A two-dimensional physical simulation experimental apparatus and method for CO2 utilization and storage in gas reservoirs.

Abstract

This invention discloses a two-dimensional physical simulation experimental device and method for CO2 utilization and storage in gas reservoirs. This experimental method enhances natural gas recovery by injecting CO2 and conducts storage simulation experiments. In this experiment, CO2 with an extracted indicator is injected into a sand-filled model saturated with natural gas to conduct a gas drive experiment. Then, an X-CT scanner is used to scan the long core model at different times. The attenuated X-rays are projected onto developing paper, and high-definition cameras are used to capture images of the developing paper at different times. The light intensity at each point in the developing paper images at different times is statistically processed to obtain the CO2 concentration at different points at different times. This allows for real-time monitoring of the CO2 distribution in the core model at different times, and the study of CO2 driving mechanism, migration, and storage laws.

Description

Technical Field

[0001] This invention relates to the field of energy simulation experiment technology, specifically to a two-dimensional physical simulation experimental device and method for CO2 utilization and storage in gas reservoirs. Background Technology

[0002] Carbon capture, utilization, and storage (CCUS) technology refers to the process of separating CO2 from industrial processes, energy utilization, or the atmosphere and directly utilizing it or injecting it into the formation to achieve permanent CO2 emission reduction. This is of great significance for mitigating global warming and environmental protection. Injecting CO2 into a gas reservoir can effectively displace natural gas through CO2 mass transfer and diffusion; on the other hand, a significant portion of the injected gas is sealed underground, thus effectively achieving carbon sequestration. After CO2 is injected into the gas reservoir, CO2 and natural gas become miscible, and the plume phenomenon and mass transfer and diffusion behavior of CO2 in the formation determine the recovery efficiency of natural gas. Given the complex phase state and flow behavior after supercritical CO2 injection into natural gas reservoirs, theoretical numerical simulation studies still need improvement; physical simulation experiments are the most realistic way to accurately study the diffusion and mass transfer behavior of injected CO2 in gas reservoirs. Some related technologies have already been publicly disclosed.

[0003] Patent CN202410231214.3 discloses a real-time monitoring device for carbon dioxide displacement under high and low temperature and high pressure conditions. This device primarily utilizes nuclear magnetic resonance (NMR) technology to monitor hydrogen (H) in rocks and measure the oil-water distribution in a model, indirectly observing CO2 distribution through changes in oil and water distribution. However, this device can only monitor CO2 in the presence of oil or water and cannot be used for CO2-driven natural gas experiments. Furthermore, NMR instruments are expensive and have significant operational limitations.

[0004] Patent CN202211406780.0 discloses a method for simulating carbon dioxide distribution monitoring during the process of carbon dioxide displacing methane. This method involves vertically penetrating the coal seam floor by arranging several concentric sampling tubes and pressure sampling tubes evenly in a circular pattern. The sampling tubes on the same circumference are spaced apart circumferentially. The upper ends of each sampling tube are inserted into the coal reservoir, and the lower ends of each tube are connected to a gas chromatograph. The gas chromatograph monitors the CO2 concentration changes at different locations on the coal seam floor. This method has a complex setup, requires a large number of gas chromatographs, and is costly. Furthermore, the gas chromatograph takes a long time to measure gas components each time, and the CO2 concentration changes continuously during the measurement process, making it impossible to achieve true real-time monitoring of CO2 concentration changes.

[0005] The main problem with existing technologies is their inability to characterize the reservoir diffusion and mass transfer mechanisms of CO2-natural gas under in-situ formation conditions. Therefore, this application proposes a physical simulation experimental device for CO2 burial in gas reservoirs. CO2 with an extracted indicator is injected into a sand-filled model saturated with natural gas for gas drive experiments. Then, an X-ray CT scanner is used to scan the long core model at different times, and the attenuated X-rays are projected onto developing paper. High-definition cameras are used to capture images of the developing paper at different times. Statistical processing of the light intensity at various points in the developing paper images at different times allows for the determination of CO2 concentrations at different points and times. This enables real-time monitoring of the CO2 distribution in the core model at different times, facilitating the study of CO2 driving mechanisms, migration, and burial patterns. Summary of the Invention

[0006] The purpose of this invention is to provide a two-dimensional physical simulation experimental device and method for CO2 utilization and storage in gas reservoirs, so as to solve the problem in the background art that it is impossible to characterize the reservoir diffusion and mass transfer law of CO2-natural gas under in-situ formation conditions.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a two-dimensional physical simulation experimental device and method for CO2 utilization and storage in gas reservoirs, comprising: a CO2 displacement system, an X-ray scanning system, and a metering system;

[0008] The CO2 displacement system includes an ISCO plunger dual pump, an intermediate container holding CO2 carrying developer, an intermediate container holding simulated formation gas, a core model holder, a pressure gauge, a backpressure valve, a backpressure pump, a temperature monitor, an intermediate container holding nitrogen, and an ISCO plunger confining pressure pump. One end of the ISCO plunger dual pump is connected to the intermediate container holding CO2 carrying developer and the intermediate container holding simulated formation gas, respectively. The other ends of the intermediate containers holding CO2 carrying developer and simulated formation gas are connected to the core model holder. The core model holder is also connected to a pressure gauge, a temperature monitor, and the intermediate container holding nitrogen, respectively. The other end of the pressure gauge is connected to the backpressure valve, and the backpressure valve is also connected to another set of pressure gauges, which are connected to the backpressure pump. The other end of the intermediate container holding nitrogen is connected to the ISCO plunger confining pressure pump.

[0009] X-ray scanning system, including X-ray scanning control computer, high-definition camera, and X-CT scanner;

[0010] Metering systems, including gas meters and gas chromatographs;

[0011] The core model holder includes a vessel body, a right end cover, and a left end cover. The right and left end covers are connected to the vessel body by right-end bolts and left-end bolts, respectively, and both are sealed with rubber sealing rings to ensure the vessel body's airtightness. An X-ray source is placed in the left end cover, which is separated from the experimental chamber by a left-end sapphire glass plate. A high-definition camera is placed in the right end cover, which is also separated from the experimental chamber by a right-end sapphire glass plate. The right end cover also has a confining pressure channel, which is connected to an intermediate container holding nitrogen gas via a pipeline.

[0012] The right end cover has a displacement inlet on its inner side, which is connected to an intermediate container for CO2 and an intermediate container for simulated formation gas via pipelines. The right end cover also has a displacement outlet on its inner side, which is connected to a back pressure valve via pipelines. The right end cover also has a temperature monitoring and control channel on its inner side, which is connected to a heating plate and a temperature monitor via wires.

[0013] A core model is mounted on the inner side of the right end cover via a bracket. The core model includes a lower cover plate, developing paper, a transparent sleeve, a fixing frame, a sand-filling model, and an upper cover plate. The developing paper is fixed at the bottom of the lower cover plate, the sand-filling model is placed in the middle of the transparent sleeve, the front end of the fixing frame is wrapped with the transparent sleeve, and the rear end of the fixing frame is fixed to the lower cover plate and the upper cover plate by bolts. The lower cover plate and the upper cover plate are connected and fixed by bolts. Inlet and outlet channels are provided on the upper cover plate, the lower cover plate, and the fixing frame.

[0014] Preferably, valves are connected to both ends of the intermediate container holding CO2 containing developer and the intermediate container holding simulated formation gas.

[0015] Preferably, a valve is provided at the connection between the core model holder and the pressure gauge.

[0016] Preferably, a two-dimensional physical simulation experimental method for CO2 utilization and storage in gas reservoirs includes the following steps in the experimental setup:

[0017] Step 1: Construct a sand-filled model and complete model assembly. Based on the physical property parameters and reservoir characteristic parameters of the target oil reservoir, construct a sand-filled model and drill a small plunger model to test its permeability, porosity and other physical property parameters until they meet the requirements.

[0018] Step 2: The absorption coefficient K of CO2 extracted with the indicator was calibrated. CO2 was then injected into the vacuum-filled sand model. After the CO2 penetrated the model, the scanning and photographing results were compared with the initial image. The relationship between the total brightness change and the total increase in matter relative to the initial image can be expressed as:

[0019]

[0020] Among them, K is the absorption rate of the substance, l is the thickness of the substance, C is the concentration of the absorbing substance. I0 is the initial light intensity, and I t is the light intensity after passing through the substance.

[0021] Before the breakthrough of CO2 to the outlet of the core model, the total amount of injected CO2 is equal to the increased CO2 content in the model. Divide the corresponding points of each picture and then take the logarithmic sum, that is, KΣ(l*c), where Σ(l*c) is the thickness of each point multiplied by the concentration, that is, the sum of the CO2 content, which is equal to the injected CO2 amount. In this way, the absorption coefficient K of CO2 extracting the indicator can be calibrated;

[0022] Step 3: Saturate the formation gas. Open the intermediate container 15 containing nitrogen, and then inject nitrogen into the clamping device kettle body through the ISCO plunger confining pressure pump to maintain the confining pressure Pconf; then, evacuate the sand-packed model with a vacuum pump, set the backpressure pump 13 to the target formation pressure P0 (P0 < Pconf), and then open the intermediate container 5 containing the simulated formation gas, and inject formation gas into the sand-packed model through the ISCO plunger double pump. When the internal pressure of the model stabilizes to the pressure P0, stop injecting, and record the injected formation gas volume V0 to complete the saturation of the formation gas;

[0023] Step 4: Depletion production. Reduce the pressure of the backpressure pump 13 at a reasonable gradient speed to slowly deplete the natural gas inside the sand-packed model. At the same time, record the produced gas volume V1 through the gas flowmeter 12, and measure the components of the produced natural gas with the gas chromatograph 42. At this time, the recovery rate of depletion production is

[0024] Step 5: Inject CO2 to displace gas to improve the recovery rate. Open the X-ray scanning system and the ISCO plunger double pump 1, and inject CO2 into the sand-packed model. Record the injected CO2 gas volume V2, let CO2 displace the formation natural gas, and the outlet flowmeter measures the produced gas volume V3 at all times. At the same time, obtain the concentration of CO2 and the natural gas concentration Cg in the produced gas through the gas chromatograph. At the same time, the X-CT scanner emits X-rays to the sand-packed model at all times. After the X-rays pass through the sand-packed model, they are projected onto the developing paper. Then, set a reasonable exposure time for the high-definition camera and take pictures of the developing paper at different gas displacement times, and then process the pictures to obtain a high-resolution distribution map of CO2 in the rock, so as to study the migration path and distribution law of CO2 during the process of injecting CO2 to improve the recovery rate and storage.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. This study utilizes a two-dimensional physical simulation experimental device and method to conduct CO2 injection experiments to enhance oil recovery and storage in the gas reservoir. Based on the physical properties and reservoir characteristics of the target reservoir, a sand-filled model is constructed. During a specific production stage of the gas reservoir (e.g., the later stages of depletion-induced gas recovery), CO2 is injected to enhance natural gas recovery, and storage simulation experiments are conducted.

[0027] 2. The CO2 reservoir utilizes a two-dimensional physical simulation experimental device and method to optimize the timing of CO2 injection to enhance oil recovery and storage. CO2 is injected at different times to displace natural gas. The final recovery rate and the amount of CO2 stored in the model are detected and compared by gas chromatography to optimize the timing of CO2 injection to enhance natural gas recovery and storage.

[0028] 3. Using a two-dimensional physical simulation experimental device and method for CO2 storage in this gas reservoir, the migration path and distribution law of CO2 during CO2 injection for enhanced oil recovery and storage were studied. The location of CO2 extracted with X-ray indicator (such as iodoethane or iodopropane) in the sand-filled model was identified by X-ray scanning. By setting an appropriate exposure time for a high-definition camera, the developing paper was photographed, and the photographs were processed to obtain a high-resolution distribution map of CO2 in the rock. The migration path and distribution law of CO2 during CO2 injection for enhanced oil recovery and storage were then studied. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the physical simulation experimental device of the present invention;

[0030] Figure 2 This is a cross-sectional view of the displacement clamp portion in the device of the present invention;

[0031] Figure 3 This is a three-dimensional schematic diagram of the displacement clamp part in the device of the present invention;

[0032] Figure 4 This is a three-dimensional schematic diagram of the core model in this invention.

[0033] In the diagram: 1. ISCO dual plunger pump; 2, 3, 6, 7, 9. Valves; 4. Intermediate container holding CO2 containing developer; 5. Intermediate container holding simulated formation gas; 8. Core model holder; 10. Pressure gauge; 11. Back pressure valve; 12. Gas meter; 13. Back pressure pump; 14. Temperature monitor; 15. Intermediate container holding nitrogen; 16. ISCO plunger confining pressure pump; 17. X-ray scanning control computer; 18. Confining pressure channel; 19. Displacement inlet; 20. High-definition camera; 21. Displacement outlet; 22. 1. Temperature monitoring and control channel; 23. Right end bolt; 24. Rubber sealing ring; 25. Left end bolt; 26. Right end sapphire glass plate; 27. Heating plate; 28. Core model; 29. ​​Left end sapphire glass plate; 30. X-ray and CT scanner; 31. Reactor body; 32. Right end cover; 33. Left end cover; 34. Lower cover plate; 35. Developing paper; 36. Transparent sleeve; 37. Fixing bracket; 38. Upper cover plate; 39. Outlet channel; 40. Inlet channel; 41. Sand filling model; 42. Gas chromatograph; 43. Fixing bracket bolt. Detailed Implementation

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] Please see Figure 1-4 The present invention provides a technical solution: a two-dimensional physical simulation experimental device and method for CO2 utilization and storage in gas reservoirs, including: a CO2 displacement system, an X-ray scanning system, and a metering system;

[0036] The CO2 displacement system includes an ISCO dual plunger pump 1, an intermediate container 4 containing CO2 carrying developer, an intermediate container 5 containing simulated formation gas, a core model holder 8, a pressure gauge 10, a back pressure valve 11, a back pressure pump 13, a temperature monitor 14, an intermediate container 15 containing nitrogen, and an ISCO plunger confining pressure pump 16. One end of the ISCO dual plunger pump 1 is connected to both the intermediate container 4 (containing CO2 carrying developer) and the intermediate container 5 (containing simulated formation gas). Valves 2 and 6 are connected to the two ends of the intermediate containers 4 and 5, respectively. In addition to valves 3 and 7, the other ends of the intermediate container 4 containing CO2 carrying developer and the intermediate container 5 containing simulated formation gas are connected to the core model holder 8. The core model holder 8 is also connected to a pressure gauge 10, a temperature monitor 14 and an intermediate container 15 containing nitrogen. A valve 9 is provided at the connection between the core model holder 8 and the pressure gauge 10. The other end of the pressure gauge 10 is connected to a back pressure valve 11. The back pressure valve 11 is also connected to another set of pressure gauges 10. The other set of pressure gauges 10 is connected to a back pressure pump 13. The other end of the intermediate container 15 containing nitrogen is connected to an ISCO plunger confining pressure pump 16.

[0037] The X-ray scanning system includes an X-ray scanning control computer 17, a high-definition camera 20, and an X-CT scanner 30;

[0038] The metering system includes a gas meter 12 and a gas chromatograph 42;

[0039] The core model holder 8 includes a vessel body 31, a right end cover 32, and a left end cover 33. The right end cover 32 and the left end cover 33 are connected to the vessel body 31 by right end bolts 23 and left end bolts 25, respectively, and both are sealed by rubber sealing rings 24 to ensure the vessel body's airtightness. An X-ray source 30 is placed in the left end cover 33, which is separated from the experimental chamber by a left end sapphire glass plate 29. A high-definition camera 20 is placed in the right end cover 32, which is separated from the experimental chamber by a right end sapphire glass plate 26. The right end cover 32 also has a confining pressure channel 18, which is connected to an intermediate container 15 containing nitrogen gas via a pipeline.

[0040] A displacement inlet 19 is provided inside the right end cover 32. The displacement inlet 19 is connected to the intermediate container 4 containing CO2 and the intermediate container 5 containing simulated formation gas through pipelines. A displacement outlet 21 is also provided inside the right end cover 32. The displacement outlet 21 is connected to the back pressure valve 11 through pipelines. A temperature monitoring and control channel 22 is provided inside the right end cover 32. The temperature monitoring and control channel 22 is connected to the heating plate 27 and the temperature monitor 14 through wires.

[0041] A core model 28 is mounted on the inner side of the right end cover 32 via a bracket. The core model 28 includes a lower cover plate 34, developing paper 35, transparent plastic sleeve 36, fixing frame 37, sand filling model 41, and upper cover plate 38. The developing paper 35 is fixed at the bottom of the lower cover plate 34, and the sand filling model 41 is placed in the middle of the transparent plastic sleeve 36. The front end of the fixing frame 37 is wrapped with the transparent plastic sleeve 36, and the rear end of the fixing frame 37 is fixed to the lower cover plate 34 and the upper cover plate 38 by bolts 43. The lower cover plate 34 and the upper cover plate 38 are connected and fixed by bolts 43. An inlet channel 39 and an outlet channel 40 are provided on the upper cover plate 38, the lower cover plate 34, and the fixing frame 37.

[0042] The physical simulation experimental device for CO2 burial in gas reservoirs can conduct high-temperature and high-pressure CO2 displacement and burial experiments, and monitor the distribution of CO2 in the core model in real time, generating a high-resolution CO2 plume distribution map. This CO2 plume distribution map is identified based on the following principles:

[0043] X-rays have strong penetrating power, allowing direct observation of the interior of rock cores through titanium or aluminum alloy holders. CO2 has strong extraction capabilities, and under high temperature and pressure conditions, volatile oily markers (such as iodoethane and iodopropane) can be easily added. Adding markers increases the attenuation rate of CO2 on X-rays while having minimal impact on the inherent properties of CO2. Therefore, iodoethane (or iodopropane, etc.) can be added to CO2 as an X-ray indicator, allowing X-ray CT to easily locate the CO2. The intensity of the rays projected onto the developing paper will also differ accordingly. By setting an appropriate exposure time with a high-definition camera, photographing the developing paper, and then processing the images, a high-resolution map of CO2 distribution in the rock can be obtained.

[0044] Calculation method:

[0045] The attenuation of X-rays as they pass through matter can generally be described by the Lambert-Beer law. The formula is:

[0046]

[0047] In the formula, K is the absorptivity of the substance, l is the thickness of the substance, and C is the concentration of the absorbing substance. I0 is the initial light intensity, I t Let be the light intensity after passing through the material. For a point, taking the logarithm of the ratio of the light intensity of the same material after attenuation to that before attenuation yields a result that is linearly related to the thickness of the material.

[0048] After CO2 intrusion into the model, the scanning and photographing results are compared with the initial image. The relationship between the change in total brightness and the increase in total matter relative to the initial image can be expressed as:

[0049]

[0050] Before CO2 breaks through to the core model outlet, the total amount of injected CO2 equals the increase in CO2 content within the model. Dividing the corresponding points in each image and then summing the logarithms yields K∑(l*c), where ∑(l*c) represents the thickness of each point multiplied by its concentration, i.e., the sum of the CO2 contents, which equals the amount of injected CO2. This allows us to calibrate the CO2 absorption coefficient K of indicators with different levels of extraction.

[0051] During the experiment, corresponding images were obtained at different stages. The light intensity at the same location in the images taken at different time points was divided by the logarithm, and then divided by the calibrated absorption coefficient K to obtain the concentration of CO2 absorbed by each pixel, thus obtaining the specific distribution of CO2 at different locations.

[0052] Implementation method: A two-dimensional physical simulation experimental method for CO2 utilization and storage in gas reservoirs, comprising the following steps:

[0053] Step 1: Create a sand-filled model and assemble it;

[0054] Based on the physical properties and reservoir characteristics of the target reservoir, a sand-filled model is constructed, and a small plunger model is drilled to test its permeability, porosity, and other physical properties until they meet the requirements. Then, the prepared sand-filled model 41 and the fixing frame 37 are sequentially placed into the rubber sleeve 36 and placed on the developing paper in the lower cover plate 34. The upper cover plate 38 is then placed on top, and the fixing frame is secured to the upper and lower cover plates with bolts. The upper and lower cover plates are then secured and sealed with bolts. The constructed model is fixed to the right end cover 32 of the clamp 8. The heating plate 27 is installed inside the vessel body 31, and the wiring connections are checked for proper functioning, and the temperature monitoring and control are verified to be accurate and stable. Then, the right end cover 32 and the left end cover 33 are connected and fixed to the vessel body 31 with bolts, and a rubber sealing ring 24 is used to ensure a tight seal. After assembling the clamp, the CO2 displacement system, X-ray scanning system, and metering system are sequentially connected and assembled.

[0055] Step 2: Calibrate the absorption coefficient K of CO2 extracted from the indicator;

[0056] CO2 was injected into a vacuum-filled sand model. After the CO2 penetrated the model, the scanning and photographing results were compared with the initial image. The relationship between the change in total brightness and the increase in total matter relative to the initial image can be expressed as:

[0057]

[0058] Where K is the absorptivity of the substance, I is the thickness of the substance, and C is the concentration of the absorbing substance. I0 is the initial light intensity, I t The intensity of light after passing through the material.

[0059] Before the CO2 breaks through to the outlet of the core model, the total amount of injected CO2 is equal to the increased CO2 content in the model. Divide the corresponding points of each picture and then take the logarithm and sum, that is, K∑(l*c), where Σ(l*c) is the thickness of each point multiplied by the concentration, that is, the sum of the CO2 content, which is equal to the injected CO2 amount. In this way, the absorption coefficient K of the CO2 that extracts the indicator can be calibrated.

[0060] Step 3: Saturate the formation gas;

[0061] Open the intermediate container 15 containing nitrogen, and then inject nitrogen into the clamping device kettle body through the ISCO piston confining pressure pump to maintain the confining pressure P围; then, evacuate the sand-filled model with a vacuum pump, set the back pressure pump 13 to the target formation pressure P0 (P0 < P围), and then open the intermediate container 5 containing the simulated formation gas, and inject the formation gas into the sand-filled model through the ISCO piston double pump. When the internal pressure of the model stabilizes to the pressure P0, stop injecting, and record the injected formation gas volume V0 to complete the saturation of the formation gas.

[0062] Step 4: Depletion production;

[0063] Reduce the pressure of the back pressure pump 13 at a reasonable gradient speed to slowly deplete the natural gas inside the sand-filled model. At the same time, record the produced gas volume V1 through the gas flow meter 12, and measure the components of the produced natural gas with the gas chromatograph 42. At this time, the recovery rate of depletion production is

[0064] Step 5: Inject CO2 to displace gas and improve the recovery rate;

[0065] Turn on the X-ray scanning system, including the X-ray scanning control computer 17, the high-definition camera 20, and the X-CT scanner 30. Open the intermediate container 4, and then inject CO2 into the sand-filled model through the ISCO piston double pump 1. Record the injected CO2 gas volume V2, and let the CO2 displace the formation natural gas. The outlet flow meter measures the produced gas volume V3 at all times. At the same time, obtain the concentration of CO2 and the natural gas concentration Cg in the produced gas through the gas chromatograph. At the same time, the X-CT scanner emits X-rays to the sand-filled model at all times. After the X-rays pass through the sand-filled model, they are projected onto the developing paper. Then, set a reasonable exposure time for the high-definition camera and take pictures of the developing paper at different gas displacement times.

[0066] Divide the light intensities of the same position points on the photos at different times, take the logarithm, and then divide by the calibrated absorption coefficient K to obtain the concentration of the absorbed CO2 at each pixel point, and obtain the distribution and concentration of CO2 at different positions:

[0067]

[0068] Where K is the absorption rate of the substance, l is the thickness of the substance, and C is the thickness of the substance. i This represents the concentration of the absorbed substance. I 0i Let I be the initial light intensity at point i on the developing paper. ti Let be the light intensity at time t on the developing paper.

[0069] Simultaneously, the total recovery rate after gas drive can be obtained. CO2 storage volume is

[0070] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A two-dimensional physical simulation experimental device for CO2 utilization and storage in gas reservoirs, characterized in that, include: CO2 displacement system, X-ray scanning system, metrology system; The CO2 displacement system includes an ISCO plunger dual pump, an intermediate container holding CO2 carrying developer, an intermediate container holding simulated formation gas, a core model holder, a pressure gauge, a backpressure valve, a backpressure pump, a temperature monitor, an intermediate container holding nitrogen, and an ISCO plunger confining pressure pump. One end of the ISCO plunger dual pump is connected to the intermediate container holding CO2 carrying developer and the intermediate container holding simulated formation gas, respectively. The other ends of the intermediate containers holding CO2 carrying developer and simulated formation gas are connected to the core model holder. The core model holder is also connected to a pressure gauge, a temperature monitor, and the intermediate container holding nitrogen, respectively. The other end of the pressure gauge is connected to the backpressure valve, and the backpressure valve is also connected to another set of pressure gauges, which are connected to the backpressure pump. The other end of the intermediate container holding nitrogen is connected to the ISCO plunger confining pressure pump. X-ray scanning system, including X-ray scanning control computer, high-definition camera, and X-CT scanner; The metering system includes a gas meter and a gas chromatograph. The back pressure valve is connected to the inlet of the gas meter, and the outlet of the gas meter is connected to the gas chromatograph. The core model holder includes a vessel body, a right end cover, and a left end cover. The right end cover and the left end cover are connected to the vessel body by right end bolts and left end bolts, respectively, and both are sealed by rubber sealing rings to ensure the vessel body's airtightness. An X-ray source is placed in the left end cover, which is separated from the experimental chamber by a left end sapphire glass plate. A high-definition camera is placed in the right end cover, which is separated from the experimental chamber by a right end sapphire glass plate. A confining pressure channel is also provided in the right end cover, and it is connected to an intermediate container containing nitrogen gas through a pipeline. The right end cover has a displacement inlet on its inner side, which is connected to an intermediate container for CO2 and an intermediate container for simulated formation gas via pipelines. The right end cover also has a displacement outlet on its inner side, which is connected to a back pressure valve via pipelines. The right end cover also has a temperature monitoring and control channel on its inner side, which is connected to a heating plate and a temperature monitor via wires. A core model is mounted on the inner side of the right end cover via a bracket. The core model includes a lower cover plate, developing paper, a transparent sleeve, a fixing frame, a sand-filling model, and an upper cover plate. The developing paper is fixed at the bottom of the lower cover plate, and the sand-filling model is placed in the middle of the transparent sleeve. The front end of the fixing frame is wrapped with a transparent sleeve, and the rear end of the fixing frame is fixed to the lower cover plate and the upper cover plate by bolts. The lower cover plate and the upper cover plate are connected and fixed by bolts. Inlet and outlet channels are provided on the upper cover plate, the lower cover plate, and the fixing frame.

2. The two-dimensional physical simulation experimental device for CO2 utilization and storage in a gas reservoir according to claim 1, characterized in that, The intermediate container holding CO2 containing the developer and the intermediate container holding the simulated formation gas are each connected to a valve at both ends.

3. The two-dimensional physical simulation experimental device for CO2 utilization and storage in a gas reservoir according to claim 1, characterized in that, A valve is installed at the connection between the core model holder and the pressure gauge.

4. A two-dimensional physical simulation experimental method for CO2 utilization and storage in gas reservoirs, utilizing the experimental apparatus described in any one of claims 1-3, characterized in that, The experimental method includes the following steps: Step 1: Fabricate the sand-packed model and complete model assembly. According to the physical property parameters and reservoir characteristic parameters of the target reservoir, fabricate the sand-packed model, drill a small plunger model to test its permeability and porosity physical property parameters until they meet the requirements. Step 2: Calibrate the absorption coefficient K of CO2 extracted with an indicator. Inject CO2 into the evacuated sand-packed model. After CO2 invades the model, compare the scanning and photographing results with the initial picture. The relationship between the total brightness change and the total mass increase relative to the initial photograph can be expressed as: Where K is the absorptivity of the substance, l is the thickness of the substance, C is the concentration of the absorbing substance, I0 is the initial light intensity, and I t The intensity of light after it has passed through the material; Before CO2 breaks through to the outlet of the core model, the total amount of injected CO2 is equal to the increased CO2 content in the model. Divide the corresponding points of each picture and then take the logarithm and sum, that is, K∑(l*c), where ∑(l*c) is the thickness of each point multiplied by the concentration, that is, the sum of the CO2 content, equal to the injected CO2 amount. Thus, the absorption coefficient K of CO2 extracted with an indicator can be calibrated. Step 3: Saturate the formation gas. Open the intermediate container (15) containing nitrogen, and then inject nitrogen into the holder autoclave through the ISCO plunger confining pressure pump to maintain the confining pressure Pconf. Then, evacuate the sand-packed model with a vacuum pump, set the back-pressure pump (13) to the target formation pressure P0, P0 < Pconf, then open the intermediate container (5) containing the simulated formation gas, and inject the formation gas into the sand-packed model through the ISCO plunger double pump. When the internal pressure of the model stabilizes at the pressure P0, stop injecting, and record the injected formation gas volume V0 to complete the saturation of the formation gas. Step 4: Depletion extraction. The pressure of the backpressure pump (13) is reduced at a reasonable gradient rate to allow the natural gas inside the sand-filled model to slowly deplete. Simultaneously, the volume of produced gas V1 is recorded using a gas meter (12), and the composition of the produced natural gas is determined using a gas chromatograph (42). At this point, the recovery rate of the depletion extraction is... Step 5: Inject CO2 to displace gas and improve the recovery rate. Open the X-ray scanning system and the ISCO plunger double pump (1), and inject CO2 into the sand-packed model. Record the injected CO2 gas volume V2. Let CO2 displace the formation natural gas. The outlet flowmeter measures the produced gas volume V3 at all times. At the same time, obtain the concentration of CO2 and the natural gas concentration Cg in the produced gas through a gas chromatograph. At the same time, the X-CT scanner emits X-rays towards the sand-packed model at all times. After the X-rays pass through the sand-packed model, they are projected onto the developing paper. Then, set a reasonable exposure time for the high-definition camera, take pictures of the developing paper at different gas displacement times, and then process the pictures to obtain a high-resolution distribution map of CO2 in the rock, so as to study the migration path and distribution law of CO2 during the process of injecting CO2 to improve the recovery rate and storage.

Images