Note: Descriptions are shown in the official language in which they were submitted.
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TOP DRIVE UNIT, PIPE GRIPPING DEVICE AND METHOD OF
DRILLING A WELLBORE
The present invention relates to a top drive unit,
to a pipe gripping device for use with a top drive and to
a method of drilling a wellbore.
In the construction of an oil or gas well, a
borehole (or wellbore as it is sometimes known in the
art) is drilled into the earth. A drill bit is arranged
on the end of a drill string and is rotated to bore the
borehole. A drilling fluid known as "drilling mud" is
pumped through the drill string to the drill bit to inter
alia lubricate and cool the drill bit. The drilling mud
is also used to carry the cuttings produced by the drill
bit and other solids to the surface through an annulus
formed between the drill string and the borehole and/or
casing lining the borehole.
In one prior art method a kelly bar, connected to a
top joint of the drill string, is used to rotate the
drill string. A rotary table at the derrick floor level
rotates the kelly bar while simultaneously the kelly bar
can move vertically through a drive bushing within the
rotary table at the rig floor as the borehole deepens. In
another prior art method, a top drive drilling unit
suspended in a derrick grips and rotates the drill string
and a kelly bar is not used.
As the borehole deepens further sections of drill
pipe (usually "stands" each comprising two or three
lengths of drill pipe) must be added to the top of a
drill string in order to bore deeper; to add each stand
(or a single length of drill pipe) drilling is halted to
prevent inter alia spillage of drilling fluid. The
process of adding drill pipe to a drill string, and
particularly the step of applying the final torque to a
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new joint, has often been called "making up". Similarly
to remove drill pipe from the string, to "trip out" of a
hole, (e.g. to replace a drill bit or to cement a section
of casing), the process is reversed, and each stand of
drill pipe must be unscrewed from the drill string and
from the top drive; this can also require stopping
circulation of drilling fluid while each stand (or singly
length of drill pipe) is removed. The process of removing
drill pipe from a drill string, and particularly the step
of applying torque to undo a joint, has often been called
"breaking-out". Re-instituting the flow of drilling fluid
and reconstituting the required column of it in the
wellbore can take a significant amount of time, and the
effects of removing and then reintroducing the drilling
fluid into the wellbore can have harmful effects on
equipment, on the wellbore and on the formation being
drilled. In such circumstances, expensive and time-
consuming of additional fluid weighting may be required.
It is often preferable to maintain drilled cuttings
in suspension in the drilling fluid to facilitate moving
them away from a drill bit and to prevent them from
falling back down in a wellbore. Cessation of fluid
circulation can cause the drilled cuttings to sink. To
counter this in many prior art systems additional fluid
weighting is attempted, often increasing the viscosity of
the fluid. This results in the need for more pumping
power at the surface to move the thicker fluid; but such
an increase in pump force can result in over pressuring
of a downhole which can cause formation damage or loss of
fluids downhole.
It is a clear that the process of drilling (both
tripping into and out of the borehole) is interrupted
frequently. This is highly undesirable since inter alia
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average penetration rates are reduced.
To address this problem a continuous circulation
system (CCS) has been developed and is disclosed in WO
98/16716. The CCS allows circulation of drilling mud to
be carried out throughout the making-up and breaking-out
of pipe to and from a pipe string. WO 98/16716 discloses,
inter alia the use of an upper set of pipe rams to apply
and seal about part of a single length or stand of pipe
to be connected to the string, a lower set of pipe rams
to apply and seal about part of the pipe at the top of
the string in the well to create a chamber therebetween
and a blind ram to divide the chamber between the end pin
of the pipe to be connected and the box of the pipe at
the top of the string, to form upper and lower chambers.
A drilling mud inlet is arranged in the lower chamber
between the blind ram and the lower set of pipe rams and
a drilling mud supply is also provided at the top end of
the pipe to be connected.
To make a connection, the lower set of pipe rams is
activated to seal about the top end of the string of pipe
in the wellbore and the blind rams are activated to form
the lower chamber about the top of the drill string.
Drilling mud is allowed to flow into the lower chamber
and circulate into the top of the drill string. The
drilling mud passes through the drill string to the drill
bit and returns through an annulus formed by the drill
string and the borehole in the normal way. Meanwhile, a
single or stand of pipe is lowered into the top of the
continuous circulation system. The upper set of pipe rams
is activated to seal about the pipe. The upper end of the
single length or stand of pipe is attached to the supply
of drilling mud and drilling mud flows into the upper
chamber following actuation of a valve. The pressures in
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the upper and lower chambers are now substantially equal.
The blind ram is opened and the pin end of the single or
stand of pipe is stabbed into the box in the top end of
the string of pipe and spun and torqued to make the
connection. The drilling mud in the chamber may be
drained and the upper and lower pipe rams opened to allow
the pipe string with the added single or stand of pipe to
be lowered into the well. Thus circulation is continuous
through the pipe string and annulus whilst the connection
is made and broken. This is a substantial improvement
over the traditional drilling method.
Various improvements to the continuous circulation
system have been made, including conducting continuous
drilling whilst the single or stand of pipe is connected
or disconnected from the string. The CCS is useful for
drilling with drill pipe or when drilling with casing,
for example.
The CCS can be used in reverse i.e. to remove stands
of pipe when whilst continuously circulating drilling
fluid. Removal of stands or individual lengths of pipe
may take place for example when tripping out of the hole
or during a backreaming operation for example.
Backreaming may be desirable to smooth out the hole by
removing keyseats.
To maintain continuous circulation of drilling fluid
while tripping out it is necessary for the saver sub to
be connected to the top of the drill string in the CCS
unit. After connection drilling fluid is supplied through
the top drive as described above. It is then necessary to
raise the drill string above the CCS unit by
approximately one, two or three joints of pipe (i.e.
about 9.1m, 18.3m, and 27.5m respectively), depending on
the number of lengths of pipe to be removed from the
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string. The CCS unit is then able to disconnect the stand
from the drill string at the appropriate point whilst
maintaining flow of drilling fluid. The top drive is then
relieved of the duty of supplying drilling fluid.
However, the stand of drill pipe remains attached to the
saver sub and must be removed before the top drive can be
lowered back to the CCS unit to remove the next stand.
US-A-4 449 596 discloses a torque wrench suspended
below a top drive for breaking a joint between a saver
sub and a drill string. The torque wrench comprises an
upper section having a circular series of parallel
splines for engagement with corresponding splines on the
saver sub, and a lower section comprising two jaws, one
of which is moveable radially by a piston to engage the
drill string. In use, the torque wrench is moveable
axially along the drill string to bring the splines of
the upper section partly into engagement with the splines
of the saver sub. The piston in the lower section is
actuated to move the jaw into engagement with the drill
string. A pair of pistons, each connected to the upper
and lower sections is then actuated to apply relative
rotational movement between the upper and lower sections
to break the joint. After this the saver sub can be spun
out from the drill string with the top drive.
The drill string in US-A-4 449 596 can only be
brought into the torque wrench and attached to the saver
sub by axial movement along the drill string. Accordingly
when a new stand of pipe is attached and drilling
continues, the downward movement of the top drive is
limited by the torque wrench below. Since the
aforementioned CCS unit is situated between the rig floor
and the top drive, this also limits the amount of
downward movement of the top drive whilst drilling. With
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more apparatus being used during drilling between the top
drive and the rig floor there is a need for a device that
permits a stand of drill pipe to be removed quickly from
a top drive whilst the top drive is positioned some
distance above the rig floor, but which device does not
limit downward movement of the top drive whilst drilling
and/or whilst attaching the top drive to the top of the
drill string when tripping out of the well.
According to the present invention there is provided
a top drive unit comprising a top drive and a pipe
gripping device connectable beneath said top drive, the
arrangement being such that, in use, whilst a pipe is
connected to said top drive said pipe gripping device is
moveable between a first position in which said pipe is
accommodated within said pipe gripping device and a
second position in which said pipe is not accommodated
within said pipe gripping device. Preferably, the pipe is
connected to a short length of pipe, also known in the
art as a "saver sub", that is disposed between the top
drive and the drill string. The saver sub, although
expendable and therefore replaceable, is often considered
as part of the top drive.
Preferably, said pipe gripping device permits
movement having a component of direction substantially
radially toward/away from a longitudinal axis of said
pipe.
Advantageously, said top drive unit further
comprises a pivot mechanism for pivoting said pipe
gripping mechanism between said first and second
positions.
Preferably, in use said pivot mechanism provides a
pivoting action in a plane substantially parallel with a
longitudinal axis of said pipe.
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Advantageously, in use said pivot mechanism provides
a pivoting action in a plane substantially perpendicular
with a longitudinal axis of said pipe.
Preferably said pipe gripping device further
comprises an open throat for permitting said movement.
Advantageously, said pipe gripping device comprises
a body having first and second parts each part comprising
an opening defining said open throat, wherein in use said
first part provides a locking function in which rotation
of said body relative to said top drive is inhibited, and
said second part provides a rotating function relative to
said body or making/breaking connections between pipes.
Preferably, said pipe gripping device comprises a
body, a first jaw movably connected to the body, a second
jaw movably connected to the body.
Advantageously, said first jaw and said second jaw
are arranged for pivoting movement around two common
axes, pivoting around a first common axis for clamping
and releasing said pipe, and pivoting around a second
common axis for rotating said pipe to make/break a
connection with another pipe.
Preferably, said pipe gripping device further
comprises an actuation device for both moving said first
and second jaws to clamp and release said pipe, and for
making/breaking a connection with another pipe.
Advantageously, said first jaw and said second jaw
are pivotably connected to one another.
Preferably, said first jaw is connected to the
second jaw so that the first jaw and the second jaw move
together.
Advantageously, said pipe gripping device further
comprises:
a first piston/cylinder device movably
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interconnected with said first jaw,
a second piston/cylinder device movably
interconnected with said second jaw,
the first piston/cylinder device for moving the
first jaw to clamp a pipe and the second piston/cylinder
device for moving the second jaw to clamp the pipe, and
both the first piston/cylinder device and the second
piston/cylinder device for rotating the pipe.
Preferably, said first piston/cylinder device is
disposed for and is operable for moving said first jaw in
a first direction with respect to the pipe to locate said
first jaw with respect to the pipe, and said first
piston/cylinder device is disposed for and operable for
then moving said first jaw in a second direction opposite
to the first direction for clamping the pipe with the
first jaw.
Advantageously, said second piston/cylinder device
is disposed for and is operable for moving said first jaw
in the second direction with respect to the pipe to
locate said second jaw with respect to the pipe, and the
second piston/cylinder device is disposed for and
operable for then moving said second jaw generally in the
first direction for clamping the pipe with the second
jaw.
Preferably, said first piston/cylinder device is
disposed for and is, following clamping of the pipe
between the first jaw and the second jaw, operable for
moving the first jaw generally in the first direction for
rotating the pipe for breaking a connection between the
pipe and another tubular member, and
said second piston/cylinder device is disposed for
and is, following clamping of the pipe between the first
jaw and the second jaw, operable for moving the second
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jaw generally in the first direction for rotating the
pipe for breaking a connection between the pipe and said
another tubular member.
According to another aspect of the present invention
there is provided for use with a top drive, a pipe
gripping device having any of the pipe gripping device
features set our above.
According to another aspect of the present invention
there is provided a method of drilling a wellbore with a
top drive, which method comprises the step of whilst a
pipe is connected to said top drive, moving a pipe
gripping device having any of the features set out above
from a first position in which said pipe is accommodated
within said pipe gripping device to a second position in
which said pipe is not accommodated within said pipe
gripping device, or vice versa.
Advantageously, the method further comprises the
step of breaking with said pipe gripping device a
connection between said pipe and a pipe connected to said
top drive.
Preferably, the method further comprises the step of
making up with said pipe gripping device a connection
between said pipe and a pipe connected to said top drive.
Advantageously, said breaking step and/or making up
step is performed during a continuous drilling fluid
circulation method.
Preferably, the method further comprises the step
of, whilst said pipe is connected to said top drive
during tripping into the well, moving said pipe gripping
device away from a centre line of the well, whereby said
top drive may move closer to a floor of the drilling rig.
Advantageously, the method further comprises the
step of, whilst said pipe is connected to said top drive
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during tripping out of the well, moving said pipe
gripping device toward a centre line of the well, whereby
a connection between said top drive and said pipe may be
broken by said pipe gripping device.
The present invention, in at least certain
embodiments, teaches a new top drive drilling system with
a top drive drilling unit and a joint breaking system
suspended below the top drive drilling unit.
In certain aspects a top drive drilling system
according to the present invention includes a joint
handling system which, in one aspect, is a joint breaker
system that is a pipe gripper system according to the
present invention which has a body with an open throat
for receiving a tubular member and two selectively
engageable jaws for contacting and gripping a tubular
that has been positioned within the throat (in one
aspect, a piece of drill pipe which, in one aspect, may
be part of a stand of drill pipe). In one aspect each jaw
has an interconnected hydraulic cylinder apparatus which
is selectively controlled and activated to move the jaw
into gripping engagement with a tubular or to move it out
of gripping engagement with a tubular so that the tubular
can be moved out of the throat and away from the pipe
gripper system. In another aspect, e.g. by inverting the
system as it is used for joint breaking, the system can
be used, according to the present invention, to make
connections (with appropriate re-configuration of
hydraulic fluid lines).
In certain aspects such a gripper system is used not
to spin a tubular (as may be a tong), but to grip a
tubular and rotate sufficiently to break its threaded
connection to another corresponding tubular. In one
aspect hydraulic cylinder apparatuses which are used to
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effect gripping of a tubular are also used to effect
slight rotation of the tubular sufficient to break its
threaded connection with another tubular.
In one aspect a support for a pipe gripper system
according to the present invention (useful with grippers
according to the present invention and with prior art
grippers) has eye members connected to corresponding main
links which are connected to a top drive drilling unit.
Each eye member has a body with a channel therethrough
and a support shaft extends through each channel. A pipe
gripper body with the open throat is connected to lower
ends of these support shafts. Optionally, a holding
mechanism is connected to the upper ends of these shafts.
This holding mechanism has two upper latches, each with
an open throat, which encompass a part of the main links
that connect at the pipe gripper system to the top drive
drilling unit. These latches are selectively operable so
that in a first mode while drilling (and while tripping
or backreaming), the pipe gripper system [and, if
present, an elevator connected therebelow] hang below the
top drive drilling unit; and, in a second mode, the upper
latches pivot so that the previously-encompassed portions
of the main links exit from the upper latches freeing the
support shafts thereby permitting the pipe gripper system
(and equipment connected therebelow, if any; e.g., but
not limited to an elevator) to be moved away from a
center line coinciding with a center line of the
wellbore. Thus, in one particular aspect, an elevator
suspended below the pipe gripper system can be presented
to rig personnel, e.g., but not limited to a derrickman
for emplacement around a piece of drill pipe, e.g., but
not limited to, a piece of drill pipe in a stand of drill
pipe.
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Such a system can be used advantageously with a
continuous circulation system. The pipe gripper, with the
upper latches engaging or disengaging the main links, is
moved away from the wellbore center line and out of the
way of the continuous circulation system so that the top
drive drilling unit can continue to rotate a drill
string, permitting the top drive drilling unit to move
down further than it would be able to if the pipe gripper
system (and, if connected thereto, an elevator, etc.) was
still in the way beneath the continuous circulation
system.
In certain aspects, using an elevator having dual
opposed members which have dual interactive connection
apparatuses so that either side of the elevator can be
opened. Thus, the elevator can be opened on one side to
permit the elevator unit to be moved away from the
wellbore center line so that the top drive drilling unit
can drill the drill string down as far as possible before
adding a new piece or stand of drill pipe; and then the
elevator can be opened from the other side for receiving
a new piece or stand of drill pipe. In certain aspects,
such an elevator has dual opposed selectively releasable
latch mechanisms and dual opposed handling projections.
It is, therefore, an object of at least certain
preferred embodiments of the present invention to provide
a pipe gripper system in which the same piston/cylinder
devices are used in torquing a tubular as are used in
clamping a tubular;
Such systems and methods which employ an open throat
pipe gripper system suspended below a top drive drilling
unit; and
Such systems and methods with apparatus for
selectively locating the pipe gripper system operably
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beneath the top drive drilling unit and for selectively
moving the pipe gripper system away from such a position
for further tubular rotation by the top drive drilling
unit without the need for disconnecting the pipe gripper
system from its connection to the top drive drilling
unit.
The present invention, therefore, provides in some,
but not in necessarily all, embodiments a top drive
system with a top drive unit, and a pipe gripping system
connected to and beneath the top drive unit, the pipe
gripping system having an open throat for receiving a
tubular to be gripped by the pipe gripping system.
The present invention, therefore, provides in some,
but not in necessarily all, embodiments a top drive
system with a top drive unit, and a pipe gripping system
connected to and beneath the top drive unit, the pipe
gripping system having a body, a first jaw movably
connected to the body, a second jaw movably connected to
the body, a first piston/cylinder device movably
interconnected with the first jaw, a second
piston/cylinder device movably interconnected with the
second jaw, the first piston/cylinder device for moving
the first jaw to clamp a pipe and the second
piston/cylinder device for moving the second jaw to clamp
the pipe, and both the first piston/cylinder device and
the second piston/cylinder device for rotating the pipe.
Such a pipe gripping system may have one or some, in
any possible combination, of the following: connectible
to and beneath a top drive unit, the pipe gripping system
having an open throat for receiving a tubular to be
gripped by the pipe gripping system; and/or wherein the
pipe gripping system has a body, a first jaw movably
connected to the body, a second jaw movably connected to
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the body, the first jaw connected to the second jaw so
that the first jaw and the second jaw move together.
The present invention, therefore, provides in some,
but not in necessarily all, embodiments a pipe gripping
system which is connectible to and beneath a top drive
unit, the pipe gripping system having a body, a first jaw
movably connected to the body, a second jaw movably
connected to the body, a first piston/cylinder device
movably interconnected with the first jaw, a second
piston/cylinder device movably interconnected with the
second jaw, the first piston/cylinder device for moving
the first jaw to clamp a pipe and the second
piston/cylinder device for moving the second jaw to clamp
the pipe, and both the first piston/cylinder device and
the second piston/cylinder device for rotating the pipe.
Such a pipe gripping system may have one or some, in any
possible combination, of the following: wherein the first
jaw is connected to the second jaw so that the first jaw
and the second jaw move together; wherein the first
piston/cylinder device is disposed for and is operable
for pulling the first jaw in a first direction with
respect to the pipe to locate the first jaw with respect
to the pipe and the first piston/cylinder device is
disposed for and operable for then moving the first jaw
in a second direction opposite to the first direction for
clamping the pipe with the first jaw; wherein the second
piston/cylinder device is disposed for and is operable
for pulling the first jaw in the second direction with
respect to the pipe to locate the second jaw with respect
to the pipe and the second piston/cylinder device is
disposed for and operable for then moving the second jaw
generally in the first direction clamping the pipe with
the second jaw; and/or wherein the first piston/cylinder
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device is disposed for and is, following clamping of the
pipe between the first jaw and the second jaw, operable
for moving the first jaw generally in the first direction
for rotating the pipe for breaking a connection between
the pipe and another tubular member, and the second
piston/cylinder device is disposed for and is, following
clamping of the pipe between the first jaw and the second
jaw, operable for moving the second jaw generally in the
first direction for rotating the pipe for breaking a
connection between the pipe and the another tubular
member.
The present invention, therefore, provides in some,
but not in necessarily all, embodiments a method for
gripping a tubular member beneath a top drive unit, the
method including moving a portion of a tubular member
into a gripping system, the gripping system located
beneath the top drive unit and having an open throat for
receiving a tubular to be gripped by the pipe gripping
system, the gripping system having a gripping mechanism
for gripping the tubular member, the portion of the
tubular member moved into the open throat of the gripping
system, and gripping the portion of the tubular member
with the gripping mechanism of the gripping system.
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For a better understanding of the present invention,
reference will now be made, by way of example, to the
accompanying drawings, in which:
Figure 1A is a front elevation view of a prior art
well drilling apparatus;
Figure 1B is a side elevational view taken on line
1B-1B of Figure 1A but showing the drilling unit swung to
its mouse-hole position;
Figure 1C is a fragmentary front elevational view
showing part of the drilling unit of Figure 1A swung to
its retracted position permitting a trip of the well pipe
into or out of the well;
Figure 2 is a perspective view of a top drive unit
according to the present invention mounted on a derrick
in use with a Continuous Circulation System (CCS);
Figure 2A is a perspective view of the pipe gripping
unit that is connected to the top drive unit in Figure 2;
Figures 2B and 2C are perspective cut-away views of
part of the pipe gripping device in Figure 2;
Figure 3A is a plan view, partly in cut-away and in
cross-section, of the pipe gripping device of Figures 2A
and 2B in use with a tubular;
Figure 3B is an enlarged plan cross section of the
cut-away in Figure 3A;
Figures 4 to 8 are plan views showing steps in the
operation of the pipe gripping device of Figure 3A;
Figures 9A - 9C are plan views of an alternative
embodiment of jaws for the pipe gripping device of Fig.
2, each Figure showing a different position of an
adjustment mechanism enabling the pipe gripping device to
accommodate tubulars of different diameter;
Figure 10 is a side view of a top drive unit of
Figure 2 in a first stage of operation;
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Figure 11 is a side view of the top drive unit of
Figure 10 in a second stage of operation;
Figure 12 is a perspective view of the pipe gripping
unit of Figures 10 and 11 having been swung away from the
drill string; and
Figure 13 is a side view of the top drive unit in
Figure 2 with the pipe gripping device swung away from
the drill pipe to permit the top drive to drill to move
adjacent the CCS unit.
Figures 1A - 1C show a prior art rig and top drive
system 1010 as disclosed in U.S. 4,458,768.
The prior art drilling rig 1010 comprises a derrick
1011 projecting upwardly above a location at which a well
bore 1012 is being drilled by a rotary drill string 1013
formed in conventional manner in a series of drill pipe
stands connected together in end to end fashion at
threaded connections 1014. The string 1013 is turned
about the vertical axis 1015 of the well by a drilling
unit 1016 (e.g. top drive) connected to the upper end of
the string. The drill string and drilling unit 1016 are
supported and adapted to be moved upwardly and downwardly
by a hoisting mechanism 1017 including a crown block
1018, travelling block 1019, tackle 1020, supporting
travelling block 1019 from crown block 1018, and power
driven draw works for reeling the line 1020 in or out to
raise or lower the travelling block 1019. The travelling
block 1019 supports a hook 1Q21 from which the drilling
unit 1016 is suspended, and which has a gate 1121 adapted
to be opened for connecting and disconnecting the
drilling unit 1016. The drilling unit 1016 and hook 1019
are guided during their upward and downward movement by
two sectionally formed parallel elongated guide rails
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1022 and 1023, engaging and guiding a carriage 1024
forming a portion of the drilling unit 1016 and a
carriage 1025 to which the travelling block 1019 is
connected.
The two sectionally formed guide rails 1022 and 1023
are preferably of H shaped horizontal sectional
configuration that continues from the upper extremity of
each rail to its lower extremity. The rails 1022 and 1023
have upper sections which extend from the upper end of
derrick 1011 to a mid-derrick location and are attached
rigidly to the derrick for retention stationary in
positions of extension directly vertically and parallel
to one another and to well axis 1015. Beneath the mid-
derrick location the two guide rails have second portions
or sections extending parallel to one another, continuing
downwardly and to locations 1027, and mounted by two
pivotal connections for swinging movement relative to
upper sections and about a horizontal axis. An inclined
mousehole 1030 is used (Figure 1B).
The rails have third lowermost sections which are
carried by the second sections for swinging movement
therewith between the vertical and inclined positions and
which also are mounted by connections 1031 and 1032 for
horizontal swinging movement about two axes 1033 and 1034
which are parallel to one another and to the longitudinal
axes of the second sections.
The two pivotal connections 1031 and 1032 include
two parallel mounting pipes or tubes 1037 and 1038
connected rigidly to the second sections. The two second
rail sections are adapted to be power actuated between
the vertical and inclined positions by a piston and
cylinder mechanism 1045 whose cylinder is connected to a
horizontally extending stationary portion of the derrick
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1011, and whose piston rod acts against the tube 1037 of
pivotal connection 1031.
Carriage 1025 to which travelling block 1019 is
connected includes two frames 1056 and 1057 extending
partially about the rails 1022 and 1023 respectively and
rotatably carrying rollers 1058 which are received
between and engage the front and rear flanges 1059 of the
various rail sections in a manner effectively locating
carriage 1025 against movement transversely of the
longitudinal axis of the rail structure, and guiding the
carriage for movement only longitudinally of the rails.
The drilling unit 1016 includes the previously
mentioned rail contacting carriage structure 1024, a
power unit 1061 for turning the string, and a
conventional swivel 1062 for delivering drilling fluid to
the drill string 1013.
The power unit 1061 of the drilling assembly
includes a pipe section having a lower tapered external
thread forming a pin and threadedly connectable to the
upper end of drill string 1013 to drive it. In most
instances, a conventional crossover sub 1072 and a short
"pup joint" 1073 are connected into the string directly
beneath the power unit. At its upper end, pipe section
1070 has a tapered internal thread connectable to the
rotary stem 1075 of swivel 1062. The rotary stem 1075
turns with the drill string 1013 relative to the body
1076 of the swivel 1062. The body 1076 is supported in
non rotating relation by a bail 1077 engaging hook 1021
of the travelling block 1019. Drilling fluid is supplied
to the swivel 1062 through a flexible inlet hose 1078,
whose second end is connected to the derrick at an
elevated location 1079 well above the level of the rig
floor. For driving the tubular shaft 1070, power unit
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1061 includes an electric motor.
Figure 2 shows a top drive drilling system 10
according to the present invention which includes a top
drive drilling unit 20 ("TD 20") suspended in a derrick
12 (like the rig and derrick in Figure 1A with the
various parts etc. as shown in Figure 1A). A continuous
circulation system 30 ("CCS 30") rests on a rig floor 14
and part of a saver sub 22 projects up from the CCS 30.
The saver sub 22 is connected to and rotated by the TD
20.
The CCS 30 is any known continuous circulation
system and is, in one aspect, a CCS system commercially
available from Varco International, Inc. The CCS 30
operates as described in the introduction above.
An elevator 40 is suspended below the TD 20 and a
pipe gripping device 50 ("PG 50") is suspended from the
TD 20 above the elevator 40. Any suitable known elevator
may be used with the pipe gripping device 50. The PG 50
is suspended from the TD 20 with links 18 and the
elevator 40 is suspended from the PG 50 with links 24.
Referring to Figure 2A the pipe gripping device
generally identified by reference numeral 110 is
suspended at one end of a pair of main links 104' below
the top drive 102' ; the other ends of the main links are
connected to the top drive 102' (see Figure 2). The pipe
gripping device 110 comprises a holding mechanism 150'
and a movement mechanism 120'. The holding mechanism 150'
enables the pipe gripping mechanism 110 to be
substantially locked in position relative to the main
links 104', in which position swinging of the pipe
gripping device 110 about the main links 104' is
inhibited. The movement mechanism 120' enables the pipe
gripping device to be moved between a retracted position
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in which the saver sub 160' of the top drive 102' is free
to rotate, and an extended position in which the saver
sub 160' is prevented from rotating as described in
greater detail below.
The holding mechanism 150' has a housing 151'
comprising upper and lower plates (only one shown in Fig.
2A), to which are pivotally connected two plate members
152'. The housing 151' is connected via intermediate
springs 126' to a pair of shafts 125' that extend
upwardly from a pipe gripping device 110. Each plate
member 152' has an open throat 155' within which is
releasably positioned part of main link 104'. The open
throat 155' is defined by two fingers 157a' and 157b' and
the remaining plate member which are all integrally
formed from one sheet plate of metal, although any other
suitable material may be used. Each plate member 152'
pivots on top of shafts 125' against intermediate springs
126'. To selectively prevent such pivoting, a pin 156b'
is inserted through each plate member 152'. A yoke plate
156 is arranged centrally on the end of a rod of a
piston/cylinder apparatus 156a' (see Fig. 12), which
cylinder is fixed to the housing 151' and the rod of
which passes through the upper and lower plates 151a' and
151b'. The yoke plate 156' has two ends, each connected
to top of the pins 156b'. Upon retraction of the rod into
the piston/cylinder 156a', the pins 156b' pass through
holes in each plate member 152' to lock the plate member
152' in position. Each plate member 152' has at least one
hole to lock the links and the pipe gripping device 110
in relation to one another when depending vertically and
in line with the well centre (as shown in Fig. 2A). In
this position the main links 104' are held within the
throats 155' which are sufficiently deep so that the main
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links 104' as shown in Figure 2A cannot move out of the
throats 155' when in that position. With the bolts 156c'
removed when the cylinder 156a' raises the plate 156',
the members 152' are free to pivot and, thus, the main
links 104' are freed to move away from the throats 155',
as shown in Figure 12, and the pipe gripping device hangs
under gravity below main links 104'. Swinging of the pipe
gripping device 110 is inhibited by the interaction
between the plate members 152', the intermediate springs
126' and the shafts 125'.
The movement system 120' has piston/cylinders 128
for moving the pipe gripping device 110 up and down
relative to the main links 104' and therefore relative
the top drive 102' and saver sub 106'. Upper ends of
piston rods 128d' are secured to the bodies 123' each
having an eye 121', and lower ends of the cylinders 132'
are secured to a main body 129' of the pipe gripping
device 110. Optional protective railings 131' connected
to the main body 129' encompass part of the perimeter of
the pipe gripping system 110 to inter alia protect its
various parts. Mounting posts 128c', move in
corresponding tubes 128a'. Actuation of the
piston/cylinders 128 causes the pipe gripping device 110
to move or down via relative movement between the
mounting posts 128c' and tubes 128a'.
Referring to Figures 2A and 2B the pipe gripping
device 110 comprises a body 129 and two movable jaws 111,
112. The jaw 111 is pivotably connected with a pin 113 to
a movable member 114 and the jaw 112 is pivotably
connected with a pin 115 to a movable member 116 via a
connecting bar 117. The movable member 114 is connected
to four shafts 118 and the movable member 116 is
connected to four shafts 119. An end 133 of the
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connection bar 117 is secured with a pin 134 to the jaw
112. A gripping insert apparatus 135 with a removable
insert 136 is releasably held on the jaw 112 by removable
bolts 137. Studs 149 insure proper placement of the
removable insert 136 in a groove 153 of a holder 135. A
shoulder screw 138 (see also Figure 9A and accompanying
description) extends through the jaw 112. The connection
bar 117 has a hole 139 which receives a pin 143 which
passes through the jaw 112. The connection bar 117 shown
in Figure 2A is a top connection bar and a similar lower
connection bar 117b (see Figure 9A; shown in outline in
Figure 2B) is connected to the jaw 112 by the same pins
115, 134, 143. The connection bars 117 and 117b permit
pivoting of the jaw 112 about pin 115.
The jaw 111 has a gripping insert apparatus 144
releasably secured to the jaw 111. Bolts 146a releasably
secure the gripping insert apparatus 144 to the insert
holder body 157. An insert 147 is held within a groove
148 by studs 149a. Bolts 146 secure the insert holder
body 157 to the jaw 111. An end 154 of the insert holder
body 157 is held in a recess 155 defined by part of the
jaw 111 and by lips 156.
A hole 158 in the jaw 111 receives a pin 159 that
projects through the jaw 111 and permits pivotal movement
of the jaw 111 with respect to the jaw 112. The jaw 111
includes top and bottom parts llla, lllb respectively
(see Fig. 2A).
The body 129 has an open throat 161 for receiving a
portion of a tubular, e.g., but not limited to, a
tubular, a drill pipe, a saver sub, or a splined portion
of a saver sub used with a top drive drilling system. The
open throat 161 ensures that only radial movement (with
respect to a tubular) is needed to bring pipe gripping
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device 110 into and out of engagement with the tubular;
although it will be appreciated that other directions of
movement can be incorporated with the radial movement if
desired.
The movable member 114 is connected to a base member
162 by the shafts 118. The movable member 116 is
connected to a base 168 by the shafts 119.
Trunnion blocks 165 and 165a (only 165 shown in
Figs. 2A and 2B) are connected to a parts of piston/rod
assemblies as described below. Bolts 165d connect the
trunnion blocks 165 to a splined torque plate 165f (see
Figure 10). The splined torque plate 165f comprises an
open throat similar to the open throat 161, and is
substantially in alignment therewith to define an opening
on one side of the pipe gripping device 110. The splines
of the splined torque plate 165f do not form a closed
circle in plan view. The movable member 116 is secured to
a connector 166 (part of a piston/rod assembly) which has
a hole 166a through which extends a pin 166b which is
integral with the trunnion block 165 above it. Similarly,
the movable member 114 is secured to a connector 164
(part of a piston/rod assembly) which has a hole 164a
through which extends a pin 164b which is integral with
the trunnion block 165a (see Figure 10). A framework 131
(solid or tubular) encompasses the body 129.
Figure 3B shows in detail a selectively activatable
piston 170 with one end 170a sealingly disposed within a
recess 171 in the insert holder body 157 and another end
170b projecting out from the recess 171 to contact the
jaw 112. Hydraulic fluid under pressure in a hose 170c is
applied to the end 170a of the piston 170 to initially
maintain the jaws 111, 112 in the position shown in
Figures 3A and 4 i.e. inhibiting rotation of the jaws
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relative to one another about pin 159 to keep them in an
open position for receiving and releasing a tubular. The
hydraulic fluid under pressure can be supplied from a
separate source; from existing hydraulic lines, e.g.
lines to a top drive; and/or from a manifold interposed
between an hydraulic power source and the gripper system
110. However, it is preferred that hydraulic fluid is
supplied from the shaft 164c piston/rod assembly
associated with connector 164.
Referring to Fig. 3A the piston/rod assembly with
the connector 166 has a shaft 166c to which is connected
a piston 166d which is movable within a housing 166e in
response to hydraulic fluid under pressure (from any of
the sources for the hydraulic power that moves the piston
170) introduced into the housing 166e. As shown in the
"stored" position of Figure 3A, pressure is applied to a
surface 166f of the end 166d to maintain the jaw 112 in
the position shown i.e. in a retracted position relative
to the drill pipe DP.
The piston/rod assembly with the connector 164 has a
shaft 164c to which is connected a piston 164d which is
movable within a housing 164e in response to hydraulic
fluid under pressure introduced into the housing 164e.
The housing 164e has hydraulic power fluid channels 164p
and 164r for introducing/venting hydraulic power fluid
from either side of the piston 166d. The housing 164e has
hydraulic power fluid channels 164p and 164r (see Fig.
2B) for introducing/venting hydraulic power fluid from
either side of the piston 164d. As shown in Figure 3A in
the "stored" position, pressure is applied to a surface
164f of the piston 164d to maintain the jaw 111 in the
position shown; as mentioned above hydraulic fluid is
supplied at the same time to actuate the piston 170.
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Figures 4 - 7 illustrate a method according to the
present invention for gripping and torquing a tubular,
e.g., in one aspect, a piece of drill pipe, to engage the
tubular and then to break a connection between the
tubular and another member (e.g., in one aspect, between
the tubular and a saver sub of a top drive system). It is
within the scope of the present invention to invert the
system 110 and use it to make up connections between
tubulars.
The steps performed by the pipe gripping device 110
are carried out during use of the CCS unit 30 for
continuous circulation of drilling fluid during tripping
out of the well, as described above in the introduction.
In particular, the pipe gripping device breaks the
connection between the saver sub and a stand of drill
pipe after the lower joint of the stand has been broken
by the CCS unit 30 and after the upper chamber in the CCS
unit has been drained of drilling fluid. Following
breaking of the upper joint the stand of drill pipe is
supported by the elevator 40 for racking in a pipe rack
for example.
When a driller initiates a method according to the
present invention to break a saver-sub/drill-pipe
connection, e.g. by pressing a button on the driller's
console, hydraulic fluid is supplied to the
piston/cylinder 128' (see Fig. 2A) and piston/cylinder
156a' (see Fig. 12). As described above this actuates the
movement mechanism 120' to lower the pipe gripping device
110 such that the splines of the splined torque plate
165f interengage with the splines at the end of the saver
sub, and bring the jaws 111, 112 into alignment with the
box of the drill string. Furthermore movement of the
piston/cylinder 156a' causes locking of the plate members
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152' relative to the housing 151', thereby inhibiting
swinging of the pipe gripping device 110 about ends of
the main links 104'.
Referring to Figure 4, hydraulic fluid under
pressure is then applied to a surface 166g of the piston
166d which moves the housing 166e and the components
connected to it including the connection bars 117, the
jaw 112, and the jaw 111 as shown in Figure 4 so that the
jaws are disposed about a drill pipe DP. The piston/rod
assembly 166 pivots inwardly toward the drill pipe DP
about the pin 166b to permit the moveable member 116 to
move outwardly along the shaft 166c without pulling the
jaws across the longitudinal axis of the drill pipe DP
(leftwards in the sense of Fig. 4) . At the same time the
piston/rod assembly 164 pivots inwardly toward the drill
pipe DP about the pin 164b, so that the jaws are not
pulled in the opposite sense across the longitudinal axis
of the drill pipe DP (rightwards in the sense of Fig. 4).
The effect of this is that the spacing between the grips
136 and 146 remains the same, but the jaws 111 and 112
have been moved from a retracted or stored position (see
Fig. 3A), to a position in which the grips now lie on the
diameter of the drill pipe DP.
As shown in Figure 5A, the application of hydraulic
fluid under pressure to a surface 164g (and at the same
time releasing of hydraulic pressure on surface 164f) of
the piston 164d moves the housing 164e outwardly and
moves the jaw 111 as shown so that the jaws 111, 112 now
grip the drill pipe DP as shown in Figure 5A. In
particular, the jaws 111, 112 are rotated about the
longitudinal axis of the drill pipe DP via movement of
the housing 164e along the shaft 164c. To permit this
rotation, the housing 166e moves back along the shaft
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166c; otherwise the movement of the housing 164e and jaw
111 would push of the drill pipe DP out of the gripping
device. As explained above, hydraulic fluid pressure is
only maintained on piston 170 whilst pressure is
maintained on surface 164f. Accordingly, at the same time
as pressure is released from surface 164f, the piston 170
is able to retract. The tendency of both housing 164e and
166e to move outwardly is resisted by contact between the
jaw 112 and the drill pipe DP. Thus the weight of the
stand drill pipe (recalling that it is hanging from the
saver sub) resists further movement of the housing 166e
outwardly. The tendency is therefore for the pivot pin
159 on jaw 112 to be moved inwardly about a pivot point
on the drill pipe DP; this is counteracted by the
tendency for the jaw 111 to pull the pivot pin 159
outwardly. The hydraulic pressure applied to the surfaces
164g and 166g therefore causes the jaws 111, 112 to pivot
about the pin 159 (since no resistance is provided by the
piston 170) to bring the grips 136 and 147 into
engagement with the outer surface of the drill pipe DP.
As shown in Figure 5B venting of the fluid from the end
170a of the piston 170 allowing the piston 170 to retract
within the recess 171 permits the jaw 112 to move with
respect to the jaw 111 to the positions shown in Figures
5A - 6.
The grips 136 and 147 are now firmly in engagement
with the drill pipe DP applying a compression force but
no rotational force. Furthermore by actuating the piston
166 first the jaws 111, 112 are permitted to move through
a larger angle to break the joint as described below.
Figure 6 illustrates the breaking of a connection,
e.g. a connection between the drill pipe DP and a saver
sub to which it is connected. The pipe gripping device
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110 enables a rotational force to be applied by the jaws
111, 112 to the drill DP, whilst maintaining sufficient
compression force to engage the drill pipe DP with the
grips 136, 147.
In particular, hydraulic fluid pressure is now
applied to the surface 166f. This pushes the housing 166e
inwardly, causing the jaw 112 and therefore the pin 159
to try to move in the same direction. However, this force
is opposed by the outward force caused by hydraulic
pressure on surface 164g, causing the jaw 111 and pin 159
to move outwardly. The result is that the jaws 111, 112
are caused to maintain their compression force on the
drill pipe DP; however, now the two forces applied by the
jaws are in opposite directions on opposite sides of the
drill pipe DP resulting in a rotational force. The pivot
pins 164b and 166b permit the shafts 164c and 166c to
rotate, and therefore the jaws 111, 112 to rotate about
the drill pipe without widening the separation between
grips 136, 147. If sufficient hydraulic pressure is
applied this results in turning of the drill pipe DP in
the direction of the arrow A as ends 117a of the
connection bars 117 move in the direction of the arrow W
moving the jaw 112 in the direction of the arrow R1 while
the jaw 111 moves in the direction of the arrow R2. The
saver sub (not shown in Figure 6) is held substantially
still by a splined portion 165e of the splined torque
plate 165f (see Figure 10) so that the saver-sub-drill-
pipe connection can be broken. Figures 10 and 11 show a
top drive TD (partially) with links LS that support a
support system SS that supports the pipe gripping device
110 from which are suspended links LK which support the
elevator 230 and, in Figure 11, drill pipe DR.
Figure 7 shows the limit of travel of the jaws 111
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and 112 provided by the pistons 164d and 166d in their
respective housing 164e and 166e. The drill pipe has been
turned sufficiently to break the connection. In order to
ensure reliable release of the grips 136 and 147 from the
drill pipe, the piston 170 is actuated causing the jaws
111, 112 to pivot apart.
As shown in Figure 8 the jaws 111, 112 are then
moved to their original position or "stored" position (as
in Figure 3A). In this position the piston 170 has
returned to its initial position (see Figure 3B).
The pipe gripper device 110 can then be retracted by
actuating the piston/cylinders 128/ to disengage the
splined torque plate 165f from the splines of the saver
sub. The top drive can then spin out the saver sub from
the drill pipe. For this purpose the other end of the
drill pipe may or may not be held by an iron roughneck in
the CCS unit 30.
Referring to Fig. 13, when the top drive 20 is
tripping into or out of the hole, the pipe gripping
device 110 can be swung on the main links 104' away from
the centre line of the well. This allows the saver sub to
get close enough to the CCS unit 30 to enable continuous
circulation to take place as described above. The pipe
gripping device is swung out away from the wellbore
centre line by winching a tugger line 250', whereupon the
elevator 140 seats itself on a seat 254' attached to the
end of the tugger line 250' and pulls pipe gripping
device 110 radially and upwardly out of line with the
wellbore centreline, allowing the saver sub to be lowered
into the CCS 240 to locate the top of the drill string
(if tripping out). If tripping in, the open throat 161
and the open throat of the splined torque plate 165f
enable the pipe gripping device 110 to be moved radially
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away from the well centre line without having to
disconnect the saver sub from the top of the drill
string. During raising of the top drive 20, the tugger
line 250' can be gradually released to allow the pipe
gripping device 110 to swing back to the well centre line
under its own weight.
As shown in Figures 9A - 9C a device according to
the present invention (like the pipe gripping device 110
can effectively accommodate tubulars of different
diameters. As shown in Figure 9A by using spacers 181,
182 and a nut 183 and cotter pin 184 with the shoulder
screw 138, part 138a of the shoulder screw 138 projects
inwardly of the jaw 112 to serve as a stop for a tubular
(e.g., but not limited to, drill pipe between 3.5 inches
and 4 inches in diameter).
Figure 9B shows the use of spacers 185 and 186 with
the shoulder screw 138 so that part 138a of he shoulder
screw projects inwardly of the jaw 112 to serve as a stop
for a tubular (e.g., but not limited to, drill pipe
between 4.5 and 5 inches in diameter).
Figure 9C shows the use of spacers 187 and 188 with
the shoulder screw 138 so that part 138a of he shoulder
screw projects inwardly of the jaw 112 to serve as a stop
for a tubular (e.g., but not limited to, drill pipe
between 5.5 and 5 inches in diameter).
By using the shoulder screw 138 and associated
spacers as shown in Figures 9A - 9C, a tubular is
positioned between the jaws 111, 112 so that the inserts
136, 147 are diametrically opposed across the tubular,
enhancing efficient gripping of the tubular by the jaws
111, 112. Alternatively and/or in addition to this method
of accommodating different size tubulars, jaws with
different dimensions may be used.
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When a system according to the present invention
uses hydraulic power lines for an existing top drive
and/or for an existing upper pipe handler, the in-place
driller's console, buttons, and controls can be used to
control the pipe gripper system according to the present
invention. Alternatively a completely separate hydraulic
power system and/or controls may be used.
The present invention teaches a pipe gripper in
which the same hydraulic piston/cylinder devices are used
to clamp a tubular and then used to rotate the same
tubular. These devices may be incorporated into known
pipe handlers and iron roughnecks. An extended saver sub
may be used with any pipe gripper system according to the
present invention, e.g. to bring a connection within a
continuous circulation system.
