Patent Publication Number: US-10309166-B2

Title: Genset for top drive unit

Description:
BACKGROUND OF THE DISCLOSURE 
     Field of the Disclosure 
     The present disclosure generally relates to a genset for a top drive unit. 
     Description of the Related Art 
     A wellbore is formed to access hydrocarbon-bearing formations (e.g., crude oil and/or natural gas) or for geothermal power generation by the use of drilling. Drilling is accomplished by utilizing a drill bit that is mounted on the end of a drill string. To drill within the wellbore to a predetermined depth, the drill string is often rotated by a top drive on a surface rig. After drilling to a predetermined depth, the drill string and drill bit are removed and a section of casing is lowered into the wellbore. An annulus is thus formed between the string of casing and the formation. The casing string is hung from the wellhead. A cementing operation is then conducted in order to fill the annulus with cement. The casing string is cemented into the wellbore by circulating cement into the annulus defined between the outer wall of the casing and the borehole. The combination of cement and casing strengthens the wellbore and facilitates the isolation of certain areas of the formation behind the casing for the production of hydrocarbons. 
     Top drives are equipped with a motor for rotating the drill string. The quill of the top drive is typically threaded for connection to an upper end of the drill pipe in order to transmit torque to the drill string. The top drive may also have various accessories to facilitate drilling. For adapting to the larger casing string, the drilling accessories are removed from the top drive and a casing running tool is added to the top drive. The casing running tool has a threaded adapter for connection to the quill and grippers for engaging an upper end of the casing string. It would be useful to have sensors on the casing running tool to monitor operation thereof. Transmitting electricity from a stationary power source to the rotating casing running tool is problematic. Electrical slip rings are not practical because the top drive operates in a harsh environment where components are exposed to shock and vibration. Moreover, because slip rings can spark during operation, they require complex measures, such as flameproof housings or purging with air for use in the explosive atmospheres that sometime occur during casing running operations. Slip rings also utilize brushes requiring frequent replacement. It would be beneficial to provide a local source of electrical power for the various accessories that facilitate drilling. 
     SUMMARY OF THE DISCLOSURE 
     The present disclosure generally relates to a genset for a top drive unit. In one embodiment, a system includes an accessory tool selected from a group consisting of a casing unit, a cementing unit, and a drilling unit; and a genset mounted to the accessory tool and comprising: a fluid driven motor having an inlet and an outlet for connection to a control swivel of the system; an electric generator connected to the fluid driven motor; a manifold having an inlet for connection to the control swivel and an outlet connected an accessory tool actuator; and a control unit in communication with the electric generator and the manifold and comprising a wireless data link. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, 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 disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments. 
         FIG. 1  illustrates a top drive system, according to one embodiment of the present disclosure. 
         FIG. 2A  illustrates a motor unit of the top drive system.  FIG. 2B  illustrates a drilling unit of the top drive system. 
         FIGS. 3A and 3B  illustrate a casing unit of the top drive system. 
         FIG. 4  illustrates a genset of the casing unit. 
         FIG. 5  is a control diagram of the top drive system in a drilling mode. 
         FIGS. 6, 7A, 7B, 8A, and 8B  illustrate shifting of the top drive to the drilling mode. 
         FIG. 9  illustrates the top drive system in the drilling mode. 
         FIG. 10  illustrates shifting of the top drive system from the drilling mode to the casing mode. 
         FIGS. 11 and 12A  illustrate extension of a casing string using the top drive system in the casing mode.  FIG. 12B  illustrates running of the extended casing string into the wellbore using the top drive system. 
         FIGS. 13A and 13B  illustrate a cementing unit of the top drive system. 
         FIG. 14  illustrates cementing of the casing string using the top drive system in a cementing mode. 
         FIG. 15  illustrates cementing of the casing string using an alternative cementing unit, according to another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a top drive system  1 , according to one embodiment of the present disclosure. The top drive system  1  may be a modular top drive system and may include a linear actuator  1   a  ( FIG. 8A ), several accessory tools (e.g., casing unit  1   c , a drilling unit  1   d , and a cementing unit  1   s ) a pipe handler  1   p , a unit rack  1   k , a motor unit  1   m , a rail  1   r , and a unit handler  1   u . The unit handler  1   u  may include a post  2 , a slide hinge  3 , an arm  4 , a holder  5 , a base  6 , and one or more actuators (not shown). One or more of the accessory tools may include a genset  51  (sometimes referred to as an engine-generator set, and typically including an electric generator and an engine or motor mounted together to form a single piece of equipment). 
     The top drive system  1  may be assembled as part of a drilling rig  7  by connecting a lower end of the rail  1   r  to a floor  7   f  or derrick  7   d  of the rig and an upper end of the rail to the derrick  7   d  such that a front of the rail is adjacent to a drill string opening in the rig floor. The rail  1   r  may have a length sufficient for the top drive system  1  to handle stands  8   s  of two to four joints of drill pipe  8   p . The rail length may be greater than or equal to twenty-five meters and less than or equal to one hundred meters. The rail  1   r  may be a monorail (shown) or the top drive system may include twin rails instead of the monorail  1   r.    
     The base  6  may mount the post  2  on or adjacent to a structure of the drilling rig  7 , such as a subfloor structure, such as a catwalk (not shown) or pad. The unit rack  1   k  may also be located on or adjacent to the rig structure. The post  2  may extend vertically from the base  6  to a height above the rig floor  7   f  such that the unit handler  1   p  may retrieve any of the units  1   c,d,s  from the rack  1   k  and deliver the retrieved unit to the motor unit  1   m.    
     The arm  4  may be connected to the slide hinge  3 , such as by fastening. The slide hinge  3  may be transversely connected to the post  2 , such as by a slide joint, while being free to move longitudinally along the post. The slide hinge  3  may also be pivotally connected to a linear actuator (not shown), such as by fastening. The slide hinge  3  may longitudinally support the arm  4  from the linear actuator while allowing pivoting of the arm relative to the post  2 . The unit handler  1   u  may further include an electric or hydraulic slew motor (not shown) for pivoting the arm  4  about the slide hinge  3 . 
     The linear actuator may have a lower end pivotally connected to the base  6  and an upper end pivotally connected to the slide hinge  3 . The linear actuator may include a cylinder and a piston disposed in a bore of the cylinder. The piston may divide the cylinder bore into a raising chamber and a lowering chamber and the cylinder may have ports formed through a wall thereof and each port may be in fluid communication with a respective chamber. Each port may be in fluid communication with a manifold  60   m  of a hydraulic power unit (HPU)  60  (both in  FIG. 5 ) via a control line (not shown). Supply of hydraulic fluid to the raising port may move the slide hinge  3  and arm  4  upward to the rig floor  7   f . Supply of hydraulic fluid to the lowering port may move the slide hinge  3  and arm  4  downward toward the base  6 . 
     Alternatively, the linear actuator may include an electro-mechanical linear actuator, such as a motor and lead screw or pinion and gear rod, instead of the piston and cylinder assembly. 
     The arm  4  may include a forearm segment, an aft-arm segment, and an actuated joint, such as an elbow, connecting the arm segments. The holder  5  may be releasably connected to the forearm segment, such as by fastening. The arm  4  may further include an actuator (not shown) for selectively curling and extending the forearm segment and relative to the aft-arm segment. The arm actuator may have an end pivotally connected to the forearm segment and another end pivotally connected to the aft-arm segment. The arm actuator may include a cylinder and a piston disposed in a bore of the cylinder. The piston may divide the cylinder bore into an extension chamber and a curling chamber and the cylinder may have ports formed through a wall thereof and each port may be in fluid communication with a respective chamber. Each port may be in fluid communication with the HPU manifold  60   m  via a control line (not shown). Supply of hydraulic fluid to the respective ports may articulate the forearm segment and holder  5  relative to the aft-arm segment toward the respective positions. 
     Alternatively, the arm actuator may include an electro-mechanical linear actuator, such as a motor and lead screw or pinion and gear rod, instead of the piston and cylinder assembly. Alternatively, the actuated joint may be a telescopic joint instead of an elbow. Additionally, the holder  5  may include a safety latch for retaining any of the units  1   c,d,s  thereto after engagement of the holder therewith to prevent unintentional release of the units during handling thereof. Additionally, the holder  5  may include a brake for torsionally connecting any of the units  1   c,d,s  thereto after engagement of the holder therewith to facilitate connection to the motor unit  1   m.    
     Referring to  FIG. 8A , the pipe handler  1   p  may include a drill pipe elevator  9  ( FIG. 9 ), a pair of bails  10 , a link tilt  11 , and a slide hinge  12 . The slide hinge  12  may be transversely connected to the front of the rail  1   r  such as by a slide joint, while being free to move longitudinally along the rail. Each bail  10  may have an eyelet formed at each longitudinal end thereof. An upper eyelet of each bail  10  may be received by a respective pair of knuckles of the slide hinge  12  and pivotally connected thereto, such as by fastening. Each bail  10  may be received by a respective ear of the drill pipe elevator  9   d  and pivotally connected thereto, such as by fastening. 
     The link tilt  11  may include a pair of piston and cylinder assemblies for swinging the elevator  9  relative to the slide hinge  12 . Each piston and cylinder assembly may have a coupling, such as a hinge knuckle, formed at each longitudinal end thereof. An upper hinge knuckle of each piston and cylinder assembly may be received by the respective lifting lug of the slide hinge  12  and pivotally connected thereto, such as by fastening. A lower hinge knuckle of each piston and cylinder assembly may be received by a complementary hinge knuckle of the respective bail  10  and pivotally connected thereto, such as by fastening. A piston of each piston and cylinder assembly may be disposed in a bore of the respective cylinder. The piston may divide the cylinder bore into a raising chamber and a lowering chamber and the cylinder may have ports formed through a wall thereof and each port may be in fluid communication with a respective chamber. Each port may be in fluid communication with the HPU manifold  60   m  via a respective control line  66   b,c  ( FIG. 5 ). Supply of hydraulic fluid to the raising port may lift the elevator  9  by increasing a tilt angle (measured from a longitudinal axis of the rail  1   r ). Supply of hydraulic fluid to the lowering port may drop the elevator  9  by decreasing the tilt angle. 
     The drill pipe elevator  9  may be manually opened and closed or the pipe handler  1   p  may include an actuator (not shown) for opening and closing the elevator. The drill pipe elevator  9  may include a bushing having a profile, such as a bottleneck, complementary to an upset formed in an outer surface of a joint of the drill pipe  8   p  adjacent to the threaded coupling thereof. The bushing may receive the drill pipe  8   p  for hoisting one or more joints thereof, such as the stand  8   s . The bushing may allow rotation of the stand  8   s  relative to the pipe handler  1   p . The pipe handler  1   p  may deliver the stand  8   s  to a drill string  8  where the stand  8   s  may be assembled therewith to extend the drill string during a drilling operation. When connected to the motor unit  1   m , the pipe handler  1   p  may be capable of supporting the weight of the drill string  8  to expedite tripping of the drill string. 
     The linear actuator  1   a  may raise and lower the pipe handler  1   p  relative to the motor unit  1   m  and may include a gear rack, one or two pinions (not shown), and one or two pinion motors (not shown). The gear rack may be a bar having a geared upper portion and a plain lower portion. The gear rack may have a knuckle formed at a bottom thereof for pivotal connection with a lifting lug of the slide hinge  12 , such as by fastening. Each pinion may be meshed with the geared upper portion and torsionally connected to a rotor of the respective pinion motor. A stator of each pinion motor may be connected to the motor unit  1   m  and be in electrical communication with a motor driver  61  via a cable  67   b  (both shown in  FIG. 5 ). The pinion motors may share a cable via a splice (not shown). Each pinion motor may be reversible and rotation of the respective pinion in a first direction, such as counterclockwise, may raise the slide hinge  12  relative to the motor unit  1   m  and rotation of the respective pinion in a second opposite direction, such as clockwise, may lower the slide hinge relative to the motor unit. Each pinion motor may include a brake (not shown) for locking position of the slide hinge once the pinion motors are shut off. The brake may be disengaged by supply of electricity to the pinion motors and engaged by shut off of electricity to the pinion motors. 
     The linear actuator  1   a  may be capable of hoisting the stand  8   s . A stroke of the linear actuator  1   a  may be sufficient to stab a top coupling of the stand  8   s  into a quill  37  of the motor unit  1   m.    
     The unit rack  1   k  may include a base, a beam, two or more (three shown) columns connecting the base to the beam, such as by welding or fastening, and a parking spot for each of the units  1   c,d,s  (four spots shown). A length of the columns may correspond to a length of the longest one of the units  1   c,d,s , such as being slightly greater than the longest length. The columns may be spaced apart to form parking spots (four shown) between adjacent columns. The units  1   c,d,s  may be hung from the beam by engagement of the parking spots with respective couplings  15  ( FIG. 2B ) of the units. Each parking spot may include an opening formed through the beam, a ring gear, and a motor. Each ring gear may be supported from and transversely connected to the beam by a bearing (not shown) such that the ring gear may rotate relative to the beam. Each bearing may be capable supporting the weight of any of the units  1   c,d,s  and placement of a particular unit in a particular parking spot may be arbitrary. 
     Each motor may include a stator connected to the beam and may be in electrical communication with the motor driver  61  via a cable (not shown). A rotor of each motor may be meshed with the respective ring gear for rotation thereof between a disengaged position and an engaged position. Each ring gear may have an internal latch profile, such as a bayonet profile, and each coupling  15  may include a head  15   h  having an external latch profile, such as a bayonet profile. The bayonet profiles may each have one or more (three shown) prongs and prong-ways spaced around the respective ring gears and heads  15   h  at regular intervals. When the prongs of the respective bayonet profiles are aligned, the external prongs of the heads  15   h  may be engaged with the internal prongs of the respective ring gears, thereby supporting the units  1   c,d,s  from the beam. When the external prongs of the heads  15   h  are aligned with the internal prong-ways of the ring gears (and vice versa), the heads may be free to pass through the respective ring gears. 
     Alternatively, the latch profiles may each be threads or load shoulders instead of bayonets. Alternatively, the unit rack  1   k  and the motor unit  1   m  may each have slips, a cone, and a linear actuator for driving the slips along the cone (or vice versa) instead of the latch profiles. 
     Each coupling  15  may further include a neck  15   n  extending from the head  15   h  and having a reduced diameter relative to a maximum outer diameter of the head for extending through the respective beam opening and respective ring gear. Each coupling  15  may further include a lifting shoulder  15   s  connected to a lower end of the neck  15   n  and having an enlarged diameter relative to the reduced diameter of the neck and a torso  15   r  extending from the lifting shoulder  15   s  and having a reduced diameter relative to the enlarged diameter of the lifting shoulder. The torso  15   r  may have a length corresponding to a length of the holder  5  for receipt thereof and a bottom of the lifting shoulder  15   s  may seat on a top of the holder for transport from the unit rack  1   k  to the motor unit  1   m.    
     The unit rack  1   k  may further include a side bar for holding one or more accessories for connection to the forearm segment instead of the holder  5 , such as a cargo hook  16  and a pipe clamp  17 . The side bar may also hold the holder  5  when the unit handler  1   u  is equipped with one of the accessories. 
       FIG. 2A  illustrates the motor unit  1   m . The motor unit  1   m  may include one or more (pair shown) drive motors  18 , a becket  19 , a hose nipple  20 , a mud swivel  21 , a drive body  22 , a drive ring, such as drive gear  23 , a trolley  24  ( FIG. 5 ), a thread compensator  25 , a control, such as hydraulic, swivel  26 , a down thrust bearing  27 , an up thrust bearing  28 , a backup wrench  29  ( FIG. 8A ), a swivel frame  30 , a bearing retainer  31 , a motor gear  32  ( FIG. 5 ), and a latch  69  ( FIG. 5 ). The drive body  22  may be rectangular, may have thrust chambers formed therein, may have an inner rib dividing the thrust chambers, and may have a central opening formed therethrough and in fluid communication with the chambers. The drive gear  23  may be cylindrical, may have a bore therethrough, may have an outer flange  23   f  formed in an upper end thereof, may have an outer thread formed at a lower end thereof, may have an inner locking profile  23   k  formed at an upper end thereof, and may have an inner latch profile, such as a bayonet profile  23   b , formed adjacently below the locking profile. The inner bayonet profile  23   b  may be similar to the inner bayonet profile of the ring gears except for having a substantially greater thickness for sustaining weight of either the drill string  8  or a casing string  90  ( FIG. 12A ). The bearing retainer  31  may have an inner thread engaged with the outer thread of the drive gear  23 , thereby connecting the two members. 
     The drive motors  18  may be electric (shown) or hydraulic (not shown) and have a rotor and a stator. A stator of each drive motor  18  may be connected to the trolley  24 , such as by fastening, and be in electrical communication with the motor driver  61  via a cable  67   c  ( FIG. 5 ). The motors  18  may be operable to rotate the rotor relative to the stator which may also torsionally drive respective motor gears  32 . The motor gears  32  may be connected to the respective rotors and meshed with the drive gear  23  for torsional driving thereof. 
     Alternatively, the motor unit  1   m  may instead be a direct drive unit having the drive motor  18  centrally located. 
     Each thrust bearing  27 ,  28  may include a shaft washer, a housing washer, a cage, and a plurality of rollers extending through respective openings formed in the cage. The shaft washer of the down thrust bearing  27  may be connected to the drive gear  23  adjacent to a bottom of the flange thereof. The housing washer of the down thrust bearing  27  may be connected to the drive body  22  adjacent to a top of the rib thereof. The cage and rollers of the down thrust bearing  27  may be trapped between the washers thereof, thereby supporting rotation of the drive gear  23  relative to the drive body  22 . The down thrust bearing  27  may be capable of sustaining weight of a tubular string, such as either the drill string  8  or the casing string  90 , during rotation thereof. The shaft washer of the up thrust bearing  28  may be connected to the drive gear  23  adjacent to the bearing retainer  31 . The housing washer of the up thrust bearing  28  may be connected to the drive body  22  adjacent to a bottom of the rib thereof. The cage and rollers of the up thrust bearing  28  may be trapped between the washers thereof. 
     The trolley  24  may be connected to a back of the drive body  22 , such as by fastening. The trolley  24  may be transversely connected to a front of the rail  1   r  and may ride along the rail, thereby torsionally restraining the drive body  22  while allowing vertical movement of the motor unit  1   m  with a travelling block  73   t  ( FIG. 9 ) of a rig hoist  73 . The becket  19  may be connected to the drive body  22 , such as by fastening, and the becket may receive a hook of the traveling block  73   t  to suspend the motor unit  1   m  from the derrick  7   d.    
     Alternatively, motor unit  1   m  may include a block-becket instead of the becket  19  and the block-becket may obviate the need for a separate traveling block  73   t.    
     The hose nipple  20  may be connected to the mud swivel  21  and receive an end of a mud hose (not shown). The mud hose may deliver drilling fluid  87  ( FIG. 9 ) from a standpipe  79  ( FIG. 9 ) to the hose nipple  20 . The mud swivel  21  may have an outer non-rotating barrel  210  connected to the hose nipple  20  and an inner rotating barrel  21   n . The mud swivel  21  may have a bearing (not shown) and a dynamic seal (not shown) for accommodating rotation of the rotating barrel relative to the non-rotating barrel. The outer non-rotating barrel  210  may be connected to a top of the swivel frame  30 , such as by fastening. The swivel frame  30  may be connected to a top of the drive body  22 , such as by fastening. The inner rotating barrel  21   n  may have an upper portion disposed in the outer non-rotating barrel  210  and a stinger portion extending therefrom, through the control swivel  26 , and through the compensator  25 . A lower end of the stinger portion may carry a stab seal for engagement with an inner seal receptacle  15   b  of each coupling  15  when the respective unit  1   c,d,s  is connected to the motor unit  1   m , thereby sealing an interface formed between the units. 
     The control swivel  26  may include a non-rotating inner barrel and a rotating outer barrel. The inner barrel may be connected to the swivel frame  30  and the outer barrel may be supported from the inner barrel by one or more bearings. The outer barrel may have hydraulic ports (six shown) formed through a wall thereof, each port in fluid communication with a respective hydraulic passage formed through the inner barrel (only two passages shown). An interface between each port and passage may be straddled by dynamic seals for isolation thereof. The inner barrel passages may be in fluid communication with the HPU manifold  60   m  via a plurality of fluid connectors, such as the hydraulic conduits  64   a - e  ( FIG. 5 ), and the outer barrel ports may be in fluid communication with either the linear actuator  33  or lock ring  34  via jumpers (not shown). The outer barrel ports may be disposed along the outer barrel. The inner barrel may have a mandrel portion extending along the outer barrel and a head portion extending above the outer barrel. The head portion may connect to the swivel frame  30  and have the hydraulic ports extending therearound. 
     The compensator  25  may include a linear actuator  33 , the lock ring  34 , and one or more (such as three, but only one shown) lock pins  35 . The lock ring  34  may have an outer flange  34   f  formed at an upper end thereof, a bore formed therethrough, one or more chambers housing the lock pins  35  formed in an inner surface thereof, a locking profile  34   k  formed in a lower end thereof, members, such as males  34   m , of a hydraulic junction  36  ( FIG. 7A ) formed in the lower end thereof, and hydraulic passages (two shown) formed through a wall thereof. The locking profile  34   k  may include a lug for each prong-way of the external bayonet profiles of the heads  15   h.    
     Each lock pin  35  may be a piston dividing the respective chamber into an extension portion and a retraction portion and the lock ring  34  may have passages formed through the wall thereof for the chamber portions. Each passage may be in fluid communication with the HPU manifold  60   m  via a respective fluid connector, such as hydraulic conduit  64   a  ( FIG. 3 , only one shown). The lock pins  35  may share an extension control line and a retraction control line via a splitter (not shown). Supply of hydraulic fluid to the extension passages may move the lock pins  35  to an engaged position where the pins extend into respective slots  15   t  formed in the prong-ways of the heads  15   h , thereby longitudinally connecting the lock ring  34  to a respective unit  1   c,d,s . Supply of hydraulic fluid to the retraction passages may move the lock pins  35  to a release position (shown) where the pins are contained in the respective chambers of the lock ring  34 . 
     The linear actuator  33  may include one or more, such as three, piston and cylinder assemblies  33   a,b  for vertically moving the lock ring  34  relative to the drive gear  23  between a lower hoisting position ( FIG. 7A ) and an upper ready position (shown). A bottom of the lock ring flange  34   f  may be seated against a top of the drive gear flange  23   f  in the hoisting position such that string weight carried by either the drilling unit  1   d  or the casing unit  1   c  may be transferred to the drive gear  23  via the flanges and not the linear actuator  33  which may be only capable of supporting stand weight or weight of a casing joint  90   j  ( FIG. 12A ) of casing. String weight may be one hundred (or more) times that of stand weight or joint weight. A piston of each assembly  33   a,b  may be seated against the respective cylinder in the ready position. 
     Each cylinder of the linear actuator  33  may be disposed in a respective peripheral socket formed through the lock ring flange  34   f  and be connected to the lock ring  34 , such as by threaded couplings. Each piston of the linear actuator  33  may extend into a respective indentation formed in a top of the drive gear flange  23   f  and be connected to the drive gear  23 , such as by threaded couplings. Each socket of the lock ring flange  34   f  may be aligned with the respective lug of the locking profile  34   k  and each indentation of the drive gear flange  23   f  may be aligned with a receptacle of the locking profile  23   k  such that connection of the linear actuator  33  to the lock ring  34  and drive gear  23  ensures alignment of the locking profiles. 
     Each piston of the linear actuator  33  may be disposed in a bore of the respective cylinder. The piston may divide the cylinder bore into a raising chamber and a lowering chamber and the cylinder may have ports (only one shown) formed through a wall thereof and each port may be in fluid communication with a respective chamber. Each port may be in fluid communication with the HPU manifold  60   m  via a respective fluid connector, such as hydraulic conduit  64   b  (only one shown in  FIG. 5 ). Supply of hydraulic fluid to the raising port may lift the lock ring  34  toward the ready position. Supply of hydraulic fluid to the lowering port may drop the lock ring  34  toward the hoisting position. A stroke length of the linear compensator  25  between the ready and hoisting positions may correspond to, such as being equal to or slightly greater than, a makeup length of the drill pipe  8   p  and/or casing joint  90   j.    
     Each coupling  15  may further include mating members, such as females  15   f , of the junction  36  formed in a top of the prongs of the head  15   h . The male members  34   m  may each have a nipple for receiving a respective jumper from the control swivel  26 , a stinger, and a passage connecting the nipple and the stinger. Each stinger may carry a respective seal. The female member  15   f  may have a seal receptacle for receiving the respective stinger. The junction members  34   m ,  15   f  may be asymmetrically arranged to ensure that the male member  34   m  is stabbed into the correct female member  15   f.    
     Referring to  FIG. 8A , the backup wrench  29  may include a hinge  29   h , a tong  29   t , a guide  29   g , an arm  29   a , a tong actuator (not shown), a tilt actuator (not shown), and a linear actuator (not shown). The tong  29   t  may be transversely connected to the arm  29   a  while being longitudinally movable relative thereto subject to engagement with a stop shoulder thereof. The hinge  29   h  may pivotally connect the arm  29   a  to a bottom of the drive body  22 . The hinge  29   h  may include a pair of knuckles fastened or welded to the drive body  22  and a pin extending through the knuckles and a hole formed through a top of the arm  29   a . The tilt actuator may include a piston and cylinder assembly having an upper end pivotally connected to the bottom of the drive body  22  and a lower end pivotally connected to a back of the arm  29   a . The piston may divide the cylinder bore into an activation chamber and a stowing chamber and the cylinder may have ports (only one shown) formed through a wall thereof and each port may be in fluid communication with a respective chamber. Each port may be in fluid communication with the HPU manifold  60   m  via a respective control line (not shown). Supply of hydraulic fluid to the activation port may pivot the tong  29   t  about the hinge  29   h  toward the quill  37 . Supply of hydraulic fluid to the stowing port may pivot the tong  29   t  about the hinge  29   h  away from the quill  37 . 
     The tong  29   t  may include a housing having an opening formed therethrough and a pair of jaws (not shown) and the tong actuator may move one of the jaws radially toward or away from the other jaw. The guide  29   g  may be a cone connected to a lower end of the tong housing, such as by fastening, for receiving a threaded coupling, such as a box, of the drill pipe  8   p . The quill  37  may extend into the tong opening for stabbing into the drill pipe box. Once stabbed, the tong actuator may be operated to engage the movable jaw with the drill pipe box, thereby torsionally connecting the drill pipe box to the drive body  22 . The tong actuator may be hydraulic and operated by the HPU  60  via a control line  66   d  ( FIG. 5 ). 
     The backup wrench linear actuator may include a gear rack (not shown) formed along a straight lower portion of the arm  29   a , one or two pinions (not shown), and one or two pinion motors (not shown). The arm  29   a  may have a deviated upper portion engaged with the hinge  29   h . Each pinion may be meshed with the gear rack of the arm  29   a  and torsionally connected to a rotor of the respective pinion motor. A stator of each pinion motor may be connected to the housing of the tong  29   t  and be in electrical communication with the motor driver  61  via a cable  67   a  ( FIG. 5 ). The pinion motors may share a cable via a splice (not shown). Each pinion motor may be reversible and rotation of the respective pinion in a first direction, such as counterclockwise, may raise the tong  29   t  along the arm  29   a  and rotation of the respective pinion in a second opposite direction, such as clockwise, may lower the tong along the arm. Each pinion motor may include a brake (not shown) for locking position of the tong  29   t  once the pinion motors are shut off. The brake may be disengaged by supply of electricity to the pinion motors and engaged by shut off of electricity to the pinion motors. 
     Referring to  FIG. 5 , the latch  69  may include a one or more (pair shown) units disposed at sides of the drive body  22 . Each latch unit may include a lug connected, such as by fastening or welding, to the drive body  22  and extending from a bottom thereof, a fastener, such as a pin, and an actuator. Each lug may have a hole formed therethrough and aligned with a respective actuator. Each interior knuckle of the slide hinge  12  may have a hole formed therethrough for receiving the respective latch pin. Each actuator may include a cylinder and piston (not shown) connected to the latch pin and disposed in a bore of the cylinder. Each cylinder may be connected to the drive body  22 , such as by fastening, adjacent to the respective lug. The piston may divide the cylinder bore into an extension chamber and a retraction chamber and the cylinder may have ports formed through a wall thereof and each port may be in fluid communication with a respective chamber. Each port may be in fluid communication with the HPU manifold  60   m  via a control line  66   a  ( FIG. 3 , only one shown). The latch units may share an extension control line and a retraction control line via a splitter (not shown). Supply of hydraulic fluid to the extension port may move the pin to an engaged position (shown) where the pin extends through the respective lug hole and the respective interior knuckle hole of the slide hinge  12 , thereby connecting the pipe handler  1   p  to the drive body  22 . Supply of hydraulic fluid to the retraction port may move the pin to a release position (not shown) where the pin is clear of the interior slide hinge knuckle. 
       FIG. 2B  illustrates the drilling unit  1   d . The drilling unit  1   d  may include the coupling, the quill  37 , an internal blowout preventer (IBOP)  38 , and one or more, such as two (only one shown), hydraulic passages  39 . The quill  37  may be a shaft, may have an upper end connected to the torso  15   r , may have a bore formed therethrough, may have a threaded coupling, such as a pin, formed at a lower end thereof. In some embodiments, the IBOP could be controlled from a separate control unit at the accessory tool. The separate control unit could be powered from the genset  51 . For example, the genset  51  could be connected to the tool so as to avoid impacts during the drilling process, such as with springs. 
     The IBOP  38  may include an internal sleeve  38   v  and one or more shutoff valves  38   u,b . The IBOP may further include an automated actuator for one  38   u  of the shutoff valves  38   u,b  and the other  38   b  of the shutoff valves  38   u,b  may be manually actuated. Each shutoff valve  38   u,b  may be connected to the sleeve  38   v  and the sleeve may be received in a recessed portion of the quill  37  and/or coupling  15 . The IBOP valve actuator may be disposed in a socket formed through a wall of the quill  37  and/or coupling  15  and may include an opening port and/or a closing port and each port may be in fluid communication with the HPU manifold  60   m  via a respective hydraulic passage  39 , respective male  34   m  and female  15   f  members, respective jumpers, the control swivel  26 , and respective fluid connectors, such as hydraulic conduits  64   c,d  ( FIG. 5 ). The hydraulic conduit  64   e  may connect to a drain port of the IBOP valve actuator. 
       FIGS. 3A and 3B  illustrate the casing unit  1   c . The casing unit  1   c  may include the coupling  15 , a clamp, such as a spear  40 , an adapter  48 , one or more, such as three (only one shown), hydraulic passages  49 , a fill up tool  50 , a genset  51 , and a frame  58 . The fill up tool  50  may include a flow tube  50   t , a stab seal, such as a cup seal  50   c , a release valve  50   r , a mud saver valve  50   m , a fill up valve  50   f , and a fill up valve actuator  50   a.    
     The fill up valve  50   f  may include a valve member, such as a ball, a valve seat, and a housing. The housing may be tubular, may have an upper end connected to the torso  15   r  and a lower end connected to the adapter  48 . The valve seat may be disposed in the housing, may be made from a metal/alloy, ceramic/cermet, or polymer and may be connected to the housing, such as by fastening. The ball may be disposed in a spherical recess formed by the valve seat and rotatable relative to the housing between an open position (shown) and a closed position. The ball may have a bore therethrough corresponding to the housing bore and aligned therewith in the open position. A wall of the ball may close the housing bore in the closed position. The ball may have a stem extending into an actuation port formed through a wall of the housing. The stem may mate with a shaft of the actuator  50   a  and the actuator may be operable to rotate the ball between the open and the closed positions. 
     The fill up valve actuator  50   a  may be hydraulic and may have a position sensor Op in communication with the shaft and in communication with a microcontroller MCU of the genset  51  via a data cable  59   a . The position sensor Op may also be electrically powered by the microcontroller MCU via the data cable  59   a . The position sensor Op may verify that the actuator  50   a  has properly functioned to open and/or close the fill up valve  50   f . The actuator  50   a  may be operated by one or more fluid connectors, such as hydraulic conduits  59   b,c  leading to a fluid, such as hydraulic, manifold  56  ( FIG. 4 ) of the genset  51 . 
     The adapter  48  may be tubular, may have a bore formed therethrough, and may have an upper end connected to the housing of the fill up valve  50   f , and may have an outer thread and an inner receptacle formed at a lower end thereof. The frame  58  may mount the genset  51  to an outer surface of the adapter  48 . 
     The spear  40  may include a clamp actuator, such as linear actuator  41 , a bumper  42 , a collar  43 , a mandrel  44 , a set of grippers, such as slips  45 , a seal joint  46 , and a sleeve  47 . The collar  43  may have an inner thread formed at each longitudinal end thereof. The collar upper thread may be engaged with the outer thread of the adapter  48 , thereby connecting the two members. The collar lower thread may be engaged with an outer thread formed at an upper end of the mandrel  44  and the mandrel may have an outer flange formed adjacent to the upper thread and engaged with a bottom of the collar  43 , thereby connecting the two members. 
     The seal joint  46  may include the inner barrel, an outer barrel, and a nut. The inner barrel may have an outer thread engaged with a threaded portion of the adapter receptacle and an outer portion carrying a seal engaged with a seal bore portion of the adapter receptacle. The mandrel  44  may have a bore formed therethrough and an inner receptacle formed at an upper portion thereof and in fluid communication with the bore. The mandrel receptacle may have an upper conical portion, a threaded mid portion, and a recessed lower portion. The outer barrel may be disposed in the recessed portion of the mandrel  44  and trapped therein by engagement of an outer thread of the nut with the threaded mid portion of the mandrel receptacle. The outer barrel may have a seal bore formed therethrough and a lower portion of the inner barrel may be disposed therein and carry a stab seal engaged therewith. 
     The linear actuator  41  may include a housing, an upper flange, a plurality of piston and cylinder assemblies, a lower flange, and a position sensor Ret in communication with one or more of the piston and cylinder assemblies. The position sensor Ret may be also be in communication with the microcontroller MCU via a data cable  59   f . The position sensor Ret may also be electrically powered by the microcontroller MCU via the data cable  59   f . The position sensor Ret may verify that the piston and cylinder assemblies have properly functioned to extend and/or retract the slips  45 . The housing may be cylindrical, may enclose the cylinders of the assemblies, and may be connected to the upper flange, such as by fastening. The collar  43  may also have an outer thread formed at the upper end thereof. The upper flange may have an inner thread engaged with the outer collar thread, thereby connecting the two members. Each flange may have a pair of lugs for each piston and cylinder assembly connected, such as by fastening or welding, thereto and extending from opposed surfaces thereof. 
     Each cylinder of the linear actuator  41  may have a coupling, such as a hinge knuckle, formed at an upper end thereof. The upper hinge knuckle of each cylinder may be received by a respective pair of lugs of the upper flange and pivotally connected thereto, such as by fastening. Each piston of the linear actuator  41  may have a coupling, such as a hinge knuckle, formed at a lower end thereof. Each piston of the linear actuator  41  may be disposed in a bore of the respective cylinder. The piston may divide the cylinder bore into a raising chamber and a lowering chamber and the cylinder may have ports formed through a wall thereof and each port may be in fluid communication with a respective chamber. 
     Each port may be in fluid communication with the hydraulic manifold  56  via respective fluid connectors, such as hydraulic conduits  59   d,e . Supply of hydraulic fluid to the raising port may lift the lower flange to a retracted position (shown). Supply of hydraulic fluid to the lowering port may drop the lower flange toward an extended position (not shown). The piston and cylinder assemblies may share an extension conduit  59   e  and a retraction conduit  59   d  via a splitter (not shown). 
     The sleeve  47  may have an outer shoulder formed in an upper end thereof trapped between upper and lower retainers. A washer may have an inner shoulder formed in a lower end thereof engaged with a bottom of the lower retainer. The washer may be connected to the lower flange, such as by fastening, thereby longitudinally connecting the sleeve  47  to the linear actuator  41 . The sleeve  47  may also have one or more (pair shown) slots formed through a wall thereof at an upper portion thereof. 
     The bumper  42  include a striker and a base connected to the mandrel, such as by one or more threaded fasteners, each fastener extending through a hole thereof, through a respective slot of the sleeve  47 , and into a respective threaded socket formed in an outer surface of the mandrel  44 , thereby also torsionally connecting the sleeve to the mandrel while allowing limited longitudinal movement of the sleeve relative to the mandrel to accommodate operation of the slips  45 . The striker may be linked to the base by one or more (pair shown) compression springs. A lower portion of the spear  40  may be stabbed into the casing joint  90   j  until the striker engages a top of the casing joint. The springs may cushion impact with the top of the casing joint  90   j  to avoid damage thereto. 
     The sleeve  47  may extend along the outer surface of the mandrel from the lower flange of the linear actuator  41  to the slips  45 . A lower end of the sleeve  47  may be connected to upper portions of each of the slips  45 , such as by a flanged (i.e., T-flange and T-slot) connection. Each slip  46  may be radially movable between an extended position and a retracted position by longitudinal movement of the sleeve  47  relative to the slips. A slip receptacle may be formed in an outer surface of the mandrel  44  for receiving the slips  45 . The slip receptacle may include a pocket for each slip  46 , each pocket receiving a lower portion of the respective slip. The mandrel  44  may be connected to lower portions of the slips  45  by reception thereof in the pockets. Each slip pocket may have one or more (three shown) inclined surfaces formed in the outer surface of the mandrel  44  for extension of the respective slip. A lower portion of each slip  46  may have one or more (three shown) inclined inner surfaces corresponding to the inclined slip pocket surfaces. 
     Downward movement of the sleeve  47  toward the slips  45  may push the slips along the inclined surfaces, thereby wedging the slips toward the extended position. The lower portion of each slip  46  may also have a guide profile, such as tabs, extending from sides thereof. Each slip pocket may also have a mating guide profile, such as grooves, for retracting the slips  45  when the sleeve  47  moves upward away from the slips. Each slip  46  may have teeth formed along an outer surface thereof. The teeth may be made from a hard material, such as tool steel, ceramic, or cermet for engaging and penetrating an inner surface of the casing joint  90   j , thereby anchoring the spear  40  to the casing joint. 
     The cup seal  50   c  may have an outer diameter slightly greater than an inner diameter of the casing joint  90   j  to engage the inner surface thereof during stabbing of the spear  40  therein. The cup seal  50   c  may be directional and oriented such that pressure in the casing bore energizes the seal into engagement with the casing joint inner surface. An upper end of the flow tube  50   t  may be connected to a lower end of the mandrel  44 , such as by threaded couplings. The mud saver valve  50   m  may be connected to a lower end of the flow tube  50   t , such as by threaded couplings. The cup seal  50   c  and release valve  50   r  may be disposed along the flow tube  50   t  and trapped between a bottom of the mandrel  44  and a top of the mudsaver valve  50   m.    
     The spear  40  may be capable of supporting weight of the casing string  90 . The string weight may be transferred to the becket  19  via the slips  45 , the mandrel  44 , the collar  43 , the adapter  48 , the coupling  15 , the bayonet profile  23   b , the down thrust bearing  27 , the drive body  22 . Fluid may be injected into the casing string  90  via the hose nipple  20 , the mud swivel  21 , the coupling  15 , the adapter  48 , the seal joint  46 , the mandrel  44 , the flow tube  50   t , and the mud saver valve  50   m.    
     Alternatively, the clamp may be a torque head instead of the spear  40 . The torque head may be similar to the spear except for receiving an upper portion of the casing joint  90   j  therein and having the set of grippers for engaging an outer surface of the casing joint instead of the inner surface of the casing joint. 
       FIG. 4  illustrates the genset  51 . The genset  51  may include a fluid driven, such as hydraulic, motor  52 , a gearbox  53 , an electric generator  54 , a control unit  55 , and the hydraulic manifold  56 . The gearbox  53  may be a planetary gearbox. 
     Alternatively, the control swivel  26 , the fluid driven motor  52 , the fluid manifold  56 , the linear actuator  41 , and the fill up valve actuator  50   a  may be pneumatic instead of hydraulic. 
     The fluid driven motor  52  may be a gerotor motor and include a housing  52   h , a drive shaft  52   d , a valve shaft  52   v , an output shaft  52   o , an orbital gear set having a rotor  52   r  and a stator  52   s , a plurality of roller vanes  52   n , and a valve spool  52   p . To facilitate assembly, the housing  52   h  may include two or more sections connected together, such as by one or more threaded fasteners. The output shaft  52   o  may have a hollow upper head disposed in the housing and a lower shank extending therethrough. The head may have a torsional profile, such as splines, formed in an inner surface thereof. A shaft spacer and a lower portion of the drive shaft  52   d  may each have teeth meshed with the splines, thereby torsionally connecting the members. The shaft spacer may also have a torsional profile formed in an inner surface thereof meshed with a torsional profile formed in a lower end of the valve shaft  52   v.    
     The drive shaft  52   d  may be disposed in the head with a sufficient clearance formed therebetween to accommodate articulation of the drive shaft with the orbiting of the rotor  52   r . The stator  52   s  may be disposed between the housing sections and connected thereto by the threaded fasteners. The roller vanes  52   n  may be disposed in sockets formed in the stator  52   s  and may be trapped between the housing sections. The rotor  52   r  may be disposed in the stator  52   s  and have a number of lobes formed in an outer surface thereof equal to the number of roller vanes minus one. Selective supply of pressurized hydraulic fluid by the valve spool  52   p  through pressure chambers formed between the rotor  52   r  and the stator  52   s  may drive the rotor in an orbital movement within the stator, thereby converting fluid energy from the hydraulic fluid into kinetic energy of the output shaft  52   o.    
     The rotor  52   r  may have a torsional profile formed in an inner surface thereof meshed with a torsional profile formed of the upper portion of the drive shaft  52   d , thereby torsionally connecting the two members. The valve shaft  52   v  may extend through the drive shaft  52   s  and have an upper portion with a torsional profile meshed with a torsional profile formed in a lower portion of the valve spool  52   p . An inlet may be formed through a wall of the housing  52   h  to provide fluid communication between the valve spool  52   p  and a fluid connector, such as hydraulic conduit  57   a  leading to the hydraulic passage  49 . An outlet (not shown) may be formed through a wall of the housing  52   h  to provide fluid communication between the valve spool  52   p  and a fluid connector (not shown) leading to a second hydraulic passage of the coupling  15 . 
     The valve spool  52   p  may be disposed in the housing  52   h  and may rotate with the output shaft  52   o  via the valve shaft  52   v . The valve spool  52   p  may have flow slots formed in an outer surface thereof that selectively provide fluid communication between the inlet and outlet and the appropriate pressure chambers formed between the rotor  52   r  and the stator  52   s . A bushing may be disposed between the housing  52   h  and the output shaft  52   o  for radial support of the output shaft therefrom. A thrust bearing may be disposed between the housing  52   h  and the output shaft  52   o  for longitudinal support of the output shaft therefrom. One or more (pair shown) dynamic seals may be disposed between the housing  52   h  and the output shaft  52   o  to isolate the rotating interface therebetween for prevention of loss of hydraulic fluid from the fluid driven motor  52  and for prevention of contaminants from entering therein. 
     The gear box  53  may be planetary and include a housing  53   h  and a cover  53   c  connected thereto, such as by fasteners (not shown). The housing  53   h  and cover  53   c  may enclose a lubricant chamber sealed at ends thereof by oil seals. The gear box  53  may further include an input disk  53   k  having a hub extending from an upper end of the lubricant chamber and torsionally connected to the output shaft  52   o  of the fluid driven motor  52  by mating profiles (not shown), such as splines, formed at adjacent ends thereof. The gear box  53  may further include an output shaft  53   p  extending from a lower end of the lubricant chamber and torsionally connected to a shaft  54   s  of the electric generator  54  by mating profiles (not shown), such as splines, formed at adjacent ends thereof. 
     Each of the output shaft  53   p  and input disk  53   k  may be radially supported from the respective cover  53   c  and housing  53   h  for rotation relative thereto by respective bearings. The hub of the input disk  53   k  may receive an end of the output shaft  53   p  and a needle bearing may be disposed therebetween for supporting the output shaft therefrom while allowing relative rotation therebetween. A sun gear  53   s  may be disposed in the lubricant chamber and may be mounted onto the output shaft  53   p . A stationary housing gear  53   g  may be disposed in the lubricant chamber and mounted to the housing  53   h . A plurality of planetary rollers  53   r  may also be disposed in the lubricant chamber. 
     Each planetary roller  53   r  may include a planetary gear  53   e  disposed between and meshed with the sun gear  53   s  and the housing gear  53   g . The planetary gears  53   e  may be linked by a carrier  53   b  which may be radially supported from the output shaft  53   p  by a bearing to allow relative rotation therebetween. Each planetary roller  53   r  may further include a support shaft  53   f  which is supported at its free end by a support ring and on which the respective planetary gear  53   e  may be supported by a bearing. Each planetary gear  53   e  may include first and second sections of different diameters, the first section meshing with the housing gear  53   g  and the sun gear  53   s  and the second section meshing with an input gear  53   j  and a support gear  53   b . The input gear  53   j  may be mounted to the input disk  53   k  by fasteners. The support gear  53   b  may be radially supported from the input shaft  53   p  by a bearing to allow relative rotation therebetween. 
     The support shafts  53   f  may be arranged at a slight angle with respect to longitudinal axes of the output shaft  53   p  and input disk  53   k . The planetary gears  53   e , housing gear  53   g , input gear  53   j , and support gear  53   b  may also be slightly conical so that, upon assembly of the gear box  53 , predetermined traction surface contact forces may be generated. The gear box  53  may further include assorted thrust bearings disposed between various members thereof. 
     In operation, rotation of the input disk  53   k  by the fluid driven motor  52  may drive the input gear  53   j . The input gear  53   j  may drive the planetary gears  53   e  to roll along the housing gear  53   g  while also driving the sun gear  53   s . Since the diameter of the second section of each planetary gear  53   e  may be significantly greater than that of the first section, the circumferential speed of the second section may correspondingly be significantly greater than that of the first section, thereby providing for a speed differential which causes the output shaft  53   p  to counter-rotate at a faster speed corresponding to the difference in diameter between the planetary gear sections. Driving torque of the output shaft  53   p  is also reduced accordingly. 
     Alternatively, the diameter of the first section of each planetary gear  53   e  may be greater in diameter than that of the second section resulting in rotation of the input gear  53   j  in the same direction as the input shaft  53   p  again at a speed corresponding to the difference in diameter between the two sections. 
     The electric generator  54  may include a rotor, a stator, and a pair of bearings supporting the rotor for rotation relative to the stator. The electric generator  54  may be a permanent magnet generator. For example, the rotor may include a hub  54   b  made from a magnetically permeable material, a plurality of permanent magnets  54   m  torsionally connected to the hub, and a shaft  54   s . The rotor may include one or more pairs of permanent magnets  54   m  having opposite polarities N,S. The permanent magnets  54   m  may also be fastened to the hub  54   b , such as by retainers. The hub  54   b  may be torsionally connected to the shaft  54   s  and fastened thereto. The stator may include a housing  54   h , a core  54   c , a pair of end caps  54   p , and a plurality of windings  54   w , such as three (only two shown). The core  54   c  may include a stack of laminations made from a magnetically permeable material. The stack may have lobes formed therein, each lobe for receiving a respective winding. The core  54   c  may be longitudinally and torsionally connected to the housing  54   h , such as by an interference fit. 
     The control unit  55  may include a power converter  55   c , an electrical energy storage device, such as a battery  55   b , the microcontroller MCU, a wireless data link. The wireless data link may include a transmitter TX, a receiver RX, an antenna  55   a . The transmitter TX and receiver RX may be separate devices (as shown) or may be integrated into a single transceiver. The transmitter TX and receiver RX may share the single antenna  55   a  (shown) or each have their own antenna. The wireless data link may be half-duplex or full-duplex. The power converter  55   c  may have an input in electrical communication with each winding  54   w  of the electric generator  54  and an output in electrical communication with the battery  55   b . The power converter  55   c  may receive a multi-phase, such as three phase, power signal from the electric generator  54  and convert the power signal into a direct current power signal for charging the battery  55   b . The power converter  55   c  may also step-down a voltage of the power signal from the electric generator  54  to a voltage usable by the battery  55   b , such as three, six, nine, twelve, or twenty-four volts. The battery  55   b  may also be in electrical communication with the microcontroller MCU. The transmitter TX may be in electrical communication with the microcontroller MCU and the antenna  55   a  and may include an amplifier, a modulator, and an oscillator. The receiver RX may be in electrical communication with the microcontroller MCU and the antenna  55   a  and may include an amplifier, a demodulator, and a filter. The microcontroller MCU may receive instruction signals, via the antenna  55   a  and receiver RX, from a control console  62  ( FIG. 5 ) to operate the fill up valve actuator  50   a  and/or the linear actuator  41  in response thereto. The instruction signals may be radio frequency wireless signals and may also be digital. The instruction signals may be received or transmitted with the used of the wireless data link. The microcontroller MCU may receive position statuses from the position sensors Op, Ret, and may send the position statuses to the control console  62  via the antenna  55   a  and transmitter TX. 
     Alternatively, the electrical energy storage device may be a super-capacitor, capacitor, or inductor instead of a battery. 
     The hydraulic manifold  56  may include a plurality of control valves, such as directional control valves, for operating the fill up valve actuator  50   a  and the linear actuator  41 . Each control valve may be operated by an electric actuator (not shown) in electrical communication with the microcontroller MCU. An inlet of the hydraulic manifold  56  may be in fluid communication with the hydraulic passage  49  via a fluid connector, such as hydraulic conduit  57   b . The inlet of the hydraulic manifold  56  may also be in fluid communication with the second hydraulic passage of the coupling  15  via another fluid connector, such as hydraulic conduit  57   c . The inlet of the hydraulic manifold  56  may also be in fluid communication with a third hydraulic passage of the coupling  15  via another fluid connector, such as hydraulic conduit  57   d . The hydraulic conduits  57   a,b  may both be in simultaneous fluid communication with the hydraulic passage  49  via a splitter. 
     When the casing unit  1   c  is connected to the motor unit  1   m , the hydraulic conduit  64   c  may be connected to the hydraulic conduits  57   a,b  via the control swivel  26  and the hydraulic passage  49 . The hydraulic conduit  64   d  may be connected to the hydraulic conduit  57   c  and the outlet of the fluid driven motor  52  via the control swivel  26  and the second hydraulic passage of the coupling  15 . The hydraulic conduit  64   e  may be connected to the hydraulic conduit  57   d  via the control swivel  26  and the second hydraulic passage of the coupling  15 . The hydraulic conduit  64   c  may be a supply line. The hydraulic conduit  64   d  may be a return line. The hydraulic conduit  64   e  may be a drain line. The microcontroller MCU may operate the hydraulic manifold  56  to selectively provide fluid communication between the hydraulic conduits  57   b - d  and the hydraulic conduits  59   b - e  based on the instruction signals from the control console  62 . 
     Also as the casing unit  1   c  is connected to the motor unit  1   m , the genset  51  may receive hydraulic fluid from the HPU  60  via the hydraulic conduit  57   a , hydraulic passage  49 , and hydraulic conduit  64   c  and return spent hydraulic fluid to the HPU via the hydraulic conduit leading from the second hydraulic passage of the coupling  15 , the second hydraulic passage of the coupling, and the hydraulic conduit  64   d , thereby driving the fluid driven motor  52 . The fluid driven motor  52  may in turn drive the electric generator  54  via the gearbox  53 . The electric generator  54  may power the control unit  55  which may await instruction signals from the control console  62  to operate the spear  40  and/or the fill up valve  50   f  via the hydraulic manifold  56 . 
       FIG. 5  is a control diagram of the top drive system  1  in the drilling mode. The HPU  60  may include a pump  60   p , a check valve  60   k , an accumulator  60   a , a reservoir  60   r  of hydraulic fluid, and the HPU manifold  60   m . The motor driver  61  may be one or more (three shown) phase and include a rectifier  61   r  and an inverter  61   i . The inverter  61   i  may be capable of speed control of the drive motors  18 , such as being a pulse width modulator. Each of the HPU manifold  60   m  and motor driver  61  may be in data communication with the control console  62  for control of the various functions of the top drive system  1 . The top drive system  1  may further include a video monitoring unit  63  having a video camera  63   c  and a light source  63   g  such that a technician (not shown) may visually monitor operation thereof from the rig floor  7   f  or control room (not shown) especially during shifting of the modes. The video monitoring unit  63  may be mounted on the motor unit  1   m.    
     The pipe handler control lines  66   b,c  may flexible control lines such that the pipe handler  1   p  remains connected thereto in any position thereof. 
     The motor unit  1   m  may further include a proximity sensor  68  connected to the swivel frame  30  for monitoring a position of the lock ring flange  34   f . The proximity sensor  68  may include a transmitting coil, a receiving coil, an inverter for powering the transmitting coil, and a detector circuit connected to the receiving coil. A magnetic field generated by the transmitting coil may induce eddy current in the turns gear lock ring flange  34   f  which may be made from an electrically conductive metal or alloy. The magnetic field generated by the eddy current may be measured by the detector circuit and supplied to the control console  62  via control line  65 . 
       FIGS. 6, 7A, 7B, 8A, and 8B  illustrate shifting of the top drive system  1  to the drilling mode. The unit handler  1   u  may be operated to engage the holder  5  with the torso  15   r  of the drilling unit  1   d . Once engaged, the arm  4  may be raised slightly to shift weight of the drilling unit  1   d  from the unit rack  1   k  to the holder  5 . The respective motor  14   m  may then be operated to rotate the respective ring gear  14   g  until the external prongs of the respective head  15   h  are aligned with the internal prong-ways of the ring gear (and vice versa), thereby freeing the head for passing through the ring gear. The arm  4  may then be lowered, thereby passing the drilling unit  1   d  through the respective ring gear  14   g . The unit handler  1   u  may be operated to move the drilling unit  1   d  away from the unit rack  1   k  until the drilling unit is clear of the unit rack. The arm  4  may be raised to lift the drilling unit  1   d  above the rig floor  7   f . The unit handler  1   u  may be operated to horizontally move the drilling unit  1   d  into alignment with the motor unit  1   m.    
     The arm  4  may then be raised to lift the drilling unit  1   d  until the respective head  15   h  is adjacent to the bottom of the drive gear  23 . The drive motors  18  may then be operated to rotate the drive gear  23  until the external prongs of the respective head  15   h  are aligned with the internal prong-ways of the bayonet profile  23   b  and at a correct orientation so that when the drive gear is rotated to engage the bayonet profile with the respective head  15   h , the asymmetric profiles of the hydraulic junction  36  will be aligned. The drive gear  23  may have visible alignment features (not shown) on the bottom thereof to facilitate use of the camera  63   c  for obtaining the alignment and the orientation. Once aligned and oriented, the arm  4  may be raised to lift the coupling  15  of the drilling unit  1   d  into the drive gear  23  until the respective head  15   h  is aligned with the locking profile  23   k  thereof. The lock ring  34  may be in a lower position, such as the hoisting position, such that the top of the respective head  15   h  contacts the lock ring and pushes the lock ring upward. The proximity sensor  68  may then be used to determine alignment of the respective head  15   h  with the locking profile  23   k  by measuring the vertical displacement of the lock ring  34 . Once alignment has been achieved, the compensator actuator  33  may be operated to move the lock ring  34  to the ready position. 
     The drive motors  18  may then be operated to rotate the drive gear  23  until sides of the external prongs of the respective head  15   h  engage respective stop lugs of the locking profile  23   k , thereby aligning the external prongs of the respective head with the internal prongs of the bayonet profile  23   b  and correctly orienting the profiles of the hydraulic junction  36 . In some embodiments, the compensator actuator  33  may then be operated to move the lock ring  34  to the hoisting position, thereby moving the lugs of the locking profile  34   k  into the external prong-ways of the respective head  15   h  and aligning the lock pins  35  with the respective slots  15   t . Movement of the lock ring  34  also stabs the male members  34   m  into the respective female members  15   f , thereby forming the hydraulic junction  36 . The proximity sensor  68  may again be monitored to ensure that the bayonet profiles  23   b  have properly engaged and are not jammed. Hydraulic fluid may then be supplied to the extension portions of the chambers housing the lock pins  35  via the control line  64   a , thereby moving the lock pins radially inward and into the respective slots  15   t . The locking profile  23   k  may have a sufficient length to maintain a torsional connection between the drilling unit  1   d  and the drive gear  23  in and between the ready and hoisting positions of the compensator  25 . The drilling unit  1   d  is now longitudinally and torsionally connected to the drive gear  23 . 
     The tilt actuator of the backup wrench  29  may then be operated to pivot the arm  29   a  and tong  29   t  about the hinge  29   h  and into alignment with the drilling unit  1   d . The linear actuator of the backup tong  29  may then be operated via the cable  67   a  to move the tong  29   t  upward along the arm  29   a  until the tong is positioned adjacent to the quill  37 . The top drive system  1  is now in the drilling mode. 
       FIG. 9  illustrates the top drive system  1  in the drilling mode. The drilling rig  7  may be part of a drilling system. The drilling system may further include a fluid handling system  70 , a blowout preventer (BOP)  71 , a flow cross  72  and the drill string  8 . The drilling rig  7  may further include a hoist  73 , a rotary table  74 , and a spider  75 . The rig floor  7   f  may have the opening through which the drill string  8  extends downwardly through the flow cross  72 , BOP  71 , and a wellhead  76   h , and into a wellbore  77 . 
     The hoist  73  may include the drawworks  73   d , wire rope  73   w , a crown block  73   c , and the traveling block  73   t . The traveling block  73   t  may be supported by wire rope  73   w  connected at its upper end to the crown block  73   c . The wire rope  73   w  may be woven through sheaves of the blocks  73   c,t  and extend to the drawworks  73   d  for reeling thereof, thereby raising or lowering the traveling block  73   t  relative to the derrick  13   d.    
     The fluid handling system  70  may include a mud pump  78 , the standpipe  79 , a return line  80 , a separator, such as shale shaker  81 , a pit  82  or tank, a feed line  83 , and a pressure gauge  84 . A first end of the return line  80  may be connected to the flow cross  72  and a second end of the return line may be connected to an inlet of the shaker  81 . A lower end of the standpipe  79  may be connected to an outlet of the mud pump  78  and an upper end of the standpipe may be connected to the mud hose. A lower end of the feed line  83  may be connected to an outlet of the pit  82  and an upper end of the feed line may be connected to an inlet of the mud pump  78 . 
     The wellhead  76   h  may be mounted on a conductor pipe  76   c . The BOP  71  may be connected to the wellhead  76   h  and the flow cross  72  may be connected to the BOP, such as by flanged connections. The wellbore  77  may be terrestrial (shown) or subsea (not shown). If terrestrial, the wellhead  76   h  may be located at a surface  85  of the earth and the drilling rig  7  may be disposed on a pad adjacent to the wellhead. If subsea, the wellhead  76   h  may be located on the seafloor or adjacent to the waterline and the drilling rig  7  may be located on an offshore drilling unit or a platform adjacent to the wellhead. 
     The drill string  8  may include a bottomhole assembly (BHA)  8   b  and a stem. The stem may include joints of the drill pipe  8   p  connected together, such as by threaded couplings. The BHA  8   b  may be connected to the stem, such as by threaded couplings, and include a drill bit and one or more drill collars (not shown) connected thereto, such as by threaded couplings. The drill bit may be rotated by the motor unit  1   m  via the stem and/or the BHA  8   b  may further include a drilling motor (not shown) for rotating the drill bit. The BHA  8   b  may further include an instrumentation sub (not shown), such as a measurement while drilling (MWD) and/or a logging while drilling (LWD) sub. 
     The drill string  8  may be used to extend the wellbore  77  through an upper formation  86  and/or lower formation (not shown). The upper formation may be non-productive and the lower formation may be a hydrocarbon-bearing reservoir. During the drilling operation, the mud pump  78  may pump the drilling fluid  87  from the pit  82 , through the standpipe  79  and mud hose to the motor unit  1   m . The drilling fluid may include a base liquid. The base liquid may be refined or synthetic oil, water, brine, or a water/oil emulsion. The drilling fluid  87  may further include solids dissolved or suspended in the base liquid, such as organophilic clay, lignite, and/or asphalt, thereby forming a mud. 
     The drilling fluid  87  may flow from the standpipe  79  and into the drill string  8  via the motor  1   m  and drilling  1   d  units. The drilling fluid  87  may be pumped down through the drill string  8  and exit the drill bit, where the fluid may circulate the cuttings away from the bit and return the cuttings up an annulus formed between an inner surface of the wellbore  77  and an outer surface of the drill string  8 . The drilling fluid  87  plus cuttings, collectively returns, may flow up the annulus to the wellhead  76   h  and exit via the return line  80  into the shale shaker  81 . The shale shaker  81  may process the returns to remove the cuttings and discharge the processed fluid into the mud pit  82 , thereby completing a cycle. As the drilling fluid  87  and returns circulate, the drill string  8  may be rotated by the motor unit  1   m  and lowered by the traveling block  73   t , thereby extending the wellbore  77 . 
       FIG. 10  illustrates shifting of the top drive system  1  from the drilling mode to the casing mode. Once drilling the formation  86  has been completed, the drill string  8  may be tripped out from the wellbore  77 . Once the drill string  8  has been retrieved to the rig  7 , the drilling unit  1   d  may be released from the motor unit  1   m  and loaded onto the unit rack  1   k . The top drive system  1  may then be shifted into the casing mode by repeating the steps discussed above in relation to  FIGS. 6-8B  for the casing unit  1   c.    
       FIGS. 11 and 12A  illustrate extension of a casing string  90  using the top drive system  1  in the casing mode. Once the casing unit  1   c  has been connected to the motor unit  1   m , the holder  5  may be disconnected from the arm  4  and stowed on the side bar  13   r . The pipe clamp  17  may then be connected to the arm  4  and the unit handler  1   u  operated to engage the pipe clamp with the casing joint  90   j . The pipe clamp  17  may be manually actuated between an engaged and disengaged position or include an actuator, such as a hydraulic actuator, for actuation between the positions. The casing joint  90   j  may initially be located on the subfloor structure and the unit handler  1   u  may be operated to raise the casing joint to the rig floor  7   f  and into alignment with the casing unit  1   c  and the unit handler  1   h  may hold the casing joint while the spear  40  and fill up tool  50  are stabbed into the casing joint. 
     Just before stabbing, the compensator  25  may be stroked upward and the pressure regulator of the HPU manifold  60   m  may be operated to maintain the compensator actuator  33  at a sensing pressure, such as slightly less than the pressure required to support weight of the lock ring  34  and casing unit  1   c , such that the compensator  25  drifts to the hoisting position. During stabbing, the bumper  42  may engage a top of the casing joint  90   j  and the proximity sensor  68  may be monitored by the control console  62  to detect stroking of the compensator  25  to the ready position. The camera  63   c  may also observe stabbing of the spear  40  into the casing joint  90   j . Once stabbed, the spear slips  45  may be engaged with the casing joint  90   j  by operating the linear actuator  41 . 
     The compensator  25  may be stroked upward and the pressure regulator of the HPU manifold  60   m  may be operated to maintain the compensator actuator  33  at a second sensing pressure, such as slightly less than the pressure required to support weight of the lock ring  34 , casing unit  1   c , and casing joint  90   j , such that the compensator  25  drifts to the hoisting position. The motor  1   m  and casing  1   c  units, pipe handler  1   p , and casing joint  90   j  may be lowered by operation of the hoist  73  and a bottom coupling of the casing joint stabbed into the top coupling of the casing string  90 . During stabbing, the proximity sensor  68  may be monitored by the control console  62  to detect stroking of the compensator  25  to the ready position and the hoist  73  may be locked at the ready position. 
     The rotary table  74  may be locked or a backup tong (not shown) may be engaged with the top coupling of the casing string  90  and the drive motors  18  may be operated to spin and tighten the threaded connection between the casing joint  90   j  and the casing string  90 . The hydraulic pressure may be maintained in the linear actuator  33  corresponding to the weight of the lock ring  34 , casing unit  1   c , and casing joint  90   j  so that the threaded connection is maintained in a neutral condition during makeup. The pressure regulator of the HPU manifold  60   m  may relieve fluid pressure from the linear actuator  33  as the casing joint  90   j  is being madeup to the casing string  90  to maintain the neutral condition while the compensator  25  strokes downward to accommodate the longitudinal displacement of the threaded connection. 
       FIG. 12B  illustrates running of the extended casing string  90 ,  90   j  into the wellbore  77  using the top drive system  1 . The HPU manifold  60   m  may be operated to pressurize the linear actuator  33  to exert the downward preload onto the lock ring  34 . The spider  75  may then be removed from the rotary table  74  to release the extended casing string  90 ,  90   j  and running thereof may continue. Injection of the drilling fluid  87  into the extended casing string  90 ,  90   j  and rotation thereof by the drive motors  18  allows the casing string to be reamed into the wellbore  77 . 
     Alternatively, the casing string  90  may be drilled into the formation  86 , thereby simultaneously extending the wellbore  77  and deploying the casing string into the wellbore. 
       FIGS. 13A and 13B  illustrate the cementing unit  1   s  of the top drive system  1 . The cementing unit  1   s  may include the coupling  15 , the fill up valve  50   f  and actuator  50   a  (repurposed as a top drive isolation valve), an adapter  99 , the genset  51 , the frame  58 , the hydraulic passages  49 , and a cementing head  88 . The cementing head  88  may include a cementing swivel  88   v , a launcher  88   h , a release plug, such as a dart  89 , and a dart detector. The adapter  99  may similar to the adapter  48  except for having a lower connector, such as a threaded coupling, suitable for mating with the cementing head  88 . 
     The cementing swivel  88   v  may include a housing torsionally connected to the drive body  22  or derrick  7   d , such as by an arrestor (not shown). The cementing swivel  88   v  may further include a mandrel and bearings for supporting the housing from the mandrel while accommodating rotation of the mandrel. An upper end of the mandrel may be connected to a lower end of the adapter  99 , such as by threaded couplings. The cementing swivel  88   v  may further include an inlet formed through a wall of the housing and in fluid communication with a port formed through the mandrel and a seal assembly for isolating the fluid communication between the inlet and the port. The mandrel port may provide fluid communication between a bore of the cementing head  88  and the housing inlet. 
     The launcher  88   h  may include a body, a deflector, a canister, a gate, the actuator, and a crossover. The body may be tubular and may have a bore therethrough. An upper end of the body may be connected to a lower end of the cementing swivel  88   v , such as by threaded couplings, and a lower end of the body may be connected to the crossover, such as by threaded couplings. The canister and deflector may each be disposed in the body bore. The deflector may be connected to the cementing swivel mandrel, such as by threaded couplings. The canister may be longitudinally movable relative to the body. The canister may be tubular and have ribs formed along and around an outer surface thereof. Bypass passages (only one shown) may be formed between the ribs. The canister may further have a landing shoulder formed in a lower end thereof for receipt by a landing shoulder of the adapter. The deflector may be operable to divert fluid received from a cement line  92  ( FIG. 14 ) away from a bore of the canister and toward the bypass passages. The crossover may have a threaded coupling, such as a threaded pin, formed at a lower end thereof for connection to a work string  91  ( FIG. 14 ). 
     The dart  89  may be disposed in the canister bore. The dart  89  may be made from one or more drillable materials and include a finned seal and mandrel. The mandrel may be made from a metal or alloy and may have a landing shoulder and carry a landing seal for engagement with the seat and seal bore of a wiper plug (not shown) of the work string  91 . 
     The gate of the launcher  88   h  may include a housing, a plunger, and a shaft. The housing may be connected to a respective lug formed in an outer surface of the launcher body, such as by threaded couplings. The plunger may be radially movable relative to the body between a capture position and a release position. The plunger may be moved between the positions by a linkage, such as a jackscrew, with the shaft. The shaft may be connected to and rotatable relative to the housing. The actuator may be fluid driven, such as a hydraulic, motor, operable to rotate the shaft relative to the housing. The actuator may include an inlet and an outlet in fluid communication with the hydraulic manifold  56  via respective conduits  100   a,b.    
     In operation, when it is desired to launch the dart  89 , the console  62  may be operated to supply hydraulic fluid to the launcher actuator via a control line  56  extending to the control swivel  26  and a control line extending from the control swivel to the HPU manifold  60   m . The launcher actuator may then move the plunger to the release position. The canister and dart  89  may then move downward relative to the launcher body until the landing shoulders engage. Engagement of the landing shoulders may close the canister bypass passages, thereby forcing chaser fluid  98  ( FIG. 14 ) to flow into the canister bore. The chaser fluid  98  may then propel the dart  89  from the canister bore, down a bore of the crossover, and onward through the work string  91 . 
     Alternatively, the control swivel  26  and launcher actuator may be pneumatic or electric. Alternatively, the launcher actuator may be linear, such as a piston and cylinder. Alternatively, the launcher  88   h  may include a main body having a main bore and a parallel side bore, with both bores being machined integral to the main body. The dart  89  may be loaded into the main bore, and a dart releaser valve may be provided below the dart to maintain it in the capture position. The dart releaser valve may be side-mounted externally and extend through the main body. A port in the dart releaser valve may provide fluid communication between the main bore and the side bore. In a bypass position, the dart  89  may be maintained in the main bore with the dart releaser valve closed. Fluid may flow through the side bore and into the main bore below the dart via the fluid communication port in the dart releaser valve. To release the dart  89 , the dart releaser valve may be turned, such as by ninety degrees, thereby closing the side bore and opening the main bore through the dart releaser valve. The chaser fluid  98  may then enter the main bore behind the dart  89 , thereby propelling the dart into the work string  91 . 
     The dart detector may include one or more ultrasonic transducers, such as an active transducer  88   a  and a passive transducer  88   p . Each transducer  88   a,p  may include a respective: bell, a knob, a cap, a retainer, a biasing member, such as compression spring, a linkage, such as a spring housing, and a probe. Each bell may have a respective flange formed in an inner end thereof for longitudinal and torsional connection to an outer surface of the crossover, such as by one or more respective fasteners. The transducers  88   a,p  may be arranged on the crossover in alignment and in opposing fashion, such as being spaced around the crossover by one hundred eighty degrees. Each bell may have a cavity formed in an inner portion thereof for receiving the respective probe and a smaller bore formed in an outer portion thereof for receiving the respective knob. 
     Each knob may be linked to the respective bell, such as by mating lead screws formed in opposing surfaces thereof. Each knob may be tubular and may receive the respective spring housing in a bore thereof. Each knob may have a first thread formed in an inner surface thereof adjacent to an outer end thereof for receiving the respective cap. Each knob may also have a second thread formed in an inner surface thereof adjacent to the respective first thread for receiving the respective retainer. 
     Each spring housing may be tubular and have a bore for receiving the respective spring and a closed inner end for trapping an inner end of the spring therein. An outer end of each spring may bear against the respective retainer, thereby biasing the respective probe into engagement with the outer surface of the crossover. A compression force exerted by the spring against the respective probe may be adjusted by rotation of the knob relative to the respective bell. Each knob may also have a stop shoulder formed in an inner surface and at a mid-portion thereof for engagement with a stop shoulder formed in an outer surface of the respective spring housing. 
     Each probe may include a respective: shell, jacket, backing, vibratory element, and protector. Each shell may be tubular and have a substantially closed outer end for receiving a coupling of the respective spring housing and a bore for receiving the respective backing, vibratory element, and protector. Each bell may carry one or more seals in an inner surface thereof for sealing an interface formed between the bell and the respective shell. Each seal may be made from an elastomer or elastomeric copolymer and may additionally serve to acoustically isolate the respective probe from the respective bell. Each bell and each shell may be made from a metal or alloy, such as steel or stainless steel. Each backing may be made from an acoustically absorbent material, such as an elastomer, elastomeric copolymer, or acoustic foam. The elastomer or elastomeric copolymer may be solid or have voids formed throughout. 
     Each vibratory element may be a disk made from a piezoelectric material, such as natural crystal, synthetic crystal, electroceramic, such as perovskite ceramic, a polymer, such as polyvinylidene fluoride, or organic nanostructure. A peripheral electrode may be deposited on an inner face and side of each vibratory element and may overlap a portion of an outer face thereof. A central electrode may be deposited on the outer face of each vibratory element. A gap may be formed between the respective electrodes and each backing may extend into the respective gap for electrical isolation thereof. Each electrode may be made from an electrically conductive material, such as gold, silver, copper, or aluminum. Leads, such as wires, may be connected to the respective electrodes and combine into a cable for extension to an electrical coupling connected to the bell. Each pair of wires or each cable may extend through respective conduits formed through the backing and the shell. Each backing may be bonded or molded to the respective vibratory element and electrodes. Electric cables  100   c,d  may connect the electrical couplings of the respective transducers  88   a,p  to the microcontroller MCU. 
     The protector may be bonded or molded to the respective peripheral electrode. Each jacket may be made from an injectable polymer and may bond the respective backing, peripheral electrode, and protector to the respective shell while electrically isolating the peripheral electrode therefrom. Each protector may be made from a polymer, such as an engineering polymer or epoxy, and also serve to electrically isolate the respective peripheral electrode from the crossover. 
       FIG. 14  illustrates cementing of the casing string  90  using the top drive system  1  in a cementing mode. As a shoe (not shown) of the casing string  90  nears a desired deployment depth of the casing string, such as adjacent a bottom of the lower formation, a casing hanger  90   h  may be assembled with the casing string  90 . Once the casing hanger  90   h  reaches the rig floor  7   f , the spider  75  may be set. 
     The casing unit  1   c  may be released from the motor unit  1   m  and replaced by the cementing unit  1   s  using the unit handler  4   u . The work string  91  may be connected to the casing hanger  90   h  and the work string extended until the casing hanger  90   h  seats in the wellhead  76   h . The work string  91  may include a casing deployment assembly (CDA)  91   d  and a stem  91   s , such as such as one or more joints of drill pipe connected together, such as by threaded couplings. An upper end of the CDA  91   d  may be connected a lower end of the stem  91   s , such as by threaded couplings. The CDA  91   d  may be connected to the casing hanger  90   h , such as by engagement of a bayonet lug (not shown) with a mating bayonet profile (not shown) formed the casing hanger. The CDA  91   d  may include a running tool, a plug release system (not shown), and a packoff. The plug release system may include an equalization valve and a wiper plug. The wiper plug may be releasably connected to the equalization valve, such as by a shearable fastener. 
     Once the cementing unit  1   s  has been connected to the motor unit  1   m , an upper end of the cement line  92  may be connected to an inlet of the cementing swivel  88   v . A lower end of the cement line  92  may be connected to an outlet of a cement pump  93 . A cement shutoff valve  92   v  and a cement pressure gauge  92   g  may be assembled as part of the cement line  92 . An upper end of a cement feed line  94  may be connected to an outlet of a cement mixer  95  and a lower end of the cement feed line may be connected to an inlet of the cement pump  93 . 
     Once the cement line  92  has been connected to the cementing swivel  88   v , the fill up valve  50   f  may be closed and the drive motors  18  may be operated to rotate the work string  91  and casing string  90  during the cementing operation. The cement pump  93  may then be operated to inject conditioner  96  from the mixer  95  and down the casing string  90  via the feed line  94 , the cement line  92 , the cementing head  88 , and a bore of the work string  91 . Once the conditioner  96  has circulated through the wellbore  77 , cement slurry  97  may be pumped from the mixer  95  into the cementing swivel  88   v  by the cement pump  93 . The cement slurry  97  may flow into the launcher  88   h  and be diverted past the dart  89  (not shown) via the diverter and bypass passages. 
     The technician may operate the control console  62  to send a command signal to the microcontroller MCU during pumping of cement slurry  97 . The command signal may instruct the dart detector to switch to an initialization mode for establishing a baseline. The microcontroller MCU may transmit input voltage pulses at an ultrasonic frequency to the active transducer  88   a  and record the amplitude and time of the transmission for each input voltage pulse. The active transducer  88   a  may then convert the voltage pulses into ultrasonic pulses. The ultrasonic pulses may travel through the adjacent crossover wall, through fluid contained in/flowing therethrough, and through the distal crossover wall to the passive transducer  88   p . The passive transducer  88   p  may convert the received ultrasonic pulses into raw voltage pulses and supply the raw voltage pulses to the microcontroller MCU. The microcontroller MCU may refine the raw voltage pulses into output voltage pulses and calculate an amplitude ratio of each output pulse to the respective input pulse and calculate the transit time of each output pulse. The microcontroller MCU may then supply the calculated data to the transmitter TX for sending to the control console  62  via the antenna  55   a . A programmable logic controller (PLC) of the control console  62  may process the data to determine the baseline. 
     Once the desired quantity of cement slurry  97  has been pumped, the dart  89  may be released from the launcher  88   h  by operating the launcher actuator. The chaser fluid  98  may be pumped into the cementing swivel  88   v  by the cement pump  93 . The chaser fluid  98  may flow into the launcher  88   h  and be forced behind the dart  89  by closing of the bypass passages, thereby launching the dart. 
     Passing of the dart  89  through the dart detector may substantially decrease amplitudes of the baseline voltage pulses to reduced amplitude voltage pulses. The amplitude reduction may be caused by a substantial difference in acoustic impedance between the dart mandrel and the cement slurry  97  reflecting a portion of the pulses back toward the active transducer  88   a . Passing of the dart  89  through the dart detector may substantially decrease the baseline transit times to faster transit times. The transit time reduction may be caused by increased acoustic velocity of the dart mandrel relative to the cement slurry  97 . The control console  62  may detect passage of the dart  89  using either or both criteria and indicate successful launch of the dart by a visual indicator, such as a light or display screen. 
     Pumping of the chaser fluid  98  by the cement pump  93  may continue until residual cement in the cement line  92  has been purged. Pumping of the chaser fluid  98  may then be transferred to the mud pump  78  by closing the valve  92   v  and opening the fill up valve  50   f . The dart  89  and cement slurry  97  may be driven through the work string bore by the chaser fluid  98 . The dart  89  may land onto the wiper plug and continued pumping of the chaser fluid  98  may increase pressure in the work string bore against the seated dart  89  until a release pressure is achieved, thereby fracturing the shearable fastener. Continued pumping of the chaser fluid  98  may drive the dart  89 , wiper plug, and cement slurry  97  through the casing bore. The cement slurry  97  may flow through a float collar (not shown) and the shoe of the casing string  90 , and upward into the annulus. 
     Pumping of the chaser fluid  98  may continue to drive the cement slurry  97  into the annulus until the wiper plug bumps the float collar. Pumping of the chaser fluid  98  may then be halted and rotation of the casing string  90  may also be halted. The float collar may close in response to halting of the pumping. The work string  91  may then be lowered to set a packer of the casing hanger  90   h . The bayonet connection may be released and the work string  91  may be retrieved to the rig  1   r.    
     Alternatively, for a liner operation (not shown) or a subsea casing operation, the drilling unit  1   d  may be used again after the casing or liner string is assembled for assembling the work string used to deploy the assembled casing or liner string into the wellbore  77 . The top drive system  1  may be shifted back to the drilling mode for assembly of the work string. The work string may include a casing or liner deployment assembly and a string of drill pipe such that the drilling unit  1   d  may be employed to assemble the pipe string. The motor unit  1   m  may be operated for reaming the casing or liner string into the wellbore  77 . 
       FIG. 15  illustrates cementing of the casing string  90  using an alternative cementing unit  101 , according to another embodiment of the present disclosure. The alternative cementing unit  101  may include the coupling  15 , the fill up valve  50   f  and actuator  50   a  (repurposed as an IBOP), the adapter  99 , the genset  51 , the frame  58 , the hydraulic passages  49 , and a modified cementing head. The modified cementing head may include the launcher  88   h , a release plug, such as the dart  89 , and the dart detector. The alternative cementing unit  101  may be similar to the cementing unit  1   s  except for omission of the cementing swivel  88   v.    
     To accommodate omission of the cementing swivel  88   v , a flow tee and shutoff valve  102  may be assembled as part of the standpipe  79  and the upper end of the cement line  92  may be connected to the flow tee. During the cementing operation, the shutoff valve  102  may be closed and the conditioner  96  and cement slurry  97  may be pumped by the cement pump  93  and through the cement line  92 , mud hose, motor unit  1   m , alternative cementing unit  101 , work string  91 , and casing string  90 . Once the cement line  92  has been purged by the chaser fluid  98 , the shutoff valve  92   v  may be closed and the shutoff valve  102  opened and the cementing operation may proceed as discussed above. 
     Alternatively, either cementing unit  1   s ,  101  may have a position sensor instead of or in addition to the dart detector and for verifying that the launcher actuator has properly moved the plunger to the release position. 
     Alternatively, the casing unit  1   c  and/or either cementing unit  1   s ,  101  may have its own control swivel and the hydraulic junction  36  may be omitted. 
     Alternatively, the motor unit  1   m  may have a wireless data link for relaying communication between the control console  62  and the control unit  55 . 
     Alternatively, the fluid driven motor  52 , gearbox  53 , electric generator  54 , and power converter  55   c  may be omitted and the battery  55   b  may have sufficient energy capacity to operate the casing unit  1   c  and/or either cementing unit  1   s ,  101  during the respective operations. 
     Alternatively, the genset  51  may further include an air compressor driven by the fluid driven motor  52  or the genset may include an electric motor for driving the air compressor. 
     Alternatively, the genset  51  may be used with any other accessory tool, such as a drilling unit, a completion tool, a wireline tool, a fracturing tool, a pump, or a sand screen. 
     In one embodiment, a system includes an accessory tool selected from a group consisting of a casing unit, a cementing unit, and a drilling unit; and a genset mounted to the accessory tool and comprising: a fluid driven motor having an inlet and an outlet for connection to a control swivel of the system; an electric generator connected to the fluid driven motor; a manifold having an inlet for connection to the control swivel and an outlet connected an accessory tool actuator; and a control unit in communication with the electric generator and the manifold and comprising a wireless data link. 
     In one or more embodiments described herein, the fluid driven motor is hydraulic. 
     In one or more embodiments described herein, the system also includes a fill up valve for opening and closing a bore of the accessory tool; and a fill up valve actuator for operating the fill up valve and connected to the outlet of the manifold. 
     In one or more embodiments described herein, the fill up valve actuator comprises a position sensor in communication with the control unit for monitoring operation of the fill up valve actuator. 
     In one or more embodiments described herein, the genset further comprises a gearbox connecting the fluid driven motor to the electric generator. 
     In one or more embodiments described herein, the fluid driven motor is a gerotor, the gearbox is a planetary gearbox, and the electric generator is a permanent magnet generator. 
     In one or more embodiments described herein, the wireless data link comprises an antenna. 
     In one or more embodiments described herein, the control unit further comprises at least one of: a power converter in electrical communication with the electric generator; a battery in electrical communication with the power converter; a microcontroller in electrical communication with the battery; a transmitter in electrical communication with the microcontroller and the antenna; and a receiver in electrical communication with the microcontroller and the antenna. 
     In one or more embodiments described herein, the control swivel is located on a motor unit of the system, the system further comprising: a rail for connection to a drilling rig; and the motor unit, comprising: a drive body; a drive motor having a stator connected to the drive body; a trolley for connecting the drive body to the rail; a drive ring torsionally connected to a rotor of the drive motor; and a swivel frame connected to the drive body and the control swivel. 
     In one or more embodiments described herein, the motor unit further comprises: a becket for connection to a hoist of the drilling rig; a mud swivel connected to the swivel frame; and a down thrust bearing for supporting the drive ring for rotation relative to the drive body. 
     In one or more embodiments described herein, the system also includes a unit handler locatable on or adjacent to a structure of the drilling rig and operable to retrieve the accessory tool from a rack and deliver the accessory tool to the motor unit. 
     In one or more embodiments described herein, the unit handler comprises: an arm; and a holder releasably connected to the arm and operable to carry the accessory tool. 
     In one or more embodiments described herein, the unit handler further comprises a pipe clamp releasably connected to the arm and operable to carry a casing joint or liner for delivery to the accessory tool. 
     In one or more embodiments described herein, the unit handler further comprises: a base for mounting the unit handler to a subfloor structure of the drilling rig; a post extending from the base to a height above a floor of the drilling rig; a slide hinge transversely connected to the post; and the arm connected to the slide hinge and comprising a forearm segment, an aft-arm segment, and an actuated joint connecting the arm segments. 
     In one or more embodiments described herein, the accessory tool is the casing unit; the casing unit comprises a clamp comprising: a set of grippers for engaging a surface of a casing joint; and a clamp actuator for selectively engaging and disengaging the set of grippers with the casing joint; the genset is mounted to the clamp; and the accessory tool actuator is the clamp actuator. 
     In one or more embodiments described herein, the casing unit further comprises a stab seal connected to the clamp for engaging an inner surface of the casing joint. 
     In one or more embodiments described herein, the clamp comprises a position sensor in communication with the control unit for monitoring operation of the clamp actuator. 
     In one or more embodiments described herein, the control swivel is located on a motor unit of the system, and the casing unit further comprises a coupling connected to the clamp and having a head with a latch profile for mating with a latch profile of the motor unit and having a plurality of fluid connectors for mating with fluid connectors of the motor unit. 
     In one or more embodiments described herein, the accessory tool comprises the cementing unit; the cementing unit comprises a cementing head comprising a launcher; the genset is mounted to the cementing head; and the accessory tool actuator is the launcher. 
     In one or more embodiments described herein, the cementing head further comprises a dart detector in communication with the control unit and for monitoring launching of a plug. 
     In one or more embodiments described herein, the dart detector comprises: an active transducer mounted to an outer surface of the launcher and operable to generate ultrasonic pulses; a passive transducer mounted to the outer surface of the launcher and operable to receive the ultrasonic pulses. 
     In one or more embodiments described herein, the cementing head further comprises a cementing swivel for allowing rotation of a tubular string during cementing. 
     In one or more embodiments described herein, the cementing swivel comprises: a housing having an inlet formed through a wall thereof for connection of a cement line; a mandrel having a port formed through a wall thereof in fluid communication with the inlet of the housing; a bearing for supporting rotation of the mandrel relative to the housing; and a seal assembly for isolating the fluid communication between the inlet of the housing and the port of the mandrel. 
     In one or more embodiments described herein, the launcher comprises: a launcher body connected to the mandrel of the cementing swivel; a dart disposed in the launcher body; and a gate having a portion extending into the launcher body for capturing the dart therein and movable to a release position allowing the dart to travel past the gate. 
     In one or more embodiments described herein, the launcher comprises a plunger movable between a capture position and a release position, wherein the launcher is operable to keep a plug retained therein in the capture position while allowing fluid flow therethrough, and to allow the fluid flow to propel the plug in the release position. 
     In one or more embodiments described herein, the control swivel is located on a motor unit of the system, and the cementing unit further comprises a coupling connected to the cementing head and having a head with a latch profile for mating with a latch profile of the motor unit and having a plurality of fluid connectors for mating with fluid connectors of the motor unit. 
     In one or more embodiments described herein, the system also includes an internal blowout preventer controlled by a second control unit at the accessory tool and powered by the genset. 
     In one embodiment, a casing unit for a top drive system includes a clamp and a genset mounted to the clamp. The clamp includes a set of grippers for engaging a surface of a casing joint; and a clamp actuator for selectively engaging and disengaging the set of grippers with the casing joint. The genset includes a fluid driven motor having an inlet and an outlet for connection to a control swivel of the top drive system; an electric generator connected to the fluid driven motor; a manifold having an inlet for connection to the control swivel and an outlet connected to the clamp actuator; and a control unit in communication with the electric generator and the manifold and having a wireless data link. 
     In another embodiment, a casing unit for a top drive system includes a clamp and an assembly mounted to the clamp. The clamp includes a set of grippers for engaging a surface of a casing joint; and a clamp actuator for selectively engaging and disengaging the set of grippers with the casing joint. The assembly includes a manifold having an inlet for connection to a control swivel of the top drive system and an outlet connected to the clamp actuator; and a control unit in communication with the manifold and having a battery and a wireless data link. 
     In another embodiment, a cementing unit for a top drive system includes a cementing head and a genset mounted to the cementing head. The cementing head includes a launcher: operable between a capture position and a release position, operable to keep a plug retained therein in the capture position while allowing fluid flow therethrough, and operable to allow the fluid flow to propel the plug in the release position. The genset includes a fluid driven motor having an inlet and an outlet for connection to a control swivel of the top drive system; an electric generator connected to the fluid driven motor; a manifold having an inlet for connection to the control swivel and an outlet connected to the launcher; and a control unit in communication with the electric generator and the manifold and having a wireless data link. 
     While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope of the invention is determined by the claims that follow.