Salt cavern compressed air energy storage well pipe column anti-corrosion device, system and method

Abstract

The invention discloses a salt cavern compressed air energy storage well pipe column anti-corrosion device, system and method. The device can comprise a metal cable, an active metal block and a balancing weight. Wherein the metal cable comprises a first metal wire, and the material of the first metal wire is consistent with that of the active metal block; the material of the balancing weight is consistent with that of a pipe column of the salt cavern compressed air energy storage well; the metal cable is fixedly connected with the upper end of the active metal block; the lower end of the active metal block is connected with the balancing weight; the upper end of the metal cable is fixed on a gas production tree of the energy storage well; the active metal block and the balancing weight are used for being arranged in a cavity of a salt cavern below an energy storage well, and under the action of gravity, the active metal block and the balancing weight enable the metal cable to be straightened and located on a center shaft of the tubular column. The device can effectively protect the pipe column, so that safety production is guaranteed, and the service life of an energy storage well is prolonged; and meanwhile, monitoring and replacement are facilitated, and the service life of the energy storage well is prolonged on the basis of saving the engineering construction cost.

Description

Technical Field

[0001] The present invention relates to the technical field of salt cavern compressed air energy storage, and particularly relates to an anti-corrosion device, system and method for the well string of a salt cavern compressed air energy storage well. Background Art

[0002] Salt cavern compressed air energy storage is an application of large-scale energy storage power generation technology, and its principle is similar to that of a common pumped-storage power station. The pumped-storage power station pumps water to the upper reservoir using electric energy during the low electricity consumption period at night; and releases the water for power generation during the high electricity consumption period during the day. The salt cavern compressed air energy storage power station replaces the upper reservoir with a salt cavern and the water with air. When the electricity consumption is low, the air is extracted and compressed into the underground salt cavern using electric energy, and the compressed air is released for power generation during the high electricity consumption period.

[0003] The air injected into the salt cavern compressed air energy storage injection well contains oxygen (O 2 ) accounting for about 21%. Since oxygen is a simple substance formed by oxygen elements, its chemical properties are relatively active and it can react with most elements to undergo oxidation reactions, so its corrosiveness is extremely strong. Since there is a large amount of saturated salt brine at the bottom of the salt cavern, the water will evaporate into the air, making the water in the air at the bottom of the cavity reach the saturated state. During the process of extracting air, due to the decrease in temperature and pressure from the bottom to the wellhead in the wellbore, free water will precipitate from the air in the wellbore. Under certain temperature and pressure conditions, the oxygen in the air and the free water act together to cause serious corrosion of the downhole tubing and the inner wall of the gas production wellhead.

[0004] Currently, the following methods are commonly used to prevent oxygen corrosion of the well string of a salt cavern compressed air energy storage well: one is to use an organic coating to protect the inner wall of the downhole tubing; the second is to change the tubing material to improve the anti-corrosion performance; the third is to directly fix an active metal block on the tubing. Summary of the Invention

[0005] In order to avoid electrochemical corrosion of the tubing and facilitate observing the corrosion condition of the active metal block below for timely replacement, the present invention provides an anti-corrosion device, system and method for the well string of a salt cavern compressed air energy storage well.

[0006] In a first aspect, an embodiment of the present invention provides an anti-corrosion device for the well string of a salt cavern compressed air energy storage well, which may include: a metal cable, an active metal block and a counterweight block;

[0007] Wherein, the metal cable includes a first metal wire, and the material of the first metal wire is the same as that of the active metal block; the material of the counterweight block is the same as that of the tubing of the salt cavern compressed air energy storage well;

[0008] The metal cable is fixedly connected to the upper end of the active metal block, and the lower end of the active metal block is connected to the counterweight block;

[0009] The upper end of the metal cable is used to be fixed on the gas production tree of the energy storage well; the active metal block and the counterweight block are used to be arranged in the cavity of the salt cavern under the energy storage well. Under the action of gravity, the active metal block and the counterweight block make the metal cable straight and located on the central axis of the pipe string.

[0010] Optionally, the mass of the counterweight block is greater than the ratio of the product of the wellhead pressure of the energy storage well and the cross-sectional area of the metal cable to the acceleration of gravity.

[0011] Optionally, the metal cable further includes a second metal wire; wherein, the material of the second metal wire is the same as that of the pipe string, and the second metal wire and the first metal wire are alternately arranged and stranded to form the metal cable.

[0012] Optionally, the device may further include: a conversion joint located between the metal cable and the active metal block, and the metal cable and the active metal block are connected through the conversion joint.

[0013] Optionally, the material of the conversion joint is a non-metallic material, or the material of the conversion joint is the same as that of the pipe string.

[0014] Optionally, threads are provided at both ends of the active metal block, and the active metal block is threadedly connected to the conversion joint and the counterweight block respectively.

[0015] Optionally, the device may further include: a guide cone, and the guide cone is connected to the lower end of the counterweight block.

[0016] Optionally, the material of the guide cone is a non-metallic material, or the material of the guide cone is the same as that of the pipe string.

[0017] In a second aspect, an anti-corrosion system for a pipe string of a salt cavern compressed air energy storage well according to an embodiment of the present invention may include: a pipe string, a gas production tree, a blowout preventer, a blowout prevention pipe, a blowout prevention control box, and the anti-corrosion device for a pipe string of a salt cavern compressed air energy storage well as described in the first aspect;

[0018] The pipe string is installed in the salt cavern compressed air energy storage well and partially extends out of the wellhead of the energy storage well. The gas production tree is communicated with the pipe string on the wellhead. The blowout preventer is connected to the upper end of the gas production tree. The blowout prevention control box is communicated with the blowout preventer through the blowout prevention pipe;

[0019] The upper end of the metal cable is fixed to the gas production tree, and the areas where the metal cable passes through the blowout prevention control box and the blowout preventer are respectively wrapped by the sealing rubber packing of the blowout prevention control box and the cable gate of the blowout preventer and are limited to the central axes of the blowout prevention control box and the blowout preventer; the active metal block and the counterweight are suspended in the cavity of the salt cavern below the energy storage well. Under the action of gravity, the active metal block and the counterweight straighten the metal cable and make it located on the central axis of the pipe string.

[0020] Optionally, the system may further include: an insulating flange, and the gate of the gas production tree is connected to the insulating flange to externally connect a gas transmission pipeline through the insulating flange.

[0021] In a third aspect, an embodiment of the present invention provides a method for anti-corrosion of a pipe string of a salt cavern compressed air energy storage well, which uses the anti-corrosion device for the pipe string of the salt cavern compressed air energy storage well as described in the first aspect to perform anti-corrosion on the pipe string, including:

[0022] Based on the wellhead pressure of the salt cavern compressed air energy storage well and the cross-section of the metal cable, determine the mass of the counterweight; and, based on the well depth of the salt cavern compressed air energy storage well, determine the length of the metal cable;

[0023] Assemble the metal cable, the active metal block and the counterweight in sequence to form an anode assembly;

[0024] After the completion of the salt cavern compressed air energy storage well, install the gas production tree, the blowout preventer, the blowout prevention pipe and the blowout prevention control box at the wellhead of the energy storage well respectively;

[0025] Use a winch to lower the active metal block and the counterweight connected by the metal cable into the salt cavern cavity below the energy storage well, and fix the upper end of the metal cable to the gas production tree;

[0026] After the energy storage well has produced for a preset time period, use a winch to take out the active metal block and the counterweight to observe the corrosion condition of the active metal block and judge whether to replace it with a new active metal block.

[0027] In a fourth aspect, an embodiment of the present invention provides an application of the anti-corrosion device for the pipe string of the salt cavern compressed air energy storage well as described in the first aspect in a salt cavern compressed air energy storage well.

[0028] The beneficial effects of the above technical solutions provided in the embodiments of the present invention at least include:

[0029] In an embodiment of the present invention, an anti-corrosion device, system, and method for a pipe string in a salt cavern compressed air energy storage well are provided. When applied, the device can effectively protect the pipe string, prevent the pipe string from being corroded by oxygen in the air, thereby ensuring safe production and extending the service life of the energy storage well. Second, during the process of lowering the device, it is not easy to cause bumps. Even if the surface of the pipe string is damaged due to bumps, the pipe string will not be corroded due to the existence of potential difference. Third, compared with the active metal blocks fixed on the pipe string, the device is convenient for monitoring and replacement, further extending the service life of the energy storage well on the basis of saving the engineering construction cost.

[0030] Other features and advantages of the present invention will be described in the following specification, and, in part, will be obvious from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained by the structures specifically pointed out in the written specification and the drawings.

[0031] The technical solutions of the present invention will be further described in detail below with reference to the drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0033] Figure 1 is a structural diagram of the anti-corrosion device for the pipe string in the salt cavern compressed air energy storage well provided in the embodiment of the present invention;

[0034] Figure 2 is a cross-sectional schematic diagram of the metal cable provided in the embodiment of the present invention;

[0035] Figure 3 is a structural schematic diagram of the anti-corrosion system for the pipe string in the salt cavern compressed air energy storage well provided in the embodiment of the present invention;

[0036] Among them, 1 - anti-corrosion device for the pipe string in the salt cavern compressed air energy storage well; 2 - pipe string; 3 - gas production tree; 4 - blowout preventer; 5 - blowout prevention pipe; 6 - blowout prevention control box; 7 - insulating flange;

[0037] 11 - metal cable; 12 - active metal block; 13 - counterweight block; 14 - adapter; 15 - guide cone;

[0038] 111 - first metal wire; 112 - second metal wire. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art.

[0040] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "far", "near", "front", "rear", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, 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 should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and should not be construed as indicating or implying relative importance.

[0041] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] The inventors found that there are various defects in the existing corrosion prevention methods for pipe strings, resulting in the inability to protect the pipe strings for a long time as required, far from reaching the design life of the salt cavern compressed air energy storage well. Among them, for the method of organic coating protection, since the well is often hundreds or even thousands of meters deep and dozens of pipe strings need to be connected (threaded connection or welding), the coating at the connection part is extremely easy to be damaged when using organic coating protection; at the same time, the coating is also easily damaged during the downhole production process (gas injection or gas production), and once the coating on the surface of the pipe string is damaged, the corrosion rate at the damaged part is often very fast. For the method of changing the pipe string material for anti-corrosion, its anti-corrosion effect is limited, and currently there is still no kind of steel that can completely prevent oxygen corrosion; at the same time, the cost of changing the pipe string material to improve the anti-corrosion performance is too high. For the scheme of fixing active metal blocks at preset intervals on the pipe string as anodes to achieve sacrificial anode protection of the cathode, due to the long service life of the pipe string underground, the loss of the active metal blocks cannot be effectively monitored, and timely replacement cannot be achieved, and the pipe string needs to be completely lifted out for replacement, resulting in huge engineering costs and being inapplicable to the working conditions of large salt cavern compressed air energy storage wells. In view of the above problems, the present invention is proposed to provide a salt cavern compressed air energy storage well pipe string anti-corrosion device, system and anti-corrosion method that overcome the above problems or at least partially solve the above problems.

[0043] In an embodiment of the present invention, a salt cavern compressed air energy storage well pipe string anti-corrosion device is provided. Referring to Figure 1 As shown, the salt cavern compressed air energy storage well pipe string anti-corrosion device 1 may include: a metal cable 11, an active metal block 12 and a counterweight block 13; wherein, the metal cable 11 includes a first metal wire 111, and the material of the first metal wire 111 is the same as that of the active metal block 12; the material of the counterweight block 13 is the same as that of the pipe string 2 of the salt cavern compressed air energy storage well; the metal cable 11 is fixedly connected to the upper end of the active metal block 12, and the lower end of the active metal block 12 is connected to the counterweight block 13; the upper end of the metal cable 11 is used to be fixed on the gas production tree 3 of the energy storage well; the active metal block 12 and the counterweight block 13 are used to be arranged in the cavity of the salt cavern below the energy storage well, and under the action of gravity, the active metal block 12 and the counterweight block 13 make the metal cable 11 straight and located on the central axis of the pipe string 2.

[0044] The active metal block in the above-mentioned salt cavern compressed air energy storage well pipe string anti-corrosion device provided in the embodiment of the present invention and the first metal wire in the metal cable together serve as sacrificial anodes to protect the pipe string as the cathode, thereby preventing the pipe string from being corroded by oxygen in the air. The material of the above-mentioned active metal block in the embodiment of the present invention may be a reactive metal such as zinc, lead, magnesium, etc., and the first metal wire is also made of the above-mentioned active metal. The preparation process of the first metal wire is as follows: heating and melting reactive metal blocks such as zinc, lead, magnesium, etc. into a liquid, and drawing them into metal wires as anodes through a mold with round holes.

[0045] In this embodiment, the above-mentioned active metal block and the first metal wire in the metal cable serve as sacrificial anodes, which penetrate the pipe string part of the entire energy storage well. During the process of extracting air, since free water will precipitate from the air in the wellbore and the flow rate of the extracted air is very high (tens of meters per second), the free water forms charged particulate matter, and under the combined action of oxygen, it causes electrochemical corrosion of the inner wall of the pipe string. Based on the principle of sacrificial anode protecting the cathode, in the embodiment of the present invention, the active metal block and the first metal wire are used as sacrificial anodes, penetrating the pipe string part of the entire energy storage well and located at the central axis part of the pipe string, so that a current loop can be formed between the sacrificial anode and the pipe string as the cathode, and the sacrificial anode part is corroded in exchange for the protection of the pipe string. It should be noted that since the sacrificial anode penetrates the pipe string part of the entire energy storage well, the pipe string and the adjacent active metal or the first metal wire of the metal cable form a current loop, which can protect all the pipe strings in the entire energy storage well.

[0046] The function of the counterweight block in this embodiment is to limit the active metal block in the cavity of the salt cavern at the lower part of the energy storage well. During the gas extraction process, since the air flow is upward and the flow rate is very high, there is a tendency to drive the entire device to move upward. Therefore, the counterweight block is used to relatively fix the entire device in the pipe string, which not only avoids the metal cable from curling and tangling together, but also facilitates the lowering or lifting of the entire device. Here, it should be noted that since saturated brine will gather at the bottom of the salt cavern under the energy storage well, when the above-mentioned device in this embodiment is used, it is necessary to avoid lowering the active metal block to the bottom to contact the saturated brine to prevent rapid corrosion.

[0047] When the above-mentioned device in this embodiment is used, in order to only electrochemically corrode the sacrificial anode and avoid the corrosion of other components, it is necessary to keep the positions of other components consistent with those of the pipe string, that is, the material of the above-mentioned counterweight block needs to be consistent with the material of the pipe string, so as to avoid electrochemical corrosion caused by different potential differences between the two.

[0048] The above-mentioned pipe string anti-corrosion device for salt cavern compressed air energy storage well provided in the embodiment of the present invention is applied to the salt cavern compressed air energy storage well. During application, it can effectively protect the pipe string, avoid the pipe string from being corroded by oxygen in the air, thereby ensuring safe production and extending the life of the energy storage well; second, during the process of lowering the device, it is not easy to cause bumps. Even if the surface layer of the pipe string is damaged due to bumps, it will not corrode the pipe string due to the existence of potential difference; third, compared with the active metal block fixed on the pipe string, this device is convenient for monitoring and replacement, further extending the service life of the energy storage well on the basis of saving the engineering construction cost.

[0049] In an alternative embodiment, the mass of the counterweight block is greater than the product of the wellhead pressure of the energy storage well and the cross-sectional area of the metal cable divided by the acceleration due to gravity.

[0050] The counterweight in this embodiment needs to meet the following conditions: m > (P * S) / g; where m is the mass of the counterweight, P is the wellhead pressure, S is the cross-sectional area of the metal cable, and g is the acceleration due to gravity in the region. The counterweight in the embodiment of the present invention can prevent the metal cable from curling or bunching and then winding around the pipe string, thereby avoiding the entire device from being unable to be lowered and lifted. At the same time, the entire metal cable is kept in a straight state, and an electric current loop can be formed between the adjacent pipe strings.

[0051] In another alternative embodiment, referring to Figure 2 As shown, the metal cable 11 may further include a second metal wire 112; wherein, the material of the second metal wire 112 is the same as that of the pipe string 2, and the second metal wire 112 and the first metal wire 111 are alternately arranged and twisted into the metal cable 11.

[0052] In the embodiment of the present invention, in order to prevent the entire metal cable from being composed of only the first metal wire, after the first metal wire is corroded, the counterweight and the active metal block fall to the bottom of the salt cavern and cannot be lifted. Therefore, the metal cable in this embodiment further includes a second metal wire, and the material of the second metal wire is the same as that of the pipe string. The second metal wire also serves as a cathode and forms an electric current loop with the first metal wire. Referring to Figure 2 As shown, multiple anode metal wires (first metal wires) and the second metal wire are alternately arranged and twisted into a metal cable to serve as a part of the anode assembly and perform a traction function.

[0053] In another alternative embodiment, referring to Figure 1 As shown, the salt cavern compressed air energy storage well pipe string anti-corrosion device 1 may further include: a conversion joint 14 located between the metal cable 11 and the active metal block 12, and the metal cable 11 and the active metal block 12 are connected through the conversion joint 14. In this embodiment, in order to facilitate the connection between the metal cable and the active metal block, the device further includes a conversion joint, which connects the cable and the active metal block respectively, facilitating the replacement of the metal cable or the active metal block during later maintenance.

[0054] In a specific embodiment, the material of the conversion joint 14 is a non-metallic material, or the material of the conversion joint 14 is the same as that of the pipe string 2. Since the conversion joint in this embodiment cannot be electrochemically corroded, the above conversion joint in this embodiment can be a non-metallic material, or of course, the same as the material of the pipe string, and be protected as a cathode together.

[0055] In another alternative embodiment, threads are provided at both ends of the active metal block 12 (not shown in the figure). The active metal block 12 is threadedly connected to the adapter 14 and the counterweight 13 respectively. In this embodiment, the above-mentioned metal block is provided with threads and is connected to the adapter and / or the counterweight, so as to facilitate the replacement of the active metal block due to the corrosion of the active metal block during subsequent use.

[0056] In another alternative embodiment, referring to Figure 1 As shown, the anti-corrosion device 1 for the salt cavern compressed air energy storage well string may further include: a guide cone 15, and the guide cone 15 is connected to the lower end of the counterweight 13. The guide cone in this embodiment plays a guiding role, facilitating the entire device to be lowered into the cavity of the lower salt cavern of the energy storage well, and preventing the counterweight or the active metal block from getting stuck at the connection part or the protruding part of the well string.

[0057] In a specific embodiment, the material of the guide cone is a non-metallic material, or the material of the guide cone is the same as that of the well string. Since the guide cone in this embodiment cannot be electrochemically corroded, the above-mentioned guide cone in this embodiment can be a non-metallic material, and of course it can also be the same as the material of the well string and be protected as the cathode together.

[0058] Based on the same inventive concept, an anti-corrosion system for a salt cavern compressed air energy storage well string is further provided in the embodiments of the present invention. Referring to Figure 3 As shown, the system may include: a well string 2, a Christmas tree 3, a blowout preventer 4, a blowout prevention pipe 5, a blowout prevention control box 6 and the above-mentioned anti-corrosion device 1 for the salt cavern compressed air energy storage well string; the well string 2 is installed in the salt cavern compressed air energy storage well and partially extends out of the wellhead of the energy storage well, the Christmas tree 3 is communicated with the well string 2 on the wellhead, the blowout preventer 4 is connected to the upper end of the Christmas tree 3, and the blowout prevention control box 6 is communicated with the blowout preventer 4 through the blowout prevention pipe 5; the upper end of the metal cable 11 is fixed on the Christmas tree 3, and the areas where the metal cable 11 passes through the blowout prevention control box 6 and the blowout preventer 4 are respectively wrapped by the sealing rubber packing (not shown in the figure) of the blowout prevention control box 6 and the cable gate of the blowout preventer and are limited on the central axis of the blowout prevention control box and the blowout preventer; the active metal block and the counterweight are suspended in the cavity of the lower salt cavern of the energy storage well, and under the action of gravity, the metal cable is straightened and located on the central axis of the well string.

[0059] After the completion of the salt cavern compressed air energy storage well in the embodiment of the present invention, one end of the metal cable is fixed at the wellhead by referring to the wire operation method, and the sacrificial metal block and counterweight block at the other end are lowered into the well, and the metal cable is fixed at the wellhead. After a certain period of production, the metal cable is retrieved, and the corrosion condition of the anode metal (sacrificial metal block) is observed; a new metal cable or sacrificial metal block is re-lowered. After the entire anti-corrosion device is lowered into the salt cavern cavity, the blowout preventer control box is tightened, and the metal cable is clamped by the sealing rubber packing inside the blowout preventer control box and the cable gate of the three-gate cable blowout preventer to achieve double sealing at the wellhead. A section of the metal cable is left and effectively fixed at the wellhead. If the sealing of the blowout prevention system fails, the metal cable is cut by the shear gate of the three-gate cable blowout preventer, and effective well sealing is achieved by using the full-closed gate of the three-gate cable blowout preventer and the wellhead gate of the gas production tree.

[0060] After a certain period of production, the metal cable and the lowered sacrificial metal block are retrieved from the wellhead by referring to the wire operation method using a winch, and the corrosion condition of the anode metal (sacrificial metal block) is observed; if the metal cable or the sacrificial metal block is severely corroded, a new metal cable and sacrificial metal block are re-lowered. In this system, the pipe string of the salt cavern compressed air energy storage well is not corroded by oxygen in the air, ensuring safe production and extending the life of the well.

[0061] In another alternative embodiment, also referring to Figure 3 As shown, the system may further include: an insulating flange 7, and the gate of the gas production tree 3 is connected to the insulating flange 7 to externally connect a gas transmission pipeline (not shown in the figure) through the insulating flange 7. The insulating flange in this embodiment can isolate the entire system from the external pipeline, thus avoiding the corrosion of the first metal wire as the anode in the metal cable extending upward above the wellhead, ensuring that the first metal wire can only be corroded in the well.

[0062] In a specific example, for a certain energy storage injection and production gas well, the wellhead pressure range is 7 - 9 MPa, and the depth of the salt cavern cavity top is about 520 m. It is designed to use a metal cable with an outer diameter of φ12 mm, a sacrificial metal block and a counterweight block with an outer diameter of φ60 mm. The sacrificial metal block and the counterweight block are lowered to a depth of 515 m. The total weight of the lowered metal cable is 182 kg, and the total weight of the lowered counterweight block is 102 kg. The sacrificial anode assembly composed of the metal cable and the sacrificial metal block is retrieved every 3 months, and the corrosion condition of the anode metal wire is observed; a new metal cable sacrificial anode assembly is re-lowered. If the corrosion condition is not serious, the lifting and observation period can be appropriately extended.

[0063] Based on the same inventive concept, the embodiment of the present invention also provides a method for anti-corrosion of the pipe string of a salt cavern compressed air energy storage well, which uses the above-mentioned anti-corrosion device for the pipe string of the salt cavern compressed air energy storage well for anti-corrosion, and includes the following steps:

[0064] Step 1: Determine the mass of the counterweight based on the wellhead pressure of the salt cavern compressed air energy storage well and the cross-sectional area of the metal cable; and determine the length of the metal cable based on the well depth of the salt cavern compressed air energy storage well.

[0065] Step 2: Assemble the metal cable, the active metal block, and the counterweight in sequence to form an anode assembly.

[0066] First, melt active metal blocks such as zinc, lead, and magnesium into liquid by heating and melting, draw metal wires through a mold with round holes, and process them into anode metal wires; alternately arrange multiple anode metal wires with other ordinary material steel wires (cathodes) and twist them into a metal cable; process threads at both ends of the active metal blocks such as zinc, lead, and magnesium, connect the upper end to the metal cable through a conversion joint, and connect the lower end to a counterweight made of other ordinary material metals to jointly form a sacrificial anode assembly.

[0067] Step 3: After the salt cavern compressed air energy storage well is completed, install the gas production tree, blowout preventer, blowout preventer pipe, and blowout prevention control box at the wellhead of the energy storage well respectively.

[0068] Step 4: Use a winch to lower the active metal block and the counterweight connected by the metal cable into the salt cavern cavity below the energy storage well, and fix the upper end of the metal cable on the gas production tree.

[0069] In this step, use a winch to lower the active metal block and the counterweight connected by the metal cable into the salt cavern cavity below the energy storage well, and fix the upper end of the metal cable on the gas production tree. Pull the sacrificial anode assembly into the blowout preventer pipe. The blowout preventer pipe is installed on the three - gate cable blowout preventer at the top of the gas production tree. Use a winch to lower the metal cable sacrificial anode assembly into the well to the specified depth with reference to the wire operation method from the wellhead, tighten the blowout prevention control box, and use the rubber packing inside the blowout prevention control box and the cable gate of the three - gate cable blowout preventer to hold the metal cable tightly to achieve double sealing at the wellhead. Leave a section of the metal cable and fix it effectively at the wellhead. If the sealing of the blowout prevention system fails, use the shear gate of the three - gate cable blowout preventer to cut the metal cable, and use the full - closed gate of the three - gate cable blowout preventer and the wellhead gate of the gas production tree, etc. to achieve effective well sealing.

[0070] Step 5: After the energy storage well has produced for a preset time period, use a winch to take out the active metal block and the counterweight to observe the corrosion condition of the active metal block and determine whether to replace the new active metal block.

[0071] Based on the same inventive concept, an embodiment of the present invention also provides an application of a corrosion prevention device for the pipe string of a salt cavern compressed air energy storage well in a salt cavern compressed air energy storage well.

[0072] For the detailed description and beneficial effects of the anti-corrosion system for the well string of a salt cavern compressed air energy storage well, the anti-corrosion method for the well string of a salt cavern compressed air energy storage well, and the application of the anti-corrosion device for the well string of a salt cavern compressed air energy storage well in a salt cavern compressed air energy storage well, reference can be made to the relevant introduction of the anti-corrosion device for the well string of a salt cavern compressed air energy storage well above, and they will not be elaborated herein in the embodiments of the present invention.

[0073] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. The present disclosure is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present disclosure is only limited by the appended claims. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. A corrosion prevention device for the pipe string of a salt cavern compressed air energy storage well, characterized in that, it includes: a metal cable, an active metal block and a counterweight block; wherein, the metal cable includes a first metal wire, and the material of the first metal wire is the same as that of the active metal block; the material of the counterweight block is the same as that of the pipe string of the salt cavern compressed air energy storage well; the metal cable is fixedly connected to the upper end of the active metal block, and the lower end of the active metal block is connected to the counterweight block; the upper end of the metal cable is used to be fixed on the gas production tree of the energy storage well; the active metal block and the counterweight block are used to be arranged in the cavity of the salt cavern below the energy storage well, and under the action of gravity, the metal cable is straightened and located on the central axis of the pipe string.

2. The device according to claim 1, characterized in that, the mass of the counterweight block is greater than the ratio of the product of the wellhead pressure of the energy storage well and the cross-sectional area of the metal cable to the acceleration due to gravity.

3. The device according to claim 1, characterized in that, the metal cable further includes a second metal wire; wherein, the material of the second metal wire is the same as that of the pipe string, and the second metal wire and the first metal wire are alternately arranged and twisted into the metal cable.

4. The device according to claim 1, characterized in that, it further includes: a transition joint located between the metal cable and the active metal block, and the metal cable and the active metal block are connected through the transition joint; wherein, the material of the transition joint is a non-metallic material, or the material of the transition joint is the same as that of the pipe string.

5. The device according to claim 4, characterized in that, the two ends of the active metal block are provided with threads, and the active metal block is threadedly connected to the transition joint and the counterweight block respectively.

6. The device according to any one of claims 1 to 5, characterized in that, it further includes: a guide cone, and the guide cone is connected to the lower end of the counterweight block; wherein, the material of the guide cone is a non-metallic material, or the material of the guide cone is the same as that of the pipe string.

7. A corrosion prevention system for the pipe string of a salt cavern compressed air energy storage well, characterized in that, it includes: a pipe string, a gas production tree, a blowout preventer, a blowout prevention pipe, a blowout prevention control box and a corrosion prevention device for the pipe string of a salt cavern compressed air energy storage well according to any one of claims 1 to 6; the pipe string is installed in the salt cavern compressed air energy storage well and partially extends out of the wellhead of the energy storage well, the gas production tree is communicated with the pipe string on the wellhead, the blowout preventer is connected to the upper end of the gas production tree, and the blowout prevention control box is communicated with the blowout preventer through the blowout prevention pipe; The upper end of the metal cable is fixed on the gas production tree, and the areas where the metal cable passes through the blowout prevention control box and the blowout preventer are respectively wrapped by the sealing rubber packing of the blowout prevention control box and the cable gate of the blowout preventer and are limited on the central axes of the blowout prevention control box and the blowout preventer; the active metal block and the counterweight block are suspended in the cavity of the salt cavern below the energy storage well. Under the action of gravity, the active metal block and the counterweight block straighten the metal cable and make it located on the central axis of the pipe string.

8. The system according to claim 7, wherein, it further comprises: an insulating flange, the gate of the gas production tree is connected to the insulating flange to externally connect a gas transmission pipeline through the insulating flange.

9. A method for anti-corrosion of the pipe string of a salt cavern compressed air energy storage well, wherein, using the anti-corrosion device for the pipe string of the salt cavern compressed air energy storage well according to any one of claims 1 to 6 to carry out anti-corrosion on the pipe string, including: determining the mass of the counterweight block based on the wellhead pressure of the salt cavern compressed air energy storage well and the cross-sectional area of the metal cable; and determining the length of the metal cable based on the well depth of the salt cavern compressed air energy storage well; successively assembling the metal cable, the active metal block and the counterweight block to form an anode assembly; after the completion of the salt cavern compressed air energy storage well, installing the gas production tree, the blowout preventer, the blowout prevention pipe and the blowout prevention control box at the wellhead of the energy storage well respectively; using a winch to lower the active metal block and the counterweight block connected by the metal cable into the salt cavern cavity below the energy storage well, and fixing the upper end of the metal cable on the gas production tree; after the energy storage well has produced for a preset time period, using a winch to take out the active metal block and the counterweight block to observe the corrosion condition of the active metal block and judge whether to replace it with a new active metal block.

10. An application of the anti-corrosion device for the pipe string of a salt cavern compressed air energy storage well according to any one of claims 1 to 6 in a salt cavern compressed air energy storage well.

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