Note: Descriptions are shown in the official language in which they were submitted.
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Elevators
This is a divisional application of Canadian Patent
Application Serial No. 2,331,575 filed on May 12, 1999.
This invention relates to elevators and is concerned
particularly, but not exclusively, with elevators for
facilitating the connection or disconnection of a tubular
to or from a string of tubulars.
During the drilling of oil and gas wells it is
necessary to connect and disconnect tubulars for use
therein. Recently, there has been the need to use casing
of a very large diameter for lining the well. In
particular, modern casing may be forty-eight inches in
diameter.
The weight of a single joint of modern casing causes
many problems. In particular, casing is usually threaded.
When a joint of casing is connected and disconnected from
the string of casing, there is a high probability that the
threads will become damaged by collisions therebetween.
It has been proposed to use a device called a "single
joint compensating elevator" as disclosed in EP-A-O 171
144. The device enables the weight of a single joint to
be compensated for, such that when the joint is lowered or
raised to or from a string, the effective weight of the
joint is zero. A pneumatic bellows or the like allows
small adjustments to be made to allow the joint of casing
to be made up to the string of casing. The device also
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allows over compensation to be made, such that upon
disconnection of a joint from the string of casing, the
joint springs from the string of casing. The device
depends from the primary elevator of the rig, with a
single joint elevator depending therefrom.
The above described arrangement requires the device
to be attached to the elevator prior to each connection or
disconnection and removed therefrom prior to lowering or
raising the string, which is carried out by the primary
elevator. This procedure wastes valuable rig time.
US 3588162 describes a rotating flapper elevator
incorporating flappers that may be rotated into a
horizontal position to engage beneath a collar at the end
of a tubular to support the tubular during connection or
disconnection to or from a string of tubulars. However,
such an arrangement may be unsuitable for supporting very
high loads.
EP 0147511A discloses a fixed support device for a
drill pipe incorporating bearing surfaces that are
displaceable against hydraulic pressure such that the
surfaces have an equal share of the load.
In accordance with a first aspect of the present
invention there is provided an elevator provided with a
bearing to facilitate rotation between said elevator and
an item to be held in said elevator, characterised in that
said bearing is located on a compressible member
compressible in response to weight of the item.
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The invention also provides a device for facilitating
the connection or disconnection of a tubular to or from a
string of tubulars, said device incorporating such an
elevator. The device may also incorporate a rim for
attachment to a tubular, said rim being suitable for
resting on the bearing of said elevator. Preferably, the
rim forms part of a cap.
For a better understanding of the present invention,
reference will now be made, by way of example, to the
accompanying drawings, in which:
Figure la is a side view of a first embodiment of a
wellbore tubular connection system, in use in a first
stage of operation;
Figure lb is a front view of the system of Figure la;
.15 Figure lc is a front view of the system of Figure la
in a second stage of operation;
Figure ld is an enlarged view of the system of Figure
la in said first stage of operation;
Figure le is an enlarged view of the system of Figure
la in said second stage of operation;
Figure 2a is a side view of a second embodiment of a
wellbore tubular connection system, in use in a first
stage of operation;
Figure 2b is an enlarged view of part of the system
of Figure 2a;
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Figure 3a is a view of the system of Figure 2a in a
second stage of operation;
Figure 3b is an enlarged view of part of the system
of Figure 3a;
Figure 4a is a front view of a third embodiment of a
wellbore tubular connection, in use in a first stage of
operation;
Figure 4b is a front view of the system of Figure 4a,
in use in a second stage of operation;
Figure 4c is a side view of the system of Figure 4a
in use;
Figure 5 is a front view of a fourth embodiment of a
wellbore tubular connection system in use;
Figure 6 is a front view of a fifth embodiment of a
wellbore tubular connection system in use;
Figure 7a is a view in perspective of a part of the
system of Figure 3a in accordance with the invention;
Figure 7b is a view in perspective of the part of the
system of Figure 7a;
Figure 7c is an alternative to the part of the system
of Figure 7a;
Figure 8 is an alternative arrangement of part of the
system of Figure 7a;
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Figure 9a is a view of a wellbore tubular connection
system situated above a tubular;
Figure 9b is a view of the system of Figure 9a
located on said tubular; and
5 Figure 9c is a perspective view of the system of
Figure 9a.
Referring to Figures la - le, there is shown a
wellbore tubular connection system for connection of a
tubular to a string of tubulars, generally identified by
reference numeral 1.
System 1 comprises main bails 2 suspended from the
eyes 4 of a rig's travelling block 6. Lower ends 8 of the
main bails 2 extend through eyes 9 of an upper elevator
10. Cables 11 support the travelling block 6 in a rig
(not shown).
Slings 12, made of, for example, steel or synthetic
cables, are connected at their top ends to a lower end of
the travelling block 6 and at their bottom ends to a lift
eye 14 of a joint compensator 20 (which may be any known
joint compensator, air cylinder compensator, hydraulic
cylinder compensator, or air spring compensator, including
any device for joint compensation disclosed herein).
An optional swivel 18 has its top end connected to a
lower eye 22 of the joint compensator 20 and its bottom
end connected to a shackle 16 which itself is connected
to a top end of a sub 24. The sub 24 is threadedly
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connected to a standard, commercially available lift
assembly 30 which has a lower hook end 26 to which are
releasably connected links 28. A lower elevator 40 is
connected to the lower ends of the links 28.
Both the elevators 10 and 40 may be any suitable
known elevator and any elevator disclosed herein_ As
shown each elevator 10 and 40 is a hinged-door type
elevator which is openable to receive a tubular and
closable and latchable for holding a tubular. - Slip-type
elevators may be used. A starnd 36 of two tubular joints
32 and 34 is held by the elevator 40 and supported by the
system 1. Although two tubular joints are shown, it is
to be understood that the system 1 can support one or a
plurality of two, three, four or more joints, including
an entire tubular string extending down into a wellbore.
Figures lb and ld show the system 1 at a first stage
of operation. The stand 36 of two tubular joints is being
lifted by the system 1, and the weight of the stand 36 is
being compensated for.
Figures Ic and le show the single joint compensator
20 in an extended position. The sub 24 abuts the top of
the elevator 40. The system can now hold the weight of
the entire string of tubulars to which the stand 36-may
be attached or detached.
Initially, the elevator 40 is latched onto a new
stand of tubulars. With the travelling block 6, the
stand is lifted to a vertical position. At this point, a
shoulder 38 of a shaft 42 of the assembly 30 is bottomed
out on a corresponding shoulder 44 of a bowl 46 of the
elevator 10. The compensator 20 is then activated to
compensate for the weight of the stand, raising the shaft
42 so that the elevator 10 no longer supports the stand,
as shown in Figure 19D.
While the stand's weight is compensated for by the
compensator 20, the stand is easily manipulable and its
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lower end is positioned above and then lowered into a top
joint of a tubular string being supported by the rig's
slips on the rig- floor (not shown). As the stand is made
up into the string, the compensator 20 permits the
compensated lowering of the stand. When the joint is
made up, the rig-slips are released; the travelling block
system raises the system 1; the shoulder 38 bottoms out
on the bowl's shoulder 44; and then the rig's system
= supports and lowers the entire string. Again the rig
slips are set; the elevator 40 is released; and the
process of adding an additional stand begins again. A
reverse process is used for break-out operations, with
the joint compensator 20 activated prior to or following
initial lifting'up on the string and setting of the rig's
slips. As a joint is unscrewed and rising, the joint
compensator 20 compensates for the weight of the joint.
Figures 2aand 2b show a system 50 according to the
present invention with some parts that are like those of
:the system 1 and which bear the same identifying
=numerals. Slings 52 through the eyes 4 connect the tops
of joint compensators 51 to the eyes 4. Clamps 53
releasably clamp the lower ends of the joint compensators
51 to the bails=2. Shackles 54 provide for pivoting of
the joint compensators 51.
As shown in Figure 2b, an upper part 55 of the
tubular 32 is resting on rollers (one shown) 57 rotatably
mounted to the elevator 40's body. The rollers 57 are
like the rol'lers in Figure 7a. As shown in Figure 3b,
the rollers 57 have been moved down, compressing
compression members (not shown, see Figures 5a, 5b). As
shown in Figure 3a, the joint compensators 51 are
compensating for the weight of the tubulars 32, 34; and
the top shackles of the bails 2 are riding up in the eyes
4. The eyes 4 are not at this point bearing the weight
through the entire length of the bails 2 of the system 50
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and the tubulars 32, 34. As shown in Figure 3b, the
elevator 40, bails 2 and eyes 4 are bearing this weight
and the joint compensators 51 are not compensating for
the weight of the tubulars. Typical control lines and
control apparatus (not shown) are used with the
compensators 51.
Figures 4a to 6 show a system 100 according to the
present invention with the travelling block 6 with the
cables 11 supporting the system 100 in a rig derrick (not
shown). The bails 2 support the elevator 10 which holds
the tubulars 32, 34 (all as in Figure la previously
described). Slings 12 support joint compensator 20 below
the travelling block 6 and slings 53 connect the joint
compensator 20 to the elevator 10 so that the joint
compensator (as shown in Figure 4a) compensates for the
weight of tubulars held by the elevator 10. Figure 4b
shows the eyes 4, bails 2 and elevator 10 supporting the
tubulars 32, 34 (and whatever may be connected thereto)
The joint compensator 20 may be any compensator disclosed
'herein (as may be the compensator 70, Figure 4d).
Typical control lines and control apparatus are used with
the joint compensator 20 (and the compensators 20, 70) or
such lines and apparatus as disclosed herein (as is.the
case for any compensator in Figures la, 2a, 3a, and 5).
Figure 5 shows a top drive system 150 according to
the present invention suspended below a travelling block -
72 with eyes 62 to which are connected a swivel 63, a
power train 64 and a top drive 65. A guide dolly 66
holds and guides the top drive 65. Lift eyes 67
connected to the top drive support bails 68 which support
a lower elevator 69 (like the elevator 20). A joint
compensator 70 is connected to a lower end of a lift sub
72 which is connected to the top drive 65 and slings 71
interconnect the lower elevator 69 and the joint
compensator 70.
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Figure 6 shows an embodiment of the system 150
compensating for the weight of a tubular 32 (or a tubular
string including the tubular 32). The embodi.ment of
Figure 6 has an elevator 74 instead of the lift eyes 67
of Figure 5. There is also provided a circulating head 73
for use with circulating fluids in the tubulars to be
connected and disconnected to or from a string of
tubulars.
Figures 7a and 7b show a roller bearing assembly 200"
with segments 171, 172, and-173 which areinsertable into
an elevator to facilitate rotation of 'a tubular with
respect to the elevator. A plurality of rollers 180 are
rotatably mounted to the segments 171, 172, and 173.
Arms 179 extends inwardly on each side of each roller
180. A base member 174 disposed beneath the roller
bearing assembly 200 has three segments 175, 176, and 177
each with two or three upwardly projecting supports 178.
In operation a tubular disposed in the bearing assembly
200 is initially.supported by the rollers 180. As the
tubular is lowered or elevator is raised weight applied
to the rollers increases, pushing the segments 171 to 173
down, and thereby arms 179 compress compressible members
199 adjacent each support 178. Eventually the supports
178 (see Figure 7b). project up beyond the top of the
rollers 80 and bear the weight of the tubular and other
tubulars, if any, attached to it. The compressible
members 199 may be made of any suitable compressible
and/or cushion material, including, but not limited to
elastic materials, rubber, elastomeric materials, and/or
a spring or springs of suitable spring force, and/or
vented gas filled bladders (in one aspect which are
selectively refillable) and/or any combination thereof.
Alternatively, no compressible members are used in the
system of Figure 7a (or of Figure 9).
Instead of three segments the bearing assembly
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and/or base may be made of two, four or more segments.
As shown in Ficgure 7c, an assembly 300 according to the
present invention has a bearing assembly 301 and a base
302 which are not segmented.
Bearing assemblies as in Figures 7a and 7c may be
used in any suitable tubular handling apparatus or
cievice, including, but not limited to, pipe handlers,
pipe positioners, elevators, spiders, and tongs.
Figure 8 illustrates a particular embodiment of a
bearing system 400 with a plurality of rollers 402 (one
shown) useful in assemblies as in Figures 7a and Figure
7c. Each roller 402 is rotatably n-ounted to a support
404 which is disposed above a compressible member (or
material) 406. The support 404 is releasably disposed in
a slot 408 in an elevator body 410. Each support 404 may'
be held_ in place with one or more set screws and/or
bolts. Such a system may be used in any item listed
(pipe handlers, etc.) in the preceding paragraph.
Figures 9a and 9b illustrate a lift cap 530 for use=
with various wellbore tubulars for providing a support
surface 532 which can rest on a bearing assembly (as, for
example in Figures 7a and 7c). The lift cap 530 has a
generally cylindrical body 534 with an end 535 which may.
be threadedly engageable on a threaded end 540 of a
tubular 542 (Figure 24B). The wall 544 of the tubular
-542 is received in a recess 536 around the cap's body534. Lift/rotation holes
538 (one of two shown in Figure
9a) facilitate lifting and rotation of the cap 530. Set
screws 533 through holes 537 secure the cap 530 to the
tubular 540 to prevent unwanted unscrewing of the two.
Figure 9c shows a central channel 539 through the lift
cap 530.
It is envisaged that the invention is suitable for
use with pipe, drill pipe, work strings and casing.
