Toe end sliding sleeve capable of being opened in delayed mode

Abstract

The invention discloses a delayed-opening toe-end sliding sleeve, which belongs to the technical field of underground tools in petroleum and natural gas industries and comprises an opening assembly, a delay part, a shell, a lower joint and an upper joint, one end of the shell is connected with the upper joint, the other end of the shell is connected with the lower joint, a movable sleeve and an inner sleeve are arranged in the shell, the delay part is arranged between the shell and the movable sleeve, and the lower joint is connected with the upper joint. The top of the time delay piece is connected with the movable sleeve and the inner sleeve, the bottom of the time delay piece makes sealing contact with the shell, the movable sleeve makes sealing contact with the upper connector, the inner sleeve makes sealing contact with the lower connector, the opening assembly comprises a first opening piece and a second opening piece, the first opening piece is arranged on the upper connector, and the second opening piece is arranged in a cavity defined by the upper connector, the movable sleeve and the shell. According to the toe end sliding sleeve, jamming caused by the safety shear pin in the opening process of the toe end sliding sleeve and blocking generated in the advancing process of the inner sleeve can be effectively avoided, it is ensured that the toe end sliding sleeve is smoothly opened, and the use reliability of the toe end sliding sleeve is improved.

Description

Technical Field

[0001] This invention relates to the field of downhole tools technology in the oil and gas industry, and in particular to a delayed-opening toe sleeve. Background Technology

[0002] Shale gas development primarily relies on hydraulic fracturing to obtain industrial gas flow. Currently, coiled tubing perforation and toe-sleeve fracturing are the main methods for fracturing the first stage of shale gas horizontal wells. Due to the extremely low permeability of shale gas reservoirs, shale gas production is closely related to the number of wells drilled and the scale of fracturing. With the continuous advancement of drilling technology, ultra-long horizontal sections, with horizontal wells exceeding 2500 meters, will be the development trend for efficient shale gas development. However, the coiled tubing perforation method faces the risk of incomplete perforation placement when dealing with deep, ultra-long horizontal wells, thus affecting the efficient development of shale gas.

[0003] The toe sleeve can be opened directly by surface pressure testing, resulting in high construction efficiency and no limitations on the length of the horizontal section or the well depth. Compared with coiled tubing perforation, the toe sleeve offers advantages such as high operational efficiency, low cost, low risk, and no limitations on operating depth.

[0004] As shale gas development gradually extends into deeper formations, reaching depths of up to 4500m, a full-bore pressure test of 120MPa is required before fracturing operations. In addition, with the hydraulic column pressure in the wellbore, the ultimate pressure of the tool placed at the bottom of the well can reach 165MPa. The existing toe-end sliding sleeve can no longer meet the needs of shale gas exploration and development in deeper formations.

[0005] Chinese patent document CN110541687A, published on December 6, 2019, discloses a controllable delayed-opening toe sleeve. The toe sleeve includes an opening mechanism, a delay mechanism, an adjustment mechanism, a fracturing port, and a housing, a movable piston, and an inner sleeve arranged coaxially. The inner sleeve is fixedly connected to the movable piston. The housing is fitted outside the movable piston and the inner sleeve, and forms a first cavity and a second cavity that communicate with the movable piston and / or the inner sleeve. The delay mechanism and the adjustment mechanism are disposed in the first cavity and are fixed relative to the movable piston and / or the inner sleeve, dividing the first cavity into a working cavity and a delay cavity. The working cavity and the second cavity are connected through a failure step surface and both are filled with hydraulic oil. The delay cavity is an empty cavity.

[0006] The patent document discloses a controllable delayed-opening toe sleeve that can be used for initial fracturing in oil and gas wells, solving the problems of strict opening pressure error range and uncontrollable opening time in existing technologies. However, the safety shear pins are prone to jamming, and the inner sleeve is prone to clogging, affecting the reliability of the toe sleeve. Summary of the Invention

[0007] In order to overcome the shortcomings of the prior art, the present invention provides a delayed-opening toe sleeve. The present invention can effectively avoid the jamming caused by the safety shear pin during the opening of the toe sleeve, as well as the blockage caused by the inner sleeve during the movement, ensuring the smooth opening of the toe sleeve and improving the reliability of the toe sleeve.

[0008] This invention is achieved through the following technical solution: A delayed-opening toe sleeve includes an opening assembly, a delay element, a housing, and a lower connector. It is characterized by further including an upper connector; one end of the housing is connected to the upper connector, and the other end of the housing is connected to the lower connector; a movable sleeve and an inner sleeve are disposed within the housing; the delay element is disposed between the housing and the movable sleeve; the top of the delay element is connected to both the movable sleeve and the inner sleeve; the bottom of the delay element is in sealing contact with the housing; the movable sleeve is in sealing contact with the upper connector; and the inner sleeve is in sealing contact with the lower connector. The opening assembly includes a first opening element and a second opening element; the first opening element is disposed on the upper connector, and the second opening element is disposed in the cavity formed by the upper connector, the movable sleeve, and the housing.

[0009] The first opening element includes a sealing plug, a control pin, and a control piston. The control piston and the control pin are disposed on the sealing plug, and the control piston is fixed inside the sealing plug by the control pin.

[0010] The second opening component includes a shear bearing ring, a safety shear pin, and a shear ring. The shear bearing ring is in contact with the housing, and the shear ring is disposed on the shear bearing ring. The shear ring is fixed to the movable sleeve by the safety shear pin.

[0011] The delay component includes a delay coupling and an overflow valve body, a hollow throttling valve body, a first filter, a second filter, and a tightening screw disposed within the delay coupling. The second filter is located between the first filter and the tightening screw. One end of the first filter is connected to the hollow throttling valve body, and the other end of the first filter is in contact with the second filter. The tightening screw is threadedly connected to the delay coupling and is in contact with the second filter.

[0012] The hollow throttling valve body is fixed with a screw at its end, and a damping rod assembly is installed inside the hollow throttling valve body. The damping rod assembly is located between the screw and the first filter.

[0013] The damping rod assembly includes multiple damping rods, with any two adjacent damping rods in contact.

[0014] The overflow valve body is provided with a spring adjusting screw, a spring washer, a spring and an overflow valve core. The spring adjusting screw is connected to the overflow valve body by a thread. The spring washer is set on the spring adjusting screw. One end of the spring contacts the spring washer and the other end of the spring contacts the overflow valve core.

[0015] The hollow throttling valve body includes a cylindrical section and a stepped section, which are integrally formed. The inner wall of the delay coupling has a concave stepped opening that matches the stepped section.

[0016] One end of the first filter extends into the stage and is connected to the stage by a thread.

[0017] The housing, movable sleeve, and time-delay coupling form an annular air cavity, which is located above the time-delay coupling. The inner sleeve, housing, time-delay coupling, and lower connector form an annular hydraulic oil cavity, which is located below the time-delay coupling.

[0018] The beneficial effects of this invention are mainly reflected in the following aspects: 1. In this invention, one end of the housing is connected to the upper connector, and the other end of the housing is connected to the lower connector. A movable sleeve and an inner sleeve are provided inside the housing. A delay element is provided between the housing and the movable sleeve. The top of the delay element is connected to the movable sleeve and the inner sleeve respectively, and the bottom of the delay element is in sealing contact with the housing. The movable sleeve is in sealing contact with the upper connector, and the inner sleeve is in sealing contact with the lower connector. The opening assembly includes a first opening element and a second opening element. The first opening element is provided on the upper connector, and the second opening element is provided in the cavity formed by the upper connector, the movable sleeve, and the housing. Compared with the prior art, this invention can effectively avoid the jamming caused by the safety shear pin during the opening of the toe slide sleeve, as well as the blockage caused by the inner sleeve during the movement, ensuring smooth opening of the toe slide sleeve and improving the reliability of the toe slide sleeve.

[0019] 2. In this invention, the first opening component includes a sealing plug, a control shear pin, and a control piston. The control piston and the control shear pin are disposed on the sealing plug. The control piston is fixed inside the sealing plug by the control shear pin. The control piston is specifically disposed on the upper connector. The debris generated during the activation process is less likely to cause the inner sleeve to move and become blocked, thus ensuring the working stability of the inner sleeve.

[0020] 3. In this invention, the second opening component includes a shear bearing ring, a safety shear pin, and a shear ring. The shear bearing ring contacts the housing, and the shear ring is disposed on the shear bearing ring. The shear ring is fixed to the movable sleeve by the safety shear pin. Compared to placing the safety shear pin on the outer shell of the toe sleeve body, which is easily blocked and solidified by cement slurry during cementing operations, placing the safety shear pin between the housing and the movable sleeve can effectively avoid contact with cement slurry and prevent blockage, thus ensuring a high success rate of opening.

[0021] 4. This invention can be smoothly opened after the entire wellbore has been successfully pressure tested before fracturing construction in a shale gas well, thus meeting the requirements for the first stage of fracturing construction in the casing completion of a deep shale gas well.

[0022] 5. Compared with Chinese patent document CN110541687A, published on December 6, 2019, this invention is easier to process and has lower assembly requirements, making it easier to industrialize.

[0023] 6. Compared with Chinese patent document CN110541687A published on December 6, 2019, this invention reduces the sliding contact surface when the inner sleeve and the outer shell move relative to each other, which is beneficial to improving the smoothness of the inner sleeve sliding.

[0024] 7. The present invention provides a hollow throttle valve body comprising a cylindrical section and a stepped section, which are integrally formed. The inner wall of the delay coupling has a concave stepped opening that matches the stepped section, further increasing the stepped sealing and improving the sealing effect, thus adapting to the sealing pressure caused by the increase in well depth. Attached Figure Description

[0025] The present invention will now be further described in detail with reference to the accompanying drawings and specific embodiments, wherein: Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the structure of the component that enables the present invention; Figure 3 This is a schematic diagram of the delay element of the present invention; Figure 4 for Figure 3 Enlarged view of point A in the middle; The markings in the diagram are: 1. Opening component, 2. Delay component, 3. Housing, 4. Lower connector, 5. Upper connector, 6. Movable sleeve, 7. Inner sleeve, 8. First opening component, 9. Second opening component, 10. Sealing plug, 11. Control shear pin, 12. Control piston, 13. Shear bearing ring, 14. Safety shear pin, 15. Shear ring, 16. Delay coupling, 17. Overflow valve body, 18. Hollow throttle valve body, 19. First filter, 20. Second filter, 21. Tightening screw, 22. Screw, 23. Damping rod assembly, 24. Damping rod, 25. Spring adjusting screw, 26. Spring washer, 27. Spring, 28. Overflow valve core, 29. Cylindrical section, 30. Stepped section, 31. Concave step opening, 32. Annular air cavity, 33. Annular hydraulic oil cavity. Detailed Implementation

[0026] Example 1 See Figures 1-4A delayed-opening toe sleeve includes an opening component 1, a delay element 2, a housing 3, a lower connector 4, and an upper connector 5. One end of the housing 3 is connected to the upper connector 5, and the other end of the housing 3 is connected to the lower connector 4. A movable sleeve 6 and an inner sleeve 7 are disposed inside the housing 3. The delay element 2 is disposed between the housing 3 and the movable sleeve 6. The top of the delay element 2 is connected to the movable sleeve 6 and the inner sleeve 7 respectively, and the bottom of the delay element 2 is in sealing contact with the housing 3. The movable sleeve 6 is in sealing contact with the upper connector 5, and the inner sleeve 7 is in sealing contact with the lower connector 4. The opening component 1 includes a first opening element 8 and a second opening element 9. The first opening element 8 is disposed on the upper connector 5, and the second opening element 9 is disposed in the cavity formed by the upper connector 5, the movable sleeve 6, and the housing 3.

[0027] This embodiment is the most basic implementation. One end of the housing 3 is connected to the upper connector 5, and the other end of the housing 3 is connected to the lower connector 4. The housing 3 is provided with a movable sleeve 6 and an inner sleeve 7. The delay element 2 is provided between the housing 3 and the movable sleeve 6. The top of the delay element 2 is connected to the movable sleeve 6 and the inner sleeve 7 respectively, and the bottom of the delay element 2 is in sealed contact with the housing 3. The movable sleeve 6 is in sealed contact with the upper connector 5, and the inner sleeve 7 is in sealed contact with the lower connector 4. The opening component 1 includes a first opening element 8 and a second opening element 9. The first opening element 8 is provided on the upper connector 5, and the second opening element 9 is provided in the cavity formed by the upper connector 5, the movable sleeve 6, and the housing 3. Compared with the prior art, it can effectively avoid the jamming caused by the safety shear pin 14 during the opening of the toe slide and the blockage generated by the inner sleeve 7 during the movement, ensuring the smooth opening of the toe slide and improving the reliability of the toe slide.

[0028] Example 2 See Figures 1-4 A delayed-opening toe sleeve includes an opening component 1, a delay element 2, a housing 3, a lower connector 4, and an upper connector 5. One end of the housing 3 is connected to the upper connector 5, and the other end of the housing 3 is connected to the lower connector 4. A movable sleeve 6 and an inner sleeve 7 are disposed inside the housing 3. The delay element 2 is disposed between the housing 3 and the movable sleeve 6. The top of the delay element 2 is connected to the movable sleeve 6 and the inner sleeve 7 respectively, and the bottom of the delay element 2 is in sealing contact with the housing 3. The movable sleeve 6 is in sealing contact with the upper connector 5, and the inner sleeve 7 is in sealing contact with the lower connector 4. The opening component 1 includes a first opening element 8 and a second opening element 9. The first opening element 8 is disposed on the upper connector 5, and the second opening element 9 is disposed in the cavity formed by the upper connector 5, the movable sleeve 6, and the housing 3.

[0029] The first opening member 8 includes a sealing plug 10, a control pin 11, and a control piston 12. The control piston 12 and the control pin 11 are disposed on the sealing plug 10, and the control piston 12 is fixed inside the sealing plug 10 by the control pin 11.

[0030] This embodiment is a preferred implementation. The first opening member 8 includes a sealing plug 10, a control shear pin 11, and a control piston 12. The control piston 12 and the control shear pin 11 are disposed on the sealing plug 10. The control piston 12 is fixed inside the sealing plug 10 by the control shear pin 11. The control piston 12 is specifically disposed on the upper connector 5. The debris generated during the activation process is less likely to cause the inner sleeve 7 to move and become blocked, thus ensuring the working stability of the inner sleeve 7.

[0031] Example 3 See Figures 1-4 A delayed-opening toe sleeve includes an opening component 1, a delay element 2, a housing 3, a lower connector 4, and an upper connector 5. One end of the housing 3 is connected to the upper connector 5, and the other end of the housing 3 is connected to the lower connector 4. A movable sleeve 6 and an inner sleeve 7 are disposed inside the housing 3. The delay element 2 is disposed between the housing 3 and the movable sleeve 6. The top of the delay element 2 is connected to the movable sleeve 6 and the inner sleeve 7 respectively, and the bottom of the delay element 2 is in sealing contact with the housing 3. The movable sleeve 6 is in sealing contact with the upper connector 5, and the inner sleeve 7 is in sealing contact with the lower connector 4. The opening component 1 includes a first opening element 8 and a second opening element 9. The first opening element 8 is disposed on the upper connector 5, and the second opening element 9 is disposed in the cavity formed by the upper connector 5, the movable sleeve 6, and the housing 3.

[0032] The first opening member 8 includes a sealing plug 10, a control pin 11, and a control piston 12. The control piston 12 and the control pin 11 are disposed on the sealing plug 10, and the control piston 12 is fixed inside the sealing plug 10 by the control pin 11.

[0033] The second opening member 9 includes a shear bearing ring 13, a safety shear pin 14, and a shear ring 15. The shear bearing ring 13 is in contact with the housing 3, and the shear ring 15 is disposed on the shear bearing ring 13. The shear ring 15 is fixed to the movable sleeve 6 by the safety shear pin 14.

[0034] This embodiment is another preferred implementation. The second opening component 9 includes a shear bearing ring 13, a safety shear pin 14, and a shear ring 15. The shear bearing ring 13 contacts the housing 3, and the shear ring 15 is disposed on the shear bearing ring 13. The shear ring 15 is fixed to the movable sleeve 6 by the safety shear pin 14. Compared with placing the safety shear pin 14 on the outer shell of the toe sleeve body, which is easily blocked and solidified by cement slurry during cementing operations, placing the safety shear pin 14 between the housing 3 and the movable sleeve 6 can effectively avoid contact with cement slurry and prevent blockage, thus ensuring a high success rate of opening.

[0035] Example 4 See Figures 1-4A delayed-opening toe sleeve includes an opening component 1, a delay element 2, a housing 3, a lower connector 4, and an upper connector 5. One end of the housing 3 is connected to the upper connector 5, and the other end of the housing 3 is connected to the lower connector 4. A movable sleeve 6 and an inner sleeve 7 are disposed inside the housing 3. The delay element 2 is disposed between the housing 3 and the movable sleeve 6. The top of the delay element 2 is connected to the movable sleeve 6 and the inner sleeve 7 respectively, and the bottom of the delay element 2 is in sealing contact with the housing 3. The movable sleeve 6 is in sealing contact with the upper connector 5, and the inner sleeve 7 is in sealing contact with the lower connector 4. The opening component 1 includes a first opening element 8 and a second opening element 9. The first opening element 8 is disposed on the upper connector 5, and the second opening element 9 is disposed in the cavity formed by the upper connector 5, the movable sleeve 6, and the housing 3.

[0036] The first opening member 8 includes a sealing plug 10, a control pin 11, and a control piston 12. The control piston 12 and the control pin 11 are disposed on the sealing plug 10, and the control piston 12 is fixed inside the sealing plug 10 by the control pin 11.

[0037] The second opening member 9 includes a shear bearing ring 13, a safety shear pin 14, and a shear ring 15. The shear bearing ring 13 is in contact with the housing 3, and the shear ring 15 is disposed on the shear bearing ring 13. The shear ring 15 is fixed to the movable sleeve 6 by the safety shear pin 14.

[0038] The delay component 2 includes a delay coupling 16 and an overflow valve body 17, a hollow throttling valve body 18, a first filter 19, a second filter 20, and a tightening screw 21 disposed within the delay coupling 16. The second filter 20 is located between the first filter 19 and the tightening screw 21. One end of the first filter 19 is connected to the hollow throttling valve body 18, and the other end of the first filter 19 is in contact with the second filter 20. The tightening screw 21 is threadedly connected to the delay coupling 16 and is in contact with the second filter 20.

[0039] The hollow throttling valve body 18 is fixed with a screw 22 at its end. The hollow throttling valve body 18 contains a damping rod assembly 23, which is located between the screw 22 and the first filter 19.

[0040] This embodiment is another preferred implementation method. After the full wellbore pressure test is successful before the fracturing operation of the shale gas well, it can be opened smoothly, meeting the requirements of the first stage of fracturing operation for casing completion of deep shale gas wells.

[0041] Example 5 See Figures 1-4A delayed-opening toe sleeve includes an opening component 1, a delay element 2, a housing 3, a lower connector 4, and an upper connector 5. One end of the housing 3 is connected to the upper connector 5, and the other end of the housing 3 is connected to the lower connector 4. A movable sleeve 6 and an inner sleeve 7 are disposed inside the housing 3. The delay element 2 is disposed between the housing 3 and the movable sleeve 6. The top of the delay element 2 is connected to the movable sleeve 6 and the inner sleeve 7 respectively, and the bottom of the delay element 2 is in sealing contact with the housing 3. The movable sleeve 6 is in sealing contact with the upper connector 5, and the inner sleeve 7 is in sealing contact with the lower connector 4. The opening component 1 includes a first opening element 8 and a second opening element 9. The first opening element 8 is disposed on the upper connector 5, and the second opening element 9 is disposed in the cavity formed by the upper connector 5, the movable sleeve 6, and the housing 3.

[0042] The first opening member 8 includes a sealing plug 10, a control pin 11, and a control piston 12. The control piston 12 and the control pin 11 are disposed on the sealing plug 10, and the control piston 12 is fixed inside the sealing plug 10 by the control pin 11.

[0043] The second opening member 9 includes a shear bearing ring 13, a safety shear pin 14, and a shear ring 15. The shear bearing ring 13 is in contact with the housing 3, and the shear ring 15 is disposed on the shear bearing ring 13. The shear ring 15 is fixed to the movable sleeve 6 by the safety shear pin 14.

[0044] The delay component 2 includes a delay coupling 16 and an overflow valve body 17, a hollow throttling valve body 18, a first filter 19, a second filter 20, and a tightening screw 21 disposed within the delay coupling 16. The second filter 20 is located between the first filter 19 and the tightening screw 21. One end of the first filter 19 is connected to the hollow throttling valve body 18, and the other end of the first filter 19 is in contact with the second filter 20. The tightening screw 21 is threadedly connected to the delay coupling 16 and is in contact with the second filter 20.

[0045] The hollow throttling valve body 18 is fixed with a screw 22 at its end. The hollow throttling valve body 18 contains a damping rod assembly 23, which is located between the screw 22 and the first filter 19.

[0046] The damping rod assembly 23 includes a plurality of damping rods 24, and any two adjacent damping rods 24 are in contact.

[0047] The overflow valve body 17 is provided with a spring adjusting screw 25, a spring washer 26, a spring 27 and an overflow valve core 28. The spring adjusting screw 25 is connected to the overflow valve body 17 by a thread. The spring washer 26 is set on the spring adjusting screw 25. One end of the spring 27 is in contact with the spring washer 26 and the other end of the spring 27 is in contact with the overflow valve core 28.

[0048] This embodiment is another preferred implementation. Compared with Chinese patent document CN110541687A, published on December 6, 2019, it is easier to process and has lower assembly requirements, making it easier to industrialize. Compared with Chinese patent document CN110541687A, published on December 6, 2019, when the inner sleeve 7 and the shell 3 move relative to each other, the sliding contact surface is reduced, which helps to improve the smoothness of the sliding of the inner sleeve 7.

[0049] Example 6 See Figures 1-4 A delayed-opening toe sleeve includes an opening component 1, a delay element 2, a housing 3, a lower connector 4, and an upper connector 5. One end of the housing 3 is connected to the upper connector 5, and the other end of the housing 3 is connected to the lower connector 4. A movable sleeve 6 and an inner sleeve 7 are disposed inside the housing 3. The delay element 2 is disposed between the housing 3 and the movable sleeve 6. The top of the delay element 2 is connected to the movable sleeve 6 and the inner sleeve 7 respectively, and the bottom of the delay element 2 is in sealing contact with the housing 3. The movable sleeve 6 is in sealing contact with the upper connector 5, and the inner sleeve 7 is in sealing contact with the lower connector 4. The opening component 1 includes a first opening element 8 and a second opening element 9. The first opening element 8 is disposed on the upper connector 5, and the second opening element 9 is disposed in the cavity formed by the upper connector 5, the movable sleeve 6, and the housing 3.

[0050] The first opening member 8 includes a sealing plug 10, a control pin 11, and a control piston 12. The control piston 12 and the control pin 11 are disposed on the sealing plug 10, and the control piston 12 is fixed inside the sealing plug 10 by the control pin 11.

[0051] The second opening member 9 includes a shear bearing ring 13, a safety shear pin 14, and a shear ring 15. The shear bearing ring 13 is in contact with the housing 3, and the shear ring 15 is disposed on the shear bearing ring 13. The shear ring 15 is fixed to the movable sleeve 6 by the safety shear pin 14.

[0052] The delay component 2 includes a delay coupling 16 and an overflow valve body 17, a hollow throttling valve body 18, a first filter 19, a second filter 20, and a tightening screw 21 disposed within the delay coupling 16. The second filter 20 is located between the first filter 19 and the tightening screw 21. One end of the first filter 19 is connected to the hollow throttling valve body 18, and the other end of the first filter 19 is in contact with the second filter 20. The tightening screw 21 is threadedly connected to the delay coupling 16 and is in contact with the second filter 20.

[0053] The hollow throttling valve body 18 is fixed with a screw 22 at its end. The hollow throttling valve body 18 contains a damping rod assembly 23, which is located between the screw 22 and the first filter 19.

[0054] The damping rod assembly 23 includes a plurality of damping rods 24, and any two adjacent damping rods 24 are in contact.

[0055] The overflow valve body 17 is provided with a spring adjusting screw 25, a spring washer 26, a spring 27 and an overflow valve core 28. The spring adjusting screw 25 is connected to the overflow valve body 17 by a thread. The spring washer 26 is set on the spring adjusting screw 25. One end of the spring 27 is in contact with the spring washer 26 and the other end of the spring 27 is in contact with the overflow valve core 28.

[0056] The hollow throttling valve body 18 includes a cylindrical section 29 and a stepped section 30, which are integrally formed. The inner wall of the delay coupling 16 has a concave stepped opening 31 that matches the stepped section 30.

[0057] One end of the first filter 19 extends into the stage 30 and is connected to the stage 30 by a thread.

[0058] The housing 3, movable sleeve 6, and time-delay coupling 16 form an annular air cavity 32, which is located above the time-delay coupling 16. The inner sleeve 7, housing 3, time-delay coupling 16, and lower connector 4 form an annular hydraulic oil cavity 33, which is located below the time-delay coupling 16.

[0059] This embodiment is the best implementation method. The hollow throttle valve body 18 includes a cylindrical section 29 and a stepped section 30. The cylindrical section 29 and the stepped section 30 are integrally formed. The inner wall of the delay coupling 16 has a concave stepped opening 31 that matches the stepped section 30, which further increases the stepped sealing and improves the sealing effect, and can adapt to the sealing pressure brought about by the increase in well depth.

[0060] The working process of this invention is as follows: When reservoir stimulation is required, the tubing string is first subjected to an integrity pressure test. When the pressure exceeds the threshold, the control piston 12 is pushed outward, allowing fluid in the wellbore to enter the gap between the upper connector 5, the shell 3, and the movable sleeve 6, generating thrust that pushes the movable sleeve 6 downward. When the thrust increases to the threshold of the safety shear pin 14, the safety shear pin 14 is sheared, causing the movable sleeve 6 to move downward.

[0061] The annular hydraulic oil cavity 33, formed by the inner sleeve 7, the housing 3, the time-delay coupling 16, and the lower connector 4, is filled with hydraulic oil. As the movable sleeve 6 is pushed downward by the thrust, it compresses the annular hydraulic oil cavity 33. At the same time, due to the presence of the time-delay coupling 16, the hydraulic oil will pass through the tightening screw 21, the second filter 20, the first filter 19, the hollow throttle valve body 18, and the screw 22 placed inside the time-delay coupling 16 in sequence, and enter the overflow valve core 28. When the pressure continues to increase, the thrust causes the spring 27 to contract, opening the flow passage and allowing the hydraulic oil to enter the annular air cavity 32 formed by the housing 3, the movable sleeve 6, and the time-delay coupling 16.

[0062] As the movable sleeve 6 drives the inner sleeve 7 downward, hydraulic oil flows from the annular hydraulic oil chamber 33 through the hollow throttle valve body 18 and the overflow valve body 17 into the annular air chamber 32. The duration of this movement can be adjusted in two ways: First, by adjusting the clearance between the damping rod 24 and the hollow throttle valve body 18; a larger clearance results in a shorter hydraulic oil passage time, while a smaller clearance results in a longer passage time. Second, by adjusting the viscosity of the hydraulic oil; a lower viscosity results in a shorter passage time, while a higher viscosity results in a longer passage time.

[0063] After all the hydraulic oil enters the annular air cavity 32 through the delay coupling 16, the movable sleeve 6 and the inner sleeve 7 also move to the lower step, exposing the waist hole of the outer shell, thus connecting the inside and outside and establishing a flow channel. If leakage occurs during the wellbore pressure test during the opening of the toe sleeve, it is only necessary to release the test pressure inside the wellbore. At this time, the spring 27 inside the overflow valve body 17 rebounds, closing the hydraulic oil flow channel, and the toe sleeve can stop moving.

Claims

1. A delayed-opening toe sleeve, comprising an opening assembly (1), a delay element (2), a housing (3), and a lower connector (4), characterized in that: It also includes an upper connector (5), one end of the housing (3) is connected to the upper connector (5), and the other end of the housing (3) is connected to the lower connector (4). The housing (3) is provided with a movable sleeve (6) and an inner sleeve (7). The delay element (2) is provided between the housing (3) and the movable sleeve (6). The top of the delay element (2) is connected to the movable sleeve (6) and the inner sleeve (7) respectively. The bottom of the delay element (2) is in sealed contact with the housing (3). The movable sleeve (6) is in sealed contact with the upper connector (5), and the inner sleeve (7) is in sealed contact with the lower connector (4). The opening component (1) includes a first opening element (8) and a second opening element (9). The first opening element (8) is provided on the upper connector (5), and the second opening element (9) is provided in the cavity formed by the upper connector (5), the movable sleeve (6), and the housing (3).

2. The delayed-opening toe sleeve according to claim 1, characterized in that: The first opening member (8) includes a sealing plug (10), a control pin (11) and a control piston (12). The control piston (12) and the control pin (11) are disposed on the sealing plug (10), and the control piston (12) is fixed inside the sealing plug (10) by the control pin (11).

3. The delayed-opening toe sleeve according to claim 1, characterized in that: The second opening member (9) includes a shear bearing ring (13), a safety shear pin (14) and a shear ring (15). The shear bearing ring (13) is in contact with the housing (3), and the shear ring (15) is disposed on the shear bearing ring (13). The shear ring (15) is fixed to the movable sleeve (6) by the safety shear pin (14).

4. The delayed-opening toe sleeve according to claim 1, characterized in that: The delay component (2) includes a delay coupling (16) and an overflow valve body (17), a hollow throttling valve body (18), a first filter (19), a second filter (20), and a tightening screw (21) disposed in the delay coupling (16). The second filter (20) is located between the first filter (19) and the tightening screw (21). One end of the first filter (19) is connected to the hollow throttling valve body (18), and the other end of the first filter (19) is in contact with the second filter (20). The tightening screw (21) is threadedly connected to the delay coupling (16) and is in contact with the second filter (20).

5. A delayed-opening toe sleeve according to claim 4, characterized in that: The hollow throttle valve body (18) is fixed with a screw (22) at its end. The hollow throttle valve body (18) contains a damping rod assembly (23), which is located between the screw (22) and the first filter (19).

6. The delayed-opening toe sleeve according to claim 5, characterized in that: The damping rod assembly (23) includes a plurality of damping rods (24), with any two adjacent damping rods (24) in contact.

7. The delayed-opening toe sleeve according to claim 4, characterized in that: The overflow valve body (17) is provided with a spring adjusting screw (25), a spring washer (26), a spring (27) and an overflow valve core (28). The spring adjusting screw (25) is connected to the overflow valve body (17) by a thread. The spring washer (26) is set on the spring adjusting screw (25). One end of the spring (27) is in contact with the spring washer (26), and the other end of the spring (27) is in contact with the overflow valve core (28).

8. The delayed-opening toe sleeve according to claim 4, characterized in that: The hollow throttle valve body (18) includes a cylindrical section (29) and a platform stage (30), which are integrally formed. The inner wall of the delay coupling (16) has a concave step opening (31) that matches the platform stage (30).

9. A delayed-opening toe sleeve according to claim 8, characterized in that: One end of the first filter (19) extends into the stage (30) and is connected to the stage (30) by a thread.

10. A delayed-opening toe sleeve according to claim 4, characterized in that: The housing (3), movable sleeve (6) and time-delay coupling (16) form an annular air cavity (32), which is located above the time-delay coupling (16). The inner sleeve (7), housing (3), time-delay coupling (16) and lower connector (4) form an annular hydraulic oil cavity (33), which is located below the time-delay coupling (16).

Images