Pore-scale CO2 residual capture device and multi-factor sensitivity analysis method

Abstract

The present invention discloses a CO2 residual capture device at the pore scale, which can carry out CO2 displacement and imbibition tests under room temperature and thermostatic conditions and produce effective CO2 residual capture; the present invention also discloses a multi-factor sensitivity analysis method for CO2 residual capture at the pore scale, which verifies the conclusions of numerical simulation through experimental results, uses the experimental results as a reference, and thus optimizes the simulation setting conditions of the numerical simulation sensitivity analysis, ensures the reliability of the numerical simulation conclusions, and then carries out multi-factor sensitivity analysis based on numerical simulation, which is difficult to carry out or costly under some experimental conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of CO2 geological storage, and in particular to a device for capturing CO2 residues at a pore scale, and also to a multi-factor sensitivity analysis method for capturing CO2 residues at a pore scale. Background Art

[0002] Residual CO2 capture is a key mechanism in CO2 geological storage. It can significantly increase the CO2 storage capacity of deep saline aquifers and form effective capillary closures, improving the safety and stability of CO2 geological storage. With the development of high-precision imaging technology, current research is enabling the investigation of flow physics at the pore scale and on rapid timescales during displacement and imbibition. Cutting-edge research leverages the real-time visualization advantages of microfluidics experiments and the high-precision imaging capabilities of CT scanning experiments to investigate, at the pore scale, the evolution of fluid interfaces, local dynamic filling, and two-phase fluid distribution under the influence of multiple factors during displacement and imbibition. Pore-scale numerical simulations, with their advantages such as ease of parametric analysis and the ability to obtain spatial distributions of velocity and pressure fields in the seepage domain, have become a key tool for studying reservoir microscopic seepage mechanisms, following laboratory physical experiments. Consequently, this method is widely used to investigate detailed flow behavior during spontaneous imbibition under the influence of multiple factors. However, certain key influencing factors cannot be investigated under experimental conditions, are expensive, and numerical simulations cannot accurately control the model's boundary conditions and environmental settings. Therefore, providing an analytical method that combines experiments and numerical simulations can effectively reduce the cost of CO2-brine displacement and imbibition experiments at the pore scale and improve the reliability of the conclusions of two-phase flow displacement and imbibition numerical simulations at the pore scale. Summary of the Invention

[0003] In response to the difficulty in analyzing various influencing factors in the experiments of existing technologies and the need to improve the reliability of numerical simulations, the present invention proposes a CO2 residual capture device at the pore scale and a multi-factor sensitivity analysis method for CO2 residual capture at the pore scale, thereby facilitating the research on CO2 residual capture at the pore scale.

[0004] In order to achieve the above-mentioned purpose, the present invention adopts the following technical measures:

[0005] A pore-scale CO2 residual capture device includes a pump, the piston of the pump is connected to the piston of the syringe; the water outlet of the syringe barrel is connected to a first pressure sensor through a hose, the first pressure sensor is connected to a first inlet and outlet on a chip through a hose and a hose connector in turn, the first inlet and outlet are connected to a second inlet and outlet on the chip through a pore network etched in the chip, the second inlet and outlet of the chip are connected to a second pressure sensor through a hose connector and a hose in turn, and the second pressure sensor is connected to a displaced fluid in a beaker through a hose; an imbibition pressure difference adjustment device is provided below the beaker; a high-speed camera is provided above the chip, and the high-speed camera is fixed in position by a camera clamp; the first pressure sensor, the second pressure sensor and the high-speed camera all transmit data to a computer through data cables.

[0006] As mentioned above, the chip is made of a transparent material and is fixed on a hollow fixture. The light emitted by the fill light passes through the hollow area of ​​the fixture from the bottom of the fixture and irradiates the chip.

[0007] The multi-factor sensitivity analysis method for residual CO2 capture at the pore scale, using the above-mentioned residual CO2 capture device at the pore scale, includes the following steps:

[0008] S1. Build a pore-scale CO2 residual capture device, draw the displaced fluid into the syringe, and drive the syringe to inject the displaced fluid into the chip at a set fluid injection rate until the chip is saturated.

[0009] The high-speed camera captures the two-phase distribution map in the chip after saturation;

[0010] S2. Replace a syringe filled with dry CO2 and conduct a displacement test:

[0011] The pump injects CO2 into the chip through the syringe at the set displacement injection rate;

[0012] At the same time, the first pressure sensor detects the pressure change of the first inlet and outlet during the displacement test phase, the second pressure sensor detects the pressure change of the second inlet and outlet during the displacement test phase, and the high-speed camera collects the two-phase distribution diagram of the chip during the displacement test phase;

[0013] The computer draws a pressure change curve during the displacement test phase in real time based on the pressure change data detected by the first pressure sensor; draws a curve of the relationship between the initial CO2 saturation and time during the displacement test based on the two-phase distribution diagram during the displacement test phase; and measures and statistically calculates the contact angle between the CO2 in the chip, the displaced fluid, and the solid wall based on the two-phase distribution diagram during the displacement test phase;

[0014] S3. When the initial CO2 saturation reaches the preset CO2 initial saturation threshold, stop injecting CO2 and conduct the imbibition test:

[0015] The pore-scale CO2 residual capture device is kept stationary; the displaced fluid inside the beaker absorbs the CO2 in the chip under the capillary pressure of the hose and produces CO2 residual;

[0016] At the same time, the first pressure sensor detects the pressure change of the first inlet and outlet during the imbibition test phase, and the second pressure sensor detects the pressure change of the second inlet and outlet during the imbibition test phase; the high-speed camera collects the two-phase distribution diagram of the chip during the imbibition test phase;

[0017] The computer draws a pressure change curve during the imbibition test in real time based on the pressure change data detected by the second pressure sensor; and draws a curve of the relationship between the CO2 residual saturation and time during the imbibition test based on the two-phase distribution diagram during the imbibition test;

[0018] S4, processing the two-phase distribution map in the chip after saturation in step S1 to obtain a pore network reference image, wherein the lines of the pore network in the pore network reference image are clear and consistent with the actual pore network;

[0019] S5. Using the pore network in the experimental reference image, numerical simulation is performed to reproduce the displacement test and imbibition test under the same experimental conditions as in the displacement test and imbibition test. By adjusting the simulation setting conditions, the pressure change curve and two-phase distribution diagram of the numerical simulation displacement stage are respectively consistent with the pressure change curve and two-phase distribution diagram in S2. Figure 1 The pressure change curve and two-phase distribution diagram of the numerical simulation in the imbibition stage are consistent with the pressure change curve and two-phase distribution diagram in S3. Figure 1 To;

[0020] S6. Use the final simulation setting conditions of S5 as the simulation setting conditions for the numerical simulation sensitivity analysis;

[0021] Then, the sensitivity analysis of numerical simulation under the same experimental conditions was carried out by changing one of the factors to be analyzed one by one while keeping the other factors unchanged.

[0022] As mentioned above, the displaced fluid is a mixture of brine and pure water with different components.

[0023] As mentioned above, the factors to be analyzed in S6 include:

[0024] Fluid properties of the displaced fluid, displacement injection rate, wettability of the porous medium, initial pressure inside the chip, static pressure at the first and second inlets during the imbibition phase;

[0025] Among them, fluid properties include viscosity and density, and the wettability of porous media is characterized by contact angle.

[0026] As mentioned above, the simulation setting conditions in S6 include simulation algorithm, initial step size, solver type and wall slip, and wall slip is divided into no-slip and slip.

[0027] As mentioned above, the simulation algorithms in S6 include the phase field method, the level set method, the moving mesh method and the fluid volume method.

[0028] As described above, S1 further includes the following steps:

[0029] During the process of injecting the displaced fluid into the chip, observe and check the tightness of the device. If there is no overflow of the displaced fluid at the hose connection, and the readings of the first pressure sensor and the second pressure sensor are stable and have no obvious fluctuations after being saturated with brine, the device is well-tightened. If the device is poorly-tightened, adjust or rebuild the device before injecting the displaced fluid into the chip.

[0030] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0031] First, the pore-scale CO2 residual capture device proposed in this invention can continuously conduct CO2-brine displacement and brine imbibition experiments at room temperature and constant pressure within the same closed system, enabling effective research on pore-scale CO2 residual capture. The pore-scale CO2 residual capture device has a simple structure and is easy to use. It can conduct CO2 residual capture experiments and analyze its residual characteristics under room temperature and constant pressure conditions.

[0032] In addition, the present invention also proposes a multi-factor sensitivity analysis method for CO2 residual capture at the pore scale. Combining experiments with numerical simulation methods, it can perform sensitivity analysis on various influencing factors of two-phase flow problems at the pore scale; thereby solving the difficulties of being unable to study certain key influencing factors under experimental conditions or the high experimental costs, and improving the reliability of the conclusions of the numerical simulation method. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings described herein are used to provide further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0034] Figure 1 Schematic diagram of the structure of the CO2 residual capture device at the pore scale of the present invention;

[0035] Figure 2 Schematic diagram of the multi-factor sensitivity analysis method for CO2 residual capture at the pore scale of the present invention;

[0036] Figure 3The two-phase distribution diagrams of CO2 breakthrough in the CO2-displacing brine stage in the experiment and numerical simulation, where (a) is the two-phase distribution diagram of CO2 breakthrough in the CO2-displacing brine stage in the experiment, and (b) is the two-phase distribution diagram of CO2 breakthrough in the CO2-displacing brine stage in the numerical simulation;

[0037] Figure 4 The residual CO2 distribution diagrams in the experiment and numerical simulation, where (a) is the residual CO2 distribution diagram in the experiment, and (b) is the residual CO2 distribution diagram in the numerical simulation;

[0038] Figure 5 Figure 3. The relationship curves between initial CO2 saturation and contact angle under different contact angles in the numerical simulation of contact angle sensitivity analysis, as well as the change curves of CO2 residual saturation at different contact angles. (a) is the relationship curve between initial CO2 saturation and contact angle under different contact angles with different injection times in the numerical simulation, and (b) is the change curve of CO2 residual saturation at different contact angles in the hydrophilic medium. The CO2 residual saturation is characterized by the CO2 residual volume fraction.

[0039] Among them, 1-pump, 2-syringe, 3-fill light, 4-fixer, 5-chip, 6-beaker, 7-high-speed camera, 8-camera fixture, 9-first pressure sensor, 10-second pressure sensor, 11-osmotic pressure difference adjustment device. Specific implementation methods

[0040] The invention will be described in further detail below with reference to the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0041] It should be understood that terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or other elements or combinations thereof.

[0042] Example 1:

[0043] Pore-scale CO2 residual capture devices, such as Figure 1 As shown, the device comprises a loading unit, a displacement unit, and a data recording unit, and is used to conduct CO2-brine displacement experiments at room temperature and pressure, and to generate residual CO2 capture through imbibition. The loading unit includes a pump 1 and a syringe 2; the displacement unit includes a chip 5, a fill light 3, a holder 4, a beaker 6, and an imbibition pressure differential adjustment device 11; and the data recording unit includes a first pressure sensor 9, a second pressure sensor 10, and a high-speed camera 7. This device has the advantage of enabling continuous two-phase flow displacement and imbibition experiments within the same closed system.

[0044] The piston of the pump 1 is connected to the piston of the syringe 2, thereby driving the barrel of the syringe 2 to discharge CO2 or the displaced fluid; the water outlet of the barrel of the syringe 2 is connected to the first pressure sensor 9 through a hose, and the first pressure sensor 9 is connected to the first inlet and outlet on the chip 5 in turn through a hose and a hose connector, and the first inlet and outlet are connected to the second inlet and outlet on the chip 5 through the pore network etched in the chip 5, and the second inlet and outlet of the chip 5 are connected to the second pressure sensor 10 through a hose connector and a hose in turn, and the second pressure sensor 10 is connected to the displaced fluid in the beaker 6 through a hose; an imbibition pressure difference regulating device 11 is provided below the beaker 6, and the imbibition pressure difference regulating device 11 is used to adjust the placement height of the beaker 6, thereby adjusting the imbibition pressure difference; in this embodiment, the diameter of the hose is 1 mm; a high-speed camera 7 is provided above the chip 5, and the high-speed camera 7 is fixed in position by a camera clamp 8, and the first pressure sensor 9, the second pressure sensor 10 and the high-speed camera 7 all transmit data to the computer through a data line.

[0045] The loading unit includes a pump 1 and a syringe 2. The syringe 2 is fixed to the pump 1. The pump 1 drives the syringe 2 to inject CO2 or the displaced fluid into the chip 5 at a set injection speed to achieve the displacement purpose.

[0046] The displacement unit includes a chip 5, a fill light 3, a fixture 4, a beaker 6 and an imbibition pressure difference adjusting device 11. The depth of the pores in the pore network of the chip 5, the size of the pore throat, etc. can be etched according to the test requirements. The chip 5 is fixed on the hollow fixture 4, and the fixture 4 is used to fix and adjust the horizontal position of the chip 5. The chip 5 is made of transparent material, and a suitable light source is provided by the fill light 3 under the fixture 4. The light emitted by the fill light 3 passes through the hollow area of ​​the fixture 4 from the bottom of the fixture 4 to illuminate the chip 5; the imbibition pressure difference adjusting device 11 can change the invasion pressure (i.e., the imbibition pressure difference) of the displaced fluid in the imbibition stage by adjusting the vertical height of the beaker 6, thereby controlling the imbibition rate.

[0047] The data recording unit includes a first pressure sensor 9, a second pressure sensor 10, and a high-speed camera 7, all of which transmit data to a computer via a data cable. When assembling the test equipment, the fixture 4 is fine-tuned to ensure that the center of the chip 5 and the center of the imaging plane of the high-speed camera 7 are coaxial. The focal length of the high-speed camera 7 is also adjusted to ensure a clear and complete image, thereby clearly capturing the fluid displacement process within the chip 5.

[0048] In this embodiment, the chip 5 is made of glass. The pore network in the chip 5 is etched based on the configuration of the pore network extracted from the real rock sample. The pore network in the chip 5 is connected to the outside of the chip 5 only through the first entrance and the second entrance. The etching depth of the pore network in the chip 5 can be selected to be 7μm to 20μm. In this embodiment, the etching depth is 20μm. The shooting speed of the high-speed camera 7 can be set as needed, that is, to meet the requirements of recording the CO2 breakthrough and imbibition process in detail. In the key stages of the experiment, such as the CO2 breakthrough stage and the imbibition reflux stage, the high-speed camera 7 can be set to collect 10-20 pictures per second; in other time periods when the two-phase distribution changes slowly, the number of pictures collected can be reduced. In this embodiment, the displaced fluid is selected as brine.

[0049] Example 2:

[0050] The multi-factor sensitivity analysis method for CO2 residual capture at the pore scale utilizes the CO2 residual capture device at the pore scale described in Example 1.

[0051] Factors affecting the capture of residual CO2 include: the fluid properties of CO2 and the displaced fluid, the displacement injection rate (the displacement injection rate affects the displacement injection pressure), the wettability of the porous medium (characterized by the contact angle), the initial pressure inside the chip 5, the static pressure of the first inlet and outlet during the imbibition stage, and the static pressure of the second inlet and outlet, wherein the fluid properties include viscosity and density. Except for the fixed fluid properties of CO2, other factors affecting the capture of residual CO2 are taken as factors to be analyzed (i.e., the fluid properties of the displaced fluid, the displacement injection rate, the wettability of the porous medium, the initial pressure inside the chip 5, the static pressure of the first inlet and outlet during the imbibition stage, and the static pressure of the second inlet and outlet). Sensitivity analysis refers to studying the effects of the changed factors on fluid displacement and imbibition by changing one of the factors to be analyzed one by one in the two-phase flow displacement test and the imbibition test, while keeping the other factors in the factors to be analyzed unchanged.

[0052] The method of the present invention specifically comprises the following steps:

[0053] S1. Build the CO2 residual capture device at the pore scale described in Example 1, draw the displaced fluid into the syringe 2, and drive the pump 1 to inject the displaced fluid into the chip 5 at a set fluid injection speed until the chip 5 is in a saturated state; use the high-speed camera 7 to collect the two-phase distribution diagram in the saturated chip 5.

[0054] In this embodiment, 20 ml of saline is drawn into the syringe 2 as the displaced fluid, and the fluid injection speed of the pump 1 is set to 50 μl / min; the displaced fluid (in this embodiment, the displaced fluid is saline) is injected into the chip 5 until the pore network of the chip 5 is saturated with saline; during the process of injecting the displaced fluid into the chip 5, the airtightness of the device is observed and checked. If there is no overflow of the displaced fluid at the hose connection, and the readings of the first pressure sensor 9 and the second pressure sensor 10 are stable and have no obvious fluctuations after being saturated with saline, the device is well-sealed; if the device is poorly sealed, the device is adjusted or rebuilt before injecting the displaced fluid into the chip 5.

[0055] S2. Replace syringe 2 filled with dry CO2 and conduct a displacement test:

[0056] Pump 1 uses syringe 2 to inject CO2 into chip 5 at a set displacement injection speed;

[0057] At the same time, the first pressure sensor 9 detects the pressure change of the first inlet and outlet during the displacement test phase, the second pressure sensor 10 detects the pressure change of the second inlet and outlet during the displacement test phase, and the high-speed camera 7 collects the two-phase distribution diagram of the chip 5 during the displacement test phase;

[0058] The computer draws a pressure change curve in the displacement test phase in real time based on the pressure change data detected by the first pressure sensor 9; draws a curve of the relationship between the initial CO2 saturation and time in the displacement test based on the two-phase distribution diagram of the displacement test phase; and measures and statistics the contact angles between the CO2 in the chip 5, the displaced fluid, and the solid wall based on the two-phase distribution diagram of the displacement test phase.

[0059] In this embodiment, the pump 1 is set at a displacement injection rate of 10 μl / min, so that the syringe 2 injects CO2 into the chip 5; the first pressure sensor 9 records the CO2 entry pressure and breakthrough pressure at the first inlet and outlet; in this embodiment, the obtained contact angle is approximately 30°, and the contact angle is the angle between the tangent of the gas-liquid interface at the intersection of the gas, liquid and solid phases and the solid-liquid boundary line.

[0060] S3. When the initial CO2 saturation reaches the preset CO2 initial saturation threshold, stop injecting CO2 and conduct the imbibition test:

[0061] The CO2 residual capture device at the pore scale is kept stationary; the displaced fluid inside the beaker 6 absorbs and displaces the CO2 in the chip 5 under the capillary pressure of the hose and produces CO2 residual;

[0062] At the same time, the first pressure sensor 9 detects the pressure change of the first inlet and outlet during the imbibition test phase, and the second pressure sensor 10 detects the pressure change of the second inlet and outlet during the imbibition test phase; the high-speed camera 7 collects the two-phase distribution diagram of the chip 5 during the imbibition test phase;

[0063] The computer draws the pressure change curve of the imbibition test stage in real time according to the pressure change data detected by the second pressure sensor 10; and draws the relationship curve between the CO2 residual saturation and time in the imbibition test according to the two-phase distribution diagram of the imbibition test stage.

[0064] After CO2 injection is complete, pump 1 is turned off to ensure the pore-scale CO2 residual capture device remains stationary. Under the capillary pressure of the hose, the brine inside beaker 6 spontaneously permeates into chip 5. Adjusting the height of the permeation pressure differential adjustment device 11 adjusts the permeation pressure differential, thereby controlling the brine permeation rate. The CO2 inside chip 5 is displaced and expelled by the displaced fluid from beaker 6. A snapping event occurs within the pore network of chip 5, fragmenting the continuous CO2 into CO2 clusters to form residual capture.

[0065] S4, processing the two-phase distribution map of the chip 5 after saturation in step S1 to obtain a pore network reference image, wherein the lines of the pore network in the pore network reference image are clear and consistent with the actual pore network;

[0066] The two-phase distribution map of the saturated chip 5 obtained in step S1 is selected to extract the pore network curve, avoiding the influence of the CO2 and brine two-phase interface. In this embodiment, the two-phase distribution map of the saturated chip 5 is processed by binarization, denoising, edge contour extraction, interface segmentation, de-coinciding lines, and sharpening. This produces a pore network reference image with clear lines consistent with the actual pore network, which is convenient for subsequent numerical simulation.

[0067] S5, using the pore network in the pore network reference image, numerical simulation is repeated with the same experimental conditions as in the displacement test and the imbibition test, and the simulation setting conditions are adjusted until the pressure change curve and the two-phase distribution diagram of the displacement stage of the numerical simulation are respectively consistent with the pressure change curve and the two-phase distribution diagram in S2. Figure 1 The pressure change curve and two-phase distribution diagram of the numerical simulation in the imbibition stage are consistent with the pressure change curve and two-phase distribution diagram in S3. Figure 1 To.

[0068] Experimental conditions include: fluid properties of CO2 and the displaced fluid, displacement injection rate, static pressure at the first and second inlets during the imbibition phase, wettability of the porous medium (characterized by contact angle), and initial pressure within the chip. Simulation settings include the simulation algorithm, initial step size, solver type, and the selection of wall slip in the wall conditions, where wall slip is categorized as either no slip or slip.

[0069] Numerical simulations were performed by selecting different simulation algorithms, different initial step sizes, different solvers, and wall slip properties until the pressure change curve and two-phase distribution diagram of the displacement stage of the numerical simulation were respectively consistent with the pressure change curve and two-phase distribution diagram in S2. Figure 1 The pressure change curve and two-phase distribution diagram of the numerical simulation in the imbibition stage are respectively consistent with the pressure change curve and two-phase distribution diagram in S3. Figure 1 To.

[0070] In this case, the phase field method is selected as the numerical simulation algorithm, and the CO2-brine displacement process is analyzed based on the Navier-Stokes equation coupled with the phase field equation. The model boundary condition is set to a no-slip wall, and the contact angle inside the pore network is set to the contact angle obtained in S2 (i.e., 30°); during the CO2 displacement of brine stage, the simulation first inlet and outlet velocity is set to be equal to the displacement injection rate in S2, i.e., 10μl / min, and the second inlet and outlet pressure is 0Pa; during the brine imbibition stage, the static pressure of the first inlet and outlet is set to 0Pa, and the static pressure of the second inlet and outlet is set to 0Pa; after the simulation, the pressure cloud map, CO2 flow rate distribution cloud map, CO2 volume fraction change curve, etc. in the chip pore network model can be viewed;

[0071] Comparing the pressure change curves of the first inlet and outlet obtained from the test and numerical simulation, both satisfy the rule that the pressure at the first inlet and outlet rises before CO2 breakthrough and gradually decreases after CO2 breakthrough, with similar pressure peaks. At the moment of CO2 breakthrough, the two-phase distribution diagrams in the test and numerical simulation are similar, and the dominant channel in the test and the dominant channel in the numerical simulation have a high degree of overlap.

[0072] During the brine imbibition stage, the CO2 residuals in the experiment and the numerical simulation both meet the characteristics of accumulation at the imbibition outlet (i.e., the first inlet and outlet), with more residuals at the pore edges and dead holes; overall, the numerical simulation results obtained according to the experimental conditions meet the objective laws and are reliable.

[0073] S6. Use the final simulation setting conditions of S5 (including simulation algorithm, initial step size, solver type, and wall slip in wall conditions) as the simulation setting conditions for numerical simulation sensitivity analysis; then perform numerical simulation sensitivity analysis under the same experimental conditions by changing one of the factors to be analyzed one by one while keeping the other factors in the factors to be analyzed unchanged.

[0074] This case study analyzes the effect of contact angle on CO2 residual capture. Based on the final simulation setting conditions of S5, with contact angle as the changing factor, CO2 displacement brine simulations with contact angles of 30°, 45°, 60°, 90°, 120°, 135°, and 150°, as well as brine imbibition simulations with contact angles of 30°, 45°, and 60° were carried out. The numerical simulation results show that in hydrophilic media, the initial CO2 saturation increases with decreasing contact angle, while in CO2-philic media, the initial CO2 saturation increases with increasing contact angle. In hydrophilic media, a decrease in contact angle will produce a larger number of snap-off events, thereby increasing the amount of CO2 residual capture.

[0075] The displaced fluid in the above step S1 can be a mixture of brine and pure water with different components according to test requirements.

[0076] The above steps S2 and S3 are respectively the displacement of brine by CO2 and the spontaneous imbibition of brine. The initial CO2 saturation and the residual CO2 saturation can be calculated by image processing, and the CO2 capture rate at different displacement injection rates can be obtained.

[0077] Numerical simulation in S6 requires setting boundary conditions. Boundary conditions include but are not limited to adjusting the pressure of the first inlet and outlet, the pressure of the second inlet and outlet, the displacement injection velocity, and the wall conditions. The wall conditions include the contact angle and the wall slip. Generally, a no-slip wall is selected. However, for microfluidic experiments, some pore throats are small, and the velocity field from the wall to the center of the pore throat changes little, so a slip wall can be selected.

[0078] Improving numerical simulation algorithms includes but is not limited to using different simulation methods, such as phase field method, level set method, moving mesh method, fluid volume method, etc.

[0079] The present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely descriptions of preferred embodiments of the present invention and do not limit the concept of the present invention. The implementation schemes in the above-mentioned embodiments can be further combined or replaced. Various changes and improvements made by those skilled in the art to the technical solutions of the present invention all fall within the scope of protection of the present invention.

Claims

1. A pore-scale CO2 residual capture device, characterized in that: The invention comprises a pump (1), wherein the piston of the pump (1) is connected to the piston of the syringe (2); the water outlet of the barrel of the syringe (2) is connected to a first pressure sensor (9) through a hose, the first pressure sensor (9) is connected to a first inlet and outlet on a chip (5) in turn through a hose and a hose connector, the first inlet and outlet are connected to a second inlet and outlet on the chip (5) through a pore network etched in the chip (5), the second inlet and outlet of the chip (5) are connected to a second pressure sensor (10) through a hose connector and a hose in turn, and the second pressure sensor (10) is connected to the displaced fluid in a beaker (6) through a hose; an imbibition pressure difference regulating device (11) is provided below the beaker (6); a high-speed camera (7) is provided above the chip (5), and the high-speed camera (7) is fixed in position by a camera fixture (8); the first pressure sensor (9), the second pressure sensor (10) and the high-speed camera (7) all transmit data to a computer through a data line; When performing a displacement test, the syringe (2) injects CO2 into the chip (5), and the computer draws a pressure change curve in the displacement test phase in real time based on the pressure change data detected by the first pressure sensor (9); draws a curve of the relationship between the initial saturation of CO2 and time in the displacement test based on the two-phase distribution diagram in the displacement test phase; and measures and statistics the contact angles between the CO2 in the chip (5), the displaced fluid, and the solid wall based on the two-phase distribution diagram in the displacement test phase; When the imbibition test is carried out, the injection of CO2 is stopped, and the computer draws a pressure change curve of the imbibition test stage in real time based on the pressure change data detected by the second pressure sensor (10); and draws a curve of the relationship between the CO2 residual saturation and time in the imbibition test based on the two-phase distribution diagram of the imbibition test stage.

2. The pore-scale CO2 residual capture device according to claim 1, characterized in that: The chip (5) is made of a transparent material and is fixed on the hollow fixture (4). The light emitted by the fill light (3) passes through the hollow area of ​​the fixture (4) from below the fixture (4) and irradiates the chip (5).

3. A multi-factor sensitivity analysis method for CO2 residual capture at the pore scale, using the CO2 residual capture device at the pore scale according to claim 2, characterized in that: The steps include: S1. Build a CO2 residual capture device at the pore scale, draw the displaced fluid into the syringe (2), and drive the syringe (2) to inject the displaced fluid into the chip (5) at a set fluid injection speed by the pump (1) until the chip (5) is in a saturated state; The high-speed camera (7) collects the two-phase distribution diagram in the saturated chip (5); S2. Replace a syringe (2) filled with dry CO2 and conduct a displacement test: The pump (1) causes the syringe (2) to inject CO2 into the chip (5) at a set displacement injection speed; At the same time, the first pressure sensor (9) detects the pressure change of the first inlet and outlet during the displacement test phase, the second pressure sensor (10) detects the pressure change of the second inlet and outlet during the displacement test phase, and the high-speed camera (7) collects the two-phase distribution diagram of the chip (5) during the displacement test phase; The computer draws a pressure change curve in the displacement test phase in real time based on the pressure change data detected by the first pressure sensor (9); draws a curve of the relationship between the initial saturation of CO2 and time in the displacement test based on the two-phase distribution diagram in the displacement test phase; and obtains the contact angle between the CO2, the displaced fluid and the solid wall surface in the chip (5) by measuring and statistically analyzing the two-phase distribution diagram in the displacement test phase; S3. When the initial CO2 saturation reaches the preset CO2 initial saturation threshold, stop injecting CO2 and conduct the imbibition test: The CO2 residual capture device at the pore scale is kept stationary; the displaced fluid inside the beaker (6) absorbs the CO2 in the displaced chip (5) under the capillary pressure of the hose and produces CO2 residual; At the same time, the first pressure sensor (9) detects the pressure change of the first inlet and outlet during the imbibition test phase, and the second pressure sensor (10) detects the pressure change of the second inlet and outlet during the imbibition test phase; the high-speed camera (7) collects the two-phase distribution diagram of the chip (5) during the imbibition test phase; The computer draws a pressure change curve during the imbibition test in real time based on the pressure change data detected by the second pressure sensor (10); and draws a curve of the relationship between the CO2 residual saturation and time during the imbibition test based on the two-phase distribution diagram during the imbibition test; S4, processing the two-phase distribution map in the chip (5) after saturation in step S1 to obtain a pore network reference image, wherein the lines of the pore network in the pore network reference image are clear and consistent with the actual pore network; S5. Using the pore network in the experimental reference image, numerical simulation is performed to replicate the displacement test and the imbibition test under the same experimental conditions as in the displacement test and the imbibition test, and the simulation setting conditions are adjusted until the pressure change curve and the two-phase distribution diagram in the numerical simulation displacement stage are consistent with the pressure change curve and the two-phase distribution diagram in S2, respectively, and the pressure change curve and the two-phase distribution diagram in the numerical simulation imbibition stage are consistent with the pressure change curve and the two-phase distribution diagram in S3; S6. Use the final simulation setting conditions of S5 as the simulation setting conditions for the numerical simulation sensitivity analysis; Then, the sensitivity analysis of numerical simulation under the same experimental conditions was carried out by changing one of the factors to be analyzed one by one while keeping the other factors unchanged.

4. The multi-factor sensitivity analysis method for CO2 residual capture at the pore scale according to claim 3 is characterized in that: The displaced fluid is a mixture of brine and pure water with different components.

5. The multi-factor sensitivity analysis method for CO2 residual capture at the pore scale according to claim 3 is characterized in that: The factors to be analyzed in S6 include: The fluid properties of the displaced fluid, the displacement injection rate, the wettability of the porous medium, the initial pressure inside the chip (5), the static pressure at the first inlet and outlet during the imbibition phase, and the static pressure at the second inlet and outlet; Among them, fluid properties include viscosity and density, and the wettability of porous media is characterized by contact angle.

6. The multi-factor sensitivity analysis method for CO2 residual capture at the pore scale according to claim 3, characterized in that: The simulation setting conditions in S6 include simulation algorithm, initial step size, solver type and wall slip, and wall slip is divided into no slip and slip.

7. The multi-factor sensitivity analysis method for CO2 residual capture at the pore scale according to claim 6, characterized in that: The simulation algorithms in S6 include phase field method, level set method, moving grid method and fluid volume method.

8. The multi-factor sensitivity analysis method for CO2 residual capture at the pore scale according to claim 3, characterized in that: Said S1 further includes the following steps: During the process of injecting the displaced fluid into the chip (5), the airtightness of the device is observed and checked. If no displaced fluid overflows from the hose connection, and the readings of the first pressure sensor (9) and the second pressure sensor (10) are stable and have no obvious fluctuations after being saturated with salt water, the airtightness of the device is good. If the airtightness of the device is poor, the device is adjusted or rebuilt before injecting the displaced fluid into the chip (5).

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