - to gain or lose electrons to form hydrogen free radicals (H•) and hydroxyl free radicals (OH•), and further accelerate the related organic-inorganic interaction processes.

[0003] In oil and gas reservoirs, under high temperature and high pressure, water micro-droplets can also be formed at the hydrocarbon-water interface. There are significant characteristics in the stability of hydrocarbons and water and the properties of fluids under high temperature and high pressure conditions, resulting in obvious differences in the micro-droplets formed under high temperature and high pressure compared with those under normal temperature and pressure. Clarifying whether free radicals can be formed in micro-droplets under high temperature and high pressure conditions plays an important role in understanding the mechanism of organic-inorganic interaction in deep and ultra-deep reservoirs. At present, under low temperature and normal pressure conditions, by artificially creating a large number of micro-droplets, the EPR (electron paramagnetic resonance spectroscopy) technology can be used to effectively detect the generation of free radicals in micro-droplets. However, under high temperature and high pressure conditions, due to the small volume of the capillary, it is difficult to create a sufficient amount of water micro-droplets near the hydrocarbon-water interface to meet the requirements of free radical detection. Therefore, the detection of whether free radicals can be generated in micro-droplets at the hydrocarbon-water interface under high temperature and high pressure conditions remains a technical problem.

[0004] Therefore, a visualization detection method needs to be developed to facilitate the intuitive and convenient detection of the generation of free radicals in micro-droplets under high temperature and high pressure conditions. Summary of the Invention

[0005] The purpose of the present invention is to provide a visualization detection method for the generation of free radicals in micro-droplets at the hydrocarbon-water interface under high temperature and high pressure in order to overcome the deficiencies of the prior art.

[0006] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a visualization detection method for the generation of free radicals in micro-droplets at the hydrocarbon-water interface under high temperature and high pressure, comprising the following steps:

[0008] 1) Prepare an aqueous solution of a free radical fluorescent indicator: Mix the free radical fluorescent indicator powder and water and let it stand to obtain an aqueous solution of the free radical fluorescent indicator;

[0009] 2) Sampling with a fused silica capillary: Sequentially inject an aqueous solution of a radical fluorescent indicator and a hydrocarbon liquid into the reaction chamber of the fused silica capillary. After connecting the reaction chamber of the fused silica capillary to a high-pressure needle valve, set the initial pressure.

[0010] In step 2), the length of the aqueous solution of the radical fluorescent indicator is shorter than the length of the visible window of the fused silica capillary.

[0011] 3) Visualization simulation experiment: Insert the reaction chamber of the fused silica capillary after sampling into a thermostatic bath. Fix the reaction chamber of the fused silica capillary with a silver sheet, and then gradually increase the temperature and pressure in the reaction chamber of the fused silica capillary using the thermostatic bath and a constant-pressure liquid pump until micro-droplets of water are formed at the hydrocarbon-water interface.

[0012] In step 3), the visible window of the reaction chamber of the fused silica capillary is located above the temperature control plate of the thermostatic bath, and the interface between the two types of hydrocarbon-water liquids inside can be seen through the visible window.

[0013] 4) Analysis of radical fluorescence phenomenon: Use a laser confocal microscope to in-situ and online observe the fluorescence characteristics of the micro-droplets in the fused silica capillary at different temperatures and pressures, compare the differences in the fluorescence characteristics between the aqueous solution and the interface micro-droplets, and determine whether the micro-droplets can generate free radicals.

[0014] Preferably, the concentration of the aqueous solution of the radical fluorescent indicator in step 1) is 0.0008 - 0.0012 μmol / L.

[0015] Preferably, the temperature for standing in step 1) is 37 - 43 °C, and the standing time is 20 - 28 h.

[0016] Preferably, the preparation method of the reaction chamber of the fused silica capillary in step 2) is as follows:

[0017] Seal both ends of the quartz capillary, and remove the protective coating at one end to form a visible window.

[0018] Insert the quartz capillary from the end without the removed protective coating into a tapered sleeve filled with AB glue until the end protrudes from the tapered sleeve, and fix the quartz capillary with AB glue.

[0019] Cut off the end of the quartz capillary protruding from the tapered sleeve to form an opening as the sample injection end.

[0020] Before sealing, the length of the quartz capillary is 18 - 22 cm, the length of the end protruding from the tapered sleeve is 4 - 6 mm; the length of the visible window is 3.5 - 4.5 cm.

[0021] Preferably, the hydrocarbon liquid in step 2) is hexadecane.

[0022] Preferably, in step 2), the initial pressure is set by a constant-pressure liquid pump, and the initial pressure is 4.5 - 5.5 MPa.

[0023] Preferably, the specific process of loading the fused silica capillary in step 2) is as follows:

[0024] The aqueous solution of the radical fluorescent indicator is sucked into one end with a viewing window by capillary action, and the end with the viewing window is sealed with a hydrogen-oxygen welding torch.

[0025] After that, the thin capillary of the syringe filled with hydrocarbon liquid is inserted along the opening of the conical sleeve until the thin capillary reaches the interface of the aqueous solution of the radical fluorescent indicator, and then while injecting the hydrocarbon liquid, the thin capillary is withdrawn outward until there are no impurities or bubbles at the interface between the hydrocarbon liquid and the aqueous solution of the radical fluorescent indicator, and the sample loading is completed.

[0026] The contact interface between the aqueous solution of the radical fluorescent indicator and the hydrocarbon liquid can be seen in the viewing window.

[0027] Preferably, the silver sheet in step 3) is a silver sheet with a slender hollow in the middle.

[0028] The beneficial effects of the present invention include the following points:

[0029] 1) The present invention aims to clarify the spontaneous fluorescence of micro-droplets of radical fluorescent indicators under high temperature and high pressure. Based on the temperature and pressure range of the actual formation burial conditions, through the visualization of the fused silica capillary thermal simulation experiment, the fluorescence phenomenon of micro-droplets at the interface between the aqueous solution of the radical fluorescent indicator and the hydrocarbon liquid under high temperature and high pressure is observed, and the fluorescence characteristics of a laser confocal microscope are used for detection, and a method for in-situ online detection of whether radicals are generated during the high temperature and high pressure process is comprehensively obtained; the fluorescence intensity of the micro-droplets is significantly greater than that of the entire aqueous solution of the radical fluorescent indicator, indicating that radicals are generated in the micro-droplets.

[0030] 2) The present invention uses a visualization fused silica capillary thermal simulation experimental device to visually display the fluorescence phenomenon of micro-droplets at the interface between the aqueous solution of the radical fluorescent indicator and the hydrocarbon liquid under high temperature and high pressure, and uses a laser confocal microscope to verify the fluorescence characteristics, so as to comprehensively judge whether radicals are generated, and solves the problem that micro-droplet radicals cannot be directly detected under high temperature and high pressure conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a visualization detection device for the generation of radicals by micro-droplets at the hydrocarbon-water interface under high temperature and high pressure of the present invention;

[0032] Figure 2Image of the interface between the aqueous solution of the radical fluorescent indicator and hexadecane in the reaction cavity of the fused silica capillary at the initial temperature and pressure (20 °C / 5 MPa) for Example 1 under transmitted light of an optical microscope;

[0033] Figure 3 Image of the water microdroplets at the interface between the aqueous solution of the radical fluorescent indicator and hexadecane in the reaction cavity of the fused silica capillary at high temperature and high pressure (130 °C / 35 MPa) for Example 1 under transmitted light of an optical microscope;

[0034] Figure 4 Fluorescence micrograph of the water microdroplets at the interface between the aqueous solution of the radical fluorescent indicator and hexadecane in the reaction cavity of the fused silica capillary at high temperature and high pressure (130 °C / 35 MPa) for Example 1. Detailed implementation method

[0035] The present invention provides a method for visual detection of radical generation by microdroplets at the hydrocarbon-water interface under high temperature and high pressure, comprising the following steps:

[0036] 1) Prepare an aqueous solution of a radical fluorescent indicator: Mix the radical fluorescent indicator powder and water and let it stand to obtain an aqueous solution of the radical fluorescent indicator;

[0037] 2) Load the fused silica capillary: Sequentially inject the aqueous solution of the radical fluorescent indicator and the hydrocarbon liquid into the reaction cavity of the fused silica capillary, connect the reaction cavity of the fused silica capillary to a high-pressure needle valve, and set the initial pressure;

[0038] In step 2), the length of the aqueous solution of the radical fluorescent indicator is shorter than the length of the visible window of the fused silica capillary;

[0039] 3) Visual simulation experiment: Insert the loaded reaction cavity of the fused silica capillary into a thermostatic bath, fix the reaction cavity of the fused silica capillary with a silver sheet, and then gradually increase the temperature and pressure in the reaction cavity of the fused silica capillary using the thermostatic bath and a constant-pressure liquid pump until microdroplets of water are formed at the hydrocarbon-water interface;

[0040] In step 3), the visible window of the reaction cavity of the fused silica capillary is located above the temperature control plate of the thermostatic bath, and the interface between the two types of hydrocarbon-water liquids inside can be seen through the visible window;

[0041] 4) Analysis of radical fluorescence phenomenon: Use a laser confocal microscope to in-situ and online observe the fluorescence characteristics of the microdroplets in the fused silica capillary at different temperatures and pressures, compare the differences in the fluorescence characteristics between the aqueous solution and the interface microdroplets, and determine whether the microdroplets can generate radicals.

[0042] In the present invention, the device used for the method for visual detection of radical generation by microdroplets at the hydrocarbon-water interface under high temperature and high pressure is as Figure 1As shown, the device includes a high-temperature and high-pressure visualization micron quartz tube simulation system, a laser confocal microscope, and a photographing system;

[0043] The high-temperature and high-pressure visualization micron quartz tube simulation system includes a fused quartz capillary reaction chamber, a constant pressure liquid pump, a high-pressure needle valve, a digital pressure sensor, a slide rail, a heating and cooling stage, a high-pressure stainless steel tube, and a matching conical sleeve;

[0044] Seal both ends of the fused quartz capillary reaction chamber, remove the protective coating at one end to form a viewing window, insert the other end into the conical sleeve until the end protrudes, fix it with AB glue, and cut off the end of the quartz capillary protruding in the conical sleeve to form an opening;

[0045] The digital pressure sensor is set at the connection between the high-pressure needle valve and the fused quartz capillary reaction chamber, and the high-pressure needle valve is fixed on the slide rail, which is a manual precision fine-tuning handwheel slide rail (lead screw model 1204).

[0046] In the present invention, the concentration of the free radical fluorescent indicator aqueous solution in step 1) is preferably 0.0008 - 0.0012 μmol / L, more preferably 0.0009 - 0.0011 μmol / L, and even more preferably 0.001 μmol / L.

[0047] In the present invention, the free radical fluorescent indicator is preferably the free radical fluorescent indicator Peroxyfluor 1 (PF-1).

[0048] In the present invention, the temperature for standing in step 1) is preferably 37 - 43 °C, more preferably 38 - 42 °C, and even more preferably 40 °C; the standing time is preferably 20 - 28 h, more preferably 22 - 26 h, and even more preferably 24 h.

[0049] In the present invention, the standing is preferably carried out in an oven.

[0050] In the present invention, the preparation method of the fused quartz capillary reaction chamber in step 2) is preferably:

[0051] Seal both ends of the quartz capillary, and remove the protective coating at one end to form a viewing window;

[0052] Insert the quartz capillary from the end without the protective coating into the conical sleeve filled with AB glue until the end protrudes from the conical sleeve, and fix the quartz capillary with AB glue;

[0053] Cut off the end of the quartz capillary protruding in the conical sleeve to form an opening, which serves as the sample injection end;

[0054] Before welding and sealing, the length of the quartz capillary is preferably 18 - 22 cm, more preferably 19 - 21 cm, and most preferably 20 cm; the length of the end protruding from the conical sleeve is preferably 4 - 6 mm, more preferably 4.5 - 5.5 mm, and most preferably 5 mm; the length of the viewing window is preferably 3.5 - 4.5 cm, more preferably 3.7 - 4.2 cm, and most preferably 4 cm.

[0055] In the present invention, the purpose of welding and sealing the quartz capillary is to prevent AB glue from entering the interior of the quartz capillary during the fixing process.

[0056] In the present invention, the hydrocarbon liquid described in step 2) is preferably hexadecane.

[0057] In the present invention, step 2) preferably sets the initial pressure through a constant-pressure liquid pump, and the initial pressure is preferably 4.5 - 5.5 MPa, more preferably 4.8 - 5.2 MPa, and most preferably 5 MPa.

[0058] In the present invention, the specific process of loading the molten quartz capillary in step 2) is preferably as follows:

[0059] The aqueous solution of the radical fluorescent indicator is sucked into one end with a viewing window by capillary action, and the end with the viewing window is sealed with an oxy-hydrogen torch;

[0060] After that, the thin capillary of the syringe filled with the hydrocarbon liquid is inserted along the opening of the conical sleeve until the thin capillary reaches the interface of the aqueous solution of the radical fluorescent indicator, and then the hydrocarbon liquid is injected while the thin capillary is withdrawn outward until there are no impurities or bubbles at the interface of the hydrocarbon liquid and the aqueous solution of the radical fluorescent indicator, and the sample loading is completed;

[0061] The contact interface between the aqueous solution of the radical fluorescent indicator and the hydrocarbon liquid can be seen in the viewing window.

[0062] In the present invention, the silver sheet described in step 3) is preferably a silver sheet with a slender hollow in the middle.

[0063] In the present invention, the analysis of the radical fluorescence phenomenon in step 4) is to qualitatively analyze the radicals in the micro-droplets using a fluorescence micrograph. The specific method is as follows:

[0064] The laser confocal microscope is equipped with a laser scanning device on the basis of fluorescence microscope imaging. Through a two-way channel, lasers are fixed at 555 nm and 488 nm respectively. The fluorescence probe is excited by ultraviolet or visible light, and image processing is carried out using a computer to obtain a fluorescence image;

[0065] According to the temperature and pressure conditions of the actual formation depth, the temperature and pressure of the fused silica capillary reaction chamber are increased, and the change of the interface between the free radical fluorescent indicator aqueous solution and the hydrocarbon liquid is observed as the temperature and pressure increase; if micro-droplets of water appear at the interface position, the fluorescence intensity of the micro-droplets of water and the fluorescence intensity of the entire free radical fluorescent indicator aqueous solution are compared through a laser confocal microscope to determine whether the fluorescence intensity of the micro-droplets is significantly greater than the fluorescence intensity of the entire free radical fluorescent indicator aqueous solution, so as to determine whether free radicals are generated in the micro-droplets (if the fluorescence intensity of the micro-droplets is significantly greater than the fluorescence intensity of the entire free radical fluorescent indicator aqueous solution, it indicates that free radicals are generated in the micro-droplets).

[0066] The technical solutions provided by the present invention will be described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0067] The relative molecular mass of the free radical fluorescent indicator Peroxyfluor 1 (PF-1) is 552.23 g / mol.

[0068] Example 1

[0069] The visualization detection device for the generation of free radicals in micro-droplets at the hydrocarbon-water interface under high temperature and high pressure includes a high temperature and high pressure visualization micro quartz tube simulation system (HTHPOC), a laser confocal microscope and a photographing system; the high temperature and high pressure visualization micro quartz tube simulation system includes a fused silica capillary reaction chamber (FSCC), a constant pressure liquid pump, a high pressure needle valve (30-15HF4, 30000 psi), a digital pressure sensor (0~150 MPa), a slide rail, a heating and cooling stage (Linkam CAP-500, -196~500 °C, ±0.1 °C), a high pressure stainless steel tube and a matching conical sleeve; the digital pressure sensor is arranged at the connection between the high pressure needle valve and the fused silica capillary reaction chamber, the high pressure needle valve is fixed on the slide rail, and the slide rail is a manual precision fine adjustment handwheel slide rail (lead screw model 1204).

[0070] A quartz capillary with a length of 20 cm (ID 299 µm, OD 789 µm) is intercepted. One end of the intercepted quartz capillary is sealed with a hydrogen-oxygen welding torch, and the sealed end is inserted into the conical sleeve filled with AB glue until the length of the end protruding from the conical sleeve is 5 mm. Then, the quartz capillary is fixed with AB glue and placed in a drying oven at 40 °C for 24 h to dry. After the AB glue solidifies, the end of the quartz capillary protruding from the conical sleeve is cut off to form an opening. Finally, the protective coating at the non-sealed end is removed to form a visible window with a length of 4 cm.

[0071] Preparation of an Aqueous Solution of a Free Radical Fluorescent Indicator: Take 55.223 ng of the free radical fluorescent indicator Peroxyfluor 1 (PF-1) powder sample and place it in a sample bottle. Use a pipette to draw 100 mL of deionized water and inject it into the sample bottle containing the Peroxyfluor 1 (PF-1) powder sample. Cover the cap and let it stand in a drying oven at 40 °C for 24 h to prepare an aqueous solution containing 0.001 μmol / L of the free radical fluorescent indicator.

[0072] Capillary Sampling: Draw 0.14 mL of the aqueous solution of the free radical fluorescent indicator with a concentration of 0.001 μmol / L into one end with a viewing window through capillary action. Its length is shorter than the viewing window. Then, seal the end with the viewing window using a hydrogen-oxygen torch. Insert the thin capillary of the syringe filled with hexadecane liquid along the opening of the conical sleeve until the thin capillary reaches the interface of the aqueous solution of the free radical fluorescent indicator. While injecting hexadecane, slowly withdraw the thin capillary until there are no impurities or bubbles at the interface between the hexadecane liquid and the aqueous solution of the free radical fluorescent indicator. Sampling is completed. Finally, connect the fused silica capillary reaction chamber to the high-pressure needle valve, set the initial pressure to 5 MPa using a constant-pressure liquid pump, and add water for use.

[0073] Visualization of the Thermal Simulation Experiment Process: After wiping the viewing window of the fused silica capillary reaction chamber after sampling with absorbent cotton dipped in anhydrous alcohol, insert the fused silica capillary reaction chamber into the hot and cold stage, and place the viewing window section of the fused silica capillary reaction chamber (where the hydrocarbon-water two-liquid interface can be seen) above the temperature control plate of the hot and cold stage. Then, use a silver sheet with a slender hollow in the middle to fix the fused silica capillary reaction chamber to prevent it from shaking or tilting upwards. Subsequently, gradually increase the temperature and pressure in the fused silica capillary reaction chamber using the hot and cold stage and the constant-pressure liquid pump. The temperature and pressure settings of the fused silica capillary reaction chamber are shown in Table 1 until micro-droplets of water are formed at the hydrocarbon-water interface.

[0074] Table 1 Temperature and Pressure Settings of the Fused Silica Capillary Reaction Chamber

[0075]

[0076] Analysis of the Free Radical Fluorescence Phenomenon: Keep the temperature and pressure of the capillary unchanged, and use a Zeiss LSM700 laser confocal microscope to in-situ and online observe the fluorescence characteristics of the micro-droplets of water, the aqueous solution of the free radical fluorescent indicator, and hexadecane in the fused silica capillary reaction chamber using a 555 nm fixed laser and a 488 nm fixed laser respectively, and obtain fluorescence images, so as to qualitatively analyze the free radicals in the micro-droplets of water, compare the fluorescence characteristic differences between the aqueous solution and the micro-droplets of water at the interface, and further verify whether free radicals are generated inside the micro-droplets.

[0077] The image of the interface between the aqueous solution of the radical fluorescent indicator and hexadecane in the reaction cavity of the fused silica capillary under the transmitted light of an optical microscope at the initial temperature and pressure (20°C / 5 MPa) in this embodiment is as follows Figure 2 shown. It can be seen from Figure 2 that when the fused silica capillary is under the initial temperature and pressure conditions of 20°C / 5 MPa, no micro-droplets of water are formed at the interface between the aqueous solution of the radical fluorescent indicator and hexadecane.

[0078] The image of the micro-droplets of water at the interface between the aqueous solution of the radical fluorescent indicator and hexadecane in the reaction cavity of the fused silica capillary under the transmitted light of an optical microscope at high temperature and high pressure (130°C / 35 MPa) in this embodiment is as follows Figure 3 shown. It can be seen from Figure 3 that when the temperature and pressure rise to 130°C / 35 MPa, the interface between the aqueous solution of the radical fluorescent indicator and hexadecane begins to change, and micro-droplets of water are formed near the interface in hexadecane.

[0079] The fluorescence micrograph of the micro-droplets of water at the interface between the aqueous solution of the radical fluorescent indicator and hexadecane in the reaction cavity of the fused silica capillary at high temperature and high pressure (130°C / 35 MPa) in this embodiment is as follows Figure 4 shown. It can be seen from Figure 4 that at 130°C / 35 MPa, micro-droplets of water are formed near the interface in hexadecane. At the same time, it is observed that the generated micro-droplets of water have extremely strong fluorescence compared with the whole section of the aqueous solution of the radical fluorescent indicator, indicating that free radicals are generated and detected by the radical fluorescent indicator inside the micro-droplets of water at this time.

[0080] Example 2

[0081] Change the mass of the radical fluorescent indicator. The concentration of the aqueous solution of the radical fluorescent indicator is 0.0009 μmol / L. The temperature for the sample bottle to stand still is 38°C, the time is 26 h, the length of the end of the quartz capillary protruding from the conical sleeve is 4.5 mm, and the length of the visible window of the quartz capillary is 3.7 cm. Other conditions are the same as those in Example 1.

[0082] In this embodiment, when the fused silica capillary is at 130°C / 35 MPa, micro-droplets of water are formed near the interface in hexadecane. At the same time, it is observed that the micro-droplets of water have extremely strong fluorescence compared with the whole section of the aqueous solution of the radical fluorescent indicator, indicating that free radicals are generated and detected by the radical fluorescent indicator inside the micro-droplets of water at this time.

[0083] Example 3

[0084] Change the mass of the free radical fluorescent indicator. The concentration of the free radical fluorescent indicator aqueous solution is 0.00011 μmol / L. The temperature at which the sample bottle is static is 42 °C, and the time is 22 h. The length of the quartz capillary tube end protruding from the conical sleeve is 5.5 mm, and the length of the quartz capillary visual window is 4.2 cm. Other conditions are the same as those in Example 1.

[0085] In this example, when the fused silica capillary is at 130 °C / 35 MPa, micro-droplets of water are formed near the interface of hexadecane. At the same time, it is observed that the micro-droplets of water have extremely strong fluorescence compared with the whole free radical fluorescent indicator aqueous solution, indicating that free radicals are generated inside the micro-droplets of water detected by the free radical fluorescent indicator at this time.

[0086] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A visual detection method for free radical generation from microdroplets at a hydrocarbon-water interface under high temperature and high pressure, characterized in that: The following steps are included: 1) Prepare a free radical fluorescent indicator aqueous solution: mix the free radical fluorescent indicator powder and water and let it stand to obtain a free radical fluorescent indicator aqueous solution; 2) Fused silica capillary sample loading: Inject the free radical fluorescence indicator aqueous solution and hydrocarbon liquid into the fused silica capillary reaction chamber in sequence, connect the fused silica capillary reaction chamber to the high-pressure needle valve and set the initial pressure; Step 2) the length of the free radical fluorescent indicator aqueous solution is shorter than the length of the visible window of the fused silica capillary; 3) Visual simulation experiment: insert the loaded fused silica capillary reaction chamber into the hot and cold stage, fix the fused silica capillary reaction chamber with a silver sheet, and then use the hot and cold stage and constant pressure liquid pump to gradually increase the temperature and pressure in the fused silica capillary reaction chamber until water droplets are formed at the hydrocarbon-water interface; In step 3), the visual window of the fused silica capillary reaction chamber is located above the temperature control plate of the hot and cold stage, and the hydrocarbon-water liquid interface inside can be seen through the visual window; 4) Analysis of free radical fluorescence phenomenon: Use laser confocal microscopy to observe the fluorescence characteristics of microdroplets in fused silica capillaries at different temperatures and pressures in situ, compare the differences in fluorescence characteristics of aqueous solution and interface microdroplets, and determine whether microdroplets can generate free radicals.

2. The visual detection method for free radical generation by micro-droplets at hydrocarbon-water interface under high temperature and high pressure according to claim 1, characterized in that: Step 1) The concentration of the free radical fluorescent indicator aqueous solution is 0.0008-0.0012 μmol / L.

3. The visual detection method for free radical generation by micro-droplets at hydrocarbon-water interface under high temperature and high pressure according to claim 1 or 2, characterized in that: Step 1) The standing temperature is 37-43° C. and the standing time is 20-28 hours.

4. The visual detection method for free radical generation by micro-droplets at hydrocarbon-water interface under high temperature and high pressure according to claim 3, characterized in that: Step 2) The preparation method of the fused silica capillary reaction chamber is: The two ends of the quartz capillary are welded and sealed, and the protective coating on one end is removed to form a visual window; Insert the end of the capillary tube that has not been protected by the protective coating into the tapered sleeve filled with AB glue until the end protrudes out of the tapered sleeve, and fix the quartz capillary tube with AB glue; The end of the quartz capillary extending from the tapered sleeve is cut off to form an opening serving as a sample injection end; The length of the quartz capillary before welding is 18~22cm, the length of the end extending out of the tapered sleeve is 4~6mm; the length of the viewing window is 3.5~4.5cm.

5. The visual detection method for free radical generation by micro-droplets at hydrocarbon-water interface under high temperature and high pressure according to claim 1 or 4, characterized in that: Step 2) The hydrocarbon liquid is hexadecane.

6. The visual detection method for free radical generation by micro-droplets at hydrocarbon-water interface under high temperature and high pressure according to claim 5, characterized in that: Step 2) Set the initial pressure using a constant pressure liquid pump. The initial pressure is 4.5~5.5MPa.

7. The visual detection method for free radical generation by micro-droplets at hydrocarbon-water interface under high temperature and high pressure according to claim 1 or 6, characterized in that: Step 2) The specific process of loading the sample into the fused silica capillary is: A free radical fluorescent indicator aqueous solution is sucked into the end with the visual window through capillary action, and the end with the visual window is sealed with a hydrogen-oxygen welding torch; Then, a capillary tube containing a hydrocarbon liquid syringe is inserted along the opening of the tapered sleeve until the capillary tube reaches the interface of the free radical fluorescent indicator aqueous solution, and then the capillary tube is drawn outward while the hydrocarbon liquid is injected until there is no impurity or bubble at the interface between the hydrocarbon liquid and the free radical fluorescent indicator aqueous solution, and the sample loading is completed; The contact interface between the free radical fluorescent indicator aqueous solution and the hydrocarbon liquid can be seen in the viewing window.

8. The visual detection method for free radical generation by micro-droplets at hydrocarbon-water interface under high temperature and high pressure according to claim 7, characterized in that: Step 3) The silver sheet is a thin and hollow silver sheet in the middle.

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