Note: Descriptions are shown in the official language in which they were submitted.
CA 02547944 2000-11-17
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WRENCHING TONG
This is a divisional application of Canadian Patent Application Serial No.
2,389,449 filed on November 17, 2000.
S This invention relates to wrenching tongs and other power tongs. It should
be
understood that the expression "the invention" and the like encompasses the
subject
matter of both the parent and the divisional applications.
In the construction of oil or gas wells it is usually necessary to construct
long drill
pipes. Due to the length of these pipes, sections or stands of pipe are
progressively added
to the pipe as it is lowered into the well from a drilling platform. In
particular, when it is
desired to add a section or stand of pipe the string is usually restrained
from falling into
the well by applying the slips of a spider located in the floor of the
drilling platform. The
new section or stand of pipe is then moved from a rack to the well centre
above the
spider. The threaded pin of the section or stand of pipe to be connected is
then located
over the threaded box of the pipe in the well and the connection is made up by
rotation
therebetween. An elevator is connected to the top of the new section or stand
and the
whole pipe string lifted slightly to enable the slips of the spider to be
released. The whole
pipe string is then lowered until the top of the section is adjacent the
spider whereupon
the slips of the spider are re-applied, the elevator disconnected and the
process repeated.
It is common practice to use a power tong to torque the connection up to a
predetermined torque in order to make this connection. The power tong is
located on the
platform, either on rails, or hung from a dernck on a chain. In order to make
up or break
out a threaded connection, a two tong arrangement is necessary. An active (or
wrenching) tong supplies torque to the section of pipe above the threaded
connection,
while a passive (or back up) tong supplies a reaction torque below the
threaded
connection. The back up tong clamps the pipe below the threaded connection,
and
prevents it from rotating. This clamping can be performed mechanically,
hydraulically or
pneumatically. The wrenching tong clamps the upper part of the connection and
is driven
so that it supplies torque for a limited angle.
This power tong arrangement is also used to torque up connections between
other
tubulars, for example casing and tubing.
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Normally, in order to supply high torque, the wrenching tong is driven
hydraulically. One or two hydzaulic cylinders drive the tong tlv-ough a small
angle,
- typically in the region of 25°, depending on the tong design. Due to
the geometric
configuration normally used, the torque output of the tong changes as a sine
function
of the angle driven, which results in a reduction of torque output across the
drive
eagle ofup to 15%.
In order to makeup or break out a connection of modern drill pipe or casing,
high-torgue must be supplied over a large angle, 'This angle is sometimes six
times
higher than a conventional wrenching tong can supply. Tn order to overcome
this, the
wrenching tong must grip and wrench the tubular several times to tig~rteu, or
break the
threaded connection fully. This has a number of disadvantages. The action of
gripping and releasing the pipe repeatedly can damage the pipe surface. Due to
the
high costs associated with the const~ction of oil aid gab wells, time is
critical, and
the repeated clamping and unclamping of the wrenching tong greatly increases
the
time taken to attach each new section or stead of tubulars. It alsD has the
effect that
the torque provided is discontinuous, increasing the di~culty of accurately
controlling the torque with respect to the angle turned.
WO 93118276 discloses as apparatus for applying torque to a first tubular
rels4,ve to a .second tubulat. The apparatus compares fit'st and second tongs
for
~PP~ ~e ~ ~ second tubulars, respectively.
GB 2128524 discloses a tong for gripping a tubular, driven by a pinion and
gear.
GB 1215967 discloses a tool secured in rotary table slips, and tongs for
coupling and uncoupling tubulars.
According to a first aspect of the present invention there is grovided
apparatus
for applying torque to a ~rst tubular relative to a second tubular, the
apparatus
comprising a first tong for gripping the first tubular and a seGOnd tong far
gripping the
second tubular, wherein the first tong is provided with teeth around a
peripheral
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2a
surface thereof, the second tong is provided with at least one pinion, and the
pinion
meshes with the teeth in such a way that the first tong and the second tong
can be rotated
relative to one another when the pinion is rotated.
S
The present invention also provides a method of coupling a tool to a length of
tubular, the
method comprising the steps of securing the tool in a basket, lowering a tong
arrangement
having a rotary part and a stationary part, relative to the basket to engage
respective
locking members of the tong arrangement and the basket, thereby fixing the
basket and
the tool relative to the stationary part of the tong arrangement, and rotating
the length of
tubular using the rotary part of the tong arrangement so as to couple the tool
to the length
of tubular.
The present invention also provides an apparatus for enabling a tool to be
secured to a
length of drill pipe, the apparatus comprising a basket arranged to securely
retain the tool,
and a tong arrangement having a rotary portion and a stationary portion, the
rotary
portion being arranged in use to grip and rotate the length of tubular,
wherein first locking
means are provided on the basket and second locking means are provided on the
stationary portion of the tong arrangement, the first and second locking means
being
engageable with one another to fix the basket relative to the stationary
portion of the tong
arrangement.
Preferably the first tong is a back-up tong and the second tong is a wrenching
tong. Both
tongs are preferably substantially cylindrical, and an axial passage is
preferably provided
therethrough for receiving tubulars. A passage is preferably provided from a
peripheral
edge to the axial passage of each tong to allow the introduction of tubulars
into the axial
passage. The pinion is preferably located at or near the periphery of the
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second tong. A motor may be provided on the second tong and coupled to the or
each
pinion.
The second tong is preferably provided with two pinions, although in another
embodiment it may be provided with only one. The pinions are preferably
located at
or near the periphery of the second tong spaced by substantially 180°
about the
longitudinal axis of the tong. In another embodiment they may be spaced by
substantially 120° about the longitudinal axis of the tong.
Preferably, the first tong comprises a plurality of hydraulically driven
clamping jaws
for gripping the first tubular and the second tong comprises a plurality of
hydraulically driven clamping jaws for gripping the second tubular. Each jaw
may be
equipped with two or more dies, and is preferably attached to hydraulic
driving means
via a spherical bearing, although the jaw may be an integral part of the
hydraulic
15' driving means.
Bearings supported on resilient means are preferably provided between the
first tong
and the second tong to facilitate relative axial movement of the first and
second tongs.
According to a second aspect of the present invention there is provided
apparatus for
applying torque to a first tubular relative to a second tubular, the apparatus
comprising
a gear and at least one pinion, and first clamping means for clamping the
first.tubular
within the gear, the pinion being attached to second clamping means for
clamping the
second tubular, and the pinion meshing with the gear in such a way that the
first
clamping means and the second clamping means can be rotated relative to one
another
by rotating the pinion.
The first clamping means preferably comprise jaws mounted within the gear
about an
axial ~ passage extending through the gear. The second clamping means
preferably
comprises jaws mounted within a clamping housing about an axial passage
extending
therethrough. A motor is preferably fixed to the clamping housing and coupled
to the
or each pinion.
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According to a third aspect of the present invention there is provided a
method of
applying torque to a first tubular relative to a second tubular, the method
comprising:
clamping the first tubular in a first tong; clamping the second tubular in a
second tong;
and rotating a pinion connected to the second tong and which meshes with teeth
provided around a peripheral surface of the first tong so as to rotate the
first tong
relative to the second tong.
According to a fourth aspect of the present invention there is provided a
method of
coupling a tool to a length of tubular, the method comprising the steps of
securing the tool in a basket;
lowering a tong arrangement having a rotary part and a stationary part,
relative
to the basket to engage respective locking members of the tong arrangement and
the
basket, thereby fixing the basket and the tool relative to the stationary part
of the tong
arrangement; and
rotating the length of tubular using the rotary part of the tong arrangement
so
as to couple the tool to the length of tubular.
This method may be used to couple a tool such as a drill bit, to a length of
drill pipe.
The coupling portion of the length ofdrill pipe may be brought into proximity
with a
corresponding coupling portion of the tool either before or after the lowering
of the
tong arrangement.
The length of drill string may be gripped by the rotary part of the tong
arrangement
either before or after the lowering of the tong arrangement. The length of
drill string
may be located proximate to the basket containing the tool either before or
after the
string is gripped by the rotary part of the tong arrangement.
By carrying out the steps of the above fourth aspect of the present invention
in reverse
(including rotating the length of tubing in the opposite direction), a tool
may be
decoupled from a length of tubular.
According to a fifth aspect of the present invention there is provided
apparatus for
enabling a tool to be secured to a length of drill pipe, the apparatus
comprising:
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a basket arranged to securely retain the tool;
a tong arrangement having a rotary portion and a stationary portion, the
rotary
portion being arranged in use to grip and rotate the length of tubular; and
first locking means provided on the basket and second locking means provided
on the stationary portion of the tong arrangement, the first and second
locking means
being engageable with one another to fix the basket relative to the stationary
portion
of the tong arrangement.
Preferably the first and second locking means are engageable and disengageble
by
means of linear movement of the tong arrangement relative to the basket.
Preferably, the basket is arranged to prevent rotation of the tool in the
basket, wherein
in use the rotary portion of the tong arrangement may be used to rotate the
length of
drill pipe to secure a screw connection between the length of drill pipe and
the tool.
Preferably, one of the first and second locking means comprises one or more
slots,
and the other of the first and second locking means comprises one or more
projecting
members, the slots and the members being engageable and disengageable by
relative
linear movement of the tong arrangement and the basket.
According to a sixth aspect of the present invention there is provided a tong
for use in
clamping a length of tubular during the making up or breaking out of a
connection,
the tong comprising:
a body portion having a central opening therein for receiving a length of
tubular; and
at least two clamping mechanisms mounted in said body, the clamping
mechanisms being radially spaced about said opening;
a plurality of elongate mounting members disposed between each of the
clamping mechanisms and the body of the tong, each mounting member having a
flat
face for abutting a side of a clamping mechanism and a rounded side for
locating in a
complimentary shaped recess in the tong body,
wherein each tong may be displaced to some extent from radial alignment with
the central opening of the tong.
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Some preferred embodiments of the invention will now be described by way of
example only and with reference to the accompanying drawings, in which:
Figure 1 is a view of an arrangement of a wrenching tong and a back-up tong;
Figure 2 is a side view of the wrenching tong and back-up tong of Figure 1;
Figure 3 is a view of the back-up tong of Figure 1;
Figure 4 is a cutaway view of the back-up tong of Figure 1;
Figure 5 is a cutaway view of the wrenching tong of Figure 1;
1 S Figure 6 is a view of the wrenching tong and back-up tong of Figure I
supported by a
C-frame and fixed in a frame for handling equipment on tracks at a rig floor;
Figure 7 is a view of the wrenching tong and back-up tong of Figure 1 in use,
with a
tubular clamped in the wrenching tong;
Figure 8 is a view of an arrangement of an alternative wrenching tong and back-
up
tong;
Figure 9 is a view of an arrangement of a further alternative wrenching tong
and back-
up tong;
Figure IO illustrates a modifed tong arrangement;
Figure 11 illustrates a modified back-up tong;
Figure 12 illustrates in detail a clamping arrangement of the tong of Figure
I1
including support elements;
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Figure 13 illustrates an arrangement for connecting a drill bit to a length of
drill pipe;
Figure 14 illustrates the arrangement of Figure 13 during the connection
operation;
and
Figure 15 illustrates the arrangement of Figure 13 following completion of the
connection operation.
Figures l and 2 show an arrangement of a composite wrenching tong and
back-up tong. A wrenching tong 1 is generally in the form of a disc with an
opening 2
through the centre thereof for receiving a stand of drill pipe (not shown),
and a recess
3 cut from the edge to the opening 2 at the centre. The wrenching tong 1 is
provided
with two pinion drives 4 arranged opposite each other at the periphery of the
disc,
equally spaced either side of the recess 3. Each pinion drive comprises a
drive motor
1 S S, drive shaft 6, and pinion 7 attached to the drive shaft 6.
A back-up tong 11 is located beneath the wrenching tong 1. The back-up tong
is generally in the form of a disc with similar dimensions to the wrenching
tong 1.
The back-up tong is also provided with an opening 12 through the centre and a
recess
13 from the edge to the opening at the centre. The opening 12 and recess 13
correspond to the opening 2 and recess 3 of the wrenching tong when the back-
up
tong 11 and the wrenching tong' 1 are correctly aligned.
A plurality of guide rollers 10 or other guide elements are spaced around the
edge of the wrenching tong 1 in order to maintain the alignment of the
wrenching tong
1 with the back-up tong 11.
A gear 14 is provided around the periphery of the back-up tong 11, broken by
the recess 13. The gear 14 meshes with the pinions 7 attached to the motors 5
on the
wrenching tong, so that when the drive motors S drive the drive shafts 6 and
gears 7,
the wrenching tong 1 rotates relative to the back-up tong 11. The angle of
rotation is
limited by the recess 13 of the back up tong.
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Figure 3 shows a back-up tong I I before the wrenching tong is placed on top
of it. The back-up tong 11 has a plurality of roller bearings 21, upon which
the
wrenching tong 1 is designed to be placed. The roller bearings 21 are
supported by
resilient means such as springs, elastic material or hydraulic/pneumatic
cylinders, in
order to support the wrenching tong during wrenching. During one wrenching
cycle,
the stands will move axially relative to one another as the connection is
tightened.
The wrenching tong must follow the axial movement of the top stand during one
wrenching cycle. This axial travel length depends on the pitch of the thread.
~ Three clamping jaws 8 equipped with dies 9 are located inside each of the
wrenching tong 1 and back-up tong 11. These are hydraulically driven for
clamping
the drill pipe stand in place in the centre of the wrenching tong. The
hydraulic power
supply may be provided by hoses (not shown).
Figure 4 shows the clamping mechanism of the back-up tong 11. Three
hydraulic pistons 16, comprising piston rods 17 and chambers 18, are located
inside
the casing of the back-up tong 11. Each piston rod 17 has an end 19 which is
secured
to the outside edge of the back-up tong 11. At the other end of the piston,
the jaw 8
containing two dies 9 with teeth (not shown) is fixed to the chamber 18 by a
spherical
bearing 20. With the arrangement shown, each drill pipe stand is clamped by
three
jaws and six dies at the joint. The spherical bearings 20 enable the jaws and
dies to
match the pipe surfaces closely, resulting in a low penetration depth of the
teeth of the
dies into the pipe surface, and thus prolonging the life of the drill pipe.
The wrenching
tong has a similar clamping jaw design, as shown in Figure 5.
Figure 6 shows the wrenching tong 1 and back-up tong 11 supported by a C-
frame 22 for handling at the rig. The C-frame 22 is in turn fixed in a frame
23 for
handling the equipment on tracks at the rig floor. A drill pipe spinner 24 is
mounted
on the C-frame above the tongs for rotating a drill pipe stand at high speed.
In order to make a connection between two stands of drill pipe, the recesses 3
and 13 in the wrenching 1 and back-up 11 tongs are aligned (the tongs may
already be
in this configuration following the removal of the tongs from a previous
section of
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tubing). Two stands of drill pipe 25,26 are then introduced into the openings
2,12 in
the wrenching and back-up tongs 1,1 I, respectively, through the recesses
3,13, and the
lower stand 26 is clamped in position in the back-up tong 11. The upper stand
25 is
introduced into the drill pipe spinner 24, and rotated at high speed in order
to pre-
y tighten the threaded connection. The final high torque will be applied by
the
wrenching tong 1.
The upper stand 25 is now clamped in position in the opening 2 through the
wrenching tong 1. The pinion drives 4 are then driven to, torque the
connection
between the stands 25,26 until the connection is fully tightened or until one
of the
pinion drives 4 is at the edge of the recess 13, at which stage the wrenching
tong 1 is
at one end of its possible arc of travel relative to the back-up tong 11. The
maximum
wrenching angle which can be reached in one cycle in the embodiment shown is
+/-
75°. If necessary, the upper stand 25 can then be released from the
wrenching tong I,
the tong returned to its original position, and the torquing process repeated.
To break a connection, the above operation is reversed.
An even larger wrenching angle can also be simply achieved with this
arrangement, as shown in Figure 7. The stands of drill pipe 25,26 are
introduced to
the tongs I,11 through the recesses 3,13 and pretightened using the drill pipe
spinner
24 as described above. However, before the top stand 25 is clamped in place in
the
opening 2, the wrenching tong drive is reversed, and the wrenching tong 1 is
driven to
its end position relative to the back-up tong, as shown in Figure 7. The top
stand 25 is
now clamped with the tongs in this position, so that with the embodiment shown
a
wrenching angle of 150° is achievable.
Figure 8 shows a similar arrangement of a composite wrenching tong and
back-up tong to that described above. However, in this case only one pinion
drive 4 is
used, which increases the possible wrenching angle to 300°.
Figure 9 shows another similar arrangement, with two pinion drives 4 being
used as in Figures 1 to 7. This time the pinion drives 4 are not opposite each
other,
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but spaced 120° each side of the recess 3. This gives the advantage of
the torque and
control provided by two drives, but allows a higher wrenching angle than the
arrangement of Figure 1. The maximum wrenching angle in this embodiment will
be
in the region of 210°.
The torque can be monitored by measuring the reaction torque at each drive by
means of a load cell, or by measuring the pressure of the drive motor.
It is to be understood that other variations are possible while still falling
within
IO the scope of the invention. For example, the preferred embodiments show an
arrangement whereby the pinion drives are mounted on the wrenching tong and
the
gear is mounted on the back-up tong. However, the arrangement could be the
other
way round with the pinion drives mounted to the back-up tong and the large
gear
mounted on the wrenching tong. Such an arrangement is illustrated in Figure
10.
Alternatively, the wrenching tong could be provided with a gear, and the
pinion drives mounted on the frame 24.
Hydraulic clamping cylinders are shown, but the tong could clamp the drill
pipe stands by any known means.
The preferred embodiments show one. or two pinion drives, but more could be
used if arranged in a suitable configuration.
Although the preferred embodiments have been described in relation to
tightening stands of drill pipe, it is to be understood that the arrangements
described
are suitable for applying torque to any tubular sections.
Figure 11 illustrates in partial section a modified back-up tong 40 which may
replace the back-up tong 1 I ofthe embodiment of Figure 1 to 9. The modified
tong
has only two jaws 41 associated with respective clamping arrangements 42. Each
arrangement 42 is held in place within the main body 43 of the tong 40 by a
set of
four "pendulum" bolts 44. .A clamping arrangement 42 associated with four
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pendulum bolts 44 is illustrated in more detail in Figure 12 from which it can
be seen
that each bolt comprises a cylinder cut in half along its longitudinal axis to
provide a
flat surface and a rounded surface. The flat surface of each bolt 44 abuts the
side of
the clamping arrangement 42, whilst the rounded side is located in a rounded
recess
45 provided in the side of the main body 43 opposed to the clamping
arrangement. It
will be appreciated that as the bolts 44 are able to rotate within their
respective
recesses in the tong body 43, each clamping arrangement 42 may pivot slightly
about
its centre. This allows the jaws 41 to conform to the outer surface of a
tubular to be
clamped when the tubular is for example not perfectly cylindrical.
Figure 13 .illustrates apparatus which can be used in association with a tong
arrangement 49 to connect and disconnect a tool such as a drill bit to and
from a
length of tubular such as a drill pipe. The apparatus comprises a basket 50
which is
arranged in use to be placed on the floor of a drilling rig. The basket 50 has
an
1 S opening in the top thereof for receiving a tool S I which is to be
connected to a length
of tubular 52. The opening has a shape which is complimentary to the shape of
the
tool S 1 such that the tool is held securely in an upright position and
rotation of the tool
within the basket 50 is prevented.
Two opposed sides of an upper plate of the basket SO are provided with slots
53. These slots 53 are shaped to receive locking members 54 which project
downwardly from the lower surface of the back-up tong 55 of the tong
arrangement.
The operation to connect a tool will now be described.
As shown in Figure 13, the tool 51 is first located in the basket 50. The
length
of tubular 52 is moved to a position over the tool (Figure 14) and is lowered
to bring
the box of the tubular into engagement with the externally threaded coupling
of the
tool 51. At this point, the tong arrangement is brought up to the tubular 52
with the
jaws of the rotary and back-up tongs being fully opened, and the tong is
placed around
the tubular 52. The tong arrangement is then lowered within its frame, to a
position in
which the locking members 54 are received by the respective receiving slots 53
of the
basket 50. In this position, the basket is locked to the back-up tong. The
jaws ofthe
rotary tong are then clamped against the tubular 52 and the rotary tong
rotated,
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relative to the back-up tong, to tighten the threaded joint (Figure 1 S). The
jaws of the
rotary tong are then released, and the tong arrangement withdrawn from around
the
tubular. The tubular and the connected tool can then be lifted clear of the
basket S0.
It will be appreciated that the tool 51 may be disconnected from the tubular
52
by carrying out the same operation but in reverse.
