U.S. patent application number 12/436960 was filed with the patent office on 2009-11-12 for pipe handling unit.
Invention is credited to Leon K. Jantzen.
Application Number | 20090279987 12/436960 |
Document ID | / |
Family ID | 41265546 |
Filed Date | 2009-11-12 |
United States Patent
Application |
20090279987 |
Kind Code |
A1 |
Jantzen; Leon K. |
November 12, 2009 |
PIPE HANDLING UNIT
Abstract
A pipe handling unit particularly adaptable for use in
association with slant wells includes a pipe manipulation mechanism
mounted to a mobile pipe storage rack, which when sited adjacent to
a drilling rig or service rig can transport pipe sections to or
from the rig mast regardless of the angular orientation of the rig
mast. The pipe manipulation mechanism includes a boom rotatably
mounted to the storage rack, with two or more swivel arms mounted
to the mast, with pipe grapple means connected to the outboard end
of the swivel arms may be swivelled outward, about axes parallel to
the boom, to a position in which the grapple means can grasp a pipe
section held in the rig mast. The swivel arms may then be swivelled
in the opposite rotation to rotate the pipe away from the mast. The
boom and swivel arms are then manipulated in coordinated fashion to
deposit the pipe section in the storage rack.
Inventors: |
Jantzen; Leon K.; (Calgary,
CA) |
Correspondence
Address: |
DONALD V. TOMKINS;C/O TOMKINS LAW OFFICE
740, 10150 - 100 STREET
EDMONTON
AB
T5J 0P6
CA
|
Family ID: |
41265546 |
Appl. No.: |
12/436960 |
Filed: |
May 7, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61051280 |
May 7, 2008 |
|
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|
Current U.S.
Class: |
414/22.53 |
Current CPC
Class: |
E21B 15/04 20130101;
E21B 19/155 20130101 |
Class at
Publication: |
414/22.53 |
International
Class: |
E21B 19/15 20060101
E21B019/15; E21B 19/00 20060101 E21B019/00 |
Claims
1. A pipe handling apparatus comprising: (a) a mobile pipe storage
rack having a longitudinal axis; (b) a boom having an upper end and
a lower end, said lower end being mounted to the pipe storage rack
such that the boom is rotatable, in a substantially vertical plane
parallel to the longitudinal axis of the storage rack, between a
lowered position and a raised position; (c) a first swivel arm
having an inner end and an outer end, said inner end of the first
swivel arm being mounted to the boom such that the first swivel arm
is swivellable relative to the boom about a first swivel axis
parallel to the boom; (d) a second swivel arm having an inner end
and an outer end, said inner end of the second swivel arm being
mounted to the outer end of the first swivel arm such that the
second swivel arm is swivellable relative to the first swivel arm
about a second swivel axis parallel to the boom; (e) an elongate
slide member mounted in association with the outer end of the
second swivel arm so as to be slidable relative to the second
swivel arm along an axis parallel to the boom; and (f) grapple
means associated with the slide member and adapted for gripping
engagement of a length of pipe.
2. The pipe handling apparatus of claim 1 wherein the boom
comprises a boom extension mounted to the boom so as to be
selectively movable in a direction parallel to the boom, and
wherein the first swivel arm is swivellably connected to the boom
extension.
3. The pipe handling apparatus of claim 1 wherein the boom
comprises a lower boom member rotatably mounted to the pipe storage
rack and a main boom member rotatably mounted to the lower boom
member.
4. The pipe handling apparatus of claim 3 wherein the boom further
comprises a boom extension mounted to the main boom so as to be
selectively movable in a direction parallel to the main boon, and
wherein the first swivel arm is swivellably connected to the boom
extension.
5. The pipe handling apparatus of claim 1 wherein the grapple means
comprises grapple extension means whereby the position of the
grapple means may be selectively adjusted in a radial direction
relative to the slide member.
6. The pipe handling apparatus of claim 5 wherein the grapple means
comprises two or more grapples, and wherein the grapple extension
means is adapted for selectively adjusting the radial position of
at least one of the grapples.
7. The pipe handling apparatus of claim 1, further comprising a
control system for controlling the operation of the pipe handling
apparatus.
8. The pipe handling apparatus of claim 7 wherein the control
system comprises programmable control means.
9. The pipe handling apparatus of claim 8 wherein the programmable
control means comprises a microprocessor.
10. The pipe handling apparatus of claim 8 wherein the programmable
control means comprises a programmable logic controller.
11. The pipe handling apparatus of claim 7 wherein the control
system is adapted for semi-automatic operation of the pipe handling
apparatus.
12. The pipe handling apparatus of claim 7 wherein the control
system is adapted for fully automatic operation of the pipe
handling apparatus.
13. The pipe handling apparatus of claim 8, further comprising one
or more sensors selected from the group consisting of linear
absolute position transducers, rotational absolute position
transducers, hydraulic fluid pressure transducers, and proximity
sensors.
14. The pipe handling apparatus of claim 13 wherein the control
system actuates the pipe handling apparatus in response to control
inputs received from the one or more sensors.
15. The pipe handling apparatus of claim 7 wherein the control
system is mounted in association with the mobile pipe storage
rack.
16. The pipe handling apparatus of claim 1 wherein the mobile
storage rack comprises a trailer.
17. The pipe handling apparatus of claim 1 wherein the mobile
storage rack comprises at least one adjustable stabilizer leg, for
adjusting the elevation of the mobile storage rack.
18. The pipe handling apparatus of claim 17, further comprising
stabilizer extension means, for adjusting the lateral position of
the mobile storage rack.
19. The pipe handling apparatus of claim 1 wherein the mobile
storage rack comprises at least one set of spaced vertical
dividers, with the space between adjacent dividers being selected
to receive a pipe section of selected diameter.
20. The pipe handling apparatus of claim 19, wherein the mobile
storage rack comprises first and second sets of vertical dividers
positioned toward the front end and rear end, respectively, of the
mobile storage rack.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit, pursuant to 35 U.S.C.
119(e), of U.S. Provisional Application No. 61/051,280, filed on
May 7, 2008, and said provisional application is incorporated
herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to apparatus for handling pipe
used in well drilling and servicing operations, particularly in
association with inclined or "slant" wells.
BACKGROUND OF THE INVENTION
[0003] Oil and gas wells are typically drilled by rotating a drill
bit mounted to the bottom of a "drill string" made up of sections
of pipe (also referred to as "joints" or "tubulars") joined
together by means of threaded connections at the ends of each pipe
section. After a well has been drilled, the drill string is removed
and typically a string of tubular casing sections is installed to
line the wellbore, and then a string of production tubing is
inserted into the well to carry oil and gas from a subsurface
formation up to ground surface. The term "tripping" is commonly
used to describe the procedure of adding a tubular to the drill
string or production string ("tripping in") or removing a tubular
from the string ("tripping out"). Well drilling and well servicing
involve both tripping in and tripping out, for various purposes
well known in the field. During tripping operations, tubulars
removed from a drill string or production string must be
transported to a pipe storage rack of some sort, and/or from the
storage rack to the wellbore for connection to the string already
in the wellbore.
[0004] There are many known types of apparatus well-suited for
carrying out these pipe-handling tasks in association with vertical
or near-vertical wells. However, pipe handling is more complicated
for tripping operations relating to slant wells, in which the drill
string or production string may enter the wellbore at up to 45
degrees or more from vertical.
[0005] U.S. Pat. No. 4,951,759 (Richardson) illustrates some of the
challenges associated with tripping pipe oil a slant well,
including safety issues associated with the handling of heavy
joints of pipe. In accordance with conventional methods, handling
tubulars usually requires a person to work on an elevated platform
in the mast of the drilling rig or service rig, and to connect a
winch line to each tubular as it is tripped out of the well so that
it can be moved to a vertical suspended position and then swung
away from the mast and into a storage rack. Richardson addresses
these requirements with a mast-mounted device that can grasp a
tubular while inclined parallel to the mast, and then rotate it
away from the mast and deposit in on a horizontal storage rack. The
mast-mounted pipe-handling device of Richardson must be either
installed on a purpose-built rig where the device is accommodated
into the design, or retrofitted to an existing rig, which would
entail extensive and expensive modifications.
[0006] Accordingly, there remains a need for improved pipe handling
apparatus, particularly for use in drilling and servicing slant
wells. More particularly, there is a need for such improved
apparatus that is readily usable with conventional drilling rigs
and service rigs, without need for significant or any modification
to the rigs. The present invention is directed to these needs.
SUMMARY OF THE INVENTION
[0007] In general terms, the apparatus of the present invention is
a pipe handling unit comprising a pipe manipulation mechanism
mounted to a mobile pipe storage rack, which can be parked adjacent
to a drilling rig or service rig and which can pick up tubulars
from the rig mast and position them in selected positions in a
horizontal storage rack. The pipe manipulation mechanism provides
for variable and selective pipe travel paths between the rig mast
and the storage rack, such that precise positioning relative to the
rig is not critical, thus providing greater flexibility in
field-positioning of the pipe handling unit to avoid interference
with wellhead equipment, flow lines, shacks, and other wellsite
appurtenances. The pipe handling unit does not require an elevated
work platform, and thus eliminates safety risks associated with
such platforms.
[0008] The pipe manipulation mechanism incorporates grapple means
for grasping a section of pipe, with actuation means whereby the
mechanism can transport a section of pipe from a vertical or
inclined rig mast to the pipe storage rack (i.e., tripping out), or
from the storage rack to the rig (i.e., tripping in). The mobile
storage rack preferably will accommodate storage of pipe sections
in a horizontal or near-horizontal position, with vertical "finger
racks" to facilitate pipe placement in desired locations within the
rack. Racking the pipes horizontally rather than vertically
eliminates the need to guy the rig mast in many situations, thus
leading to much faster rig-up and rig-down times. However,
horizontal pipe storage is not essential to the invention; the
apparatus could also be adapted for use with non-horizontal pipe
storage racks.
[0009] The mobile storage rack preferably has adjustable
downriggers or stabilizing legs which may be extended to bear on
the ground surface and carry up to the full weight of the unit as
necessary to level and stabilize the storage rack and thus
facilitate accurate positioning of pipe within the rack.
Downriggers may be of any suitable type, such as those commonly
used in association with mobile cranes. Although the present
invention does not require the use of downriggers of any particular
type (or at all), preferred embodiments comprise a downrigger
stabilizer system incorporating means for laterally shifting or
slewing the pipe manipulation mechanism relative to the rig mast
and wellhead after the unit has been parked, thus minimizing or
eliminating the need for comparatively precise positioning of the
pipe handling unit relative to the rig.
[0010] The pipe handling unit preferably includes a self-contained
hydraulic power unit to actuate the pipe manipulation mechanism so
as to manipulate pipe joints with optimal speed and efficiency to
achieve pipe-handling cycle times that are at least as fast as
those achieved using conventional methods and equipment. In
alternative embodiments, however, power for actuating the pipe
manipulation mechanism may be provided from a suitable auxiliary
power unit, which may be but is not limited to a hydraulic power
unit.
[0011] The pipe handling unit of the present invention is readily
adaptable to automated control and operation, using known
technologies such as but not limited to microprocessors and
programmable logic controllers (PLCs), which are well known in the
art. Automated operation is particularly advantageous for
embodiments having vertical finger racks, as a computerized control
system can readily determine and store in memory the positions of
individual pipes within the storage rack and actuate the pipe
manipulation mechanism to retrieve pipes from the storage rack in
an automatic mode, thereby facilitating pipe handling without the
pipes needing to be manually handled or manipulated.
[0012] Control of the pipe handling unit may be from a simple
control panel that could be remotely mounted near the rig
operator's control panel. The control system may include a set-up
mode and an operational mode, with control of the unit being
handled primarily by a PLC or other suitable programmable device to
enable semi- or fully-automated tripping operations, depending on
the desired level of operational integration with the rig.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Embodiments of the invention will now be described with
reference to the accompanying figures; in which numerical
references denote like parts, and in which:
[0014] FIG. 1 is an isometric view of a pipe handling unit in
accordance with the present invention, shown parked alongside a
conventional service rig.
[0015] FIG. 2 is a rear view of a pipe handling unit positioned
beside a service rig as shown in FIG. 1.
[0016] FIG. 3A is a side view illustrating the pipe handling unit
of FIGS. 1 and 2, shown alongside a service rig with its mast in
the vertical position.
[0017] FIG. 3B is a side view illustrating the pipe handling unit
of FIGS. 1 and 2, shown alongside a service rig with its mast in an
inclined position.
[0018] FIG. 4 is a partial plan of the pipe handling unit as in
FIG. 3A, showing various possible positions of the unit's pipe
manipulation mechanism as it transports a pipe section to or from
the service rig mast.
[0019] FIG. 5A is a side view of the pipe handling unit, showing
various possible positions of the pipe manipulation mechanism as it
moves a pipe section to or from the unit's pipe storage rack.
[0020] FIG. 5B is a side view illustrating mechanisms for actuating
the pipe manipulation mechanism in accordance with one embodiment
of the invention.
[0021] FIG. 6 is a partial rear view of the pipe handling unit
showing representative positions of the pipe manipulation mechanism
as it places or retrieves a pipe section in or from the pipe
storage rack.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] In preferred embodiments as illustrated in the Figures, the
pipe handling unit 100 of the present invention comprises a pipe
manipulation mechanism (generally indicated by reference numeral
50) mounted to a mobile pipe storage rack which may be positioned
as required adjacent to a drilling rig or service rig 1 having a
mast 2. Rig 1 does not form part of the broadest embodiments of the
present invention. In the illustrated embodiments, the mobile
storage rack is provided in the form of a trailer 10, adapted to be
transported and maneuvered as required by a suitable tractor unit
(not shown). In alternative embodiments, mobile pipe storage rack
may be a self-propelled unit with its own motor and drive train.
Trailer 10 is preferably provided with front downrigger stabilizer
legs 11 and rear downrigger stabilizer legs 12 which may be
deployed to lift trailer 10 off of its tires 13, whereupon
stabilizer extension slides (not shown) may be used to position
trailer 10 as appropriate adjacent to service rig 1 and then
trailer 10 is levelled.
[0023] Trailer 10 has a flat deck 10A which serves as a pipe
storage area or storage rack 60. In preferred embodiments, one or
more sets of vertical dividers or "finger racks" 14 extend upward
from deck 10A, preferably with one set of finger racks 14F near the
front end of trailer 10 and a second set of finger racks 14R near
the rear end of trailer 10 as shown in FIG. 1, to facilitate
orderly storage of pipe sections 15 as they are tripped out of the
well and stored pending their return to the well ("tripping in") in
accordance with typical well-servicing operations. The space
between adjacent finger racks will be sized to receive a single
pipe section, and finger racks 14 preferably will be adjustable to
accommodate different pipe diameters. Preferably, the space between
adjacent finger racks will be in the range of 1.5 to 1.8 times the
pipe diameter, or less. To minimize weight trailer 10 will
typically be designed only to carry racked pipe sections 15 while
trailer 10 is supported in a stationary position on stabilizer legs
11 and 12. However, alternative embodiments may be designed for
highway transport of racked pipe sections 15.
[0024] FIG. 1 shows pipe handling unit 100 positioned adjacent to a
service rig 1 which has been configured to service a slant well
having a wellhead 3 protruding from the ground (conceptually
indicated by reference character G). In a typical application,
service rig 1 uses a travelling block 5, which is longitudinally
movable along mast 2, to lift a string of jointed pipe 4 (e.g., a
production string) out of the well using an elevator (not shown) of
well-known type. When the elevator and travelling block 5 are not
supporting the weight of pipe string 4, the weight is carried by
slips 7 associated with wellhead 3 (in accordance with well-known
technologies). In FIG. 1, a pipe section 15 has been disconnected
from pipe string 4, and is being grasped by grapple means 30
associated with pipe manipulation mechanism 50, with pipe string 4
being supported by slips 7.
[0025] In preferred embodiments, pipe handling unit 100
incorporates an engine-driven hydraulic power unit (conceptually
indicated by reference numeral 32) mounted to trailer 10, to
provide pressurized hydraulic fluid for actuation of pipe
manipulation mechanism 50. Preferred embodiments also incorporate a
control system for pipe manipulation mechanism 50, also mounted on
trailer 10 as conceptually indicated by reference numeral 33.
However, alternative power means and control systems, including
non-trailer-mounted and remotely-operated alternatives, may be used
without departing from the concept and scope of the present
invention.
[0026] FIG. 2 illustrates service pipe handling unit 100 positioned
adjacent to rig 1 as in FIG. 1, but viewed from the rear. In the
embodiment shown in FIG. 2, pipe manipulation mechanism 50
comprises a main boom 19 which is rotatably mounted to trailer 10
as described in greater detail below. Main boom 19 will typically
be mounted to the rear end of trailer 10, and preferably offset
from the trailer's longitudinal centerline as shown in FIG. 2, for
optimal accessibility to an adjacent rig 1. A boom extension 21 is
slidably or telescopically mounted to main boom 19 for increased
access to upper regions of mast 2 of rig 1.
[0027] As best appreciated with reference to FIGS. 2, 5, and 6,
pipe manipulation mechanism 50 further includes an inner swivel arm
23 having an inner end 23A and an outer end 23B, with inner arm 23
being mounted along its inner end 23A to boom extension 21 so as to
be swivellable about a first swivel axis X-1 parallel to main boom
19. An inner arm actuator 24 is provided for swivelling inner arm
23 about first swivel axis X-1 as necessary. Pipe manipulation
mechanism 50 further comprises an outer swivel arm 25 having an
inner-end 25B and an outer end 25C, with outer swivel arm 25 being
mounted along its inner end 25B to outer end 23B of inner swivel
arm 23 so as to be swivellable about a second swivel axis X-2
parallel to first swivel axis X-1 (and, therefore, parallel to main
boom 19). An outer swivel arm actuator 26 is provided for
swivelling outer swivel arm 25 about second swivel axis X-2 as
necessary.
[0028] As indicated in the Figures, inner swivel arm 23 and outer
swivel arm 25 may be of substantial width in the direction parallel
to axes X-1 and X-2, and in preferred embodiments may be provided
in the form of trussed frames as shown. However, this is only one
of many possible configurations for inner swivel arm 23 and outer
swivel arm 25, and the present invention is not limited to any
particular form or structure for these components.
[0029] As perhaps best seen in FIGS. 3A, 3B, and 5A, an elongate
axial slide member 28 is mounted to outer swivel arm 25 along outer
end 25C thereof, so as to be selectively movable along and relative
to outer swivel arm 25 in a direction parallel to second swivel
axis X-2 (and, therefore, parallel to main boom 19), to facilitate
even greater access to upper regions of mast 2 of rig 1. This
functionality can be appreciated from FIGS. 3A and 3B, in which
slide member 28 is in it lowermost axial position relative to outer
swivel arm 25, and from FIG. 5A in which slide member 28 is in its
uppermost axial position relative to outer swivel arm 25. Provided
near each end of slide member 28 are grapples of any type suitable
for grasping a section of pipe, whether from mast 2 or from pipe
storage rack 60. An additional function of slide member 28 is to
position grapples 30 so that they do not interfere with finger
racks 14 when pipe manipulation mechanism 50 is depositing a pipe
section 15 into storage rack 60.
[0030] As shown in FIG. 5A, main boom 19 is rotatably mounted to
trailer 10 such that it can be rotated from a lowered position in
which it is substantially parallel to deck 10A of trailer 10, to a
fully-raised position (which typically but not necessarily will be
the vertical position shown in FIG. 3A), with the ability to stop
at any intermediate position between these extremes so as to be
substantially parallel to mast 2 of a drilling rig or service rig
with which pipe handling unit 100 is being used. In the preferred
but non-limiting embodiment shown in FIG. 5B, this functionality is
enabled by a providing a lower boom member 19 the lower end 19L of
which is mounted to trailer 10 so as to be rotatable about a first
horizontal axis X-3 transverse to the longitudinal axis of trailer
10, and mounting the lower end 17L of main boom 17 to the upper end
19U of lower boom member 19 so as to be rotatable about a second
horizontal axis X-4 parallel to first horizontal axis X-3. The
rotational position of lower boom member 19 relative to trailer 10
is controlled by a lower boom actuator 18 (shown in FIG. 5B in the
exemplary form of a hydraulic cylinder), and the rotational
position of main boom 17 is controlled by an upper boom actuator 20
(shown in FIG. 5B in the exemplary form of a hydraulic cylinder
with an associated mechanical linkage 22). Persons skilled in the
art of the invention will appreciate that various other mechanisms
may be devised to effect the desired functionality of main boom 17,
with or without a lower boom member 19, and using hydraulic
cylinders or other known types of actuators, without departing from
the scope of the present invention.
[0031] Field operation of a pipe handling unit 100 in accordance
with the present invention may be readily understood having regard
to the Figures and the foregoing description. With trailer 10
positioned substantially parallel to a drilling rig or service rig
1 (as the case may be), with mast 2 of rig 1 being angularly
oriented as required (i.e., vertical or inclined), main boom 17 is
rotated upward until it is substantially parallel to tie axis of
mast 2. Inner and outer swivel arm actuators 24 and 26 may then be
operated as required to rotate slide member 28 to a position
allowing grapples 30 to engage and grasp a pipe section 15 disposed
within mast 2 (after removal from a drill string or production
string), in conjunction with any appropriate adjustment of the
axial position of slide member 28 relative to outer swivel arm 25.
This process can then be reversed to rotate pipe section 15 out of
mast 2 (as may be particularly well understood with reference to
FIGS. 4 and 5A), for deposition into storage rack 60 as shown in
FIG. 6 (again, adjusting the axial position of slide member 28 as
appropriate for optimal positioning of pipe section 15 in storage
rack 60).
[0032] It will be appreciated from FIG. 4 in particular that boom
extension 21 can start moving downward along main boom 17 as soon
as pipe section 15 has begun rotating out of and away from mast 2.
This feature reduces pipe-handling cycle time compared to prior art
pipe-handling equipment which due to structural constraints
requires the pipe to be rotated fully out of the mast before
rotation to a lower position can begin.
[0033] The foregoing describes the tripping-out procedure; for
tripping-in operations, the process is simply reversed. During
tripping-in operations, slide member 28 may be actuated to
facilitate "stabbing" each added pipe section 15 into the upper end
of pipe string 4 for thread makeup, thus minimizing or eliminating
the need to use the rig's travelling block and elevator, and
reducing the tripping-in cycle time as a result.
[0034] FIG. 6 further illustrates how pipe sections 15 may be
deposited on storage rack 60, guided by finger racks 14 which
facilitate orderly arrangement of pipe sections 15 and optimal pipe
storage capacity. Grapples 30 are preferably adapted to release and
pick up pipe sections from storage rack 60 one at a time without
colliding with other pipe sections already in the rack. In order to
do this most efficiently, pipe sections 15 can be laid down in and
retrieved from horizontal layers, laying the pipe sections down
from right to left (as viewed in FIG. 6) and picking them up from
left to right. In order to move pipe sections 15 in and out of the
fingers of finger rack 14, pipe manipulation mechanism 50 must lift
and lower the pipe sections 15 in a vertical movement. However,
this movement can be readily achieved by coordinated operation of
inner swivel arm actuator 24 and outer swivel arm actuator 26,
preferably in association with a programmed control mechanism, to
manipulate inner swivel arm 23 and outer swivel arm 25 so as to
produce the required vertical movement of slide member 28 and, in
turn, a pipe section 15 held in grapples 30.
[0035] In preferred embodiments, the various actuators required to
operate pipe manipulation mechanism 50 are hydraulically actuated
and hydraulically controlled by use of suitable valves, which are
in turn controlled by one or more PLCs or other programmable
controllers or computers, based on control algorithms using control
inputs from one or more sensors (not shown) of known types and
applicability. Such sensors may include, but are not limited to,
linear and rotational absolute position transducers, hydraulic
fluid pressure transducers, proximity sensors, and other
position-sensing technologies.
[0036] Preferred embodiments of pipe manipulation mechanism 50 may
further comprise grapple extension means (not shown) for
facilitating alignment of grapples 30 with a pipe section 15
disposed within the mast of a drilling rig or service rig. Such
grapple extension means would be adapted to selectively extend one
or both grapples (in concert, independently, or differentially) in
a radial direction relative to slide member 28, so as to bring
grapples 30 into optimal alignment with pipe section 15, even
though the axis of slide member 28 might not be precisely parallel
to the axis of the well (and pipe section 15). Accordingly, the
apparatus can be adapted such that if grapples 30 are not optimally
aligned with pipe section 15, the first grapple 30 to contact pipe
sections 15 will not push it out of position, or if the pipe is
constrained, it will not pull on outer swivel arm 25. Preferably,
the control system of the apparatus will be programmed such that
the first grapple contacting the pipe will sense, the contact and
stop, allowing (and triggering) the other grapple to move into
contact with pipe. Once both grapples 30 are in contact with the
pipe, the gripping pressure applied by both grapples may be
increased to an appropriate level before lifting the pipe. Persons
of ordinary skill in the art will readily appreciate that the
above-described functionality of the grapple extension means can be
provided in a variety of ways using well-known technologies, such
as (but not limited to) limit switches, linear potentiometer
detection of position coupled with pressure or force
transducer-generated inputs to PLC, or microprocessor-based
automated control systems.
[0037] While preferred embodiments have been shown and described
herein, modifications thereof can be made by one skilled in the art
without departing from the scope and teaching of the present
invention, including modifications which may use equivalent
structures or materials hereafter conceived or developed.
[0038] The described and illustrated embodiments are exemplary only
and are not limiting. For example, the illustrated embodiment of
pipe manipulation mechanism 50 features two swivel arms (inner
swivel arm 23 and outer swivel arm 25) with associated actuators 24
and 26. However, it will be readily appreciated by persons skilled
in the art that alternative embodiments may include three or more
swivel arms and corresponding actuators without departing from the
concept and scope of the present invention.
[0039] It is to be especially understood that the substitution of a
variant of a claimed element or feature, without any substantial
resultant change in the working of the invention, will not
constitute a departure from the scope of the invention. It is to
also be fully appreciated that the different teachings of the
embodiments described and discussed herein may be employed
separately or in any suitable combination to produce desired
results.
[0040] In this patent document, any form of the word "comprise" is
to be understood in its non-limiting sense to mean that any item
following such word is included, but items not specifically
mentioned are not excluded. A reference to an element by the
indefinite article "a" does not exclude the possibility that more
than one of the element is present, unless the context clearly
requires that there be one and only one such element. Any use of
any form of the terms "connect", "engage", "couple", "attach", or
any other term describing an interaction between elements is not
meant to limit the interaction to direct interaction between the
subject elements, and may also include indirect interaction between
the elements such as through secondary or intermediary structure.
Relational terms such as "parallel", "perpendicular", "coincident",
"intersecting", and "equidistant" are not intended to denote or
require absolute mathematical or geometrical precision.
Accordingly, such terms are to be understood as denoting or
requiring substantial precision (e.g., "substantially parallel")
unless the context clearly requires otherwise.
* * * * *