GB2251013A

GB2251013A - Single trip casing hanger/packoff running tool

Info

Publication number: GB2251013A
Application number: GB9125626A
Authority: GB
Inventors: Shiva Prasad Singeetham
Original assignee: FMC Corp
Current assignee: FMC Corp
Priority date: 1990-12-21
Filing date: 1991-12-02
Publication date: 1992-06-24
Anticipated expiration: 2011-12-02
Also published as: GB2251013B; GB9125626D0

Abstract

A well tool assembly for running a casing hanger 40 and a packoff 34 into a wellhead housing 90 during a single trip into the well, comprises a tubular inner mandrel 12, a locking mandrel 26 and inner body 28, an outer annular body 16 surrounding and rotatably connected to the inner mandrel, an outer sleeve 20 surrounding the outer body, and means 30 to selectively prevent relative rotation between the outer body and the locking mandrel. The casing hanger is releasably secured to the tool by a lock ring 36 expandable by the looking mandrel 26 and inner body 28. The packoff is secured to the tool by lock pins 32 withdrawable into a circumferential groove provided on the locking mandrel to permit release of the packoff following landing and setting. A breech block thread system is provided for selectively inter-connecting inner mandrel 14 and the locking mandrel 26. <IMAGE>

Description

SINGLE TRIP CASING HANGER/PACKOFF RUNNING TOOL This invention relates to running tools for installing casing hangers and annulus packoffs in a wellhead housing, and more particularly to such tools that facilitate running a hanger and a packoff together in a single trip into the well.

In subsea or other underwater well drilling procedures an established practice is to run, land and set casing hangers and annulus packoffs in the submerged wellhead housing by means of a running tool connected to a drill string or other pipe string. The hanger and packoff are releasably connected to the running tool to facilitate retrieval of the tool after the hanger and packoff have been set in the wellhead housing, and advances in this technology have produced running tools that enable the operator to accomplish those tasks during a single trip into the well. As the search for offshore oil deposits progresses into deeper water areas the costs thereof escalate dramatically, thereby continuing the need for tools that function more efficiently and procedures that are less time-consuming.

The present invention provides a well tool for running a casing hanger and an annulus packoff into a wellhead housing comprising: a mandrel for connection to a pipe running string, means to releasably attach an annulus packoff to the tool and means to releasably attach a casing hanger to the tool; the tool being operable to land a casing hanger carved by the hanger attachment means in a wellhead housing, subsequent rotation of the mandrel relative to the hanger attachment means causing release of the hanger, and permitting downward movement of an annulus packoff carried by the packoff attachment means to land and set the packoff between the hanger and the wellhead housing, said downward movement also causing release of the packoff from the packoff attachment means, permitting the tool to be withdrawn upwardly from the wellhead housing.

The mandrel may comprise a tubular inner mandrel with means to connect it to a pipe string, the tool further comprising an annular outer body surrounding the inner mandrel, a tubular locking mandrel surrounding the inner mandrel, a tubular inner body within the locking mandrel and means, for example spring-biased anti-rotation pins) selectively operable to prevent relative rotation between the outer body and the locking mandrel. Further spring-biased lock pins in the outer body may be used to releasably secure a packoff to the tool.An expandable split lock ring on the inner body may releasably secure a casing hanger to the tool, spring-biased anti-rotation pins in the inner body preventing its rotation with respect to the casing hanger, and antirotation keys in the inner body co-operating with axial slots in the locking mandrel to prevent relative rotation between that body and mandrel yet facilitating relative axial movement therebetween.

In a preferred embodiment installation of an annul us packoff on the running tool is accomplished by rotating the tool's outer body to extend the packoff attachment lock pins into an inner annular groove in the packoff, this rotation also permitting the anti-rotation pins in the outer body to move into functional locking engagement with adjacent axial grooves in the locking mandrel, thereby preventing further relative rotation between that body and mandrel. The tool is then attached to a casing hanger hy left hand rotation of the inner mandrel, causing axial movement-of the locking mandrel with respect to the inner body and expansion of the lock ring into an inner annular groove in the hanger.After running and landing the hanger in the wellhead housing the running string is rotated to the right, thereby rotating and unthreading the inner mandrel from the locking mandrel. The inner mandrel, outer body and packoff are then lowered as a unit until the packoff lands on a support shoulder on the hanger or other location in the wellhead housing, and the weight of the running string and tool inner mandrel, outer body and outer sleeve imposed on the packoff to energise and set it in functional sealing position between the hanger and housing.

Depending upon the type of packoff, further energisation thereof can be achieved by closing the blowout preventer (BOP) rams around the running string and pressurising the space between those rams and the tool's outer body, causing further downward movement of the outer body and outer sleeve and resulting in additional energising forces on the packoff. The tool can then be retrieved for further use by simply lifting the running string to withdraw the tool from the hanger, packoff and wellhead housing.

Further preferred features of the invention are set forth in the claims and in the following description of one embodiment made by way of example and with reference to the drawings wherein Figures 1A and 1B together constitute a view in central vertical section of a single trip casing hanger and packoff running tool according to the present invention; Figures 2A and 2B together constitute a view like Figures 1A and 1B, but also showing a casing hanger and a packoff attached to the running tool; Figure 3 is a view in central vertical section, on a reduced scale, showing the running tool, casing anger and packoff of Figures 2A and 2B in a wellhead housing with the hanger and packoff set in their functional positions.

Figure 4 is a view like Figure 3 but showing the running tool disconnected from the packoff and hanger and ready for retrieval from the wellhead housing; and Figure 5 is an isometric fragmentary view, partially in section, of the running tool inner mandrel and locking mandrel, showing the breech-block threads for inter-connecting these elements.

As best seen in Figures 1A, 1B and 2A, 2B, a single trip casing hanger and packoff running tool 10 according to the present invention comprises a tubular inner mandrel 12 with internal threads 14 at its upper end for attaching it to a drill or other pipe string (not shown) employed to run and retrieve the tool from a surface location, an annular outer body 16 surrounding the inner mandrel 12 and rotatably retained thereon by an annular cap body retainer 18 threaded onto the mandrel 12, an outer sleeve 20 surrounding and releasably secured to the outer body by a plurality of shear pins 22, a tubular locking mandrel 24 surrounding the inner mandrel 12 and having an upper portion 26 located between the inner mandrel and the outer body 16, and a tubular inner body 28 surrounding the lower portion of the inner mandrel 12 and surrounded by the lower portion of the locking mandrel 24. A plurality (preferably two) of circumferentially spaced springbiased anti-rotation pins 30 (only one shown) in the outer body 16 co-operate with a plurality of circumferentially spaced (preferably four) axial slots 31 (only one shown) on the outer surface of the locking mandrel 24 to prevent relative rotation between the outer body and that mandrel when the pins are in their functional position (Figures 1 to 4), and a plurality (preferably four) of circumferentially spaced packoff lock pins 32 (only one shown) in the outer body 16 releasably connect an annulus packoff 34 (Figure 2B) to the running tool when in their functional position. The lower ends of the axial slots 31 open into a circumferential groove 25, whose purpose is described below.

The tool 10 further includes a split lock ring 36 carried by the inner body 28 and expandable into a groove 38 (Figure 2B in a casing hanger 40 to releasably attach the hanger to the tool, and a plurality (preferably three) of circumferentially spaced spring-biased anti-rotation pins 42 (only one shown) in the inner body 28 to prevent rotation between the inner body and the casing hanger 40 when in their functional position in axial slots 44 in the hanger. In addition, the tool 10 includes a plurality (preferably two) of circumferentially spaced anti-rotation keys 46 (only one shown) in the inner body 28 that co-operate with axial grooves 48 in the locking mandrel 24 to prevent relative rotation, yet facilitate relative axial movement, between the body 28 and mandrel 24.An annular sleeve 50, surrounding the upper portion of the outer body 16 and retained thereon by a snap ring 52, serves as a retainer for the outer sleeve 20. In order to facilitate flushing out the annular chamber 54 between the outer body 16 and the inner mandrel 12, a wash port 56 with a removable wash plug 58 are provided in the upper end of the outer body. A stop key 60 (Figures 1B, 2B), secured to the upper end of the locking mandrel 24 by a cap screw 62, co-operates with a stop lug 64 (Figures 1A, 2A) on the inner mandrel 12 to rotationally position the inner mandrel with respect to the locking mandrel during the procedure for landing the packoff 34, as will be more fully described later.

The inner mandrel 12 and the locking mandrel 24 are inter-connected by a breech-block thread system 68 comprising internal threads 70 (Figure 5) on the locking mandrel and external threads 72 on the inner mandrel. As illustrated in Figure 5, the lower half 70a of the threads 70 are discontinuous because of three circumferentially spaced n-n-threaded axial slots 74, and in like manner the upper half 72a of the threads 72 are discontinuous because of three circumferentially spaced non-threaded axial slots 76. The slots 74, 76 facilitate axial movement of the inner mandrel 12 partially through the locking mandrel 24 without rotation of either element, whereas when any portion of the threads 70 is engaged with any portion of the threads 72 the mandrels can move axially with respect to each other only during relative rotational movement between them.

The lower end of the locking mandrel 24 functions to expand the lock ring 36 into its functional locking position in the hanger groove 38 (Figures 2B and 3) when the mandrel moves downwardly with respect to the inner body 28. The Lock ring 36 has a plurality (preferably two) of circumferentially spaced radial slots 78 in its upper end into which extend the radial or "foot" portions 80 of a plurality (preferably two) of circumferentially spaced keys 82 on the outer surface of the inner body 28, these foot portions functioning to hold the lock ring down on the radial surface or shoulder 84 of the inner body. The keys 82 also co-operate with the locking mandrel grooves 48 to provide an anti-rotation function between the inner body 28 and the locking mandrel 24 when the keys and slots are engaged.

CASING HANGER/PACKOFF RUNNING PROCEDURE Using the tool 10 to run, land and set the casing hanger 40 and the packoff assembly 34 in a wellhead housing 90 (Figure 3) is accomplished as follows. The tool inner mandrel 12 is threaded onto a pipe string (not shown) and suspended above the floor of the drilling platform (not shown).

At this stage the locking mandrel 26 is in a raised position relative to the rest of the tool elements, similar to the position shown in Figure 3, but somewhat higher, so as to allow the anti-rotation pins 30 to ter the circumferential groove- 25, such that the outer body is free to rotate relative to the locking mandrel 26. Alternatively, the pins 30 may be manually withdrawn against their spring bias via access openings 30a provided in the outer sleeve 20 thereby obviating the need to fully raise the locking mandrel 26. When in the raised position, the locking mandrel is secured against rotation relative to the inner mandrel 12 by engagement of the stop key 60 in a longitudinal groove 64a formed in the outer surface of the inner mandrel 12.The stop lug 64 is positioned adjacent the lower end of the groove 64a and serves to guide the key 60 into the groove 64a once the locking mandrel has been raised sufficiently to disengage the breech block thread system; it also serves to re-align the threaded portions 72a of the inner mandrel 12 with the nonthreaded axial slots 74 of the locking mandrel 24, upon lowering of the locking mandrel.

With the locking pins 30 withdrawn from the grooves 31, the outer body 16 is rotated relative to the locking mandrel until the packoff lock pins 32 move inward into the locking mandrel slots 31. With the threaded portions 72a of the inner mandrel 12 residing in the non-threaded axial slots 74 of the locking mandrel 24 the lock ring 36 lies in its retracted condition. The packoff assembly 34 is then positioned around the lower end of the outer body 16, and the outer body is rotated so that camming surfaces 31a (Figure 5) force the lock pins 32 outward from the slots 31 into a groove 92 in the packoff, thereby releasably connecting the packoff to the tool and allowing the anti-rotation pins 30 to move into the slots 31.The tool 10 is then lowered into and landed on the casing hanger 40 and the inner mandrel 12 then rotated to the left, causing engagement of the breech block thread system 68 and descent of the locking mandrel 24, which forces the lock ring 36 to expand into the hanger groove 38, thereby releasably connecting the hanger to the tool (Figure 28).

The tool, hanger and packoff are then lowered as a unit into the wellhead housing 90 (Figure 3) until the hanger shoulder 94 lands on the upper annular surface 96 of a previously installed casing hanger 98 or on a landing seat (not shown) in the housing bore. The running string is then rotated to the right, simultaneously rotating the tool's inner mandrel 12 to the right and causing it to thread downwardly with respect to the locking mandrel 24 until the breech block thread system 68 is disengaged. Stop lug 64 is then used to guide stop key 60 into groove 64a, rotation of the running string ceasing. As the inner mandrel moves further downward it causes the outer body 16 and packoff 34 to likewise descend until the packoff lands on the outer frusto-conical surface 100 of the casing hanger 40.The weight of the running string, the inner mandrel 12 and the outer body 16 are then imposed through the outer sleeve 20 and a packoff-to-wellhead lockdown ring 101 onto a packoff energising mandrel 104, energises a packoff seal 106 into sealing engagement with the hanger 40 and the housing 90.

When the downward force on the outer body 16 exceeds the strength of the shear pins 22 these pins shear, letting the outer body 16 and inner mandrel 12 continue to descend and drive the packoff locking mandrel 102 downward. This downward force on the outer body 16 is produced by closing the blow out preventer (BOP) rams or the annular (neither shown) around the running string and pressurising the annular space between the tool and the preventers. All the elements of the packoff assembly 34, except the seal 106, move further downward until the packoff's wellhead lockdown ring 101 is aligned with a wellhead housing groove 91 and the packoff's hanger lockdown ring 107 is aligned with an annular groove 41 on the hanger 40, whereupon the ring 101 expands into the groove 91 and the ring 107 contracts into the groove 41 as the locking mandrel 102 moves even further downward, locking the packoff to the wellhead housing and the hanger (Figure 3). At this point the casing hanger 40 and the packoff 34 are fully installed in the wellhead housing 90. When the packoff 34 is in Stt position (Figure 3) the location of the outer body 16 is such that the packoff lock pins 32 are retracted into the annular groove 25 in the locking mandrel 24, releasing the tool 10 from the packoff.

The running tool 10 is then disengaged from the packoff 34 and hanger 40 by lifting straight up on the running string.

As the inner mandrel 12 rises it carries the outer body 16 upward. When the breech block threads 72 of the inner mandrel contact the threads 70 of the locking mandrel the locking mandrel moves upward from behind the lock ring 36, permitting the ring to retract out of the hanger groove 38 and releasing the tool from the hanger. Continued upward motion causes a shoulder 13 on the inner mandrel to contact a shoulder 29 on the inner body, lifting the tool out of the hanger. The tool can then be retrieved to the surface by continued lifting, without any need for rotation, of the running string.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention, as defined in the claims.

Claims

CLAINS

1. A well tool for running a casing hanger and an annulus packoff into a wellhead housing, said tool comprising a mandrel for connection to a pipe running string, means to releasably attach an annulus packoff to the tool and means to releasably attach a casing hanger to the tool; the tool being operable to land a casing hanger carried by the hanger attachment means in a wellhead housing, subsequent rotation of the mandrel relative to the hanger attachment means causing release of the hanger, and permitting downward movement of an annulus packoff carried by the packoff attachment means to land and set the packoff between the hanger and the wellhead housing, said downward movement also causing release of the packoff from the packoff attachment means, permitting the tool to be withdrawn upwardly from the wellhead housing.

2. A well tool according to claim 1, wherein the mandrel comprises a tubular inner mandrel with means to connect it to a pipe running string; the tool further comprising an annular outer body surrounding the inner mandrel; a tubular locking mandrel surrounding the inner mandrel; a tubular inner body within the locking mandrel; and means selectively operable to prevent relative rotation between the outer body and the locking mandrel.

3. A well tool according to claim 2 including interconnecting means to rotatably inter-connect the inner mandrel and the locking mandrel.

4. A well tool according to claim 3 wherein the interconnecting means comprises a thread system.

5. A well tool according to claim 3 wherein the inter connecting means comprises a breech-block thread system.

6. A well tool according to claim 3 wherein the interconnecting means comprises breech-block threads and conventional threads on both the inner and locking mandrels.

7. A well tool according to claim 6 wherein the breech-block and conventional threads are positioned to facilitate continuous threading of the inner mandrel threads into the locking mandrel threads.

8. A well tool according to claim 6 or 7 wherein the breechblock threads on the inner mandrel are positioned in axial opposition to the breech-block threads on the locking mandrel, such that engagement of the breech-block threads can be accomplished prior to engagement of the continuous threads.

9. A well tool according to any of claims 2 to 8 including anti-rotation means to prevent rotation of the inner body with respect to the casing hanger in use.

10. A well tool according to any of claims 2 to 9 wherein the inner body and casing hanger anti-rotation means comprises at least one spring-based anti-rotation pin in the inner body.

11. A well tool according to any of claims 2 to 11 including anti-rotation means to prevent rotation of the inner body with respect to the locking mandrel.

12. A well tool according to claim 11 wherein the antirotation means comprises at least one anti-rotation key fixed to the inner body.

13. A well tool according to any of claims 2 to 12 wherein the means selectively operable to prevent relative rotation between the outer body and the locking mandrel comprises at least one anti-rotation pin selectively engageable in at least one corresponding slot, said slot and pin being provided on respective ones of the outer body and locking mandrel.

14. A well tool according to any of claims 2 to 13 wherein the means to attach an annular packoff to the tool comprises at least one radially movable lock pin in the outer body.

15. A well tool according to any of claims 2 to 14 wherein the means to attach a casing hanger to the tool comprises a split lock ring.

16. A well tool according to claim 15 wherein the lock ring is biased towards its contracted condition and expands therefrom in response to a force exerted by the locking mandrel.

17. A well tool according to any of claims 2 to 16 wherein the outer body is rotatably connected to the inner mandrel.

18. A well tool according to any of claims 2 to 17 including an outer sleeve shearably connected to the outer body.

19. A well tool according to any of claims 2 to 18 including shoulder means on the inner mandrel and co-operating shoulder means on the inner body to limit axial movement of the inner mandrel in one direction with respect to the inner body.

20. A well tool according to any of claims 2 to 19 wherein the means selectively operable to prevent relative rotation between the outer body and the locking mandrel comprises at least one anti-rotation pin in the outer body, wherein the means to attach a packoff to the tool comprises at least one lock pin in the outer-body, and wherein said outer body antirotation pin and said packoff attachment lock pin are actuated to prevent rotation between the outer body and the locking mandrel and to attach the packoff to the outer body respectively by rotation of said outer body with respect to the locking mandrel.

21. A well tool according to claim 20 wherein the inner body includes at least one axial slot into which either the outer body anti-rotation pin or the packoff attachment lock pin extends depending upon the location of said pins with respect to said slot.

22. A well tool according to claim 20 wherein the locking mandrel includes a circumferential groove alignable with the packoff attachment lock pin by axial movement of the locking mandrel with respect to the outer body so as to permit withdrawal of the packoff attachment lock pin and disengagement of the packoff from the tool.

23. A well tool for running a casing hanger and an annulus packoff into a wellhead housing substantially as shown in or as described with reference to the drawings.