Note: Descriptions are shown in the official language in which they were submitted.
CA 02512800 2001-03-22
1
Method and Apparatus for Handling Tubular Goods
Field of the Invention
The manufacture, assembly and use of tubular systems in drilling and
constructing
wells, frequently involves operations where the tubular work piece must be
gripped and
handled to enable the application of axial and torsional loads. Devices
employing jaws,
such as elevators, tongs or pipe wrenches are commonly used to engage the pipe
body
directly, with the risk of damage by distortion of the pipe or marking by the
jaw faces.
Where the tubular ends are threaded, adapters may be used to temporarily
engage the
threads and transfer load running the risk of damaging the threads. The
present
invention provides a means to internally friction grip a tubular work piece
with an
expandable cage, and apply assembly, handling and drilling loads through an
attachment.
Background of the Invention
Historically, petroleum drilling rigs have used an architecture where drilling
torque is
applied through a rotary table placed in the derrick floor. The rig mast is
used to
support the block and tackle equipment for hoisting tubular strings comprised
of
individual joints of pipe connected by threaded connections, in and out of the
drilled
hole or well. With this architecture, it is inconvenient to use the rotary
table to apply
torque to make up or break out the connections. Tongs are therefore typically
used to
apply and react make up or break out torque, by externally gripping the pipe
ends to be
connected directly above and below the threaded connection. This well known
procedure is used to make up and break out drill pipe, casing and tubing to
trip tubular
strings in or out of the well. In the case of casing and tubing, the method is
typically
incorporated into devices, referred to as power tongs, which provide a means
to apply
continuous rotation and torque through a motor and gear box assembly. However
these
devices still require external grips, typically using some form of jaws as
described, for
example, in US Patent 5172613. Whether powered or not, this method requires
that one
tong grip the upper end of the pipe joint suspended from the rotary table in
the derrick
CA 02512800 2001-03-22
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floor, to provide a reaction for the torque applied through a second tong
which is used
to grip and rotate the pipe joint being made up or broken out. The upper end
of the pipe
joint being rotated is supported by an elevator, hanging from the travelling
blocks, thus
allowing rotation and providing limited freedom to translate laterally.
However recent advances in drilling rig technology have resulted in increased
use of
rigs having a new architecture, and known in the industry as top drive rigs.
As the name
suggests, these rigs are equipped with a hydraulic or electric drive head unit
that moves
up and down the rig mast constrained by a track, thus enabling the application
of
rotational force from any position. These rigs employ a drive head capable of
applying
torque and axial load to the top of the pipe through an output shaft known as
a "quill,"
and typically employ more automated and powered pipe-handling equipment than
conventional rigs. This configuration allows the tubulars to be made up and
broken out
using the top drive to rotate and apply torque to the top joint, but
necessitates a method
of coupling the quill to the tubular capable of transmitting full make up or
break out
torque and at least some axial load.
For tubing and casing, this is typically accomplished using a threaded make up
adapter,
commonly referred to as a "nubbin", threaded on the lower end to match the
tubing or
casing thread and on the upper end to match the thread on the quill. A device
capable of
stroking up and down and transmitting torque, commonly referred to as a
floating
cushion sub, is also often placed between the quill and the nubbin to
accommodate
thread make up and break out length change without top drive movement. This
laterally
rigid and flexurally stiff device effectively forms an extension of the quill.
Unlike the conventional make up and break out method using tongs, this method
of top
drive make up requires extra steps to handle, install and remove the nubbin,
increasing
the time and consequently, the cost of running tubulars. In addition, the risk
of thread
damage is increased by the extra make up and break out to the nubbin required
for each
joint run in or out of the well.
This method of top drive make up further exacerbates the potential for
connection
thread damage because the rigid lateral positioning of the top drive at the
top end of the
joint, where it is supported during rotation. This prevents the tendency of
the thread
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axis to "self align" as otherwise occurs when the top of the joint is
suspended from the
cable-supported travelling block on conventional rigs, allowing relatively
free lateral
movement. Although the axes of the pin and box threads are generally parallel
when
the connection is stabbed, tolerances for rig mast position with respect to
the hole axis,
pipe straightness and threading can all conspire to allow significant
misalignment.
Under these conditions, the potential for connection damage is aggravated by
alignment
constraints as imposed by relatively rigid support at the upper end of joints.
Contrast
this with the greater freedom of motion allowed on conventional rigs when the
travelling block supports the upper end of the pipe. During rotation of the
connection at
the lower end, this alignment constraint tends to prevent the pin and box
thread axes
from self aligning which results in a tendency toward `cross threading' of the
connection when significant tolerancing errors exist, with consequent high
internal
contact stress and galling susceptibility. In many instances known to the
inventors, this
misalignment has resulted in connection damage and improperly made-up
connections.
It is therefore desirable to have a method for gripping the pipe without
contacting the
threads and that allows the top end of the pipe to displace laterally with
relative
freedom.
Methods using jaws on the exterior of the pipe to apply torque without
contacting the
threads are numerous. As mentioned above, jaws are typically employed with
power
tongs. Torque activated jaws such as described in US Patent 5172613, are the
most
typical architecture but the tendency of this method to mark and damage the
pipe has
led to more controlled active gripping systems such as described in US Patent
5172613.
To further avoid "causing surface damage or structural deformation", more
nearly
uniformly radial loading friction grips, such as described in US patent
4,989,909 are
known as a means to grip the exterior of tubulars where tolerance to damage is
low.
While these methods provide a generally satisfactory means for gripping the
exterior of
pipe, they are not amenable to use in conjunction with a top drive. Gripping
the interior
of the pipe avoids the need to apply torque through the coupling, or to invoke
more
complex means to bypass the connection, while all the time avoiding
interference with
other pipe handling equipment, such as elevators. Neither do these methods
address
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intolerance to connection thread misalignment, which is peculiar to the top
drive make
up and break out method.
The device/method of the present invention was therefore conceived
specifically as a
means to friction grip the inside of the tubular and thus provide the capacity
to transfer
torque and carry most of the axial handling loads presently provided by
nubbins. It will
also shorten the handling time requirements, eliminate nubbin contact with the
threads,
and provide increased lateral compliance to accommodate the tendency for top
end of
the pipe to move off axis during make up.
Summary of the Invention
To meet these objectives, the method of the present invention makes use of a
device
having an upper end provided with a crossover sub to attach to the quill and
having a
lower coupling end provided with a grip assembly, which may be inserted into
the top
end of a tubular work piece to be handled, and expanded to engage or grip the
inside
surface of the tubular joint. The grip method and contacting element
preferably
frictionally engage the inside wall of the tubular with a uniform distribution
of radial
loading virtually eliminating the risk of marking or distorting the pipe or
connection. It
will be understood that such attachment to the top drive quill may be direct
or indirect
to other intermediate components of the drill string such as a `thread saver
sub'
essentially forming an extension of the quill.
The upper adapter is coupled to the grip assembly by means of a tube having
upper and
lower universal joints which enable lateral movement during transmission of
torque, as
is commonly employed in applications where torque is transmitted over some
length,
such as in automobile drive shafts flexibly coupled through universal joints.
Both of the
upper and lower universal joints are capable of transferring torque while
bending in any
direction. The grip assembly is further arranged to permit the grip to be
activated, or
set, by application of right hand torque and deactivated or released by
application of
left hand torque when a first operating mode is engaged. In a second operating
mode,
either left or right hand torque is transferred directly through the grip
without changing
the grip force. The first or setting mode is engaged by application of slight
axial
compressive load, or by setting the quill down. The second or direct torque
mode is
CA 02512800 2008-09-09
engaged by application of slight tension or by lifting the quill up once the
grip is set.
These simple, fast and direct means of gripping and releasing provide
substantial
operational improvements over the existing methods.
The primary purpose of the present invention is to provide a method employing
an
5 internal gripping device for handling tubular work pieces in general and
particularly
suited to perform make up and break out of pipe joints being run in or out of
a well
with a top drive drilling rig, having as its gripping mechanism a sub-assembly
comprised of-
1 . a generally cylindrical expandable cage with upper and lower ends,
2. a structural member is provided in the form of a mandrel. Mandrel has upper
and
lower ends placed coaxially inside the cage where the lower ends of the
mandrel
and cage are attached, and where the external diameter of the cage is somewhat
less
than the internal diameter of the tubular work piece to be gripped, allowing
the cage
to be positioned within the tubular work piece,
3. a significant annular space between the inside surface of the cage and the
outside
surface of the mandrel,
4. a pressure member disposed in the lower interval of the annular space
between the
mandrel and cage as an expansion element, and
5. means to activate the expansion element to cause the cage to expand and
frictionally engage the inside surface of the tubular work piece with
sufficient radial
force to enable the mobilization of friction to transfer significant torque
and axial
load from the upper end of the mandrel through the cage to the tubular.
Said expandable cage of the gripping mechanism having a lower and upper end:
= is preferably comprised of a plurality of flexible strips aligned largely
axially along
the body of the cage and attached to cylindrical sleeves at each end of the
cage,
= where the edges of adjacent strips are preferably profiled to provide
interleaving
tabs or fingers,
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= which fingers permit cage expansion or radial displacement of the strips but
tend to
prevent cage twist or shear displacement between strips under torsion loading.
Said means to provide cage expansion is preferably provided by:
= a largely incompressible elastomeric material disposed in the lower interval
of the
annular space between the mandrel and cage,
= means to confine the ends of the elastomeric material and if necessary
further
means to confine the outer sides of the elastomeric material across gaps that
may
exist between adjacent edges of the cage strips to prevent excess extrusion of
the
elastomeric material when compressed, and
= means to axially compress the annular elastomeric material with sufficient
force to
cause the cage to expand and frictionally engage the inner surface of the
tubular
enabling transfer of torque and axial load from the upper end of the mandrel
through the cage to the tubular.
An additional purpose of the present invention is to provide a tubular
gripping and
handling device having said gripping sub-assembly joined to an external load
and
torque application device, such as the quill of a top drive rig, through a
load transfer
member or drive shaft, flexibly coupled at each end where such flexible
couplers
function as universal joints enabling transfer of torque with little or no
moment or
lateral resistance.
This purpose is preferably realized by:
= providing a crossover sub configured to thread to the quill on its upper end
and
connect to a tubular or hollow drive shaft at its lower end,
= by means of pins engaging slots in the upper end of the drive shaft thus
providing
the function of a universal joint, where
= a similar slotted and pinned connection is provided to join the lower end of
the
drive shaft to the upper end of the gripping mechanism sub-assembly.
A further purpose of the present invention is to provide a means to flow fluid
and apply
pressure through the top drive adapter and into the tubular work piece being
gripped.
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This purpose is realized by providing a flow path through the crossover sub,
drive shaft
and tool mandrel and is preferably augmented by provision of an internal cup
seal, such
as a packer or swab cup, attached to the lower end of the mandrel to prevent
leakage
into the annular space between the mandrel and inside surface of the tubular
work
piece.
In applications, where the lifting capacity of the frictional grip is
insufficient to reliably
support the hoisting loads required to run assembled tubular strings into or
out of a
well, the make up and break out functions provided by the tubular handling and
gripping assembly, must be supplemented by the addition of hoisting equipment.
In a
manner well known to the industry, such hoisting equipment may be provided as
elevators. However, to support applications where suitable elevators may not
be
available or convenient to use, it is a further purpose of the present
invention to provide
additional means to support hoisting loads, integral with the frictional grip
device.
This purpose is realized by providing an external hoisting sub-assembly, which
sub-
assembly is comprised of-
= a largely cylindrical hoisting sleeve coaxially placed outside the internal
gripping
sub-assembly having an upper end attached to the upper end of the internal
gripping
sub-assembly, a lower end extending downward to overlap an interval of the
tubular
work piece, typically to the lower end of the collar typically attached to the
upper
end of casing or tubing joints, and lower end configured with internal
grooves,
= a plurality of jaw segments, preferably provided as a collet where the upper
end of
the collet fingers are attached, and the lower end of the collet fingers carry
the jaw
segments configured to mate on their interior with the outside surface of the
tubular
work piece and on their exterior with ribs engaging the internal grooves of
the
hoisting sleeve where the spring action of the collet is preferably arranged
so the
jaws tends to contact the work piece,
= where the mating ribs and grooves of the jaw and hoisting sleeve surfaces
respectively tend to force the jaws inward under application of hoisting load,
in the
manner of slips, well known to the industry as a method of providing load
transfer
between hoisting equipment and tubular goods, and
CA 02512800 2009-06-18
7a
= means to retract the jaws to facilitate disengaging from the tubular work
piece,
which means is preferably linked to the operation of the internal friction
grip so that
the jaws may only be retracted when the tool is not set or activated.
In CA Pat. No. 2,403,746 there was described and claimed an apparatus for
handling
tubular goods having an internal gripping device for handling tubular work
pieces.
There was also described the use of articulated couplings. It has now been
realized that
the articulated couplings illustrated and described were equally important to
the internal
gripping device claimed, as they permit the transfer of torque with little or
not moment
or lateral resistance. Once the principles underlying the use of the
articulated coupling
are understood, beneficial results may be obtained even when other
configurations of
gripping devices (internal or external) are used to engage the tubular goods.
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Description of the Drawings
Figure 1 Isometric view of the assembled top drive make up adapter tool.
Figure 2 Longitudinal cross-sectional view through the centre of the top drive
make up
adapter tool as it appears prior to setting.
Figure 3 Longitudinal cross-sectional view of the top drive make up adapter
tool with
the gripping assembly in setting mode showing exaggerated cage expansion
gripping
the tubular work piece.
Figure 4 Longitudinal cross sectional view of the top drive make up adapter
tool with
gripping assembly in torque mode showing exaggerated cage expansion gripping
the
tubular work piece.
Figure 5 Schematic showing the general shape of a single `dovetailed' tooth as
they
may be employed on the setting nut face with matching grooves in the actuator
sleeve.
Figure 6 Isometric view of the assembled top drive make up adaptor tool
configured
with externally latching, integral hoisting sub-assembly.
Figure 7 Longitudinal cross-sectional view along the axis of the top drive
make up
adapter tool with hoisting sub-assembly showing position of components with
tool in
hoisting mode engaging the collar on the upper end of a typical tubular work
piece.
Figure 8 Longitudinal cross-sectional view of hoisting sub-assembly showing
position
of components with the tool in hoisting mode, engaging the collar on the upper
end of
tubular work piece.
Figure 9 Longitudinal cross-sectional view of hoisting sub-assembly showing
position
of components with tool in retract mode.
Figure 10 Isometric view of the assembled casing drive tool.
Figure I I Longitudinal cross-sectional view through the centre of the casing
drive tool
as it appears stabbed into the tubular work piece prior to setting.
Figure 12 View of mandrel showing exterior profiled intervals.
Figure 13 Isometric view of the casing drive tool with cage removed showing
helical
spring expansion assembly.
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Figure 14 Longitudinal cross-sectional view through the casing drive tool
centre with
the gripping assembly in setting mode showing cage expansion gripping the
tubular
work piece.
Figure 15 Longitudinal cross sectional view through the casing drive tool
centre with
gripping assembly in torque mode showing cage expansion gripping the tubular
work
piece.
Figure 16 Longitudinal cross sectional view through the centre of the casing
drive tool
with tool set and in torque mode showing tool position hoisting the tubular
work piece.
The aspect ratio of the drawings shown in FIGURES 14, 15 and 16 has been
adjusted to
exaggerate the width.
Description of the Preferred Embodiment
In its preferred embodiment, the tubular internal gripping and handling device
of the
present invention is configured as a top drive make up adapter tool, which
tool connects
a crossover sub I to an internal gripping assembly through a flexibly coupled
tubular
drive shaft 2. FIGURE 1 is an isometric view of the assembled tool with the
grip in its
unexpanded state, as it would appear preparatory to insertion into a tubular
joint.
The crossover sub I is generally cylindrical and made from a suitably strong
and rigid
material. Referring to FIGURE 2, crossover sub I has an upper end 10
configured with
internal threads 21 suitable for connection to the quill of a top drive and a
lower end 22
configured to allow insertion into an upper end 23 of tubular drive shaft 2.
In the
preferred embodiment it is also provided with a centre bore 24 to allow
passage of
pumped fluid through the quill as a convenient and desirable means for filling
the
tubular string.
Referring to FIGURE 1, tubular drive shaft 2 is provided with sets of through-
wall
closed L-shaped slots 25 at each of its upper and lower ends. Slots 25 are
distributed
equidistantly about the circumference and aligned axially. Tubular drive
shaft, 2 is
fastened to lower end 22 of crossover sub I by means of pins 26 placed through
the
upper set of slots 25 in tubular drive shaft 2. This provides a flexible
connection. The
pin positions and outside diameter of the lower end of the crossover sub I in
the
CA 02512800 2001-03-22
interval of overlap with the tubular drive shaft 2 are so arranged that said
flexible
connection is free to bend or flex through several degrees in any direction
when the
pins 26 are in the axial `leg' 25a of the L-shaped slots 25 but prevent such
flexibility
when the pins 26 are in the lower circumferential leg 25b of the L-shaped
slots 25. The
5 lower end of the drive shaft 2 is similarly connected by means of pins 26
within L-
shaped slots 25 that are inverted and reversed relative to the upper end of
the actuator
sleeve, 9, comprising the top element of the grip assembly. When the pins 26
are in the
axial legs 25a of the slots 25, this method of coupling both ends of the drive
shaft, 2, to
the crossover sub i and grip assembly respectively not only provides for
lateral
10 translation of the top of the joint with respect to the quill axis but also
allows some
axial length variation, or stroking, since the pins may ride up and down in
their slots,
thus enabling the make up adapter tool to provide the function of a floating
cushion sub
during make up and break out. When the pins 26 are in the circumferential legs
25b of
the slots 25, this method of coupling allows the tool to be moved and
positioned with
the lateral flexibility fully disabled, thus providing advantages in handling,
particularly
valuable in slant rig operations, where the tool would otherwise droop with
difficulty
then being encountered when attempting to stab into the top of the tubular
joint.
FIGURE 2 is a cross sectional view along the axis of the tool showing the
relation of
components in the grip assembly portion of the tool. In its preferred
embodiment the
grip assembly is comprised of several interacting components, those being:
= an expandable generally cylindrical cage 3 with provided with an upper end
27 and
a lower end 29. Cage 3 has an outer diameter slightly less than the inside
diameter
of a tubular work piece 13 except at its upper end 27 where a stop ring 28
with
increased diameter over a short distance is provided to create a shoulder
sufficient
to engage the end of the tubular work piece 13;
= a mandrel 4 is provided having an upper end 30 and a lower end 31. Mandrel
104
has an outside diameter significantly less than the cage 3 internal diameter
and
placed coaxially inside the cage, 3, with its lower end 31 attached to lower
end 29
of cage 3, in a manner enabling transfer of axial load and torque and upper
end
extended beyond the upper end of the cage 3;
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= cylindrical lower spacer sleeve 5 and upper spacer sleeve 7, separated by a
generally cylindrical elastomeric setting element 6, or series of elements, to
form an
element stack, which sleeves and element stack are placed coaxially in the
annular
space between the cage 3 and mandrel 4, and where the length of the sleeves
and
element stack is somewhat less than the cage length;
= a largely cylindrical setting nut 8 internally threaded to engage matching
threads
provided on the mandrel 4 over an interval starting at a position covered by
the
upper spacer sleeve 7 and having the face of its upper end configured as a dog
nut
with teeth 32 distributed equidistantly about the circumference, which teeth
are
preferably shaped as illustrated in FIGURE 5;
= an actuator sleeve 9 sliding on the upper interval of the mandrel 4, as
illustrated in
FIGURE 2. Sleeve 9 has notches 33 on its lower end face matching teeth 32
provided on the upper end face of the setting nut 8. Referring to FIGURE 2,
sleeve
9 has internal splines 34 on its lower end 36 matching external splines 35
provided
on upper end 30 of mandrel 4, and having threads on its external surface to
accommodate jam nut 12;
= a jam nut 12, internally threaded to fit the actuator sleeve 9 and provided
with set
screws to lock its position on the actuator sleeve 9 and;
= a swab cup 10, or similar annular seal element such as a packer cup,
retained with a
nut 11 to the extreme lower end of the mandrel 4.
Referring to FIGURE 1, the expandable cage, 3, is generally cylindrical in its
body, and
in its preferred embodiment is formed from a thin smooth walled vessel of
steel or
other suitably strong and flexible material by cutting a series of largely
square wave
slits 78 along a mid length interval of the vessel at several circumferential
locations.
Although a smooth walled vessel is preferred to avoid surface marking of
tubular
goods; in some applications cage 3 may be made with a friction enhancing
surface to
improve its friction coefficient with respect to the tubular good. This forms
a series of
largely axially aligned strips 80 having their ends 82 attached by the non-
slit upper and
lower ends of the cylinder but having their edges 84 interlocked by the `tabs'
86
resulting from the largely square wave cutting pattern. Even though
interlocked, there is
CA 02512800 2001-03-22
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some space or a gap between the strip edges, the magnitude of which is
dependent on
the method of manufacturing and tolerancing thereof. It will be evident to one
skilled in
the art that torsional loading applied along the axis of such a cage will tend
to generate
twisting distortion with associated shear displacement along the strip edges
until any
gaps between faces of the tabs are closed. Once these gaps are closed they
begin to bear
and transfer shear load along the strip length causing the torsional stiffness
and strength
of the cage 3 to increase dramatically and greatly enhancing it's overall
ability to
transmit torque. It is therefore desirable to keep the axial gap spacing as
small as
possible to limit the twist required to engage the tabs. It has been
determined that laser
cutting offers an efficient means to form slits narrow enough to sufficiently
limit the
angle of twist before tab contact; however, alternative manufacturing methods
may be
employed as indeed the cage 3 may built up from individual pieces suitably
attached.
The square wave amplitude or tab height must further be arranged to ensure
sufficient
overlap exists to achieve satisfactory shear load transfer when the cage 3 is
in its
expanded position within the tubular work piece 13. It should also be apparent
to one
skilled in the art that numerous variations of the slitting geometry may be
employed to
enhance the fatigue and strength performance of the cage 3, which rely on some
form
of interlocking to achieve maximum torque transfer capacity while retaining
the ability
to expand significantly as disclosed herein. Upper end 27 of the cage 3, is
provided
with an upset diameter forming a stop ring 28 greater than the inside diameter
of the
tubular work piece 13 end to be gripped. Lower end 29 of cage 3 is typically
provided
with an internally upset diameter internally splined for attachment to the
lower end 31
of mandrel 4.
The generally cylindrical mandrel 4 is formed from a suitably strong and rigid
material
to enable its function of axial load and torque transfer into the lower end of
the cage 3
and in its preferred embodiment is provided with a centre bore 37 to enable
fluids to be
passed in or out of the tubular work piece 13 if desired. Lower end 31 of
mandrel 4 is
typically threaded and splined to attach the splined lower end 29 of cage 3
retained by
nut 11. The splined engagement being generally indicated by reference numeral
38. In
the preferred embodiment the lower threaded interval of the mandrel 4 may also
be
used to attach the swab cup 10 to provide sealing between the inside of the
tubular
CA 02512800 2001-03-22
13
work piece 13 and the mandrel bore, which method of sealing is well known to
the oil
field industry. The main body diameter of the mandrel , is selected with
respect to the
inside diameter of the cage 3 to provide an annular space sufficiently large
to
accommodate the elastomeric setting element 6. Right hand threads are provided
along
the mandrel length over an interval where the load nut travel is desired. The
upper end
of the mandrel 4 is splined where the splines are open downward but have
closed or
blind upper ends. To facilitate and simplify assembly, the mandrel diameter at
each of
the intervals described generally increases from the lower to upper end, as
needed to
accommodate the functions of the threads, splines or controlled diameters. The
upper
end of the mandrel inside bore is provided with threads suitable for
attachment to a
hose or similar fluid conduit.
The lower spacer sleeve 5 is a rigid cylinder of sufficient length to extend
from the
closed end of the cage 3 to a point somewhat above the ends of the cage strips
80 to
provide a transition interval over which the strips of cage 3 can expand
without being
additionally radially loaded by application of expansion pressure by the
elastomer. The
inside and outside diameters of the lower sleeve are selected to fit inside
the annular
space between the mandrel 4 and cage 3 while minimizing the elastomer
extrusion
gaps.
The upper spacer sleeve 7 is similar to the lower spacer sleeve 5 where its
length is
selected relative to the setting nut 8 and upper end of the cage slots 78 to
also provide
an interval where cage expansion can occur in the absence of radial expansion
pressure.
The setting element 6, or element stack, is largely cylindrical and may be
comprised of
several separate components including specialized end elements or devices to
control
extrusion, such as is well known in the well bore packer and bridge plug art,
but is
generally formed of hydrostatically incompressible and highly deformable
elastomeric
materials and is dimensioned to largely fill the annular space between the
upper spacer
sleeve 7 and lower spacer sleeve 5. This annular space and hence element stack
must be
of sufficient annular thickness and initial length so that the shortening
under axial
displacement required for expanding the cage 3 and setting, still provides an
adequate
interval length over which radial displacement and the consequent radial load
are
sufficient to mobilize the friction grip capacity as required by the
application.
CA 02512800 2001-03-22
14
The setting nut 8 is a largely cylindrical internally threaded nut with lower
end smooth
faced to allow sliding contact with the upper end of the upper spacer sleeve
7. The
upper face of setting nut 8 is configured with dog nut teeth 32 to enable
torque coupling
with the actuator sleeve 9. To further facilitate engagement in applications
requiring
some `locking', the tooth shape may be dovetailed and oriented so that the
narrow
portion of the dovetail is attached to the face of the nut as shown in FIGURE
5.
The actuator sleeve 9 is largely cylindrical and rigid with internal diameter
slightly
greater than the upper end of the mandrel 4 on which it slides. The face of
its lower end
is provided with evenly distributed notches 33 to engage the matching notches
in the
upper end of the setting nut 8 which notches may be dovetailed as required to
match the
setting nut 8 geometry as shown in FIGURE 5. The inside surface of the lower
end of
the actuator sleeve 9 is provided with splines 34 to match the splines 35 on
the upper
end of the mandrel 4. When assembled, the actuator sleeve 9 is able to slide
on the
mandrel 4 but is constrained in its lower position by the top of the setting
nut 8, referred
to as setting mode position, and in its upper position by the blind ends of
the spline
grooves 35 on the mandrel 4 referred to as torque mode position. The various
interacting component lengths are arranged so that the actuator has sufficient
travel
between these two positions to create a range of motion where neither the
setting nut 8
nor the upper mandrel splines are engaged, which intermediate position is
referred to as
neutral because the actuator sleeve 9 is free to rotate about the mandrel 4.
The upper
end of the actuator sleeve 9 has an external diameter somewhat less than the
internal
diameter of the drive shaft 2, and has several holes distributed equidistantly
around its
circumference to accept pins 6 which provide attachment to the drive shaft 2.
In operation, with the crossover sub 1, of the top drive adapter tool made up
to the quill
of a top drive rig, the grip assembly is lowered into the top end of a tubular
joint until
the cage stop ring engages the top end surface of the joint. The top drive is
then further
lowered or set down on the tool which causes the actuator sleeve 9 to displace
downward until its notched lower end 33 engages the teeth 32 on the upper face
of
setting nut 8. This position is referred to as setting mode. Right hand
rotation of the top
drive then drives the nut downward against the upper spacer sleeve 7 which
acts as an
annular piston, compressing the elastomeric element and causing it to expand
radially
CA 02512800 2001-03-22
thus forcing the cage 3 outward and into contact with the inside surface of
the tubular
work piece 13. Continued right hand rotation causes largely hydrostatic
compression of
the elastomer with consequent development of significant contact stress
between the
cage 3 and the inner surface of the tubular over the length of the elastomeric
setting
5 element 6. Frictional resistance to the compressive axial load is developed
in the setting
nut threads and end face and is manifest as torque at the top drive. It will
be apparent
that this torque is reacted through the tool into the tubular joint. Until the
cage 3 is
expanded, this reaction is provided by incidental friction of the cage strips,
the swab
cup 10 and contact with the stop ring 28. Once activated the cage expansion
`self
10 reacts' the increasing setting torque, a measurement of which is available
to the top
drive control system and may be used to limit the amount of setting force
applied. As a
further means to limit the amount of setting force applied, the position of
the jam nut 12
may be adjusted up or down on the actuator sleeve by rotation, and locked with
the set
screws provided in the jam nut 12. When thus positioned and locked the jam nut
will
15 engage the top of the cage and `jam' during setting with consequent
dramatic torque
increase and thus limit the downward travel of the actuator sleeve and hence
setting
nut. When sufficient setting torque has been applied, the tool is considered
set.
FIGURE 3 shows a cross section of the tool in setting mode with the cage, 3,
expanded
into contact with the tubular work piece 13.
Once set, the top drive is raised which disengages the lower face of the
actuator sleeve
9 from the setting nut 8 and upon being further raised engages the actuator
sleeve
splines 34 and mandrel splines 35 at the upper extent of the actuator range of
travel
where the closed ends of the mandrel spline 35 grooves prevent the actuator
sleeve 9
from sliding off the top of the mandrel 4. This position is referred to as
torque mode
and either right or left hand torque may by transferred through the actuator
sleeve 9,
directly to the mandrel 4.
As is apparent in FIGURE 1, the application of right hand torque during
setting will
move the pins out of the circumferential leg 25b of the L-shaped slots 25 so
that when
the quill is raised to engage torque mode, the pins will tend to slide up the
axial legs
25a of the L-shaped slots and re-establish the flexibility of the drive shaft
coupling.
CA 02512800 2001-03-22
16
If the joint is to be broken out, the top drive is positioned to allow the
drive shaft 2 to
`float', i.e. with the pins positioned approximately mid-way in the slots, and
reverse
torque applied. Once broken out, the joint weight may be supported by the tool
and
raised out of the connection until gripped by separate pipe handling tools.
Once gripped
by the pipe handlers, the top drive is set down on the tool, engaging the set
mode. Left
hand torque is then applied and the setting nut 8 rotated a sufficient number
of turns to
release the tool. The amount of rotation required to release will in general
be equal to
the number of turns required for setting.
If the joint is to be made up, its weight may be supported by the tool while
being
positioned and stabbed into the connection to be made up. Once stabbed, and
with the
joint weight still largely supported by the tool, the connection may be made
up. As for
break out, the tool is released by setting down the top drive to engage set
mode and
applying sufficient left hand rotation to release the tool.
For either make up or break out, it will be evident from FIGURE 1, that
setting down
and applying left hand torque will cause the pins 26 to move into the
circumferential
legs 25b of the L-shaped slots. Upon withdrawal from the tubular work piece
13, the
tool will be more or less rigidly coupled to the quill, facilitating stabbing
into the top of
the next joint of tubular goods to be handled.
FIGURE 4 shows the tool in torque mode set inside a tubular work piece 13. It
will be
evident to one skilled in the art that loads (torque or tension) applied to
the mandrel 4
with the tool set and in torque mode are reacted in part into the tubular work
piece 13
by shear coupling through the annular thickness of the elastomer and cage
material
compressed between the mandrel 4 and tubular work piece 13. However the
greater part
of any applied loads are reacted through the lower end of the mandrel 4 into
the lower
end of the cage 3, and from there, are shed into the tubular work piece 13
over the
interval along which it is in contact with the expanded cage 3. The axial or
torsional
load required to initiate slippage is therefore determined by the area in
contact, the
effective friction coefficient acting between the two surfaces and the normal
stress
acting in the interfacial region between the cage 3 and work piece 13. It will
be further
evident to one skilled in the art that to provide sufficient torque and axial
load capacity,
these variables may be manipulated in numerous ways including: lengthening the
CA 02512800 2001-03-22
17
expanded interval of the grip; coating, knurling or otherwise roughening the
cage
exterior to enhance the effective friction coefficient; increasing the axial
stress that may
be applied to the elastomer through improved materials and extrusion
protection
(within the limits imposed by the allowable stress state (e.g., burst
capacity) of the
tubular work piece, 13), and; reduced friction loss along the setting element
6 by
disposing lubricants on the mandrel and cage surfaces contacted by the setting
element
6, perhaps in combination with friction reducing coatings such as Teflon .
It will be apparent to one skilled in the art that as the elastomer is
compressed from the
top, sliding resistance will tend to cause the hydrostatic stress to decrease
from top to
bottom over the elastomer length. It has been found in practice that
lubrication of the
elastomer surfaces can be employed to reduce this effect if required to either
improve
the `self starting' response or the relationship between setting torque and
axial or
torsional grip capacity.
To provide further functionality in applications where it is desired to apply
fluid
pressure or flow fluids into or out of the tubular work piece 13, as often
occurs when
running casing which must be filled from the top, in its preferred embodiment
the top
drive adapter tool is configured with a hose connected between the bottom end
of the
crossover sub bore and the top of the mandrel bore. The hose length and
positioning
must be arranged to accommodate the length change between the hose end
attachment
points occurring during operation as allowed by the axial stroke of the drive
shaft slots
and the movement of the actuator sleeve, 9. Positioning the hose as a coil
inside the
drive shaft, 2, provides one means to accommodate the required length change
during
operation. The hose and connections must also accommodate rotation of the
cross over
sub I with respect to the mandrel 4 during setting and unsetting or if
rotating in neutral.
A swivel coupling, or other suitable means, may be used to provide this
function.
To further enhance the operational and handling characteristics of the tool,
springs may
be provided between the drive shaft 2, crossover sub I and grip assembly. A
compression spring may be provided between the drive shaft 2 and actuator
sleeve 9 to
reduce the tendency for the actuator sleeve 9 to become disengaged from the
setting
nut, 8, while rotating in setting mode without downward travel of the quill. A
tension
spring may be provided between the crossover sub I and the drive shaft 2 to
similarly
CA 02512800 2001-03-22
18
reduce the tendency of the actuator sleeve spline to disengage from the
mandrel 4 while
rotating in torque mode to break out a joint, which break out tends to push
the joint
upward. As the joint moves upward in the absence of quill travel, sliding will
tend to
occur in the tool either within the slots of the drive shaft 2 or by sliding
between the
engaged actuator sleeve and mandrel splines. It will be seen that the tension
spring
biases the pins in the upper end of the drive shaft 2 to slide in favour of
the engaged
spline. It will be evident to one skilled in the art that various other
biasing strategies
may be similarly employed such as control of friction coefficient in the
pinned flexible
couplings relative to the engaged components to simplify operating procedures.
Alternatively, details of the engagement mechanisms may be varied to
accomplish
similar purposes such as lengthening the overlapped splined interval or
modifying the
tooth and notch profile between the setting nut 8 and actuator sleeve 9 to
obtain a more
preferential friction angle. One such configuration is shown in FIGURE 5.
In the preferred embodiment, expansion of the cage 3 is accomplished by
elastomeric
material that comprises the setting element 6 making direct contact against
the cage , so
that under setting stresses, elastomer extrusion into the gaps between cage
strip edges is
possible. If the combination of applied stress and gap size required for
certain
applications results in excessive extrusion, the cage gaps may be bridged by
provision
of individual thin solid strips placed on the inside surface of the cage 3 so
as to cover
the gaps over the interval where elastomer load occurs. To facilitate
assembly, said
strips may be fastened to one or the other of the strips forming the gap to be
bridged.
Preferred Embodiment Incorporating Additional Integral Hoisting
In its preferred embodiment as a top drive make up adaptor tool, the method of
the
present invention readily accommodates the axial and torsional loads required
to
handle, make up and break out single joints of pipe as required to run casing
or tubing
strings in and out of well bores. However, to support applications where the
hoisting
loads associated with running such strings may exceed the ability of the
internal friction
grip of the make up adaptor tool to reliably support the string weight, the
tool may be
provided with an externally gripping, integral hoisting sub-assembly.
CA 02512800 2001-03-22
19
FIGURE 6 shows an isometric view of a tool configured with such a hoisting sub-
assembly, showing the general location of the components supporting the
hoisting
function relative to the cage 3 and drive shaft 2. The components comprising
the
hoisting sub-assembly may be described with reference to FIGURE 7, which shows
an
entire longitudinal cross section along the tool axis, and FIGURE 8, which
shows a
close up view of the tool centre interval. In these figures the hoisting
components are
shown in relation to the tubular work piece 13 having a threaded collar 41
forming its
upper end as is typical of oil field casing or tubing. The components are
shown as they
would appear when hoisting.
A largely cylindrical hoist tube 40, is attached at its upper end to the
actuator sleeve 9
and at is lower end to the upper end of a largely axisymmetric hoist collar
42, having an
internal diameter somewhat greater than the outside diameter of the work piece
collar
41 and having a length extending below the lower face of the work piece collar
41. The
lower end of the hoist collar, 42, is provided with one or more relatively
deep grooves,
forming teeth having a shape similar to buttress threads, where the load flank
is sloping
downward and the stab flank is relatively flat. The latch segments 44 are
configured as
the lower ends of fingers on the hoist collet 46 having an interior profile
closely
matching the work piece 13 diameter, below the work piece collar 41 when the
collet is
in its relaxed state. The exterior surface of the latch segments 44 are
profiled to form
ribs loosely engaging and generally matching the buttress profile of the
grooves
provided in the lower end of the hoist collar 42. The root and crest
diameters, and other
dimensions of the buttress profiled grooves and ribs, are selected to ensure
the
engagement of the load flanks when the latch segments 44 are positioned
against the
pipe is sufficient to carry the hoisting load and that the latch segments 44
may displace
outward a sufficient distance so that the bore formed by the expanded segments
is
greater than the outside diameter of the work piece collar 41. The upper end
of the latch
segments are arranged to align with the lower face of the work piece collar 41
when the
actuator sleeve 9 is near the upper extent of its travel in torque mode.
The body of the hoist collet 46 extends upward passed the latch control collet
48
attached to the upper end of the cage 3. The fingers of the latch control
collet 48 open
upward having ends which form an internal upset conical surface and external
upset
CA 02512800 2001-03-22
rounded surface. In its relaxed state, the external diameter defined by the
latch control
collet 48 fingers, is slightly less than the internal diameter of the relaxed
hoist collet 46
body. The setting nut indicator sleeve 50 has a relatively thin cylindrical
lower end
extending downward and engaging the setting nut 8 at the outside edge of its
upper end.
5 The upper end of the setting nut indicator sleeve 50 is provided with an
externally upset
conical end, dimensioned to engage the internally upset conical end of the
latch control
collet 48.
To further support the hoisting load capacity of the tool, externally threaded
split rings
52 are provided to mate with internal threads on the upper and lower ends of
the drive
10 shaft 2. When the slotted and pinned connections between the drive shaft 2
and the
crossover sub I and actuator sleeve 9 are fully extended, the externally
threaded split
rings 52 engage shoulders provided in the crossover sub I and actuator sleeve
9, which
shoulder engagement reacts the hoisting load instead of the pinned connection.
In operation the hoisting sub-assembly may be placed in one of two modes
depending
15 on the position of the setting nut 8. When the tool is set, the setting nut
8 will be in its
lower position compressing the setting element 6. In this position the hoist
collet 46
tends to hold the latch segments against the work piece 13 placing the
hoisting sub-
assembly in hoisting mode as shown in FIGURE 8. Application of hoisting load
tending to lift the tool, will be transferred through the hoist collar and
carry the latch
20 segments upward until their upper ends begin to bear on the lower face of
the work
piece 13 collar. Upon application of additional hoisting load, engagement of
the conical
load flank surfaces provided by the buttress shaped hoist collar 42 grooves,
and latch
segment 44 ribs, tend to create a radial force, in the manner of slips, which
radial force
ensures positive engagement between the work piece 13 and tool.
To disengage the tool from the work piece 13, collar the latch segments 44
must be
retracted to place the tool in release mode as shown in FIGURE 9. To retract
the latch
segments, the hoisting load must be removed and the tool un-set by left hand
rotation of
the setting nut 8, which as described above, raises the setting nut 8 and
simultaneously
raises the setting nut indicator sleeve 50. Continued left hand rotation
brings the upper
cone of the setting indicator sleeve into contact with the mating internal
conical surface
on the inside of the latch control collet 48, forcing the fingers outward and
into contact
CA 02512800 2001-03-22
21
with the interior of the hoisting collet 46 body, expanding the hoisting
collet 46 and
retracting the latch segments 44 carried on the ends of the hoisting collet 46
fingers,
thus enabling the tool to be disengaged from the work piece 13.
Preferred Embodiment Incorporating Additional Axial Load and Fatigue
Capacity
As discussed above, advances in drilling rig technology have resulted in
increased use
of top drive rigs. Top drives are primarily used to apply drilling loads to
drill pipe,
however they also allow application of handling, make up and break out loads
required
for running tubulars, referred to as casing and tubing, typically used to case
or complete
the well. To run casing or tubing requires a method of coupling the quill to
the tubular
capable of transmitting full make up or break out torque, and at least some
axial load,
without risking damage to the threaded connections of these tubulars which are
less
robust than those used to connect joints of drill pipe.
The embodiment of the present invention described to this point, specifically
address
this need for a tool to support running tubing or casing. However the emerging
use of
top drives to perform drilling using casing, referred to in the industry as
Casing
DrillingTM, has resulted in the further need for a method to grip casing to
perform
drilling operations. The preferred embodiment described above, while suited to
the
needs of make up and break out of casing and tubing for running operations,
does not
provide the axial load and fatigue capacity required for drilling with casing.
The embodiment which will now be described, with reference to FIGURES 10
through
16, was therefore conceived specifically as a means to couple the top drive
quill to
casing with a device having sufficient axial and torsional fatigue capacity to
support
drilling with the casing while preserving the advantages of a friction grip
provided by
the earlier casing running tool.
To meet these objectives, the method of the present invention makes use of a
device
having an upper end provided with a cross-over sub to attach to the quill of a
top drive
and having a lower end provided with a grip assembly, which may be inserted
into the
top end of a tubular work piece and expanded to engage or grip the inside
surface of the
CA 02512800 2001-03-22
22
tubular work piece. The grip method and contacting element preferably
frictionally
engage the inside wall of the tubular with symmetric radial loading, virtually
eliminating the risk of marking or distorting the pipe or connection. The
method of
expansion employed in the grip assembly further provides means whereby the
application of axial load tends to increase the gripping force applied by the
device to
the work piece, better enabling hoisting loads to be reliably transferred from
the quill
into the tubular joint. It will be understood that such attachment to the top
drive quill
may be direct or indirect to other intermediate components of the drill string
such as a
`thread saver sub' essentially forming an extension of the quill.
The cross over sub is coupled to the grip assembly by means of a sliding,
splined and
sealing connection, providing the function of a `cushion sub' to facilitate
management
of load during make-up, transmission of axial and torque loads and containment
of
fluids. The grip assembly is further arranged to permit the grip to be
activated, or set,
by application of right hand torque and deactivated or released by application
of left
hand torque when a first operating mode is engaged. In a second operating
mode, either
left or right hand torque is transferred directly through the grip without
changing the
grip force. The first or setting mode is engaged by application of slight
downward axial
movement, or setting the quill down. The second or direct torque mode is
engaged by
lifting the quill up once the grip is set, i.e., application of upward
movement until slight
tensile resistance occurs. These simple, fast and direct means of gripping and
releasing
provide substantial operational improvements over the existing methods.
Summary of Preferred Embodiment Incorporating Additional Axial Load and
Fatigue Capacity
An additional purpose of the present invention is to provide a method
employing an
internal gripping device for handling tubular work pieces in general and
particularly
suited for connecting between a top drive quill and upper joint of casing in a
string used
for Casing DrillingTM, having as its gripping mechanism a sub-assembly
comprised of:
1. a generally cylindrical expandable cage with upper and lower ends,
2. a structural member in the form of a mandrel is provided. The mandrel has
upper
and lower ends placed coaxially inside the cage where the lower ends of the
CA 02512800 2001-03-22
23
mandrel and cage are attached in a manner allowing torque transfer and some
relative axial movement, and where the external diameter of the cage is
somewhat
less than the internal diameter of the tubular work piece to be gripped,
allowing the
cage to be placed inside the tubular work piece,
3. a significant annular space between the inside surface of the cage and the
outside
surface of the mandrel,
4. a pressure member disposed in the lower interval of the annular space
between the
mandrel and cage as a spring expansion element, and
5. means to activate the spring expansion element to cause the cage to expand
and
frictionally engage the inside surface of the tubular work piece with
sufficient radial
force to enable transfer of significant torque and axial load from the upper
end of
the mandrel through the cage to the tubular
6. further means to increase the radial force applied by the spring expansion
element,
beyond that provided by the activation means, upon application of sufficient
axial
load as may be required to support some portion of the string weight while
conducting running or drilling operations.
Said cylindrical cage of the gripping mechanism having a lower and upper end:
= is preferably comprised of a plurality of strips aligned largely axially
along the
body of the cage and attached to cylindrical sleeves at each end of the cage,
= where the edges of adjacent strips are preferably profiled to provide
interlocking
tabs or fingers, and
= which fingers permit cage expansion or radial displacement of the strips but
tend to
prevent cage twist or shear displacement between strips under torsion loading.
Said means to provide cage expansion is preferably provided by:
= a generally cylindrical helical spring expansion assembly disposed in the
central
interval of the annular space between the mandrel and cage,
= which helical spring expansion assembly is formed by a plurality of
structural,
coaxial, helically parallel coils having co-terminal upper and lower ends and
side
CA 02512800 2001-03-22
24
edges, and by upper and lower spring end sleeves structurally engaging the
upper
and lower co-terminal ends of the coils,
= means to axially compress the cylindrical helical spring assembly with
sufficient
force to cause the cage to expand and frictionally engage the tubular work
piece
enabling transfer of torque and axial load from the upper end of the mandrel
through the cage to the tubular,
= which structural engagement between the coil ends and sleeves preferably
using a
pivoting connection formed by providing said coil ends with a curved profile
to
mate with sockets placed in the upper and lower spring end sleeves where the
axis
of rotation for each pivoting connection is largely radially aligned to thus
facilitate
rotation as the helix angle increases under deformation imposed by axial
compression causing expansion of the cylindrical helical spring assembly,
= helix angle of the helically parallel coils chosen so that under compression
the
spring assembly expands significantly and preferably chosen to be slightly
less than
45 with respect to the pipe axis in their expanded configuration,
= where contact between side edges of helically parallel coils is preferably
allowed,
but if not allowed a means is provided to react the torque required to prevent
edge
contact, and
= which means to react torque to prevent edge contact is preferably obtained
largely
by providing the cylindrical spring assembly in two co-axial layers having
their
helixes wound in opposite directions and sleeve elements at their ends
connected.
Said means to increase the radial force applied by the expansion element upon
application of axial load provided by reacting the lower spring end sleeve
into the
mandrel and the upper spring end sleeve into the upper end of the cage. Thus
configured, lifting load, applied to the upper end of the mandrel, is reacted
into the
lower end of the cylindrical spring assembly and thence partially reacted by
frictional
contact through the cage wall into the tubular work piece and partially as
tension
applied to the top of the cage and resisted by frictional contact between the
cage and
work piece.
CA 02512800 2001-03-22
An additional purpose of the present invention is to provide a tubular
gripping and
handling device having its cross-over sub joined to said gripping sub-assembly
by an
appropriately splined and dogged connection allowing sufficient free sliding
axial
movement to facilitate control of axial load during make up required to
perform what is
5 known as a `floating make up', i.e., make up under conditions where at most
the weight
of the single joint being made up is allowed to be born by the threaded
connection
undergoing make up.
A further purpose of the present invention is to provide a means to flow fluid
and apply
pressure through the casing drive tool and into the tubular work piece being
gripped.
10 This purpose is realized by providing a flow path through the crossover sub
and tool
mandrel and is preferably augmented by provision of an internal annular seal,
such as a
packer or swab cup, attached to the lower end of the mandrel preventing
leakage in the
annulus between the mandrel and inside surface of the tubular work piece.
Description of preferred embodiment incorporating additional axial load and.
fatigue
15 capacity
In the preferred embodiment of the present invention incorporating additional
axial
load and fatigue capacity, the tubular internal gripping and handling device
of the
present invention, generally referred to as gripping assembly 100, is
configured as a
casing drive tool. Referring to FIGURE 10, gripping assembly 100 connects to a
20 crossover sub 101. Referring to FIGURE 11, crossover sub 101, is generally
axisymmetric and made from a suitably strong and rigid material. Crossover sub
101
has an upper end 140 configured with threads suitable for connection to the
quill of a
top drive rig and a lower end 142 configured with threads to engage an upper
end 146
of an actuator sleeve of gripping assembly 100. In the preferred embodiment it
is also
25 provided with a centre bore 148 to allow passage of fluid pumped through
the quill to
facilitate various drilling and running operations such as mud circulation.
FIGURE l l is a cross sectional view of the casing drive tool showing the
relation of
components in the gripping assembly 100 as they would appear stabbed into a
tubular
work piece 113. Tubular work piece 113 is shown as the top interval of a joint
of casing
CA 02512800 2001-03-22
26
having a collar 150 at its upper end 152. In its preferred embodiment grip
assembly 100
is comprised of several interacting components, those being:
= an expandable generally cylindrical cage 103 is provided having an upper end
154 and a lower end 156. Cage 103 has an outer diameter slightly less than the
inside diameter of tubular work piece 113, except at its upper end 154 where a
stop ring 157 with increased diameter over a short distance is provided to
create
a shoulder sufficient to engage collar 150 at upper end 152 of tubular work
piece 113;
= a mandrel 104 is provided having an upper end 158 and a lower end 160.
Mandrel 104 has an outside diameter significantly less than an internal
diameter
of cage 103 and is placed co-axially inside cage 103. Upper end 158 of mandrel
104 extends beyond upper end 154 of cage 103. Lower end 160 of mandrel 104
is splined to lower end 156 of the cage 103. This splined interval, indicated
by
reference numeral 162, enables torque transfer and allows some relative axial
movement tending to prevent transfer of axial lifting load from mandrel 104 to
lower end 156 of cage 103 and;
= there is also provided a cylindrical lower spring end sleeve 105, and an
upper
spring end sleeve 107, separated by a plurality of coaxial closely spaced
helical
coils forming a generally cylindrical helical spring element 106. Helical
spring
element 106 together with the spring end sleeves 105 and 107 form a helical
spring expansion assembly, generally indicated by reference numeral 164.
Helical spring expansion assembly 164 is placed co-axially in the annular
space
between cage 103 and mandrel 104. The length of helical spring expansion
assembly 164 is somewhat less than the length of cage 103. Lower spring end
sleeve 105 is attached to lower end 160 of mandrel 104 directly above splined
interval 162 traversed by mating lower end 156 of cage 103;
= a largely cylindrical setting nut 108 is provided which is externally
threaded to
engage matching threads provided in upper end 154 of cage 103. Setting nut
108 has an external spline over a portion of its upper interval, this splined
interval being indicated by reference numeral 168;
CA 02512800 2001-03-22
27
= an actuator sleeve 109 is provided which slides on upper end 158 of mandrel
104. Actuator sleeve 109 has an internal splined interval 170 on its lower
cylindrical end 172 that mates with external splined interval 168 on the upper
end of setting nut 108. Actuator sleeve 109 also has internal splines 174
matching external splines 176 provided on upper end 158 of mandrel 104, and;
= a packer cup 110, or similar annular seal element, is fastened with a nut
111, to
the extreme lower end 160 of mandrel 104. Packer cup 110 and nut Ill also
constrain the lower travel limit of cage 103, which engages splined interval
162
of mandrel 104.
Referring to FIGURE 10, the expandable cage 103 is generally cylindrical and
is,
preferably, formed from a generally smooth walled vessel of steel or other
suitably
strong and flexible material. Cage 103 has a series of largely square wave
slits 178
along the cylindrical interval of the vessel body at several circumferential
locations,
thus forming a series of largely axially aligned strips 180. Strips 180 have
their ends
182 attached by the non-slit upper and lower ends of the cylinder and have
their edges
184 interlocked by the `tabs' 186 resulting from the largely square wave
cutting pattern.
Even though interlocked, there is some space or a gap between the strip edges,
the
magnitude of which is dependent on the method of manufacturing and tolerances
thereof. It will be evident to one skilled in the art that torsional loading
applied along
the axis of such a cage will tend to generate twisting distortion with
associated shear
displacement along the strip edges until any gaps between faces of the tabs
are closed.
Once these gaps are closed they begin to bear and transfer shear load along
the strip
length causing the torsional stiffness and strength of the cage 103 to
increase
dramatically and greatly enhancing it's overall ability to transmit torque. It
is therefore
desirable to keep the axial gap spacing as small as possible to limit the
twist required to
engage the tabs. It has been determined that laser cutting offers an efficient
means to
form slits narrow enough to sufficiently limit the angle of twist before tab
contact;
however, alternative manufacturing methods may be employed as indeed the cage
103
may built up from individual pieces suitably attached. The square wave
amplitude or
tab height must further be arranged to ensure sufficient overlap exists to
achieve
satisfactory shear load transfer when the cage 103 is in its expanded position
within the
CA 02512800 2001-03-22
28
tubular work piece. It should also be apparent to one skilled in the art that
numerous
variations of the slitting geometry may be employed to enhance the fatigue and
strength
performance of the cage 103 that rely on some form of interlocking to achieve
maximum torque transfer capacity while retaining the ability to expand
significantly as
disclosed herein. The non-slit upper end 154 of the cage 103 is provided with
a stop
ring 1 57 having an upset diameter greater than the inside diameter of the
upper end 152
tubular work piece end 113 to be gripped and internal threads mating with the
external
threads of the setting nut 108. The lower end of the cage 103 is typically
provided with
an internally upset diameter internally splined over interval 162 for
attachment to the
lower end of the mandrel 104.
Referring to FIGURE 11, the generally cylindrical mandrel 104 is formed from a
suitably strong and rigid material to enable its function of axial load and
torque
transfer. In its preferred embodiment, it is provided with a centre bore 188
to enable
fluids to be passed in or out of tubular work piece 113, if desired. An upper
end 190 of
bore 188 is enlarged and threaded to attach a flow tube, 112. A lower end 192
is
similarly enlarged and threaded to attach the nut I11. An outer surface 194 of
the
mandrel is shaped as shown in FIGURE 12 to accommodate connection to and
interaction with various sub-components of the system and has the following
intervals
described in order from its lower to upper end.
= Outer surface 194 on lower end 160 of the mandrel 104 is smooth to form a
packer
seal interval 196. The packer cup, 110, provides annular sealing between the
inside
of the tubular work piece and the mandrel bore, which method of sealing is
well
known to the oil field industry.
= Directly above the packer seal interval 196 is lower splined interval 162
that
engages the internally splined lower end 156 of the cage 103, which splined
interval
is of sufficient length to allow cage 103 to slide axially.
= Above lower splined interval 162 is an upper threaded interval 200 that
engages the
internally threaded lower spring end sleeve 105, which threads are tapered in
the
preferred embodiment to maximize the axial load transfer efficiency of the
connection.
CA 02512800 2001-03-22
29
= Extending upward from the upper threaded interval 200 is the central body
interval
202 having a diameter slightly less than the internal diameter of the unloaded
helical spring expansion assembly 164.
= Central body interval 202 extends upward from upper threaded interval 200
and
ends abruptly at a shoulder 204 forming the lower limit of a stop shoulder
upset
interval 206 having a diameter slightly less than the crest diameter of the
actuator
sleeve 109 internal splines 174 and length somewhat greater than the actuator
sleeve 109 mid-section splined interval 170. Shoulder 204 acts as a stop,
limiting
the range of relative upward travel allowed to setting nut 108, with respect
to the
1.0 mandrel 104.
= Directly above stop shoulder upset interval 206 is the upper splined
interval 176
which splines are open downward and configured to facilitate engagement with
internal splines 174 of actuator sleeve 109.
= A shoulder 208 forming the lower limit of hoisting shoulder upset interval
210,
closes the upper end of upper splined interval 176. Shoulder 208 engages a
matching internal shoulder 212 in actuator sleeve 109, enabling transfer of
hoisting
loads from actuator sleeve 109 to mandrel 104.
It will thus be apparent that to facilitate and simplify assembly, the mandrel
diameter at
each of the intervals described generally increases from its lower to upper
end, as
needed to accommodate the functions of the threads, splines, shoulders or
controlled
diameters.
The lower spring end sleeve, 105, is a rigid cylinder, internally threaded to
engage the
mandrel 105 as described above. It is of sufficient length to extend from the
cylindrical
end of the cage 103 to a point somewhat above the ends of cage strips 180.
This
provides a transition interval over which the strips of cage 103 can expand
without
being additionally radially loaded by application of expansion pressure by the
helical
spring element 106. The outside diameter of the lower spring end sleeve 105 is
selected
to fit just inside the cage 103. Referring to FIGURE 13, its lower end 214 is
contoured
or scalloped to form sockets 216 mating with the rounded ends of the helical
coils
constituting the helical spring element 106. Its lower end 218 is configured
as a dog nut
CA 02512800 2001-03-22
to mate with dogs provided in lower end 156 of internally upset splined
interval 162 of
cage 103. The dog teeth are configured to be engaged over the range of motion
allowed
to the cage 103 with respect to the mandrel 104. This prevents lower spring
end sleeve
105 from rotating on the mandrel 104, enabling transfer of torque from the
mandrel 104
5 into the helical spring assembly 164.
The upper spring end sleeve 107 is similar to the lower spring end sleeve 105,
having
its lower end 220 contoured or scalloped. Its length is selected relative to
the setting
nut 108 and upper end of cage slits 178 to also provide an interval where cage
expansion can occur in the absence of radial expansion pressure. However its
internal
10 bore is smooth to facilitate sliding relative to the mandrel.
Referring to FIGURES 11 and 13, the helical spring element 106 is largely
cylindrical
and comprised of a plurality of coaxial closely spaced coils formed with a
helix angle
slightly less than 45 with respect to the cylinder axis. In its preferred
embodiment, the
coils of the helical spring element 106, have a rectangular cross-section with
smooth
15 edges nearly touching when unloaded. When assembled between the upper
spring end
sleeve 107 and lower spring end sleeve 105 to form a helical spring expansion
assembly 164, the coil ends and sockets 216 form pivoting connections as shown
in
FIGURE 13. In operation, axial compression applied to the helical spring
expansion
assembly initially brings the coil edges into contact. Further application of
load tends to
20 cause the entire helical spring element to expand radially. Confined by the
cage 103,
which is in turn confined by the tubular work piece 113, the application of
sufficient
axial load results in a radial or pressure load being transferred through cage
103 and
reacted by work piece 113. The presence of such radial load at both the inner
and outer
surfaces of cage l03 enables frictional transfer of axial and radial loads
from upper end
25 158 of mandrel 104 to work piece 113 both through helical spring element
106 and
through cage ends 154 and 156. Spring element 106 must be of sufficient length
so that
the radially loaded interval provides an adequate area over which to mobilize
the
friction grip capacity required by the application. The thickness of spring
element 106,
and mating lower and upper spring end sleeves, 106 and 107, are selected to
ensure
30 sufficient contact area exists across the pivoting connections to transfer
the required
axial load when spring 106 is expanded.
CA 02512800 2001-03-22
31
The setting nut 108, is a largely cylindrical externally threaded nut with
internal
diameter slightly greater than the mandrel 104 main body interval 202 and
lower end
smooth faced to allow sliding contact with the upper end of the upper spring
end sleeve
107, which sliding contact may be enhanced by the addition of a thrust washer
or other
means generally known in the industry to manage wear and promote consistent
frictional resistance. The upper end of the setting nut 108 is upset and
carries external
spline 168 engaging internal spline 170 on lower end 172 of actuator sleeve
109, which
splined connection enables torque coupling while allowing relative axial
sliding
movement.
The actuator sleeve 109 is largely axisymmetric and rigid, with a generally
uniform
diameter external surface. Its internal surface is profiled to mate with three
components
as follows. Its lower end 172 forms an internally splined cylindrical sleeve
170 to
engage the matching exterior splines 168 in the upper end of the setting nut
108, which
splined connection is loose fitting providing a significant amount of
rotational back-
lash, and sufficiently long to accommodate the full travel of the setting nut
108.
Directly above the splined sleeve interval 170 is a relatively short
internally upset i mid-
section splined interval 174 engaging the mandrel 104 upper splined interval
176.
Above the mid-section splined interval 174 the bore increases to accommodate
hoisting
shoulder upset interval 210 of mandrel 104, with shoulder 212 of actuator
sleeve 109
engaging shoulder 208 of mandrel 104. The bore extends to the upper end of the
actuator sleeve 109, where it is provided with threads to connect with the
crossover sub
101.
When assembled, the actuator sleeve 109 is able to slide on the mandrel 104,
and is
constrained in its upper position by hoisting shoulder 208 on mandrel 104,
enabling
transfer of hoisting load from the mandrel 104 into the actuator sleeve 109.
The range
of motion from this upper position downward to the point where the actuator
sleeve and
mandrel splines disengage is referred to as torque mode, and is illustrated in
FIGURES
15 and 16. The interval between the position where actuator sleeve 109 is
lowered a
sufficient distance to first disengage the mandrel splines 176 and its lowest
position
constrained by contact with the top of setting nut 108, is referred to as
setting mode
position and is illustrated in FIGURES II and 14. The various interacting
component
CA 02512800 2001-03-22
32
lengths are preferably arranged so that the actuator has sufficient travel in
both torque
and setting modes to provide the function of a `floating cushion', where no
significant
axial load may be transferred between the tool and work piece.
In its preferred embodiment a flow tube 112 is provided between the interior
bores 188
and 148, respectively, of mandrel, 104, and crossover sub, 101. A lower end
224 of
flow tube, 112, is sealingly threaded to upper end 190 of the mandrel bore
188. An
upper end 226 of flow tube 112 extends telescopically into the lower end of
the
crossover sub bore 148 through an annular seal 228 carried in the lower end of
the
crossover sub bore 148. This configuration readily accommodates the required
range of
sliding between the crossover sub 101 and mandrel 104 while minimizing the
fluid end
load that would otherwise occur if sealing were provided between the mandrel
104 and
actuator sleeve 109.
In its preferred embodiment the nut I I I is provided with a lower conical end
230 to
facilitate stabbing into the tubular work piece 113. Where upper end 152 of
tubular
work piece 113 carries an interior box thread, as is typical for casing and
tubing joints,
the conical end surface is preferably coated with an elastomer or similar
relatively soft
material to mitigate the potential for damage to the threads.
In operation, with crossover sub 101 of the casing drive tool made up to the
quill of a
top drive rig, the grip assembly is lowered into the top end of a tubular
joint until the
cage stop ring 157 engages the top end surface, illustrated as collar 150, of
the joint.
The top drive is then further lowered or set down on the tool which causes the
actuator
sleeve 109 to displace downward until it disengages from spline 176 on mandrel
104
and simultaneously causes cage 103 to slide up lower splined interval 162 of
mandrel
104 until stopped by contact between lower spring end sleeve, 105 and lower
end 156
of cage 103. This position is referred to as setting mode, as illustrated in
FIGURE 11.
Right hand rotation of the top drive then drives nut 108 downward against
upper spring
end sleeve 107, which acts as an annular piston, compressing helical spring
106 causing
it to expand radially, thus forcing cage 103 outward and into contact with the
inside
surface of the tubular work piece, as illustrated in FIGURE 14. Continued
right hand
rotation causes largely biaxial compression of the helical spring element,
106, with
consequent development of significant contact stress between the cage 103 and
the
CA 02512800 2001-03-22
33
inner surface of the tubular over the length of the spring element. Frictional
resistance
to the compressive axial load is developed in the setting nut threads and end
face and is
manifest as torque at the top drive. It will be apparent that this torque is
reacted through
the tool into the tubular joint. Until the cage 103, is expanded, this
reaction is provided
by incidental friction of the cage strips 180, the packer cup 110 and contact
with the
stop ring 157. Once activated the cage expansion `self reacts' the increasing
setting
torque, a measurement of which is available to the top drive control system
and may be
used to limit the amount of setting force applied. When sufficient setting
torque has
been applied, the tool is considered set. FIGURE 14 shows a cross section of
the tool in
setting mode with the cage 103 expanded into contact with the tubular work
piece.
Once set, the top drive may be raised to engage the torque mode position,
where the
upward movement causes the actuator sleeve 109 to slide up relative to the
mandrel and
engage the splines 174 and 176, respectively, between the actuator sleeve 109
and
mandrel 104. At the upper extent of the actuator range of travel the actuator
sleeve
shoulder 212 engages the mandrel shoulder 208 to prevent the actuator sleeve
109 from
sliding off the top of the mandrel 104 and enable transfer of hoisting loads.
To facilitate
engagement of this spline, the mating spline tooth ends on both the mandrel
104 and
actuator sleeve 109 are appropriately tapered. Engagement is further
facilitated by the
relatively loose fitting spline engagement between the actuator sleeve 109,
and setting
nut 108 allowing some relatively free rotation. Thus in torque mode either
right or left
hand torque may by transferred through the actuator sleeve 109 directly to the
mandrel
104. FIGURE 15 shows the tool in torque mode, set inside a tubular work piece
as it
might appear prior to making up or breaking out a joint.
Thus set, if the joint is to be broken out, the top drive is positioned to
place the actuator
sleeve 109 at or near the upper limit of the `float' provided in torque mode,
and reverse
torque applied. Once broken out, the joint weight may be supported by the tool
and
raised out of the connection until gripped by separate pipe handling tools.
Once gripped
by the pipe handlers, the top drive is set down on the tool to a position near
the upper
limit of the float provided in set mode. Left hand torque is then applied and
the setting
nut, 108, rotated a sufficient number of turns to release the tool. The amount
of rotation
required to release will in general be equal to the number of turns required
for setting.
CA 02512800 2001-03-22
34
Alternately, if the joint is to be made up after the tool is set, the joint
weight may be
supported by the tool while being positioned and stabbed into the connection
to be
made up. Once stabbed, and with the top drive is positioned to place the
actuator
sleeve, 109, at or near the lower limit of the `float' provided in torque
mode, the
connection may be made up. As for break out, the tool is released by setting
down the
top drive to engage set mode and applying sufficient left hand rotation to
release the
tool.
FIGURE 16 shows the tool in torque mode, set inside a tubular work piece 113
as it
would appear while carrying hoisting load. Based on the teachings given herein
describing the load transfer behaviour of the helical spring assembly
interacting with
the cage 103 and tubular work piece 113, it will be evident to one skilled in
the art that
loads (axial and torque) applied to the mandrel 104 with the tool set and in
torque
mode, are reacted in part into the tubular work piece by coupling through the
helical
spring assembly and in part through the upper and lower ends of the cage. The
relatively stiff connection between the mandrel 104 and the helical spring
element 106
provided by the lower spring end sleeve 105 ensures that only torque loads
exceeding
the frictional capacity of the interfacial region of contact between the
helical spring
element 106 and cage 103 tend to be transferred to lower splined connection
between
the cage 103 and mandrel 104. This greatly reduces the magnitude of cyclic
torsional
load transferred through the lower interval of the cage 103, and hence
substantially
improves its operational fatigue life. Axial hoisting load is reacted through
the lower
spring end sleeve 105 and if it exceeds the setting load tends to cause
sliding in the
interval of travel allowed by the lower splined connection between the mandrel
104 and
the cage 103 which movement is evident as gap between the cage and lower
spring end
sleeve as shown in FIGURE 16 and allows an increase in the radial pressure
applied by
the helical spring element 106 and hence the frictional lifting capacity of
the grip
assembly. This `self energizing' tendency is highly valuable as a means to
ensure
sufficient frictional force is available to prevent slippage when hoisting. It
will be
further apparent that a portion of the axial load is reacted through the upper
spring end
sleeve 107 and into the top of the cage, 103, as tension, which tension for
large lifting
loads will tend to increase above that required for setting. However it will
only tend to
CA 02512800 2001-03-22
decrease significantly upon a substantial reduction in axial hoisting load
due, to the
reversal in direction the friction vectors must undergo when the direction of
sliding is
reversed. This behaviour has an advantageous effect on the fatigue life of the
cage, 103,
upper end similar to the manner in which the grip assembly responds to
fluctuations in
5 torque load.
Amoung other variables, the axial or torsional load required to initiate
slippage is
determined by the area in contact, the effective friction coefficient acting
between the
two surfaces, and the normal stress acting in the interfacial region between
the cage,
103, and work piece. It will be further evident to one skilled in the art that
to provide
10 sufficient torque and axial load capacity, these variables may be
manipulated in
numerous ways including: lengthening the expanded interval of the grip;
coating,
knurling or otherwise roughening the cage exterior to enhance the effective
friction
coefficient; and increasing the axial stress that may be applied to the
helical spring
assembly.
15 It will be apparent to one skilled in the art, that as the helical spring
element, 106, is
compressed from the top, sliding resistance will tend to cause the axial and
radial
contact stress to decrease from top to bottom over the element length. It has
been found
in practice that lubrication of the contacting surfaces can be employed to
reduce this
effect if required to either improve the `self starting' response or the
relationship
20 between setting torque and axial or torsional grip capacity.
The casing drive tool also provides a fluid conduit from the top drive quill
into the
tubular joint in which it is set. This is necessary in Casing DrillingTM
applications
where it is desired to apply fluid pressure or flow fluids into or out of the
tubular work
piece 113 and often occurs when running casing that must be filled from the
top. In its
25 preferred embodiment, the flow tube 112 connecting the internal bores of
the cross over
sub 101 and actuator sleeve 109, and the packer cup 110, support this
function.
Alternative embodiments
Sensors to provide measurements of torque and axial load may be incorporated
into the
actuator sleeve or other member of the load train or provided as separate
devices and
30 incorporated into the tool load train.
CA 02512800 2001-03-22
36
A hydraulic actuator may be used to provide the axial setting load on the
helical spring
element that causes expansion of the cage in place of the mechanical system of
the
preferred embodiment using a torque driven setting nut to apply the setting
load.
A stronger yet still readily expandable cage wall may be constructed by
joining at the
ends two or more individual layers of coaxial close fitting thin wall tubes,
each slit with
interlocking tabs in the manner of the single wall cage described for the
preferred
embodiment.
In a further aspect of the preferred embodiment, we believe the helical spring
element
may be provided in two close fitting concentric layers having their helix
angles wound
in opposite directions, and the upper spring end sleeve keyed to the mandrel
so that
relative axial sliding movement is allowed but not rotation. This arrangement
allows
the helical spring elements to be loaded without contact between the edges of
individual coils by reacting the torsion required to prevent edge contact
under
application of axial load. By adjusting the helix angle along the length of
the helical
spring element, this arrangement allows the relationship between axial load
and radial
pressure to be favourably adjusted to increase the overall grip capacity in a
given
length.
The method of internally gripping a work piece using a cage to enable torque
and axial
load transfer may be applied to applications where external gripping is
required by
inverting the grip architecture presented in the preferred embodiment. For
such an
inverted architecture the function of the mandrel is provided by a rigid outer
sleeve,
where the cage is coaxially positioned inside the outer sleeve and attached at
one end,
and the tubular work piece placed inside the cage. The helical spring element
is
disposed in the annular space between the mandrel and cage and means provided
to
activate the helical spring element with tension to cause the cage to contract
inward and
frictionally engage the outside surface of the tubular work piece with
sufficient radial
force to enable the mobilization of friction to transfer significant torque
and axial load
from the outer sleeve through the cage to the tubular.
