A displacement coal methane multiphase multi-component fluid migration monitoring system and method

Abstract

The application discloses a kind of displacement coal methane multiphase multicomponent fluid migration monitoring system and method, it is related to CO2 displacement methane technical field, monitoring system includes reservoir simulation component, multiparameter monitoring component, diffusion-seepage conversion monitoring component, visualization and quantization component and data acquisition and processing component;Reservoir simulation component can simulate real formation environment, multiparameter monitoring component can realize the synchronous monitoring of concentration, flow rate, saturation, pore pressure and other parameters in multiphase multicomponent fluid diffusion / seepage process, diffusion-seepage conversion monitoring component can accurately capture fluid diffusion-seepage conversion condition and critical parameter, visualization and quantization component can realize the visualization observation and quantization characterization of displacement front position and morphology.The monitoring system is highly controllable, easy to operate, safe and reliable, and can provide reliable experimental support for CO2 displacement methane mechanism and process optimization research.

Description

Technical Field

[0001] This invention relates to the field of CO2 displacement of methane technology, and in particular to a monitoring system and method for multiphase and multicomponent fluid transport of methane in coal. Background Technology

[0002] CO2 displacement of methane technology is a core technology for the coordinated development of efficient extraction and geological storage of unconventional natural gas (coalbed methane, shale gas, etc.). Its core mechanism is to utilize the adsorption competition effect between CO2 and methane in the reservoir medium to efficiently replace and displace adsorbed and free methane in the reservoir, while achieving permanent geological storage of CO2, which has the dual significance of energy development and carbon emission reduction.

[0003] Low-permeability coal reservoirs are widely distributed and have low permeability, making it difficult to achieve efficient development using conventional in-situ coalbed methane extraction methods. CO2-driven methane displacement technology provides an effective approach for natural gas extraction and CO2 storage in low-permeability reservoirs. In indoor simulation experiments and field engineering applications of CO2-driven methane displacement, the diffusion and seepage physical processes and parameter evolution characteristics of multiphase, multi-component fluids (CO2, CH4, formation water, and reservoir impurities) directly determine the displacement efficiency and CO2 storage stability. Accurate capture of fluid diffusion-seepage transition conditions (such as pressure thresholds and concentration gradient thresholds) is a core prerequisite for revealing the synergistic mechanism of diffusion and seepage during displacement and optimizing displacement process parameters. The displacement front, as a dynamic interface region between CO2 and methane, directly reflects the advancement characteristics of the displacement front through its positional migration patterns, morphological evolution characteristics, and quantitative parameters, providing important theoretical and engineering guidance for predicting the displacement range and optimizing injection parameters.

[0004] Currently, existing experimental equipment and monitoring technologies for CO2 displacement of methane still have significant technical shortcomings: First, the monitoring parameters are limited. Existing equipment can only monitor single parameters such as displacement pressure, flow rate, or outlet fluid composition, and cannot simultaneously monitor and systematically characterize multiple parameters such as concentration distribution, fluid velocity, phase saturation, and pore pressure during the diffusion / seepage process of multiphase and multi-component fluids. This makes it difficult to comprehensively and accurately reflect the fluid transport and evolution laws. Second, there is a lack of targeted monitoring technologies for diffusion-seepage transition conditions, making it impossible to accurately capture critical transition parameters. This results in insufficient in-depth research on the synergistic mechanism of diffusion and seepage during displacement, hindering the improvement of the displacement mechanism. Third, monitoring of the displacement front relies heavily on indirect inference methods such as changes in outlet composition, making it difficult to achieve visual observation of the front morphology. Furthermore, there is a lack of scientific and effective quantitative characterization methods, making it impossible to accurately obtain core parameters such as front position, thickness, and propulsion speed, which is not conducive to the precise optimization of the displacement process.

[0005] Therefore, developing a CO2-driven methane displacement device that can simultaneously monitor diffusion / seepage parameters of multiphase and multicomponent fluids, accurately capture diffusion-seepage conversion conditions, and enable visual observation and quantitative characterization of the displacement front is an urgent issue to be addressed in this field. It has significant theoretical guidance and engineering application value for CO2 geological treatment and efficient methane extraction from low-permeability reservoirs. Summary of the Invention

[0006] This solution addresses the problems and needs raised above by proposing a monitoring system and method for the multiphase and multicomponent fluid transport of methane in displaced coal. The system achieves the aforementioned technical objectives and brings about several other technical benefits due to the adoption of the following technical features.

[0007] One object of the present invention is to provide a monitoring system for the multiphase, multicomponent fluid transport of methane in displaced coal, comprising: The reservoir simulation component includes: a visualization high-pressure core holder, which is filled with formation reservoir medium, and the reservoir simulation component has an input end and an output end; The fluid supply assembly includes: a CO2 cylinder, a methane cylinder, a formation water storage tank, and an intermediate container. The CO2 cylinder, methane cylinder, and formation water storage tank are all connected to the intermediate container. The intermediate container is configured to premix CO2, methane, and formation water to simulate a real formation multiphase and multicomponent fluid environment. The CO2 cylinder and the intermediate container are connected to the input terminal. The environmental control component includes: a constant temperature chamber, a high-pressure booster pump, and a pressure sensor. The constant temperature chamber is located outside the reservoir simulation component and is configured to adjust the temperature of the formation reservoir medium to simulate the temperature environment of formations at different depths. The high-pressure booster pump is connected between the intermediate container and the input end and is configured to adjust the displacement pressure of the formation reservoir medium to simulate different formation pressure conditions. The pressure sensor is configured to monitor the internal pressure information of the constant temperature chamber. A fluid recovery component, connected to the output end, is configured to separate the gas phase and liquid phase produced after displacement. A multi-parameter monitoring component, connected to the fluid recovery component, is configured to monitor fluid component concentration, fluid flow rate, phase saturation, formation reservoir pore pressure, and the temperature of the reservoir simulation component. A diffusion-permeation conversion monitoring component, connected to the reservoir simulation component, is configured to capture fluid-permeation conversion conditions during CO2 displacement of methane and identify critical conversion parameters. The visualization and quantification components are configured to enable the visualization and observation of the position and morphology of the displacement front inside the high-pressure core holder, and to scientifically quantify the characteristic parameters of the front to obtain the advancement law of the displacement front. The data acquisition and processing component is coupled to the multi-parameter monitoring component, the diffusion-seepage conversion monitoring component, and the visualization and quantification component, and is configured to acquire and process the monitoring data from the multi-parameter monitoring component, the diffusion-seepage conversion monitoring component, and the visualization and quantification component.

[0008] In addition, the multiphase, multicomponent fluid transport monitoring system for methane in displaced coal according to the present invention may also have the following technical features: In one example of the present invention, the fluid recovery assembly includes a gas-liquid separator and a recovery tank. The gas-liquid separator has at least an inlet end and a first outlet end and a second outlet end. The inlet end is connected to the output end, the first outlet end is connected to the recovery tank, and the second outlet end is connected to a multi-parameter monitoring assembly. The gas-liquid separator is configured to separate the gas phase and liquid phase produced after displacement. The gas phase flows into the multi-parameter monitoring assembly, and the liquid phase is collected in the recovery tank.

[0009] In one example of the present invention, the multi-parameter monitoring component includes a gas chromatograph and a spectrometer. The gas chromatograph is connected to a second outlet and is configured to determine the concentrations of CO2 and methane components in the produced gas phase to reflect the evolution of fluid components during displacement in real time. The spectrometer is connected to a visualization high-pressure core holder and is configured to monitor the concentration distribution characteristics of CO2, methane, and formation water at different locations and times within the formation reservoir medium in real time, capturing the concentration gradient changes during fluid diffusion and seepage.

[0010] In one example of the present invention, the multi-parameter monitoring component further includes: a nuclear magnetic resonance imaging module and a micro / nano piezoresistive sensing array. The nuclear magnetic resonance imaging module is arranged along the circumferential direction of the visualized high-pressure core holder and is configured to monitor the flow velocity distribution of fluids inside the reservoir, while characterizing the phase saturation distribution of CO2, methane, and formation water. The micro / nano piezoresistive sensing array is located within the formation reservoir medium and is configured to capture pore pressure fluctuations during fluid seepage to reflect the characteristics of fluid flow velocity changes.

[0011] In one example of the present invention, the multi-parameter monitoring component further includes: a distributed optical fiber pressure sensor and a temperature sensor. The distributed optical fiber pressure sensor is arranged along the axial and radial directions of the visualized high-pressure core holder and is configured to monitor the spatiotemporal evolution characteristics of pore pressure at different locations inside the formation reservoir medium. The temperature sensor is installed inside the visualized high-pressure core holder, the intermediate container, and the constant temperature chamber, respectively, and is configured to realize synchronous monitoring of the temperature in each key area during the displacement process, ensure the stability of temperature parameters, and avoid interference of temperature fluctuations on the monitoring results.

[0012] In one example of the present invention, the diffusion-permeability conversion monitoring component includes: a pressure difference sensor and a concentration gradient sensor. The pressure difference sensor is installed between the input and output ends of the reservoir simulation component and is configured to monitor the dynamic changes of fluid pressure difference in real time. The concentration gradient sensor is arranged along the axial direction of the inner surface of the visualization high-pressure core holder and is configured to measure the fluid concentration gradient at different locations inside the formation reservoir medium and capture the abrupt change characteristics of the concentration gradient.

[0013] In one example of the present invention, the visualization and quantification components include: an industrial process tomography module and a high-definition high-speed camera module. The industrial process tomography module is configured to realize three-dimensional visualization imaging of the displacement front inside the reservoir simulation component, clearly presenting the spatial morphology and distribution characteristics of the front, capturing the dynamic changes of the front in real time, and adapting to the high-pressure multiphase flow experimental environment. The high-definition high-speed camera module is set close to the visualization high-pressure core holder and configured to record the dynamic advancement process of the displacement front in real time, realizing intuitive visualization observation of the front morphology.

[0014] In one example of the present invention, the visualization and quantization component further includes: an image acquisition card and a quantization analysis module. The image acquisition card is used to simultaneously acquire industrial process tomography data and high-definition camera images from the industrial process tomography module and the high-definition high-speed camera module. The quantization analysis module is configured to perform precise processing on the displacement leading edge image, extract leading edge feature parameters, and achieve quantization characterization.

[0015] In one example of the present invention, the data acquisition and processing component includes: a data acquisition card, a data processor, and a display terminal. The data acquisition card is configured to acquire parameter data and image data of a multi-parameter monitoring component, a diffusion-percolation conversion monitoring component, and a visualization and quantification component. The data processor is configured to preprocess the acquired raw data and perform correlation analysis between the image data and the parameter data. The display terminal is configured to display various monitoring data, leading-edge visualization images, and data analysis results in real time.

[0016] Another object of the present invention is to provide a monitoring method for a multiphase, multicomponent fluid transport monitoring system for methane in displaced coal as described above, comprising the following steps: S10: Equipment commissioning and preliminary preparation: First, check the sealing of the equipment connections and conduct an airtightness test. Adjust the constant temperature chamber to the preset formation temperature for the experiment, start the environmental control components, and adjust them to the preset displacement pressure range. Perform precise calibration on the multi-parameter monitoring components, diffusion-seepage conversion monitoring components, and visualization and quantification components to ensure that the monitoring accuracy meets the experimental requirements. S20: Initial State Stabilization and Baseline Data Recording: Start the methane cylinder and adjust the methane injection pressure and flow rate through the fluid supply component to inject methane into the reservoir simulation component until the formation reservoir medium reaches methane adsorption saturation. During this process, start the multi-parameter monitoring component to simultaneously monitor the pore pressure, temperature, and methane saturation inside the reservoir. When each parameter remains stable for more than the preset time, record the parameter data at this time as experimental baseline data to provide a reference for subsequent displacement process parameter comparison. S30: Displacement Process Initiation and Multi-Parameter Synchronous Monitoring: The methane cylinder is shut off, and a premixed multiphase, multi-component fluid from the intermediate container is injected into the reservoir simulation component at the preset pressure and flow rate using a high-pressure booster pump, initiating the CO2 displacement of methane experiment. Simultaneously, the multi-parameter monitoring component, diffusion-permeation conversion monitoring component, visualization and quantification component, and data acquisition and processing component are activated to achieve synchronous monitoring throughout the entire process. Specifically, the multi-parameter monitoring component monitors fluid component concentration, flow rate, saturation, pore pressure, and temperature in real time; the diffusion-permeation conversion monitoring component captures changes in pressure difference and concentration gradient in real time; the visualization and quantification component observes and quantifies the front position and morphology in real time; and the data acquisition and processing component synchronously acquires, transmits, stores, and analyzes various types of data in real time. S40: Diffusion-Permeation Transition Condition Capture and Recording: During the experiment, the diffusion-permeation transition monitoring component continuously monitors the dynamic changes of fluid pressure difference and concentration gradient inside the reservoir simulation component, and compares the monitoring signals with preset thresholds in real time; when the pressure difference and concentration gradient reach the preset thresholds, and the sudden change in fluid velocity exceeds the preset range, it is determined to be the diffusion-permeation transition critical point, and the critical parameters of pressure, concentration gradient, and temperature at the transition moment are recorded simultaneously to complete the capture and characterization of diffusion-permeation transition conditions; S50: Visualization and Quantitative Characterization of Displacement Front: During the displacement process, the visualization and quantification components work continuously to capture the position migration, morphological evolution, and dynamic advancement of the displacement front in real time. The collected imaging data and camera images are continuously processed by image processing algorithms to extract quantitative parameters of the front position coordinates, thickness, and advancement speed, update the morphological quantification curve of the front, and establish the correlation between the front features and fluid transport parameters, so as to realize full-process visualization and precise quantitative characterization of the displacement front. S60: Experiment End and Data Processing: When the displacement process reaches the preset experimental termination conditions, stop the operation of the high-pressure booster pump, shut down the fluid supply component, environmental control component, and all monitoring components, and end the displacement experiment; start the fluid recovery component to recover the separated gas and liquid phases, the gas phase is purified and recycled, and the liquid phase is circulated to the formation water storage tank; integrate and analyze the monitoring data and image data of the entire experimental process through the data acquisition and processing component to generate a standardized experimental report; export and archive the experimental data to complete the entire experimental operation process.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The equipment is complete and fully functional, realizing simultaneous monitoring and characterization of multiple parameters. It integrates a variety of advanced monitoring technologies and can simultaneously monitor multiple core parameters such as fluid component concentration, flow rate, and saturation, covering the entire diffusion and seepage process. It comprehensively reflects the transport law of multiphase and multi-component fluids and solves the deficiency of existing equipment in monitoring only one parameter.

[0018] 2. A targeted diffusion-percolation transition monitoring component is designed to accurately capture the critical point of diffusion-percolation transition through signal capture and threshold recognition, and simultaneously record critical parameters. This fills the technical gap that existing equipment cannot specifically monitor transition conditions, and provides reliable data support for the study of displacement mechanisms.

[0019] 3. Achieve visual observation and quantitative characterization of the displacement front. By combining industrial process tomography and high-definition video technology, overcome the limitations of traditional indirect inference. Extract core quantitative parameters of the front through the quantitative analysis module to provide accurate guidance for displacement process optimization and displacement range prediction.

[0020] 4. The equipment has high simulation realism and wide applicability. Temperature and pressure parameters can be flexibly adjusted to adapt to different types of reservoir media and multiphase multicomponent fluid systems. It is suitable for CO2 displacement of methane experiments of different scales and conditions. The operation method is standardized and the process is clear, which is convenient for experimental personnel to operate and promote its application.

[0021] 5. Efficient and convenient data processing: Through data acquisition and processing components, data can be collected, analyzed and displayed synchronously, and experimental reports can be generated automatically, which greatly improves the efficiency of experimental data processing, reduces the workload of experimental personnel, and enhances the convenience of experimental research.

[0022] The preferred embodiments of the invention will be described in more detail below with reference to the accompanying drawings, so as to facilitate an understanding of the features and advantages of the invention. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention will be briefly described below. The drawings are merely illustrative of some embodiments of the present invention and are not intended to limit the scope of the present invention to all embodiments.

[0024] Figure 1 This is a schematic diagram of the structure of a multiphase, multicomponent fluid transport monitoring system for displaced coal according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the connection structure between the reservoir simulation component and the parameter monitoring component according to an embodiment of the present invention; Figure 3 This is a schematic diagram of parameter extraction for the quantitative characterization of the displacement front according to an embodiment of the present invention.

[0025] List of reference numerals in the attached diagram: Monitoring system 100; Reservoir simulation component 10; Visualized high-pressure core holder 11; Input terminal 12; Output terminal 13; Sealing component 14; Formation reservoir medium 15; Displacement leading edge 16; Fluid supply assembly 20; CO2 cylinder 21; Methane cylinder 22; Formation water storage tank 23; Intermediate container 24; Stirring device 25; Pressure regulator 26; Flow meter 27; Environmental control component 30; Incubator 31; High-pressure booster pump 32; Pressure sensor 33; Fluid recovery assembly 40; Gas-liquid separator 41; Entry point 411; First exit end 412; Second exit end 413; Recycling tank 42; Multi-parameter monitoring component 50; Gas chromatograph 51; Spectral sensor 52; Magnetic resonance imaging module 53; 54 micro / nano piezoresistive sensing arrays; Distributed fiber optic pressure sensor 55; Temperature sensor 56; Diffusion-permeation conversion monitoring component 60; Differential pressure sensor 61; Concentration gradient sensor 62; Signal amplifier 63; Threshold recognition module 64; 70 visualization and quantification components; Industrial process tomography module 71; 72 high-definition high-speed camera modules; Image acquisition card 73; Quantitative Analysis Module 74; Data acquisition and processing components 80; Data acquisition card 81; Data processor 82; Display terminal 83. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The same reference numerals in the drawings represent the same components. It should be noted that the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] According to a first aspect of the present invention, a multiphase, multicomponent fluid transport monitoring system 100 for displaced coal, such as... Figure 1 As shown, it includes: The reservoir simulation component 10 includes: a visualization high-pressure core holder 11, which is filled with formation reservoir medium 15, and the reservoir simulation component 10 has an input end 12 and an output end 13. The fluid supply assembly 20 includes: a CO2 cylinder 21, a methane cylinder 22, a formation water storage tank 23, and an intermediate container 24. The CO2 cylinder 21, methane cylinder 22, and formation water storage tank 23 are all connected to the intermediate container 24. The intermediate container 24 is configured to premix CO2, methane, and formation water to simulate a real formation multiphase and multicomponent fluid environment. The CO2 cylinder 21 and the intermediate container 24 are connected to the input terminal 12. Specifically, the CO2 cylinder 21, methane cylinder 22, and formation water storage tank 23 form a fluid supply system. The system consists of a water storage tank 23 and an intermediate container 24. Each fluid source is connected to the input end 12 of the reservoir simulation component 10 via a high-pressure corrosion-resistant pipeline. A precision pressure regulator 26 and a mass flow meter 27 are connected in series at the outlet ends of the CO2 cylinder 21 and methane cylinder 22, respectively, to achieve precise control of the fluid injection pressure and flow rate. The intermediate container 24 is used to premix CO2, methane, and formation water, simulating a real formation multiphase and multicomponent fluid environment. A stirring device 25 and a temperature sensor 56 are installed inside the container to ensure uniform fluid mixing and stable temperature. It is worth noting that the stirring device 25 in the intermediate container 24 is used to stir the premixed multiphase and multicomponent fluid, making it more uniform.

[0028] The environmental control component 30 includes: a constant temperature chamber 31, a high-pressure booster pump 32, and a pressure sensor 33. The constant temperature chamber 31 is located outside the reservoir simulation component 10 and is configured to adjust the temperature of the formation reservoir medium 15 to simulate the temperature environment of formations at different depths. The high-pressure booster pump 32 is connected between the intermediate container 24 and the input terminal 12 and is configured to adjust the displacement pressure of the formation reservoir medium 15 to simulate different formation pressure conditions. The pressure sensor 33 is configured to monitor the internal pressure information of the constant temperature chamber 31. In other words, the environmental control component 30 includes... The system consists of two parts: temperature and pressure control. The reservoir simulation component 10 and the intermediate container 24 are both placed inside the constant temperature chamber 31. The constant temperature chamber 31 can achieve precise temperature control within the range of 0℃-100℃, with a temperature control accuracy of ±0.1℃, and can simulate the temperature environment of different formation depths. The pressure control system consists of a high-pressure booster pump 32 and a high-precision pressure sensor, which are connected to the input end 12 and output end 13 of the reservoir simulation component 10 and the intermediate container 24. It can achieve precise adjustment and stable control of the displacement pressure within the range of 0MPa-50MPa, with a pressure control accuracy of ±0.01MPa, simulating different formation pressure conditions.

[0029] The fluid recovery component 40 is connected to the output terminal 13 and is configured to separate the gas phase and liquid phase produced after displacement. The multi-parameter monitoring component 50 is connected to the fluid recovery component 40 and is configured to monitor fluid component concentration, fluid flow rate, phase saturation, formation reservoir pore pressure and the temperature of the reservoir simulation component 10. The diffusion-permeation conversion monitoring component 60 is connected to the reservoir simulation component 10 and is configured to capture the fluid-permeation conversion conditions during the CO2 displacement of methane process and identify the critical conversion parameters. The visualization and quantification component 70 is configured to enable the visualization observation of the position and morphology of the displacement front 16 inside the high-pressure core holder 11, and to scientifically quantify the characteristic parameters of the front to obtain the propulsion law of the displacement front 16. The data acquisition and processing component 80 is coupled to the multi-parameter monitoring component 50, the diffusion-seepage conversion monitoring component 60, and the visualization and quantification component 70, and is configured to acquire and process the monitoring data of the multi-parameter monitoring component 50, the diffusion-seepage conversion monitoring component 60, and the visualization and quantification component 70.

[0030] The working process of the monitoring system 100 is as follows: Equipment commissioning and preliminary preparation: First, check the sealing of the equipment connections and conduct an airtightness test. Adjust the constant temperature chamber 31 to the preset formation temperature. Start the environmental control component 30 and adjust it to the preset displacement pressure range. Perform precise calibration on the multi-parameter monitoring component 50, diffusion-permeability conversion monitoring component 60, and visualization and quantification component 70 to ensure that the monitoring accuracy meets experimental requirements. Initial state stabilization and baseline data recording: Start the methane cylinder 22. Adjust the methane injection pressure and flow rate through the pressure regulator 26 and flow meter 27 of the fluid supply component 20 to inject methane into the reservoir simulation component 10 until the formation reservoir medium 15 reaches methane adsorption saturation. During this process, start the multi-parameter... The monitoring component 50 synchronously monitors the pore pressure, temperature, and methane saturation inside the reservoir. When each parameter remains stable for a specified period of time, the data is recorded as experimental baseline data to provide a reference for parameter comparison in subsequent displacement processes. Displacement process initiation and multi-parameter synchronous monitoring: The methane cylinder 22 is closed, and the premixed multiphase multi-component fluid in the intermediate container 24 is injected into the reservoir simulation component 10 at the preset pressure and flow rate via the high-pressure booster pump 32, initiating the CO2 displacement of methane experimental process. Simultaneously, the multi-parameter monitoring component 50, the diffusion-percolation conversion monitoring component 60, the visualization and quantification component 70, and the data acquisition and processing component 80 are activated to achieve synchronous monitoring throughout the entire process. The system includes a multi-parameter monitoring component 50 that monitors fluid component concentration, flow rate, saturation, pore pressure, and temperature in real time; a diffusion-permeability conversion monitoring component 60 that captures changes in pressure difference and concentration gradient in real time; a visualization and quantification component 70 that observes and quantifies the front position and morphology in real time; and a data acquisition and processing component 80 that simultaneously acquires, transmits, stores, and analyzes various types of data in real time. The diffusion-permeability conversion condition capture and recording component 60 continuously monitors the dynamic changes in fluid pressure difference and concentration gradient within the reservoir simulation component 10 during the experiment, and compares the monitoring signals with preset thresholds in real time. When the pressure difference and concentration gradient reach the preset thresholds, and the fluid flow rate changes abruptly... When the flow exceeds the preset range, it is determined to be the critical point of diffusion-seepage transition. The critical parameters of pressure, concentration gradient, and temperature at the transition moment are recorded simultaneously to capture and characterize the diffusion-seepage transition conditions. Visual observation and quantitative characterization of the displacement front 16: During the displacement process, the visualization and quantification component 70 works continuously to capture the position migration, morphological evolution, and dynamic advancement process of the displacement front 16 in real time. The acquired imaging data and camera images are continuously extracted using image processing algorithms to extract the quantitative parameters of the front position coordinates, thickness, and advancement speed, update the quantitative curve of the front morphology, and establish the correlation between the front characteristics and fluid transport parameters to achieve full-process visual observation and precise quantitative characterization of the displacement front 16.Experiment End and Data Processing: When the displacement process reaches the preset experimental termination conditions, the high-pressure booster pump 32 is stopped, and the fluid supply component 20, environmental control component 30, and all monitoring components are shut down, ending the displacement experiment. The fluid recovery component 40 is activated to recover the separated gas and liquid phases. The gas phase is purified and reused, while the liquid phase is circulated to the formation water storage tank 23. The data acquisition and processing component 80 integrates and analyzes the monitoring data and image data from the entire experimental process, generating a standardized experimental report. The experimental data is exported and archived, completing the entire experimental operation process.

[0031] The monitoring system is complete and fully functional, realizing simultaneous monitoring and characterization of multiple parameters. It integrates a variety of advanced monitoring technologies and can simultaneously monitor multiple core parameters such as fluid component concentration, flow rate, and saturation, covering the entire diffusion and seepage process. It comprehensively reflects the transport laws of multiphase and multi-component fluids and solves the problem of single monitoring parameters in existing equipment.

[0032] The monitoring system 100 is specifically equipped with a diffusion-seepage transition monitoring component 60. Through signal capture and threshold recognition, it can accurately capture the critical point of diffusion-seepage transition and simultaneously record critical parameters. This fills the technical gap that existing equipment cannot specifically monitor transition conditions and provides reliable data support for the study of displacement mechanisms.

[0033] The monitoring system 100 enables the visualization and quantitative characterization of the displacement leading edge 16. Combining industrial process tomography and high-definition video technology, it overcomes the limitations of traditional indirect inference. Through the quantitative analysis module 74, it extracts the core quantitative parameters of the leading edge, providing precise guidance for displacement process optimization and displacement range prediction.

[0034] The monitoring system boasts high equipment simulation realism and wide applicability. It allows for flexible adjustment of temperature and pressure parameters, adapting to different types of reservoir media and multiphase, multi-component fluid systems. It is suitable for CO2-driven methane displacement experiments of varying scales and conditions. The operating methods are standardized and the procedures are clear, facilitating operation by experimental personnel and widespread application.

[0035] This monitoring system offers highly efficient and convenient data processing. Through the data acquisition and processing components, it enables synchronous data acquisition, analysis, and display, automatically generating experimental reports. This significantly improves the efficiency of experimental data processing, reduces the workload of experimental personnel, and enhances the convenience of experimental research.

[0036] In one example of the present invention, the fluid supply assembly 20 further includes a pressure regulator 26 and a flow meter 27. The pressure regulator 26 and flow meter 27 are sequentially arranged between the intermediate container 24 and the high-pressure booster pump 32 to control the pressure and flow rate of the premixed multiphase multicomponent fluid output from the intermediate container 24 injected into the visualized high-pressure core holder 11. Similarly, the pressure regulator 26 and flow meter 27 are sequentially arranged between the CO2 cylinder 21 and the high-pressure booster pump 32 to control the pressure and flow rate of the CO2 gas output from the CO2 cylinder 21 injected into the visualized high-pressure core holder 11. In other words, while the CO2 cylinder 21 is connected to the intermediate container 24, a branch is sequentially connected to the pressure regulator 26 and flow meter 27, and then connected to the high-pressure booster pump 32.

[0037] In one example of the present invention, the interior of the visualized high-pressure core holder 11 is filled with simulated formation reservoir media 15 such as coal, rock, and shale; the main body of the holder is made of high-strength transparent high-pressure resistant materials such as sapphire, which has a good visualization effect and can directly observe the internal fluid transport state and the morphology of the displacement front 16; high-performance sealing components 14 are configured at both ends of the holder to effectively prevent high-pressure fluid leakage; multiple monitoring interfaces are uniformly reserved along the axial and radial directions on the sidewall for installing various monitoring sensors to realize multi-position parameter monitoring inside the reservoir.

[0038] In one example of the present invention, the fluid recovery assembly 40 includes a gas-liquid separator 41 and a recovery tank 42. The gas-liquid separator 41 has at least an inlet end 411, a first outlet end 412, and a second outlet end 413. The inlet end 411 is connected to the output end 13, the first outlet end 412 is connected to the recovery tank 42, and the second outlet end 413 is connected to a multi-parameter monitoring assembly 50. The gas-liquid separator 41 is configured to separate the gas phase and liquid phase produced after displacement. The gas phase flows into the multi-parameter monitoring assembly 50, and the liquid phase is collected in the recovery tank 42.

[0039] In other words, the gas-liquid separator 41 is connected to the output end 13 of the reservoir simulation component 10 to achieve efficient separation of the gas phase (a mixture of CO2 and CH4) and the liquid phase (formation water) produced after displacement. The separated liquid phase is introduced into the recovery tank 42 for collection and treatment. After purification, the liquid phase can be recycled, which avoids fluid waste and prevents environmental pollution.

[0040] In one example of the present invention, such as Figure 2As shown, the multi-parameter monitoring component 50 includes a gas chromatograph 51 and a spectral sensor 52. The gas chromatograph 51 is connected to the second outlet 413 and is configured to measure the concentration of CO2 and methane components in the produced gas phase to reflect the evolution of fluid components during the displacement process in real time. The spectral sensor 52 is connected to the visualization high-pressure core holder 11 and is configured to monitor the concentration distribution characteristics of CO2, methane and formation water at different locations and times inside the formation reservoir medium 15 in real time, and capture the concentration gradient changes during fluid diffusion and seepage.

[0041] Specifically, a collaborative monitoring mode is adopted using a gas chromatograph 51 and a Raman spectral sensor 52. The gas chromatograph 51 is connected to the gas phase outlet of the gas-liquid separator 41 and has a detection accuracy of ±0.1%. It can accurately determine the concentration of CO2 and methane components in the produced gas phase and reflect the evolution of fluid components in real time during the displacement process. The Raman spectral sensor 52 is implanted through the monitoring interface on the side wall of the reservoir simulation component 10. The detection range covers 0%-100% (mole fraction). It can monitor the concentration distribution characteristics of CO2, methane and formation water at different locations and times inside the reservoir simulation component 10 in real time and accurately capture the concentration gradient changes during fluid diffusion and seepage.

[0042] In one example of the present invention, the multi-parameter monitoring component 50 further includes: a nuclear magnetic resonance imaging module 53 and a micro / nano piezoresistive sensing array 54. The nuclear magnetic resonance imaging module 53 is arranged along the circumferential direction of the visualization high-pressure core holder 11 and is configured to monitor the flow velocity distribution of fluids inside the reservoir, while characterizing the phase saturation distribution of CO2, methane and formation water. The micro / nano piezoresistive sensing array 54 is disposed within the formation reservoir medium 15 and is configured to capture pore pressure fluctuations during fluid seepage to reflect the characteristics of fluid flow velocity changes.

[0043] Specifically, the nuclear magnetic resonance imaging module 53 and the micro / nano piezoresistive sensing array 54 are connected to the data acquisition card 81, and the nuclear magnetic resonance (NMR) imaging module and the micro / nano piezoresistive sensing array 54 are used for collaborative monitoring. The nuclear magnetic resonance imaging module 53 surrounds the outside of the reservoir simulation component 10. Utilizing the NMR transverse relaxation time (T2) distribution characteristics, it can monitor the flow velocity distribution of fluids inside the reservoir in real time (detection accuracy ±0.01mm / s), and accurately characterize the phase saturation distribution of CO2, methane, and formation water (detection accuracy ±0.5%). Combined with the NMR amplitude changes, the conversion law of adsorbed and free methane can be further analyzed, and the fluid transport characteristics during diffusion and seepage can be clearly distinguished. The micro / nano piezoresistive sensing array 54 is embedded inside the reservoir simulation medium, with a sampling frequency of 1kHz, which can accurately capture the pore pressure fluctuations during fluid seepage and indirectly reflect the fluid flow velocity change characteristics.

[0044] In one example of the present invention, the multi-parameter monitoring component 50 further includes: a distributed optical fiber pressure sensor 55 and a temperature sensor 56. The distributed optical fiber pressure sensor 55 is arranged along the axial and radial directions of the visualized high-pressure core holder 11 and is configured to monitor the spatiotemporal evolution characteristics of pore pressure at different locations inside the formation reservoir medium 15. The temperature sensor 56 is installed inside the visualized high-pressure core holder 11 and inside the intermediate container 24 and the constant temperature chamber 31, respectively, and is configured to realize synchronous monitoring of the temperature in each key area during the displacement process, ensure the stability of temperature parameters, and avoid interference of temperature fluctuations on the monitoring results.

[0045] The distributed fiber optic pressure sensor 55 and temperature sensor 56 are connected to the data acquisition card 81. The distributed fiber optic pressure sensor 55 is uniformly distributed along the axial and radial directions of the reservoir simulation component 10, with a measurement range of 0MPa-50MPa and an accuracy of ±0.01MPa. It can monitor the spatiotemporal evolution characteristics of pore pressure at different locations inside the reservoir in real time. The temperature sensor 56 is installed at the input end 12, the middle, the output end 13, the intermediate container 24, and the constant temperature chamber 31 of the reservoir simulation component 10, respectively. It has a measurement range of 0-100℃ and an accuracy of ±0.1℃. It realizes synchronous monitoring of the temperature in each key area during the displacement process, ensures the stability of temperature parameters, and avoids the interference of temperature fluctuations on the monitoring results.

[0046] In one example of the present invention, the diffusion-permeability conversion monitoring component 60 includes a pressure difference sensor 61 and a concentration gradient sensor 62. The pressure difference sensor 61 is installed between the input end 12 and the output end 13 of the reservoir simulation component 10, and is configured to monitor the dynamic changes of fluid pressure difference in real time. The concentration gradient sensor 62 is arranged along the axial direction of the inner surface of the visualization high-pressure core holder 11 and is configured to measure the fluid concentration gradient at different locations inside the formation reservoir medium 15 and capture the abrupt change characteristics of the concentration gradient.

[0047] In short, the pressure difference sensor 61 can monitor the dynamic changes of fluid pressure difference in real time; the concentration gradient sensor 62 and the Raman spectral sensor 52 work together to accurately measure the fluid concentration gradient at different locations inside the reservoir simulation component 10, capture the abrupt change characteristics of the concentration gradient, and provide signal support for the identification of the conversion critical point.

[0048] Preferably, the diffusion-percolation conversion monitoring component 60 further includes: a signal amplifier 63 and a threshold identification module 64 connected thereto; the signal amplifier 63 is connected to the pressure difference sensor 61 and the concentration gradient sensor 62 respectively, and is used to amplify the monitoring signals of pressure difference and concentration gradient, effectively reduce environmental noise interference, and improve signal identification accuracy; the threshold identification module 64 presets the pressure difference threshold and concentration gradient threshold range for diffusion-percolation conversion, and by comparing the monitoring signal with the preset threshold in real time, combined with the flow rate monitoring data, when the pressure difference and concentration gradient reach the preset threshold and the fluid flow rate changes significantly, it automatically determines that it is the critical point of fluid diffusion-percolation conversion, and synchronously records the critical parameters such as pressure, concentration gradient, and temperature at the conversion time, so as to achieve accurate capture and system characterization of conversion conditions.

[0049] In one example of the present invention, such as Figure 3 As shown, the visualization and quantification component 70 includes: an industrial process tomography imaging module 71 and a high-definition high-speed camera module 72. The industrial process tomography imaging module 71 is configured to realize three-dimensional visualization imaging of the displacement front 16 inside the reservoir simulation component 10, clearly presenting the spatial morphology and distribution characteristics of the front, capturing the dynamic changes of the front in real time, and adapting to the high-pressure multiphase flow experimental environment. The high-definition high-speed camera module 72 is set close to the visualization high-pressure core holder 11 and is configured to record the dynamic advancement process of the displacement front 16 in real time, realizing intuitive visualization observation of the front morphology.

[0050] Specifically, the industrial process tomography module 71 and the high-definition high-speed camera module 72 work together. The industrial process tomography module 71 consists of an X-ray computed tomography (CT) module and a capacitance tomography (ECT) module. The X-ray computed tomography module can realize three-dimensional visualization imaging of the displacement front 16 inside the reservoir simulation component 10, clearly presenting the spatial morphology and distribution characteristics of the front. It overcomes the defect of small gas X-ray attenuation coefficient through signal enhancement processing and reduces the signal-to-noise ratio. The capacitance tomography module is used to capture the dynamic changes of the front in real time and is adapted to the high-pressure multiphase flow experimental environment. The high-definition high-speed camera module 72 is aligned with the visualization high-pressure core holder 11, and the shooting frequency can be adjusted in the range of 10 frames / second to 100 frames / second to record the dynamic advancement process of the displacement front 16 in real time and realize intuitive visualization observation of the front morphology.

[0051] In one example of the present invention, the visualization and quantization component 70 further includes an image acquisition card 73 and a quantization analysis module 74. The image acquisition card 73 is used to simultaneously acquire industrial process tomography data and high-definition camera images from the industrial process tomography module 71 and the high-definition high-speed camera module 72. The quantization analysis module 74 is configured to perform precise processing on the displacement leading edge 16 image, extract leading edge feature parameters, and achieve quantization characterization.

[0052] Specifically, the industrial process tomography module 71 is connected to the high-definition high-speed camera module 72 and the image acquisition card 73, and the quantitative analysis module 74 is connected to the image acquisition card 73. The image acquisition card 73 is used to simultaneously acquire industrial process tomography imaging data and high-definition camera images, and quickly transmit them to the quantitative analysis module 74. The quantitative analysis module 74 uses advanced algorithms such as image segmentation and edge detection to accurately process the image of the displacement leading edge 16, extract the leading edge feature parameters and realize quantitative characterization. The core quantitative parameters include: leading edge position coordinates (accuracy ±0.1mm), leading edge thickness (accuracy ±0.01mm), leading edge advance speed (accuracy ±0.01mm / s), leading edge morphological non-uniformity coefficient (value range 0-1, the closer to 0, the smoother the leading edge), and leading edge coverage area ratio (reflecting the leading edge advance range). At the same time, combined with component concentration monitoring data, the correlation between the leading edge position, morphology and fluid concentration is established to realize accurate quantitative characterization of the displacement leading edge 16.

[0053] In one example of the present invention, the data acquisition and processing component 80 includes: a data acquisition card 81, a data processor 82, and a display terminal 83. The data acquisition card 81 is configured to acquire parameter data and image data of the multi-parameter monitoring component 50, the diffusion-percolation conversion monitoring component 60, and the visualization and quantification component 70. The data processor 82 is configured to preprocess the acquired raw data and perform correlation analysis between the image data and the parameter data. The display terminal 83 is configured to display various monitoring data, leading-edge visualization images, and data analysis results in real time.

[0054] Specifically, the data acquisition card 81 is connected to the multi-parameter monitoring component 50, the diffusion-percolation conversion monitoring component 60, and the visualization and quantification component 70 via signal lines, enabling synchronous acquisition of various monitoring parameter data and image data. The acquisition frequency can be flexibly adjusted within the range of 1Hz-100Hz to ensure the timeliness and completeness of data acquisition. The data processor 82 has built-in dedicated data processing software that can perform preprocessing such as noise reduction, calibration, and integration on the acquired raw data, perform correlation analysis between image data and parameter data, and automatically generate displacement process parameter evolution curves, frontal morphology quantification curves, and diffusion-percolation conversion critical parameter reports, realizing systematic data analysis and organization. The display terminal 83 uses a high-definition display that can display various monitoring data, frontal visualization images, and data analysis results in real time. It also supports data export and historical data query functions, facilitating subsequent analysis, organization, and archiving of experimental data by experimental personnel.

[0055] According to a second aspect of the present invention, a monitoring method for a multiphase, multicomponent fluid transport monitoring system 100 for displaced coal as described above includes the following steps: S10: Equipment commissioning and preliminary preparation: First, check the sealing of the equipment connections and conduct an airtightness test. Adjust the constant temperature chamber 31 to the preset formation temperature for the experiment. Start the environmental control component 30 and adjust it to the preset displacement pressure range. Perform precise calibration on the multi-parameter monitoring component 50, the diffusion-seepage conversion monitoring component 60, and the visualization and quantification component 70 to ensure that the monitoring accuracy meets the experimental requirements. S20: Initial State Stabilization and Baseline Data Recording: Start the methane cylinder 22, and adjust the methane injection pressure and flow rate through the pressure regulator 26 and flow meter 27 of the fluid supply component 20 to inject methane into the reservoir simulation component 10 until the formation reservoir medium 15 reaches the methane adsorption saturation state; during this process, start the multi-parameter monitoring component 50 to simultaneously monitor the pore pressure, temperature, and methane saturation inside the reservoir. When each parameter remains stable and continues for more than the preset time, record the parameter data at this time as experimental baseline data to provide a reference for subsequent displacement process parameter comparison; S30: Displacement Process Initiation and Multi-Parameter Synchronous Monitoring: Methane cylinder 22 is closed, and the premixed multiphase, multi-component fluid in intermediate container 24 is injected into reservoir simulation component 10 at the preset pressure and flow rate via high-pressure booster pump 32, initiating the CO2 displacement of methane experimental process. Simultaneously, multi-parameter monitoring component 50, diffusion-permeation conversion monitoring component 60, visualization and quantification component 70, and data acquisition and processing component 80 are activated to achieve synchronous monitoring throughout the entire process. Specifically, multi-parameter monitoring component 50 monitors fluid component concentration, flow rate, saturation, pore pressure, and temperature in real time; diffusion-permeation conversion monitoring component 60 captures pressure difference and concentration gradient changes in real time; visualization and quantification component 70 observes and quantifies the front position and morphology in real time; and data acquisition and processing component 80 synchronously acquires, transmits, stores, and analyzes various types of data in real time. S40: Diffusion-Permeation Transition Condition Capture and Recording: During the experiment, the diffusion-permeation transition monitoring component 60 continuously monitors the dynamic changes of fluid pressure difference and concentration gradient inside the reservoir simulation component 10, and compares the monitoring signals with preset thresholds in real time; when the pressure difference and concentration gradient reach the preset thresholds, and the fluid velocity change exceeds the preset range, it is determined to be the diffusion-permeation transition critical point, and the critical parameters of pressure, concentration gradient, and temperature at the transition time are recorded simultaneously to complete the capture and characterization of diffusion-permeation transition conditions; S50: Visual observation and quantitative characterization of the displacement leading edge 16: During the displacement process, the visualization and quantification component 70 works continuously to capture the position migration, morphological evolution and dynamic advancement process of the displacement leading edge 16 in real time. The image processing algorithm continuously extracts the quantitative parameters of the leading edge position coordinates, thickness and advancement speed from the collected imaging data and camera images, updates the quantitative curve of the leading edge morphology, and establishes the correlation between the leading edge features and fluid transport parameters, so as to realize the full-process visual observation and accurate quantitative characterization of the displacement leading edge 16. S60: Experiment End and Data Processing: When the displacement process reaches the preset experimental termination conditions, stop the operation of the high-pressure booster pump 32, shut down the fluid supply component 20, the environmental control component 30 and all monitoring components, and end the displacement experiment; start the fluid recovery component 40 to recover the separated gas and liquid phases, the gas phase is purified and reused, and the liquid phase is circulated to the formation water storage tank 23; integrate and analyze the monitoring data and image data of the entire experimental process through the data acquisition and processing component 80 to generate a standardized experimental report; export and archive the experimental data to complete the entire experimental operation process.

[0056] The monitoring method features a complete and comprehensive set of equipment, enabling simultaneous monitoring and characterization of multiple parameters. It integrates various advanced monitoring technologies and can simultaneously monitor multiple core parameters such as fluid component concentration, flow rate, and saturation, covering the entire diffusion and seepage process. It comprehensively reflects the transport laws of multiphase and multicomponent fluids and solves the problem of single monitoring parameters in existing equipment.

[0057] Specifically, Step 1: Equipment Debugging and Preliminary Preparation: First, check the sealing performance of each system connection, focusing on the high-pressure pipeline, sealing component 14, and monitoring interface to avoid fluid leakage during the experiment; fill the reservoir simulation component 10 with a reservoir simulation medium (such as coal rock or shale core) of a preset specification, ensuring that the medium is uniform and dense during the filling process to avoid voids; conduct an airtightness test on the entire equipment, setting the test pressure to 1.2 times the preset maximum test pressure, and only proceed to subsequent operations after maintaining the pressure for 2 hours without leakage; CO2 and methane are injected into their respective gas cylinders, and simulated formation water is injected into the formation water storage tank 23. CO2, methane, and formation water are premixed through the intermediate container 24. The stirring device 25 in the intermediate container 24 is started and stirred for 30 minutes to ensure uniform mixing of the fluids. The constant temperature chamber 31 is adjusted to the preset formation temperature, and the pressure control system is started and adjusted to the preset displacement pressure range. Each monitoring sensor, gas chromatograph 51, nuclear magnetic resonance imaging module 53, and industrial process tomography imaging module 71 are precisely calibrated to ensure that the monitoring accuracy meets the experimental requirements. Step 2: Initial State Stabilization and Baseline Data Recording: Start the methane cylinder 22, and adjust the methane injection pressure and flow rate through the pressure regulator 26 and flow meter 27 to inject methane into the reservoir simulation component 10 until the reservoir simulation medium reaches methane adsorption saturation. During this process, start the multi-parameter monitoring component 50 to simultaneously monitor parameters such as pore pressure, temperature, and methane saturation inside the reservoir. When each parameter remains stable (fluctuation range ≤ ±0.05%) for more than 30 minutes, record the parameter data at this time as experimental baseline data to provide a reference for parameter comparison in the subsequent displacement process. Step 3: Displacement Process Initiation and Multi-Parameter Synchronous Monitoring: Methane cylinder 22 is closed, and the displacement system is started. The pre-mixed multiphase, multi-component fluid (containing CO2) in intermediate container 24 is injected into reservoir simulation component 10 at the preset pressure and flow rate via high-pressure booster pump 32, officially initiating the CO2 displacement of methane experimental process. Simultaneously, multi-parameter monitoring component 50, diffusion-permeation conversion monitoring component 60, the displacement front 16 visualization and quantitative characterization system, and the data acquisition and processing system are activated to achieve synchronous operation throughout the entire process: multi-parameter monitoring component 50 monitors fluid component concentration, flow rate, saturation, pore pressure, temperature, and other parameters in real time; diffusion-permeation conversion monitoring component 60 captures pressure difference and concentration gradient changes in real time; the displacement front 16 visualization and quantitative characterization system observes and quantifies the front position and morphology in real time; and the data acquisition and processing system synchronously collects, transmits, stores, and analyzes various types of data in real time.Step 4: Capturing and Recording Diffusion-Permeation Transition Conditions: During the experiment, the diffusion-permeation transition monitoring component 60 continuously monitors the dynamic changes in the fluid pressure difference and concentration gradient inside the reservoir simulation component 10. The signal amplifier 63 amplifies the monitoring signal, and the threshold identification module 64 compares the monitoring signal with the preset threshold in real time. When the pressure difference and concentration gradient reach the preset threshold, and the fluid velocity change exceeds the preset range (usually set to 50%), it is automatically determined as the diffusion-permeation transition critical point. The pressure, concentration gradient, temperature, and other critical parameters at the transition time are recorded simultaneously to complete the capture and characterization of diffusion-permeation transition conditions. Step 5: Visual observation and quantitative characterization of the displacement front 16: During the displacement process, the industrial process tomography module 71 and the high-definition high-speed camera module 72 work continuously to capture the position migration, morphological evolution and dynamic advancement process of the displacement front 16 in real time. The image acquisition card 73 transmits the acquired imaging data and camera images to the quantitative analysis module 74 in real time. The quantitative analysis module 74 continuously extracts quantitative parameters such as the position coordinates, thickness and advancement speed of the front through image processing algorithms, updates the quantitative curve of the front morphology, and establishes the correlation between the front characteristics and fluid transport parameters, so as to realize the full-process visual observation and accurate quantitative characterization of the displacement front 16. Step 6: Experiment End and Data Processing: When the displacement process reaches the preset experimental termination condition (usually set as: methane concentration at the outlet is below 0.1%), stop the high-pressure booster pump 32, shut down all fluid sources and monitoring system 100, and end the displacement experiment; start the fluid recovery component 40 to recover the separated gas and liquid phases in the separator. The gas phase is purified and recycled, and the liquid phase is circulated to the formation water storage tank 23; integrate and analyze the monitoring data and image data of the entire experimental process through the data acquisition and processing system to generate a standardized experimental report, including core contents such as multi-parameter evolution law, diffusion-seepage conversion critical parameters, and quantitative characteristics of the displacement front 16; export and archive the experimental data to complete the entire experimental operation process.

[0058] This monitoring method specifically sets up a diffusion-seepage transition monitoring component 60. Through signal capture and threshold identification, it can accurately capture the critical point of diffusion-seepage transition and simultaneously record critical parameters. This fills the technical gap that existing equipment cannot specifically monitor transition conditions and provides reliable data support for the study of displacement mechanisms.

[0059] This monitoring method enables the visualization and quantitative characterization of the displacement leading edge 16. By combining industrial process tomography and high-definition video technology, it overcomes the limitations of traditional indirect inference. The core quantitative parameters of the leading edge are extracted through the quantitative analysis module 74, providing precise guidance for displacement process optimization and displacement range prediction.

[0060] The monitoring method features highly realistic equipment simulation and wide applicability. It allows for flexible adjustment of temperature and pressure parameters, making it suitable for different types of reservoir media and multiphase, multi-component fluid systems. It is applicable to CO2-driven methane displacement experiments of different scales and conditions. The operation method is standardized and the process is clear, facilitating operation by experimental personnel and its widespread application.

[0061] This monitoring method offers efficient and convenient data processing. Through the data acquisition and processing component 80, it enables synchronous data acquisition, analysis, and display, automatically generating experimental reports. This significantly improves the efficiency of experimental data processing, reduces the workload of experimental personnel, and enhances the convenience of experimental research.

[0062] Specific examples: This embodiment provides a multiphase, multi-component fluid transport monitoring system for methane in displaced coal, the specific composition and operation method of which are as follows: 1. Specific composition parameters of the equipment (1) Reservoir simulation component: The reservoir simulation component adopts a sapphire material visualization high-pressure core holder with an inner diameter of 25mm, a length of 100mm, and a maximum pressure of 50MPa. It is filled with coal core (particle size 2mm-5mm, porosity 15%-20%). Six monitoring interfaces are evenly arranged along the axial and radial directions on the side wall. In the fluid supply component, the CO2 gas cylinder and methane gas cylinder are both 99.99% pure. The formation water storage tank is filled with 1% NaCl to simulate formation water. The intermediate container has a volume of 500mL and is equipped with an electromagnetic stirring device (speed 0r / min-500r / min) and a temperature sensor (PT100). In the environmental control component, the constant temperature chamber has a temperature control range of 0℃-100℃ and a temperature control accuracy of ±0.1℃. The high-pressure booster pump has a maximum output pressure of 50MPa and a pressure sensor accuracy of ±0.01MPa. The fluid recovery component adopts a gas-liquid separator and is equipped with two 1000mL recovery tanks. The recovery tanks are equipped with pressure relief valves.

[0063] (2) Multi-parameter monitoring components: The component concentration monitoring unit adopts a GC-9790 gas chromatograph (thermal conductivity detector, detection accuracy ±0.1%) and a Raman-Probe-2000 spectrometer (detection range 0-100% mole fraction); the flow rate and saturation monitoring unit adopts an NMR-20MHz nuclear magnetic resonance imaging module 53 (magnetic field strength 0.5T, flow rate detection accuracy ±0.01mm / s, saturation detection accuracy ±0.5%) and a micro-nano piezoresistive sensor array with a sampling frequency of 1kHz; the pore pressure and temperature monitoring unit adopts a distributed fiber optic pressure sensor (measurement range 0MPa-50MPa, accuracy ±0.01MPa) and a PT100 temperature sensor (accuracy ±0.1℃).

[0064] (3) Diffusion-percolation conversion monitoring component: pressure difference sensor with a measurement range of 0MPa-10MPa and an accuracy of ±0.001MPa; signal amplifier with an amplification factor of 1000 times; threshold recognition module with preset pressure difference threshold of 0.5MPa and concentration gradient threshold of 0.02mol / (cm³). 3 ·mm).

[0065] (4) Visualization and quantification components: The X-ray CT module in the industrial process tomography module 71 has a resolution of 0.1 mm, the ECT module has 16 electrodes, the high-definition high-speed camera module 72 uses a Phantom V2512 high-speed camera (shooting frequency 50 frames / second, resolution 1080P), and the quantification analysis module uses the Canny edge detection algorithm and the region growing segmentation algorithm.

[0066] (5) Data acquisition and processing components: The data acquisition card adopts the NI PCI-6259 model, and the acquisition frequency is adjusted to 10Hz; the data processor adopts an industrial computer with Intel Core i7-12700H, 32GB memory and 1TB hard disk, and installs dedicated data processing software; the display terminal is a 27-inch high-definition monitor, which supports data export in Excel and PDF formats.

[0067] 2. Specific operating procedures Step 1: Equipment debugging and preparation. Check the sealing of each system connection. Fill the reservoir simulation component with coal core and conduct an airtightness test (pressure 30MPa, pressure held for 2 hours without leakage). Inject CO2, methane, and formation water into the intermediate container at a volume ratio of 5:3:2 and stir for 30 minutes to mix evenly. Adjust the constant temperature chamber to 35℃ and adjust the pressure control system to 5MPa-10MPa. Calibrate each monitoring device to ensure monitoring accuracy.

[0068] Step 2: Once the initial state is stable, inject methane (injection pressure 5 MPa) into the reservoir simulation component until the coal core is saturated (methane concentration at the outlet is stable above 99% for 30 minutes). Record the baseline data such as initial pore pressure, temperature, and methane saturation.

[0069] Step 3: Start the displacement experiment. Start the high-pressure booster pump and inject the mixed fluid into the reservoir simulation component at a pressure of 8MPa and a flow rate of 50mL / min. Start each monitoring system and simultaneously monitor multi-parameter data, conversion signals and leading edge morphology.

[0070] Step 4: Condition switching and capture. After 120 minutes of the experiment, a pressure difference of 0.5 MPa and a concentration gradient of 0.02 mol / (cm²) were detected. 3 When the flow rate changes by 55% (·mm), it is determined to be the critical point of transition. At this time, the critical parameters such as pressure 8.2MPa and temperature 35℃ are recorded.

[0071] Step 5: Leading edge quantification characterization. The leading edge morphology is captured by the industrial process tomography module 71 and the high-definition high-speed camera module 72. The initial leading edge distance is 20mm from the inlet end, the propulsion speed is 0.08mm / min, the thickness is 0.8mm, the non-uniformity coefficient is 0.2, and the coverage area is 60%. The leading edge parameters are updated in real time.

[0072] Step 6: Experiment End and Data Processing. The experiment lasted 360 minutes. When the methane concentration at the outlet dropped to 0.08%, the experiment was stopped, and the fluid was recovered. The data was integrated and analyzed using a data processor to generate an experimental report and export the data for archiving. The CO2-driven methane multi-parameter monitoring and characterization device constructed in this embodiment operated stably throughout the process, with good coordination among the systems. The time synchronization error of the monitoring data was ≤0.5s. The monitoring accuracy of core parameters such as pressure, concentration, flow rate, and leading edge position all met the preset design specifications. The relative deviation of parameters in parallel experiments was ≤2%, demonstrating excellent experimental reliability and data repeatability.

[0073] From the perspective of theoretical research and technological application, this device breaks through the core technical bottlenecks of existing CO2-driven methane displacement experimental devices: Firstly, addressing the shortcomings of existing devices in monitoring single parameters and insufficient spatiotemporal resolution, this device achieves in-situ, synchronous, and distributed monitoring of multiple parameters such as component concentration, phase saturation, pore pressure, and transport velocity of multiphase and multi-component fluids throughout the displacement process. It can comprehensively characterize the transport evolution of fluids at different stages of diffusion and seepage, effectively distinguishing the dynamic conversion process of adsorbed and free methane, filling the gap in existing technologies that cannot simultaneously acquire multiple field coupling parameters, and providing comprehensive data source support for revealing the competitive adsorption-transport coupling mechanism of CO2 and methane; Secondly, addressing the core challenge of existing technologies being unable to accurately define the boundaries of the diffusion-seepage process, this device achieves precise capture and quantitative characterization of the critical conditions for fluid diffusion-seepage conversion. In this embodiment, it can... The device accurately identifies critical parameters such as pressure, concentration gradient, and temperature at the critical point of conversion, with a time resolution of 1 second. This provides crucial experimental evidence for clarifying the dominant migration channels for CO2 to displace methane in low-permeability reservoirs and for determining the contribution ratio of diffusion and seepage to displacement efficiency. It can directly serve the optimization design of process parameters such as CO2 injection pressure and flow rate. Thirdly, addressing the limitations of existing technologies that rely on indirect inference of front characteristics from outlet components and cannot achieve quantitative characterization of the front, this device enables visualized observation and high-precision quantitative characterization of the displacement front position and morphology. It can acquire core quantitative parameters such as front thickness, propulsion speed, and non-uniformity coefficient in situ, with a spatial resolution of 0.1 mm. It can accurately characterize the non-uniform propulsion characteristics of the displacement front and establish a quantitative correlation between front morphological evolution and fluid transport parameters, providing direct experimental support for predicting the CO2 displacement range and evaluating the safety of sealed reservoirs.

[0074] In summary, this embodiment fully verifies that the equipment possesses excellent operational stability and data accuracy, comprehensively covering the core experimental requirements of multi-parameter monitoring, diffusion-permeability transition condition capture, and quantitative characterization of the displacement front during CO2 methane displacement. It can provide a reliable indoor experimental platform for the mechanism study, process optimization, and field engineering application of CO2 methane displacement in unconventional reservoirs such as low-permeability coal seams and shale reservoirs, and has both important theoretical research value and engineering guidance significance.

[0075] The foregoing description, with reference to preferred embodiments, details an exemplary implementation of the present invention’s proposed system 100 and method for monitoring the multiphase and multicomponent fluid migration of methane in coal. However, those skilled in the art will understand that various modifications and alterations can be made to the above specific embodiments without departing from the concept of the present invention, and various combinations can be made to the various technical features and structures proposed in the present invention without exceeding the protection scope of the present invention.

Claims

1. A monitoring system for multiphase, multicomponent fluid transport of methane in displaced coal, characterized in that, include: The reservoir simulation component (10) includes: a visualization high-pressure core holder (11), which is filled with formation reservoir medium (15), and the reservoir simulation component (10) has an input end (12) and an output end (13). The fluid supply assembly (20) includes: a CO2 cylinder (21), a methane cylinder (22), a formation water storage tank (23), and an intermediate container (24). The CO2 cylinder (21), the methane cylinder (22), and the formation water storage tank (23) are all connected to the intermediate container (24). The intermediate container (24) is configured to premix CO2, methane, and formation water to simulate a real formation multiphase and multicomponent fluid environment. The CO2 cylinder (21) and the intermediate container (24) are connected to the input end (12). The environmental control component (30) includes: a constant temperature chamber (31), a high-pressure booster pump (32), and a pressure sensor (33). The constant temperature chamber (31) is located outside the reservoir simulation component (10) and is configured to adjust the temperature of the formation reservoir medium (15) to simulate the temperature environment of formations at different depths. The high-pressure booster pump (32) is connected between the intermediate container (24) and the input end (12) and is configured to adjust the displacement pressure of the formation reservoir medium (15) to simulate different formation pressure conditions. The pressure sensor (33) is configured to monitor the internal pressure information of the constant temperature chamber (31). The fluid recovery assembly (40) is connected to the output end (13) and is configured to separate the gas phase and liquid phase produced after displacement. A multi-parameter monitoring component (50) is connected to the fluid recovery component (40) and is configured to monitor fluid component concentration, fluid flow rate, phase saturation, formation reservoir pore pressure and the temperature of the reservoir simulation component (10); A diffusion-permeation conversion monitoring component (60) is connected to the reservoir simulation component (10) and configured to capture fluid-permeation conversion conditions during CO2 displacement of methane and identify critical conversion parameters; The visualization and quantification component (70) is configured to realize the visualization observation of the position and morphology of the displacement front (16) inside the high-pressure core holder (11), and to scientifically quantify the characteristic parameters of the front to obtain the propulsion law of the displacement front (16); The data acquisition and processing component (80) is coupled to the multi-parameter monitoring component (50), the diffusion-seepage conversion monitoring component (60), and the visualization and quantification component (70), and is configured to acquire and process the monitoring data of the multi-parameter monitoring component (50), the diffusion-seepage conversion monitoring component (60), and the visualization and quantification component (70).

2. The monitoring system for multiphase, multicomponent fluid transport of methane in displaced coal according to claim 1, characterized in that, The fluid recovery assembly (40) includes a gas-liquid separator (41) and a recovery tank (42). The gas-liquid separator (41) has at least an inlet end (411), a first outlet end (412), and a second outlet end (413). The inlet end (411) is connected to the output end (13), the first outlet end (412) is connected to the recovery tank (42), and the second outlet end (413) is connected to a multi-parameter monitoring assembly (50). The gas-liquid separator (41) is configured to separate the gas phase and liquid phase produced after displacement. The gas phase flows into the multi-parameter monitoring assembly (50), and the liquid phase is collected in the recovery tank (42).

3. The monitoring system for multiphase, multicomponent fluid transport of methane in displaced coal according to claim 2, characterized in that, The multi-parameter monitoring component (50) includes a gas chromatograph (51) and a spectral sensor (52). The gas chromatograph (51) is connected to the second outlet (413) and is configured to measure the concentration of CO2 and methane components in the produced gas phase to reflect the evolution of fluid components during the displacement process in real time. The spectral sensor (52) is connected to the visualization high-pressure core holder (11) and is configured to monitor the concentration distribution characteristics of CO2, methane and formation water at different locations and times inside the formation reservoir medium (15) in real time, and capture the concentration gradient changes during the fluid diffusion and seepage process.

4. The monitoring system for multiphase, multicomponent fluid transport of methane in displaced coal according to claim 2, characterized in that, The multi-parameter monitoring component (50) further includes: a nuclear magnetic resonance imaging module (53) and a micro-nano piezoresistive sensing array (54). The nuclear magnetic resonance imaging module (53) is set along the circumferential direction of the visualization high-pressure core holder (11) and is configured to monitor the flow velocity distribution of fluids inside the reservoir, while characterizing the phase saturation distribution of CO2, methane and formation water. The micro-nano piezoresistive sensing array (54) is located inside the formation reservoir medium (15) and is configured to capture pore pressure fluctuations during fluid seepage to reflect the characteristics of fluid flow velocity changes.

5. The monitoring system for multiphase, multicomponent fluid transport of methane in displaced coal according to claim 2, characterized in that, The multi-parameter monitoring component (50) further includes a distributed optical fiber pressure sensor (55) and a temperature sensor (56). The distributed optical fiber pressure sensor (55) is arranged along the axial and radial directions of the visualized high-pressure core holder (11) and is configured to monitor the spatiotemporal evolution characteristics of pore pressure at different locations inside the formation reservoir medium (15). The temperature sensor (56) is installed inside the visualized high-pressure core holder (11) and inside the intermediate container (24) and the constant temperature chamber (31) respectively. It is configured to realize the synchronous monitoring of the temperature of each key area during the displacement process, ensure the stability of temperature parameters, and avoid the interference of temperature fluctuations on the monitoring results.

6. The monitoring system for multiphase, multicomponent fluid transport of methane in displaced coal according to claim 1, characterized in that, The diffusion-seepage conversion monitoring component (60) includes a pressure difference sensor (61) and a concentration gradient sensor (62). The pressure difference sensor (61) is installed between the input end (12) and the output end (13) of the reservoir simulation component (10) and is configured to monitor the dynamic changes of fluid pressure difference in real time. The concentration gradient sensor (62) is arranged along the axial direction of the inner surface of the visualization high-pressure core holder (11) and is configured to measure the fluid concentration gradient at different locations inside the formation reservoir medium (15) and capture the abrupt change characteristics of the concentration gradient.

7. The monitoring system for multiphase, multicomponent fluid transport of methane in displaced coal according to claim 1, characterized in that, The visualization and quantification component (70) includes an industrial process tomography module (71) and a high-definition high-speed camera module (72). The industrial process tomography module (71) is configured to realize three-dimensional visualization imaging of the displacement front (16) inside the reservoir simulation component (10), clearly presenting the spatial morphology and distribution characteristics of the front, capturing the dynamic changes of the front in real time, and adapting to the high-pressure multiphase flow experimental environment. The high-definition high-speed camera module (72) is set close to the visualization high-pressure core holder (11) and is configured to record the dynamic advancement process of the displacement front (16) in real time, realizing intuitive visualization observation of the front morphology.

8. The monitoring system for multiphase, multicomponent fluid transport of methane in displaced coal according to claim 7, characterized in that, The visualization and quantization component (70) also includes an image acquisition card (73) and a quantization analysis module (74). The image acquisition card (73) is used to simultaneously acquire industrial process tomography data and high-definition camera images from the industrial process tomography module (71) and the high-definition high-speed camera module (72). The quantization analysis module (74) is configured to perform precise processing on the displacement leading edge (16) image, extract leading edge feature parameters, and realize quantization characterization.

9. The monitoring system for multiphase, multicomponent fluid transport of methane in displaced coal according to claim 1, characterized in that, The data acquisition and processing component (80) includes: a data acquisition card (81), a data processor (82), and a display terminal (83). The data acquisition card (81) is configured to acquire parameter data and image data of the multi-parameter monitoring component (50), the diffusion-percolation conversion monitoring component (60), and the visualization and quantification component (70). The data processor (82) is configured to preprocess the acquired raw data and perform correlation analysis between the image data and the parameter data. The display terminal (83) is configured to display various monitoring data, leading-edge visualization images, and data analysis results in real time.

10. A monitoring method for a multiphase, multicomponent fluid transport monitoring system for methane in displaced coal as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S10: Equipment debugging and preliminary preparation: First, check the sealing of the equipment connection and conduct an airtightness test. Adjust the constant temperature chamber (31) to the preset formation temperature for the experiment, start the environmental control component (30), and adjust it to the preset displacement pressure range. Accurately calibrate the multi-parameter monitoring component (50), diffusion-seepage conversion monitoring component (60), and visualization and quantification component (70) to ensure that the monitoring accuracy meets the experimental requirements. S20: Initial State Stabilization and Baseline Data Recording: Start the methane cylinder (22), adjust the methane injection pressure and flow rate through the fluid supply component (20), and inject methane into the reservoir simulation component (10) until the formation reservoir medium (15) reaches the methane adsorption saturation state; during this process, start the multi-parameter monitoring component (50) to simultaneously monitor the pore pressure, temperature and methane saturation inside the reservoir. When each parameter remains stable and continues for more than the preset time, record the parameter data at this time as experimental baseline data to provide a reference for subsequent displacement process parameter comparison; S30: Displacement process start-up and multi-parameter synchronous monitoring: The methane cylinder (22) is closed, and the premixed multiphase multi-component fluid in the intermediate container (24) is injected into the reservoir simulation component (10) at the preset pressure and flow rate through the high-pressure booster pump (32) to start the CO2 displacement of methane experimental process; at the same time, the multi-parameter monitoring component (50), diffusion-permeation conversion monitoring component (60), visualization and quantification component (70) and data acquisition and processing component (80) are started to achieve synchronous monitoring of the whole process. Among them, the multi-parameter monitoring component (50) monitors the fluid component concentration, flow rate, saturation, pore pressure and temperature in real time; the diffusion-permeation conversion monitoring component (60) captures the pressure difference and concentration gradient changes in real time; the visualization and quantification component (70) observes the front position and morphology in real time and performs quantification; the data acquisition and processing component (80) synchronously collects, transmits and stores various types of data and performs real-time analysis. S40: Diffusion-permeability transition condition capture and recording: During the experiment, the diffusion-permeability transition monitoring component (60) continuously monitors the dynamic changes of fluid pressure difference and concentration gradient inside the reservoir simulation component (10), and compares the monitoring signal with the preset threshold in real time; when the pressure difference and concentration gradient reach the preset threshold and the fluid velocity change exceeds the preset range, it is determined to be the diffusion-permeability transition critical point, and the critical parameters of pressure, concentration gradient and temperature at the transition time are recorded simultaneously to complete the capture and characterization of diffusion-permeability transition conditions; S50: Visual observation and quantitative characterization of the displacement front (16): During the displacement process, the visualization and quantification components (70) work continuously to capture the position migration, morphological evolution and dynamic propulsion process of the displacement front (16) in real time. The collected imaging data and camera images are processed by image processing algorithms to continuously extract the quantitative parameters of the front position coordinates, thickness and propulsion speed, update the morphological quantification curve of the front, establish the correlation between the front features and fluid transport parameters, and realize the full-process visual observation and precise quantitative characterization of the displacement front (16). S60: Experiment End and Data Processing: When the displacement process reaches the preset experimental termination conditions, stop the operation of the high-pressure booster pump (32), shut down the fluid supply component (20), environmental control component (30) and each monitoring component, and end the displacement experiment; start the fluid recovery component (40) to recover the separated gas phase and liquid phase, the gas phase is purified and recycled, and the liquid phase is circulated to the formation water storage tank (23); integrate and analyze the monitoring data and image data of the entire experimental process through the data acquisition and processing component (80) to generate a standardized experimental report; export and archive the experimental data to complete the entire experimental operation process.

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