Early warning and source tracing method for CO2 microleakage in saline aquifers based on isotope tracing

Abstract

This invention discloses an early warning and source tracing method for CO2 microleakage in saline aquifers based on isotope tracing, comprising: an injection device including an air compressor, a tracer storage tank, and an injection pump; a monitoring well device including a wellbore, a wellhead device, and monitoring instruments, arranged around the injection device; a sampling device including a sampler and a sample bottle, connected to the monitoring well device; analytical instruments including an inductively coupled plasma mass spectrometer, an isotope ratio mass spectrometer, an X-ray fluorescence spectrometer, and an atomic absorption spectrometer; and a data processing and early warning system. This invention solves the problem that conventional monitoring technologies cannot identify early microleakage, achieving accurate early identification and timely warning of CO2 microleakage. Furthermore, through optimized design of the structure of each device, the integrity and pollution-free nature of the saline aquifer water samples are ensured, enabling accurate and rapid analysis of water quality parameters.

Description

Technical Field

[0001] This invention relates to the field of geological material analysis technology, specifically to an early warning and source tracing method for CO2 micro-leakage in saline aquifers based on isotope tracing. Background Technology

[0002] With the intensification of global warming, greenhouse gas emission reduction has become an urgent task for all mankind. Carbon capture, utilization and storage (CFS) technology, as one of the core supporting technologies for achieving the "dual carbon" goal, can effectively capture CO2 from industrial emissions and energy production and achieve long-term carbon sequestration through geological storage. Among them, saline aquifers have become the preferred carrier for CO2 geological storage due to their huge reserves, wide distribution and outstanding storage potential. Many mature CO2 geological storage projects around the world use saline aquifers as the main storage sites. my country's near-shore basin saline aquifers have a huge CO2 storage capacity, providing an important foundation for the large-scale application of carbon capture, utilization and storage technology.

[0003] However, the long-term safety of CO2 sequestration in saline aquifers remains a key bottleneck restricting the widespread application of this technology. The complex and uncertain geological conditions of saline aquifers mean that long-term CO2 injection can lead to changes in formation pressure. Combined with issues such as formation fracturing, insufficient reservoir strength, and sand production during injection, this can easily trigger micro-leakage of CO2. This means that CO2 migrates upwards from the saline aquifer reservoir at extremely low rates through caprock fractures, faults, or wellbore gaps, potentially contaminating shallow groundwater, affecting drinking water safety, causing public health concerns, and even inducing geological disasters. Simultaneously, it reduces CO2 sequestration efficiency, contradicting the original purpose of carbon capture, utilization, and storage (CCUS) technology. The U.S. Environmental Protection Agency has issued regulatory orders for related CCC projects due to the potential impact of CO2 leaks on drinking water reservoirs. Illinois has even enacted legislation to protect aquifers, further highlighting the importance of preventing micro-leakage of CO2. The Intergovernmental Panel on Climate Change (IPCC) of the United Nations has also explicitly required that the leakage of CO2 during a 1000-year geological sequestration period should be less than 1%.

[0004] CO2 microleakage is characterized by its high concealment, low leakage rate, and complex migration path. In the early stages, there are no obvious macroscopic anomalies, making accurate identification and early warning difficult with conventional monitoring technologies. Current CO2 leak monitoring methods have many limitations. For example, weighing methods, liquid level detection methods, and tapping methods all have significant time lags, only detecting leaks after they have reached a certain level, failing to meet early warning requirements. While non-dispersive infrared sensing technology has high sensitivity, it is mostly used for leak location in industrial pipelines and cold storage facilities, making it unsuitable for long-term continuous monitoring in complex underground environments like saline aquifers. Traditional geological monitoring technologies such as seismic monitoring and resistivity methods not only face difficulties in data processing and calibration, and the inability to cross-reference results from different monitoring methods, but are also susceptible to surface subsidence and the coexistence of multiple sealing strata, making it difficult to accurately capture microleakage signals and distinguish the source and migration patterns of leaked CO2. Summary of the Invention

[0005] The purpose of this invention is to provide an early warning and source tracing method for CO2 microleakage in saline aquifers based on isotope tracing, so as to solve the problems mentioned in the background art.

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

[0007] Early warning of CO2 microleakage in saline aquifers based on isotope tracing includes:

[0008] An injection device, comprising an air compressor, a tracer storage tank, and an injection pump, is used to precisely inject CO2 carrying a tracer into a saline water body, providing a specific identifier for subsequent water quality tracer monitoring;

[0009] The monitoring well device includes a well casing, a wellhead device, and monitoring instruments, which are set around the injection device to monitor the pressure, temperature, and other physicochemical parameters of the saline water in real time, and to collect saline water samples to provide basic samples for water quality analysis.

[0010] The sampling device includes a sampler and a sample bottle, and is connected to the monitoring well device. It is used to quantitatively collect water samples from different depths and locations in the saline aquifer to ensure that the samples are free from pollution and deterioration and meet the sample requirements for water quality analysis.

[0011] The analytical instruments include an inductively coupled plasma mass spectrometer, an isotope ratio mass spectrometer, an X-ray fluorescence spectrometer, and an atomic absorption spectrometer, which are used to perform precise water quality analysis on saline water samples, detect tracer concentration, isotope ratio and related ion content in the samples, and capture water quality parameter anomalies caused by CO2 microleakage.

[0012] The data processing and early warning system is electrically connected to the analytical instrument and is used to receive water quality analysis data. Based on the variation patterns of tracer concentration and isotope ratio in the water body, combined with the water quality benchmark parameters of the saline aquifer, it determines whether CO2 micro-leakage has occurred and issues an early warning in a timely manner.

[0013] Preferably, the air compressor is sealed to the air inlet of the tracer storage tank through a high-pressure corrosion-resistant pipe. The inner wall of the high-pressure corrosion-resistant pipe is coated with a nano-coating to prevent pipeline corrosion from generating impurities that pollute the saline water layer and ensure the accuracy of water quality monitoring.

[0014] Preferably, the outlet of the injection pump is connected to the return pipe of the tracer storage tank and the main CO2 injection pipe respectively through a three-way connector, and the pipe connecting the outlet of the tracer storage tank and the inlet of the injection pump is equipped with a flow regulating valve, which can accurately control the amount of tracer injected, ensure that the initial concentration of tracer in the saline water layer is uniform, and provide a stable benchmark for water quality tracer analysis.

[0015] Preferably, a dynamic proportioning valve and a CO2-tracer mixing chamber are installed on the pipeline between the injection pump and the tee connector, and a spiral turbulence-disrupting blade is set inside the mixing chamber to ensure that the tracer and CO2 are fully mixed before being injected into the saline water layer, so as to avoid the local concentration of tracer being too high or too low and affecting the accuracy of water quality monitoring; the tracer storage tank is equipped with a layered slow-release baffle to realize the slow and stable release of tracer and maintain the stability of the tracer baseline concentration in the saline water layer.

[0016] Preferably, the well casing adopts a carbon steel inner polyethylene sleeve structure, which is fixed to the flange of the wellhead device by threaded connection. The connection is filled with epoxy resin mortar to prevent shallow groundwater and surface impurities from seeping into the monitoring well, avoid contaminating the saline water sample, and ensure the authenticity and reliability of water quality analysis data.

[0017] Preferably, an explosion-proof junction box is installed on the top of the wellhead device. The monitoring interface of the wellhead device is connected to a pressure sensor, a temperature sensor and an isotope concentration detector through a quick connector, which can collect the physicochemical parameters and preliminary isotope detection data of the saline water body in real time, and realize the real-time monitoring of water quality parameters and the preliminary detection of anomalies.

[0018] Preferably, the sampler is connected to the sampling port at the bottom of the monitoring well via a temperature- and pressure-resistant flexible hose to ensure that the water sample does not come into contact with the outside world and does not experience sudden temperature or pressure changes during the sampling process; the sample outlet of the sampler is connected to the sample bottle via a connecting pipe, and a vacuum isolation valve is installed on the connecting pipe to prevent the sample in the sample bottle from being contaminated, ensuring the integrity of the water sample and meeting the needs of subsequent accurate water quality analysis.

[0019] Preferably, the sample vial is connected to the sample inlet chamber of the inductively coupled plasma mass spectrometer via an automated sampler, enabling automated and continuous water quality analysis of water samples and improving analysis efficiency and accuracy. The inductively coupled plasma mass spectrometer, isotope ratio mass spectrometer, and X-ray fluorescence spectrometer are connected to the central data processing unit via an Ethernet interface, ensuring rapid and lossless transmission of water quality analysis data and providing timely support for subsequent data processing and early warning.

[0020] Preferably, the data processing and early warning system includes a computer, data processing software, and an early warning device. The computer, data processing software, early warning device, inductively coupled plasma mass spectrometer, isotope ratio mass spectrometer, X-ray fluorescence spectrometer, and atomic absorption spectrometer are electrically connected to each other, enabling real-time processing of water quality analysis data and comparison with the baseline water quality parameters of the saline aquifer. When abnormal fluctuations occur in the tracer concentration or isotope ratio, an early warning is quickly triggered.

[0021] A source-tracing method for early warning of CO2 microleakage in saline aquifers based on isotope tracing includes the following steps:

[0022] S1. Water Quality Data Acquisition and Preprocessing: Using monitoring instruments in the monitoring well system, physicochemical parameters such as pressure and temperature of the water within the saline aquifer are continuously collected. Simultaneously, sampling devices are used to quantitatively collect water samples from the saline aquifer at different times and locations. Comprehensive water quality analysis is performed on the water samples using analytical instruments to obtain data on tracer concentration, isotope ratios, and related ion content. The collected water quality data undergoes preprocessing, including washing to remove outliers and noise, and normalization to ensure the comparability of water quality parameters of different dimensions, providing a reliable water quality data foundation for subsequent source tracing analysis.

[0023] S2. Constructing a Water Quality Source Tracing Model: Based on the geological structure, hydrological characteristics, and historical CO2 injection data of the saline aquifer, and combining the principles of isotope tracing and water quality migration patterns, a CO2 micro-leakage water quality source tracing model suitable for this saline aquifer is constructed. The model should focus on the diffusion and migration patterns of tracers in the saline aquifer, as well as the correlation between changes in tracer concentration and isotope ratios at different locations and time points and the CO2 micro-leakage source. The model is trained and validated using known CO2 injection experimental or simulated water quality data, and the model parameters are adjusted to ensure that it accurately reflects the migration characteristics of tracers and isotopes in the saline aquifer, thereby improving the accuracy of source tracing.

[0024] S3. Micro-leakage Source Location and Water Quality Source Tracing Analysis: Pre-treated water quality data is input into the source tracing model. Through model calculation and analysis, based on the abnormal variation range of tracer concentration and isotope ratio in the water body, the possible location area of ​​CO2 micro-leakage is determined, and the micro-leakage source is preliminarily located. Combining the geological structure of the saline aquifer, hydrological flow path, and water quality anomaly distribution characteristics, a detailed analysis of the preliminary location results is conducted. Taking into account factors such as leakage path and causes, the final micro-leakage source is determined, and the potential impact of the micro-leakage on the surrounding saline aquifer water quality and ecological environment is assessed.

[0025] S4. Source Tracing Result Verification and Model Dynamic Update: The source tracing analysis results are verified using methods such as on-site investigation and supplementary monitoring. For example, borehole sampling is conducted at suspected micro-leakage sources, and water samples are re-tested. The test results are compared with the tracer concentration and isotope ratio predicted by the model to verify the accuracy of the source tracing results. As time progresses and new water quality monitoring data is acquired, the water quality source tracing model is continuously updated and optimized to adapt to changes in the saline aquifer environment and the evolution of CO2 micro-leakage, improving the reliability and accuracy of subsequent source tracing analyses.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1. This invention overcomes the limitations of existing monitoring technologies, which are lagging behind and have poor adaptability. Taking saline aquifer water quality monitoring as the core, it constructs an integrated system of injection, monitoring, sampling, analysis, and early warning. Combined with the high sensitivity and specificity of isotope tracer technology, it can accurately capture the abnormalities in tracer concentration, isotope ratio, and physicochemical parameters of water caused by CO2 microleakage. It solves the problem that conventional monitoring technologies cannot identify early microleakage, realizes early and accurate identification and timely warning of CO2 microleakage, and effectively ensures the long-term safety of CO2 sequestration in saline aquifers.

[0028] 2. This invention, through optimized design of various device structures (such as pipe nano-coating, mixing chamber baffles, vacuum isolation valves, etc.), ensures the integrity and pollution-free nature of saline water samples. Combined with the collaborative application of multiple analytical instruments, it achieves accurate and rapid analysis of water quality parameters. At the same time, it is equipped with a dedicated source tracing method, which can accurately locate micro-leakage sources, trace migration paths, and assess environmental impacts. This solves the problems of existing technologies being unable to distinguish leakage sources and having low source tracing accuracy. Furthermore, it can dynamically optimize the source tracing model, further improving the reliability of monitoring and source tracing, and providing strong technical support for the large-scale application of carbon capture, utilization, and storage technologies. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the present invention;

[0030] Figure 2 This is a schematic diagram of the method flow of the present invention.

[0031] In the diagram: 1. Air compressor; 2. Tracer storage tank; 3. Injection pump; 4. Wellbore; 5. Wellhead device; 6. Monitoring instrument; 7. Sampler; 8. Sample bottle; 9. Inductively coupled plasma mass spectrometer; 10. Isotope ratio mass spectrometer; 11. X-ray fluorescence spectrometer; 12. Atomic absorption spectrometer. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1:

[0034] Please see Figures 1-2 The present invention provides a technical solution:

[0035] Early warning of CO2 microleakage in saline aquifers based on isotope tracing includes:

[0036] The injection device includes an air compressor 1, a tracer storage tank 2, and an injection pump 3. It is used to precisely inject CO2 carrying the tracer into the saline water layer, providing a specific identifier for subsequent water quality monitoring. The air compressor 1 is sealed to the air inlet of the tracer storage tank 2 via a high-pressure corrosion-resistant pipe. The inner wall of the high-pressure corrosion-resistant pipe is coated with a nano-coating to prevent corrosion and contamination of the saline water layer, ensuring the accuracy of water quality monitoring. The outlet of the injection pump 3 is connected to the return pipe of the tracer storage tank 2 and the main CO2 injection pipe via a tee connector. The outlet of the tracer storage tank 2 is connected to the inlet of the injection pump 3. The pipeline connected to the liquid end is equipped with a flow regulating valve, which can precisely control the amount of tracer injected, ensuring that the initial concentration of tracer in the saline water is uniform and providing a stable benchmark for water quality tracer analysis. The pipeline between the injection pump 3 and the tee joint is equipped with a dynamic proportioning valve and a CO2-tracer mixing chamber. The mixing chamber is equipped with spiral baffles to ensure that the tracer and CO2 are fully mixed before being injected into the saline water, avoiding excessively high or low local concentrations of tracer that could affect the accuracy of water quality monitoring. The tracer storage tank 2 is equipped with a layered slow-release baffle to achieve slow and stable release of tracer, maintaining a stable benchmark concentration of tracer in the saline water.

[0037] After system startup, air compressor 1 generates high-pressure gas, which is transported to tracer storage tank 2 through a high-pressure corrosion-resistant pipeline with a nano-coated inner wall, providing stable pressure for tracer output. The storage tank is equipped with layered slow-release baffles, which extend the tracer flow path, allowing for slow and stable release and avoiding pulsed concentration fluctuations. Injection pump 3 precisely extracts the tracer from the tank. Before entering the main CO2 injection pipeline, it first passes through a dynamic proportioning valve and merges with high-pressure CO2, then enters a mixing chamber with built-in spiral turbulence vanes. The turbulence vanes disrupt the laminar flow state through high-speed shearing, achieving molecular-level uniform mixing of the tracer and CO2, and finally, precise injection into the target saline aquifer through the injection well. This process utilizes a specific isotopic tracer as a "marker," physically ensuring a highly uniform and stable initial concentration in CO2, providing a clear background value for subsequent monitoring. Simultaneously, the nano-coating effectively prevents pipeline corrosion from generating impurities that contaminate the saline aquifer, eliminating interfering factors. This high-precision injection method allows for the correlation of CO2 migration with even minute changes in tracer concentration, significantly improving the sensitivity and accuracy of microleakage identification.

[0038] The monitoring well device includes a well casing 4, a wellhead device 5, and monitoring instruments 6, which are set around the injection device. It is used to monitor the physicochemical parameters such as pressure and temperature of the saline water in real time and to collect saline water samples to provide basic samples for water quality analysis. The well casing 4 adopts a carbon steel inner polyethylene sleeve structure and is fixed to the flange of the wellhead device 5 by threaded connection. The connection is filled with epoxy resin mortar to prevent shallow groundwater and surface impurities from seeping into the monitoring well and avoiding contamination of the saline water samples, thus ensuring the authenticity and reliability of water quality analysis data. The top of the wellhead device 5 is equipped with an explosion-proof junction box. The monitoring interface of the wellhead device 5 is connected to the pressure sensor, temperature sensor, and isotope concentration detector through quick connectors, which can collect the physicochemical parameters and preliminary isotope detection data of the saline water in real time, realizing real-time monitoring of water quality parameters and preliminary detection of anomalies.

[0039] After arranging a group of monitoring wells around the injection well according to hydrogeological conditions, the well casing 4, made of carbon steel lined with polyethylene casing, is fixed to the flange of the wellhead device 5 via threaded connection. The connection is filled with epoxy resin mortar to completely seal the infiltration channels of shallow groundwater or surface water, ensuring that the collected water samples only represent the true condition of the target saline aquifer. The top of the wellhead device 5 is equipped with an explosion-proof junction box. The monitoring interface is connected to the pressure sensor, temperature sensor, and isotope concentration detector via quick connectors to collect the physicochemical parameters and preliminary isotope data of the saline aquifer in real time and transmit them to the ground control room. This device establishes a long-term, stable, and undisturbed underground fluid observation window: real-time online monitoring can capture minute fluctuations in pressure, temperature field, or tracer concentration at the first moment, realizing the leap from "point sampling" to "continuous monitoring"; strict sealing and isolation measures ensure the authenticity and reliability of the data, eliminate false alarms caused by the mixing of external water bodies, and buy valuable time for early warning.

[0040] The sampling device includes a sampler 7 and a sample bottle 8, and is connected to the monitoring well device. It is used to quantitatively collect water samples from different depths and locations within the saline aquifer, ensuring the samples are uncontaminated and undeteriorated, meeting the requirements for water quality analysis. The sampler 7 is connected to the sampling port at the bottom of the monitoring well via a temperature- and pressure-resistant flexible hose, ensuring that the water sample does not come into contact with the outside environment and does not experience sudden temperature or pressure changes during sampling. The outlet of the sampler 7 is connected to the sample bottle 8 via a connecting pipe equipped with a vacuum shut-off valve to prevent the sample from leaking into the sample bottle 8. To prevent contamination and ensure the integrity of water samples, meeting the needs of subsequent precise water quality analysis, sample bottle 8 is connected to the sample introduction chamber of the inductively coupled plasma mass spectrometer via an automated sampler, enabling automated and continuous water quality analysis and improving analysis efficiency and accuracy. The inductively coupled plasma mass spectrometer 9, isotope ratio mass spectrometer 10, and X-ray fluorescence spectrometer 11 are connected to the central data processing unit via an Ethernet interface, ensuring rapid and lossless transmission of water quality analysis data and providing timely support for subsequent data processing and early warning.

[0041] When monitoring instrument 6 detects an anomaly or according to the preset sampling plan, sampler 7 is lowered to the designated depth of the monitoring well via a temperature- and pressure-resistant flexible hose, and water is drawn using negative pressure or a piston principle. Before the sample enters the sample vial 8 through the connecting tube, the vacuum isolation valve is first opened to expel the air in the tube, ensuring that the sample is filled into the vial in a completely isolated environment, preventing the sample from oxidizing or absorbing carbon dioxide from the air and changing the isotope ratio. After collection, the sample vial 8 is sequentially sent to analytical instruments such as inductively coupled plasma mass spectrometry for depth analysis via an automated sampler. The core of this device is to ensure the "authenticity" of the sample throughout the entire process from deep underground to analysis: the temperature- and pressure-resistant flexible hose prevents sudden changes in pressure and temperature from disrupting ion balance or causing gas escape; the vacuum isolation valve prevents contact with air; and the automated sample introduction eliminates secondary contamination and errors caused by manual operation. Ultimately, this ensures that laboratory data accurately reflects the underground geochemical state, improves analytical efficiency and data comparability, and provides a reliable data source for the early warning system.

[0042] The analytical instruments include an inductively coupled plasma mass spectrometer 9, an isotope ratio mass spectrometer 10, an X-ray fluorescence spectrometer 11, and an atomic absorption spectrometer 12, which are used to perform precise water quality analysis on saline water samples, detect tracer concentration, isotope ratio and related ion content in the samples, and capture water quality parameter anomalies caused by CO2 microleakage.

[0043] After sample preparation, the samples were assigned to different instruments according to the detection targets: inductively coupled plasma mass spectrometry (ICP-MS) determined the concentration of trace tracers and the content of multiple elements in the water; isotope ratio mass spectrometry (IPSM) 10 accurately measured the changes in specific isotope ratios of the tracers; X-ray fluorescence spectrometry (XRF) 11 and atomic absorption spectrometry (AAS) 12 supplemented the analysis to analyze major and trace elements in the water and any possible sediments. All instruments uploaded the analysis results to the central data processing unit in real time via Ethernet interface. This process utilizes the expertise of multiple instruments to "diagnose" the water samples: IPSM 10, by measuring the isotope fractionation effect, can highly sensitively identify tracers originating from injected CO2 (even at extremely low concentrations); ICP-MS monitors characteristic ions related to CO2 dissolution (such as...). , Changes in (etc.) indirectly confirm the CO2-water-rock reaction. The use of multiple instruments constructs a multi-dimensional water quality monitoring system. Isotope tracing provides direct evidence, while ion changes provide indirect evidence. The two corroborate each other, greatly improving the accuracy of microleakage identification and effectively reducing the risk of false alarms and missed alarms caused by instrument drift or abnormalities in a single indicator.

[0044] The data processing and early warning system, electrically connected to the analytical instruments, receives water quality analysis data. Based on the variation patterns of tracer concentration and isotope ratio in the water body, combined with the reference parameters of saline water quality, it determines whether CO2 micro-leakage has occurred and issues timely warnings. The data processing and early warning system includes a computer, data processing software, and an early warning device. The computer, data processing software, early warning device, inductively coupled plasma mass spectrometer 9, isotope ratio mass spectrometer 10, X-ray fluorescence spectrometer 11, and atomic absorption spectrometer 12 are electrically connected. It can process water quality analysis data in real time, compare it with the reference water quality parameters of saline water body, and quickly trigger an early warning when abnormal fluctuations occur in tracer concentration and isotope ratio.

[0045] The central data processing unit receives all data in real time from online monitoring instrument 6 and laboratory analytical instruments. Built-in data processing software automatically cleans and corrects the data, and performs real-time comparison and trend analysis with previously established saline aquifer water quality benchmark parameters (background values). Based on statistical and geochemical models, the system establishes an early warning model, comparing not only the absolute values ​​of single indicators but also analyzing the coupling relationships between multiple parameters (e.g., whether an increase in tracer concentration is accompanied by a decrease in pH and an increase in Ca ions). By identifying this characteristic "abnormal fingerprint," the system accurately determines whether the anomaly is caused by CO2 microleakage. When tracer concentration, isotope ratio, or specific ion concentration exhibits abnormal fluctuations exceeding threshold ranges, the system immediately triggers an early warning through audible and visual alarms, SMS, and email. This early warning system transforms scattered raw data into intuitive early warning information, achieving full automation from data acquisition, analysis, and interpretation to early warning, significantly shortening response time. Through multi-parameter comprehensive identification, it significantly improves the scientific rigor and reliability of early microleakage identification, providing a solid technical guarantee for the long-term safety of saline aquifer storage.

[0046] Example 2:

[0047] The difference between Example 2 and Example 1 is that:

[0048] A source-tracing method for early warning of CO2 microleakage in saline aquifers based on isotope tracing includes the following steps:

[0049] S1. Water Quality Data Acquisition and Preprocessing: Using monitoring instruments 6 of the monitoring well device, physicochemical parameters such as pressure and temperature of the water in the saline aquifer are continuously collected. Simultaneously, sampling devices are used to quantitatively collect water samples from the saline aquifer at different times and locations. Comprehensive water quality analysis is performed on the water samples using analytical instruments to obtain data on tracer concentration, isotope ratios, and related ion content. The collected water quality data undergoes preprocessing, including washing to remove outliers and noise, and normalization to ensure the comparability of water quality parameters of different dimensions, providing a reliable water quality data foundation for subsequent source tracing analysis.

[0050] S2. Constructing a Water Quality Source Tracing Model: Based on the geological structure, hydrological characteristics, and historical CO2 injection data of the saline aquifer, and combining the principles of isotope tracing and water quality migration patterns, a CO2 micro-leakage water quality source tracing model suitable for this saline aquifer is constructed. The model should focus on the diffusion and migration patterns of tracers in the saline aquifer, as well as the correlation between changes in tracer concentration and isotope ratios at different locations and time points and the CO2 micro-leakage source. The model is trained and validated using known CO2 injection experimental or simulated water quality data, and the model parameters are adjusted to ensure that it accurately reflects the migration characteristics of tracers and isotopes in the saline aquifer, thereby improving the accuracy of source tracing.

[0051] S3. Micro-leakage Source Location and Water Quality Source Tracing Analysis: Pre-treated water quality data is input into the source tracing model. Through model calculation and analysis, based on the abnormal variation range of tracer concentration and isotope ratio in the water body, the possible location area of ​​CO2 micro-leakage is determined, and the micro-leakage source is preliminarily located. Combining the geological structure of the saline aquifer, hydrological flow path, and water quality anomaly distribution characteristics, a detailed analysis of the preliminary location results is conducted. Taking into account factors such as leakage path and causes, the final micro-leakage source is determined, and the potential impact of the micro-leakage on the surrounding saline aquifer water quality and ecological environment is assessed.

[0052] S4. Source Tracing Result Verification and Model Dynamic Update: The source tracing analysis results are verified using methods such as on-site investigation and supplementary monitoring. For example, borehole sampling is conducted at suspected micro-leakage sources, and water samples are re-tested. The test results are compared with the tracer concentration and isotope ratio predicted by the model to verify the accuracy of the source tracing results. As time progresses and new water quality monitoring data is acquired, the water quality source tracing model is continuously updated and optimized to adapt to changes in the saline aquifer environment and the evolution of CO2 micro-leakage, improving the reliability and accuracy of subsequent source tracing analyses.

[0053] 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. An early warning of CO2 microseepage in a saline aquifer based on isotope tracing, characterized in that, include: An injection device, comprising an air compressor (1), a tracer storage tank (2), and an injection pump (3), is used to precisely inject CO2 carrying tracer into the saline water body to provide a specific identifier for subsequent water quality tracer monitoring; The monitoring well device includes a well casing (4), a wellhead device (5), and a monitoring instrument (6), which are set around the injection device to monitor the pressure, temperature and other physicochemical parameters of the saline water body in real time, and to collect saline water body samples to provide basic samples for water quality analysis. The sampling device includes a sampler (7) and a sample bottle (8), and is connected to the monitoring well device. It is used to quantitatively collect water samples from different depths and locations of the saline layer to ensure that the samples are free from pollution and deterioration and meet the sample requirements for water quality analysis. The analytical instruments include an inductively coupled plasma mass spectrometer (9), an isotope ratio mass spectrometer (10), an X-ray fluorescence spectrometer (11), and an atomic absorption spectrometer (12), which are used to perform precise water quality analysis on saline water samples, detect tracer concentration, isotope ratio and related ion content in the samples, and capture water quality parameter anomalies caused by CO2 microleakage. The data processing and early warning system is electrically connected to the analytical instrument and is used to receive water quality analysis data. Based on the variation patterns of tracer concentration and isotope ratio in the water body, combined with the water quality benchmark parameters of the saline aquifer, it determines whether CO2 micro-leakage has occurred and issues an early warning in a timely manner.

2. The isotope-tracer based early warning of saline aquifer CO2 microseepage according to claim 1, wherein: The air compressor (1) is sealed to the air inlet of the tracer storage tank (2) through a high-pressure corrosion-resistant pipe. The inner wall of the high-pressure corrosion-resistant pipe is coated with a nano-coating to prevent the pipe from corroding and generating impurities that pollute the saline water layer, thus ensuring the accuracy of water quality monitoring.

3. The isotope-tracer based early warning of saline aquifer CO2 microseepage according to claim 1, wherein: The outlet of the injection pump (3) is connected to the return pipe of the tracer storage tank (2) and the main CO2 injection pipe through a three-way connector. The pipe connecting the outlet of the tracer storage tank (2) and the inlet of the injection pump (3) is equipped with a flow regulating valve, which can accurately control the amount of tracer injected, ensure that the initial concentration of tracer in the saline water layer is uniform, and provide a stable benchmark for water quality tracer analysis.

4. The isotope-tracer based early warning of saline aquifer CO2 microseepage according to claim 3, wherein: A dynamic proportioning valve and a CO2-tracer mixing chamber are installed on the pipeline between the injection pump (3) and the three-way connector. The mixing chamber is equipped with spiral turbulence blades to ensure that the tracer and CO2 are fully mixed before being injected into the saline water body, so as to avoid the local concentration of the tracer being too high or too low and affecting the accuracy of water quality monitoring. The tracer storage tank (2) is equipped with a layered slow-release baffle to realize the slow and stable release of the tracer and maintain the stability of the tracer reference concentration in the saline water body.

5. The isotope-tracer based early warning of saline aquifer CO2 microseepage according to claim 1, wherein: The well casing (4) adopts a carbon steel inner polyethylene sleeve structure and is fixed to the flange of the wellhead device (5) by threaded connection. The connection is filled with epoxy resin mortar to prevent shallow groundwater and surface impurities from seeping into the monitoring well, avoid contaminating the saline water sample, and ensure that the water quality analysis data is true and reliable.

6. The early warning system for CO2 microleakage in saline aquifers based on isotope tracing according to claim 5, characterized in that: The wellhead device (5) is equipped with an explosion-proof junction box on its top. The monitoring interface of the wellhead device (5) is connected to a pressure sensor, a temperature sensor and an isotope concentration detector through a quick connector. It can collect the physicochemical parameters and preliminary isotope detection data of the saline water body in real time, and realize the real-time monitoring of water quality parameters and the preliminary capture of anomalies.

7. The early warning system for CO2 microleakage in saline aquifers based on isotope tracing according to claim 1, characterized in that: The sampler (7) is connected to the sampling port at the bottom of the monitoring well via a heat-resistant and pressure-resistant hose to ensure that the water sample does not come into contact with the outside world and does not experience sudden temperature or pressure changes during the sampling process. The outlet of the sampler (7) is connected to the sample bottle (8) via a connecting pipe. A vacuum isolation valve is installed on the connecting pipe to prevent the sample in the sample bottle (8) from being contaminated, ensuring the integrity of the water sample and meeting the needs of subsequent accurate water quality analysis.

8. The early warning system for CO2 microleakage in saline aquifers based on isotope tracing according to claim 1, characterized in that: The sample vial (8) is connected to the injection chamber of the inductively coupled plasma mass spectrometer via an automated sampler, enabling automated and continuous water quality analysis of water samples and improving analysis efficiency and accuracy. The inductively coupled plasma mass spectrometer (9), isotope ratio mass spectrometer (10), and X-ray fluorescence spectrometer (11) are connected to the central data processing unit via an Ethernet interface, ensuring rapid and lossless transmission of water quality analysis data and providing timely support for subsequent data processing and early warning.

9. The early warning system for CO2 microleakage in saline aquifers based on isotope tracing according to claim 1, characterized in that: The data processing and early warning system includes a computer, data processing software, and an early warning device. The computer, data processing software, early warning device, inductively coupled plasma mass spectrometer (9), isotope ratio mass spectrometer (10), X-ray fluorescence spectrometer (11), and atomic absorption spectrometer (12) are electrically connected to each other. The system can process water quality analysis data in real time and compare it with the reference water quality parameters of the saline water body. When the tracer concentration and isotope ratio show abnormal fluctuations, an early warning is quickly triggered.

10. A source tracing method for early warning of CO2 microleakage in saline aquifers based on isotope tracing, characterized in that, The following steps are included: S1. Water quality data acquisition and preprocessing: Using the monitoring instruments (6) of the monitoring well device, the pressure, temperature and other physicochemical parameters of the water in the saline layer are continuously collected. At the same time, the water samples of the saline layer at different times and locations are quantitatively collected using a sampling device. The water samples are comprehensively analyzed by analytical instruments to obtain data on tracer concentration, isotope ratio and related ion content. The collected water quality data are preprocessed, including cleaning to remove outliers and noise, and normalization to make water quality parameters of different dimensions comparable, providing a reliable water quality data basis for subsequent source tracing analysis. S2. Constructing a Water Quality Source Tracing Model: Based on the geological structure, hydrological characteristics, and historical CO2 injection data of the saline aquifer, and combining the principles of isotope tracing and water quality migration patterns, a CO2 micro-leakage water quality source tracing model suitable for this saline aquifer is constructed. The model should focus on the diffusion and migration patterns of tracers in the saline aquifer, as well as the correlation between changes in tracer concentration and isotope ratios at different locations and time points and the CO2 micro-leakage source. The model is trained and validated using known CO2 injection experimental or simulated water quality data, and the model parameters are adjusted to ensure that it accurately reflects the migration characteristics of tracers and isotopes in the saline aquifer, thereby improving the accuracy of source tracing. S3. Micro-leakage source location and water quality source tracing analysis: Pre-treated water quality data is input into the source tracing model. Through model calculation and analysis, based on the abnormal variation range of tracer concentration and isotope ratio in the water body, the possible location area of ​​CO2 micro-leakage is determined, and the micro-leakage source is initially located. Combining the geological structure of the saline aquifer, hydrological flow path, and water quality anomaly distribution characteristics, a detailed analysis of the preliminary location results is conducted. Taking into account factors such as leakage path and causes, the final micro-leakage source is determined, and the potential impact of the micro-leakage on the surrounding saline aquifer water quality and ecological environment is assessed. S4. Source Tracing Result Verification and Model Dynamic Update: The source tracing analysis results are verified using methods such as on-site investigation and supplementary monitoring. For example, borehole sampling is conducted at suspected micro-leakage sources, and water samples are re-tested. The test results are compared with the tracer concentration and isotope ratio predicted by the model to verify the accuracy of the source tracing results. As time progresses and new water quality monitoring data is acquired, the water quality source tracing model is continuously updated and optimized to adapt to changes in the saline aquifer environment and the evolution of CO2 micro-leakage, improving the reliability and accuracy of subsequent source tracing analyses.

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