A microfluidic chip device and experimental method suitable for visualizing oil displacement experiments
By using microfluidic chip devices and digital modeling technology, the problems of poor microscopic observation and repeatability in traditional core experiments have been solved, enabling real-time observation and experimental repeatability of microscopic residual oil in the pores, and providing a platform for the study of oil displacement mechanisms at the microscale.
Patent Information
- Application Number
- CN202510575622.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-06
- Publication Date
- 2026-11-06
AI Technical Summary
Traditional core flooding experiments cannot observe the initiation, migration and retention of microscopic residual oil in the pores in real time. Inconsistent pore structure characteristics lead to poor experimental repeatability, cores cannot be reused, and it is difficult to simulate the seepage state of low-permeability layers in actual oil reservoirs.
The device employs a microfluidic chip, including a microfluidic chip, chip fixture, displacement system, image acquisition system, and image analysis system. It accurately constructs the pore structure through digital modeling, observes fluid seepage in real time using a microscope and a high-speed camera, enables complex injection modes through the displacement system, and adjusts parameters in real time through the image analysis system.
It enables real-time visualization of microscopic residual oil within the pores, ensuring experimental repeatability and reusability, simulating different reservoir types, and providing a platform for studying oil displacement mechanisms at the microscale.
Smart Images
Figure CN123038901A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of microscopic oil displacement experimental technology, and in particular to a microfluidic chip device and experimental method suitable for visual oil displacement experiments. Background Technology
[0002] In the field of oil extraction, especially in the research of tertiary oil recovery technology, a deep understanding of the seepage laws of oil displacement systems in porous media and the microscopic residual oil mobilization mechanism is crucial. Currently, laboratory core flooding experiments are the mainstream method for studying oil displacement effects. This method involves placing natural cores or cores cast with artificial resin in a holder for displacement, and relying on the changes in water content, oil content, and pressure of the produced fluid to macroscopically evaluate the efficiency of the oil displacement system. However, this method has significant drawbacks and is difficult to meet the research needs of modern fine reservoir development.
[0003] The main problems with existing technologies: 1. Traditional core experiments can only indirectly infer the oil displacement effect through macroscopic parameters, and cannot observe the initiation, migration and retention of microscopic residual oil in the pore in real time.
[0004] 2. Natural cores are affected by differences in reservoir properties, resulting in significant individual differences in pore radius, throat size, and pore-throat combination. Although artificial resin cores can partially simulate pore structure, the casting process limits the precise control of pore-throat parameters. Inconsistent experimental conditions lead to incomparable results from parallel experiments, making it impossible to accurately quantify the impact of pore structure on oil displacement and hindering the understanding of the regularity of oil displacement mechanisms.
[0005] 3. During the displacement process, the polymers, surfactants, salts, and other components in the composite system undergo irreversible changes in the pore structure inside the core due to shearing, rock adsorption, and mineral carrying. The cores are then discarded after the experiment, resulting in high costs per use and the inability to reproduce the same pore conditions. This resource waste is particularly pronounced when multiple rounds of comparative experiments are required.
[0006] 4. Traditional core holders have a fixed injection and production direction, making it difficult to overcome the influence of gravity on fluid seepage. Furthermore, the control accuracy of injection flow rate and pressure is limited, making it impossible to simulate the low-velocity seepage state of low-permeability layers in actual oil reservoirs, resulting in deviations between experimental results and real oil reservoir conditions. Summary of the Invention
[0007] (a) Technical problems to be solved This invention provides a microfluidic chip device and experimental method suitable for visual oil displacement experiments, overcoming the problems of traditional core oil displacement experiments, such as the inability to visualize the initiation and migration process of microscopic residual oil in the pores in real time, poor experimental repeatability due to inconsistent pore structure characteristics, and the inability to reuse cores.
[0008] (II) Technical Solution To achieve the above objectives, the present invention provides a microfluidic chip device suitable for visual oil displacement experiments, comprising: a microfluidic chip, a chip fixture, a displacement system, an image acquisition system, and an image analysis system; The microfluidic chip has a porous structure inside, which includes: a homogeneous porous structure and a heterogeneous porous structure. The chip fixture is used to fix the microfluidic chip. The chip fixture has at least four injection and sampling interfaces. The injection and sampling interfaces can switch the injection direction. The chip fixture is provided with a sealing structure. The sealing structure is used to detachably fix the microfluidic chip. The displacement system includes a micro-flow control pump, an intermediate container, a constant temperature chamber, and a six-way valve. The micro-flow control pump is used to precisely control the fluid flow rate, the intermediate container is used to store different displacement fluids, the constant temperature chamber is used to control the experimental temperature, and the six-way valve is used to switch the injected fluid. The displacement system is connected to the microfluidic chip through an injection-sampling interface. The image acquisition system includes a microscope and a high-speed camera, wherein the high-speed camera is used to capture real-time images of the fluid seepage within the microfluidic chip; The image acquisition system records the fluid seepage within the microfluidic chip in real time; The image analysis system is used to process and analyze the acquired seepage images, calculate the recovery rate, and analyze the distribution and migration patterns of the remaining oil. The image analysis system is connected to both the image acquisition system and the displacement system. The image analysis system receives the acquired images, processes and analyzes them, and feeds back the analysis results to the displacement system to adjust the displacement parameters.
[0009] Preferably, the microfluidic chip is made of ultra-white glass with a light transmittance of ≥90%.
[0010] Preferably, the pore structure is obtained by digitally modeling an image of the pore structure of a real rock core required for the experiment.
[0011] Preferably, the chip fixture includes: a main structure, a cover plate, and a plurality of plugs; The main structure is made of acrylic material, and the center of the main structure has a groove that matches the size of the microfluidic chip. The cover plate matches the size of the main structure and is used to position the microfluidic chip. The main structure and the cover plate are connected by several fixing screws. The injection port passes through the outer wall of the main structure and the groove. The number of plugs matches the number of injection ports. The plugs are used to seal the injection ports.
[0012] Preferably, the flow control range of the micro-flow control pump is 0.00001-25 mL / min, and the pressure range is 10-20000 psi; The micro-flow control pump is connected to the chip fixture via an injection line.
[0013] Preferably, the microscope is equipped with a zoom lens that supports a magnification range of 0.8x to 5.6x, a zoom ratio of 7, and an inverted light source. Combined with the inverted light source design, the total magnification can reach 4.0x to 366x. The high-speed camera can capture 1 image per second, and can capture up to 999 images.
[0014] On the other hand, the present invention also provides an experimental method for a microfluidic chip device suitable for visual oil displacement experiments, comprising the following steps: Microfluidic chip pore structure design steps: Step S11: Acquire images of the pore structure of real rock cores and perform black-and-white conversion. Step S12: Perform pore segmentation and editing on the black-and-white image to generate a digital pore model; Step S13: Adjust the porosity and permeability distribution and pore structure characteristic parameters of the digital pore model according to experimental requirements, and output CAD design files; Step S14: Based on the CAD design file, fabricate the microfluidic chip using high-precision CNC technology; Steps for using microfluidic chips and devices: Step S21: Install the microfluidic chip made in step S14 into the chip fixture and fix it with a cover plate; Step S22: Connect the displacement system to the chip fixture, and inject simulated oil into the microfluidic chip through the displacement system to saturate the microfluidic chip with oil. Step S23: Start the displacement system, switch the injection of different oil displacement fluids through the six-way valve, and at the same time capture the seepage image of the fluid in the microfluidic chip in real time through the image acquisition system. Step S24: The acquired seepage images are processed and analyzed using an image analysis system to calculate the recovery rate and analyze the distribution and migration patterns of the remaining oil. Step S25: After the experiment, the microfluidic chip and chip fixture are thoroughly cleaned for reuse.
[0015] Preferably, the channel segmentation and editing in step S12 includes: eliminating redundant channels, supplementing defective channels, and ensuring channel connectivity and reasonable distribution of throats.
[0016] Preferably, the cleaning in step S25 includes: cleaning the microfluidic chip and chip fixture with hot water, then performing vacuum treatment to remove the liquid remaining in the channel, then performing air injection to remove surface water stains, and finally drying in a constant temperature oven.
[0017] Preferably, when injecting the simulated oil in step S22, the simulated oil needs to be heated to reduce its viscosity; When switching to injecting different oil displacement fluids in step S23, the original fluid in the injection pipeline must be drained first.
[0018] (III) Beneficial Effects This invention provides a microfluidic chip device and experimental method suitable for visual oil displacement experiments. It can fully preserve the pore connectivity, pore throat distribution and permeability heterogeneity characteristics of the original core by using digital modeling technology based on real core pore structure images, ensuring that the model pore structure is both close to the actual oil reservoir and has the physical integrity required for the experiment. Digital pore models enable dynamic adjustment of permeability and porosity distribution and pore structure characteristics, simulating a full range of reservoir types from low-permeability tight reservoirs to high-permeability sandstone reservoirs. This flexibility allows researchers to design experimental schemes for specific reservoir characteristics, overcoming the limitations of traditional physical models. By continuously recording the fluid seepage process with a high-speed camera and combining it with microscope magnification, the evolution of the fluid interface, the formation of viscous fingering, and the phenomenon of residual oil retention at the pore scale can be clearly captured, providing direct evidence for the study of microscopic oil displacement mechanisms. The displacement system switches the injection fluid through a six-way valve and, combined with a micro-flow control pump, can realize complex injection modes such as slug drive and alternating drive. The image analysis system feeds back the remaining oil distribution data to the displacement system in real time and automatically adjusts parameters such as injection flow rate and pressure, thereby achieving the goal of providing a microscale research platform for oil and gas field development. Attached Figure Description
[0019] Figure 1 This diagram illustrates the structure of a microfluidic chip device suitable for visual oil displacement experiments according to the present invention. Figure 2 This invention illustrates a flowchart of the pore structure design steps for a microfluidic chip device suitable for visual oil displacement experiments. Figure 3 This invention illustrates a flowchart of the steps for using a microfluidic chip device suitable for visual oil displacement experiments. Figure 4 The diagram shows the structure of the microfluidic chip and chip fixture of the present invention. Detailed Implementation
[0020] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. The technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0021] In the description of this invention, it is necessary to understand that the orientations or positional relationships indicated by terms such as "upper," "lower," "left," "right," "inner," "outer," "top," and "bottom" are based on the orientations or positional relationships shown in the accompanying drawings. They are intended only to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the components referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.
[0022] like Figure 1-4 As shown, the present invention provides a microfluidic chip device suitable for visual oil displacement experiments, comprising: a microfluidic chip, a chip fixture, a displacement system, an image acquisition system, and an image analysis system; The microfluidic chip has an internal pore structure, which includes a homogeneous pore structure and a heterogeneous pore structure. The homogeneous pore structure provides an experimental environment for basic seepage theory research by constructing an idealized model with uniform permeability distribution, ensuring that users can focus on the basic laws of fluid transport under single permeability conditions. The heterogeneous pore structure replicates the interlayer permeability differences, pore throat coordination number inhomogeneity, and pore connectivity differences of real oil reservoirs, thus constructing a complex seepage environment that closely resembles the actual reservoir. This microfluidic chip uses B270i ultra-white glass as the substrate material. The optical and physical properties of B270i ultra-white glass provide key support for visualization experiments. Its high transmittance ensures that the image acquisition system can clearly capture the details of fluid seepage at the pore scale, reduce image distortion caused by light refraction and scattering, and meet the high-precision observation requirements for dynamic processes such as viscous fingering and oil droplet deformation. Ultra-white glass has excellent high temperature resistance, high pressure resistance and chemical stability, and can withstand the temperature control of the constant temperature chamber and the pressure loading of the displacement system in the experiment. At the same time, it resists the long-term corrosion of the oil displacement fluid and ensures the structural integrity of the chip in repeated experiments.
[0023] The chip fixture is used to fix the microfluidic chip. The chip fixture has at least four injection ports, which are evenly arranged. The injection direction can be switched through the injection ports to achieve bottom-up injection, overcoming the influence of gravity on fluid seepage in traditional core experiments. The chip fixture is equipped with a sealing structure for detachable fixation of the microfluidic chip. The chip fixture includes: a main structure, a cover plate and several plugs. The main structure is made of acrylic material, which is lightweight, highly transparent and chemically stable. The high light transmittance of acrylic material complements the ultra-white glass substrate of the microfluidic chip, ensuring that the microscope and high-speed camera can observe the inside of the chip from the entire field of view without blind spots. The main structure has a groove in the center that matches the size of the microfluidic chip. The central groove is strictly matched with the size of the microfluidic chip to form an embedded installation structure, ensuring that the chip has no displacement deviation during the experiment and avoiding image acquisition distortion or changes in fluid flow path due to positional displacement. The cover plate matches the dimensions of the main structure. The cover plate is used to position the microfluidic chip. The cover plate applies uniform pressure to the chip surface and, together with the sealing structure, forms a reliable fluid seal at the injection interface. It can withstand high-pressure injection from the displacement system without leakage, while also preventing chip damage due to overtightening of screws. This sealing structure fixes the chip by physical clamping rather than adhesive, avoiding the influence of adhesive on the optical properties of the chip surface. At the same time, it ensures that the chip can be completely disassembled after the experiment, which is convenient for cleaning and reuse. The sealing structure can adjust the sealing strength according to the screw tightening force, and can maintain zero leakage in both low-pressure and high-pressure scenarios, adapting to the pressure conditions of different oil displacement systems. The main structure and the cover plate are connected by several fixing screws. The screw fixing method supports the installation and removal of the chip. The injection interface runs through the outer wall and groove of the main structure. The plug corresponds to the injection interface one by one. Unused ports can be sealed by the plug to prevent external impurities from entering or fluid leakage. At the same time, it supports temporary changes to the injection path during the experiment without disassembling the whole device.
[0024] The displacement system includes: a micro-flow control pump, an intermediate container, a thermostatic chamber, and a six-way valve. The micro-flow control pump is used to precisely control the fluid flow rate, the intermediate container is used to store different displacement fluids, the thermostatic chamber is used to control the experimental temperature, and the six-way valve is used to switch the injected fluid. The displacement system is connected to the microfluidic chip via the injection-production interface. The flow control range of the microflow control pump is 0.00001-25 mL / min, and the pressure range is 10-20000 psi. The microflow control pump can be precisely controlled within a very small flow range. When simulating low-permeability reservoirs, it can provide extremely low flow rates to accurately reflect the slow flow of fluid in tiny pores. When simulating high-permeability reservoirs or conducting rapid displacement experiments, it can provide larger flow rates. This intermediate container is used in the displacement system to store different oil displacement fluids, providing a variety of oil displacement media options for experiments. The intermediate container adopts a sealed design, which can effectively prevent external impurities from entering and ensure the purity and property stability of the stored oil displacement fluids. The main function of this constant temperature chamber is to control the experimental temperature and provide a stable temperature environment for oil displacement experiments. The constant temperature chamber can precisely control the temperature within the set range according to the experimental requirements. Temperature has a significant impact on the physical properties of fluids and the properties of reservoir rocks. Precise temperature control can simulate the formation temperature conditions of different reservoirs and ensure that the experimental results are consistent with the actual situation. This six-way valve can switch between different fluid channels in a short time, ensuring that the injected oil displacement fluid can be changed quickly during the experiment. During the switching process, it can ensure the sealing between each channel and prevent mutual leakage and contamination between different oil displacement fluids. The displacement system is connected to the microfluidic chip through the injection-sampling interface, forming a complete experimental system. The microflow control pump is connected to the chip fixture through the injection pipeline, accurately delivering the oil displacement fluid to the microfluidic chip. The various components cooperate with each other and work together to complete the various tasks of the oil displacement experiment.
[0025] This image acquisition system includes a microscope and a high-speed camera. The microscope is equipped with a zoom lens supporting a magnification range of 0.8x to 5.6x, with a zoom ratio of 7. Combined with an inverted light source design, the total magnification can reach 4.0x to 366x, providing ideal conditions for observing the microscopic world within microfluidic chips. The inverted light source illuminates the chip from below, effectively reducing interference from light reflection and scattering, resulting in clearer images with higher contrast. Different magnifications can meet diverse observation needs; at low magnification, a large seepage area can be observed, allowing for rapid location of regions of interest, while at high magnification, the focus can be on tiny pore structures, clearly capturing subtle changes in fluid flow within the pores. This high-speed camera plays a crucial role in capturing real-time images of fluid flow within microfluidic chips. Capable of capturing one image per second, with a maximum capacity of 999 images, it is sufficient to capture various dynamic changes during the fluid flow process. In oil displacement experiments, fluid flow is a complex and dynamic process involving multiple aspects such as fluid propulsion, oil droplet migration, and interface changes. The high-speed camera can record these moments at an appropriate frame rate, providing rich image material for subsequent analysis.
[0026] This image analysis system is used to comprehensively and deeply process and analyze the acquired seepage images. Through image processing and analysis, the image analysis system can accurately calculate the recovery rate in the oil displacement experiment, identify the distribution areas of the oil phase and water phase in the image, and accurately calculate the amount of oil displaced based on the initial oil saturation and the distribution of the remaining oil after displacement, thereby obtaining the recovery rate. The image analysis system is closely connected to the image acquisition system and the displacement system, forming a closed-loop feedback mechanism. It receives images acquired by the image acquisition system, processes and analyzes them, and then feeds the analysis results back to the displacement system. The displacement system can adjust the displacement parameters, such as flow rate, pressure, and type of injected fluid, in a timely manner based on this feedback information.
[0027] The experimental method for the microfluidic chip device used for visualizing oil displacement experiments is characterized by the following steps: Microfluidic chip pore structure design steps: Step S11: Acquire images of the pore structure of real rock cores and perform black-and-white conversion. Obtain images of real core castings or three-dimensional pore structures using microscopes or CT scans, preserving the original core's pore throat morphology, coordination number, and connectivity characteristics to ensure the geological authenticity of subsequent modeling. Black-and-white processing transforms complex grayscale images into clear binary structures, providing basic data for accurate segmentation and avoiding pore identification errors caused by noise interference.
[0028] Step S12: Perform pore segmentation and editing on the black-and-white image to generate a digital pore model; Eliminate redundant channels and supplement defective channels. By repairing broken channels and connecting narrow throats, ensure channel connectivity and reasonable throat distribution, and avoid abnormal fluid seepage caused by model defects.
[0029] Step S13: Adjust the permeability distribution and pore throat parameters of the digital pore model according to experimental requirements, and output the CAD design file; By adjusting the channel width, throat length, and connectivity density, homogeneous and heterogeneous models are constructed. The location and size of the injection and sampling interfaces are clearly defined in the CAD design, and the sealing structure of the chip fixture is matched. At the same time, blank areas at the edges are reserved to avoid the refraction of fluid at the chip boundary from interfering with image acquisition, thus ensuring the integrity of the effective experimental area.
[0030] Step S14: Fabricate the microfluidic chip based on the CAD design file; The CAD model is transformed into a solid pore structure with micron-level precision by using ultra-white glass CNC precision machining and photolithography or laser etching technology. This ensures that the depth and width errors of the pores meet the requirements of the structural clarity for visualization observation. The chip surface is modified to be hydrophilic or hydrophobic according to experimental needs.
[0031] Steps for using microfluidic chips and devices: Step S21: Install the microfluidic chip made in step S14 into the chip fixture and fix it with a cover plate; Step S22: Connect the displacement system to the chip fixture, connect the injection line to the injection port of the chip fixture, and inject simulated oil into the microfluidic chip through the displacement system to saturate the microfluidic chip with oil. It should be noted that the simulated oil needs to be heated to reduce its viscosity before injection.
[0032] Step S23: Start the displacement system, switch the injection of different oil displacement fluids through the six-way valve, and at the same time capture the seepage image of the fluid inside the microfluidic chip in real time through the image acquisition system. It should be noted that under normal circumstances, water flooding is carried out first. After the recovery rate in the microfluidic chip reaches a certain level, the system will be switched to polymer or composite flooding system. Before switching the oil displacement fluid, flush the pipeline with a large flow rate through a six-way valve to ensure that the residual fluid is completely discharged, avoid the mixing of different oil displacement agents in the pipeline to cause precipitation or viscosity loss, and ensure the purity of the fluid properties injected into the chip.
[0033] Step S24: The acquired seepage images are processed and analyzed using an image analysis system to calculate the recovery rate and analyze the distribution and migration patterns of the remaining oil. The image analysis system simulates fluid transport paths using streamline tracing technology, revealing seepage bottlenecks at the pore throat scale.
[0034] Step S25: After the experiment, the microfluidic chip and chip fixture are cleaned for reuse. When cleaning microfluidic chips and chip fixtures, for the simulated oil remaining in the pipes inside the fixture, kerosene is first used to clean it to dissolve the oil residue, and then it is rinsed with clean water. Use hot water to clean the microfluidic chip and fixture body in both directions, and use a soft brush to gently brush the grooves of the fixture to remove mechanical impurities; After cleaning, vacuuming is used to vaporize and discharge the liquid remaining in the channels, avoiding bacterial growth or mineral precipitation caused by moisture residue. Air is injected and blown to remove surface water stains, preventing water spots from forming during the drying process and affecting the chip's light transmittance. After drying, the chip pores are inspected under a microscope for blockage or damage, and the airtightness of the fixture sealing structure is tested to ensure the consistency of experimental conditions during repeated use and reduce the cost of consumables.
[0035] It is understood that the various embodiments mentioned above in this invention can be combined with each other to form combined embodiments without violating the principle and logic. Due to space limitations, this invention will not elaborate further.
[0036] Those skilled in the art will understand that, in the above-described method of the specific implementation, the order in which each step is written does not imply a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic.
[0037] The present invention provides a microfluidic chip device and experimental method suitable for visual oil displacement experiments. Through digital modeling technology based on real core pore structure images, it fully preserves the pore connectivity, pore throat distribution and permeability heterogeneity characteristics of the original core, ensuring that the model is both faithful to the actual reservoir and has the physical integrity required for the experiment. Digital pore models enable dynamic adjustment of permeability distribution and pore throat parameters, simulating a full range of reservoir types from low-permeability tight reservoirs to high-permeability sandstone reservoirs. This flexibility allows researchers to design experimental schemes for specific reservoir characteristics, overcoming the limitations of traditional physical models. By continuously recording the fluid seepage process with a high-speed camera and combining it with microscope magnification, the evolution of the fluid interface, the formation of viscous fingering, and the phenomenon of residual oil retention at the pore scale can be clearly captured, providing direct evidence for the study of microscopic oil displacement mechanisms. The displacement system switches the injection fluid through a six-way valve and, combined with a micro-flow control pump, can realize complex injection modes such as slug drive and alternating drive. The image analysis system feeds back the remaining oil distribution data to the displacement system in real time and automatically adjusts parameters such as injection flow rate and pressure, thereby achieving the goal of providing a microscale research platform for oil and gas field development.
[0038] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.
Claims
1. A microfluidic chip device suitable for visual oil displacement experiments, characterized in that, include: Microfluidic chips, chip fixtures, displacement systems, image acquisition systems, and image analysis systems; The microfluidic chip has a porous structure inside, which includes: a homogeneous porous structure and a heterogeneous porous structure. The chip fixture is used to fix the microfluidic chip. The chip fixture has at least four injection and sampling interfaces. The injection and sampling interfaces can switch the injection direction. The chip fixture is provided with a sealing structure. The sealing structure is used to detachably fix the microfluidic chip. The displacement system includes a micro-flow control pump, an intermediate container, a constant temperature chamber, and a six-way valve. The micro-flow control pump is used to precisely control the fluid flow rate, the intermediate container is used to store different displacement fluids, the constant temperature chamber is used to control the experimental temperature, and the six-way valve is used to switch the injected fluid. The displacement system is connected to the microfluidic chip through an injection-sampling interface. The image acquisition system includes a microscope and a high-speed camera, wherein the high-speed camera is used to capture real-time images of the fluid seepage within the microfluidic chip; The image acquisition system records the fluid seepage within the microfluidic chip in real time; The image analysis system is used to process and analyze the acquired seepage images, calculate the recovery rate, and analyze the distribution and migration patterns of the remaining oil. The image analysis system is connected to both the image acquisition system and the displacement system. The image analysis system receives the acquired images, processes and analyzes them, and feeds back the analysis results to the displacement system to adjust the displacement parameters.
2. The microfluidic chip device suitable for visual oil displacement experiments according to claim 1, characterized in that, The microfluidic chip is made of ultra-white glass with a light transmittance of ≥90%.
3. The microfluidic chip device suitable for visual oil displacement experiments according to claim 1, characterized in that, The pore structure is obtained by digitally modeling the pore structure image of the actual rock core required for the experiment.
4. The microfluidic chip device suitable for visual oil displacement experiments according to claim 1, characterized in that, The chip fixture includes: a main structure, a cover plate, and several plugs; The main structure is made of acrylic material, and the center of the main structure has a groove that matches the size of the microfluidic chip. The cover plate matches the size of the main structure and is used to position the microfluidic chip. The main structure and the cover plate are connected by several fixing screws. The injection port passes through the outer wall of the main structure and the groove. The number of plugs matches the number of injection ports. The plugs are used to seal the injection ports.
5. The microfluidic chip device suitable for visual oil displacement experiments according to claim 1, characterized in that, The flow control range of the micro-flow control pump is 0.00001-25 mL / min, and the pressure range is 10-20000 psi; The micro-flow control pump is connected to the chip fixture via an injection line.
6. The microfluidic chip device suitable for visual oil displacement experiments according to claim 1, characterized in that, The microscope is equipped with a zoom lens that supports a magnification range of 0.8x to 5.6x and a zoom ratio of 7. The microscope light source is an inverted light source. Combined with the inverted light source design, the total magnification can reach 4.0x to 366x. The high-speed camera can capture 1 image per second, and can capture up to 999 images.
7. The experimental method of the microfluidic chip device suitable for visual oil displacement experiments according to any one of claims 1-6, characterized in that, Includes the following steps: Microfluidic chip pore structure design steps: Step S11: Acquire images of the pore structure of real rock cores and perform black-and-white conversion. Step S12: Perform pore segmentation and editing on the black-and-white image to generate a digital pore model; Step S13: Adjust the porosity and permeability distribution and pore structure characteristic parameters of the digital pore model according to experimental requirements, and output CAD design files; Step S14: Based on the CAD design file, fabricate the microfluidic chip using high-precision CNC technology; Steps for using microfluidic chips and devices: Step S21: Install the microfluidic chip made in step S14 into the chip fixture and fix it with a cover plate; Step S22: Connect the displacement system to the chip fixture, and inject simulated oil into the microfluidic chip through the displacement system to saturate the microfluidic chip with oil. Step S23: Start the displacement system, switch the injection of different oil displacement fluids through the six-way valve, and at the same time capture the seepage image of the fluid in the microfluidic chip in real time through the image acquisition system. Step S24: The acquired seepage images are processed and analyzed using an image analysis system to calculate the recovery rate and analyze the distribution and migration patterns of the remaining oil. Step S25: After the experiment, the microfluidic chip and chip fixture are thoroughly cleaned for reuse.
8. The experimental method of the microfluidic chip device suitable for visual oil displacement experiments according to claim 7, characterized in that, The channel segmentation and editing in step S12 includes: eliminating redundant channels, supplementing defective channels, and ensuring channel connectivity and reasonable throat distribution.
9. The experimental method of the microfluidic chip device suitable for visual oil displacement experiments according to claim 7, characterized in that, The cleaning process in step S25 includes: cleaning the microfluidic chip and chip fixture with hot water, then performing vacuum treatment to remove the liquid remaining in the channel, then performing air injection and purging to remove surface water stains, and finally drying in a constant temperature oven.
10. The experimental method of the microfluidic chip device suitable for visual oil displacement experiments according to claim 7, characterized in that, When injecting the simulated oil in step S22, the simulated oil needs to be heated to reduce its viscosity; When switching to injecting different oil displacement fluids in step S23, the original fluid in the injection pipeline must be drained first.