Underground gas storage gas monitoring method and system based on optical fiber spectrum analysis

Abstract

The invention discloses an underground gas storage gas monitoring method and system based on optical fiber spectrum analysis. The method comprises the following steps: S1, optical fiber network deployment: arranging a corrosion-resistant optical fiber sensor network in a gas storage; s2, spectral data acquisition: transmitting light with a specific wavelength to a gas chamber at the tail end of an optical fiber through a Fourier transform infrared spectrometer, and acquiring a transmitted spectrum after interaction of gas and light; s3, spectrum decoupling and concentration calculation: based on a peak pattern fitting algorithm of the Lambert-Beer law, decoupling the infrared spectrum characteristics of the mixed gas, matching a standard spectrum database, and calculating the concentration of each gas component; s4, constructing a three-dimensional gas model: according to the position of the optical fiber sensor and the gas concentration data, establishing a gas migration model to predict a leakage position and a movement direction; according to the method, the trend, the component distribution, the concentration change and the potential leakage risk of the gas in the storage are effectively evaluated, and technical support is provided for the safety, the effectiveness and the economical efficiency of operation of the gas storage.

Description

Technical Field

[0001] The present application relates to the technical field of underground gas storage safety monitoring and operation optimization, and in particular to a gas monitoring method and system for underground gas storage based on optical fiber spectroscopy. Background Art

[0002] As energy demand grows, underground gas storage, as an important energy storage facility, faces severe challenges in safety monitoring. Gas leaks and abnormal composition may occur during operation, posing a threat to its safe operation. In the closed environment of an underground gas storage, it is very difficult to monitor the composition, concentration, and movement direction of gases over a large area. This places very stringent requirements on the sensitivity, flexibility, layout, cost, and size of sensors. Existing technologies have the following drawbacks: Insufficient monitoring accuracy: Existing gas storage monitoring methods struggle to achieve comprehensive, real-time, and accurate monitoring of gas distribution, composition, and concentration within the reservoir. They suffer from limited monitoring range, slow response, and low measurement accuracy. Traditional gas monitoring methods (such as electrochemical sensors) are limited in sensitivity and selectivity, making it difficult to accurately identify mixed gas components and low-concentration leaks. Poor real-time performance: Offline sampling and laboratory analysis cannot meet dynamic monitoring needs, resulting in delayed leak warnings; Deployment difficulties: The gas storage environment is complex (high pressure, high temperature, corrosive), conventional sensors are prone to failure, and there is a lack of fiber optic sensor designs that can adapt to the complex geological environment and gas composition of gas storage. Furthermore, it is difficult to cover a large monitoring area. Weak multi-parameter decoupling capability: Gas spectral signals are easily affected by temperature and pressure interference, and there is a lack of effective algorithms to eliminate cross-influence, resulting in large concentration inversion errors; Lack of three-dimensional visualization: It is impossible to build a gas distribution model of the gas storage reservoir in real time, making it difficult to track the leakage source and the direction and distribution pattern of gas movement, and it is impossible to effectively warn of risks such as gas leakage and gas crossflow.

[0003] The lack of reliability verification and lifespan assessment methods suitable for the long-term operating environment of gas storage facilities makes it difficult to ensure the long-term stability and reliability of monitoring systems. Existing gas migration models are also difficult to effectively verify and optimize using existing technologies: existing gas migration models typically rely on laboratory experiments or numerical simulations, lacking sufficient actual formation data for verification and optimization. Traditional monitoring technologies struggle to deploy high-density sensor networks within gas storage facilities, making it difficult to obtain sufficiently detailed gas distribution information. This makes it difficult to assess the accuracy and reliability of gas migration models, limiting their optimization and application. Summary of the Invention

[0004] To address the above-mentioned issues, the present application provides a method and system for underground gas storage gas monitoring based on fiber optic spectroscopy analysis. This method can be used for real-time, three-dimensional monitoring of the operating status of underground gas storage, enabling effective assessment of the gas flow, composition distribution, concentration changes, and potential leakage risks within the storage, thereby providing technical support for the safety, effectiveness, and economy of gas storage operations. The technical solution is as follows: In a first aspect, the present application provides a method for monitoring gas in an underground gas storage reservoir based on optical fiber spectroscopy, comprising the following steps: S1: Fiber optic network deployment: A corrosion-resistant fiber optic sensor network is deployed within the gas storage facility. The optical fibers are extended to the target monitoring area of ​​salt caverns, artificial chambers, or depleted oil and gas reservoirs through kink-resistant hoses or bionic motion mechanisms. The optical fibers are coated with a salt-resistant and high-temperature resistant anti-corrosion coating or a protective jacket made of a salt-resistant and high-temperature resistant anti-corrosion material. S2: Spectral data acquisition: A Fourier transform infrared spectrometer is used to transmit light of a specific wavelength to the gas chamber at the end of the optical fiber. The gas chamber is an open-circuit, closed-circuit, or multi-pass reflection structure, and the transmission spectrum after the interaction between the gas and the light is collected; S3: Spectral decoupling and concentration calculation: Based on the peak fitting algorithm of Lambert-Beer law, the infrared spectral characteristics of the mixed gas are decoupled, matched with the standard spectral database, and the concentration of each gas component is calculated; S4: Construction of a three-dimensional gas model: Based on the fiber optic sensor position and gas concentration data, an interpolation algorithm is used to generate a three-dimensional gas distribution cloud map of the gas storage reservoir, and a gas migration model is established to predict the leakage location and movement direction.

[0005] For example, in the underground gas storage gas monitoring method based on fiber optic spectroscopy provided in one embodiment, in step S1, the bionic motion mechanism is a serpentine hose device, which realizes the turning and extension of the optical fiber in the salt cavern by alternating contraction and extension, and the optical fiber layout spacing is 10-50 cm.

[0006] For example, in the underground gas storage gas monitoring method based on fiber spectroscopy provided in one embodiment, in step S2, the multi-pass reflective gas chamber is built with at least 3 groups of reflectors, the optical path length is ≥5m, and the gas detection sensitivity is ≤1ppm.

[0007] For example, in the underground gas storage gas monitoring method based on fiber spectroscopy provided in one embodiment, in step S3, the peak fitting algorithm optimizes the spectral matching accuracy through a neural network (such as a convolutional neural network CNN), and the concentration inversion error is ≤2%.

[0008] For example, in the underground gas storage gas monitoring method based on fiber optic spectroscopy provided in one embodiment, in step S4, the gas migration model is combined with the fluid mechanics equation and the measured concentration gradient to predict the leakage location with a positioning accuracy of ≤0.5m.

[0009] A second aspect of the present application provides an underground gas storage gas monitoring system based on optical fiber spectroscopy, comprising: Fiber optic deployment module: including anti-bend hose, bionic motion mechanism and anti-corrosion coating processing unit; Spectral acquisition unit: integrated with Fourier transform infrared spectrometer FTIR, gas chamber and light source; Data processing platform: equipped with peak fitting algorithm, three-dimensional interpolation model and gas migration prediction module; Early warning terminal: used to output leakage location, concentration exceeding standard alarm and gas movement direction prediction results.

[0010] For example, in the underground gas storage gas monitoring system based on optical fiber spectroscopy provided in one embodiment, the gas chamber adopts a hollow-core optical fiber structure, and the gas and light directly interact with each other in the hollow core.

[0011] For example, in the underground gas storage gas monitoring system based on fiber spectral analysis provided in one embodiment, the data processing platform also includes a spectrum zeroing unit for eliminating fiber optic transmission loss and environmental noise, and the data signal-to-noise ratio is ≥40dB.

[0012] For example, in the underground gas storage gas monitoring system based on fiber spectroscopy provided in one embodiment, the early warning terminal is connected to the gas storage injection and production control system, and automatically adjusts the injection and production rate or triggers the emergency shutdown procedure according to the leakage early warning signal.

[0013] For example, in the underground gas storage gas monitoring system based on optical fiber spectroscopy provided in one embodiment, the anti-corrosion coating is a polyimide-silicon carbide composite material.

[0014] Some embodiments of the present application provide a method and system for underground gas storage gas monitoring based on fiber optic spectroscopy analysis. The method and system are suitable for using fiber optic sensors to monitor the cavity wall deformation, temperature distribution, and gas leakage of salt cavern gas storage in real time and online during the construction and operation process, providing technical support for the safe operation of salt cavern gas storage. The beneficial effects brought about are: (1) High-precision spectral analysis: Based on Fourier transform infrared spectrometer (FTIR) and peak fitting algorithm, accurate identification and concentration calculation of mixed gas components are achieved.

[0015] (2) Adaptive fiber optic deployment: The use of anti-bend hoses and bionic motion mechanisms ensures the flexible deployment and long-term stability of optical fibers in complex gas storage environments.

[0016] (3) Three-dimensional dynamic monitoring: Combining interpolation algorithms with gas migration models to generate real-time gas distribution cloud maps and predict leakage locations and movement directions.

[0017] (4) Strong anti-interference ability: Through spectrum zeroing technology and corrosion-resistant coating design, it eliminates optical fiber transmission loss and environmental interference, and improves data reliability.

[0018] (5) Intelligent early warning and control: Integrate the linkage function of the injection and production control system to achieve automatic response to leakage risks and ensure the safe operation of the gas storage facility. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 This is a flow chart of the underground gas storage gas monitoring method based on fiber optic spectroscopy analysis in this application; Figure 2 Schematic diagram of the multi-pass reflection air chamber structure. DETAILED DESCRIPTION

[0021] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0022] The first aspect of the present application provides a method for monitoring gas in an underground gas storage reservoir based on optical fiber spectroscopy. Figure 1 As shown, the following steps are included: S1: Fiber optic network deployment: A corrosion-resistant fiber optic sensor network is deployed within the gas storage facility. The optical fibers are extended through kink-resistant hoses or biomimetic motion mechanisms to target monitoring areas in salt caverns, artificial chambers, or depleted oil and gas reservoirs. The optical fibers are coated with a salt-resistant and high-temperature resistant anti-corrosion coating or a protective jacket made of salt-resistant and high-temperature resistant anti-corrosion material. Through the deployment of a corrosion-resistant fiber optic network, spectral data acquisition, and three-dimensional model construction, full-process monitoring of gas composition, concentration, and movement direction in the gas storage facility is achieved, covering various gas storage types such as salt caverns and artificial chambers. Specifically, gas storage facilities primarily include salt caverns, artificial chambers, and depleted oil and gas reservoirs. ① In salt caverns: Optical fibers are lowered from the wellbore to measure all gas data within their extended range. Alternatively, flex-resistant optical fibers can be placed in jointed tubes. After extending down the wellbore into the salt cavern, the joints are controlled to allow the fiber to turn. For example, a flexible hose device, similar to a snake or worm's bionic locomotion mechanism, achieves movement by alternating contraction and extension. The optical fiber is fixed within the device and moves with it. The serpentine hose device's contraction and extension mechanism (with a spacing of 10-50 cm) overcomes the rigid layout limitations of traditional optical fibers, adapts to the complex terrain of salt caverns, and increases monitoring coverage density. A small mobile device is added to the fiber's head. ② In artificial chambers: Optical fibers can be placed at any suitable location within the chamber.

[0023] In addition, due to the highly corrosive environment of salt caverns, effective anti-corrosion measures should be taken before deployment, such as selecting corrosion-resistant fiber coatings, using corrosion-resistant adhesives and anchors, etc. Sharp bends in optical fibers should be avoided, or bend-resistant optical fibers should be used.

[0024] S2: Spectral data acquisition: A Fourier transform infrared spectrometer is used to transmit light of a specific wavelength to the gas chamber at the end of the optical fiber. The gas chamber is an open-circuit, closed-circuit, or multi-pass reflection structure, and the transmission spectrum after the interaction between the gas and the light is collected; Among them, the multi-pass reflection chamber structure is as follows Figure 2 As shown, an optical fiber coated with a gas-sensitive material is arranged in the gas chamber. By arranging multiple reflectors in the gas chamber, the propagation distance of light in the gas is increased, thereby improving the measurement sensitivity. A gas port is provided on the outer wall of the gas chamber, and the gas port is a large air hole to ensure fluidity, a breathable membrane to ensure sealing, or a micropore; a compartment is provided in the gas chamber, and the compartment is equipped with a device for emitting and receiving light in the optical fiber, and the angle of light emission can be adjusted to ensure that the other end receives it. After the optical fiber leaves the gas chamber, it is wrapped with an optical fiber membrane and connected to the gas analyzer on the well. The multi-path reflection gas chamber has at least 3 sets of reflectors built in, the optical path length is ≥5m, and the gas detection sensitivity is ≤1ppm. The built-in ≥3 sets of reflectors (optical path ≥5m) significantly enhances the intensity of the interaction between light and gas, and the detection sensitivity is increased to 1ppm, which is suitable for trace gas monitoring; Specifically, light from a light source is transmitted via optical fiber to the gas measurement area. After the light interacts with the gas, the transmitted light is then transmitted back through the optical fiber to the spectrometer for analysis. Downhole, light is used to illuminate the gas and collect spectra: ① Open-path gas chamber: An open gas chamber is placed at the end of the optical fiber (or anywhere along the fiber; or various locations are tested as the cavity is formed and the fiber is extended; or the fiber is enclosed in a housing that allows the fiber to extend and retract within the housing). Gas can directly enter the chamber and interact with the light. This method has a simple structure but is susceptible to environmental interference; ② Closed-circuit gas chamber: a closed gas chamber is set on the optical fiber, and the gas chamber is connected to the external gas through a breathable membrane or micropores; this method can reduce environmental interference, but the response speed is slow; ③ Multi-path reflection gas chamber: by setting multiple reflectors in the gas chamber, the propagation distance of light in the gas is increased, thereby improving the measurement sensitivity; ④ Use hollow-core optical fiber to confine light and gas to interact in the same space, thereby increasing the interaction strength between light and gas and improving measurement sensitivity; ⑤ Encapsulate the fiber grating in a breathable membrane, and the gas diffuses through the breathable membrane to the surface of the fiber grating to react with the sensitive material.

[0025] After the optical fiber's gas chamber reaches the desired monitoring location, the existing spectral changes within the fiber are reset. Simultaneously, light from the light source is transmitted through the optical fiber to the gas measurement area. After the light interacts with the gas, the transmitted light is then transmitted back through the optical fiber to the spectrometer for analysis. Furthermore, the spectrum within the fiber can be recorded before the reset, and the fiber can be returned to its original function after the gas test is complete. This allows gas information to be collected without interrupting the original function of the fiber. If changes in gas composition and concentration need to be monitored, a separate optical fiber can be set up to open the gas chamber for a long period of time for detection, or the gas chamber can be opened briefly at a regular interval for monitoring.

[0026] In order to detect mixed gases and their concentrations, this application uses a Fourier transform infrared spectrometer, which is a highly sensitive infrared spectrometer commonly used for the analysis of complex gas mixtures. The measured spectrum is compared with the standard spectrum of known gases to determine the type of gas molecules. The infrared spectrum of gases is unique, and each gas molecule has a specific spectrum. Under certain temperature and pressure conditions, the spectral shape of the infrared spectrum of the mixed gas is also unique.

[0027] S3: Spectral decoupling and concentration calculation: A peak fitting algorithm based on the Beer-Lambert law decouples the infrared spectral characteristics of the mixed gas, matches the standard spectral database, and calculates the concentration of each gas component. The peak fitting algorithm optimizes the spectral matching accuracy through a neural network (e.g., a convolutional neural network (CNN)), and the concentration inversion error is ≤2%.

[0028] Specifically, the concentration of gas molecules is calculated using a peak-shape fitting algorithm based on the Lambert-Beer law. A series of peak shapes in the infrared spectrum of a particular gas at different concentrations has been previously measured. By matching and fitting the spectral data stored in the database with the characteristic spectrum of the measured gas, the concentration of each gas at that location can be determined. The spectrum of the measured mixed gas can be compared with a spectrum that takes all gas components into account to determine the gas components present in the measured mixed gas. These steps can be performed manually or automatically using a designed algorithm.

[0029] S4: Construction of a three-dimensional gas model: Based on the fiber optic sensor position and gas concentration data, an interpolation algorithm is used to generate a three-dimensional gas distribution cloud map of the gas storage reservoir, and a gas migration model is established to predict the leakage location and movement direction. The gas migration model combines fluid mechanics equations with measured concentration gradients to predict the location of the leakage with an accuracy of ≤0.5m.

[0030] Specifically, changes in optical fiber position, gas composition, and concentration data are recorded in real time, calibrating all monitoring data points in three-dimensional space. An algorithm is designed to obtain gas composition and concentration data at unmeasured locations, thereby constructing a cloud map of gas composition and concentration across the entire three-dimensional space. The algorithm also utilizes changes in gas concentration in three-dimensional space to develop a migration model for each gas component. Finally, the system can further predict gas migration direction and monitor leaks and their locations.

[0031] The present invention relates to a method for monitoring gas in underground gas storage facilities based on optical fiber spectroscopy. (1) Comprehensive, real-time and accurate monitoring of gas distribution, composition and concentration inside the gas storage: By deploying a high-density fiber optic sensor network, it is possible to cover the entire spatial range of the gas storage and monitor multiple gas components simultaneously with fast response speed and high measurement accuracy, providing data support for a comprehensive assessment of the operating status of the gas storage.

[0032] (2) Improving the long-term operating capability of optical fiber sensors in the complex environment of gas storage facilities: By adopting new optical fiber sensor designs and packaging materials that are resistant to high pressure, high temperature, and corrosion, the service life of sensors in the harsh environment of gas storage facilities can be extended, thereby improving the reliability of the system.

[0033] (3) Improving the accuracy of gas component concentration inversion: By developing advanced spectral data processing methods, the cross-interference between different gas components can be effectively eliminated, the accuracy of concentration inversion can be improved, and more reliable data support can be provided for the safe operation of gas storage facilities.

[0034] (4) Realize three-dimensional visualization monitoring of gas distribution inside the gas storage reservoir, and provide a basis for early warning of risks such as gas leakage and gas crossflow: By combining the monitoring data of the fiber optic sensor array and three-dimensional visualization technology, a dynamic three-dimensional model of the gas distribution inside the gas storage reservoir can be constructed, and the gas direction and distribution pattern can be visualized, providing a more intuitive basis for early warning of risks such as gas leakage and gas crossflow.

[0035] (5) Providing data support for the verification and optimization of gas migration models and improving the predictive ability and reliability of the models: The actual gas distribution data monitored by the fiber optic sensor array can be used to verify and optimize the gas migration model, improve the predictive ability and reliability of the model, and provide a more accurate basis for the operation optimization of the gas storage facility.

[0036] (6) High-precision, multi-parameter gas composition analysis was achieved: the Fourier transform infrared spectrometer (FTIR) was used, combined with a unique peak fitting algorithm, to perform high-precision quantitative analysis of multiple gas components in the gas storage reservoir, overcoming the difficulties of traditional methods in detecting multiple gases simultaneously and having low measurement accuracy.

[0037] (7) Flexible and diverse gas collection methods are realized: the proposed open-circuit, closed-circuit, multi-pass reflection and hollow-core optical fiber gas collection methods can adapt to different geological environments and monitoring needs. For example, the multi-pass reflection gas chamber can improve the sensitivity of low-concentration gas detection, and the hollow-core optical fiber can enhance the interaction between gas and light.

[0038] (8) Reduced the error caused by optical fiber transmission loss: Through the optical fiber spectrum zeroing technology, the measurement error caused by optical fiber transmission loss and environmental interference is effectively reduced, and the reliability of the system is improved.

[0039] (9) Improved the early warning capability of gas leakage in gas storage facilities: By monitoring the changes in gas concentration and the direction of gas migration, it is possible to promptly detect signs of gas leakage and accurately locate the leakage location, thus providing protection for the safe management of gas storage facilities.

[0040] (10) Ensure the reliability of the monitoring system in the long-term operation environment of the gas storage: Establish a complete sensor reliability verification and life assessment system, including accelerated aging tests, on-site long-term monitoring, etc., to ensure the long-term application of fiber optic sensors in gas storage.

[0041] A second aspect of the present application provides an underground gas storage gas monitoring system based on optical fiber spectroscopy, comprising: Fiber optic deployment module: including anti-bend hose, bionic motion mechanism and anti-corrosion coating processing unit; Spectral acquisition unit: integrated with Fourier transform infrared spectrometer FTIR, gas chamber and light source; Data processing platform: equipped with peak fitting algorithm, three-dimensional interpolation model and gas migration prediction module; Early warning terminal: used to output leakage location, concentration exceeding standard alarm and gas movement direction prediction results.

[0042] The underground gas storage gas monitoring system based on fiber optic spectral analysis in this application integrates fiber optic deployment, multiple sensor units, data processing and early warning terminals to build a closed-loop monitoring system that supports fully automated management from data collection to risk control.

[0043] For example, in one embodiment of the underground gas storage gas monitoring system based on fiber spectroscopy, the gas chamber utilizes a hollow-core fiber structure, allowing gas and light to interact directly within the hollow core. This hollow-core structure confines light and gas to the same space, increasing optical path efficiency by ≥30% and enhancing low-concentration gas detection capabilities.

[0044] For example, in one embodiment of the underground gas storage gas monitoring system based on fiber spectroscopy, the data processing platform also includes a spectrum zeroing unit to eliminate fiber transmission loss and environmental noise, ensuring a data signal-to-noise ratio of 40 dB or higher. Eliminating fiber transmission loss and environmental noise (with a signal-to-noise ratio of 40 dB or higher) ensures the authenticity and reliability of the spectral data.

[0045] For example, in one embodiment of the underground gas storage gas monitoring system based on fiber spectroscopy, the early warning terminal is connected to the gas storage injection and production control system and automatically adjusts the injection and production rate or triggers an emergency shutdown process based on leak warning signals. The early warning terminal and the injection and production system interact in real time, automatically adjusting the injection and production rate or triggering a shutdown based on the leak level, minimizing the risk of accidents.

[0046] For example, in the underground gas storage gas monitoring system based on optical fiber spectroscopy provided in one embodiment, the anti-corrosion coating is a polyimide-silicon carbide composite material. The polyimide-silicon carbide composite material (salt resistance ≥ 10 years, temperature resistance -50°C to 200°C) ensures the long-term stability of the optical fiber in harsh environments and extends the life of the system.

[0047] The fiber-optic sensing-based salt cavern wall deformation and airtightness monitoring system and method of the present application can be used for real-time, three-dimensional monitoring of the operating status of underground gas storage facilities, enabling effective assessment of the gas flow, composition distribution, concentration changes, and potential leakage risks within the facility, thereby providing technical support for the safety, effectiveness, and economy of gas storage operations.

[0048] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for monitoring gas in an underground gas storage facility based on optical fiber spectroscopy, characterized in that: The following steps are involved: S1: Fiber optic network deployment: A corrosion-resistant fiber optic sensor network is deployed within the gas storage facility. The optical fibers are extended to the target monitoring area of ​​salt caverns, artificial chambers, or depleted oil and gas reservoirs through kink-resistant hoses or bionic motion mechanisms. The optical fibers are coated with a salt-resistant and high-temperature resistant anti-corrosion coating or a protective jacket made of a salt-resistant and high-temperature resistant anti-corrosion material. S2: Spectral data acquisition: A Fourier transform infrared spectrometer is used to transmit light of a specific wavelength to the gas chamber at the end of the optical fiber. The gas chamber is an open-circuit, closed-circuit, or multi-pass reflection structure, and the transmission spectrum after the interaction between the gas and the light is collected; S3: Spectral decoupling and concentration calculation: Based on the peak fitting algorithm of Lambert-Beer law, the infrared spectral characteristics of the mixed gas are decoupled, matched with the standard spectral database, and the concentration of each gas component is calculated; S4: Construction of a three-dimensional gas model: Based on the fiber optic sensor position and gas concentration data, an interpolation algorithm is used to generate a three-dimensional gas distribution cloud map of the gas storage reservoir, and a gas migration model is established to predict the leakage location and movement direction.

2. The underground gas storage gas monitoring method based on optical fiber spectroscopy according to claim 1 is characterized in that: In step S1, the bionic motion mechanism is a serpentine hose device, which realizes the turning and extension of the optical fiber in the salt cavern by alternately contracting and extending. The optical fiber is arranged at a spacing of 10-50 cm.

3. The underground gas storage gas monitoring method based on optical fiber spectroscopy according to claim 1 is characterized in that: In step S2, the multi-pass reflective gas chamber has at least three sets of reflective mirrors built in, an optical path length of ≥5m, and a gas detection sensitivity of ≤1ppm.

4. The underground gas storage gas monitoring method based on optical fiber spectroscopy according to claim 1 is characterized in that: In step S3, the peak fitting algorithm optimizes the spectral matching accuracy through a convolutional neural network (CNN), and the concentration inversion error is ≤2%.

5. The underground gas storage gas monitoring method based on optical fiber spectroscopy according to claim 1, characterized in that: In step S4, the gas migration model is combined with the fluid mechanics equation and the measured concentration gradient to predict the leakage position with a positioning accuracy of ≤0.5m.

6. A gas monitoring system for underground gas storage based on fiber optic spectroscopy analysis according to the method of any one of claims 1 to 5, characterized in that: include: Fiber optic deployment module: including anti-bend hose, bionic motion mechanism and anti-corrosion coating processing unit; Spectral acquisition unit: integrated with Fourier transform infrared spectrometer FTIR, gas chamber and light source; Data processing platform: equipped with peak fitting algorithm, three-dimensional interpolation model and gas migration prediction module; Early warning terminal: used to output leakage location, concentration exceeding standard alarm and gas movement direction prediction results.

7. The underground gas storage gas monitoring system based on optical fiber spectroscopy according to claim 6, characterized in that: The gas chamber adopts a hollow core optical fiber structure, and the gas and light directly interact with each other in the hollow core.

8. The underground gas storage gas monitoring system based on optical fiber spectroscopy according to claim 6, characterized in that: The data processing platform also includes a spectrum zeroing unit for eliminating optical fiber transmission loss and environmental noise, and the data signal-to-noise ratio is ≥40dB.

9. The underground gas storage gas monitoring system based on optical fiber spectroscopy according to claim 6, characterized in that: The early warning terminal is connected to the gas storage reservoir injection and production control system, and automatically adjusts the injection and production rate or triggers the emergency shutdown procedure according to the leakage early warning signal.

10. The underground gas storage gas monitoring system based on optical fiber spectroscopy according to claim 6, characterized in that: The anti-corrosion coating is a polyimide-silicon carbide composite material.

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