A time-delayed toe slip sleeve

Abstract

The application belongs to the technical field of oil and gas well completion, and particularly relates to a delay toe sleeve. The delay toe sleeve comprises an outer cylinder, a circulation hole arranged on the cylinder wall of the outer cylinder, and an inner working cylinder for closing the circulation hole, the inner working cylinder is arranged in the inner part of the outer cylinder, and the inner working cylinder can move in response to the inner cavity pressure of the outer cylinder, so as to open the circulation hole, wherein an upper pressure receiving end and a lower pressure receiving end are respectively arranged at the axial two ends of the inner working cylinder, the pressure receiving area of the upper pressure receiving end is greater than that of the lower pressure receiving end, so that the inner working cylinder can move in response to the pressure, a pressure cavity is arranged in the outer cylinder, a delay mechanism for connecting the pressure cavity and the inner cavity of the outer cylinder is arranged on the outer cylinder, the upper pressure receiving end is located in the pressure cavity, and the pressure in the inner cavity of the outer cylinder cannot be transmitted to the upper pressure receiving end before the delay mechanism is opened. The application has the function of delay opening.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas well completion technology, specifically, it relates to a delayed toe sleeve. Background Technology

[0002] The toe sleeve is a commonly used downhole tool in staged fracturing. The first-stage fracturing toe sleeve is the first-stage sleeve in the cementing sleeve staged fracturing process. It is inserted into the well along with the casing to the predetermined position and cemented. During fracturing, the toe sleeve can be opened simply by pressurizing the wellhead, forming the first stage of fracturing channel. Compared with coiled tubing perforation, this method is more efficient and has lower operational risks and costs.

[0003] As development progresses, unconventional gas reservoirs are buried deeper and the length of horizontal sections is increasing. On-site construction requires a pressure integrity test of the entire wellbore casing before opening and establishing a flow channel to the target formation to ensure the smooth implementation of subsequent operations. During the pressure integrity test, a certain pressure needs to be pumped into the entire wellbore. During this process, the toe sleeve must be in a closed state. However, conventional toe sleeves open directly under pressure differential, which cannot meet this requirement. Therefore, it is necessary to develop a toe sleeve with a delayed opening function. Summary of the Invention

[0004] To address the technical problems described above, the present invention aims to provide a delayed toe sleeve with a delayed opening function.

[0005] According to the present invention, a delayed toe sleeve is provided, comprising:

[0006] The outer cylinder has circulation holes on its wall.

[0007] and an inner working cylinder for closing the circulation hole, the inner working cylinder being disposed inside the outer cylinder, the inner working cylinder being movable in response to the internal pressure of the outer cylinder, thereby opening the circulation hole, wherein,

[0008] An upper pressure-bearing end and a lower pressure-bearing end are respectively provided at both ends of the inner working cylinder along its axial direction. The pressure-bearing area of ​​the upper pressure-bearing end is larger than that of the lower pressure-bearing end, thereby enabling the inner working cylinder to move in response to pressure.

[0009] A pressure chamber is provided inside the outer cylinder, and a delay mechanism is provided on the outer cylinder to connect the pressure chamber with the inner cavity of the outer cylinder. The upper pressure-receiving end is located inside the pressure chamber. Before the delay mechanism is activated, the pressure in the inner cavity of the outer cylinder cannot be transmitted to the upper pressure-receiving end.

[0010] In a preferred embodiment of the present invention, the delay mechanism includes a liquid flow channel disposed on the outer cylinder, the liquid flow channel connecting the pressure chamber to the inner cavity of the outer cylinder, and a delay element is enclosed within the liquid flow channel, the delay element being made of a soluble material.

[0011] In a preferred embodiment of the present invention, a shear pin is provided between the inner working cylinder and the outer cylinder.

[0012] In a preferred embodiment of the present invention, the outer cylinder includes an upper connector and an outer working cylinder that are coaxially fixedly connected, and the pressure chamber is formed between the upper connector, the outer working cylinder and the inner working cylinder.

[0013] In a preferred embodiment of the present invention, the outer working cylinder is sleeved outside the upper connector, and the pressure chamber is disposed between the lower outer wall of the upper connector and the inner wall of the outer working cylinder.

[0014] In a preferred embodiment of the present invention, the upper connector includes a threaded portion, a sealing portion, and a cavity portion connected sequentially from top to bottom with decreasing outer diameters. The top of the outer working cylinder is fixedly connected to the threaded portion by a threaded connection. A sealing element is provided between the outer working cylinder and the sealing portion. The outer diameter of the cavity portion is smaller than the inner diameter of the outer working cylinder, thereby forming the pressure cavity between the cavity portion and the outer working cylinder.

[0015] In a preferred embodiment of the present invention, the inner working cylinder includes a first pipe section and a second pipe section, the outer diameters of the first pipe section and the second pipe section are equal, the inner diameter of the first pipe section is greater than the inner diameter of the second pipe section, and the first pipe section is located between the cavity portion and the outer working cylinder.

[0016] In a preferred embodiment provided by the present invention, the upper end of the second pipe segment abuts against the upper connector.

[0017] In a preferred embodiment provided by the present invention, the outer cylinder further includes a lower connector disposed at the lower end of the outer working cylinder.

[0018] In a preferred embodiment of the present invention, the lower connector includes a connecting part and an abutting part that are coaxially fixedly connected. The connecting part is provided on the outer side of the lower end of the outer working cylinder by means of a threaded connection, and the inner diameter of the abutting part is smaller than the outer diameter of the inner working cylinder.

[0019] Compared with the prior art, the advantages of this application are as follows.

[0020] After the toe sleeve is inserted into the well along with the tubing string, a rated pressure test of the tubing string is required. In existing technology, the toe sleeve is fixed to the inner and outer working cylinders solely by shear pins. Once the inner working cylinder is subjected to pressure, it shears off the shear pins and moves downwards, thus opening the circulation port. However, during the rated pressure test, the toe sleeve must remain closed. Therefore, in existing technology, the shear pins of the toe sleeve are designed with high strength to meet the rated pressure test conditions. This is to prevent the inner working cylinder from moving relative to the circulation port during installation and to prevent movement relative to the circulation port during the rated pressure test. During the rated pressure test, the design requires that the shear pins not break. Therefore, the part of the inner working cylinder connected to the shear pins is prone to deformation, increasing the friction between the inner and outer working cylinders and preventing the inner working cylinder from moving smoothly.

[0021] In this invention, the upper pressure-bearing end of the inner working cylinder is protected by a pressure chamber. Before the delay mechanism is activated, the upper pressure-bearing surface of the inner working cylinder is not affected by the pressure of the inner cavity of the outer cylinder. Therefore, the inner working cylinder will not generate a downward force. In this case, a shear pin may not be provided between the inner and outer working cylinders, or even if a shear pin is provided between the inner and outer working cylinders, the strength of the shear pin can be designed to be very small, only enough to prevent the inner working cylinder from moving downward under gravity during the process of the toe end sliding sleeve entering the well.

[0022] This invention, through a delay mechanism installed on the outer cylinder, can, on the one hand, meet the rated pressure test of the tubing in the fracturing process, and on the other hand, avoid the inner working cylinder from deforming during the shearing process due to excessively high design strength of the shear pin, thereby avoiding the situation where the frictional resistance of the inner working cylinder is too great and the toe sleeve cannot be opened. Attached Figure Description

[0023] The present invention will now be described with reference to the accompanying drawings.

[0024] Figure 1 A schematic diagram of one embodiment of the delayed toe sleeve according to the present invention is shown;

[0025] Figure 2 A schematic diagram of another embodiment of the delayed toe sleeve according to the present invention is shown;

[0026] Figure 3 Showing Figure 2 A schematic diagram of the delay mechanism 3 in the diagram.

[0027] In the diagram: 1. Outer cylinder; 11. Circulation hole; 12. Pressure chamber; 13. Upper connector; 131. Threaded part; 132. Sealing part; 133. Cavity part; 14. Outer working cylinder; 15. Lower connector; 151. Connecting part; 152. Abutting part;

[0028] 2. Inner working cylinder; 21. Upper pressure end; 211. First upper pressure surface; 212. Second upper pressure surface; 22. Lower pressure end; 23. First pipe section; 24. Second pipe section;

[0029] 3. Delay mechanism; 31. Fixed ring; 32. Rupture disc; 33. Liquid flow channel; 34. Delay component;

[0030] 4. Cut the pin;

[0031] 51. First protrusion; 52. First groove; 53. Second protrusion; 54. Second groove;

[0032] 100. Delayed toe slip sleeve.

[0033] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. Detailed Implementation

[0034] The invention will now be described with reference to the accompanying drawings.

[0035] It should be noted that in this application, the direction near the wellhead after the delayed toe sleeve 100 according to the present invention is inserted into the well is described as "up" or a similar term, while the direction away from the wellhead is described as "down" or a similar term.

[0036] Figure 1 The structure of the delayed toe sleeve 100 according to the present invention is shown. Figure 1 As shown, the delayed toe sleeve 100 includes at least an outer cylinder 1 and an inner working cylinder 2.

[0037] In this embodiment, a circulation hole 11 is provided on the wall of the outer cylinder 1. The number of circulation holes 11 is at least one. In this embodiment, multiple circulation holes 11 are evenly distributed on the wall of the outer cylinder 1 along the circumferential direction of the outer cylinder 1, thereby connecting the inner cavity of the outer cylinder 1 with the outside of the outer cylinder 1.

[0038] The inner working cylinder 2 is used to close the circulation hole 11 in the initial state and to open the circulation hole 11 when the cylinder is lowered in the fracturing state.

[0039] Figure 1The diagram shows the initial state of the delay toe sleeve 100. At this state, the inner working cylinder 2 is coaxially fitted inside the outer cylinder 1, and the circulation hole 11 is located within the length of the inner working cylinder 2. Sealing elements are provided on both the upper and lower sides of the circulation hole 11 between the outer wall of the inner working cylinder 2 and the inner wall of the outer cylinder 1. This arrangement allows the inner working cylinder 2 to close the circulation hole 11 in the initial state.

[0040] Under fracturing conditions, the pressure inside the outer cylinder 1 is increased by pressurizing the wellhead. The inner working cylinder 2 can move in response to the pressure inside the outer cylinder 1, thereby opening the circulation hole 11.

[0041] Specifically, an upper pressure-bearing end 21 and a lower pressure-bearing end 22 are respectively provided at both axial ends of the inner working cylinder 2, with the pressure-bearing area of ​​the upper pressure-bearing end 21 being larger than that of the lower pressure-bearing end 22. Under fracturing conditions, if both the upper pressure-bearing end 21 and the lower pressure-bearing end 22 of the inner working cylinder 2 are simultaneously subjected to the internal pressure of the outer cylinder 1, the pressure on the upper pressure-bearing end 21, due to its larger area, is greater than that on the lower pressure-bearing end 22, thus enabling the inner working cylinder 2 to move in response to the pressure. Finally, after the inner working cylinder 2 moves downward, the seal on the circulation hole 11 is released, allowing fracturing operations to commence.

[0042] According to the present invention, a pressure chamber 12 is provided inside the outer cylinder 1, and a delay mechanism 3 is provided on the outer cylinder 1 to connect the pressure chamber 12 with the inner cavity of the outer cylinder 1. The upper pressure end 21 is located inside the pressure chamber 12. Before the delay mechanism 3 bursts, the pressure in the inner cavity of the outer cylinder 1 cannot be transmitted to the upper pressure end 21.

[0043] Under this configuration, during the rated pressure test after the delayed toe sleeve 100 of the present invention is inserted into the well and before fracturing, as long as the delayed mechanism 3 is not opened, the inner working cylinder 2 will not move in response to the internal pressure of the outer cylinder 1. Therefore, there is no situation where the inner working cylinder 2 opens during the rated pressure test, and thus the inner working cylinder 2 will not be deformed due to squeezing with other parts.

[0044] In this case, shear pins 4 may not be provided between the inner working cylinder 2 and the outer cylinder 1, or only shear pins 4 with very low strength need to be provided, so as to prevent the inner working cylinder 2 from deforming due to the excessive strength of shear pins 4 during the shearing process after the delay mechanism 3 is opened.

[0045] In a specific embodiment, such as Figure 1 As shown, the outer cylinder 1 includes an upper connector 13 and an outer working cylinder 14 that are coaxially fixedly connected, and a pressure chamber 12 is formed between the upper connector 13, the outer working cylinder 14 and the inner working cylinder 2.

[0046] Furthermore, the outer working cylinder 14 is sleeved on the outside of the upper connector 13, and the pressure chamber 12 is located between the lower outer wall of the upper connector 13 and the inner wall of the outer working cylinder 14.

[0047] Specifically, such as Figure 1 As shown, the upper connector 13 includes a threaded portion 131, a sealing portion 132, and a cavity portion 133 connected from top to bottom with decreasing outer diameters.

[0048] The outer working cylinder 14 is coaxially fixedly sleeved on the outside of the upper connector 13. The top of the outer working cylinder 14 is fixedly connected to the threaded part 131 by a threaded connection. A sealing element is provided between the outer working cylinder 14 and the sealing part 132. The outer diameter of the cavity part 133 is smaller than the inner diameter of the outer working cylinder 14, thereby forming a pressure chamber 12 between the cavity part 133 and the outer working cylinder 14. The delay mechanism 3 is provided on the cylinder wall of the cavity part 133.

[0049] Furthermore, the inner working cylinder 2 includes a first pipe section 23 and a second pipe section 24. The outer diameters of the first pipe section 23 and the second pipe section 24 are equal, and the inner diameter of the first pipe section 23 is larger than the inner diameter of the second pipe section 24. The first pipe section 23 is located between the cavity portion 133 and the outer working cylinder 14. That is, the inner diameter of the first pipe section 23 is larger than the outer diameter of the cavity portion 133, so that the first pipe section 23 can extend into the pressure chamber 12, and at least a portion of the upper pressure-receiving end 21 enters the pressure chamber 12.

[0050] Preferably, the delay mechanism 3 is located above the upper end face of the first pipe section 23. It is easy to understand that a seal is provided between the inner wall of the first pipe section 23 and the outside of the cavity portion 133, so that the pressure chamber 12 formed by the upper connector 13, the outer working cylinder 14 and the inner working cylinder 2 constitutes a closed space, preventing the inner cavity pressure of the outer cylinder 1 from entering the pressure chamber 12 and applying pressure to the upper pressure end 21 of the inner working cylinder 2 before the delay mechanism 3 is opened.

[0051] According to a specific embodiment of the present invention, one end of the inner working cylinder 2, which is provided with the upper pressure end 21, abuts axially with the outer cylinder 1. For example... Figure 1 As shown, the upper end face of the second pipe section 24 of the inner working cylinder 2 abuts against the lower end face of the cavity portion 133 of the upper connector 13. A shear pin 4 is provided between the inner working cylinder 2 and the outer cylinder 1.

[0052] According to the present invention, in this embodiment, the upper pressure-bearing end 21 includes a first upper pressure-bearing surface 211, which is the upper end surface of the first pipe segment 23. The upper pressure-bearing end 21 also includes a second upper pressure-bearing surface 212, which is the end surface of the second pipe segment 24 that abuts against the cavity portion 133. The lower pressure-bearing end 22 is the lower end surface of the second pipe segment 24. The area of ​​the end surface of the second pipe segment 24 that abuts against the cavity portion 133 is less than or equal to the area of ​​the lower end surface of the second pipe segment 24.

[0053] Under this setup, during the rated pressure test, after the pressure inside the outer cylinder 1 increases, the end face of the second pipe section 24 that abuts against the cavity portion 133 and the lower end face of the second pipe section 24 are simultaneously subjected to pressure. Since the upper end face of the second pipe section 24 of the inner working cylinder 2 abuts against the cavity portion 133 of the upper connector 13, the inner working cylinder 2 cannot move upward. Therefore, as long as the area of ​​the end face of the second pipe section 24 that abuts against the cavity portion 133 is less than or equal to the area of ​​the lower end face of the second pipe section 24, the inner working cylinder 2 will not move downward in response to the pressure inside the outer cylinder 1, and thus will not open the circulation hole 11.

[0054] In a preferred embodiment, the area of ​​the end face of the second pipe section 24 that abuts against the cavity portion 133 is equal to the area of ​​the lower end face of the second pipe section 24. With this arrangement, the pressure areas at the upper and lower ends of the inner working cylinder 2 are equal, preventing any upward or downward movement and further avoiding deformation caused by compression between the inner working cylinder 2 and other parts.

[0055] like Figure 1 and Figure 2 As shown, at least one delay mechanism 3 is disposed through the wall of the cavity portion 133 or the sealing portion 132, as long as the delay mechanism 3 is located below the seal between the sealing portion 132 and the outer working cylinder 14. In this embodiment, multiple delay mechanisms 3 are evenly distributed along the circumferential direction of the cavity portion 133.

[0056] Specifically, the delay mechanism 3 includes a liquid flow channel 33 and a delay element 34 enclosed within the liquid flow channel 33, the delay element 34 being made of a soluble material.

[0057] It is easy to understand that soluble materials are commonly used materials for downhole tools in oil and gas drilling. Their specific composition is not a key technical point of this invention and will not be repeated here.

[0058] After the delay element 34 is set in this invention, the delay element 34 will not dissolve immediately during the rated pressure test. Instead, it will dissolve after a certain period of time according to the setting requirements. The dissolution time of the delay element 34 is related to the composition of the specific soluble material used, etc., which will not be elaborated here.

[0059] Before the delay element 34 dissolves, the delay mechanism 3 is in a closed state, and the internal pressure of the outer cylinder 1 cannot be transmitted to the upper pressure end 21 of the inner working cylinder 2, thus preventing the inner working cylinder 2 from moving downward. This configuration allows the delay toe sleeve 100 of the present invention to remain closed during the rated pressure test. After a certain period, the delay element 34 dissolves, the delay mechanism 3 opens, and the internal pressure of the outer cylinder 1 is transmitted to the pressure chamber 12 through the liquid flow channel 33, and then to the upper pressure end 21 of the inner working cylinder 2, enabling the inner working cylinder 2 to move downward in response to the internal pressure of the outer cylinder 1, opening the circulation hole 11.

[0060] According to the present invention, in one specific embodiment, such as Figure 1 As shown, the outer cylinder 1 also includes a lower connector 15 disposed at the lower end of the outer working cylinder 14. The lower connector 15 includes a connecting part 151 and an abutting part 152 arranged coaxially from top to bottom. An internal thread is provided on the inner wall of the connecting part 151 for engaging with the external thread at the lower end of the outer working cylinder 14 to achieve a fixed connection. The inner diameter of the abutting part 152 is smaller than the inner diameter of the connecting part 151. When the inner working cylinder 2 moves downward to the opening of the circulation hole 11 in response to the internal pressure of the outer cylinder 1, the lower end of the inner working cylinder 2 abuts against the upper end of the abutting part 152, thereby preventing the inner working cylinder 2 from detaching from the outer cylinder 1.

[0061] According to the present invention, another embodiment is also provided. For example... Figure 2 and Figure 3 As shown, in this embodiment, the delay mechanism 3 includes a liquid flow channel 33, a fixing ring 31, and a rupture disc 32.

[0062] The fixed ring 31 is coaxially fixed and sealed within the fluid flow channel 33, and the rupture disc 32 is coaxially fixed and sealed within the fixed ring 31. The burst pressure of the rupture disc 32 is greater than the pressure during the rated pressure test. Under this setup, the rupture disc 32 will not burst during the rated pressure test, therefore the delay mechanism 3 will not activate. After the rated pressure test is completed, the pressure inside the outer cylinder 1 is increased by pressurizing the wellhead until the pressure inside the outer cylinder 1 reaches the design strength of the rupture disc 32. At this point, the rupture disc 32 bursts, making the axial direction of the fixed ring 31 unobstructed, i.e., the fluid flow channel 33 unobstructed, connecting the inner cavity of the outer cylinder 1 with the pressure chamber 12. The pressure inside the outer cylinder 1 can then be transmitted to the pressure chamber 12, thereby exerting pressure on the upper pressure end 21 of the inner working cylinder 2, pushing the inner working cylinder 2 downward and opening the circulation hole 11.

[0063] The remaining structure of this embodiment is the same as that of the above embodiments, and will not be described again here.

[0064] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0065] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0066] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0067] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A delayed toe slip sleeve, characterized in that, include: The outer cylinder (1) has a circulation hole (11) on its wall. and an inner working cylinder (2) for closing the circulation hole (11), the inner working cylinder (2) being disposed inside the outer cylinder (1), the inner working cylinder (2) being movable in response to the internal pressure of the outer cylinder (1), thereby opening the circulation hole (11), wherein, An upper pressure-bearing end (21) and a lower pressure-bearing end (22) are respectively provided at both axial ends of the inner working cylinder (2). The pressure-bearing area of ​​the upper pressure-bearing end (21) is larger than that of the lower pressure-bearing end (22), thereby enabling the inner working cylinder (2) to move in response to pressure. A pressure chamber (12) is provided inside the outer cylinder (1). A delay mechanism (3) is provided on the outer cylinder (1) to connect the pressure chamber (12) with the inner cavity of the outer cylinder (1). The delay mechanism (3) includes a liquid flow channel (33) provided on the outer cylinder (1). The liquid flow channel (33) connects the pressure chamber (12) with the inner cavity of the outer cylinder (1). A delay element (34) is enclosed in the liquid flow channel (33). The delay element (34) is made of a soluble material. The opening time of the delay mechanism is controlled by the dissolution time of the delay element. The upper pressure end (21) is located in the pressure chamber (12). Before the delay mechanism (3) is opened, the pressure in the inner cavity of the outer cylinder (1) cannot be transmitted to the upper pressure end (21).

2. The delayed toe sleeve according to claim 1, characterized in that, A shear pin (4) is provided between the inner working cylinder (2) and the outer cylinder (1).

3. The delayed toe sleeve according to any one of claims 1 to 2, characterized in that, The outer cylinder (1) includes an upper connector (13) and an outer working cylinder (14) that are coaxially fixedly connected, and the pressure chamber (12) is formed between the upper connector (13), the outer working cylinder (14) and the inner working cylinder (2).

4. The delayed toe sleeve according to claim 3, characterized in that, The outer working cylinder (14) is sleeved on the outside of the upper connector (13), and the pressure chamber (12) is located between the lower outer wall of the upper connector (13) and the inner wall of the outer working cylinder (14).

5. The delayed toe sleeve according to claim 4, characterized in that, The upper connector (13) includes a threaded part (131), a sealing part (132), and a cavity part (133) connected from top to bottom with decreasing outer diameters. The top of the outer working cylinder (14) is fixedly connected to the threaded part (131) by a threaded connection. A sealing element is provided between the outer working cylinder (14) and the sealing part (132). The outer diameter of the cavity part (133) is smaller than the inner diameter of the outer working cylinder (14), thereby forming the pressure cavity (12) between the cavity part (133) and the outer working cylinder (14).

6. The delayed toe sleeve according to claim 5, characterized in that, The inner working cylinder (2) includes a first pipe section (23) and a second pipe section (24). The outer diameters of the first pipe section (23) and the second pipe section (24) are equal. The inner diameter of the first pipe section (23) is greater than the inner diameter of the second pipe section (24). The first pipe section (23) is located between the cavity part (133) and the outer working cylinder (14).

7. The delayed toe sleeve according to claim 6, characterized in that, The upper end of the second pipe section (24) abuts against the upper connector (13).

8. The delayed toe sleeve according to claim 3, characterized in that, The outer cylinder (1) also includes a lower connector (15) disposed at the lower end of the outer working cylinder (14).

9. The delayed toe sleeve according to claim 8, characterized in that, The lower connector (15) includes a connecting part (151) and an abutting part (152) that are coaxially fixedly connected. The connecting part (151) is provided on the outer side of the lower end of the outer working cylinder (14) by means of a threaded connection. The inner diameter of the abutting part (152) is smaller than the outer diameter of the inner working cylinder (2).

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