Visual detection method for free radicals generated by hydrocarbon-water interface micro-droplets at high temperature and high pressure

Abstract

The invention belongs to the technical field of high-temperature and high-pressure free radical in-situ analysis, and provides a visual detection method for free radicals generated by hydrocarbon-water interface micro-droplets at high temperature and high pressure. The method comprises the following steps: preparation of a free radical fluorescence indicator aqueous solution, sample loading of a fused quartz capillary tube, visual simulation experiment and free radical fluorescence phenomenon analysis. On the basis of the temperature and pressure range of the actual stratum burying condition, the micro-droplet fluorescence phenomenon of the free radical fluorescence indicator water solution and the hydrocarbon liquid interface under the high-temperature and high-pressure conditions is observed through a visual fused quartz capillary thermal simulation experiment, and the fluorescence characteristics of a laser confocal microscope are used for detection. Comprehensively obtaining a method for in-situ online detection of generation of free radicals in the high-temperature and high-pressure process; the problem that micro-droplet free radicals cannot be directly detected under high-temperature and high-pressure conditions is solved.

Description

Technical Field

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

[0002] Compared with the bulk water in nature, water 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 droplets, which can make the H + and OH - Gaining or losing electrons forms hydrogen radicals (H•) and hydroxyl radicals (OH•), and further accelerates related organic-inorganic reaction processes.

[0003] In oil and gas reservoirs, water droplets can also be formed at the hydrocarbon-water interface under high temperature and high pressure. There are significant characteristics in the stability of hydrocarbons and water under high temperature and high pressure conditions and the properties of the fluid, which leads to the fact that the droplets formed under high temperature and high pressure conditions are significantly different from those under normal temperature and pressure. Clarifying whether droplets can form free radicals under high temperature and high pressure conditions is important for understanding the mechanism of deep and ultra-deep organic-inorganic interactions. At present, under low temperature and normal pressure conditions, by artificially producing a large number of droplets, the EPR (electron paramagnetic resonance spectroscopy) technology can be used to effectively detect the generation of free radicals in droplets. However, under high temperature and high pressure conditions, due to the small volume of the capillary, it is difficult to produce enough water droplets near the hydrocarbon-water interface to meet the needs of free radical detection. Therefore, the detection of whether droplets at the hydrocarbon-water interface under high temperature and high pressure conditions can generate free radicals is still a technical problem.

[0004] Therefore, it is necessary to develop a visual detection method that can intuitively and conveniently detect the generation of microdroplet free radicals under high temperature and high pressure conditions. Summary of the invention

[0005] The purpose of the present invention is to provide a visual detection method for free radical generation by micro-droplets at a 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 object of the invention, the present invention provides the following technical solutions: The present invention provides a visual detection method for free radical generation by micro-droplets at a hydrocarbon-water interface under high temperature and high pressure, comprising the following steps: 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.

[0007] Preferably, the concentration of the free radical fluorescent indicator aqueous solution in step 1) is 0.0008-0.0012 μmol / L.

[0008] Preferably, in step 1), the standing temperature is 37-43° C., and the standing time is 20-28 h.

[0009] Preferably, the preparation method of the fused silica capillary reaction chamber in step 2) is: The two ends of the quartz capillary are sealed by welding, 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.

[0010] Preferably, the hydrocarbon liquid in step 2) is hexadecane.

[0011] Preferably, in step 2), an initial pressure is set by a constant pressure liquid pump, and the initial pressure is 4.5-5.5 MPa.

[0012] Preferably, the specific process of loading the sample in the fused silica capillary in step 2) is: The 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.

[0013] Preferably, the silver sheet in step 3) is a slender hollow silver sheet in the middle.

[0014] The beneficial effects of the present invention include the following: 1) The present invention aims to clarify the spontaneous fluorescence of free radical fluorescent indicator microdroplets under high temperature and pressure. Based on the temperature and pressure range of actual stratum burial conditions, the present invention observes the fluorescence phenomenon of microdroplets at the interface between free radical fluorescent indicator aqueous solution and hydrocarbon liquid under high temperature and high pressure conditions through a visualized fused silica capillary thermal simulation experiment, and uses the fluorescence characteristics of a laser confocal microscope for detection. A method for in-situ online detection of whether free radicals are generated during high temperature and high pressure is comprehensively obtained. The fluorescence intensity of the microdroplets is significantly greater than the fluorescence intensity of the entire free radical fluorescent indicator aqueous solution, indicating that free radicals are generated in the microdroplets.

[0015] 2) The present invention uses a visualized fused silica capillary thermal simulation experimental device to intuitively display the micro-droplet fluorescence phenomenon at the interface of the free radical fluorescence indicator aqueous solution and the hydrocarbon liquid under high temperature and high pressure conditions, and uses a laser confocal microscope to verify the fluorescence characteristics, so as to comprehensively judge whether free radicals are generated, thereby solving the problem that micro-droplet free radicals cannot be directly detected under high temperature and high pressure conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The visual detection device for free radical generation by hydrocarbon-water interface micro-droplets under high temperature and high pressure of the present invention; Figure 2 This is an image of the interface between the free radical fluorescent indicator aqueous solution and hexadecane in the fused silica capillary reaction chamber under the initial temperature and pressure (20°C / 5MPa) of Example 1 under the optical microscope transmission light state; Figure 3 This is an image of a water microdroplet at the interface between a free radical fluorescent indicator aqueous solution and hexadecane in a fused silica capillary reaction chamber under high temperature and high pressure (130°C / 35MPa) in Example 1 under an optical microscope transmitted light state; Figure 4 This is a fluorescence micrograph of water droplets at the interface between the free radical fluorescent indicator aqueous solution and hexadecane in the fused silica capillary reaction chamber under high temperature and high pressure (130°C / 35MPa) in Example 1. DETAILED DESCRIPTION

[0017] The present invention provides a visual detection method for free radical generation by micro-droplets at a hydrocarbon-water interface under high temperature and high pressure, comprising the following steps: 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.

[0018] In the present invention, the apparatus used in the method for visualizing the generation of free radicals by microdroplets at the hydrocarbon-water interface under high temperature and high pressure is as follows: Figure 1 As shown, the device includes a high temperature and high pressure visualization micron quartz tube simulation system, a laser confocal microscope and a photography system; The high-temperature and high-pressure visualized 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 hot and cold stage, a high-pressure stainless steel tube and a matching tapered sleeve; The two ends of the fused silica capillary reaction chamber are welded and sealed, the protective coating on one end is removed to form a visual window, the other end is inserted into the tapered sleeve until the end is extended, and AB glue is used to fix it, and the end of the quartz capillary extending from the tapered sleeve is cut off to form an opening; 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 a slide rail, which is a manual precision fine-tuning handwheel slide rail (screw model 1204).

[0019] In the present invention, the concentration of the free radical fluorescent indicator aqueous solution in step 1) is preferably 0.0008 to 0.0012 μmol / L, more preferably 0.0009 to 0.0011 μmol / L, and more preferably 0.001 μmol / L.

[0020] In the present invention, the free radical fluorescent indicator is preferably the free radical fluorescent indicator Peroxyfluor 1 (PF-1).

[0021] In the present invention, the standing temperature in step 1) is preferably 37-43° C., more preferably 38-42° C., and more preferably 40° C.; the standing time is preferably 20-28 h, more preferably 22-26 h, and more preferably 24 h.

[0022] In the present invention, the standing is preferably performed in a drying oven.

[0023] In the present invention, the method for preparing the fused silica capillary reaction chamber in step 2) is preferably: The two ends of the quartz capillary are sealed by welding, 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 preferably 18~22cm, more preferably 19~21cm, and more preferably 20cm; the length of the end extending out of the tapered sleeve is preferably 4~6mm, more preferably 4.5~5.5mm, and more preferably 5mm; the length of the visual window is preferably 3.5~4.5cm, more preferably 3.7~4.2cm, and more preferably 4cm.

[0024] In the present invention, the purpose of welding and sealing the quartz capillary is to prevent the AB glue from entering the interior of the quartz capillary during the fixing process.

[0025] In the present invention, the hydrocarbon liquid in step 2) is preferably hexadecane.

[0026] In the present invention, in step 2), the initial pressure is preferably set by a constant pressure liquid pump, and the initial pressure is preferably 4.5-5.5 MPa, more preferably 4.8-5.2 MPa, and more preferably 5 MPa.

[0027] In the present invention, the specific process of loading the sample in the fused silica capillary in step 2) is preferably: The 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.

[0028] In the present invention, the silver sheet in step 3) is preferably a silver sheet with an elongated hollow middle portion.

[0029] In the present invention, step 4) free radical fluorescence phenomenon analysis is to use fluorescence microscopy to perform qualitative analysis on micro-droplet free radicals, and the specific method is: Laser confocal microscope is equipped with laser scanning device on the basis of fluorescence microscope imaging. Through two-way channels, 555nm and 488nm lasers are fixed respectively, ultraviolet or visible light is used to excite fluorescent probes, and computer is used for image processing to obtain fluorescence images. According to the temperature and pressure conditions at the actual formation depth, the temperature and pressure of the fused silica capillary reaction chamber are increased to observe the changes in the interface between the free radical fluorescence indicator aqueous solution and the hydrocarbon liquid as the temperature and pressure increase; if water droplets appear at the interface, the fluorescence intensity of the water droplets is compared with the fluorescence intensity of the entire free radical fluorescence indicator aqueous solution through a laser confocal microscope to determine whether the fluorescence intensity of the microdroplets is significantly greater than the fluorescence intensity of the entire free radical fluorescence indicator aqueous solution, thereby determining whether free radicals are generated in the microdroplets (if the fluorescence intensity of the microdroplets is significantly greater than the fluorescence intensity of the entire free radical fluorescence indicator aqueous solution, it indicates that free radicals are generated in the microdroplets).

[0030] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0031] The relative molecular mass of free radical fluorescence indicator Peroxyfluor 1 (PF-1) is 552.23 g / mol.

[0032] Example 1

[0033] The visualization detection device for free radical generation from micro-droplets at the hydrocarbon-water interface under high temperature and high pressure includes a high temperature and high pressure visualization micron quartz tube simulation system (HTHPOC), a laser confocal microscope and a camera system; the high temperature and high pressure visualization micron quartz tube simulation system includes a fused silica capillary reaction chamber (FSCC), a constant pressure liquid pump, a high pressure needle valve (30-15HF4, 30000psi), a digital pressure sensor (0~150MPa), a slide rail, a hot and cold stage (LinkamCAP-500, -196~500℃, ±0.1℃), a high pressure stainless steel pipe and a matching tapered 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-tuning handwheel slide rail (screw model 1204).

[0034] A quartz capillary (ID299µm, OD789µm) with a length of 20cm was cut, one end of the cut quartz capillary was sealed with a oxyhydrogen welding gun, and the sealed end was inserted into a conical sleeve filled with AB glue until the end protruded from the conical sleeve by 5mm. Then, the quartz capillary was fixed with AB glue and placed in a drying oven at 40℃ for 24h to dry. After the AB glue solidified, the end of the quartz capillary protruding from the conical sleeve was cut off to form an opening. Finally, the protective coating on the unsealed end was removed to form a visual window with a length of 4cm.

[0035] Prepare the free radical fluorescent indicator aqueous solution: 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 with the Peroxyfluor 1 (PF-1) powder sample. Cover the bottle with a seal and place it in a drying oven at 40°C for 24 hours to prepare a 0.001 μmol / L aqueous solution containing the free radical fluorescent indicator.

[0036] Capillary sampling: 0.14 mL of a free radical fluorescent indicator aqueous solution with a concentration of 0.001 μmol / L is sucked into one end with a visual window through capillary action, and its length is shorter than the visual window. Then, the end with the visual window is sealed with a hydrogen-oxygen welding gun. A thin capillary equipped with a syringe of hexadecane liquid is inserted along the opening of the tapered sleeve until the thin capillary reaches the interface of the free radical fluorescent indicator aqueous solution. While injecting hexadecane, the thin capillary is drawn outward until there is no impurity or bubble at the interface between the hexadecane liquid and the free radical fluorescent indicator aqueous solution. The sampling is completed. Finally, the fused quartz capillary reaction chamber is connected to the high-pressure needle valve, and the initial pressure is set to 5 MPa by a constant pressure liquid pump and water is added for standby use.

[0037] Visualized thermal simulation experiment process: After wiping the visible window of the fused silica capillary reaction chamber after sample loading with absorbent cotton dipped in anhydrous alcohol, the fused silica capillary reaction chamber is inserted into the hot and cold stage, and the visible window section of the fused silica capillary reaction chamber (the visible window section can see the hydrocarbon-water liquid interface) is placed above the temperature control plate of the hot and cold stage, and then the fused silica capillary reaction chamber is fixed with a slender hollow silver sheet in the middle to prevent it from shaking or warping; then the temperature and pressure in the fused silica capillary reaction chamber are gradually increased by 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 water droplets are formed at the hydrocarbon-water interface.

[0038] Table 1 Temperature and pressure settings of the fused silica capillary reaction chamber

[0039] Analysis of free radical fluorescence phenomenon: The temperature and pressure of the capillary were kept constant, and a Zeiss LSM700 laser confocal microscope was used with a 555nm fixed laser and a 488nm fixed laser to observe the fluorescence characteristics of the water microdroplets, the free radical fluorescence indicator aqueous solution and hexadecane in the fused silica capillary reaction chamber in situ online. Fluorescence images were obtained to qualitatively analyze the free radicals in the water microdroplets, compare the differences in the fluorescence characteristics of the microdroplets of aqueous solution and interfacial water, and further verify whether free radicals are generated inside the microdroplets.

[0040] The image of the interface between the free radical fluorescent indicator aqueous solution and hexadecane in the fused silica capillary reaction chamber under the initial temperature and pressure (20°C / 5MPa) under the optical microscope transmission light state is shown in the figure below: Figure 2 As shown by Figure 2 It can be seen that when the fused silica capillary is under the initial temperature and pressure conditions of 20°C / 5 MPa, no water droplets are formed at the interface between the free radical fluorescent indicator aqueous solution and hexadecane.

[0041] The image of the microdroplets of free radical fluorescent indicator aqueous solution and hexadecane interface water in the fused silica capillary reaction chamber under high temperature and high pressure (130°C / 35MPa) under optical microscope transmission light is shown in the figure below. Figure 3 As shown by Figure 3 It can be seen that when the temperature and pressure rise to 130°C / 35MPa, the interface between the free radical fluorescent indicator aqueous solution and hexadecane begins to change, and water droplets are formed near the interface of hexadecane.

[0042] The fluorescence micrograph of the microdroplet of the free radical fluorescence indicator aqueous solution and the interface water of hexadecane in the fused silica capillary reaction chamber under high temperature and high pressure (130°C / 35MPa) in this example is shown in FIG. Figure 4 As shown. Figure 4It can be seen that at 130℃ / 35MPa, water droplets are formed near the interface of hexadecane. At the same time, it is observed that the generated water droplets have extremely strong fluorescence compared with the entire free radical fluorescence indicator aqueous solution, indicating that the free radical fluorescence indicator inside the water droplets detects the generation of free radicals at this time.

[0043] Example 2

[0044] The mass of the free radical fluorescent indicator was changed, the concentration of the free radical fluorescent indicator aqueous solution was 0.0009 μmol / L, the temperature of the sample bottle was 38° C., the time was 26 h, the length of the quartz capillary end extending out of the tapered sleeve was 4.5 mm, the length of the quartz capillary visible window was 3.7 cm, and the other conditions were the same as in Example 1.

[0045] When the fused silica capillary of this embodiment is at 130°C / 35MPa, water droplets are formed near the interface of hexadecane, and it is observed that the water droplets have extremely strong fluorescence compared with the entire free radical fluorescent indicator aqueous solution, indicating that the free radical fluorescent indicator inside the water droplets detects the generation of free radicals at this time.

[0046] Example 3

[0047] The mass of the free radical fluorescent indicator was changed, the concentration of the free radical fluorescent indicator aqueous solution was 0.00011 μmol / L, the temperature of the sample bottle was 42° C., the time was 22 h, the length of the quartz capillary end extending out of the tapered sleeve was 5.5 mm, the length of the quartz capillary visible window was 4.2 cm, and the other conditions were the same as in Example 1.

[0048] When the fused silica capillary of this embodiment is at 130°C / 35MPa, water droplets are formed near the interface of hexadecane, and it is observed that the water droplets have extremely strong fluorescence compared with the entire free radical fluorescent indicator aqueous solution, indicating that the free radical fluorescent indicator inside the water droplets detects the generation of free radicals at this time.

[0049] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection 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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