Dynamic monitoring construction process for salt cavern gas storage

Abstract

The invention discloses a salt cavern gas storage dynamic monitoring construction process which comprises the following steps: connecting a sensing optical cable with an optical cable tail device, placing the optical cable tail device in a supporting cylinder of a cavity-building outer pipe, and fixing the sensing optical cable on the outer wall of the cavity-building outer pipe; a plurality of cavity construction outer pipes are connected in sequence; fixing the optical cable splicing device on the outer wall of the cavity-building outer tube at the upper part of the position where the cavity-building outer tube is preset to be cut off; when the last cavity-building outer pipe is connected, the cavity-building outer pipe is fixed by using a slip, the sleeve four-way joint is lifted to be on the same straight line with the cavity-building outer pipe, and the sensing optical cable penetrates in from the bottom of the sleeve four-way joint and penetrates out from the four-way joint; the casing pipe four-way joint is connected with the last cavity building outer pipe and fixed to the base through a well mouth flange; and a wellhead static sealing device is arranged at the penetrating part of the sensing optical cable. According to the invention, the sensing optical cable and the cavity construction pipe column are put into the well together, the shaft condition and the gas-liquid interface change condition are monitored in real time, and the integrity and the sealing performance of the sensing optical cable are not affected after the pipe cutting operation.

Description

Technical Field

[0001] This invention belongs to the field of oilfield geological exploration technology, and specifically relates to a construction process for dynamic monitoring of salt cavern gas storage. Background Technology

[0002] Salt cavern gas storage facilities are constructed by creating cavities within salt layers to form gas storage chambers, ensuring the chamber volume and stability meet storage requirements. For salt cavern gas storage, cavity creation is a crucial step in the construction process; the shape and stability of the resulting salt cavity significantly impact the operational stability of the gas storage facility, ultimately affecting its lifespan. The cavity creation process for salt cavern gas storage facilities is mainly divided into four stages: the trenching stage, the middle stage of cavity creation, the late stage of cavity creation, and the top forming stage.

[0003] Salt cavern gas storage cavity construction often employs a solvent-inhibiting convection cavity construction process. This requires running two cavity inner and outer tubes suspended at the wellhead within the production casing. A circulation system is established between the inner and outer annulus tubes for water injection and brine drainage to create the cavity. Simultaneously, a solvent-inhibiting agent is injected into the annulus between the outer tube and the production casing to control the dissolution of the cavity. The solvent-inhibiting agent is insoluble in water and does not dissolve the salt rock. The interface depth between the solvent-inhibiting agent and the brine in the cavity is the cavity top depth. Controlling this interface is the most crucial step in the entire cavity construction process, making monitoring the oil-water interface depth even more critical. Traditional methods use neutron logging to periodically obtain the oil-water interface depth. However, this method cannot provide continuous measurement, and unforeseen circumstances cannot be detected and assessed promptly. Fiber optic monitoring involves running a sensing fiber optic cable into the well along with the cavity construction outer tube to continuously monitor the oil-water interface position. After the previous stage of cavity construction is completed, tube cutting is required to ensure that the cavity top and cavity body extend as designed. Existing technology cannot solve the problem of the integrity of the sensing optical cable after tube cutting. Therefore, there is an urgent need for a construction technology for dynamic monitoring of salt cavern gas storage to ensure the smooth progress of dynamic monitoring of optical fiber gas storage. Summary of the Invention

[0004] To address the above problems, this invention discloses a construction process for dynamic monitoring of salt cavern gas storage facilities, comprising the following steps:

[0005] Connect the sensing optical cable to the optical cable tail device, place the optical cable tail device in the support tube of the cavity outer tube and fix it with the limit screw, and use the optical cable fixing clip to fix the sensing optical cable to the outer wall of the cavity outer tube.

[0006] Connect multiple cavity-forming tubes in sequence, and use optical cable fixing clips to fix the sensing optical cable at the joint of two cavity-forming tubes; use an optical fiber testing device to verify the integrity of the sensing optical cable at each set length.

[0007] Depending on the different stages of cavity creation, tube cutting is required. The optical cable splicing device is fixed to the outer wall of the cavity outer tube at the pre-set position for cutting the outer tube.

[0008] When connecting the last cavity external tube, use a clamp to fix the cavity external tube, lift the sleeve four-way connector and put it on the same straight line as the cavity external tube, and insert the sensing optical cable from the bottom of the sleeve four-way connector and out from the four-way connector.

[0009] Connect the casing tee to the last cavity-forming outer tube and fix it to the base using a wellhead flange;

[0010] Install a wellhead static sealing device at the point where the sensing optical cable exits, conduct an integrity test on the sensing optical cable, and connect it to the fiber optic ground long-term acquisition system.

[0011] Furthermore, a support tube is provided on the outer wall of the first inserted cavity tube, and the optical cable tail device is installed in the support tube.

[0012] Furthermore, the specific steps of the pipe cutting operation are as follows:

[0013] After the cavity is created in the previous stage, the outer tube of the cavity is cut with a cutter at the preset cutting position of the outer tube of the cavity.

[0014] Furthermore, the specific steps for inserting the sensing optical cable from the bottom of the sleeve four-way connector and exiting from the four-way connector are as follows:

[0015] The sensing optical cable is continuously lowered into the well along with the cavity-making outer tube until the target depth is reached. A suspension device is installed on the last cavity-making outer tube, and the cavity-making outer tube is fixed to the working platform using a wellhead chuck. The sensing optical cable is then cut after leaving a set length.

[0016] Separate the casing tee from the wellhead flange and raise it to the set height;

[0017] Insert a flexible steel wire through the four-way sleeve valve installation port and exit through the bottom of the four-way sleeve. Securely connect the flexible steel wire to the sensor optical cable head. Pull back the flexible steel wire to pass the sensor optical cable out through the four-way sleeve valve installation port.

[0018] Use a lifting device to place the casing tee onto the wellhead flange, and connect the casing tee to the wellhead flange with connecting bolts;

[0019] Pass the sealing core of the wellhead static sealing device through the sensing optical cable and install it in the casing four-way casing valve installation port. Then pass the sealing cap through the sensing optical cable and connect it to the thread on the casing four-way casing valve installation port to press the sealing core tightly.

[0020] Use the lifting device to lift the cavity-making outer tube and separate it from the wellhead chuck. Remove the wellhead chuck and install the last cavity-making outer tube with the suspension device inside the casing cross.

[0021] Furthermore, the integrity of the sensing optical cable is verified using an optical fiber testing device every 200-500 meters.

[0022] Furthermore, the optical cable tail device is located 3-5 meters away from the bottom of the first inserted cavity tube.

[0023] Furthermore, the optical cable splicing device is located 3-5 meters above the location of the cavity external tube cutting position.

[0024] Furthermore, the optical cable tail device includes an underground sealed pressure-bearing optical cable sealing chamber and an optical unit tail sealing chamber;

[0025] The underground sealed pressure-bearing optical cable sealing chamber is connected to the tail sealing chamber of the optical unit;

[0026] The underground sealed pressure-bearing optical cable sealing chamber is equipped with an optical cable clamping structure.

[0027] The sensing optical cable passes through the optical cable clamping structure inside the sealed pressure-bearing optical cable compartment in the well, and the end of the sensing optical cable is located in the tail sealed compartment of the optical unit.

[0028] Furthermore, the optical cable splicing device includes an upper optical cable sealing chamber, a lower optical cable sealing chamber, and an optical unit splicing sealing chamber;

[0029] The upper optical cable sealing chamber is connected to one end of the optical unit splicing sealing chamber;

[0030] The other end of the optical unit connection sealing chamber is connected to the lower optical cable sealing chamber;

[0031] Both the upper and lower optical cable sealing chambers are equipped with optical cable clamping structures.

[0032] The sensing optical cable passes sequentially through the upper optical cable sealing chamber, the optical unit splicing sealing chamber, and the lower optical cable sealing chamber.

[0033] Furthermore, the wellhead static sealing device includes a sealing inner core and a sealing pressure cap;

[0034] Both the sealing inner core and the sealing cap are provided with through holes;

[0035] The sealing inner core is installed on the sleeve valve mounting port;

[0036] The sealing cap is installed on the sleeve valve mounting port and abuts against the sealing core.

[0037] Compared with the prior art, the embodiments of the present invention have at least the following advantages: The present invention lowers the sensing optical cable into the well along with the cavity-building tubing in the early stage of cavity building in the salt cavern gas storage, and monitors the wellbore conditions and changes in gas-liquid interface in real time. After the pipe cutting operation, the integrity and sealing performance of the sensing optical cable are not affected, and well fluid leakage will not occur. At the same time, the wellhead static sealing device effectively ensures the wellhead sealing performance and ensures long-term monitoring safety performance.

[0038] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention can be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 A process flow diagram of the construction technology for dynamic monitoring of salt cavern gas storage according to an embodiment of the present invention is shown;

[0041] Figure 2 A schematic diagram of the overall optical cable deployment according to an embodiment of the present invention is shown;

[0042] Figure 3 A schematic diagram of the cavity-building process of a salt cavern gas storage tank according to an embodiment of the present invention is shown;

[0043] Figure 4 A schematic diagram of the structure of an optical cable splicing device according to an embodiment of the present invention is shown;

[0044] Figure 5 A schematic diagram of the structure of an optical cable tail device according to an embodiment of the present invention is shown;

[0045] Figure 6 A schematic diagram of the sensing optical cable crossing the ground oil production tree according to an embodiment of the present invention is shown;

[0046] Figure 7 An installation schematic diagram of the optical cable tail device according to an embodiment of the present invention is shown;

[0047] Figure 8 A schematic diagram of a four-way passage for a sensing optical cable conduit according to an embodiment of the present invention is shown.

[0048] Reference numerals: 1. Surface casing; 2. Two-section casing; 3. Three-section casing; 4. Outer cavity tube; 5. Inner cavity tube; 6. Sensor fiber optic cable; 7. Fiber optic cable tail device; 8. Fiber optic cable splicing device; 9. Salt cavity; 10. First-stage cavity structure; 11. Second-stage cavity structure; 12. Nth-stage cavity structure; 13. Cutting position of outer cavity tube; 14. Upper fiber optic cable sealing chamber; 15. Lower fiber optic cable sealing chamber; 16. Fiber optic unit splicing sealing chamber; 17. Downhole sealing pressure-bearing fiber optic cable sealing chamber; 18. Fiber optic unit tail sealing chamber; 19. Suspension device; 20. Sealing inner core; 21. Sealing cap; 22. Wellhead flange; 23. Casing valve mounting port; 24. Fiber optic cable fixing clip; 25. Limiting device; 26. Support tube. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] Figure 1 A process flow diagram of the construction technology for dynamic monitoring of salt cavern gas storage facilities according to an embodiment of the present invention is shown. Figure 1 As shown, the present invention proposes a construction process for dynamic monitoring of salt cavern gas storage facilities, which includes the following steps:

[0051] Step 1: Connect the sensing optical cable 6 to the optical cable tail device 7, place the optical cable tail device 7 in the support tube 26 on the outer wall of the cavity outer tube 4, and fix it with the limit screw to prevent longitudinal displacement. Use the optical cable fixing clip 24 to fix the sensing optical cable 6 to the outer wall of the cavity outer tube 4.

[0052] Step 2: Connect multiple cavity-forming tubes 4 in sequence. After each cavity-forming tube 4 is connected, use optical cable fixing clips 24 to fix the sensing optical cable 6 at the joint between two cavity-forming tubes 4. Use an optical fiber testing device to verify the integrity of the sensing optical cable 6 at each set length.

[0053] Step 3: Depending on the cavity creation stage, tube cutting is required. At the pre-set cut position of the cavity creation outer tube 4, use a fixing steel strap to fix the optical cable splice device 8 to the outer wall of the cavity creation outer tube 4.

[0054] Step 4: When connecting the cavity external tube 4, rotation must be prevented to avoid the sensing optical cable 6 getting tangled on the cavity external tube 4;

[0055] Step 5: When connecting the last cavity external tube 4, use a clamp to fix the cavity external tube 4, lift the sleeve four-way connector and put it on the same straight line as the cavity external tube 4, insert the sensing optical cable 6 from the bottom of the sleeve four-way connector and out from the four-way connector.

[0056] Step 6: Connect the casing tee to the last cavity-making outer tube 4, and fix it to the base using the wellhead flange;

[0057] Step 7: Install a wellhead static sealing device at the exit point of the sensing optical cable 6, perform an integrity test on the sensing optical cable 6, and connect it to the fiber optic ground long-term acquisition system.

[0058] This invention provides a construction process for dynamic monitoring of salt cavern gas storage facilities, effectively solving the problem of accurately monitoring changes in the oil-water interface during the cavity construction process. The bottom of the sensing optical cable 6 is sealed and fixed to the bottom of the outer wall of the lowest cavity-building outer pipe 4. A fixing steel strap is used to secure the sensing optical cable 6 in the upper part of the tubing string. During the cavity construction process, a certain length of the cavity-building outer pipe 4 (measured from the bottom upwards) is cut according to the design. An optical cable splicing device 8 is installed above the cut position 13 of the cavity-building outer pipe to ensure that well fluid does not enter the sensing optical cable 6 after it is cut, thus affecting its performance and preventing well fluid leakage. The sensing optical cable 6 is fixed to the outer wall of the cavity-building outer pipe 4 and lowered into the well along with it. It exits from the wellhead through the Christmas tree cross-section and a wellhead static sealing device is installed. This effectively solves the construction problem of dynamic monitoring in salt cavern gas storage facilities.

[0059] like Figure 2 As shown, from the outside to the inside, the wellhead is provided with the following components in sequence: surface casing 1, second-opening casing 2, third-opening casing 3, cavity-making outer casing 4, and cavity-making inner casing 5. The sensing optical cable 6 is installed on the outer wall of the cavity-making outer casing 4, and the bottom periphery of the cavity-making outer casing 4 is a salt cavity 9.

[0060] like Figure 7 As shown, in some embodiments, a support cylinder 26 is fixedly installed on the outer wall of the first inserted cavity-forming tube 4 (located at the bottom end) as needed. The sensing optical cable 6 is connected to the optical cable tail device 7, the optical cable tail device 7 is installed in the support cylinder 26, and fixed with a limiting device 25 to prevent longitudinal displacement within the support cylinder 26. The limiting device 25 can be a limiting screw.

[0061] In some embodiments, the specific steps of the pipe cutting operation are as follows:

[0062] After the cavity is created in the previous stage, the outer tube 4 of the cavity is cut with a cutter at the preset cavity outer tube cutting position 13.

[0063] During the cavity-building process, to ensure the salt cavity top continues to extend upwards, the outer tube 4 of the cavity-building system needs to be cut after the previous cavity-building stage is completed. The internal optical unit of the sensing optical cable 6 is a hollow tube structure. After the tube cutting operation, the sealing section will fall to the bottom of the salt cavity along with the broken tube. If the sensing optical cable 6, which is fixed to the remaining outer tube 4 of the cavity-building system, does not have a sealing device, well fluid will invade the optical unit of the sensing optical cable 6, damaging the internal optical fiber. Under pressure, the well fluid will spray out of the wellhead, causing a safety accident. An optical cable splicing device 8 is installed above the pre-set outer tube cutting position 13 of the cavity-building system to ensure the internal optical fiber splicing of the sensing optical cable 6 while sealing the optical unit. The optical cable splicing device 8 is fixed to the outer wall of the outer tube 4 of the cavity-building system using a fixing steel strap. Figure 3 As shown, after the first stage cavity structure 10 is completed, the cavity outer tube 4 is cut to continue cavity creation; after the second stage cavity structure 11 is completed, the cavity outer tube 4 is cut to continue cavity creation; the above steps are repeated until the nth stage cavity structure 12 is completed.

[0064] like Figure 8 As shown, in some embodiments, the specific steps for inserting the sensing optical cable 6 through the bottom of the sleeve four-way connector and exiting through the four-way connector are as follows:

[0065] The sensing optical cable 6 is continuously lowered into the well along with the cavity-making outer tube 4 until the target depth is reached. The suspension device 19 is installed on the last cavity-making outer tube 4 (located at the top). The cavity-making outer tube 4 is fixed on the working platform using the wellhead chuck. The sensing optical cable 6 is cut off after leaving a set length.

[0066] Use a lifting device to separate the casing tee from the wellhead flange 22 and lift it to a set height, enough to pull out the sensing optical cable 6 from between the lower end of the casing tee and the wellhead flange 22.

[0067] Use a flexible steel wire to pass through the four-way sleeve valve installation port 23 and out through the bottom of the four-way sleeve. Securely connect the flexible steel wire to the sensor optical cable head. Pull back the flexible steel wire to pass the sensor optical cable 6 out through the four-way sleeve valve installation port 23.

[0068] Use the lifting device to place the casing tee onto the wellhead flange 22, and connect the casing tee to the wellhead flange 22 with connecting bolts.

[0069] The sealing inner core 20 of the wellhead static sealing device is passed through the sensing optical cable 6 and installed in the casing four-way casing valve installation port 23. Then, the sealing cap 21 is passed through the sensing optical cable 6 and connected to the thread on the casing four-way casing valve installation port 23 to press the sealing inner core 20, thus achieving the static sealing effect.

[0070] Use the lifting device to lift the outer tube 4 of the cavity to separate it from the wellhead chuck, remove the wellhead chuck, and install the last outer tube 4 of the cavity with the suspension device 19 into the casing cross.

[0071] In some embodiments, the integrity of the sensing optical cable 6 is verified every 200-500 meters (preferably 300 meters) using an optical fiber testing device to avoid the problem of disconnection.

[0072] In some embodiments, the bottom of the optical cable tail device 7 is 3-5 meters away from the bottom of the first inserted cavity-forming outer tube 4, preferably 3 meters away. This ensures that the detection range of the sensing optical cable 6 covers the wellbore to the maximum extent, while also ensuring that the optical cable tail device 7 can be detached along with the broken tube after the pipe cutting operation.

[0073] In some embodiments, the optical cable splicing device 8 is located 3-5 meters, preferably 5 meters, above the pipe cutting position 13 of the cavity external tube, to ensure that the sensing optical cable 6 covers the wellbore to the maximum extent and to ensure that the pipe cutting operation is located at the lower end of the optical cable splicing device 8, thereby reducing the depth error of the pipe cutting operation.

[0074] like Figure 5 As shown, in some embodiments, the optical cable tail device 7 includes an underground sealed pressure-bearing optical cable sealing chamber 17 and an optical unit tail sealing chamber 18.

[0075] The downhole sealed pressure-bearing optical cable sealing chamber 17 is connected to the optical unit tail sealing chamber 18;

[0076] The underground sealed pressure-bearing optical cable sealing chamber 17 is equipped with an optical cable clamping structure to ensure that the sensing optical cable 6 passing through it will not undergo longitudinal displacement under rated tension.

[0077] The sensing optical cable 6 passes through the optical cable clamping structure inside the underground sealed pressure-bearing optical cable sealing chamber 17, and the end of the sensing optical cable 6 is located inside the tail sealing chamber 18 of the optical unit.

[0078] The underground sealed pressure-bearing optical cable sealing chamber 17 is used to seal the main body of the sensing optical cable 6.

[0079] The tail sealing chamber 18 of the optical unit is used to seal the tail of the optical unit, ensuring that well fluid will not enter the sealing chamber through the outer wall of the sensing optical cable 6, thereby damaging the optical unit inside the sensing optical cable 6.

[0080] The sensing optical cable 6 is connected to the optical cable tail device 7. The optical cable tail device 7 can effectively isolate the well fluid pressure from corroding the sensing optical cable 6 and ensure the integrity of its optical unit.

[0081] like Figure 4 As shown, in some embodiments, the optical cable splicing device 8 includes an upper optical cable sealing chamber 14, a lower optical cable sealing chamber 15, and an optical unit splicing sealing chamber 16.

[0082] The upper optical cable sealing chamber 14 is connected to one end of the optical unit connection sealing chamber 16;

[0083] The other end of the optical unit connection sealing chamber 16 is connected to the lower optical cable sealing chamber 15;

[0084] Both the upper optical cable sealing chamber 14 and the lower optical cable sealing chamber 15 are equipped with optical cable clamping structures to ensure that the sensing optical cable 6 passing through them will not undergo longitudinal displacement under rated tension.

[0085] The sensing optical cable 6 passes sequentially through the upper optical cable sealing chamber 14, the optical unit splicing sealing chamber 16, and the lower optical cable sealing chamber 15.

[0086] The optical cable splicing device 8 is also designed with a sealing structure for the sensing optical cable 6 to ensure that well fluid does not enter the sealed chamber through the outer wall of the sensing optical cable 6. The optical unit splicing sealing chamber 16 ensures that well fluid does not enter the sealed chamber from the inside of the damaged optical unit of the lower sensing optical cable 6, thereby damaging the optical unit inside the sensing optical cable 6. The optical cable splicing device 8 is designed with an optical fiber splicing and fixing structure. After the optical fibers in the upper and lower sensing optical cable 6 optical units are welded to ensure connection, they are fixed by this optical fiber splicing and fixing structure to ensure that they will not break under downhole vibration.

[0087] In the design, an optical cable splicing device 8 is fixed on the outer wall of the upper cavity-making outer pipe 4 that requires pipe cutting operation. After the pipe cutting operation is completed, the lower sensing optical cable 6 is damaged, and the well fluid enters the optical unit of the damaged sensing optical cable 6. Since the optical cable splicing device 8 is present, it will not damage the upper intact sensing optical cable 6, and will maintain continuous monitoring of the next stage of cavity-making process.

[0088] like Figure 6 As shown, in some embodiments, the wellhead static sealing device includes a sealing inner core 20 and a sealing cap 21;

[0089] Both the sealing inner core 20 and the sealing cap 21 are provided with through holes;

[0090] The sealing inner core 20 is installed on the sleeve valve mounting port 23;

[0091] The sealing cap 21 is installed on the sleeve valve mounting port 23 and abuts against the sealing inner core 20.

[0092] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A construction technology for dynamic monitoring of salt cavern gas storage facilities, characterized in that, The following steps are involved: Connect the sensing optical cable to the optical cable tail device, place the optical cable tail device in the support tube of the cavity outer tube and fix it with the limit screw, and use the optical cable fixing clip to fix the sensing optical cable to the outer wall of the cavity outer tube. Connect multiple cavity-forming tubes in sequence, and use optical cable fixing clips to fix the sensing optical cable at the joint of two cavity-forming tubes; use an optical fiber testing device to verify the integrity of the sensing optical cable at each set length. Depending on the different stages of cavity creation, tube cutting is required. The optical cable splicing device is fixed to the outer wall of the cavity outer tube at the pre-set position for cutting the outer tube. When connecting the last cavity external tube, use a clamp to fix the cavity external tube, lift the sleeve four-way connector and put it on the same straight line as the cavity external tube, and insert the sensing optical cable from the bottom of the sleeve four-way connector and out from the four-way connector. Connect the casing tee to the last cavity-forming outer tube and fix it to the base using a wellhead flange; Install a wellhead static sealing device at the point where the sensing optical cable exits, conduct an integrity test on the sensing optical cable, and connect it to the fiber optic ground long-term acquisition system.

2. The construction technology for dynamic monitoring of salt cavern gas storage according to claim 1, characterized in that, A support tube is provided on the outer wall of the first inserted cavity tube, and the optical cable tail device is installed in the support tube.

3. The construction technology for dynamic monitoring of salt cavern gas storage according to claim 1, characterized in that, The specific steps of the pipe cutting operation are as follows: After the cavity is created in the previous stage, the outer tube of the cavity is cut with a cutter at the preset cutting position of the outer tube of the cavity.

4. The construction technology for dynamic monitoring of salt cavern gas storage according to claim 1, characterized in that, The specific steps for inserting the sensing optical cable from the bottom of the sleeve four-way connector and exiting from the four-way connector are as follows: The sensing optical cable is continuously lowered into the well along with the cavity-making outer tube until the target depth is reached. A suspension device is installed on the last cavity-making outer tube, and the cavity-making outer tube is fixed to the working platform using a wellhead chuck. The sensing optical cable is then cut after leaving a set length. Separate the casing tee from the wellhead flange and raise it to the set height; Insert a flexible steel wire through the four-way sleeve valve installation port and exit through the bottom of the four-way sleeve. Securely connect the flexible steel wire to the sensor optical cable head. Pull back the flexible steel wire to pass the sensor optical cable out through the four-way sleeve valve installation port. Use a lifting device to place the casing tee onto the wellhead flange, and connect the casing tee to the wellhead flange with connecting bolts; Pass the sealing core of the wellhead static sealing device through the sensing optical cable and install it in the casing four-way casing valve installation port. Then pass the sealing cap through the sensing optical cable and connect it to the thread on the casing four-way casing valve installation port to press the sealing core tightly. Use the lifting device to lift the cavity-making outer tube and separate it from the wellhead chuck. Remove the wellhead chuck and install the last cavity-making outer tube with the suspension device inside the casing cross.

5. The construction technology for dynamic monitoring of salt cavern gas storage according to claim 1, characterized in that, The integrity of the sensing optical cable is verified using an optical fiber testing device every 200-500 meters.

6. The construction technology for dynamic monitoring of salt cavern gas storage according to claim 2, characterized in that, The optical cable tail device is located 3-5 meters from the bottom of the first inserted cavity tube.

7. The construction technology for dynamic monitoring of salt cavern gas storage according to claim 1, characterized in that, The optical cable splicing device is located 3-5 meters above the location of the external tube cutting position in the cavity.

8. The construction technology for dynamic monitoring of salt cavern gas storage according to claim 1, characterized in that, The optical cable tail assembly includes a sealed pressure-bearing optical cable compartment in the well and a sealed optical unit tail compartment. The underground sealed pressure-bearing optical cable sealing chamber is connected to the tail sealing chamber of the optical unit; The underground sealed pressure-bearing optical cable sealing chamber is equipped with an optical cable clamping structure. The sensing optical cable passes through the optical cable clamping structure inside the sealed pressure-bearing optical cable compartment in the well, and the end of the sensing optical cable is located in the tail sealed compartment of the optical unit.

9. The construction technology for dynamic monitoring of salt cavern gas storage according to claim 1, characterized in that, The optical cable splicing device includes an upper optical cable sealing chamber, a lower optical cable sealing chamber, and an optical unit splicing sealing chamber. The upper optical cable sealing chamber is connected to one end of the optical unit splicing sealing chamber; The other end of the optical unit connection sealing chamber is connected to the lower optical cable sealing chamber; Both the upper and lower optical cable sealing chambers are equipped with optical cable clamping structures. The sensing optical cable passes sequentially through the upper optical cable sealing chamber, the optical unit splicing sealing chamber, and the lower optical cable sealing chamber.

10. The construction technology for dynamic monitoring of salt cavern gas storage according to claim 1, characterized in that, The wellhead static sealing device includes a sealing inner core and a sealing cap; Both the sealing inner core and the sealing cap are provided with through holes; The sealing inner core is installed on the sleeve valve mounting port; The sealing cap is installed on the sleeve valve mounting port and abuts against the sealing core.

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