Microscopic visualization underground reservoir two-phase flow displacement experiment system and method

Abstract

The invention relates to a microcosmic visualization underground reservoir two-phase flow displacement experiment system and method, and the system comprises a microcosmic seepage chip, and an injection module, a microcosmic holder, a pressure and temperature acquisition control module, a gas metering module and a data and image acquisition module which are connected in sequence; a microscopic seepage chip is clamped in the microscopic clamping device; the injection module comprises an N2 gas cylinder, a hydrogen generator, a piston container, an injection pump and a pressure regulating valve; the pressure and temperature acquisition control module comprises an annular pressure tracking pump, a pressure return unit, a temperature sensor and a heating unit. The pressure return unit comprises a pressure return valve, a pressure return container and a pressure return pump. Compared with the prior art, the seepage condition of the two-phase flow in the model and the residual gas phase distribution condition after the two-phase flow passes through gas drive water, water drive gas, polymer drive and other chemical drive can be visually observed, and the accuracy of experimental data is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of multiphase flow simulation experimental devices for underground reservoirs, and in particular to a microscopic visualization underground reservoir two-phase flow displacement experimental system and method. Background Art

[0003] However, for underground hydrogen storage in porous reservoirs, which has attracted the most attention, its feasibility depends largely on the flow and transport behavior of hydrogen. During the injection and extraction cycle of the reservoir, it is controlled by complex pore-scale processes. According to the observation of researchers, when trying to simulate sandstone reservoirs for hydrogen storage, hydrogen mainly occupies large pores, while small pores, pore throats and corners are occupied by brine because hydrogen has very high water wettability. Pore-level observations have provided strong preliminary signs that saline aquifers in sandstone reservoirs are conducive to hydrogen storage, but what factors will affect it during the two-phase displacement of hydrogen and brine, and what factors will make hydrogen storage more efficient, there is still little research in my country. Therefore, how to design an experimental device that can microscopically visualize the two-phase flow displacement of underground reservoirs and intuitively observe the whole process of seepage of brine and hydrogen two-phase displacement under different conditions is of great significance for studying the quantitative relationship between hydrogen storage and pore network structure characteristic parameters and multiphase flow field parameters, and establishing hydrogen storage efficiency and prediction models under complex reservoir conditions.

[0004] Chinese patent CN112630407 discloses a microscopic visualization simulation experimental device and method for sand production from hydrate reservoir seepage, which can simulate sand production from natural gas hydrate exploitation, and directly observe the entire microscopic migration process of fine particles driven by gas-liquid mixed multiphase fluid, so as to analyze the sand production law and study the sand production mechanism of hydrate reservoir. However, this design cannot observe and quantify the seepage of gas-liquid two-phase flow in the model and the residual gas phase distribution after gas-water drive, water-gas drive, polymer drive and other chemical drive from a more microscopic level. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a microscopic visualization underground reservoir two-phase flow displacement experimental system and method. The device of the present invention can intuitively observe the seepage conditions of the two-phase flow in the model and the distribution of the residual gas phase after gas-driven water, water-driven gas, polymer-driven and other chemical-driven.

[0006] The present invention provides a microscopic visualized underground reservoir two-phase flow displacement experimental system, comprising: a microscopic seepage chip and an injection module, a microscopic clamp, a pressure and temperature acquisition control module, a gas metering module, and a data and image acquisition module connected in sequence;

[0007] The microscopic seepage chip is clamped in the microscopic clamp;

[0008] The injection module includes an N2 gas cylinder, a hydrogen generator, a piston container, an injection pump and a pressure regulating valve. The N2 gas cylinder and the hydrogen generator are both connected to the pressure regulating valve. The piston container can be loaded with two different liquids. The piston container is connected to the injection pump to inject the two different liquids into the microscopic seepage chip respectively. A first gas flow meter and a one-way valve are installed between the pressure regulating valve and the piston container;

[0009] The pressure and temperature acquisition control module includes: an annular pressure tracking pump, a back pressure unit, a temperature sensor and a heating unit. The back pressure unit includes: a back pressure valve, a back pressure container and a back pressure pump. The vacuum pump, the back pressure valve, the back pressure container and the back pressure pump are connected in sequence through pipelines. Pressure sensors and valves are installed between the vacuum pump, the back pressure valve, the back pressure container and the back pressure pump. The heating device includes a semi-open insulation sleeve and an electric heating sleeve. The semi-open insulation sleeve and the electric heating sleeve are built into the microscopic clamp.

[0010] The gas metering module includes a flow meter group consisting of a second gas flow meter, a desiccant and a gas-liquid separator connected in sequence;

[0011] The data and image acquisition module comprises: pressure sensors arranged at multiple points on the pipeline, digital display instruments, data acquisition cards, special oil displacement light sources, stereo microscopes and computers, and the stereo microscope lens is aimed at the pore channel of the microscopic clamp.

[0012] Further, the microscopic gripper comprises:

[0013] A shell body, constituting a lateral outer wall structure;

[0014] The pressure-bearing glass covers the top and bottom of the shell to form the upper and lower outer wall structures, and together with the shell forms a sealed cavity;

[0015] Pressure covers are located above and below the pressure-bearing glass;

[0016] The etching model is arranged in the sealed cavity and has a plurality of regular cylinders engraved thereon to simulate the pore channel structure with different pore throat sizes.

[0017] Furthermore, the housing is provided with:

[0018] Connecting screws, used to fix the gland, pressure-bearing glass and shell;

[0019] An outlet connector connected to the outlet of the piston container or the pressure regulating valve;

[0020] The inlet and outlet sealing rings are installed at the outlet of the lead-out joint.

[0021] Furthermore, a sealing ring is provided between the pressure-bearing glass and the shell;

[0022] The microscopic holder also includes a window sealing unit, a sample pressure pad and a rubber plate;

[0023] The upper and lower window sealing units are respectively arranged on the upper and lower sample pressure pads and the upper and lower parts of the rubber plate.

[0024] Furthermore, the hydrogen generator adopts a high-sensitivity fuzzy system and an automatic tracking system, and is provided with a reflux device to ensure that there is no liquid return phenomenon in the instrument.

[0025] Furthermore, the pressure regulating valve is a high-pressure type pressure regulating valve, the valve module of which is detachable and has a standard exhaust hole.

[0026] Furthermore, the first gas flow meter and the second gas flow meter use pneumatic valves to achieve automatic switching between different ranges through a computer, and a manual valve is installed to achieve manual switching, which can display instantaneous flow and cumulative flow.

[0027] Furthermore, the injection pump is a double-cylinder constant speed and constant pressure pump, which is a horizontal flow pump and adopts a double-plunger reciprocating method for infusion.

[0028] Furthermore, the piston container adopts a ring-type combined sealing structure to eliminate the "pulse" phenomenon when running under low speed and pressure; the ring pressure tracking pump has manual and automatic functions to ensure that the difference between the ring pressure and the internal pressure remains fixed.

[0029] The back pressure valve is a high-precision back pressure valve, adopts a thin-film structure, and is mainly composed of a stainless steel thin film, a valve needle, a valve seat, a valve upper and lower body, and a sealing ring.

[0030] The stereo microscope and the computer together constitute a high-definition image collector, which can combine "microscopic simulation technology" and "image analysis" to be used for dynamic image quantitative analysis of microscopic simulation displacement test.

[0031] The present invention also provides a microscopic visualization underground reservoir two-phase flow displacement experimental method, comprising the following steps:

[0032] S1: Install the microscopic seepage chip on the microscopic holder, and connect the injection module, the pressure and temperature acquisition control module, the gas metering module, and the data and image acquisition module to the microscopic holder;

[0033] S2: Clean the microscopic seepage chip, open the corresponding valve, first turn on the vacuum pump to remove air and other impurities in the entire device, then fill the piston container with deionized water, use the injection pump to inject the deionized water into the microscopic seepage chip, so that the chip is full of deionized water, and finally use the pressure regulating valve to continuously inject N2 into the micromodel to dry the model;

[0034] S3: Conduct contact angle measurements to verify that the micromodel is hydrophilic under the experimental conditions; in this study, the drainage process was performed at a temperature of 25 °C and ambient pressure. The H2 injection rate ranged from 0.005 ml / min to 0.1 ml / min, and the corresponding volumetric velocity was calculated.

[0035] S4: Inject dyed brine into the microscopic permeation chip at a certain injection rate to sweep out N2 and thoroughly saturate the pores; during this process, use a stereo microscope to observe whether saturation is achieved; when there are no bubbles in the entire pore area of ​​the micromodel, saturation is considered to have been achieved; then, set a constant flow rate, use a pressure regulating valve and a first gas flow meter to inject H2 into the brine-saturated micromodel, and once the hydrogen phase reaches the field of view, continuously record the image of the brine phase until no saturation occurs in the entire micromodel. When a quasi-stable condition is reached, take a series of photos by slowly moving the stereo microscope stage to edit the entire network;

[0036] S5: Quantify the residual brine saturation using image processing software, separate the colors, and retain the red channel; obtain the percentage of residual brine by counting the black or white pixels in the binary image; based on the total area and pore area of ​​the micromodel, the saturation of the H2 phase can be determined;

[0037] S6: Repeat the experiment with chips of different porosity and pore size, record the data and make comparisons.

[0038] The high-definition image collector composed of the stereo microscope and the computer is used to observe and record the flow state of single-phase flow and gas-liquid two-phase flow in the pore network at the micrometer scale.

[0039] Compared with the prior art, the present invention has the following advantages:

[0040] (1) The present invention utilizes a microscopic clamp, a microscopic seepage chip, and a data and image acquisition module to solve the problem that traditional underground reservoir two-phase flow displacement experiments can only be conducted through numerical simulation or macroscopic experiments, thereby realizing microscopic visualization of the underground reservoir two-phase flow displacement process, making the experimental process intuitive and visible, and being able to observe the entire seepage process of brine and hydrogen two-phase displacement under different conditions.

[0041] (2) The present invention makes a microscopic seepage chip and uses electron microscope and X-ray micro-computed tomography images to extract the real rock microstructure characteristics, which can accurately characterize the pore space and then extract statistical information. The quantitative relationship between parameters such as porosity, pores, particle size distribution and anisotropy is established, providing a theoretical basis for studying the hydrogen storage capacity and the characteristic parameters of the pore network structure.

[0042] (3) The injection module, pressure and temperature acquisition control module and gas metering module provided by the present invention have high accuracy and stability, and can accurately control and monitor parameters such as pressure, temperature, flow rate, etc. during the experiment to ensure the accuracy of the experimental data.

[0043] (4) The data and image acquisition system used in the present invention can collect data such as pressure and flow rate in real time during the experiment, and analyze and process the experimental images in combination with image processing software to achieve quantitative analysis of the two-phase flow displacement process, providing a theoretical reference for establishing hydrogen storage efficiency and prediction models under complex reservoir conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic diagram of the structure of the experimental system for microscopic visualization of underground reservoir two-phase flow displacement;

[0045] Figure 2 Schematic diagram of the structure of the microscopic holder for the microscopic visualization of the underground reservoir two-phase flow displacement experimental system.

[0046] Figure numerals: 1. N2 gas cylinder; 2. Hydrogen generator; 3. Pressure regulating valve; 4-1. First gas flow meter; 4-2. Second gas flow meter; 5. One-way valve; 6. Double-cylinder constant speed and constant pressure pump; 7. Piston container; 8. Microscopic clamp; 9. Annular pressure tracking pump; 10. Vacuum pump; 11. Back pressure pump; 12. Desiccant; 13. Back pressure valve; 14. Gas-liquid separator; 15. Back pressure container; 16. Stereo microscope; 17. Computer; 18. Lead connector; 19. Semi-open insulation cover; 20. Electric heating cover; 21. Connecting screws; 22. Sealing ring; 23. Pressure cover; 24. Window sealing unit; 25. Pressure glass; 26. Sample pressure pad and rubber plate; 27. Shell; 28. Inlet and outlet sealing rings. DETAILED DESCRIPTION

[0047] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms and other features not clearly described in this technical solution are all considered to be common technical features disclosed in the prior art.

[0048] Example 1

[0049] This embodiment provides a microscopic visualization underground reservoir two-phase flow displacement experimental system, such as Figure 1 , 2 As shown, it includes: a microscopic seepage chip and an injection module, a microscopic clamp 8, a pressure and temperature acquisition control module, a gas metering module, and a data and image acquisition module connected in sequence;

[0050] The microscopic seepage chip is clamped in the microscopic clamp 8;

[0051] The injection module includes an N2 gas cylinder 1, a hydrogen generator 2, a piston container 7, an injection pump and a pressure regulating valve 3. The N2 gas cylinder 1 and the hydrogen generator 2 are both connected to the pressure regulating valve 3. The piston container 7 can be loaded with two different liquids. The piston container 7 is connected to the injection pump to inject the two different liquids into the microscopic seepage chip respectively. A first gas flow meter 4-1 and a one-way valve 5 are installed between the pressure regulating valve 3 and the piston container 7;

[0052] The pressure and temperature acquisition control module includes: an annular pressure tracking pump 9, a back pressure unit, a temperature sensor and a heating unit. The back pressure unit includes: a back pressure valve 13, a back pressure container 15 and a back pressure pump 11. The vacuum pump 10, the back pressure valve 13, the back pressure container 15 and the back pressure pump 11 are connected in sequence through pipelines. Pressure sensors and valves are installed between the vacuum pump 10, the back pressure valve 13, the back pressure container 15 and the back pressure pump 11. The heating device includes a semi-open insulation sleeve 19 and an electric heating sleeve 20. The semi-open insulation sleeve 19 and the electric heating sleeve 20 are built in the microscopic clamp 8;

[0053] The gas metering module includes a flow meter group consisting of a second gas flow meter 4-2, a desiccant 12 and a gas-liquid separator 14 connected in sequence;

[0054] The data and image acquisition module includes: pressure sensors arranged at multiple points on the pipeline, digital display instruments, data acquisition cards, special oil displacement light sources, stereo microscopes 16 and computers 17. The lens of the stereo microscope 16 is aimed at the pore channel of the microscopic clamp 8.

[0055] In a specific embodiment, the microscopic holder 8 comprises:

[0056] The housing 27 constitutes a lateral outer wall structure;

[0057] The pressure-bearing glass 25 covers the top and bottom of the housing 27 to form the upper and lower outer wall structures, and together with the housing 27 forms a sealed cavity;

[0058] The pressure cover 23 is arranged above and below the pressure-bearing glass 25;

[0059] The etching model is arranged in the sealed cavity and has a plurality of regular cylinders engraved thereon to simulate the pore channel structure with different pore throat sizes.

[0060] In a specific embodiment, the housing 27 is provided with:

[0061] Connecting screws 21, used to fix the pressure cover 23, the pressure-bearing glass 25 and the housing 27;

[0062] The outlet connector 18 is connected to the outlet of the piston container 7 or the pressure regulating valve 3;

[0063] The inlet and outlet sealing rings 28 are arranged at the outlet of the lead-out joint 18 .

[0064] In a specific embodiment, a sealing ring 22 is provided between the pressure-bearing glass 25 and the housing 27;

[0065] The microscopic holder 8 also includes a window sealing unit 24 and a sample pressure pad and a rubber plate 26;

[0066] The upper and lower window sealing units 24 are respectively disposed above and below the upper and lower sample pressure pads and the rubber plate 26 .

[0067] In a specific implementation, the hydrogen generator 2 adopts a high-sensitivity fuzzy system and an automatic tracking system, and is provided with a reflux device to ensure that there is no liquid return phenomenon in the instrument.

[0068] In a specific implementation, the pressure regulating valve 3 is a high-pressure type pressure regulating valve, the valve module of which is detachable and has a standard exhaust hole.

[0069] In a specific embodiment, pneumatic valves are used to realize automatic switching between different ranges of the first gas flow meter 4-1 and the second gas flow meter 4-2 through a computer, and manual valves are installed to realize manual switching, which can display instantaneous flow and cumulative flow.

[0070] In a specific implementation, the injection pump is a double-cylinder constant speed and constant pressure pump 6, which is a horizontal flow pump and uses a double-plunger reciprocating method for infusion.

[0071] In a specific embodiment, the piston container 7 adopts a ring-type combined sealing structure to eliminate the "pulse" phenomenon when running under low speed pressure; the ring pressure tracking pump 9 has manual and automatic functions to ensure that the difference between the ring pressure and the internal pressure remains fixed.

[0072] The back pressure valve 13 is a high-precision back pressure valve, which adopts a thin-film structure and is mainly composed of a stainless steel thin film, a valve needle, a valve seat, a valve upper and lower body, and a sealing ring.

[0073] The stereo microscope 16 and the computer 17 together constitute a high-definition image collector, which can combine "microscopic simulation technology" and "image analysis" to be used for dynamic image quantitative analysis of microscopic simulation displacement test.

[0074] This embodiment also provides a microscopic visualization underground reservoir two-phase flow displacement experimental method, comprising the following steps:

[0075] S1: Make a microscopic seepage chip, use electron microscope and X-ray microcomputer tomography images to extract the real rock microstructure characteristics and characterize its pore space, then extract statistical information, count the porosity, pore, particle size distribution and anisotropy, and then use the QSGS algorithm to generate an equivalent geometric shape, analyze the statistical information of the generated porous medium to determine whether it is close enough to the real porous medium. When all its statistical information is close to the real porous medium, output it as a file suitable for the printing system, so as to make a microscopic seepage chip; install the microscopic seepage chip on the microscopic holder 8, and connect the injection module, pressure and temperature acquisition control module, gas metering module, data and image acquisition module and the microscopic holder;

[0076] S2: Clean the microscopic seepage chip, open the corresponding valves, first open the vacuum pump 10 to remove air and other impurities in the entire device, then fill the piston container 7 with deionized water, use the injection pump to inject the deionized water into the microscopic seepage chip, so that the chip is full of deionized water, and finally use the pressure regulating valve 3 to continuously inject N2 into the micromodel to dry the model;

[0077] S3: Conduct contact angle measurements to verify that the micromodel is hydrophilic under the experimental conditions; in this study, the drainage process was performed at a temperature of 25 °C and ambient pressure. The H2 injection rate ranged from 0.005 ml / min to 0.1 ml / min, and the corresponding volumetric velocity was calculated.

[0078] S4: Inject dyed brine into the microscopic seepage chip at a certain injection rate to sweep out N2 and thoroughly saturate the pores; during this process, use a stereo microscope 16 to observe whether saturation is achieved; when there are no bubbles in the entire pore area of ​​the micromodel, saturation is considered to have been achieved; then, set a constant flow rate, use the pressure regulating valve 3 and the first gas flow meter 4-1 to inject H2 into the brine-saturated micromodel, and once the hydrogen phase reaches the field of view, continuously record the image of the brine phase until no saturation occurs in the entire micromodel, and when a quasi-stable condition is reached, take a series of photos by slowly moving the stereo microscope 16 stage to edit the entire network;

[0079] S5: Quantify the residual brine saturation using image processing software, separate the colors, and retain the red channel; obtain the percentage of residual brine by counting the black or white pixels in the binary image; based on the total area and pore area of ​​the micromodel, the saturation of the H2 phase can be determined;

[0080] S6: Repeat the experiment with chips of different porosity and pore size, record the data and make comparisons.

[0081] The high-definition image collector composed of the stereo microscope 16 and the computer 17 is used to observe and record the flow state of single-phase flow and gas-liquid two-phase flow in the pore network at the micrometer scale.

[0082] This embodiment simulates the two-phase flow displacement process of underground reservoirs under different pore structures or environmental conditions, and injects different types of gases into the microscopic seepage chip in sequence, and then injects displacement fluids such as water and chemicals into the chip. Through a high-power microscope and a visual model, the seepage of oil and water in the model and the distribution of residual oil after oil-to-water, water-to-oil, polymer drive and other chemical drives can be intuitively observed; at the same time, the flow conditions of each step of the fluid during the displacement are collected in real time to the computer through software through a microscope with a collection port, and the oil-water saturation distribution and size in the microscopic pore structure displacement process are quantitatively described, which provides a theoretical reference for studying the quantitative relationship between hydrogen storage capacity and pore network structure characteristic parameters and multiphase flow field parameters, and establishing hydrogen storage efficiency and prediction models under complex reservoir conditions.

[0083] Components not described in detail in this embodiment are all existing components that can be purchased through public channels.

[0084] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A microscopic visualization underground reservoir two-phase flow displacement experimental system, characterized in that: include: A microscopic seepage chip and an injection module, a microscopic clamp (8), a pressure and temperature acquisition control module, a gas metering module, and a data and image acquisition module connected in sequence; The microscopic seepage chip is clamped in the microscopic clamp (8); The injection module comprises an N2 gas cylinder (1), a hydrogen generator (2), a piston container (7), an injection pump and a pressure regulating valve (3); the N2 gas cylinder (1) and the hydrogen generator (2) are both connected to the pressure regulating valve (3); the piston container (7) can be loaded with two different liquids; the piston container (7) is connected to the injection pump to respectively inject the two different liquids into the microscopic seepage chip; a first gas flow meter (4-1) and a one-way valve (5) are installed between the pressure regulating valve (3) and the piston container (7); The pressure and temperature acquisition control module comprises: a ring pressure tracking pump (9), a back pressure unit, a temperature sensor and a heating unit; the back pressure unit comprises: a back pressure valve (13), a back pressure container (15) and a back pressure pump (11); the vacuum pump (10), the back pressure valve (13), the back pressure container (15) and the back pressure pump (11) are connected in sequence through pipelines; and pressure sensors and valves are installed between each of the vacuum pump (10), the back pressure valve (13), the back pressure container (15) and the back pressure pump (11); The gas metering module comprises a flow meter group consisting of a second gas flow meter (4-2), a desiccant (12) and a gas-liquid separator (14) connected in sequence; The data and image acquisition module comprises: pressure sensors arranged at multiple points on the pipeline, a digital display instrument, a data acquisition card, a special oil displacement light source, a stereo microscope (16) and a computer (17), wherein the lens of the stereo microscope (16) is aimed at the pore channel of the microscopic clamp (8).

2. A microscopic visualization underground reservoir two-phase flow displacement experimental system according to claim 1, characterized in that: The microscopic holder (8) comprises: A housing (27) constituting a lateral outer wall structure; The pressure-bearing glass (25) covers the top and bottom of the shell (27) to form the upper and lower outer wall structures, and together with the shell (27) forms a sealed cavity; A pressure cover (23) is arranged above and below the pressure-bearing glass (25); The etching model is arranged in the sealed cavity and has a plurality of regular cylinders engraved thereon to simulate the pore channel structure with different pore throat sizes.

3. A microscopic visualization underground reservoir two-phase flow displacement experimental system according to claim 2, characterized in that: The housing (27) is provided with: Connecting screws (21) for fixing the gland (23), the pressure-bearing glass (25) and the housing (27); An outlet connector (18) connected to the outlet of the piston container (7) or the pressure regulating valve (3); The inlet and outlet sealing rings (28) are arranged at the outlet of the lead-out joint (18).

4. A microscopic visualization underground reservoir two-phase flow displacement experimental system according to claim 2, characterized in that: A sealing ring (22) is provided between the pressure-bearing glass (25) and the housing (27); The microscopic holder (8) further comprises a window sealing unit (24) and a sample pressure pad and a rubber plate (26); The upper and lower window sealing units (24) are respectively arranged above and below the upper and lower sample pressure pads and the rubber plate (26).

5. The microscopic visualization underground reservoir two-phase flow displacement experimental system according to claim 1, characterized in that: The hydrogen generator (2) adopts a high-sensitivity fuzzy system and an automatic tracking system, and is provided with a reflux device to ensure that there is no liquid return phenomenon in the instrument.

6. The microscopic visualization underground reservoir two-phase flow displacement experimental system according to claim 1, characterized in that: The pressure regulating valve (3) is a high-pressure type pressure regulating valve, the valve module of which is detachable and has a standard exhaust hole.

7. The microscopic visualization underground reservoir two-phase flow displacement experimental system according to claim 1, characterized in that: The first gas flow meter (4-1) and the second gas flow meter (4-2) use pneumatic valves to achieve automatic switching between different ranges through a computer, and a manual valve is installed to achieve manual switching, and can display instantaneous flow and cumulative flow.

8. The microscopic visualization underground reservoir two-phase flow displacement experimental system according to claim 1, characterized in that: The injection pump is a double-cylinder constant speed and constant pressure pump (6), which belongs to a horizontal flow pump and adopts a double-plunger reciprocating method for infusion.

9. The microscopic visualization underground reservoir two-phase flow displacement experimental system according to claim 1, characterized in that: The piston container (7) adopts a ring-type combined sealing structure to eliminate the "pulse" phenomenon when running at low speed and pressure; the ring pressure tracking pump (9) has manual and automatic functions to ensure that the difference between the ring pressure and the internal pressure remains fixed.

10. A microscopic visualization underground reservoir two-phase flow displacement experimental method, characterized in that: The following steps are involved: S1: Mounting the microscopic seepage chip on a microscopic holder (8), and connecting the injection module, the pressure and temperature acquisition control module, the gas metering module, and the data and image acquisition module to the microscopic holder; S2: Clean the microscopic seepage chip, open the corresponding valve, first open the vacuum pump (10) to remove impurities in the entire device, then fill the piston container (7) with deionized water, use the injection pump to inject the deionized water into the microscopic seepage chip, so that the chip is full of deionized water, and finally use the pressure regulating valve (3) to continuously inject N2 into the micromodel to dry the model; S3: Conduct contact angle measurements to verify whether the micromodel is hydrophilic under experimental conditions; S4: Inject dyed brine into the microscopic permeation chip at a certain injection rate to sweep out N2 and thoroughly saturate the pores; during this process, use a stereo microscope (16) to observe whether saturation is achieved; when there are no bubbles in the entire pore area of ​​the micromodel, saturation is considered to have been achieved; then, set a constant flow rate, use the pressure regulating valve (3) and the first gas flow meter (4-1) to inject H2 into the brine-saturated micromodel, and once the hydrogen phase reaches the field of view, continuously record the image of the brine phase until no saturation occurs in the entire micromodel. When a quasi-stable condition is reached, take a series of photos by slowly moving the stereo microscope (16) stage to edit the entire network; S5: Quantify the residual brine saturation using image processing software, separate the colors, and retain the red channel; obtain the percentage of residual brine by counting the black or white pixels in the binary image; based on the total area and pore area of ​​the micromodel, the saturation of the H2 phase can be determined; S6: Repeat the experiment with chips of different porosity and pore size, record the data and make comparisons.

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