Visual test device and method for porous medium displacement under different gravities

Abstract

The invention discloses a visual test device and method for porous medium displacement under different gravities. The micro-fluidic chip model module, the displacement injection module, the image acquisition module and the light source module are all placed in the model box shell, the model box shell is placed in a hanging basket of a centrifugal machine, fluid is stored in the displacement injection module and used for providing the fluid for the micro-fluidic chip model module, the displacement injection module is connected with the micro-fluidic chip model module, and the image acquisition module is connected with the light source module. The image acquisition module is used for acquiring optical image information of the micro-fluidic chip model module in a fluid displacement process; the method comprises the following steps: dyeing a primary fluid, installing the micro-fluidic chip, pushing a plastic injector by using an injection pump to inject the fluid into the micro-fluidic chip, and observing a flow migration mode and fluid distribution of the fluid in a displacement process in a porous medium. The device is simple and easy to manufacture, easy to operate and high in stability, model tests are carried out by utilizing supergravity and microgravity, and real-time observation of the two-phase fluid displacement process is realized.

Description

Technical Field

[0001] The present invention belongs to the field of experimental models of fluid displacement in porous media, and particularly relates to a visualization test device and method for porous media displacement under different gravities. Background Art

[0002] In recent years, with the construction of major energy projects such as underground carbon dioxide geological storage and underground hydrogen storage, the long-term displacement process of fluids in pores under the influence of gravity has received extensive attention. Taking carbon dioxide geological storage as an example, when carbon dioxide is injected underground at a depth of 1 kilometer, the buoyancy caused by density differences causes carbon dioxide to migrate upward, and this process is affected by brine and rocks. Therefore, understanding the dynamic migration pattern of carbon dioxide displacing brine in the pore structure is of great significance for evaluating the long-term migration and flow process of carbon dioxide in the pore structure.

[0003] Currently, in on-site monitoring means and simulation experiments, it is difficult to study the underground carbon dioxide migration process and leakage process because the fluid displacement and migration process cannot be directly observed. In addition, according to theoretical evaluations, the underground migration process of carbon dioxide may take more than a thousand years. Since it is difficult to capture this long-term fluid dynamic process under the in-situ high-temperature and high-pressure environmental conditions of underground reservoirs and the research cost is high, it is necessary to use alternative fluids and a supergravity centrifuge to accelerate the process for research.

[0004] Therefore, how to simply and conveniently observe the immiscible fluid displacement and migration process in the pore structure for a long time and effectively shorten the time has become a technical problem. Currently, the research and analysis of this process at home and abroad are mostly limited to the simulation level, and there is an urgent need for a set of test methods and devices to achieve observation and analysis. Summary of the Invention

[0005] In order to solve the problems existing in the background art, the purpose of the present invention is to provide a visualization test device and method for porous media displacement under different gravities. By using the tilt angle of the microfluidic chip to achieve microgravity conditions and the centrifugal force provided by the high-speed rotation of a supergravity centrifuge to achieve supergravity conditions, the large-scale fluid displacement and migration process in the field can be restored through the scale and time reduction effect, and real-time observation and analysis can be carried out. The test method is simple and highly operable, and can more deeply understand the displacement mechanism of two-phase fluids in porous media, which is of great significance for evaluating the long-term migration and flow process of carbon dioxide in the pore structure.

[0006] The technical solution adopted by the present invention is as follows:

[0007] I. A visualization test device for porous media displacement under different gravities:

[0008] It includes a model box housing, a microfluidic chip model module, a displacement injection module, an image acquisition module, and a light source module. The microfluidic chip model module, the displacement injection module, the image acquisition module, and the light source module are all placed inside the model box housing. The model box housing is placed in the hanging basket of a centrifuge. The displacement injection module stores fluid, and there is a connection between the displacement injection module and the microfluidic chip model module. The image acquisition module is used to acquire the optical image information of the microfluidic chip model module during the fluid displacement process.

[0009] The described microfluidic chip model module includes a microfluidic chip, a microfluidic chip fixing fixture, and an adjustable model fixing device. The adjustable model fixing device is installed on the inner bottom surface of the model box housing. The microfluidic chip fixing fixture is installed on the adjustable model fixing device. The adjustable model fixing device is used to adjust the height and angle of the microfluidic chip fixing fixture. The microfluidic chip is installed in the fixing groove of the microfluidic chip fixing fixture. The described microfluidic chip includes an injection port, a discharge port, and a porous medium area. The injection port and the discharge port are respectively arranged on both sides of the porous medium area. The porous medium area is mainly formed by arranging a number of cylinders with different sizes in a matrix at intervals.

[0010] The described displacement injection module includes a plastic syringe, an injection pump, and a fluid collection device. The injection pump and the fluid collection device are both installed on the inner bottom surface of the model box housing. The plastic syringe stores fluid. The inlet of the plastic syringe is connected to the injection pump. The outlet of the plastic syringe is connected to the injection port of the microfluidic chip through a diversion tube. The injection pump is externally connected to a control machine. The control machine is used to control the injection pump to push the plastic syringe to inject fluid into the microfluidic chip at a certain rate. The discharge port of the microfluidic chip is connected to the fluid collection device through a diversion tube. The fluid collection device is used to collect the fluid displaced from the microfluidic chip model module during the fluid displacement process.

[0011] The described image acquisition module includes an industrial camera and a camera fixing frame. The camera fixing frame is mainly composed of a lens support frame, an industrial camera fixing frame, and a camera base. The front end of the industrial camera is assembled with a lens. The industrial camera and the lens are respectively connected to the industrial camera fixing frame and the lens support frame. The lens support frame and the industrial camera fixing frame are both installed on the camera base. The camera base is installed on the inner bottom surface of the model box housing. The industrial camera is externally connected to a control machine.

[0012] The light source module is mainly composed of a light source and a light source fixing frame. The light source is installed inside the model box housing through the light source fixing frame. The light source is used to provide visible light for the imaging of the microfluidic chip model module.

[0013] The described device also includes a sealing and heat preservation module. The sealing and heat preservation module is mainly composed of a sealing plate and a heat preservation material. The sealing plate is installed on the inner surface of the model box housing. The heat preservation material is coated between the inner surface of the model box housing and the sealing plate.

[0014] The microfluidic chip stores the dyed native fluid, and the plastic syringe of the displacement injection module stores the displacement fluid. The native fluid and the displacement fluid have different densities and viscosities and are immiscible. The native fluid uses ethanol, and the displacement fluid uses pure carbon dioxide gas or air.

[0015] Second, a visualization test method for porous medium displacement under different gravities includes the following steps:

[0016] Step S1: First, dye the native fluid with a dye. Then, load the displacement fluid into another plastic syringe and install it on the injection pump. Install the microfluidic chip in the microfluidic chip fixing fixture, install the microfluidic chip fixing fixture on the adjustable model fixing device, and adjust the installation angle of the microfluidic chip fixing fixture.

[0017] Step S2: Inject the dyed native fluid into the microfluidic chip.

[0018] Step S3: Under different gravity conditions, use the controller to control the injection pump to push the plastic syringe to inject the displacement fluid into the microfluidic chip at a preset rate.

[0019] Step S4: When the displacement fluid reaches the outlet of the microfluidic chip and flows out to the fluid collection device, the controller receives the image or video information transmitted back by the image acquisition module, and obtains the flow migration pattern and fluid distribution of the fluid during the displacement process in the porous medium through the image or video information. Based on the flow migration pattern and fluid distribution collected from the simulation test, the analysis of the flow migration pattern and fluid distribution under actual working conditions is realized.

[0020] The specific content of step S2 is as follows:

[0021] Use the plastic syringe in the displacement injection module to inject the dyed native fluid into the microfluidic chip until it is saturated. Remove the plastic syringe filled with the dyed native fluid, switch to another plastic syringe filled with the displacement fluid and install it on the injection pump. The outlet of the plastic syringe is connected to the inlet at the bottom of the microfluidic chip through a diversion tube, and the outlet at the top of the microfluidic chip is connected to the fluid collection device. Adjust the angle and position of the industrial camera in the image acquisition module according to the tilt angle of the microfluidic chip.

[0022] Under microgravity conditions, the specific steps of step S3 are as follows:

[0023] Adjust the microfluidic chip to the preset tilt angle. Then, use the controller to start the injection pump, so that the injection pump pushes the plastic syringe to inject the displacement fluid into the microfluidic chip at a constant speed and constant pressure, and use the image acquisition module to collect the optical image information of the microfluidic chip during the fluid displacement process in real time.

[0024] Under hypergravity conditions, the specific steps of step S3 are as follows:

[0025] Start the centrifuge. When the centrifugal acceleration reaches N times the gravitational acceleration, use the control machine to control the injection pump to push the plastic syringe to inject the displacement fluid into the microfluidic chip at a constant speed and constant pressure, and use the image acquisition module to collect the optical image information of the microfluidic chip during the fluid displacement process in real time.

[0026] The device of the present invention can use a hypergravity centrifuge to provide a high centrifugal acceleration for pore structure scale-down and time-scale model experiments, and can also provide microgravity conditions for pore structure model experiments by customizing the angle of the adjustable model fixing module. The device is used to realize the real-time observation of the dynamic behavior of the two-phase displacement process in the pore structure, analyze the displacement movement mechanism of the two-phase fluid in the porous medium, so as to understand and predict the fluid displacement mode at the field scale. The device is simple and easy to manufacture, easy to operate, and has high stability. By using hypergravity and microgravity for model experiments, the real-time observation of the two-phase fluid displacement process is realized.

[0027] The present invention uses different gravity environments for pore structure scale model experiments, uses a transparent microfluidic chip to simulate the porous medium, and the image acquisition module observes the dynamic behavior of the two-phase displacement process in the pore structure in real time, analyzes the fluid migration mode and fluid distribution during the fluid displacement process in the porous medium, and provides an easy-to-operate and low-cost experimental method for studying the mechanism of fluid displacement at the pore scale. The present invention can control the injection pump to change the injection flow rate, adjust the angle of the microfluidic chip to achieve microgravity, and control the centrifuge to achieve hypergravity for different experiments, and analyze the flow pattern transformation mode of the fluid during the displacement process in the porous medium under different conditions.

[0028] The beneficial effects of the present invention are as follows:

[0029] 1. The present invention uses the image acquisition module to realize the visualization of the fluid displacement process, which is easy to analyze the fluid flow migration and flow pattern transformation mode generated during this process.

[0030] 2. The present invention adjusts the angle of the microfluidic chip to achieve microgravity, and uses the hypergravity centrifuge to provide a high centrifugal acceleration to achieve hypergravity, which can effectively reflect the two-phase fluid displacement process of the porous medium at the field scale.

[0031] 3. The present invention can change the influencing factors of fluid displacement, including injection rate, injection pressure, permeability, gravitational acceleration, etc., and can perform single-phase fluid displacement and multi-phase fluid displacement. The test device and method are simple, convenient, highly operable, and low-cost.

[0032] 4. The present invention utilizes the advantages of strong plasticity and strong repeatability of the microfluidic chip, can randomly set the pore structure, and restore the pore characteristics of the real field rock mass.

[0033] 5. The present invention is of great significance for studying the mechanism of two-phase fluid displacement in porous media, and has important guiding significance for the safety of carbon dioxide geological storage projects and the improvement of oil recovery in oilfields. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic diagram of the operation of the test device of the present invention;

[0035] Figure 2 is a side view of the structure of the device model box of the present invention;

[0036] Figure 3 is a schematic diagram of the structure of the visualization microfluidic chip model module of the present invention.

[0037] In the figure: Ⅰ - model box housing; Ⅱ - microfluidic chip model module; Ⅲ - displacement injection module; Ⅳ - image acquisition module; Ⅴ - control machine; Ⅵ - centrifuge; Ⅶ - counterweight; 1 - microfluidic chip fixing fixture; 2 - industrial camera; 3 - plastic syringe; 4 - injection pump; 5 - fluid collection device; 6 - camera fixing frame; 7 - adjustable model fixing device; 8 - light source; 9 - light source fixing frame; 10 - fixing platform; 11 - sealing and heat preservation module; 12 - diversion pipe; 13 - bolt; 14 - hexagon screw; 15 - upper fixing plate; 16 - lens support frame; 17 - injection port; 18 - porous media area; 19 - outlet; 20 - microfluidic chip. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] The present invention will be described in detail below in conjunction with specific implementation cases. The following implementation cases will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form.

[0039] As Figure 1 shown, the device includes a model box housing Ⅰ, a microfluidic chip model module Ⅱ, a displacement injection module Ⅲ, an image acquisition module Ⅳ and a light source module. The microfluidic chip model module Ⅱ is used to simulate the displacement process of two-phase fluid in porous media; the microfluidic chip model module Ⅱ, the displacement injection module Ⅲ, the image acquisition module Ⅳ and the light source module are all placed in the model box housing Ⅰ. The model box housing Ⅰ is placed in the hanging basket of the centrifuge Ⅵ. The displacement injection module Ⅲ stores fluid, and the displacement injection module Ⅲ is connected to the microfluidic chip model module Ⅱ to provide fluid for the microfluidic chip model module Ⅱ. The image acquisition module Ⅳ is used to collect optical image information of the microfluidic chip model module Ⅱ during the fluid displacement process.

[0040] Among them, the centrifuge VI includes two hanging baskets and a machine base. The two hanging baskets are respectively fixedly installed on both sides of the machine base of the centrifuge VI through the rotating arms, and are vertically downward in the initial state. The outer shell I of the model box is placed in the hanging basket on one side of the centrifuge VI, and a counterweight VII is placed in the hanging basket on the other side. The control machine V is electrically connected to the centrifuge VI, and the control machine V is used to drive the centrifuge VI to rotate. The hanging basket slowly rises to the horizontal state as the centrifuge VI rotates, and the rotating arm drives the hanging basket to rotate together to provide a high centrifugal acceleration. The centrifuge VI is used to provide a hypergravity environment equivalent to a high centrifugal acceleration and a high gravitational acceleration, so as to realize the reduction of the scale and time effect and restore the large-scale fluid displacement process on site; the counterweight VII is used to balance the model box I to maintain the mass balance of the two hanging baskets on both sides of the centrifuge VI.

[0041] As Figure 3 shown, the microfluidic chip model module II includes a microfluidic chip 20, a microfluidic chip fixing fixture 1, and an adjustable model fixing device 7. The adjustable model fixing device 7 is installed on the inner bottom surface of the outer shell I of the model box through a fixing platform 10. The microfluidic chip fixing fixture 1 is installed on the adjustable model fixing device 7 through hexagon screws 14. The adjustable model fixing device 7 is used to adjust the height and angle of the microfluidic chip fixing fixture 1. A fixing groove is provided in the middle of the microfluidic chip fixing fixture 1, and the microfluidic chip 20 is installed in the fixing groove of the microfluidic chip fixing fixture 1. The microfluidic chip 20 includes an injection port 17, a discharge port 19, and a porous medium area 18. The injection port 17 and the discharge port 19 are respectively arranged on the lower and upper sides of the porous medium area 18. The porous medium area 18 is mainly formed by arranging a number of cylinders with different sizes in a matrix at intervals.

[0042] The microfluidic chip 20 is an important component of the device of the present invention, and is processed by an etching process using a transparent glass material. According to the designed planar pattern of the microfluidic channel, a microfluidic channel (i.e., the porous medium area 18) capable of simulating the pores between real rock or soil particles is etched, which can simulate the actual working conditions of real rock or soil. The purpose of designing the microfluidic channel is to reproduce the internal structure of real rock or soil and allow detailed research on the displacement and migration of fluids in rock or soil. For different fluids such as water, oil, organic solvents, etc., it is necessary to select the material of the chip and perform targeted chemical modification or coating treatment. The adjustable model fixing device 7 is used to fix the microfluidic chip 20 so that the microfluidic chip 20 is on the same horizontal line as the industrial camera 2.

[0043] As Figure 2As shown in the figure, the displacement injection module III includes a plastic syringe 3, an injection pump 4, and a fluid collection device 5. The injection pump 4 and the fluid collection device 5 are both installed on the inner bottom surface of the model box housing I through a fixed platform 10. The plastic syringe 3 stores fluid. The inlet of the plastic syringe 3 is connected to the injection pump 4, and the outlet of the plastic syringe 3 is connected to the injection port 17 of the microfluidic chip 20 through a diversion tube 12. The injection pump 4 is externally connected to a control machine V, and the control machine V is used to control the injection pump 4 to push the plastic syringe 3 to inject displacement fluid into the microfluidic chip 20 at a certain rate. The outlet 19 of the microfluidic chip 20 is connected to the fluid collection device 5 through a diversion tube 12, and the fluid collection device 5 is used to collect the fluid displaced from the microfluidic chip model module II during the fluid displacement process.

[0044] In specific implementation, the characteristics of constant speed and constant pressure of the injection pump 4 can be used to accurately control the fluid flow rate entering the microfluidic chip 20, ensuring that the fluid passes through the microfluidic channels of the microfluidic chip 20 at a stable rate during the test. The fluid collection device 5 includes an L-shaped fixing frame and a centrifuge tube. The L-shaped fixing frame is fixedly connected to the fixed platform 10 through a bolt 13. The fixed platform 10 is fixed on the inner bottom surface of the model box housing I, and the centrifuge tube is tied to the L-shaped fixing frame through a binding band to avoid affecting fluid collection when the ultra-high gravity centrifuge VI rotates.

[0045] The image acquisition module IV includes an industrial camera 2 and a camera fixing frame 6. The camera fixing frame 6 is mainly composed of a lens support frame 16, an industrial camera fixing frame, and a camera base. A lens is assembled at the front end of the industrial camera 2. The industrial camera 2 and the lens at the front end of the industrial camera 2 are respectively connected to the industrial camera fixing frame and the lens support frame 16. The lens support frame 16 and the industrial camera fixing frame are both installed on the camera base, and the camera base is installed on the inner bottom surface of the model box housing I through a fixed platform 10. The industrial camera 2 is externally connected to a control machine V.

[0046] The lens support frame 16 is connected to the middle of the lens. The shooting angle direction of the industrial camera 2 can be changed by adjusting the height of the lens support frame 16, and finally ensuring that the microfluidic chip model module II is in the center of the field of view. The image acquisition module IV is mainly used to shoot the two-phase fluid displacement process and obtain the displacement mechanism of the fluid in the porous medium. The displacement injection module III is used to inject the original fluid and the displacement fluid during the test process.

[0047] The light source module is mainly composed of a light source 8 and a light source fixing frame 9. The light source 8 is installed inside the model box housing I through the light source fixing frame 9, and the light source 8 is used to provide visible light for the imaging of the microfluidic chip model module II.

[0048] The light source 8 is used to provide a uniform and stable light intensity during the experiment, and the light source 8 adopts LED lights arranged in multiple points. The light source fixing bracket 9 is installed on the inner bottom surface of the model box housing I through the fixing platform 10. The light source fixing bracket 9 is used to fix the light source 8 behind the microfluidic chip model module II, so that the center of the light source 8 is aligned with the center of the microfluidic chip model module II.

[0049] The device also includes a sealing and heat preservation module 11, which is mainly composed of a sealing plate and heat preservation materials. The sealing plate is installed on the inner surface of the model box housing I, and heat preservation materials are coated between the inner surface of the model box housing I and the sealing plate. The sealing and heat preservation module 11 is used for light shielding and heat preservation during the experiment.

[0050] The fixing platform 10 is used to jointly form an experimental system with the camera fixing bracket 6, the adjustable model fixing device 7, the displacement injection module III, and the sealing and heat preservation module 11. The camera fixing bracket 6, the adjustable model fixing device 7, and the displacement injection module III are all connected to the fixing platform 10 through bolts 13. The injection pump 4 is connected to the control center of the control machine V through wires and the centrifuge optical terminal. The image acquisition module IV is connected to the control center of the control machine V through wires.

[0051] The adjustable model fixing device 7 is used to fix the microfluidic chip 20, so that the microfluidic chip 20 and the industrial camera 2 are on the same horizontal line. The adjustable model fixing device 7 includes a front fixing plate and an upper fixing plate 15; the side of the front fixing plate is provided with holes to fix the microfluidic chip fixing fixture 1. The specific hole opening angle can be determined by the side hole opening distance of the microfluidic chip fixing fixture 1 and the expected microgravity value, so that the microfluidic chip 20 is tilted at a certain angle to conduct a fluid displacement experiment under microgravity conditions; the acceleration under microgravity conditions is less than the normal gravitational acceleration g, and the specific value is gsinθ, where θ is the angle between the microfluidic chip 20 and the ground, which can be achieved by tilting the microfluidic chip 20 at a certain angle. The upper fixing plate 15 is used to connect and fix the front fixing plate and the light source fixing bracket 9 to avoid the influence of disturbances during the experiment. The distance of the base of the adjustable model fixing device 7 can be adjusted back and forth to make the camera imaging clearer.

[0052] The microfluidic chip 20 stores a dyed native fluid, and the plastic syringe 3 of the displacement injection module III stores a displacement fluid. The native fluid and the displacement fluid have different densities and viscosities and are immiscible. The native fluid uses dyed ethanol, and the displacement fluid uses pure carbon dioxide gas or air.

[0053] The embodiments of the present invention include the following steps:

[0054] Step S1: First, dye the native fluid (ethanol) with a dye. Then, load a displacing fluid (carbon dioxide or air) that has a different density and viscosity from the native fluid and is immiscible into another plastic syringe, install the plastic syringe on the injection pump 4, install the microfluidic chip 20 in the microfluidic chip fixing fixture 1, install the microfluidic chip fixing fixture 1 with the microfluidic chip 20 installed therein on the adjustable model fixing device 7, and adjust the installation height and angle of the microfluidic chip fixing fixture 1 according to a preset angle.

[0055] Step S2: Inject the dyed native fluid into the microfluidic chip 20.

[0056] Step S3: Under different gravity conditions, use the controller V to control the injection pump 4 to push the plastic syringe 3 to inject the displacing fluid into the microfluidic chip 20 at a certain rate.

[0057] Step S4: When the displacing fluid reaches the outlet 19 of the microfluidic chip 20 and flows out to the fluid collection device 5, the porous medium displacement test under different gravities ends. The controller V receives the image or video information transmitted back by the image acquisition module IV, and obtains the flow migration pattern and fluid distribution of the fluid during the displacement process in the porous medium through the image or video information. Based on the flow migration pattern and fluid distribution collected from the simulation test, the analysis of the flow migration pattern and fluid distribution under actual working conditions is further realized.

[0058] Step S2 is specifically as follows:

[0059] Use the plastic syringe 3 in the displacement injection module III to inject the dyed native fluid into the microfluidic chip 20 until it is saturated. Remove the plastic syringe 3 filled with the dyed native fluid, switch to another plastic syringe 3 filled with the displacing fluid, install the other plastic syringe 3 on the injection pump 4, connect the outlet of the plastic syringe 3 to the injection port 17 at the bottom of the microfluidic chip 20 through the diversion tube 12, connect the outlet 19 at the top of the microfluidic chip 20 to the fluid collection device 5, turn on the light source 8 in the light source module, adjust the angle and position of the industrial camera 2 in the image acquisition module IV according to the tilt angle of the microfluidic chip 20 to calibrate the image of the industrial camera 2, and close the sealing plate with the bolt 13.

[0060] Under microgravity conditions, the specific steps of Step S3 are as follows:

[0061] Adjust the microfluidic chip (20) to the preset tilt angle, use the controller V to start the injection pump 4, so that the injection pump 4 pushes the plastic syringe 3 to inject the displacing fluid into the microfluidic chip 20 at a constant speed and constant pressure, and use the image acquisition module IV to collect the optical image information of the microfluidic chip 20 during the fluid displacement process in real time.

[0062] Under hypergravity conditions, the specific steps of step S3 are as follows:

[0063] Start centrifuge VI. After the centrifugal acceleration reaches N times the gravitational acceleration, use controller V to control injection pump 4 to push plastic syringe 3 to inject displacement fluid into microfluidic chip 20 at a constant speed and constant pressure, and use image acquisition module IV to collect the optical image information of microfluidic chip 20 during the fluid displacement process in real time.

[0064] The displacement fluid enters through inlet 17 at the bottom of microfluidic chip 20 through diversion tube 12. The displacement process of the fluid entering the interior of microfluidic chip 20 is affected by gravity, viscous force, and capillary force, and finally selects the optimal path for displacement. Image acquisition module IV can collect the fluid displacement process in microfluidic chip 20 in real time. The present invention can conduct experiments under different conditions by changing the angle of microfluidic chip 20, fluid flow rate, inlet pressure, and gravitational acceleration, and can analyze the flow pattern transition mode of the fluid displacement process in porous media under different conditions, and then analogize to the fluid displacement mode at the field scale.

[0065] The present invention uses different gravity environments to conduct pore structure scaled-down model experiments, restores the large-scale fluid displacement and migration process at the field through the scaling and time-scaling effects of the hypergravity field, and uses real-time observation and recording methods to understand the displacement mechanism of two-phase fluids in porous media, which is of great significance for evaluating the long-term migration and flow process of carbon dioxide in pore structures.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A visualization test device for porous media displacement under different gravities, characterized in that: It includes a model box housing (Ⅰ), a microfluidic chip model module (Ⅱ), a displacement injection module (Ⅲ), an image acquisition module (Ⅳ) and a light source module; the microfluidic chip model module (Ⅱ), the displacement injection module (Ⅲ), the image acquisition module (Ⅳ) and the light source module are all placed inside the model box housing (Ⅰ), the model box housing (Ⅰ) is placed in the hanging basket of a centrifuge (Ⅵ), the displacement injection module (Ⅲ) stores fluid, the displacement injection module (Ⅲ) is connected to the microfluidic chip model module (Ⅱ), and the image acquisition module (Ⅳ) is used to acquire the optical image information of the microfluidic chip model module (Ⅱ) during the fluid displacement process.

2. The visualization test device for porous medium displacement under different gravities according to claim 1, characterized in that: The microfluidic chip model module (Ⅱ) described above includes a microfluidic chip (20), a microfluidic chip fixing fixture (1) and an adjustable model fixing device (7); The adjustable model fixing device (7) is installed on the inner bottom surface of the model box housing (Ⅰ), the microfluidic chip fixing fixture (1) is installed on the adjustable model fixing device (7), the adjustable model fixing device (7) is used to adjust the height and angle of the microfluidic chip fixing fixture (1), the microfluidic chip (20) is installed in the fixing groove of the microfluidic chip fixing fixture (1), the microfluidic chip (20) includes an injection port (17), a discharge port (19) and a porous medium area (18), the injection port (17) and the discharge port (19) are respectively arranged on both sides of the porous medium area (18), and the porous medium area (18) is mainly formed by arranging a number of cylinders with different sizes in a matrix at intervals.

3. A visualization test device for porous medium displacement under different gravities according to claim 2, characterized in that: The displacement injection module (Ⅲ) described above includes a plastic syringe (3), an injection pump (4) and a fluid collection device (5); the injection pump (4) and the fluid collection device (5) are both installed on the inner bottom surface of the model box housing (Ⅰ), the plastic syringe (3) stores fluid, the inlet of the plastic syringe (3) is communicated with the injection pump (4), the outlet of the plastic syringe (3) is communicated with the injection port (17) of the microfluidic chip (20) through a diversion tube (12), the injection pump (4) is externally connected to a control machine (Ⅴ), and the control machine (Ⅴ) is used to control the injection pump (4) to push the plastic syringe (3) to inject fluid into the microfluidic chip (20), the discharge port (19) of the microfluidic chip (20) is communicated with the fluid collection device (5) through a diversion tube (12), and the fluid collection device (5) is used to collect the fluid displaced from the microfluidic chip model module (Ⅱ) during the fluid displacement process.

4. A visualization test device for porous medium displacement under different gravities according to claim 2, characterized in that: The image acquisition module (Ⅳ) described above includes an industrial camera (2) and a camera fixing frame (6), the camera fixing frame (6) is mainly composed of a lens support frame (16), an industrial camera fixing frame and a camera base, a lens is assembled at the front end of the industrial camera (2), the industrial camera (2) and the lens are respectively connected to the industrial camera fixing frame and the lens support frame (16), the lens support frame (16) and the industrial camera fixing frame are both installed on the camera base, the camera base is installed on the inner bottom surface of the model box housing (Ⅰ), and the industrial camera (2) is externally connected to a control machine (Ⅴ).

5. A visualization test device for porous medium displacement under different gravities according to claim 2, characterized in that: The light source module mainly consists of a light source (8) and a light source fixing bracket (9). The light source (8) is installed inside the model box housing (Ⅰ) through the light source fixing bracket (9), and the light source (8) is used to provide visible light for imaging the microfluidic chip model module (Ⅱ).

6. A visualization test device for porous medium displacement under different gravities according to claim 2, characterized in that: The device further includes a sealing and heat preservation module (11), which mainly consists of a sealing plate and heat preservation materials. The sealing plate is installed on the inner surface of the model box housing (Ⅰ), and heat preservation materials are coated between the inner surface of the model box housing (Ⅰ) and the sealing plate.

7. A visualization test device for porous medium displacement under different gravities according to claim 3, characterized in that: The microfluidic chip (20) stores a stained native fluid, and the plastic syringe (3) of the displacement injection module (Ⅲ) stores a displacement fluid. The native fluid and the displacement fluid have different densities and viscosities and are immiscible. The native fluid uses ethanol, and the displacement fluid uses pure carbon dioxide gas or air.

8. A visualization test method for porous medium displacement under different gravities, which is applied to the device according to any one of claims 1-7, characterized in that It includes the following steps: Step S1: First, stain the native fluid with a dye. Then, load the displacement fluid into another plastic syringe and install it on the injection pump (4). Install the microfluidic chip (20) in the microfluidic chip fixing fixture (1), install the microfluidic chip fixing fixture (1) on the adjustable model fixing device (7), and adjust the installation angle of the microfluidic chip fixing fixture (1). Step S2: Inject the stained native fluid into the microfluidic chip (20). Step S3: Under different gravity conditions, use the control machine (Ⅴ) to control the injection pump (4) to push the plastic syringe (3) to inject the displacement fluid into the microfluidic chip (20) at a preset rate. Step S4: When the displacement fluid reaches the outlet (19) of the microfluidic chip (20) and flows out to the fluid collection device (5), the control machine (Ⅴ) receives the image or video information transmitted back by the image acquisition module (Ⅳ), and obtains the flow migration pattern and fluid distribution of the fluid during the displacement process in the porous medium through the image or video information. Based on the flow migration pattern and fluid distribution collected from the simulation experiment, the analysis of the flow migration pattern and fluid distribution under actual working conditions is further realized.

9. A visualization test method for porous medium displacement under different gravities according to claim 8, characterized in that: The specific content of the above-mentioned step S2 is: Use the plastic syringe (3) in the displacement injection module (Ⅲ) to inject the stained native fluid into the microfluidic chip (20) until it is saturated. Remove the plastic syringe (3) filled with the stained native fluid, switch to another plastic syringe filled with the displacement fluid and install it on the injection pump (4). Connect the outlet of the plastic syringe (3) to the inlet (17) at the bottom of the microfluidic chip (20), and connect the outlet (19) at the top of the microfluidic chip (20) to the fluid collection device (5). Adjust the angle and position of the industrial camera (2) in the image acquisition module (Ⅳ) according to the inclination angle of the microfluidic chip (20).

10. A visualization test method for porous medium displacement under different gravities according to claim 8, characterized in that: Under microgravity conditions, the specific steps of the above-mentioned step S3 are as follows: Adjust the microfluidic chip (20) to a preset tilt angle, then start the injection pump (4) using the controller (Ⅴ), so that the injection pump (4) pushes the plastic syringe (3) to inject the displacement fluid into the microfluidic chip (20) at a constant speed and constant pressure, and use the image acquisition module (Ⅳ) to collect the optical image information of the microfluidic chip (20) during the fluid displacement process in real time; Under hypergravity conditions, the specific steps of step S3 are as follows: Start the centrifuge (Ⅵ), when the centrifugal acceleration reaches N times the gravitational acceleration, use the controller (Ⅴ) to control the injection pump (4) to push the plastic syringe (3) to inject the displacement fluid into the microfluidic chip (20) at a constant speed and constant pressure, and use the image acquisition module (Ⅳ) to collect the optical image information of the microfluidic chip (20) during the fluid displacement process in real time.

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