Hanger unit, cementing tool comprising same and method of use thereof

Abstract

The present application relates to a hanger unit, a cementing tool comprising the same and a method of use thereof. The hanger unit comprises: a longitudinally extending cylindrical body; a slip support assembly sleeved outside the cylindrical body, a hydraulic chamber being formed between the slip support assembly and the cylindrical body, the slip support assembly and the cylindrical body being connected by a first shear pin; and a piston sleeve sealingly sleeved between the cylindrical body and the slip support assembly and located in the hydraulic chamber, the piston sleeve being configured to slide longitudinally in the hydraulic chamber, the piston sleeve dividing the hydraulic chamber into an upper hydraulic chamber and a lower hydraulic chamber; wherein in a first state, the piston sleeve is fixed in the hydraulic chamber and transmits a longitudinal force between the cylindrical body and the slip support assembly to avoid the first shear pin being sheared; and wherein in a second state, the piston sleeve moves longitudinally to no longer transmit the longitudinal force between the cylindrical body and the slip support assembly to allow the first shear pin to be sheared. Thus, the hanger unit can be prevented from being prematurely set on the well wall due to scratching.

Description

Technical Field

[0001] This invention relates to the field of tailpipe cementing technology, and more particularly to a hanger unit. The invention also relates to a cementing tool incorporating the hanger unit. Furthermore, the invention relates to a method of using the hanger unit. Background Technology

[0002] In oil and gas well cementing operations within the petroleum engineering industry, with the continuous deepening of oil and gas exploration and development, tailpipe hangers have become one of the essential downhole tools. Tailpipe hangers are used to guide the tailpipe to the designed position to complete tailpipe suspension and cementing operations. Based on different mounting methods, they can be divided into three types: mechanical, hydraulic, and hydraulic-mechanical dual-acting, with hydraulic tailpipe hangers being the most widely used. However, hydraulic tailpipe hangers carry the risk of premature mounting during the lowering process.

[0003] Currently, several tailpipe hangers exist to prevent premature seating. However, these hangers are generally designed to prevent premature seating caused by unstable pressure within the tube. For example, CN112227994A describes a tailpipe hanger for preventing premature seating. This hanger includes a suspension mechanism and a return cylinder connected above the suspension mechanism. A seating drive mechanism is connected within the return cylinder. The seating drive mechanism drives the return cylinder downwards to engage the suspension mechanism. This tailpipe hanger prevents premature seating caused by unstable pressure within the tailpipe by maintaining pressure balance in the two hydraulic chambers of the hydraulic cylinder of the seating drive mechanism.

[0004] During the lowering of the tailpipe into the well, the slips or related structures of the tailpipe hanger may scrape against the wellbore. This can lead to premature settling. Currently, a centralizer is typically used to prevent the slips or related structures from contacting the wellbore. However, if the slips or related structures scrape against the wellbore and the shear force exceeds the shear force that the hydraulic cylinder shear pins can withstand, premature settling can easily occur. Summary of the Invention

[0005] This invention provides a hanger unit that can be used to solve at least one of the aforementioned problems. This invention also provides a cementing tool incorporating the hanger unit. Furthermore, this invention provides a method of using the hanger unit.

[0006] According to a first aspect of the present invention, a suspension unit is provided, comprising: a cylindrical body extending longitudinally; a slip support assembly sleeved on the cylindrical body, forming a hydraulic cavity between the slip support assembly and the cylindrical body, the slip support assembly and the cylindrical body being connected by a first shear pin; and a piston sleeve sealed between the cylindrical body and the slip support assembly and located within the hydraulic cavity, the piston sleeve being configured to slide longitudinally within the hydraulic cavity, the piston sleeve dividing the hydraulic cavity into an upper hydraulic cavity and a lower hydraulic cavity; wherein, in a first state, the piston sleeve is fixed within the hydraulic cavity and transmits a longitudinal force between the cylindrical body and the slip support assembly to prevent the first shear pin from shearing; wherein, in a second state, the piston sleeve moves longitudinally to no longer transmit a longitudinal force between the cylindrical body and the slip support assembly, thereby allowing the first shear pin to shear.

[0007] The aforementioned suspension unit can effectively support the slip support sleeve in the first state, thereby preventing the first shear pin from breaking and thus effectively preventing the suspension unit from prematurely sitting down due to friction with the well wall during its lowering into the well.

[0008] Preferably, the slip support assembly includes a slip support sleeve disposed longitudinally above the piston sleeve, and a hydraulic cylinder sleeved on the outside of the piston sleeve, wherein the hydraulic cylinder is fixedly connected to the slip support sleeve.

[0009] Preferably, the upper hydraulic chamber is connected to the outside of the hydraulic cylinder through an external connecting hole on the hydraulic cylinder, and the lower hydraulic chamber is connected to the inside of the cylindrical body through an internal connecting hole on the cylindrical body. This allows for pressure balance between the upper and lower parts of the piston sleeve.

[0010] Preferably, the piston sleeve is constructed as an elastic sleeve, comprising: a main body ring; and a plurality of elastic claws connected to the longitudinal upper end of the main body ring, the plurality of elastic claws being arranged circumferentially spaced apart, the elastic claws being constructed to deform radially, each elastic claw having a locking protrusion at its upper end, the locking protrusion comprising an inner protrusion extending radially inward and an outer protrusion extending radially outward; wherein, in a first state, a first mating surface at the upper edge of the inner protrusion engages with a longitudinally inclined downward inner abutment surface on the outer side of the cylindrical main body, the first mating surface matching the inner abutment surface, and a second mating surface at the lower edge of the outer protrusion engages with a longitudinally upward outer abutment surface on the inner side of the slip support assembly, the second mating surface matching the outer abutment surface, so that the elastic sleeve can transmit longitudinal force between the slip support assembly and the cylindrical main body; wherein, in a second state, the first mating surface separates from the inner abutment surface, and the second mating surface separates from the outer abutment surface.

[0011] Preferably, the outer contact surface is constructed to be longitudinally inclined upwards.

[0012] Preferably, in the first state, the elastic sleeve is fixed to the cylindrical body by the second shear pin. By increasing the pressure in the lower hydraulic chamber, the second shear pin can be cut, and the elastic sleeve can be moved longitudinally upward to switch to the second state.

[0013] Preferably, the outer surface of the cylindrical body is provided with a mounting groove, and the upper edge of the mounting groove is provided as the inner abutment surface. In the first state, the inner protrusion of the snap-fit ​​protrusion is located in the mounting groove.

[0014] Preferably, the inner protrusion of the snap-fit ​​protrusion is further provided with a third mating surface that is longitudinally inclined downward at the lower edge, and the third mating surface is located below the second mating surface in the longitudinal direction.

[0015] Preferably, the suspension unit further includes: a locking slip hinged above the locking slip fixing sleeve and sleeved outside the cylindrical body; and a straightening ring fixedly sleeved outside the cylindrical body and located below the locking slip support sleeve, and capable of relative rotation with respect to the cylindrical body.

[0016] According to a second aspect of the invention, a cementing tool is provided, comprising the aforementioned hanger unit and a tailpipe mounted below the hanger unit.

[0017] Preferably, a pressure-holding mechanism is provided inside the tailpipe or the cylindrical body of the suspension unit, and the pressure-holding mechanism is used to change from the first state to the second state.

[0018] According to a third aspect of the present invention, a method of using the above-described suspension unit is provided, comprising the following steps: cutting off the second shear pin between the piston sleeve and the cylindrical body by pressing, causing the piston sleeve to move upward, thereby causing the suspension unit to change from a first state to a second state; further pressing to break off the first shear pin, causing the slip support assembly to move upward to cause the suspension unit to sit and change from the second state to a third state. Attached Figure Description

[0019] The invention will be described in more detail below with reference to the accompanying drawings.

[0020] Figure 1 A schematic diagram of a cementing tool according to an embodiment of the present invention is shown.

[0021] Figure 2A schematic diagram of a suspension unit according to an embodiment of the present invention is shown, the suspension unit being in a first state.

[0022] Figure 3 Showing Figure 2 A partial enlarged view of the suspension unit in the image.

[0023] Figure 4 A schematic diagram of a suspension unit according to an embodiment of the present invention is shown, the suspension unit being in a second state.

[0024] Figure 5 Showing Figure 4 A partial enlarged view of the suspension unit in the image.

[0025] Figure 6 A schematic diagram of a suspension unit according to an embodiment of the present invention is shown, the suspension unit being in a third state.

[0026] Figure 7 A schematic perspective view of an embodiment of a piston sleeve in a suspension unit according to the present invention is shown.

[0027] Figure 8 A schematic cross-sectional view of an embodiment of the piston sleeve in the suspension unit according to the present invention is shown.

[0028] In the accompanying drawings, the same parts use the same reference numerals. The drawings are not drawn to scale. Detailed Implementation

[0029] The invention will now be further described with reference to the accompanying drawings.

[0030] Figure 1 An embodiment of a cementing tool 1 according to the present invention is shown. The cementing tool 1 includes, from top to bottom, a feed tool unit 10, a return sleeve 20, a sealing box unit 30, a hanger unit 40, and a tailpipe.

[0031] The structure and specific working method of the feed tool unit 10, return tube 20, sealing box unit 30 and tail tube are well known in the art and will not be described in detail here.

[0032] Figure 2 An embodiment of a hanger unit 40 is shown. The hanger unit 40 includes an upper connector 41 and a cylindrical body 42 threadedly connected to the lower end of the upper connector 41. The upper connector 41 is used to connect the hanger unit 40 to the sealing box unit 30. The cylindrical body 42 is generally constructed in a cylindrical shape and extends longitudinally, forming a central channel therein for the passage of downhole fluids.

[0033] The suspension unit 40 also includes an end ring 43 sleeved around the cylindrical body 42. The upper end of the end ring 43 is engaged with the upper connector 41 via a bearing 431. This allows the end ring 43 and the structure connected below it to rotate relative to the cylindrical body 42.

[0034] The suspension unit 40 also includes a conical sleeve 44 sleeved outside the cylindrical body 42. The upper end of the conical sleeve 44 is fixedly connected to the end ring 43; the lower end is a free end, and its outer surface is a seated inclined surface that is radially inward in the longitudinal downward direction.

[0035] The suspension unit 40 also includes a slip 45, a slip support assembly (including a slip support sleeve 46 and a hydraulic cylinder 47) and a straightening ring 48, which are sleeved on the cylindrical body 42 and connected in sequence in the longitudinal downward direction.

[0036] The upper end of the slip 45 is a free end, and its inner surface is a seated inclined surface that is radially inclined inward in a longitudinally downward direction. The seated inclined surface of the cone sleeve 44 matches the seated inclined surface of the slip 45.

[0037] The upper end of the slip support sleeve 46 is hinged to the slip 45. The lower end of the slip support sleeve 46 is fixedly connected to the hydraulic cylinder 47 on its radially outer side. Thus, through the slip support sleeve 46 and the hydraulic cylinder 47, the hydraulic cylinder 47 forms a downward-facing stepped surface. An upward-facing stepped surface is provided on the outer wall of the cylindrical body 42, which is located longitudinally below the aforementioned downward-facing stepped surface, thereby forming a longitudinally extending hydraulic cavity between the hydraulic cylinder 47 and the cylindrical body 42. The hydraulic cylinder 47 can be fixedly connected to the cylindrical body 42 by a first shear pin 411.

[0038] The centering ring 48 is longitudinally supported at the lower end of the hydraulic cylinder. A retaining spring 412 is provided between the centering ring 48 and the cylindrical body 42 to fix the centering ring 48 relative to the cylindrical body 42. The retaining spring is secured with a set screw and then retracts 1 / 4 to 1 / 2 turn. The centering ring 48 can rotate circumferentially relative to the cylindrical body 42.

[0039] like Figure 2-3 As shown, a piston sleeve 49 is provided within the hydraulic chamber. This piston sleeve 49 slides and seals with the cylindrical body 42 and the hydraulic cylinder 47, allowing the piston sleeve 49 to move longitudinally within the hydraulic chamber. The piston sleeve 49 divides the hydraulic chamber into an upper hydraulic chamber 413 and a lower hydraulic chamber 414. Specifically, the upper hydraulic chamber 413 is formed on the upper side of the piston sleeve 49, and the lower hydraulic chamber 414 is formed on the lower side of the piston sleeve 49. The upper hydraulic chamber 413 is connected to the outside of the hydraulic cylinder 47 through a radially penetrating external connecting hole 471, thereby connecting to the downhole annulus. The lower hydraulic chamber 414 is connected to the central channel within the cylindrical body 42 through a radially penetrating internal connecting hole 421.

[0040] Figure 7 and Figure 8 The diagram shows the specific structure of one embodiment of the piston sleeve 49. The piston sleeve 49 is formed as an elastic sleeve. The piston sleeve 49 (elastic sleeve) includes a generally annular main body ring 493. An outer sealing groove 495 is provided on the outer surface of the main body ring 493. A sealing ring can be provided within the outer sealing groove 495 to achieve a sealing fit between the piston sleeve 49 and the hydraulic cylinder 47. An inner sealing groove 494 is provided on the inner surface of the main body ring 493. A sealing ring can be provided within the inner sealing groove 494 to achieve a sealing fit between the piston sleeve 49 and the cylindrical main body 42. The outer sealing groove 495 and the inner sealing groove 494 are offset longitudinally by a certain distance. This helps to reduce the thickness of the main body ring 493, thereby helping to reduce the overall diameter of the suspension unit 40. Figure 7 and Figure 8 In the example shown, the outer sealing groove 495 is longitudinally above the inner sealing groove 494. However, if desired, the inner sealing groove 494 may also be longitudinally above the outer sealing groove 495.

[0041] Multiple elastic claws 492 are connected to the upper longitudinal end of the main body ring 493. The multiple elastic claws 492 are evenly spaced in the circumferential direction. Each elastic claw is constructed to extend longitudinally and can undergo bending deformation in the radial direction.

[0042] Each elastic claw 492 has a locking protrusion 491 at its upper end. The locking protrusion 491 includes an inner protrusion extending radially inward and an outer protrusion extending radially outward.

[0043] The inner protrusion extends radially inward relative to the elastic claw 492. The upper edge of the inner protrusion has a first mating surface 4911, and the lower edge has a third mating surface 4913. The first mating surface 4911 is used to engage with the longitudinally inclined downward inner abutment surface on the outer surface of the cylindrical body 42. Figure 3 The first mating surface 4911 matches the position, size, and slope of the inner abutment surface.

[0044] The outer protrusion extends radially outward relative to the elastic claw 492. The lower edge of the outer protrusion has a second mating surface 4912. The second mating surface 4912 is used to engage with the longitudinally upward outer abutment surface on the inner surface of the slip support sleeve. Figure 3 The second mating surface 4912 is matched with the outer abutment surface in terms of position, size, and slope. The second mating surface 4912 and the outer abutment surface are preferably constructed to be inclined longitudinally upward.

[0045] In one example, the resilient claw 492 is integrally formed with the body ring 493 and the snap-fit ​​protrusion 491. The entire resilient sleeve can be made of spring steel (such as 65Mn) or high-strength alloy steel (such as 35CrMo).

[0046] In another example, the resilient claw 492 is separately formed and then assembled with the body ring 493 and / or the snap-fit ​​protrusion 491. The resilient claw 492 may be made of spring steel (such as 65Mn) or high-strength alloy steel (such as 35CrMo).

[0047] The following will combine Figures 2 to 6 The method of using the suspension unit 40 of the present invention will be described in detail.

[0048] exist Figure 2 and Figure 3 In the first state shown, the main ring 493 of the piston sleeve 49 is fixedly connected to the cylindrical body 42 by the second shear pin 410. At this time, the snap-fit ​​protrusion 492 is located in the mounting groove on the outer side of the cylindrical body 42. The first mating surface 4911 of the inner protrusion of the snap-fit ​​protrusion 492 engages with the inner abutment surface of the cylindrical body 42 (which forms the upper edge of the mounting groove). They are inclined surface fits. The second mating surface 4912 of the outer protrusion of the snap-fit ​​protrusion 492 engages with the outer abutment surface of the slip support sleeve. They are inclined surface fits. The mounting groove helps to position the piston sleeve 49 relative to the cylindrical body 42 during assembly, thereby simplifying the installation process.

[0049] In the first state, if a downward longitudinal force is applied to the slip 45, slip support sleeve 46, or cylinder 47, the centering ring 48 can withstand the downward longitudinal force, thereby ensuring that the slip 45 and slip support sleeve remain in place. If a upward longitudinal force is applied to the slip 45, slip support sleeve 46, or cylinder 47 (e.g., due to scraping), this force is transmitted to the piston sleeve 49 through the engagement of the second mating surface 4912 with the outer abutment surface, and to the cylindrical body 42 through the engagement of the inner protrusion with the mounting groove and the engagement of the first mating surface 4911 with the inner abutment surface. Specifically, when the force is transmitted to the second mating surface 4912 through the outer abutment surface, the piston sleeve 49 (elastic sleeve) can undergo elastic deformation, so a torque (counterclockwise) can be applied to the locking protrusion 491, thereby enabling the locking protrusion 491 to be pressed tightly radially inward against the cylindrical body 42. The engagement of the inner abutment surface with the first mating surface 4911 helps to ensure the position of the piston sleeve 49 is fixed. In other words, the hydraulic cylinder 47, the snap-fit ​​protrusion 491, and the cylindrical body 42 are tightly "squeezed" together. This provides stable support for the slip 45 and the hydraulic cylinder 47, and prevents the first shear pin 411 from shearing off due to the load.

[0050] When the hanger unit 40 and cementing tool 1 are sent down into the well in the first state, it can effectively prevent the hanger unit 40 from getting stuck prematurely due to the scraping of the well wall.

[0051] A pressure-retaining mechanism may be provided within the cylindrical body 42 and / or the tailpipe of the cementing tool 1. This pressure-retaining mechanism is located below the aforementioned internal connecting hole 421 or within the tailpipe string. By applying pressure at the pressure-retaining mechanism, a transition from a first state to a second state can be achieved.

[0052] Specifically, when pressure is applied via the pressure-retaining mechanism, the pressure in the central channel within the cylindrical body 42 increases, thereby increasing the pressure in the lower hydraulic chamber 414, which is connected to the central channel via the inner connecting hole 421. At this time, the upper hydraulic chamber 413 is connected to the downhole annulus, so their pressures are the same. In this situation, the pressure in the lower hydraulic chamber 414 is greater than the pressure in the upper hydraulic chamber 413, causing the piston sleeve 49 to be pushed longitudinally upwards. Since the first mating surface 4911 and the inner abutment surface are in a beveled fit, when the piston sleeve 49 is pushed upwards by the lower hydraulic chamber 414, the second shear pin 410 can be sheared off, and under the cooperation of the first mating surface 4911 and the inner abutment surface, the elastic claw 492 deforms radially outwards, allowing the inner protrusion of the locking protrusion 491 to leave the mounting groove. Figure 4 and Figure 5 As shown, the piston sleeve 49 is pushed longitudinally upward, causing the first mating surface 4911 to separate from the inner abutment surface and the second mating surface 4912 to separate from the outer abutment surface. Thus, the piston sleeve 49 no longer transmits longitudinal force between the slip support sleeve and the cylindrical body 42, preventing the suspension unit from being suspended and allowing it to be suspended.

[0053] By further pressurizing at the pressurizing mechanism, the piston sleeve 49 can be pushed longitudinally upward against the slip support sleeve 46, causing the first shear pin 411 to shear off, transitioning to the third state. At this time, as... Figure 6 As shown, the piston sleeve 49 can push the slip support sleeve 46 and the slip 45 to move longitudinally upward together. Through the cooperation of the slip 45 and the cone sleeve 44, the slip 45 extends radially outward and engages with the well wall to achieve mounting.

[0054] Furthermore, since the end ring 43 and the centralizer 48 are designed to rotate circumferentially relative to the cylindrical body 42, during the cementing tool 1's insertion into the well, when the upper connector 41 drives the cylindrical body 42 to rotate, the end ring 43 and the centralizer 48, as well as the cone sleeve 44, slips 45, and slip support assembly between them, can remain stable or rotate relatively slowly. This helps reduce the required torque and the resistance experienced by the cementing tool 1. Consequently, premature settling of the suspension unit 40 can be avoided from another perspective.

[0055] By using the aforementioned cementing tool 1, its suspension unit 40, and the corresponding usage method, premature snagging of the suspension unit 40 due to downhole friction during its insertion into the well can be effectively prevented. This is highly advantageous for cementing operations in complex well conditions such as horizontal wells, deep wells, and ultra-deep wells.

[0056] In this article, the term "longitudinal" refers to the direction in which the wellbore extends, "up" refers to the direction near or toward the wellhead, and "down" refers to the direction near or toward the bottom of the well.

[0057] Although the invention has been described with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner as long as there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A suspension unit, comprising: A cylindrical body extending longitudinally; A slip support assembly, which is sleeved outside the cylindrical body, forms a hydraulic cavity between the slip support assembly and the cylindrical body, and is connected to the cylindrical body by a first shear pin; and A piston sleeve is sealed between the cylindrical body and the slip support assembly and located within the hydraulic chamber. The piston sleeve is configured to slide longitudinally within the hydraulic chamber and divides the hydraulic chamber into an upper hydraulic chamber and a lower hydraulic chamber. In the first state, the piston sleeve is fixed inside the hydraulic chamber and transmits longitudinal force between the cylindrical body and the slip support assembly to prevent the first shear pin from shearing off. In the second state, the piston sleeve moves longitudinally until it no longer transmits longitudinal force between the cylindrical body and the slip support assembly, allowing the first shear pin to cut.

2. The suspension unit according to claim 1, characterized in that, The slip support assembly includes a slip support sleeve disposed longitudinally above the piston sleeve, and a hydraulic cylinder sleeved on the outside of the piston sleeve, the hydraulic cylinder being fixedly connected to the slip support sleeve.

3. The suspension unit according to claim 2, characterized in that, The upper hydraulic chamber is connected to the outside of the hydraulic cylinder through an external connecting hole on the hydraulic cylinder, and the lower hydraulic chamber is connected to the inside of the cylindrical body through an internal connecting hole on the cylindrical body.

4. The suspension unit according to any one of claims 1 to 3, characterized in that, The piston sleeve is configured as an elastic sleeve, the elastic sleeve comprising: Main ring; and Multiple elastic claws are connected to the upper longitudinal end of the main body ring. The multiple elastic claws are arranged circumferentially spaced apart. The elastic claws are constructed to deform radially. Each elastic claw has a snap-fit ​​protrusion at its upper end. The snap-fit ​​protrusion includes an inner protrusion extending radially inward and an outer protrusion extending radially outward. In the first state, the first mating surface at the upper edge of the inner protrusion engages with the longitudinally inclined downward inner abutment surface on the outer side of the cylindrical body, and the first mating surface matches the inner abutment surface. The second mating surface at the lower edge of the outer protrusion engages with the longitudinally upward outer abutment surface on the inner side of the slip support assembly, and the second mating surface matches the outer abutment surface, so that the elastic sleeve can transmit longitudinal force between the slip support assembly and the cylindrical body. In the second state, the first mating surface is separated from the inner abutting surface, and the second mating surface is separated from the outer abutting surface.

5. The suspension unit according to claim 4, characterized in that, The outer contact surface is constructed to be inclined vertically upwards.

6. The suspension unit according to claim 4 or 5, characterized in that, In the first state, the elastic sleeve is fixed to the cylindrical body by the second shear pin. By increasing the pressure in the lower hydraulic chamber, the second shear pin can be cut, and the elastic sleeve can be moved longitudinally upward to switch to the second state.

7. The suspension unit according to any one of claims 4 to 6, characterized in that, The outer surface of the cylindrical body is provided with a mounting groove, and the upper edge of the mounting groove is provided as the inner abutment surface. In the first state, the inner protrusion of the snap-fit ​​protrusion is located in the mounting groove.

8. The suspension unit according to any one of claims 4 to 7, characterized in that, The inner protrusion of the snap-fit ​​protrusion is also provided with a third mating surface that is longitudinally inclined downward at the lower edge, and the third mating surface is located below the second mating surface in the longitudinal direction.

9. The suspension unit according to any one of claims 1 to 8, characterized in that, The suspension unit also includes: The slip, hinged above the slip fixing sleeve and fitted over the cylindrical body; and The straightening ring is fixedly sleeved outside the cylindrical body and located below the slip support sleeve, and can rotate relative to the cylindrical body.

10. A cementing tool comprising a hanger unit according to any one of claims 1 to 8, and a tailpipe mounted below the hanger unit.

11. The suspension unit according to claim 10, characterized in that, A pressure-holding mechanism is provided inside the tailpipe or the cylindrical body of the suspension unit. The pressure-holding mechanism enables the transition from the first state to the second state and from the second state to the third state.

12. A method of using a suspension unit according to any one of claims 1 to 8, comprising the following steps: By pressing and shearing the second shear pin between the piston sleeve and the cylindrical body, the piston sleeve moves upward, thereby causing the suspension unit to change from the first state to the second state. Further pressure is applied to disengage the first shear pin, causing the slip support assembly to rise and cause the suspension unit to sit, transitioning from the second state to the third state.

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