Gas reservoir CO2 utilization and burying two-dimensional physical simulation experiment device and experiment method

Abstract

The invention discloses a gas reservoir CO2 utilization and burying two-dimensional physical simulation experimental device and experimental method.According to the experimental method, CO2 is injected to improve the natural gas recovery rate, a burying simulation experiment is carried out, CO2 extracted with an indicator is injected into a sand filling model saturated with natural gas, a gas drive experiment is carried out, and the gas reservoir CO2 utilization and burying two-dimensional physical simulation experimental device is obtained. Then, an X-CT scanner is used for scanning the long rock core model at different moments, attenuated X-rays are projected to developing paper, a high-definition camera is used for shooting developing paper pictures at different moments, light intensity of all points of the developing paper pictures at different moments is subjected to statistical processing, and CO2 concentrations at different moments and different points can be obtained; therefore, CO2 distribution states in the rock core model at different moments can be monitored in real time, and a CO2 gas driving mechanism and migration and burying rules can be researched.

Description

Technical Field

[0001] The present invention relates to the technical field of energy simulation experiments, and in particular to a two-dimensional physical simulation experimental device and an experimental method for utilization and storage of CO2 in gas reservoirs. Background Art

[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 or injecting it into the formation to achieve permanent CO2 emission reduction. It is of great significance to mitigate global warming and protect the environment. Injecting CO2 into a gas reservoir can, on the one hand, effectively displace natural gas through the mass transfer and diffusion of CO2, and on the other hand, a considerable portion of the injected gas is sealed underground, thereby effectively achieving carbon sequestration. When CO2 is injected into a gas reservoir, CO2 and natural gas will be mixed. The plume phenomenon and mass transfer and diffusion behavior of CO2 in the formation determine the natural gas recovery effect. In view of the complex phase state and flow behavior of supercritical CO2 after injection into a natural gas reservoir, theoretical numerical simulation research needs to be improved. Physical simulation experimental research is the most realistic way to accurately study the diffusion and mass transfer behavior of CO2 injected into a gas reservoir. At present, some related technologies have been disclosed.

[0003] Patent CN202410231214.3 discloses a real-time monitoring device for carbon dioxide displacement under high-temperature and high-pressure conditions. The device mainly uses nuclear magnetic resonance technology to monitor the H element in the rock, measure the oil and water distribution in the model, and indirectly observe the distribution of CO2 through the distribution changes of oil and water. The device can only monitor CO2 in the presence of oil or water, and cannot perform CO2 displacement experiments on natural gas. In addition, nuclear magnetic resonance instruments are expensive and have large operating restrictions.

[0004] Patent CN202211406780.0 discloses a simulation method for monitoring the distribution of carbon dioxide in the process of carbon dioxide displacement of methane. The method is to arrange each chromatographic sampling tube and each pressure sampling tube in a number of concentric circles evenly and vertically through the coal seam floor. The chromatographic sampling tube and the pressure sampling tube on the same circumference are arranged at intervals in the circumferential direction. The upper ends of each chromatographic sampling tube and each pressure sampling tube are inserted into the coal reservoir. The lower ends of each chromatographic sampling tube are connected to a gas chromatograph, and the concentration changes of CO2 at different positions of the coal seam floor are monitored by the gas chromatograph. The method has a complex device layout, a large number of gas chromatographs required, and a high cost. At the same time, the gas chromatograph takes a long time to measure the gas components each time, and the concentration of CO2 has been changing during the measurement process, and it is impossible to achieve real-time monitoring of the concentration changes of CO2.

[0005] The main problem with the existing technology is that it is impossible to characterize the reservoir diffusion and mass transfer law of CO2-natural gas under in-situ formation conditions. Therefore, this application proposes a physical simulation experimental device for CO2 storage in gas reservoirs, which uses CO2 extracted with an indicator to be injected into a sand-filled model saturated with natural gas to conduct a gas drive experiment, and then uses an X-CT scanner to scan the long core model at different times, and the attenuated X-rays are projected onto the developing paper. Use a high-definition camera to take pictures of the developing paper at different times, and perform statistical processing on the light intensity of each point in the developing paper pictures at different times, so as to obtain the CO2 concentration at different points at different times, thereby realizing real-time monitoring of the CO2 distribution state at different times in the core model, and studying the CO2 drive mechanism, migration and storage law. Summary of the invention

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

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

[0008] A CO2 displacement system, comprising an ISCO plunger double pump, an intermediate container for holding CO2 carrying a developer, an intermediate container for holding simulated formation gas, a core model holder, a pressure gauge, a back pressure valve, a back pressure pump, a temperature monitor, an intermediate container for holding nitrogen, and an ISCO plunger confining pressure pump, wherein one end of the ISCO plunger double pump is respectively connected to an intermediate container for holding CO2 carrying a developer and an intermediate container for holding simulated formation gas, the other ends of the intermediate container for holding CO2 carrying a developer and the intermediate container for holding simulated formation gas are connected to the core model holder, the core model holder is also respectively connected to a pressure gauge, a temperature monitor and an intermediate container for holding nitrogen, the other end of the pressure gauge is connected to a back pressure valve, the back pressure valve is also connected to another set of pressure gauges, the other set of pressure gauges is connected to the back pressure pump, and the other end of the intermediate container for 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, X-CT scanner;

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

[0011] The core model holder includes a kettle body, a right end cover and a left end cover, wherein the right end cover and the left end cover are connected to the kettle body through right end bolts and left end bolts respectively, and the sealing of the kettle body is ensured by rubber sealing rings. An X-ray source is placed in the left end cover, and the X-ray source is separated from the experimental cavity by a sapphire glass plate at the left end. A high-definition camera is placed in the right end cover, and is separated from the experimental cavity by a sapphire glass plate at the right end. A confining pressure channel is also provided in the right end cover, and is connected to an intermediate container containing nitrogen through a pipeline;

[0012] A displacement inlet is provided on the inner side of the right end cover, and the displacement inlet is connected to the intermediate container containing CO2 and the intermediate container containing simulated formation gas through pipelines; a displacement outlet is also provided on the inner side of the right end cover, and the displacement outlet is connected to the back pressure valve through pipelines; a temperature monitoring and control channel is provided on the inner side of the right end cover, and the temperature monitoring and control channel is connected to the heating plate and the temperature monitor through wires;

[0013] A core model is installed on the inner side of the right end cover through a bracket. The core model includes a lower cover plate, developing paper, a transparent rubber 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 rubber sleeve, the front end of the fixing frame is wrapped with a transparent rubber 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, and the upper cover plate, the lower cover plate and the fixing frame are all provided with an inlet channel and an outlet channel;

[0014] Preferably, both ends of the intermediate container for holding CO2 carrying the developer and the intermediate container for holding the simulated formation gas are respectively connected with a valve, a valve, and a valve, and a valve.

[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 comprises the experimental device described in claims 1-3, and the experimental device comprises the following steps:

[0017] Step 1: Make a sand filling model and complete the model assembly. According to the physical parameters of the target oil reservoir and the reservoir characteristic parameters, make a sand filling model, and drill a small plunger model to test its permeability, porosity and other physical parameters until it meets the requirements;

[0018] Step 2: Calibrate the absorption coefficient K of CO2 extracted with the indicator, inject CO2 into the vacuumed sand-filled model, and compare the scanning and photographing results with the initial picture after CO2 invades the model. The relationship between the total brightness change and the total substance increase relative to the initial picture 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 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, which is equal to the injected CO2 amount. In this way, the absorption coefficient K of the CO2 extracting the indicator can be calibrated;

[0022] Step 3: Saturate the formation gas. Open the intermediate container 15, and then inject nitrogen into the clamping device kettle body through the ISCO piston 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), then open the intermediate container 5, and inject formation gas into the sand-packed model through the ISCO piston double pump. When the internal air pressure of the model stabilizes to the pressure P0, stop injecting, and record the injected formation gas volume V0 to complete the formation gas saturation;

[0023] Step 4: Depletion exploitation. 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 exploitation is

[0024] Step 5: Inject CO2 to displace gas and improve the recovery rate. Open the X-ray scanning system and the ISCO piston double pump 1, and inject CO2 into the sand-packed model. Record the injected CO2 gas volume V2, let the 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, 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. The two-dimensional physical simulation experimental device and experimental method of CO2 utilization and storage in the gas reservoir are used to conduct CO2 injection to improve the recovery rate and storage experiment in the gas reservoir. According to the physical parameters of the target oil reservoir and the reservoir characteristic parameters, the sand filling model is made. In a certain production stage of the gas reservoir (such as the middle and late stages of gas reservoir depletion exploitation), CO2 is injected to improve the recovery rate of natural gas and a storage simulation experiment is conducted.

[0027] 2. The two-dimensional physical simulation experimental device and experimental method for CO2 utilization and storage in the gas reservoir are used to optimize the timing of CO2 injection to improve the recovery rate and storage, and CO2 is injected at different times to displace natural gas. The final recovery rate at different injection times and the CO2 storage amount in the model are detected and compared by gas chromatograph, so as to optimize the timing of CO2 injection to improve the recovery rate and storage of natural gas.

[0028] 3. The two-dimensional physical simulation experimental device and experimental method for CO2 utilization and storage in the gas reservoir are used to study the migration path and distribution law of CO2 during CO2 injection to improve the recovery rate and storage. The position of CO2 extracted with X-ray indicators (ethyl iodide or propyl iodide, etc.) in the sand filling model is identified by X-ray scanning. By setting the appropriate exposure time of the high-definition camera, taking pictures of the developing paper, and then processing the photos, a high-resolution distribution map of CO2 in the rock can be obtained, and the migration path and distribution law of CO2 during CO2 injection to improve the recovery rate and storage can be studied. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0031] Figure 3 A three-dimensional schematic diagram of a displacing clamp portion in the device of the present invention;

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

[0033] In the figure: 1. ISCO plunger double pump; 2, 3, 6, 7, 9, valve; 4. Intermediate container for CO2 carrying developer; 5. Intermediate container for 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 for nitrogen; 16. ISCO plunger confining pressure pump; 17. X-ray scanning control computer; 18. Confining pressure channel; 19. Displacement inlet; 20. High-definition video camera; 21. Displacement outlet; 22 , 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, CT scanner; 31, kettle body; 32, right end cover; 33, left end cover; 34, lower cover; 35, developing paper; 36, transparent rubber sleeve; 37, fixing frame; 38, upper cover; 39, outlet channel; 40, inlet channel; 41, sand filling model; 42, gas chromatograph; 43, fixing frame bolt. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0035] See also Figure 1-4 ,The present invention provides a technical solution: a two-dimensional physical simulation experimental device and experimental 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 comprises an ISCO plunger double pump 1, an intermediate container 4 for containing CO2 carrying a developer, an intermediate container 5 for 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 for containing nitrogen, and an ISCO plunger confining pressure pump 16. One end of the ISCO plunger double pump 1 is respectively connected to the intermediate container 4 for containing CO2 carrying a developer and the intermediate container 5 for containing simulated formation gas, and both ends of the intermediate container 4 for containing CO2 carrying a developer and the intermediate container 5 for containing simulated formation gas are respectively connected to valves 2 and valves 6. and valve 3, valve 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 respectively 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, and the other end of the intermediate container 15 containing nitrogen is connected to an ISCO plunger confining pressure pump 16;

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

[0038] A metering system, including a gas meter 12 and a gas chromatograph 42;

[0039] The core model holder 8 includes a kettle 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 kettle body 31 through a right end bolt 23 and a left end bolt 25, respectively, and the kettle body is sealed by a rubber sealing ring 24. An X-ray source 30 is placed in the left end cover 33, and the X-ray source 30 is separated from the experimental cavity by a sapphire glass plate 29 at the left end. A high-definition camera 20 is placed in the right end cover 32, and is separated from the experimental cavity by a sapphire glass plate 26 at the right end. A confining pressure channel 18 is also provided in the right end cover 32, and is connected to an intermediate container 15 containing nitrogen through a pipeline;

[0040] A displacement inlet 19 is provided inside the right end cover 32, and 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, and 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, and the temperature monitoring and control channel 22 is connected to the heating plate 27 and the temperature monitor 14 through electric wires;

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

[0042] The gas reservoir CO2 storage physical simulation experimental device can carry out high-temperature and high-pressure CO2 displacement and storage experiments, and monitor the distribution of CO2 in the core model in real time to form a high-resolution CO2 plume distribution map. The CO2 plume distribution map identifies the distribution based on the following principles:

[0043] X-rays have strong penetrability. Through X-rays, the internal conditions of the core can be observed directly through titanium alloy or aluminum alloy holders. CO2 has a strong extraction ability. Under high temperature and high pressure conditions, it is relatively easy to add volatile oily markers (such as ethyl iodide, propyl iodide, etc.). After adding the marker, while increasing the attenuation rate of CO2 to X-rays, the effect on the characteristics of CO2 itself is relatively small. Therefore, ethyl iodide (or propyl iodide, etc.) can be used as an X-ray indicator to add to CO2, so that X-ray CT can easily show the position of CO2, and the intensity of the rays projected onto the developing paper will also be different. By setting the appropriate exposure time of the high-definition camera, shooting the developing paper, and then processing the photos, a high-resolution distribution map of CO2 in the rock can be obtained.

[0044] Calculation method:

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

[0046]

[0047] In the formula, K is the absorption rate of the material, 1 is the thickness of the material, and C is the concentration of the absorbing material. I0 is the initial light intensity, I t is the intensity of light after passing through a substance. For a point, the logarithm of the ratio of the light intensity after attenuation to the light intensity before attenuation of the same substance is taken, and the result is linearly related to the thickness of the substance.

[0048] After CO2 invades the model, the scanning results are compared with the initial picture. The relationship between the total brightness change and the total material increase relative to the initial picture can be expressed as:

[0049]

[0050] Before CO2 breaks through to the core model outlet, the total amount of CO2 injected is equal to the increased CO2 content in the model. Divide the corresponding points of each image and then take the logarithm 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, which is equal to the amount of CO2 injected. In this way, the CO2 absorption coefficient K of the indicator with different degrees of extraction can be calibrated.

[0051] During the experiment, corresponding pictures were obtained at different stages of shooting. The light intensity at the same point in the pictures taken at different time points was divided and the logarithm was taken, and then divided by the calibrated absorption coefficient K. The concentration of CO2 absorbed at each pixel can be obtained, and the specific distribution of CO2 at different positions can be obtained.

[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: Make a sand-filled model and complete model assembly;

[0054] According to the physical parameters of the target reservoir and the reservoir characteristic parameters, a sand filling model is made, and a small plunger model is drilled to test its physical parameters such as permeability and porosity until it meets the requirements. Then the configured sand filling model 41 and the fixing frame 37 are placed in the rubber sleeve 36 in turn, and placed on the developing paper in the lower cover plate 34, and the upper cover plate 38 is covered. The fixing frame is fixed to the upper and lower cover plates with bolts, and then the upper and lower cover plates are fixed and sealed with bolts. The made model is fixed on the right end cover 32 of the clamp 8. The heating plate 27 is installed in the kettle body 31, and the line connection is checked to be normal, and the temperature monitoring and control are accurate and stable. Then, the right end cover 32 and the left end cover 33 are connected and fixed to the kettle body 31 by bolts, and the sealing is ensured by the rubber sealing ring 24. After the clamp is assembled, the CO2 displacement system, the X-ray scanning system, and the metering system are connected and assembled in turn.

[0055] Step 2: calibrate the absorption coefficient K of CO2 extracted with the indicator;

[0056] Inject CO2 into the vacuumed sand-filled model. After CO2 enters the model, compare the scanned image with the initial image. The relationship between the total brightness change and the total material increase relative to the initial image can be expressed as:

[0057]

[0058] Where K is the absorption rate of the material, 1 is the thickness of the material, and C is the concentration of the absorbing material. I0 is the initial light intensity, I t is the intensity of light after passing through a substance.

[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 logarithmic 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, which is equal to the injected CO2 amount. In this way, the absorption coefficient K of the CO2 extracting the indicator can be calibrated.

[0060] Step 3: Saturate the formation gas;

[0061] Open the intermediate container 15, and then inject nitrogen into the holder autoclave through the ISCO piston 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), then open the intermediate container 5, and inject formation gas into the sand-packed 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 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 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-packed model through the ISCO piston double pump 1. Record the injected CO2 gas volume V2, let the CO2 displace the formation natural gas, and the outlet flow meter measures the produced gas volume V3 at all times. At the same time, obtain the CO2 concentration and 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, and the X-rays pass through the sand-packed model and are projected onto the developing paper. Then, the high-definition camera sets a reasonable exposure time and takes 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 CO2 absorbed by each pixel point, and obtain the distribution and concentration of CO2 at different positions:

[0067]

[0068] Among them, K is the absorption rate of the substance, 1 is the thickness of the substance, C iis the concentration of the absorbing substance. 0i is the initial light intensity at point i on the developing paper, I ti is the light intensity at point i on the developing paper at time t when the gas is driven.

[0069] At the same time, the total recovery after gas flooding can be obtained as The CO2 storage capacity is

[0070] Although 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 the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present 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, metering system; A CO2 displacement system, comprising an ISCO plunger double pump, an intermediate container for holding CO2 carrying a developer, an intermediate container for holding simulated formation gas, a core model holder, a pressure gauge, a back pressure valve, a back pressure pump, a temperature monitor, an intermediate container for holding nitrogen, and an ISCO plunger confining pressure pump, wherein one end of the ISCO plunger double pump is respectively connected to an intermediate container for holding CO2 carrying a developer and an intermediate container for holding simulated formation gas, the other ends of the intermediate container for holding CO2 carrying a developer and the intermediate container for holding simulated formation gas are connected to the core model holder, the core model holder is also respectively connected to a pressure gauge, a temperature monitor and an intermediate container for holding nitrogen, the other end of the pressure gauge is connected to a back pressure valve, the back pressure valve is also connected to another set of pressure gauges, the other set of pressure gauges is connected to the back pressure pump, and the other end of the intermediate container for holding nitrogen is connected to the ISCO plunger confining pressure pump; X-ray scanning system, including X-ray scanning control computer, high-definition camera, X-CT scanner; Metering systems, including gas meters and gas chromatographs; The core model holder includes a kettle body, a right end cover and a left end cover, wherein the right end cover and the left end cover are connected to the kettle body through right end bolts and left end bolts respectively, and the sealing of the kettle body is ensured by rubber sealing rings. An X-ray source is placed in the left end cover, and the X-ray source is separated from the experimental cavity by a sapphire glass plate at the left end. A high-definition camera is placed in the right end cover, and is separated from the experimental cavity by a sapphire glass plate at the right end. A confining pressure channel is also provided in the right end cover, and is connected to an intermediate container containing nitrogen through a pipeline; A displacement inlet is provided on the inner side of the right end cover, and the displacement inlet is connected to the intermediate container containing CO2 and the intermediate container containing simulated formation gas through pipelines; a displacement outlet is also provided on the inner side of the right end cover, and the displacement outlet is connected to the back pressure valve through pipelines; a temperature monitoring and control channel is provided on the inner side of the right end cover, and the temperature monitoring and control channel is connected to the heating plate and the temperature monitor through wires; A core model is installed on the inner side of the right end cover through a bracket. The core model includes a lower cover plate, developing paper, a transparent rubber sleeve, a fixing frame, a sand filling model and an upper cover plate. The developing paper is fixed to the bottom of the lower cover plate, the sand filling model is placed in the middle of the transparent rubber sleeve, the front end of the fixing frame is wrapped with a transparent rubber 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, and the upper cover plate, the lower cover plate and the fixing frame are all provided with inlet channels and outlet channels.

2. A two-dimensional physical simulation experimental device for CO2 utilization and storage in gas reservoirs according to claim 1, characterized in that: The two ends of the intermediate container for containing CO2 carrying the developer and the intermediate container for containing the simulated formation gas are respectively connected with valves, valves, valves, and valves.

3. A two-dimensional physical simulation experimental device for CO2 utilization and storage in gas reservoirs according to claim 1, characterized in that: A valve is provided 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, comprising the experimental device according to claims 1-3, characterized in that: The experimental setup includes the following steps: Step 1: Make a sand filling model and complete the model assembly. According to the physical parameters of the target oil reservoir and the reservoir characteristic parameters, make a sand filling model, and drill a small plunger model to test its permeability, porosity and other physical parameters until it meets the requirements; Step 2: Calibrate the absorption coefficient K of the CO2 extracted with the indicator. Inject CO2 into the sand-packed model after evacuation. After the 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 absorption rate of the material, 1 is the thickness of the material, and C is the concentration of the absorbing material. I0 is the initial light intensity, I t is the intensity of light after passing through a substance. 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 ∑(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 the CO2 extracted with the indicator can be calibrated; Step 3: Saturate the formation gas. Open the intermediate container 15, and then inject nitrogen into the holder autoclave through the ISCO piston 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), then open the intermediate container 5, and inject formation gas into the sand-packed model through the ISCO piston double pump. When the internal pressure of the model stabilizes at the pressure P0, stop the injection and record the injected formation gas volume V0 to complete the saturation of the formation gas; Step 4: exhaustion exploitation: reduce the pressure of the back pressure pump 13 at a reasonable gradient rate to allow the natural gas inside the sand filling model to exhaust slowly. At the same time, the gas volume V1 is recorded by the gas meter 12, and the components of the produced natural gas are measured by the gas chromatograph 42. At this time, the recovery rate of exhaustion exploitation is Step 5: Inject CO2 to displace gas to improve oil recovery. Turn on the X-ray scanning system through the ISCO piston double pump 1, and inject CO2 into the sand-packed model. Record the injected CO2 gas volume V2. Let the CO2 displace the formation natural gas. The outlet flowmeter measures the produced gas volume V3 at all times. At the same time, obtain the CO2 concentration and 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 to 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 oil recovery and storage.

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