Sealing assembly for drilling liner hanger and drilling liner hanger

Abstract

The invention discloses a sealing assembly for a drilling liner hanger and the drilling liner hanger. The sealing assembly comprises a barrel-shaped body, a sealing ring and a sealing ring, an inner sealing group and an outer sealing group; the cylindrical core shaft coaxially extends into the body from the lower part of the body, the core shaft is in sliding connection with the body and can slide upwards from a first position to a second position, and the outer wall of the core shaft is provided with a convex part and a concave part; the limiting parts are arranged outside the mandrel in the circumferential direction, each limiting part is provided with a limiting main body and a clamping hook, the clamping hooks are connected to the body in a hooked mode and located between the mandrel and the body, the limiting main bodies are located below the body, and the limiting parts can move in the radial direction relative to the body so that the limiting main bodies can be in an extending state or a retracting state; when the mandrel is located at the first position, the convex part is jointed with the joint surface of the limiting part, and the limiting main body is in an extending state; and when the mandrel is located at the second position, the concave part is matched with the joint surface, and the limiting main body is allowed to be in a retracted state. The problem that the central pipe is damaged or stuck can be solved, and the sealing performance can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of downhole liner cementing of oil and gas wells, and in particular to a sealing assembly for a liner hanger and a liner hanger. Background Art

[0002] The ratchet type and the block type are the two most commonly used sealing system structures for full-bore liner hangers. During the liner cementing process, the liner hanger often gets stuck in the center tube due to the retraction of the lock block or the untimely contraction of the claw sleeve, making it impossible to release the hand, resulting in serious accidents such as inserting a flagpole. The claws of the ratchet-type sealing system are always in an expanded state inside the liner hanger, which is prone to plastic deformation and difficult to retract, which may eventually cause the center tube to get stuck; and when the center tube is lifted up and lowered, the claw structure is also prone to deformation, resulting in sealing failure. The lock block part of the lock block sealing system is often prone to jamming the center tube due to processing accuracy or inability to retract, resulting in the center tube being unable to be lifted out, thus causing downhole accidents. Summary of the invention

[0003] The main purpose of the present invention is to provide a sealing assembly for a liner hanger and a liner hanger, so as to at least solve the problem that the current ratchet type and block type sealing systems easily damage the center tube of the hanger or cause the center tube to get stuck.

[0004] According to one aspect of the present invention, a sealing assembly for a liner hanger is provided, comprising:

[0005] cylindrical body;

[0006] The inner sealing group and the outer sealing group are respectively arranged on the inner wall and the outer wall of the body;

[0007] A cylindrical mandrel coaxially extends from the lower part of the body into the body, the mandrel is slidably connected to the body and can slide upward from a first position to a second position relative to the body, and an outer wall of the mandrel has convex portions and concave portions distributed along the axial direction;

[0008] A plurality of limiting parts are arranged outside the core shaft along the circumferential direction, the limiting parts have a limiting body and a hook extending from the limiting body, the hook is hooked to the body and located between the core shaft and the body, the limiting body is located below the body, and the limiting parts can move radially relative to the body to make the limiting body in an extended state or a retracted state;

[0009] When the mandrel is in the first position, the convex portion engages with the engagement surface of the limiting portion, and the limiting body is in an extended state; when the mandrel is in the second position, the concave portion cooperates with the engagement surface, allowing the limiting body to be in a retracted state.

[0010] According to one embodiment of the present invention, the body has a plurality of guide portions distributed along the circumferential direction, the guide portions extend radially and protrude from the inner wall of the body, and the core shaft has a plurality of track grooves distributed along the circumferential direction and extending axially, the track grooves cooperate with the guide portions.

[0011] According to one embodiment of the present invention, a matching groove with an inverted L-shaped cross-section is provided at the lower portion of the inner wall of the main body, and the hook of the limiting portion matches with the matching groove.

[0012] According to one embodiment of the present invention, the outer wall of the core shaft has two protrusions and two recesses distributed along the axial direction, and the limiting portion has two engaging surfaces and a groove located between the two engaging surfaces; when the core shaft is in the first position, the two protrusions engage with the two engaging surfaces; when the core shaft is in the second position, the two recesses cooperate with the two engaging surfaces, and the protrusion located at the bottom of the two protrusions cooperates with the groove.

[0013] According to one embodiment of the present invention, the core shaft has a flange located below the limiting portion, and the sealing assembly also includes a return spring sleeved outside the core shaft and arranged between the limiting portion and the flange. When the core shaft is in the second position, the return spring is in a compressed state.

[0014] According to one embodiment of the present invention, the protrusion and the limiting portion have chamfered surfaces that cooperate with each other and are used to guide the core shaft to slide downward; and / or the outer wall of the limiting body forms a chamfered surface.

[0015] According to an embodiment of the present invention, the inner wall of the body has an abutment portion, and when the core shaft is in the second position, the upper portion of the core shaft abuts against the abutment portion.

[0016] According to one embodiment of the present invention, the inner sealing group and / or the outer sealing group includes a first outer ring, one or more reverse V-shaped sealing rings, an O-shaped sealing ring, one or more forward V-shaped sealing rings, and a second outer ring, which are arranged in sequence from top to bottom; preferably, the material of the first outer ring and the second outer ring is polytetrafluoroethylene, and the material of the reverse V-shaped sealing ring, the O-shaped sealing ring and the forward V-shaped sealing ring is rubber.

[0017] According to one embodiment of the present invention, the inner wall and the outer wall of the body have an annular receiving groove, and the inner sealing group and the outer sealing group are respectively arranged in the corresponding receiving grooves.

[0018] According to another aspect of the present invention, a tail pipe hanger is proposed, comprising: a cylindrical hanger body, a center tube arranged in the hanger body, and a sealing assembly as described above, wherein the sealing assembly is arranged between the hanger body and the center tube, and the center tube can drive the core shaft to slide upward from a first position to a second position; when the core shaft is in the first position, the limit body is in an extended state and is clamped in a slot of the hanger body; when the core shaft is in the second position, the limit body is in a retracted state and is disengaged from the slot.

[0019] In the technical solution of the present invention, the core shaft can slide relative to the body so that the convex part or concave part on the core shaft cooperates with the same joint surface of the limiting part, so that the limiting part can move radially to make the limiting body in an extended state or a retracted state. When the limiting body is in an extended state, it can be snapped into the slot of the hanger body to achieve the limiting of the sealing assembly. When the limiting body is in a retracted state, it can be disengaged from the slot of the hanger body to achieve the release of the sealing assembly, which is convenient for the center pipe to take the sealing assembly away from the hanger body. In the present invention, the limiting part is arranged outside the core shaft and is not in direct contact with the center pipe, which can avoid damage to the center pipe or jamming of the center pipe during the extension and retraction of the limiting part, thereby ensuring the smooth progress of the tail pipe cementing operation. The present invention also achieves better sealing performance by improving the structure of the inner sealing group and the outer sealing group. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic structural diagram of a liner hanger according to an embodiment of the present invention is shown;

[0022] Figure 2 A schematic structural diagram of a sealing assembly according to an embodiment of the present invention is shown, wherein the limiting body is in a retracted state;

[0023] Figure 3 A schematic structural diagram of a sealing assembly according to an embodiment of the present invention is shown, wherein the limiting body is in an extended state;

[0024] Figure 4 A schematic structural diagram of a mandrel according to an embodiment of the present invention is shown;

[0025] Figure 5 A schematic structural diagram of a position limiting portion according to an embodiment of the present invention is shown;

[0026] Figure 6 A schematic diagram showing an inner seal group and an outer seal group according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0028] It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are for distinguishing two non-identical entities with the same name or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. The subsequent embodiments will not explain this one by one.

[0029] As mentioned in the background technology above, the inventors of the present application recognize that the existing ratchet-type and block-type sealing systems are prone to central tube damage or jamming, which affects the liner cementing operation. In addition, the applicant further recognizes that in ultra-deep wells, the conventional sealing system of the liner hanger cannot withstand high temperature and high pressure due to high bottom hole temperature and high pressure, resulting in failure, which ultimately causes malicious events such as liner cementing short circuit. Based on the above recognition, the present application proposes one or more embodiments to be described below to solve the above problems.

[0030] refer to Figure 1 The liner hanger 200 includes: a running tool 210, a cylindrical hanger body 220, and a sealing assembly 100. The running tool 210 includes a center tube 212 and a lifting nipple 214, a sand cap 216, a release system 218 and other structures arranged on the center tube 212. The hanger body 220 includes a sitting system 222, a hydraulic system 224, a lower joint 226 and other structures. The center tube 212 coaxially extends into the hanger body 220, and the sealing assembly 100 is arranged between the center tube 212 and the hanger body 220 to achieve a seal therebetween. When the liner hanger 200 enters the well and completes the operation, the hanger body 220 remains in the well, and the running tool 210 and the sealing assembly 100 can be taken out of the well for subsequent reuse. The central tube 212 has a step portion, and when the central tube 212 is lifted, the step portion engages with the sealing assembly 100, thereby carrying the sealing assembly 100 upward to leave the wellbore. The sealing assembly 100 has the function of being able to limit the position on the hanger body 220 and the function of being able to release the limit from the hanger body 220 (so as to leave with the central tube 212).

[0031] Combination Figures 2 to 5The present invention provides a sealing assembly 100 for a tail pipe hanger, comprising: a cylindrical body 10; an inner sealing group 20 and an outer sealing group 22, which are respectively arranged on the inner wall and the outer wall of the body 10; a cylindrical core shaft 30, the core shaft 30 coaxially extends into the body 10 from the lower part of the body 10, the core shaft 30 is slidably connected with the body 10 and can slide upward from a first position to a second position relative to the body 10, and the outer wall of the core shaft 30 has a convex portion 32 and a concave portion 34 distributed in the axial direction; a plurality of limiting portions 40 are circumferentially arranged outside the core shaft 30, the limiting portion 40 has a limiting body 42 and a hook 44 extending from the limiting body 42, the hook 44 is hooked to the body 10 and is located between the core shaft 30 and the body 10, the limiting body 42 is located below the body 10, and the limiting portion 40 can move radially relative to the body 10 to make the limiting body 42 in an extended state or a retracted state; when the core shaft 30 is in the first position (such as Figure 3 As shown), the convex portion 32 engages with the engagement surface 46 of the limiting portion 40, and the limiting body 42 is in an extended state; when the mandrel 30 is in the second position (as shown Figure 2 As shown in FIG. 1 , the recess 34 cooperates with the engagement surface 46 to allow the limiting body 42 to be in a retracted state.

[0032] In the embodiment of the present invention, the inner seal group 20 is used to achieve the seal between the seal assembly 100 and the center tube 212, and the outer seal group 22 is used to achieve the seal between the seal assembly 100 and the hanger body 220, so that the seal between the center tube 212 and the hanger body 220 is achieved through the seal assembly 100. The inner seal group 20 and the outer seal group 22 can be arranged in the middle and upper part of the body 10, so as to avoid mutual interference with the core shaft 30 and the limit part 40 arranged in the middle and lower part and below the body 10.

[0033] The hook 44 of the limiting part 40 extends upward between the body 10 and the mandrel 30 and is hooked and matched with the lower part of the body 10 to achieve axial fixation of the limiting part 40 and allow the hook 44 to move radially. The limiting body 42 of the limiting part 40 is located below the body 10 and outside the mandrel 30, and is not blocked, so that it is convenient to cooperate with the slot on the hanger body 220 in the extended state, and it can also avoid being stuck due to excessive restrictions during the extension and retraction process. The limiting part 40 is arranged outside the mandrel 30 and does not directly contact the central tube, which can avoid damage to the central tube or cause the central tube to get stuck during the extension and retraction process. When the limiting body 42 is in the extended state, it protrudes outward relative to the outer wall of the body 10. When the limiting body 42 is in the retracted state, it can be flush with the outer wall of the body 10 or retracted inward relative to the outer wall of the body 10. The inner and outer surfaces of the limiting part 40 can be curved surfaces to match the shapes of the inner wall of the hanger body 220 and the outer wall of the mandrel 30. The plurality of stoppers 40 are evenly distributed along the circumference and symmetrically distributed along the radial direction, providing a stable and uniform stop effect. The convex portion 32 and the concave portion 34 on the mandrel 30 can both be annular, which is convenient for cooperation with the plurality of stoppers 40 distributed along the circumference and is also convenient for molding and manufacturing.

[0034] When the mandrel 30 is in the first position, the protrusion 32 on the mandrel 30 engages with the engagement surface 46 of the stopper 40, and the stopper body 42 is in an extended state, and can cooperate with the slot of the hanger body 220 to achieve the limit of the sealing assembly 100. When the center tube 212 is lifted, it drives the mandrel 30 to slide upward from the first position to the second position. In this process, the concave portion 34 on the mandrel 30 is transformed into being opposite to the engagement surface 46 of the stopper 40, thereby forming a gap between the concave portion 34 and the engagement surface 46, allowing the stopper body 42 to retract. At the same time, the slot wall of the hanger body 220 will apply a radial thrust to the stopper body 42. Under the action of the thrust, the stopper body 42 is retracted, thereby releasing the limit of the sealing assembly 100, so that it can be lifted out of the hanger body 220 along with the center tube 212.

[0035] In some embodiments, the body 10 has a plurality of guide portions 12 distributed along the circumferential direction, the guide portions 12 extend radially and protrude from the inner wall of the body 10, the mandrel 30 has a plurality of track grooves 36 distributed along the circumferential direction and extending axially, the track grooves 36 cooperate with the guide portions 12, thereby realizing a sliding connection between the mandrel 30 and the body 10, ensuring the circumferential consistency of the body 10 and the mandrel 30, and only relative movement occurs in the axial track grooves 36. The guide portion 12 may be a guide pin mounted to the body 10. In this way, a sliding connection between the mandrel 30 and the body 10 can be realized with a simple structure. When the body 10 is in the first position, the guide portion 12 cooperates with the upper limit position of the track groove 36, and the body 10 can no longer slide downward; when the body 10 is in the second position, the guide portion 12 cooperates with the lower limit position of the track groove 36, and the body 10 can no longer slide upward.

[0036] In some embodiments, the lower portion of the inner wall of the body 10 is provided with a matching groove 14 having an inverted L-shaped cross section, and the hook 44 of the limiting portion 40 is also inverted L-shaped, and the hook 44 cooperates with the matching groove 14. After the inverted L-shaped matching groove 14 is formed, the remaining structure of the lower portion of the body 10 is roughly an L-shaped hook-shaped portion, so as to be hooked with the inverted L-shaped hook 44. The matching groove 14 can be an integral annular groove, and the hooks 44 of the multiple limiting portions 40 are matched to different positions of the matching groove 14 along the circumferential direction. Alternatively, there can be multiple matching grooves 14, which are spaced apart along the circumferential direction.

[0037] In some embodiments, the outer wall of the mandrel 30 has two protrusions 32 and two recesses 34 distributed along the axial direction, and the limiting portion 40 has two engaging surfaces 46 and a groove 48 located between the two engaging surfaces 46; when the mandrel 30 is in the first position, the two protrusions 32 engage with the two engaging surfaces 46; when the mandrel 30 is in the second position, the two recesses 34 cooperate with the two engaging surfaces 46, and the protrusion 32 located at the lower side of the two protrusions 32 cooperates with the groove 48. By forming a plurality of protrusions 32 and recesses 34, the limiting portion 40 can be more reliably pushed to move outward so that the limiting body 42 has a more stable extended state. The two protrusions 32 can be used to cooperate with the engaging surfaces on the hook 44 and the limiting body 42, respectively.

[0038] In some embodiments, the mandrel 30 has a flange 38 located below the limiting portion 40, and the sealing assembly 100 further includes a return spring 50 sleeved outside the mandrel 30 and disposed between the limiting portion 40 and the flange 38. When the mandrel 30 is in the second position, the return spring 50 is in a compressed state, and when the sealing assembly 100 is lifted out, under the action of the restoring force of the return spring 50, the mandrel 30 slides downward from the second position relative to the body 10 and returns to the first position, so that the sealing assembly 100 can be limited again, and the sealing assembly 100 can be easily reused.

[0039] In some embodiments, the convex portion 32 and the limiting portion 40 have chamfered surfaces 31 and 41 that cooperate with each other and are used to guide the sliding. Through the cooperation of the chamfered surface 31 and the chamfered surface 41, it can be ensured that the mandrel 30 slides smoothly downward from the second position to the first position to restore the extended state of the limiting body 42. In some embodiments, the outer wall of the limiting body 42 forms a chamfered surface 43, which is conducive to ensuring that the limiting body 42 is smoothly separated from the card slot of the hanger body 220.

[0040] In some embodiments, the inner wall of the body 10 has an abutment portion 16 , and when the mandrel 30 is in the second position, the upper portion of the mandrel 30 abuts against the abutment portion 16 , thereby further limiting the movement of the mandrel 30 .

[0041] refer to Figure 6 In some embodiments, the inner seal group 20 and / or the outer seal group 22 include a first outer ring 21, one or more reverse V-shaped seal rings 23, an O-shaped seal ring 25, one or more forward V-shaped seal rings 27, and a second outer ring 29, which are arranged from top to bottom. Through such an arrangement, a good bidirectional sealing effect can be achieved, thereby improving the sealing performance, and being able to improve the resistance to high temperature, high pressure, and wear and impact. The first outer ring 21 and the second outer ring 29 can have good mechanical properties, thereby playing the role of external support and protection. Preferably, the material of the first outer ring 21 and the second outer ring 29 is polytetrafluoroethylene, and the material of the reverse V-shaped seal ring 23, the O-shaped seal ring 25, and the forward V-shaped seal ring 27 is rubber. The first outer ring 21, the reverse V-shaped seal ring 23, the O-shaped seal ring 25, the forward V-shaped seal ring 27, and the second outer ring 29 can all be made of high temperature and high pressure resistant materials to avoid failure under high temperature and high pressure conditions underground. The sealing assembly 100 of the present invention can be applied to high temperatures greater than or equal to 220°C and high pressure conditions greater than or equal to 70MPa, for example. The side of the first outer ring 21 that engages with the reverse V-shaped seal ring 23 has a V-shaped groove, which facilitates the tight engagement between the first outer ring 21 and the reverse V-shaped seal ring 23. The side of the first outer ring 21 that faces away from the reverse V-shaped seal ring 23 is a plane, which facilitates tight engagement with an external mounting plane. The second outer ring 29 is similar. Multiple reverse V-shaped seal rings 23 and multiple forward V-shaped seal rings 27 are stacked and arranged.

[0042] In some embodiments, the inner wall and the outer wall of the body 10 have an annular receiving groove, and the inner seal group 20 and the outer seal group 22 are respectively disposed in the corresponding receiving grooves and can abut between the upper and lower groove walls of the receiving groove. In some embodiments, the sealing assembly 100 further includes a stop ring 60, which is disposed on the upper part of the body 10 and can constitute the upper groove wall of the receiving groove. The body 10 has a step structure, and the stop ring 60 is sealingly mounted to the step structure.

[0043] The present invention also proposes a tail pipe hanger 200, comprising: a cylindrical hanger body 220, a center tube 212 arranged in the hanger body 220, and a sealing assembly 100 as described above, wherein the sealing assembly 100 is arranged between the hanger body 220 and the center tube 212, and the center tube 212 can drive the core shaft 30 to slide upward from the first position to the second position; when the core shaft 30 is in the first position, the limiting body 42 is in an extended state and is clamped in the slot of the hanger body 220; when the core shaft 30 is in the second position, the limiting body 42 is in a retracted state and is disengaged from the slot.

[0044] In summary, the present invention provides a movable block type sealing system. In the technical solution of the present invention, the body is slidably connected with the mandrel, and the mandrel can slide up and down axially relative to the body; the tail of the body is connected with a plurality of circumferentially distributed petal limit blocks by a hook connection structure, the petal limit blocks are controlled by the body, axially fixed, and can move radially with the axial movement of the concave or convex part of the mandrel, so that its outer diameter increases or shrinks; a spring wound around the tail of the mandrel is installed below the petal limit block; the contraction and expansion of the petal limit block are controlled by the mandrel, which plays the role of limiting and releasing the limit of the sealing system. Since the petal limit block does not directly contact the center tube of the hanger, the accident of damaging the center tube of the hanger or jamming the center tube during its contraction and expansion is avoided. The present invention also designs an improved sealing group structure to improve the sealing performance under high temperature and high pressure. In general, the movable block type sealing system of the present invention can effectively ensure the sealing performance of the tail tube hanger under high temperature and high pressure downhole conditions during the tail tube cementing construction process, and can avoid damage or jamming of the center tube, so as to achieve smooth release.

[0045] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the embodiments of the present invention as described above, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A sealing assembly for a liner hanger, It is characterized in that include: cylindrical body; An inner sealing group and an outer sealing group are respectively arranged on the inner wall and the outer wall of the body; A cylindrical mandrel, the mandrel coaxially extending from the lower part of the body into the body, the mandrel being slidably connected to the body and being able to slide upward from a first position to a second position relative to the body, the outer wall of the mandrel having convex portions and concave portions distributed along the axial direction; A plurality of limiting parts are arranged outside the core shaft along the circumferential direction, the limiting parts have a limiting body and a hook extending from the limiting body, the hook is hooked to the body and located between the core shaft and the body, the limiting body is located below the body, and the limiting parts can move radially relative to the body to make the limiting body in an extended state or a retracted state; When the core shaft is in the first position, the protrusion engages with the engagement surface of the limiting portion, and the limiting body is in an extended state; when the core shaft is in the second position, the recess cooperates with the engagement surface, allowing the limiting body to be in a retracted state.

2. The sealing assembly according to claim 1, It is characterized in that The body has a plurality of guide parts distributed along the circumferential direction, the guide parts extend radially and protrude from the inner wall of the body, and the core shaft has a plurality of track grooves distributed along the circumferential direction and extending axially, the track grooves cooperate with the guide parts.

3. The sealing assembly according to claim 1, It is characterized in that A matching groove with an inverted L-shaped cross section is provided at the lower portion of the inner wall of the main body, and the hook of the limiting portion matches with the matching groove.

4. The sealing assembly according to claim 1, It is characterized in that The outer wall of the core shaft has two protrusions and two recesses distributed along the axial direction, and the limiting portion has two engaging surfaces and a groove located between the two engaging surfaces; when the core shaft is in the first position, the two protrusions engage with the two engaging surfaces; when the core shaft is in the second position, the two recesses cooperate with the two engaging surfaces, and the protrusion located at the bottom of the two protrusions cooperates with the groove.

5. The sealing assembly according to claim 1, It is characterized in that The core shaft has a flange located below the limiting portion, and the sealing assembly also includes a return spring sleeved outside the core shaft and arranged between the limiting portion and the flange. When the core shaft is in the second position, the return spring is in a compressed state.

6. The sealing assembly according to claim 1, It is characterized in that The convex portion and the limiting portion have chamfered surfaces that cooperate with each other and are used to guide the core shaft to slide downward; and / or the outer wall of the limiting body forms a chamfered surface.

7. The sealing assembly according to claim 1, It is characterized in that The inner wall of the body has an abutment portion, and when the core shaft is in the second position, the upper portion of the core shaft abuts against the abutment portion.

8. The sealing assembly according to claim 1, It is characterized in that The inner sealing group and / or the outer sealing group include a first outer ring, one or more reverse V-shaped sealing rings, an O-shaped sealing ring, one or more forward V-shaped sealing rings, and a second outer ring, which are arranged in sequence from top to bottom; preferably, the material of the first outer ring and the second outer ring is polytetrafluoroethylene, and the material of the reverse V-shaped sealing ring, the O-shaped sealing ring and the forward V-shaped sealing ring is rubber.

9. The sealing assembly according to claim 8, It is characterized in that The inner wall and the outer wall of the body are provided with an annular receiving groove, and the inner sealing group and the outer sealing group are respectively arranged in the corresponding receiving grooves.

10. A tail pipe hanger, It is characterized in that include: A cylindrical hanger body, a center tube arranged in the hanger body, and a sealing assembly as described in any one of claims 1 to 9, wherein the sealing assembly is arranged between the hanger body and the center tube, and the center tube can drive the core shaft to slide upward from the first position to the second position; when the core shaft is in the first position, the limiting body is in an extended state and is clamped in the slot of the hanger body; when the core shaft is in the second position, the limiting body is in a retracted state and is disengaged from the slot.

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