An apparatus for microscopically characterizing solid-liquid interface hydrate crystal properties in situ

Abstract

The application discloses a device for micro in-situ characterization of hydrate crystal characteristics of a solid-liquid interface, which comprises a visual reaction kettle, a test sample, a simulated disturbance system, a confocal Raman spectrometer and a constant-temperature control system. The test sample comprises solid wafers arranged oppositely and liquid bridges between the solid wafers. The test sample is placed into the visual reaction kettle, and the temperature and pressure in the visual reaction kettle are adjusted to a low-temperature and high-pressure state. According to different test requirements, a three-axis moving force arm of the simulated disturbance system can drive the solid wafers to move in different directions, so that different degrees of disturbance can be simulated. Meanwhile, the disturbance of fluid injection / extraction, a magnetic field, an electric field and pH value change can also be simulated. In the state of disturbance, micro-analysis information of hydrate structure, components, pore occupancy, hydration number and the like in a natural gas hydrate generation / dissolution dynamic process on the solid-liquid interface can be obtained, so as to provide a theoretical basis for natural gas hydrate accumulation and exploitation.

Description

A device for microscopic in-situ characterization of the crystal properties of solid-liquid interface hydrates. Technical Field

[0001] This invention relates to the field of natural gas hydrate extraction technology, specifically to a device for microscopic in-situ characterization of the crystal properties of solid-liquid interface hydrates. Background Technology

[0002] Natural gas hydrates are ice-like, cage-like crystalline substances formed by water and natural gas molecules under low temperature and high pressure conditions. They are classified into Type I, Type II, and Type H. Natural gas hydrates represent both abundant clean energy reserves and a major obstacle to oil and gas pipeline transportation. From an energy extraction perspective, natural gas hydrate reservoirs have complex compositions, consisting of various mineral particles, primarily quartz, feldspar, calcite, and clay minerals. Under various disturbances such as temperature, pressure, and fluid flow, hydrate decomposition is easily induced, leading to deterioration of reservoir mechanical properties and potentially triggering catastrophic geological risks such as uneven formation subsidence, landslides, and even tsunamis. From a flow safety perspective, during long-distance natural gas transportation, various disturbances within the pipeline can promote hydrate formation and adhesion to the inner walls, forming dense blockages that seriously threaten transportation efficiency and safety.

[0003] The main interface for the formation and decomposition of hydrates is the solid-liquid interface. Different solid surfaces have a significant impact on the formation and decomposition of hydrates. However, the mechanism by which solid surfaces affect the crystal structure of hydrates, and thus their adhesion, formation, and decomposition, remains unclear. Therefore, exploring the microscopic influence of solid interfaces on the formation and decomposition of hydrates can provide a theoretical basis for the application of hydrate technology. However, there are currently no devices or methods for microscopically observing the changes in the formation and decomposition of hydrates at the solid-liquid interface. This makes it impossible to fully understand the characteristics of the hydrate-sediment solid interface and provide favorable data support for the industrial development of hydrate resources. Summary of the Invention

[0004] In view of this, the present invention proposes a device for microscopic in-situ characterization of the crystal properties of solid-liquid interface hydrates, which can simulate different perturbations, and then obtain qualitative and quantitative information on the formation / decomposition of hydrates during the dynamic process by confocal Raman spectroscopy.

[0005] The technical solution of this invention is implemented as follows:

[0006] A device for microscopic in-situ characterization of solid-liquid interface hydrate crystal properties includes a visualization reactor, a test sample, a simulation perturbation system, a confocal Raman spectrometer, and a constant temperature control system. The visualization reactor includes a viewing window and a reactor body, with the viewing window located on the top surface of the reactor body. The test sample includes solid wafers and liquid bridges, with the solid wafers positioned opposite each other inside the reactor body and the liquid bridges located between the solid wafers. The simulation perturbation system includes a placement platform, a three-axis moving arm, and a three-axis moving control panel. The placement platform is located inside the reactor body and below the viewing window, with the solid wafers placed on the placement platform. The three-axis moving arm is located inside the reactor body and is used to drive the movement of the solid wafers. The three-axis moving control panel is located outside the reactor body and is used to control the three-axis moving arm. The confocal Raman spectrometer is located above the viewing window. The constant temperature control system includes a constant temperature water bath and a circulation pipeline. An external cavity is provided inside the bottom surface of the reactor body, and the constant temperature water bath is located on one side of the reactor body and is connected to the external cavity via the circulation pipeline.

[0007] Preferably, the visualized reaction vessel further includes an inlet pipe, an outlet pipe, and valves. The inlet pipe and the outlet pipe are located on both sides of the vessel body, and the valves are respectively located on the inlet pipe and the outlet pipe.

[0008] Preferably, the system also includes a data acquisition and control system, which includes a temperature sensor, a pressure sensor, and an industrial control computer. The temperature sensor is embedded in the vessel body, the pressure sensor is installed on the exhaust pipe, and the industrial control computer is connected to the confocal Raman spectrometer, the temperature sensor, and the pressure sensor respectively.

[0009] Preferably, it also includes a gas supply system, which includes a gas cylinder and a pressure gauge, the inlet pipe is connected to the gas cylinder, and the pressure gauge is installed on the inlet pipe.

[0010] Preferably, the simulated disturbance system further includes a metal ring, a first electric push rod, a gas supply pipe, a gas pump, a porous medium, and a driving mechanism. The top surface of the placement platform is provided with an annular groove, the bottom surface of the metal ring is located in the annular groove, the solid wafer is located inside the metal ring, the first electric push rod is embedded in the top surface of the metal ring, and its output shaft is connected to the bottom surface of the gas supply pipe. The gas pump is located at the top of the gas supply pipe and is connected to one end of the gas supply pipe. The gas supply pipe is open on the side facing the solid wafer, the porous medium is located on the open side of the gas supply pipe, and the driving mechanism is used to drive the metal ring to rotate.

[0011] Preferably, the driving mechanism includes a rotary motor and an electromagnetic plate. The rotary motor is disposed inside the placement platform, and its output shaft is connected to the bottom surface of the electromagnetic plate. The electromagnetic plate is located below the metal ring and the solid wafer.

[0012] Preferably, the simulated disturbance system further includes a second electric push rod, a U-shaped frame, an electric turntable, a rotating box, an electrode plate, an electrode rod, a force plate, a spring, a conductive head, a conductive track, a battery pack, a horizontal electric slide, a vertical electric slide, and a third electric push rod. The second electric push rod is disposed on the inner side wall of the vessel, and its output shaft is connected to the side wall of the U-shaped frame. The opening of the U-shaped frame faces downward. The electric turntable is disposed opposite to the inner side wall of the U-shaped frame, and its rotation surface is connected to the end of the rotating box. The electrode plate is disposed on the side wall of the rotating box, and a through groove is provided on the side wall of the rotating box opposite to the electrode plate. The electrode rod passes through the through groove, and the force plate and the electrode rod... The end connection is located inside the rotating box. The spring connects the force plate and the inner side wall of the rotating box. The conductive head is located on the top of the electrode rod. The conductive track is located on the top surface of the through slot and on the moving path of the conductive head. The battery pack is located inside the rotating box and is electrically connected to the electrode plate and the conductive track. The horizontal electric slide is embedded in the top and bottom surfaces of the rotating box. The two ends of the vertical electric slide are connected to the mover of the horizontal electric slide. The third electric push rod is located on the side wall of the mover of the vertical electric slide. The force plate is located on one side of the moving path of the third electric push rod. The solid wafer is located on the moving path of the rotating box.

[0013] Preferably, the simulated disturbance system further includes a sleeve, a normally open button, and a gravity rod. The sleeve is disposed on the bottom surface of the rotating box and has an open bottom end. The normally open button is disposed on the inner top surface of the sleeve. The top end of the gravity rod extends into the sleeve, and a slider is disposed on its side wall. A sliding groove is disposed on the inner side wall of the sleeve, and the slider is located in the sliding groove. The electrode plate is electrically connected to the battery pack through the normally open button.

[0014] Preferably, the simulated disturbance system further includes a storage tank and an injection head. The storage tank is located on the top surface of the U-shaped frame and stores pH adjustment liquid. The injection head is connected to the storage tank and faces the direction of the liquid bridge.

[0015] Preferred methods include the following:

[0016] The confocal Raman spectrometer was calibrated so that the Raman peak position was at 520.

[0017] The solid wafers are placed opposite each other on the placement platform, and a liquid bridge is formed in the middle of the solid wafers using a micro-injector.

[0018] Nitrogen gas was injected into the reactor to test its airtightness.

[0019] A three-axis moving arm, controlled by a three-axis moving console, drives the solid-state wafer to move, simulating different degrees of disturbance.

[0020] The laser position of the confocal Raman spectrometer is adjusted to the contact point between the solid wafer and the liquid bridge for focusing, and the test time is set.

[0021] Seal the vessel and regulate the temperature and pressure inside.

[0022] Microscopic analysis information on the dynamic process of natural gas hydrate formation / decomposition at the interface between a solid wafer and a liquid bridge was obtained by confocal Raman spectroscopy.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] ① Solid wafers are used to simulate mineral particles in actual reservoirs, and liquid bridges are set between solid wafers to simulate the morphology of water droplets on the mineral surface in the pore space of the reservoir. After providing a low temperature and high pressure environment through the reactor body, the natural gas hydrate formation / decomposition process at the solid-liquid interface of the solid wafers and liquid bridges is collected by a confocal Raman spectrometer, which provides a theoretical basis for the formation and exploitation of natural gas hydrates.

[0025] ② During the experiment, the three-axis moving lever arm can be used to move the solid wafers on both sides along the XYZ axes. Depending on the experimental requirements, different degrees of disturbance can be simulated, thereby obtaining the hydrate structure, composition, pore occupancy rate, and hydration number in the dynamic process. This provides an in-depth understanding of the microscopic occurrence state and time-varying evolution law of hydrates at the pore scale, and has practical significance for the prediction of natural gas hydrate production capacity and the optimization of mining schemes. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only preferred embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 is a schematic diagram of the structure of a first embodiment of a device for microscopic in-situ characterization of the crystal properties of solid-liquid interface hydrates according to the present invention.

[0028] Figure 2 is a schematic diagram of the connection structure between the vessel and the simulated disturbance system of a second embodiment of the device for microscopic in-situ characterization of solid-liquid interface hydrate crystal properties according to the present invention.

[0029] Figure 3 is a schematic diagram of the connection structure between the placement platform and the test sample in a second embodiment of the device for microscopic in-situ characterization of solid-liquid interface hydrate crystal properties according to the present invention.

[0030] Figure 4 is a schematic diagram of the internal structure of the rotating box of a second embodiment of the device for microscopic in-situ characterization of solid-liquid interface hydrate crystal properties according to the present invention.

[0031] Figure 5 is an enlarged view of point A in Figure 4;

[0032] Figure 6 shows the contact angles of different quartz wafers;

[0033] Figure 7 shows the hydrate formation process of different quartz wafers under static conditions;

[0034] Figure 8 shows the hydrate decomposition process of different quartz wafers under static conditions;

[0035] Figure 9 shows the peak intensities of the large and small cage hydrates collected by a confocal Raman spectrometer during dynamic hydrate formation / decomposition experiments using different quartz crystals in the apparatus of this invention.

[0036] Figure 10 is a schematic diagram of the structure of a device for microscopic in-situ characterization of solid-liquid interface hydrate crystal properties, showing the hydrate adhesion force test in a reactor.

[0037] Figure 11 is a comparison of the adhesion forces of different quartz crystal faces during the decompression process of hydrates;

[0038] Figure 12 is a schematic diagram of the structure of a reaction vessel for friction force testing of a device for microscopic in-situ characterization of solid-liquid interface hydrate crystal properties according to the present invention.

[0039] In the diagram, 1. Confocal Raman spectrometer; 2. Industrial computer; 3. Pressure sensor; 4. Temperature sensor; 5. Three-axis motion control panel; 6. Three-axis motion lever arm; 7. Solid-state wafer; 8. Constant temperature water bath; 9. Gas cylinder; 10. Pressure gauge; 11. Reactor body; 12. Viewing window; 13. Liquid bridge; 14. Placement platform; 15. Circulation pipeline; 16. Reactor outer cavity; 17. Inlet pipe; 18. Exhaust pipe; 19. Valve; 20. Metal ring; 21. First electric actuator; 22. Gas delivery pipeline; 23. Gas pump; 24. Porous medium; 25. Annular groove; 26. Rotary electric... 27. Electromagnetic plate; 28. Second electric push rod; 29. ​​U-shaped frame; 30. Electric turntable; 31. Rotating box; 32. Electrode plate; 33. Electrode rod; 34. Force plate; 35. Spring; 36. Conductive head; 37. Conductive track; 38. Battery pack; 39. Horizontal electric slide; 40. Vertical electric slide; 41. Third electric push rod; 42. Through slot; 43. Sleeve; 44. Normally open button; 45. Gravity rod; 46. Slider; 47. Slide groove; 48. Storage box; 49. Injection head; 50. Mechanical sensor; 51. Fiberglass; 52. Spherical water droplet. Detailed Implementation

[0040] To better understand the technical content of this invention, a specific embodiment is provided below, and the invention will be further described in conjunction with the accompanying drawings.

[0041] Referring to Figures 1 to 5, the present invention provides a device for microscopic in-situ characterization of solid-liquid interface hydrate crystal properties, comprising a visualization reactor, a test sample, a simulation perturbation system, a confocal Raman spectrometer 1, and a constant temperature control system. The visualization reactor includes a viewing window 12 and a reactor body 11, the viewing window 12 being disposed on the top surface of the reactor body 11; the test sample includes solid wafers 7 and liquid bridges 13, the solid wafers 7 being disposed opposite each other inside the reactor body 11, and the liquid bridges 13 being located between the solid wafers 7; the simulation perturbation system includes a placement platform 14, a three-axis moving lever arm 6, and a three-axis moving control panel 5. The placement platform 14 is located inside the vessel body 11 and below the viewing window 12. The solid wafer 7 is placed on the placement platform 14. The three-axis moving lever 6 is located inside the vessel body 11 and is used to drive the solid wafer 7 to move. The three-axis moving control panel 5 is located outside the vessel body 11 and is used to control the three-axis moving lever 6. The confocal Raman spectrometer 1 is located above the viewing window 12. The constant temperature control system includes a constant temperature water bath 8 and a circulation pipeline 15. An outer cavity 16 is provided inside the bottom surface of the vessel body 11. The constant temperature water bath 8 is located on one side of the vessel body 11 and is connected to the outer cavity 16 through the circulation pipeline 15.

[0042] This invention discloses a device for microscopic in-situ characterization of the crystal properties of solid-liquid interface hydrates, used to investigate the formation / decomposition process of natural gas hydrates. The solid-liquid interface is the primary interface for hydrate formation and decomposition. Therefore, this invention simplifies the sedimentary reservoir into two parallel matrices, namely solid wafers 7, and then artificially creates liquid bridges 13 between the solid wafers 7 to simulate the morphology of water droplets on the mineral surface in the reservoir pore space. The formation / decomposition process of natural gas hydrates is carried out in a visualization reactor, which includes a reactor body 11 with a circular... A high-pressure transparent viewing window 12 made of sapphire, with a pressure resistance of 15 MPa, allows for full observation of the formation process on the mineral surface. The solid wafer 7, together with the liquid bridge 13, is placed inside the reactor body 11. The viewing window 12 allows observation of the formation / decomposition process of natural gas hydrates at the solid-liquid interface between the solid wafer 7 and the liquid bridge 13 inside the reactor body 11. Above the viewing window 12, a confocal Raman spectrometer 1 is set up to perform in-situ Raman observation of the hydrates, obtaining the formation / decomposition process of hydrates on the surface of the solid wafer 7, providing a theoretical basis for the formation and exploitation of natural gas hydrates.

[0043] In addition to the visual reactor, the present invention also includes a constant temperature control system. The constant temperature water bath 8 can deliver antifreeze to the outer cavity 16 of the reactor through the circulation pump and circulation pipeline 15. The internal temperature of the reactor body 11 can be adjusted by controlling the temperature of the antifreeze in the outer cavity 16. It has the function of rapid temperature adjustment and ensures the temperature control accuracy of the overall test system with small fluctuation range, thus fully ensuring the reliability of the test data.

[0044] Due to various disturbances, the storage state of hydrates is not static. This invention sets up a placement platform 14 inside the vessel 11 for placing the solid wafer 7. The three-axis moving lever arm 6 can drive the solid wafer 7 to move on the XYZ axes, thereby applying disturbances such as tension, compression, and shear to the liquid bridge 13. According to the experimental requirements, the hydrate formation / decomposition process at the solid-liquid interface under disturbance can be simulated. The confocal Raman spectrometer 1 can collect microscopic analysis information such as hydrate structure, composition, pore occupancy, and hydration number during the dynamic process, providing an in-depth understanding of the microscopic occurrence state and time-varying evolution law of hydrates at the pore scale. This has practical significance for the prediction of natural gas hydrate production capacity and the optimization of exploitation schemes.

[0045] Preferably, the visualized reaction vessel further includes an inlet pipe 17, an exhaust pipe 18, and a valve 19. The inlet pipe 17 and the exhaust pipe 18 are disposed on both sides of the vessel body 11, and the valve 19 is disposed on the inlet pipe 17 and the exhaust pipe 18 respectively.

[0046] Before the experiment begins, 0.2 MPa of methane gas can be vented into the vessel body 11 through the exhaust pipe 18, and the exhaust pipe 18 can be opened to vent the residual gas. After repeating this three times, high-pressure methane gas is injected into the vessel body 11 to ensure that the pressure inside the vessel body 11 is greater than the phase equilibrium pressure value of 3 MPa, so as to ensure that the vessel body 11 can stably provide a high-pressure environment.

[0047] Preferably, the system also includes a data acquisition and control system, which includes a temperature sensor 4, a pressure sensor 3, and an industrial control computer 2. The temperature sensor 4 is embedded in the vessel body 11, the pressure sensor 3 is installed on the exhaust pipe 18, and the industrial control computer 2 is connected to the confocal Raman spectrometer 1, the temperature sensor 4, and the pressure sensor 3 respectively.

[0048] A high-precision platinum resistance temperature sensor 4 and a specific diaphragm pressure sensor 3 are used to detect and stably acquire test temperature and pressure in real time, with high accuracy. The acquired data can be transmitted to an industrial control computer 2, which can view the current temperature and pressure. If any abnormality is found, timely intervention can be carried out to ensure that the inside of the vessel 11 can provide a high-pressure and low-temperature environment. In addition, the data acquired by the confocal Raman spectrometer 1 can also be transmitted to the industrial control computer 2 for display.

[0049] Preferably, it also includes a gas supply system, which includes a gas cylinder 9 and a pressure gauge 10. The inlet pipe 17 is connected to the gas cylinder 9, and the pressure gauge 10 is installed on the inlet pipe 17.

[0050] Gas cylinder 9 is connected to gas inlet pipe 17, which can supply methane into vessel 11. The pressure gauge 10 can monitor the output methane pressure in real time. Methane gas at different pressures can be injected into vessel 11 according to test requirements.

[0051] Preferably, the simulated disturbance system further includes a metal ring 20, a first electric push rod 21, a gas supply pipe 22, a gas pump 23, a porous medium 24, and a driving mechanism. The top surface of the placement platform 14 is provided with an annular groove 25, the bottom surface of the metal ring 20 is located in the annular groove 25, the solid wafer 7 is located inside the metal ring 20, the first electric push rod 21 is embedded in the top surface of the metal ring 20, and its output shaft is connected to the bottom surface of the gas supply pipe 22. The gas pump 23 is located at the top of the gas supply pipe 22 and is connected to one end of the gas supply pipe 22. The gas supply pipe 22 is open on the side facing the solid wafer 7, the porous medium 24 is located on the open side of the gas supply pipe 22, and the driving mechanism is used to drive the metal ring 20 to rotate.

[0052] In addition to providing compression, tension, and shear disturbances, this invention can also provide fluid injection / extraction disturbances near the solid-liquid interface. A rotatable metal ring 20 is provided on the outside of the solid wafer 7. A driving mechanism can drive the metal ring 20 to rotate around the solid wafer 7 and the liquid bridge 13 along the annular groove 25. A gas delivery pipe 22 is provided on the top of the metal ring 20. The gas delivery pipe 22 is open at both ends. A gas pump 23 is connected to one end, which can draw air from the vessel body 11 into the gas delivery pipe 22 and flow out from the other side of the gas delivery pipe 22. A porous medium 24 is provided on the open side of the gas delivery pipe 22 facing the solid wafer 7. When the gas flows through the gas delivery pipe 22, it can flow from the porous medium 24 to the solid wafer 7 and the liquid bridge 13, thereby simulating fluid flow disturbances.

[0053] Preferably, the driving mechanism includes a rotary motor 26 and an electromagnetic plate 27. The rotary motor 26 is disposed inside the placement platform 14, and its output shaft is connected to the bottom surface of the electromagnetic plate 27. The electromagnetic plate 27 is located below the metal ring 20 and the solid wafer 7.

[0054] The rotation of the metal ring 20 can be achieved by the electromagnetic plate 27. After the electromagnetic plate 27 is energized, it can magnetically attract the metal ring 20. Then, driven by the rotary motor 26, the electromagnetic plate 27 can drive the metal ring 20 to rotate. In addition, if it is not necessary to disturb the fluid flow, the electromagnetic plate 27 can generate a magnetic field at the solid wafer 7 and the liquid bridge 13 after being energized, in order to simulate magnetic field disturbance. At the same time, the direction of the magnetic field can be changed by the rotary motor 26 driving the electromagnetic plate 27 to rotate and by changing the direction of the input current of the electromagnetic plate 27, thus providing different magnetic field disturbances.

[0055] Preferably, the simulated disturbance system further includes a second electric push rod 28, a U-shaped frame 29, an electric turntable 30, a rotating box 31, an electrode plate 32, an electrode rod 33, a force plate 34, a spring 35, a conductive head 36, a conductive track 37, a battery pack 38, a horizontal electric slide 39, a vertical electric slide 40, and a third electric push rod 41. The second electric push rod 28 is disposed on the inner wall of the vessel body 11, and its output shaft is connected to the side wall of the U-shaped frame 29. The U-shaped frame 29 has its opening facing downwards. The electric turntable 30 is disposed opposite to the inner wall of the U-shaped frame 29, and its rotating surface is connected to the end of the rotating box 31. The electrode plate 32 is disposed on the side wall of the rotating box 31, and a through groove 42 is provided on the side wall of the rotating box 31 opposite to the electrode plate 32. The electrode rod 33 passes through the through groove 42. The force plate 36 has its output shaft connected to the side wall of the rotating box 31, and the electrode rod 33 passes through the through groove 42. The force plate 36 has its output shaft connected to the side wall of the rotating box 31, and the electrode rod 33 passes through the through groove 42. The second electric push rod 28 is disposed on the inner wall of the vessel body 11, and its output shaft is connected to the side wall of the U-shaped frame 29. The second electric push rod 28 is disposed on the inner wall of the vessel body 11, and its output shaft is connected to the side wall of the U-shaped frame 29. The second electric push rod 28 has its output shaft connected to the side wall of the rotating box 31, and its output shaft is connected to the side wall of the rotating box 31. The second electric push rod 28 has its output shaft connected to the side wall of the rotating box 31, and its output The electrode rod 33 is connected to the end of the rotating box 31. The spring 35 connects the force plate 34 and the inner side wall of the rotating box 31. The conductive head 36 is located on the top of the electrode rod 33. The conductive track 37 is located on the top surface of the through slot 42 and is located on the moving path of the conductive head 36. The battery pack 38 is located inside the rotating box 31 and is electrically connected to the electrode plate 32 and the conductive track 37. The horizontal electric slide 39 is embedded in the top and bottom surfaces of the rotating box 31. The two ends of the vertical electric slide 40 are connected to the moving parts of the horizontal electric slide 39. The third electric push rod 41 is located on the moving part side wall of the vertical electric slide 40. The force plate 34 is located on one side of the moving path of the third electric push rod 41. The solid wafer 7 is located on the moving path of the rotating box 31.

[0056] In addition to fluid flow disturbance and magnetic field disturbance, electric field disturbance can also be provided. Second electric push rods 28 are provided on both sides of the vessel body 11. The second electric push rods 28 can drive the electric turntable 30 and the rotating box 31 to move through the U-shaped frame 29. On both sides of the rotating box 31 are electrode plates 32 and several electrode rods 33. The electric turntable 30 can drive the rotating box 31 to rotate, so that the electrode plates 32 or electrode rods 33 face the solid wafer 7. When the rotating box 31 moves to the side of the solid wafer 7, the electrode plates 32 or electrode rods 33 can contact the solid wafer 7, apply an electric field to the solid wafer 7, and change the surface charge of the solid wafer 7. Thus, electric field disturbance can be applied to the solid wafer 7 and the liquid bridge 13. The electrode plates 32 and electrode rods 33 can respectively apply a uniform electric field or a local electric field to meet various experimental requirements.

[0057] There are multiple electrode rods 33. Several through slots 42 are provided on the side wall of the rotating box 31, allowing the electrode rods 33 to move within them. A force-bearing plate 34 is provided at one end of each electrode rod 33. The force-bearing plate 34 is connected to the inner wall of the rotating box 31 via a spring 35. When the force-bearing plate 34 is subjected to a pushing force, it can push the electrode rod 33 to move along the through slots 42. During this movement, the conductive heads 36 on the electrode rods 33 move into the conductive tracks 37, allowing the electrical energy from the battery pack 38 to be transferred to the electrode rods 33. The outwardly protruding electrode rods 33 can contact the solid wafer 7, applying a local electric field. The conductive heads 36 of the other stationary electrode rods 33 do not contact the conductive tracks. 37 is in contact with the circuit and is in a non-energized state to avoid wasting electrical energy. Inside the rotating box 31, there is also a horizontal electric slide 39 and a vertical electric slide 40. The horizontal electric slide 39 can drive the vertical electric slide 40 to move horizontally, while the vertical electric slide 40 can drive the third electric push rod 41 to move vertically. Thus, the third electric push rod 41 can move to different sides of the force plate 34. When the output shaft of the third electric push rod 41 extends, it can push the force plate 34, causing the electrode rod 33 to move to apply a local electric field. When the third electric push rod 41 leaves the force plate 34, the electrode rod 33 can be reset under the action of the spring 35, causing the conductive head 36 to leave the conductive track 37.

[0058] Preferably, the simulated disturbance system further includes a sleeve 43, a normally open button 44, and a gravity rod 45. The sleeve 43 is disposed on the bottom surface of the rotating box 31 and has an open bottom end. The normally open button 44 is disposed on the inner top surface of the sleeve 43. The top end of the gravity rod 45 extends into the sleeve 43, and a slider 46 is disposed on its side wall. A groove 47 is disposed on the inner side wall of the sleeve 43, and the slider 46 is located in the groove 47. The electrode plate 32 is electrically connected to the battery pack 38 through the normally open button 44.

[0059] Initially, electrode rod 33 is located on one side of solid-state wafer 7, while electrode plate 32 is located on the opposite side of electrode rod 33. At this time, sleeve 43 is located at the bottom of rotating box 31, gravity rod 45 is not in contact with normally open button 44, and electrode plate 32 cannot receive power from battery pack 38, thus being in a de-energized state. When it is necessary to apply a uniform electric field to solid-state wafer 7, electric turntable 30 will drive rotating box 31 to rotate, causing electrode plate 32 and electrode rod 33 to exchange positions. At this time, sleeve 43 will rotate to the top of rotating box 31. Under the influence of gravity, the gravity rod 45 will move downwards and press the normally open button 44, triggering the normally open button 44 to be closed. At this time, the electrical energy of the battery pack 38 can be supplied to the electrode plate 32 to apply a uniform electric field. During the movement of the gravity rod 45, the slider 46 can move along the slide groove 47 to ensure that the movement of the gravity rod 45 will not deviate. At the same time, the slider 46 is limited by the slide groove 47 to prevent the gravity rod 45 from sliding out of the sleeve 43 when the sleeve 43 is facing downwards.

[0060] Preferably, the simulated disturbance system further includes a storage tank 48 and an injection head 49. The storage tank 48 is disposed on the top surface of the U-shaped frame 29 and stores pH adjustment liquid. The injection head 49 is connected to the storage tank 48 and faces the liquid bridge 13.

[0061] In addition, the simulated disturbance of the present invention also includes pH adjustment of the liquid bridge 13. The second electric push rod 28 can drive the U-shaped frame 29 to move to one side of the solid wafer 7 and the liquid bridge 13. The injection head 49 can inject the acidic or alkaline pH adjustment liquid stored in the storage tank 48 into the liquid bridge 13 to adjust the pH value of the liquid bridge 13 and study the effect of acidic or alkaline environment on mineral surface properties and the stability of the liquid bridge 13.

[0062] The present invention provides a method for microscopic in-situ characterization of the properties of solid-liquid interface hydrate crystals, as follows:

[0063] After placing the solid wafer 7 face up in an alcohol beaker, place the alcohol beaker in an ultrasonic cleaner for cleaning. After cleaning, rinse with pure water and then dry with nitrogen.

[0064] To calibrate the confocal Raman spectrometer 1, test the silicon wafer until the Raman peak position is at 520°, then the calibration is successful.

[0065] The solid wafer 7 is placed opposite each other on the placement platform 14, and a liquid bridge 13 is formed in the middle of the solid wafer 7 by using a micro-injector to simulate the shape of water droplets on the surface of minerals in the pore space of the reservoir.

[0066] Apply foam water to the connection between the inlet pipe 17 and the outlet pipe and the vessel body 11 to monitor the airtightness. Inject nitrogen gas at about 2 MPa into the vessel body 11 and maintain it for about half an hour. Check whether there is any pressure change and whether there are continuous bubbles. If no such phenomenon occurs, the device is airtight.

[0067] The automatic movement parameters (movement direction: up, down, left, right, forward, backward, can be in the same direction or opposite) and movement time (can be simultaneous or sequential) of the intelligent control three-axis moving lever arm 6 can be set. According to the experimental requirements, it can simulate the disturbance of minerals in pores to different degrees. In addition, according to the experimental requirements, it can also provide fluid flow disturbance, magnetic field disturbance, electric field disturbance and pH value change disturbance.

[0068] The laser position of the confocal Raman spectrometer 1 is adjusted to the contact point between the solid wafer 7 and the liquid bridge 13 for focusing, and the test time is set.

[0069] Seal the vessel 11, determine the phase equilibrium temperature and pressure according to the phase equilibrium curve of natural gas hydrate, adjust the temperature inside the vessel 11 to the phase equilibrium temperature using a constant temperature water bath 8, inject 0.2 MPa of methane gas into the vessel to purge residual gas, repeat this operation three times, and then inject high pressure methane gas to ensure that the pressure inside the vessel 11 is greater than the phase equilibrium pressure value of 3 MPa.

[0070] After hydrate formation is complete, a depressurization decomposition experiment is conducted while maintaining the original disturbance state. A mineral surface hydrate formation / decomposition experiment is performed, where hydrates are formed / decomposed under varying degrees of disturbance. Confocal Raman spectroscopy is used to obtain the hydrate structure, composition, pore occupancy, and hydration number during the dynamic process of natural gas hydrate formation / decomposition at the mineral interface. This provides a deeper understanding of the microscopic occurrence state and time-varying evolution of hydrates at the pore scale, and has practical significance for predicting natural gas hydrate production capacity and optimizing extraction schemes.

[0071] This invention uses quartz wafers as the solid wafer 7 as the experimental material. Quartz is a trigonal crystal with multiple crystal faces. In actual reservoirs, natural gas hydrates can contact various crystal faces of quartz. However, the influence of different crystal faces on natural gas hydrates may vary significantly. The exposed crystal faces have different hydroxyl concentrations, resulting in different surface wettability. Figure 6 shows the contact angles of different quartz wafers. The two types of quartz wafers in Figure 6 were subjected to a static process hydrate formation / decomposition experiment. The formation and decomposition processes are shown in Figures 7-8. The hydrates are first formed on the (0001) quartz wafer, while the decomposition process occurs first on the (0001) quartz wafer. The experiment was conducted on a quartz crystal wafer. The generation and decomposition of this experiment are static processes, and can only be explained from the perspective of optical observation. It cannot fully simulate the actual state of hydrate formation in the strata, nor does it explore and analyze its microscopic scale. However, by applying the device of the present invention, this phenomenon can be studied in greater depth.

[0072] After performing the dynamic hydrate formation / decomposition process using the device of this invention, a confocal Raman spectrometer can obtain the hydrate structure, composition, pore occupancy, and hydration number on the solid wafer 7 during the dynamic process of hydrate formation / decomposition. This accurately reflects the dynamic information of hydrate formation and decomposition, providing a more precise characterization at the microscale. As shown in Figure 9, the intensity ratio of the large and small cage peaks of methane hydrate on the (0001) quartz wafer is approximately 2.78:1. The intensity ratio of the large and small cage peaks of methane hydrate in quartz wafers is 2.33:1, while the ratio under normal conditions is 3:1. Based on the analysis of formation stability, the stability of (0001) quartz wafers is... Quartz crystals are larger and relatively less prone to decomposition, which preliminarily verifies the results in Figure 8 from a microscopic perspective, providing a theoretical reference for the formation and decomposition of natural gas hydrates.

[0073] In addition to performing dynamic hydrate formation / decomposition processes, this invention can also test hydrate adhesion and friction. As shown in Figure 10, the elastic coefficient of glass fiber 51 is first calibrated using a mechanical sensor 50 to obtain the relationship between elastic force and deformation of glass fiber 51, which satisfies Hooke's Law. A spherical droplet 52 is suspended at the front end of glass fiber 51 using a spherical droplet ejector, and then gas is introduced to conduct a hydrate formation experiment. After hydrate formation, a three-axis moving lever arm 6 is used to make the solid wafer 7 parallel to the glass fiber 51, allowing the hydrate to contact the solid wafer 7. Then, a confocal Raman spectrometer 1 focuses on the contact point between the hydrate and the solid wafer 7 to observe the deformation of glass fiber 51 and the in-situ Raman spectral changes throughout the process. Subsequently, hydrate decomposition under pressure is performed, and hydrate adhesion and in-situ Raman spectral tests are conducted at different time points. Figure 11 shows a preliminary experimental comparison of adhesion forces on different crystal planes during the decomposition process of the quartz crystal plane. Compared to the (0001) quartz crystal plane, the adhesion force of natural gas hydrate particles to… Quartz wafers have relatively strong adhesion; analysis suggests that, compared to the (0001) crystal plane, Quartz wafers are relatively hydrophobic, and the difference in adhesion may be due to the difference in wettability between different quartz crystal faces.

[0074] During the hydrate friction test, the solid wafer 7 is placed on the mechanical sensor 50, and the spherical water droplet 52 is dragged at a constant speed by the three-axis moving force arm 6, as shown in Figure 12. The in-situ Raman spectroscopy test is completed during the hydrate formation and decomposition process, and the changes in friction and Raman spectrum during the hydrate formation and decomposition process are obtained.

[0075] 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 within the protection scope of the present invention.

Claims

1. A device for microscopic in-situ characterization of the crystal properties of solid-liquid interface hydrates, characterized in that, The system includes a visualization reactor, test samples, a simulation perturbation system, a confocal Raman spectrometer, and a temperature control system. The visualization reactor includes a viewing window and a reactor body; the viewing window is located on the top surface of the reactor body. The test samples include solid wafers and liquid bridges; the solid wafers are positioned opposite each other inside the reactor body, and the liquid bridges are located between the solid wafers. The simulation perturbation system includes a placement platform, a three-axis moving arm, and a three-axis moving control panel. The placement platform is located inside the reactor body and below the viewing window; the solid wafers are placed on the placement platform. The three-axis moving arm is located inside the reactor body and is used to drive the movement of the solid wafers. The three-axis moving control panel is located outside the reactor body and is used to control the three-axis moving arm. The confocal Raman spectrometer is located above the viewing window. The temperature control system includes a constant-temperature water bath and circulation pipelines; the bottom surface of the reactor body is equipped with... The outer cavity of the reactor includes a constant temperature water bath located on one side of the reactor body and connected to the outer cavity via a circulation pipeline. The simulated disturbance system further includes a metal ring, a first electric push rod, a gas supply pipe, a gas pump, a porous medium, and a driving mechanism. The top surface of the placement platform is provided with an annular groove, the bottom surface of the metal ring is located in the annular groove, and the solid wafer is located inside the metal ring. The first electric push rod is embedded in the top surface of the metal ring, and its output shaft is connected to the bottom surface of the gas supply pipe. The gas pump is located at the top of the gas supply pipe and connected to one end of the gas supply pipe. The gas supply pipe is open on the side facing the solid wafer, and the porous medium is located on the open side of the gas supply pipe. The driving mechanism is used to drive the metal ring to rotate. The driving mechanism includes a rotary motor and an electromagnetic plate. The rotary motor is located inside the placement platform, and its output shaft is connected to the bottom surface of the electromagnetic plate. The electromagnetic plate is located below the metal ring and the solid wafer.The simulated disturbance system further includes a second electric push rod, a U-shaped frame, an electric turntable, a rotating box, an electrode plate, an electrode rod, a force plate, a spring, a conductive head, a conductive track, a battery pack, a horizontal electric slide, a vertical electric slide, and a third electric push rod. The second electric push rod is located on the inner wall of the vessel body, and its output shaft is connected to the side wall of the U-shaped frame. The U-shaped frame has its opening facing downwards. The electric turntable is located opposite to the inner wall of the U-shaped frame, and its rotation surface is connected to the end of the rotating box. The electrode plate is located on the side wall of the rotating box, and a through groove is provided on the side wall of the rotating box opposite to the electrode plate. The electrode rod passes through the through groove. The force plate is connected to the end of the electrode rod located inside the rotating box. The spring connects the force plate and the inner wall of the rotating box. The conductive head is located on the top of the electrode rod. The conductive track is located on the top surface of the through groove and is located on the moving path of the conductive head. The battery pack is located inside the rotating box and is connected to the electrode plate and the conductive track. The system includes an electric track connection. The horizontal electric slide is embedded in the top and bottom surfaces of the rotating box. The vertical electric slide is connected at both ends to the movers of the horizontal electric slide. The third electric push rod is located on the side wall of the mover of the vertical electric slide. The force plate is located on one side of the movement path of the third electric push rod. The solid wafer is located on the movement path of the rotating box. The simulated disturbance system also includes a sleeve, a normally open button, and a gravity rod. The sleeve is located on the bottom surface of the rotating box with an open bottom end. The normally open button is located on the top surface of the sleeve. The top of the gravity rod extends into the sleeve, and a slider is provided on its side wall. A groove is provided on the inner side wall of the sleeve, and the slider is located in the groove. The electrode plate is electrically connected to the battery pack through the normally open button. The simulated disturbance system also includes a storage tank and an injection head. The storage tank is located on the top surface of the U-shaped frame and stores pH adjustment liquid. The injection head is connected to the storage tank and faces the liquid bridge direction.

2. The apparatus for microscopic in-situ characterization of solid-liquid interface hydrate crystal properties according to claim 1, characterized in that, The visualized reaction vessel also includes an inlet pipe, an outlet pipe, and valves. The inlet pipe and the outlet pipe are located on both sides of the vessel body, and the valves are respectively located on the inlet pipe and the outlet pipe.

3. The apparatus for microscopic in-situ characterization of solid-liquid interface hydrate crystal properties according to claim 2, characterized in that, It also includes a data acquisition and control system, which includes a temperature sensor, a pressure sensor, and an industrial control computer. The temperature sensor is embedded in the vessel body, the pressure sensor is installed on the exhaust pipe, and the industrial control computer is connected to the confocal Raman spectrometer, the temperature sensor, and the pressure sensor respectively.

4. The apparatus for microscopic in-situ characterization of solid-liquid interface hydrate crystal properties according to claim 2, characterized in that, It also includes a gas supply system, which includes a gas cylinder and a pressure gauge. The inlet pipe is connected to the gas cylinder, and the pressure gauge is installed on the inlet pipe.

5. The apparatus for microscopic in-situ characterization of solid-liquid interface hydrate crystal properties according to claim 1, characterized in that, The following methods were used: calibrating the confocal Raman spectrometer to ensure the Raman peak position was at 520 cm⁻¹. -1 ; The solid wafer is placed on the placement platform and a liquid bridge is formed in the middle of the solid wafer using a micro-injector; nitrogen gas is injected into the reactor for airtightness testing; the solid wafer is moved by the three-axis moving arm controlled by the three-axis moving console to simulate different degrees of disturbance; the laser position of the confocal Raman spectrometer is adjusted to the contact point between the solid wafer and the liquid bridge for focusing, and the test time is set. The reactor was sealed, and the temperature and pressure inside the reactor were adjusted. Microscopic analysis information on the dynamic process of natural gas hydrate formation / decomposition at the interface between the solid wafer and the liquid bridge was obtained by confocal Raman spectroscopy.

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