A method for real-time calculation of saturation of multiphase flow fluid based on microfluidics technology

Abstract

This application relates to the field of hydrogeology and provides a method for real-time calculation of multiphase flow fluid saturation based on microfluidic technology. The method includes: first, establishing a multiphase flow image dataset; then, cropping original images from different times within the dataset to the target size and rotating them to the target position; identifying the target fluid in the cropped and rotated original images according to a preset RGB range, and adjusting the preset RGB range until the identification result is accurate, identifying the target fluid region; next, generating real-time target fluid saturation data based on the target fluid region; and finally, plotting the saturation evolution curve of the target fluid in the multiphase flow process based on the real-time target fluid saturation data. This improves the accuracy of real-time fluid saturation calculation in multiphase flow displacement and mass transfer processes.

Description

Technical Field

[0001] This application belongs to the field of hydrogeological technology, and in particular relates to a method for real-time calculation of multiphase flow saturation based on microfluidic technology. Background Technology

[0002] Multiphase flow problems in porous and fractured media are widely encountered in natural processes such as carbonate dissolution-precipitation, reservoir seepage prevention and safety control, carbon dioxide geological sequestration, groundwater pollution and remediation, and microbial mineralization technologies, as well as in energy, environmental, and water conservancy projects. In multiphase flow research for oil and gas extraction, quantifying changes in the saturation of the oil or gas phase can clarify the extraction efficiency. In the field of carbon dioxide geological sequestration, quantifying changes in the saturation of gaseous and supercritical carbon dioxide can elucidate the microscopic sequestration mechanism. In the remediation of soil and groundwater pollution caused by non-aqueous liquids, quantifying changes in the saturation of the non-aqueous liquid can reveal the remediation mechanism and thus improve remediation efficiency. Therefore, real-time calculation of fluid saturation in multiphase flow processes is of great significance for studying the microscopic mechanisms of multiphase flow and improving the engineering efficiency of related systems.

[0003] To address the problem of fluid saturation calculation in multiphase flow processes, numerous scholars have employed computed tomography (CT), low-field nuclear magnetic resonance (NMR), and sandbox light transmission experiments for direct measurement or inversion of saturation. However, CT scans are time-consuming, and some displacement or repair reactions occur instantaneously, making it difficult to capture saturation changes in real time. While NMR offers faster imaging, accurately distinguishing between different fluid phases containing protons presents challenges; furthermore, both CT and NMR instruments are expensive. Although sandbox light transmission experiments are cost-effective and fast, their internal structure cannot be directly observed, and inverting fluid saturation through light intensity still introduces errors. Therefore, current methods for calculating fluid saturation in multiphase flow processes suffer from low accuracy. Summary of the Invention

[0004] This application provides a method for real-time calculation of fluid saturation in multiphase flow based on microfluidic technology, which can solve the problem of low accuracy in the current calculation of fluid saturation in multiphase flow processes.

[0005] In a first aspect, embodiments of this application provide a method for real-time calculation of multiphase flow saturation based on microfluidics technology, comprising: S1 establishing a multiphase flow image dataset; conducting microfluidics experiments on multiphase flow in porous or fractured media according to actual needs, and acquiring images of the multiphase flow process at a preset resolution in real time using an image acquisition device to establish the multiphase flow image dataset; S2 cropping the original images at different times in the multiphase flow image dataset to a target size and rotating them to a target position, identifying the target fluid in the cropped and rotated original images according to a preset RGB range, and adjusting the preset RGB range until the identification result is accurate, wherein the identification result is the target fluid region; S3 generating target fluid saturation data in real-time based on the target fluid region in S2; and S4 plotting the saturation evolution curve of the target fluid in the multiphase flow process based on the target fluid saturation data obtained in S3.

[0006] In one possible implementation of the first aspect, step S1 specifically includes the following steps:

[0007] S101 conducts microfluidic visualization experiments on multiphase flow in porous or fractured media: According to the research objectives, porous or fractured microfluidic transparent media are prepared, and different fluids are dyed and then injected into the microfluidic transparent media in sequence;

[0008] S102 Acquiring a multiphase flow image dataset: Using an image acquisition device, images at a preset resolution are acquired in real time during the multiphase flow microfluidic visualization experiment at a preset acquisition frame rate to establish a multiphase flow image dataset.

[0009] Optionally, in another possible implementation of the first aspect, step S2 specifically includes the following steps:

[0010] In MATLAB, S201 uses the `imrotate` function to rotate the original images at different times in a multiphase flow image dataset to a normalized position, and uses the `imcrop` function to crop the rotated images to a normalized size.

[0011] S202 identifies the target fluid in the cropped and rotated original image according to the preset RGB range;

[0012] S203 determines whether the preset RGB range is accurate based on the recognition result. If it is not accurate, the preset RGB range is adjusted until the recognition result is correct.

[0013] Optionally, in another possible implementation of the first aspect, step S3 specifically includes the following steps:

[0014] S301 marks the pixels occupied by the target fluid in the target fluid region as white;

[0015] S302 counts the number of pixels N occupied by the target fluid;

[0016] S303 calculates the target fluid saturation S in the normalized image under instantaneous conditions; for porous media, the formula for calculating the target fluid saturation S is:

[0017]

[0018] In the formula, N is the number of pixels occupied by the target fluid; δ is the image resolution; h is the channel depth of the microfluidic chip; and s is the channel area of ​​the microfluidic chip. Porosity of the medium;

[0019] For fractured media, the formula for calculating the target fluid saturation S is:

[0020] S=Nδa / L f W f a=Nδ / L f W f (2)

[0021] In the formula, a is the average aperture of the crack; L f W is the crack length; f The width of the crack;

[0022] Image resolution δ represents the area occupied by each pixel in the normalized image, and its calculation formula is:

[0023] δ=LW / mn (3)

[0024] In the formula, L is the actual length of the multiphase flow experimental image; W is the actual width of the multiphase flow experimental image; m is the horizontal resolution of the camera in the multiphase flow experiment, i.e., the number of pixels in the horizontal direction of the screen; n is the vertical resolution of the camera in the multiphase flow experiment, i.e., the number of pixels in the vertical direction of the screen.

[0025] S304 generates target fluid saturation data in real time based on the target fluid saturation S in the normalized image under instantaneous conditions.

[0026] Optionally, in another possible implementation of the first aspect, step S4 specifically includes the following steps:

[0027] S401 Statistical analysis of the capture time t and target fluid saturation S for each image in the multiphase flow image dataset;

[0028] S402 plots the saturation evolution curve St of multiphase flow experiment with time t as the abscissa and the target fluid saturation S as the ordinate.

[0029] Optionally, in another possible implementation of the first aspect, after step S4 above, the following is also included:

[0030] Based on the saturation evolution curve (St diagram), the saturation change rate is calculated to quantify the multiphase flow process. The saturation change rate includes the instantaneous change rate of the target fluid saturation and the overall change rate of the target fluid saturation.

[0031] The instantaneous rate of change k of the target fluid saturation is used to quantify the instantaneous displacement efficiency of two-phase or multiphase flow, and its calculation formula is as follows:

[0032]

[0033] In the formula, S1 is the saturation of the target fluid at time t1; S2 is the saturation of the target fluid at time t2;

[0034] The overall rate of change of the target fluid saturation, K, is used to quantify the overall displacement efficiency of two-phase or multiphase flow, and its calculation formula is as follows:

[0035]

[0036] In the formula, S end S represents the saturation level of the target fluid at the end of the multiphase flow experiment. init is the saturation level of the target fluid at the start of the multiphase flow experiment; T is the duration of the multiphase flow experiment.

[0037] Optionally, in another possible implementation of the first aspect, after calculating the saturation change rate based on the saturation evolution curve St diagram to quantify the multiphase flow process, it further includes:

[0038] When the target fluid is in a residual state and no longer displaced by the intruding phase fluid in a two-phase flow process, the saturation change is triggered by mass transfer. The two-phase mass transfer rate coefficient K is calculated based on the saturation change. mf The calculation formula is:

[0039]

[0040] In the formula, S l ρ is the saturation of the residual fluid in the experiment; t is time (T); ρ is the density of the residual fluid. It refers to the porosity of the medium; c e c is the equilibrium solubility of the residual fluid in the intruding phase fluid; c is the concentration of the residual fluid in the intruding phase fluid, where c is expressed as:

[0041]

[0042] In the formula, s is the flow channel area of ​​the microfluidic chip; h is the flow channel depth of the microfluidic chip; and v is the injection velocity of the intrusive phase fluid.

[0043] In this technical solution, a multiphase flow image dataset is first established. Then, the original images at different times in the multiphase flow image dataset are cropped to the target size and rotated to the target position. The target fluid in the cropped and rotated original images is identified according to a preset RGB range, and the preset RGB range is adjusted until the identification result is accurate, identifying the target fluid region. Next, target fluid saturation data under real-time conditions is generated based on the target fluid region. Finally, based on the real-time target fluid saturation data, the saturation evolution curve of the target fluid in the multiphase flow process is plotted. This improves the accuracy of real-time fluid saturation calculation in multiphase flow displacement and mass transfer processes. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a flowchart illustrating a method for real-time calculation of multiphase flow saturation based on microfluidic technology, provided in an embodiment of this application.

[0046] Figure 2 This is a schematic diagram of the microfluidic chip with a porous structure provided in one embodiment of this application;

[0047] Figure 3 This is a schematic diagram of the target fluid identification result in an instantaneous state provided by an embodiment of this application;

[0048] Figure 4 This is a saturation evolution curve of the target fluid provided in an embodiment of this application. Detailed Implementation

[0049] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0050] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0051] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0052] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0053] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0054] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0055] The following is a detailed description of a real-time calculation method for multiphase flow saturation based on microfluidics technology provided in this application, with reference to the accompanying drawings.

[0056] Figure 1 The illustration shows a flowchart of a method for real-time calculation of multiphase flow saturation based on microfluidics technology, provided in an embodiment of this application.

[0057] like Figure 1 As shown, the real-time calculation method for multiphase flow saturation based on microfluidics technology includes the following steps:

[0058] S1. Establish a multiphase flow image dataset; Conduct microfluidic experiments on multiphase flow in porous or fractured media according to actual needs, and acquire images of the multiphase flow process at a preset resolution in real time through image acquisition equipment to establish a multiphase flow image dataset;

[0059] S2 crops the original images at different times in the multiphase flow image dataset to the target size and rotates them to the target position. Based on the preset RGB range, it identifies the target fluid in the cropped and rotated original images and adjusts the preset RGB range until the identification result is accurate. The identification result is the target fluid region.

[0060] S3 generates real-time target fluid saturation data based on the target fluid region of S2;

[0061] Based on the real-time target fluid saturation data obtained in S3, S4 plots the saturation evolution curve of the target fluid in the multiphase flow process.

[0062] Furthermore, in one embodiment of this application, step S1 specifically includes the following steps:

[0063] S101 conducts microfluidic visualization experiments on multiphase flow in porous or fractured media: According to the research objectives, porous or fractured microfluidic transparent media are prepared, and different fluids are dyed and then injected into the microfluidic transparent media in sequence;

[0064] S102 Acquiring a multiphase flow image dataset: Using an image acquisition device, images at a preset resolution are acquired in real time during the multiphase flow microfluidic visualization experiment at a preset acquisition frame rate to establish a multiphase flow image dataset.

[0065] The specific process of steps S101-S102 described above can be illustrated by the following examples.

[0066] A microfluidic visualization experimental platform was built, which includes a light source, a high-precision camera, a computer, a syringe pump, a microfluidic chip, and an optical experimental rack.

[0067] Determine the microfluidic chip structure: determine the channel area s, channel depth h, and porosity of the pore structure. Heterogeneity and wettability; determining the fracture length L of the fracture structure. f Crack width W f , average crack aperture (a), roughness, wettability;

[0068] As one possible implementation, such as Figure 2 As shown, the elliptical channel of the porous microfluidic chip has a major axis of 19.95 mm, a minor axis of 6.34 mm, and a channel area of ​​99.34 mm². 2 The channel depth is 0.05 mm, the porosity is 0.58, and the cylinders within the elliptical domain represent solid-phase skeleton particles in the porous medium. The cylinder diameter R follows a uniform distribution. in It is the average diameter λ determines the heterogeneity of the porous medium (λ=0.25), and the chip material is glass, which has a relatively hydrophilic wettability.

[0069] Conduct multiphase flow experiments: For oil-gas two-phase flow, oil-water two-phase flow, and oil-water-gas multiphase flow, determine the order of fluid injection, dye type, preset RGB range of fluid, and injection velocity v;

[0070] As one possible approach, a two-phase flow experiment can be conducted on sodium dodecyl sulfate solution (SDS, surfactant) and trichloroethylene (non-aqueous liquid). After obtaining the residual state of trichloroethylene, SDS solution is injected at a flow rate of 10 μL / min. The dye used for trichloroethylene is Oil Red-O. The initial RGB range of the fluid is [225, 170, 165] to [235, 180, 185]. The SDS solution is not dyed.

[0071] Acquire multiphase flow image dataset: Use a high-precision camera to acquire images of the multiphase flow process at a preset resolution in real time, and record the image resolution δ and the acquisition frame rate fps.

[0072] As one possible approach, a high-precision camera is used to acquire images of the multiphase flow process at a preset resolution in real time, with an image resolution of 11.3μm×1.3μm and a frame rate of 0.06Hz.

[0073] Furthermore, in one embodiment of this application, step S2 specifically includes the following steps:

[0074] In MATLAB, S201 uses the `imrotate` function to rotate the original images at different times in a multiphase flow image dataset to a normalized position, and uses the `imcrop` function to crop the rotated images to a normalized size.

[0075] S202 identifies the target fluid in the cropped and rotated original image according to the preset RGB range;

[0076] S203 determines whether the preset RGB range is accurate based on the recognition result. If it is not accurate, the preset RGB range is adjusted until the recognition result is correct.

[0077] Furthermore, in one embodiment of this application, step S3 specifically includes the following steps:

[0078] S301 marks the pixels occupied by the target fluid in the target fluid region as white;

[0079] S302 counts the number of pixels N occupied by the target fluid;

[0080] S303 calculates the target fluid saturation S in the normalized image under instantaneous conditions; for porous media, the formula for calculating the target fluid saturation S is:

[0081]

[0082] In the formula, N is the number of pixels occupied by the target fluid; δ is the image resolution; h is the channel depth of the microfluidic chip; and s is the channel area of ​​the microfluidic chip. Porosity of the medium;

[0083] For fractured media, the formula for calculating the target fluid saturation S is:

[0084] S=Nδa / L f W f a=Nδ / L f W f (2)

[0085] In the formula, a is the average aperture of the crack; L f W is the crack length; f The width of the crack;

[0086] Image resolution δ represents the area occupied by each pixel in the normalized image, and its calculation formula is:

[0087] δ=LW / mn (3)

[0088] In the formula, L is the actual length of the multiphase flow experimental image; W is the actual width of the multiphase flow experimental image; m is the horizontal resolution of the camera in the multiphase flow experiment, i.e., the number of pixels in the horizontal direction of the screen; n is the vertical resolution of the camera in the multiphase flow experiment, i.e., the number of pixels in the vertical direction of the screen.

[0089] S304 generates target fluid saturation data in real time based on the target fluid saturation S in the normalized image under instantaneous conditions.

[0090] In one embodiment of this application, as Figure 3 As shown, the target fluid is identified according to the preset RGB range, and the pixels occupied by the target fluid are marked as white; under this instantaneous condition, the saturation of trichloroethylene is 10.5%.

[0091] Furthermore, in one embodiment of this application, step S4 specifically includes the following steps:

[0092] S401 Statistical analysis of the capture time t and target fluid saturation S for each image in the multiphase flow image dataset;

[0093] S402 plots the saturation evolution curve St of multiphase flow experiment with time t as the abscissa and the target fluid saturation S as the ordinate.

[0094] In the embodiments of this application, such as Figure 4 As shown, the evolution curve St of the saturation of the multiphase flow experiment is plotted with the image acquisition time t of the multiphase flow as the horizontal axis and the target fluid saturation S as the vertical axis.

[0095] Furthermore, in one embodiment of this application, after step S4 described above, the following step is also included:

[0096] Based on the saturation evolution curve (St diagram), the saturation change rate is calculated to quantify the multiphase flow process. The saturation change rate includes the instantaneous change rate of the target fluid saturation and the overall change rate of the target fluid saturation.

[0097] The instantaneous rate of change k of the target fluid saturation is used to quantify the instantaneous displacement efficiency of two-phase or multiphase flow, and its calculation formula is as follows:

[0098]

[0099] In the formula, S1 is the saturation of the target fluid at time t1; S2 is the saturation of the target fluid at time t2;

[0100] Optionally, in one embodiment of this application, specifically in this example, under the instantaneous condition of t = 50 s, the instantaneous rate of change of trichloroethylene saturation is calculated to be -2.29 × 10⁻⁶. -4 s -1 .

[0101] The overall rate of change of the target fluid saturation, K, is used to quantify the overall displacement efficiency of two-phase or multiphase flow, and its calculation formula is as follows:

[0102]

[0103] In the formula, S end S represents the saturation level of the target fluid at the end of the multiphase flow experiment. init is the saturation level of the target fluid at the start of the multiphase flow experiment; T is the duration of the multiphase flow experiment.

[0104] Optionally, in one embodiment of this application, the overall rate of change of trichloroethylene saturation is calculated to be -1.37 × 10⁻⁶. -5 s -1 .

[0105] Furthermore, in one embodiment of this application, after calculating the saturation change rate based on the saturation evolution curve St diagram to quantify the multiphase flow process, the method further includes:

[0106] When the target fluid is in a residual state and no longer displaced by the intruding phase fluid in a two-phase flow process, the saturation change is triggered by mass transfer. The two-phase mass transfer rate coefficient K is calculated based on the saturation change.mf The calculation formula is:

[0107]

[0108] In the formula, S l ρ is the saturation of the residual fluid in the experiment; t is time (T); ρ is the density of the residual fluid. It refers to the porosity of the medium; c e c is the equilibrium solubility of the residual fluid in the intruding phase fluid; c is the concentration of the residual fluid in the intruding phase fluid, where c is expressed as:

[0109]

[0110] In the formula, s is the flow channel area of ​​the microfluidic chip; h is the flow channel depth of the microfluidic chip; and v is the injection velocity of the intrusive phase fluid.

[0111] Optionally, in one embodiment of this application, the density of trichloroethylene is 1.46 g / mL, the porosity of the medium is 0.58, and the equilibrium solubility of trichloroethylene in SDS solution is 2.03 g / L; under the instantaneous condition of t = 50 s, the two-phase mass transfer rate coefficient between trichloroethylene and SDS solution is calculated to be 1.49 min. -1 .

[0112] This application provides a method for real-time calculation of multiphase flow fluid saturation based on microfluidics technology. First, a multiphase flow image dataset is established. Then, original images from different times within the dataset are cropped to the target size and rotated to the target position. The target fluid in the cropped and rotated original images is identified according to a preset RGB range, and the preset RGB range is adjusted until the identification result is accurate, identifying the target fluid region. Next, real-time target fluid saturation data is generated based on the target fluid region. Finally, based on the real-time target fluid saturation data, the saturation evolution curve of the target fluid in the multiphase flow process is plotted. This improves the accuracy of real-time fluid saturation calculation in multiphase flow displacement and mass transfer processes.

[0113] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0114] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0115] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for real-time calculation of saturation of multiphase flow fluid based on microfluidic technology, characterized in that, Includes the following steps: S1 establishes a multiphase flow image dataset; Microfluidic experiments on multiphase flow in porous or fractured media are carried out according to actual needs. The multiphase flow process is acquired in real time using image acquisition equipment at a preset resolution to establish the multiphase flow image dataset. S2 cropped the original images at different times in the multiphase flow image dataset to the target size and rotated them to the target position. The target fluid in the cropped and rotated original images was identified according to a preset RGB range, and the preset RGB range was adjusted until the identification result was accurate. The identification result was the target fluid region. S3 generates real-time target fluid saturation data based on the target fluid region of S2; Based on the real-time target fluid saturation data obtained in S3, S4 plots the saturation evolution curve of the target fluid in the multiphase flow process.

2. The method for real-time calculation of multiphase flow saturation based on microfluidic technology according to claim 1, characterized in that, Step S1 specifically includes the following steps: S101 conducts microfluidic visualization experiments on multiphase flow in porous or fractured media: According to the research objectives, porous or fractured microfluidic transparent media are prepared, and different fluids are dyed and then injected into the microfluidic transparent media in sequence; S102 Acquiring a multiphase flow image dataset: Using an image acquisition device, images at a preset resolution are acquired in real time during the multiphase flow microfluidic visualization experiment at a preset acquisition frame rate to establish a multiphase flow image dataset.

3. The method for real-time calculation of multiphase flow saturation based on microfluidic technology according to claim 2, characterized in that, Step S2 specifically includes the following steps: In MATLAB, S201 uses the `imrotate` function to rotate the original images at different times in the multiphase flow image dataset to a normalized position, and uses the `imcrop` function to crop the rotated images to a normalized size. S202 identifies the target fluid in the cropped and rotated original image according to a preset RGB range; S203 determines whether the preset RGB range is accurate based on the recognition result. If it is not accurate, the preset RGB range is adjusted until the recognition result is correct.

4. The method for real-time calculation of multiphase flow saturation based on microfluidic technology according to claim 3, characterized in that, Step S3 specifically includes the following steps: S301 marks the pixels occupied by the target fluid in the target fluid region as white; S302 Counts the number N pixels occupied by the target fluid; S303 calculates the target fluid saturation S in the normalized image under instantaneous conditions; for porous media, the formula for calculating the target fluid saturation S is: In the formula, N is the number of pixels occupied by the target fluid; δ is the image resolution; h is the channel depth of the microfluidic chip; and s is the channel area of ​​the microfluidic chip. Porosity of the medium; For fractured media, the formula for calculating the target fluid saturation S is: S=Nδa / L f W f a=Nδ / L f W f (2) In the formula, a is the average aperture of the crack; L f W is the crack length; f The width of the crack; Image resolution δ represents the area occupied by each pixel in the normalized image, and is calculated using the following formula: δ=LW / mn (3) In the formula, L is the actual length of the multiphase flow experimental image; W is the actual width of the multiphase flow experimental image; m is the horizontal resolution of the camera in the multiphase flow experiment, i.e., the number of pixels in the horizontal direction of the screen; n is the vertical resolution of the camera in the multiphase flow experiment, i.e., the number of pixels in the vertical direction of the screen. S304 generates target fluid saturation data in real time based on the target fluid saturation S in the normalized image under the instantaneous state.

5. The method for real-time calculation of multiphase flow saturation based on microfluidic technology according to claim 4, characterized in that, Step S4 specifically includes the following steps: S401 Calculate the capture time t and target fluid saturation S for each image in the multiphase flow image dataset; S402 plots the saturation evolution curve St of multiphase flow experiment with time t as the abscissa and the target fluid saturation S as the ordinate.

6. The method for real-time calculation of multiphase flow saturation based on microfluidic technology according to claim 5, characterized in that, Following step S4, the method further includes: Based on the saturation evolution curve (St diagram), the saturation change rate is calculated to quantify the multiphase flow process. The saturation change rate includes the instantaneous change rate of the target fluid saturation and the overall change rate of the target fluid saturation. The instantaneous rate of change of the target fluid saturation, k, is used to quantify the instantaneous displacement efficiency of two-phase or multiphase flow. Its calculation formula is as follows: In the formula, S1 is the saturation of the target fluid at time t1; S2 is the saturation of the target fluid at time t2; The overall rate of change of the target fluid saturation, K, is used to quantify the overall displacement efficiency of two-phase or multiphase flow, and its calculation formula is as follows: In the formula, S end S represents the saturation level of the target fluid at the end of the multiphase flow experiment. init is the saturation level of the target fluid at the start of the multiphase flow experiment; T is the duration of the multiphase flow experiment.

7. The method for real-time calculation of multiphase flow saturation based on microfluidic technology according to claim 6, characterized in that, After calculating the saturation change rate to quantify the multiphase flow process based on the saturation evolution curve St diagram, the method further includes: When the target fluid is in a residual state and no longer displaced by the intruding phase fluid in a two-phase flow process, the saturation change is triggered by mass transfer. The two-phase mass transfer rate coefficient K is calculated based on the saturation change. mf The calculation formula is: In the formula, S l ρ represents the saturation of the residual fluid in the experiment; t represents time; and ρ represents the density of the residual fluid. It refers to the porosity of the medium; c e c is the equilibrium solubility of the residual fluid in the intruding phase fluid; c is the concentration of the residual fluid in the intruding phase fluid, where c is expressed as: In the formula, s is the flow channel area of ​​the microfluidic chip; h is the flow channel depth of the microfluidic chip; and v is the injection velocity of the intrusive phase fluid.

Images