Sliding sleeve

Abstract

The upper end of an upper joint and the lower end of a lower joint are respectively connected with an oil pipe; two ends of the middle sleeve are respectively connected with upper and lower joints; a middle sleeve circular hole is formed in the middle of the middle sleeve body; the center sliding sleeve is arranged on the inner side of the middle sleeve and between the upper connector and the lower connector. The central sliding sleeve is provided with a sliding sleeve circular hole and a sliding sleeve waist-shaped hole; sealing assemblies are arranged between the upper and lower ends of the central sliding sleeve and the sealing surface of the middle sleeve; a 90-degree circular bead I is arranged on the inner side wall of the upper joint, and a 90-degree circular bead II and a balance limiting groove are arranged on the inner side wall of the lower joint; when the central sliding sleeve slides up and down to the 90-degree shoulder I at the uppermost end, the sliding sleeve is completely closed; when the sliding sleeve slides to the 90-degree shoulder II at the lowest end, the sliding sleeve is completely opened; when the sliding sleeve slides to the balance limiting groove, fluid pressure inside and outside the sliding sleeve is balanced. The plugging device is simple and reasonable in structural design, convenient to operate and use, good in plugging effect and safe, stable and reliable to operate.

Description

Technical Field

[0001] The utility model belongs to the technical field of equipment for oil production in wells, and in particular relates to a sliding sleeve. Background Art

[0002] When oil wells are completed, if the passage between the oil pipe and the annular space is not effectively blocked, the pressure difference of the downhole fluid may be too large, which may lead to blowouts or other safety accidents. The safety of the passage blocking needs to be guaranteed by the sliding sleeve and the matching switch tools.

[0003] Especially when the pressure difference between the inside and outside of the sleeve is too large, quickly opening the sleeve may damage the sealing component inside the sleeve.

[0004] From the above, it can be seen that it is necessary to set a balance position at the lower joint of the sliding sleeve. When opening the sliding sleeve, first observe the change of the wellhead oil pressure. When the pressure changes due to shock, wait until the pressure is balanced before continuing to shock downward until the sliding sleeve is completely opened. In this regard, the following technical solution is proposed. Utility Model Content

[0005] The technical problem solved by the utility model is to provide a sliding sleeve to solve the technical problem of how to open the sliding sleeve conveniently and stably.

[0006] The technical solution adopted by the utility model is as follows: a sliding sleeve comprises an upper joint, a central sliding sleeve, an intermediate sleeve and a lower joint; the upper end of the upper joint and the lower end of the lower joint are respectively connected to the oil pipe; the upper end of the intermediate sleeve is connected to the lower end of the upper joint through an internal thread coaxial seal; the lower end of the intermediate sleeve is connected to the upper end of the lower joint through an internal thread coaxial seal; an intermediate sleeve circular hole is formed in the middle of the intermediate sleeve body; the central sliding sleeve is coaxially arranged on the inner side of the intermediate sleeve and axially slidably placed between the upper joint and the lower joint; the central sliding sleeve is formed with a plurality of sliding sleeve circular holes and sliding sleeve waist-shaped holes; the sliding sleeve circular holes and the sliding sleeve waist-shaped holes are used to communicate when the sliding sleeve is opened The inner and outer fluids of the circular hole of the intermediate sleeve; a sealing assembly is arranged between the upper and lower ends of the center sleeve and the sealing surface of the intermediate sleeve; a 90° shoulder Ⅰ is formed on the inner wall of the upper joint; a 90° shoulder Ⅱ is formed on the inner wall of the lower joint; a balancing limit groove is formed above the 90° shoulder Ⅱ on the inner wall of the lower joint; the center sleeve is driven by the sleeve switch tool to slide axially up and down; when the center sleeve slides to the uppermost 90° shoulder Ⅰ, the sleeve is completely closed; when the center sleeve slides to the lowermost 90° shoulder Ⅱ, the sleeve is completely opened; when the center sleeve slides to the balancing limit groove, it is used to balance the fluid pressure inside and outside the sleeve.

[0007] In the above technical solution, further: it also includes an open ring; the open ring is installed in an open ring groove formed on the inner wall of the intermediate sleeve body; the open ring is used to separate, position and protect the sealing component.

[0008] In the above technical scheme, further: the sealing component is composed of sealing component I, sealing component II, and sealing component III; the open ring is used to separate sealing component I and sealing component II; and the open ring is used to limit the string movement of sealing component I and prevent damage to sealing component I; sealing component I and sealing component II are arranged above the circular hole of the middle sleeve; sealing component III is arranged below the circular hole of the middle sleeve.

[0009] In the above technical scheme, further: the sealing component I is composed of a pair of support rings II, V-shaped seals I, V-shaped seals II and a single O-ring II; a V-shaped seal I is provided on the inner side of the support ring II; a V-shaped seal II is provided on the inner side of the V-shaped seal I; an O-ring II is provided at the inner center of the V-shaped seal II.

[0010] In the above technical solution, further: the sealing component II is composed of a pair of support rings I and a single O-ring II; the support ring I is arranged on the outside of the O-ring II.

[0011] In the above technical scheme, further: the sealing assembly III is composed of a pair of support rings II, V-shaped seals I, V-shaped seals II and a single O-ring II; a V-shaped seal I is provided on the inner side of the support ring II; a V-shaped seal II is provided on the inner side of the V-shaped seal I; an O-ring II is provided at the inner center of the V-shaped seal II.

[0012] In the above technical solution, further: the threaded sealing connection surface between the upper joint and the middle sleeve; and the threaded sealing connection surface between the lower joint and the middle sleeve are respectively formed with joint grooves; an O-ring I is provided in the joint groove, and the sealing of the sealing connection surface is achieved by the O-ring I.

[0013] In the above technical solution, further: the inner side wall above the 90° shoulder Ⅰ of the upper joint is formed with a neck and a groove; the neck and the groove are used to fix the downhole flow control device or the plug for temporarily blocking the fluid.

[0014] In the above technical solution, further: a limit boss is formed on the outer side wall of the lower part of the central sliding sleeve body; when the limit boss is matched with the limit stopper of the balance limit groove, the limit boss is used for temporary balance limit of the downward movement of the central sliding sleeve.

[0015] The advantages of this utility model compared with the prior art:

[0016] 1. The sleeve switch tool of the utility model can make the center sleeve slide up and down; when the center sleeve slides to the uppermost end, the sleeve is in a completely closed state, and the fluid channel between the oil pipe and the inner annular space of the sleeve is blocked; when the center sleeve slides to the middle balance limit groove, it is the balance position of the sleeve, that is, when opening the sleeve, first observe the change of the wellhead oil pressure, and when the pressure change is shocked, wait until the pressure is balanced, and then continue to shock downward until the sleeve is completely opened; when the center sleeve slides to the lowermost end, the sleeve is in a completely open state, and the channel between the oil pipe and the inner annular space of the sleeve is connected.

[0017] 2. The open ring of the utility model is inserted into the open ring groove of the intermediate sleeve to limit the string movement of the sealing component I, reduce the gap between the sealing parts, prevent the V-shaped seal I, V-shaped seal II and a single O-ring II of the sealing component I from being damaged during the up and down movement of the center sleeve, and improve the sealing performance.

[0018] 3. The support ring I and the support ring II of the utility model support the V-type seal I, V-type seal II and the single O-ring II respectively, and can also reduce the impact deformation of the high-pressure fluid on the V-type seals I and II, thereby increasing the service life of the V-type seals I and II and improving the sealing performance of the sleeve.

[0019] 4. The V-shaped seals I and II of the sealing components I and III of the utility model can block the downhole fluid when the sliding sleeve is closed; and the sealing components I and III are placed at the sealing surface between the central sliding sleeve and the intermediate sleeve, with a long service life and good sealing performance.

[0020] 5. The O-ring I and the sealing assembly of the utility model play a double sealing role, which plays a double insurance role for the blocking effect of the sliding sleeve. The V-shaped seal I, V-shaped seal II and O-ring II are placed side by side, and the gap between the seals is adjusted by an open ring, which further improves the sealing performance.

[0021] 6. The utility model has a simple and reasonable structural design, is easy to operate and use, and has stable and reliable performance. The sliding sleeve is different from other downhole pressure plugging tools. It is directly placed at the bottom of the well or at a certain depth downhole together with the oil pipe when the well is completed. It can be used to plug the channel between the oil pipe and the annular space, and can also plug the production pipe column. The plugging effect is good and the operation is safe and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the front view of the utility model;

[0023] Figure 2 for Figure 1 Schematic diagram of the local structure of the upper joint;

[0024] Figure 3 for Figure 1 A schematic diagram of the structure of the internal sealing component of the intermediate sleeve;

[0025] Figure 4 for Figure 1 Schematic diagram of the local structure of the lower joint;

[0026] In the figure: 1-upper joint, 101-90° shoulder Ⅰ, 102-neck and slot; 2-center sleeve, 201-sleeve circular hole, 202-sleeve waist hole, 203-limiting boss; 3-middle sleeve, 301-middle sleeve circular hole, 4-opening ring, 5-support ring Ⅰ, 6-lower joint, 601-90° shoulder Ⅱ, 602-balance limiting groove; 7-support ring Ⅱ, 8-V-type seal Ⅰ, 9-V-type seal Ⅱ, 10-O-ring Ⅰ, 11-O-ring Ⅱ, 12-sealing assembly Ⅰ, 13-sealing assembly Ⅱ, 14-sealing assembly Ⅲ. DETAILED DESCRIPTION

[0027] The following will be combined with the attached embodiment of the utility model Figure 1-4 , clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of them. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0028] (like Figure 1 A sliding sleeve as shown in the figure comprises an upper joint 1, a central sliding sleeve 2, an intermediate sleeve 3 and a lower joint 6. The upper joint 1, the central sliding sleeve 2, the intermediate sleeve 3 and the lower joint 6 are respectively an integrated structure, which is easy to produce, has a simple structure and a small number of components.

[0029] The upper end of the upper joint 1 and the lower end of the lower joint 6 are connected to oil pipes respectively.

[0030] The upper end of the intermediate sleeve 3 is connected to the lower end of the upper joint 1 through an internal thread coaxial seal; the lower end of the intermediate sleeve 3 is connected to the upper end of the lower joint 6 through an internal thread coaxial seal.

[0031] In the above embodiment, further: the threaded sealing connection surface between the upper joint 1 and the intermediate sleeve 3; and the threaded sealing connection surface between the lower joint 6 and the intermediate sleeve 3 are respectively formed with joint grooves; an O-ring Ⅰ10 is arranged in the joint groove, and the sealing connection surface is sealed by the O-ring Ⅰ10. The O-ring Ⅰ10 of the utility model and the sealing assembly described later play a double sealing role, which plays a double insurance role in the blocking effect of the sliding sleeve.

[0032] The middle sleeve 3 is provided with an intermediate sleeve circular hole 301 in the middle of the sleeve body; the intermediate sleeve circular hole 301 is used to connect the internal and external fluids.

[0033] The central sleeve 2 is coaxially arranged inside the middle sleeve 3 and axially slidably placed between the upper joint 1 and the lower joint 6 , and the sleeve as a whole is opened and closed by the sliding of the central sleeve 2 .

[0034] The central sleeve 2 is formed with a plurality of sleeve circular holes 201 and sleeve waist-shaped holes 202; the sleeve circular holes 201 and sleeve waist-shaped holes 202 are used to connect the internal and external fluids of the intermediate sleeve circular hole 301 when the sleeve is opened.

[0035] A sealing assembly is provided between the upper and lower ends of the central sleeve 2 and the sealing surface of the intermediate sleeve 3. Reliable sealing is achieved through the sealing assembly.

[0036] In the above embodiment, further: it also includes an open ring 4; the open ring 4 is installed in an open ring groove formed on the inner side wall of the intermediate sleeve 3; the open ring 4 is used to separate, position and protect the sealing component.

[0037] (like Figure 3 As shown in the above embodiment, further: the sealing component is composed of a sealing component I12, a sealing component II13, and a sealing component III14.

[0038] The open ring 4 is used to separate the sealing component I 12 and the sealing component II 13. The open ring 4 is used to limit the movement of the sealing component I 12 and prevent the sealing component I 12 from being damaged. The sealing components I 12 and II 13 are arranged above the circular hole 301 of the intermediate sleeve; the sealing component III 14 is arranged below the circular hole 301 of the intermediate sleeve.

[0039] In the above embodiment, further: the sealing assembly I12 is composed of a pair of support rings II7, a V-shaped seal I8, a V-shaped seal II9 and a single O-ring II11. A pair of V-shaped seals I8 are arranged inside the support ring II7; a pair of V-shaped seals II9 are arranged inside the V-shaped seal I8; and the O-ring II11 is arranged at the center of the inner side of the V-shaped seal II9. The support ring II7 of the utility model supports the V-shaped seal I8, the V-shaped seal II9 and the single O-ring II11 respectively, and can also reduce the impact deformation of the high-pressure fluid on the V-shaped seals I and II, thereby increasing the service life of the V-shaped seals I and II and improving the sealing performance of the sleeve.

[0040] In the above embodiment, further: the sealing assembly II13 is composed of a pair of support rings I5 and a single O-ring II11; the support ring I5 is arranged outside the O-ring II11. The support ring I5 of the utility model supports the single O-ring II11, reduces the impact deformation of the high-pressure fluid on the O-ring II11, and improves the sealing performance of the O-ring II11.

[0041] In the above embodiment, further: the sealing assembly III14 is composed of a pair of support rings II7, V-shaped seals I8, V-shaped seals II9 and a single O-ring II11. The inner side of the support ring II7 is provided with a V-shaped seal I8; the inner side of the V-shaped seal I8 is provided with a V-shaped seal II9; the inner center of the V-shaped seal II9 is ​​provided with the O-ring II11. Similarly, the support ring II7 supports the V-shaped seals I8, V-shaped seals II9 and the single O-ring II11, reduces the impact deformation of the high-pressure fluid on the V-shaped seals I and II, improves the service life of the V-shaped seals I and II, and increases the sealing performance of the sleeve.

[0042] The open ring 4 of the utility model is inserted into the open ring groove of the intermediate sleeve 3 to limit the string movement of the sealing component Ⅰ12, reduce the gap between the sealing parts, prevent the V-shaped seal Ⅰ8, V-shaped seal Ⅱ9 and a single O-ring Ⅱ11 of the sealing component Ⅰ12 from being damaged during the up and down movement of the central sliding sleeve 2, and improve the sealing performance.

[0043] The V-shaped seals I8 and II9 of the sealing components I12 and III14 of the utility model can block the downhole fluid when the sliding sleeve is closed; and the sealing components I12 and III14 are placed on the sealing surface between the central sliding sleeve 2 and the intermediate sleeve 3, with a long service life and good sealing performance.

[0044] In the utility model, the V-shaped seal I8, the V-shaped seal II9 and the O-ring II11 are placed side by side, and the gap between the seals is adjusted through the open ring 4, thereby further improving the sealing performance.

[0045] (like Figure 2 As shown) the inner wall of the upper joint 1 is formed with a 90° shoulder Ⅰ101; (as shown Figure 4 (As shown) the inner wall of the lower joint 6 is formed with a 90° shoulder II 601. A balancing limit groove 602 is formed above the 90° shoulder II 601 of the inner wall of the lower joint 6. The center sleeve 2 is driven by the sleeve switch tool to slide the center sleeve 2 axially up and down; when the center sleeve 2 slides to the uppermost 90° shoulder I 101, the sleeve is completely closed; when the center sleeve 2 slides to the lowermost 90° shoulder II 601, the sleeve is completely opened; when the center sleeve 2 slides to the balancing limit groove 602, it is used to balance the fluid pressure inside and outside the sleeve, thereby improving the safety, stability and reliability of the sleeve.

[0046] (like Figure 2 As shown in the above embodiment, further: the inner side wall above the 90° shoulder Ⅰ101 of the upper joint 1 is formed with a neck and a groove 102; the neck and the groove 102 are used to fix the downhole flow control device or the plug for temporarily blocking the fluid.

[0047] In the above embodiment, further: a limit boss 203 is formed on the lower outer wall of the central sleeve 2; when the limit boss 203 is matched with the limit stopper of the balance limit groove 602 mentioned above, the limit boss 203 is used for temporary balance limit of the downward movement of the central sleeve 2.

[0048] The assembly process of the utility model is as follows: seal component I (including support ring II 7, V-type seal I 8, V-type seal II 9, O-ring II 11), seal component II (including support ring I 5 and O-ring II 11), seal component III (including support ring II 7, V-type seal I 8, V-type seal II 9, O-ring II 11), open ring 4 are attached Figure 3 Insert the middle sleeve 3 into the position shown; then push the center sleeve 2 upward from the inner hole at the lower end of the middle sleeve 3, and stop inserting after the waist-shaped hole 202 at the upper end of the center sleeve 2 is exposed from the upper end surface of the middle sleeve 3; then clamp the upper joint 1 in the vise, install the O-ring Ⅰ10 into the O-groove of the upper joint 1, and then connect the upper end of the middle sleeve 3 with the lower end thread of the upper joint 1 and tighten them; finally, install the O-ring Ⅰ10 in the O-groove of the lower joint, and then screw the upper end thread of the lower joint 6 into the lower end thread of the middle sleeve 3 and tighten it, and the assembly is completed.

[0049] The working principle of the utility model is as follows: the sleeve switch tool of the utility model can make the center sleeve 2 slide up and down; when the center sleeve 2 slides to the uppermost 90° shoulder Ⅰ101, the sleeve is in a completely closed state, and at this time, the fluid channel between the oil pipe and the inner annular space of the sleeve is blocked; when the center sleeve 2 slides to the middle balance limit groove 602, it is the balance position of the sleeve, that is, when opening the sleeve, first observe the change of the wellhead oil pressure, and when the pressure change is shocked, wait until the pressure is balanced before continuing to shock downward; when the center sleeve 2 slides to the lowermost 90° shoulder Ⅱ601, the sleeve is in a completely open state, and at this time, the channel between the oil pipe and the inner annular space of the sleeve is connected.

[0050] From the above description, it can be found that: the open ring 4 of the utility model is inserted into the open ring groove of the intermediate sleeve 3, which is used to limit the string movement of the sealing component Ⅰ12, reduce the gap between the seals, prevent the V-type seal Ⅰ8, V-type seal Ⅱ9 and single O-ring Ⅱ11 of the sealing component Ⅰ12 from being damaged during the up and down movement of the center sleeve 2, and improve the sealing performance.

[0051] The support ring Ⅰ5 and the support ring Ⅱ7 of the utility model support the V-shaped seal Ⅰ8, the V-shaped seal Ⅱ9 and the single O-ring Ⅱ11 respectively, and can also reduce the impact deformation of the high-pressure fluid on the V-shaped seals Ⅰ and Ⅱ, thereby increasing the service life of the V-shaped seals Ⅰ and Ⅱ and improving the sealing performance of the sleeve.

[0052] The V-shaped seals I8 and II9 of the sealing components I12 and III14 of the utility model can block the downhole fluid when the sliding sleeve is closed; and the sealing components I12 and III14 are placed on the sealing surface between the central sliding sleeve 2 and the intermediate sleeve 3, with a long service life and good sealing performance.

[0053] The O-ring Ⅰ10 and the sealing components Ⅰ, Ⅱ and Ⅲ of the utility model play a double sealing role, which plays a double insurance role for the blocking effect of the sliding sleeve. The V-shaped seal Ⅰ8, the V-shaped seal Ⅱ9 and the O-ring Ⅱ11 are placed side by side, and the gap between the seals is adjusted by the open ring 4, which further improves the sealing performance.

[0054] It should be noted that the sleeve of the utility model uses a sleeve switch tool to open and close the sleeve, which is a mechanical operation. Compared with the fracturing sleeve, the sleeve is opened by pressing and shearing the pin after throwing a ball, and the fracturing sleeve cannot be separated from the operation of the pressure element. The sleeve of the utility model has a simple structure, convenient operation, stable performance, and is not easy to fail. The fracturing sleeve has a complex structure, many operating steps, and there is a risk of failure due to throwing a ball. Furthermore, the sleeve switch tool of the utility model can be removed underground and can be reused. The opening tool of the fracturing sleeve is a sphere, which needs to be dissolved underground and cannot be reused.

[0055] To sum up, the utility model has a simple and reasonable structural design, is easy to operate and use, and has stable and reliable performance. The sliding sleeve is different from other downhole pressure plugging tools. It is directly placed at the bottom of the well or at a certain depth downhole together with the oil pipe when the well is completed. It can be used to plug the channel between the oil pipe and the annular space, and can also plug the production pipe string. The plugging effect is good, and the operation is safe, stable and reliable.

[0056] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A sliding sleeve, characterized in that: The utility model comprises an upper joint (1), a central sleeve (2), an intermediate sleeve (3) and a lower joint (6); the upper end of the upper joint (1) and the lower end of the lower joint (6) are respectively connected to oil pipes; the upper end of the intermediate sleeve (3) is connected to the lower end of the upper joint (1) through an internal thread coaxial seal; the lower end of the intermediate sleeve (3) is connected to the upper end of the lower joint (6) through an internal thread coaxial seal; the middle part of the intermediate sleeve (3) is provided with an intermediate sleeve circular hole (301); the central sleeve (2) is coaxially arranged on the inner side of the intermediate sleeve (3) and axially slidably placed between the upper joint (1) and the lower joint (6); the central sleeve (2) is provided with a plurality of sleeve circular holes (201) and sleeve waist-shaped holes (202); the sleeve circular holes (201) and sleeve waist-shaped holes (202) are used to connect with the intermediate sleeve circular holes (301) when the sleeve is opened. The central sleeve (2) is provided with a sealing assembly between the upper and lower ends of the central sleeve (2) and the sealing surface of the intermediate sleeve (3); the inner wall of the upper joint (1) is provided with a 90° shoulder I (101); the inner wall of the lower joint (6) is provided with a 90° shoulder II (601); a balancing limit groove (602) is provided above the 90° shoulder II (601) of the inner wall of the lower joint (6); the central sleeve (2) is driven by a sleeve switch tool to slide axially up and down; when the central sleeve (2) slides to the uppermost 90° shoulder I (101), the sleeve is completely closed; when the central sleeve (2) slides to the lowermost 90° shoulder II (601), the sleeve is completely opened; when the central sleeve (2) slides to the balancing limit groove (602), it is used to balance the pressure of the fluid inside and outside the sleeve.

2. The sliding sleeve according to claim 1, characterized in that: It also comprises an open ring (4); the open ring (4) is installed in an open ring groove formed on the inner side wall of the intermediate sleeve (3); the open ring (4) is used to separate, position and protect the sealing component.

3. The sliding sleeve according to claim 2, characterized in that: The sealing assembly is composed of a sealing assembly I (12), a sealing assembly II (13), and a sealing assembly III (14); the open ring (4) is used to separate the sealing assembly I (12) and the sealing assembly II (13); and the open ring (4) is used to limit the movement of the sealing assembly I (12) and prevent the sealing assembly I (12) from being damaged; the sealing assembly I (12) and the sealing assembly II (13) are arranged above the circular hole (301) of the intermediate sleeve; and the sealing assembly III (14) is arranged below the circular hole (301) of the intermediate sleeve.

4. The sliding sleeve according to claim 3, characterized in that: The sealing assembly I (12) is composed of a pair of support rings II (7), a V-shaped seal I (8), a V-shaped seal II (9) and a single O-ring II (11); the V-shaped seal I (8) is arranged on the inner side of the support ring II (7); the V-shaped seal II (9) is arranged on the inner side of the V-shaped seal I (8); the O-ring II (11) is arranged at the inner center of the V-shaped seal II (9).

5. The sliding sleeve according to claim 3, characterized in that: The sealing assembly II (13) is composed of a pair of support rings I (5) and a single O-ring II (11); the support ring I (5) is arranged outside the O-ring II (11).

6. The sliding sleeve according to claim 3, characterized in that: The sealing assembly III (14) is composed of a pair of support rings II (7), a V-shaped seal I (8), a V-shaped seal II (9) and a single O-ring II (11); the V-shaped seal I (8) is arranged on the inner side of the support ring II (7); the V-shaped seal II (9) is arranged on the inner side of the V-shaped seal I (8); the O-ring II (11) is arranged at the inner center of the V-shaped seal II (9).

7. The sliding sleeve according to claim 1, characterized in that: The threaded sealing connection surface between the upper joint (1) and the intermediate sleeve (3); and the threaded sealing connection surface between the lower joint (6) and the intermediate sleeve (3) are respectively provided with joint grooves; an O-ring I (10) is provided in the joint groove, and the sealing connection surface is sealed by the O-ring I (10).

8. The sliding sleeve according to claim 1 or 7, characterized in that: The inner side wall above the 90° shoulder Ⅰ (101) of the upper joint (1) is provided with a neck and a groove (102); the neck and the groove (102) are used to fix a downhole flow control device or a plug for temporarily blocking fluid.

9. The sliding sleeve according to claim 1, characterized in that: A limiting boss (203) is formed on the outer side wall of the lower part of the sleeve body of the central sliding sleeve (2); when the limiting boss (203) is matched with the limiting block of the balancing limiting groove (602), the limiting boss (203) is used for temporary balancing limiting of the downward movement of the central sliding sleeve (2).

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