CA2496102A1 - Casing clamp - Google Patents

Abstract

A clamp for gripping casing strings is disclosed, A series of radially arranged spring biased slips are mounted in a housing attached to a top drive. A
hydraulic system is used to release the slips from the gripping position upon a casing string.

Description

CASINQ CLAMP ' ~i~,id of tfie inv ,nl~jan:
s The present invention relates to a device for driving and handling a drilistring, and, in particular, far manipulating a casing string in a casing drilling environment, i~f~kg~round of the rove io °
:o The drilling of wells, such as those 'or oil and gas often use a top drive to turn the drillstring. Tire quill of the top drive typically threads into the box end of the top Joint of pipe used fur drilling and in turn drives the pipe. The problem encountered is that there is potential for damage to the threads of both the drill pipe and the top drive quill.
Galling of the threads is undesirable; since they have to be machined to correct the 13 damage, which is time consuming a.nd costly, especially glvorr the typically r~mote locations that wells are drilled in. it is especially desirable to avoid damaging the threads on the top drive, since they are much mare difficult and expensive to repair than drill pipe.

2~ With the development of drilling With casing, that is using a casing string as the drill pipe, the issue of thread protection has become much mare important, This is because the thread form used in casing connections is more fragile than the connections used in drill pipe, and the casing connections have: to remain f!~.~id and pressure tight once the drilling process has been completed. Other considerations are 2s that casing typically has a thinner side~wail and is less robust than drill pipe. This is especially true in the thread area, where the casing has thre2~ds an both ends, 4vith a corresponding r~ductian in section area.
While some clamps are available for gripping casing, these clamps grip the casing ort 3o the inside using expandable jaws. These clamps are therefore not suiteblc for use ir;
manipulating casing during a casing drillir;g operation. The rxpandabs'e jaws create a severe restriction on the casing's inner diameter wni;,h restricts mud flaw dow:~hoie, for example, to a dounhofe motor which may restrict the amount of power the motor is capable of producing. In addition, the jaws are not fail safe, since a biasing aget-~t must be ccmtinuo~rsly applied to maintain gripping forc~. Prior casing clamps had na means for passing fluids to the casing bare and had no means for manipulating the s casing sirr~ultaneousiy in vertical and rotational dire~ions.
Other prior methods of h2~ndling casing involved using the kelly or top drive to turn the casing, with ttie attendant risk of damage to the threaded Connections. A
safer and more efficient system of driving a casing string is needed, ~o ;~ m a ~of ~,e inve~ttion:
The present invention provides a clamp for driving a drillstring where the driltstring is formed of casing pipe. While the clamp is described herein exclusively for use with i < casing, it should be understood that the clamp might be used in other applications. By utilising a casing clamp device of the present invention, the risk of damage to the threaded connection on the ends of the casing is minimised. The clamp indudes a sealing element to enable driEling mud to be pumped down the centre of the pipe while rotating the pipe during drilling operations. In addition, the olamp permits ao simultaneous di$pfacer,~ent of the pipe, either up ar down, while rotating it, which is an essential requirement of dri6l~ng.
In accordance with a broad aspect of the present invention, there is provided a clamp for use with a top drive for gripping and turning a drifiatring formed of pipe, the clamp s: comprising: slips positioned to grip the pipe, drive method for moving the slip blocks and dies radiaily inwardly into a pipe gripping position and radially outwardly to a pipe releasing position, and an attachment method for connecting the apparatus to a top drive.
3o The slips are preferably farmed, for example including a toothed or otherwise knurled face, to enhance their engagement against the outer surface of a pipe. The slips can be replaceable to accommodate different sizes of pipe and to enable the gripping surface to be renewed as it wears In one embodiment, the slips carry slip dies. The slip dies are selected to engage a pipe disposed between the slips and, therefore, can be roughened o~ formed with teeth to enhance their engagement with the pipe outer surface. The slip dies can be carried on the slips in such a way as to be replaceable.
s in one embodimFnt, the slips am mounted in a slip bawl and are constrained to mcwe along a conical taper of the slip bawl to, thereby, be moved radially inward and outward relative to the wntre axis of the slip bowl. This permits the slips to be moved to grip or reic~ase a pipe positioned t!~erebetween. The conical taper is positioned to ~o taper down~~ardiy such that as the weight on the pipe increases, the slips will be driven to k.~itn with increased force into the pipe.
The drive method can be any suitabGa means far moving the slips radially inwardly and outwardly" fcr example, in one embodiment along the taper of the slip bowl. in one rs embodiment, tY~e dri~,re r~~ethod includes a biasing agent such as, for example, a plurality cf springs that bias the slips down the taper of the slip bowl such that they ate normally in d pipe gripping, closed position, Thus, unless a farce is applied against the pressure in the biasing agent, the slips remain in a pipe gripping position reducing the chance c~f a ripe being inadvertently released. In order to move the slips to an open zu position to release a pipe, the drive method includes a system for applying force against 'hQ biasing agent. The system for applying force can, for example, use hydraulics.
The clamp is attached to a top drive by an attachment method. The attachment 25 method is selected to be capable of transferring torque from the top drive to the clamp to cause it to rotate. In tine embodiment, a quill adapter is connected to the clamp and formed at its outboard end fUr engagement to the quill of the top drive.
1n rune embodiment, the clamp includes a stabbing spear extending ouf to fit into a ~o pipe and align if with the slips to facilitate grippi;rg. In another embodiment, a drilling fluid conduit ~s provided for conducing a flow of drifting fluid into the longitudinal bore of the pipe. Preferably, the stabbing spear is formed as a conduit so that It can also serve as the drilling fluid conduit. In such an embodiment, the stabbing spear includes seals for acting between the spear and the pipe for restricting the flow of drilling fluid outside of the pipe. The spear also acts a$ a mandrel, enhancing the casing's ability to vrithstand large inward clamping forces without deforming the pipe.
When the clamp is rr~tated, the slips rotate therewith and; therefore, any pipe gripped by the slips is also rotated.
In accordance with arzother broad asper~t of the present invention, there is provided a n method for drilling a well with a well casing as an elongated tubular drill string and a drilling assembly retrievable from the lower distal end of the drill string without withdrawing the drill string from a wellbore being formed by the drilling assembly, the method comprising: providing tire ~~asing as the drill string; providing a drilling assembly connected at the distal end of the drill string and being retrievable through t5 the longitudinal bore of the drill string; gripping the drill string on its outer surface;
inserting the drill string and the drilling assernbly into the wellbore and driving the drilling assembly to operate to farm a wellbore to a diameter greater than the diameter of tha drill string, ~o Preferably the method further includes: removing at least a portion of the drilling assembly from the distal end of the drill sting and moving the at least a portion of the drilling assernbly out of the welibore through the drill string without removing the drill string from the welibore, leaving the drill sf~ing in the wellbvre.
25 The drilling assembly can be any assembly useful for drilling a wellbore through an earth formation. As would be appreciated, the drilling assembly Can include a drill bit and any of, for example, measurement while dritling equipment and a downhole molar.
~o In a preferred embodiments the step of gr ipping the drill string is accomplished by providing a clamp according to the present in°~ention as described hereinbefore.
Preferably. the method further comprises, after the step of inserking; pumping drilling fluid through the longitudinal bore of the drill string. fn one preferred embodiment, tE;e drill string is gripped and rnnved upwardly or do4vnwardly while being rotated.
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Brief descrisitian of the rawirsgs~, A tur'ther, detailed description of the invention, briefly described above, will follow by reference to the following drawing of a specific ernbodirnent of the invention. This 3 drawing depicts only a typical embodiment of the invention, and is therefore not to be considered limiting of its sr.,ope. In the drawings:
Figure 1 ,4 a crass sectional view through a casing clamp according to the prESent invention with the slips (to facilitate understanding only two slips one shown) in the fully : o retracted position, useful during insertion or removal of casing from the clamp.
Figure 2 is a view of the casing clamp of Figure 1 with the slips closed upon a piece of .c acing and ready to drill.
Figure 3 is an end view of a slip die useful in the present invention.
Figure 4 is a plan view of the slip die of Figure 3.
is Figure 5 Is a cross sectional view through another casing clamp including a stabbing spear.
p,~taifed Dgsgr~ption o,~the Present invention:
zo TEye drawing figureC are not necessarily to scale, and certain features are shown in generalised form in the interests of clarity, As shown in Figures 1 to ~. casing clamp 10 according to the present invention is formed to grip a pipe 11 (Figure 3) and to be carr7ed on a top drive (not shown) s~,ch zs as, for example, a model no HMI X00 available from Tesco Corporation. The pipe is a portion of a drill string formed of casing. The casing clamp sewer as a load path to transfer the weight of pipe 11, and the remainder of the drill str ing extending therefrom, to th;~ top drive and to transmit the full torque applied from the top drive to the pipe and therethro~gh to the drilistring.
ao Casing clamp 10 includes an autQr housing 12 having a central axis 13. A quill adapter 1~ is attached to outer housing 12 at its top end and is pos;tioned coaxialiy with rentrai axis ~! 3. At its outbvarcr end 14a, quilt adapter 14 is threaded for threaded connection to a top drive quill snot shownj. The casing clamp is supported by the top drive through uuili adapter 14..
s Housing 12 includes an opening 12a to accept and facilitate posifionfng of the quill adapter in the housing during assarraly Cuill adapter 14 is attached via bolts 15 to housing 12. Bolts 15 thread through aligned hales in pausing 92 and quill adapter 14.
Bolts 15 finally engage in threads formed in inner piston housing 2Z3 disposed vdithin the housing, ire this mounting arrangement, quill adapter 14. is mounted between outer to housing 1?_. and inner piston housing 28.
A slip bowl 1B is rigidly connected to the lower ~:nd of housing 12 by means of incating dowels 18. Slip taowl 18 defines a centre! conical bore 17 That is concentric with central axis 13. Conical l5are 17 is tapered downwardly to define, tar example, a 4:12 ratio ~s taper between the opposing slips, or 2:12 taper for each individual slip.
While only two dowels 1 S are shown, preferably there are eight dowels spaced about the periphery of the slip bcwi. Dowels 18 are removable to facilitate removal of the slip bawl from housing 72. Dowels '18 are formed 'o transfer any weight on the slip bowl tc 2o housing 12. This weight is in turn transferred to the top drive.
Slips 20 are mounted in spaced apart relation about slip bowl 1G. Although only two slips are shown, in the preferred embodiment there are 8 slips. The slips are wedge shaped having substantially flat faces 20a and sloping bac>C surfaces 20b which 2s conform to the taper of conical bore 17. Slips 20 arr~ rnaunted in the slip bawl by dove tailed slots 21 which accept correspondingly shaped extensions 22 formed on the back of the slips. Dove tailed slots 22 extend vertically to permit the slips mounted therein to ride upwardly and downwardiy along the taper of the canicai bore and to, thereby, move radially toward or away frCm central axis 13. When the slip s 2Q
are fit 3o into their slots t1 they can ride afcng thp taper but ar$ subsf~3;~tialy~
prsv~nted frnm rotating relative to the slip bG~~l abaut the central axis. Ta provide fvr lu'arication of the slips, a grease nipple is ; rowided in a bore 23 opening i~yto each slat 21.

Slips 20 are prevented from dropping out of slots 21 by attachment to a ring-shaped push plate 24. Push plate 24 abuts against the upper surface of slip bowl 16 Ilmiting the extent to which slips 20 can move downwardly in their slots. Slips 20 are siidabiy s mounted in slots 25 formed it the push plate and connected to the push plate 24 by means of bolts 68. The bolts are formed to secure the slips from moving along axis i3 " relative to push plate 24, while allowing the slips to move relative to the push plate radlally inwardly and outwardly to accommodate the movement of the slips on the taper. Bolts 6B are accessible through apertures 72 in outer housing 12 when the io slips are In the fully extended position. Also accessible through the apertures T2 are grease nipples 76 for applying grease to slots 25 to lubricate movement between the slips and the push plate, Push piste 24 is connected to a drive means far moving the slips along thr~ir slats. !n is the illustrated embodiment, the drive means inatudes an annular ram 26 onto which push plate 24 is connected as by bolts or welding.
Annular cam 28 extends out from and is selected to ride within a torus shaped chamber 34 defined between housing 12 and inner piston hauslng 28. Chamber 34 zo contains a plurality of compression springs 30 which act between housing 12 and annular ram 26 to bias the annular tern downwardty toward push plate 24, in one embodiment, ten compression springs are spaced apart within the chamber.
Annular ram 26 is prevented from being forced completely out of chamber 34 by abutment against an annular Range 28a on inner piston housing 28. Each compression spring is zs preferably preloaded by use of a iimiter including an end plate 35 and an end cup 36 connected by a drawboit 38, !~nd cup 36 is formed to siidingly accept an end of drawbolt 38, while drawbolt 38 is rigidly connected to end plate , 35.-prQloading facilitates assembly of the clamp and permits the tension in the springs to be selected and adjusted.
The drive means further includes a hydraulic system for driving the slips against the force of springs ~0. In particular, a chamber 76 formed between ram 26, inner piston R
housing 28 and annular filange Z8a acoepts oil through oil supply tube 74 and channel 75. Sea! rings 44, for example, Po'y Pak rings available from Parker Hannifin Carp, Cleveland, Qhiv, ensure that the hydraulic fluid is contained in chamber 76.
Uil supply tuba 74 is .n communication with a connector 7i for connection to an external s hydraulic syster~* (not shown) including hoses, 8 source of hydraulic fluid, pumps and control ~~aives etc. Oii supply Tube 74 is formed of tetesovpically arranged members '78a, 78b such that it can extend between to its fried positions on housing 12 and annular ram 2fr.
ro In operation, slip dies 20 are normally biased toward the closed, oastng gripping position (Figure 2 j by spring pressure exerted through annular ram 26 and push plate 24 to slips 24. it is preferred that the slip dies are biased in this way to provent ;nadvertant release crf pipe 1 t which is gripped therebetween, as well to ensure that the grip upon the pipe w,ll oat slacken off while drilling or tripping.
Applying oil pressure to chamber 78 forces annular ram Z6 upward against the tension in springs ~0. Annular ram 26 draw's push plate 24 and the slips attached thereto upward. To return the slips 20 to the casing gripping made of operation the hydraulic fluid pressure is released through the channel 75 and oil supply tube 74. This permits Zo the tare in springs 3~ to drive the ans~uiar ram and, therr~by the slips, back to the gripping position.
Faces 20a of slips can be formed to engage against pipe 1 ~. However, irr a preferred embodiment as shown, the slips can support slip dies B0, which are knurled or zs roughener td facilitate engagemQnt against pipe 11. Slip dies g0 are preferably remavablr~ so that it is possik~fe to accommodate different sizes of pipe through aiterrvatirrg slip d#e thicknesses andlqr surface curvature, and for repair and replacement. One embad~ment cr a slip die 8t!° is shown in Figures 3 and 4. Slip die 8D' have a herringbone pattern arrange.rnent of elongate teeth $2 so that the casing ~a can be securely gripped wnile troth turning (i.e. rotating it about axis '13) and advancing the casing into t;~e borehole ;i.e. moving the casing along axis 93). Slip dies $0' mount to slips 20 via dovetailed extensions 84 and retaining bolts (not shown).

Threads $6 on riuill adapter 1A~ are formed tc engage a stabbing spear 90, as shown in Figure 5. Stabbing spear 90 extends in alignm~nt with cxntral axis 13 and is sized to fit into the bore of pipe t 1a (shown only as a short piece and including a caupling s threaded thereon). Using spear 90 the pips.to be gripped can be csntrelised as it is being offered up to the clamp. A tapertd ring 91 is mounted at outboard end of stabbing spear 90 to guide the stabbing spear into the bore of the pipe, Stabbing spear 90 includes a bore 92 which, when spear 90 is mounted on threads ~0 86, aligns with bare 93 of quill adapter 14. Together bore 93 and bore 92 act as a conduit through which drilling flusd can bs pumped from the top diive to the bore of pipe 11 and Then downhola. A seal ring 84 on stabbing spear 90 seals to the end of pipe 91. Another seal 96, in the form of a packing cup, is disposed about stab5ing spear 90 and is selected to seal between the stabbing spear and the pipe.
Seals 94 is and 96 act to substantially prevent the leakage of fluid out of pipe 11 as it circulates from quill 14 into the plp~ 1 ? .
The drill string is advanced and rotated by the casing clamp in a manner similar to what is used in canventiona( top drive drifl~ng where the pipe is attached to the top 2o drive and is rotated as well as advanced into the borehole by the top drive. The casing clarr~p is attached through quill adapter end ~14a to the quill of the top drive, and rotates with the top drive's quill. When the drillstring is gripped by the casing clamp, the drillstring rotaies in unison with the top drive. Since the drillstring is securely gripped by the casing clamp the drillstring is eithr~r lowered into or raised out of the 25 welibore as the topdrive is raised or Lowered.
.Although preferred embodirrrents at the present invention have bean described in some detail hereinabove, those skilled in the art will recognise that various substitutions and modifications may be made to the invention without depar<ing from o the scope and spirit oi~ tf!a appended claims.

Claims (15)

1. A clamp for use with a tap drive for gripping and turning a drill string formed of pipe, the clamp comprising: slips positioned to grip the pipe, drive method for moving the slip blocks and ties radially inwardly into a pipe gripping position and radially outwardly to a pipe releasing position, and an attachment method for connecting the apparatus to a top drive.

2. The casing clamp cf claim 1 further comprising slip dies mounted on the sops.

3. The casing clamp of claim 2 wherein the slip dies include a gripping surface, the gripping surface formed to facilitate engagement with a pipe.

4. The casing clamp of claim 1 further comprising a slip bowl including a conical bore formed therethrough , the slips being mounted in the slip bowl and constrained to move along the conical taper of the slip bowl to move radially inward and outward relative to the centre axis of the slip bowl,

5. The casing clamp of claim 4 wherein the conical bore tapers downwardly.

6. The casing clamp of claim 1 wherein the drive method includes a biasing agent for biasing the slips into a pipe gripping position.

7. The casing clamp of claim 5 wherein the drive method includes a biasing agent for biasing the slips dawn along the taper of the slip bowl such that they are normally in a pipe gripping, closed position.

8. The casing clamp of claim 1 wherein the drive method includes a hydraulic system.

9. The casing clamp of Claim 1 further comprising a stabbing spear extending out between the slips and formed to ~t within a pipe to be gripped by the clamp.

10. The casing clamp of claim 1 further comprising a drilling fluid conduit for conducting a flow a drilling fluid from the top drive.

11, The casing clamp of claim 1 wherein the stabbing spear includes a drilling fluid conduit for conducting a flow of drilling fluid from the top drive.

12. A method for drilling a well with a well casing as an elongated tubular drill string and a drilling assembly retrievable from the rower distal end of the drill string without withdrawing the drill string from a wellbore being formed by the drilling assembly, the method comprising: providing the casing as the drill string; providing a drilling assembly connected at the distal end of the drill string and being retrievable through the longitudinal bore of the drill string;
gripping the drill string on its outer surface; inserting the drill string and the drilling assembly into the wellbore and driving the drilling assembly to operate to form a wellbore to a diameter greater than the diameter of the drill string.

13. The method of claim 72 further comprising: removing at least a portion of the drilling assembly from the distal end of the drill string and moving at yeast a portion of the drilling assembly out of the wellbore through the drill string without removing the drill string from the wellbore while leaving the drill string in the wellbore.

14. The method of claim 12 wherein the step of gripping the drill string is conducted using a casing clamp including slips positioned to grip the pipe, drive method for moving the slip blocks and dies radially inwardly into a pipe gripping position and radially outwardly to a pipe releasing position, and an attachment method for connecting the apparatus to a top drive.

15. The method of claim 12 further comprising, after the step of inserting, pumping drilling fluid through the longitudinal bore of the drill string,