Gas-water interface monitoring method, device and equipment in salt cavern energy storage project

Abstract

The invention provides a gas-water interface monitoring method, device and equipment in a salt cavern energy storage project, and the method integrates a resistivity detection module, an audio density detection module and a magnetic positioning detection module into a single underground unit, does not need a central tubular column, and can synchronously collect three parameters only through one-time well descending. The depth reference of the casing shoe is accurately determined through magnetic positioning, the position of the gas-water interface is comprehensively calculated through complementary verification of two-parameter sudden change points of resistivity and density, and the measurement error of a single method is effectively eliminated. According to the method and the corresponding device and equipment, high-precision positioning of the gas-water interface is achieved, the monitoring efficiency is remarkably improved, the operation complexity and cost are greatly reduced, and reliable technical support is provided for safe and efficient operation of gas sealing of a salt cavern energy storage project.

Description

Technical Field

[0001] This invention relates to the field of underground energy storage engineering technology, and in particular to a method, device and equipment for monitoring the gas-water interface in salt cavern energy storage projects. Background Technology

[0002] Against the backdrop of large-scale grid connection of new energy sources and energy structure transformation, salt cavern energy storage has become one of the key technologies for ensuring the balance of energy supply and demand due to its advantages such as large storage capacity, good sealing performance, and low operating costs. The core of salt cavern energy storage projects lies in the injection and extraction of gases (such as natural gas and air) through injection and production wells. Its gas sealing performance directly determines the energy storage efficiency and project safety. Among these, the location and dynamic fluctuation monitoring of the gas-water interface are the core links in gas sealing detection, and abnormal fluctuations often indicate the risk of gas leakage.

[0003] Early monitoring of the gas-water interface in salt caverns relied primarily on single logging techniques, such as resistivity logging (utilizing the difference in resistivity between gas and water) or audio density logging (based on the difference in density between gas and water). However, these single methods are susceptible to interference from impurities within the salt cavern (such as mud, sand, and salt rock debris), resulting in insufficient accuracy. With technological advancements, the industry has attempted a comprehensive approach combining multiple logging methods with a central tubing string. This involves pre-installing a central tubing string to fix the logging equipment, enabling multi-parameter measurements. However, this approach requires additional investment in the tubing string, and the installation and removal of the string are complex, with a single monitoring cycle lasting 2-3 days, making it difficult to meet the demands of dynamic monitoring.

[0004] Existing technologies suffer from the following drawbacks: 1) Insufficient accuracy, susceptible to interference from fluid composition, impurities, or lack of depth reference; 2) Complex operation, involving the insertion and retrieval of the central tubing string, resulting in high risk; 3) Low efficiency, with long single monitoring cycles or the need for multiple well runs; 4) High cost, with the central tubing string and related operating costs accounting for a large proportion; 5) Poor adaptability, struggling to accommodate different wellbore sizes and complex downhole environments. Therefore, there is an urgent need in this field for a high-precision, low-cost, high-efficiency, easy-to-operate, and highly adaptable gas-water interface monitoring technology. Summary of the Invention

[0005] The purpose of this invention is to provide a method, device, and equipment for monitoring the gas-water interface in salt cavern energy storage projects. The aim is to achieve multi-parameter synchronous measurement without the need for a central tubing string and with a single well run, thereby achieving high-precision positioning of the gas-water interface, rapid monitoring of dynamic fluctuations, and significant cost reduction.

[0006] According to one objective of the present invention, the present invention provides a method for monitoring the gas-water interface in salt cavern energy storage projects, comprising the following steps: S1. The downhole logging unit, which integrates a resistivity detection module, an audio density detection module, and a magnetic positioning module, is lowered into the injection-production well via a cable. During the lowering process, measurements are taken simultaneously to obtain resistivity data, fluid density data, and magnetic positioning data, and depth information is recorded. S2. Determine the depth reference H0 of the sleeve shoe based on the magnetic positioning data; S3. Based on the resistivity data and fluid density data, identify the resistivity abrupt change point depth H1 and the density abrupt change point depth H2 respectively; S4. Based on the depth reference H0, and combined with the resistivity change point depth H1 and the density change point depth H2, the gas-water interface depth H is calculated comprehensively. S5. Based on the gas-water interface depth H obtained from multiple measurements, perform dynamic fluctuation monitoring and analysis, and trigger an alarm when the fluctuation exceeds the threshold.

[0007] Furthermore, the specific steps for calculating the gas-water interface depth H are as follows: Determine whether the absolute difference between the resistivity abrupt change point depth H1 and the density abrupt change point depth H2 is less than or equal to a preset threshold. If so, then the gas-water interface depth H = (H1+H2) / 2; If not, the depth H of the gas-water interface is determined by correcting the resistivity abrupt change point depth H1 and / or density abrupt change point depth H2 based on the known morphological parameters of the salt cavern.

[0008] Furthermore, the preset threshold is 0.5 meters.

[0009] Furthermore, in S5, the steps for dynamic fluctuation monitoring and analysis include: The process of releasing and calculating is repeated at a preset time cycle to obtain the gas-water interface depth Ht at different time points. Based on Ht at multiple time points, a fluctuation curve of the gas-water interface depth changing with time is generated, and the fluctuation amplitude ΔH is calculated. An alarm signal is triggered when the fluctuation amplitude ΔH exceeds the preset alarm threshold.

[0010] Furthermore, the alarm threshold is 0.5 meters per circumference.

[0011] Furthermore, the cable is lowered at a speed of 0.1-2 meters per minute; and / or, the data sampling frequency of the resistivity detection module, the audio density detection module, and the magnetic positioning module is not less than 100 Hz.

[0012] According to another objective of the present invention, the present invention provides a gas-water interface monitoring device for salt cavern energy storage projects, which implements the above-described gas-water interface monitoring method in salt cavern energy storage projects, comprising: The downhole logging unit includes a housing, and a resistivity detection module, an audio density detection module, a magnetic positioning module, a data acquisition and transmission module, a power supply module, and a centralizer disposed within the housing; The surface processing unit is connected to the downhole logging unit via a cable and includes a data receiving device, a data processing system, and a display and storage unit. The data processing system is configured to perform: determining the depth reference H0 based on magnetic positioning data, identifying the depths of resistivity abrupt change points H1 and density abrupt change points H2, and comprehensively calculating the gas-water interface depth H.

[0013] Furthermore, the centralizer consists of 2 to 4 elastic centralizers, symmetrically distributed along the axial direction of the outer shell; the magnetic positioning module includes a permanent magnet with a magnetic field strength of not less than 5000 Gs; the data acquisition and transmission module includes an AD converter with a sampling frequency of not less than 100 Hz and an optical fiber transmission unit with a transmission rate of not less than 1 Mbps.

[0014] Furthermore, the data processing system is further configured to perform dynamic fluctuation monitoring and analysis, including generating a curve of the gas-water interface depth changing over time, calculating the fluctuation amplitude, and triggering an alarm when the fluctuation amplitude exceeds the limit.

[0015] According to a third objective of the present invention, the present invention provides a gas-water interface monitoring device for salt cavern energy storage projects, comprising: The aforementioned gas-water interface monitoring device for salt cavern energy storage projects; A cable winch for retrieving and releasing the cable, the cable winch being equipped with a depth counter and having an adjustable lowering speed in the range of 0.1-2 meters per minute; A wellhead airtight connector is used to achieve a sealed connection between the cable and the wellhead of the injection / production well.

[0016] This invention integrates three logging methods—resistivity, audio density, and magnetic positioning—in a single downhole simultaneous measurement operation. Magnetic positioning provides a precise depth reference for interface measurement, fundamentally solving the systematic bias caused by the lack of casing shoe positioning in traditional methods. The resistivity and density parameters complement each other to verify the gas-water interface, effectively overcoming signal distortion and misjudgment caused by downhole impurities and fluid property changes in single-method approaches. This significantly reduces the overall positioning error to within 0.5 meters, greatly improving monitoring accuracy. This solution eliminates the expensive and bulky central tubing used in traditional integrated logging, simplifying equipment structure and construction procedures. It shortens the single monitoring cycle from 2-3 days to within 4 hours, significantly reducing operator requirements and equipment costs. This provides an efficient, economical, and reliable technical means for frequent, dynamic monitoring of salt cavern energy storage. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a flowchart illustrating the monitoring method according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the downhole logging unit according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the composition of the ground processing unit according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure used in an embodiment of the present invention.

[0019] In the diagram: 1. Outer shell; 2. Resistivity detection module; 3. Audio density detection module; 4. Magnetic positioning module; 5. Data acquisition and transmission module; 6. Power supply module; 7. Centralizer; 8. Armored fiber optic cable. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0021] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] Example 1 like Figure 1 As shown, a method for monitoring the gas-water interface in a salt cavern energy storage project includes the following steps: S1. The downhole logging unit, which integrates a resistivity detection module, an audio density detection module, and a magnetic positioning module, is lowered into the injection-production well via a cable. During the descent process, the resistivity detection module, the audio density detection module, and the magnetic positioning module simultaneously perform measurements to obtain resistivity data, fluid density data, and magnetic positioning data, and simultaneously record depth information; S2. In the ground processing unit, the depth reference H0 of the sleeve shoe is determined based on the magnetic positioning data; S3. Based on the resistivity data and fluid density data, identify the resistivity abrupt change point depth H1 and the density abrupt change point depth H2 respectively; S4. Based on the depth reference H0, and combined with the resistivity change point depth H1 and the density change point depth H2, the gas-water interface depth H is calculated comprehensively. S5. Based on the gas-water interface depth H obtained from multiple measurements, perform dynamic fluctuation monitoring and analysis, and trigger an alarm when the fluctuation exceeds the threshold.

[0024] Specifically, in S4, the steps for comprehensively calculating the gas-water interface depth H include: Determine whether the absolute difference between the resistivity abrupt change point depth H1 and the density abrupt change point depth H2 is less than or equal to a preset threshold. If so, then the gas-water interface depth H = (H1+H2) / 2; If not, the depth H of the gas-water interface is determined by correcting the resistivity abrupt change point depth H1 and / or density abrupt change point depth H2 based on the known morphological parameters of the salt cavern.

[0025] In this embodiment, the preset threshold is 0.5 meters.

[0026] Specifically, step S5, the dynamic fluctuation monitoring and analysis steps include: The process of releasing and calculating is repeated at a preset time cycle to obtain the gas-water interface depth Ht at different time points. Based on Ht at multiple time points, a fluctuation curve of the gas-water interface depth changing with time is generated, and the fluctuation amplitude ΔH is calculated. An alarm signal is triggered when the fluctuation amplitude ΔH exceeds the preset alarm threshold.

[0027] In this embodiment, the alarm threshold is 0.5 meters per circumference.

[0028] Specifically, in this embodiment, the cable is lowered at a speed of 0.1-2 meters per minute.

[0029] The data sampling frequency of the resistivity detection module, the audio density detection module, and the magnetic positioning module is not less than 100Hz.

[0030] Example 2 like Figure 2 , Figure 3 and Figure 4 As shown, this embodiment provides a gas-water interface monitoring device for salt cavern energy storage projects to implement the monitoring method of Embodiment 1, including a downhole logging unit and a surface processing unit, wherein: The downhole logging unit includes: shell; The resistivity detection module, audio density detection module, and magnetic positioning module are housed within the casing. The data acquisition and transmission module is used to simultaneously acquire signals from the resistivity detection module, the audio density detection module, and the magnetic positioning module, and to transmit the data. The power supply module is used to supply power to each of the modules; A centralizer, located on the outside of the casing, is used to center the downhole logging unit within the wellbore. The surface processing unit is connected to the downhole logging unit via a cable. The surface processing unit includes: Data receiving equipment, used to receive data transmitted from downhole; The data processing system is used to process data, perform operations such as determining the depth reference H0 based on magnetic positioning data, identifying the depth H1 of resistivity change point and the depth H2 of density change point, and comprehensively calculating the gas-water interface depth H, and performing dynamic fluctuation monitoring and analysis. The display and storage unit is used to display processing results and store data.

[0031] Specifically, in the downhole logging unit: The centralizer is an elastic centralizer, and there are 2 to 4 centralizers symmetrically distributed along the axial direction of the outer shell. The outer shell is made of titanium alloy, specifically TC4 titanium alloy, and its pressure resistance is not less than 60 MPa.

[0032] The resistivity detection module includes a power supply electrode and a measuring electrode, sharing a single pair of electrodes with a spacing of 50 mm between them. The audio density detection module has an audio emission frequency range of 20-50 kHz. The magnetic positioning module includes a permanent magnet and a magnetic flux sensor; the magnetic field strength of the permanent magnet is not less than 5000 Gs.

[0033] The data acquisition and transmission module includes an AD converter and an optical fiber transmission unit. The sampling frequency of the AD converter is not less than 100Hz, and the transmission rate of the optical fiber transmission unit is not less than 1Mbps.

[0034] The power supply module is a high-temperature resistant lithium battery pack.

[0035] Specifically, in the ground processing unit, the data processing system performs dynamic fluctuation monitoring and analysis, including: generating a curve of the gas-water interface depth changing over time, calculating the fluctuation amplitude, and triggering an alarm when the fluctuation amplitude exceeds the limit.

[0036] Example 3 This embodiment provides a gas-water interface monitoring device for salt cavern energy storage projects, including the monitoring device in embodiment 2, and further comprising; A cable winch is used to retrieve and deploy the cable connecting the downhole logging unit and the surface processing unit. The cable winch is equipped with a depth counter. Wellhead airtight connectors are used to achieve a sealed connection between the cable and the wellhead of the injection / production well.

[0037] It also includes calibration standards, which include standard resistance and standard density fluids.

[0038] The cable winch's lowering speed is adjustable from 0.1 to 2 meters per minute.

[0039] Example 4 This embodiment provides a non-transitory computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the monitoring method of Embodiment 1.

[0040] Example 5 like Figure 1 As shown in the figure, this embodiment provides a specific method for monitoring the gas-water interface in a salt cavern energy storage project, including the following steps: Preliminary preparations: Clean the wellbore to ensure unobstructed flow. Calibrate the resistivity module using standard resistance gauges (10 Ω·m, 50 Ω·m) and a standard density fluid (0.5 g / cm³). 3 1.0g / cm 3) Calibrate the audio density module. Connect the downhole logging unit to the surface processing unit.

[0041] Downhole Measurement: Start the cable winch and lower the downhole logging unit at a speed of 0.5-1 m / min. During the lowering process, the resistivity, audio density, and magnetic positioning modules work synchronously, with data sampled at a frequency of 100Hz and transmitted to the surface in real time via armored fiber optic cable. The winch's depth counter records depth information synchronously (accuracy ±0.05m).

[0042] Data processing and interface judgment: The ground software receives the data and first determines the depth H0 of the casing shoe (e.g., 100.05m) based on the abrupt change point of the magnetic positioning signal.

[0043] Analyze the resistivity and density curves to identify the resistivity abrupt change point depth H1 (e.g., 105.25 m) and the density abrupt change point depth H2 (e.g., 105.40 m).

[0044] Calculate |H1-H2| = 0.15m<0.5m, then the gas-water interface depth H = (105.25+105.40) / 2 =105.325m.

[0045] Dynamic fluctuation monitoring: Measurements are repeated weekly to obtain a series of interface depth values ​​Ht. Ground-based software generates an Ht (depth-time) fluctuation curve and calculates the fluctuation amplitude ΔH. If ΔH > 0.5 m / week, an audible and visual alarm is triggered, indicating a possible airtightness anomaly.

[0046] Example 6 This embodiment provides a specific gas-water interface monitoring device and equipment for salt cavern energy storage projects, such as... Figure 2 , Figure 3 and Figure 4 As shown, the downhole logging unit in this embodiment includes: Outer shell 1: Made of TC4 titanium alloy, 100mm in diameter and 2.0m in length, with a polytetrafluoroethylene anti-corrosion coating on the surface, and a pressure resistance of ≥60MPa.

[0047] Resistivity detection module 2: Located on the upper part of the shell, with a measurement range of 0.1-100Ω·m and an electrode spacing of 50mm.

[0048] Audio density detection module 3: Located in the middle of the outer casing, with a transmission frequency of 20-50kHz and a density measurement range of 0.1-2.0g / cm³. 3 .

[0049] Magnetic positioning module 4: Located at the bottom of the outer shell, with a magnetic field strength ≥5000Gs, used for positioning the sleeve shoe.

[0050] Data acquisition and transmission module 5: integrates a 16-bit AD converter and an optical fiber transmission unit, with a sampling frequency of 100Hz and a transmission rate of ≥1Mbps.

[0051] Power supply module 6: a heat-resistant lithium battery pack with a capacity of 100Ah.

[0052] Centralizer 7: Three polyurethane elastic centralizers are evenly distributed along the axial direction of the outer shell to ensure that the logging unit is centered.

[0053] The downhole unit is connected to the surface processing unit via armored fiber optic cable 8.

[0054] like Figure 3 As shown, the ground processing unit includes: Data receiving equipment: receives and converts fiber optic signals.

[0055] Data processing system: An industrial computer equipped with dedicated software, which performs benchmark calibration, interface calculations, and dynamic analysis.

[0056] Display and storage unit: A 27-inch display screen is used for display, and data can be stored locally and in the cloud.

[0057] The complete set of equipment in this embodiment also includes auxiliary equipment such as a cable winch (lowering speed adjustable from 0.1 to 2 m / min, depth accuracy ±0.05 m) and a wellhead airtight joint.

[0058] This invention effectively addresses the shortcomings of existing technologies through key technologies such as three-method synergy, column-free integration, synchronous acquisition, and intelligent analysis, providing a reliable guarantee for the safe and efficient operation of salt cavern energy storage.

[0059] This invention offers high measurement accuracy, establishing a precise depth benchmark through magnetic positioning and employing complementary verification using both resistivity and density parameters. The overall positioning error is ≤0.5m, reducing accuracy by over 60% compared to existing technologies. Furthermore, this invention is easy to operate, eliminating the need for a central tubing string. The logging unit is directly lowered into the well via cable, simplifying the construction process by over 50% and requiring only a small number of personnel to operate.

[0060] This invention is highly efficient, simultaneously measuring three parameters in a single well run, with a single monitoring cycle of ≤4 hours, shortening the time by 90% compared to technology with a central tubing string, and supporting high-frequency dynamic monitoring. This invention is also low-cost, eliminating the need for an expensive central tubing string, resulting in high equipment reusability and reducing the cost per well monitoring run by more than 50%.

[0061] This invention boasts strong adaptability, a compact logging unit structure, and resistance to high pressure and high salinity. Its centralizer design allows it to adapt to wellbore sizes and is compatible with various salt cavern projects. Furthermore, this invention possesses strong dynamic monitoring capabilities. Combining rapid measurement with fluctuation analysis algorithms from surface software, it can track interface changes in real time and provide timely warnings of leakage risks.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for monitoring the gas-water interface in a salt cavern energy storage project, characterized in that, Includes the following steps: S1. The downhole logging unit, which integrates a resistivity detection module, an audio density detection module, and a magnetic positioning module, is lowered into the injection-production well via a cable. During the lowering process, measurements are taken simultaneously to obtain resistivity data, fluid density data, and magnetic positioning data, and depth information is recorded. S2. Determine the depth reference H0 of the sleeve shoe based on the magnetic positioning data; S3. Based on the resistivity data and fluid density data, identify the resistivity abrupt change point depth H1 and the density abrupt change point depth H2 respectively; S4. Based on the depth reference H0, and combined with the resistivity change point depth H1 and the density change point depth H2, the gas-water interface depth H is calculated comprehensively. S5. Based on the gas-water interface depth H obtained from multiple measurements, perform dynamic fluctuation monitoring and analysis, and trigger an alarm when the fluctuation exceeds the threshold.

2. The method for monitoring the gas-water interface in salt cavern energy storage projects according to claim 1, characterized in that, The specific steps for calculating the gas-water interface depth H are as follows: Determine whether the absolute difference between the resistivity abrupt change point depth H1 and the density abrupt change point depth H2 is less than or equal to a preset threshold. If so, then the gas-water interface depth H = (H1+H2) / 2; If not, the depth H of the gas-water interface is determined by correcting the resistivity abrupt change point depth H1 and / or density abrupt change point depth H2 based on the known morphological parameters of the salt cavern.

3. The method for monitoring the gas-water interface in salt cavern energy storage projects according to claim 2, characterized in that, The preset threshold is 0.5 meters.

4. The method for monitoring the gas-water interface in salt cavern energy storage projects according to claim 1, characterized in that, In S5, the steps for dynamic fluctuation monitoring and analysis include: The process of releasing and calculating is repeated at a preset time cycle to obtain the gas-water interface depth Ht at different time points. Based on Ht at multiple time points, a fluctuation curve of the gas-water interface depth changing with time is generated, and the fluctuation amplitude ΔH is calculated. An alarm signal is triggered when the fluctuation amplitude ΔH exceeds the preset alarm threshold.

5. The method for monitoring the gas-water interface in salt cavern energy storage projects according to claim 4, characterized in that, The alarm threshold is 0.5 meters per circumference.

6. The method for monitoring the gas-water interface in salt cavern energy storage projects according to claim 1, characterized in that, The cable is lowered at a speed of 0.1-2 meters per minute; and / or the data sampling frequency of the resistivity detection module, the audio density detection module, and the magnetic positioning module is not less than 100 Hz.

7. A gas-water interface monitoring device for salt cavern energy storage projects, used to implement the gas-water interface monitoring method in any one of claims 1-6, characterized in that, include: The downhole logging unit includes a housing, and a resistivity detection module, an audio density detection module, a magnetic positioning module, a data acquisition and transmission module, a power supply module, and a centralizer disposed within the housing; The surface processing unit is connected to the downhole logging unit via a cable and includes a data receiving device, a data processing system, and a display and storage unit. The data processing system is configured to perform: determining the depth reference H0 based on magnetic positioning data, identifying the depth H1 of resistivity abrupt change point and the depth H2 of density abrupt change point, and comprehensively calculating the gas-water interface depth H.

8. The gas-water interface monitoring device for salt cavern energy storage projects according to claim 7, characterized in that, The centralizer consists of 2 to 4 elastic centralizers, symmetrically distributed along the axial direction of the outer shell; the magnetic positioning module includes a permanent magnet with a magnetic field strength of not less than 5000 Gs; the data acquisition and transmission module includes an AD converter with a sampling frequency of not less than 100 Hz and an optical fiber transmission unit with a transmission rate of not less than 1 Mbps.

9. The gas-water interface monitoring device for salt cavern energy storage projects according to claim 7, characterized in that, The data processing system is further configured to perform dynamic fluctuation monitoring and analysis, including generating a curve of the gas-water interface depth changing over time, calculating the fluctuation amplitude, and triggering an alarm when the fluctuation amplitude exceeds the limit.

10. A gas-water interface monitoring device for salt cavern energy storage projects, characterized in that, include: The monitoring device according to any one of claims 7 to 9; A cable winch for retrieving and releasing the cable, the cable winch being equipped with a depth counter and having an adjustable lowering speed in the range of 0.1-2 meters per minute; The wellhead airtight connector is used to achieve a sealed connection between the cable and the wellhead of the injection and production wells.

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