An online comprehensive monitoring system for the wellbore optical fiber of a salt cavern compressed air energy storage reservoir

Abstract

The present application discloses an online comprehensive monitoring system for a wellbore of a salt cavern compressed air energy storage reservoir using optical fiber, comprising the following modules: a wellbore structure module, comprising a wellbore that passes through the ground to an underground salt cavern cavity, wherein the lower portion of the salt cavern cavity is a brine layer, and the upper portion is a compressed air layer; an optical fiber monitoring module, used to detect the internal situation data of the wellbore; a data transmission and processing module, used to transmit and analyze the data detected by the optical fiber monitoring module; a data display module, used to receive and display the data transmitted by the data transmission and processing module; a user interaction module, used for the user to input commands or parameters in order to control the system; the optical fiber has the advantages of being flameproof, explosion-proof, corrosion-resistant, and anti-interference, so that it can operate safely in a harmful environment, effectively solving the problems of easy corrosion and easy damage existing in other downhole monitoring equipment, providing data support for operation and decision-making, having strong adaptability to the environment of different well conditions, high resolution, and small error.

Description

Technical Field

[0001] The present application relates to the field of optical fiber monitoring, and in particular to an online comprehensive optical fiber monitoring system for a salt cavern compressed air energy storage reservoir wellbore. Background Art

[0002] my country's electricity consumption shows obvious peak-valley characteristics. How to reduce peaks and fill valleys, save energy resources, and effectively improve the peak-shaving capacity of regional power grids is of great significance. Using abandoned salt mines as gas storage and using underground caves such as salt caverns to build large-capacity power stations will significantly reduce the costs of raw materials and land. However, the biggest technical difficulty lies in underground gas storage. Based on the traditional thermal power construction, it is very mature, and the burial depth of underground salt caverns is often seven or eight hundred or even thousands of meters. Gas injection, gas production, brine drainage, geothermal heat, etc. cause the salt cavity well conditions to be abnormally complex and changeable. The loss of control of the gas-liquid interface position may cause the cavity morphology to be distorted. In severe cases, it may cause the cavity morphology to be out of control, and eventually cause the cavity to collapse or even be scrapped. Therefore, high requirements are put forward for real-time and accurate monitoring and on-site installation technology. It is particularly important to monitor the temperature, pressure, brine level, wellbore deformation, and vibration leakage in the salt cavern cavity and wellbore during real-time online monitoring of injection, gas production, that is, charging and discharging. At present, there is a specific test method for a certain parameter. For example, neutron logging can be used to test the brine interface. However, neutron logging requires regular testing and cannot be monitored online in real time. It is costly and has a high risk when testing at the high-pressure wellhead. It is also impossible to test other parameters at the same time. Therefore, there is an urgent need for a comprehensive testing system that can monitor all parameters online at the same time to ensure the safety of salt caverns and wellbores. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present application provides a salt cavern compressed air energy storage reservoir wellbore optical fiber online comprehensive monitoring system, aiming to solve the above problems.

[0004] An online comprehensive optical fiber monitoring system for a salt cavern compressed air energy storage reservoir includes the following modules:

[0005] A shaft structure module, comprising a shaft penetrating from the ground to an underground salt cavern, wherein the salt cavern has a brine layer below and a compressed air layer above;

[0006] Optical fiber monitoring module, used to detect the internal condition data of the wellbore;

[0007] Data transmission and processing module, used for transmitting and analyzing the data detected by the optical fiber monitoring module;

[0008] A data display module, used for receiving and displaying data transmitted by the data transmission and processing module;

[0009] A user interaction module is used for users to input commands or parameters in order to control the system;

[0010] Among them, the optical fiber monitoring module includes a tight-buffered optical cable, a downhole armored optoelectronic composite cable and a counterweight sealed cavity. The tight-buffered optical cable is laid in the wall thickness of the wellbore for monitoring the deformation and vibration of the wellbore. A wellhead penetration joint is installed at the gas production tree cap position of the wellbore. The downhole armored optoelectronic composite cable is suspended in the wellbore through the wellhead penetration joint. The counterweight sealed cavity is installed at the lower end of the downhole armored optoelectronic composite cable. An optical fiber thermometer and pressure gauge for monitoring temperature and pressure is installed in the counterweight sealed cavity. The downhole armored optoelectronic composite cable includes a temperature and pressure monitoring single-mode optical fiber, two multi-mode optical fibers and two heating wires. The temperature and pressure monitoring single-mode optical fiber is connected to the optical fiber thermometer and pressure gauge. The two multi-mode optical fibers are ring-connected in the counterweight sealed cavity. The positive and negative poles of the two heating wires in the downhole armored optoelectronic composite cable are short-circuited in the counterweight sealed cavity.

[0011] By adopting the above technical scheme, the optical fiber has the advantages of flameproof, explosion-proof, corrosion-resistant and anti-interference, so that it can operate safely in harmful environments, effectively solving the problems of easy corrosion and easy damage of other downhole monitoring equipment. At the same time, the application can monitor all parameters such as wellbore deformation, temperature, pressure, air leakage, and changes in the brine level in the salt cavity online, accurately identify changes in the salt cavity capacity and filling and exhaust volume, provide data support for operation and decision-making, have strong adaptability to the environment of different well conditions, high resolution, small error, and intelligent remote data transmission function, to escort the real-time safety monitoring and operation of compressed gas energy storage power stations.

[0012] Optionally, the data transmission and processing module includes an optical fiber splicing box, a ground armored optoelectronic composite switching cable, a heating control box, a distributed optical fiber temperature sensor demodulator DTS, a distributed optical fiber vibration sensor demodulator DAS, a distributed optical fiber strain sensor demodulator DSS and an optical fiber temperature and pressure gauge demodulator. The tight-buffered optical cable and the downhole armored optoelectronic composite cable are connected to the ground armored optoelectronic composite switching cable through the optical fiber splicing box. The heating control box is used to control the operation of the downhole heating wire. The distributed optical fiber temperature sensor demodulator DTS, the distributed optical fiber vibration sensor demodulator DAS and the distributed optical fiber strain sensor demodulator DSS are all connected to the ground armored optoelectronic composite switching cable.

[0013] By adopting the above technical solutions, this design ensures the continuity of data transmission, realizes the comprehensive monitoring of multiple parameters such as temperature, vibration and deformation in the wellbore, and enhances the sensitivity of temperature sensing by heating the control box, simplifies the system integration process, improves data processing efficiency, and ensures the reliable operation of the system in complex underground environments, providing solid technical support for the real-time safety monitoring of salt cavern compressed air energy storage.

[0014] Optionally, the counterweight sealed chamber is completely immersed in the brine layer of the salt cavern.

[0015] By adopting the above technical scheme, firstly, the buoyancy of brine is used to reduce the dead weight of the downhole armored optoelectronic composite cable, thereby preventing the risk of breaking the wellhead optical cable caused by lateral airflow during injection and gas production; secondly, the immersion design helps the downhole optical cable to accurately sense the changes in the gas-liquid interface, and enhances the accuracy of the distributed optical fiber temperature sensing technology DTS in monitoring the position of the gas-liquid interface; in addition, the hollow structure of the counterweight sealing cavity provides buoyancy in the brine, maintains structural stability, and prevents damage to the wellhead optical cable; finally, immersion in brine also helps to control the temperature of the downhole optical cable and ensure the accuracy of temperature monitoring.

[0016] Optionally, the tight-buffered optical cable is a single-mode dual-core tight-buffered cable, and the tight-buffered optical cable includes a deformation monitoring single-mode optical fiber for monitoring deformation and a vibration monitoring single-mode optical fiber for monitoring vibration.

[0017] Optionally, the tight-buffered optical cable is spirally arranged on the inner wall of the wellbore, with the ring spacing being 1 m, and the tail of the tight-buffered optical cable directly passes out of the wellbore.

[0018] By adopting the above technical solution, the spiral layout ensures that the optical cable is evenly distributed along the wellbore, thereby providing continuous monitoring data, which helps to improve the monitoring accuracy of the distributed optical fiber strain sensor demodulator DSS and the distributed optical fiber vibration sensor demodulator DAS on the deformation and vibration of the wellbore; secondly, the design of the tail directly passing through the wellbore avoids the influence of light scattering of the tail optical fiber on the measurement results, ensuring the accuracy of the measurement data; finally, the spiral layout increases the stability of the optical cable on the wellbore wall, prevents the optical cable from shifting, ensures the fixity and consistency of the optical cable in the wellbore, and thus improves the reliability of the monitoring system.

[0019] Optionally, the data display module includes an industrial computer, which is connected to the central display control screen through a first signal line. The central display screen is divided into 4 display control interfaces, which respectively display the DTS interface, DAS interface, DSS interface and comprehensive status interface. The comprehensive status interface respectively displays the gas injection status, gas production status, brine exhaust status, whether electric heating is turned on, temperature value, pressure value and abnormal operating condition alarm indicator light.

[0020] Optionally, the user interaction module includes a keyboard and a mouse, the mouse is connected to the central display and control screen via a second signal line, and the keyboard is connected to the central display and control screen via a third signal line.

[0021] By adopting the above technical solution, such a design is mainly used to provide a convenient operating experience, allowing users to easily input data and issue commands through the keyboard, and intuitively operate the menus and options on the screen with the mouse to achieve graphical interface control of the system, thereby improving work efficiency, quickly responding to alarm information, adjusting system parameters or performing other management tasks, and enhancing the interactivity and practicality of the system.

[0022] Optionally, the tight-buffered optical cable is provided with armor and an outer sheath on the outside, the armor of the tight-buffered optical cable is made of 316L stainless steel, and the outer sheath is made of polyethylene or PVC.

[0023] By adopting the above technical solutions, 316L stainless steel has excellent corrosion resistance and can effectively protect the internal optical fiber from erosion under the cement curing conditions in the wellbore environment; at the same time, the stainless steel armor provides strong mechanical protection to prevent damage such as extrusion and friction that may be encountered underground; the polyethylene or polyvinyl chloride material used for the outer sheath not only increases the flexibility and wear resistance of the optical cable, but also gives the optical cable certain flame retardant and explosion-proof properties and good insulation properties; in addition, the combination of these materials makes it easy to lay the tight-buried optical cable in the wellbore, reduces the stress on the optical fiber during the laying process, extends the service life of the optical cable, and reduces maintenance costs.

[0024] Optionally, the armor of the downhole armored optoelectronic composite cable is made of 625 nickel alloy.

[0025] By adopting the above technical solutions, first of all, 625 nickel alloy has excellent corrosion resistance, can operate stably for a long time in highly corrosive environments such as brine and high-concentration oxygen in salt caverns, and effectively resist corrosion under high temperature, high pressure and high oxygen conditions. Secondly, the alloy material has good heat resistance and mechanical strength, and can maintain the integrity of the cable under high temperature and high pressure conditions underground. In addition, 625 nickel alloy has good thermal conductivity. By heating the downhole optical cable, the sensitivity and resolution of distributed optical fiber temperature sensing DTS technology can be enhanced, thereby improving the accuracy of gas-liquid interface detection. Furthermore, 625 nickel alloy has high strength and toughness, which can effectively protect the cable from mechanical damage and adapt to the complex working environment underground. Finally, due to its advantages in corrosion resistance, temperature resistance and mechanical strength, the use of 625 nickel alloy as armor material can significantly extend the service life of the cable and reduce operating costs.

[0026] Optionally, the counterweight sealing chamber is made of 625 nickel alloy.

[0027] By adopting the above technical solutions, 625 nickel alloy has excellent corrosion resistance and can work stably for a long time in highly corrosive environments such as brine and high-concentration oxygen, effectively preventing the counterweight sealing cavity from being corroded under high temperature, high pressure and high oxygen conditions. Secondly, 625 nickel alloy has good heat resistance and mechanical strength, and can operate stably for a long time under high temperature and high pressure conditions of salt cavern compressed air energy storage. Furthermore, the alloy has excellent thermal conductivity, which can enhance the sensitivity and resolution of distributed fiber optic temperature sensing DTS technology, and produce obvious temperature changes at the gas-liquid interface by uniformly heating the downhole optical cable, which helps to more accurately measure the gas-liquid interface. The use of 625 nickel alloy can significantly extend the service life of the counterweight sealing cavity and reduce quality accidents caused by material aging or corrosion.

[0028] In summary, the present application includes at least one of the following beneficial technical effects:

[0029] 1. Optical fiber has the advantages of flameproof, explosion-proof, corrosion-resistant and anti-interference, which enables it to operate safely in harmful environments, effectively solving the problems of easy corrosion and easy damage of other downhole monitoring equipment. At the same time, this application can monitor all parameters such as wellbore deformation, temperature, pressure, air leakage, and changes in the level of brine in the salt cavity online, accurately identify changes in the salt cavity capacity and filling and exhaust volume, provide data support for operation and decision-making, have strong adaptability to the environment of different well conditions, high resolution, small error, and intelligent remote data transmission function, to escort the real-time safety monitoring and operation of compressed gas energy storage power stations.

[0030] 2. This design ensures the continuity of data transmission, realizes the comprehensive monitoring of multiple parameters such as temperature, vibration and deformation in the wellbore, and enhances the sensitivity of temperature sensing through the heating control box, simplifies the system integration process, improves data processing efficiency, and ensures the reliable operation of the system in complex underground environments, providing solid technical support for the real-time safety monitoring of salt cavern compressed air energy storage.

[0031] 3. The buoyancy of brine is used to reduce the deadweight of the downhole armored optoelectronic composite cable, preventing the risk of breakage of the wellhead optical cable caused by lateral airflow during injection and gas production. Secondly, the submerged design helps the downhole optical cable to accurately sense the changes in the gas-liquid interface and enhance the accuracy of the distributed optical fiber temperature sensing technology DTS in monitoring the position of the gas-liquid interface. In addition, the hollow structure of the weighted sealing cavity provides buoyancy in the brine, maintains structural stability, and prevents damage to the wellhead optical cable. Finally, immersion in brine also helps control the temperature of the downhole optical cable and ensure the accuracy of temperature monitoring.

[0032] 4. The spiral layout ensures that the optical cable is evenly distributed along the wellbore, thereby providing continuous monitoring data, which helps to improve the monitoring accuracy of the wellbore deformation and vibration of the distributed optical fiber strain sensor demodulator DSS and the distributed optical fiber vibration sensor demodulator DAS. Secondly, the design of the tail directly passing through the wellbore avoids the influence of light scattering of the tail optical fiber on the measurement results, ensuring the accuracy of the measurement data. In addition, this layout method simplifies the operation of the optical fiber splicing box, facilitates the connection between ground equipment and downhole optical cables, and is also conducive to the inspection and maintenance of optical cables. Finally, the spiral layout increases the stability of the optical cable on the wellbore wall, prevents the optical cable from shifting, ensures the fixity and consistency of the optical cable in the wellbore, and thus improves the reliability of the monitoring system.

[0033] 5. 316L stainless steel has excellent corrosion resistance and can effectively protect the internal optical fiber from erosion under the cement curing conditions in the wellbore environment; at the same time, the stainless steel armor provides strong mechanical protection to prevent damage such as extrusion and friction that may be encountered underground; the polyethylene or polyvinyl chloride material used for the outer sheath not only increases the flexibility and wear resistance of the optical cable, but also gives the optical cable certain flame retardant and explosion-proof properties and good insulation properties; in addition, the combination of these materials makes it easy to lay the tight-buried optical cable in the wellbore, reducing the stress on the optical fiber during the laying process, extending the service life of the optical cable and reducing maintenance costs.

[0034] 6. 625 nickel alloy has excellent corrosion resistance and can work stably for a long time in highly corrosive environments such as brine and high-concentration oxygen, effectively preventing the counterweight sealing cavity from being corroded under high temperature, high pressure and high oxygen conditions. Secondly, 625 nickel alloy has good heat resistance and mechanical strength, and can operate stably for a long time under high temperature and high pressure conditions of salt cavern compressed air energy storage. Furthermore, the alloy has excellent thermal conductivity, which can enhance the sensitivity and resolution of distributed optical fiber temperature sensing DTS technology, and produce obvious temperature changes at the gas-liquid interface by uniformly heating the downhole optical cable, which helps to more accurately measure the gas-liquid interface. The use of 625 nickel alloy can significantly extend the service life of the counterweight sealing cavity and reduce quality accidents caused by material aging or corrosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the structure of an embodiment of the present application.

[0036] Figure 2 It is a structural block diagram of an embodiment of the present application.

[0037] Figure 3 It is a structural block diagram of the optical fiber monitoring module in an embodiment of the present application.

[0038] Figure 4 It is a structural block diagram of the data transmission and processing module in an embodiment of the present application.

[0039] Description of reference numerals:

[0040] 1. Ground; 2. Salt cavern; 3. Wellbore; 4. Brine layer; 5. Compressed air layer; 6. Tight-buffered optical cable; 7. Wellhead penetration joint; 8. Downhole armored photoelectric composite cable; 9. Counterweight sealed cavity; 10. Fiber optic temperature and pressure gauge; 11. Multimode fiber optic loop connection; 12. Fiber optic splicing box; 13. Ground armored photoelectric composite adapter cable; 14. Heating control box; 15. Fiber optic temperature and pressure gauge demodulator; 16. Distributed fiber optic temperature sensor demodulator DTS; 17. Distributed fiber optic vibration sensor demodulator DAS; 18. Distributed fiber optic strain sensor demodulator DSS; 19. First signal line; 20. Industrial computer; 21. Central display and control screen; 23. Second signal line; 24. Mouse; 25. Keyboard; 26. Third signal line; 27. DTS interface; 28. DAS interface; 29. ​​DSS interface; 30. Comprehensive status interface. DETAILED DESCRIPTION

[0041] In order to facilitate the understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on the other element, or there can be one or more centered elements therebetween. When an element is described as "connected to" another element, it can be directly connected to the other element, or there can be one or more centered elements therebetween. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this specification are for illustrative purposes only.

[0042] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0043] The present application embodiment discloses an online comprehensive monitoring system for a salt cavern compressed air energy storage wellbore optical fiber. Figure 1 and Figure 2 , including the following modules: a wellbore structure module, including a wellbore 3 that passes through the ground 1 to the underground salt cavern 2, wherein the salt cavern 2 has a brine layer 4 below and a compressed air layer 5 above; an optical fiber monitoring module, used to detect the internal situation data of the wellbore 3; a data transmission and processing module, used to transmit and analyze the data detected by the optical fiber monitoring module; a data display module, used to receive and display the data transmitted by the data transmission and processing module; a user interaction module, used for the user to input commands or parameters to control the system.

[0044] Reference Figure 1 , Figure 2 and Figure 3 The optical fiber monitoring module includes a tight-buffered optical cable 6, a downhole armored optoelectronic composite cable 8 and a counterweight sealed cavity 9. The tight-buffered optical cable 6 is fixedly arranged in the wall thickness of the wellbore 3 through concrete to monitor the deformation and vibration of the wellbore 3. A wellhead penetration joint 7 is installed at the gas production tree cap position of the wellbore 3, and the downhole armored optoelectronic composite cable 8 is suspended in the wellbore 3 through the wellhead penetration joint 7. The counterweight sealing cavity 9 is installed at the lower end of the downhole armored optoelectronic composite cable 8. An optical fiber thermometer 10 for monitoring temperature and pressure is installed in the counterweight sealing cavity 9. The downhole armored optoelectronic composite cable 8 includes a temperature and pressure monitoring single-mode optical fiber, two multi-mode optical fibers and two heating wires. The temperature and pressure monitoring single-mode optical fiber is connected to the optical fiber thermometer 10, and the two multi-mode optical fibers are ring-connected in the counterweight sealing cavity 9. The positive and negative electrodes of the two heating wires in the downhole armored optoelectronic composite cable 8 are short-circuited in the counterweight sealing cavity 9. The two multi-mode optical fiber cores are ring-connected in the counterweight sealing cavity 9 by an optical fiber fusion splicer to become a multi-mode optical fiber with doubled length, which can prevent measurement errors caused by light scattering of the tail optical fiber. Optical fiber has the advantages of being flameproof, explosion-proof, corrosion-resistant, and anti-interference, allowing it to operate safely in harmful environments, effectively solving the problems of easy corrosion and easy damage in other downhole monitoring equipment. At the same time, the present application can monitor all parameters such as wellbore 3 deformation, temperature, pressure, air leakage, and changes in the brine level in the salt cavity online, accurately identify changes in the salt cavity capacity and filling and exhaust volume, provide data support for operation and decision-making, have strong adaptability to the environment of different well conditions, high resolution, small error, and intelligent remote data transmission function, to escort the real-time safety monitoring and operation of compressed gas energy storage power stations.

[0045] Reference Figure 1 , Figure 2 and Figure 4The data transmission and processing module includes an optical fiber splicing box 12, a ground armored optoelectronic composite switching cable 13, a heating control box 14, a distributed optical fiber temperature sensor demodulator DTS16, a distributed optical fiber vibration sensor demodulator DAS17, a distributed optical fiber strain sensor demodulator DSS18 and an optical fiber temperature and pressure gauge demodulator 15. The tight-buffered optical cable 6 and the downhole armored optoelectronic composite cable 8 are connected to the ground armored optoelectronic composite switching cable 13 through the optical fiber splicing box 12. The heating control box 14 is used to control the operation of the downhole heating wire. The distributed optical fiber temperature sensor demodulator DTS16, the distributed optical fiber vibration sensor demodulator DAS17 and the distributed optical fiber strain sensor demodulator DSS18 are all connected to the ground 1 armored optoelectronic composite switching cable. Such a design ensures the continuity of data transmission, realizes the comprehensive monitoring of various parameters such as temperature, vibration and deformation in the wellbore 3, and enhances the sensitivity of temperature sensing by heating the control box 14, simplifies the system integration process, improves data processing efficiency, and ensures the reliable operation of the system in complex underground environments, providing solid technical support for the real-time safety monitoring of salt cavern compressed air energy storage.

[0046] Distributed fiber temperature sensing (DTS) technology uses a single optical fiber to measure temperature and transmit data signals, and uses the principles of fiber Raman scattering and optical time domain reflectometry to obtain the spatial distribution of temperature fields.

[0047] Distributed fiber temperature sensing technology (DTS) can realize continuous measurement of temperature field. When triggered by the synchronous control unit, the laser generates high-power light pulses, which enter the sensing fiber after passing through the optical path coupler. When the high-energy pulse propagates forward, backward Raman scattering is generated. Raman scattering will form two optical signals of different frequencies: Stokes light and anti-Stokes light. Among them, the anti-Stokes light changes with the external temperature, and the fiber temperature sensor changes, which causes the spectrum reflected by the fiber temperature sensor to change. The reflected spectrum is received by the ground temperature demodulator, and the temperature distribution of the downhole sampling point is obtained after wavelength demodulation and temperature calibration. Due to the different specific heat capacities of different media [water is 4200 J / (kg·℃), air is 1030 J / (kg·℃)], the heat exchange between gas and brine on the optical cable is also different. The heating rate or cooling rate of the optical cable in different media is different, which will produce a temperature gradient at the interface of the medium. By recording the spatial distribution of temperature and processing the temperature data, the depth position of the interface can be calculated, and the brine gas-liquid interface can be displayed and recorded with the help of software.

[0048] Reference Figure 1 and Figure 2One end of the temperature and pressure monitoring single-mode optical fiber is connected to the optical fiber temperature and pressure gauge in the counterweight sealed cavity 9, and the other end is connected to the optical fiber temperature and pressure gauge demodulator 15 through the ground armored photoelectric composite transfer cable 13 to monitor the temperature and pressure at the counterweight sealed cavity 9. The multi-mode optical fiber is connected to the distributed optical fiber temperature sensor demodulator DTS16 through the ground armored photoelectric composite transfer cable 13 to monitor the gas-liquid interface of brine during gas injection and brine removal.

[0049] Reference Figure 1 , the weighted sealed cavity 9 is completely immersed in the brine layer 4 of the salt cavern cavity 2. First, the buoyancy of the brine is used to reduce the deadweight of the downhole armored optoelectronic composite cable 8, preventing the risk of breaking the wellhead optical cable caused by the lateral airflow during the injection and production of gas; secondly, the immersed design helps the downhole optical cable to accurately sense the changes in the gas-liquid interface and enhance the accuracy of the distributed optical fiber temperature sensing technology DTS in monitoring the position of the gas-liquid interface; in addition, the hollow structure of the weighted sealed cavity 9 provides buoyancy in the brine, maintains structural stability, and prevents damage to the wellhead optical cable; finally, immersion in the brine also helps to sense the temperature of the downhole optical cable and ensure the accuracy of temperature monitoring.

[0050] Reference Figure 1 and Figure 2 , the tight-wrapped optical cable 6 is a single-mode dual-core tight-wrapped cable, and the tight-wrapped optical cable 6 includes a deformation monitoring single-mode optical fiber for monitoring deformation and a vibration monitoring single-mode optical fiber for monitoring vibration. The tight-wrapped optical cable 6 is spirally laid on the inner wall of the wellbore 3, with a ring spacing of 1m, and the tail of the tight-wrapped optical cable 6 directly passes through the wellbore 3. The spiral laying method ensures that the optical cable is evenly distributed along the wellbore 3, thereby providing continuous monitoring data, which helps to improve the monitoring accuracy of the deformation and vibration of the wellbore 3 by the distributed optical fiber strain sensor demodulator DSS18 and the distributed optical fiber vibration sensor demodulator DAS17. Secondly, the design of the tail directly passing through the wellbore 3 avoids the influence of light scattering of the tail optical fiber on the measurement results, ensuring the accuracy of the measurement data. In addition, this layout method simplifies the operation of the optical fiber junction box 12, facilitates the connection between the ground 1 equipment and the downhole optical cable, and is also conducive to the inspection and maintenance of the optical cable. Finally, the spiral layout increases the stability of the optical cable on the wall of the wellbore 3, prevents the optical cable from shifting, ensures the fixity and consistency of the optical cable in the wellbore 3, and thus improves the reliability of the monitoring system.

[0051] Reference Figure 1The tight-wrapped optical cable 6 is provided with armor and outer sheath on the outside. The armor of the tight-wrapped optical cable 6 is made of 316L stainless steel, and the outer sheath is made of polyethylene or PVC. 316L stainless steel has excellent corrosion resistance and can effectively protect the internal optical fiber from corrosion under the solidified cement conditions in the wellbore environment; at the same time, the stainless steel armor provides strong mechanical protection to prevent damage such as extrusion and friction that may be encountered underground; the polyethylene or polyvinyl chloride material selected for the outer sheath not only increases the flexibility and wear resistance of the optical cable, but also gives the optical cable certain flameproof and explosion-proof properties and good insulation properties; in addition, the combination of these materials makes it easy to lay the tight-wrapped optical cable 6 in the wellbore 3, reduces the stress on the optical fiber during the laying process, and prolongs the service life of the optical cable.

[0052] Reference Figure 1 and Figure 3 , the armor of the underground armored optoelectronic composite cable 8 is made of 625 nickel alloy. First of all, 625 nickel alloy has excellent corrosion resistance, can operate stably for a long time in the highly corrosive environment of brine in salt caverns, and effectively resist corrosion under high temperature, high pressure and high oxygen conditions. Secondly, the alloy material has good heat resistance and mechanical strength, and can maintain the integrity of the cable for a long time under high temperature and high pressure conditions underground. In addition, 625 nickel alloy has good thermal conductivity. By heating the underground optical cable, the sensitivity and resolution of distributed optical fiber temperature sensing DTS technology can be enhanced, thereby improving the accuracy of gas-liquid interface detection. Furthermore, 625 nickel alloy has high strength and toughness, which can effectively protect the cable from mechanical damage and adapt to the complex working environment underground. Finally, due to its advantages in corrosion resistance, temperature resistance and mechanical strength, the use of 625 nickel alloy as armor material can significantly extend the service life of the optical cable and reduce operating costs.

[0053] Reference Figure 1 and Figure 3 , the counterweight sealing cavity 9 is made of 625 nickel alloy. 625 nickel alloy has excellent corrosion resistance, can work stably for a long time in a highly corrosive environment such as brine, and effectively prevent the counterweight sealing cavity 9 from being corroded under high temperature, high pressure and high oxygen conditions. Secondly, 625 nickel alloy has good heat resistance and mechanical strength, and can operate stably for a long time under the high temperature and high pressure conditions of the salt cavern compressed air energy storage reservoir. Furthermore, the alloy has excellent thermal conductivity, which can enhance the sensitivity and resolution of distributed optical fiber temperature sensing DTS technology, and produce obvious temperature changes at the gas-liquid interface by uniformly heating the downhole optical cable, which helps to more accurately measure the gas-liquid interface. The use of 625 nickel alloy can significantly extend the service life of the counterweight sealing cavity 9 and reduce quality accidents caused by material aging or corrosion.

[0054] Reference Figure 1The data display module includes an industrial computer 20, which is connected to the central display and control screen 21 through a first signal line 19. The central display screen is divided into four display and control interfaces, which respectively display the DTS interface 27, the DAS interface 28, the DSS interface 29 and the comprehensive status interface 30. The comprehensive status interface 30 respectively displays the gas injection status, gas production status, brine exhaust status, whether the electric heating is turned on, the temperature value, the pressure value and the abnormal working condition alarm indicator. The user interaction module includes a keyboard 25 and a mouse 24. The mouse 24 is connected to the central display and control screen 21 through a second signal line 23, and the keyboard 25 is connected to the central display and control screen 21 through a third signal line 26. Such a design is mainly used to provide a convenient operating experience, so that users can conveniently input data and issue commands through the keyboard 25, and intuitively operate the menus and options on the screen through the mouse 24 to realize the graphical interface control of the system, thereby improving work efficiency, quickly responding to alarm information, adjusting system parameters or performing other management tasks, and enhancing the interactivity and practicality of the system.

[0055] The beneficial effects of the optical fiber online comprehensive monitoring system for the wellbore of a salt cave compressed air energy storage reservoir in the embodiment of the present application are as follows: the optical fiber has the advantages of flame retardancy, explosion-proof, corrosion resistance, and anti-interference, so that it can operate safely in a harmful environment, and effectively solves the problems of easy corrosion and easy damage in other downhole monitoring equipment. At the same time, the present application can monitor all parameters such as wellbore 3 deformation, temperature, pressure, air leakage, and changes in the level of brine in the salt cave online, accurately identify changes in the salt cavern capacity and filling and exhaust volume, and provide data support for operation and decision-making. It has strong environmental adaptability to different well conditions, high resolution, small error, and intelligent remote data transmission function, which escorts the real-time safety monitoring and operation of compressed gas energy storage power stations. This application has been successfully applied to the world's first set-a 300MW compressed gas energy storage power station demonstration project in Hubei, and has been operating safely to date, and has received unanimous praise from customers.

[0056] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. An online comprehensive optical fiber monitoring system for a salt cavern compressed air energy storage reservoir, characterized in that: Includes the following modules: A shaft structure module, comprising a shaft (3) penetrating from the ground (1) to an underground salt cavern (2), wherein a brine layer (4) is located below the salt cavern (2) and a compressed air layer (5) is located above the salt cavern (2); An optical fiber monitoring module, used to detect internal condition data of the wellbore (3); Data transmission and processing module, used for transmitting and analyzing the data detected by the optical fiber monitoring module; A data display module, used for receiving and displaying data transmitted by the data transmission and processing module; A user interaction module is used for users to input commands or parameters in order to control the system; The optical fiber monitoring module comprises a tight-buffered optical cable (6), a downhole armored optoelectronic composite cable (8) and a counterweight sealed cavity (9); the tight-buffered optical cable (6) is arranged in the wall thickness of the wellbore (3) and is used to monitor the deformation and vibration of the wellbore (3); a wellhead penetration joint (7) is installed at the gas production tree cap position of the wellbore (3); the downhole armored optoelectronic composite cable (8) is suspended in the wellbore (3) through the wellhead penetration joint (7); the counterweight sealed cavity (9) is installed at the lower end of the downhole armored optoelectronic composite cable (8); an optical fiber temperature and pressure gauge (10) for monitoring temperature and pressure is installed in the counterweight sealed cavity (9); the downhole armored optoelectronic composite cable (8) comprises a temperature and pressure monitoring single-mode optical fiber, two multimode optical fibers and two heating wires; The temperature and pressure monitoring single-mode optical fiber is connected to the optical fiber temperature and pressure gauge (10), the two multi-mode optical fibers are connected in a ring in the counterweight sealed cavity (9), the positive and negative electrodes of the two heating wires in the downhole armored optoelectronic composite cable (8) are short-circuited in the counterweight sealed cavity (9), the tight-wrapped optical cable (6) is a single-mode double-core tight-wrapped cable, the tight-wrapped optical cable (6) includes a deformation monitoring single-mode optical fiber for monitoring deformation and a vibration monitoring single-mode optical fiber for monitoring vibration, the tight-wrapped optical cable (6) is spirally arranged on the inner wall of the wellbore (3), the ring spacing is 1m, the tail of the tight-wrapped optical cable (6) directly passes through the wellbore (3), the armor of the downhole armored optoelectronic composite cable (8) is made of 625 nickel alloy, and the counterweight sealed cavity (9) is made of 625 nickel alloy.

2. According to claim 1, a salt cavern compressed air energy storage reservoir wellbore optical fiber online comprehensive monitoring system is characterized by: The data transmission and processing module comprises an optical fiber splicing box (12), a ground armored optoelectronic composite switching cable (13), a heating control box (14), a distributed optical fiber temperature sensor demodulator DTS (16), a distributed optical fiber vibration sensor demodulator DAS (17), a distributed optical fiber strain sensor demodulator DSS (18) and an optical fiber temperature and pressure gauge demodulator (15); the tight-buffered optical cable (6) and the downhole armored optoelectronic composite cable (8) are connected to the ground armored optoelectronic composite switching cable (13) through the optical fiber splicing box (12); the heating control box (14) is used to control the operation of the downhole heating wire; the distributed optical fiber temperature sensor demodulator DTS (16), the distributed optical fiber vibration sensor demodulator DAS (17) and the distributed optical fiber strain sensor demodulator DSS (18) are all connected to the ground armored optoelectronic composite switching cable (13).

3. According to claim 1, a salt cavern compressed air energy storage reservoir wellbore optical fiber online comprehensive monitoring system is characterized by: The counterweight sealing chamber (9) is completely immersed in the brine layer (4) of the salt cave chamber (2).

4. According to claim 1, a salt cavern compressed air energy storage reservoir wellbore optical fiber online comprehensive monitoring system is characterized by: The data display module comprises an industrial computer (20), the industrial computer (20) is connected to a central display control screen (21) via a first signal line (19), the central display screen is divided into four display control interfaces, respectively displaying a DTS interface (27), a DAS interface (28), a DSS interface (29) and a comprehensive status interface (30), the comprehensive status interface (30) respectively displaying a gas injection status, a gas production status, a brine exhaust status, whether electric heating is turned on, a temperature value, a pressure value and an abnormal working condition alarm indicator light.

5. According to claim 1, a salt cavern compressed air energy storage reservoir wellbore optical fiber online comprehensive monitoring system is characterized by: The user interaction module comprises a keyboard (25) and a mouse (24); the mouse (24) is connected to the central display and control screen (21) via a second signal line (23); and the keyboard (25) is connected to the central display and control screen (21) via a third signal line (26).

6. The salt cavern compressed air energy storage reservoir wellbore optical fiber online comprehensive monitoring system according to claim 1 is characterized by: The tight-buffered optical cable (6) is provided with armor and an outer sheath on the outside. The armor of the tight-buffered optical cable (6) is made of 316L stainless steel, and the outer sheath is made of polyethylene or PVC.

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