Method for monitoring health state of plug of underground high-pressure gas storage

Abstract

The invention belongs to the technical field of automation, and particularly discloses an underground high-pressure gas storage plug health state monitoring method, which comprises the following steps: selecting a plurality of monitoring sections on a contact surface of a concrete plug and surrounding rock according to stress field analysis, and respectively arranging monitoring instruments such as a joint meter, a pressure box and an interface displacement meter on the different monitoring sections, key parameters such as gap opening degree, contact pressure and shearing slippage are collected; through setting a parameter reference value and a threshold value, preprocessing and normalization are carried out on collected data, a concrete plug operation comprehensive health index is constructed, the health state of the plug is evaluated in combination with a single parameter change trend, and timely monitoring and effective operation and maintenance management are realized. The monitoring device comprises a joint meter, a pressure box, an interface displacement meter and a data acquisition system, and can fully cover the mechanical behavior of the contact surface and transmit data to a remote monitoring platform in real time. Gas leakage or plug failure can be effectively prevented, and safe operation of the gas storage is guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of automation technology, and in particular, to a method for monitoring the health status of a plug in an underground high-pressure gas storage reservoir. Background Art

[0002] Compressed Air Energy Storage (CAES) is an efficient energy storage technology. Its basic principle is to utilize the surplus electricity during the low load period of the power system. An air compressor is driven by an electric motor to compress air into an underground high-pressure gas storage reservoir, converting electrical energy into the pneumatic potential energy of compressed air for storage. When needed, the compressed air is released to drive a generator to generate electricity to meet the peak shaving demand of the power system. Underground high-pressure gas storage reservoirs usually use deep-buried rock masses as the gas storage space. Plugs need to be set at their entrances or key positions to seal high-pressure gas and withstand the pressure of surrounding rocks. The plugs are generally cast with high-strength concrete, forming a close contact with the surrounding rocks, and need to resist the high-pressure gas inside the gas storage reservoir (usually in the range of 5 - 15 MPa) and the long-term stress of the surrounding rocks.

[0003] During the operation of an underground high-pressure gas storage reservoir for compressed air energy storage, the plug bears periodic high-pressure gas impacts, temperature changes, and dynamic stresses of the surrounding rocks, which are extremely likely to cause problems such as opening and closing, shear slip, or abnormal pressure at the contact surface between the plug and the surrounding rocks. Once the contact surface fails, it may lead to gas leakage, plug cracking, or even the overall instability of the gas storage reservoir, seriously threatening the safety and economic benefits of the system.

[0004] In the prior art, the monitoring of plugs in high-pressure gas storage reservoirs mainly focuses on the measurement of the internal pressure of the gas storage reservoir or the overall displacement, such as monitoring the gas storage pressure through pressure sensors or measuring the overall deformation of the plug through displacement gauges. However, these methods are difficult to directly reflect the complex mechanical behaviors of the contact surface between the plug and the surrounding rocks, such as the opening degree (gap size) of the contact surface, the distribution of contact pressure, and the dynamic changes of key parameters such as shear slip (dislocation displacement). In addition, the special working conditions of high-pressure gas storage reservoirs (such as periodic pressure changes and gas leakage risks) pose higher requirements on the accuracy and reliability of the monitoring system. The existing monitoring means lack pertinence in layout and data analysis and are difficult to meet the requirements of the compressed air energy storage system for safety and stability.

[0005] Therefore, there is an urgent need for a method for monitoring the health status of plugs in underground high-pressure gas storage reservoirs for compressed air energy storage to achieve comprehensive and real-time monitoring of the mechanical state of the contact surface between the plug and the surrounding rocks and ensure the safe operation of the gas storage reservoir. Summary of the Invention

[0006] The object of the present invention is to provide a method for monitoring the health status of a plug in an underground high-pressure gas storage reservoir. By reasonably arranging a variety of monitoring instruments, key parameters such as the opening degree, contact pressure, and shear slip of the contact surface between the plug and the surrounding rock are comprehensively monitored, and a corresponding monitoring data processing and health assessment model is established to achieve timely monitoring and effective operation and maintenance management of the working state of the plug.

[0007] To achieve the above object, the present invention provides the following technical solution: A method for monitoring the health status of a plug in an underground high-pressure gas storage reservoir, comprising:

[0008] On the contact surface between the concrete plug and the surrounding rock, multiple monitoring sections are selected along the length direction of the concrete plug according to stress field analysis;

[0009] On different monitoring sections, multiple monitoring instruments are respectively arranged, and the opening degree of the gap, contact pressure, and shear slip of the contact surface between the concrete plug and the surrounding rock are collected through the monitoring instruments;

[0010] Setting of parameter reference values and thresholds;

[0011] Performing data preprocessing and normalization on the collected opening degree of the gap, contact pressure, and shear slip;

[0012] Constructing a comprehensive health index for the operation of the concrete plug according to the normalized data;

[0013] Based on the comprehensive health index and the real-time change trends of individual parameters, evaluating the health status of the concrete plug, and performing operation and maintenance management according to the evaluation results.

[0014] Further, the monitoring instruments include two crack gauges installed on the first monitoring section, two pressure cells installed on the second monitoring section, and two interface displacement gauges installed on the third monitoring section.

[0015] Further, the monitoring instruments further include a data acquisition system connected to the crack gauges, pressure cells, and interface displacement gauges by wires.

[0016] Further, the crack gauge includes a crack gauge sleeve, a displacement gauge, and an observation cable. During installation, an installation hole is vertically drilled on the surface of the surrounding rock, the crack gauge sleeve is pushed into the installation hole and backfilled tightly, and the displacement gauge is installed in the sleeve and embedded in the concrete plug.

[0017] Further, the pressure cell is installed in a pressure cell installation groove on the surface of the surrounding rock. During installation, rapid-setting cement mortar is covered on the installation base surface, the back plate of the pressure cell is attached to the installation base surface and fixed, and the sensing surface of the pressure cell is in hard contact with the surface of the concrete plug.

[0018] Further, the interface displacement meter includes an interface displacement meter sensor, a guide rod, a fixed anchor plate, a universal joint, a threaded connecting rod, and an anchor bolt. During installation, an installation notch for the interface displacement meter is cut on the surface of the surrounding rock, a hole is drilled and grouted to fix the anchor bolt, the interface displacement meter sensor is installed in the installation notch for the interface displacement meter, and the fixed anchor plate is vertically fixed inside the concrete plug.

[0019] Further, the standard measurement range of the joint meter is 0 - 50 mm, and the resolution is 0.025% FS; the measurement range of the pressure cell is 0 - 15 MPa, and the resolution is 0.04% FS; the standard measurement range of the interface displacement meter is 0 - 50 mm, and the resolution is 0.025% FS.

[0020] Further, the parameter reference value and threshold setting include:

[0021] Gap opening degree G: reference value G base , threshold G th ;

[0022] Contact pressure P: reference value P0, threshold ΔP;

[0023] Shear slip S: reference value S base , threshold S th ;

[0024] Among them, the reference value G base is the opening degree during the design of the concrete plug, and the threshold G th is the opening degree when the concrete plug seal fails; the reference value P0 is the allowable contact pressure during the design of the concrete plug, and ΔP is the allowable fluctuation range; the reference value S base is the shear slip during the design of the concrete plug, and the threshold S th is the shear slip when the concrete plug seal fails.

[0025] Further, data preprocessing and normalization include:

[0026] S3. Monitoring data preprocessing and normalization

[0027] Normalized index S of gap opening degree gap :

[0028]

[0029] When the measured gap opening degree G is equal to the reference value G base , the score is 1; when the gap opening degree G reaches or exceeds the threshold G th , the score drops to 0;

[0030] Normalized index S of contact pressure pressure :

[0031]

[0032] If the difference between the measured contact pressure P and the reference value P0 is greater than or equal to 0, the score is between 0 and 1, and the health score decreases, indicating that the system is under greater stress.

[0033] Shear slip normalization index S shear :

[0034]

[0035] The closer the measured shear slip S is to the reference value S base the safer it is. When the shear slip S approaches the threshold value S th the score tends to 0.

[0036] Furthermore, the decision logic for health status assessment includes:

[0037] When the comprehensive health index H ≥ 0.9, it is in a normal state. At this time, all data are within the designed safety range, the operation is normal, and no operation and maintenance intervention is required.

[0038] When 0.7 ≤ comprehensive health index H < 0.9, it is in a warning state. At this time, there are slight abnormalities, and it is necessary to adjust the operation parameters in a timely manner or arrange on-site inspections.

[0039] When 0.5 ≤ comprehensive health index H < 0.7, it is in a risk state. At this time, the indicators deviate significantly, there are potential safety hazards, and it is necessary to reinforce or adjust the plan.

[0040] When the comprehensive health index H < 0.5, it is in a dangerous state. At this time, it must be immediately shut down or emergency treatment must be carried out.

[0041] Compared with the prior art, the present invention discloses at least the following beneficial effects:

[0042] By reasonably arranging a variety of monitoring instruments (joint meters, pressure cells, interface displacement meters) on the contact surface between the concrete plug and the surrounding rock, it is possible to simultaneously monitor key parameters such as the crack opening degree, contact pressure, and shear slip, comprehensively reflect the mechanical state of the contact surface between the plug and the surrounding rock, overcome the limitation of only monitoring a single parameter in the prior art, and improve the accuracy and comprehensiveness of monitoring. At the same time, the monitoring section is selected based on stress field analysis to ensure that the monitoring points are arranged in the area where the stress changes most significantly, further improving the pertinence and accuracy of monitoring.

[0043] In addition, through real-time data acquisition and processing, and by combining the set parameter reference values and thresholds, the present invention can quickly preprocess and normalize the data, construct a comprehensive health index for the operation of the concrete plug, and realize real-time hierarchical evaluation and early warning of the health status of the plug. Based on the comprehensive health index and the real-time change trends of individual parameters, it provides a scientific decision-making basis for operation and maintenance management, enabling managers to take corresponding measures in a timely manner according to different health statuses, avoiding potential safety accidents, and thus improving the efficiency and scientific nature of operation and maintenance management.

[0044] The present invention can also effectively prevent potential problems that may lead to gas leakage, plug cracking, or overall instability of the gas storage reservoir, enhance the safety and stability of the system, and ensure the reliable operation of the underground high-pressure gas storage reservoir. At the same time, the monitoring data is transmitted to the remote monitoring platform in real time, facilitating managers to grasp the health status of the plug in real time at the monitoring center far from the site, further improving the convenience and timeliness of operation and maintenance management. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0046] Figure 1 It is a schematic diagram of the arrangement of monitoring sensors in the monitoring device of the present invention;

[0047] Figure 2 It is a partial enlarged view of the position where the crack measuring gauge is arranged;

[0048] Figure 3 It is a partial enlarged view of the position where the pressure cell is arranged;

[0049] Figure 4 It is a partial enlarged view of the position where the interface displacement meter is arranged;

[0050] Figure 5 It is a flowchart of the detection method of the present invention;

[0051] In the figure: 1, surrounding rock; 2, concrete plug; 3, crack gauge 1; 4, crack gauge 2; 5, pressure cell 1; 6, pressure cell 2; 7, interface displacement gauge 1; 8, interface displacement gauge 2; 9, first monitoring section; 10, second monitoring section; 11, third monitoring section; 12, installation hole; 13, quick-setting cement mortar; 14, crack gauge sleeve; 15, displacement gauge; 16, observation cable; 17, pressure cell installation notch; 18, pressure cell cable; 19, interface displacement gauge installation notch; 20, foaming material; 21, interface displacement gauge sensor; 22, guide rod; 23, fixed anchor plate; 24, universal joint; 25, threaded connecting rod; 26, anchor bolt; 27, sensor cable. Specific implementation mode

[0052] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0053] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation modes.

[0054] Embodiment 1

[0055] Refer to Figures 1 to 5 As shown, Embodiment 1 of the present invention provides a method for monitoring the health status of a plug in an underground high-pressure gas storage cavern, including the following steps:

[0056] S1. Monitoring system layout and data collection

[0057] In a certain underground gas storage cavern, a section of concrete plug 2 is designed, and the contact length between the concrete plug 2 and the surrounding rock 1 is 15 meters. According to the stress field analysis of the contact surface between the concrete plug 2 and the surrounding rock 1, three monitoring sections are selected along the length direction of the concrete plug 2, namely the first monitoring section 9, the second monitoring section 10, and the third monitoring section 11. Different monitoring instruments are used to collect monitoring data on different monitoring sections. The monitoring data includes the crack opening degree, contact pressure, and shear slip of the contact surface between the concrete plug 2 and the surrounding rock 1.

[0058] In a specific embodiment, 2 crack gauges, 2 pressure cells, and 2 interface displacement gauges are respectively installed on the first monitoring section 9, the second monitoring section 10, and the third monitoring section 11.

[0059] Use the crack gauge 1-3 and the crack gauge 2-4 to measure the opening degree of the contact surface between the concrete plug 2 and the surrounding rock 1 (the size of the contact surface gap), and take the average value of the measured values of the two crack gauges as the opening degree of the contact surface gap to evaluate the high-pressure gas leakage risk.

[0060] Use the pressure cell 1-5 and the pressure cell 2-6 to measure the contact pressure of the contact surface between the concrete plug 2 and the surrounding rock 1, and take the average value of the measured values of the two pressure cells as the contact pressure of the contact surface to monitor the pressure distribution under the action of periodic high-pressure gas.

[0061] Use the interface displacement gauge 1-7 and the interface displacement gauge 2-8 to measure the shear slip of the contact surface between the concrete plug 2 and the surrounding rock 1, and take the average value of the measured values of the two interface displacement gauges as the dislocation displacement of the contact surface to evaluate the stability of the concrete plug 2.

[0062] In a specific embodiment, the monitoring system layout includes:

[0063] S11. Crack gauge layout. The specific layout method is as follows:

[0064] Drill two installation holes 12 perpendicular to the surface of the surrounding rock 1 for installing the crack gauge 1-3 and the crack gauge 2-4. The drilling diameter is 70-90 mm, and the drilling depth should be slightly greater than the length of the crack gauge sleeve 14;

[0065] Backfill an appropriate amount of quick-setting cement mortar 13 into the installation hole 12, and then push the entire crack gauge sleeve 14 into the installation hole 12 and squeeze out the mortar until the outer edge of the crack gauge sleeve 14 is flush with the hole opening of the installation hole 12 to ensure that the backfill between the crack gauge sleeve 14 and the hole wall is dense;

[0066] Install a displacement gauge 15 inside the crack gauge sleeve 14. The displacement gauge 15 is buried in the concrete plug 2. During concrete pouring, manual vibration should be used within a radius of 1 m of the observation cable 16, and mechanical vibration is prohibited;

[0067] The observation cable 16 can be directly buried in the concrete, but attention should be paid to the layout of the cable route to minimize the possibility of cable damage caused by moving construction equipment, gravel edges or other reasons. If necessary, protect the observation cable 16.

[0068] S12. Pressure cell layout. The specific layout method is as follows:

[0069] Cut a circular pressure cell installation notch 17 on the surface of the surrounding rock 1. The diameter of the pressure cell installation notch 17 is 25 cm and the depth is 3 cm;

[0070] Before installation, mortar should be paved and leveled in the area to be installed in advance to form the installation base surface of the pressure cell, and 4 holes with a diameter of 6 mm should be drilled using the hanging ear holes on the pressure cell as a template for installing nylon expansion plugs;

[0071] During installation, a quick-setting cement mortar 13 with sufficient thickness should be covered on the installation base surface. Then, one side of the backplate of the pressure cell should be attached to the installation base surface, and the excess mortar should be extruded from the four sides of the backplate. Then, use the matching screws to fix until the mortar solidifies;

[0072] When pouring the concrete plug 2, it should be ensured that the sensing surface side of the pressure cell is in direct hard contact with the surface of the concrete plug 2, and at the same time, pay attention to protecting the pressure cell cable 18.

[0073] S13. Arrangement of the interface displacement gauge. The specific arrangement method is as follows:

[0074] Cut an interface displacement gauge installation notch 19 on the surface of the surrounding rock 1. The length of the interface displacement gauge installation notch 19 is 50 cm, the width is 10 cm, and the depth is 10 cm;

[0075] Drill a hole and grout to fix the anchor rod 26 on the right side inside the interface displacement gauge installation notch 19. The anchor rod 26 is a threaded steel bar with a diameter of 22 mm × 600 mm. It is recommended that the diameter of the drilled hole is not less than 40 mm. When fixing the anchor rod 26, it should be ensured that the exposed size of the anchor rod 26 is not less than 50 mm;

[0076] Install the interface displacement gauge sensor 21 inside the interface displacement gauge installation notch 19, and connect the right threaded connecting rod 25 of the interface displacement gauge sensor 21 to the fixed anchor rod 26. Note that the lead-out end of the sensor cable 27 should be located on one side of the anchor rod 26 to avoid stretching and damage of the cable due to crossing the sliding guide rod 22;

[0077] After the interface displacement gauge sensor 21 is fixed, ensure that the guide rod 22 is pulled out to a position slightly greater than the 0 mm reading position to make the best use of the sensor range. If it is too large or too small, it can be adjusted by adjusting the fixed height of the fixed anchor plate 23. The fixed anchor plate 23 is vertically fixed inside the concrete plug 2 and the tail is connected to the universal joint 24.

[0078] After all components are installed, fill the notch with foaming material 20 to protect the sensor.

[0079] S14. Connect the crack gauge, pressure cell and interface displacement gauge to the data acquisition system in a wired manner, and the sampling frequency is 10 times per second;

[0080] In a specific embodiment, the data acquisition includes:

[0081] Obtain the opening and closing degree of the crack varying with the gas injection pressure through the crack gauge, combine the contact surface pressure value recorded by the pressure cell, and the shear slip displacement amount collected by the interface displacement gauge, and analyze the comprehensive stress and deformation law of the contact surface between the concrete plug 2 and the surrounding rock 1 under different gas injection stages (such as pressure increase, constant pressure, pressure decrease, etc.);

[0082] Through the data acquisition system, set the sampling frequency (such as once per hour) to collect the measurement data of the joint meter, pressure cell, and interface displacement meter; combine the data of the three sensors, evaluate the coupling relationship of soil stress, interface displacement, and crack change, draw the time-parameter curve, and judge the structural stability.

[0083] S2. Parameter reference value and threshold setting

[0084] Gap opening degree G: reference value G base , threshold G th .

[0085] Contact pressure P: reference value P0, threshold ΔP.

[0086] Shear slip S: reference value S base , threshold S th .

[0087] Among them, the reference value G base is the opening degree during the design of the concrete plug 2, and the threshold G th is the opening degree when the concrete plug 2 fails to seal; the reference value P0 is the allowable contact pressure during the design of the concrete plug 2, and ΔP is the allowable fluctuation range (exceeding this range is regarded as abnormal); the reference value S base is the shear slip during the design of the concrete plug 2, and the threshold S th is the shear slip when the concrete plug 2 fails to seal.

[0088] Specifically, in this embodiment, the parameter reference value and threshold are set as follows:

[0089] Gap opening degree G: reference value G base is 1 mm, and threshold G th is 1.5 mm.

[0090] Contact pressure P: reference value P0 is 15 MPa, and threshold ΔP is 3 MPa.

[0091] Shear slip S: reference value S base is 1 mm, and threshold S th is 1.5 mm.

[0092] S3. Monitoring data preprocessing and normalization

[0093] Normalized index S of gap opening degree gap :

[0094]

[0095] When the measured gap opening degree G is equal to the reference value G base , the score is 1 (optimal state); when the gap opening degree G reaches or exceeds the threshold G thWhen the score drops to 0;

[0096] Contact pressure normalization index S pressure :

[0097]

[0098] If the difference between the measured contact pressure P and the reference value P0 is greater than or equal to 0, the score is between 0 and 1, and the health score decreases, indicating that the system may be under high stress;

[0099] Shear slip normalization index S shear :

[0100]

[0101] The closer the measured shear slip S is to the reference value S base the safer it is. When the shear slip S approaches the threshold S th the score tends to 0.

[0102] S4. Construction of the comprehensive health index for the operation of the concrete plug 2

[0103] To comprehensively evaluate the overall health status of the concrete plug 2, a weighted average method is used to construct the overall health index H. Set S gap , S pressure , S pressure The weights of are W gap , W pressure and W shear , which can be allocated according to the influence degree of each index on safety. For example, in a specific embodiment, set W gap to 0.4, W pressure to 0.3, W shear to 0.3, then:

[0104] H = w gap ·S gap + w pressure ·S pressure + w shear ·S shear

[0105] This H value ranges from 0 to 1. The higher the value, the healthier the state of the concrete plug 2; when H is close to 1, it indicates that all parameters of the concrete plug 2 are within the safe range; when H decreases, it means that at least one or more parameters deviate from the normal working conditions.

[0106] S5. Health assessment of the operation of the concrete plug 2

[0107] Based on the comprehensive health index H and combined with the real-time change trend of the single parameter, the following decision logic is established:

[0108] Logic 1: Normal state (H≥0.9): All data are within the designed safety range, the operation is normal, and no operation and maintenance intervention is required;

[0109] Logic 2: Warning state (0.7≤H<0.9): There are slight anomalies. It is advisable to consider adjusting the operation parameters in a timely manner or arranging on-site inspections; if any index approaches its critical value (for example, the opening degree approaches Gth or the shear slip approaches Sth), preventive measures should be arranged in advance;

[0110] Logic 3: Risk state (0.5≤H<0.7): The indicators deviate significantly, and there may be potential safety hazards in the system; it is recommended to increase the monitoring frequency and formulate targeted reinforcement or adjustment plans, such as reducing the gas storage pressure, local structural reinforcement, etc.;

[0111] Logic 4: Dangerous state (H<0.5): The system is already in a dangerous area, and it must be immediately deactivated or emergency treatment should be carried out, an alarm should be activated and maintenance personnel should be notified.

[0112] Embodiment 1 of the present invention proposes a method for monitoring the health status of a plug in an underground high-pressure gas storage cavern. By selecting three monitoring sections according to stress field analysis on the contact surface between the concrete plug 2 and the surrounding rock 1, and respectively arranging crack gauges, pressure cells, and interface displacement gauges on the three monitoring sections, collecting and analyzing the monitoring data of the crack gauges, pressure cells, and interface displacement gauges, evaluating the health status of the concrete plug 2, and performing operation and maintenance management according to the analysis results to prevent gas leakage or the failure of the concrete plug 2.

[0113] Embodiment 2

[0114] Refer to Figures 1 to 4 As shown, Embodiment 2 of the present invention provides a device for monitoring the health status of a plug in an underground high-pressure gas storage cavern, which is used to execute the method for monitoring the health status of a plug in an underground high-pressure gas storage cavern described in the above embodiment. The device includes crack gauges, pressure cells, and interface displacement gauges arranged on the contact surface between the concrete plug 2 and the surrounding rock 1, and a data acquisition system connected to the crack gauges, pressure cells, and interface displacement gauges by lines. The crack gauges, pressure cells, and interface displacement gauges are respectively arranged on different monitoring sections of the concrete plug 2 and the surrounding rock 1. The crack gauges, pressure cells, and interface displacement gauges are connected to the data acquisition system in a wired manner, and the sampling frequency is set through the data acquisition system, and the measurement data of the crack gauges, pressure cells, and interface displacement gauges are collected to evaluate the coupling relationship between soil stress, interface displacement, and crack change, draw a time-parameter curve, and judge the structural stability.

[0115] Specifically, the crack gauge is used to measure the opening degree of the contact surface between the concrete plug 2 and the surrounding rock 1; the pressure cell is used to measure the pressure of the contact surface between the concrete plug 2 and the surrounding rock 1; the interface displacement gauge is used to measure the shear slip of the contact surface between the concrete plug 2 and the surrounding rock 1.

[0116] In a specific embodiment, two crack meters, two pressure cells, and two interface displacement meters are respectively installed on each monitoring section. Specifically, as Figure 1 shown, crack meter one 3 and crack meter two 4 are symmetrically installed on the first monitoring section 9, pressure cell one 5 and pressure cell two 6 are symmetrically installed on the second monitoring section 10, and interface displacement meter one 7 and interface displacement meter two 8 are symmetrically installed on the third monitoring section 11. The above-mentioned crack meters, pressure cells, and interface displacement meters are respectively arranged at different positions along the contact surface between the concrete plug 2 and the surrounding rock 1 to comprehensively cover the mechanical behavior of the contact surface.

[0117] As Figure 2 shown, the crack meter includes a crack meter sleeve 14, a displacement meter 15, and an observation cable 16. The observation cable 16 is arranged at one end of the displacement meter 15, and the other end of the displacement meter 15 is installed in the sleeve and embedded in the concrete plug 2 together with the sleeve. During installation, an installation hole 12 is vertically drilled on the surface of the surrounding rock 1. The diameter of the installation hole 12 is preferably 70 - 90 mm, and the drilling depth should be slightly greater than the sleeve length. An appropriate amount of quick-setting cement mortar 13 is backfilled in the installation hole 12, and then the crack meter sleeve 14 is fully pushed into the installation hole 12 to extrude the mortar until the outer edge of the sleeve is flush with the hole opening, ensuring that the backfill between the sleeve and the hole wall is dense.

[0118] In a specific embodiment, the crack meter uses a high-precision crack measurement instrument with a standard range of 0 - 50 mm and a resolution of 0.025% FS, which can measure the tiny opening and closing changes of the contact surface in the vertical direction to meet the requirements of the high-pressure gas storage reservoir for gas tightness.

[0119] As Figure 3 shown, the pressure cell is installed in the pressure cell installation notch 17 on the surface of the surrounding rock 1. During installation, a thick enough layer of quick-setting cement mortar 13 is covered on the installation base surface, then one side of the pressure cell backplane is attached to the installation base surface, and the excess mortar is extruded from the four sides of the backplane. Then, it is fixed with the matching screws until the mortar solidifies. The sensing surface of the pressure cell is in hard contact with the surface of the concrete plug 2. The pressure cell has a pressure cell cable 18 led out, and attention must be paid to protecting the pressure cell cable 18 during the installation of the pressure cell.

[0120] Specifically, a pressure cell installation notch 17 is cut on the surface of the surrounding rock 1. The diameter of the pressure cell installation notch 17 is 25 cm and the depth is 3 cm. Mortar is paved and leveled in the pressure cell installation notch 17 to form the installation base surface of the pressure cell. Four Φ6 mm holes are drilled for installing nylon expansion plugs using the ear holes on the pressure cell as a template for lofting, and it is fixed with the matching screws until the mortar solidifies.

[0121] In a specific embodiment, the pressure cell is a high-range circular pressure sensor. A pressure sensor with a range of 0 - 15 MPa and a resolution of 0.04% FS is selected. It can withstand a high pressure of 15 MPa and is embedded between the contact surface of the concrete plug 2 and the surrounding rock 1 for real-time monitoring of the dynamic changes in the contact pressure.

[0122] As Figure 4 shown, the interface displacement meter includes an interface displacement meter sensor 21, a guide rod 22, a fixed anchor plate 23, a universal joint 24, a threaded connecting rod 25, and an anchor bolt 26. One end of the interface displacement meter sensor 21 is connected to the guide rod 22, and the other end is connected to the threaded connecting rod 25. The end of the guide rod 22 away from the interface displacement meter sensor 21 is connected to the fixed anchor plate 23 through the universal joint 24. The end of the threaded connecting rod 25 away from the interface displacement meter sensor 21 is connected to the anchor bolt 26, and the sensor cable 27 is led out.

[0123] Specifically, an interface displacement meter installation notch 19 is cut on the surface of the surrounding rock 1. The length of the interface displacement meter installation notch 19 is 50 cm, the width is 10 cm, and the depth is 10 cm. A hole is drilled and grouted to fix the anchor bolt 26 on the right side in the interface displacement meter installation notch 19. The anchor bolt 26 is a threaded steel bar with a diameter of Φ22 mm and a length of 600 mm. It is recommended that the drilling hole be not less than Φ40 mm. When fixing the anchor bolt 26, it should be ensured that the exposed size of the anchor bolt 26 is not less than 50 mm. The interface displacement meter sensor 21 is installed in the interface displacement meter installation notch 19, and the fixed anchor plate 23 is vertically fixed inside the concrete plug 2 and connected to the universal joint 24 at the tail. After all components are installed, the interface displacement meter installation notch 19 is filled with foaming material 20 around the interface displacement meter sensor 21.

[0124] In a specific embodiment, the interface displacement meter is a high-sensitivity sensor. The standard range of the interface displacement meter is 0 - 50 mm, and the resolution is 0.025% FS. It is fixed to the contact surface between the concrete plug 2 and the surrounding rock 1 for measuring the shear slip in the horizontal direction of the contact surface.

[0125] In a specific embodiment, the monitoring data is transmitted to the remote monitoring platform in real time through the data acquisition system. The remote monitoring platform processes and analyzes the data in combination with the operating conditions of the gas storage reservoir (such as the charging and discharging cycle, pressure change).

[0126] The monitoring method and device of the above embodiment are used to monitor and evaluate the health status of a certain underground gas storage reservoir for many times, and the obtained monitoring data are shown in Table 1 and Table 2:

[0127] Table 1 Monitoring data of a certain time

[0128] parameter monitoring value calculation result opening degree (G) 1.1 mm <![CDATA[S gap = 0.8]]> contact pressure (P) 14 MPa <![CDATA[S pressure = 1]]> shear slip (S) 1.2 mm <![CDATA[S shear = 0.6]]> comprehensive health index (H) / H＝0.8

[0129] As can be seen from Table 1, H = 0.8, which falls into the early warning state range (0.7 ≤ H < 0.9). Therefore, the following operation and maintenance suggestions are given:

[0130] Increase the encryption monitoring frequency and closely monitor the change trend of the contact surface data; appropriately adjust the operating pressure of the gas storage reservoir to reduce the internal pressure load; perform local structural reinforcement when necessary to prevent further slippage or cracking.

[0131] Table 2 Monitoring data of a certain time

[0132] parameter monitoring value calculation result opening degree (G) 0.6 mm <![CDATA[S gap = 1 <!-- 8 -->]]> contact pressure (P) 12 MPa <![CDATA[S pressure = 1]]> shear slip (S) 0.8 mm <![CDATA[S shear = 1]]> comprehensive health index (H) / H＝1

[0133] As can be seen from Table 2, H = 1, which is in the normal state range (H ≥ 0.9), and all data are in an ideal state, so no special operation and maintenance measures are required.

[0134] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0135] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for monitoring the health status of a plug in an underground high-pressure gas storage reservoir, characterized in that, Including: On the contact surface between the concrete plug (2) and the surrounding rock (1), multiple monitoring sections are selected along the length direction of the concrete plug (2) according to stress field analysis; Multiple monitoring instruments are respectively arranged on different monitoring sections, and the gap opening degree, contact pressure, and shear slip of the contact surface between the concrete plug (2) and the surrounding rock (1) are collected through the monitoring instruments; Setting of parameter reference values and thresholds; Performing data preprocessing and normalization on the collected gap opening degree, contact pressure, and shear slip; Constructing a comprehensive operation health index of the concrete plug (2) based on the normalized data; Evaluating the health status of the concrete plug (2) based on the comprehensive health index and the real-time change trends of individual parameters, and performing operation and maintenance management according to the evaluation results.

2. The method for monitoring the health status of the plug of an underground high-pressure gas storage reservoir according to claim 1, characterized in that The monitoring instruments include two crack gauges installed on the first monitoring section (9), two pressure cells installed on the second monitoring section (10), and two interface displacement gauges installed on the third monitoring section (11).

3. The method for monitoring the health status of the plug of the underground high-pressure gas storage reservoir according to claim 2, wherein, The monitoring instruments further include a data acquisition system connected to the crack gauges, pressure cells, and interface displacement gauges by lines.

4. The method for monitoring the health status of the plug in the underground high-pressure gas storage reservoir according to claim 3, characterized in that, The crack gauge includes a crack gauge sleeve (14), a displacement gauge (15), and an observation cable (16). During installation, an installation hole (12) is vertically drilled on the surface of the surrounding rock (1), the crack gauge sleeve (14) is pushed into the installation hole (12) and backfilled tightly, and the displacement gauge (15) is installed in the sleeve and embedded in the concrete plug (2).

5. The method for monitoring the health status of the plug in the underground high-pressure gas storage reservoir according to claim 3, characterized in that, The pressure cell is installed in the pressure cell installation notch (17) on the surface of the surrounding rock (1). During installation, rapid-setting cement mortar (13) is covered on the installation base surface, the back plate of the pressure cell is attached to the installation base surface and fixed, and the sensing surface of the pressure cell is in hard contact with the surface of the concrete plug (2).

6. The method for monitoring the health status of the plug of the underground high-pressure gas storage reservoir according to claim 3, characterized in that, The interface displacement gauge includes an interface displacement gauge sensor (21), a guide rod (22), a fixed anchor plate (23), a universal joint (24), a threaded connecting rod (25), and an anchor rod (26). During installation, an interface displacement gauge installation notch (19) is cut on the surface of the surrounding rock (1), a hole is drilled and the anchor rod (26) is fixed by grouting, the interface displacement gauge sensor (21) is installed in the interface displacement gauge installation notch (19), and the fixed anchor plate (23) is vertically fixed inside the concrete plug (2).

7. The method for monitoring the health status of the plug in the underground high-pressure gas storage reservoir according to claim 3, wherein, The standard measuring range of the crack gauge is 0 - 50 mm, and the resolution is 0.025% FS; the measuring range of the pressure cell is 0 - 15 MPa, and the resolution is 0.04% FS; the standard measuring range of the interface displacement gauge is 0 - 50 mm, and the resolution is 0.025% FS.

8. The method for monitoring the health status of the plug of an underground high-pressure gas storage reservoir according to claim 1, wherein The setting of parameter reference values and thresholds includes: Gap opening degree G: reference value G base , threshold value G th ; Contact pressure P: reference value P0, threshold ΔP; Shearing slip S: reference value S base , threshold value S th ; Among them, the reference value G base is the opening degree during the design of the concrete plug (2), and the threshold value G th is the opening degree when the concrete plug (2) fails to seal; the reference value P0 is the allowable contact pressure during the design of the concrete plug (2), and ΔP is the allowable fluctuation range; the reference value S base is the shear slip during the design of the concrete plug (2), and the threshold value S th is the shear slip when the concrete plug (2) fails to seal.

9. The method for monitoring the health status of the plug of the underground high-pressure gas storage described in claim 8, characterized in that, Data preprocessing and normalization include: S3. Monitoring data preprocessing and normalization Normalized index S of gap opening degree gap : When the measured gap opening degree G is equal to the reference value G base the score is 1; when the gap opening degree G reaches or exceeds the threshold value G th the score drops to 0; Contact pressure normalization index S pressure : If the difference between the measured contact pressure P and the reference value P0 is greater than or equal to 0, the score is between 0 and 1, and the health score decreases, indicating that the system bears greater stress; Shearing slip normalization index S shear : The closer the measured shear slip S is to the reference value S base the safer it is. When the shear slip S approaches the threshold S th the score tends to 0.

10. The method for monitoring the health status of the plug of the underground high-pressure gas storage cavern according to claim 9, characterized in that, The decision logic for health status evaluation includes: When the comprehensive health index H ≥ 0.9, it is in a normal state. At this time, all data are within the designed safety range, the operation is normal, and no operation and maintenance intervention is required; When 0.7 ≤ comprehensive health index H < 0.9, it is in a warning state. At this time, there are slight abnormalities, and it is necessary to adjust the operating parameters in a timely manner or arrange on-site inspections; When 0.5 ≤ comprehensive health index H < 0.7, it is in a risk state. At this time, the indicators deviate significantly, and there are potential safety hazards. It is necessary to reinforce or adjust the plan; When the comprehensive health index H < 0.5, it is in a dangerous state. At this time, it must be immediately deactivated or emergency treatment must be carried out.

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