A self-setting packer with asymmetric flow channel double insurance mechanism

Abstract

This invention discloses a self-setting packer with an asymmetric flow channel dual insurance mechanism, relating to the field of oil and gas field exploration and development technology. The packer includes an upper connector, a rubber sleeve, a retaining ring, an outer core tube, a middle core tube, a lower connector, an upper sealing cylinder, a piston assembly, an outer sealing cylinder, and an inner sealing cylinder. A low-pressure chamber is provided between the upper sealing cylinder and the piston assembly; a starting chamber and an initial chamber are provided between the piston assembly and the inner sealing cylinder; a helical damping element and a one-way valve are provided between the starting chamber and the initial chamber; the initial chamber is connected to the external wellbore through a fluid inlet channel, and a soluble element is provided at the location of the fluid inlet channel in the initial chamber. This invention constructs an asymmetric fluid control system, which achieves automatic setting by utilizing the hydrostatic pressure of the wellbore, and achieves soft start and anti-missetting through a two-stage cavity buffer delay and a helical damping microchannel. It also incorporates a precision mechanical control mechanism for highly reliable unsealing, combined with a locking pin shearing groove and a tooth retraction mechanism.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field exploration and development technology, specifically to a self-settling packer with an asymmetric flow channel dual insurance mechanism. Background Technology

[0002] In complex operations such as layered water injection, layered fracturing, geothermal resource development, and reservoir testing in oil and gas fields, packers are core downhole tools for achieving effective interlayer isolation and controlling fluid channels. Traditional packers mostly use hydraulic setting (requiring pressurization from a surface pump truck) or mechanical action (requiring lifting and rotating the tubing string) to achieve setting. Self-setting packers, due to their characteristics of not requiring pressurization from a surface pump truck or operation of the tubing string, can automatically trigger setting using the hydrostatic pressure of the wellbore. Currently, mainstream self-setting technology typically uses a soluble element as a time-delay switch. When the tool reaches the predetermined depth, the soluble element gradually dissolves under the action of the high temperature and high pressure fluid environment downhole, thereby opening a channel between the external high-pressure wellbore fluid and the internal chamber. The pressure difference between the two drives the piston to move, which in turn compresses the packer to achieve setting.

[0003] The existing self-seating packers mainly modify the negative pressure chamber and piston mechanism: ① After the self-dissolving switch assembly dissolves, it allows external fluid to enter the piston chamber and directly pushes the piston to compress the rubber cylinder; ② The dissolved material controls the connection between the sealed chamber and the outside, and the piston is driven by the pressure difference of the negative pressure chamber; ③ After the soluble timed sliding sleeve dissolves, it connects the liquid inlet hole with the initial chamber, and the two-stage vacuum piston mechanism is used to achieve the setting seal.

[0004] However, existing self-setting packers still have certain technical defects: ① Once the soluble element completely dissolves, high-pressure wellbore fluid rushes in instantly, causing the piston to generate extremely high initial acceleration under the full differential pressure, violently impacting and compressing the rubber sleeve. This "liquid hammer" effect can easily cause the shoulder of the rubber sleeve to protrude, the rubber material to tear, and even cause the mechanical locking mechanism to break and fail; ② Relying solely on a single soluble element as a delay barrier, if the element breaks or leaks prematurely due to vibration, friction, or corrosion during the downhole process, the tool will instantly start and jam halfway; ③ Existing mechanical locking mostly uses rigid unidirectional locking teeth, which rely on the tubing string to forcefully pull off the packer during unsealing, which can easily cause wear and breakage of the locking teeth, and even damage to the mechanical locking mechanism. Summary of the Invention

[0005] The main objective of this invention is to provide a self-settling packer with a dual-safety mechanism for asymmetric flow channels, in order to overcome the problems existing in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A self-seat packer with an asymmetric flow channel dual safety mechanism includes an upper connector, a rubber sleeve, a retaining ring, an outer core tube, a middle core tube, a lower connector, an upper sealing cylinder, a piston assembly, an outer sealing cylinder, and an inner sealing cylinder; wherein, a low-pressure chamber is provided between the upper sealing cylinder and the piston assembly, a starting chamber and an initial chamber are provided between the piston assembly and the inner sealing cylinder, a helical damping element and a one-way valve are provided between the starting chamber and the initial chamber, the initial chamber is connected to the external wellbore through a fluid inlet channel, and a soluble element is provided at the part of the fluid inlet channel located in the initial chamber; During the setting stage, after the soluble element dissolves, the fluid from the external wellbore enters the initial cavity through the inlet channel. When the initial cavity is filled, the fluid level rises to the inlet height of the helical damping element. After passing through the helical damping microchannel inside the helical damping element, the fluid permeates upward into the starting cavity. When a small amount of fluid enters the starting cavity, the fluid covers the pressure-bearing bottom surface of the piston assembly, converting the hydrostatic pressure of the wellbore into axial starting thrust, causing the piston assembly to move upward and squeeze the rubber sleeve. At this time, the rubber material of the rubber sleeve undergoes viscoelastic creep, uniformly filling the irregular areas of the wellbore casing inner wall to achieve a seal. The helical damping microchannel inside the helical damping element is used to increase the resistance of the fluid flow and control its flow rate. During the unsealing phase, after the rubber sleeve rebounds, the pressure in the starting chamber rapidly rises to the set value. At this time, the one-way valve is opened, and the fluid in the starting chamber flows through the one-way valve, sequentially through the initial chamber and the inlet channel, and merges into the external wellbore, thus achieving unsealing. The flow direction of the one-way valve is from the starting chamber to the external wellbore, which provides a low-resistance, high-flow-rate pressure relief path, eliminates hydraulic lock-up, and allows the piston assembly to quickly reset.

[0007] Furthermore, the helical damping element includes an outer body and an inner core. The outer body has an upper flow channel and a lower flow channel at both ends. A first reserved space is provided between the upper flow channel and the inner core, and a second reserved space is provided between the lower flow channel and the inner core. The helical damping microchannel is located inside the inner core. The inner core has a helical flow channel inlet at the end near the lower flow channel and a helical flow channel outlet at the end near the upper flow channel. The lower flow channel consists of three cylindrical channels, and the upper flow channel consists of one cylindrical channel, forming a three-in-one-out structure. During setting, the fluid first flows in through the three dispersed cylindrical channels, then through the spiral damping microchannel, and finally flows out through the upper cylindrical channel.

[0008] Furthermore, the starting chamber and the initial chamber are configured as a series of two-stage buffer delay chambers to provide a dual, long-lasting reaction time window. When the soluble element is damaged prematurely during the well run, the fluid also needs to fill the initial chamber in sequence, and then slowly enter the starting chamber through the spiral damping microchannel, thereby eliminating the engineering hazard of the packer accidentally setting and getting stuck in the wellbore. The initial chamber is a chamber with a fixed volume, and the starting chamber is a space with a defined annular volume reserved between the pressure-bearing bottom surface of the piston assembly and the upper end surface of the one-way valve.

[0009] Furthermore, the outer sealing cylinder is located between the retaining ring and the lower connector, the inner sealing cylinder is disposed inside the outer sealing cylinder, a pin groove is provided between the inner sealing cylinder and the central core tube, a locking pin is installed in the pin groove, and the two ends of the locking pin are respectively connected to the inner sealing cylinder and the central core tube.

[0010] Furthermore, one side of the outer sealing cylinder is provided with an outer retaining tooth, and the side of the inner sealing cylinder near the outer sealing cylinder is provided with an inner retaining tooth, the inner retaining tooth engaging with the outer retaining tooth.

[0011] Furthermore, during the setting process, the piston assembly drives the outer sealing cylinder to move upward forcibly. The outer teeth of the outer sealing cylinder and the inner teeth of the inner sealing cylinder mesh with each other to form an initial mechanical lock. At the same time, the end of the pin presses against one side of the inner sealing cylinder to limit and support it, forming a mechanical deadlock structure. The mechanical deadlock structure is used to resist the rebound force of the rubber cylinder, ensure the stability of the setting, and prevent seal failure. During the unsealing process, the tubing string is pulled up from the wellhead. The pulling force of the tubing string acts on the locking pin through the core tube. When the pulling force exceeds the set shear strength limit of the locking pin, the locking pin is sheared off. The sheared locking pin fragment falls into the pin groove. After the locking pin falls off, the inner sealing cylinder loses its limiting support and can move to the clearance space behind it. At this time, the compressed rubber sleeve releases its accumulated elastic potential energy and pushes the piston assembly and the outer sealing cylinder downward. When the outer sealing cylinder moves downward, the inclined surface of its outer locking teeth will press against the inclined surface of the inner locking teeth of the inner sealing cylinder. At this time, since the inner sealing cylinder has lost the support of the locking pin and has clearance space, the axial thrust of the outer sealing cylinder is converted into a radial component force on the inner sealing cylinder by the inclined surface, causing the inner sealing cylinder to radially retract, realizing the smooth disengagement of the inner and outer locking teeth.

[0012] Furthermore, the upper connector and the lower connector are respectively connected to the two ends of the central core tube by pins. One end of the upper connector abuts against the end of the rubber tube, and one end of the lower connector abuts against the end of the outer sealing tube. The outer core tube is sleeved on the outside of the central core tube and is located between the rubber tube and the central core tube.

[0013] Furthermore, the rubber tube includes a soft rubber tube in the middle and hard rubber tubes at both ends, and the three retaining rings are respectively disposed at the lower ends of the soft rubber tube and the two hard rubber tubes.

[0014] Furthermore, the one-way valve includes a ball, a spring base, a spring, and a valve seat.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. By introducing a spiral damping microchannel, the instantaneous impact kinetic energy of the high-pressure fluid in the wellbore is converted into potential energy dissipated through the microchannel, thereby achieving precise control of the piston assembly's movement speed. The setting process is transformed from the traditional instantaneous high-pressure "impact" to a smooth and controllable "soft start," effectively avoiding rubber sleeve tearing, shoulder protrusion, and damage to the mechanical structure, significantly extending tool life and reliability. This innovative approach transforms the destructive instantaneous impact of high-pressure fluid into a smooth and controllable soft start. The piston speed is precisely controlled through a hydraulic damping circuit, and Pascal's principle is used to ensure full thrust under microflow, allowing the rubber sleeve to obtain sufficient viscoelastic creep time, achieving perfect fit with the inner wall of the casing, and significantly extending the rubber sleeve's sealing life and setting reliability. 2. This innovative approach combines the chemical delay characteristics of soluble materials with the hydraulic delay effects of two-stage buffer chambers and hydraulic damping elements to form a dual insurance mechanism. Even if the soluble element is accidentally damaged or leaks during well entry, the fluid still needs to fill the initial chamber sequentially and slowly pass through the damping microchannel before starting, eliminating safety hazards. With this approach, the two-stage series buffer structure of the initial chamber and the starting chamber, combined with the chemical delay of the soluble material and the hydraulic delay of the damping element, constructs a "chemical + hydraulic" dual insurance mechanism. 3. A purely mechanical unlocking mechanism was established, which links the locking pin shearing and slotting clearance with the retraction of the locking teeth. This mechanism cleverly utilizes the elastic potential energy of the rubber sleeve to drive the unsealing and quickly releases the pressure in the sealed cavity through the bypass check valve, so as to achieve smooth disengagement of the inner and outer locking teeth. This purely mechanical linkage process eliminates the risks of locking tooth breakage, hydraulic locking and drill string jamming caused by traditional "hard pull" unsealing.

[0016] This invention achieves soft start in the setting process, rapid pressure relief in the unsealing process, and non-destructive disengagement of the locking teeth through an asymmetric fluid control system combining a spiral damping circuit and a one-way valve, a dual insurance mechanism of chemical and hydraulic systems, and methods such as locking pin support, shearing and slotting for clearance, and internal force squeezing to remove the teeth. This effectively ensures the reliability and safety of the tool and perfectly solves the aforementioned industry problems. Attached Figure Description

[0017] Figure 1 This is a cross-sectional view of the overall structure of the present invention.

[0018] Figure 2 This is a diagram of the lower structure of the present invention.

[0019] Figure 3 This is a schematic diagram of the helical damping element structure of the present invention.

[0020] Figure 4 This is a cross-sectional view of the helical damping element of the present invention.

[0021] Figure 5 This is a schematic diagram of the one-way valve structure of the present invention.

[0022] Explanation of reference numerals in the attached drawings: 1-Upper connector; 2-Pin; 3-Pin groove; 4-Rubber sleeve; 5-Retaining ring; 6-Outer core tube; 7-Middle core tube; 8-Starting chamber; 9-Initial chamber; 10-Lower connector; 11-Upper sealing cylinder; 12-Low pressure chamber; 13-Piston assembly; 14-Helical damping element; 15-Locking pin; 16-One-way valve; 17-Outer sealing cylinder; 18-Inner sealing cylinder; 19-Soluble element; 20-Inlet channel; 21-Upper flow channel; 22-Helical flow channel outlet; 23-Helical flow channel inlet; 24-Lower flow channel; 25-First reserved space; 26-Outer body of helical damping element; 27-Inner core of helical damping element; 28-Second reserved space; 29-Spherical body; 30-Spring base; 31-Spring; 32-Valve seat. Detailed Implementation

[0023] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] Combination Figures 1 to 5 This embodiment provides a self-settling packer with a dual insurance mechanism for asymmetric flow channels. Its core lies in an innovative asymmetric fluid control system, which cleverly integrates a spiral damping microchannel and a one-way valve, supplemented by a two-stage buffer delay chamber and a locking pin groove internal sealing cylinder retraction and unlocking mechanism.

[0025] The packer includes an upper connector 1, a rubber sleeve 4, a retaining ring 5, an outer core tube 6, a middle core tube 7, a lower connector 10, an upper sealing cylinder 11, a piston assembly 13, an outer sealing cylinder 17, and an inner sealing cylinder 18. The upper connector 1 and the lower connector 10 are connected to both ends of the middle core tube 7 by pins 2. One end of the upper connector 1 abuts against the end of the rubber sleeve 4, and one end of the lower connector 10 abuts against the end of the outer sealing cylinder 17. The outer core tube 6 is sleeved on the outside of the middle core tube 7 and is located between the rubber sleeve 4 and the middle core tube 7. A low-pressure chamber 12 is provided between the upper sealing cylinder 11 and the piston assembly 13. A starting chamber 8 and an initial chamber 9 are provided between the piston assembly 13 and the inner sealing cylinder 18. A spiral damping element 14 and a one-way valve 16 are provided between the starting chamber 8 and the initial chamber 9. The initial chamber 9 is connected to the outer wellbore through a liquid inlet channel 20. A soluble element 19 is provided at the location of the liquid inlet channel 20 in the initial chamber 9. During the setting stage, after the soluble element 19 dissolves, the fluid from the external wellbore enters the initial chamber 9 through the inlet channel 20. When the fluid fills the initial chamber 9, the fluid level rises to the inlet height of the spiral damping element 14. After passing through the spiral damping microchannel inside the spiral damping element 14, the fluid permeates upwards to the starting chamber 8. When a small amount of fluid enters the starting chamber 8, the fluid covers the pressure-bearing bottom surface of the piston assembly 13, converting the hydrostatic pressure of the wellbore into axial starting thrust, causing the piston assembly 13 to move upwards and squeeze the rubber sleeve 4. At this time, the rubber material of the rubber sleeve 4 undergoes viscoelastic creep, uniformly filling the irregular areas of the inner wall of the wellbore casing, thus achieving a seal. The spiral damping microchannel inside the spiral damping element 14 is used to increase the resistance of the fluid flow and control its flow rate. During the unsealing phase, after the rubber sleeve 4 rebounds, the pressure in the starting chamber 8 rapidly rises to the set value. At this time, the one-way valve 16 is opened, and the fluid in the starting chamber 8 flows through the one-way valve 16 and then through the initial chamber 9 and the inlet channel 20 in sequence, and flows into the external wellbore to achieve unsealing. The flow direction of the one-way valve 16 is from the starting chamber 8 to the external wellbore, which is used to provide a low-resistance, high-flow pressure relief path, eliminate hydraulic lock-up, and enable the piston assembly 13 to quickly reset.

[0026] The above-described scheme constitutes the asymmetric fluid control system of this invention, which is the core innovation of this invention. Through ingenious fluid channel design, it provides distinctly different fluid control characteristics during the setting and unsetting phases: The first is the set-sealing flow path: with the spiral damping microchannel as the core, after the soluble element 19 dissolves, the external wellbore fluid first enters the preset fixed volume initial cavity 9 through the arm-shaped inlet channel 20; the fluid only begins to permeate into the upper start-up cavity 8 when the lower part of the initial cavity 9 is completely filled and the liquid level rises to the inlet height of the spiral damping element 14; the spiral damping element 14 has a precision-machined spiral damping microchannel with an ultra-high aspect ratio inside, and its design simulates the characteristics of high-damping capillary fluid, significantly improving the resistance of fluid flow and achieving precise control of flow rate; a certain volume of reserved sand settling space is provided on the outside of its inlet and outlet ends to prevent solid particles from clogging; the fluid first flows in through three dispersed small cylindrical channels, then through the spirally rising damping channel, and finally flows out through the upper large channel, forming a unique "three-in-one-out" structure; During the setting stage, this hydraulic damping circuit strictly limits the rate at which fluid flows into the starting chamber 8, thereby converting the instantaneous impact kinetic energy of the external high-pressure fluid on the piston assembly 13 (piston and piston rod) into energy dissipated through the microchannel, achieving a continuous and stable low-speed thrust. After a small amount of fluid enters the starting chamber 8, it quickly fills the pressure-bearing bottom surface of the piston. The system utilizes Pascal's principle to convert the hydrostatic pressure of the wellbore into a huge axial starting thrust. The piston assembly moves upward at an extremely slow and constant speed, squeezing the rubber sleeve 4, allowing the rubber material sufficient time to undergo viscoelastic creep, uniformly and perfectly filling the irregular areas of the casing inner wall, achieving a highly efficient and reliable seal.

[0027] Secondly, the unsealing flow path: Centered on the one-way valve flow channel, the flow direction of the one-way valve 16 is strictly limited to from the starting chamber 8 towards the external wellbore. During setting, because the external wellbore fluid pressure is always higher than the internal pressure of the starting chamber 8, the one-way valve 16 remains closed under the pressure difference, forcing all fluid to enter the starting chamber 8 through the high-damping spiral microchannel. During the unsealing phase, when the pressure inside the starting chamber 8 rapidly rises to the set value due to the rebound of the rubber sleeve 4, the one-way valve 16 is opened, providing a low-resistance, high-flow-rate pressure relief path. This ensures that the piston assembly 13 can quickly reset, completely eliminating hydraulic lock-up, thereby guaranteeing smooth and reliable unsealing.

[0028] In this embodiment, the starting chamber 8 and the initial chamber 9 are configured as two-stage buffer delay chambers connected in series to provide a dual, long-term reaction time window. When the soluble element 19 is damaged prematurely during the well run, the fluid also needs to fill the initial chamber 9 in sequence, and then slowly enter the starting chamber 8 through the spiral damping microchannel, thereby eliminating the engineering hazard of the packer accidentally setting and getting stuck in the middle of the well. The initial chamber 9 is a chamber with a fixed volume, and the starting chamber 8 is a space with a defined annular volume reserved between the pressure-bearing bottom surface of the piston assembly 13 and the upper end surface of the one-way valve 16.

[0029] This design employs a two-stage, cascaded buffer delay chamber as a second hydraulic delay safety measure following the chemical delay: After the fully encapsulated soluble material dissolves, the external wellbore fluid first enters the initial chamber 9, which has a fixed volume, through the arm-shaped inlet channel 20. At this stage, the fluid only fills the lower part of the initial chamber 9 and does not immediately contact the helical damping element 14. This process provides the first pure volumetric filling time delay, the length of which can be designed based on the volume of the initial chamber 9 and the wellbore fluid injection rate. Only when the liquid level rises to the inlet height of the helical damping element 14 does the fluid begin to permeate through the helical damping element into the upper starting chamber 8. The starting chamber 8 is a space with a defined annular volume (≥5 mL) reserved between the piston's pressure-bearing bottom surface and the upper end face of the one-way valve 16.

[0030] This unique series architecture provides a dual, long-lasting reaction time window. Even if the soluble plug is accidentally damaged or leaks prematurely during the well run due to vibration, friction, corrosion, or other reasons, the fluid must fill the initial cavity sequentially before slowly entering the starting cavity through the high-damping microchannel. This fundamentally eliminates the serious engineering hazard of the tool accidentally setting and getting stuck in the wellbore, greatly improving the safety of well run operations.

[0031] like Figure 1-2 As shown, in this embodiment, the outer sealing cylinder 17 is located between the retaining ring 5 and the lower connector 10, and the inner sealing cylinder 18 is disposed inside the outer sealing cylinder 17. A pin groove 3 is provided between the inner sealing cylinder 18 and the central core tube 7, and a locking pin 15 is installed in the pin groove 3. The two ends of the locking pin 15 are respectively connected to the inner sealing cylinder 18 and the central core tube 7. An outer locking tooth is provided on one side of the outer sealing cylinder 17, and an inner locking tooth is provided on the side of the inner sealing cylinder 18 near the outer sealing cylinder 17. The inner locking tooth engages with the outer locking tooth.

[0032] During the setting process, the piston assembly 13 drives the outer sealing cylinder 17 to move upward forcibly. The outer teeth of the outer sealing cylinder 17 and the inner teeth of the inner sealing cylinder 18 mesh with each other to form an initial mechanical lock. At the same time, the end of the locking pin 15 presses against one side of the inner sealing cylinder 18 to limit and support it, preventing it from moving radially and forming a mechanical deadlock structure. The mechanical deadlock structure is used to resist the rebound force of the rubber sleeve 4, ensure the stability of the setting, and prevent the seal from failing. During the unsealing process, the tubing string is pulled up from the wellhead. The pulling force of the tubing string acts on the locking pin 15 through the core tube 7. When the pulling force exceeds the set shear strength limit of the locking pin 15, the locking pin 15 is sheared off, and the sheared pin fragment falls into the pin groove 3 (this is the pin falling into the groove). After the locking pin 15 falls off, the internal sealing cylinder 18 loses its limiting support and can move to the clearance space behind it (internal sealing cylinder clearance). At this time, the rubber cylinder 4, which is in a compressed state, releases its accumulated elastic potential energy and pushes the piston assembly 13 downward. When the outer sealing cylinder 17 descends, the inclined surface of its outer locking teeth will press against the inclined surface of the inner locking teeth of the inner sealing cylinder 18. At this time, since the inner sealing cylinder 18 has lost the support of the locking pin 15 and has room to retreat, the axial thrust of the outer sealing cylinder 17 is converted into a radial component force on the inner sealing cylinder 18 by the inclined surface, causing the inner sealing cylinder 18 to retreat radially, realizing the smooth disengagement of the inner and outer locking teeth, completely avoiding the risk of "tooth breakage" and tool damage caused by traditional "hard pull" unsealing, and significantly improving the reliability and safety of unsealing.

[0033] like Figure 3-4 As shown, in this embodiment, the helical damping element 14 includes an outer body 26 and an inner core 27 located inside it. The outer body 26 has an upper flow channel 21 and a lower flow channel 24 at both ends. A first reserved space 25 is provided between the upper flow channel 21 and the inner core 27, and a second reserved space 28 is provided between the lower flow channel 24 and the inner core 27. The helical damping microchannel is located inside the inner core 27. The inner core 27 has a helical flow channel inlet 23 at one end near the lower flow channel 24 and a helical flow channel outlet 22 at one end near the upper flow channel 21. The lower flow channel 24 consists of three cylindrical channels, and the upper flow channel 21 consists of one cylindrical channel, forming a three-inlet-one-outlet structure. During setting, the fluid first flows in through the three dispersed cylindrical channels, then through the helical damping microchannel, and finally flows out through the upper cylindrical channel.

[0034] like Figure 5 As shown, in this embodiment, the one-way valve includes a ball 29, a spring base 30, a spring 31, and a valve seat 32.

[0035] In a further embodiment, the rubber tube 4 includes a soft rubber tube in the middle and hard rubber tubes at both ends, and three retaining rings 5 ​​are respectively disposed at the lower ends of the soft rubber tube and the two hard rubber tubes.

[0036] The working principle of this invention is based on fluid mechanics and mechanical linkage, and consists of two core processes: setting and unsetting. Setting process: The packer is connected to the tubing string and lowered into the wellbore. At this time, the fully encapsulated soluble element 19 acts as the first physical barrier to seal the inlet. After reaching the predetermined depth, under the action of well temperature and wellbore fluid, the soluble material gradually dissolves, allowing the arm-shaped inlet channel 20 to connect with the external wellbore. There is a huge pressure difference between the high-pressure fluid outside the wellbore and the low-pressure chamber 12. The fluid first enters the initial chamber 9 through the inlet channel 20, filling the lower part of the chamber. This process provides the first volume filling time delay. When the liquid level rises and contacts the inlet of the spiral damping element 14, the fluid is forced into the ultra-long-diameter spiral microchannel inside. Due to the strong damping effect of the microchannel, the flow rate is strictly limited. The fluid slowly enters the starting chamber 8 at a controlled, extremely slow speed. At this time, the pressure in the starting chamber 8 is rapidly established and, according to Pascal's principle, acts evenly on the entire bottom surface of the piston and piston rod, generating a huge axial thrust. The piston assembly moves smoothly upwards at a constant and extremely slow speed (design target approximately 1-2 mm / min), first compressing the metal retaining ring 5, then compressing the rubber sleeve 4. The shoulder of the upper connector 1 is fixed, so the rubber sleeve 4 can only expand radially outwards. The soft rubber sleeve in the middle has sufficient time to undergo viscoelastic creep under the slow push of the piston, uniformly and fully filling the sleeve defects. The retaining rings of the hard rubber sleeves at both ends open to prevent the soft rubber sleeves from being over-extended. The outer sealing sleeve 17 connected to the piston moves upwards with the piston assembly, and its outer locking teeth mesh with the inner locking teeth of the inner sealing sleeve to achieve mechanical locking. At the same time, the release pin rigidly presses against the inner sealing sleeve 18, preventing the locking teeth on it from retracting. The rebound force of the rubber sleeve is completely balanced by this absolute mechanical deadlock, and the setting process is completed smoothly and firmly.

[0037] Unsealing process: The tubing string is pulled up from the wellhead. The pulling force of the tubing string acts directly on the locking pin 15 through the core tube 7. When the combined force of the pulling force and the friction between the rubber sleeve 4 and the casing wall exceeds the set shear strength of the locking pin 15, the locking pin 15 is cleanly sheared off. The sheared lock pin 15 fragments will automatically fall into the pre-reserved pin groove 3 at the bottom. After losing the support of the locking pin 15, the radial constraint of the inner sealing cylinder 18 is released, gaining a small free space. The huge elastic potential energy accumulated by the rubber sleeve 4 is released instantly, pushing the piston assembly and the outer sealing cylinder 17 downward with great force. During the downward movement of the outer sealing cylinder 17, the inclined surface of its outer retaining teeth presses against the inclined surface of the inner retaining teeth of the inner sealing cylinder 18. The axial thrust of the outer sealing cylinder 17 is cleverly converted into a radial component force by the inclined surface, forcing the inner sealing cylinder 18 to produce a small radial yield. This purely mechanical linkage action allows the inner and outer locking teeth to disengage smoothly and instantly without resistance, completely avoiding the risk of "tooth breakage". When the rubber sleeve 4 rebounds rapidly, it quickly squeezes the liquid in the starting chamber 8, and the pressure inside the chamber rises instantly. This high pressure then opens the bypass check valve 16, and the liquid inside the chamber is quickly discharged into the external wellbore through the large-diameter channel.

[0038] The technical solution of this invention achieves soft start in the setting process, rapid pressure relief in the unsealing process, and non-destructive disengagement of the locking teeth through an asymmetric fluid control system combining a spiral damping circuit and a one-way valve, a dual insurance mechanism of chemical and hydraulic systems, and methods such as pin support locking, shearing and slotting clearance, and internal force squeezing to remove the teeth. This effectively ensures the reliability and safety of the tool and perfectly solves the aforementioned industry problems.

[0039] This technology, centered on "hydraulic damping soft start, two-stage buffer delay to prevent accidental activation, and pin-feedback-free unsealing," overcomes the technical bottlenecks of traditional self-sealing tools, which suffer from "impact upon start-up, easy accidental activation during operation, and easy stuck drill bit during unsealing." As the development of deep shale gas and geothermal resources in China enters deep-water areas, well conditions are becoming increasingly complex, and the demand for high reliability, adequate sealing, and safe recovery is becoming increasingly urgent. This invention provides a low-cost, high-safety, and long-life solution for well completion operations under complex well conditions, and has broad prospects for widespread application.

[0040] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A self-seating packer with a dual-safety mechanism for asymmetric flow channels, characterized in that, It includes an upper connector (1), a rubber sleeve (4), a retaining ring (5), an outer core tube (6), a middle core tube (7), a lower connector (10), an upper sealing cylinder (11), a piston assembly (13), an outer sealing cylinder (17), and an inner sealing cylinder (18); wherein, a low-pressure chamber (12) is provided between the upper sealing cylinder (11) and the piston assembly (13), a starting chamber (8) and an initial chamber (9) are provided between the piston assembly (13) and the inner sealing cylinder (18), a spiral damping element (14) and a one-way valve (16) are provided between the starting chamber (8) and the initial chamber (9), and the initial chamber (9) is connected to the outer wellbore through a liquid inlet channel (20), and a soluble element (19) is provided at the part of the liquid inlet channel (20) located in the initial chamber (9). During the setting stage, after the soluble element (19) dissolves, the fluid from the external wellbore enters the initial chamber (9) through the inlet channel (20). When the fluid fills the initial chamber (9) and the liquid level rises to the inlet height of the spiral damping element (14), the fluid permeates into the upper starting chamber (8) after passing through the spiral damping microchannel inside the spiral damping element (14). When a small amount of fluid enters the starting chamber (8), the fluid covers the pressure-bearing bottom surface of the piston assembly (13), converting the hydrostatic pressure of the wellbore into axial starting thrust, causing the piston assembly (13) to move upward and squeeze the rubber sleeve (4). At this time, the rubber material of the rubber sleeve (4) undergoes viscoelastic creep, uniformly filling the irregular parts of the inner wall of the wellbore casing to achieve sealing. The spiral damping microchannel inside the spiral damping element (14) is used to increase the resistance of the fluid flow and control its flow rate. During the unsealing phase, after the rubber sleeve (4) rebounds, the pressure in the starting chamber (8) rapidly rises to the set value. At this time, the one-way valve (16) is opened, and the fluid in the starting chamber (8) flows through the one-way valve (16) and then sequentially through the initial chamber (9) and the inlet channel (20), and flows into the external wellbore to achieve unsealing. The flow direction of the one-way valve (16) is from the starting chamber (8) to the external wellbore, which is used to provide a low-resistance, high-flow pressure relief path, eliminate hydraulic lock-up, and enable the piston assembly (13) to quickly reset.

2. The self-seat packer with an asymmetric flow channel dual insurance mechanism as described in claim 1, characterized in that, The helical damping element (14) includes an outer body (26) and an inner core (27) located inside it. The outer body (26) has an upper flow channel (21) and a lower flow channel (24) at both ends. A first reserved space (25) is provided between the upper flow channel (21) and the inner core (27), and a second reserved space (28) is provided between the lower flow channel (24) and the inner core (27). The helical damping microchannel is located inside the inner core (27). The inner core (27) has a helical flow channel inlet (23) at one end near the lower flow channel (24) and a helical flow channel outlet (22) at one end near the upper flow channel (21). The lower flow channel (24) consists of three cylindrical channels, and the upper flow channel (21) consists of one cylindrical channel, forming a three-in-one-out structure. During the setting process, the fluid first flows in through the three dispersed cylindrical channels, then through the spiral damping microchannel, and finally flows out through the upper cylindrical channel.

3. A self-seat packer with an asymmetric flow channel dual insurance mechanism as described in claim 1, characterized in that, The starting chamber (8) and the initial chamber (9) are set as two-stage buffer delay chambers in series to provide a dual, long-term reaction time window. When the soluble element (19) is damaged prematurely during the well running process, the fluid also needs to fill the initial chamber (9) in sequence, and then slowly enter the starting chamber (8) through the spiral damping microchannel, thereby eliminating the engineering hazard of the packer being accidentally set and stuck in the middle of the well. The initial chamber (9) is a chamber with a fixed volume, and the starting chamber (8) is a space with a defined annular volume reserved between the pressure-bearing bottom surface of the piston assembly (13) and the upper end surface of the one-way valve (16).

4. A self-seat packer with an asymmetric flow channel dual insurance mechanism as described in claim 1, characterized in that, The outer sealing cylinder (17) is located between the retaining ring (5) and the lower connector (10). The inner sealing cylinder (18) is located inside the outer sealing cylinder (17). A pin groove (3) is provided between the inner sealing cylinder (18) and the central core tube (7). A locking pin (15) is installed in the pin groove (3). The two ends of the locking pin (15) are respectively connected to the inner sealing cylinder (18) and the central core tube (7).

5. A self-seat packer with an asymmetric flow channel dual insurance mechanism as described in claim 4, characterized in that, The outer sealing cylinder (17) has an outer locking tooth on one side, and the inner sealing cylinder (18) has an inner locking tooth on the side near the outer sealing cylinder (17), and the inner locking tooth engages with the outer locking tooth.

6. A self-seating packer with an asymmetric flow channel dual insurance mechanism as described in claim 5, characterized in that, During the setting process, the piston assembly (13) drives the outer sealing cylinder (17) to move upward forcibly. The outer teeth of the outer sealing cylinder (17) and the inner teeth of the inner sealing cylinder (18) mesh with each other to form an initial mechanical lock. At the same time, the end of the locking pin (15) presses against one side of the inner sealing cylinder (18) to limit and support it, forming a mechanical deadlock structure. The mechanical deadlock structure is used to resist the rebound force of the rubber cylinder (4), ensure the stability of the setting, and prevent the seal from failing. During the unsealing process, the tubing string is pulled up from the wellhead. The pulling force of the tubing string acts on the locking pin (15) through the core tube (7). When the pulling force exceeds the set shear strength limit of the locking pin (15), the locking pin (15) is sheared off. The sheared pin fragments fall into the pin groove (3). After the locking pin (15) falls off, the inner sealing cylinder (18) loses its limiting support and can move to the back clearance space. At this time, the rubber cylinder (4) in the compressed state releases its accumulated elastic potential energy. Push the piston assembly (13) and the outer sealing cylinder (17) downwards. When the outer sealing cylinder (17) moves downwards, the inclined surface of its outer locking teeth will press against the inclined surface of the inner locking teeth of the inner sealing cylinder (18). At this time, since the inner sealing cylinder (18) has lost the support of the locking pin (15) and has room to retreat, the axial thrust of the outer sealing cylinder (17) is converted into a radial component force on the inner sealing cylinder (18) by the inclined surface, causing the inner sealing cylinder (18) to retreat radially, thus achieving smooth disengagement of the inner locking teeth and the outer locking teeth.

7. A self-seat packer with an asymmetric flow channel dual insurance mechanism as described in claim 1, characterized in that, The upper connector (1) and the lower connector (10) are respectively connected to the two ends of the central tube (7) by pins (2). One end of the upper connector (1) abuts against the end of the rubber tube (4), and one end of the lower connector (10) abuts against the end of the outer sealing tube (17). The outer core tube (6) is sleeved on the outside of the central core tube (7) and is located between the rubber tube (4) and the central core tube (7).

8. A self-seating packer with an asymmetric flow channel dual insurance mechanism as described in claim 1 or 7, characterized in that, The rubber tube (4) includes a soft rubber tube in the middle and hard rubber tubes at both ends, and three retaining rings (5) are respectively disposed at the lower ends of the soft rubber tube and the two hard rubber tubes.

9. A self-seating packer with an asymmetric flow channel dual insurance mechanism as described in claim 1, characterized in that, The one-way valve includes a ball (29), a spring base (30), a spring (31), and a valve seat (32).

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