Foaming and displacement integrated micro-fluidic chip as well as microcosmic visual experimental device and method

Abstract

The invention relates to the technical field of oil and gas field development, and discloses a foaming and displacement integrated micro-fluidic chip and a microcosmic visual experimental device and method.The chip comprises a premixing area, a Venturi tube structure, a foaming area and a displacement experimental area which are sequentially connected in the fluid flowing direction; a herringbone baffle structure is installed in the bubbling area and comprises a plurality of bent baffles arranged in a staggered mode. The device comprises a reaction kettle, a fluid injection system, a temperature and pressure control system, a fluid treatment system and a data acquisition and video recording system, a foaming and displacement integrated micro-fluidic chip is mounted in the reaction kettle; the fluid injection system is used for injecting gas and liquid foaming agents into the premixing area. By adopting an integrated structure, the migration distance from foam to a porous medium is reduced, the visualization of the whole efficient foaming and displacement process is realized, foam generation can be simulated and observed more truly, and the foam flooding effect can be evaluated more truly and more efficiently.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field development technology, and in particular to an integrated microfluidic chip for foaming and displacement, and experimental apparatus and methods for microscopic visualization. Background Technology

[0002] Foam flooding generates foam by injecting gas and surfactant solution, creating a Jamin effect in high-permeability layers that blocks large pores. This forces subsequent displacement fluids to redirect to unaffected low-permeability areas, while simultaneously reducing oil-water interfacial tension, thereby increasing sweep efficiency and oil washing efficiency, and ultimately enhancing oil production. Microscopic experiments directly observe the dynamic behavior of foam generation, migration, blocking, and collapse in porous media, revealing the physical essence of its control over fluid flow and enhancement of oil recovery at the pore scale, providing key mechanistic support for macroscopic oil displacement strategies.

[0003] Current common foam flooding experiments involve pre-preparing foam in a separate foaming device and then pumping it into the displacement system via a long connecting pipeline. This "split-type" experimental process has significant technical drawbacks: during the long-distance pipeline transport, the foam is affected by various physical forces such as shearing and compression, leading to significant changes and attenuations in its structure, particle size distribution, and stability. The foam that finally enters the displacement zone is no longer in its initial state, failing to accurately reflect the foam's original generation capacity and dynamic plugging and displacement behavior in porous media, thus affecting foam evaluation and the effectiveness of the displacement experiment. Furthermore, in the foam generation stage, traditional foaming methods often face problems such as low foaming efficiency, poor foam uniformity, or high energy consumption. There is still room for improvement in the one-time mixing efficiency within a limited space. In addition, while gas displacement experiments can be conducted using experimental setups, they cannot monitor the generation and transport process of CO2 foam or efficiently prepare CO2 foam, limiting their ability to reveal the microscopic mechanisms of CO2 foam displacement and enhanced oil recovery.

[0004] To address this, we propose an integrated microfluidic chip for foaming and displacement, along with a microscopic visualization experimental setup and method. Summary of the Invention

[0005] The purpose of this invention is to provide an integrated bubble-displacement microfluidic chip, a microscopic visualization experimental apparatus and method, which aims to solve or improve at least one of the above-mentioned technical problems.

[0006] To achieve the above objectives, the present invention provides the following solution: The present invention provides a foaming and displacement integrated microfluidic chip, comprising a premixing region, a Venturi tube structure, a foaming region and a displacement experimental region connected sequentially along the fluid flow direction; A herringbone baffle structure is installed in the bubbling area, and the herringbone baffle structure includes several staggered curved baffles.

[0007] According to the foaming and displacement integrated microfluidic chip provided by the present invention, the premixing region includes a liquid phase channel and a gas phase channel, both of which are connected to the Venturi tube structure via pipelines.

[0008] According to the integrated foaming and displacement microfluidic chip provided by the present invention, the displacement experimental area includes a foam channel, a displacement area, and a fluid outlet channel; the foam channel and the fluid outlet channel are respectively installed on both sides of the displacement area, and the foam channel is connected to the foaming area.

[0009] This invention also provides a microscopic visualization experimental apparatus for constructing a bubble-displacement integrated microfluidic chip, comprising: The reaction vessel is equipped with an integrated microfluidic chip for foaming and displacement. A fluid injection system is used to inject gaseous and liquid foaming agents into the premixing zone; A temperature and pressure control system, which is used to regulate the temperature and pressure inside the reactor; A fluid processing system for gas-liquid separation of the fluid discharged from the displacement experimental zone; A data acquisition and recording system is installed on the reactor and is used to acquire and transmit images of the reactor's temperature, pressure, and displacement.

[0010] According to the experimental apparatus for microscopic visualization provided by the present invention, the fluid injection system includes: A gas cylinder, which is connected to the premixing zone via a gas supply pipe; A liquid injection pump, which is connected to the premixing zone via a liquid supply pipeline; A first valve is installed on the liquid supply pipeline; The second valve is installed on the gas supply pipeline.

[0011] According to the microscopic visualization experimental apparatus provided by the present invention, the temperature and pressure control system includes: A heater, which is installed on the reactor, is used to regulate the temperature inside the reactor; A confining pressure pump, wherein the confining pressure pump is connected to the inner cavity of the reactor via a pressure regulating pipe; The pressure regulating pipeline is equipped with a third valve and a first pressure gauge.

[0012] According to the experimental apparatus for microscopic visualization provided by the present invention, the fluid handling system includes: A gas-liquid separator, wherein the feed end of the gas-liquid separator is connected to the discharge end of the displacement experimental zone via a discharge pipe; A waste gas cylinder, wherein the waste gas cylinder is installed at the exhaust end of the gas-liquid separator; Waste liquid tank, which is installed at the drain end of the gas-liquid separator; The discharge pipe is equipped with a fifth valve, and a back pressure pipe is connected to the discharge pipe via a back pressure valve. The back pressure pipe is equipped with a back pressure pump, a fourth valve, and a second pressure gauge.

[0013] According to the experimental apparatus for microscopic visualization provided by the present invention, the data acquisition and recording system includes an electronic thermometer, a pressure sensor, a high-speed camera, and a data collection system. The electronic thermometer and the high-speed camera are both installed on the reaction vessel, and the pressure sensor is installed on the discharge pipe. The electronic thermometer, the pressure sensor, and the high-speed camera are all electrically connected to the data collection system.

[0014] This invention also provides an experimental method for microscopic visualization, comprising the following steps: Step 1: Install the integrated foaming and displacement microfluidic chip inside the reactor; Step 2: Use the temperature and pressure control system to adjust the temperature and pressure inside the reactor; Step 3: Inject a gas-liquid two-phase fluid into the premixing zone using a fluid injection system, and form a steady-state gas-liquid stratified flow by controlling the flow rate ratio of the two phases; the gas-liquid stratified flow includes initial spherical bubbles; Step 4: When the gas-liquid stratified flow enters the Venturi tube structure, the gas-liquid stratified flow is subjected to shear force and transitions from a steady state to a turbulent state. Then, several staggered curved baffles are used to generate transverse secondary flow vortices and chaotic convection in the fluid, forming microbubbles. Step 5: After the microbubbles enter the displacement experimental zone, the temperature, pressure and displacement images of the reactor are collected and transmitted using a data acquisition and recording system. Then, the fluid discharged from the displacement experimental zone is separated into gas and liquid using a fluid processing system to complete the microscopic visualization displacement experiment.

[0015] The present invention discloses the following technical effects: This invention improves fluid shear efficiency through a venturi tube structure and a herringbone baffle structure, reduces foam breakage caused by migration, and enhances the stability, continuity, and uniformity of the foam used for displacement. It can improve foam quality, achieve uniform and efficient displacement, realize efficient foaming, and evaluate the foam displacement effect more realistically and efficiently. This invention replaces the foam generator, microfluidic chip (core holder, core), and intermediate connecting pipelines in traditional foam displacement experiments with an integrated foam displacement microfluidic chip. The integrated structure reduces the transport distance of foam to porous media, enabling more realistic simulation and observation of foam generation, optimizing experimental equipment, and simplifying experimental operations. This invention uses a data acquisition and recording system and an integrated microfluidic chip for foam generation and displacement to visualize the entire process of foam generation and displacement, enabling further research on the foam seepage mechanism and displacement characteristics. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of the microscopic visualization experimental device of the present invention; Figure 2 This is a schematic diagram of the structure of the integrated bubble-displacement microfluidic chip of the present invention.

[0018] Among them, 2. Reactor; 3. Heater; 4. Back pressure valve; 5. Electronic thermometer; 6. High-speed camera; 7. Data collection system; 8. Gas-liquid separator; 9. Confining pressure pump; 10. Gas cylinder; 11. Liquid injection pump; 12. Back pressure pump; 13. Pressure sensor; 14. First pressure gauge; 15. Second pressure gauge; 16. First valve; 17. Second valve; 18. Third valve; 19. Fourth valve; 20. Fifth valve; 21. Waste gas cylinder; 22. Waste liquid tank; 23. Liquid phase channel; 24. Gas phase channel; 25. Venturi tube structure; 26. Bubbling zone; 27. Displacement experimental zone. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Reference Figures 1-2The present invention provides a microfluidic chip integrating foaming and displacement, comprising a premixing region, a Venturi tube structure 25, a foaming region 26 and a displacement experimental region 27 connected sequentially along the fluid flow direction; the Venturi tube structure 25, the foaming region 26 and the displacement experimental region 27 are fabricated using silicon dioxide (SiO2) through a standard glass etching process and bonded and sealed. A herringbone baffle structure is installed in the bubbling zone 26. The herringbone baffle structure includes several staggered curved baffles. With this configuration, the present invention improves fluid shear efficiency through the Venturi tube structure 25 and the herringbone baffle structure, reduces foam breakage caused by migration, and enhances the stability, continuity and uniformity of the foam used for displacement. This improves foam quality, achieves uniform and efficient displacement, realizes efficient foaming, and allows for a more realistic and efficient evaluation of the foam displacement effect. This invention replaces the foam generator, microfluidic chip (core holder, core), and intermediate connecting pipelines in traditional foam displacement experiments with an integrated foam displacement microfluidic chip. The integrated structure reduces the transport distance of foam to porous media, enabling more realistic simulation and observation of foam generation, optimizing experimental equipment, and simplifying experimental operations. This invention uses a data acquisition and recording system and an integrated microfluidic chip for foam generation and displacement to visualize the entire process of foam generation and displacement, enabling further research on the foam seepage mechanism and displacement characteristics.

[0022] The scheme is further optimized so that the premixing zone includes a liquid phase channel 23 and a gas phase channel 24, both of which are connected to the Venturi tube structure 25 via pipelines.

[0023] The scheme is further optimized. The displacement test zone 27 includes a foam channel, a displacement zone, and a fluid outlet channel. The foam channel and the fluid outlet channel are installed on both sides of the displacement zone, and the foam channel is connected to the foaming zone 26. The foam generated in the foaming zone 26 enters the displacement zone through the foam channel to complete the displacement process, and is discharged through the fluid outlet channel.

[0024] The present invention also provides an experimental apparatus for microscopic visualization, comprising: Reactor 2, which is equipped with an integrated microfluidic chip for foaming and displacement; a visualization window is provided on reactor 2. A fluid injection system is used to inject gaseous and liquid foaming agents into the premixing zone; Temperature and pressure control system, used to regulate the temperature and pressure inside reactor 2; A fluid processing system is used to perform gas-liquid separation on the fluid discharged from the displacement experimental zone 27. The data acquisition and recording system is installed on the reactor 2 and is used to acquire and transmit images of the temperature, pressure and displacement of the reactor 2.

[0025] Further optimization of the scheme includes the following fluid injection system: Gas cylinder 10 is connected to the premixing zone via a gas supply pipeline; Liquid injection pump 11 is connected to the premixing zone via a liquid supply pipeline; First valve 16, first valve 16 is installed on the liquid supply pipeline; The second valve 17 is installed on the gas supply pipeline.

[0026] Further optimization of the scheme, the temperature and pressure control system includes: Heater 3 is installed on reactor 2 and is used to regulate the temperature inside reactor 2; Confining pressure pump 9 is connected to the inner cavity of reactor 2 through a pressure regulating pipe. Confining pressure pump 9 injects gas into reactor 2 to control the confining pressure. The pressure regulating pipeline is equipped with a third valve 18 and a first pressure gauge 14.

[0027] Further optimization of the solution, the fluid handling system includes: The gas-liquid separator 8 has its feed end connected to the discharge end of the displacement test zone 27 via a discharge pipe. Waste gas cylinder 21 is installed at the exhaust end of gas-liquid separator 8; Waste liquid tank 22 is installed at the drain end of gas-liquid separator 8; The discharge pipe is equipped with a fifth valve 20, and a back pressure pipe is connected to the discharge pipe through a back pressure valve 4. The back pressure pipe is equipped with a back pressure pump 12, a fourth valve 19, and a second pressure gauge 15. The displaced fluid enters the gas-liquid separator 8 through the fluid outlet channel of the microfluidic chip for separation. The separated gas and liquid enter 21 and the waste liquid tank 22 for collection, respectively.

[0028] The scheme was further optimized. The data acquisition and recording system includes an electronic thermometer 5, a pressure sensor 13, a high-speed camera 6, and a data collection system 7. The electronic thermometer 5 and the high-speed camera 6 are both installed on the reactor 2, and the pressure sensor 13 is installed on the discharge pipe. The electronic thermometer 5, the pressure sensor 13, and the high-speed camera 6 are all electrically connected to the data collection system 7. In this embodiment, the data collection system 7 uses a computer, the electronic thermometer 5 is used to collect the temperature data of the reactor 2 during the experiment, the high-speed camera 6 is set at the visualization window of the reactor to collect displacement images during the experiment, the pressure sensor 13 is used to collect outlet pressure and confining pressure data, and the high-speed camera 6 is set at the visualization window of the reactor 2 to collect displacement images during the experiment.

[0029] This invention also provides an experimental method for microscopic visualization, comprising the following steps: Step 1: Install the integrated foaming and displacement microfluidic chip inside the reactor 2; Step 2: Use the temperature and pressure control system to adjust the temperature and pressure inside reactor 2; Step 3: Inject a gas-liquid two-phase fluid into the premixing zone using a fluid injection system. By controlling the flow rate ratio of the two phases, a gas-liquid stratified flow is formed in a steady state. The gas-liquid stratified flow includes initial spherical bubbles. Step 4: When the gas-liquid stratified flow enters the Venturi tube structure 25, the gas-liquid stratified flow is subjected to shear force and transitions from a steady state to a turbulent state. Then, several staggered curved baffles are used to generate transverse secondary flow vortices and chaotic convection in the fluid, forming microbubbles. Step 5: After the microbubbles enter the displacement experimental zone 27, the temperature, pressure and displacement images of the reactor 2 are collected and transmitted using the data acquisition and recording system. Then, the fluid discharged from the displacement experimental zone 27 is separated into gas and liquid using the fluid processing system to complete the microscopic visualization displacement experiment.

[0030] In this embodiment, the Reynolds number of the gas-liquid stratified flow stage in a steady state is determined by controlling the flow rate ratio of the two phases. Re The calculation formula is as follows: (1-1) in, ρ and μ These are the density and viscosity of the liquid phase, respectively. U The average flow velocity within the liquid phase channel 23 and the gas phase channel 24. d h Let be the hydraulic diameter. Under the conditions of this example, the calculation is as follows: Re 1 < 10, the flow is a stable laminar flow.

[0031] When the gas-liquid stratified flow enters the Venturi tube structure 25, according to the continuity equation: (1-2) in A 1 and A 2 represents the cross-sectional area of ​​the inlet and throat, respectively. U 1 andU 2 represents the average flow velocity at the corresponding location. When fluid enters from the inlet of the Venturi tube structure 25 ( A 1) Flows to the throat of Venturi tube structure 25 ( A 2) If the cross-sectional area is reduced to 1 / 4, the flow velocity... U 2. Increase the inlet flow velocity to the venturi tube structure 25. U 1 is 4 times.

[0032] According to Bernoulli's equation (ignoring height difference and viscous loss): (1-3) because U 2>> U 1. Throat pressure of Venturi tube structure 25 P 2 will have an inlet pressure much lower than that of the Venturi tube structure 25. P 1. This low-pressure effect enhances gas entrainment and exerts strong shear forces on the flowing bullet-shaped bubbles, causing them to be stretched and crushed. The local Reynolds number here... Re 2 significantly higher than Re 1. The flow begins to transition to turbulence.

[0033] The herringbone baffle structure is the core of this invention for achieving efficient and precise foaming. In the foaming zone 26, there is a series of periodically arranged asymmetrical herringbone baffle structures (see...). Figure 2 (Enlarged view of the herringbone baffle structure).

[0034] The herringbone baffle structure uses herringbone-shaped baffles, with the two arms of the herringbone baffle being curved baffles with a certain curvature. Several staggered curved baffles form an asymmetrical structure, and several staggered curved baffles constitute one cycle. Several cycles are set within the bubbling zone 26. The function of the herringbone baffle structure is achieved through two key fluid dynamics principles: Induced secondary flow (Dehn vortex): The asymmetric structure of the herringbone baffle is equivalent to introducing continuous, alternating bends in the flow channel, thereby generating strong transverse secondary flow vortices, i.e., Dean vortices. Their intensity is quantified by the Dean number (De): (1-4) in, Re The Reynolds number of this module. d h Let be the hydraulic diameter of the channel, for a rectangular channel. , R c The equivalent radius of curvature of the flow channel is determined by the geometry of the herringbone pattern. In this embodiment, by optimizing the curvature and spacing of the herringbone pattern, the... DeThe number is in the range of 50-200, thus ensuring the generation of sufficiently strong Dean vortices to transport bubbles from the center of the channel to the wall and back, achieving strong lateral mixing and multi-directional shear.

[0035] Inducing chaotic convection: The periodic, asymmetric herringbone structure causes the flow field to exhibit periodic variations in space. As fluid particles (and bubbles) flow through each herringbone, their trajectories are nonlinearly altered. This leads to an exponential separation of the trajectories of adjacent fluid particles over time. This chaotic convection effect efficiently stretches, folds, and breaks up the bubble interface, much faster than simple molecular diffusion.

[0036] After the bubbles that have been initially broken up by the Venturi tube structure 25 enter this module, they are further "torn" and "kneaded" under the combined action of chaotic convection and Dean's vortex, eventually forming microbubbles with uniform size and height.

[0037] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0038] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A bubble-driven displacement integrated microfluidic chip, characterized in that: The pre-mixing area, the Venturi structure (25), the foaming area (26) and the displacement experiment area (27) are sequentially connected along the fluid flow direction. The foaming area (26) is provided with a herringbone baffle structure, and the herringbone baffle structure comprises a plurality of staggered curved baffles.

2. The integrated bubble displacement microfluidic chip according to claim 1, wherein: The pre-mixing area comprises a liquid phase channel (23) and a gas phase channel (24), and the liquid phase channel (23) and the gas phase channel (24) are communicated with the Venturi structure (25) through pipelines.

3. The integrated bubble displacement microfluidic chip according to claim 1, wherein: The displacement experiment area (27) comprises a foam channel, a displacement area and a fluid outlet channel, the foam channel and the fluid outlet channel are respectively arranged on the two sides of the displacement area, and the foam channel is communicated with the foaming area (26).

4. The experimental setup for micro-visualization of bubble displacement integrated microfluidic chip construction according to any one of claims 1-3, characterized in that, The reaction kettle (2) is provided with a foaming and displacement integrated micro-fluidic chip; The fluid injection system is used for injecting gas and liquid foaming agent into the pre-mixing area; The temperature and pressure control system is used for adjusting the temperature and pressure in the reaction kettle (2); The fluid treatment system is used for gas-liquid separation of the fluid discharged from the displacement experiment area (27); The data acquisition and recording system is arranged on the reaction kettle (2) and used for acquiring and transmitting the temperature, pressure and displacement image of the reaction kettle (2). The fluid injection system comprises:

5. The experimental setup for microscopic visualization according to claim 4, characterized in that: The gas cylinder (10) is communicated with the pre-mixing area through a gas supply pipeline; The liquid injection pump (11) is communicated with the pre-mixing area through a liquid supply pipeline; The first valve (16) is arranged on the liquid supply pipeline; The second valve (17) is arranged on the gas supply pipeline. The temperature and pressure control system comprises:

6. The experimental setup for microscopic visualization according to claim 4, characterized in that: The heater (3) is arranged on the reaction kettle (2) and used for adjusting the temperature in the reaction kettle (2); The confining pressure pump (9) is communicated with the inner cavity of the reaction kettle (2) through a pressure regulating pipeline; The third valve (18) and the first pressure gauge (14) are arranged on the pressure regulating pipeline. The fluid treatment system comprises:

7. The experimental setup for microscopic visualization according to claim 4, characterized in that: The gas-liquid separator (8) is communicated with the discharge end of the displacement experiment area (27) through a discharge pipeline; The waste gas cylinder (21) is arranged at the exhaust end of the gas-liquid separator (8); The waste liquid tank (22) is arranged at the liquid discharge end of the gas-liquid separator (8); The fifth valve (20) is arranged on the discharge pipeline, the back pressure pipeline is connected to the discharge pipeline through the back pressure valve (4), the back pressure pump (12), the fourth valve (19) and the second pressure gauge (15) are arranged on the back pressure pipeline. ​ 8. The experimental setup for microscopic visualization according to claim 7, characterized in that: The data acquisition video system comprises an electronic thermometer (5), a pressure sensor (13), a high-speed camera (6) and a data collection system (7), wherein the electronic thermometer (5) and the high-speed camera (6) are both installed on the reaction kettle (2), the pressure sensor (13) is installed on the discharge pipeline, and the electronic thermometer (5), the pressure sensor (13) and the high-speed camera (6) are electrically connected with the data collection system (7).

9. Experimental method of micro-visualization based on the experimental device of micro-visualization according to any one of claims 4 to 8, characterized in that, The method comprises the following steps: Step one, install the foam displacement integrated microfluidic chip in the reaction kettle (2); Step two, adjust the temperature and pressure in the reaction kettle (2) by using a temperature and pressure control system; Step three, inject gas-liquid two-phase fluid into the premixing area by using a fluid injection system, and form gas-liquid stratified flow in a stable state by controlling the flow rate ratio of the two phases; the gas-liquid stratified flow comprises initial slug-shaped bubbles; Step four, when the gas-liquid stratified flow enters the Venturi tube structure (25), the gas-liquid stratified flow is transitioned from a stable state to a turbulent state by the shearing force, then a plurality of staggered arrangement curved baffles are used to make the fluid generate transverse secondary flow vortex and chaotic convection, and micro-bubbles are formed; Step five, when the micro-bubbles enter the displacement experiment area (27), the temperature, pressure and displacement image of the reaction kettle (2) are collected and transmitted by using the data acquisition video system, then the fluid discharged from the displacement experiment area (27) is subjected to gas-liquid separation by using a fluid processing system, and the micro-visualized displacement experiment is completed.

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