Pack-off system and apparatus

Abstract

A pack-off assembly comprising a main body and an upper body configured to receive a line for deployment in a well, and a seal adapted to be actuated into sealing engagement with the line in the body to contain wellbore pressure within the well below the actuated seal. The pack-off assembly comprises a slip to secure the line from moving in or out, the slip has a tapered cylindrical wall with a flanged end. A compression plate pushes the slip in place, the compression plate pushed by a slip compression sub through a thrust bearing.

Description

PACK-OFF SYSTEM AND APPARATUSCROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to US provisional application no. 63 / 635,236, filed 04 / 17 / 2024, and entitled PACK OFF SYSTEM AND APPARATUS, the contents of which are entirely incorporated herein.FIELD

[0002] The disclosure relates generally to an apparatus for drilling and completing wall bores. The disclosure relates specifically to an apparatus for sealing assembly adapted to seal a line such as wireline deployed in an oil or gas well.BACKGROUND

[0003] Oil and gas well servicing can involve inserting a tool into the wellbore to analyze geological formations around wellbore, gather information about the hydrocarbon reservoir, determine the integrity of the wellbore, or for other reasons. The tool can be connected to a cable that is a wireline which has electrical conductors for sending and / or receiving data to the tool. These cables are typically connected to a winch at the surface and are used to lower and raise the tool in the wellbore. When using downhole cables, such as wireline cables, in high-pressure wellbores, measures must be taken to prevent release of that pressure when running cable in and out of the wellbore.

[0004] As a safety precaution, a pack-off assembly can be employed to assist in control of well pressure. The pack-off assembly may take the form as a stripper, stuffing box, sealing gland, and pack-off heads. In each case, the assembly performs the safety function of pressure containment during wireline operations. For example, A pack-off head is designed to make a pressure seal around a wireline to contain the well pressure during trips in and out of the well. If during wireline operations a well kick was experienced, an unsafe condition would occur if the well head was not contained but instead left open to atmosphere. A typical pack-off assembly includes a hard rubber insert with a passage where the wire line passes through the annulus. To seal around the wireline, the hard rubber insert is axially compressed, which reduces the cross-sectional area of the passage. Reducing the cross-sectional area of the passage causes the inner radius of the passage to fit around the outer radius of the wire line, thus preventing fluid flow through the passage. The typical prior art pack-off assembly only functioned to seal around a static line. This was due at least in part to the fact that theprior art braided cable would quickly destroy the seal if it moved though the energized seal element in use.

[0005] There is a need, therefore, for a pack-off assembly having improved resistance to deterioration during well servicing operations.SUMMARY

[0006] A pack-off assembly can comprise a device with an elastomer packing element that depends on pressure below the packing to effectuate a seal in the annulus. A pack-off herein can be used to run or pull pipe under varying pressures.

[0007] The present disclosure provides a pack-off assembly comprising a main body and an upper body configured to receive a line for deployment in a well, and a seal adapted to be actuated into sealing engagement with the line in the body to contain wellbore pressure within the well below the actuated seal, wherein the seal comprises a sealing element which is resilient.

[0008] The main body comprises an outer wall and an inner wall, the lower end of a cylindrical wall of the upper body inserts into the space between the outer wall and the inner wall of the main body. A union nut overlaps parts of the main body and the upper body to connect them.

[0009] The pack-off assembly further comprises a slip to secure the line from moving in or out, the slip has a tapered cylindrical wall with a flanged end. To secure the slip in place, a compression plate is employed to push the slip, the compression plate pushed by a slip compression sub through a thrust bearing. The slip compression sub has a cylindrical wall, the cylindrical wall has an inner threaded surface which engages the exterior threaded surface of the inner wall of the main body. A thrust bearing is located between the compression sub and the compression plate such that the compression sub can transmit force to the compression plate while rotating.

[0010] In order to compress the sealing element within the upper body, the sealing element is sandwiched between two compression plates. A top compression plate is pushed by a lock nut, the lock nut has an externally threaded surface which engages the internally threaded surface of the upper body, a thrust bearing is located between the lock nut and the top compression plate. The compression plate has at least one hole corresponding to at least one channel of the sealing element to pass through at least one line.

[0011] The pack-off assembly further comprises a removable nut coupled to the lower end of the main body through a split ring and a retaining ring.

[0012] The foregoing has outlined the features of the present disclosure in order that the detailed description that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter, which form the subject of the claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order that the manner in which the above-recited and other enhancements and objects of the disclosure are obtained, a more particular description of the disclosure briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the disclosure and are therefore not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through the use of the accompanying drawings in which:

[0014] FIG.l is a perspective view of a pack-off assembly in accordance with embodiments disclosed herein.

[0015] FIG.2 is a cross-sectional view of the pack-off assembly of FIG.l.

[0016] FIG.3 is a perspective view of the main body in FIG.l.

[0017] FIG.4 is a perspective view of the upper body in FIG.l.

[0018] FIG.5 is a perspective view of a slip in accordance with embodiments disclosed herein.

[0019] FIG.6 is a perspective view of a bearing washer in accordance with embodiments disclosed herein.

[0020] FIG.7 is a perspective view of a thrust roller bearing in accordance with embodiments disclosed herein.

[0021] FIG.8 is a perspective view of a snap ring in accordance with embodiments disclosed herein.

[0022] FIG.9 is a perspective view of a seal element in accordance with embodiments disclosed herein.

[0023] FIG.10 is a perspective view of a compression plate in accordance with embodiments disclosed herein.

[0024] FIG.11 is a perspective view of a split ring in accordance with embodiments disclosed herein.DETAILED DESCRIPTION

[0025] The particulars shown herein are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present disclosure only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of various embodiments of the disclosure. In this regard, no attempt is made to show structural details of the disclosure in more detail than is necessary for the fundamental understanding of the disclosure, the description taken with the drawings making apparent to those skilled in the art how the several forms of the disclosure may be embodied in practice.

[0026] The terms “up” and “down”; “upper” and “lower”; “upwardly” and downwardly”; “above” and “below”; and other like terms as used herein refer to relative positions to one another and are not intended to denote a particular direction or spatial orientation.

[0027] Referring now to the drawings, one example of a pack-off assembly 10 shown in FIG. 1 comprises a main body 20, an upper body 40 coupled to the main body 20 through a union nut 50. FIG. 2 shows a cross-sectional view of the pack-off assembly 10 in FIG. 1. A central bore 28 extends through the main body 20 and the upper body 40 which receives at least one line such as wireline or slickline adapted to be deployed in the well, the central bore 28 guides the line alone a pathway through the pack-off assembly 10. The pack-off assembly 10 has a sealing element 70 inside the upper body 40, the sealing element 70 has at least one channel 71 to receive the at least one line, the sealing element 70 can seal the annulus between the inner surface of the upper body 40 and the outer surface of the at least one line.

[0028] FIG. 3 is a perspective view of main body 20. The lower end 21 of main body 20 is a cylindrical wall with a flanged end 25, transitioning into a larger diameter section in the middle portion 22, the upper end of the main body 20 has a two-layer cylindrical wall, the outer wall 23 and inner wall 24. The upper end of the main body 20 has a flange 26 between the middle portion and theupper end, the inner wall 24 defines a tapered bore 27 to receive a slip which will be depicted hereafter.

[0029] FIG. 4 is a perspective view of the upper body 40. Referring to FIGS. 2 and 4, the upper body 40 has a cylindrical wall 44, lower end of the cylindrical wall 44 can insert into the space between the outer wall 23 and inner wall 24 of the upper end of the main body 20, a shoulder 46 is on the cylindrical wall 44 to position the insertion depth. The outer surface of the cylindrical wall 44 closely fits to the inner surface of the inner surface of the outer wall 23. Cylindrical wall 44 has two grooves 47, 48 around the outer circumference to accommodate two O-rings 36 respectively to provide seal between the outer surface of cylindrical wall 44 and inter surface of the outer wall 23 of the main body 20. In a preferred embodiment, each O-ring 36 is sandwiched by two backup rings 35,37 to provide added extrusion resistance and prevent damage to the O-ring 36 when subjected to high pressures, larger extrusion gaps, and / or high temperatures.

[0030] A union nut 50 overlaps parts of the main body 20 and the upper body 40 to connect the main body 20 and the upper body 40. The upper end of the union nut 50 has an inner flange 53 to push the shoulder 46 of the upper body 40 to against the upper end of the outer wall 23 of the main body 20, The lower end of the union nut 50 has an inner threaded surface 54 which engages the exterior threaded surface of the outer wall 23 of the main body 20, such that the union nut 50 connects the upper body 40 to the main body 20. To lock the connection, the union nut 50 comprises a plurality of screw holes to engage lock screws 52 to lock the flange 46 of the upper body 40 to the union nut 50.

[0031] The upper body 40 has a stepped interior bore 45 to receive slip assembly and sealing element 70 respectively, the slip assembly comprises a slip 52, a compression plate 64, a thrust bearing and a slip compression sub 60.

[0032] The pack-off assembly 10 comprises a slip 66 to secure the line from moving in or out. As shown in FIG. 5, the slip 66 has a tapered cylindrical wall 661 with a flanged end 662, it’s tapered so when tightened it bites into the tapered bore 27 in the inner wall 24 of the main body 20 to hold it in place. Slip 66 is pushed into the tapered bore 27 and retained by the flanged end against the top end of inner wall 24 of the main body 20.

[0033] Referring back to FIG. 2, to secure the slip 66 in place, a compression plate 64 is employed to push the slip 66, the compression plate 64 is pushed by a slip compression sub 60 through a thrust bearing, the slip compression sub 66 has a cylindrical wall 602, The cylindrical wall 602 has an innerthreaded surface 601 which engages the exterior threaded surface of the inner wall 24 of the main body 20, such that rotation of the compression sub 60 can push the thrust bearing and transmit the force to the compression plate 64 to push the slip 66 in place. The thrust bearing is located between the compression sub 60 and the compression plate 64 such that the compression sub 60 can transmit force to the compression plate 64 while rotating, since a thrust bearing can rotate between parts and support a predominantly axial load. As shown in FIGS. 6 and 7, the thrust bearing comprises two bearing washer 61 ,63 and a cylindrical thrust roller bearing 62 therebetween. To lock the connection between the compression sub 60 and the inner wall 24, the compression sub 60 comprises a plurality of screw holes to engage lock screws 67 to against the outer surface of the inner wall 24.

[0034] The inner surface of the cylindrical wall 602 of the compression sub 60 comprises a groove to accommodate a snap ring 68 to retain the slip 66. FIG. 8 is a perspective view of snap ring 68. Referring to FIGS. 2 and 8, when the snap ring 68 is pushed into the groove, it wraps around the flanged end 662 of the slip 66 to secure the slip 66 in place.

[0035] Compression plate 64 has two grooves around the outer circumference to accommodate O- rings 65,69 respectively to provide seal between the compression plate 64 and the compression sub 60.

[0036] FIG. 9 is a perspective view of the sealing element 70. Referring to FIGS. 2 and 9, the sealing element 70 is closely received within the cylindrical interior bore of the upper body 40, the sealing element 70 has a cylindrical exterior sidewall and has at least one channel 71 which is appropriately sized to receive and seal around at least one line. The sealing element 70 will typically be formed of a suitable elastomeric material, such as a suitable rubber. To ensure that the sealing element 70 will seal around the line, it is important that the elastomeric material be sufficiently pliable to perform under extreme cold or hot conditions for which it will be used and yet be of adequate resiliency to sustain the pressure applied to it to preclude leakage between the wiper sealing element 70 and the at least one line.

[0037] In order to compress the sealing element 70 within the upper body 40, The sealing element 70 is sandwiched between two compression plates 73, 74. The lower compression plate 73 is retained by an interior shoulder of the upper body 40, the top compression plate 74 is pushed by a lock nut 80. The lock nut 80 has an externally threaded surface 86 which engages the internally threaded surface of the upper body 40, a thrust bearing is located between the lock nut and the top compression plate such that the lock nut 80 can transmit force to the compression plate 74 while rotating the locknut to push the compression plate. The thrust bearing comprises two bearing washer 82, 84 and a cylindrical thrust roller bearing 83 therebetween.

[0038] Referring to FIG. 10, compression plate 74 is a metal disc, it has at least one hole 741 being aligned with at least one channel 71 of the sealing element 70 to pass through at least one line, in one embodiment, the number of the channel or hole is seven. The compression plate 74 has one groove 742 around the outer circumference to accommodate an O-ring 76 to provide seal between the compression plate and the upper body 40. In a preferred embodiment, the O-ring 76 is sandwiched between two backup rings 75, 77.

[0039] The pack-off assembly 10 further comprises a removable nut 30 coupled to the lower end of the main body through a split ring 31 and a retaining ring 32. The split ring 31 slips over the lower end 21 of the main body 20 and retained by the flanged end 25 of the main body 21, referring to FIG. 11, the split ring 31 has a flange 312 on its bottom end, and a groove 311 around the outer circumference to accommodate the retaining ring 32, referring to FIG. 2, the removable nut 30 coupled to the split ring 31 between the flange 312 and the groove 311. Once the retaining ring 31 sits properly in the groove 311, part of its circumference sticks out to form a shoulder that secures the removable nut 30 on the split ring 31.

[0040] The compositions and methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this disclosure have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions and methods and in the steps or in the sequence of steps of the methods described herein without departing from the concept, spirit and scope of the disclosure. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the scope and concept of the disclosure as defined by the appended claims.

Claims

CLAIMS1. A pack-off assembly comprising: a main body; an upper body to receive a sealing element; a union nut connecting the main body and the upper body; and a central bore extending through the main body and the upper body which receives at least one line used in oil and gas well servicing.

2. The pack-off assembly of claim 1, wherein the sealing element is resilient.

3. The pack-off assembly of claim 1, wherein the sealing element comprises at least one channel to accommodate the at least one line.

4. The pack-off assembly of claim 1 , wherein the main body comprises an outer wall and an inner wall, the lower end of a cylindrical wall of the upper body inserts into the space between the outer wall and the inner wall of the main body.

5. The pack-off assembly of claim 4, further comprising a slip attached to the lower end of inner wall of the main body.

6. The pack-off assembly of claim 5, wherein the slip has a tapered cylindrical wall with a flanged end.

7. The pack-off assembly of claim 5, further comprising a compression plate to push the slip to attached to the lower end of inner wall of the main body.

8. The pack-off assembly of claim 7, further comprising a slip compression sub to push the compression plate.

9. The pack-off assembly of claim 8, wherein the slip compression sub has an inner threaded surface to engage the exterior threaded surface of the inner wall of the main body.

10. The pack-off assembly of claim 8, further comprising a first thrust bearing between the slip compression sub and the compression plate.

11. The pack-off assembly of claim 10, wherein the first thrust bearing comprises two bearing washer and a cylindrical thrust roller bearing.

12. The pack-off assembly of claim 8, wherein the slip compression sub comprises a snap ring to retain the slip.

13. The pack-off assembly of claim 2, wherein the sealing element is sandwiched between a lower compression plate and a top compression plate.

14. The pack-off assembly of claim 13, wherein the lower compression plate and the top compression plate have at least one hole to pass through the at least one line.

15. The pack-off assembly of claim 13, further comprising a lock nut to push the top compression plate.

16. The pack-off assembly of claim 14, the lock nut 80 has an externally threaded surface to engage the internally threaded surface of the upper body.

17. The pack-off assembly of claim 14, further comprising a second thrust bearing between the top compression plate and the lock nut.

18. The pack-off assembly of claim 13, further comprising an O-ring between the lower compression plate and the inner surface of the upper body.

19. The pack-off assembly of claim 18, further comprising two backup rings to sandwich the O-ring.

20. The pack-off assembly of claim 1, further comprising a removable nut coupling to the lower end of the main body.ABSTRACT

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