A flue gas thermal fracturing-displacement-sequestration isotope tracing monitoring device and method

Abstract

This invention discloses an isotope tracing monitoring device and method for flue gas thermal fracturing-displacement-sealage, belonging to the field of isotope tracing technology. It includes multiple combined extraction and monitoring wells and multiple L-shaped injection wells. The vertical portion of each injection well and the combined extraction and monitoring wells penetrate the rock strata from top to bottom and extend into the coal seam, while the horizontal portion of the injection wells is within the coal seam. This invention utilizes separate injection... 13 CO2, 15 NO2 34 SO2, acting as a "fingerprint marker," combined with online isotope ratio analysis, enables independent, in-situ, and simultaneous tracking of key pollutant components in flue gas. Based on an isotope mass balance model, the real-time retention rate and cumulative sequestration amount of CO2, SO2, and NO2 can be calculated separately and quantitatively. This overcomes the limitations of traditional technologies that can only assess the overall sequestration effect, providing a revolutionary means for accurately assessing the sequestration safety and environmental risks of different pollutants.

Description

Technical Field

[0001] This invention relates to the field of isotope tracing technology, specifically to an isotope tracing monitoring device and method for flue gas thermal fracturing-displacement-sealing. Background Technology

[0002] Industrial flue gas (mainly composed of CO2, N2 and small amounts of SO2 and NO) x Direct emissions of CO2-rich industrial flue gas (such as coal seams, oil and gas reservoirs, and coal seams) would cause enormous environmental pollution. Against this backdrop, permanently storing CO2-rich industrial flue gas in deep saline aquifers, depleted oil and gas reservoirs, or low-permeability coal seams is considered a key technological approach to achieve large-scale carbon reduction. However, the large-scale and commercial application of this technology has always been limited by the high complexity of the process and the serious lag of traditional monitoring methods.

[0003] This complexity stems primarily from the strong nonlinear coupling of multiple components and physicochemical fields throughout the injection-displacement-storage process. When industrial flue gas migrates through the complex fracture network formed by thermal fracturing, each component undergoes complex processes such as competitive adsorption, dissolution, mineralization, and possible chemical reactions, resulting in varying migration paths, retention efficiencies, and storage effects. Traditional engineering practices and monitoring models treat flue gas as a homogeneous mixture for overall treatment, neglecting the differentiated storage behavior and risk characteristics of different pollutants. This leads to an inability to accurately assess the independent storage efficiency and potential environmental risks of each component (especially SO2 and NO2, which require key control).

[0004] Furthermore, existing technologies are severely inadequate in sensing the underground storage status, relying primarily on limited wellhead pressure monitoring and periodic, costly geophysical exploration. This point-based, intermittent monitoring method leaves the entire storage system operating in a near-black box state, making it difficult to capture the migration fronts of different gas components in real time and in situ, accurately characterize their spatial distribution, and independently quantify the real-time storage efficiency of key components such as CO2, SO2, and NO2. Current safety warnings largely rely on lagging concentration threshold alarms, lacking a technical means to identify early, forward-looking leakage risks based on the dynamic decay trend of storage efficiency. Although isotope tracing technology has the advantage of identifying the "fingerprint" of gases from different sources, in complex geological storage projects, there is still a lack of a complete technical system integrating precise injection of stable isotope markers, simultaneous sampling at multiple well locations, online rapid analysis, and intelligent retention rate calculation and early warning based on mass balance.

[0005] To overcome the aforementioned bottlenecks and achieve a transformation in the entire process of industrial flue gas geological storage—from "black box speculation" to "transparent monitoring," from "overall assessment" to "component analysis," and from "post-event alarm" to "early warning"—an innovative monitoring method is urgently needed. This invention aims to propose a monitoring device and method based on multi-isotope tracing, deeply integrating stable isotope labeling, multi-well collaborative sampling, online isotope analysis, and intelligent data processing models. This provides key technical support for achieving safe and efficient geological storage of industrial flue gas. Summary of the Invention

[0006] To address or partially address the problems existing in related technologies, this invention provides a flue gas thermal fracturing-displacement-storage isotope tracer monitoring device and method. This device and method can achieve full-process, multi-component, and quantitative monitoring, providing an effective means for safety evaluation of industrial flue gas geological storage.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: a flue gas thermal fracturing-displacement-storage isotope tracer monitoring device is provided, the innovation of which is: it includes multiple extraction and monitoring combined wells and multiple L-shaped injection wells, the vertical part of each injection well and the extraction and monitoring combined well both penetrate the rock strata from top to bottom and extend to the coal seam, and the horizontal part of the injection well is inside the coal seam; It also includes an isotope injection module, a sampling system, an isotope analyzer, a data processing and retention rate calculation module, and a ground control center; the output end of the isotope injection module extends from the ground into each injection well and downwards into the coal seam through multiple gas injection pipes; the input end of each sampling system extends from the ground into each combined extraction and monitoring well and downwards into the coal seam through multiple extraction pipes. The output terminals of the sampling system and the isotope injection module are both connected to the isotope analyzer via gas tubes to analyze the values ​​of the injected or sampled gases in real time. The isotope analyzer is also connected to the data processing and retention rate calculation module, which receives the gas values ​​and calculates the instantaneous retention rate and cumulative sequestration of each gas in the formation. The ground control center is connected to both the isotope injection module and the data processing and retention rate calculation module to coordinate and control the entire monitoring process.

[0008] Preferably, the injection well is equipped with a gas injection plug at the position corresponding to the top of the coal seam, and the extraction monitoring well is equipped with an extraction plug at the position corresponding to the top of the coal seam.

[0009] Preferably, the isotope injection module includes a hot flue gas storage tank, an isotope storage tank, a static mixer, a variable frequency gas injection pump, a humidity control and dust removal system, and a heat exchanger group, which are connected in sequence through gas pipes. The hot flue gas storage tank is also connected to the ground control center via a communication cable. The ground control center can remotely monitor the pressure, temperature, and remaining gas volume of the hot flue gas storage tank, and control its gas supply valve to achieve automated adjustment and safety monitoring of the injection process. The isotope storage tank is equipped with a mass flow controller (MFC) on the gas pipes that connect the hot flue gas storage tank and the static mixer, respectively. The heat exchanger assembly is connected to multiple gas injection pipes, and each gas injection pipe is also connected to an isotope analyzer via a gas pipe; each gas injection pipe extends downward through a gas injection plugger in its corresponding injection well. It also includes an injection data transmission line, one end of which extends downward through the gas injection plugger inside the injection well and is connected to an injection data acquisition device at the other end; the other end is connected to a data processing and retention rate calculation module; the data acquisition device is located at the lower end of the gas injection pipeline.

[0010] Preferably, the control accuracy of the mass flow controller (MFC) is within 0.5% FS; the static mixer is a Kenics-type spiral static mixer with an aspect ratio (L / D) of not less than 15 and a mixing non-uniformity of less than 2%.

[0011] Preferably, the sampling system includes a downhole gas sampling pump, a gas-liquid separator, a drying and filtering unit, and an inert-coated sample buffer container, which are connected in sequence via gas pipes; It also includes multiple extraction monitoring and data transmission lines. One end of the extraction pipeline and the extraction monitoring and data transmission line both extend downward through the extraction plug in the extraction monitoring well. The other end of the extraction pipeline extends upward to connect to the downhole gas sampling pump. The lower end of the extraction monitoring and data transmission line is connected to an extraction monitoring data acquisition device, and the upper end is connected to a data processing and retention rate calculation module. The extraction monitoring data acquisition device is located at the lower end of the extraction pipeline.

[0012] Preferably, the ground control center includes a map module for displaying the well location, real-time status, and real-time retention rate curves of carbon, nitrogen, and sulfur elements for each injection well and extraction monitoring joint well. When the isotope δ value of the extraction monitoring joint well rises abnormally, a leakage warning is issued, and an annual retention rate ≥95% is considered safe for sealing.

[0013] Preferably, the isotope analyzer is a mass spectrometer or a laser spectrometer; when a mass spectrometer is used, it is a continuous-flow isotope ratio mass spectrometer, which is effective for δ¹⁸O⁻ ... 13 The analytical precision error of C is within 0.1‰, for δ 15 The analytical precision error of N is within 0.2‰, and for δ 34 The analytical precision error of S is within 0.3‰.

[0014] This invention also provides a flue gas thermal fracturing-displacement-sealage isotope tracing monitoring method based on the above-mentioned device, the innovation of which lies in the following steps: Step 1: Before the industrial flue gas injection begins, continuous background value monitoring is conducted using the combined extraction and monitoring well to establish a background isotope database, i.e., the isotope ratios of the formation background gas. isotope ratio The results were obtained by analyzing the background gas sampled using an isotope analyzer. Step 2 Step 21: Injection is carried out through one or more injection wells. Specifically, industrial flue gas is output from the hot flue gas storage tank and enters the isotope storage tank. After the flow rate of the stable isotope markers in the isotope storage tank is controlled by a precision mass flow controller, the gas is then fed into a static mixer for uniform mixing. Stable isotope markers include 13 CO2, 15 NO2 and 34 SO2; The injection ratio of stable isotope markers is such that the δ0 of the flue gas after injection into the coal seam is increased. 13 The C value is -5‰ to -10‰ relative to the PDB standard, δ 15 The N value is +50‰ to +80‰ relative to the AIR standard, δ 34 The S value is +10‰ to +20‰ relative to the V-CDT standard; Step 22: The mixed gas is pressurized by a variable frequency gas injection pump, then enters the humidification and dust removal system for treatment, and finally enters the heat exchanger group for temperature adjustment. A small portion of the temperature-adjusted flue gas enters the isotope analyzer through a gas pipe to obtain the isotope ratio of the injected flue gas. The data is then transmitted to the data processing and retention rate calculation module, with most of it injected into the coal seam via gas injection pipelines. During this process, the injection data acquisition device will collect the real-time concentrations of each component ξ at the injection end of the gas injection pipeline. and real-time traffic injection The data is fed to the data processing and retention rate calculation module, where ξ represents CO2 / NO2 / SO2. Step 3: After isotope injection is completed and 24-72 hours of operation has passed, timed, quantitative, and multi-point synchronous sampling is conducted using a sampling system and multiple extraction monitoring wells. The sampling process includes extracting downhole gas using a downhole gas sampling pump, removing liquid through a gas-liquid separator, removing moisture and particulate matter through a drying and filtration unit, and finally transporting it through pipelines to an inert-coated sample buffer tank. The extraction monitoring data acquisition device collects the real-time flow rate of the extracted gas. and the real-time concentration of each component ξ The data is transmitted to the data processing and retention rate calculation module. When multiple sampling systems perform multi-point synchronous sampling through corresponding extraction and monitoring joint wells, the start-up time of each gas sampling pump is staggered. That is, each sampling system adopts asynchronous triggering timing control, and the sampling time points of each extraction and monitoring joint well are set at intervals to avoid interference between wells. Step 4: The inert-coated sample buffer container of the sampling system is connected to the isotope analyzer via a gas pipe. The analyzer performs real-time analysis on the collected gas samples. When using a mass spectrometer, the analysis cycle should not exceed 15 minutes; when using a laser spectrometer, the time resolution should not be less than 1 Hz. The isotope ratio of the gas sampled from the combined well for extraction and monitoring is obtained through the isotope analyzer. The calculated values ​​are output to the data processing and retention rate calculation module, which calculates the mole fraction of the injected gas in the produced gas. The calculation formula is: in, The isotope ratios are measured from gas samples taken from the combined well for extraction and monitoring. The isotope ratio of the injected flue gas. The isotope ratio of the background gas in the formation; Step 5: The data processing and retention rate calculation module calculates the instantaneous retention rate and cumulative sequestration of CO2, NO2, and SO2 in the formation based on the received injection flow rate, sampling flow rate, concentration of each component in the gas during injection and sampling, and mole fraction of the injected gas in the produced gas, and using an isotope mass balance model. It also calculates the instantaneous retention rate of each component based on the isotope mass balance model. The calculation formula is: Where ξ represents CO2, NO2, or SO2. and These are the production flow rate of the combined extraction monitoring well and the injection flow rate of the injection well. and These represent the concentrations of component ξ in the combined extraction and monitoring wells and the injection well, respectively.

[0015] The cumulative time from the start of injection to the arrival of the gas in the inert coating sample buffer container Total retention rate The calculation formula is: In the data processing and retention rate calculation module, component ξ is calculated from the start of injection to time. Cumulative amount of sealed and total seizure rate The calculation formula is: Step 6: The data processing and retention rate calculation module transmits all data to the ground control center, which receives the instantaneous retention rates of each component calculated by the data processing and calculation module. Cumulative amount sealed Total seizure rate The ground control center performs a moving average on the calculated instantaneous retention rate to obtain a trend line. Based on the error propagation theory, it assesses the uncertainty of the retention rate value, determines the confidence interval, compares the instantaneous retention rate value with a preset threshold, outputs the real-time retention rate curve and leakage early warning information, determines whether an early warning is triggered, and outputs the early warning level, trigger time, well location information and suggested measures when an early warning is triggered. Preferably, in step 6, when the instantaneous retention rate and total retention rate are lower than the preset threshold or the rate of decrease exceeds the limit, a leakage warning is automatically generated and issued, and control instructions are simultaneously output to the hot flue gas storage tank to adjust the injection parameters. The ground control center also integrates and visualizes the information, and uses spatial interpolation to reconstruct the spatial distribution of the retention rate in the entire formation for the instantaneous retention rate and the cumulative storage volume. It outputs a spatial contour map of the retention rate and a thermal map of the spatial distribution of the storage volume, displays the warning color and the change curve of the multi-component instantaneous retention rate in real time, and forms a structured monitoring report.

[0016] Preferably, the early warning judgment is based on three indicators: Indicator A: Instantaneous Detention Rate absolute level green: >95%; Yellow: 90% ≤ <95%; Red: <90%; Indicator B: Instantaneous Detention Rate rate of descent green: <0.5% / h; Yellow: 0.5% / h ≤ < 2% / h; Red: ≥ 2% / h; Indicator C: Total Sequestration Rate level green: ≥ 95%; Yellow: 90% ≤ < 95%; Red: < 90%.

[0017] Early warning decision-making: The final warning status is determined based on the most severe level of the three indicators: Red Alert: If any indicator reaches the red level, it indicates a high risk of leakage and emergency measures must be taken immediately. Yellow alert: There is no red indicator but at least one yellow indicator, indicating potential risk that requires enhanced monitoring; Green status: All indicators are green, indicating normal operation.

[0018] This invention provides a flue gas thermal fracturing-displacement-sequestration isotope tracing monitoring device and method, which has the following beneficial effects: (1) Multi-component independent tracking and precise quantification capability: Traditional monitoring technologies treat industrial flue gas as a mixed whole, failing to distinguish the differentiated behavior of different components (CO2, SO2, NO2) in the formation. This invention achieves this by separately injecting... 13 CO2, 15 NO2 34 SO2, acting as a "fingerprint marker," combined with online isotope ratio analysis, enables independent, in-situ, and simultaneous tracking of key pollutant components in flue gas. Based on an isotope mass balance model, the real-time retention rate and cumulative sequestration amount of CO2, SO2, and NO2 can be calculated separately and quantitatively. This overcomes the limitations of traditional technologies that can only assess the overall sequestration effect, providing a revolutionary means for accurately assessing the sequestration safety and environmental risks of different pollutants.

[0019] (2) Full-process dynamic perception and early warning capability. This invention constructs a three-dimensional monitoring network covering injection wells and monitoring combined extraction wells through a multi-well collaborative automatic sampling system, realizing high spatiotemporal resolution capture of the front edge of the sealed fluid migration. Based on the real-time decay trend of the retention rate (such as the rate of decline), intelligent analysis is performed. Before physical leakage occurs, early warning can be triggered by the abnormal decline trend of the sealing efficiency (instantaneous retention rate, cumulative sealed amount, total sealed rate), realizing a paradigm shift from "passive alarm after the event" to "active early warning before the event", which greatly improves the safety control level of the sealing project.

[0020] (3) High-fidelity sample acquisition and high-quality data foundation. The high temperature, high pressure, and complex composition environment underground poses a severe challenge to the representativeness of samples. The multi-well collaborative sampling system designed in this invention integrates a downhole sampling pump resistant to high temperature and high pressure, a high-efficiency gas-liquid separation and deep drying filtration unit, and combines full-process heating and inert coating sample buffering to effectively prevent distortion, condensation, or adsorption loss of samples during acquisition, transmission, and temporary storage. This ensures that the samples delivered to the isotope analyzer can truly reflect the in-situ state downhole, laying a high-quality data foundation for subsequent accurate isotope analysis and reliable calculations, and guaranteeing the accuracy and reliability of the entire monitoring results. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0022] Figure 2 This is the flowchart for the data processing and retention rate calculation module.

[0023] In the diagram: 1-Rock strata; 2-Coal seam; 3-Hot flue gas storage tank; 4-Isotope storage tank; 5-Mass flow controller; 6-Static mixer; 7-Variable frequency gas injection pump; 8-Humidity conditioning and dust removal system; 9-Heat exchanger group; 10-Gas injection pipeline; 11-Gas injection plug; 12-Injection well; 13-Injection data acquisition unit; 14-Injection data transmission line; 15-Combined well for extraction and monitoring; 16-Extraction plug; 17-Extraction pipeline; 18-Combined data acquisition unit for extraction and monitoring; 19-Combined data transmission line for extraction and monitoring; 20-Downhole gas sampling pump; 21-Gas-liquid separator; 22-Drying and filtration unit; 23-Inert coating sample buffer tank; 24-Isotope analyzer; 25-Data processing and retention rate calculation module; 26-Surface control center. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings, but the scope of protection of the present invention is not limited to the content described.

[0025] This invention provides a flue gas thermal fracturing-displacement-sequestration isotope tracing monitoring device, the structure of which is as follows: Figure 1 As shown ( Figure 1 The image shows only one injection well 12 and one combined extraction and monitoring well 15. In actual use, there can be multiple injection wells 12 and multiple combined extraction and monitoring wells 15, including multiple combined extraction and monitoring wells 15 and multiple L-shaped injection wells 12. The vertical part of each injection well 12 and the combined extraction and monitoring well 15 penetrate the rock stratum 1 from top to bottom and extend to the coal seam 2. The horizontal part of the injection well 12 is inside the coal seam 2.

[0026] It also includes an isotope injection module, a sampling system, an isotope analyzer 24, a data processing and retention rate calculation module 25, and a ground control center 26; the output end of the isotope injection module extends from the ground into each injection well 12 and downwards into the coal seam 2 through multiple gas injection pipes 10; the input end of each sampling system extends from the ground into each extraction monitoring well 15 and downwards into the coal seam 2 through multiple extraction pipes 17.

[0027] The output terminals of the sampling system and the isotope injection module are both connected to the isotope analyzer 24 via gas tubes to analyze the values ​​of the injected or sampled gas in real time. The isotope analyzer 24 is also connected to the data processing and retention rate calculation module 25. The data processing and retention rate calculation module 25 receives the gas values ​​and calculates the instantaneous retention rate and cumulative sequestration of each gas in the formation. The ground control center 26 is connected to both the isotope injection module and the data processing and retention rate calculation module 25 to coordinate and control the entire monitoring process.

[0028] The data processing and retention rate calculation module 25 is deployed on a separate computing device. Available models of the data processing and retention rate calculation module include Xue Dilong's SCS-900S, MRU's SWG300-1, and Shenzhen Guoan's SGA-100X.

[0029] A gas injection plug 11 is installed in the injection well 12 at the top of the coal seam 2, and a extraction plug 16 is installed in the extraction monitoring well 15 at the top of the coal seam 2.

[0030] The isotope injection module of the present invention includes a hot flue gas storage tank 3, an isotope storage tank 4, a static mixer 6, a variable frequency gas injection pump 7, a humidity control and dust removal system 8, and a heat exchanger group 9, which are connected in sequence through gas pipes.

[0031] The hot flue gas storage tank 3 is also connected to the ground control center 26 via a communication cable. The ground control center 26 can remotely monitor the pressure, temperature, and remaining gas volume of the hot flue gas storage tank 3, and control its gas supply valve to realize automated adjustment and safety monitoring of the injection process.

[0032] The isotope storage tank 4 is equipped with a mass flow controller 5MFC on the gas pipes that are connected to the hot flue gas storage tank 3 and the static mixer 6 respectively. This controller is used to precisely control the injection flow rate of each stable isotope marker. The static mixer 6 is used to uniformly mix the stable isotope marker with the industrial flue gas and to inject the stable isotope marker into the industrial flue gas according to a set ratio.

[0033] The heat exchanger assembly 9 is connected to multiple gas injection pipes 10, and each gas injection pipe 10 is also connected to the isotope analyzer 24 via a gas pipe; each gas injection pipe 10 extends downward through a gas injection plug 11 in the corresponding injection well 12. The isotope injection module also includes an injection data transmission line 14. One end of the injection data transmission line 14 extends downward through the gas injection plug 11 in the injection well 12 and is connected to an injection data acquisition device 13 at the end. The other end is connected to a data processing and retention rate calculation module 25. The data acquisition device is located at the lower end of the gas injection pipeline 10.

[0034] The mass flow controller 5MFC has a control accuracy within 0.5% FS; the static mixer 6 is a Kenics type spiral static mixer 6 with an aspect ratio L / D of not less than 15 and a mixing non-uniformity of less than 2%.

[0035] The sampling system includes a downhole gas sampling pump 20, a gas-liquid separator 21, a drying and filtering unit 22, and an inert-coated sample buffer tank 23, which are connected in sequence via gas pipes. The sampling system also includes multiple extraction monitoring combined data transmission lines 19. One end of the extraction pipeline 17 and the extraction monitoring combined data transmission line 19 both extend downward through the extraction plug 16 in the extraction monitoring combined well 15. The other end of the extraction pipeline 17 extends upward to connect to the downhole gas sampling pump 20. The lower end of the extraction monitoring combined data transmission line 19 is connected to the extraction monitoring combined data acquisition device 18, and the upper end is connected to the data processing and retention rate calculation module 25. The extraction monitoring combined data acquisition device is located at the lower end of the extraction pipeline 17.

[0036] The injection data acquisition unit 13 and the extraction monitoring combined data acquisition unit 18 integrate a gas component concentration detection module and a flow monitoring module. The injection data acquisition unit 13 can be a combination of a gas analyzer (QIC MultiStream, VA-5000, Sensi+NG) and a flow meter; the extraction monitoring combined data acquisition unit 18 can be a multi-parameter monitoring device for mine gas extraction boreholes or a mine multi-parameter sensor.

[0037] The ground control center 26 includes a map module, which displays the well location, real-time status, and real-time retention rate curves of carbon, nitrogen, and sulfur elements for each injection well 12 and the combined extraction and monitoring well 15. When the isotope δ value of the combined extraction and monitoring well rises abnormally, a leakage warning is issued. An annual retention rate of ≥95% is considered safe for sealing.

[0038] The isotope analyzer 24 employs a mass spectrometer or a laser spectrometer; when a mass spectrometer is used, it is a continuous-flow isotope ratio mass spectrometer, which is effective for δ¹⁴ ... 13 The analytical precision error of C is within 0.1‰, for δ 15 The analytical precision error of N is within 0.2‰, and for δ 34 The analytical precision error of S is within 0.3‰.

[0039] The present invention also provides a flue gas thermal fracturing-displacement-sealage isotope tracing monitoring method based on the above-mentioned device, comprising the following steps: Step 1: Before the industrial flue gas injection begins, continuous background value monitoring is conducted using the combined extraction and monitoring well to establish a background isotope database, i.e., the isotope ratios of the formation background gas. isotope ratio The results were obtained by analyzing the background gas sampled using an isotope analyzer. Step 2 Step 21: Injection is carried out through one or more injection wells. Specifically, industrial flue gas is output from the hot flue gas storage tank and enters the isotope storage tank. After the flow rate of the stable isotope markers in the isotope storage tank is controlled by a precision mass flow controller, the gas is then fed into a static mixer for uniform mixing. Stable isotope markers include 13 CO2, 15 NO2 and 34 SO2; The injection ratio of stable isotope markers is such that the δ0 of the flue gas after injection into the coal seam is increased. 13 The C value is -5‰ to -10‰ relative to the PDB standard, δ 15 The N value is +50‰ to +80‰ relative to the AIR standard, δ 34 The S value is +10‰ to +20‰ relative to the V-CDT standard; Step 22: The mixed gas is pressurized by a variable frequency gas injection pump, then enters the humidification and dust removal system for treatment, and finally enters the heat exchanger group for temperature adjustment. A small portion of the temperature-adjusted flue gas enters the isotope analyzer through a gas pipe to obtain the isotope ratio of the injected flue gas. The data is then transmitted to the data processing and retention rate calculation module, with most of it injected into the coal seam via gas injection pipelines. During this process, the injection data acquisition device will collect the real-time concentrations of each component ξ at the injection end of the gas injection pipeline. and real-time traffic injection The data is fed to the data processing and retention rate calculation module, where ξ represents CO2 / NO2 / SO2. Step 3: After isotope injection is completed and 24-72 hours of operation has passed, timed, quantitative, and multi-point synchronous sampling is conducted through a sampling system and multiple extraction and monitoring wells. The sampling process includes extracting downhole gas using a downhole gas sampling pump, removing liquid through a gas-liquid separator, removing moisture and particulate matter through a drying and filtration unit, and finally transporting it through pipelines to an inert-coated sample buffer tank. The extraction and monitoring data acquisition unit collects the real-time flow rate of the extracted gas. and the real-time concentration of each component ξ The data is transmitted to the data processing and retention rate calculation module. When multiple sampling systems perform multi-point synchronous sampling through corresponding extraction and monitoring joint wells, the start-up time of each gas sampling pump is staggered. That is, each sampling system adopts asynchronous triggering timing control, and the sampling time points of each extraction and monitoring joint well are set at intervals to avoid interference between wells. Step 4: The inert-coated sample buffer container of the sampling system is connected to the isotope analyzer via a gas pipe. The analyzer performs real-time analysis on the collected gas samples. When using a mass spectrometer, the analysis cycle should not exceed 15 minutes; when using a laser spectrometer, the time resolution should not be less than 1 Hz. The isotope ratio of the gas sampled from the combined well for extraction and monitoring is obtained through the isotope analyzer. The calculated values ​​are output to the data processing and retention rate calculation module, which calculates the mole fraction of the injected gas in the produced gas. The calculation formula is: in, The isotope ratios are measured from gas samples taken from the combined well for extraction and monitoring. The isotope ratio of the injected flue gas. The isotope ratio of the background gas in the formation; Step 5: The data processing and retention rate calculation module calculates the instantaneous retention rate and cumulative sequestration of CO2, NO2, and SO2 in the formation based on the received injection flow rate, sampling flow rate, concentration of each component in the gas during injection and sampling, and mole fraction of the injected gas in the produced gas, and using an isotope mass balance model. It also calculates the instantaneous retention rate of each component based on the isotope mass balance model. The calculation formula is: Where ξ represents CO2, NO2, or SO2. and These are the production flow rate of the combined extraction monitoring well and the injection flow rate of the injection well. and These represent the concentrations of component ξ in the combined extraction and monitoring wells and the injection well, respectively.

[0040] The cumulative time from the start of injection to the arrival of the gas in the inert coating sample buffer container Total retention rate The calculation formula is: In the data processing and retention rate calculation module, component ξ is calculated from the start of injection to time. Cumulative amount of sealed and total seizure rate The calculation formula is: Step 6: The data processing and retention rate calculation module transmits all data to the ground control center, which receives the instantaneous retention rates of each component calculated by the data processing and calculation module. Cumulative amount sealed Total seizure rate The ground control center performs a moving average on the calculated instantaneous retention rate to obtain a trend line. Based on the error propagation theory, it assesses the uncertainty of the retention rate value, determines the confidence interval, compares the instantaneous retention rate value with a preset threshold, outputs the real-time retention rate curve and leakage early warning information, determines whether an early warning is triggered, and outputs the early warning level, trigger time, well location information and suggested measures when an early warning is triggered. Preferably, in step 6, when the instantaneous retention rate and total retention rate are lower than the preset threshold or the rate of decrease exceeds the limit, a leakage warning message is automatically generated and issued, and control instructions are output to the hot flue gas storage tank of the isotope injection module to adjust the injection parameters. The ground control center also integrates and visualizes the information, displays the injection well status, multi-component retention rate change curves, and spatial storage efficiency distribution map in real time, and forms a structured monitoring report.

[0041] Based on the above apparatus and method, the present invention will be further described below: The data processing and retention rate calculation module and the ground control center processing flow of this invention are as follows: Figure 2 As shown, this method enables precise monitoring, quantitative assessment, and intelligent early warning of the geological storage process of industrial flue gas. The specific steps include: S1. Data Input and Collection: The data received by the data processing and retention rate calculation module includes: isotope data (the isotope ratios δ of each component in the injected flue gas and sampled gas measured in real time by the isotope analyzer). 13 C、δ 15 N, δ 34 S ratio), concentration data (concentration values ​​of CO2, NO2, and SO2 in injected flue gas and sampled gas), flow data (injection flow rate of injection wells) ) and the production flow rate of each well monitored in the extraction process ( Background parameters (background values ​​determined before injection, including background isotope ratios) ) and background concentration ( Auxiliary data (wellhead pressure, temperature, well location coordinates, etc.); S2. Data Preprocessing and Quality Control: The raw data is standardized to ensure the accuracy of the calculation, including data cleaning (using statistical methods such as Grubbs test to identify and remove outlier measurements), time synchronization (correcting time offsets caused by transmission and analysis delays in each data stream and unifying the time base), unit standardization (converting all concentration and flow data to values ​​under standard temperature and pressure (STP) conditions), and quality labeling (assigning a quality label to each data point to distinguish reliable data, questionable data, and invalid data). S3, Core Model Calculation (1) Calculation of the injected gas fraction based on isotope mass balance theory Using a binary isotope mixing model: in Indicates time The mole fraction of the produced gas from the injected flue gas. The isotope ratios measured from the sampled gas. The isotope ratio of the injected flue gas. This represents the isotopic ratio of the background gas in the formation. This calculation requires separate analysis of the CO2, NO2, and SO2 components.

[0042] (2) Calculate the instantaneous retention rate For each component ξ (CO2, NO2, SO2): and These are the real-time production flow rate of the combined extraction monitoring well and the real-time injection flow rate of the injection well, respectively. and These represent the real-time concentrations of component ξ in the sampling well and injection well, respectively. This represents the mole fraction of the injected gas in the produced gas, calculated based on isotope ratios. Instantaneous retention rate. It reflects the formation’s sequestration efficiency of each component at a specific time, and the value ranges from 0 (no sequestration) to 1 (complete sequestration).

[0043] (3) Calculate the cumulative amount of sealed inventory The time interval from the start of injection is obtained through time integration. Total amount of sealed inventory: In practical calculations, numerical integration methods (such as the composite trapezoidal rule) are used for discretization.

[0044] (4) Calculate the total seizure rate The sequestration rate reflects the efficiency of the overall sequestration project.

[0045] S4, Post-processing and Spatial Analysis The data is input into the ground control center, where the preliminary calculation results undergo further processing, including data smoothing (using moving average filtering on the instantaneous retention rate time series to eliminate random fluctuations and highlight trend characteristics), uncertainty assessment (calculating the confidence intervals of each result based on error propagation theory to quantify the reliability of the calculation), spatial interpolation (reconstructing the spatial distribution of retention rate in the formation using Kriging interpolation based on data from each monitoring well), and trend analysis (calculating the rate and acceleration of change of retention rate to identify the trend). The ground control center of this invention can be an OHR-K800 embedded data acquisition and control workstation, equipped with Macrochip Panorama Suite, Spotfire Industry Pro, and Esri ArcGIS GeostatisticalAnalyst as core analysis software.

[0046] When the instantaneous retention rate is lower than the preset threshold or the rate of decrease exceeds the limit, a leakage warning is automatically generated and issued. At the same time, control commands are sent to the hot flue gas storage tank to adjust the injection parameters. The ground control center also integrates and visualizes the information. For the instantaneous retention rate and the cumulative storage volume, the spatial interpolation method is used to reconstruct the spatial distribution of the retention rate in the entire formation. The spatial contour map of the retention rate and the thermal map of the spatial distribution of the storage volume are output. The warning colors and the change curves of the instantaneous retention rate of multiple components are displayed in real time, and a structured monitoring report is generated.

[0047] S5. Multi-indicator early warning judgment and parameter adjustment Establish a three-tiered early warning system, based on a comprehensive assessment of three core indicators: Indicator A: Instantaneous Detention Rate absolute level green: >95% (Excellent sealing effect); Yellow: 90% ≤ <95% (Good sealing effect, needs monitoring); Red: <90% (Poor sealing effect, risk exists); Indicator B: Instantaneous Retention Rate rate of descent green: <0.5% / h (gradual change); Yellow: 0.5% / h ≤ < 2% / h (rapid decline); Red: ≥ 2% / h (rapid decline, abnormal situation); Indicator C: Total Sequestration Rate level green: ≥ 95% (high overall sealing efficiency); Yellow: 90% ≤ <95% (overall storage efficiency is good); Red: < 90% (overall sealing efficiency is insufficient).

[0048] Injection parameter adjustment method: Green status: No operation Yellow alert: Perform the following operations according to priority: (1) Reduce the injection flow rate of hot flue gas storage tank. (1) Reduce formation pressure disturbance by 10%~20% and slow down gas breakthrough speed; (2) Reduce the injection pressure of hot flue gas storage tank by 5%~10% to inhibit fracture propagation and dominant channel formation; (3) Switch the injection mode to intermittent injection mode by controlling the injection valve of hot flue gas storage tank: inject for 1 hour and stop for 0.5 hours to give the formation pressure recovery time and improve the sealing efficiency.

[0049] Red Alert: Perform the following operations according to priority: (1) Immediately and significantly reduce the injection flow rate of the hot flue gas storage tank by 30% to 50% to quickly reduce the formation pressure load and block the rapid migration of gas; (2) Significantly reduce the injection pressure of the hot flue gas storage tank to near the formation static pressure to suppress the driving force of the leakage channel; (3) Close the valve to stop the injection, return the flow rate to zero, and then restore it after evaluation; (4) Manually intervene to determine whether emergency measures such as wellhead sealing are needed.

[0050] S6. Comprehensive Early Warning Decision-Making The final warning status is determined based on the most severe level of the three indicators: Red Alert: If any indicator reaches the red level, it indicates a high risk of leakage and emergency measures must be taken immediately. Yellow alert: There is no red indicator but at least one yellow indicator, indicating potential risk that requires enhanced monitoring; Green status: All indicators are green, indicating normal operation.

[0051] S7. Results Output and Visualization The calculation results will be output in multiple formats for engineering decision-making: Real-time graphs: Instantaneous retention rate over time (CO2, NO2, SO2), cumulative storage volume growth curve, and total storage rate change curve; Warning status display: The three-color indicator light (red / yellow / green) displays the current warning level, a detailed explanation of the warning reason (which indicator is high / low), and historical warning event records; Spatial distribution map: spatial contour map of retention rate, thermal map of spatial distribution of stored volume, and marking of monitoring well locations; Structured data reports: summary tables of key indicators, detailed calculation process data, and periodic analysis reports; S8, Looping and Updating The entire processing is executed in a loop at a preset frequency (e.g., every 5 minutes) to achieve real-time data updates: continuously receiving new monitoring data; dynamically refreshing calculations: updating all calculation results based on new data; reassessing early warning status: reassessing the risk status based on the latest data; and archiving historical data: storing the processing results in the database for long-term analysis.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A flue gas thermal fracturing-displacement-sequestration isotope tracing monitoring device, characterized in that: It includes multiple combined extraction and monitoring wells and multiple L-shaped injection wells. The vertical part of each injection well and the combined extraction and monitoring well penetrate the rock strata from top to bottom and extend into the coal seam, while the horizontal part of the injection well is inside the coal seam. It also includes an isotope injection module, a sampling system, an isotope analyzer, a data processing and retention rate calculation module, and a ground control center; the output end of the isotope injection module extends from the ground into each injection well and downwards into the coal seam through multiple gas injection pipes; the input end of each sampling system extends from the ground into each combined extraction and monitoring well and downwards into the coal seam through multiple extraction pipes. The output terminals of the sampling system and the isotope injection module are both connected to the isotope analyzer via gas tubes to analyze the values ​​of the injected or sampled gases in real time. The isotope analyzer is also connected to the data processing and retention rate calculation module, which receives the gas values ​​and calculates the instantaneous retention rate and cumulative sequestration of each gas in the formation. The ground control center is connected to both the isotope injection module and the data processing and retention rate calculation module to coordinate and control the entire monitoring process.

2. The flue gas thermal fracturing-displacement-sequestration isotope tracing monitoring device according to claim 1, characterized in that: The injection well is equipped with a gas injection plug at the top of the coal seam, and the extraction monitoring well is equipped with an extraction plug at the top of the coal seam.

3. The flue gas thermal fracturing-displacement-sequestration isotope tracing monitoring device according to claim 2, characterized in that: The isotope injection module includes a hot flue gas storage tank, an isotope storage tank, a static mixer, a variable frequency gas injection pump, a humidity and dust removal system, and a heat exchanger group, which are connected in sequence by gas pipes. The hot flue gas storage tank is also connected to the ground control center via a communication cable. The ground control center can remotely monitor the pressure, temperature, and remaining gas volume of the hot flue gas storage tank, and control its gas supply valve to achieve automated adjustment and safety monitoring of the injection process. The isotope storage tank is equipped with a mass flow controller (MFC) on the gas pipes that connect the hot flue gas storage tank and the static mixer, respectively. The heat exchanger assembly is connected to multiple gas injection pipes, and each gas injection pipe is also connected to an isotope analyzer via a gas pipe; each gas injection pipe extends downward through a gas injection plugger in its corresponding injection well. It also includes an injection data transmission line, one end of which extends downward through the gas injection plugger inside the injection well and is connected to an injection data acquisition device at the other end; the other end is connected to a data processing and retention rate calculation module; the data acquisition device is located at the lower end of the gas injection pipeline.

4. The flue gas thermal fracturing-displacement-sequestration isotope tracing monitoring device according to claim 3, characterized in that: The control accuracy of the mass flow controller (MFC) is within 0.5% FS; the static mixer is a Kenics-type spiral static mixer with an aspect ratio (L / D) of not less than 15 and a mixing non-uniformity of less than 2%.

5. The flue gas thermal fracturing-displacement-sequestration isotope tracing monitoring device according to claim 2, characterized in that: The sampling system includes a downhole gas sampling pump, a gas-liquid separator, a drying and filtering unit, and an inert-coated sample buffer container, which are connected in sequence via gas pipes. It also includes multiple extraction monitoring and data transmission lines. One end of the extraction pipeline and the extraction monitoring and data transmission line both extend downward through the extraction plug in the extraction monitoring well. The other end of the extraction pipeline extends upward to connect to the downhole gas sampling pump. The lower end of the extraction monitoring and data transmission line is connected to an extraction monitoring data acquisition device, and the upper end is connected to a data processing and retention rate calculation module. The extraction monitoring data acquisition device is located at the lower end of the extraction pipeline.

6. The flue gas thermal fracturing-displacement-sequestration isotope tracing monitoring device according to claim 5, characterized in that: The ground control center includes a map module, which displays the well location, real-time status, and real-time retention rate curves of carbon, nitrogen, and sulfur for each injection well and extraction monitoring well. When the isotope δ value of the extraction monitoring well rises abnormally, a leakage warning is issued. An annual retention rate of ≥95% is considered safe for sealing.

7. The flue gas thermal fracturing-displacement-sequestration isotope tracing monitoring device according to claim 1, characterized in that: The isotope analyzer is a mass spectrometer or a laser spectrometer; when a mass spectrometer is used, it is a continuous-flow isotope ratio mass spectrometer, which is effective for δ¹⁸O⁻ ... 13 The analytical precision error of C is within 0.1‰, for δ 15 The analytical precision error of N is within 0.2‰, and for δ 34 The analytical precision error of S is within 0.3‰.

8. A flue gas thermal fracturing-displacement-sealage isotope tracing monitoring method based on the apparatus described in any one of claims 1-7, characterized in that: Includes the following steps: Step 1: Before the industrial flue gas injection begins, continuous background value monitoring is conducted using the combined extraction and monitoring well to establish a background isotope database, i.e., the isotope ratios of the formation background gas. isotope ratio The results were obtained by analyzing the background gas sampled using an isotope analyzer. Step 2 Step 21: Injection is carried out through one or more injection wells. Specifically, industrial flue gas is output from the hot flue gas storage tank and enters the isotope storage tank. After the flow rate of the stable isotope markers in the isotope storage tank is controlled by a precision mass flow controller, the gas is then fed into a static mixer for uniform mixing. Stable isotope markers include 13 CO2, 15 NO2 and 34 SO2; The injection ratio of stable isotope markers is such that the δ0 of the flue gas after injection into the coal seam is increased. 13 The C value is -5‰ to -10‰ relative to the PDB standard, δ 15 The N value is +50‰ to +80‰ relative to the AIR standard, δ 34 The S value is +10‰ to +20‰ relative to the V-CDT standard; Step 22: The mixed gas is pressurized by a variable frequency gas injection pump, then enters the humidification and dust removal system for treatment, and finally enters the heat exchanger group for temperature adjustment. A small portion of the temperature-adjusted flue gas enters the isotope analyzer through a gas pipe to obtain the isotope ratio of the injected flue gas. The data is then transmitted to the data processing and retention rate calculation module, with most of it injected into the coal seam via gas injection pipelines. During this process, the injection data acquisition device will collect the real-time concentrations of each component ξ at the injection end of the gas injection pipeline. and real-time traffic injection The data is sent to the data processing and retention rate calculation module, where ξ represents CO2, NO2, or SO2. Step 3: After isotope injection is completed and 24-72 hours of operation has passed, timed, quantitative, and multi-point synchronous sampling is conducted using a sampling system and multiple extraction monitoring wells. The sampling process includes extracting downhole gas using a downhole gas sampling pump, removing liquid through a gas-liquid separator, removing moisture and particulate matter through a drying and filtration unit, and finally transporting it through pipelines to an inert-coated sample buffer tank. The extraction monitoring data acquisition device collects the real-time flow rate of the extracted gas. and the real-time concentration of each component ξ The data is transmitted to the data processing and retention rate calculation module. When multiple sampling systems perform multi-point synchronous sampling through corresponding extraction and monitoring joint wells, the start-up time of each gas sampling pump is staggered. That is, each sampling system adopts asynchronous triggering timing control, and the sampling time points of each extraction and monitoring joint well are set at intervals to avoid interference between wells. Step 4: The inert-coated sample buffer container of the sampling system is connected to the isotope analyzer via a gas pipe. The analyzer performs real-time analysis on the collected gas samples. When using a mass spectrometer, the analysis cycle should not exceed 15 minutes; when using a laser spectrometer, the time resolution should not be less than 1 Hz. The isotope ratio of the gas sampled from the combined well for extraction and monitoring is obtained through the isotope analyzer. The calculated values ​​are output to the data processing and retention rate calculation module, which calculates the mole fraction of the injected gas in the produced gas. The calculation formula is: in, The isotope ratios are measured from gas samples taken from the combined well for extraction and monitoring. The isotope ratio of the injected flue gas. The isotope ratio of the background gas in the formation; Step 5: The data processing and retention rate calculation module calculates the instantaneous retention rate and cumulative sequestration of CO2, NO2, and SO2 in the formation based on the received injection flow rate, sampling flow rate, concentration of each component in the gas during injection and sampling, and mole fraction of the injected gas in the produced gas, and using an isotope mass balance model. It also calculates the instantaneous retention rate of each component based on the isotope mass balance model. The calculation formula is: Where ξ represents CO2, NO2, or SO2. and These are the production flow rate of the combined extraction monitoring well and the injection flow rate of the injection well. and The concentrations of component ξ in the combined extraction and injection wells are respectively. The cumulative time from the start of injection to the arrival of the gas in the inert coating sample buffer container Total retention rate The calculation formula is: In the data processing and retention rate calculation module, component ξ is calculated from the start of injection to time. Cumulative amount of sealed and total seizure rate The calculation formula is: Step 6: The data processing and retention rate calculation module transmits all data to the ground control center, which receives the instantaneous retention rates of each component calculated by the data processing and calculation module. Cumulative amount sealed Total seizure rate The ground control center performs a moving average process on the calculated instantaneous retention rate to obtain a trend line. Based on the error propagation theory, it assesses the uncertainty of the retention rate value, determines the confidence interval, compares the instantaneous retention rate value with a preset threshold, and outputs a real-time retention rate curve and leakage early warning information.

9. The flue gas thermal fracturing-displacement-sequestration isotope tracing monitoring method according to claim 8, characterized in that: In step 6, when the instantaneous retention rate and total sealed volume are lower than the preset threshold or the rate of decrease exceeds the limit, a leakage warning is automatically generated and issued. At the same time, control commands are output to the hot flue gas storage tank to adjust the injection parameters. The ground control center also integrates and visualizes the information. For the instantaneous retention rate and cumulative sealed volume, a spatial interpolation method is used to reconstruct the spatial distribution of the retention rate in the entire formation. The spatial contour map of the retention rate and the thermal map of the spatial distribution of the sealed volume are output. The warning colors and the change curves of the instantaneous retention rate of multiple components are displayed in real time, and a structured monitoring report is generated.

10. The flue gas thermal fracturing-displacement-sequestration isotope tracing monitoring method according to claim 9, characterized in that: Early warning judgments are based on three indicators: Indicator A: Instantaneous Detention Rate absolute level green: >95%; Yellow: 90% ≤ <95%; Red: <90%; Indicator B: Instantaneous Detention Rate rate of descent green: <0.5% / h; Yellow: 0.5% / h ≤ < 2% / h; red: ≥ 2% / h; Indicator C: Total Sequestration Rate level green: ≥ 95%; Yellow: 90% ≤ < 95%; red: < 90%. Early warning decision-making: The final warning status is determined based on the most severe level of the three indicators: Red Alert: If any indicator reaches the red level, it indicates a high risk of leakage and emergency measures must be taken immediately. Yellow alert: There is no red indicator but at least one yellow indicator, indicating potential risk that requires enhanced monitoring; Green status: All indicators are green, indicating normal operation.

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