A CO2 plume transport simulation and monitoring device and method based on fiber Bragg grating

Abstract

The application provides a CO2 plume migration simulation monitoring device and method based on a fiber grating, which comprises a core holder, a fluid control system, a fiber pressure sensing system and a confining pressure-temperature control system; the core holder is internally provided with a core, and fluid inlet / outlet pipelines are connected to the two sides of the core and connected with the fluid control system; a confining pressure cavity is formed between the outer metal cylinder of the core and a rubber sleeve (106), the confining pressure-temperature control system provides different temperature and pressure conditions for the confining pressure cavity, the fiber pressure sensing system can measure the fluid pressure change in the two-phase flow process, the application can realize the test under different temperature and pressure conditions, simulate the two-phase flow process of the saturated rock after CO2 injection under different fluid pressure, temperature and confining pressure conditions, thereby monitoring the plume distribution of CO2 in the saturated rock, tracking the change of the CO2 plume front and monitoring the migration process of CO2 in the saturated rock.

Description

Technical Field

[0001] This invention relates to the field of aquifer CO2 plume transport and fiber optic pressure measurement technology, and particularly to a CO2 plume transport simulation and monitoring device and method based on fiber Bragg gratings. Background Technology

[0002] With the increasing severity of environmental problems, reducing atmospheric CO2 levels and developing clean energy are among the urgent issues that need to be addressed to achieve dual carbon goals. CO2 plume geothermal energy has emerged as a new energy utilization method. CO2 plume geothermal systems utilize natural porous media, injecting low-temperature CO2 into deep geothermal reservoirs through injection wells. The injected CO2 permeates and migrates within the reservoir pores, displacing water and exchanging heat with the high-temperature rock mass. Due to buoyancy caused by density differences, CO2 forms a forward-upward plume distribution in space. The heated CO2 is transported to the surface through production wells for heating or power generation, and then the cooled CO2 is reinjected underground. The amount of CO2 lost within the formation is the geological sequestration. CO2 plume geothermal energy combines CO2 geological sequestration and geothermal production processes, reducing CO2 sequestration costs and generating clean energy.

[0003] After CO2 enters the underground reservoir from the production well, its flow within the reservoir determines the CO2 sequestration efficiency and the heat extraction capacity of the production well. Therefore, monitoring the migration and distribution of CO2 in the reservoir is crucial for CO2 geological sequestration and heat extraction power generation from the production well. Currently, there are very few methods for monitoring CO2 plumes in reservoirs. Conventional experimental monitoring methods use nuclear magnetic resonance (NMR) spectrometers to distinguish the response amplitudes of different fluids; however, such equipment is expensive and cannot be used for practical field monitoring. Due to the different properties of CO2 and water, the fluid pressure changes after CO2 is injected into the aquifer. Fiber gratings (FGRs) can sense pressure changes through wavelength variations and can be deployed on both experimental and field scales, by selecting FGRs with different sensitivities. Therefore, a CO2 plume migration simulation monitoring device and method based on fiber gratings is still lacking to detect the migration and distribution of CO2 after injection into the reservoir. Summary of the Invention

[0004] To address the aforementioned problems of existing technologies, this invention provides a CO2 plume transport simulation and monitoring device and method based on fiber Bragg gratings, solving the problem that existing technologies cannot meet the requirements for indoor and field CO2 injection into water-bearing rocks for transport research and monitoring. To achieve the above objective, embodiments of this invention provide a CO2 plume transport simulation and monitoring device based on fiber Bragg gratings, comprising: a core holder, a fluid control system, a fiber optic pressure sensing system, a confining pressure-temperature control system, and a computational controller electrically connected to the core holder, fluid control system, fiber optic pressure sensing system, and confining pressure-temperature control system. The core holder contains a core, with a left plug and a right plug at each end. A left conical ring and a right conical ring are fitted over the exterior of each plug, respectively. A rubber sleeve is fitted over the front end of each conical ring, tightly sealing and wrapping the core, the left plug, and the right plug. The exterior of the rubber sleeve is a metal cylinder, forming a confining pressure cavity between the metal cylinder and the rubber sleeve. The two ends of the metal cylinder are tightly pressed against the left and right conical rings using sealing rings to maintain the seal of the confining pressure cavity. A fluid inlet pipe is located in the middle of the left plug, and a fluid outlet pipe is located in the middle of the right plug. The fluid control system includes a fluid injection control component connected to the fluid inlet pipe and a fluid detection component connected to the fluid outlet pipe. The fiber optic pressure sensing system includes a fiber optic grating and a wavelength signal processor. The fiber optic grating is laid inside the core and bundled in the right end cap, passing through a small hole and connected to the wavelength signal processor. The confining pressure-temperature control system is connected to the confining pressure chamber.

[0005] Furthermore, the fluid injection control component is equipped with a CO2 cylinder at its inlet end. The CO2 cylinder is connected to a cooling tower via valve a. The cooling tower is connected to a constant speed and pressure pump A via valve b. A valve c is provided on the connecting pipe between the cooling tower and the fluid inlet pipe. The valve c controls the injection of CO2. The fluid injection control component also includes a constant speed and pressure pump B. One end of the constant speed and pressure pump B is connected to a water source, and the other end is connected to the fluid inlet pipe via valve d.

[0006] Furthermore, the fluid detection assembly includes a back pressure control valve, a silicone drying tube, and a gas flow meter connected in sequence from the outlet end of the fluid outflow pipe. Below the silicone drying tube is an electronic mass meter that records changes in mass. Both the electronic mass meter and the gas flow meter are connected to a computing controller.

[0007] Furthermore, pressure gauges P4 and P5 are respectively installed on the fluid inlet pipe and fluid outlet pipe of the core holder, and the monitoring data can be transmitted to the computing controller.

[0008] Furthermore, four fiber optic gratings extend from the right end cap and are arranged at equal intervals from top to bottom along the center of the core. The core is drilled with holes of 2 mm in diameter, with each hole having a diameter of 2 mm.

[0009] Furthermore, the confining pressure-temperature control system includes a pressure pump, valve e, and a constant temperature chamber. The pressure pump injects water into the confining pressure chamber through valve e to control the confining pressure. A pressure gauge P3 is installed on the pipeline at valve e.

[0010] Furthermore, the left and right conical rings have grooves on their outer sides, and a rubber ring is fitted on the grooves, so that the left and right conical rings, the rubber ring, and the metal cylinder fit together tightly.

[0011] A method for simulating and monitoring CO2 plume transport based on fiber Bragg gratings includes the following steps: a. Core sample preparation: Select a complete rock and process it into a cylindrical sample that matches the size of the rock core inside the holder. Then, drill a hole in the sample with a diameter of 2 mm to match the fiber grating arranged on the right end. The sample radius is R and the length is L. b. Loading and sealing of the sample: The left and right conical rings, along with the rubber sleeve, are pre-inserted into the metal cylinder. After inserting the fiber grating on the right end into the sample bore, they are placed together into the rubber sleeve from the right end of the holder. The clustering holes on the right end and the right nut are kept directly above the holder, with the scale aligned with the metal cylinder, so that the fiber gratings are arranged from top to bottom. The left end is inserted into the left end of the holder, and the left and right nuts are fixed to the metal cylinder with bolts. The end is then pressed tightly to seal the sample. c. Test confining pressure loading: Open valve e and use a pressure pump to inject water into the confining pressure chamber. When the pressure gauge P3 displays the set value, close valve e. The confining pressure loading range is 0-50MPa. d. Test temperature loading: The interior of the chamber is heated using a constant temperature chamber with a temperature loading range of 20-150℃. To ensure that the fluid is heated to the set temperature during the injection process, the pipeline is folded to extend the heating time. A temperature gauge T is installed at the end of the folded pipeline to observe the temperature maintenance of the entire chamber. e. Acquisition of fluid loading and permeation data: f. Acquisition of fiber Bragg grating data.

[0012] In step e, First, set the back pressure control valve value to 8 MPa to simulate the supercritical state of the CO2 plume in the formation, ensuring an initial fluid pressure of 8 MPa. Open valve d and inject water (saline water) at a constant flow or pressure using constant-speed, constant-pressure pump B. This serves two purposes: first, to saturate the sample, and second, to record the flow rate Q and pressure difference ΔP when the flow stabilizes. The flow rate Q is recorded using constant-speed, constant-pressure pump B, and the pressure difference ΔP is obtained from the difference between pressure gauges P4 and P5, used to calculate the rock permeability. Close valve d and open valve a to compress the CO2 in the CO2 cylinder into the cooling tower. When pressure gauge P2 displays 8 MPa, close valve a and open... Open valve b to start the constant-speed, constant-pressure pump A, filling the pipeline from pump A to the cooling tower with water at a constant pressure of 8 MPa. Then, set pump A to inject at a constant flow rate to drive the CO2 in the cooling tower. Simultaneously, open valve c to allow the CO2 in the cooling tower to be injected into the clamp at a constant flow rate. The mass change of the silica gel drying tube and the monitoring data from the gas flow meter are transmitted to the computing controller in real time to record the instantaneous flow rate value of each phase in the two-phase flow. The real-time water phase flow rate value monitored by the silica gel drying tube is Q1, and the real-time gas phase flow rate value monitored by the gas flow meter is Q2, thereby calculating the effective permeability and relative permeability of each phase. rock permeability k The calculation formula is as follows:

[0013] Relative permeability of each phase k r Calculation formula:

[0014] in, ke For each corresponding effective permeability, the flow rate value Q1 or Q2 of each phase is substituted into equation (1) to calculate the effective permeability.

[0015] In step f, when the saturated rock is still under hydrostatic pressure, i.e. before CO2 is injected, the wavelength signal processor records the initial pressure value through the wavelength signal transmitted by the fiber Bragg grating. After CO2 injection, due to the difference in density and viscosity between CO2 and water, the CO2 plume extends forward from the top of the core under the action of driving force and buoyancy. At this time, the wavelength data of each point on the four fiber Bragg gratings will change, reflecting the change in fluid pressure. The fluid pressure decreases gradually from the fluid entering the pipe to the fluid flowing out of the pipe. However, due to the difference in properties between CO2 and water, the fluid pressure contour lines in the core are not regular. At the same cross section of the core, the pressure of the fiber Bragg gratings at the upper part of the core cross section is lower, and the pressure of the fiber Bragg gratings at the lower part of the core cross section is higher. Connecting the points with the same pressure on the four fibers, where the experimental scale does not consider the gravity gradient, displays the real-time pressure contour image on the computing controller to determine the transport and distribution of CO2 in the core.

[0016] The above-described solution of the present invention has the following beneficial effects: This invention includes a core holder, a fluid control system, a fiber optic pressure sensing system, and a confining pressure-temperature control system. The fluid control system allows for constant pressure or constant flow injection of fluid, meeting various research requirements beyond just CO2 and water two-phase flow modes. It can also be used to study CO2 displacement of methane and gas-driven oil. The fluid control system features a backpressure control valve at the core holder outlet to control the initial fluid pressure of the rock, simulating formation fluid pressure conditions. A silica gel drying tube and a gas flow meter record the gas and liquid phases of the fluid, converting the data into real-time flow rates for measuring the effective and absolute permeability of each phase in the two-phase flow. The confining pressure-temperature control system of this device can apply confining pressure and temperature. The injection pipeline in the constant temperature chamber is folded, and there is a temperature gauge T at the end of the folded pipeline to ensure that the temperature of the injected fluid and the temperature of the clamp reach the set value. This fiber optic pressure sensing system inserts a fiber optic grating into the core. The borehole diameter in the core matches the grating diameter, ensuring a tight fit between the grating and the core. A cable bundle is integrated into the right end cap, passing through a small hole in the end cap to transmit signals to a wavelength signal processor. The grating is highly sensitive to pressure changes, meeting the accuracy requirements of indoor experiments. The monitored pressure changes effectively reflect the migration and distribution of CO2 plumes in water-bearing sandstone. Furthermore, in actual reservoirs, by directional drilling between the injection and production wells, the gratings can be deployed to monitor CO2 in the CO2 plume geothermal system. The monitoring accuracy depends on the sensitivity of the gratings, while the monitoring range depends on the number and arrangement of the gratings. This device only arranges four gratings in the middle of the core, primarily observing the migration pattern of CO2 after injection along the axial central section. The number and arrangement of gratings can be increased as needed.

[0017] This device can measure the effective permeability and relative permeability of gas-liquid two-phase flow in rocks, monitor the migration patterns of CO2 injected into water-bearing rocks, and quantitatively analyze the CO2 migration patterns under different temperatures, confining pressures, and initial fluid pressures. Applying fiber optic gratings to geothermal development, a method and device based on fiber optic gratings for monitoring CO2 plume migration and distribution in deep geothermal reservoirs are proposed. This research can provide a basis for evaluating CO2 migration and sequestration in CO2 plume geothermal systems, and is of great significance for realizing the efficient utilization of CO2 as a heat transfer medium and achieving the early commercial exploitation of CO2 plume geothermal systems. Attached Figure Description

[0018] Figure 1 is a schematic diagram of the CO2 plume transport simulation and monitoring device based on fiber Bragg grating of the present invention; Figure 2 is a schematic diagram of the right plug structure of the CO2 plume transport simulation and monitoring device based on fiber Bragg grating of the present invention; Figure 3 is a schematic diagram of the core borehole of the CO2 plume transport simulation and monitoring device based on fiber optic grating of the present invention.

[0019] Figure 4 shows the fiber Bragg grating pressure sensing range of the CO2 plume transport simulation monitoring device based on fiber Bragg grating of the present invention, which is 0-50 MPa.

[0020] [Explanation of Labels in the Attached Image] 101-Core; 102-Left plug; 103-Right plug; 104-Left conical ring; 105-Right conical ring; 106-Rubber sleeve; 107-Metal cylinder; 108-Left nut; 109-Right nut; 201-CO2 cylinder; 202-Valve a; 203-Cooling tower; 204-Constant speed and pressure pump A; 205-Valve b; 206-Constant speed and pressure pump B; 207-Valve d; 208-Valve c; 209-Back pressure control valve; 210-Silicone drying tube; 211-Gas flow meter; 301-Fiber grating; 302-Wavelength signal processor; 401-Pressure pump; 402-Valve e; 403-Thermostatic chamber; 501-Computational controller. Detailed Implementation

[0021] To make the functions and advantages achieved by the present invention clearer, specific embodiments will be described in detail below.

[0022] This invention addresses the lack of devices for simulating and monitoring CO2 plume transport in existing CO2 plume geothermal systems, and the fact that existing experimental devices are too expensive and cannot be applied to actual sites. It provides a CO2 plume transport simulation and monitoring device based on fiber Bragg gratings.

[0023] like Picture 1As shown, an embodiment of the present invention provides a CO2 plume transport simulation and monitoring device based on fiber Bragg gratings, comprising: a core holder, a fluid control system, a fiber optic pressure sensing system, a confining pressure-temperature control system, and a computing controller 501 electrically connected to the core holder, the fluid control system, the fiber optic pressure sensing system, and the confining pressure-temperature control system; a core 101 is placed inside the core holder, with a left plug 102 and a right plug 103 at both ends of the core 101, respectively. The left plug 102 and the right plug 103 are in close contact with the core, and the left plug 102 and the right plug 103 are externally... A left conical ring 104 and a right conical ring 105 are fitted together. The outer side of each conical ring has a groove with a rubber ring attached. A rubber sleeve 106 is fitted onto the front end of the left and right conical rings 104 and 105. The rubber sleeve 106 is used to wrap the core used in the experiment, tightly fitting and wrapping the core 101, the left plug 102, and the right plug 103. Outside the rubber sleeve 106 is a metal cylinder 107, forming a confining cavity between the metal cylinder 107 and the rubber sleeve 106. The ends of the metal cylinder 107 and the left and right conical rings 104 and 105 are tightly pressed together by the rubber rings to maintain the seal of the confining cavity. A left nut 108 and a right nut 109 are provided on the outside of the left plug 102 and right plug 103. The left nut 108 and right nut 109 are fixed to the metal cylinder 107 with bolts, ensuring the core remains sealed by the tight pressure of the plugs.

[0024] The left plug 102 and the right plug 103 are respectively provided with a fluid inlet pipe and a fluid outlet pipe to connect the core to the outside world; the fluid control system includes a fluid injection control component connected to the fluid inlet pipe and a fluid detection component connected to the fluid outlet pipe.

[0025] The fluid injection control component includes a CO2 cylinder 201, which is connected to a cooling tower 203 via valve a202. The cooling tower 203 is connected to a constant speed and pressure pump A204 via valve b205. A valve c208 is provided on the connecting pipe between the cooling tower 203 and the fluid inlet pipe. The valve c208 controls the injection of CO2. The fluid injection control component also includes a constant speed and pressure pump B206, one end of which is connected to a water source, and the other end is connected to the fluid inlet pipe via valve d207.

[0026] The fluid detection assembly includes a back pressure control valve 209, a silica gel drying tube 210, and a gas flow meter 211 connected sequentially from the outlet end of the fluid outflow pipe. Below the silica gel drying tube 210 is an electronic mass meter that records changes in mass. Both the electronic mass meter and the gas flow meter 211 are connected to a computing controller 501. Real-time data measured by the silica gel drying tube 210 and the gas flow meter 211 can be uploaded to the computing controller 501 for storage. The fiber optic pressure sensing system includes a fiber optic grating 301 and a wavelength signal processor 302. The fiber optic grating 301 is laid inside the core 101 and bundled within the right plug 103, exiting through a small hole and connecting to the wavelength signal processor 302. The processed data is displayed on the computing controller 501.

[0027] The confining pressure-temperature control system includes a pressure pump 401, a valve e402, and a constant temperature chamber 403. The pressure pump 401 injects water into the confining pressure chamber through the valve e402 to control the confining pressure, and the constant temperature chamber 403 controls the temperature of the fluid and the temperature of the core.

[0028] Among them, there are four fiber optic gratings 301 extending from the right end cap 103, arranged at equal intervals from top to bottom along the center of the core 101. The core 101 is drilled with holes of 2mm in diameter, so that the fiber optic grating and the core borehole fit tightly together, ensuring the monitoring sensitivity of the fiber optic grating.

[0029] The CO2 cylinder 201, cooling tower 203, constant speed and constant pressure pump A204, and constant speed and constant pressure pump B206 are connected by pipelines. A valve a202 is provided between the CO2 cylinder 201 and the cooling tower 203, and a valve b205 is provided between the cooling tower and the constant speed and constant pressure pump A204. Valves c208 and d207 control the injection of CO2 and water, respectively.

[0030] The CO2 in CO2 cylinder 201 is first cooled and compressed into cooling tower 203. Cooling tower 203 is equipped with a pressure gauge P2 to display the gas pressure inside the cooling tower. Cooling tower 203 has a capacity of 1L.

[0031] The left conical ring 104 and the right conical ring 105 have grooves on their outer sides, and a rubber ring is fitted on the grooves. The conical ring, the rubber ring and the metal cylinder 107 fit tightly together, forming a sealed space with the rubber sleeve to ensure the sealing of the confining cavity.

[0032] The constant temperature chamber 403 heats the fluid and the core and maintains the set temperature. The temperature gauge T is placed at the end of the inlet folded pipe to ensure that the injected fluid reaches the set temperature before entering the core.

[0033] The pressure pump 401 injects water into the confining pressure chamber at constant pressure, and the confining pressure value is observed through the pressure gauge P3 to ensure that the confining pressure is normal.

[0034] In the core 101, four small holes with a diameter of 2 mm are drilled along the diameter. The holes correspond one-to-one with the fiber optic gratings 301 arranged in the right plug (103) to ensure that the fiber optic gratings 301 and the holes are tightly fitted. The fiber optic gratings 301 are bundled in the right plug 103 and pass through the small holes to connect with the wavelength signal processor 302 to process the wavelength data and convert it into the corresponding pressure.

[0035] The core holder is equipped with pressure gauges P4 and P5 at both ends of the inlet and outlet, and can transmit monitoring data to the computing controller 501. The back pressure control valve 209 is located at the outlet of the core holder to adjust the core hydrostatic pressure, i.e. the initial fluid pressure. The outlet fluid passes through the silica gel drying tube 210 and the gas flow meter 211 to measure the real-time flow data of water and CO2, respectively, in order to calculate the effective permeability and relative permeability of each phase.

[0036] A method for simulating and monitoring CO2 plume transport based on fiber Bragg gratings, the specific operation process of which is as follows: 1. Core sample preparation: Select a complete rock and process it into a cylindrical sample that matches the size of the core 101 in the holder. Then, drill a hole in the sample with a diameter of 2 mm to match the fiber optic grating 301 arranged on the right plug 103. The sample radius is R and the length is L.

[0037] 2. Loading and sealing of the sample: The left conical ring 104, the right conical ring 105, and the rubber sleeve 106 are pre-inserted into the metal cylinder 107. After inserting the fiber optic grating 301 on the right plug 103 into the drilled hole of the sample, they are put into the rubber sleeve 106 from the right end of the holder. The clustering holes on the right plug and the right nut are kept directly above the holder and the scale is aligned with the metal cylinder so that the fiber optic grating is arranged from top to bottom. The left plug 102 is inserted into the left end of the holder, and the left nut 108 and the right nut 109 are fixed to the metal cylinder 107 by bolts. The plug is pressed tightly to seal the sample.

[0038] 3. Test confining pressure loading: Open valve e402 and use pressure pump 401 to inject water into the confining pressure chamber. When the confining pressure gauge P3 displays the set value, close valve e. The confining pressure loading range is 0-50MPa.

[0039] 4. Test temperature loading: The inside of the chamber is heated using a constant temperature chamber 403, with a temperature loading range of 20-150℃. To ensure that the fluid is heated to the set temperature during the injection process, the pipeline is folded to extend the heating time. A thermometer T is installed at the end of the folded pipeline to observe the temperature maintenance of the entire chamber.

[0040] 5. Fluid Loading and Permeation Data Acquisition: First, set the back pressure control valve value. To simulate the supercritical state of the CO2 plume in the formation, it is set to 8 MPa to ensure an initial fluid pressure of 8 MPa. Open valve d207 and inject saline water through constant-speed, constant-pressure pump B206 at a constant flow or pressure. This is to saturate the sample and record the flow rate Q and pressure difference ΔP when the flow stabilizes. The flow rate Q is recorded by constant-speed, constant-pressure pump B206, and the pressure difference ΔP is obtained from the difference between P4 and P5 to calculate the rock permeability. Close valve d207 and open valve a202 to compress the CO2 in CO2 cylinder 201 into cooling tower 203. When pressure gauge P2 shows 8 MPa, close valve a202 and open... Valve b05 is used to open the constant speed and pressure pump A204, filling the pipeline from the constant speed and pressure pump A (204) to the cooling tower 203 with water at a constant pressure of 8MPa. Then, the constant speed and pressure pump A204 is set to inject at a constant flow to drive the CO2 in the cooling tower 203. At the same time, valve c208 is opened so that the CO2 in the cooling tower can be injected into the clamp at a constant flow. The mass change of the silica gel drying tube 210 and the monitoring data of the gas flow meter 211 are transmitted to the computer 501 in real time to record the instantaneous flow value of each phase in the two-phase flow. The real-time water phase flow value monitored by the silica gel drying tube 210 is Q1, and the real-time gas phase flow value monitored by the gas flow meter 211 is Q2, thereby calculating the effective permeability and relative permeability of each phase. rock permeability k The calculation formula is as follows:

[0041] Relative permeability of each phase k r Calculation formula:

[0042] in, ke For each corresponding effective permeability, the flow rate value Q1 or Q2 of each phase is substituted into equation (1) to obtain the effective permeability.

[0043] 6. Acquisition of Fiber Bragg Grating Data: When the saturated rock is still under hydrostatic pressure (i.e., before CO2 injection), the wavelength signal processor 302 records the initial pressure value through the wavelength signal transmitted by the fiber Bragg grating 301. After CO2 injection, due to the difference in density and viscosity between CO2 and water, the CO2 plume extends forward from the upper part of the core under the action of driving force and buoyancy. At this time, the wavelength data of each point on the four fiber Bragg gratings will change, reflecting the change in fluid pressure. The fluid pressure decreases gradually from the inlet to the outlet. However, due to the difference in properties between CO2 and water, the fluid pressure contour lines in the core are not regular. At the same cross section of the core, the pressure of the fiber Bragg grating at the upper part of the core cross section is lower, and the pressure of the fiber Bragg grating at the lower part of the core cross section is higher. Connecting the points with the same pressure on the four fibers (the experimental scale does not consider the gravity gradient) displays the real-time pressure contour image on the computer 501, thereby determining the migration and distribution of CO2 in the core.

[0044] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A CO2 plume transport simulation and monitoring device based on fiber Bragg gratings, characterized in that, include: A core holder, a fluid control system, a fiber optic pressure sensing system, a confining pressure-temperature control system, and a computing controller (501) electrically connected to the core holder, the fluid control system, the fiber optic pressure sensing system, and the confining pressure-temperature control system. The core holder contains a core (101). The core (101) has a left plug (102) and a right plug (103) at its two ends. A left conical ring (104) and a right conical ring (105) are fitted onto the outside of the left plug (102) and right plug (103), respectively. A rubber sleeve (106) is fitted onto the front end of the left conical ring (104) and right conical ring (105). The rubber sleeve (106) holds the core (101) and the left plug (102) in place. The right plug (103) is tightly wrapped around the outside of the rubber sleeve (106), which is a metal cylinder (107). A confining cavity is formed between the metal cylinder (107) and the rubber sleeve (106). The two ends of the metal cylinder (107) are tightly pressed with the left conical ring (104) and the right conical ring (105) by sealing rings to keep the confining cavity sealed. The left plug (102) has a fluid inlet pipe in the middle, and the right plug (103) has a fluid outlet pipe in the middle. The fluid control system includes a fluid injection control component connected to the fluid inlet pipe and a fluid detection component connected to the fluid outlet pipe. The fiber optic pressure sensing system includes a fiber optic grating (301) and a wavelength signal processor (302). The fiber optic grating (301) is laid inside the core (101) and bundled in the right plug (103) to pass through a small hole and connect to the wavelength signal processor (302). The confining pressure-temperature control system is connected to the confining pressure chamber; The fluid injection control component is equipped with a CO2 cylinder (201) at the inlet end. The CO2 cylinder (201) is connected to a cooling tower (203) through valve a (202). The cooling tower (203) is connected to a constant speed and constant pressure pump A (204) through valve b (205). A valve c (208) is provided on the connecting pipe between the cooling tower (203) and the fluid inlet pipe. The valve c (208) controls the injection of CO2. The fluid injection control component also includes a constant speed and constant pressure pump B (206). One end of the constant speed and constant pressure pump B (206) is connected to a water source, and the other end is connected to the fluid inlet pipe through valve d (207). The fiber grating (301) extends from the right end cap (103), and there are a total of 4 fiber gratings, which are arranged at equal intervals from top to bottom along the center of the core (101).

2. The CO2 plume transport simulation and monitoring device based on fiber Bragg grating according to claim 1, characterized in that, The fluid detection assembly includes a back pressure control valve (209), a silica gel drying tube (210), and a gas flow meter (211) connected in sequence from the outlet end of the fluid outflow pipe. The silica gel drying tube (210) has an electronic mass meter for recording changes in mass. The electronic mass meter and the gas flow meter (211) are both connected to a computing controller (501).

3. The CO2 plume transport simulation and monitoring device based on fiber Bragg grating according to claim 2, characterized in that, Pressure gauges P4 and P5 are installed on the fluid inlet and fluid outlet pipes of the core holder, and the monitoring data can be transmitted to the computing controller (501).

4. The CO2 plume transport simulation and monitoring device based on fiber Bragg grating according to claim 1, characterized in that, The core (101) is drilled with holes of 2 mm in diameter, which are the diameter of the fiber optic grating (301).

5. The CO2 plume transport simulation and monitoring device based on fiber Bragg grating according to claim 1, characterized in that, The confining pressure-temperature control system includes a pressure pump (401), a valve e (402), and a constant temperature chamber (403). The pressure pump (401) injects water into the confining pressure chamber through the valve e (402) to control the confining pressure. A pressure gauge P3 is installed on the pipeline at the valve e (402).

6. The CO2 plume transport simulation and monitoring device based on fiber Bragg grating according to claim 1, characterized in that, The left conical ring (104) and the right conical ring (105) have grooves on their outer sides, and a rubber ring is fitted on the grooves. The left conical ring (104), the right conical ring (105), the rubber ring and the metal cylinder (107) fit together tightly.

7. A method for simulating and monitoring CO2 plume transport based on fiber Bragg gratings, characterized in that, The CO2 plume transport simulation and monitoring using the fiber Bragg grating-based CO2 plume transport simulation and monitoring device as described in claim 1 includes the following steps: a. Core sample preparation: Select a complete rock and process it into a cylindrical sample that matches the size of the rock core (101) in the holder. Then drill a hole in the sample with a diameter of 2 mm to match the fiber optic grating (301) arranged on the right plug (103). The sample radius is R and the length is L. b. Loading and sealing of the sample: The left conical ring (104) and the right conical ring (105) and the rubber sleeve (106) are pre-inserted into the metal cylinder (107). After inserting the fiber grating (301) on the right plug (103) into the sample bore, they are put into the rubber sleeve (106) from the right end of the holder. The clustering holes on the right plug and the right nut are kept directly above the holder and the scale is aligned with the metal cylinder so that the fiber grating is arranged from top to bottom. The left plug (102) is put into the left end of the holder, and the left nut (108) and the right nut (109) are fixed on the metal cylinder (107) by bolts. The plug is pressed tightly to seal the sample. c. Test confining pressure loading: Open valve e (402) and use pressure pump (401) to inject water into the confining pressure chamber. When pressure gauge P3 displays the set value, close valve e. The confining pressure loading range is 0-50MPa. d. Test temperature loading: The interior of the chamber is heated using a constant temperature chamber (403) with a temperature loading range of 20-150℃. In order to ensure that the fluid is heated to the set temperature during the injection process, the pipeline is folded to extend the heating time. A temperature gauge T is provided at the end of the folded pipeline to observe the temperature maintenance of the entire chamber. e. Acquisition of fluid loading and permeation data: f. Acquisition of fiber Bragg grating data.

8. The method for simulating and monitoring CO2 plume transport based on fiber Bragg gratings according to claim 7, characterized in that, In step e, First, set the back pressure control valve value. To simulate the supercritical state of the CO2 plume in the formation, it is set to 8MPa to ensure the initial fluid pressure is 8MPa. Open valve d (207) and inject saline water through constant speed and constant pressure pump B (206) for constant flow or constant pressure. This is to saturate the sample and record the flow rate Q and pressure difference ΔP when the flow stabilizes. The flow rate Q is recorded by constant speed and constant pressure pump B (206), and the pressure difference ΔP is obtained from the difference between pressure gauge P4 and pressure gauge P5 to calculate the permeability of the rock. Close valve d (207) and open valve a (202) to compress the CO2 in the CO2 cylinder (201) into the cooling tower (203). When pressure gauge P2 shows 8MPa, close valve a (202) and open valve b (205). A constant-speed, constant-pressure pump A (204) is started, and water is used to fill the pipeline from the constant-speed, constant-pressure pump A (204) to the cooling tower (203) at a constant pressure of 8 MPa. Then, the constant-speed, constant-pressure pump A (204) is set to inject at a constant flow to drive the CO2 in the cooling tower (203). At the same time, valve c (208) is opened so that the CO2 in the cooling tower can be injected into the holder at a constant flow. The mass change of the silica gel drying tube (210) and the monitoring data of the gas flow meter (211) are transmitted to the computing controller (501) in real time to record the instantaneous flow value of each phase in the two-phase flow. The real-time water phase flow value monitored by the silica gel drying tube (210) is Q1, and the real-time gas phase flow value monitored by the gas flow meter (211) is Q2, thereby calculating the effective permeability and relative permeability of each phase. Formula for calculating rock permeability k: （1） Relative permeability k of each phase r Calculation formula: （2） Where ke is the effective permeability of each corresponding phase, which is obtained by substituting the flow rate value Q1 or Q2 of each phase into equation (1).

9. The method for simulating and monitoring CO2 plume transport based on fiber Bragg gratings according to claim 7, characterized in that, In step f, when the saturated rock is still under hydrostatic pressure, i.e. before CO2 is injected, the wavelength signal processor (302) records the initial pressure value through the wavelength signal transmitted by the fiber optic grating (301). After CO2 is injected, due to the difference in density and viscosity between CO2 and water, the CO2 plume extends forward from the top of the core under the action of driving force and buoyancy. At this time, the wavelength data of each point on the four fiber optic gratings will change, reflecting the change in fluid pressure. The fluid pressure decreases in a gradient from the fluid entering the pipe to the fluid flowing out of the pipe. However, due to the difference in properties between CO2 and water, the fluid pressure contour lines in the core are not regular. At the same cross section of the core, the pressure of the fiber optic grating at the upper part of the core cross section is small, and the pressure of the fiber optic grating at the lower part of the core cross section is large. Connect the points with the same pressure on the four fibers. The experimental scale does not consider the gravity gradient. The real-time pressure contour image is displayed on the computing controller (501) to determine the movement and distribution of CO2 in the core.

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