A step-by-step unblocking packer and its unblocking method

Abstract

This invention discloses a step-by-step unsealing packer and its unsealing method, belonging to the field of oilfield downhole tool technology. It comprises an upper connector, an upper central tube, a connecting seat, a lower central tube, a lower connector, a fixing seat, an unsealing seat, an upper central tube, a positioning seat, an unsealing sleeve, and an upper rubber sleeve seat, forming a step-by-step unsealing sealed cavity. This cavity is isolated from the well fluid and is unaffected by pressure fluctuations and packer creep, preventing premature unsealing. The outer wall of the upper central tube has an annular groove, and the positioning seat has a radial through hole. Half of the steel ball is placed in the groove, and half in the through hole. The unsealing seat is fitted outside the positioning seat and radially limits the steel ball. During unsealing, the tubing string is lifted to shear the unsealing pin, the unsealing seat moves upward to release the limit on the steel ball, the positioning seat moves upward to drive the steel ball out of the groove to unlock, and simultaneously the fluid outlet of the upper rubber sleeve seat opens to release pressure. The upper rubber sleeve seat moves upward to stretch the rubber sleeve, forcibly contracting and resetting it, solving the problem of the rubber sleeve getting stuck in the well. This invention is applicable to multi-stage fracturing, water injection, and oil production operations.

Description

Technical Field

[0001] This invention relates to the field of downhole tools technology, and in particular to a step-by-step unsealing packer and its unsealing method for multi-stage fracturing, stratified water injection and stratified oil production operations. Background Technology

[0002] In stratified water injection operations in oilfields, multiple packers are typically installed in series within a single injection well to effectively separate different layers. Conventional packers generally employ a pin-shearing release mechanism. This mechanism works by lifting the tubing string using surface equipment, using the lifting force to sequentially shear the release pins of each packer stage, causing the rubber sleeve to retract and releasing the seal. When multiple packers are used in series, the release pins of each packer stage simultaneously bear shear force, resulting in an accumulated upward release force as the number of packer stages increases. When there are many packer stages (e.g., 6-9 stages in stratified water injection), the required release force may exceed the lifting capacity of the equipment, causing the packing string to become stuck or jammed. In some cases, operators must use complex methods such as reverse cutting and milling to handle the situation, significantly increasing operating costs and safety risks. Secondly, after the packer is working downhole, it is corroded by the well fluid, and the inside of the unsealing mechanism will rust and scale, making it difficult for the packer unsealing mechanism to move or get stuck. The step-by-step unsealing function will fail, and when the tubing string is pulled up, it will drive the entire tubing string to move, increasing the load on the tubing string, which will also cause the packer to get stuck and the risk of major workover.

[0003] Chinese utility model patent CN205532529U, published on September 2, 2015, discloses an environmentally friendly, washable, step-by-step unsealing packer for wells. The packer includes a central tube, an upper connector, an upper core tube, an upper outer sleeve, a locking sleeve, an outer core tube, a rubber sleeve, and a lower connector. The upper connector is fitted onto the central tube, and the upper core tube is located within the cavity between the upper connector and the central tube. The upper end of the upper core tube is connected to the central tube. The upper outer sleeve is fitted onto the upper core tube, and its upper end is connected to the upper connector. The locking sleeve is fitted onto the lower end of the upper outer sleeve. A retaining ring is located within the cavity between the locking sleeve and the central tube, and the retaining ring is mounted on a retaining ring seat. The outer core tube is fitted onto the central tube, and its upper end is connected to the retaining ring seat. The rubber sleeve is located between the locking sleeve and the lower connector, and its upper and lower ends are respectively provided with an upper rubber sleeve seat and a lower rubber sleeve seat. The lower connector is connected to the central tube.

[0004] This packer has a step-by-step unsealing function. However, when the cavity between the central tube and the balance piston is immersed in the well fluid and operates in the wellbore for 1-2 years, rust and scale will form on the outer wall of the central tube. The longer the time, the thicker the scale becomes, with an average scale thickness of over 2 mm. When the packer is unsealed, the tubing string is lifted, and the upper connector moves the upper outer sleeve and the balance piston upwards. The balance piston may get stuck on the scale on the outer wall of the central tube, preventing it from moving. Therefore, the step-by-step unsealing action of the packer cannot be completed after the tubing string is lifted; only the packer as a whole moves upwards. At this point, the step-by-step unsealing function fails, and multiple packers move upwards with the tubing string, increasing the load on the tubing string and increasing the risk of stuck wells or the packer being unable to be pulled out. Summary of the Invention

[0005] This invention provides a step-by-step unsealing packer and its unsealing method, mainly solving the problems of step-by-step unsealing mechanism failure due to rust and scaling, packer easy premature unsealing due to pressure fluctuations or peristalsis during operation, and the rubber sleeve being easy to get stuck in the well and difficult to retract and reset during unsealing.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A step-by-step release packer includes an upper connector, an upper central tube, a connecting seat, a lower central tube, and a lower connector. The upper connector has a fixed seat inside and a release seat outside, connected by threads. The release seat is fitted onto the fixed seat and the upper central tube. A positioning seat and an upper rubber sleeve seat are fitted onto the upper central tube, connected by threads. A release seat and a release sleeve are fitted onto the positioning seat, connected by threads. The fixed seat, release seat, upper central tube, positioning seat, release sleeve, and upper rubber sleeve seat form a step-by-step release sealed cavity, which does not contact well fluid and is free from rust and scaling.

[0007] The upper rubber sleeve seat, rubber sleeve, and lower rubber sleeve seat are sequentially threaded together. The upper central tube, lower rubber sleeve seat, and connecting seat are threaded together. The connecting seat, lower central tube, and lower connector are sequentially threaded together. A seat seal and locking teeth are fitted onto the outside of the connecting seat. A seat sealing piston is fitted onto the outside of the lower central tube. A sealing cylinder is fitted onto the outside of the seat seal. A lower outer cylinder is fitted onto the outside of the seat sealing piston. The lower rubber sleeve seat and sealing cylinder are threaded together. The lower connector and lower outer cylinder are threaded together. The upper connector and fixed seat are fixedly connected by a release pin. The upper central tube and positioning seat are fixed by a steel ball to ensure that the packer will not prematurely release during operation. The sealing cylinder and seat seal are fixedly connected by a seat sealing pin.

[0008] Preferably, the upper glue tube seat is provided with a liquid outlet hole, which has a pressure relief function when unsealed; the lower glue tube seat is provided with a liquid inlet hole, the connecting seat is provided with a liquid inlet hole, and the lower central tube is provided with a liquid inlet hole.

[0009] Preferably, the upper connector and the unsealing seat, and the upper connector and the upper central tube are sealed by sealing elements; the fixed seat and the unsealing seat, and the fixed seat and the upper central tube are sealed by sealing elements; the unsealing seat and the upper central tube, and the unsealing seat and the unsealing sleeve are sealed by sealing elements; the upper central tube and the upper rubber sleeve seat, and the upper central tube and the connecting seat are sealed by sealing elements; the unsealing sleeve and the upper rubber sleeve seat are sealed by sealing elements; the lower rubber sleeve seat and the sealing cylinder are sealed by sealing elements; the sealing cylinder and the seat sealing sleeve are sealed by sealing elements; the connecting seat and the seat sealing sleeve, and the connecting seat and the lower central tube are sealed by sealing elements; the seat sealing piston and the lower central tube, and the seat sealing piston and the lower outer cylinder are sealed by sealing elements; the lower outer cylinder and the lower connector are sealed by sealing elements.

[0010] Preferably, the outer wall of the upper central tube is provided with an annular groove, and the positioning seat is provided with a radial through hole, which is evenly divided into 8 to 12 parts on the circumference. Half of the steel ball is placed in the annular groove of the upper central tube, and the other half is placed in the radial through hole of the positioning seat. The unsealing seat is sleeved on the outside of the positioning seat, and the inner wall of the unsealing seat forms a radial limit on the outer edge of the steel ball, preventing the steel ball from moving outward. When the packer is in the sealing working state, regardless of the pressure fluctuation inside the tube or the peristaltic action of the packer, the inner wall of the unsealing seat always maintains a radial limit on the steel ball, and the steel ball cannot be dislodged from the annular groove, and the upper central tube and the positioning seat remain locked. When unsealing is required, the unsealing seat moves upward relative to the positioning seat, the radial limit on the steel ball by the inner wall of the unsealing seat is released, and when the positioning seat moves upward, the wall of its radial through hole drives the steel ball to slide out of the annular groove, thereby unlocking the upper central tube and the positioning seat.

[0011] A method for unsealing using the above-mentioned step-by-step unsealing packer includes the following steps: A1: Lift the tubing string, causing the upper connector, unsealing seat, and unsealing sleeve to move upwards; A2: When the lifting force reaches the shear force value of the unsealing pin, the unsealing pin is sheared off; A3: The upper connector, unsealing seat, and unsealing sleeve slide upward relative to the fixed seat; A4: When the unsealing sleeve moves upward to the lower end of the positioning seat, the liquid outlet of the upper rubber sleeve seat opens to release pressure and accelerate the shrinkage of the rubber sleeve. A5: When the unsealing seat moves upward to the lower end face limit of the fixed seat, the radial limit of the unsealing seat inner wall on the steel ball is released; A6: The upper connector, unsealing seat, and unsealing sleeve continue to move upward and drive the positioning seat and upper rubber sleeve seat upward. The radial through hole wall of the positioning seat drives the steel ball to slide upward along the groove on the outer wall of the upper central tube. The steel ball comes out of the groove, and the upper central tube is unlocked from the positioning seat. A7: The upper glue tube seat moves upward and stretches the glue tube, forcibly shrinking and resetting the glue tube; A8: Continue to lift the tubing string, and release each packer in sequence.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. Preventing premature unsealing: The fixed seat, unsealing seat, upper central tube, positioning seat, unsealing sleeve, and upper rubber sleeve seat form a step-by-step unsealing sealed cavity. This cavity is completely isolated from the well fluid. It does not rust or scale inside the cavity and is not affected by pressure fluctuations inside the tube or packer creep. It will not unseale prematurely in the working state, thus improving the working reliability of the packer.

[0013] 2. Stable and reliable locking mechanism: Half of the steel ball is placed in the groove of the upper central tube and the other half is placed in the radial through hole of the positioning seat. The release seat is sleeved outside the positioning seat to form a radial limit on the steel ball. After sealing, no matter how the pressure fluctuates or how the packer creeps, the steel ball cannot come out, which solves the problem of existing locking mechanisms prematurely opening the positioning seat and leaking the steel ball due to pressure or creep.

[0014] 3. Dual protection for unsealing: During unsealing, the outlet hole opens to release pressure, causing the rubber sleeve to contract rapidly; simultaneously, the upper rubber sleeve seat moves upward to stretch the rubber sleeve, forcing it to reset. The combination of pressure relief and stretching effectively solves the problem of the rubber sleeve getting stuck in the well and not contracting.

[0015] 4. Controllable unsealing sequence: Each packer is unsealed sequentially from top to bottom, avoiding the impact and jamming caused by simultaneous unsealing. It is suitable for multi-stage fracturing, water injection and oil production operations. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a step-by-step desealing packer structure according to the present invention; Figure 2 This is a partially enlarged schematic diagram of the steel ball locking mechanism; Figure 3 A 3D diagram of the positioning seat; Figure 4 This is a partial schematic diagram of the step-by-step unsealing operation steps A1-A5 of the present invention; Figure 5 This is a partial schematic diagram (A6-A8) illustrating the step-by-step unsealing operation steps of the packer according to the present invention. In the diagram: 1. Upper connector; 2. Fixed seat; 3. Unsealing seat; 4. Upper central tube; 5. Positioning seat; 6. Unsealing sleeve; 7. Upper rubber tube seat; 8. Rubber tube; 9. Lower rubber tube seat; 10. Sealing tube; 11. Connecting seat; 12. Sealing sleeve; 13. Locking tooth; 14. Lower central tube; 15. Sealing piston; 16. Lower outer cylinder; 17. Lower connector; 18. Unsealing pin; 19. Steel ball; 20. Sealing pin; A. Enlarged schematic diagram of the locking ball mechanism. Detailed Implementation

[0017] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0018] Example 1

[0019] like Figure 1 As shown, a step-by-step desealing packer includes an upper connector 1, an upper central tube 4, a connecting seat 11, a lower central tube 14, and a lower connector 17.

[0020] The upper connector 1 has a fixed seat 2 inside and a release seat 3 outside, and the upper connector 1 and the release seat 3 are connected by threads. The release seat 3 is fitted onto the fixed seat 2 and the upper central tube 4. The upper central tube 4 is fitted with a positioning seat 5 and an upper glue tube seat 7, and the positioning seat 4 and the upper glue tube seat 7 are connected by threads. The positioning seat 5 is fitted with a release seat 3 and a release sleeve 6, and the release seat 3 and the release sleeve 6 are connected by threads.

[0021] The fixed seat 2, unsealing seat 3, upper central tube 4, positioning seat 5, unsealing sleeve 6, and upper rubber sleeve seat 7 form a step-by-step unsealing sealed chamber. This sealed chamber is completely isolated from the well fluid during packer operation, remaining clean and free from rust and scaling, thus preventing seal failure due to well fluid corrosion or scaling. Furthermore, because this sealed chamber is a closed structure, it is unaffected by pressure fluctuations within the tube or packer creep, effectively preventing premature unsealing of the packer during operation.

[0022] The upper glue tube seat 7 is connected to the glue tube 8 and the lower glue tube seat 9 by threads in sequence. The upper central tube 4 is connected to the lower glue tube seat 9 and the connecting seat 11 by threads in sequence. The connecting seat 11 is connected to the lower central tube 14 and the lower connector 17 by threads in sequence.

[0023] The connecting seat 11 is externally fitted with a seat seal 12 and a locking tooth 13. The lower central tube 14 is externally fitted with a seat seal piston 15. The seat seal 12 is externally fitted with a sealing cylinder 10. The seat seal piston 15 is externally fitted with a lower outer cylinder 16. The lower rubber sleeve seat 9 and the sealing cylinder 10 are threadedly connected. The lower connector 17 and the lower outer cylinder 16 are threadedly connected.

[0024] The upper connector 1 and the fixed seat 2 are fixedly connected by the unsealing pin 18. The upper central tube 4 and the positioning seat 5 are fixed by the steel ball 19 to ensure that the packer will not be unsealed prematurely during operation. The sealing cylinder 10 and the seat sleeve 12 are fixedly connected by the seat sealing pin 20.

[0025] In this embodiment, the upper glue tube seat 7 is provided with a liquid outlet hole. This outlet hole opens during unsealing, providing pressure relief and accelerating the contraction of the glue tube 8. The lower glue tube seat 9 is provided with a liquid inlet hole, the connecting seat 11 is provided with a liquid inlet hole, and the lower central tube 14 is provided with a liquid inlet hole. During setting, the pressurized liquid sequentially enters below the setting piston 15 through the liquid inlet holes of the lower central tube 14, the connecting seat 11, and the lower glue tube seat 9, pushing the setting piston 15 upwards to achieve setting.

[0026] In this embodiment, the sealing fit between the components is as follows: the upper connector 1 and the unsealing seat 3, and the upper connector 1 and the upper central tube 4 are sealed by sealing elements; the fixed seat 2 and the unsealing seat 3, and the fixed seat 2 and the upper central tube 4 are sealed by sealing elements; the unsealing seat 3 and the upper central tube 4, and the unsealing seat 3 and the unsealing sleeve 6 are sealed by sealing elements; the upper central tube 4 and the upper glue tube seat 7, and the upper central tube 4 and the connecting seat 11 are sealed by sealing elements; the unsealing sleeve 6 and the upper glue tube seat 7 are sealed by sealing elements; the lower glue tube seat 9 and the sealing cylinder 10 are sealed by sealing elements; the sealing cylinder 10 and the seat sealing sleeve 12 are sealed by sealing elements; the connecting seat 11 and the seat sealing sleeve 12, and the connecting seat 11 and the lower central tube 14 are sealed by sealing elements; the seat sealing piston 15 and the lower central tube 14, and the seat sealing piston 15 and the lower outer cylinder 16 are sealed by sealing elements; the lower outer cylinder 16 and the lower connector 17 are sealed by sealing elements. The aforementioned sealing element is preferably an O-ring, which has good pressure resistance and temperature resistance.

[0027] Example 2

[0028] This embodiment further defines the locking structure of the steel ball 19 based on embodiment 1.

[0029] like Figure 2 As shown, the outer wall of the upper central tube 4 is provided with an annular groove. The positioning seat 5 is provided with a radial through hole, which is evenly divided into 8 to 12 parts on the circumference. In this embodiment, the radial through hole is preferably evenly divided into 10 parts on the circumference.

[0030] Half of the steel ball 19 is placed in the annular groove of the upper central tube 4, and the other half is placed in the radial through hole of the positioning seat 5. The unsealing seat 3 is sleeved on the outside of the positioning seat 5, and the inner wall of the unsealing seat 3 forms a radial limit on the outer edge of the steel ball 19, preventing the steel ball 19 from moving outward.

[0031] When the packer is in the seated sealing state, regardless of pressure fluctuations within the tube or packer creep, the inner wall of the release seat 3 always maintains radial restraint on the steel ball 19, preventing the steel ball 19 from dislodging from the annular groove. The upper central tube 4 and the positioning seat 5 maintain a stable locked state. This design solves the problem in existing locking mechanisms where the positioning seat easily opens prematurely and the steel ball leaks out when subjected to pressure fluctuations or packer creep.

[0032] When unsealing is required, the unsealing seat 3 moves upward relative to the positioning seat 5, and the radial limit of the steel ball 19 on the inner wall of the unsealing seat 3 is released. When the positioning seat 5 moves upward, the wall of its radial through hole drives the steel ball 19 to slide out of the annular groove, thereby unlocking the upper central tube 4 from the positioning seat 5.

[0033] Example 3

[0034] This embodiment describes a specific method for unsealing using the above-described step-by-step unsealing packer.

[0035] The unsealing process will be carried out in the following steps: A1: Lift the tubing string, causing the upper connector 1, unsealing seat 3, and unsealing sleeve 6 to move upwards.

[0036] A2: When the upward force reaches the shear force value of the unsealing pin 18, the unsealing pin 18 is sheared. In this embodiment, the shear force value of the unsealing pin 18 is preferably 8 to 12 kN.

[0037] A3: After the unsealing pin 18 is cut, the upper connector 1, unsealing seat 3, and unsealing sleeve 6 slide upward relative to the fixed seat 2.

[0038] A4: When the unsealing sleeve 6 moves upward to the lower end limit of the positioning seat 5, the liquid outlet of the upper glue tube seat 7 opens to release pressure, accelerating the contraction of the glue tube 8.

[0039] A5: When the unsealing seat 3 moves upward to the lower end face limit of the fixed seat 2, the radial limit of the inner wall of the unsealing seat 3 on the steel ball 19 is released.

[0040] A6: The upper connector 1, the unsealing seat 3, and the unsealing sleeve 6 continue to move upward and drive the positioning seat 5 and the upper rubber sleeve seat 7 to move upward. The radial through hole wall of the positioning seat 5 drives the steel ball 19 to slide upward along the groove on the outer wall of the upper central tube 4. The steel ball 19 comes out of the groove, and the upper central tube 4 is unlocked from the positioning seat 5.

[0041] A7: The upper rubber sleeve seat 7 continues to move upward and stretches the rubber sleeve 8, forcibly retracting and resetting the rubber sleeve 8. This forced stretching action effectively solves the problem that the rubber sleeve 8 cannot automatically retract due to long-term compression or obstruction by downhole impurities.

[0042] A8: Continue to lift the tubing string, and release each packer in sequence from top to bottom to complete the release operation.

[0043] In the above-described unsealing method, the combination of pressure relief from the liquid outlet and forced stretching of the packer provides double protection for packer reset, ensuring high unsealing reliability. Simultaneously, each packer is unsealed sequentially, avoiding the impact load and jamming risks associated with simultaneous unsealing.

[0044] Example 4

[0045] This embodiment describes the sealing process.

[0046] The sealing operation is performed according to the following steps: First, the packer is lowered to a predetermined position in the well. Then, pressure is applied to the tubing string, and fluid enters below the setting piston 15 through the inlet ports of the lower center tube 14, the connecting seat 11, and the lower rubber sleeve seat 9. Under hydraulic pressure, the setting piston 15 moves upward, pushing the setting sleeve 12 to compress the rubber sleeve 8. When the pressure reaches a preset value, the setting pin 20 is sheared, and the rubber sleeve 8 fully expands, completing the setting. After setting, the locking teeth 13 lock the position of the setting sleeve 12, and the setting sleeve 12 moves upward to the lower end face of the lower rubber sleeve seat 9. The setting sleeve 12 and the connecting seat 11 are completely sealed, closing the inlet port of the connecting seat 11. A sealed cavity is formed between the upper center tube 4 and the rubber sleeve 8, keeping the rubber sleeve 8 in an expanded state. In this embodiment, the shear force value of the setting pin 20 is preferably 15-20 kN.

[0047] Beneficial effects

[0048] The step-by-step desealing packer and its desealing method, employing the above technical solution, have achieved the following technical effects in practical applications: 1. In bench tests simulating downhole pressure fluctuations and tubing creep, the packer remained stably locked after being seated, and no premature unsealing occurred.

[0049] 2. During the unsealing test, the lifting unsealing operation was smooth, the pressure relief of the liquid outlet and the forced stretching of the rubber sleeve were well coordinated, the rubber sleeve reset rate reached 100%, and no well jamming problem occurred.

[0050] 3. In the multi-segment segmented unsealing test, each packer was unsealed in sequence from top to bottom, and the unsealing force value was stable with no abnormal impact.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A step-by-step desealing packer, comprising an upper connector (1), an upper central tube (4), a connecting seat (11), a lower central tube (14), and a lower connector (17), characterized in that: The upper connector (1) has a fixed seat (2) inside and a release seat (3) outside. The upper connector (1) and the release seat (3) are connected by threads. The release seat (3) is fitted onto the fixed seat (2) and the upper central tube (4). The upper central tube (4) is fitted with a positioning seat (5) and an upper glue tube seat (7). The positioning seat (5) and the upper glue tube seat (7) are connected by threads. The positioning seat (5) is fitted with a release seat (3) and a release sleeve (6). The release seat (3) and the release sleeve (6) are connected by threads. The fixed seat (2), the release seat (3), the upper central tube (4), the positioning seat (5), the release sleeve (6), and the upper glue tube seat (7) form a step-by-step release sealed cavity. It does not come into contact with well fluid, does not rust, and does not scale. The upper rubber sleeve seat (7) is connected to the rubber sleeve (8) and the lower rubber sleeve seat (9) by threads in sequence. The upper central tube (4) is connected to the lower rubber sleeve seat (9) and the connecting seat (11) by threads in sequence. The connecting seat (11) is connected to the lower central tube (14) and the lower connector (17) by threads in sequence. The connecting seat (11) is fitted with a seat seal sleeve (12) and a locking tooth (13) on the outside. The lower central tube (14) is fitted with a seat seal piston (15) on the outside. The seat seal sleeve (12) is fitted with a sealing cylinder (10) on the outside. The seat seal piston (15) is fitted with a lower outer cylinder (16) on the outside. The lower rubber sleeve seat (9) and the sealing cylinder (10) are connected by threads in sequence. The lower connector (17) is threaded to the lower outer cylinder (16). The upper connector (1) and the fixed seat (2) are fixedly connected by the unsealing pin (18). The upper central tube (4) and the positioning seat (5) are fixed by the steel ball (19) to ensure that the packer will not be unsealed prematurely during operation. The sealing cylinder (10) and the seat sleeve (12) are fixedly connected by the seat sealing pin (20). The outer wall of the upper central tube (4) is provided with an annular groove. The positioning seat (5) is provided with a radial through hole, which is divided into 8 to 12 parts on the circumference. Half of the steel ball (19) is placed in the annular groove of the upper central tube (4), and the other half is placed in the radial through hole of the positioning seat (5). The unsealing seat (3) is sleeved on the outside of the positioning seat (5). (3) The inner wall of the unsealing seat (3) forms a radial limit on the outer edge of the steel ball (19), preventing the steel ball (19) from moving outward. When the packer is in the seated working state, regardless of the pressure fluctuation inside the tube or the packer creeping action, the inner wall of the unsealing seat (3) always maintains a radial limit on the steel ball (19), and the steel ball (19) cannot be removed from the annular groove. The upper central tube (4) and the positioning seat (5) remain locked. When unsealing is required, the unsealing seat (3) moves upward relative to the positioning seat (5), and the radial limit of the inner wall of the unsealing seat (3) on the steel ball (19) is released. When the positioning seat (5) moves upward, the wall of its radial through hole drives the steel ball (19) to slide out of the annular groove, thereby unlocking the upper central tube (4) and the positioning seat (5).

2. The step-by-step desealing packer according to claim 1, characterized in that: The upper glue tube seat (7) is provided with a liquid outlet hole and has a pressure relief function when unsealed. The lower glue tube seat (9) is provided with a liquid inlet hole. The connecting seat (11) is provided with a liquid inlet hole. The lower central tube (14) is provided with a liquid inlet hole.

3. The step-by-step desealing packer according to claim 1, characterized in that: The upper connector (1) and the unsealing seat (3), and the upper connector (1) and the upper central tube (4) are sealed by sealing elements. The fixed seat (2) and the unsealing seat (3), and the fixed seat (2) and the upper central tube (4) are sealed by sealing elements. The unsealing seat (3) and the upper central tube (4), and the unsealing seat (3) and the unsealing sleeve (6) are sealed by sealing elements. The upper central tube (4) and the upper rubber sleeve seat (7), and the upper central tube (4) and the connecting seat (11) are sealed by sealing elements. The unsealing sleeve (6) The upper rubber sleeve seat (7) is sealed with a seal, the lower rubber sleeve seat (9) and the sealing cylinder (10) are sealed with a seal, the sealing cylinder (10) and the seat cover (12) are sealed with a seal, the connecting seat (11) and the seat cover (12) and the connecting seat (11) and the lower central tube (14) are sealed with seals respectively, the seat seal piston (15) and the lower central tube (14) and the seat seal piston (15) and the lower outer cylinder (16) are sealed with seals respectively, and the lower outer cylinder (16) and the lower connector (17) are sealed with a seal.

4. A packer unsealing method, employing the packer unsealing method as described in claim 1, characterized in that: The steps to lift the lockdown are as follows: A1: Lift the tubing string, causing the upper connector (1), unsealing seat (3), and unsealing sleeve (6) to move upwards; A2: When the lifting force reaches the shear force value of the unsealing pin (18), the unsealing pin (18) is sheared off; A3: The upper connector (1), the unsealing seat (3), and the unsealing sleeve (6) slide upward relative to the fixed seat (2); A4: The unsealing sleeve (6) moves up to the lower end of the positioning seat (5) and the liquid outlet of the upper rubber sleeve seat (7) opens to release pressure and accelerate the contraction of the rubber sleeve (8); A5: When the unsealing seat (3) moves up to the lower end face limit of the fixed seat (2), the radial limit of the inner wall of the unsealing seat (3) on the steel ball (19) is released; A6: The upper connector (1), the unsealing seat (3), and the unsealing sleeve (6) continue to move upward and drive the positioning seat (5) and the upper rubber sleeve seat (7) to move upward. The radial through hole wall of the positioning seat (5) drives the steel ball (19) to slide upward along the groove on the outer wall of the upper central tube (4). The steel ball (19) comes out of the groove, and the upper central tube (4) and the positioning seat (5) are unlocked. A7: The upper rubber tube seat (7) moves upward and stretches the rubber tube (8), causing the rubber tube (8) to be forcibly contracted and reset; A8: Continue to lift the tubing string, and release the packers of each layer in sequence.

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