A floating short section, a floating lower tail pipe string and its application

Abstract

The present invention provides a floating short section, a floating lower tail pipe string and its application, and belongs to the field of well solidification completion technology in the petroleum industry. The floating short section includes: a body and a retaining ring, a rupture disk, a striker mechanism and a sliding sleeve installed in the inner cavity of the body; the retaining ring is installed in the upper part of the inner cavity of the body; the striker mechanism is a stepped shaft structure, including a large diameter section and a small diameter section, and the connection between the two forms a shaft shoulder; a central through hole coaxial with the striker mechanism is opened on the striker mechanism; the sliding sleeve is sleeved on the outside of the small diameter section of the striker mechanism and connected to the striker mechanism through shear nails; the upper end surface of the sliding sleeve is higher than the upper end surface of the striker mechanism; the rupture disk is installed between the lower end surface of the retaining ring and the upper end surface of the sliding sleeve; there is a gap between the lower end surface of the sliding sleeve and the shaft shoulder of the striker mechanism. The present invention reduces the friction between the tail pipe and the open hole, and realizes the floating lowering of the tail pipe of horizontal wells and large displacement wells.

Description

Technical Field

[0001] The invention belongs to the technical field of well solidification and completion in the petroleum industry, and in particular relates to a floating pup joint, a floating lower tail pipe string and applications thereof. Background Art

[0002] When the casing is lowered into a horizontal well, the casing will go down close to the bottom of the horizontal wellbore. In addition, the drilling fluid injected into the casing during normal lowering increases the contact force of the casing on the well wall, which increases the friction resistance, making the lowering of the casing very difficult, and may even cause the casing to fail to be lowered into place, resulting in significant economic losses. In recent years, floating technology has been used to address the problems of long horizontal sections, shallow vertical depth, large water-to-vertical ratio, limited tail pipe pressurization, and easy casing jams.

[0003] Chinese patent publication CN205577845U discloses a self-breaking floating casing tool, which is mainly composed of an outer body, an elastic spacer, a blind plate and a cementing ring. The two ends of the outer body are connecting ends. An elastic spacer is arranged in the middle of the outer body, and a blind plate is arranged inside the elastic spacer. The cementing ring is arranged in the outer body and on the upper part of the elastic steel ring; Chinese patent publication CN1910336B discloses a test plug device, which is a plug for pressure testing of a wellbore and a related pipe. In the pipe, the plug is installed in a plug loading chamber, and the plug seals the passage through the pipe by combining with a sealing body, and the lower side of the plug is arranged (placed) on a seat at the bottom of the chamber. The plug includes a plurality of layered or laminated annular disc elements of a given thickness, each of which is The element is installed on the top of another element; Chinese patent publication CN107313727U discloses a high-strength self-dissolving coupling for floating casing, which includes an upper joint, a sliding sleeve, a pressure plate and a lower joint, the inner wall of the upper joint is provided with a sliding groove, and the sliding sleeve and the sliding groove form an axial sliding sealing fit; the pressure plate and the lower joint are sealed and fixedly connected; a sleeve is provided above the pressure plate, the upper end of the sleeve is connected to the lower end of the sliding sleeve by a pin, and the lower part of the sliding sleeve and the upper part of the sleeve form an axial plug-in fit; an opener is provided at the joint between the sleeve and the pressure plate; a dissolving liquid tank is provided in the sleeve; the dissolving liquid tank and the bottom of the upper sliding sleeve form an extrusion fit, and the dissolving liquid tank and the lower opener form an opening fit; the pressure plate, sleeve, sliding sleeve and dissolving liquid tank are all made of self-dissolving high-strength material.

[0004] The key tool for floating casing lowering is the floating nipple. As can be seen from the above patent, there are currently two main types of floating nipple. One is the blind plate type. The main problem with this type of nipple is that the blind plate may break prematurely during the lowering process. Therefore, most of them use high-strength prestressed materials. However, if there is no breaking point, it is easy to fail to open under the set pressure. The other is the sliding sleeve type. The circulation hole is opened by shear nails to achieve internal circulation of the pipe. However, before cementing, a rubber plug needs to be inserted to push the internal sliding sleeve mechanism as a whole to the floating collar position. The operation is more complicated and has a certain risk of jamming.

[0005] At present, casing floating technology is mainly used for full-well casing, and there is no related method for floating liner. The main reasons are:

[0006] 1) The floating sub achieves temporary plugging inside the pipe. The turbulent pressure during lowering of the liner has a significant impact on the hydraulic liner hanger, which may lead to accidents such as premature liner hanging.

[0007] 2) If the floating nipple adopts a sliding sleeve structure, after the liner is in place, a specific rubber plug needs to be put in to open the coupling to achieve circulation. It cannot be integrated with the existing liner cementing tools and increases the risk of cementing operations.

[0008] 3) If the existing blind plate structure is used, the opening reliability is low and the diameter cannot be guaranteed, which affects the subsequent cementing operation. Summary of the invention

[0009] The purpose of the present invention is to solve the problems existing in the above-mentioned prior art, and to provide a floating pup joint, a floating liner string and applications thereof, so as to reduce the friction between the liner and the open hole and realize the rapid lowering of the liner in horizontal wells and large-displacement wells.

[0010] The present invention is achieved through the following technical solutions:

[0011] A first aspect of the present invention provides a floating nipple, the floating nipple comprising: a body, and a retaining ring, a rupture disk, a striker mechanism and a sliding sleeve installed in an inner cavity of the body;

[0012] The retaining ring is installed on the upper part of the inner cavity of the body;

[0013] The striker mechanism is a stepped shaft structure, including a large diameter section and a small diameter section, and a shaft shoulder is formed at the connection between the two sections; a central through hole coaxial with the striker mechanism is opened on the striker mechanism;

[0014] The sliding sleeve is sleeved on the outside of the small diameter section of the striker mechanism and is connected to the striker mechanism through shear pins; the upper end surface of the sliding sleeve is higher than the upper end surface of the striker mechanism;

[0015] The rupture disk is installed between the lower end surface of the retaining ring and the upper end surface of the sliding sleeve;

[0016] There is a gap between the lower end surface of the sliding sleeve and the shaft shoulder of the striker mechanism.

[0017] A further improvement of the present invention is:

[0018] A plurality of strikers evenly distributed on the circumference are arranged at one end of the small diameter section of the striker mechanism away from the shaft shoulder;

[0019] Each firing pin is a sharp structure protruding upward;

[0020] There is a gap between two adjacent firing pins.

[0021] A further improvement of the present invention is:

[0022] A plurality of breathing holes are opened on the small diameter section of the striker mechanism near the shaft shoulder, and each breathing hole is connected to the central through hole of the striker mechanism;

[0023] The plurality of breathing holes are evenly distributed on the circumference, and the central axis of each breathing hole is perpendicular to the central axis of the striker mechanism.

[0024] A further improvement of the present invention is:

[0025] The sliding sleeve is a cylindrical structure, and is provided with a plurality of first shear nail holes;

[0026] The plurality of first shear nail holes are evenly distributed on the circumference, and the central axis of each first shear nail hole is perpendicular to the central axis of the sliding sleeve.

[0027] A further improvement of the present invention is:

[0028] A plurality of second shear nail holes are opened on the small diameter section of the striker mechanism, and the second shear nail holes are located above the breathing hole; the second shear nail holes correspond to the first shear nail holes on the sliding sleeve one by one;

[0029] The small diameter section of the striker mechanism is inserted into the inner cavity of the sliding sleeve, and each first shear nail hole is aligned with the second shear nail hole, and the shear nail passes through the first shear nail hole and the second shear nail hole in sequence.

[0030] A further improvement of the present invention is:

[0031] The main body is a cylindrical structure, and internal threads are respectively arranged on the upper and lower parts of its inner wall;

[0032] The retaining ring is a cylindrical structure, and an external thread is arranged on its outer wall, and the retaining ring is connected to the internal thread on the upper part of the main body through the external thread;

[0033] An external thread is arranged on the outer wall of the large diameter section of the striker mechanism, and the striker mechanism is connected with the internal thread of the lower part of the body through the external thread.

[0034] A further improvement of the present invention is:

[0035] An annular sealing groove coaxial with the inner wall of the body is provided, and the sealing groove is located between the lower end surface of the retaining ring and the upper end surface of the sliding sleeve;

[0036] A sealing member is installed in the sealing groove;

[0037] The seal is located between the outer wall of the rupture disk and the inner wall of the body.

[0038] A second aspect of the present invention provides a floating liner string, the floating liner string comprising: a floating shoe, a liner, the above-mentioned floating nipple, a liner hanger, and a drill pipe connected in sequence.

[0039] Preferably, the liner hanger is a balanced cylinder hanger.

[0040] A third aspect of the present invention provides a method for applying the above floating tail pipe string, the method comprising:

[0041] After the floating lower tail pipe string is lowered into place, pressure is applied to the drill pipe above the floating short joint, and the pressure is transmitted to the rupture disk through the central through hole of the retaining ring, and then to the sliding sleeve through the rupture disk, thereby shearing the shear pins. The rupture disk and the sliding sleeve move downward rapidly, and the rupture disk touches the striker, which smashes the rupture disk and breaks it into tiny particles. The tiny particles enter the central through hole of the striker mechanism from the gap between the strikers and are discharged, and then the tiny particles are discharged from the wellbore through circulation, so that the full diameter of the tail pipe is achieved;

[0042] After the circulation is completed, the liner hanger is set and then the liner is cemented to form a cement ring.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The present invention reduces the friction between the tail pipe and the open hole, and realizes the floating lowering of the tail pipe of the horizontal well and the large displacement well. The floating short section in the present invention controls the start of the striker through the shear nail, smashes the rupture disk, and improves the opening reliability of the floating short section; at the same time, the rupture disk is made of special brittle materials with strong pressure bearing capacity. After being smashed, it becomes tiny particles and can be circulated out of the well, realizing the full diameter of the casing, and there is no need to change the subsequent tail pipe hanger sitting and cementing operation process; the balanced tail pipe hanger can prevent the tail pipe hanger from sitting early due to abnormal pressure changes in the pipe. At the same time, after encountering resistance during floating lowering, the floating device can be opened by holding pressure, and the large-displacement circulation can be used to remove the resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a schematic diagram of the floating lower tail pipe string;

[0046] Figure 2 It is a schematic diagram of tail pipe circulation;

[0047] Figure 3 It is a schematic diagram of tail pipe cementing;

[0048] Figure 4 It is a structural diagram of a floating short section.

[0049] in:

[0050] 1- Strata

[0051] 2-Upper casing

[0052] 3-Drill rod

[0053] 4-Tinner pipe hanger

[0054] 5-Floating short section

[0055] 6-Drilling fluid

[0056] 7-Tail pipe

[0057] 8-naked eye

[0058] 9-Floating shoes

[0059] 10-Cement ring

[0060] 501-Retaining ring

[0061] 502-Rupture disk

[0062] 503-Firing pin mechanism

[0063] 5031-Firing pin

[0064] 5032-Groove

[0065] 5033-Breathing hole

[0066] 504-Shear nails

[0067] 505-Sliding Bushing

[0068] 506-Ontology

[0069] 507-Seal. DETAILED DESCRIPTION

[0070] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0071] The floating short section of the present invention comprises: a body and a retaining ring, a rupture disk, a striker mechanism and a sliding sleeve installed in the inner cavity of the body; the retaining ring is installed at the upper part of the inner cavity of the body; the striker mechanism is a stepped shaft structure, including a large diameter section and a small diameter section, and a shaft shoulder is formed at the connection between the two; a central through hole coaxial with the striker mechanism is opened on the striker mechanism; the sliding sleeve is sleeved on the outside of the small diameter section of the striker mechanism and is connected to the striker mechanism by shear nails; the upper end surface of the sliding sleeve is higher than the upper end surface of the striker mechanism; the rupture disk is installed between the lower end surface of the retaining ring and the upper end surface of the sliding sleeve; there is a gap between the lower end surface of the sliding sleeve and the shaft shoulder of the striker mechanism.

[0072] Embodiments of the present invention are as follows:

[0073] [Example 1]

[0074] like Figure 1 As shown, the floating liner string of the present invention includes: a floating shoe 9, a liner 7, a floating short section 5, a liner hanger 4, and a drill pipe 3 connected in sequence, and each mechanism is connected by a threaded buckle. Specifically, the lower end of the drill pipe 3 is threadedly connected to the upper end of the liner hanger 4, the lower end of the liner hanger 4 is connected to the upper end of the floating short section 5, the lower end of the floating short section 5 is connected to one end of the liner 7, and the other end of the liner 7 is connected to the floating shoe 9.

[0075] In this way, a floating section is formed inside the tail pipe through the floating shoe 9 and the floating short section 5. The inside of the floating section can be air or low-density liquid, so that the tail pipe 7 is suspended in the open hole 8, the positive pressure of the lower pipe string on the well wall is reduced, and the friction resistance of the lowering is greatly reduced. Drilling fluid 6 is poured into the pipe string above the floating short section to increase the gravity of the upper pipe string, push the pipe string downward, and thus realize the smooth lowering of the entire pipe string.

[0076] In order to further reduce the risk of the pipe string encountering obstruction, the tail pipe hanger 4 arranged above the floating short section adopts a balanced cylinder hanger (i.e. a balanced tail pipe hanger). If the floating descent encounters obstruction, the floating short section is opened by holding the pressure, and then the obstruction is relieved by large-displacement circulation; at the same time, the hanger will not be prematurely suspended due to the exciting pressure.

[0077] [Example 2]

[0078] like Figure 4 As shown, the floating sub 5 includes a body 506 and a retaining ring 501 , a rupture disk 502 , a striker mechanism 503 , a shear pin 504 , and a sliding sleeve 505 installed in the inner cavity of the body 506 .

[0079] Specifically, the body 506 is a cylindrical structure, and an internal thread is provided on the upper part of the inner wall thereof for connecting with the retaining ring 501, and an internal thread is provided on the lower part of the inner wall of the body 506 for connecting with the lower end of the striker mechanism 503. An annular sealing groove coaxial with the inner wall of the body is provided, and the sealing groove is located below the retaining ring 501. Further, the upper end of the body 506 is connected to the tail pipe hanger 4 through a thread, and the lower end of the body 506 is connected to the tail pipe 7 through a thread.

[0080] The retaining ring 501 is a cylindrical structure with an external thread on its outer wall. The external thread is connected to the internal thread on the upper part of the body 506, so that the retaining ring 501 can be installed in the inner cavity on the upper part of the body 506.

[0081] The striker mechanism 503 is a stepped shaft structure, including a large diameter section and a small diameter section, wherein the diameter of the large diameter section is larger than the diameter of the small diameter section, and a shaft shoulder is formed at the connection between the two. A central through hole coaxial with the striker mechanism 503 is provided. An external thread is provided on the outer wall of the large diameter section, and the external thread is connected to the thread at the lower part of the body 506, so that the striker mechanism 503 is installed in the inner cavity of the body 506.

[0082] The sliding sleeve 505 is sleeved outside the small diameter section of the striker mechanism 503, located between the outer wall of the small diameter section and the inner wall of the body 506, and connected to the striker mechanism 503 through the shear nails 504. There is a gap between the lower end surface of the sliding sleeve 505 and the shaft shoulder of the striker mechanism 503.

[0083] The rupture disk 502 is installed between the lower end surface of the retaining ring 501 and the upper end surface of the sliding sleeve 505, and the rupture disk 502 is fixed in the inner cavity of the body 506 by the retaining ring 501 and the sliding sleeve 505. Before crushing, there is a gap between the uppermost end of the striker mechanism and the rupture disk 502.

[0084] The sealing groove on the inner wall of the main body 506 is located between the lower end surface of the retaining ring 501 and the upper end surface of the sleeve 505. A seal 507 is installed in the sealing groove. The seal 507 can adopt a variety of sealing parts, such as an O-ring or other parts that can form a seal. The seal 507 is located between the outer wall of the rupture disk 502 and the inner wall of the main body 506, and is used to isolate the upper and lower pressures of the rupture disk 502.

[0085] [Example 3]

[0086] The sliding sleeve 505 is a cylindrical structure, and is provided with a plurality of first shear nail holes. Preferably, the plurality of first shear nail holes are evenly distributed on the circumference, and the central axis of each first shear nail hole is perpendicular to the central axis of the sliding sleeve 505 .

[0087] A plurality of breathing holes 5033 are provided near the shoulder of the small diameter section of the striker mechanism 503, and each breathing hole 5033 is connected to the central through hole of the striker mechanism 503. Preferably, the plurality of breathing holes 5033 are evenly distributed on the circumference, and the central axis of each breathing hole 5033 is perpendicular to the central axis of the striker mechanism 503. The breathing holes 5033 are used to prevent a closed space from being formed between the sliding sleeve 505, the body 506 and the striker mechanism 503.

[0088] A plurality of strikers 5031 are provided at one end of the striker mechanism's small diameter section away from the shaft shoulder, each striker 5031 being a sharp structure protruding upwards, and used to strike the rupture disk 502; a gap 5032 between two adjacent strikers 5031 is used to discharge rupture disk debris, to prevent the debris from clogging the gap between the striker mechanism 503 and the sliding sleeve 505. Preferably, the plurality of strikers 5031 are evenly distributed on the circumference.

[0089] Furthermore, a plurality of second shear nail holes are formed on the small diameter section of the striker mechanism 503, and the second shear nail holes are located above the breathing hole 5033. The second shear nail holes correspond one to one with the first shear nail holes on the sliding sleeve.

[0090] During assembly, the small diameter section of the striker mechanism 503 is inserted into the inner cavity of the sleeve 505 and the first shear nail holes are aligned with the second shear nail holes. Then, the shear nails 504 are passed through the first shear nail holes and the second shear nail holes in sequence, and then the sleeve 505 and the striker mechanism 503 are connected. At this time, there is a certain gap between the lower end surface of the sleeve 505 and the shoulder of the striker mechanism 503, which provides space for the downward movement of the sleeve 505, and there is a certain gap between the tip of the striker 5031 of the striker mechanism 503 and the rupture disk 502, ensuring that before the sleeve 505 moves downward, the striker 5031 does not touch the rupture disk 502, and when the rupture disk 502 moves downward with the sleeve 505, the rupture disk 502 contacts the striker 5031.

[0091] The number of the shear nails 504 can be adjusted according to the needs on site, so that the opening pressure of the floating pup joint can be controlled, thereby improving the adaptability and opening accuracy of the floating pup joint.

[0092] The rupture disk 502 is made of a brittle material, such as glass or ceramic, as long as it has the characteristics of high pressure resistance and easy to break into particles (particle size less than 10 mm). According to the use requirements, rupture disks of different pressure resistance levels can be selected to improve the application range of the floating short section.

[0093] [Example 4]

[0094] The method of applying the above floating lower tail pipe string is as follows:

[0095] like Figure 1As shown, an upper casing 2 is arranged in the formation 1. After the floating lower tail pipe string is lowered into place, pressure is applied to the drill pipe 3 above the floating short section 5. The pressure is transmitted to the rupture disk 502 through the central through hole of the retaining ring 501, and then to the sliding sleeve 505 through the rupture disk 502, thereby shearing the shear pin 504. The rupture disk 502 and the sliding sleeve 505 move downward rapidly, and the rupture disk 502 touches the striker 5031. The striker 5031 smashes the rupture disk 502, and the rupture disk 502 is broken into tiny particles. The tiny particles enter the central through hole of the striker mechanism 503 from the gap 5032 between the strikers 5031 and are discharged. In this way, the gap between the striker mechanism 503 and the sliding sleeve 505 is prevented from being blocked by tiny particles. Then, the debris is discharged from the wellbore through circulation, thereby realizing the full diameter of the tail pipe. Figure 2 After the cycle is completed, the liner hanger 4 is set, and then the liner cementing is carried out according to the normal process to form a cement ring 10, as shown in FIG. Figure 3 shown.

[0096] When encountering obstacles while floating down, the methods to resolve the obstacles are as follows:

[0097] The pipe string above the floating short section 5 is pressurized, and the pressure is transmitted to the rupture disk 502 through the central through hole of the retaining ring 501, and then to the sliding sleeve 505, thereby shearing the shear pin 504. The rupture disk 502 and the sliding sleeve 505 move downward rapidly, and the rupture disk 502 touches the striker 5031, and the striker 5031 smashes the rupture disk 502, and the rupture disk 502 is broken into tiny particles. The tiny particles enter the central through hole of the striker mechanism 503 from the gap 5032 between the strikers 5031 and are discharged, and then the debris is discharged from the wellbore through circulation, further unblocking, and the floating tail pipe is sent into place.

[0098] Therefore, the present invention can achieve two ways of reducing frictional resistance by setting a floating short section, wherein one way is floating lowering, and the other way is that if the floating lowering is not in place, the resistance can be relieved by circulation. If the floating short section is not set, there is only one way to reduce frictional resistance, which is circulation relief.

[0099] The floating nipple of the present invention controls the start of the striker by shear nails to break the rupture disk, thereby improving the opening reliability of the floating nipple; at the same time, the rupture disk is made of special brittle material with strong pressure-bearing capacity. After being broken, it becomes tiny particles and can be circulated out of the well to achieve full-diameter casing without changing the subsequent liner hanger sitting and cementing operation process; the present invention adopts a balanced liner hanger to prevent problems such as premature sitting of the liner hanger caused by abnormal pressure changes in the pipe. At the same time, after encountering resistance during floating entry, the floating device can be opened by holding pressure, and large-displacement circulation can be used to achieve resistance relief.

[0100] In the description of the present invention, unless otherwise specified, the terms "upper", "lower", "left", "right", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0101] Finally, it should be explained that the above technical solution is only one implementation method of the present invention. For those skilled in the art, it is easy to make various types of improvements or modifications based on the application methods and principles disclosed in the present invention, and it is not limited to the method described in the above specific implementation method of the present invention. Therefore, the method described above is only preferred and does not have a restrictive meaning.

Claims

1. A floating sub, characterized by: The floating sub comprises: a body and a retaining ring, a rupture disk, a striker mechanism and a sliding sleeve installed in the inner cavity of the body; The retaining ring is installed on the upper part of the inner cavity of the body; The striker mechanism is a stepped shaft structure, including a large diameter section and a small diameter section, and a shaft shoulder is formed at the connection between the two sections; a central through hole coaxial with the striker mechanism is opened on the striker mechanism; The sliding sleeve is sleeved on the outside of the small diameter section of the striker mechanism and is connected to the striker mechanism through shear pins; the upper end surface of the sliding sleeve is higher than the upper end surface of the striker mechanism; The rupture disk is installed between the lower end surface of the retaining ring and the upper end surface of the sliding sleeve; There is a gap between the lower end surface of the sliding sleeve and the shoulder of the striker mechanism; A plurality of breathing holes are opened on the small diameter section of the striker mechanism near the shaft shoulder, and each breathing hole is connected to the central through hole of the striker mechanism; An annular sealing groove coaxial with the inner wall of the body is provided, and the sealing groove is located between the lower end surface of the retaining ring and the upper end surface of the sliding sleeve; A sealing member is installed in the sealing groove; The seal is located between the outer wall of the rupture disk and the inner wall of the body.

2. The floating sub according to claim 1, characterized in that: A plurality of strikers evenly distributed on the circumference are arranged at one end of the small diameter section of the striker mechanism away from the shaft shoulder; Each firing pin is a sharp structure protruding upward; There is a gap between two adjacent firing pins.

3. The floating sub according to claim 2, characterized in that: The plurality of breathing holes are evenly distributed on the circumference, and the central axis of each breathing hole is perpendicular to the central axis of the striker mechanism.

4. The floating sub according to claim 3, characterized in that: The sliding sleeve is a cylindrical structure, and is provided with a plurality of first shear nail holes; The plurality of first shear nail holes are evenly distributed on the circumference, and the central axis of each first shear nail hole is perpendicular to the central axis of the sliding sleeve.

5. The floating sub according to claim 4, characterized in that: A plurality of second shear nail holes are opened on the small diameter section of the striker mechanism, and the second shear nail holes are located above the breathing hole; the second shear nail holes correspond to the first shear nail holes on the sliding sleeve one by one; The small diameter section of the striker mechanism is inserted into the inner cavity of the sliding sleeve, and each first shear nail hole is aligned with the second shear nail hole, and the shear nail passes through the first shear nail hole and the second shear nail hole in sequence.

6. The floating sub according to claim 5, characterized in that: The main body is a cylindrical structure, and internal threads are respectively arranged on the upper and lower parts of its inner wall; The retaining ring is a cylindrical structure, and an external thread is arranged on its outer wall, and the retaining ring is connected to the internal thread on the upper part of the main body through the external thread; An external thread is arranged on the outer wall of the large diameter section of the striker mechanism, and the striker mechanism is connected with the internal thread of the lower part of the body through the external thread.

7. A floating tail pipe string, characterized by: The floating lower liner pipe string comprises: a floating shoe, a liner, a floating nipple according to any one of claims 1 to 6, a liner hanger, and a drill pipe connected in sequence.

8. The floating tail pipe string according to claim 7, characterized in that: The tail pipe hanger adopts a balanced hydraulic cylinder hanger.

9. A method for using the floating liner pipe string according to claim 7 or 8, characterized in that: The method comprises: After the floating liner string as claimed in claim 7 or 8 is lowered into place, pressure is applied to the drill pipe above the floating short joint, and the pressure is transmitted to the rupture disk through the central through hole of the retaining ring, and then to the sliding sleeve through the rupture disk, thereby shearing the shear pins. The rupture disk and the sliding sleeve move downward rapidly, and the rupture disk touches the striker, which smashes the rupture disk, and the rupture disk is broken into tiny particles. The tiny particles enter the central through hole of the striker mechanism from the gap between the strikers and are discharged, and then the tiny particles are discharged from the wellbore through circulation, so as to realize the full diameter of the liner; After the circulation is completed, the liner hanger is set and then the liner is cemented to form a cement ring.

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