Soluble expansion packer with auxiliary deblocking mechanism and working method of soluble expansion packer

Abstract

The invention belongs to the technical field of gas field vertical well completion, and discloses a soluble expansion packer with an auxiliary deblocking mechanism and a working method thereof, the soluble expansion packer comprises a central pipe, a rubber sleeve, an upper joint unit and a lower joint unit; the center pipe and the rubber sleeve are arranged in an annular mode, one end of the center pipe and one end of the rubber sleeve are connected with the upper connector unit, the other end of the center pipe and the other end of the rubber sleeve are connected with the lower connector unit, an upper rubber sleeve base is arranged in the upper connector unit, a lower rubber sleeve base is arranged in the lower connector unit, and the upper rubber sleeve base and the lower rubber sleeve base are connected to the two ends of the rubber sleeve respectively. An energy storage mechanism is arranged on the outer side of the center pipe, a baffle ring is arranged at one end of the energy storage mechanism and connected with a lower rubber sleeve base, the center pipe is connected with a lower connector, and an outer lining is arranged outside the lower connector. And the upper rubber sleeve seat, the rubber sleeve, the lower rubber sleeve seat, the baffle ring and the outer bushing are all made of soluble materials. Through reasonable structural layout and component connection, the setting and unsetting processes of the packer can be controlled more easily, so that the operation of the packer is simpler and more convenient.

Description

Technical Field

[0001] This invention belongs to the field of gas field vertical well completion technology, and in particular, it relates to a soluble expandable packer with an auxiliary unsealing mechanism and its working method. Background Technology

[0002] In the vast natural gas extraction area, the geological structure is complex and varied, with multiple sets of natural gas-rich strata widely distributed vertically. These strata interweave vertically, each containing unique resource potential, collectively forming a solid foundation for high gas field production. However, these abundant resources also come with significantly increased extraction difficulty. In the early stages of gas field development, to maximize the utilization of these multi-layered gas-bearing resources, technicians primarily employed mechanical packer-based layered fracturing technology as the main reservoir stimulation method. This technology, through precise control of fracturing operations in different strata, effectively improved the utilization rate of multi-layered gas reservoirs, laying a solid foundation for rapid production increases in the gas field.

[0003] However, as gas well production enters the mid-to-late stages, a series of problems gradually emerge. Due to the natural decline in gas well production and the increasing demand for well workover and resumption of production, the mechanical packer pressure-reducing technology has gradually revealed problems such as low success rate of tripping out of the casing, high difficulty in well workover operations, and high costs. These problems not only increase the operational burden of the gas field but also seriously affect the stable production capacity and economic benefits of gas wells. In response to these problems, technical personnel, through in-depth analysis and field investigation, and based on the actual situation on site, found that the excessively small gap between the packer and the completion casing is the main reason for the low success rate of tripping out in the later stages. An excessively small gap not only increases the frictional resistance during tripping out but also easily leads to stuck pipe and other malfunctions, severely reducing operational efficiency and increasing costs. Furthermore, the difficulty of well workover operations also increases, especially when dealing with malfunctions under complex geological conditions, posing a severe challenge to technology and equipment.

[0004] To address this issue, researchers began exploring the application prospects of soluble packers. These packers not only dissolve into formation fluids after completing their sealing function, reducing permanent wellbore occupation, but more importantly, by optimizing the dissolution mechanism, they hold the promise of significantly changing the packer's outer diameter, thereby fundamentally solving the problem of low tripping-out success rates. However, current soluble packers are primarily compression-type, and only the sealing components dissolve later; the packer's outer diameter remains unchanged after dissolution, thus not fundamentally altering the subsequent tripping-out success rate. Summary of the Invention

[0005] The purpose of this invention is to provide a soluble expandable packer with an auxiliary unsealing mechanism and its working method, thereby solving the problem that the outer diameter of the packer does not change after the existing soluble packer is dissolved.

[0006] To achieve the above objectives, the present invention employs the following technical solution: A soluble expandable packer with an auxiliary unsealing mechanism includes a central tube, a rubber sleeve, an upper connector unit, and a lower connector unit; The central tube and the rubber tube are arranged in annular space. One end of the central tube and the rubber tube are connected to the upper connector unit, and the other end of the central tube and the rubber tube are connected to the lower connector unit. The upper connector unit is provided with an upper rubber tube seat, and the lower connector unit is provided with a lower rubber tube seat. The upper rubber tube seat and the lower rubber tube seat are respectively connected to the two ends of the rubber tube. An energy storage mechanism is provided on the outside of the central tube. One end of the energy storage mechanism is provided with a retaining ring. The retaining ring is connected to the lower rubber tube seat. The central tube is connected to the lower connector. An outer bushing is provided on the outside of the lower connector. The materials of the upper glue tube seat, glue tube, lower glue tube seat, retaining ring and outer bushing are all soluble materials.

[0007] Furthermore, the central tube includes an upper central tube and a lower central tube, which are connected by threads.

[0008] Furthermore, a slit is provided on the upper central tube.

[0009] Furthermore, the energy storage mechanism is located on the outside of the lower central tube, and an air cavity is formed in the energy storage mechanism, with a spring installed inside the air cavity.

[0010] Furthermore, the retaining ring is connected to the lower rubber sleeve seat via an external thread, and a sealing ring is provided between the retaining ring and the lower central tube.

[0011] Furthermore, the upper glue tube seat is threadedly connected to the glue tube via an upper glue tube connector, and the lower glue tube seat is threadedly connected to the glue tube via a lower glue tube connector.

[0012] Furthermore, the upper rubber sleeve seat is connected to one end of the upper connector via an external thread, one end of the upper connector is connected to the upper central tube via an internal thread, and the other end of the upper connector is connected to the construction oil pipe via a thread.

[0013] Furthermore, the lower connector is connected to the lower central tube via an internal thread, and the outer bushing is connected to the outside of the lower connector via a thread.

[0014] Furthermore, the materials of the upper rubber sleeve seat, lower rubber sleeve seat, retaining ring and outer bushing are all soluble metals, and the material of the rubber sleeve is all soluble rubber.

[0015] A method of operating the soluble expandable packer with auxiliary unsealing mechanism, comprising: When hydraulic pressure is applied inside the packer, high-pressure liquid enters the central tube and the annulus between the rubber sleeve and the packer. Under the action of hydraulic pressure, the rubber sleeve expands radially and its outer diameter increases. At the same time, the lower connector unit moves upward, and the energy storage mechanism is compressed to store elastic energy. When the internal pressure of the packer is released, the energy storage mechanism rebounds, pushing the lower connector unit downwards, and the rubber sleeve rebounds, thus releasing the packer; After the packer is unsealed, in the downhole environment, the upper rubber sleeve seat, rubber sleeve, lower rubber sleeve seat, retaining ring and outer bushing gradually dissolve, the outer diameter of the packer decreases, and the gap between the packer and the well wall increases.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a soluble expandable packer with an auxiliary unsealing mechanism. By annularly arranging the central tube and the rubber sleeve, with one end of both connected to an upper connector unit and the other end connected to a lower connector unit, it helps to disperse pressure, reduce stress concentration, and thus enhance the overall stability and durability of the packer structure. An energy storage mechanism is provided in the lower connector unit. After pressure relief, the energy storage mechanism releases stored energy, and its rebound force pushes the lower rubber sleeve seat, spring, and retaining ring of the packer to reset, achieving rapid and forced unsealing of the packer. This mechanized unsealing method is more efficient and reliable than traditional methods, significantly reducing the risk of stuck drills and increasing the success rate of unsealing. The invention's reasonable structural layout and component connections make the operation and maintenance of the packer simpler. Operators can more easily control the setting and unsealing process of the packer, and it also facilitates subsequent maintenance and component replacement.

[0017] This invention also provides a method for operating a soluble expandable packer with an auxiliary unsealing mechanism. The packer is set by utilizing pressure buildup, while simultaneously, the energy storage mechanism is compressed to store energy. After depressurization, the packer's lower rubber sleeve seat, spring, and retaining ring reset under the rebound force of the energy storage mechanism, achieving forced unsealing of the packer. After unsealing, in the downhole environment, the upper rubber sleeve seat, lower rubber sleeve seat, retaining ring, outer bushing, and rubber sleeve dissolve, reducing the packer's outer diameter and increasing the annular space clearance. This invention employs a pressure buildup setting and an energy storage mechanism rebound reset design, making the packer more stable and reliable during setting and unsealing. By introducing an auxiliary unsealing mechanism, especially the application of an energy storage mechanism, forced unsealing of the packer is achieved. This mechanism ensures that even in complex or adverse environments, the packer can be effectively released from the wellbore, avoiding problems such as stuck drill bit encountered in traditional methods, reducing the risk of subsequent tripping operations, and thus significantly improving the success rate and efficiency of tripping operations.

[0018] Furthermore, the slotted design and the introduction of energy storage mechanisms give the packer greater flexibility and controllability during expansion, contraction, and desealing, enabling it to adapt to more complex wellbore conditions. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the soluble expandable packer with an auxiliary unsealing mechanism according to the present invention.

[0021] Wherein: 1-Upper connector, 2-Upper rubber tube seat, 3-Upper rubber tube connector, 4-Upper central tube, 5-Rubber tube, 6-Slit, 7-Lower rubber tube connector, 8-Lower rubber tube seat, 9-Lower central tube, 10-Energy storage mechanism, 11-Retaining ring, 12-Lower connector, 13-Outer bushing. Detailed Implementation

[0022] 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, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0024] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0026] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0027] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0028] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0029] The present invention will now be described in further detail with reference to the accompanying drawings: See Figure 1 This invention provides a soluble expandable packer with an auxiliary unsealing mechanism, comprising an upper connector 1, an upper rubber sleeve seat 2, a rubber sleeve upper connector 3, an upper central tube 4, a rubber sleeve 5, a slit 6, a rubber sleeve lower connector 7, a lower rubber sleeve seat 8, a lower central tube 9, an energy storage mechanism 10, a retaining ring 11, a lower connector 12, and an outer bushing 13. The upper rubber sleeve seat 2, lower rubber sleeve seat 8, retaining ring 11, and outer bushing 13 are made of soluble metal, and the rubber sleeve 5 is made of soluble rubber. This design allows these components to gradually dissolve into the surrounding medium in the downhole environment, thereby achieving residue-free self-unsealing of the packer, enhancing the packer's flexibility, and reducing the difficulty and risk of subsequent operations.

[0030] The upper connector 1 serves as the top connection of the packer. Both ends of the upper connector 1 are threaded, with the upper thread connecting to the construction tubing to ensure stability and sealing during operation. The lower part connects to the upper rubber sleeve seat 2 via an external thread and to the upper central tube 4 via an internal thread, forming a stable internal support structure. The upper central tube 4 and the rubber sleeve 5 are annularly spaced to reduce direct pressure on the rubber sleeve 5, extending its service life while ensuring unobstructed fluid passage. A 0.1~0.3mm slit 6 is cut in the middle of the upper central tube 4, allowing fluid to pass through the slit 6 under pressure, enabling precise application of fluid to the rubber sleeve 5 for rapid expansion or contraction. The rubber sleeve 5, as the core sealing element of the packer, has an upper rubber sleeve connector 3 and a lower rubber sleeve connector 7 at each end. The upper rubber sleeve connector 3 and the lower rubber sleeve connector 7 are connected to the upper rubber sleeve seat 2 and the lower rubber sleeve seat 8 via external threads, ensuring uniform force distribution during expansion and effectively sealing specific areas in the wellbore. The upper rubber sleeve seat 2 is threadedly connected to the rubber sleeve 5 via the upper rubber sleeve connector 3, and the lower rubber sleeve seat 8 is threadedly connected to the rubber sleeve 5 via the lower rubber sleeve connector 7. The precise threaded connections between the components ensure both stability and ease of disassembly and replacement when needed. The upper central tube 4 is connected to the lower central tube 9 via a lower external thread. An energy storage mechanism 10 is located on the outside of the lower central tube 9. This energy storage mechanism contains an air cavity with a spring inside. Through the combined action of the spring and the air cavity, the energy storage mechanism 10 provides additional power when the packer needs to be released, utilizing the spring's elasticity and the air cavity's compressibility. This helps the packer release more smoothly and enhances its adaptability to complex well conditions. A retaining ring 11 is located at the lower part of the energy storage mechanism 10. The retaining ring 11 is threadedly connected to the lower rubber sleeve seat 8. A sealing ring is installed between the retaining ring 11 and the lower central tube 9, ensuring a tight seal between the energy storage mechanism and the lower central tube. The lower connector 12 serves as the bottom connector of the packer. The lower connector 12 is connected to the lower central tube 9 via an internal thread. An outer bushing 13 is provided on the outside of the lower connector 12, and the outer bushing 13 is connected to the outside of the lower connector 12 via a thread. The outer bushing 13 not only enhances the structural strength of the bottom of the packer, but may also protect the lower connector from the influence of the external environment to a certain extent.

[0031] The working method of the soluble expandable packer with auxiliary unsealing mechanism of the present invention: After the packer is installed in the predetermined position, high-pressure liquid is applied to the inside of the packer through the construction tubing. During the pressurization process, the liquid pressure must be strictly controlled to avoid exceeding the capacity of the packer. The high-pressure liquid enters the annulus between the upper central tube 4 and the packer 5 through the slit 6 in the middle of the upper central tube 4. Under hydraulic action, the packer 5 is driven to expand radially, increasing its outer diameter and achieving a seal on the wellbore. As the packer expands, its outer diameter gradually increases, tightly fitting against the well wall to form an effective sealing barrier. At the same time, since the upper packer seat 2 and the upper packer connector 3 are threadedly connected to the upper connector 1 and cannot move relative to each other, when the packer 5 expands radially, the lower packer connector 7 drives the lower packer seat 8 and the retaining ring 11 to move upward through the thread. The spring in the energy storage mechanism 10 and the air in the air cavity are compressed and store elastic energy.

[0032] When the packer needs to be released, the pressure inside the packer is relieved, and the spring and compressed air in the energy storage mechanism 10 quickly rebound, pushing the retaining ring 11 and the lower rubber sleeve seat 8 downward, causing the rubber sleeve 5 to rebound to its initial state, thus releasing the packer. During the release operation, it should be ensured that the pressure has been completely released to avoid excessive impact force generated by the energy storage mechanism 10 during the rebound process.

[0033] After the packer is released, in the downhole environment, over time, the upper rubber sleeve seat 2, lower rubber sleeve seat 8, retaining ring 11, outer bushing 13 and rubber sleeve 5 gradually dissolve into the surrounding medium, the outer diameter of the packer decreases, the gap between the packer and the well wall increases, reducing the risk of later tripping and facilitating subsequent operations.

[0034] During operation, the soluble expandable packer of this invention applies pressure to the upper connector 1 via the construction tubing. The pressurized fluid is precisely guided to the rubber sleeve 5 through the slit 6 in the upper central tube 4. Through a precise hydraulic system and uniform force design, the rubber sleeve 5 rapidly expands and tightly adheres to the wellbore, forming an effective sealing barrier. At this time, the spring in the energy storage mechanism 10 is compressed, and the air in the air chamber is compressed to store energy. When it is necessary to release the packer, the pressure is released, the spring in the energy storage mechanism 10 rebounds, and combined with the pressure relief effect of the air chamber, provides strong power for the packer to unseal, pushing the lower rubber sleeve seat 8, retaining ring 11, and other components to reset, achieving a rapid and smooth unsealing process. The energy storage mechanism combines the elasticity of the spring and the compressibility of the air chamber, providing additional power for unsealing and ensuring smooth unsealing of the packer under complex well conditions. Its soluble material design allows the packer to automatically dissolve into the formation after completing the isolation task, reducing permanent occupation of the wellbore and facilitating subsequent operations.

[0035] This invention integrates advanced materials science and mechanical design concepts. By using soluble metals and soluble rubber as manufacturing materials for key components, it achieves residue-free unsealing under specific downhole environments. Simultaneously, the introduction of an auxiliary unsealing energy storage mechanism, utilizing the dual action of springs and air chambers, improves the reliability and efficiency of packer unsealing, enabling operation in complex well conditions and adapting to different downhole environments. This reduces the difficulty and risk of subsequent operations, saving costs and time. It can be widely applied in oil and gas field exploration and development, especially in situations requiring temporary isolation of different wellbore sections, production enhancement operations, or formation pressure testing, providing a more efficient, reliable, and economical solution for natural gas extraction and other fields.

[0036] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Within the spirit and principles of the present invention, those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to substitute them, but without departing from the spirit of the present invention or exceeding the scope defined by the appended claims, all of which should be included within the protection scope of the present invention.

Claims

1. A soluble expandable packer with an auxiliary unsealing mechanism, characterized in that, Includes a central tube, a rubber sleeve (5), an upper connector unit, and a lower connector unit; The central tube and the rubber tube (5) are arranged in annular space. One end of the central tube and the rubber tube (5) are connected to the upper connector unit, and the other end of the central tube and the rubber tube (5) are connected to the lower connector unit. The upper connector unit is provided with an upper rubber tube seat (2), and the lower connector unit is provided with a lower rubber tube seat (8). The upper rubber tube seat (2) and the lower rubber tube seat (8) are respectively connected to the two ends of the rubber tube (5). An energy storage mechanism (10) is provided on the outside of the central tube. A retaining ring (11) is provided at one end of the energy storage mechanism (10). The retaining ring (11) is connected to the lower rubber tube seat (8). The central tube is connected to the lower connector (12). An outer bushing (13) is provided on the outside of the lower connector (12). The materials of the upper glue tube seat (2), glue tube (5), lower glue tube seat (8), retaining ring (11) and outer bushing (13) are all soluble materials.

2. The soluble expandable packer with an auxiliary unsealing mechanism according to claim 1, characterized in that, The central tube includes an upper central tube (4) and a lower central tube (9), which are connected by threads.

3. A soluble expandable packer with an auxiliary unsealing mechanism according to claim 2, characterized in that, A slit (6) is provided on the upper central tube (4).

4. A soluble expandable packer with an auxiliary unsealing mechanism according to claim 2, characterized in that, The energy storage mechanism (10) is located on the outside of the lower central tube (9), and an air cavity is provided in the energy storage mechanism (10), and a spring is provided in the air cavity.

5. A soluble expandable packer with an auxiliary unsealing mechanism according to claim 2, characterized in that, The retaining ring (11) is connected to the lower rubber sleeve seat (8) by external thread, and a sealing ring is provided between the retaining ring (11) and the lower central tube (9).

6. A soluble expandable packer with an auxiliary unsealing mechanism according to claim 1, characterized in that, The upper glue tube seat (2) is threadedly connected to the glue tube (5) through the upper glue tube connector (3), and the lower glue tube seat (8) is threadedly connected to the glue tube (5) through the lower glue tube connector (7).

7. A soluble expandable packer with an auxiliary unsealing mechanism according to claim 1, characterized in that, The upper rubber sleeve seat (2) is connected to one end of the upper connector (1) by an external thread, one end of the upper connector (1) is connected to the upper central tube (4) by an internal thread, and the other end of the upper connector (1) is connected to the construction oil pipe by a thread.

8. A soluble expandable packer with an auxiliary unsealing mechanism according to claim 1, characterized in that, The lower connector (12) is connected to the lower center tube (9) via an internal thread, and the outer bushing (13) is connected to the outside of the lower connector (12) via a thread.

9. A soluble expandable packer with an auxiliary unsealing mechanism according to claim 1, characterized in that, The materials of the upper rubber sleeve seat (2), lower rubber sleeve seat (8), retaining ring (11) and outer bushing (13) are all soluble metals, and the material of the rubber sleeve (5) is all soluble rubber.

10. A method of operating the soluble expandable packer with an auxiliary unsealing mechanism as described in any one of claims 1 to 9, characterized in that, include: When hydraulic pressure is applied inside the packer, high-pressure liquid enters the central tube and the rubber cylinder (5) annular space. Under the action of hydraulic pressure, the rubber cylinder (5) expands radially and the outer diameter increases. At the same time, the lower connector unit moves upward and the energy storage mechanism (10) is compressed to store elastic energy. When the internal pressure of the packer is released, the energy storage mechanism (10) rebounds, pushing the lower connector unit downwards, and the rubber sleeve (5) rebounds, thus releasing the packer; After the packer is unsealed, in the downhole environment, the upper rubber sleeve seat (2), rubber sleeve (5), lower rubber sleeve seat (8), retaining ring (11) and outer bushing (13) gradually dissolve, the outer diameter of the packer becomes smaller, and the gap between it and the well wall increases.

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