APPARATUS AND METHOD FOR HANDLING WELLBORE TUBULARS
A handling apparatus and method for manipulation of tubulars include an elongate base such as a trailer supporting one or more layers of tubulars in a stack. A trough extends along the base for receiving and supporting a tubular and can be actuated to adjust its elevation such as to unstack or stack tubulars on the base, adjust its inclination to assist with longitudinal manipulation of the tubulars on and off of the trough. The trough can be oriented between an upright tubular supporting position and tipped transfer position for transfer of tubulars to and from an uppermost layer of the stack. More preferably, a pivoting grabber at the discharge end of the trough is used to engage and manipulate tubulars on and off of the trough.
The invention relates to an apparatus and method for handling tubulars and in particular to an apparatus and method for transferring wellbore tubulars between a stack of wellbore tubulars on the apparatus and the work floor of an oil or gas well service rig.
BACKGROUND OF THE INVENTIONIn the servicing of gas and oil wells, sectional wellbore tubulars such as drill pipe, collars and the like must be transferred to and from a well service rig. At the service rig, the tubulars are installed in or removed from the well, as necessary. Such tubulars are very heavy and service rig procedures require the tubulars to be raised or lowered approximately ten to twenty feet, thus requiring the use of mechanical aids for personnel to handle the tubulars for use and for stacking the tubulars for storage and transport. Some prior art tubular handling apparatus use slings and winches to raise and lower tubulars; however, these may be difficult to control, may not properly secure the tubular, and do not necessarily permit personnel to manipulate the tubular ends with the required precision and speed.
Alternatively, it is well known to utilize a trough for carrying tubular whereby the trough can be raised or lowered at a proximal end positioned adjacent a service rig to assist in transferring tubular to and from the rig floor, commonly referred to as “pick up” and “lay down”, respectively. In general, the trough is longitudinally positioned along a base and an elevation of the proximal end is adjusted by an actuator positioned between the base and the trough. The trough thereby moves between a lower horizontal position and an inclined position. Typically, a distal end of the trough, remote from the rig, is longitudinally movable along the base, such as by attachment of the trough to a roller or slide assembly in the base, to further adjust the position of the inclined trough toward the rig. When the trough is in the inclined position, a proximal end of a tubular received therein is generally positioned at the height of the rig floor. Workers on the rig can then attach the proximal end of the tubular to an elevator to pull the tubular off the trough for installation in the well. In the reverse operation, tubular that has been tripped out of the well is positioned on the inclined trough, which is then lowered to the base where the tubular can be unloaded and returned to storage racks or to a transport vehicle. Typically, cranes or other overhead lifting means are used for moving tubular between the pipe handler and other locations.
A variety of trough-base apparatus have been disclosed which have additional features to further assist in the mechanical handling of tubular. For example, U.S. Pat. No. 4,426,182 to Frias (“Frias”) provides a carriage or push member that is adapted to be driven bi-directionally between the ends of the trough for moving a tubular, such as pipe, up or down the inclined trough. Frias further discloses a discrete transferring assembly for transferring pipe between the trough and a storage rack. The transferring assembly is positioned on the side of the base and adjacent a rack located adjacent to the base. Pipe from the trough is rolled across the base to a tilt tray. The tilt tray tilts to receive pipe rolled over from the base and tilts to dump pipe to the rack or vice versa. Further, tilt tray is arranged as a four-bar linkage to adjust its height while remaining horizontal.
Canadian patent 2,224,638 to Morelli (“Morelli”) discloses a kicker nestably positioned within the trough for ejecting pipe out of the trough and onto the base. The kicker is operated by a rod that engages the underside of the kicker to laterally tip the kicker to roll the pipe out of the trough. A dump assembly is also provided to clear pipe from the base after it has been ejected from the trough. The dump assembly comprises a secondary trough nestably positioned in the base alongside the pipe trough. The secondary trough receives the ejected pipe and is moveable in an arc above the base to a point at which the pipe falls from the secondary trough and away from the base. Morelli also discloses a pivoting leg member that passively raises the end of the trough remote from the rig in response to longitudinal and vertical movement of the other end of the trough, to thereby permit further adjustment of the position of the inclined trough.
While Frias and Morelli generally reduce the manual labor required to use a trough-based handler, Frias has multiple discrete components and is complicated in design, while Morelli does not provide for transfer of tubulars between a stack and the trough. Further, prior art handling apparatus do not secure the ends of a tubular as it is being guided between the trough and the service rig, thereby risking injury to workers in the vicinity of the tubular. In addition, prior art pipe handling apparatus require that separate storage racks be provided for storing tubulars and separate transport vehicles be used for hauling pipe to and from the worksite.
Therefore, there is a need in the art for an improved apparatus for handling tubulars.
SUMMARY OF THE INVENTIONApplicant has provided an improved apparatus for handling tubulars that is simple in design and efficient in operation. The apparatus not only provides for transfer of tubulars to and from an elevated position, but also stacks and unstacks tubulars on the apparatus itself. Advantageously, the apparatus eliminates the need for a separate stacking rack, cranes and other equipment used for removing tubulars from the apparatus for storage and transport. In a preferred embodiment, the apparatus can be used both for transport of tubulars to the work site and for manipulation of tubulars for pick-up and lay-down operations. Further, the apparatus is capable of manipulating both ends of a tubular during tubular handling operations, thereby increasing versatility, increasing worker safety, minimizing components and reducing the requirement for manual handling of the tubular.
In one embodiment of the invention, stacking apparatus for handling tubulars on a base is provided comprising: a base for supporting a stack of one or more layers of a plurality of tubulars, the base preferably being a trailer; a trough having a longitudinal axis positioned along the base and having an open top for receiving a tubular; a first actuator for adjusting the elevation of the trough relative to the base and for at least maintaining the trough substantially parallel to the base; and a second actuator for orienting the open top of the trough between an upright supporting position and tipped transfer position for transfer of tubulars to and from an uppermost layer of the stack.
Preferably the first actuator is a trough control assembly comprising: a lift actuator for adjusting the elevation of a first distal end of the trough; an angle actuator connected between the base and the trough and spaced apart from the trough's distal end for adjusting the elevation of a second, proximal end of the trough wherein coordinated movement of the lift actuator and the angle control actuator permits elevation of the trough substantially parallel to the layers of tubulars, inclination of the trough through pivoting about the first and second pivots, or both elevation and inclination of the trough.
Further, longitudinal manipulation of tubulars is enhanced using a grabber spaced apart from the distal end of the trough, the grabber having a pivotal end connected to the base for pivotal movement of the grabber and having a grabber end for releasably grabbing a tubular supported in the trough and extending beyond the proximal end of the trough; and a third grabber actuator for pivoting the grabber towards and away from the distal end of the trough, whereby coordinated actuation of the trough control assembly and grabber actuators permits the grabber to manipulate tubulars longitudinally towards and away from the trough respectively through grabbing and pivoting of the grabber.
The apparatus enables a methodology for moving tubulars longitudinally to and from an off-base location such as a pick-up and lay-down operation in well servicing comprising: positioning the base with the proximal end of the trough adjacent the off-base location; unloading tubulars from the base comprising manipulating a tubular supported in the trough to the off-base location by elevating the proximal end of the trough with the tubular supported therein, pivoting the grabber end toward the trough to position the grabber end below the proximal end of the supported tubular, lowering the proximal end of the trough to engage the proximal end of the tubular with the grabber end, grabbing the tubular with the grabber end, and pivoting the grabber end away from the trough to manipulate the tubular longitudinally towards the adjacent off-base location, and releasing the tubular from the grabber end; and loading tubulars to the base comprising manipulating the tubular suspended at the off-base location to the trough by lowering the distal end of the tubular from the off-base location towards the base, grabbing the distal end of the tubular with the grabber end, guiding the distal end of the tubular with the grabber end to the trough, and pivoting the grabber end toward the trough to further guide the distal end of the tubular slidably and supportably into the trough.
BRIEF DESCRIPTION OF THE DRAWINGSThe following drawings are intended to illustrate embodiments of the invention and are not intended to limit the scope of the invention:
With reference to
The trough 28 is generally V-shaped having an open top 29 for receiving and supporting a tubular 21 such as drill and production pipe. The trough 28 extends longitudinally along the base 22. A first actuator is provided for adjusting the elevation of the trough 28 relative to the base and for at least maintaining the trough substantially parallel to the base 22. The first actuator comprises a trough control assembly 32 generally positioned at the distal end 26 of the base 22 and connected to the trough 28 for assisting with elevational control of the trough 28. The first actuator further comprises an angle control actuator 50 positioned along the trough 28 for further assisting with elevational control of the trough 28.
Tubulars 21 are loaded and unloaded between a stack 30 (
The grabber 34 is positioned adjacent the proximal end 24 of the base 22 and is spaced apart from the trough 28. As described in more detail below, operation of the apparatus 20 requires coordinated repositioning of the elevation, the inclination, or both the elevation and inclination of the trough 28 by the trough control assembly 32 and the angle control actuator 50 and additionally with the grabber 34 for transferring a tubular 21 between the base 22 and an off-base location such as an elevated location including a gas or oil well service rig. A control box 36 houses control levers 38 for operating the apparatus 20 and is positioned at the distal end 26 of the base 22 to provide a convenient and safe location for manipulating tubulars 21 to and from the base 22 at the proximal end 24. Although the base 22 as illustrated is a mobile trailer, other varieties of a mobile or non-mobile base 22 can be used. It is to be understood that the term tubular(s) 21 includes any elongated member of circular cross-section or cylindrical member that is suitable for use with the apparatus 20.
Referring to
Referring to
Trough Control Assembly
With further reference to
The lift actuator 48 is positioned adjacent to the distal end 42 of the trough 28 and comprises a trough tail-end guide plate 70 movable in a substantially vertical track 71. The trough 28 is supported by a support arm 74 which in turn is supported by the tail-end guide plate 70. The support arm 74 is rotationally actuable for rotation of the trough 28 about its distal end 42.
The lift actuator 48 comprises generally vertical lift member or arm 56 that is vertically actuated relative to the base 22 by a lift hydraulic cylinder 58 or other suitable actuator. In detail, a bottom end 60 of the lift hydraulic cylinder 58 is securely attached to the base 22, while a top end 62 of the lift hydraulic cylinder 58 is connected to a top end 64 of the lift arm 56 by a cross-connector 66. A bottom end 68 of the lift arm 56 is attached to, or is integrally formed with, the guide plate 70 that is slidably received between two opposing generally vertical side rails 71a,7b of the track 71 to permit vertical movement of the lift arm 56 while maintaining vertical alignment of the lift arm 56. Extending through the guide plate 70 is the T-shaped support arm 74. The T-shaped arm 74 is rotatable about a longitudinal axis to enable tipping of the trough 28 and is connected at the laterally extending T-intersection to a yoke 76 extending outwardly from the trough 28. The yoke 76 forms a first pivot 97 for pivotal connection at the T-intersection for enabling inclination of the trough 28 about its distal end 42. In this arrangement, extension and retraction of the lift hydraulic cylinder 58 causes the distal end 42 of the trough 28 to be raised and lowered at the guide plate 70, respectively, as seen in
Tipping Control
Referring also to
Angle Control
With reference to
Although the lift actuator 48 and angle control actuator 50, and the tip actuator 52 have been described with respect to the preferred embodiment, other suitable arrangements for adjusting the elevation and angle of the trough 28 while providing for tipping of the trough 28 can be employed, as would be contemplated by one skilled in the art.
Stacking
In operation and with reference to
Generally, stacking and unstacking operations require coordinated adjustment of the elevation of the trough 28 using the lift actuator 48 and angle control actuator 50. Tubulars 21 are typically loaded laterally into and out of the trough 28 when the trough 28 is oriented substantially parallel to the base 22, tipping the trough 28 with the tip actuator 52, as necessary. Preferably, the grabber 34 is used to manipulate tubulars 21 longitudinally on and off of the trough 28, as described later in more detail.
Referring now to
Alternatively (not shown), the trough 28 can be positioned along a side of the base 22 such that tipping of the open top 29 of the trough 28 is required to one side only. Positioned at the side of the base 22, the trough 28 can not only be used to stack tubulars 21 on one side of the base 22, but can also be used to stack tubulars 21 to a separate rack or other apparatus positioned adjacent an opposing side of the base 22.
To retain the stack 30 on the base 22, the plurality of tubulars 21 in a layer are constrained laterally. To prevent stacked layers of tubulars 21 from rolling toward the trough 28 and to provide a rolling surface for the tubulars 21 during stacking and unstacking operations, two or more of the spacers 104 can be removeably positioned between adjacent stacked layers 100,100 of tubulars 21. In particular, the spacers 104 comprise L-shaped bars having a downwardly depending retaining arm 108 adjacent the trough 28 so as to restrain tubulars 21 from rolling towards the trough 28. The spacers 104 are positioned to extend across each layer 100 transverse to the stack 30 and substantially perpendicular to the axes of the tubulars, with the retaining arm 108 adjacent the trough 28 and extending downwards toward a lower layer 100. The spacers 104 thereby provide a surface for rolling a tubular 21 of the plurality of tubulars within the layer 100 and between the layer and the trough 28. An opposing end 110 of the spacers 104 are removeably secured to the base 22.
Having reference to
Preferably, as shown in
Other configurations and arrangements for the retaining and spacing tubulars 21 on the base 22 can be used, as would be contemplated by one skilled in the art. For example, the spacer 104 can be an extended sheet rather than a bar, in which case only a single spacer may be necessary. Alternatively, the retaining pipe spacing functions may be provided as separate components, rather than as a unified component.
Loading and Unloading of Tubulars
Having described the stacking and unstacking operation of the apparatus 20, the apparatus 20 is now described with respect to moving tubulars 21 between the trough 28 and a destination adjacent the proximal end 24 of the base 22 such as the floor of a service rig. The stacking and unstacking are also generally referred to as “pick up” and “lay down”, respectively. In general, pick up and lay down operations require the coordinated movement of the proximal end 40 of the trough 28 by the angle control actuator 50, previously described, and the grabber 34.
Referring now to
The grabber arm 34 is pivotally moved by any suitable third actuating means which, in one embodiment, is a grabber arm hydraulic cylinder 128 that is pivotally connected to a midsection 130 of the grabber arm 126 and is further pivotally connected to the base 22. Extension and retraction of the grabber arm hydraulic cylinder 128 thereby pivotally moves the grabber arm 126 to move the grabber head 124 towards and away from the trough 28.
Preferably, the grabber arm 126 is further fit with a fourth actuator such as a hydraulic cylinder (not shown) for adjusting the elevation of the grabber head 124.
With reference to
In the preferred embodiment as shown in
The apparatus 20 is suitable for conducting operations to move tubulars longitudinally to and from an off-base location.
Referring now to
As shown in
At
If desired, either personnel or, more preferably, the grabber 34 can intercept the distal end 46 of the tubular 21 as it swings under gravity to approach the rig 142. Accordingly, as shown in
Referring now to
During the tubular handling operations described in
While it is preferable that the pick up and lay down operations of the apparatus 20 be performed in conjunction with the unstacking and stacking operations, respectively, this is not required. For example, the grabber 24 can be used with a trough 28 in which only the proximal end 40 of the trough 28 can be lifted. In this case, other means must be used to stack and unstack tubulars such as pipe. In another example using the stacking embodiment, a carriage member rather than the grabber 34 may be implemented for longitudinally moving tubulars 21 along the trough 28.
While the preferred embodiment has described the use of the apparatus 20 for handling wellbore tubulars 21 and in the context of a service rig 142, the apparatus 20 can be used in any situation that requires stacking and unstacking or picking up and laying down of tubulars 21. For example, the apparatus 20 can be used at a construction site for handling rebar or pilings, and which are further handled by an elevator such as a crane.
The base 22 incorporates additional safety and environmental features such as deck drip trays or catch basins which correspond to the distal and proximal ends 46,44 of the tubulars 21 for receiving fluids draining therefrom and minimizing spills. An operator control platform for manipulation of the trough 28 and grabber 34 is located remote from the tubulars 21 themselves. Load stabilizers are provided to secure the base 22 when incorporated in a wheeled trailer. Personnel safety is improved through minimization of worker contact with heavy tubulars 21 in motion through mechanization of tubular 21 manipulation.
Although preferred embodiments of the invention have been described in some detail herein above, those skilled in the art will recognize that various substitutions and modifications of the invention may be made, without departing from the scope of the invention.
Claims
1. An apparatus for handling tubulars comprising:
- a base for supporting a stack of one or more layers of a plurality of tubulars;
- a trough having a longitudinal axis positioned along the base and having an open top for receiving a tubular;
- a first actuator for adjusting the elevation of the trough relative to the base and for at least maintaining the trough substantially parallel to the base; and
- a second actuator for orienting the open top of the trough between an upright supporting position and tipped transfer position for transfer of tubulars to and from an uppermost layer of the stack.
2. The apparatus of claim 1 wherein the first actuator is a trough control assembly comprising:
- a lift actuator for adjusting the elevation of a first distal end of the trough;
- an angle actuator connected between the base and the trough and spaced apart from the trough's distal end for adjusting the elevation of a second proximal end of the trough; and
- a first pivot between the trough and the distal end of the trough,
- a second pivot between the trough and the proximal end of the trough,
- wherein coordinated movement of the lift actuator and the angle control actuator permits elevation of the trough substantially parallel to the layers of tubulars,
- inclination of the trough through pivoting about the first and second pivots, or both elevation and inclination of the trough.
3. The apparatus of claim 2 wherein the first pivot further comprises a rotationally actuable support arm connected between the lift actuator and the second actuator for a tipping rotation of the trough by the second actuator about the trough's longitudinal axis.
4. The apparatus of claim 3 wherein
- the lift actuator further comprises
- a lift arm which is vertically actuable relative to the base; and
- a guide plate supported by the lift arm, the second actuator is supported by the lift arm and further comprises
- a crank connected to the support arm and rotationally actuable relative to the lift arm.
5. The apparatus of claim 1 further comprising one or more spacers positioned between adjacent layers of tubulars for providing a rolling surface therebetween.
6. The apparatus of claim 5 wherein each of the one or more spacers further comprise a downwardly depending arm adjacent the trough to restrain tubulars from rolling toward the trough.
7. The apparatus of claim 1 wherein the base is a mobile trailer.
8. The apparatus of claim 1 wherein the trough is positioned along a midline of the base and the open top of the trough is capable of being tipped to both sides.
9. A method of stacking tubulars using the apparatus of claim 1 comprising:
- orienting the trough to the supporting position with a tubular supported therein;
- adjusting the elevation of the trough to the uppermost layer of the stack;
- orienting the trough to the transfer position to unload the tubular from the trough; and
- repeating the orienting, adjusting and orienting steps to transfer supported tubulars to the uppermost layer of the stack.
10. The method of claim 9 further comprising positioning two or more spacers spaced longitudinally between adjacent layers of tubulars to provide a rolling surface.
11. A method of unstacking tubulars using the apparatus of claim 1 comprising:
- adjusting the elevation of the trough to the uppermost layer of tubulars in a stack of tubulars;
- orienting the trough to receive a tubular;
- rolling a tubular onto the trough from the plurality of tubulars in the uppermost layer;
- unloading the tubular from the trough; and
- repeating the adjusting, orienting, rolling and unloading steps to unstack the tubulars.
12. The apparatus of claim 1 further comprising:
- a grabber spaced apart from the distal end of the trough, the grabber having a pivotal end connected to the base for pivotal movement of the grabber end towards and away from the distal end of the trough and having a grabber end for releasably engaging a tubular supported in the trough and extending beyond the proximal end of the trough, whereby coordinated movement of the proximal end of the trough and the grabber permits the grabber to move tubulars longitudinally towards and away from the trough respectively.
13. The apparatus of claim 2 further comprising:
- a grabber spaced apart from the distal end of the trough, the grabber having a pivotal end connected to the base for pivotal movement of the grabber end and having a grabber end for releasably grabbing a tubular supported in the trough and extending beyond the proximal end of the trough; and
- a third actuator for pivoting the grabber towards and away from the distal end of the trough,
- whereby coordinated actuation of the first and third actuators permits the grabber to manipulate tubulars longitudinally towards and away from the trough respectively through grabbing and pivoting of the grabber.
14. The apparatus of claim 13 wherein the grabber end comprises a lower supporting jaw and an upper grabbing jaw for releasable engagement of a tubular positioned therebetween.
15. The apparatus of claim 14 wherein the grabber end is pivotally attached to the grabber for adjustment of the upper and lower jaws to conform substantially with the longitudinal axis of the tubular supported in the trough.
16. The apparatus of claim 15 further comprising a fourth actuator for extending the grabber end for adjusting the elevation the grabber head.
17. A method for moving a tubular longitudinally to an off-base location using the apparatus of claim 13 comprising:
- positioning the base with the proximal end of the trough adjacent the off-base location;
- elevating the proximal end of the trough with the tubular supported therein;
- pivoting the grabber end toward the trough to position the grabber end below the proximal end of the supported tubular;
- lowering the proximal end of the trough to engage the proximal end of the tubular with the grabber end;
- grabbing the tubular with the grabber end; and
- pivoting the grabber end away from the trough to manipulate the tubular longitudinally towards the adjacent off-base location.
18. The method of claim 17 further comprising:
- engaging the proximal end of the tubular to an elevator at the off-base location;
- releasing the proximal end of the tubular from the grabber end;
- raising the tubular with the elevator for lifting the proximal end of the tubular from the grabber end, with the distal end of the tubular being slidably supported by the trough; and
- lifting the distal end of the tubular out of the trough.
19. The method of claim 17 wherein prior to lifting the distal end of the tubular out of the trough, the method further comprising:
- pivoting the grabber end toward the distal end of the tubular grabbing the distal end of the tubular with the grabber end;
- pivoting the grabber end away from the trough to guide the distal end of the tubular as it moves away from the trough; and
- guiding the tubular through the grabber end while lifting the distal end of the tubular out of the trough.
20. A method for moving a tubular longitudinally to the trough from an off-base location using the apparatus of claim 13 comprising the steps of:
- positioning the proximal end of the trough adjacent the off-base location;
- lowering the distal end of the tubular from the off-base location to towards the base;
- grabbing a distal end of the tubular with the grabber end pivoted toward the off-base location;
- guiding the distal end of the tubular with the grabber end to the trough;
- pivoting the grabber end toward the trough to further manipulate the distal end of the tubular slidably and supportably into the trough;
- releasing the grabber end from the tubular and lowering the proximal end of the tubular from the off-base location;
- pivoting the grabber end away from the trough to position the grabber end below the proximal end of the tubular;
- lowering the tubular from the off-base location and grabbing the proximal end of the tubular with the grabber end;
- releasing the proximal end of the tubular from the off-base location; and
- pivoting the grabber end towards the trough to move the tubular onto the trough until the tubular is supported therein.
21. The method of claim 20 wherein the off-base location further comprises an elevator for releasably engaging a proximal end of the tubular and wherein the lowering of the tubular from the off-base location further comprises:
- engaging the proximal end of the tubular with the elevator at the off-base location;
- lowering the elevator for
- lowering the distal end of the tubular to the grabber end, and after guiding the distal end of the tubular to the trough, then
- lowering the proximal end of the tubular to the grabber end as the distal end slides in the trough.
22. A method for moving tubulars longitudinally to and from an off-base location using the apparatus of claim 13 comprising:
- positioning the base with the proximal end of the trough adjacent the off-base location;
- unloading tubulars from the base comprising manipulating a tubular supported in the trough to the off-base location by elevating the proximal end of the trough with the tubular supported therein, pivoting the grabber end toward the trough to position the grabber end below the proximal end of the supported tubular, lowering the proximal end of the trough to engage the proximal end of the tubular with the grabber end, grabbing the tubular with the grabber end, and pivoting the grabber end away from the trough to manipulate the tubular longitudinally towards the adjacent off-base location, and releasing the tubular from the grabber end; and
- loading tubulars to the base comprising manipulating the tubular suspended at the off-base location to the trough by lowering the distal end of the tubular from the off-base location towards the base, grabbing the distal end of the tubular with the grabber end, guiding the distal end of the tubular with the grabber end to the trough, and pivoting the grabber end toward the trough to further guide the distal end of the tubular slidably and supportably into the trough.
23. The method of claim 22 wherein:
- prior to manipulating the tubular from the base to the off-base location, unloading the base further comprising adjusting the elevation of the trough to the uppermost layer of tubulars in a stack of tubulars; orienting the trough to receive a tubular;
- rolling the tubular from the uppermost layer onto the trough and repeating the adjusting, orienting, rolling and manipulating steps to unload tubulars one-by-one to the off-base location; and
- after manipulating the tubular from the off-base location to the trough,
- unloading the trough comprising adjusting the elevation the trough to the uppermost layer of the stack, orienting the trough to the transfer position to unload the tubular from the trough to the uppermost layer, re-orienting the trough to the supporting position to receive another tubular, and repeating the elevation adjusting, orienting and re-orienting steps to transfer each manipulated tubular from the off-base location uppermost layer of the stack.
Type: Application
Filed: Aug 30, 2005
Publication Date: Jun 15, 2006
Inventors: Cheryl GUST (Medicine Hat), Sam GUST (Medicine Hat)
Application Number: 11/162,136
International Classification: E21B 19/14 (20060101);