Abstract:
The present invention relates to a new apparatus and method for use in subterranean exploration. The present invention provides a rapid rig-up and rig-down of a drill floor mounted device such as a pipe racking system. In particular, the present invention discloses a system and method for rapid deployment of a drill floor mounted pipe racking system that is capable of being retrofit to an existing drilling rig.

Description:
TECHNICAL FIELD OF INVENTION 
     The present invention relates to a new apparatus and method for use in subterranean exploration. The present invention provides a system and method for rapid rig-up and rig-down of a mechanism that is mountable to a drill floor of a conventional drilling rig, such as a pipe racking mechanism. Still more particularly, the present invention discloses an apparatus and method for rapid deployment of a drill floor mounted pipe racking system during rig-up at a new drilling location. 
     BACKGROUND OF THE INVENTION 
     In the exploration of oil, gas and geothermal energy, drilling operations are used to create boreholes, or wells, in the earth. Subterranean drilling necessarily involves the movement of long lengths of tubular sections of pipe. At various intervals in the drilling operation, all of the drill pipe must be removed from the wellbore. This most commonly occurs when a drill bit wears out, requiring a new drill bit to be located at the end of the drill string. It can also be necessary to reconfigure the bottom-hole assembly or replace other downhole equipment that has otherwise failed. When the drill pipe has to be removed, it is disconnected at every second or third connection, depending on the height of the mast. On smaller drilling rigs used in shallower drilling, every other connection is disconnected, and two lengths of drill pipe, known as “doubles,” are lifted off of the drill string, aligned in the fingers of the rack by the derrickman, and then lowered onto the drill floor away from the well center. On larger drilling rigs used for deeper drilling, every third connection is disconnected and three lengths of pipe, known as “triples,” are lifted off of the drill string, aligned in the fingers of the rack by the derrickman, and then lowered onto the drill floor away from the well center. The doubles and triples are called a stand of pipe. The stands are stored vertically on the rig floor, aligned neatly between the fingers of the rack on the mast. A triple pipe stand is long and thin (about ninety feet long). 
     Removing all of the drill pipe from the well and then reconnecting it to run back into the well is known as “tripping the pipe” or “making a trip,” since the drill bit is making a round trip from the bottom of the hole to the surface and then back to the bottom of the hole. Tripping the drill pipe is a very expensive and dangerous operation for a drilling rig. Most injuries that occur on a drilling rig are related to tripping the pipe. Additionally, the wellbore is making no progress while the pipe is being tripped, so it is downtime that is undesirable. This is why quality drill bits are critical to a successful drill bit operation. Drill bits that fail prematurely can add significant cost to a drilling operation. Since tripping pipe is “non-drilling time,” it is desirable to complete the trip as quickly as possible. Most crews are expected to move the pipe as quickly as possible. 
     There are a number of variables that contribute to a very irregular and hostile movement of the pipe stand as it is disconnected and moved to the rack for setting on the drill floor, as well as when it is being picked up for alignment over the wellbore center for stabbing and connection to the drill string in the wellbore. For example, the vertical alignment and travel of the elevator and hoist connection which lift the drill string from the wellbore is cable connected and capable of lateral movement which is translated to the drill string rising from the wellbore. Also, the drill string is supported from the top, and as the derrickman moves the drill string laterally, the accelerated lateral movement of the long length of the pipe stand away from the well center generates a wave form movement in the pipe itself. As a result of the natural and hostile movement of the heavy drill stand, which typically weighs between 1,500 and 2,000 lbs., and drill collars which weigh up to 20,000 lbs., it is necessary for the crew members to stabilize the drill pipe manually by physically wrestling the pipe into position. The activity also requires experienced and coordinated movement between the driller operating the drawworks and the derrickman and floorhands. Many things can go wrong in this process, which is why tripping pipe and pipe racking is a primary safety issue in a drilling operation. 
     Attempts have been made to mechanize all or part of the pipe racking operation. On offshore platforms, where funding is justifiable and drill floor space is available, large Cartesian racking systems have been employed in which the drill stands are gripped at upper and lower positions to add stabilization, and tracked modules at the top and bottom of the pipe stand coordinate the movement of the pipe stand from the wellbore center to a racked position. Such systems are very large and very expensive, and are not suitable for consideration for use on a traditional land based drilling rig. 
     An attempt to mechanize pipe racking on conventional land based drilling rigs is known as the Iron Derrickman® pipe-handling system. The apparatus is attached high in the mast, at the rack board, and relies on a system of hydraulics to lift and move stands of drill pipe and collars from hole center to programmed coordinates in the racking board. This cantilever mast mounted system has a relatively low vertical load limit, and therefore requires assistance of the top drive when handling larger diameter collars and heavy weight collars. 
     The movement of the pipe with this system has proved unpredictable and thus requires significant experience to control. One problem with this system is that it grips the pipe far above the center of gravity of the tubular and fails to control the hostile movement of the drill pipe stand sufficiently to allow for safe handling of the stands or for timely movement without the intervention of drilling crew members. In particular, the system is not capable for aligning the lower free end of the drill stand accurately for stabbing into the drill string in the wellbore without frequent human assistance. As a result of these and other deficiencies, the system has had limited acceptance in the drilling industry. 
     An alternative system that is known provides vertical lifting capacity from the top drive and a lateral movement only guidance system located near the rack. The system still requires a floorman for stabbing the pipe to the stump as well as to the set-back position. 
     A primary difficulty in mechanizing pipe stand racking is the hostile movement of the pipe that is generated by stored energy in the stand, misaligned vertical movement, and the lateral acceleration and resultant bending and oscillation of the pipe, which combine to generate hostile and often unpredictable movements of the pipe, making it hard to position, and extremely difficult to stab. 
     A conflicting difficulty in mechanizing pipe stand racking is the need to move the pipe with sufficient rapidity that cost savings are obtained over the cost of manual manipulation by an experienced drilling crew. The greater accelerations required for rapid movement store greater amounts of energy in the pipe stand, and greater attenuated movement of the stand. 
     Another primary obstacle in mechanizing pipe stand racking is the prediction and controlled management of the pipe stand movement sufficient to permit the precise alignment required for stabbing the pipe to a first target location on the drill floor and to a second target location within the fingers of the racking board. 
     An even greater obstacle in mechanizing pipe stand racking is the prediction and controlled management of the pipe stand movement sufficient to achieve the precise alignment required for stabbing the tool joint of the tubular held by the racking mechanism into the receiving tubular tool joint connection extending above the wellbore and drill floor. 
     Another obstacle to land-based mechanizing pipe stand racking is the lack of drilling floor space to accommodate a railed system like those that can be used on large offshore drilling rigs, as well as the several structural constraints that are presented by the thousands of existing conventional drilling rigs, where the need to retrofit is constrained to available space and structure. 
     A recent solution to these several obstacles is disclosed in U.S. patent application Ser. No. 13/681,244. This solution provides a relatively large and complex pipe racking mechanism that must be stability erected on the top of a conventional drill floor of a land based drilling rig, where it must also be connected securely to the mast of the drilling rig. 
     Thus, the best technology for an automatic pipe racking solution creates a significant related obstacle in the transportation and rig-up and rig-down of such a large system. A first obstacle is to efficiently reduce such a large structure into a transportable envelope. A second obstacle is to accomplish the conversion from a truck mounted transportable load to a rigged-up position using the existing equipment for positioning and raising the mast and substructure of the conventional drilling rig. 
     It is also desirable to minimize accessory structure and equipment, particularly structure and equipment that may interfere with transportation or with manpower movement and access to the rig floor during drilling operations, or that will unreasonably extend the time needed to erect the drilling rig. It is also desirable to ergonomically limit the manpower interactions with rig components during rig-up for cost, safety and convenience. 
     Thus, the currently best known solution for automatic pipe racking problems presents unique challenges of rig-up, rig-down and transportation. 
     The various embodiments of the present invention provide for a system and method of efficient rig-up, rig-down and transportation of a drill floor mountable automatic pipe racking device capable of use on a conventional land based drilling rig floor. 
     SUMMARY OF THE INVENTION 
     The present invention provides a new and novel pipe stand racking system and method of use. In one embodiment, an automatic pipe racker is provided, having a base frame connectable to a drill floor of a drill rig and extending upwards at a position offset to a V-door side of a drilling mast that is also connected to the drill floor. In one embodiment, the base frame is a C-frame design. A mast brace may be connected between the base frame and the drilling mast at a position distal to the drill floor for stabilizing an upper end of the base frame in relationship to the mast. A tensioner may be connected between the base frame and the drilling floor for stabilizing the base frame in relationship to the substructure. 
     The base frame is connectable to the drill floor of a drill rig, in a position offset to the drilling mast. A pair of base legs is pivotally connected to the base frame, and movable between a retracted position for transportation and an extended position for pivotal connection to the drill floor. A pipe handling mechanism is extendable from the base frame, and capable of moving stands of connected pipe from a racked position on the drill floor to a stabbing position above a drill string component held in a rotary table. 
     Besides the base frame, the pipe stand racking system may include components such as a lateral extend mechanism connected to the base frame, and extendable between a retracted position and a deployed position. The pipe handling mechanism may further include a rotate mechanism connected to the lateral extend mechanism, and being rotatable in each of the left and right directions. A finger extend mechanism may further be connected to the rotate mechanism, being laterally extendable between a retracted position and a deployed position. 
     A vertical grip and stab mechanism may be attached to the finger extend mechanism. The gripping mechanism has grippers to hold a tubular pipe or stand of pipe and is capable of moving the pipe vertically to facilitate stabbing. 
     The automatic pipe racking system is series nested and substantially retractable into the base frame. This property transforms the automatic pipe stand racking system into a structure having a transportable envelope. 
     In another embodiment, a system is provided for transportation and erection of an automated pipe racker, comprising a base frame connectable to a drill floor of a drill rig, offset to a drilling mast that is also connected to the drill floor. A pair of legs is retractably connected to the base frame, and movable between a retracted position for transportation and an extended position for connection to the drill floor. A mast brace is connectable between the base frame and the drilling mast. A skid assembly is connected to the base frame. The skid assembly is designed to be a platform on which the automatic pipe racker rests during transportation. 
     In one embodiment, the skid assembly is tiltable to facilitate connection to the drill floor for rig-up. In this embodiment, the skid assembly has an upper skid and a lower skid, with the lower skid pivotally connected to the base frame and movable between an extended position for transportation and a retracted position for connection of the automatic pipe racker to the drill floor for rig-up. 
     In another embodiment, a retractable standoff is located between the base frame and lower skid. An optional retractable latch may be provided to lock or unlock the position of the lower skid in relation to the base frame. A jack may be provided and located proximate to the upper skid. The jack is extendable to tilt the automatic pipe racker onto the lower skid when the lower skid is in the retracted position. 
     A ground pivot point is located near the center of gravity of the automated pipe racker when the automatic pipe racker is resting on the skid assembly. The upper skid portion extends substantially (mostly) above the ground pivot. The lower skid portion extends substantially (mostly) below the ground pivot. The ground pivot is located in between the lower and upper skids. In another embodiment, the ground pivot is located near and below the center of gravity of the automated pipe racker when the automatic pipe racker is resting on the skid assembly, such that the automatic pipe racker will rest on the upper skid when the skid is resting on a substantially (mostly) horizontal plane. 
     As will be understood by one of ordinary skill in the art, the sequence of the steps, and designation of retractable elements disclosed may be modified and the same advantageous result obtained. For example, the functions of the upper and lower skids may be reversed, and other certain elements may be deployed before or after other elements where minor change in sequence does not change the result. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objects and features of the invention will become more readily understood from the following detailed description and appended claims when read in conjunction with the accompanying drawings in which like numerals represent like elements. 
       The drawings constitute a part of this specification and include exemplary embodiments to the invention, which may be embodied in various forms. It is to be understood that in some instances various aspects of the invention may be shown exaggerated or enlarged to facilitate an understanding of the invention. 
         FIG. 1  is an isometric view of a drilling rig fitted with an automatic pipe racking system of the type to which the present invention applies. 
         FIG. 2  is an isometric view of the automatic pipe racking mechanism, illustrated without the drilling rig, and showing a skid assembly mounted to the back side of the pipe racker. 
         FIG. 3  is an isometric representation of a transport vehicle transporting an automatic pipe racker to a position in alignment beneath the mast connected to the substructure. The transport vehicle is aligned for approach to the collapsed substructure. 
         FIG. 4  is a continuation of the rig-up process illustrated in  FIG. 3 , illustrating deployment of components of the automatic pipe racking system that were previously retracted for transportation. 
         FIG. 5  is a general side view of an optional embodiment, illustrating the automatic pipe racker resting on its skid assembly, in the transport position on the trailer bed of a truck. 
         FIG. 6  is a general side view of the base frame of the pipe racker, including an exploded view of a skid assembly normally connected to the base frame. 
         FIG. 7  is a general side view, illustrating the automatic pipe racker resting on its skid, with the skid assembly shown transitioning into the rig-up position. 
         FIG. 8  is a general side view, illustrating the automatic pipe racker resting on its skid, with the skid assembly shown in the rig-up position. 
         FIG. 9  is a continuation of the rig-up process illustrated in  FIG. 4 , illustrating movement of the transport vehicle closer to the substructure, tilting the automatic pipe racking system on the transport trailer bed, and connection of deployed components of the automatic pipe racking system to the drill floor and mast. 
         FIG. 10  is a continuation of the rig-up process illustrated in  FIG. 9 , illustrating the removal of the transport vehicle from beneath the mast, and with the automatic pipe racking system supported by its connection to the drill floor and the drill mast. 
         FIG. 11  is a continuation of the rig-up process illustrated in  FIG. 10 , illustrating partial raising of the mast and automatic pipe racking system to a position above the drill floor. 
         FIG. 12  is a continuation of the rig-up process illustrated in  FIG. 11 , illustrating the mast and automatic pipe racking system in the vertical position above the drill floor. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is presented to enable any person skilled in the art to make and use the invention, and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein. 
       FIG. 1  is an isometric view of an automatic pipe racking mechanism  100  including features of the invention disclosed in U.S. patent application Ser. No. 13/681,244, and which embodies a drill floor mounted structure of the type to which the present inventive system and method of raising applies. Drilling rig  10  has a drill floor  14  located over a wellbore  12 . A drilling mast  16  is mounted to drill floor  14 , which has an open V-door side  18 . Racking mechanism  100  is mounted on drill floor  14 , on the V-door side  18  of drilling mast  16 . 
     Racking mechanism  100  is comprised of a base frame  200  that is pivotally connected to drill floor  14  by floor pins  202 . In one embodiment, base frame  200  is a tapered C-frame that extends upwards from drill floor  14  at a position offset to V-door side  18  of drilling mast  16 . A pipe handling mechanism  800  is extendable from base frame  200 , and capable of moving stands of connected pipe  50  from a racked position on drill floor  14  to a stabbing position above a drill string component held in a rotary table. A mast brace  204  is connected between base frame  200  and drilling mast  16  at a position distal to drill floor  14  for stabilizing an upper end of base frame  200  in relationship to drilling mast  16 . In one embodiment, a pair of tensioning members  206  is connected between drill floor  14  and base frame  200 . 
     In one embodiment, the length of mast brace  204  is controllably adjustable to compensate for deflection of racking mechanism  100  under different payloads which vary with the size of the tubular being handled. Adjustment is also advantageous to accommodate non-verticality and settling of drilling rig  10 . Adjustment is also useful for connectivity to other mechanisms that deliver or receive pipe from racking mechanism  100 . Adjustment is also useful when using mast braces  204  as a connected lifting component of the present raising system. 
       FIG. 2  is an isometric view of base frame  200  of racking mechanism  100 , illustrating base frame  200  in isolation of the remaining components of racking mechanism  100  and of drilling rig  10 . In one embodiment, base frame  200  includes a pair of deployable legs  210  pivotally connectable at a lower end of base frame  200 . When legs  210  are deployed downward, deployed ends of legs  210  are connected to drill floor  14  (not shown) by floor pins  202 . Retraction of legs  210  provides a shorter transport profile for transporting racking mechanism  100  between drilling sites. 
     Base frame  200  also includes a pair of deployable arms  212 , pivotally attached to base frame  200 . In one embodiment, when arms  212  are deployed outward, deployed ends of arms  212  are connected to base frame  200  by struts  214 . In this embodiment, mast braces  204  are pivotally connected to the ends of arms  212 , and pivotally connectable to mast  16 . This connectivity increases the spacing between mast braces  204  and mast  16 , providing conflict free mechanical operation of racking mechanism  100 . Retraction of arms  212  and pivotal retraction of braces  204  provides a narrower transport profile for transporting racking mechanism  100  between drilling sites. In another embodiment (best seen in  FIG. 3 ), legs  210 , arms  212  and braces  204  fully retract without structural interference, such that each retracts proximate to base  200  for greater transportability. As shown in the present embodiment of base frame  200 , an optional bracket  216  may be provided for supporting mast braces  204  during transport of base frame  200 . Bracket  216  may be attached to struts  214  or mast braces  204  to secure these elements to the mast braces  204  during transport. 
     Base frame  200  has a skid assembly  220  attached to the side opposite mast  16 . In another embodiment, tensioning members  206  connect each side of base frame  200  to drill floor  14  (not shown) of drilling rig  10  (not shown). Tensioning members  206  stabilize base frame  200  of racking mechanism  100 . In one embodiment, tensioning members  206  are adjustable to stiffen racking mechanism  100 , and to compensate for verticality and the variable deflection of racking mechanism  100  when handling different sizes of drill pipe  50 . 
     It will be appreciated that the disclosed invention, or a similar automatic pipe racking system, must be capable of rapid disassembly and assembly. In contemporary drilling operations, it is necessary to minimize the downtime of the drilling rig and to “rig down” or disassemble the entire drilling rig to a minimum number of transportable components as quickly as possible. The transportable components must fit within regulated physical dimensions for safe transport on designated highways to remote locations where the drilling activity can resume. 
       FIG. 3  is an isometric representation of a transport vehicle  900  transporting racking mechanism  100  to a position in alignment beneath mast  16 . Drilling rig  10  has its mast  16  assembled but not raised. Mast  16  is pivotally connected to a substructure  30  that is also not raised. In the embodiment illustrated, mast  16  is optionally supported by a rack, such as a headache rack  40  for safety. In the embodiment illustrated in this view, base frame  200  has a skid assembly  220  attached. 
     Skid assembly  220  supports racking mechanism  100  on transport vehicle  900 . During transportation, and as illustrated here, lower skid  228  and upper skid  226  support racking mechanism  100  on the trailer bed  910  of transport vehicle  900 . Transport vehicle  900  is maneuvered to position racking mechanism  100  beneath mast  16 . Alternatively, racking mechanism  100  may be placed on the ground on top of skid assembly  220  and positioned into place with equipment such as a fork lift. 
       FIG. 4  is a continuation of the rig-up process illustrated in  FIG. 3 , illustrating deployment of components of racking mechanism  100  that were previously retracted for transportation as shown in  FIG. 3 . In particular, arms  212 , mast braces  204 , and legs  210  have been deployed. Optionally, when arms  212  are deployed outward, deployed ends of arms  212  may be connected to base frame  200  by struts  214  to further strengthen their position. 
     Also illustrated in  FIG. 4 , lower skid  228  has been retracted, and a jack  240  ( FIG. 6 ) has been actuated to tilt racking mechanism  100  backwards over pivot center  222  such that racking mechanism  100  is resting on retracted lower skid  228 . Upper skid  226  no longer supports the weight of racking mechanism  100 , as the center of gravity  224  of racking mechanism  100  has shifted below pivot center  222 . 
     In an optional embodiment, wheel assembly  242  is deployed when jack  240  is actuated to facilitate minor realignment of racking mechanism  100  relative to drill floor  14  as may be necessary. 
       FIG. 5  is a close-up side view, illustrating the automatic pipe racking mechanism  100  resting on skid assembly  220  in the transport position on trailer bed  910  of a transport vehicle  900 . 
     In the embodiment illustrated, skid assembly  220  has a skid ground pivot  222  located proximate to where lower skid  228  is pivotally connected to base frame  200 . Ground pivot  222  is also located near the center of gravity  224  of racking mechanism  100  when the automatic pipe racking mechanism  100  is resting on skid  220 . In this embodiment, an upper skid portion  226  extends above ground pivot  222 , and lower skid portion  228  extends below ground pivot  222 . 
     In this transport position, both lower skid  228  and upper skid  226  are in contact with trailer bed  910  of transport vehicle  900 . This configuration provides for stability during transport, as both lower skid  228  and upper skid  226  support the weight of racking mechanism  100  as transport vehicle  900  accelerates, decelerates and navigates turns, shifting the weight of racking mechanism  100  on trailer bed  910 . 
     In the embodiment illustrated, one or more skid stand-offs  230  are pivotally connected to lower skid portion  228  at pivot  232 . Retractable stand-offs  230  are pivotally connected to base frame  200  at pivots  234 . Stand-offs  230  hold lower skid  228  in the deployed position. Also seen in the embodiment illustrated, an optional jack  240  is located proximate to the upper end of upper skid  226 , opposite to the ground pivot  222  end of upper skid  226 . 
       FIG. 6  is a general side view of the lower portion of base frame  200 , including an exploded view of skid assembly  220  in accordance with an embodiment of the present invention. In this view, upper skid  226  is shown attached to base frame  200 . Lower skid  228  is shown detached from pivot  222 . Stand-offs  230  are shown having wheels  246  attached, which are mostly hidden from view in the other figures. 
     To transition racking mechanism  100  to a rig-up position, stand-offs  230  are moved from the extended position to the retracted position, causing lower skid  228  to retract into proximity with base frame  200 . In the embodiment illustrated, this movement exposes wheels  246  beneath lower skid  228 . This will permit wheels  246  to engage trailer bed  910  to facilitate corrective alignment of racking mechanism  100  with drill floor  14  and mast  16  if such alignment is necessary. Such engagement will occur in the next step of tilting. 
     Still referring to  FIG. 6 , a jack  240  is attached to a jack frame  244  having a wheel assembly  242  attached. To transition racking mechanism  100  to a rig-up position, jack  240  may be actuated, causing racking mechanism  100  to tilt onto wheels  242  of retracted lower skid  228 . In the embodiment illustrated, extension of jack  240  exposes wheel assembly  242  beneath upper skid  226 . This permits wheels  246  to engage trailer bed  910  to facilitate corrective alignment of racking mechanism  100  with drill floor  14  and mast  16  if such alignment is necessary. 
       FIG. 7  is a general side view, illustrating the automatic racking mechanism  100  resting on skid assembly  220 , with skid assembly  220  shown transitioning from the transport position to the rig-up position. In this intermediate step, stand-offs  230  are retracted, which retracts lower skid  228  about pivot  222  to a position closer to base frame  200 . Since center of gravity  224  is located on the upper skid  226  side of ground pivot  222 , racking mechanism  100  does not tip uncontrollably onto wheels  246  of lower skid  228 . 
       FIG. 8  is a general side view, illustrating automatic racking mechanism  100  resting on skid assembly  220 , with skid assembly  220  shown in the rig-up position. Jack  240  has been actuated so as to tilt racking mechanism  100  rearward until wheels  246  of lower skid  228  contact trailer bed  910 . Additionally, wheel assembly  242  comes into engagement with trailer bed  910  to further facilitate corrective alignment of racking mechanism  100  with drill floor  14  and mast  16  if such alignment is necessary. 
       FIG. 9  is a continuation of the rig-up process illustrated in  FIG. 4 , and as illustrated in  FIGS. 5-8 .  FIG. 9  illustrates movement of transport vehicle  900  into position closer to substructure  30 . Tilted automatic racking mechanism  100  on transport trailer bed  910  is now in position for connection of the deployed components of racking mechanism  100  to drill rig  10 . 
     As seen in  FIG. 9 , by tilting racking mechanism  100 , racking mechanism  100  is now positioned such that legs  210  extend appropriately over drill floor  14  to align legs  210  for pivotal connection to drill floor  14  with floor pins  202 . Mast braces  204  may also be pivotally connected to mast  16  in this position. Optionally, a pair of tensioning members  206  are connected between drill floor  14  and base frame  200 . Tensioning members  206  further stabilize base frame  200  in relationship to drilling rig  10 . Alternatively, tensioning members  206  may be connected after raising automatic pipe racking mechanism  100 . Optionally, a frame support  40  such as the headache rack, can be positioned underneath mast  16  for safety. 
       FIG. 10  is a continuation of the rig-up process illustrated in  FIGS. 3-9 .  FIG. 10  illustrates transport vehicle  900  removed from beneath mast  16 , and racking mechanism  100  remains suspended by its connections to drill rig  10 . When transport vehicle  900  departs, the racking board  20  can be attached to the mast  16  as shown. 
       FIG. 11  is a continuation of the rig-up process illustrated in  FIGS. 3-10 , illustrating partial raising of mast  16  and automatic pipe racking mechanism  100  towards a vertical position over drill floor  14 . This step is conventionally performed by extension of hydraulic cylinders sized for the task. As mast  16  is raised, automatic pipe racking mechanism  100  is pulled into position by mast braces  204  through arms  212 , pivoting automatic pipe racking mechanism  100  on the pivotal connection  202  of legs  210  to drill floor  14  at floor pins  202 . Tensioning members  206  are not shown connected between automatic pipe racking mechanism  100  and drill floor  14 , but they may be connected at this time as well. 
       FIG. 12  is a continuation of the rig-up process illustrated in  FIGS. 3-11 , illustrating mast  16  and automatic pipe racking mechanism  100  in the vertical position above drill floor  14 . Mast braces  204  are no longer supporting the weight of automatic pipe racking mechanism  100 . In this position, the verticality of automatic pipe racking mechanism  100  can be adjusted by adjustment of mast braces  204 . 
     As described, the relationship of these elements has been shown to be extremely advantageous in providing an automatic pipe racking mechanism  100  that can be mounted to a conventional drill floor, and that is capable of lifting and moving drill pipe between a racked position within a largely conventional racking board and a stabbed position over a wellbore. 
     Having thus described the present invention by reference to selected embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered desirable by those skilled in the art based upon a review of the foregoing description of embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.