Air energy storage extrusion reducing expansion type sealing device and method

Abstract

The invention relates to an extrusion reducing expansion type sealing device for air energy storage. The extrusion reducing expansion type sealing device comprises an upper guide ring, an upper threaded back ring, an upper rubber barrel, a middle rubber barrel, a lower rubber barrel, a lower threaded back ring, a lower guide ring and an anti-extrusion ring which are sequentially arranged on a reducing mandrel in a sleeving mode from top to bottom. A thread is arranged at the inner diameter of the upper guide ring and is in threaded connection with the upper threaded back ring; a thread is arranged at the inner diameter of the lower guide ring and is in threaded connection with the lower threaded back ring; the inner diameter of the lower guide ring is matched with that of the reducing mandrel after reducing; and an anti-extrusion ring is arranged on the shoulder part of the inner wall of the lower thread back ring. The invention further relates to a method for utilizing the air energy storage extrusion reducing expansion type sealing device. The device can reliably operate in various complex and severe well and mine environments such as high and low temperature, high and low pressure, hydrogen sulfide containing or conventional oil, water and the like; the sealing failure risk caused by external interference factors is reduced, and the service life and the maintenance period of the sealing assembly are prolonged; the working efficiency and the economical efficiency are improved; and the operation cost and the maintenance cost are reduced.

Description

Technical Field

[0001] This invention relates to the field of downhole tool technology, and more specifically to an air-storage compression-variable-diameter expansion sealing device and method. Background Art

[0002] With the development of society and the economy, the efficient storage and rational utilization of energy have become important issues. Load imbalance is a common problem in power systems; for example, my country faces a large difference between peak and off-peak loads, which not only affects power supply quality but also poses challenges to the stable operation of the power grid. While traditional pumped-storage hydroelectric power stations can store large amounts of electrical energy, their capabilities are limited by factors such as power station site selection and construction costs.

[0003] Against this backdrop, compressed air energy storage technology has emerged as a new type of energy storage and electricity storage technology. Based on gas turbine technology, it uses electrical energy to compress air during periods of low electricity load, sealing the high-pressure air in specific storage spaces such as abandoned mines, submerged seabed gas tanks, caves, expired oil and gas wells, or newly built gas wells. During periods of high electricity load, the compressed air is released to drive a gas turbine to generate electricity. The world's first commercially operational compressed air energy storage power plant was the Huntorf plant in Germany, built in the 1970s. Its compressor power capacity was 60MW, and its energy release output power was 290MW. It continues to operate today, primarily for thermal backup and load smoothing. Subsequently, countries such as the United States and Japan also put their own compressed air energy storage power plants into operation, such as the McIntosh compressed air energy storage power plant in Alabama, USA, which went into operation in 1991, and the Sunagawa-dori compressed air energy storage demonstration project in Japan, which went into operation in 2001, promoting the development and application of this technology.

[0004] However, the implementation of downhole air energy storage projects faces numerous technical challenges, among which sealing is of paramount importance. The downhole environment is complex, characterized by high pressure, fluctuating temperatures, and potentially corrosive gases, placing stringent demands on the performance of seals. Seals must not only effectively prevent gas leakage during long-term operation to ensure the energy storage efficiency of the system, but also withstand the harsh downhole conditions, guaranteeing the durability and reliability of the equipment and thus ensuring the stable operation of the entire air energy storage project. Therefore, developing high-performance seals suitable for downhole air energy storage projects has become one of the key technological requirements in this field.

[0005] The shortcomings of existing technology are:

[0006] 1. Limited Adaptability to Operating Conditions: Traditional sealing components have certain drawbacks in well conditions with stringent environmental requirements. In high and low temperature environments, especially extreme low and ultra-high temperature conditions, performance degrades significantly or even fails to function properly. Low-temperature sealing systems rely on the deformation of elastomers for sealing, which contradicts the fact that elastomers have a low deformation rate at low temperatures, making effective sealing impossible. Furthermore, in complex and harsh well environments containing hydrogen sulfide, reliability is greatly reduced, severely limiting their application range and making them unsuitable for air storage well projects with varying geological conditions and operational requirements.

[0007] 2. Weak anti-interference capability of structural design: The existing sealing system lacks special threaded connection and specific angle fit between the upper guide ring and the upper threaded back ring. In complex fluid environments, the back ring of the sealing system is susceptible to adverse effects of scouring and erosion, leading to premature expansion, which in turn damages the stability of the sealing structure, increases the risk of seal failure due to external interference factors, shortens the service life of the sealing components, and requires frequent maintenance.

[0008] 3. Insufficient pressure adaptability and structural specificity: The traditional sealing assembly's threaded back ring structure is poorly designed. During axial compression and expansion, the inner wall of the upper rubber sleeve's tail is easily squeezed out, causing damage to the rubber sleeve body and leading to seal failure. Moreover, it cannot flexibly adjust its shape and stress distribution according to actual working pressure, nor can it drive the entire rubber sleeve system to deform in an orderly manner to achieve a seal. During air energy storage injection and production processes with varying pressure fluctuations, it is difficult to maintain a good sealing effect, requiring frequent replacement or adjustment of sealing components, resulting in low operational efficiency and poor economy.

[0009] 4. Low sealing reliability: Existing technology lacks a variable-diameter mandrel structure design. When an axial load is applied by the tool, the seal deforms on the straight mandrel solely due to the axial force. This mechanism is difficult to drive the entire rubber sleeve system to work in coordination in large-scale air storage projects, and there is a possibility of irregular deformation, thus failing to achieve a comprehensive and tight seal of the annulus. During static or dynamic sealing processes, the working medium (air, oil, water, hydrogen sulfide-containing gas, etc.) is prone to leakage, affecting the energy storage efficiency of the air energy storage system, reducing operational safety, and increasing the risk of energy loss and safety accidents due to seal leakage.

[0010] 5. Inadequate component protection: Existing technology lacks effective components similar to anti-extrusion rings. Under high pressure, the rubber sleeves at both ends are easily extruded from the gaps in the variable-diameter mandrel, compromising the integrity and sealing performance of the sleeves. Furthermore, the material selection for each component is not appropriate, resulting in poor fit between them. This leads to irregular expansion and deformation, corrosion, and other serious damage, reducing the durability and reliability of the entire sealing assembly, increasing operating and maintenance costs, and making it difficult to ensure the long-term stable operation of air energy storage projects. Summary of the Invention

[0011] To address the aforementioned problems, this invention provides an extrusion-type variable-diameter expansion sealing device and method for air energy storage. Its purpose is to ensure reliable operation in various complex and harsh well and mining environments, including high and low temperatures (covering extreme low and high temperature conditions), high and low pressure (showing stability from low to high pressure), and environments containing hydrogen sulfide or conventional oil and water; reduce the risk of seal failure due to external interference factors; extend the service life and maintenance cycle of sealing components; improve operational efficiency and economy; and reduce operating and maintenance costs.

[0012] To solve the above problems, the technical solution provided by the present invention is as follows:

[0013] An air-energy storage extrusion-type variable-diameter expansion sealing device comprises, from top to bottom, an upper guide ring, an upper threaded back ring, an upper rubber sleeve, a middle rubber sleeve, a lower rubber sleeve, a lower threaded back ring, a lower guide ring, and an anti-extrusion ring, which are sequentially sleeved on a variable-diameter mandrel, wherein:

[0014] The upper guide ring has a threaded inner diameter and is threadedly connected to the upper threaded back ring; the outer side of the upper threaded back ring has a first extension structure for axially pressing the upper rubber cylinder; the inner wall of the first extension structure is tightly fitted with the outer wall of the upper rubber cylinder; the lower guide ring has a threaded inner diameter and is threadedly connected to the lower threaded back ring; the inner diameter of the lower guide ring is fitted with the diameter-changing mandrel after the diameter change; the outer side of the lower threaded back ring has a second extension structure for axially pressing the lower rubber cylinder; the inner wall of the second extension structure is tightly fitted with the outer wall of the lower rubber cylinder; the lower threaded back ring is located at the diameter change of the diameter-changing mandrel; the shoulder of the inner wall of the lower threaded back ring has the anti-extrusion ring.

[0015] Preferably, the engagement angle between the upper guide ring and the shoulder of the upper threaded back ring is 45° to 50°, which is used to prevent the upper threaded back ring from expanding prematurely due to scouring and erosion during operation, thereby enhancing connection stability.

[0016] Preferably, the outer surface of the upper threaded back ring is provided with a thread that matches the upper guide ring; the initial angle at the mating point between the upper threaded back ring and the upper guide ring is 45° to 50°, and the angle gradually changes to 30° to 40° as it extends outward; the threaded portion of the upper threaded back ring is a solid structure; the first extension structure is a multi-layer structure with gaps between the layers; the outermost two layers of the first extension structure have slits and are symmetrically staggered, and the angle and number of layers of the first extension structure are adjusted with pressure changes; the shoulder of the upper threaded back ring is provided with a barb near the variable diameter mandrel portion; the barb is used to prevent the inner wall of the tail of the upper rubber tube from being squeezed out during axial compression expansion, which would lead to sealing failure.

[0017] Preferably, the first extension structure is a three-layer structure with an interlayer gap of 1mm to 2mm.

[0018] Preferably, the end of the lower rubber cylinder is provided with an angled slope; the angle of the slope is adapted to the angle at the diameter change point.

[0019] Preferably, the angle of the slope is 30°.

[0020] Preferably, the anti-extrusion ring is an isosceles triangle with the apex angle of the isosceles triangle pointing in the opposite direction to the variable diameter mandrel; the anti-extrusion ring is installed between the lower rubber sleeve and the lower threaded back ring near the variable diameter mandrel.

[0021] Preferably, the upper guide ring, the upper threaded back ring, the lower threaded back ring, and the lower guide ring are made of steel; the upper rubber cylinder, the middle rubber cylinder, and the lower rubber cylinder are made of high-performance rubber; and the anti-extrusion ring is made of thermoplastic plastic.

[0022] Preferably, the upper rubber tube, the middle rubber tube, and the lower rubber tube are made of nitrile rubber, hydrogenated nitrile rubber, fluororubber, tetrafluoropropylene rubber, or perfluoroether rubber.

[0023] A method utilizing the aforementioned air-storage extrusion-variable-diameter expansion sealing device includes the following steps:

[0024] S100. The sealing device applies an axial load downward; the lower rubber cylinder gradually climbs and expands along the 30° angle at the diameter change point of the variable diameter mandrel; during the expansion process, the lower rubber cylinder is in close contact with the lower threaded back ring, and then the expansion force of the lower rubber cylinder drives the lower threaded back ring to expand outward synchronously.

[0025] S200. During the expansion of the lower threaded back ring, the connection structure between the lower threaded back ring and the lower guide ring causes the lower guide ring to also be subjected to an outward thrust; the inner diameter of the lower guide ring is precisely matched with the diameter-changing mandrel after the diameter change; under the action of the thrust, the lower guide ring is further stabilized on the diameter-changing mandrel and provides support and guidance for the subsequent operation of the sealing components;

[0026] S300. Under the expansion of the lower rubber cylinder and the linkage of the lower threaded back ring and the lower guide ring, the middle rubber cylinder is subjected to the extrusion force transmitted from the lower rubber cylinder and the lower threaded back ring; the middle rubber cylinder begins to deform and bulge, and the elastic properties of its material cause it to gradually adhere to the sleeve wall during the bulging process;

[0027] S400. The reaction force generated after the middle rubber cylinder adheres tightly to the sleeve wall is transmitted to the upper rubber cylinder; the upper rubber cylinder begins to expand under the action of the reaction force; at the same time, the outer wall of the upper rubber cylinder is tightly fitted with the inner wall of the upper threaded back ring; the expansion of the upper rubber cylinder generates an outward pushing force on the upper threaded back ring, causing the upper threaded back ring to expand further.

[0028] S500. During the expansion process, the upper threaded back ring adaptively adjusts its shape and force distribution according to pressure changes, thereby ensuring that the entire sealing device maintains a stable sealing structure under different pressure conditions;

[0029] S600. As the sealing device continues to move downward, the first bulging middle rubber cylinder, under continuous extrusion, further crawls towards the diameter change point of the variable diameter mandrel; the lower rubber cylinder, the middle rubber cylinder, and half of the upper rubber cylinder gradually climb to the diameter change point of the variable diameter mandrel, ultimately achieving complete sealing of the annulus.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] 1. Excellent adaptability to working conditions: Because this invention can operate reliably in a variety of complex and harsh well and mine environments, including high and low temperatures (covering extreme low and high temperature conditions), high and low pressure (showing stability from low pressure to high pressure environments), and containing hydrogen sulfide or conventional oil and water, it effectively solves the problem of traditional sealing components being greatly limited by the environment, greatly expanding its application range and making it suitable for air energy storage well and mine projects with different geological conditions and operational requirements.

[0032] 2. Optimized structural design with strong anti-interference: Due to the special threaded connection and specific angle fit between the upper guide ring and the upper threaded back ring of this invention, it effectively resists the adverse effects of scouring and erosion on the back ring of the sealing system, prevents premature expansion, ensures the stability of the sealing structure in complex fluid environments, reduces the risk of sealing failure caused by external interference factors, and extends the service life and maintenance cycle of the sealing components.

[0033] 3. Flexible pressure adaptability and special structure: Due to the unique structural design of the upper threaded back ring of this invention, it can effectively avoid the extrusion of the inner wall of the tail of the upper rubber tube during axial compression expansion, which would cause the rubber tube body to be damaged and the seal to fail. At the same time, it can flexibly adjust its shape and stress distribution according to the actual working pressure, and can also drive the orderly deformation of the entire rubber tube system to achieve sealing. Thus, the sealing component can maintain a good sealing effect during the air energy storage injection and production process with different pressure fluctuations, without the need for frequent replacement or adjustment of sealing components, thereby improving operation efficiency and economy.

[0034] 4. Highly Reliable Sealing: Due to the structure of the variable-diameter mandrel of this invention, when an axial load is applied by the tool, the mandrel guides the lower rubber sleeve to precisely climb and expand along its angle, thereby driving the entire rubber sleeve system to work in tandem, achieving a comprehensive and tight seal of the annulus. Whether in static or dynamic sealing processes, it effectively prevents leakage of the working medium (air, oil, water, hydrogen sulfide-containing gas, etc.), ensuring the energy storage efficiency and operational safety of the air energy storage system, and reducing energy loss and safety risks caused by sealing leaks. Furthermore, because the variable-diameter mandrel of this invention is made of a material with high strength and good wear resistance, it can maintain shape and performance stability during long-term, frequent sealing operations, further enhancing the reliability and durability of the sealing assembly.

[0035] 5. Excellent component protection: The anti-extrusion ring of this invention effectively prevents the lower rubber sleeve from being squeezed out from the gap of the variable diameter mandrel under high pressure, thus protecting the integrity and sealing performance of the rubber sleeve. Simultaneously, the rational selection of materials for each component (e.g., the metal materials of the guide ring and back ring ensure structural strength, while the rubber sleeve material is temperature and media resistant) and their mutual cooperation reduce wear, corrosion, and other damage between components, thereby improving the durability and reliability of the entire sealing assembly, reducing operating and maintenance costs, and providing strong support for the long-term stable operation of air energy storage projects. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of a specific embodiment of the present invention for an air energy storage extrusion variable diameter expansion sealing device.

[0037] The components include: 1. Upper guide ring, 2. Upper threaded back ring, 3. Upper rubber sleeve, 4. Middle rubber sleeve, 5. Lower rubber sleeve, 6. Lower threaded back ring, 7. Lower guide ring, 8. Anti-extrusion ring, 9. Variable diameter mandrel, 2.1. First extension structure, 2.2. Barb, 5.1. Sloping surface, 6.1. Second extension structure, 9.1. Variable diameter section. Detailed Implementation

[0038] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0039] like Figure 1 As shown, an air energy storage extrusion-type variable diameter expansion sealing device includes, from top to bottom, an upper guide ring 1, an upper threaded back ring 2, an upper rubber sleeve 3, a middle rubber sleeve 4, a lower rubber sleeve 5, a lower threaded back ring 6, a lower guide ring 7, and an anti-extrusion ring 8, which are sequentially sleeved on a variable diameter mandrel 9, wherein:

[0040] The upper guide ring 1 has a thread at its inner diameter and is threadedly connected to the upper threaded back ring 2; the outer side of the upper threaded back ring 2 has a first extension structure 2.1 for axially compressing the upper rubber cylinder 3; the inner wall of the first extension structure 2.1 is tightly fitted with the outer wall of the upper rubber cylinder 3; the lower guide ring 7 has a thread at its inner diameter and is threadedly connected to the lower threaded back ring 6; the inner diameter of the lower guide ring 7 is fitted with the diameter-changing mandrel 9 after the diameter change; the outer side of the lower threaded back ring 6 has a second extension structure 6.1 for axially compressing the lower rubber cylinder 5; the inner wall of the second extension structure 6.1 is tightly fitted with the outer wall of the lower rubber cylinder 5; the lower threaded back ring 6 is located at the diameter change point 9.1 of the diameter-changing mandrel 9; the shoulder of the inner wall of the lower threaded back ring 6 has an anti-extrusion ring 8.

[0041] It should be noted that the mating angle between the shoulder of the upper guide ring 1 and the upper threaded back ring 2 is 45° to 50°. This is to prevent the upper threaded back ring 2 from expanding prematurely due to scouring and erosion during operation, thereby enhancing connection stability. This angle setting significantly enhances the stability and reliability of the connection, enabling it to adapt to complex and changing working conditions.

[0042] It should be further explained that the inner thread of the upper guide ring 1 is tightly connected to the upper threaded back ring 2, effectively preventing premature expansion of the sealing system's back ring due to scouring and erosion during operation. Furthermore, the thread of the upper guide ring 1 can connect to the tool body, thus enabling smooth setting, pressure application, unsealing, and removal operations. The lower guide ring 7 is threadedly connected to the lower threaded back ring 6, and the thread of the lower guide ring 7 can also connect to the tool body, enabling smooth setting, pressure application, unsealing, and removal operations.

[0043] It should be noted that the outer surface of the upper threaded back ring 2 is provided with threads that match the upper guide ring 1; the initial angle at the mating point between the upper threaded back ring 2 and the upper guide ring 1 is 45° to 50°, and the angle gradually changes to 30° to 40° as it extends outward; the threaded portion of the upper threaded back ring 2 is a solid structure; the first extension structure 2.1 is a multi-layer structure with gaps between the layers; the outermost two layers of the first extension structure 2.1 have slits and are symmetrically staggered, and the angle and number of layers of the first extension structure 2.1 are adjusted according to pressure changes; the shoulder of the upper threaded back ring 2 near the variable diameter mandrel 9 is provided with barbs 2.2; barbs 2.2 are used to prevent the inner wall of the tail of the upper rubber sleeve 3 from being squeezed out during axial compression expansion, which would lead to sealing failure.

[0044] It should be further explained that the angle and number of layers of the upper thread back ring 2 in the invention can be flexibly modified according to the pressure changes of the actual working conditions, so as to ensure that good sealing performance can be maintained under different pressure conditions.

[0045] In this specific embodiment, the first extension structure 2.1 is a three-layer structure with a gap of 1mm to 2mm between the layers.

[0046] It should be noted that the end of the lower rubber sleeve 5 is provided with an angled slope 5.1; the angle of the slope 5.1 is adapted to the angle of the diameter change 9.1. When the tool applies an axial load downward, the lower rubber sleeve 5 will gradually climb and expand along the angle of the diameter change 9.1, thereby triggering a series of subsequent sealing actions.

[0047] In this specific embodiment, the angle of slope 5.1 is 30°.

[0048] It should be noted that the anti-extrusion ring 8 is an isosceles triangle with its apex angle pointing in the opposite direction to the reducing mandrel 9. The anti-extrusion ring 8 is installed between the lower rubber sleeve 5 and the lower threaded back ring 6 near the reducing mandrel 9. When the sealing assembly moves downward, the anti-extrusion ring 8 guides the lower rubber sleeve 5 to be squeezed in the opposite direction to the reducing mandrel along the triangular slope. The high-strength anti-extrusion ring 8 prevents the lower rubber sleeve 5 from being squeezed out of the gap in the reducing mandrel 9 under high pressure, ensuring the integrity and sealing performance of the lower rubber sleeve 5. This effectively guarantees the stability and reliability of the sealing device under complex pressure conditions and various media environments, ensuring the durability and effectiveness of the sealing effect, thus providing a solid sealing guarantee foundation for the stable operation of the entire air energy storage system in the well and mining environment.

[0049] It should be noted that the upper guide ring 1, the upper threaded back ring 2, the lower threaded back ring 6, and the lower guide ring 7 are made of steel; the upper rubber cylinder 3, the middle rubber cylinder 4, and the lower rubber cylinder 5 are made of high-performance rubber; and the anti-extrusion ring 8 is made of thermoplastic plastic.

[0050] It should be further noted that the upper rubber sleeve 3, the middle rubber sleeve 4, and the lower rubber sleeve 5 are made of nitrile rubber, hydrogenated nitrile rubber, fluororubber, tetrafluoropropylene rubber, or perfluoroether rubber. The middle rubber sleeve has a slightly lower material hardness than the upper rubber sleeve 3 and the lower rubber sleeve 5. These materials possess excellent temperature resistance, pressure resistance, and resistance to media erosion. They can maintain stable sealing characteristics in high and low temperatures, high and low pressures, and environments containing hydrogen sulfide or conventional oils and water, effectively preventing the deterioration of sealing performance caused by media erosion and temperature and pressure changes.

[0051] It should be further noted that the upper guide ring 1, upper threaded back ring 2, lower threaded back ring 6 and lower guide ring 7 are made of hot steel, wear-resistant steel, stainless steel or carbon steel. In special environments, 718 nickel alloy can be selected.

[0052] A method for using an air-storage extrusion-variable-diameter expansion seal device includes the following steps:

[0053] S100. The sealing device applies an axial load downwards; the lower rubber cylinder 5 gradually climbs and expands along the 30° angle of the diameter change point 9.1 of the variable diameter mandrel 9; during the expansion process, the lower rubber cylinder 5 is in close contact with the lower threaded back ring 6, and then the expansion force of the lower rubber cylinder 5 drives the lower threaded back ring 6 to expand outwards synchronously.

[0054] During the expansion of the lower thread back ring 6, the connection structure between the lower thread back ring 6 and the lower guide ring 7 causes the lower guide ring 7 to also be subjected to an outward thrust; the inner diameter of the lower guide ring 7 is precisely matched with the diameter-changing mandrel 9 after the diameter change; under the action of the thrust, the lower guide ring 7 is further stabilized on the diameter-changing mandrel 9, and provides support and guidance for the subsequent operation of the sealing components.

[0055] S300. Under the expansion of the lower rubber cylinder 5 and the linkage of the lower threaded back ring 6 and the lower guide ring 7, the middle rubber cylinder 4 is subjected to the extrusion force transmitted from the lower rubber cylinder 5 and the lower threaded back ring 6; the middle rubber cylinder 4 begins to deform and bulge, and the elastic properties of its material cause it to gradually adhere to the sleeve wall during the bulging process.

[0056] S400. The reaction force generated after the middle rubber sleeve 4 is pressed against the sleeve wall is transmitted to the upper rubber sleeve 3; the upper rubber sleeve 3 begins to expand under the action of this reaction force; at the same time, the outer wall of the upper rubber sleeve 3 is tightly pressed against the inner wall of the upper threaded back ring 2; the expansion of the upper rubber sleeve 3 generates an outward pushing force on the upper threaded back ring 2, causing the upper threaded back ring 2 to expand further.

[0057] During the expansion process, the unique structural design of the S500 upper thread back ring 2, such as angle change, three-layer structure and slit distribution, enables it to adaptively adjust its shape and stress distribution according to pressure changes, thereby ensuring that the entire sealing device maintains a stable sealing structure under different pressure conditions.

[0058] S600. As the sealing device continues to move downward, the first bulging middle rubber cylinder 4, under continuous extrusion, further crawls towards the diameter change point 9.1 of the variable diameter mandrel 9; the lower rubber cylinder 5, the middle rubber cylinder 4, and half of the upper rubber cylinder 3 gradually climb to the diameter change point 9.1 of the variable diameter mandrel 9, ultimately achieving complete sealing of the annulus, achieving a highly efficient and reliable sealing effect, and effectively preventing leakage of various media in the well and mine environment.

[0059] It should be noted that during the entire sealing process, the various components work closely together and interact with each other, giving full play to their respective structural and material advantages, ensuring stable and reliable sealing performance in complex downhole environments, and meeting the sealing requirements of downhole air storage projects.

[0060] It should be further explained that the air storage compression variable diameter expansion sealing assembly of this invention patent can achieve excellent sealing performance. Before the packer is started, its threaded part connects to the tool body, preventing premature setting during operations such as fluid replacement in the annulus. When the packer is started, thanks to its unique design, the rubber sleeve and the upper threaded back ring 2 and lower threaded back ring 6 sequentially open to seal the annulus, ensuring a tight fit between the packer and the well wall. The unique barb 2.2 design on the shoulder of the upper threaded back ring 2 protects the upper rubber sleeve 3, and the unique triangular anti-extrusion ring 8 design at the variable diameter mandrel 9 of the lower threaded back ring 6 protects the lower rubber sleeve 5, preventing the seal from being squeezed out during system operation, thereby ensuring a good sealing effect and effectively protecting the pressure-bearing rubber sleeve. This composite design allows for flexible selection of various materials based on operating conditions. Whether under low or high pressure, it can achieve reliable airtight and liquid-tight sealing effects, enhancing the applicability and flexibility of the packer. It can be adapted to different pressure ratings of bushings, effectively preventing premature setting of the sealing components. It has strong pressure resistance and wide adaptability, avoiding leakage problems caused by improper use or environmental factors.

[0061] In the detailed description above, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features in a single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, with each claim representing a separate preferred embodiment of the invention.

[0062] The disclosed embodiments have been described above to enable any person skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit and scope of this disclosure. Therefore, this disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0063] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," as interpreted when used as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

[0064] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A variable diameter expansion sealing device for air energy storage, characterized in that: The invention comprises an upper guide ring (1), an upper thread back ring (2), an upper rubber cylinder (3), a middle rubber cylinder (4), a lower rubber cylinder (5), a lower thread back ring (6), a lower guide ring (7) and an anti-extrusion ring (8) which are sleeved on a reducing core shaft (9) in sequence from top to bottom, wherein: The upper guide ring (1) is provided with a thread at the inner diameter thereof and is threadedly connected with the upper threaded back ring (2); the outer side of the upper threaded back ring (2) is provided with a first extension structure (2.1) for axially extruding the upper rubber tube (3); the inner wall of the first extension structure (2.1) is tightly matched with the outer wall of the upper rubber tube (3); the inner diameter of the lower guide ring (7) is provided with a thread and is threadedly connected with the lower threaded back ring (6); the inner diameter of the lower guide ring (7) is matched with the reduced diameter core shaft (9); the outer side of the lower threaded back ring (6) is provided with a second extension structure (6.1) for axially extruding the lower rubber tube (5); the inner wall of the second extension structure (6.1) is tightly matched with the outer wall of the lower rubber tube (5); the lower threaded back ring (6) is arranged at the reduced diameter portion (9.1) of the reduced diameter core shaft (9); the inner wall shoulder of the lower threaded back ring (6) is provided with the anti-extrusion ring (8).

2. The air energy storage extrusion variable diameter expansion sealing device according to claim 1, characterized in that: The matching angle between the upper guide ring (1) and the shoulder of the upper thread back ring (2) is 45° to 50°, which is used to prevent the upper thread back ring (2) from expanding prematurely due to scouring and erosion during operation, thereby enhancing the connection stability.

3. The air energy storage extrusion variable diameter expansion sealing device according to claim 1, characterized in that: The outer portion of the upper threaded back ring (2) is provided with a thread matching the upper guide ring (1); the starting angle of the matching portion of the upper threaded back ring (2) and the upper guide ring (1) is 45° to 50°, and the angle gradually changes to 30° to 40° after extending outward; the threaded portion of the upper threaded back ring (2) is a solid structure; the first extension structure (2.1) is a multi-layer structure, and gaps are provided between the layers; the two outermost layers of the first extension structure (2.1) have slits and are symmetrically staggered, and the angle and number of layers of the first extension structure (2.1) are adjusted with pressure changes; the shoulder of the upper threaded back ring (2) close to the reducer core shaft (9) is provided with a barb (2.2); the barb (2.2) is used to prevent the inner wall of the tail of the upper rubber cylinder (3) from being squeezed out during axial compression and expansion, thereby causing sealing failure.

4. The air energy storage extrusion variable diameter expansion sealing device according to claim 3 is characterized in that: The first extension structure (2.1) is a three-layer structure, and the gap between layers is 1mm to 2mm.

5. The extrusion variable diameter expansion type sealing device for air energy storage according to claim 1, characterized in that: The end of the lower rubber cylinder (5) is provided with a slope surface (5.1) with an angle; the angle of the slope surface (5.1) is adapted to the angle of the diameter-changing portion (9.1).

6. The extrusion variable diameter expansion type sealing device for air energy storage according to claim 4 is characterized in that: The angle of the slope (5.1) is 30°.

7. The extrusion variable diameter expansion type sealing device for air energy storage according to claim 1, characterized in that: The anti-extrusion ring (8) is in the shape of an isosceles triangle, and the vertex of the isosceles triangle is designed to be in the opposite direction of the reducing core shaft (9); the anti-extrusion ring (8) is installed between the lower rubber cylinder (5) close to the reducing core shaft (9) and the lower thread back ring (6).

8. The extrusion variable diameter expansion type sealing device for air energy storage according to claim 1 is characterized in that: The upper guide ring (1), the upper thread back ring (2), the lower thread back ring (6) and the lower guide ring (7) are made of steel; the upper rubber cylinder (3), the middle rubber cylinder (4) and the lower rubber cylinder (5) are made of high-performance rubber; and the anti-extrusion ring (8) is made of thermoplastic plastic.

9. The extrusion variable diameter expansion type sealing device for air energy storage according to claim 1, characterized in that: The upper rubber cylinder (3), the middle rubber cylinder (4) and the lower rubber cylinder (5) are made of nitrile rubber, hydrogenated nitrile rubber, fluororubber, tetrafluoroethylene rubber or perfluoroether rubber.

10. A method using the air energy storage extrusion variable diameter expansion sealing device according to claim 1, characterized in that: The following steps are involved: S100. The sealing device applies an axial load downward; the lower rubber cylinder (5) gradually climbs and expands along the 30° angle of the diameter reduction point (9.1) of the diameter reduction core shaft (9); during the expansion process, the lower rubber cylinder (5) is in close contact with the lower thread back ring (6), and then the lower thread back ring (6) is driven to expand outward synchronously through the expansion force of the lower rubber cylinder (5); S200. During the expansion process of the lower thread back ring (6), the connection structure between the lower thread back ring (6) and the lower guide ring (7) causes the lower guide ring (7) to also be subjected to an outward thrust; the inner diameter of the lower guide ring (7) is precisely matched with the reduced diameter core shaft (9); under the action of the thrust, the lower guide ring (7) is further stabilized on the reduced diameter core shaft (9), and provides support and guidance for the subsequent movement of the sealing component; S300. Due to the expansion of the lower rubber cylinder (5) and the linkage effect of the lower threaded back ring (6) and the lower guide ring (7), the middle rubber cylinder (4) is subjected to the extrusion force transmitted by the lower rubber cylinder (5) and the lower threaded back ring (6); the middle rubber cylinder (4) begins to deform and swell, and the elastic properties of its material make it gradually adhere to the casing wall during the swelling process; S400. The reaction force generated by the middle rubber tube (4) being pressed against the casing wall is transmitted to the upper rubber tube (3); the upper rubber tube (3) begins to expand under the action of the reaction force; at the same time, the outer wall of the upper rubber tube (3) is tightly fitted with the inner wall of the upper thread back ring (2); the expansion of the upper rubber tube (3) generates an outward thrust on the upper thread back ring (2), prompting the upper thread back ring (2) to further expand; S500. The upper thread back ring (2) adaptively adjusts its shape and force distribution according to pressure changes during the expansion process, thereby ensuring that the entire sealing device maintains a stable sealing structure under different pressure conditions; S600. As the sealing device as a whole continues to move downward, the middle rubber cylinder (4) that swells first further climbs toward the diameter-changing point (9.1) of the diameter-changing core shaft (9) under the action of continuous extrusion pressure; the lower rubber cylinder (5), the middle rubber cylinder (4), and half of the upper rubber cylinder (3) gradually climb to the diameter-changing point (9.1) of the diameter-changing core shaft (9), ultimately achieving comprehensive sealing of the annulus.

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