Multi-parameter collaborative sensing device and method for process of injecting CO2 into coal seam

Abstract

The invention discloses a multi-parameter collaborative sensing device and method for a process of injecting CO2 into a coal seam, and relates to the technical field of carbon sequestration testing. The hydraulic loading module is arranged on the outer wall of the box body, and a confining pressure loading structure of the hydraulic loading module can apply pressure to the rock-soil body in the box body; a heat exchange structure of the temperature control module is arranged in the confining pressure loading structure; a high-pressure gas pipeline of the high-pressure gas control module is implanted into the rock-soil body; an injection medium output pipeline of the chemical fluid control module is arranged in the box body; a plurality of sensing optical fibers of the distributed optical fiber acquisition module are distributed in the box body; a plurality of electrodes of the multi-frequency electrical method acquisition module are distributed in the box body; an acoustic emission probe of the acoustic emission acquisition module is connected to the confining pressure loading structure; and the upper computer is used for cooperatively processing and analyzing the plurality of acquired parameters. The multi-source sensing technology is integrated, and multi-parameter collaborative intelligent sensing and multi-source data fusion processing can be achieved under the THMC coupling condition.

Description

Technical Field

[0001] This invention relates to the field of carbon sequestration testing technology, and in particular to a multi-parameter collaborative sensing device and method for CO2 injection into coal seams. Background Technology

[0002] Injecting CO2 into deep, unminable coal seams can achieve long-term geological sequestration of CO2 and simultaneously improve coalbed methane recovery (ECBM), making it one of the most promising methods for coalbed methane injection (CCUS). During CO2 injection, the coal and rock mass is in a high-temperature, high-pressure, and high-mineralization fluid environment. Strong coupling effects occur between the four fields of temperature (T), seepage (H), stress (M), and chemical (C), leading to complex physicochemical processes such as adsorption expansion, mineral dissolution, fracture propagation, and permeability evolution. These processes directly affect the accurate evaluation of coal reservoir compressibility, caprock sealing capacity, and CO2 migration and diffusion patterns.

[0003] Most existing rock mechanics testing devices can only achieve single physical field or dual-field (TH, HM, TM, etc.) coupling, making it difficult to simultaneously and accurately control and maintain a true THMC four-field coupling environment. In terms of monitoring methods, traditional strain gauges, resistivity methods, and conventional acoustic emission sensors have problems such as low spatial resolution, point measurement, inability to conduct distributed continuous monitoring, and difficulty in synchronously acquiring different physical quantities. They cannot perform spatiotemporal collaborative sensing and multi-source data fusion of the multi-field response of CO2 injection-induced strain-temperature-electricity-acoustic emission, resulting in a serious lack of understanding of the evolution of microscopic damage in coal and rock, solute transport mechanisms, and information on the precursors of fracture. This restricts the further development of technologies for evaluating the carbon storage potential of deep coal seams, assessing the safety of storage, and providing early warning of leaks.

[0004] Therefore, there is an urgent need to develop a device and method that can integrate multi-source sensing technology under real THMC coupling conditions to achieve multi-parameter collaborative intelligent sensing, real-time synchronous acquisition and multi-source data fusion processing, so as to fill the gap in existing technology and provide key support for the research and engineering application of CO2 geological storage mechanism. Summary of the Invention

[0005] In view of this, the present invention proposes a multi-parameter collaborative sensing device and method for CO2 injection into coal seams, aiming to solve at least one of the above-mentioned technical problems.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a multi-parameter collaborative sensing device for the CO2 injection process into coal seams, comprising: The box body is rectangular and its internal cavity is a pressure-bearing cavity capable of being filled with rock and soil. A hydraulic loading module is disposed on the outer wall of the box and its confining pressure loading structure is capable of applying pressure to the rock and soil mass located inside the box in the front-back, left-right and up-down directions. A temperature control module, wherein the heat exchange structure of the temperature control module is disposed inside the confining pressure loading structure, thereby controlling the temperature through heat exchange when the confining pressure loading structure presses against the outer wall of the rock and soil body; A high-pressure gas control module, wherein the high-pressure gas pipeline of the high-pressure gas control module extends into the housing and can be implanted into the rock and soil mass for CO2 injection; A chemical fluid control module, wherein the injection medium output pipe of the chemical fluid control module is disposed inside the housing, for adding injection medium into the rock and soil mass; A distributed optical fiber acquisition module, wherein multiple sensing optical fibers of the distributed optical fiber acquisition module are distributed in the internal space of the box, for acquiring the internal strain and / or temperature information of the rock and soil mass; A multi-frequency electrical resistivity tomography (EPT) acquisition module, wherein multiple electrodes of the multi-frequency EPT acquisition module are distributed in the internal space of the housing, for applying excitation current or voltage of different frequencies to the rock and soil mass; An acoustic emission acquisition module, wherein the acoustic emission probe of the acoustic emission acquisition module is connected to the confining pressure loading structure, and is used to receive the acoustic emission signals generated by the rock and soil mass during the deformation and failure process; The host computer is communicatively connected to the data output terminals of the hydraulic loading module, the temperature control module, the high-pressure gas control module, the chemical fluid control module, the distributed optical fiber acquisition module, the multi-frequency electrical resistivity acquisition module, and the acoustic emission acquisition module to collaboratively process and analyze the acquired parameters.

[0008] The multi-parameter collaborative sensing device for CO2 injection into coal seams of this invention can provide a multi-field coupled environment of water, heat, force, and chemistry in the soil and rock mass (e.g., coal seam). It provides distributed optical fiber, frequency domain electrical resistivity tomography, and acoustic emission synchronous testing for the CO2 injection process, and can monitor CO2 migration and diffusion, soil and rock compressibility, and caprock sealing capacity in real time. This invention enables multi-parameter collaborative intelligent sensing, real-time synchronous acquisition, and multi-source data fusion processing, providing crucial support for research on CO2 geological storage mechanisms and engineering applications.

[0009] As a further improvement to the above technical solution, the hydraulic loading module includes a hydraulic power unit, a confining pressure loading unit, a stress acquisition unit, a displacement feedback unit, and a loading control unit; The confining pressure loading unit comprises multiple sets, each set including a hydraulic cylinder and an end pressure head. The end pressure heads of the multiple sets of confining pressure loading units are evenly distributed on the top wall, bottom wall, and side walls of the housing, thereby enclosing and forming a confining pressure loading structure capable of applying pressure to the rock and soil mass in the front-back, left-right, and up-down directions. The hydraulic power unit is connected to the hydraulic cylinders of the multiple sets of confining pressure loading units to supply hydraulic oil. The hydraulic cylinders of the multiple sets of confining pressure loading units are all located on the outer wall of the housing, and their loading pistons are correspondingly connected to the multiple end pressure heads to provide pressurization driving force. The stress acquisition unit and the displacement feedback unit are spaced apart and located on the end face of the end pressure head away from the loading piston. The loading control unit is communicatively connected to the hydraulic power unit, the confining pressure loading unit, the stress acquisition unit, and the displacement feedback unit for pressurization control. The host computer is communicatively connected to the loading control unit.

[0010] As a further improvement to the above technical solution, the temperature control module includes a heating and cooling unit, a heat preservation unit, a temperature acquisition unit, and a temperature control unit; the heating and cooling unit includes a circulating liquid supply pipe and a circulating liquid supply mechanism disposed inside the end pressure head; the circulating liquid supply mechanism is connected to the circulating liquid supply pipe through a pipeline to circulate and transport circulating liquid; the heat preservation unit is disposed inside the end pressure head and located on the side of the circulating liquid supply pipe near the loading piston; the temperature acquisition unit includes multiple temperature sensing units; the inner wall of the chamber and the input and output ends of the circulating liquid supply pipe are all provided with the temperature sensing units; the temperature control unit is communicatively connected to the circulating liquid supply mechanism and the temperature sensing units for temperature control; the host computer is communicatively connected to the temperature control unit.

[0011] As a further improvement to the above technical solution, the high-pressure gas control module includes a CO2 supply unit, a pressure boosting and stabilizing unit, a flow regulation unit, a second stress acquisition unit, a second temperature acquisition unit, and a high-pressure gas control unit. The output of the CO2 supply unit is connected to the input of the pressure boosting and stabilizing unit; the output of the pressure boosting and stabilizing unit is the CO2 injection end; both the second stress acquisition unit and the second temperature acquisition unit are located at the output of the pressure boosting and stabilizing unit to acquire real-time stress and temperature signals during the injection process; the flow regulation unit is located on the pressure boosting and stabilizing unit to regulate the injection flow rate; the high-pressure gas control unit is communicatively connected to the CO2 supply unit, the pressure boosting and stabilizing unit, the flow regulation unit, the second stress acquisition unit, and the second temperature acquisition unit to receive stress and temperature signals and perform injection control; the host computer is communicatively connected to the high-pressure gas control unit.

[0012] As a further improvement to the above technical solution, the chemical fluid control module includes a solution preparation unit, a component metering and mixing unit, a storage unit, a dosing adjustment unit, a discharge and purification unit, and a chemical fluid control unit. The solution preparation unit is used to prepare a base solution with set ion concentration, pH, and mineralization. The component metering and mixing unit is connected to the solution preparation unit and can quantitatively add and mix acid / alkali, salt solutions, buffer solutions, and additives according to a preset ratio. The component metering and mixing unit is connected to the storage unit through a supply pipeline to supply the injection medium. The storage unit is used to maintain the constant volume storage and component stability of the injection medium. The storage unit is equipped with an online monitoring unit for acquiring real-time feedback signals of the chemical parameters of the injection medium. One end of the dosing adjustment unit is connected to the storage unit, and the other end is an injection medium output pipeline located inside the tank and capable of adding the injection medium into the rock and soil mass. The discharge and purification unit is located at the bottom of the tank and is used to discharge the reacted medium. The chemical fluid control unit is communicatively connected to the component metering and mixing unit, the online monitoring unit, and the dosing adjustment unit. The host computer is communicatively connected to the chemical fluid control unit.

[0013] As a further improvement to the above technical solution, the distributed optical fiber acquisition module includes a sensing optical fiber, an optical fiber fixing unit, an optical fiber lead-out sealing unit, and a demodulation unit. The sensing optical fibers are multiple and arranged inside the housing along the height direction of the housing; the multiple sensing optical fibers are spaced apart along the width and length directions of the housing; there are multiple optical fiber fixing units, which are spaced apart along the length direction of the sensing optical fibers and can couple the sensing optical fibers into the rock and soil mass; there are multiple sets of optical fiber lead-out sealing units, all of which are sealed and penetrate through the top wall of the housing; the lower ends of the multiple sets of optical fiber lead-out sealing units are connected to the upper ends of the multiple sensing optical fibers; the host computer is connected to the signal output terminal of the demodulation unit; the signal input terminal of the demodulation unit is connected to the upper ends of the multiple sets of optical fiber lead-out sealing units, and is used to demodulate the echo signal of the sensing optical fibers and output distributed strain and temperature data.

[0014] As a further improvement to the above technical solution, the multi-frequency electrical resistivity acquisition module includes multiple electrodes and an electrical resistivity instrument; the multiple electrodes are evenly distributed in layers in the rock and soil mass; the multiple electrodes are electrically connected to the electrical resistivity instrument through cable assemblies; and the host computer is communicatively connected to the electrical resistivity instrument.

[0015] As a further improvement to the above technical solution, the acoustic emission acquisition module includes an acoustic emission probe, a signal transmission line, and an acoustic emission acquisition instrument; there are multiple acoustic emission probes, which are closely attached to and evenly distributed on the sidewall of the confining pressure loading structure away from the soil and rock mass; the acoustic emission acquisition instrument is electrically connected to the multiple acoustic emission probes through the signal transmission line for parameter acquisition and storage; the host computer is communicatively connected to the acoustic emission acquisition instrument.

[0016] Another aspect of the present invention provides a multi-parameter collaborative sensing method for the CO2 injection coal seam process, which, using the aforementioned multi-parameter collaborative sensing device for the CO2 injection coal seam process, includes the following steps: S1: Pre-install sensing optical fibers and electrodes inside the housing 1, and arrange acoustic emission probes on the outer periphery of the confining pressure loading structure. S2: Based on the actual lithological distribution of the strata, a similar strata model is built in the pressure cavity to construct the rock and soil mass; S3: Activate the hydraulic loading module to ensure the loading pressure meets the test requirements; activate the temperature control module to heat or cool the chamber to the target temperature; activate the chemical fluid control module to inject the injection medium into the soil and rock mass, providing a water, heat, mechanical, and chemical environment for the soil and rock mass; S4: Enable the distributed fiber optic acquisition module, multi-frequency electrical resistivity acquisition module and acoustic emission acquisition module to perform real-time acquisition of multi-field data such as acoustic emission signals, temperature data and stress data; S5: Activate the high-pressure gas control module to pressurize and supply CO2 gas into the soil and rock mass, and collect multiple data in real time; S6: After the CO2 gas supply is completed, shut down the hydraulic loading module and remove the confining pressure; take photos of the soil and rock mass, and perform data processing and analysis.

[0017] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a multi-parameter collaborative sensing device and method for CO2 injection into coal seams, which has the following advantages and beneficial effects.

[0018] 1. This invention provides a device and method for synchronous, continuous, and coordinated acquisition of three types of sensing technologies—distributed optical fiber (OFDR), frequency domain electrical resistivity, and acoustic emission—under real THMC (temperature-permeation-stress-chemical) multi-field coupling conditions.

[0019] 2. This invention is the first to achieve accurate reproduction of the true four-field coupling environment and distributed collaborative sensing of multiple physical field parameters during the entire process of CO2 injection in deep coal seams. It breaks through the bottleneck of traditional rock mechanics test devices that can only carry out single-field or dual-field coupling, and the monitoring means are point-based and different physical quantities are difficult to synchronize. It fills the gap in multi-source sensing collaborative sensing technology under multi-field coupling conditions in THMC in China.

[0020] 3. This invention can obtain centimeter-level spatial resolution distributed strain-temperature field through OFDR, obtain spectrally resolved complex resistivity evolution through frequency domain electrical methods, and obtain amplitude-energy-location information of micro-damage events through acoustic emission. The three are acquired synchronously in time, which can capture key processes such as coal and rock adsorption expansion, mineral dissolution, fracture initiation and propagation, and permeability mutation induced by CO2 injection in real time, dynamically and intuitively. It provides high-precision and multi-dimensional data support for coal reservoir compressibility evaluation, caprock sealability assessment, and CO2 migration and diffusion law research.

[0021] 4. This invention can be equipped with a multi-source data fusion processing method (multi-scale comparison, four-field joint response curve, parameter correlation analysis, fracture precursor prediction, dynamic digital core construction) to organically link microscopic fracture evolution with macroscopic mechanical-electrical-acoustic response, realize quantitative characterization of damage evolution mechanism and early warning of CO2 leakage risk, and significantly improve the scientificity and reliability of carbon storage potential evaluation and storage safety assessment of deep unminable coal seams.

[0022] 5. The device of this invention has a compact structure, high control precision, and clear operation process. It has good engineering applicability and scalability, and can directly serve multidisciplinary research such as CCUS major projects, coalbed methane production enhancement, and deep rock mechanics. It provides key experimental means and theoretical support for the large-scale application of CO2 geological storage technology under my country's "dual carbon" target, and has significant scientific value and broad engineering application prospects. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the overall structure of the multi-parameter collaborative sensing device for the CO2 injection coal seam process of the present invention.

[0025] Figure 2 This is a schematic diagram of the hydraulic loading module structure of the multi-parameter collaborative sensing device for CO2 injection into coal seams according to the present invention.

[0026] Figure 3 This is a schematic diagram of the internal structure of the end pressure head of the multi-parameter collaborative sensing device for CO2 injection into the coal seam process of the present invention.

[0027] Figure 4 This is a schematic diagram of the distributed optical fiber acquisition module of the multi-parameter collaborative sensing device for CO2 injection into coal seams according to the present invention.

[0028] Figure 5 This is a schematic diagram of the multi-frequency electrical resistivity tomography (EDT) acquisition module of the multi-parameter collaborative sensing device for CO2 injection into coal seams according to the present invention.

[0029] Figure 6 This is a schematic diagram of the acoustic emission acquisition module of the multi-parameter collaborative sensing device for CO2 injection into coal seams according to the present invention.

[0030] In the diagram: 1. Housing; 2. Hydraulic power unit; 201. Oil tank; 202. Hydraulic pump; 203. Piping assembly; 204. Overflow valve; 3. Confining pressure loading unit; 31. Hydraulic cylinder; 311. Loading piston; 32. End pressure head; 4. Stress acquisition unit one; 5. Displacement feedback unit; 6. Heating and cooling unit; 61. Circulating liquid supply pipeline; 611. Circulating liquid; 7. Insulation unit; 8. Temperature acquisition unit one; 81. Temperature sensing unit; 9. CO2 supply unit; 10. Pressure boosting and stabilizing unit; 101. Booster pump; 102. Pressure stabilizing container; 103. High-pressure gas pipeline; 11. Flow regulation unit; 12. Stress acquisition unit two; 13. Temperature acquisition unit two; 14. Solution preparation unit; 15. Component metering and mixing unit; 15 1. Metering pump; 152. Pipeline valve assembly; 153. Mixing container; 16. Storage unit; 161. Online monitoring unit; 1611. pH sensor; 1612. Conductivity sensor; 17. Dosing and adjustment unit; 171. Corrosion-resistant pipe; 172. High-pressure nozzle; 173. Injected medium output pipe; 18. Discharge and purification unit; 19. Sensing fiber optic cable; 20. Fiber optic cable fixing unit; 21. Fiber optic cable lead-out sealing unit; 211. Test fiber optic cable jumper; 212. Communication base; 213. Fiber optic cable lead-out jumper; 22. Demodulation unit; 23. Electrode; 24. Cable assembly; 241. Cable; 242. Aviation connector; 25. Electrophysiology instrument; 26. Acoustic emission probe; 27. Signal transmission line; 28. Acoustic emission acquisition instrument; 29. ​​Host computer. Detailed Implementation

[0031] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0032] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0033] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0034] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0035] According to embodiments of the present invention, such as Figures 1 to 6 As shown, the multi-parameter collaborative sensing device for CO2 injection into coal seams includes: a housing 1, a hydraulic loading module, a temperature control module, a high-pressure gas control module, a chemical fluid control module, a distributed optical fiber acquisition module, a multi-frequency electrical resistivity acquisition module, an acoustic emission acquisition module, and a host computer 29.

[0036] Box 1 is rectangular and its inner cavity is a pressure-bearing cavity that can be filled with rock and soil.

[0037] The hydraulic loading module is installed on the outer wall of the box 1, and its confining pressure loading structure can apply pressure to the rock and soil inside the box 1 in the front-back, left-right and up-down directions.

[0038] The heat exchange structure of the temperature control module is set inside the confining pressure loading structure, so as to exchange heat and control the temperature when the confining pressure loading structure presses against the outer wall of the rock and soil.

[0039] The high-pressure gas pipeline of the high-pressure gas control module extends into the housing 1 and can be implanted into the soil and rock mass for CO2 injection.

[0040] The injection medium output pipeline of the chemical fluid control module is located inside the housing 1 and is used to inject the injection medium into the rock and soil.

[0041] Multiple sensing optical fibers of the distributed optical fiber acquisition module are distributed in the internal space of the housing 1 to acquire internal strain and / or temperature information of the rock and soil mass.

[0042] Multiple electrodes of the multi-frequency electrical resistivity acquisition module are distributed in the internal space of the housing 1 to apply excitation current or voltage of different frequencies to the rock and soil.

[0043] The acoustic emission probe of the acoustic emission acquisition module is connected to the confining pressure loading structure to receive acoustic emission signals generated by the rock and soil mass during deformation and failure.

[0044] The host computer 29 communicates with the data output terminals of the hydraulic loading module, temperature control module, high-pressure gas control module, chemical fluid control module, distributed optical fiber acquisition module, multi-frequency electrical resistivity acquisition module, and acoustic emission acquisition module to collaboratively process and analyze the acquired parameters.

[0045] The multi-parameter collaborative sensing device for CO2 injection into coal seams in this embodiment can provide a multi-field coupled environment of soil and rock masses, such as coal seam water, heat, force, and chemistry. It provides distributed optical fiber, frequency domain electrical resistivity tomography, and acoustic emission synchronous testing for the CO2 injection process, and can monitor CO2 migration and diffusion, soil and rock compressibility, and caprock sealing capacity in real time. This invention enables multi-parameter collaborative intelligent sensing, real-time synchronous acquisition, and multi-source data fusion processing, providing crucial support for research on CO2 geological storage mechanisms and engineering applications.

[0046] In some embodiments, the hydraulic loading module includes a hydraulic power unit 2, a confining pressure loading unit 3, a stress acquisition unit 4, a displacement feedback unit 5, and a loading control unit; The confining pressure loading unit 3 consists of multiple sets, each including a hydraulic cylinder 31 and an end pressure head 32. The end pressure heads 32 of the multiple sets of confining pressure loading units 3 are evenly distributed on the top wall, bottom wall, and side wall of the box body 1, thereby forming a confining pressure loading structure capable of applying pressure to the rock and soil in the front-back, left-right, and up-down directions. The hydraulic power unit 2 is connected to the hydraulic cylinders 31 of the multiple sets of confining pressure loading units 3 to deliver hydraulic oil. The hydraulic cylinders 31 of the multiple sets of confining pressure loading units 3 are all located on the outer wall of the box body 1, and their loading pistons 311 are connected to the multiple end pressure heads 32 in a one-to-one transmission to provide pressure driving force. The stress acquisition unit 4 and the displacement feedback unit 5 are spaced apart on the end face of the end pressure head 32 away from the loading piston 311. The loading control unit is communicatively connected to the hydraulic power unit 2, the confining pressure loading unit 3, the stress acquisition unit 4, and the displacement feedback unit 5 for pressure control. The host computer 29 is communicatively connected to the loading control unit.

[0047] Specifically, the hydraulic power unit 2 is used to provide a stable hydraulic source for the confining pressure loading unit 3. It includes an oil tank 201, a hydraulic pump 202 and a pipeline assembly 203 connected in sequence. The pipeline assembly 203 includes a main pipeline and multiple branch pipelines. One end of the main pipeline is connected to the hydraulic pump 202, and the other end is connected to one end of multiple branch pipelines. The other ends of the multiple branch pipelines are connected to multiple hydraulic cylinders 31 one by one. An overflow valve 204 is installed on the main pipeline.

[0048] Specifically, the hydraulic loading module can apply forward, backward, left, right, upward, and downward stresses to the soil and rock mass and achieve constant stress, constant displacement, or graded loading. Multiple sets of confining pressure loading units 3 are arranged sequentially along the height, length, and width of the box body 1; multiple sets of confining pressure loading units 3 are symmetrically arranged on any two opposite side walls of the box body 1, and multiple sets of confining pressure loading units 3 are symmetrically arranged on the top and bottom walls of the box body 1, thus forming a layered confining pressure loading structure, which can provide different confining pressures at different heights of the soil and rock mass.

[0049] Specifically, the top wall, bottom wall, and four side walls of the housing 1 are each arrayed with multiple guide holes. The end pressure head 32 is slidably connected in the guide holes and can move into the inner cavity of the housing 1 under the drive of the loading piston 311 of the hydraulic cylinder 31 to apply pressure. The end pressure head 32 can be a loading plate; the stress acquisition unit 4 can be a resistance stress testing material, used to obtain real-time stress feedback signals; the displacement feedback unit 5 can be a displacement sensor, used to obtain displacement of the loading plate and deformation information of the soil and rock mass. The host computer 29 is connected to the loading control unit, which can perform closed-loop control of the confining pressure and loading rate according to the set stress path, and is equipped with overload interlock and automatic unloading protection.

[0050] In some embodiments, the temperature control module includes a heating and cooling unit 6, a heat preservation unit 7, a temperature acquisition unit 8, and a temperature control unit; the heating and cooling unit 6 includes a circulating liquid supply pipe 61 and a circulating liquid supply mechanism disposed inside the end pressure head 32; the circulating liquid supply mechanism is connected to the circulating liquid supply pipe 61 through a pipeline to circulate circulating liquid 611 for heating or cooling the rock and soil in the pressure chamber; the heat preservation unit 7 is disposed inside the end pressure head 32 and located on the side of the circulating liquid supply pipe 61 near the loading piston 311, for reducing heat loss. Temperature gradient; Temperature acquisition unit 8 includes multiple temperature sensing units 81; Temperature sensing units 81 are installed on the inner wall of the housing 1 and at both the input and output ends of the circulating liquid supply pipe 61 to acquire temperature feedback signals; Temperature control unit is communicatively connected to the circulating liquid supply mechanism and the temperature sensing units 81 for temperature control; Host computer 29 is communicatively connected to the temperature control unit and can adjust the heating power, cooling flow rate, and liquid supply valve opening of the circulating liquid supply mechanism based on the deviation between the feedback temperature and the set temperature to achieve closed-loop temperature control, and is equipped with over-temperature protection and interlock shutdown.

[0051] In some embodiments, the high-pressure gas control module includes a CO2 supply unit 9, a pressure boosting and stabilizing unit 10, a flow regulation unit 11, a stress acquisition unit 12, a temperature acquisition unit 13, and a high-pressure gas control unit.

[0052] CO2 supply unit 9 is used to provide a high-purity CO2 gas source or liquid CO2 source; the output end of CO2 supply unit 9 is connected to the input end of pressure boosting and stabilizing unit 10; the output end of pressure boosting and stabilizing unit 10 is the CO2 injection end; stress acquisition unit 2 12 and temperature acquisition unit 2 13 are both located at the output end of pressure boosting and stabilizing unit 10, used to acquire real-time stress and temperature signals during the injection process; flow regulation unit 11 is located on pressure boosting and stabilizing unit 10, used to regulate the injection flow rate; high-pressure gas control unit is communicatively connected to CO2 supply unit 9, pressure boosting and stabilizing unit 10, flow regulation unit 11, stress acquisition unit 2 12 and temperature acquisition unit 2 13 to receive stress and temperature signals and perform injection control; host computer 29 is communicatively connected to high-pressure gas control unit.

[0053] Specifically, the pressurization and stabilization unit 10 includes a pressurization pump 101, a pressure stabilization container 102, and a high-pressure gas pipeline 103, used to pressurize CO2 and suppress stress fluctuations. The output end of the CO2 supply unit 9 is connected to the input end of the pressurization pump 101, the output end of the pressurization pump 101 is connected to the input end of the pressure stabilization container 102, the output end of the pressure stabilization container 102 is connected to the input end of the high-pressure gas pipeline 103, and the output end of the high-pressure gas pipeline 103 is the CO2 injection end. The output end of the high-pressure gas pipeline 103 is located in the middle of the rock and soil mass. The stress acquisition unit 12 and the temperature acquisition unit 13 are both located at the output end of the high-pressure gas pipeline 103. The flow rate regulation unit 11 is located on the high-pressure gas pipeline 103 and is used to regulate the injection flow rate, thereby realizing at least one injection mode among constant flow injection, staged injection, or pulse injection.

[0054] In some embodiments, the chemical fluid control module includes a solution preparation unit 14, a component metering and mixing unit 15, a storage unit 16, a dosing adjustment unit 17, a discharge and purification unit 18, and a chemical fluid control unit; the solution preparation unit 14 is used to prepare a base solution with set ion concentration, pH, and mineralization; the component metering and mixing unit 15 is connected to the solution preparation unit 14 and can quantitatively add and mix acid / alkali, salt solutions, buffer solutions, and additives according to a preset ratio; the component metering and mixing unit 15 is connected to the storage unit 16 through a liquid supply pipeline to supply the injection medium; the storage unit 16 is used for The system ensures constant volume storage and component stability of the injected medium. Storage unit 16 includes an online monitoring unit 161 for acquiring real-time feedback signals of the injected medium's chemical parameters. Dosing and regulating unit 17 is connected at one end to storage unit 16 and at the other end to an injection medium output pipe 173 located inside housing 1, capable of adding the injected medium to the soil. Discharge and purification unit 18 is located at the bottom of housing 1 for discharging the reacted medium. Chemical fluid control unit is communicatively connected to component metering and mixing unit 15, online monitoring unit 161, and dosing and regulating unit 17. Host computer 29 is communicatively connected to chemical fluid control unit.

[0055] Specifically, the solution preparation unit 14 includes multiple solution preparation containers, each containing a different base solution. The component metering and mixing unit 15 includes a metering pump 151, a pipeline valve assembly 152, and a mixing container 153. The pipeline valve assembly 152 includes a main pipe and multiple branch pipes. One end of the main pipe is connected to one end of each of the branch pipes; the other ends of the branch pipes are connected to the multiple solution preparation containers; the other end of the main pipe is connected to the mixing container 153; and metering pumps 151 are installed on each of the branch pipes. The storage unit 16 can be a pressure-resistant and corrosion-resistant storage tank for achieving constant-volume storage and component stabilization of the injected medium.

[0056] Specifically, the online monitoring unit 161 includes a pH sensor 1611 and a conductivity sensor 1612 arranged at the bottom of the storage unit 16, used to acquire real-time feedback signals of the chemical parameters of the injected medium; the dosing adjustment unit 17 includes a corrosion-resistant pipe 171 and a high-pressure nozzle 172. One end of the corrosion-resistant pipe 171 is connected to and communicates with the storage unit 16, and the other end is connected to and communicates with one end of the injected medium output pipe 173; a metering pump 151 is installed on the corrosion-resistant pipe 171; multiple high-pressure nozzles 172 are spaced apart along the length of the injected medium output pipe 173. The injected medium output pipe 173 can be made of corrosion-resistant material to improve durability.

[0057] The chemical fluid control unit communicates with and coordinates the operation of multiple metering pumps 151, pH sensor 1611, and conductivity sensor 1612; the host computer 29 communicates with the chemical fluid control unit and is used to adjust the dosage of each component according to the feedback signal, thereby maintaining the target chemical environment; the discharge and purification unit 18 includes a discharge valve installed at the bottom of the housing and a purification tank connected to the discharge valve for collecting the discharged reaction medium, and is used for discharging and safely treating the reaction medium.

[0058] In some embodiments, the distributed optical fiber acquisition module includes a sensing optical fiber 19, an optical fiber fixing unit 20, an optical fiber lead-out sealing unit 21, and a demodulation unit 22. Multiple sensing optical fibers 19 are arranged inside the housing 1 along the height direction of the housing 1; the multiple sensing optical fibers 19 are spaced apart along the width and length directions of the housing 1; multiple optical fiber fixing units 20 are arranged spaced apart along the length direction of the sensing optical fibers 19, and can couple the sensing optical fibers 19 into the rock and soil; multiple sets of optical fiber lead-out sealing units 21 are arranged, all sealingly penetrating the top wall of the housing 1; the lower ends of the multiple sets of optical fiber lead-out sealing units 21 are connected to the upper ends of the multiple sensing optical fibers 19 respectively; the host computer 29 is connected to the signal output terminal of the demodulation unit 22; the signal input terminal of the demodulation unit 22 is connected to the upper ends of the multiple sets of optical fiber lead-out sealing units 21, and is used to demodulate the echo signal of the sensing optical fibers 19 and output distributed strain and temperature data.

[0059] Specifically, the sensing fiber 19 is a distributed strain / temperature fiber arranged vertically to acquire spatially continuous strain / temperature information. The fiber fixing unit 20 is ring-shaped and can be fixed to the surface of the sensing fiber 19 to achieve reliable coupling and mechanical protection between the sensing fiber 19 and the measured structure (soil). The fiber lead-out sealing unit 21 includes a test fiber jumper 211, a communication base 212, and a fiber lead-out jumper 213. The communication base 212 penetrates the top wall of the housing 1 and is sealed. One end of the test fiber jumper 211 is connected to the bottom of the communication base 212, and the other end is connected to the top of the sensing fiber 19. One end of the fiber lead-out jumper 213 is connected to the top of the communication base 212, and the other end is connected to the signal input terminal of the demodulation unit 22. The lead-out sealing unit 21 is used to achieve fiber lead-out and maintain the seal of the pressure chamber under high temperature and high pressure conditions. The demodulation unit 22 can be an OFDR demodulator used to demodulate the echo signal of the fiber sensing unit and output distributed strain / temperature data. The host computer 29 can be a laptop computer.

[0060] In some embodiments, the multi-frequency electrical resistivity acquisition module includes multiple electrodes 23 and an electrical resistivity instrument 25; the multiple electrodes 23 are evenly distributed in layers in the soil and rock mass to construct different measurement electrode spacings and measurement methods; the multiple electrodes 23 are all electrically connected to the electrical resistivity instrument 25 through cable assembly 24; the host computer 29 is communicatively connected to the electrical resistivity instrument 25 to issue acquisition commands, record and store data.

[0061] Specifically, the cable assembly 24 includes a cable 241 and an aviation plug 242; one end of the cable 241 is connected to multiple electrodes 23, and the other end of the cable 241 is connected to the aviation plug 242, which is connected to an electrical resistivity meter 25 for applying excitation current or voltage of different frequencies to the coal seam / rock and soil layer.

[0062] In some embodiments, the acoustic emission acquisition module includes an acoustic emission probe 26, a signal transmission line 27, and an acoustic emission acquisition instrument 28; there are multiple acoustic emission probes 26, which are closely attached to and evenly distributed on the sidewall of the confining pressure loading structure away from the soil and rock mass; the acoustic emission acquisition instrument 28 is electrically connected to the multiple acoustic emission probes 26 through the signal transmission line 27 for parameter acquisition and storage; the host computer 29 is communicatively connected to the acoustic emission acquisition instrument 28.

[0063] Specifically, the acoustic emission probe 26 is mounted on the outer wall of the end pressure head 32 via a coupling agent and a clamping device to ensure stable acoustic coupling between the acoustic emission probe 26 and the measured structure (coal sample or soil / rock mass); it is used to receive acoustic emission signals generated by the coal sample or soil / rock mass during deformation and failure. The signal transmission line 27 is used to achieve high-speed sampling, threshold triggering, and event localization of multi-channel acoustic emission signals. The acoustic emission acquisition instrument 28 is used to extract and store characteristic parameters such as amplitude, energy, count, duration, and dominant frequency of acoustic emission events; the host computer 29 is used to achieve time synchronization and collaborative analysis of acoustic emission data with distributed optical fiber, multi-frequency electrical resistivity, and displacement monitoring data.

[0064] In some embodiments, the multi-parameter collaborative sensing device for CO2 injection into coal seams provided in this invention can synchronously and continuously acquire parameters such as displacement data of the end pressure head 32, temperature, pH, strain, multi-frequency electrical resistivity and acoustic emission.

[0065] Another embodiment of the present invention provides a multi-parameter collaborative sensing method for the CO2 injection coal seam process, using a multi-parameter collaborative sensing device for the CO2 injection coal seam process, including the following steps: S1: Pre-install sensing optical fibers and electrodes inside the housing 1, and arrange acoustic emission probes on the outer periphery of the confining pressure loading structure. S2: Based on the actual lithological distribution of the strata, a similar strata model is built in the pressure cavity to construct the rock and soil mass; S3: Activate the hydraulic loading module to ensure the loading pressure meets the test requirements; activate the temperature control module to heat or cool the chamber to the target temperature; activate the chemical fluid control module to inject the injection medium into the soil and rock mass, providing a water, heat, mechanical, and chemical environment for the soil and rock mass; S4: Enable the distributed fiber optic acquisition module, multi-frequency electrical resistivity acquisition module and acoustic emission acquisition module to perform real-time acquisition of multi-field data such as acoustic emission signals, temperature data and stress data; S5: Activate the high-pressure gas control module to pressurize and supply CO2 gas into the soil and rock mass, and collect multiple data in real time; S6: After the CO2 gas supply is completed, shut down the hydraulic loading module and remove the confining pressure; take photos of the soil and rock mass, and perform data processing and analysis.

[0066] Specifically, in step S1, the device is pre-installed with a sensing unit, which mainly includes a sensing fiber, electrodes, cables, a stress acquisition unit, and a temperature sensing unit. The sensing fiber is arranged vertically with a bent end to enhance light path reflection. The electrodes are fixed after the underlying soil and rock material is laid. An acoustic emission probe 26 is arranged externally for acoustic signal acquisition.

[0067] Specifically, in step S2, a similar stratum model is built in the loading model according to the actual lithological distribution of the strata. According to the similarity theory, the initial similar model material must not only meet the similarity in terms of geometric dimensions, time scale, mechanical properties and rock mass structure, but also meet the similarity in hydrological properties (mainly referring to parameters such as the water absorption rate, permeability coefficient, softening coefficient and seepage pressure of the material).

[0068] Specifically, in step S3, the sensors on each loading plate are placed and connected, the cables are connected, the loading device is started, and the sensing unit is kept in good contact with the soil and rock and is working normally.

[0069] Specifically, in step S4, the confining pressure loading unit is activated to ensure that the three-dimensional (x, y, z directions) loading pressure meets the test requirements; the heating and cooling unit 6 is activated to heat / cool the model box to the target temperature; and the chemical fluid control module is activated to inject fluid with a certain pH and salinity into the model box to provide a deep water, heat, force, and chemical environment for the soil and rock mass inside the model box.

[0070] Specifically, in step S4, the distributed optical fiber acquisition module, the multi-frequency electrical resistivity acquisition module, and the acoustic emission acquisition module are activated to simultaneously acquire parameters such as optical fiber strain and temperature parameters, multi-frequency electrical resistivity parameters, acoustic emission time signals, temperature, and stress in real time.

[0071] Specifically, in step S6, after the confining pressure and stress are removed, the oil tank 201 of the hydraulic power unit 2 returns oil, the discharge and purification unit 18 is opened, the rock and soil are photographed and recorded, and the data is processed and analyzed at the same time.

[0072] In some embodiments, data processing and analysis include comparative analysis of multi-scale synchronous test results, comparative analysis of THMC four-field test results, comparative analysis of response characteristics between parameters, predictive analysis and construction of dynamic deformation and failure digital geotechnical models. Comparative analysis of multi-scale synchronous test results: Multi-scale synchronous testing is mainly reflected in the distributed scale and the specimen scale. Real-time monitoring based on distributed optical fiber (OFDR) can obtain the continuous strain-temperature field distribution of coal and rock mass. Synchronous testing based on sensors on the loading plate, multi-frequency electrical resistivity and acoustic emission can obtain the macroscopic deformation, electrical evolution and damage event distribution of coal and rock at the overall specimen scale. Combining the distributed scale and the specimen scale is of great help in obtaining the THMC coupled damage evolution mechanism of coal and rock adsorption expansion, mineral dissolution and fracture propagation during CO2 injection.

[0073] Comparative Analysis of THMC Four-Field Test Results: The device of this invention can acquire temperature parameters, stress-strain parameters, chemical parameters (pH, conductivity, mineralization), and electro-acoustic emission parameters of coal and rock during CO2 injection. Starting from four different field parameters—temperature field (T), flow-chemical field (HC), and mechanical field (M)—the multi-field response characteristics of the entire CO2 injection process can be depicted. With time as the common variable, the joint response characteristic curves of multiple field parameters can be obtained using Origin software. Different parameters exhibit different response characteristics at different stages of CO2 injection (adsorption-expansion period, dissolution period, fracture propagation period, etc.). By constructing a multi-parameter evaluation system, the THMC field parameter response characteristics of coal and rock at each stage can be sensitively captured.

[0074] Comparative analysis of response characteristics among parameters: When the device of this invention obtains multi-source parameters, there is a certain correlation between the parameters. By constructing a correlation analysis between parameters using SPSS, the correlation between parameters such as strain, electrical properties, acoustic emission energy, and temperature can be further understood. Correlation analysis methods include neural networks, regression analysis, analysis of variance, and joint analysis. By constructing a correlation analysis between parameters, the joint response mechanism between parameters such as strain, electrical properties, and acoustic emission can be further understood, providing quantitative evidence for revealing the intrinsic relationship between CO2-induced coal and rock damage.

[0075] Predictive Analysis: The device of this invention, through multi-scale, multi-parameter collaborative testing of the CO2 injection process under THMC coupling conditions, is of great help in real-time acquisition of parameter response characteristics and precursory information of CO2 leakage (such as sudden increases in acoustic emission events, electrical anomalies, and strain abrupt changes). Based on multi-scale, multi-parameter data, mathematical modeling and prediction of coal and rock fracture propagation, CO2 migration and diffusion paths, and sealing risks can be performed using massive amounts of monitoring data. This has important engineering guiding significance for early warning of CO2 leakage, assessment of caprock sealability, and coal reservoir compressibility.

[0076] Construction of dynamic deformation and failure digital geotechnical models: Test results such as strain-temperature fields obtained through distributed optical fibers, resistivity fields obtained through frequency-domain electrical resistivity methods, and acoustic emission event localization can be used to invert the three-dimensional distribution of the damage field and CO2 saturation-related field of coal or rock / soil mass. Based on multi-parameter test results, a three-dimensional dynamic digital rock core can be constructed. The construction of the three-dimensional digital rock core can be based on a single parameter or on the fusion of multi-source data. The construction of digital rock cores significantly improves the visualization of coal deformation and failure, crack initiation and propagation, and CO2 migration and diffusion processes, providing intuitive three-dimensional dynamic image support for mechanism analysis and engineering decision-making.

[0077] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0078] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A multi-parameter collaborative sensing device for CO2 injection into coal seams, characterized in that, include: Box (1), the box (1) is rectangular and its inner cavity is a pressure-bearing cavity that can be filled with rock and soil; A hydraulic loading module is provided on the outer wall of the box (1) and its confining pressure loading structure can apply pressure in the front-back, left-right and up-down directions to the rock and soil located inside the box (1); A temperature control module, wherein the heat exchange structure of the temperature control module is disposed inside the confining pressure loading structure, thereby controlling the temperature through heat exchange when the confining pressure loading structure presses against the outer wall of the rock and soil body; A high-pressure gas control module, wherein the high-pressure gas pipeline of the high-pressure gas control module extends into the box (1) and can be implanted into the rock and soil mass for CO2 injection; A chemical fluid control module, wherein the injection medium output pipe of the chemical fluid control module is located inside the box (1) for injecting the injection medium into the rock and soil mass; A distributed optical fiber acquisition module, wherein multiple sensing optical fibers of the distributed optical fiber acquisition module are distributed in the internal space of the box (1) to acquire the internal strain and / or temperature information of the rock and soil mass; A multi-frequency electrical resistivity tomography (EPT) acquisition module, wherein multiple electrodes of the multi-frequency EPT acquisition module are distributed in the internal space of the housing (1) for applying excitation current or voltage of different frequencies to the rock and soil mass; An acoustic emission acquisition module, wherein the acoustic emission probe of the acoustic emission acquisition module is connected to the confining pressure loading structure, and is used to receive the acoustic emission signals generated by the rock and soil mass during the deformation and failure process; The host computer (29) is communicatively connected to the data output terminals of the hydraulic loading module, the temperature control module, the high-pressure gas control module, the chemical fluid control module, the distributed optical fiber acquisition module, the multi-frequency electrical resistivity acquisition module and the acoustic emission acquisition module to collaboratively process and analyze the acquired parameters.

2. The multi-parameter collaborative sensing device for CO2 injection into coal seams according to claim 1, characterized in that, The hydraulic loading module includes a hydraulic power unit (2), a confining pressure loading unit (3), a stress acquisition unit (4), a displacement feedback unit (5), and a loading control unit; The confining pressure loading unit (3) consists of multiple sets, each set including a hydraulic cylinder (31) and an end pressure head (32); the end pressure heads (32) of the multiple sets of confining pressure loading units (3) are evenly distributed on the top wall, bottom wall and side wall of the box (1), thereby enclosing and forming a confining pressure loading structure capable of applying pressure in the front-back, left-right and up-down directions to the rock and soil; the hydraulic power unit (2) connects to the hydraulic cylinders (31) of the multiple sets of confining pressure loading units (3) to deliver hydraulic oil; the hydraulic cylinders (31) of the multiple sets of confining pressure loading units (3) are all located in the box. The outer wall of the housing (1) and its loading piston (311) are connected to a plurality of the end pressure heads (32) to provide pressure driving force; the stress acquisition unit (4) and the displacement feedback unit (5) are spaced apart on the end face of the end pressure head (32) away from the loading piston (311); the loading control unit is communicatively connected to the hydraulic power unit (2), the confining pressure loading unit (3), the stress acquisition unit (4) and the displacement feedback unit (5) to perform pressure control; the host computer (29) is communicatively connected to the loading control unit.

3. The multi-parameter collaborative sensing device for CO2 injection into coal seams according to claim 2, characterized in that, The temperature control module includes a heating and cooling unit (6), a heat preservation unit (7), a temperature acquisition unit (8), and a temperature control unit; the heating and cooling unit (6) includes a circulating liquid supply pipe (61) and a circulating liquid supply mechanism disposed inside the end pressure head (32); the circulating liquid supply mechanism is connected to the circulating liquid supply pipe (61) through a pipeline to circulate and transport circulating liquid (611); the heat preservation unit (7) is disposed inside the end pressure head (32) and located on the side of the circulating liquid supply pipe (61) near the loading piston (311); the temperature acquisition unit (8) includes multiple temperature sensing units (81); the inner wall of the housing (1) and the input and output ends of the circulating liquid supply pipe (61) are all provided with the temperature sensing units (81); the temperature control unit is communicatively connected to the circulating liquid supply mechanism and the temperature sensing units (81) for temperature control; the host computer (29) is communicatively connected to the temperature control unit.

4. The multi-parameter collaborative sensing device for CO2 injection into coal seams according to claim 1, characterized in that, The high-pressure gas control module includes a CO2 supply unit (9), a pressure boosting and stabilizing unit (10), a flow regulation unit (11), a stress acquisition unit (12), a temperature acquisition unit (13), and a high-pressure gas control unit; The output end of the CO2 supply unit (9) is connected to the input end of the pressure boosting and stabilizing unit (10); the output end of the pressure boosting and stabilizing unit (10) is the CO2 injection end; the stress acquisition unit 2 (12) and the temperature acquisition unit 2 (13) are both located at the output end of the pressure boosting and stabilizing unit (10) to acquire real-time stress and temperature signals during the injection process; the flow rate adjustment unit (11) is located on the pressure boosting and stabilizing unit (10) to regulate the injection flow rate; the high-pressure gas control unit is communicatively connected to the CO2 supply unit (9), the pressure boosting and stabilizing unit (10), the flow rate adjustment unit (11), the stress acquisition unit 2 (12), and the temperature acquisition unit 2 (13) to receive stress and temperature signals and perform injection control; the host computer (29) is communicatively connected to the high-pressure gas control unit.

5. The multi-parameter collaborative sensing device for CO2 injection into coal seams according to claim 1, characterized in that, The chemical fluid control module includes a solution preparation unit (14), a component metering and mixing unit (15), a storage unit (16), a dosing adjustment unit (17), a discharge and purification unit (18), and a chemical fluid control unit. The solution preparation unit (14) is used to prepare a base solution with set ion concentration, pH, and mineralization. The component metering and mixing unit (15) is connected to the solution preparation unit (14) and can quantitatively add and mix acid / alkali, salt solutions, buffer solutions, and additives according to a preset ratio. The component metering and mixing unit (15) is connected to the storage unit (16) through a liquid supply pipeline to supply the injection medium. The storage unit (16) is used to store the injection medium at a constant volume. The components are stable; the storage unit (16) is equipped with an online monitoring unit (161) for obtaining real-time feedback signals of chemical parameters of the injection medium; one end of the dosing adjustment unit (17) is connected to the storage unit (16), and the other end is an injection medium output pipe set in the box (1) and capable of adding injection medium to the rock and soil; the discharge and purification unit (18) is set at the bottom of the box (1) for discharging the medium after the reaction; the chemical fluid control unit is communicatively connected to the component metering and mixing unit (15), the online monitoring unit (161) and the dosing adjustment unit (17); the host computer (29) is communicatively connected to the chemical fluid control unit.

6. The multi-parameter collaborative sensing device for CO2 injection into coal seams according to claim 1, characterized in that, The distributed optical fiber acquisition module includes a sensing optical fiber (19), an optical fiber fixing unit (20), an optical fiber lead-out sealing unit (21), and a demodulation unit (22). The sensing optical fibers (19) are multiple and arranged inside the box (1) along the height direction of the box (1); the multiple sensing optical fibers (19) are spaced apart along the width and length directions of the box (1); there are multiple optical fiber fixing units (20), which are spaced apart along the length direction of the sensing optical fibers (19) and can couple the sensing optical fibers (19) into the rock and soil; there are multiple sets of optical fiber lead-out sealing units (21), which are all sealed and penetrate through the top wall of the box (1); the lower ends of the multiple sets of optical fiber lead-out sealing units (21) are connected to the upper ends of the multiple sensing optical fibers (19) respectively; the host computer (29) is communicatively connected to the signal output end of the demodulation unit (22); the signal input end of the demodulation unit (22) is connected to the upper ends of the multiple sets of optical fiber lead-out sealing units (21) for demodulating the echo signal of the sensing optical fibers (19) and outputting distributed strain and temperature data.

7. The multi-parameter collaborative sensing device for CO2 injection into coal seams according to claim 1, characterized in that, The multi-frequency electrical resistivity acquisition module includes multiple electrodes (23) and an electrical resistivity instrument (25); the multiple electrodes (23) are evenly distributed in layers in the rock and soil; the multiple electrodes (23) are electrically connected to the electrical resistivity instrument (25) through a cable assembly (24); the host computer (29) is communicatively connected to the electrical resistivity instrument (25).

8. The multi-parameter collaborative sensing device for CO2 injection into coal seams according to claim 1, characterized in that, The acoustic emission acquisition module includes an acoustic emission probe (26), a signal transmission line (27), and an acoustic emission acquisition instrument (28). There are multiple acoustic emission probes (26), which are closely attached to and evenly distributed on the side wall of the confining pressure loading structure away from the soil and rock mass. The acoustic emission acquisition instrument (28) is electrically connected to the multiple acoustic emission probes (26) through the signal transmission line (27) to collect and store parameters. The host computer (29) is communicatively connected to the acoustic emission acquisition instrument (28).

9. A multi-parameter collaborative sensing method for CO2 injection into coal seams, characterized in that, Using the multi-parameter collaborative sensing device for CO2 injection into coal seams according to any one of claims 1-8, the process includes the following steps: S1: Pre-install sensing optical fibers and electrodes inside the housing 1, and arrange acoustic emission probes on the outer periphery of the confining pressure loading structure. S2: Based on the actual lithological distribution of the strata, a similar strata model is built in the pressure cavity to construct the rock and soil mass; S3: Activate the hydraulic loading module to ensure the loading pressure meets the test requirements; activate the temperature control module to heat or cool the chamber to the target temperature; activate the chemical fluid control module to inject the injection medium into the soil and rock mass, providing a water, heat, mechanical, and chemical environment for the soil and rock mass; S4: Enable the distributed fiber optic acquisition module, multi-frequency electrical resistivity acquisition module and acoustic emission acquisition module to perform real-time acquisition of multi-field data such as acoustic emission signals, temperature data and stress data; S5: Activate the high-pressure gas control module to pressurize and supply CO2 gas into the soil and rock mass, and collect multiple data in real time; S6: After the CO2 gas supply is completed, shut down the hydraulic loading module and remove the confining pressure; take photos of the soil and rock mass, and perform data processing and analysis.

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