Casing deformation well plugging device with small unblocking difficulty

Abstract

According to the casing deformation well plugging device, the unblocking difficulty is small, an upper piston and a lower piston are slidably arranged between a center pipe and an outer pipe which are connected through a hydraulic cylinder cover, and a driving medium is introduced into a hydraulic cylinder space formed among the center pipe, the outer pipe, the upper piston and the lower piston; the bottom end of the lower piston is fixedly connected with a double-Z-shaped interlocking rubber sleeve expansion anti-overturning mechanism which is in sliding connection with the outer wall of the central pipe and the inner wall of the outer pipe; the outer wall of the lower portion of the center pipe is sleeved with a liner pipe, and the outer wall of the liner pipe is sleeved with a rubber sleeve. The double-Z-shaped interlocking rubber sleeve expansion anti-overturning mechanism is driven by the lower piston to slide along the outer wall of the central pipe and the inner wall of the outer pipe to be coned into the rubber sleeve or withdrawn from the inner part of the rubber sleeve; the double-Z-shaped interlocking rubber sleeve expansion anti-overturning mechanism is provided with a dissoluble part. Under the condition that the conventional unsealing process cannot be completed, liquid with a certain degree of mineralization is injected into a shaft, so that a dissolvable part of the double-Z-shaped interlocking rubber sleeve expansion anti-overturning mechanism is dissolved, rubber sleeve expansion support is released, unsealing is completed, and then the unsealing difficulty is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of casing-change well isolation, and in particular relates to a casing-change well plugging device with low unblocking difficulty. Background Art

[0002] Wellbore integrity is crucial to the normal development of an oilfield. However, over time, due to various factors such as geology and process, a certain percentage of casing damage is inevitable in injection and production wells, severely impacting normal oilfield production. This is particularly true during the heavy oil well-production phase, where casing fatigue damage is easily caused by the frequent cycling of hot and cold water. For ultra-heavy oil wells, due to the short throughput cycles and frequent runs, casing damage typically occurs within 2-4 cycles. Furthermore, the packers commonly used in heavy oil thermal recovery wells often face difficulties in unsealing. The diameter of casing-change wells is significantly reduced compared to normal wells, making conventional packers difficult to operate downhole. Currently, packer designs used to seal casing-change wells primarily achieve this by controlling the tool's outer diameter, employing a long rubber sleeve, and increasing the degree of compression across the casing-change section. While this approach can isolate casing-change wells, the high expansion rate makes unsealing extremely difficult. Summary of the Invention

[0003] In order to overcome the problem of difficult unsealing in the existing casing-change well sealing method, the present invention provides a casing-change well sealing device with low unsealing difficulty. The rubber cylinder is sealed or unsealed by the cone insertion or release of the rubber cylinder by the double Z-type interlocking rubber cylinder expansion and anti-turnover mechanism. When the conventional unsealing process cannot be completed, a certain mineralized liquid is injected into the wellbore to dissolve the soluble component made of soluble material of the double Z-type interlocking rubber cylinder expansion and anti-turnover mechanism, thereby releasing the rubber cylinder expansion support, completing the unsealing, and reducing the difficulty of unsealing.

[0004] The technical solution adopted by the present invention to solve its technical problems is:

[0005] The outer tube of the liner is sleeved with a liner, and the outer tube is sleeved with a liner. The inner tube and the outer tube are connected by a cylinder cover. An upper piston and a lower piston are slidingly provided between the center tube and the outer tube. A cylinder space is formed between the center tube, the outer tube, the upper piston and the lower piston. A driving medium for driving the lower piston to move is introduced into the cylinder space. A double Z-type interlocking rubber cylinder expansion and anti-rollover mechanism is fixedly connected to the bottom end of the lower piston. The double Z-type interlocking rubber cylinder expansion and anti-rollover mechanism is slidably connected to the outer wall of the center tube and the inner wall of the outer tube. A sealing pin is connected between the mechanism and the outer tube. A liner is sleeved on the outer wall of the lower part of the center tube, and a rubber cylinder is sleeved on the outer wall of the liner. The double Z-type interlocking rubber cylinder expansion and anti-rollover mechanism is driven by the lower piston to slide along the outer wall of the center tube and the inner wall of the outer tube into the interior of the rubber cylinder or exit from the interior of the rubber cylinder. The double Z-type interlocking rubber cylinder expansion and anti-rollover mechanism has a soluble component.

[0006] Furthermore, the double Z-shaped interlocking rubber cylinder expansion anti-turnover mechanism includes a pressure sleeve, an upper Z-shaped anti-burst part, a lower Z-shaped anti-burst part and a sleeve-changing cone, wherein the upper Z-shaped anti-burst part and the lower Z-shaped anti-burst part are made of soluble materials that can dissolve and react with mineralized liquid; the outer wall of the pressure sleeve is in sliding contact with the inner wall of the outer tube, the sealing pin is connected between the pressure sleeve and the outer tube, and the bottom end of the lower piston is fixedly connected to the top end of the pressure sleeve; the inner wall of the sleeve-changing cone is in sliding contact with the outer wall of the center tube The inner wall of the bottom end of the pressure-bearing sleeve is in sliding connection with the outer wall of the sleeve-changing cone; the inner walls of the connected upper Z-shaped anti-protrusion part and the lower Z-shaped anti-protrusion part are in sliding connection with the outer wall of the sleeve-changing cone, and the upper Z-shaped anti-protrusion part and the lower Z-shaped anti-protrusion part are arranged between the pressure-bearing sleeve and the sleeve-changing cone; the end face of the bottom end of the pressure-bearing sleeve and the top end face of the upper Z-shaped anti-protrusion part are set as Z-shaped conical surfaces that can cooperate and clamp with each other; the end face of the bottom end of the lower Z-shaped anti-protrusion part and the end face of the side wall of the sleeve-changing cone are set as Z-shaped conical surfaces that can cooperate and clamp with each other.

[0007] Furthermore, the sleeve-changing cone is made of a heat-sensitive material or a soluble material that can react with a mineralized liquid.

[0008] Furthermore, a limiting ring a is embedded in the outer wall of the central tube to limit the maximum downward position of the lower piston.

[0009] Furthermore, a limiting ring b is provided on the outer wall of the sleeve-changing cone for limiting the maximum retraction position of the pressure sleeve.

[0010] Furthermore, an expandable lower joint is sleeved on the outer wall of the lower portion of the rubber cylinder, and the side walls of the lower joint are each provided with a plurality of axially arranged slits.

[0011] Furthermore, the driving medium introduced into the cylinder space is a heat-sensitive agent or hydraulic pressure.

[0012] Furthermore, when the driving medium is a thermosensitive agent, the thermosensitive agent is filled into the liquid cylinder space through the dosing hole opened on the lower piston or on the wall of the outer tube; when the driving medium is hydraulic, the lateral hole of the central tube is used as the pressure inlet hole, and the sealing device is used as a hydraulic seal.

[0013] Furthermore, under the working condition that the driving medium cannot continuously provide driving force and continuous support is required for the rubber cylinder, a locking ring is embedded in the inner wall of the outer tube to limit the one-way movement of the pressure sleeve. The locking ring is made of a soluble material that can dissolve with the mineralized liquid.

[0014] Furthermore, a plurality of sealing members are provided between the upper piston and the central tube and the outer tube.

[0015] Furthermore, a plurality of sealing members are provided between the lower piston and the central tube and the outer tube.

[0016] Furthermore, the rubber cylinder is made of short rubber cylinder high temperature resistant rubber.

[0017] The beneficial effects of the present invention include:

[0018] The double Z-shaped interlocking rubber cylinder expansion and anti-turnover mechanism is adopted, which consists of a pressure sleeve, an upper Z-shaped anti-bumping part, a lower Z-shaped anti-bumping part, and a sleeve-changing cone. During the downward setting process, the pressure sleeve pushes the upper Z-shaped anti-bumping part, and the upper Z-shaped anti-bumping part drives the lower Z-shaped anti-bumping part to push the sleeve-changing cone axially forward and cone into the rubber cylinder. The rubber cylinder begins to expand and seal the annular space between the pipe string and the wellbore to achieve the purpose of sealing; the inclined surface formed by the sleeve-changing cone and the upper and lower Z-shaped anti-bumping parts provides support for the sharp part of the sleeve-changing cone to cone into the rubber cylinder, thereby increasing the support height of the expansion and compression cone surface of the rubber cylinder after passing through the sleeve changing section. The reliability of the sealing is enhanced; in the conventional unsealing process, the outer tube is lifted up through the threaded connection between the center tube and the cylinder cover, and at the same time, the limit ring a embedded in the center tube drives the lower piston and then drives the pressure sleeve to lift up, releasing the double Z-type interlocking rubber cylinder expansion anti-turnover mechanism, and completing the unsealing of the rubber cylinder; if the unsealing process encounters a sleeve change section and the conventional unsealing process cannot be completed, liquid with a certain mineralization degree is injected into the wellbore. Under this environment, the upper Z-type anti-bumping part and the lower Z-type anti-bumping part made of soluble material dissolve, thereby releasing the rubber cylinder expansion support, completing the unsealing, and reducing the difficulty of unsealing.

[0019] The lower joint is evenly distributed with multiple slits along the lateral side, which expand and wrap the rubber cylinder during the expansion process of the rubber cylinder to prevent the rubber cylinder from turning outward; the rubber cylinder is made of short high-temperature resistant rubber, which solves the problem of difficulty in unsealing and inability to work in high-temperature environment caused by the long rubber cylinder structure; when the sleeve-changing cone is made of heat-sensitive material, the temperature rises during the sealing process to cause expansion, which strengthens the support effect on the rubber cylinder, and shrinks as the temperature drops during the unsealing process, which facilitates unsealing; when the sleeve-changing cone is made of soluble material, it can be dissolved in a mineralized environment, which is more convenient for unsealing; under the working condition that the driving medium cannot continuously provide driving force and continuous support is required for the rubber cylinder, a locking ring is embedded in the inner wall of the outer tube, which can limit the one-way movement of the pressure sleeve and prevent the rubber cylinder from retreating. When unsealing, the locking ring and the soluble components of the Z-type interlocking rubber cylinder expansion and anti-turnover mechanism are dissolved and released together.

[0020] In summary, this device utilizes a localized dissolution approach to design a double-Z-shaped interlocking rubber cartridge expansion and anti-flip mechanism. This increases the support height of the rubber cartridge's expanded and compressed cone after passing through the sleeve transition, preventing it from everting outward and enhancing the reliability of the plugging process. After application, a mineralized liquid dissolves the soluble components of the mechanism, reducing the difficulty of unsealing and preventing difficulties, thereby ensuring production. This device has great potential and is suitable for widespread promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the overall structure of the device according to embodiment 1 of the present invention;

[0022] Figure 2 This is a schematic diagram of the overall structure of the device according to embodiment 2 of the present invention;

[0023] Figure 3 yes Figure 2 3D renderings;

[0024] Figure 4 yes Figure 2 A magnified view of the local structure;

[0025] Figure 5 This is a schematic diagram of the double Z-shaped interlocking rubber cylinder expansion anti-flip mechanism;

[0026] Figure 6 This is a schematic diagram of the lock ring structure in Example 2;

[0027] 1-coupling, 2-center tube, 3-cylinder cover, 4-upper piston, 5-outer tube, 6-lower piston, 7-pressure sleeve, 8-locking ring, 9-limiting ring a, 10-limiting ring b, 11-upper Z-type anti-protrusion part, 12-lower Z-type anti-protrusion part, 13-sleeve variable cone, 14-rubber cylinder, 15-liner, 16-lower joint, 17-sealing ring a, 18-sealing ring b, 19-sealing gasket a, 20-O-type rubber sealing ring a, 21-sealing gasket b, 22-O-type rubber sealing ring b, 23-sealing pin. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] Example 1:

[0031] See also Figure 1 A casing-to-well plugging device that is locally dissolvable and has low unsealing difficulty. It is suitable for use with heat-sensitive agents as the driving medium and can provide a long-term high-temperature setting environment. It consists of a coupling 1, a center pipe 2, a cylinder head 3, an upper piston 4, an outer pipe 5, a lower piston 6, a pressure sleeve 7, a limit ring a9, a limit ring b10, an upper Z-shaped anti-burst member 11, a lower Z-shaped anti-burst member 12, a casing-to-well cone 13, a rubber sleeve 14, a liner 15, a lower joint 16, a sealing ring a17, a sealing ring b18, a sealing gasket a19, an O-type rubber sealing ring a20, a sealing gasket b21, an O-type rubber sealing ring b22, and a setting pin 23.

[0032] When assembling the device, a heat-sensitive agent (n-octane or other heat-sensitive agents, etc.) is added to the liquid cylinder composed of the central tube 2, upper pistons 4, 5-outer tube, and lower piston 6 through the inclined hole opened on the lower piston 6 or the dosing hole opened on the wall of the outer tube 5, and then the other parts are assembled. When lowering, the entire plugging device is connected to the pipe string through the coupling 1 and lowered into the designated plugging position. Under the action of steam injection or formation temperature, the heat-sensitive agent in the liquid cylinder begins to expand, generating thrust, pushing the lower piston 6 and driving the pressure sleeve 7 axially downward ( Figure 1 The setting process starts when the sealing pin 23 is cut off.

[0033] During the downward setting process, the Z-shaped conical surface of the pressure sleeve 7 pushes the upper Z-shaped anti-protrusion piece 11 forward axially and expands radially, and the flat convexity of the upper Z-shaped anti-protrusion piece 11 drives the lower Z-shaped anti-protrusion piece 12 to expand radially and move axially. At this time, the Z-shaped conical surface of the lower Z-shaped anti-protrusion piece 12 is combined with the Z-shaped conical surface of the sleeve variable cone 13, as shown in FIG. Figure 4 As shown, while expanding radially, the sleeve change cone 13 is pushed axially forward and cones into the rubber cylinder 14. The rubber cylinder 14 begins to expand and seal the annular space between the pipe string and the wellbore to achieve the purpose of sealing. At this time, the lower joint 16 expands along the lateral slit to prevent the rubber cylinder 14 from turning outward. The inclined surface formed by the sleeve change cone and the upper and lower Z-shaped anti-protrusion parts provides support for the rubber cylinder to be cone-entered at the sharp point of the sleeve change cone, thereby improving the support height of the expansion and compression cone surface of the rubber cylinder after passing through the sleeve change section, and enhancing the reliability of the sealing.

[0034] Several seals, including a sealing ring a17, a sealing ring b18, a sealing gasket a19, and an O-ring a20, are installed between the upper piston 4 and the central tube 2 and outer tube 5. Several seals, including a sealing gasket b21 and an O-ring b22, are also installed between the lower piston 6 and the central tube 2 and outer tube 5. This combined sealing approach improves the cylinder's operating efficiency.

[0035] The lower piston 6, pressure sleeve 7, limit ring a9, limit ring b10, sleeve change cone 13, and liner 15 constitute the setting limit mechanism of this device. The compression distance of the rubber cylinder 14 is controlled by the distance between the internal boss of the sleeve change cone 13 and the liner 15; the expansion degree of the double Z-type interlocking rubber cylinder expansion anti-rollover mechanism is controlled by the travel distance of the pressure sleeve 7 and the sleeve change cone 13; the travel distance of the hydraulic cylinder is controlled by the distance between the lower piston 6 and the limit ring a9, and the limit ring a9 is embedded in the groove on the outer wall of the center tube 2; at this time, the travel distance of the hydraulic cylinder is the sum of the compression distance of the rubber cylinder 14 and the travel distance of the pressure sleeve 7 and the sleeve change cone 13. The ratio of this distance to the hydraulic cylinder length is preferably 1:4, so as to achieve the purpose of accurately controlling the setting distance. The ratio can be adjusted according to the setting tonnage. The hydraulic cylinder distance can be increased for a large tonnage, and vice versa.

[0036] During the conventional unsealing process, the lifting pipe column carries the center tube 2 and drives the outer tube 5 to be lifted up through the threaded connection between the center tube 2 and the cylinder cover 3. The outer tube 5 slides upward relative to the lower piston 6 and the pressure sleeve 7 until the limit ring a9 embedded in the center tube 2 is stuck, driving the lower piston 6 and then the pressure sleeve 7 to be lifted up, releasing the double Z-type interlocking rubber cylinder expansion anti-flip mechanism, and completing the rubber cylinder unsealing.

[0037] In the event that the sleeve change section cannot complete the conventional unsealing process during the unsealing process, a liquid with a certain degree of mineralization is injected into the wellbore. Under this environment, the upper Z-shaped anti-burst member 11 and the lower Z-shaped anti-burst member 12 made of soluble material dissolve, thereby releasing the expansion support of the rubber cylinder, completing the unsealing and reducing the difficulty of unsealing. Preferably, the sleeve change cone 13 can also be made of soluble material, which can be dissolved together with the upper Z-shaped anti-burst member 11 and the lower Z-shaped anti-burst member 12, making unsealing more convenient. In addition, the sleeve change cone 13 can also be made of heat-sensitive material. During the setting process, the temperature rises and it expands, strengthening the support effect on the rubber cylinder. During the unsealing process, it shrinks as the temperature drops, facilitating unsealing.

[0038] The soluble material is preferably a soluble alloy; the heat-sensitive material is preferably a heat-sensitive alloy.

[0039] Since the rubber tube material of the long rubber tube structure has limited performance in high temperature environment and cannot meet the needs of long-term work, the rubber tube of the present invention is made of short rubber tube high-temperature resistant rubber, which solves the problem of difficulty in unsealing and inability to work in high temperature environment caused by the long rubber tube structure.

[0040] Example 2:

[0041] Applicable working conditions: It is not possible to provide a long-term high-temperature setting environment in the future, but continuous support for the rubber cylinder is required. The structure of the casing-to-well plugging device in this working condition differs from that of Example 1 in that:

[0042] See also Figure 2 A locking ring 8 is embedded in the inner wall of the outer tube 5 and locks onto the outer side of the pressure sleeve 7. This restricts the pressure sleeve 7 from moving in one direction, preventing the rubber sleeve from retracting. The locking ring 8 is made of a soluble material that reacts with mineralized liquids. When unsealed, the locking ring and the soluble component of the Z-shaped interlocking rubber sleeve expansion and anti-flip mechanism dissolve and release together.

[0043] Example 3:

[0044] Applicable working conditions: Using hydraulic pressure as the driving medium, the hydraulic pressure can be maintained all the time. The structure of the casing-changing well plugging device under this working condition is different from that of Example 1 in that no dosing hole or dosing hole plugging is provided on the lower piston 6 or the wall of the outer tube 5, and the lateral hole of the central tube 2 is used as the pressure inlet hole for hydraulic drive. In this case, the device can be used as a hydraulic packer.

[0045] Example 4:

[0046] Applicable working conditions: Using hydraulic pressure as the driving medium, it is impossible to provide a long-term hydraulic environment but it is necessary to provide continuous support for the rubber cylinder. The structure of the casing-changing well plugging device under this working condition is different from that of Example 3 in that the locking ring 8 structure described in Example 2 is embedded in the inner wall of the outer tube 5.

[0047] This invention utilizes a double-Z-shaped interlocking rubber cartridge expansion and anti-flip mechanism with a partially dissolving design. This mechanism controls the compression of the high-expansion rubber cartridge after it passes through the sleeve change section, preventing it from everting. After use, the dissolvable components of the mechanism are dissolved with an electrolyte solution, reducing the difficulty of unsealing and ensuring production. The setting and unsealing distances are adjustable to accommodate the varying expansion requirements of the rubber cartridge for different tubing inner diameters.

[0048] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A casing-change well plugging device with low unblocking difficulty, characterized in that: The invention comprises a central tube (2) and an outer tube (5) sleeved on the outside of the central tube (2), wherein the central tube (2) and the outer tube (5) are connected via a cylinder cover (3); an upper piston (4) and a lower piston (6) are slidingly provided between the central tube (2) and the outer tube (5); a cylinder space is formed between the central tube (2), the outer tube (5), the upper piston (4) and the lower piston (6); a driving medium for driving the lower piston (6) to move is introduced into the cylinder space; a double Z-shaped interlocking rubber cylinder expansion anti-turnover mechanism is fixedly connected to the bottom end of the lower piston (6); the ... The locking rubber tube expansion and anti-turnover mechanism is in sliding connection with the outer wall of the central tube (2) and the inner wall of the outer tube (5), and a sealing pin (23) is connected between the locking rubber tube and the outer tube (5); the outer wall of the lower part of the central tube (2) is sleeved with a liner (15), and the outer wall of the liner (15) is sleeved with a rubber tube (14); the double Z-type interlocking rubber tube expansion and anti-turnover mechanism is driven by the lower piston (6) to slide along the outer wall of the central tube (2) and the inner wall of the outer tube (5) into the interior of the rubber tube (14) or exit from the interior of the rubber tube (14); and the double Z-type interlocking rubber tube expansion and anti-turnover mechanism has a soluble component.

2. A casing-to-well plugging device with low unblocking difficulty according to claim 1, characterized in that: The double Z-shaped interlocking rubber cylinder expansion anti-turnover mechanism comprises a pressure sleeve (7), an upper Z-shaped anti-protrusion piece (11), a lower Z-shaped anti-protrusion piece (12) and a sleeve-changing cone (13), wherein the upper Z-shaped anti-protrusion piece (11) and the lower Z-shaped anti-protrusion piece (12) are made of a soluble material that can react with a mineralized liquid; the outer wall of the pressure sleeve (7) is in sliding contact with the inner wall of the outer tube (5), the sealing pin (23) is connected between the pressure sleeve (7) and the outer tube (5), the bottom end of the lower piston (6) is fixedly connected to the top end of the pressure sleeve (7); the inner wall of the sleeve-changing cone (13) is in sliding contact with the outer wall of the center tube (2), The inner wall of the bottom end of the pressure-bearing sleeve (7) is in sliding contact with the outer wall of the sleeve-changing cone (13); the inner walls of the connected upper Z-shaped anti-protrusion piece (11) and the lower Z-shaped anti-protrusion piece (12) are both in sliding contact with the outer wall of the sleeve-changing cone (13), and the upper Z-shaped anti-protrusion piece (11) and the lower Z-shaped anti-protrusion piece (12) are arranged between the pressure-bearing sleeve (7) and the sleeve-changing cone (13); the end surface of the bottom end of the pressure-bearing sleeve (7) and the top end surface of the upper Z-shaped anti-protrusion piece (11) are set as Z-shaped conical surfaces that can be matched and clamped with each other; the end surface of the bottom end of the lower Z-shaped anti-protrusion piece (12) and the end surface of the side wall of the sleeve-changing cone (13) are set as Z-shaped conical surfaces that can be matched and clamped with each other.

3. The casing-changing well plugging device with low unblocking difficulty according to claim 2 is characterized in that: The sleeve-changing cone (13) is made of a heat-sensitive material or a soluble material that can react with a mineralized liquid.

4. A casing-to-well plugging device with low unblocking difficulty according to claim 3, characterized in that: The outer wall of the central tube (2) is embedded with a limiting ring a (9) for limiting the maximum downward position of the lower piston (6).

5. The casing-to-well plugging device with low unblocking difficulty according to claim 4 is characterized in that: The outer wall of the sleeve-changing cone (13) is provided with a limiting ring b (10) for limiting the maximum retraction position of the pressure-bearing sleeve (7).

6. The casing-to-well plugging device with low unblocking difficulty according to claim 5 is characterized in that: An expandable lower joint (16) is sleeved on the outer wall of the lower portion of the rubber cylinder (14), and a plurality of axially arranged slits are uniformly distributed on the side wall of the lower joint (16).

7. The casing-to-well plugging device with low unblocking difficulty according to claim 5 is characterized in that: The driving medium introduced into the cylinder space is a heat-sensitive agent or hydraulic pressure.

8. The casing-to-well plugging device with low unblocking difficulty according to claim 7 is characterized in that: When the driving medium is a heat-sensitive agent, the heat-sensitive agent is filled into the liquid cylinder space through the dosing hole opened on the lower piston (6) or opened on the wall of the outer tube (5); when the driving medium is hydraulic pressure, the side hole of the central tube (2) is used as the pressure inlet hole, and the sealing device is used as a hydraulic packer.

9. The casing-to-well plugging device with low unblocking difficulty according to claim 8, characterized in that: Under the working condition that the driving medium cannot continuously provide driving force and continuous support is required for the rubber cylinder (14), a locking ring (8) is embedded in the inner wall of the outer tube (5) to limit the unidirectional movement of the pressure sleeve (7), and the locking ring (8) is made of a soluble material that can react with the mineralized liquid.

10. A casing-to-well plugging device with low unblocking difficulty according to any one of claims 1 to 9, characterized in that: Several sealing elements are provided between the upper piston (4), the central tube (2) and the outer tube (5).

11. A casing-to-well plugging device with low unblocking difficulty according to any one of claims 1 to 9, characterized in that: Several sealing elements are provided between the lower piston (6), the central tube (2) and the outer tube (5).

12. A casing-to-well plugging device with low unblocking difficulty according to any one of claims 1 to 9, characterized in that: The rubber cylinder (14) is made of short rubber cylinder high temperature resistant rubber.

Images