EP0471588A1 - Grappins - Google Patents

Grappins Download PDF

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Publication number
EP0471588A1
EP0471588A1 EP91307588A EP91307588A EP0471588A1 EP 0471588 A1 EP0471588 A1 EP 0471588A1 EP 91307588 A EP91307588 A EP 91307588A EP 91307588 A EP91307588 A EP 91307588A EP 0471588 A1 EP0471588 A1 EP 0471588A1
Authority
EP
European Patent Office
Prior art keywords
cam sleeve
grapple
outer housing
mandrel
movement
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP91307588A
Other languages
German (de)
English (en)
Inventor
Kenneth Alexander Murray
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tri State Oil Tool UK Ltd
Tri State Oil Tools Inc
Original Assignee
Tri State Oil Tool UK Ltd
Tri State Oil Tools Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tri State Oil Tool UK Ltd, Tri State Oil Tools Inc filed Critical Tri State Oil Tool UK Ltd
Publication of EP0471588A1 publication Critical patent/EP0471588A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B29/00—Cutting or destroying pipes, packers, plugs or wire lines, located in boreholes or wells, e.g. cutting of damaged pipes, of windows; Deforming of pipes in boreholes or wells; Reconditioning of well casings while in the ground
    • E21B29/12—Cutting or destroying pipes, packers, plugs or wire lines, located in boreholes or wells, e.g. cutting of damaged pipes, of windows; Deforming of pipes in boreholes or wells; Reconditioning of well casings while in the ground specially adapted for underwater installations
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B31/00—Fishing for or freeing objects in boreholes or wells
    • E21B31/12—Grappling tools, e.g. tongs or grabs
    • E21B31/16—Grappling tools, e.g. tongs or grabs combined with cutting or destroying means
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B31/00—Fishing for or freeing objects in boreholes or wells
    • E21B31/12—Grappling tools, e.g. tongs or grabs
    • E21B31/20—Grappling tools, e.g. tongs or grabs gripping internally, e.g. fishing spears

Definitions

  • This invention relates to grapples, and relates more particularly but not exclusively to a form of grapple known as a "spear", for grappling tubular items in wells.
  • wellhead cut and pull spear essentially comprises a wellhead grapple above a casing cutter.
  • the tool assembly is lowered onto the wellhead such that the cutter penetrates down into the casing while the grapple latches onto the wellhead.
  • a lifting force is applied to the tool assembly to take the weight of the wellhead, and at the same time, at least the lower end of the tool assembly is rotated to cause the cutter to sever the casing and thus detach the wellhead from the casing.
  • the tool assembly is then raised to the surface, along with the wellhead.
  • Proposals have been made for wellhead cut-and-pull spears, but existing commercial forms of such spears suffer from certain disadvantages, such as the likelihood of damage being caused to critical parts of the wellhead, restriction on throughflow of mud tending to allow cuttings to jam the tool against correct operation, and excessively large overall dimensions, particularly where the wellhead is externally grappled.
  • Other disadvantages of known spears include complexity leading to high costs and maintenance difficulties, low reliability, limited load capacities and damage vulnerability.
  • a grapple for internally grappling a tubular article comprising an elongate member having a central throughbore and arranged for connection to a drill string and to a working device, the member being rotatably slidably mounted within an intermediate member and provided with a selectively engageable clutch means for rotation thereof, said intermediate member being rotatably slidably disposed within an outer body by virtue of key members on said intermediate member extending into L shaped slots on said outer body and having tapered means arranged to cooperate with engagement dogs extending through said outer body selectively to bias said engagement dogs outwardly for engagement with said tubular article, the arrangement being such that in a first position of said key members the intermediate member and the outer member are restrained against relative slidable movement such that the engagement dogs are not biased outwardly and on rotation of the intermediate member by the drive member through the selectively engageable clutch means a second position of the key members is obtained which permits relative slidable movement of the intermediate member and the outer member so that the tapered means on the intermediate member
  • a grapple for internally grappling a tubular article comprising a coaxial assembly of a hollow tubular mandrel, a cam sleeve, and an outer housing, said hollow tubular mandrel having an upper end formed as a drillstring coupling for attachment to a drillstring and a lower end formed as a tool coupling for attachment of a cutting tool thereto, said hollow tubular mandrel having a bore extending between said couplings and adapted to carry a fluid flow therethrough, said cam sleeve being mounted on the periphery of said mandrel for rotational and longitudinal movements of said cam sleeve with respect to said mandrel, said outer housing being mounted on the periphery of said cam sleeve for rotational and longitudinal movements of said outer housing with respect to said cam sleeve, clutch means on said mandrel and on said cam sleeve, said clutch means being adapted to engage upon longitudinal movement of said mand
  • Said camming surface means preferably comprises at least one tapered surface on the periphery of said cam sleeve, said at least one tapered surface preferably being frusto-conical about an axis substantially coincident with the longitudinal axis of said cam sleeve.
  • Said camming surface means more preferably comprises at least two tapered surfaces, each said tapered surface being frusto-conical about a common axis substantially coincident with the longitudinal axis of said cam sleeve, a first of said at least two tapered surfaces having a relatively high cone angle, a second of said at least two tapered surfaces having a relatively low cone angle, said radially movable dog means interacting upon relative longitudinal movement of said cam sleeve with respect to said outer housing in said one direction of such relative movement initially with said first tapered surface and subsequently with said second tapered surface to cause said radially outward movement of said dog means initially to be relatively rapid and subsequently to be relatively slow with a concomitant increase in the mechanical advantage of radially outward forces exerted by said dog means with respect to longitudinal force exerted on said cam sleeve.
  • Said radially movable dog means preferably comprises a plurality of dogs individually radially slidable in a respective one of a like plurality of radial passages in and circumferentially distributed around said outer housing.
  • Each said dog is preferably shaped at the inner end thereof substantially to conform to the shape of the underlying camming surface means whereby to distribute pressure stresses between the inner ends of said dogs and said camming surface means in operation of said grapple and to minimise concentration of such pressure stresses.
  • Each said dog is preferably shaped at the outer end thereof by one or more projections and one or more intervening indentations to engage a corresponding series of indentations and intervening projections on the interior of said tubular article.
  • said corresponding series of indentations and intervening projections may be constituted by at least one circumferential groove formed in said cylindrical bore, the outer end of each said dog being shaped accordingly.
  • Said plurality of dogs may number four, and said plurality of radial passages in said outer housing likewise number four, said four radial passages being circumferentially distributed around said outer housing at mutual spacings of substantially ninety degrees with respect to the longitudinal axis of said outer housing.
  • Said clutch means preferably comprises a plurality of axially projecting teeth circumferentially distributed around the upper end of said cam sleeve, and a like plurality of axially projecting teeth circumferentially distributed around the lower end of a shoulder on said mandrel, the two sets of said teeth being formed for mutual interengagement upon said engagement of said clutch means rotationally to lock said cam sleeve to said mandrel while said clutch means is engaged.
  • Said relative movement limit means preferably comprises at least one L-shaped slot on one of said cam sleeve and said outer housing and at least one radially extending projection on the other of said cam sleeve and said outer housing, the or each said L-shaped slot having two arms mutually conjoint at one end thereof, one said arm extending longitudinally and the other said arm extending circumferentially, said radially extending projection radially extending into said L-shaped slot to limit relative movement of said cam sleeve and said outer housing to a slot limited range of relative axial movement while said projection lies within said longitudinally-extending arm of said slot and to a slot-limited range of relative rotational movement while said projection lies within said circumferentially-extending arm of said slot.
  • Said relative movement limit means more preferably comprises a diametrically-opposed pair of such L-shaped slots formed in said outer housing and a diametrically-opposed pair of radially outwardly extending projections on said cam sleeve, said cam sleeve and said outer housing being mutually disposed such that said projections each extend into a respective one of said L-shaped slots.
  • Said cam sleeve and said outer housing preferably have torque-transmitting means formed thereon and arranged to transmit torque therebetween while said relative movement limit means is effective to limit relative movement therebetween to relative movement substantially only in said longitudinal direction.
  • Said torque-transmitting means is preferably arranged for rotational disengagement of said cam sleeve from said outer housing while said relative movement limit means is effective to limit relative movement therebetween to relative movement substantially only in said rotational direction.
  • Said torque-transmitting means preferably comprises key-and-slot dog clutch means arranged with key means on one of said cam sleeve and said outer housing and slot means on the other of said cam sleeve and said outer housing, said key means entering said slot means substantially when said cam sleeve commences to undergo longitudinal movement in said one direction with respect to said outer housing thereupon to clutch said cam sleeve to said outer housing for torque transmission therebetween.
  • said key means comprises a plurality of radially outwardly projecting keys mounted on and circumferentially distributed around said cam sleeve
  • said slot means comprises a like plurality of axially extending slots formed on a radially interior surface of said outer housing and circumferentially distributed therearound at locations thereon to match the circumferential distribution of said keys on said cam sleeve, said keys and said slots being mutually dimensioned for said keys to enter and axially slide within said slots.
  • Said cam sleeve is preferably mounted on the periphery of said mandrel by interposed bearing means sustaining said rotational and longitudinal movement of said cam sleeve with respect to said mandrel.
  • Said bearing means preferably comprises at least one cylindrical bearing bush mounted on an inner surface of said cam sleeve and bearing on an underlying cylindrical portion of the periphery of said mandrel. More preferably, said cam sleeve comprises at least two such bearing bushes, one said bearing bush being mounted adjacent each of the axially opposite ends of said cam sleeve.
  • the or each said bearing bush is preferably formed of a phosphor bronze.
  • Axial bearing means are preferably interposed between said cam sleeve and said mandrel to be effective to transmit axial loads therebetween upon relative rotation thereof while said mandrel is at the limit of movement thereof in said direction opposite to said one direction with respect to said cam sleeve.
  • Said axial bearing means preferably comprises an annulus of bearing metal encircling said mandrel at a location between the lower end of said cam sleeve and an upper end of a lower shoulder on said mandrel.
  • Said bearing metal may be a phosphor bronze.
  • Said outer housing is preferably provided with an axial stop means to limit axial insertion of said grapple into said tubular article, preferably to an extent that locates said dog means substantially opposite a grappling formation in the bore of said tubular article.
  • Said axial stop means preferably comprises at least one radial projection on and extending radially outwards of said outer housing to a position where said at least one projection will abut an adjacent end of the tubular article into which said grapple is inserted in use thereof.
  • Said axial stop means preferably comprises an annular shoulder encircling the periphery of said outer housing.
  • Said annular shoulder is preferably mounted on said outer housing such that its longitudinal position thereon is adjustable, or such that a given said shoulder is detachable and replaceable by another such shoulder having a lower end face thereof at a different longitudinal position on said outer housing, whereby in either case to provide for selective adjustment of the predetermined maximum insertion of said grapple into said tubular article.
  • FIG. 1A this illustrates the left half of a longitudinal sectional elevation of a first embodiment of grapple 10 in accordance with the present invention in its "release" or non-grappling operative condition, i.e. the configuration in which the grapple 10 is lowered onto a wellhead 12 for retrieval thereof.
  • the grapple 10 is generally circularly symmetrical about its longitudinal axis (denote CL-CL in Fig. 1) and comprises the coaxial assembly of a mandrel 14, a cam sleeve 16, and an outer housing 18.
  • the mandrel 14 is a hollow tubular article composed of a main part 20 having a smooth cylindrical periphery 22, and an upper sub 24 connected to the main part 20 by a standard taper-thread connector 26.
  • the upper end of the sub 24 is formed as a standard taper-thread drillstring connector 28 for attachment of the grapple 10 to the lower end of a drillstring (not shown).
  • the lower end of the mandrel main part 20 is formed as a standard taper-thread connector 30 for attachment of a cutting tool (not shown) beneath the grapple 10 in use thereof, the fishing tool either being connected directly to the lower mandrel connector 30 or through the intermediary of a sub (not shown).
  • the cam sleeve 16 is substantially cylindrical, except for an intermediate section 32 of its periphery, which is conically tapered in a manner and for a purpose which will be detailed subsequently.
  • the cam sleeve 16 is mounted on the cylindrical mandrel periphery 22 for relative longitudinal and rotational movement thereon by means of interposed phosphor-bronze bearing bushes 34 and 36 mounted on the inner surface of the cam sleeve 16 respectively adjacent the upper and lower ends thereof.
  • the mandrel main part 20 has a shoulder 38 near its lower end, the shoulder 38 presenting a flat radial upwardly-directed upper surface.
  • a phosphor-bronze annulus 40 is located around the mandrel periphery 22, between the upper surface of the mandrel lower shoulder 38 and the lower end of the cam sleeve 16.
  • the annulus 40 acts as an axial thrust bearing by which the mandrel 14 can be lifted and rotated while the cam sleeve 16 is stationary and anchored during grappling operation of the grapple 10, as will subsequently be detailed with reference to Fig. 1B.
  • the upper end of the cam sleeve 16 is formed as a radially-enlarged shoulder 41 which is castellated to form a uniformly circumferentially distributed array of upwardly directed dog-clutch teeth 42.
  • the mandrel upper-sub 24 has a lower end shoulder 44 formed with a similar array of uniformly circumferentially distributed and downwardly directed dog-clutch teeth 46.
  • the cam sleeve 16 is at its longitudinally uppermost position along the mandrel periphery 22, such that the cam sleeve teeth 42 and the mandrel teeth 46 clutch together to dog or lock the cam sleeve 16 and the mandrel 14 against mutual relative rotation.
  • the clutch constituted by the two sets of teeth 42 and 46 disengages by longitudinal axial separation of these teeth, thereby to free the mandrel 14 for subsequent rotation within and relative to the cam sleeve 16, as will subsequently be detailed.
  • the upper sleeve shoulder 41 prevents the cam sleeve 16 being driven down through the outer housing 18 by the weight of the mandrel 14.
  • the outer housing 18 is a hollow cylindrical article which mounts on the periphery of the cam sleeve 16 for relative axial and longitudinal movement thereon, within limits defined by a relative movement limiter constituted by a diametrically opposed pair of L-shaped slots 48 formed in an upwardly extending skirt 50 of the housing 18, in operative combination with a diametrically opposed pair of radially outwardly projecting keys 52 rigidly secured to the cam sleeve 16.
  • Each of the L-shaped slots 48 comprises a vertical arm extending longitudinally along the housing skirt 50 from adjacent the upper end thereof towards the lower end of the skirt 50 where the vertical arm is contiguous with a horizontal arm of the slot 48, this horizontal arm extending circumferentially around the skirt 50 from its junction with the vertical arm in a direction which is clockwise as viewed from above the grapple 10 and looking downwards thereon.
  • the keys 52 each project into a respective one of those L-shaped slots 48 such that with respect to the outer housing 18, movement of the cam sleeve 16 is either a short-range slot-limited vertical (longitudinal) movement or a short-range slot-limited rotational movement about the common longitudinal central axis of the main grapple components 14, 16 and 18.
  • the interior surface of the lower end of the outer housing 18 is formed with a circumferentially distributed array of axially extending slots 54 (preferably four in number and mutually spaced by ninety degrees).
  • a matching array of keys 56 is rigidly secured to the lower end of the cam sleeve 16.
  • the cam sleeve keys 56 become rotationally aligned with and then axially enter the axial slots 54.
  • the combination of the housing slots 54 and the sleeve keys 56 provides a torque-transmitting function in the manner of a dog clutch by which the cam sleeve 16 and the outer housing 18 are mutually rotationally locked for the transmission of torque therebetween (i.e. there is further augmentation of the relative positional limits provided by the L-shaped slots 48 and the keys 52).
  • the outer housing 18 is formed with four radially extending passages 58 mutually spaced at ninety degrees around the housing 18.
  • Each of the four radial housing passages 58 holds a respective radially slidable dog 60 in a position which radially overlies the tapered portion 12 of the cam sleeve 16.
  • the radially inner end 62 of each dog 60 is shaped in a manner detailed below to conform to the taper shape of the underlying tapered portion 12 of the cam sleeve 16.
  • each dog 60 is formed with a pattern of circumferential projections and alternating grooves that matches a corresponding pattern of circumferential grooves 66 (and intervening effective projections) that circumscribe the bore 68 of the tubular wellhead 12 for the purposes of grappling thereof in a wellhead retrieval procedure that will be detailed subsequently.
  • the tapered portion 32 on the periphery of the cam sleeve 16 is formed at its longitudinally upper end with a reduced-diameter cylindrical portion that accepts radially-retracted dogs 60 when the cam sleeve 16 is in longitudinally lower position with respect to the outer housing 18 as shown in Fig. 1A.
  • the cylindrical portion merges into a longitudinally short but relatively high cone angle taper portion angled e.g. at thirty degrees, which functions to "kick" the dogs 60 radially outwards as the cam sleeve 16 starts to more longitudinally upwards within the outer housing 18.
  • the "kick” taper merges into a longitudinally longer and relatively low cone angle wedging taper (angled e.g. at three degrees) which forces the dogs 60 radially outwards through the housing passages 58 with a relatively high mechanical advantage as the cam sleeve 16 undergoes further longitudinal lifting movement within the outer housing 18 to reach the grappling configuration illustrated in Fig. 1B.
  • Such wedging action on the dogs 60 forces their outer ends 64 into firm grappling contact with the wellhead grappling grooves 66 to anchor the dogs 60 and hence the grapple 10 as a whole to the wellhead 12 to enable the grapple 10 to apply a substantial lifting force to the wellhead 12 during recovery thereof.
  • a modified and preferred form of the tapered portion 32 of the cam sleeve 16 will subsequently be detailed with reference to Fig. 3).
  • the outer housing 18 is fitted with a radially projecting annular shoulder 70 detachably secured to the outer housing 18 by means of fasteners 72.
  • the lower end face of the housing shoulder 70 is located at just such a position that when the grapple 10 is lowered into the wellhead bore 68 until the shoulder 70 abuts the rim of the wellhead 12, the dogs 60 will be longitudinally directly opposite and substantially perfectly aligned with the wellhead grappling grooves 66 for reliable grappling engagement therewith in subsequent operation of the grapple 10.
  • the shoulder 70 can be detached by removal of its fasteners 72 and replaced by another and suitably dimensioned shoulder.
  • the outer ends 64 of the dogs 60 can be detached and replaced by suitably different grappling projections/indentations (e.g. see Fig. 3) or any other appropriate forms of grappling contacts.
  • Fig. 2 is a transverse cross-section of the grapple 10 (to an enlarged scale) taken on the line II-II in Fig. 1, i.e. at the level of the dogs 60, to illustrate the overall cross-sectional shape of the grapple 10 at this level.
  • the grapple 10 is viewed from above in a position of superimposition on top of the wellhead 12.
  • the grapple 10 is compact (by comparison to prior art grapples) with low overall dimensions, particularly in respect of diameter. This facilitates handling and deployment of the grapple 10.
  • a cutting tool (not shown), e.g. an array of radially extendible cutting knives, is attached to the tool connector 30 at the lower end of the mandrel 14, and the assembly of the grapple 10 with the cutting tool is attached to the lower end of a drillstring (not shown) by means of the drillstring connector 28 at the upper end of the mandrel 14.
  • the grapple 10 is initialised by lifting and turning the outer housing 18 with respect to the cam sleeve 16 such that the torque-transmitting keys 56 come downwards out of the axial slots 54, and the movement-limiting keys 52 move to the blind (clockwise) ends of the L-shaped slots 48.
  • the bottom end of the cam sleeve 16 will be resting on the mandrel shoulder 18 through the interposed bearing annulus 40.
  • the initialised grapple 10 is then lowered on the end of the initially non-rotating (or slowly clockwise-rotating) drillstring onto the wellhead 12 such that the cutting tool and then the lower end of the grapple 10 enter the wellhead bore 68, wellhead penetration progressing until the housing shoulder 70 abuts the rim of the wellhead 12 to halt further downward movement of the outer housing 18 and the cam sleeve 16.
  • the mandrel 14 lowers further with respect to the sleeve 16 and the housing 18, until the teeth arrays 42 and 46 dog together.
  • the grapple 10 is now in the wellhead-relative position and configuration shown in Fig. 1A.
  • the drillstring is now turned anti-clockwise (as viewed from above and looking downwards) by a small amount sufficient to bring the keys 52 out of the blind ends of the horizontal arms of the L-shaped slots 48 and under the contiguous lower ends of the vertical arms of the slots 48, the temporary meshing of the teeth arrays 42 and 46 producing the requisite rotation of the cam sleeve 16 relative to the outer housing 18.
  • the drillstring is lifted a small amount to bring the keys 52 up the vertical arms of the L-shaped slots 48 and simultaneously cause the torque-transmitting keys 56 to enter the axial slots 54.
  • the grapple 10 is now fully grappled to the wellhead 12, mud is pumped down the central through bore 74 of the mandrel 14 to extend the cutters of the cutting tool and provide for effective clearance of cuttings, and normal clockwise rotation of the drillstring is commenced while lift is maintained to sustain the weight of the wellhead 12. While the casing is being cut through beneath the wellhead, the axial thrust exerted on the cam sleeve 16 and on the outer housing 18 by the continuous lifting force maintained on the drillstring is borne by the axial-thrust bearing annulus 40. Free rotation of the mandrel 14 within the currently stationary cam sleeve 16 is enabled by the bearing bushes 34 and 36.
  • the torque transmitting combination of the slots 54 and the keys 56 rotationally clutching the cam sleeve 16 to the outer housing 118 relieves any mandrel-rotation-induced rotary drag on the cam sleeve 16 from producing potentially damaging stresses on the relative-motion-limiting keys 52 within the vertical arms of the L-shaped slots 48.
  • the upper sleeve shoulder 41 relieves the keys 52 and the slots 48 of the weight and down forces, of the mandrel 14 when the grapple 10 is in its Fig. 1A "release" configuration.
  • the full-sized bore 74 through the mandrel 14 enables a copious supply of mud to the cutting tool to flush out the casing cuttings and so obviate a build-up of cuttings that might jam the grapple 10 against proper operation (e.g. intentional sub-surface release).
  • drillstring rotation is halted, the cutters are retracted, and the wellhead is recovered by lifting the drillstring with the new-detached wellhead 12 remaining attached to the grapple 10.
  • a further advantage of the form of grapple 10 lies in the requirement for making and un-making only the single connection 26 between the mandrel main part 20 and the mandrel upper sub 24 to enable the major components (14, 16, 18) of the grapple to be assembled and dismantled.
  • Fig. 3 shows a modified and preferred form of the tapered portion 32 on the cam sleeve 16, and the correspondingly modified inner end of the dog 60.
  • Fig. 3 shows only the left half of a longitudinal sectional elevation of the modified form of the cam sleeve 16, together with the adjacent parts of the outer housing 18 and the wellhead 12, the (unmodified) mandrel 14 being omitted from Fig. 3.
  • the keys 52 and 56 are also omitted from Fig. 3.
  • the inner end of the modified dog 60 is formed with an upper shoulder 80 dimensioned to abut the high-cone-angle "kick" taper 82 when the modified dog 60 has been radially extended through the respective radial passage 58 in the outer housing 18 by relative upward movement of the cam sleeve 16, to an extent deemed to be an upper limit on such radial extension of the dog, beyond which contact stresses between the dog and the cam sleeve would tend to be excessive and possibly lead to seizure preventing reliable release of the grapple.
  • the dog shoulder 80 thus positively prevents such excessive relative movement of the cam sleeve 16 and thereby obviates the possibility of seizure.
  • the cylindrical upper portion 84 of the tapered portion 32 on the cam sleeve 16 is modified by being provided with an uppermost portion 86 of a further-reduced diameter, in order to accommodate the dog shoulder 80 when the cam sleeve 16 has fully descended (relative to the outer housing 18) and the modified dog 60 is fully retracted radially inwards of the outer housing 18.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Mining & Mineral Resources (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Marine Sciences & Fisheries (AREA)
  • Earth Drilling (AREA)
EP91307588A 1990-08-16 1991-08-16 Grappins Withdrawn EP0471588A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9018018 1990-08-16
GB909018018A GB9018018D0 (en) 1990-08-16 1990-08-16 Wellhead cut and pull spear

Publications (1)

Publication Number Publication Date
EP0471588A1 true EP0471588A1 (fr) 1992-02-19

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ID=10680774

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91307588A Withdrawn EP0471588A1 (fr) 1990-08-16 1991-08-16 Grappins

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EP (1) EP0471588A1 (fr)
GB (1) GB9018018D0 (fr)
NO (1) NO913216L (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2335937A (en) * 1998-04-01 1999-10-06 Baker Hughes Inc A wellhead retrieval tool
CN112041536A (zh) * 2018-02-19 2020-12-04 斯伦贝谢技术有限公司 用于井下装置的模块化机电组件

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2687324A (en) * 1951-08-13 1954-08-24 Grunsky Charles Pipe puller
US4273372A (en) * 1978-09-14 1981-06-16 Standard Oil Company (Indiana) Apparatus for use in lowering casing strings
EP0154520A2 (fr) * 1984-03-02 1985-09-11 Smith International (North Sea) Limited Harpon pour la récupération d'objets tubulaires dans un puits de forage
GB2178093A (en) * 1985-07-18 1987-02-04 Smith International Releasable spear for retrieving a hollow member from a well bore

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2687324A (en) * 1951-08-13 1954-08-24 Grunsky Charles Pipe puller
US4273372A (en) * 1978-09-14 1981-06-16 Standard Oil Company (Indiana) Apparatus for use in lowering casing strings
EP0154520A2 (fr) * 1984-03-02 1985-09-11 Smith International (North Sea) Limited Harpon pour la récupération d'objets tubulaires dans un puits de forage
GB2178093A (en) * 1985-07-18 1987-02-04 Smith International Releasable spear for retrieving a hollow member from a well bore

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2335937A (en) * 1998-04-01 1999-10-06 Baker Hughes Inc A wellhead retrieval tool
US6056049A (en) * 1998-04-01 2000-05-02 Baker Hughes Incorporated Wellhead retrieving tool
GB2335937B (en) * 1998-04-01 2000-07-12 Baker Hughes Inc Wellhead retrieving tool
CN112041536A (zh) * 2018-02-19 2020-12-04 斯伦贝谢技术有限公司 用于井下装置的模块化机电组件
CN112041536B (zh) * 2018-02-19 2023-03-10 斯伦贝谢技术有限公司 用于井下装置的模块化机电组件

Also Published As

Publication number Publication date
NO913216D0 (no) 1991-08-16
GB9018018D0 (en) 1990-10-03
NO913216L (no) 1992-02-17

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