Microscopic visual displacement experimental device and experimental method

Abstract

The invention relates to a microcosmic visual displacement experimental device and experimental method.The microcosmic visual displacement experimental device comprises a reaction kettle, the reaction kettle is connected with a reaction kettle support through a first rotation driving mechanism, a fixing mechanism is arranged in the reaction kettle and used for fixing a rock core clamping mechanism, and a rock core placing area is arranged in the rock core clamping mechanism; a feeding cavity and a discharging cavity are arranged on two sides of the rock core placing area, the feeding cavity is connected with a feeding mechanism, the discharging cavity is connected with a back pressure mechanism and a vacuumizing mechanism, the reaction kettle is further connected with a confining pressure mechanism, a first window is arranged at the top of the reaction kettle, a lighting element is arranged above the first window, and a second window is arranged at the bottom of the reaction kettle. A first prism is arranged below the second window and connected with a first prism support through a second rotation driving mechanism, a second prism support is arranged on one side of the first prism support and connected with a second prism through a third rotation driving mechanism, and a microscope is arranged below the second prism. The experimental result of the experimental device is more accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of deep earth energy engineering physics experiments, and in particular to a microscopic visualization displacement experimental device and an experimental method. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Typical deep energy projects, such as shale gas development, CO2 geological storage, and underground energy storage, essentially involve the dynamic displacement of multiphase fluids in porous media. Compared to conventional multiphase flow processes, the high temperatures, high ground stresses, strongly heterogeneous pore structures, and multi-field coupling conditions unique to deep geological environments cause internal flows to exhibit strong nonlinearity. Therefore, understanding the multiphase displacement laws under high temperature, high pressure, and gravity is crucial for improving the development efficiency and storage safety of deep energy.

[0004] Researchers at home and abroad have conducted extensive experimental research on this issue, but most existing studies have employed two-dimensional planar models and simulated pore structures using PDMS (polydimethylsiloxane) chips. This approach has two limitations: First, two-dimensional planar models struggle to accurately reproduce the gravity-driven dynamics of fluid migration in deep-earth engineering, such as phase separation, sedimentation, and buoyancy; second, PDMS chips struggle to accurately simulate the pore topology and wall wettability of natural rock, which in turn affects the accuracy of experimental results. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a microscopic visual displacement experimental device and experimental method, which can take into account the gravity-dominated phase separation, sedimentation and flotation behaviors, and the experimental results are more accurate.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] In the first aspect, an embodiment of the present invention provides a microscopic visualization displacement experimental device, including a reactor, which is connected to a reactor bracket through a first rotation drive mechanism, a fixing mechanism is provided in the reactor, the fixing mechanism is used to fix a core clamping mechanism, a core placement area is provided inside the core clamping mechanism, a feed chamber and a discharge chamber are provided on both sides of the core placement area, wherein the feed chamber is connected to the feeding mechanism, and the discharge chamber is connected to a back pressure mechanism and a vacuum mechanism, the reactor is also connected to a confining pressure mechanism, a first window is provided on the top of the reactor, a lighting element is provided above the first window, a second window is provided at the bottom of the reactor, a first prism is provided below the second window, the first prism is connected to the first prism bracket through a second rotation drive mechanism, a second prism bracket is provided on one side of the first prism bracket, the second prism bracket is connected to the second prism through a third rotation drive mechanism, and a microscope is provided below the second prism.

[0008] Optionally, the feeding mechanism includes a feeding pipe, the discharge end of the feeding pipe is connected to the feeding chamber, the feeding end is connected to the first interface of the electrically controlled three-way valve, the second interface of the electrically controlled three-way valve is connected to the injection pump through the pump pipe, and the third interface of the electrically controlled three-way valve is connected to the discharge end of the suction pipeline. The suction pipeline is provided with multiple branches, each branch is connected to the corresponding intermediate container, and a switch valve is provided on the branch.

[0009] Optionally, the back pressure structure includes a back pressure pump, which is connected to one end of the back pressure pipeline, and the other end of the back pressure pipeline is connected to the discharge chamber. A back pressure valve is provided on the back pressure pipeline, and the pressure relief port of the back pressure valve is connected to the waste liquid pool through a pipeline.

[0010] Optionally, the vacuum pumping structure includes a vacuum pump connected to one end of a vacuum pumping pipeline, the other end of the vacuum pumping pipeline is connected to a discharge chamber of the core clamping mechanism, and a valve is provided on the vacuum pumping pipeline.

[0011] Optionally, the core clamping mechanism includes a base plate and a cover plate made of transparent material, the base plate and the cover plate are fixedly connected, a cavity is provided between the base plate and the cover plate, the cavity is provided with a core placement area for placing core pieces, and the core placement area has a feed cavity and a discharge cavity on both sides respectively.

[0012] Optionally, the fixing mechanism includes an annular upper plate and a lower plate, the upper plate and the lower plate are fixedly connected, the upper plate presses the core clamping mechanism through the groove on the edge of the inner ring part, and the lower plate is fixed to the bottom surface of the reactor.

[0013] Optionally, the bottom ends of the reactor bracket, the first prism bracket, and the second prism bracket are all connected to the moving part of the moving platform.

[0014] Optionally, the periphery of the reactor is covered with a heating element, and correspondingly, a temperature sensor is provided inside the reactor.

[0015] Optionally, the confining pressure mechanism includes a confining pressure pump, which is connected to one end of a confining pressure pipe, and the other end of the confining pressure pipe is connected to the internal space of the reactor. Accordingly, a pressure sensor is provided inside the reactor.

[0016] In a second aspect, an embodiment of the present invention provides an experimental method for the microscopic visualization displacement experimental device described in the first aspect, comprising the following steps:

[0017] The core slice is encapsulated in the core clamping mechanism, the core clamping mechanism is placed in the reactor, and the feeding cavity of the core clamping mechanism is connected to the feeding mechanism, and the discharging cavity is connected to the vacuum mechanism and the back pressure mechanism;

[0018] The reactor is adjusted to a simulated angle by a first rotation drive mechanism, and the angles of the first prism and the second prism are adjusted by a second rotation drive mechanism and a third rotation drive mechanism, so that the microscope can capture an image of the core slice through the first prism and the second prism;

[0019] The vacuum mechanism works to vacuum the microchannels in the core slice;

[0020] Injecting the displaced phase into the core clamping mechanism through the feeding mechanism, and after the displaced phase is injected, injecting the displacing phase into the core clamping mechanism through the feeding mechanism;

[0021] The images of the displacing phase and the displaced phase during the process of the displacing phase replacing the displaced phase are observed under a microscope.

[0022] Optionally, the method for preparing the core slice comprises the following steps:

[0023] The core blank is initially cut into cube pile samples;

[0024] The sample is cut to the set size for the second time, and then the sample is ground until the sample reaches the set thickness;

[0025] Femtosecond laser etching was used to machine microchannels on the surface of the polished sample.

[0026] The beneficial effects of the present invention are as follows:

[0027] 1. In the microscopic visualization displacement experimental device of the present invention, the reactor can rotate under the drive of the first rotation drive mechanism, the first prism can rotate, and the second prism can rotate, so that after the reactor is rotated to any angle, the microscope can collect images of the core inside the reactor. Since the reactor can rotate, it can realize 0-90° gravity vector simulation, and can simulate processes such as oil-water separation and CO2 storage at any gravity inclination angle of 0-90°. It can realistically reproduce the dynamic behaviors of phase separation, sedimentation, and flotation dominated by gravity during the migration of deep-earth engineering fluids, thereby improving the accuracy of the test results and the applicability of the entire experimental device.

[0028] 2. The microscopic visualization displacement experimental device of the present invention is provided with a back-pressure mechanism, which can apply a certain pressure at the discharge end of the core clamping mechanism, and cooperate with the pressure applied by the feeding mechanism at the feed end of the core clamping mechanism, so that the entire experimental device can perform experiments under high-pressure conditions. At the same time, the internal and external pressures of the core clamping mechanism are balanced through the confining pressure mechanism to avoid damage to the core clamping mechanism under the action of internal high pressure. At the same time, a heating element is provided on the periphery of the reactor, which can heat the reactor, thereby realizing displacement experiments under high-temperature conditions. The entire experimental device can truly simulate the actual high-temperature and high-pressure conditions of the formation, and can accurately simulate deep oil and gas reservoirs and storage environments, thereby improving the accuracy of the experimental results.

[0029] 3. The microscopic visualization displacement experimental device and experimental method of the present invention use real rock cores that are cut, ground, and processed by femtosecond etching to obtain core slices with microchannels for experiments. This can more realistically simulate the pore topology and wall wettability of natural rocks, thereby improving the accuracy of the experimental results. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0031] Figure 1 This is a schematic diagram of the overall structure of Example 1 of the present invention;

[0032] Figure 2 This is a schematic diagram of the cooperation between the first prism, the second prism and the mobile platform in Example 1 of the present invention;

[0033] Figure 3 This is a schematic structural diagram of a reactor according to Example 1 of the present invention;

[0034] Figure 4 This is a cross-sectional view of a reactor according to Example 1 of the present invention;

[0035] Figure 5This is a schematic diagram of the fixing mechanism of Example 1 of the present invention;

[0036] Figure 6 This is a flow chart of core slice production and packaging according to Example 2 or Example 3 of the present invention;

[0037] Figure 7 This is a schematic diagram of light path propagation when the core slice is placed horizontally in Example 2 or Example 3 of the present invention;

[0038] Figure 8 This is a schematic diagram of light path propagation when the reactor in Example 2 or Example 3 of the present invention rotates 30° counterclockwise;

[0039] Figure 9 This is a schematic diagram of light path propagation when the reactor in Example 2 or Example 3 of the present invention is rotated 60° counterclockwise;

[0040] Figure 10 Schematic diagram of light path propagation when the reactor in Example 2 or Example 3 of the present invention is rotated 90° counterclockwise;

[0041] Among them, 1. Injection pump; 2. First intermediate container; 3. Second intermediate container; 4. Third intermediate container; 5. Electric control tee; 6. Core clamping mechanism; 7. First valve; 8. Second valve; 9. Third valve; 10. Vacuum pump; 11. Confining pressure pump; 12. Controller; 13. Microscope; 14. Camera; 15. Computer; 16. Back pressure pump; 17. Back pressure valve; 18. Waste liquid tank; 19. Mobile platform; 20. First prism; 21. Second prism; 22. Control system; 23. Reactor; 24. Reactor cover. 25. Split clamp body; 26. Connecting screws; 27. Feed pipe; 28. Discharge pipe; 29. First viewing window; 30. Heating jacket; 31. LED shadowless lamp; 32. Fixing mechanism; 33. Second viewing window; 34. Sealing ring; 35. Pressure gauge; 36. First prism bracket; 37. Second prism bracket; 38. High-rigidity ball screw guide; 39. Micro-stepping motor; 40. Rotating shaft; 42. Core slice; 43. Base plate; 44. Cover plate; 45. Valve; 46. Capillary interface; 47. Upper plate; 48. Lower plate. DETAILED DESCRIPTION

[0042] Example 1

[0043] This embodiment provides a microscopic visualization displacement experimental device, such as Figure 1-Figure 2As shown, the reactor 23 includes a fixing mechanism 32 fixed inside the reactor 23. The two ends of the fixing mechanism are fixed to the bottom surface of the reactor 23 by bolts. The fixing mechanism 32 is used to fix the core clamping mechanism 6. The core clamping mechanism 6 is used to fix the core slice to be tested. The core slice has a microchannel. In this embodiment, the microchannel is a micro-nanoscale channel for the flow of the displaced phase and the displacing phase liquid. The core clamping mechanism 6 has a cavity inside for accommodating the core slice. The middle position of the cavity It is the core slice placement area, one side of the core slice placement area is the feed chamber, and the other side is the discharge chamber. The feed chamber is connected to the feeding mechanism, which is used to feed the displacing phase or the displaced phase into the feed chamber. The discharge chamber is connected to the back pressure mechanism and the vacuum mechanism. The back pressure mechanism is used to discharge the displaced phase. The back pressure mechanism can also apply a set pressure to the discharge chamber so that the core slice can be tested under a set high-pressure environment. The vacuum mechanism is used to vacuum the microchannel of the core slice.

[0044] The top of the reactor 23 is provided with a first viewing window 29, above which a lighting element is provided for providing a light source. The bottom of the reactor is provided with a second viewing window 33, above which a core clamping mechanism is located for transmitting light.

[0045] The reactor 23 is connected to the top of the reactor bracket via a first rotation drive mechanism. The first rotation drive mechanism can drive the reactor to rotate, thereby adjusting the angle of the reactor 23 .

[0046] A first prism 20 is provided below the reactor 23 for transmitting light. One end of the first prism 20 is connected to the top of the first prism bracket via a second rotation drive mechanism, and the second rotation drive mechanism can drive the first prism 20 to rotate.

[0047] A second prism 21 is also provided on one side of the reactor 23. The second prism 21 is used to receive light reflected by the first prism 20 or directly receive light from the reactor 23. The second prism 21 is connected to the top of the second prism bracket through a second rotation drive mechanism. The second rotation drive mechanism can adjust the angle of the second prism. A microscope 13 is provided below the second prism 21. The microscope 13 can observe the core slice through the reflection of light by the first prism 20 and the second prism 21. The microscopic dynamic process of the displacing phase and the displaced phase in the microchannel of the core slice can be observed through the microscope.

[0048] Specifically, such as Figure 3-Figure 4As shown, the reactor 23 is cylindrical and includes a reactor body. In this embodiment, the reactor body has an outer diameter of 30 cm and a height of 20 cm. It is a weld-free structure made of 1Cr18Ni9Ti stainless steel. The top of the reactor body is open, and a reactor cover 24 is provided at the open end of the reactor body. A sealing ring 34 is provided between the top of the reactor body and the reactor cover 24. In this embodiment, the sealing ring 34 is a metal-fluororubber composite sealing ring. After CNC machining, it is embedded in the sealing grooves provided between the top of the reactor body and the reactor cover 24 to achieve sealing when the pressure inside the reactor body is not less than 25 MPa.

[0049] A heating element is provided on the periphery of the kettle body, and the heating element adopts an existing annular heating sleeve 30. In this embodiment, the base of the heating sleeve 30 is made of aluminum silicate fiber material and is wound with a nickel-chromium alloy heating wire. The heating sleeve 30 is wound around the outer surface of the kettle body in a serpentine winding to achieve uniform heat field distribution, ensuring that the temperature of the medium in the kettle body changes smoothly within the range of 25°C-120°C.

[0050] The kettle body is also provided with a confining pressure injection hole, which is used to connect the confining pressure mechanism. A flange is provided at the confining pressure injection hole, which is connected to the confining pressure mechanism through the flange. The flange connection meets the sealing verification requirements of the ASME B16.20 standard.

[0051] The kettle body is provided with a pressure sensor and a temperature sensor. The pressure sensor has a measuring range of 35 MPa and the temperature sensor has a measuring accuracy controlled within the range of ±0.5°C. The digital signals of the pressure sensor and the temperature sensor are fed back to the controller 12 to achieve dynamic monitoring and closed-loop control.

[0052] The kettle cover is provided with a first viewing window 29, which is a high-transmittance window with a transmittance of not less than 95%. A lighting element is provided above the first window. In this embodiment, the lighting element is an LED shadowless lamp 31, and the two sides of the LED shadowless lamp 31 are fixedly connected to the kettle cover 24 by bolts.

[0053] A second viewing window 33 is provided at the bottom of the kettle body. The second viewing window 33 is a sapphire window made of precision polished sapphire material with a light transmittance of not less than 95%. The fixing mechanism 32 and the core clamping mechanism 6 are located directly above the second viewing window.

[0054] The inner side surfaces of the first window 29 and the second window 33 are both provided with a gold-plated layer to prevent static electricity. Preferably, the thickness of the gold-plated layer is 50 nm.

[0055] The LED shadowless lamp 31 is fixed directly above the first viewing window 29 , and the core clamping mechanism 6 is precisely installed directly above the second viewing window 33 . The four are coaxially arranged to form a vertical optical path.

[0056] The core clamping mechanism 6 is connected to the fixing mechanism 32, and both ends of the fixing mechanism 32 are mechanically fixed to the bottom surface of the kettle body by bolts, ensuring that the core slice is positioned stably during the experiment and meeting the imaging requirements of the high-resolution microscope.

[0057] The outer periphery of the heating sleeve 30 is provided with a split clamp 25, which includes a first clamp body and a second clamp body in a semicircular shape that match the kettle body. The top and bottom edges of the first clamp body and the second clamp body are provided with flanges facing inward, and the bottom flange cooperates with the bottom surface of the kettle body. The top flange is connected to a plurality of connecting screws 26 along the circumferential thread. The connecting screws 26 are pressed against the upper surface of the edge of the kettle cover 24, thereby realizing locking and fixation between the kettle cover 24, the kettle body and the split clamp. In this embodiment, the pre-tightening torque of the connecting screws 26 is controlled to be 120N.m.

[0058] A rotating shaft is provided at the center position of the outer arc surface of the first hoop body and the second hoop body. The split hoop is rotatably connected to the top of the reactor bracket through the rotating shaft. The split hoop can drive the reactor to rotate, thereby adjusting the angle of the reactor.

[0059] In this embodiment, a first rotation driving mechanism is provided at the top of the reactor bracket 41 . The first rotation driving mechanism is connected to the rotating shaft 40 , and the reactor is driven to rotate by the first rotation driving mechanism.

[0060] Preferably, the first rotation drive mechanism adopts a first motor with a horizontally arranged axis, the first motor is fixed to the top of the reactor bracket through a motor seat, and the output shaft of the first motor is connected to the rotating shaft through a coupling to drive the rotating shaft to rotate.

[0061] The first motor can drive the reaction kettle 23 to rotate, thereby adjusting the angle of the reaction kettle 23 .

[0062] The confining pressure mechanism includes a confining pressure pump 11, which is connected to a gas source or a liquid source. The outlet of the confining pressure pump 11 is connected to the confining pressure injection hole on the kettle body through a confining pressure pipeline, and is used to fill the interior of the kettle body with liquid or gas medium to apply confining pressure to the core clamping mechanism.

[0063] Furthermore, a pressure gauge 35 is provided on the confining pressure pipeline. The pressure gauge 35 adopts a high-precision piezoelectric element, has a measuring range up to 35 MPa, and a data acquisition frequency of not less than 20 Hz, thereby ensuring real-time monitoring of the confining pressure.

[0064] The reactor 23 is provided with a fixing mechanism 32, which is used to fix the core clamping mechanism. The core clamping mechanism 6 includes a bottom plate and a cover plate made of transparent glass. Preferably, the bottom plate 43 and the cover plate 44 are made of high-strength light-transmitting glass. The bottom plate 43 and the cover plate 44 are bonded and fixed. A space for accommodating the core slice 42 is formed between the bottom plate 43 and the cover plate 44. The middle of the space between the bottom plate 43 and the cover plate 44 is a core slice placement area. After the bottom plate 43 and the cover plate 44 are fixed, the core slice can be clamped and fixed in the core slice placement area. One side of the core slice placement area is a feed cavity, and the other side is a discharge cavity.

[0065] The feed chamber is detachably connected to the feed pipe 27 via a capillary joint 46 , and the discharge chamber is detachably connected to the discharge pipe 28 via a capillary joint 46 . The core clamping mechanism 6 composed of the bottom plate 43 and the cover plate 44 is fixed by a fixing mechanism 32 .

[0066] In this embodiment, Figure 5 As shown, the fixing mechanism includes a lower plate 48 and an upper plate 47. The upper plate 47 and the lower plate 48 can be detachably fixedly connected by multiple screws. The lower plate 48 and the upper plate 47 are both rectangular annular plates. The core clamping mechanism 6 is used to be placed on the lower plate 48. The upper plate 47 presses the core clamping mechanism 6 through the groove on the edge of the inner ring part. The two ends of the lower plate 48 are provided with fixing holes, and the fixing holes can pass through the fixing holes. The head of the fixing bolt is pressed on the upper surface of the lower plate 48, and the rod of the fixing bolt is threadedly fixed to the bottom surface of the reactor 23. A nut threadedly connected to the fixing bolt is provided below the lower plate 47, and the nut is pressed on the lower surface of the lower plate 47.

[0067] The feed pipe 27 is connected to the feeding mechanism, and the discharge pipe 28 is connected to the back pressure mechanism. The feeding mechanism is used to feed the displaced phase or the displacing phase into the core clamping mechanism 6 through the feed pipe 27, and the back pressure mechanism is used to introduce gas or liquid into the discharge cavity to apply pressure.

[0068] The discharge chamber is connected to one end of the vacuum tube through the discharge pipe, the other end of the vacuum tube is connected to one end of the vacuum pumping line, the other end of the vacuum pumping line passes through the kettle body and extends to the outside of the reactor and is connected to the vacuum pump 10. Preferably, a valve 45 is installed on the vacuum pumping line to control the conduction and disconnection of the vacuum pumping line.

[0069] The microchannel of the core slice in the core clamping mechanism is evacuated by a vacuum pump to ensure that the internal environment of the core clamping mechanism is free of air interference.

[0070] The feeding mechanism includes an electrically controlled three-way valve 5, which is connected to the control system 22 and can receive instructions from the control system to work.

[0071] The first interface of the electric-controlled three-way valve 5 is connected to one end of the feeding pipe, and the feeding pipe is fixedly connected to the feed pipe after extending into the interior of the reactor.

[0072] Furthermore, the feed pipe is connected to a pressure gauge 35 for detecting the feed pressure of a fluid such as a liquid or gas. The pressure gauge may be the same as the pressure gauge on the confining pressure pipeline, and will not be described in detail here.

[0073] The second port of the electrically controlled three-way valve 5 is connected to one end of the pumping tube, the other end of which is connected to the syringe pump 1. The syringe pump 1 can be an existing device and will not be described in detail here. In this embodiment, the syringe pump 1 is a medium-pressure, high-precision microfluidic syringe pump, model CETONI Nemesys M, with a built-in precision metering module and heating module, and a maximum operating pressure of 25 MPa. The syringe pump is equipped with a heating module and a heating sleeve, which can heat the conveying fluid to a set temperature to meet the requirements of high-temperature experiments.

[0074] The third interface of the electric three-way valve 5 is connected to one end of the suction pipeline. The suction pipeline is provided with three branches, which are respectively connected to the first intermediate container 2, the second intermediate container 3 and the third intermediate container 4. The three branches are provided with valves, namely the first valve 7, the second valve 8 and the third valve 9.

[0075] Preferably, the electrically controlled three-way valve 5, the first valve 7, the second valve 8 and the third valve 9 are solenoid valves, which adopt a high-response electromagnetic drive module and a precision sealing structure, and realize precise switching of fluid channels through a multi-channel solenoid valve group; the valve body material is made of corrosion-resistant stainless steel, and the internal seal is made of polytetrafluoroethylene (PTFE) material to ensure long-term stable operation under high temperature, high pressure and chemical media. The solenoid valve is connected to the control system, and its operation is controlled by the control system.

[0076] The back pressure mechanism includes a back pressure pipeline, which is connected to the discharge pipe connected to the discharge chamber, and the back pressure pipeline is connected to the back pressure pump 16. A back pressure valve 17 and a pressure gauge 35 are provided on the back pressure pipeline to achieve precise control of the back pressure and maintain the stability of the internal pressure of the core clamping mechanism 6. The pressure gauge 35 can be the same as the pressure gauge on the confining pressure pipeline and the feed pipe, and will not be described in detail here.

[0077] In this embodiment, the back-pressure valve 17 adopts an existing spring mechanical back-pressure valve, and its specific structure is not described in detail here. The back-pressure valve 17 has a pressure relief port, which is located directly below its outlet. The pressure relief port of the back-pressure valve 17 is connected to the waste liquid pool 18 through a pipeline to achieve harmless discharge of waste liquid and waste gas, ensuring that the entire experimental process meets environmental safety requirements.

[0078] Furthermore, the suction pipe, feed pipe, confining pressure pipeline, and back-pressure pipeline adopt a double-layer braided structure of 316L stainless steel with a pressure resistance of ≥35MPa, and each connection node is leak-proof sealed by a Swagelok tube joint; in addition, the outer layer of the high-pressure pipeline is coated with aluminum silicate fiber felt insulation material to ensure that the fluid maintains the required temperature during transportation.

[0079] A first prism 20 is provided below the reactor. The first prism 20 is rotatably connected to the top of the first prism bracket 36 via a rotating shaft and is connected to a second rotation drive mechanism at the top of the first prism bracket. The second rotation drive mechanism can drive the first prism to rotate, thereby adjusting the angle of the first prism.

[0080] In this embodiment, the second rotation drive mechanism uses a second motor, which is fixed to the top of the first prism bracket 36 and the output shaft of the second motor is connected to the rotating shaft 40 at the end of the first prism. The first prism is driven to rotate by the second motor to adjust the angle of the first prism.

[0081] A second prism 21 is provided on one side of the reactor. The second prism 21 is rotatably connected to the top of the second prism bracket 37 through a rotating shaft 40 and is connected to a third rotation drive mechanism at the top of the second prism bracket. The third rotation drive mechanism can drive the second prism to rotate, thereby adjusting the angle of the second prism.

[0082] In this embodiment, the third rotation drive mechanism uses a third motor, the third motor is fixed to the top of the second prism bracket and the output shaft of the third motor is connected to the rotating shaft at the end of the second prism. The second prism is driven to rotate by the third motor to adjust the angle of the second prism.

[0083] In this embodiment, the first motor, the second motor and the third motor are all micro-stepping motors 39, and optical encoders are installed on their output shafts to monitor the rotation angle in real time with an accuracy of ±0.3 arc seconds and a rotation angle resolution of ≤0.1°.

[0084] The output shafts of the first, second, and third motors are each connected to a rotation angle detection element to enable real-time monitoring of the output shaft rotation angle. The rotation angle detection element employs an encoder or a capacitive angle sensor, preferably a capacitive angle sensor. The capacitive angle sensor is connected to a control system and is capable of transmitting the detected rotation angle information to the control system, thereby controlling the rotation angles of the reactor, the first prism, and the second prism.

[0085] The bottom ends of the reactor bracket, the first prism bracket and the second prism bracket are all connected to the moving part of the moving platform and can move under the action of the moving platform.

[0086] In this embodiment, the mobile platform 19 adopts an existing two-axis linkage mechanism. The mobile platform 19 is connected to the control system 22, and its operation is controlled by the control system 22. The two-axis linkage mechanism includes an X-axis moving mechanism whose distribution directions are perpendicular to each other. The moving part of the X-axis moving mechanism is connected to the Y-axis moving mechanism, and the Y-axis moving mechanism is provided with a moving part. In this embodiment, two two-axis linkage mechanisms are provided, wherein the reactor bracket and the first prism bracket are connected to the moving part of one of the two-axis linkage mechanisms, and the second prism bracket is connected to the moving part of the other two-axis linkage mechanism.

[0087] In this embodiment, both the X-axis moving mechanism and the Y-axis moving mechanism adopt the existing ball screw mechanism, including a precision ball screw, a high-rigidity ball screw slide 38, a linear servo motor, and a grating scale. The linear servo motor sends a PWM signal to control the position and adjusts the feedback error in combination with the PID algorithm. The transmission of the high-rigidity ball screw slide is combined with the linear servo motor to drive the bracket to move along the X / Y axis. The repeated positioning accuracy can reach ±1μm, and the lead of the precision ball screw is 4mm. A laser displacement sensor is also provided to detect the displacement of the moving part. The laser displacement sensor is connected to the control system to provide real-time feedback on the translation position of the bracket.

[0088] The control system has a built-in path planning algorithm, which generates coordinated control instructions for the polygonal mirror rotation angle and bracket displacement according to the target optical path parameters, and corrects the error through PID closed-loop feedback.

[0089] The reactor bracket, the first prism bracket and the second prism bracket are made of high-strength aluminum alloy or titanium alloy material to ensure the lightness and high strength of the brackets.

[0090] A microscope 13 is provided below the second prism. The microscope 13 is a high-magnification microscope, preferably a Nikon ECLIPSE Ti2 inverted microscope. The multi-prism reflection and mobile platform integrated control system is used to observe the microscopic dynamic flow process of the core slice in the reactor in real time.

[0091] It also includes a high-speed camera 14 coupled to the microscope optical path, the high-speed camera 14 is connected to the control system 22, the control system is connected to the computer 15, and the dynamic process within the field of view of the high-magnification microscope 13 is synchronously recorded and transmitted to the computer in real time. The computer is equipped with Nikon's NIS-Elements imaging software, which is responsible for image preview, shooting and analysis to ensure efficient processing and storage of data.

[0092] The high-speed camera 14 can be arranged using existing technology, which will not be described in detail here.

[0093] Example 2

[0094] This embodiment provides an experimental method for the microscopic visualization displacement experimental device described in Example 1, comprising the following steps:

[0095] Step 1: Prepare a core slice and package the core slice together with the base plate and the cover plate to obtain a core clamping mechanism with the core slice packaged in the required experimental size;

[0096] Step 2: Install the core clamping mechanism in the reactor through a fixing mechanism, with the normal direction of the working surface of the core clamping mechanism parallel to the axis direction of the reactor body, and connect the feed pipe to the feed pipe, the vacuum pipe to the vacuum pipe, and the discharge pipe to the back pressure pipe. At the same time, the reactor is rotated to the simulation angle by the first motor, and the first prism and the second prism are rotated to the desired angle and moved to the desired position by the second motor, the third motor and the mobile platform. The core clamping mechanism is vacuumed by a vacuum pump. Generally, the vacuuming is required for more than 4 hours to remove the air inside the micro-nanoscale channels of the core slice.

[0097] Step 3: The experimental water is placed in the first intermediate container 2, and the experimental oil is placed in the second intermediate container 3 (a certain amount of methylene blue reagent can be added to the experimental water to make the experimental water appear blue). Each intermediate container is connected to the injection pump through a pipeline and a valve; the confining pressure pipeline is connected through the confining pressure pump 11, and the confining pressure liquid (water) is injected into the reactor through the confining pressure pump;

[0098] Step 4: Direct the LED shadowless lamp directly above the core slice in the reactor to illuminate it. Adjust the position and angle of the first and second prisms to ensure that the core slice image is projected vertically through the multi-prism and placed under the observation microscope. Simultaneously adjust the microscope focus position and magnification until a clear image of the micro- and nano-scale channels inside the core slice can be displayed on the computer and saved in the computer digital image processing software.

[0099] Step 5: Open the first valve 7 and control the electronically controlled three-way valve 5, so that the injection pump draws the simulated water in the first intermediate container into the injection pump, and then control the electronically controlled three-way valve to inject simulated water into the core clamping mechanism through the injection pump 1; control the injection pump and the confining pressure pump to pressurize to the formation model pressure. During this process, the confining pressure pump is controlled to make the pressure in the reactor higher than the pressure inside the core clamping mechanism by 2-3 MPa; the heating jacket 30 and the temperature and pressure controller 12 are linked to realize the control, and the confining pressure liquid in the reactor is heated to the simulated formation temperature of 100°C; use the inverted microscope 13 to observe the filling of the injected water in the real core displacement model until all the pores in the real core displacement model are completely filled, and then close the injection pump and valve; use the high-speed camera 14 to take an image of the core fully saturated with water, and calculate the saturation of the rock sample;

[0100] Step 6: Open the second valve 8, control the electronically controlled three-way valve, draw simulated oil into the syringe pump, then control the electronically controlled three-way valve to inject simulated oil into the core clamping mechanism through the syringe pump 1 (a certain amount of Sudan red dye can be added to make the experimental oil appear red in the experiment). Slowly pressurize the oil drive to drain water until the irreducible water state is reached. After that, close the syringe pump and valve. Use a microscope 13 and a high-speed camera 14 to record the oil-water seepage pattern during the oil-water drive process and the oil-water occurrence state in the irreducible water state in real time, and statistically obtain the irreducible water saturation of the rock sample.

[0101] Step 7: Conduct a water flooding experiment. By controlling the electronically controlled three-way valve, water is sucked into the injection pump, and simulated water is injected into the core clamping mechanism through the injection pump 1. At the same time, the back pressure pump 16 is started to apply pressure to the outlet of the core clamping mechanism. After the pressure at the inlet and outlet ends is balanced, the pressure of the injection pump 1 is slowly increased to conduct a water flooding experiment. At the same time, the oil-water seepage pattern during the water flooding process is observed, and the oil-water distribution image of the water flooding process is captured in real time. The oil-water saturation under the corresponding state is statistically obtained, and the microscopic oil displacement efficiency is calculated until the residual oil state is reached.

[0102] Step 8: After the experiment, petroleum ether is added to the third intermediate container 4 to flush and clean the core clamping mechanism and related displacement pipelines. The real-time data recording file is opened and analyzed in combination with the fluid flow characteristics in the channel at the corresponding time.

[0103] Example 3

[0104] This embodiment provides an experimental method for the microscopic visualization displacement experimental device described in Example 1, comprising the following steps:

[0105] Steps 1 to 4 are the same as those in Example 2 and are not described in detail here.

[0106] Step 5: Open the first valve and control the electronically controlled three-way valve to draw simulated crude oil into the injection pump. Then control the electronically controlled three-way valve to inject simulated crude oil into the core clamping mechanism through the injection pump. Control the injection pump and the confining pressure pump to pressurize the core to the formation model pressure. During this process, control the confining pressure pump to make the pressure in the reactor 2-3 MPa higher than the pressure in the core clamping mechanism. Heat the confining pressure fluid to the simulated formation temperature of 100°C through the heating jacket. Saturate the core with crude oil until the core and pores are filled with crude oil.

[0107] Step 6: Conduct a water-to-oil displacement experiment under high-temperature and high-pressure conditions. Switch the displacement fluid medium. First, close the first valve 7 and the valve on the confining pressure pipeline to ensure that the confining pressure annulus is constant at the formation temperature and pressure. Then, use the medium-pressure, high-precision microfluidic syringe pump 1 to conduct a water-to-oil displacement experiment. Take timely images during the displacement process. The water-to-oil displacement experiment ends when the residual oil in the model pores and channels no longer changes.

[0108] Step 7: No liquid is placed in the second intermediate container. The syringe pump and the three-way valve work together to absorb the gas in the second intermediate container. The switching method of the displacement medium is consistent with the water-to-oil process. The temperature and pressure of the fluid and the displacement medium in the confining pressure annulus are ensured to be stable under actual reservoir conditions. The injection flow rate of the syringe pump 1 is set to inject the displacement gas in a constant flow rate mode. The displacement process is recorded using a high-speed camera 14. The microscope supporting software is used to record images and videos of the fluid flow in the model channel. The fluid flow behavior in the model is observed in real time on a computer.

[0109] Step 8 is consistent with Step 8 of Example 2.

[0110] like Figure 6 As shown, in Examples 2 and 3, the production of core slices is roughly divided into the following steps: sample selection, grinding, microchannel etching, cover plate production, and sheet bonding and packaging. Taking the real rock sample of sandstone as an example, the production method of the core slice includes the following steps:

[0111] (1) Sampling: Sandstone cores with no obvious cracks and uniform mineral distribution were selected. X-ray diffraction analysis was used to confirm that the quartz content was greater than 75% and the clay mineral content was less than 15%. After CT scanning was used to verify the structural integrity, the cores were initially cut into rectangular samples of 3 cm × 2 cm × 1 cm, with a certain processing allowance.

[0112] (2) Grinding: Cut the sample into a standard size of 2 cm × 1 cm × 0.6 cm, and grind it to a thickness of 0.1 mm using 200#, 60#, and 9# diamond sand in order. The surface roughness after fine grinding should be ≤ 0.01 μm, and the flatness error should be < 5 μm. Ensure that the surface is as bright as a mirror and free of scratches.

[0113] (3) Microchannel etching: Using a femtosecond laser etching system, refer to the designed planar crack network model to etch multi-level cracks with a width of 30-240 μm and a depth of 100 μm. After completion, use ethanol and deionized water plasma cleaning to remove etching residues;

[0114] The microchannel has a fluid injection port and an outlet at both ends, both with an inner diameter of 200 μm.

[0115] (4) Cover plate fabrication: The cover plate 44 is made of high-strength light-transmitting glass. Double holes are pre-etched on any glass to serve as the top plate. The double holes are the inlet and outlet, respectively, for inserting the feed pipe and the discharge pipe. The inlet / outlet are connected by a capillary structure to ensure that the fluid enters the core pores smoothly;

[0116] (5) Chip bonding and packaging: The bottom plate 43, the real core slice sample 42 and the cover plate 44 are stacked in sequence, and glue coating and curing are performed in sequence to obtain the core mineral chip.

[0117] The specific steps for adjusting the inclination angles of the reactor, the first prism, and the second prism are as follows:

[0118] (1) The reactor is adjusted to rotate counterclockwise by 0° / 30° / 60° / 90° from the horizontal position by using the first motor, and the model to be observed is locked after adjustment to prevent displacement.

[0119] (2) In order to correct the optical path deviation caused by the tilt of the core clamping mechanism, the following adjustments are made to the polygonal prism and the mobile platform: the second motor and the third motor are used to control the rotation of the first prism 20 and the second prism (resolution ≤ 0.5°) respectively to achieve dynamic optical path alignment. After adjustment, the first prism 20 and the second prism 21 are prevented from displacement. After adjustment, the optical path enters the Nikon inverted microscope vertically. At the same time, the high-speed camera (frame rate 1000fps) is controlled by IS Elements software to synchronously shoot the two-phase flow process in the microfluidic channel. The bubble size distribution and flow velocity field in the image are analyzed in combination with ImageJ software. The specific rotation angle parameters are shown in Table 1, and the rotation schematic diagram is shown in Figure 7 、 Figure 8 、 Figure 9 and Figure 10 shown.

[0120] Table 1 Rotation angle parameters of the observed model, the first prism 20 and the second prism 21

[0121]

[0122] Note: In Table 1, the rotation angles of the first prism (20) and the second prism (21) are positive when the rotation axis rotates counterclockwise around the horizontal position, and negative when the rotation axis rotates clockwise; the angle descriptions in Table 1 are all angles with the positive direction of the x-axis.

[0123] The experimental apparatus and experimental method of this embodiment can realize displacement experiments of various different displacement media, such as gas flooding, water flooding, and chemical flooding. The distribution of fluid in the pore throats of the actual core and the degree of fluid flow in different pore sizes can be observed in real time during the displacement process. The experimental process can ensure thermal insulation and pressure maintenance, with temperatures reaching 100°C and pressures reaching 25 MPa, realistically simulating the actual high-temperature and high-pressure conditions of the formation. It can accurately simulate deep-earth oil and gas reservoirs and storage environments, providing equipment support for displacement experiments in high-temperature and high-pressure environments.

[0124] At the same time, the reactor in the experimental device of this embodiment can realize 0-90° gravity vector simulation through local angle adjustment, which can simulate oil-water separation, CO2 storage and other processes under any gravity inclination angle of 0-90°, and is suitable for in-situ research on deep oil and gas reservoirs and geological energy storage.

[0125] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A microscopic visualization displacement experimental device, characterized in that: The invention comprises a reactor, which is connected to the reactor bracket through a first rotation drive mechanism, a fixing mechanism is provided in the reactor, the fixing mechanism is used to fix the core clamping mechanism, a core placement area is provided inside the core clamping mechanism, a feed chamber and a discharge chamber are provided on both sides of the core placement area, wherein the feed chamber is connected to the feeding mechanism, the discharge chamber is connected to a back pressure mechanism and a vacuum mechanism, the reactor is also connected to a confining pressure mechanism, a first window is provided on the top of the reactor, a lighting element is provided above the first window, a second window is provided at the bottom of the reactor, a first prism is provided below the second window, the first prism is connected to the first prism bracket through a second rotation drive mechanism, a second prism bracket is provided on one side of the first prism bracket, the second prism bracket is connected to the second prism through a third rotation drive mechanism, and a microscope is provided below the second prism.

2. A microscopic visualization displacement experimental device according to claim 1, characterized in that: The feeding mechanism includes a feeding pipe, the discharge end of the feeding pipe is connected to the feeding chamber, the feeding end is connected to the first interface of the electrically controlled three-way valve, the second interface of the electrically controlled three-way valve is connected to the injection pump through the pump pipe, and the third interface of the electrically controlled three-way valve is connected to the discharge end of the suction pipeline. The suction pipeline is provided with multiple branches, each branch is connected to the corresponding intermediate container, and a switch valve is provided on the branch.

3. A microscopic visualization displacement experimental device according to claim 1, characterized in that: The back pressure structure includes a back pressure pump, which is connected to one end of the back pressure pipeline, and the other end of the back pressure pipeline is connected to the discharge chamber. A back pressure valve is provided on the back pressure pipeline, and the pressure relief port of the back pressure valve is connected to the waste liquid pool through a pipeline.

4. The microscopic visualization displacement experimental device according to claim 1, characterized in that: The vacuum pumping structure includes a vacuum pump connected to one end of a vacuum pumping pipeline, the other end of which is connected to a discharge cavity of the core clamping mechanism, and a valve is provided on the vacuum pumping pipeline.

5. The microscopic visualization displacement experimental device according to claim 1, characterized in that: The core clamping mechanism includes a bottom plate and a cover plate made of transparent material, which are fixedly connected. A cavity is provided between the bottom plate and the cover plate. The cavity is provided with a core placement area for placing core pieces, and the core placement area is flanked by a feed cavity and a discharge cavity.

6. The microscopic visualization displacement experimental device according to claim 1, characterized in that: The fixing mechanism includes an annular upper plate and a lower plate, which are fixedly connected. The upper plate presses the core clamping mechanism through the groove on the edge of the inner ring part, and the lower plate is fixed to the bottom surface of the reactor.

7. The microscopic visualization displacement experimental device according to claim 1, characterized in that: The outer periphery of the reactor is covered with a heating element, and correspondingly, a temperature sensor is provided inside the reactor.

8. The microscopic visualization displacement experimental device according to claim 1, characterized in that: The confining pressure mechanism includes a confining pressure pump connected to one end of a confining pressure pipe, the other end of which is connected to the internal space of the reactor. Correspondingly, a pressure sensor is provided inside the reactor.

9. An experimental method for the microscopic visualization displacement experimental device according to any one of claims 1 to 8, characterized in that: The following steps are involved: The core slice is encapsulated in the core clamping mechanism, the core clamping mechanism is placed in the reactor, and the feeding cavity of the core clamping mechanism is connected to the feeding mechanism, and the discharging cavity is connected to the vacuum mechanism and the back pressure mechanism; The reactor is adjusted to a simulated angle by a first rotation drive mechanism, and the angles of the first prism and the second prism are adjusted by a second rotation drive mechanism and a third rotation drive mechanism, so that the microscope can capture an image of the core slice through the first prism and the second prism; The vacuum mechanism works to vacuum the microchannels in the core slice; Injecting the displaced phase into the core clamping mechanism through the feeding mechanism, and after the displaced phase is injected, injecting the displacing phase into the core clamping mechanism through the feeding mechanism; The images of the displacing phase and the displaced phase during the process of the displacing phase replacing the displaced phase are observed under a microscope.

10. The experimental method of the microscopic visualization displacement experimental device according to claim 9, characterized in that: The method for making the core slice comprises the following steps: The core blank is initially cut into cube pile samples; The sample is cut to the set size for the second time, and then the sample is ground until the sample reaches the set thickness; Femtosecond laser etching was used to machine microchannels on the surface of the polished sample.

Images