Abstract:
A method and apparatus for manipulating and deploying lengths of pipe when drilling wells is provided. The apparatus has a motor assembly with a rotor shaft coupled to a drive gear, and a torque assembly with a planetary gear set coupled to the drive gear of the motor and an annular gear. Planet gears are coupled to a torque converter, which is coupled to a stub for connecting to pipe joints. The torque converter has inclined surfaces for circulating lubricant through the gear assembly, and the planet gears have openings in registration with the inclined surfaces. A drilling fluid pipe is disposed through the rotor shaft of the motor assembly, and is coupled to the torque converter. Lead-screw linear actuators position an elevator, which hangs from links hooked to the apparatus, to manipulate the drill string, and a self-locking pipe jaw handles pipe joints.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims benefit of U.S. provisional patent application Ser. No. 61/330,764, filed May 3, 2010, which is herein incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    1. Field of the Disclosure 
         [0003]    Embodiments described herein relate to apparatus for connecting drill strings for a petroleum well. More specifically, embodiments disclosed herein relate to a top drive device. 
         [0004]    2. Description of the Related Art 
         [0005]    Production of oil and gas is a trillion dollar industry. To get oil and gas out of the earth, large costly equipment is used under extreme conditions. Among this equipment are devices that align drill pipe for extending into a well bore. Such devices, known as top drives, are generally used to string pipe together for insertion into the well bore. Top drives are also used to rotate a drill string as the drilling operation progresses. A well is completed using a drill head coupled to a drill string that extends into the well bore as the drill head extends the well bore. The drill string also serves as a conduit for drilling fluids that lubricate the drill head and remove drilling solids. 
         [0006]    A platform is generally deployed over the well bore for supporting tools, such as the top drive, for manipulating the drill string. A spider generally holds the drill string extending into the well bore, and the top drive rotates the drill string. As the well bore extends, the top drive moves closer to the spider. When the top drive and the spider reach a pre-determined distance from each other, the top drive disengages from the drill string. The spider holds the drill string while the top drive engages a new spool into the string. The top drive lifts a new spool over the drill string, aligns it, and applies torque to thread the new spool into the drill string. The spider then releases the drill string, and the top drive begins lowering the drill string further into the well bore. A similar operation may be used to insert bore casing or other well bore components. The same operation may be run in reverse to remove well bore components. 
         [0007]    Well drilling is generally performed in locations that are remote and may be difficult to supply with large equipment and spare parts. In some locations, space to store spare parts may be limited. Further, maintenance of well drilling equipment can be costly in terms of lost production. It is desirable therefore to provide equipment for well drilling sites that is easily obtained, standardized as much as possible, readily stored, and easily replaced at convenient times. There remains an ongoing need for top drives that are easy to operate, assemble, and maintain, and can operate until convenient or economically attractive opportunities arise to maintain them. 
       SUMMARY 
       [0008]    Embodiments described herein provide a top drive assembly that has a frame, a rotation assembly coupled to the frame, the rotation assembly having a fluid conduit disposed therethrough, the fluid conduit disposed within an isolation sleeve with a pressure sensor, a torque assembly rotatably coupled to the fluid conduit, the torque assembly having one or more gears and a fluid circulator, a screw-actuated tilt thruster coupled to the frame, and an articulated pipe handler coupled to the frame. 
         [0009]    Other embodiments provide a torque assembly for a top drive that has a casing enclosing a planetary gear assembly, a circulator coupled to a plurality of planet gears, and a plurality of baffles extending from the circulator between the planet gears. 
         [0010]    Other embodiments provide a rotational assembly for a top drive apparatus having a motor assembly comprising a shaft coupled to a rotor, the shaft having a conduit formed therethrough and coupled to a driver gear, and a torque assembly comprising an annular gear and a plurality of planet gears in registration with the driver gear, wherein the planet gears are rotatably coupled to a torque member. 
         [0011]    Other embodiments provide a positioner for a top drive assembly, the positioner having a swivel, a strut pivotably coupled to a pivot point of the swivel, a linear actuator slidably coupled to the strut and pivotably coupled to a thrust point of the swivel, and a self-locking gripper assembly coupled to the swivel by a lift actuator. 
         [0012]    Other embodiments provide a pipe handler for a top drive assembly, the pipe handler having a pair of grippers, a linear actuator coupled to each gripper at a thrust end, and pivotably mounted to a base member at a pivot end, and a flexible linkage pivotably coupled to each gripper at a first end and pivotably coupled to the base member at a second end. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    So that the manner in which the above-recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
           [0014]      FIG. 1A  is an isometric view of an apparatus according to one embodiment. 
           [0015]      FIG. 1B  is another isometric view of the apparatus of  FIG. 1A  from a different viewpoint. 
           [0016]      FIG. 2  is a cross-sectional view of the apparatus of  FIGS. 1A and 1B . 
           [0017]      FIG. 3A  is a cross-sectional view of a motor assembly according to one embodiment. 
           [0018]      FIG. 3B  is a detail view of the motor assembly of  FIG. 3A . 
           [0019]      FIG. 4A  is a cross-sectional view of a gearbox assembly according to one embodiment. 
           [0020]      FIG. 4B  is a perspective view of a torque member according to another embodiment. 
           [0021]      FIG. 4C  is a top view of the gearbox assembly of  FIG. 4A . 
           [0022]      FIG. 4D  is a detail view of the gearbox assembly of  FIG. 4A . 
           [0023]      FIG. 5A  is a perspective view of a thruster according to another embodiment. 
           [0024]      FIG. 5B  is a cross-sectional view of the thruster of  FIG. 5A . 
           [0025]      FIG. 6  is a perspective view of a pipe jaw according to another embodiment. 
           [0026]      FIG. 7  is a detail view of a rotational actuator according to another embodiment. 
       
    
    
       [0027]    To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation. 
       DETAILED DESCRIPTION 
       [0028]    Embodiments described herein provide apparatus for supporting and extending well bore components into a bore hole.  FIGS. 1A and 1B  are isometric views of an apparatus  100  according to one embodiment. The apparatus  100  is of a type generally referred to as a “top drive” for manipulating well bore components such as drill strings and casings extended into a well. The apparatus  100  comprises a plurality of supports  102  that support the apparatus  100  from a swing mount  104 . The swing mount  104  enables the apparatus  100  to hang vertically over the well bore when manipulating downhole components. The apparatus  100  further comprises a motor assembly  106 , a gearbox assembly  108  coupled to the motor assembly  106 , and a workpiece handling assembly  110 . The gearbox assembly  108  couples torque from the motor assembly  106  to a stub  126 , which in turn couples to a workpiece, such as a piece of drill pipe or casing, for attachment to a downhole string. 
         [0029]    The workpiece handling assembly  110  comprises a pair of elevator supports  114  that hang from hooks  116  coupled to a swivel  128 . An elevator (not shown) is hung from the supports  114  and lifts workpieces for coupling to the stub  126 . The motor assembly  106 , through the gearbox assembly  108 , turns the stub  126  to engage a workpiece, and then turns the workpiece to engage with, or disengage from, a downhole string. A pair of thrusters  118  swing the elevator support  114  to position the elevator with respect to a workpiece to be lifted, or to position the elevator with respect to the apparatus  100 . The thrusters  118  may be continuously extended or retracted to any position within their stroke to achieve differential positioning of the elevator. When fully retracted, the thrusters  118  may be configured to locate the elevator in an operating position away from the rotating drill string. The thrusters  118  are continuously extendable from a fully retracted position to a fully extended position, so the elevator may be positioned at any location between the fully retracted (i.e. operating) position and the fully extended position. For example, the elevator may be positioned to access a fingerboard (i.e. pipe storage rack) or mousehole (i.e. staging location for the next joint of drill pipe or casing), and the elevator may be positioned to align a length of drill pipe or casing over the drill hole. The continuous positioning capability of the thrusters  118  allows precision positioning of the elevators for maximum effectiveness. 
         [0030]      FIG. 1B  shows another viewpoint of the apparatus  100 . The workpiece handling assembly  110  further comprises a gripper assembly  120  for holding a workpiece in place and preventing rotation of the workpiece as the stub  126  engages with the workpiece. The gripper assembly  120  comprises a frame  122  to which a gripper  124  is coupled The frame  122  supports the gripper  124  and allows differential positioning of the gripper  124  with respect to the stub  126 . 
         [0031]    Referring again to  FIG. 1A , each of the supports  102  has a collar portion  130  that at least partially surrounds a housing  132  of the gearbox assembly  108  at a lower portion thereof, supporting the gearbox assembly  108  and motor assembly  106 . The collar portion  130  spreads the load on the housing  132  from lifting drill joints, strings, and casings. 
         [0032]      FIG. 2  is a cross-sectional view of the integrated motor assembly  106  and gearbox assembly  108  of the apparatus  100 . The motor assembly  106  comprises a motor  200  with a central conduit  202  formed therein. A motor shaft  204  extends through the conduit  202  emerging from the motor  200  and entering the gearbox assembly  108  to engage a driver gear  206 . A drilling fluid conduit  208  is disposed through the motor shaft  204  to deliver drilling fluid through the motor assembly  106 , gearbox assembly  108 , and stub  126  into the drill string. The motor  200  further comprises a stator  210  and rotor  230 . In most embodiments, the motor  200  is a standard variable speed motor, any suitable variant of which may be used. 
         [0033]    The housing  132  of the gearbox assembly  108  forms an enclosure  214  in which the gearbox components are disposed. A lid plate  216  defines an upper extent of the gearbox assembly  108 . The gearbox assembly comprises a planetary gear set  218  that transmits torque from the motor  200  down to the stub  126 . The planetary gear set  218  comprises a plurality of planet gears  220  in registration with the driver gear  206 , also referred to as a “sun gear”, and with a peripheral gear  222  coupled to the housing  132 . Each of the planet gears  220  is coupled to a torque member  224  by a spindle  226  that seats in an opening  228  in the torque member  224 . Each planet gear  220  rotates about the spindle  226  and applies a shear force to the spindle  226  as it rolls along the peripheral gear  222 , which may be an annular gear. The spindle  226  applies torque to the torque member  224 . 
         [0034]    The drilling fluid conduit  208  extends through the driver gear  206  and seat in an opening  250  in the torque member  224 . Drilling fluid is delivered through the torque member  224  to the stub  126 . The drilling fluid conduit  208  comprises a plurality of longitudinal ribs, not visible in the cross-sectional view of  FIG. 2 , that mate with longitudinal grooves in the opening  250  of the torque member  224  so the drilling fluid conduit  208  rotates with the torque member  224  at a different angular velocity from the motor shaft  204 . This reduces surface velocity for rotary seals deployed along the drilling fluid conduit  208 . 
         [0035]    The drill string coupled to the stub  126  shifts in a longitudinal direction and in all radial directions of the gearbox assembly  108  during operation. For this reason, various thrust bearings are provided to protect the gearbox assembly  108  from stresses due to this motion. A first thrust bearing  232  provides support to an upper portion of the torque member  224 , while a second thrust bearing  234 , which may be plurality of thrust bearings as shown in  FIG. 2 , provides support to a lower portion of the torque member  224 . The first thrust bearing  232  generally rides against the gearbox housing  132 , and may comprise rollers or sliders of any convenient type to facilitate frictionless motion between the first thrust bearing  232  and the gearbox housing  132 . The second thrust bearing  234  rides against a spacer  236  that maintains position of the second thrust bearing (or bearings)  234  relative to the first thrust bearing  232  and the gearbox housing  132 . The second thrust bearing  234  may rest on a third thrust bearing  238 , which generally provides longitudinal support to the torque member  224  through the second thrust bearing  234  and the spacer  236 . Alignment of the torque member  224  with the various components of the apparatus  100  is thus maintained during operation. 
         [0036]    The motor shaft  204  has a brake assembly  242  that comprises a disk coupled to the shaft  204 , one or more shoes  246 , a friction member  244 , and a stop  248 . The friction member  244  is a thrust member that urges the shoes  246  against the disk  240 . The stop  248  ensures that as the thrust member urges the shoes  246  against the disk  240 , any deformation of the disk  240  away from the frictional force of the shoes  246  is minimized, such that friction develops along the disk  240 . In operation, under some circumstances, rotation of the motor shaft  204  may need to be stopped. For example, should the motor fail, torque in the drill string may uncouple joints from the drill string, resulting in expensive downtime to rebuild the drill string. The brake assembly  242  will prevent rotation of the motor shaft  204 , and by extension the gearbox assembly  108  and the drill string coupled to the stub  126 , to prevent unwinding the drill string. The friction member  244  may be extended toward the shoes  246  by hydraulic, electromechanical, or preferably pneumatic means. Use of a brake assembly with a disk coupled to the rotor shaft and extending outward to the friction member increases lever arm available to the friction member for controlling rotation of the shaft, reducing wear on the braking assembly. 
         [0037]      FIG. 3A  is a cross-sectional view of the motor assembly  106 . The motor  200  is aligned along a longitudinal axis of the apparatus  100 . The rotor  230  rotates the shaft  204  which is coupled to the rotor  230  and extends beyond both ends of the rotor  230 . The driver gear  206  is coupled to the shaft by fasteners  308 . The drilling fluid conduit  208  couples to a gooseneck  304  at a first end and extends through the rotor  230 , the shaft  302 , and the driver gear  206  to deliver drilling fluids to the drill string. 
         [0038]    Drilling fluids are often provided under extreme pressure, sometimes exceeding 7,500 psi. The gooseneck  304  is therefore sealed to the drilling fluid conduit  208  by a seal block  310 . To monitor for failure of the drilling fluid conduit  208  within the motor assembly  106 , an annulus  306  is provided between the drilling fluid conduit  208  and the shaft  302 , and one or more pressure sensors  312  is coupled to the annulus  306 . The annulus  306  is sealed by the seal block  310  at a first end, and by a seal  314  between the shaft  204  and the drilling fluid conduit  208  at a second end. A pressure relief pathway  315  may be provided to further protect any of the seals at either end of the shaft  204 . Any failure of the drilling fluid conduit  208  inside the shaft  204  may result in a large pressure spike in the annulus  306 , which can be detected by the pressure sensor  312  and relieved by the pressure relief pathway  315 . Any number of pressure sensors  312  may be provided, according to the needs of different embodiments. The pressure relief pathway  315  may be coupled to any suitable pressure relief device, such as a pressure relief valve. 
         [0039]      FIG. 3B  is a detail view of a seal block  310  according to one embodiment. The gooseneck  304  couples to the drilling fluid conduit  208  by an upper coupling  348  and a lower coupling  350 . The lower coupling  350  encloses a seal assembly that comprises a plurality of seals and seal rings, with portals for placing pressuring sensors in fluid communication with the various seal points to monitor for successive seal failures. The seal assembly seals the annulus  306  in the event of failure of the drilling fluid conduit, and provides monitoring of the seals to detect seal failure. As noted above, the annulus  306  may further be monitored by a pressure sensor such as the pressure sensor  315  of  FIG. 3A . 
         [0040]    A first o-ring  326  seals a seam between a first seal ring  322  and the drilling fluid conduit  208 . The first o-ring  326  is held by a second seal ring  328  and a third seal ring  338 , which cooperatively define a first o-ring channel  356 . The third seal ring  338  comprises a first portal  334  for placing a pressure sensor in fluid communication with the first o-ring channel  356  to monitor for failure of the first o-ring  326 . A fourth seal ring  342 , along with the third seal ring  338 , cooperatively defines a second o-ring channel  352 , in which a second o-ring  336  provides a second seal against the drilling fluid conduit  208 . The fourth seal ring  342  comprises a second portal  344  for placing a second pressure sensor in fluid communication with the second o-ring channel  352  to monitor for failure of the second o-ring  336 . Should the first o-ring  326  fail, the seam between the second and third seal rings  328  and  338  is sealed by a third o-ring  330 . The seam between the third seal ring  338  and the fourth seal ring  342  is sealed on either side of the first portal  334  by a fourth o-ring  358  and a fifth o-ring  340 . Additional safety seals  346  are provided in the fourth seal ring  342 . The sealing system of  FIG. 3B  provides redundant sealing of the annulus  306  and annunciation of seal failures such that economically attractive opportunities may be taken to replace the seal block  310 . 
         [0041]    In one aspect, some embodiments provide a method of providing drilling fluid to a wellbore, the method comprising providing a conduit from a drilling fluid pump to the down hole drill string. The conduit may be enclosed to form an isolation space around at least a portion of the conduit, which can be monitored for leakage of drilling fluids from the conduit. Any type of sensor may be deployed to monitor the isolation space, such as pressure sensors, temperature sensors, conductivity sensors, and so on. In one embodiment, a pressure sensor is coupled to the isolation space to monitor for pressure spikes from drilling fluids leaking into the space. Multiple sensors may be coupled to the isolation space to provide redundant monitoring in case one sensor fails. The sensors may all be of the same type, or of different types. In one embodiment, a plurality of pressure sensors is coupled to the isolation space to provide redundant monitoring. 
         [0042]    In other embodiments, the drilling fluid conduit  208  may be surrounded by a plurality of isolation spaces. The drilling fluid conduit  208  may be formed with ribs that contact an inner surface of the motor shaft  204  at seal surfaces, forming individual isolation spaces that may be individually monitored, if desired, and provide further sealing redundancy. Such further redundancy may provide further protection for the bottom seal  314 , for example. Still other embodiments may comprise a drilling fluid conduit  208  with longitudinal ribs extending the full length of the conduit  208 . The ribs may improve strength of the conduit  208  at high pressures, enabling drilling fluid pressures within the conduit exceeding 10,000 psi for deeper well bores. 
         [0043]    The driver gear  206  of the motor assembly  106  is positioned at the center of the gearbox assembly  108  and meshes with the planet gears  220  to drive rotation of the torque member  224 .  FIG. 4A  is a cross-sectional view of the gearbox assembly  108  and the swivel  128 . The swivel  128  comprises a casing  452  and a load collar  446  inside the casing  452 . The load collar  446  is coupled to the housing  212  of the gearbox assembly  108  by a first plurality of inserts  448  that fit into grooves in the housing  212  and the collar  446 . The casing  452 , is in turn coupled to the collar  446  by a second plurality of inserts  450  that fit into grooves in the collar  446 . A shoulder of the casing  452  rests on the second plurality of inserts  450 . The inserts  448  and  450  ensure that when a drill string is suspended from an elevator hanging from the sides of the swivel  128 , the load from the drill string, which may in some cases exceed one million pounds, is not concentrated on fasteners such as bolts. The inserts  448  and  450  distribute the load around the periphery of the housing  212  and collar  446  and among the load points thereof. 
         [0044]    The collar  446  defines an internal space  456  of the swivel  128  that provides a longitudinal degree of freedom for the stub  126  to move independently from the rest of the apparatus  100 . The stub  126  is coupled to the torque member  224  by a spool  434  fastened to the torque member  224  by fasteners. A sleeve  436  couples to the spool  434  at an upper end and to the stub  126  at a lower end. The sleeve  436  may move within the internal space  456  of the collar  446  if needed to decouple longitudinal movement of the stub from the apparatus  100 . An extension  438  mates with the sleeve  436  to form a chamber  440  between the sleeve and the extension  438 . A portal  442  allows application of pressurized gas, such as air, into the chamber  440 . The force of the pressurized gas raises the sleeve  436  within the collar  446 , lifting the stub  126  and any pipe attached thereto. Such movement may be useful to reduce longitudinal force on pipe joints when engaging or disengaging them. The reduced stress on the thread joints reduces the opportunity for damaging threads. The sleeve  436  may move upward to occupy the space  444  between the upper end of the sleeve  436  and a bottom plate  458  of the housing  212 . 
         [0045]      FIG. 4B  is a perspective view of the torque member  224 . The openings  228  into which the spindles  226  seat are located a distance “D” from a central axis of the torque member  224 , the distance D depending on the desired torque transmission from the motor to the pipe joints and strings below. The planet gears  220  are sized to mate with the driver gear  206  at the center of the gearbox assembly  108  and with a peripheral gear  222  disposed about the periphery of the housing  212 . 
         [0046]    The torque member  224  comprises a disc-like lever portion  402  that provides the lever arm for the torque member  224 , and a conduit portion  404  that extends away from the lever portion  402  and provides passage for drilling fluids through the gearbox assembly  108 . The lever portion  402  comprises a plurality of recesses  406 , each of which has a scallop  408  formed therein. Each scallop  408  is formed with a curved surface facing toward the planetary gear mechanism of the gearbox assembly  108  and toward the direction of rotation of the torque member  224 . As the driver gear  206  rotates the planet gears  220 , the planet gears  220  roll along the peripheral gear  222 , causing the torque member  224  to rotate within the gearbox assembly  108 . The housing  212  is generally filled with a lubricant through which the various moving parts of the gearbox assembly  108  move. As the torque member  224  rotates through the lubricant, the scallops  408  direct a flow of lubricant toward the planetary gear set  218 , resulting in circulation of lubricant through the gearbox assembly  108 . 
         [0047]    The torque member  224  further comprises a plurality of spacers  410  coupled to an upper surface  412  of the torque member  224 . The spacers  410  provide a support plane for the lid plate  216  of the gearbox assembly  108  that is above an upper surface of the planet gears  220 , such that the planet gears  220  do not contact the lid plate  216  during operation. The spacers  410  are located in the interstitial spaces between the planet gears  220 , and each spacer  410  has a curved surface  460  that follows the curvature of a neighboring planet gear  220  to direct a flow of lubricant to the mating surfaces of the planet gear  220  and the peripheral gear  226 . In some embodiments, the curved surface  460  may be angled instead. Each spacer  410  is fastened to the torque member  224  by a plurality of fasteners  414 . 
         [0048]      FIG. 4C  is a top view of the gearbox assembly  108  with top plates removed to expose internal components of the gearbox assembly  108 . The spacers  410  are shown in relation to the planet gears  220 , with a gap  462  formed by the curved surface of a spacer  410  and the outer extent of a planet gear  220 . The gap  462  directs lubricant to flow toward the mating surfaces of the planet gears  220  and the peripheral gear  222 . The recesses  406  of the torque member  224  are also shown in relation to the planet gears  220 . Each planet gear  220  is located in a position such that openings  416  formed in each planet gear  220  register with the scallops  408  of the torque member  224 . The scallops  408  direct a flow of lubricant toward the planet gears  220 , and the openings  416  in the planet gears  220  facilitate flow of the lubricant to the upper surface of the planet gears  220  and to the lid plate  216  of the gearbox assembly  108 . 
         [0049]    Each recess  406  has a cutout portion  428  in which the scallop  408  is formed. Each of the scallops  408  in the embodiment of  FIG. 4B  has a curved surface shaped like a portion of a cylinder. The cylinder has an axis of curvature that is parallel to a first wall  430  of the cutout portion  428  and perpendicular to a second wall  432  of the cutout portion  428 . The second wall  432  has a dimension “d” that is substantially similar to the radius of curvature of the surface of the scallops  408 . In alternate embodiments, the scallops  408  may have a cylindrical surface with a radius of curvature that is more or less than the dimension “d” of the second wall  432 . The scallop may also have a surface that is not curved, but inclined with respect to the upper surface  412  of the torque member  224 , forming a corner with the second wall  432 . 
         [0050]    The first wall  430  of each recess  406  forms an angle α with respect to a radius “R” of the torque member  224  in the embodiment of  FIG. 4B . The angle α may be selected for any reason of manufacturability or operability of the apparatus  100 , but using an angled recess  406  may facilitate spacing and orientation of various components, such as for example the spacers  410 . Additionally, the angled recess  406  provides a radial component to the induced motion of the lubricant toward the periphery of the torque member  224 , directing more of the lubricant through the openings  416  in the planet gears. 
         [0051]    The openings  416  through the planet gears  220  may be inclined with respect to a central axis of each planet gear  220 . The arrow  420  indicates the direction of travel of a planet gear  220  in an exemplary embodiment. The arrows  422  indicate the direction of rotation of the planet gear  220  as it moves along the direction of arrow  420 . The inclination of the openings  416  is generally reverse to the direction of rotation of the planet gear  220 . 
         [0052]      FIG. 4D  is a detailed cross-sectional view of the lever portion  402  of the torque member  224  in relation to a planet gear  220 . The opening  416  through the planet gear  224  forms an angle θ with respect to a central axis  418  of the spindle  226 . The arrow  424  indicates the direction of rotation of the planet gear  220 , and the arrow  426  indicates the direction of rotation of the torque member  224 . The central axis of each opening  416 , projected along two component coordinate axes, one of which is parallel to the central axis  418  of the spindle, has a component parallel to a tangent of the circle defined by the ends of the teeth of the planet gears  220 . Thus, each of the openings  416  “leans” in a direction tangent to the rotation of its planet gear  220 , but in a direction opposite the direction of rotation. This orientation of the openings  416  with respect to the scallops  408  propagates the pumping of lubricant up from the scallop  408 , into the opening  416 , and up through the opening  416  and out the top thereof. 
         [0053]    The central axis of each opening  416 , projected along two component coordinate axes, one of which is parallel to the central axis  418  of the spindle, has a component parallel to a tangent of the circle defined by the ends of the teeth of the planet gears  220 . Thus, each of the openings  416  “leans” in a direction tangent to the rotation of its planet gear  220 , but in a direction opposite the direction of rotation. 
         [0054]    Referring again to  FIG. 1B , lubricant is provided to the gearbox assembly  108  by a pump  134 , which may be coupled to the apparatus  100  at any point, such as the gearbox assembly  108  as shown in  FIG. 1B . The pump  134  may couple to the gearbox assembly  108  at any point along the housing  212  or the lid plate  216  to deliver lubricant into the enclosure  214 . Should the pump  134  fail, the lubricant circulation features of the torque member  224  and planet gears  220  will continue circulating lubricant throughout the gearbox assembly  108 , so the apparatus  100  may be operated for a time without the pump  134  until an economically advantageous opportunity is found to repair the pump  134 . 
         [0055]    In alternate embodiments, blades may be formed along the edge of the lever portion  402 . The blades may be attached or fastened to the lever portion or formed as an integral part thereof. Blades may also be formed on the upper surface  412  of the lever portion  402 . A wall portion of the spacers  410  facing in the direction of rotation of the torque member  224  may also be inclined to any desired degree to facilitate circulation of lubricant through the gearbox assembly  108 . 
         [0056]    The apparatus  100  includes a means for differentially locating an elevator with respect to the apparatus  100 . One such means comprises positioning elevator supports coupled to the apparatus  100  using continuously extendable linear actuators.  FIG. 5A  is a side view of a linear actuator that may be used to differentially position an elevator with respect to the apparatus  100 . The linear actuator of  FIG. 5A  comprises an outer tube  502  and an inner tube  504 . The inner tube moves to any position within a range of extension. An actuator  506  moves the inner tube  504  with respect to the outer tube  502 . Connectors  510  at either end may be used to couple the linear actuator  500  to the apparatus  100 , the connector  510  at a first end being coupled to a stationary point or frame of the apparatus  100 , and a second end being coupled to elevator supports coupled to the apparatus  100 . 
         [0057]    In one embodiment, the linear actuator  500  may be used as a thruster  118 .  FIG. 5B  is a cross-sectional view of the linear actuator  500  of  FIG. 5A . A rod  512  is disposed within a bore  518  of the inner tube  504 . The rod  512  is threaded with a bushing  514  disposed in the inner tube  504 . The actuator  506  is a rotational actuator that rotates the rod  512  within the threaded bushing  514  to extend or retract the inner tube  504 . A bearing  520  ensures the rod  512  travels within the bore  518  without contacting the inner surface of the bore  518 . A cap  516  prevents the threaded bushing  514  from contacting the actuator  506  when the inner tube  504  is fully retracted. The actuator  506  of  FIGS. 5A and 5B  is pneumatically driven by a pneumatic source  522  coupled to the actuator  506  by a conduit  524 . In other embodiments, hydraulic or electromechanical actuators may be used to turn the rod  512 . Additionally, other types of linear actuators, such as hydraulic or pneumatic piston actuators, may be used. 
         [0058]      FIG. 6  is a perspective view of the gripper assembly  120  of  FIG. 1A . The gripper assembly  120  comprises a pair of grippers  602 , each of which is actuated by a pair of linear actuators  604 . The linear actuators  604  are pivotably coupled to a base member  606  at a peripheral portion thereof. Each gripper  602  is also coupled to a central portion of the base member  606  by a flexible connector  608 . The central portion of the base member  606  comprises a friction member  610 . The flexible connectors  608  are coupled to the friction member  610  in a way that a surface of the friction member  610  contacts a pipe when the pipe is disposed in the gripper assembly  120 . 
         [0059]    A pair of pivot rods  614  couples each side of the base member  606  to a positioner  612  that positions the gripper assembly  120  in a longitudinal direction. A positioning rod  616  is coupled to the positioner  612  and to a linear actuator (not shown) of any convenient type to raise and lower the gripper assembly  120  as needed. A thruster  618  is coupled to the base member  606  and to a frame offset  620 , which is coupled to the positioner  612 . 
         [0060]    In operation, the positioning rod  616  moves the gripper assembly  120  to the desired longitudinal position. The thruster  618  extends or retracts to adjust the radial position of the gripper assembly  120 . Once properly positioned, the linear actuators  604  extend, wrapping the flexible connectors  608  around the pipe joint to be addressed by the apparatus  100 . The positioning rod  616  and thruster  618  deploy to align the pipe joint with the stub  126  of the gearbox assembly  108  ( FIGS. 1 ,  2 ,  4 A). When the pipe physically contacts the stub, the motor assembly  106  rotates the stub  126  to thread into the pipe joint. When the threads engage, the motor assembly  106  rotates the pipe joint within the gripper assembly  120 . The surface of the friction member  610  contacting the pipe joint develops a frictional force against the pipe joint, which drives the pipe joint against one or the other of the flexible connectors  608  and grippers  602  in a locking manner. The gripper assembly  120  may thus be said to be “self-locking” under torque from the motor assembly  106 . 
         [0061]    In one embodiment the flexible connectors  608  may be roller chains. In other embodiments, the flexible connectors  608  may comprise articulated connectors of another type, for example a plurality of rods coupled with pins. In other embodiments, the flexible connectors  608  may comprise one or more cables. In some embodiments, the flexible connectors  608  are coupled to the friction member  610  at a peripheral portion thereof, and a central portion of the friction member  610  extends away from the base member  606  to provide a substantially flat surface for contacting the pipe. In some embodiments, the flat surface of the friction member  610  positioned for contacting the pipe is serrated for better engagement with the pipe surface. In some embodiments, the flexible connectors  608  may also have serrated contact surfaces for improved engagement with the pipe surface. 
         [0062]    The pipe handler is configured to rotate for best access to processing positions.  FIG. 7  is a detail view of a rotational actuator  700  according to another embodiment. The rotational actuator  700  comprises a rotational coupling  704  coupled to a drive unit  710 . The rotational coupling  704  comprises a plurality of teeth  712 , each of which is tipped with a roller  706 . The rollers extend beyond the ends of the teeth  712  to present a rolling contact surface. The rollers engage with recesses  708  of a sprocket  702  coupled to the swivel  128  of the pipe handler. The rotational actuator  700  is mounted to the housing  132  of the gearbox assembly  108  ( FIG. 1A ) to provide a stationary reference for rotating the swivel  128 . As the rotational coupling  704  rotates, a roller  706  enters engagement with a recess  708  of the sprocket  702 . The roller  706  rolls along the internal surface of the recess  708 , providing torque to the sprocket  702  while minimizing friction along the surface of the recess  708 . Wear on the sprocket  702  is thus reduced, while wear on the rollers  706  is easily remedied by replacing the rotational actuator  700  at a convenient time. 
         [0063]    In general, o-rings used in the apparatus  100  comprise a compliant material, such as a polymeric material. The o-rings may have a circular cross-section, or they may have a different cross-sectional shape, if convenient. For example, sealing members may be used that have a square or rectangular cross-sectional shape, an oval or ellipsoidal cross-sectional shape, a polygonal cross-sectional shape (e.g. triangular, hexagonal, etc.), or any other convenient regular or irregular cross-sectional shape (e.g. star-shaped, plus-shaped, lobed, spiraled, etc.). Structural components of the apparatus  100  generally comprise steel, such as any carbon or stainless steel, or any desired alloy. 
         [0064]    While the foregoing is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof.