Multi-sealing float collar

Abstract

The invention belongs to the technical field of oil and gas drilling, and particularly relates to a multi-sealing float collar which is characterized in that a rubber plug seat is coaxially arranged in a shell, a self-locking rubber plug is mounted in the rubber plug seat, a sealing ring is arranged in the middle of the self-locking rubber plug, a conical guide surface is arranged at one end of an L-shaped extension part on the rubber plug seat, a pressure relief cavity is formed in the inner side, and a variable-diameter plunger sealing part is arranged on the outer side; the variable-diameter plunger sealing part channel and the shell are eccentric; the variable-diameter plunger sealing part channel is coaxially provided with a first plunger sealing valve, and a sealing ring is arranged on a first plunger valve element; a mushroom sealing valve is arranged in a channel on the lower side of the variable-diameter plunger sealing part, the mushroom sealing valve and the shell are eccentrically arranged, the eccentric direction of the mushroom sealing valve is opposite to that of the first plunger sealing valve, a mushroom sealing valve seat is fixed to the side, consistent with the eccentric direction of the first plunger sealing valve, of the lower end of the rubber plug seat, and the bottom of a mushroom sealing valve rod is sleeved with a mushroom sealing valve basket. Through triple sealing and the pressure relief cavity, the sealing effect of the sealing structure is effectively improved, the back pressure resistance is improved, and cement backflow is effectively avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and natural gas drilling, and particularly relates to a multi-sealed floating collar. Background Art

[0002] Float collars are commonly used in cementing operations. They come in three configurations: spring-type, ball-type, and tongue-type. Spring-type float collars and float shoes are typically used in highly deviated and horizontal wells. Because their sealing hemispheres are often made of rubber, they offer high backpressure and temperature resistance. However, their fixed sealing surface is susceptible to damage from prolonged fluid erosion, and the springs are also prone to failure during this process, resulting in relatively low reliability. Ball-type float collars are typically used in vertical wells and those with low inclinations. They rely primarily on buoyancy and backflow to propel the float ball, resulting in a high setting success rate but limited backpressure resistance. Tongue-type float collars offer a simpler structure, a wider flow channel, and comparable backpressure and temperature resistance to spring-type ones. However, their reliance on a spring for return, single sealing surface, and direct fluid erosion make them less reliable than ball-type float collars. The backpressure resistance of a float collar and float shoe directly impacts cementing quality. Summary of the Invention

[0003] The present invention provides a multi-sealed floating collar to solve the problems in the prior art of the difficulty in floating collars, low anti-back pressure capability of floating shoes, and easy cement backflow blockage.

[0004] The present invention provides a multi-seal floating collar, the technical solution is: A multi-sealing floating collar comprises a shell, wherein a plug seat (3) is coaxially provided in the shell (1), a plug mounting hole is provided on the top of the plug seat (3), a self-locking plug (2) is installed in the plug mounting hole, a sealing ring (8) is provided in the middle (22) of the self-locking plug, an extension portion is connected to the inner wall of the plug seat (3), a conical guide surface is provided on the top of one end of the extension portion, the conical guide surface is used to cooperate with the bottom of the self-locking plug (2), one side of the extension portion is a pressure relief chamber (41), and the other side is a variable diameter plunger sealing portion (42); a first plunger sealing valve (5) is coaxially provided with a channel of the variable diameter plunger sealing portion (42), the first plunger sealing valve (5) comprises a first plunger valve core, a sealing ring (8) is provided on the first plunger valve core, the bottom of the first plunger valve core is connected to a first plunger sealing valve stem (52), the first plunger sealing valve stem ( The first plunger sealing valve stem (52) is sleeved on the first flower basket (53), and a spring (7) is sleeved on the first plunger sealing valve stem (52), and the top of the spring (7) sleeved on the first plunger sealing valve stem (52) contacts the first plunger valve core of the plunger and the bottom contacts the upper surface of the first flower basket (53); a second plunger sealing valve is provided in the lower channel of the reducing plunger sealing portion (42), and the second plunger sealing valve (6) includes a second plunger valve core (61) and a second plunger sealing valve seat (62), the second plunger valve core (61) is connected to the second plunger sealing valve stem (63), the bottom of the second plunger sealing valve stem (63) is sleeved on the second flower basket (64), and a spring (7) is sleeved on the second plunger sealing valve stem (63), and the top of the spring (7) sleeved on the second plunger sealing valve stem (63) contacts the second plunger valve core and the bottom contacts the upper surface of the second flower basket (64).

[0005] Furthermore, the extension portion is an L-shaped extension portion (4), one end of which is fixed to the inner wall of the housing (1); the inner side of the L-shaped extension portion (4) is a pressure relief chamber (41), and the outer side is an eccentric plunger sealing portion (42); the channel of the variable diameter plunger sealing portion (42) is eccentrically arranged with respect to the housing (1); the second plunger sealing valve is eccentric with respect to the housing (1) and the eccentric direction is opposite to that of the first plunger sealing valve (5); the second plunger sealing valve seat (62) is fixed on the side of the lower end of the rubber plug seat (3) that is consistent with the eccentric direction of the first plunger sealing valve (5).

[0006] Furthermore, the second plunger valve core is a mushroom-shaped valve core.

[0007] Furthermore, the cross-section of the second plunger sealing valve seat is a right-angled trapezoid, with the vertical waist side installed toward the outside, and the lowermost end of the other side of the lower end of the plug seat is provided with a conical surface corresponding to the inclined waist side of the second plunger sealing valve seat.

[0008] Furthermore, a back-stop groove is provided at the bottom of the self-locking rubber plug, a self-locking claw ring mounting groove is provided below the rubber plug mounting hole, a self-locking claw ring is provided inside the self-locking claw ring mounting groove, and a pressure relief chamber sliding sleeve is provided below the self-locking claw ring mounting groove.

[0009] Furthermore, the self-locking claw ring includes a claw finger and a claw ring spring. The claw finger is installed on the inner side of the mounting ring through a connecting shaft. The claw ring spring is used to pull the claw finger to rotate. Furthermore, matching threads are provided on the outer side of the mounting ring and the inner wall of the self-locking claw ring mounting groove, and the self-locking claw ring is screwed onto the self-locking claw ring mounting groove.

[0010] Furthermore, the upper part of the self-locking plug is a columnar structure as a whole, the middle part of the self-locking plug is a columnar structure with a reduced diameter, the lower part of the self-locking plug is hemispherical or semi-ellipsoidal, and a chamfer is provided at the connection between the middle wall of the self-locking plug and the sealing groove.

[0011] Furthermore, the sealing ring is arranged in the sealing groove, the sealing grooves on the middle part of the self-locking rubber plug are provided with two, and the sealing grooves on the first plunger valve core are provided with two.

[0012] Furthermore, the first plunger valve core is a trapezoidal valve core, and the top of the trapezoidal valve core has a trapezoidal guide surface inclined toward the center of the bottom of the shell. Beneficial effects

[0013] The triple seal formed by the self-locking rubber plug, the first plunger sealing valve, and the second plunger sealing valve enhances the sealing effect through multiple seals, effectively improving the resistance to back pressure and preventing cement backflow. In addition, by providing a pressure relief chamber, during cementing and well washing operations, cement is injected into the pressure relief chamber, creating a negative pressure in the channel of the reducing plunger seal and the channel below it. This effectively improves the sealing effect of the sealing structure under the influence of high external pressure, improves the resistance to back pressure, and effectively prevents cement backflow.

[0014] An L-shaped extension is provided to facilitate setting the first plunger sealing valve and the plug seat into an eccentric structure, and a pressure relief chamber can be formed on one side of the L-shaped extension. In addition, the first plunger sealing valve and the second plunger sealing valve are also eccentrically provided, which can effectively reduce the impact of the first plunger sealing valve seat, the first plunger sealing valve core, the second plunger sealing valve seat and the second plunger sealing valve core when the fluid flows downstream, thereby avoiding wear and damage to the components, and preventing the components from having uneven surfaces due to abrasion, thereby preventing a reduction in the sealing effect.

[0015] The second plunger valve core is a mushroom-shaped valve core. The top of the mushroom-shaped valve core is arc-shaped and has an arc-shaped guide surface. When the mushroom-shaped valve core returns under the action of the spring, it will be subjected to smaller top pressure and return to its position faster.

[0016] The second plunger sealing valve seat in the right-angle trapezoidal shape can better adapt to the shape of the mushroom-shaped valve core, making it easier for the mushroom-shaped valve core to rebound into the valve seat under the action of the spring to achieve sealing.

[0017] Through the cooperation of the anti-retraction groove and the self-locking claw ring, when the self-locking plug enters the plug seat, the self-locking claw ring automatically snaps into the anti-retraction groove to lock the self-locking plug in the plug seat. Even when the internal pressure of the shell changes, the self-locking plug will not fall out of the plug seat, thereby effectively improving the anti-back pressure ability and avoiding cement reflux.

[0018] By setting a claw finger rotatably mounted on the mounting ring and through the claw ring spring, when the self-locking rubber plug enters the self-locking claw ring, the claw finger can be pushed open, and when the self-locking rubber plug descends to the end of the claw finger and enters the anti-retraction groove, the claw ring spring controls the claw finger to open and snap into the anti-retraction groove, thereby reliably and easily locking the self-locking rubber plug in the rubber plug seat.

[0019] The self-locking claw ring is screwed onto the self-locking claw ring mounting groove through a threaded connection, which can improve the stability of the self-locking claw ring installation, prevent the self-locking claw ring from falling off, and improve the overall reliability of the equipment.

[0020] The spring sleeved on the second plunger sealing valve stem and the spring sleeved on the first plunger sealing valve stem, the first plunger sealing valve and the second plunger sealing valve are opened by the flow of cement or other fluid entering the shell, and after the shell is filled with fluid, the first plunger sealing valve and the second plunger sealing valve are conveniently automatically rebounded under the action of the spring, without the need to set up a complex mechanical structure to control the opening and closing of the valves, while ensuring the sealing effect, the overall structure of the floating collar is simplified.

[0021] The middle wall of the self-locking plug and the connection with the sealing groove are chamfered for transition, which facilitates the integral molding of the entire self-locking plug during processing. In addition, the self-locking plug is further locked by the cylindrical structure with reduced diameter in the middle part and the self-locking claw ring, thereby improving the anti-back pressure ability and avoiding cement reflux.

[0022] By providing a sealing groove and installing the sealing ring in the sealing groove, the sealing ring can be prevented from falling off and being damaged, thus improving the sealing reliability. The middle part of the self-locking rubber plug and the sealing groove on the middle part of the self-locking rubber plug are both provided with two sealing grooves, which can further improve the sealing effect, enhance the anti-back pressure capability and prevent cement backflow.

[0023] The first plunger valve core is a trapezoidal valve core with a trapezoidal guide surface, which can increase the flow area, reduce the flow rate, and reduce the impact on the valve core. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is an overall structural diagram of Example 1 provided by the present invention; Figure 2This is a schematic diagram of the first-level sealing structure of Example 1 provided by the present invention; Figure 3 Schematic diagram of the self-locking claw ring structure of Example 1 provided by the present invention; Figure 4 This is a schematic diagram of the self-locking claw ring in the open state of Example 1 provided by the present invention; Figure 5 This is a schematic diagram of the second-level sealing structure of Example 1 provided by the present invention; Figure 6 Schematic diagram of the third sealing structure of Example 1 provided by the present invention; 1. Housing; 2. Self-locking rubber plug; 21. Upper part of self-locking rubber plug; 22. Middle part of self-locking rubber plug; 23. Lower part of self-locking rubber plug; 3. Rubber plug seat; 31. Self-locking claw ring; 311. Claw finger; 312. Mounting ring; 32. Pressure relief chamber sleeve; 4. L-shaped extension; 41. Pressure relief chamber; 42. Variable diameter plunger sealing part; 5. First plunger sealing valve; 51. Trapezoidal valve core; 52. First plunger sealing valve stem; 6. Second plunger sealing valve; 61. Mushroom-shaped valve core; 62. Second plunger sealing valve seat; 63. Second plunger sealing valve stem; 7. Spring; 8. Sealing ring. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings.

[0026] Specific embodiment 1 of a multi-sealed floating collar provided by the present invention: The present invention is described by taking eccentric as an example, and is also applicable to concentric structures. Figure 1 As shown, it includes a housing 1, in which a step structure is provided. The inner diameter of the housing 1 at the upper end of the step structure is larger than the inner diameter of the housing 1 at the lower end. A plug seat 3 is coaxially provided in the housing 1, and the top of the plug seat 3 is flush with the step structure. The plug seat 3 is coaxially arranged with the housing 1. A plug mounting hole is provided at the top of the plug seat 3, in which a self-locking plug 2 is installed. The upper portion 21 of the self-locking plug is an overall columnar structure, and the middle portion 22 of the self-locking plug is a columnar structure with a reduced diameter. A sealing ring 8 is provided on the middle portion 22 of the self-locking plug, and the sealing ring 8 is installed in the sealing groove. In this embodiment, two sealing rings 8 are provided, and the sealing groove is correspondingly provided with two grooves. The connection between the wall surface of the middle portion 22 of the self-locking plug and the sealing groove is provided with a chamfer, and the lower portion 23 of the self-locking plug is provided with a back-stop groove. The lower portion 23 of the self-locking plug is hemispherical or hemi-ellipsoidal. In other embodiments, the connection between the wall surface of the middle portion of the self-locking plug and the sealing groove can be omitted.

[0027] like Figure 1 , Figure 2As shown, a self-locking claw ring 31 is also installed in the plug seat 3. The self-locking claw ring 31 is installed in the self-locking claw ring mounting groove below the plug mounting hole. The structure of the self-locking claw ring 31 is shown in Figure 3. The self-locking claw ring 31 includes a claw finger 311 and a claw ring spring. The claw finger 311 is installed on the inner side of the mounting ring 312 through a connecting shaft. The claw finger 311 is pulled by the claw ring spring to rotate and open the top. In this embodiment, there are two claw fingers 311, which are symmetrically arranged in the mounting ring 312. In other embodiments, there can be three, four or more claw fingers 311, which are evenly distributed on the inner side of the mounting ring 312. The specific number of claw fingers 311 is determined according to the size of the plug seat 3. Matching threads are provided on the outer side of the mounting ring 312 and the inner wall of the self-locking claw ring mounting groove, and the self-locking claw ring 31 is screwed onto the self-locking claw ring mounting groove. When the self-locking rubber plug 2 is installed into the rubber plug seat 3 and moves down to a certain position, the self-locking claw ring 31 enters the anti-retraction groove of the self-locking rubber plug 2, pushes the claw finger 311 downward, and blocks the anti-retraction groove to prevent the self-locking rubber plug 2 from floating up. The open state of the claw finger 311 is as shown in FIG. Figure 4 A pressure relief chamber sleeve is provided below the self-locking claw ring mounting groove.

[0028] In this example, an extension is connected to the inner wall of the plug seat 3. The top of one end of the extension is provided with a tapered guide surface, which is used to cooperate with the bottom of the self-locking plug 2. One side of the extension is a pressure relief chamber 41, and the other side is a reducing plunger sealing portion 42. In this embodiment, the extension is an L-shaped extension 4. One end of the L-shaped extension 4 is fixed to the inner wall of the plug seat 3, and the top of the other end is a tapered guide surface. The plug seat 3 is provided with an inclined surface structure at the bottom of the self-locking claw ring mounting groove on the outer wall of the L-shaped extension 4, which is consistent with the inclination direction and angle of the tapered guide surface. The inner side of the L-shaped extension 4 is the pressure relief chamber 41, and the outer side is the reducing plunger sealing portion 42. The channel of the reducing plunger sealing portion 42 is eccentrically arranged with respect to the housing 1.

[0029] like Figure 3 As shown, the multi-seal eccentric floating collar also includes a first plunger sealing valve 5, which is coaxially arranged with the passage of the variable-diameter plunger sealing portion 42. The first plunger sealing valve 5 comprises a first plunger valve core, which is provided with a sealing ring 8. The first plunger valve core is a trapezoidal valve core 51, with a trapezoidal guide surface at its top inclined toward the bottom center of the housing 1. The sealing ring 8 on the first plunger valve core is installed in a sealing groove. In this embodiment, two sealing rings 8 are provided on the first plunger valve core, corresponding to two sealing grooves. The bottom of the first plunger valve core is connected to a first plunger sealing valve stem 52, which is sleeved with a spring 7. The bottom of the first plunger sealing valve stem 52 is sleeved in a first basket. The top of the spring 7 on the first plunger sealing valve stem 52 contacts the first plunger valve core, and the bottom contacts the upper surface of the first basket 53, which is fixed to the housing 1.

[0030] like Figure 4As shown, a second plunger sealing valve 6 is disposed in the lower channel of the variable-diameter plunger sealing portion 42. The second plunger sealing valve 6 comprises a second plunger valve core and a second plunger sealing valve seat 62. The flat side of the second plunger valve core is connected to a second plunger sealing valve stem 63, which is also sleeved with a spring 7. The second plunger sealing valve seat 62 has a right-angled trapezoidal cross-section, with the vertical waist side facing outward. The axis of the second plunger sealing valve 6 is eccentrically disposed relative to the housing 1, and the eccentricity is opposite to that of the first plunger sealing valve 5. The second plunger sealing valve seat 62 is fixed to the side of the lower end of the plug holder 3 that is aligned with the eccentricity of the first plunger sealing valve 5. The lowermost end of the other side of the lower end of the plug holder 3 is provided with a tapered surface corresponding to the inclined waist side of the second plunger sealing valve seat 62. The bottom of the second plunger sealing valve stem 63 is sleeved in a second basket. The spring 7 sleeved on the second plunger sealing valve stem 63 contacts the second plunger valve core at its top and contacts the upper surface of the second basket 64 at its bottom, which is fixed to the housing 1. In this embodiment, the second plunger valve core is a mushroom-shaped valve core, the top of the mushroom-shaped valve core is arc-shaped and has an arc-shaped guide surface. When the mushroom-shaped valve core returns under the action of the spring 7, it will be subjected to smaller top pressure and return to its position faster.

[0031] During cementing and well-washing operations, the self-locking plug 2 and the plug seat 3 form the first seal of the multi-seal eccentric float collar. After cement is injected into the housing 1, the self-locking plug 2 is inserted, descends to the float collar, and then enters the plug seat 3. It continues to descend along the tapered guide surface within the plug seat 3 until it is stably installed on the plug seat 3. The two sealing rings 8 on the self-locking plug 2 form a seal with the inner wall of the plug seat 3. Furthermore, when the bottom end of the lower portion 23 of the self-locking plug contacts the tapered guide surface and is squeezed, the top of the retaining groove on the lower portion 23 of the self-locking plug passes the bottom of the self-locking claw ring 31. The claws of the self-locking claw ring 31 lose their radial support force and rebound, entering the retaining groove of the plug body, thereby forming a self-locking state between the self-locking plug 2 and the plug seat 3, ensuring the stability of the self-locking plug 2 and preventing it from floating upside down.

[0032] The first plunger sealing valve 5 is the second seal. When performing cementing and well washing operations, the self-locking plug 2 enters the plug seat 3, pushing the pressure relief chamber sleeve downward, and the descending cement pushes the trapezoidal valve core 51 downward, opening the channel at the variable diameter plunger sealing part 42, compressing the spring 7, and the liquid flow continues to descend along the trapezoidal surface of the trapezoidal valve core 51. After the cement is injected, the trapezoidal valve core 51 will return to the channel at the variable diameter plunger sealing part 42 under the rebound action of the spring 7, forming a second seal.

[0033] The second plunger sealing valve 6 provides the third seal. During cementing and well washing operations, the descending cement pushes the mushroom valve downward, opening the channel and compressing the spring 7 on the second plunger sealing valve stem 63, allowing liquid to flow out of the float collar. After cementing is completed, the spring 7 rebounds, causing the second plunger sealing valve 6 to return to the second plunger sealing valve seat 62, forming the third seal.

[0034] Moreover, when cement enters the pressure relief chamber 41, negative pressure can be formed in the channel of the variable diameter plunger sealing part 42 and the channel below it, thereby further improving the sealing ability of the self-locking rubber plug 2, the first plunger sealing valve 5 and the second plunger sealing valve with the help of external pressure.

[0035] Specific embodiment 2 of a multiple-seal floating collar provided by the present invention: The only difference between this embodiment and Example 1 is that, in this embodiment, the extension portion is a tubular structure having an inner diameter smaller than that of the plug seat. The outer side of the bottom of the extension portion is fixedly connected to the inner wall of the plug seat via an annular connecting plate. The inner side of the tubular extension portion is a variable diameter plunger seal portion, and the outer side is a bottom-enclosed pressure relief chamber. The first plunger sealing valve, the second plunger sealing valve, and the variable diameter plunger seal are all coaxially arranged. In other embodiments, the first plunger sealing valve and the variable diameter plunger seal can also be coaxially arranged, while the first and second plunger sealing valves can be eccentric.

[0036] Specific embodiment 2 of a multiple-seal floating collar provided by the present invention: The only difference between this embodiment and embodiment 1 is that in this embodiment, the second plunger valve core is a rectangular valve core, and the first plunger valve core is also a rectangular valve core.

[0037] Specific embodiment 3 of a multi-seal floating collar provided by the present invention: The only difference between this embodiment and embodiment 1 is that, in this embodiment, no threads are provided on the outer side of the mounting ring of the self-locking claw ring and the inner wall of the self-locking claw ring mounting groove, and the self-locking claw ring is rigidly mounted and clamped on the self-locking claw ring mounting groove.

[0038] Specific embodiment 4 of a multi-seal floating collar provided by the present invention: The only difference between this embodiment and embodiment 1 is that, in this embodiment, one sealing ring is provided on the middle portion of the self-locking rubber plug, corresponding to one sealing groove, and one sealing ring is provided on the first plunger valve core, corresponding to one sealing groove. In other embodiments, three, four, five, or more sealing rings may be provided on the middle portion of the self-locking rubber plug and the first plunger valve core. The specific number of sealing rings provided is determined by the dimensions of the self-locking rubber plug and the first plunger valve core.

Claims

1. A multi-seal floating collar, characterized in that: The invention comprises a housing (1), wherein a plug seat (3) is coaxially provided in the housing (1), a plug mounting hole is provided on the top of the plug seat (3), a self-locking plug (2) is installed in the plug mounting hole, a sealing ring (8) is provided in the middle (22) of the self-locking plug, an extension portion is connected to the inner wall of the plug seat (3), a conical guide surface is provided on the top of one end of the extension portion, the conical guide surface is used to cooperate with the bottom of the self-locking plug (2), one side of the extension portion is a pressure relief chamber (41), and the other side is a variable diameter plunger sealing portion (42); a first plunger sealing valve (5) is coaxially provided with the channel of the variable diameter plunger sealing portion (42), the first plunger sealing valve (5) comprises a first plunger valve core, a sealing ring (8) is provided on the first plunger valve core, the bottom of the first plunger valve core is connected to a first plunger sealing valve stem (52), and the first plunger sealing valve stem (52) The bottom is sleeved in the first flower basket (53), the first plunger sealing valve stem (52) is sleeved with a spring (7), and the top of the spring (7) sleeved on the first plunger sealing valve stem (52) contacts the first plunger valve core of the plunger and the bottom contacts the upper surface of the first flower basket (53); a second plunger sealing valve is provided in the lower channel of the variable diameter plunger sealing portion (42), the second plunger sealing valve (6) comprises a second plunger valve core (61) and a second plunger sealing valve seat (62), the second plunger valve core (61) is connected to the second plunger sealing valve stem (63), the bottom of the second plunger sealing valve stem (63) is sleeved in the second flower basket (64), the second plunger sealing valve stem (63) is sleeved with a spring (7), the top of the spring (7) sleeved on the second plunger sealing valve stem (63) contacts the second plunger valve core and the bottom contacts the upper surface of the second flower basket (64).

2. A multi-seal floating collar according to claim 1, characterized in that: The extension portion is an L-shaped extension portion (4), one end of which is fixed to the inner wall of the housing (1); the inner side of the L-shaped extension portion (4) is a pressure relief chamber (41), and the outer side is an eccentric plunger sealing portion (42); the channel of the variable diameter plunger sealing portion (42) is eccentrically arranged with respect to the housing (1); the second plunger sealing valve is eccentric with respect to the housing (1), and the eccentric direction is opposite to that of the first plunger sealing valve (5); the second plunger sealing valve seat (62) is fixed on the side of the lower end of the rubber plug seat (3) that is consistent with the eccentric direction of the first plunger sealing valve (5).

3. The multi-seal floating collar according to claim 1, characterized in that: The second plunger valve core (61) is a mushroom-shaped valve core.

4. A multi-seal floating collar according to claim 3, characterized in that: The cross section of the second plunger sealing valve seat (62) is a right-angled trapezoid, with the vertical waist side being installed toward the outside, and the lowermost end of the other side of the lower end of the rubber plug seat (3) is provided with a conical surface corresponding to the inclined waist side of the second plunger sealing valve seat (62).

5. The multi-seal floating collar according to claim 1, characterized in that: The lower portion (23) of the self-locking rubber plug is provided with a stop groove, a self-locking claw ring installation groove is provided below the rubber plug installation hole, a self-locking claw ring (31) is provided inside the self-locking claw ring installation groove, and a pressure relief chamber sliding sleeve is provided below the self-locking claw ring installation groove.

6. The multi-seal floating collar according to claim 5, characterized in that: The self-locking claw ring (31) includes a claw finger (311) and a claw ring spring. The claw finger (311) is installed on the inner side of the mounting ring (312) via a connecting shaft. The claw ring spring is used to pull the claw finger (311) to rotate. The multi-sealed floating collar according to claim 6 is characterized in that matching threads are provided on the outer side of the mounting ring (312) and the inner wall of the self-locking claw ring mounting groove, and the self-locking claw ring (31) is screwed onto the self-locking claw ring mounting groove.

7. The multi-seal floating collar according to claim 1, characterized in that: The upper portion (21) of the self-locking rubber plug is a columnar structure as a whole, the middle portion (22) of the self-locking rubber plug is a columnar structure with a reduced diameter, the lower portion (23) of the self-locking rubber plug is hemispherical or hemi-ellipsoidal, and a chamfer is provided at the connection between the wall surface of the middle portion (22) of the self-locking rubber plug and the sealing groove.

8. The multi-seal floating collar according to claim 1, characterized in that: The sealing ring (8) is arranged in a sealing groove, two sealing grooves are provided on the middle portion (22) of the self-locking rubber plug, and two sealing grooves are provided on the first plunger valve core.

9. The multi-seal floating collar according to claim 1, characterized in that: The first plunger valve core is a trapezoidal valve core (51), and the top of the trapezoidal valve core (51) has a trapezoidal guide surface inclined toward the bottom center of the housing (1).

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