Abstract:
A coiled tubing directional drilling apparatus which is operated by a mud motor and is characterized by a fixed housing and a rotary steerable bent housing or sub which is selectively rotatable with respect to the fixed housing at a fixed angle bend by a shifting mechanism, typically operated by a reversible electric motor. The motor and shifting mechanism rotate with the drive shaft and employ a lead screw in a cross-nut arrangement that selectively engages and disengages a castle lock or power take-off drive system responsive to the direction of rotation of the motor, for effecting 360-degree rotation of the bent housing with respect to the fixed housing. A sun gear and pinion gear planetary gear system facilitate rotation of the bent housing with respect to the fixed housing at a slower speed than the drive train and bit box components of the device.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of and incorporates by reference prior filed copending U.S. Provisional Application Ser. No. 60/552,150, Filed Mar. 11, 2004. 

   SUMMARY OF THE INVENTION 
   This invention relates to directional drilling using coiled tubing and more particularly, to a coiled tubing directional drilling apparatus which is characterized by a fixed housing having one end connected to a length of coiled tubing and a rotatably steerable bent housing or sub extending from the opposite end of the fixed housing at a fixed angle. This mechanical configuration facilitates drilling in a selected direction responsive to operation of a drive train and drill bit which are typically operated by a mud motor located inside the fixed housing. The bent housing is caused to selectively rotate with, as well as with respect to, the fixed housing through a 360-degree range by operation of a clutch or shifting mechanism typically operated by an electric motor connected to a lead screw extending through a cross-nut that engages and disengages a castle lock or power take-off mechanism to and from an elongated sun gear. The elongated sun gear extends downwardly through the fixed housing for engagement with a set of companion pinion gears and sun gears in a planetary gear system to facilitate 360-degree rotation of the bent housing with respect to the fixed housing responsive to engagement of the castle lock or power take-off mechanism with the elongated sun gear. The planetary gears facilitate rotation of the bent housing to selected points on the 360-degree rotational path at a slower speed than the drive train of the drilling apparatus. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be better understood by reference to the accompanying drawings wherein: 
       FIG. 1  is a plan view of a typical operational embodiment of the coiled tubing directional drilling apparatus, illustrating suspension of the apparatus into a well bore by means of a length of coiled tubing extending from a coiled tubing coil mounted on a carrier; 
       FIG. 2  is a plan view of the coiled tubing directional drilling apparatus illustrated in  FIG. 1 , more particularly illustrating a substantially horizontal operation of the apparatus, also using the coiled tubing extending from a coiled tubing coil mounted on a carrier; 
       FIG. 3  is a longitudinal sectional view of a preferred embodiment of the coiled tubing directional drilling apparatus illustrated in  FIGS. 1 and 2 ; 
       FIG. 4  is a longitudinal sectional view of the upper portion of the coiled tubing directional drilling apparatus illustrated in  FIG. 3 ; 
       FIG. 5  is a cross-sectional view taken along line A′ of the coiled tubing directional drilling apparatus illustrated in  FIG. 4 , more particularly illustrating a mud motor component of the coiled tubing directional drilling apparatus; 
       FIG. 6  is a longitudinal sectional view of the upper mid-section of the coiled tubing directional drilling apparatus illustrated in  FIG. 3 , more particularly illustrating a pair of torque transfer universal, or CV joints therein; 
       FIG. 7  is a cross-sectional view taken along line B′ of the coiled tubing directional drilling apparatus illustrated in  FIG. 6 , more particularly illustrating lateral movement of the upper CV joint inside the CV housing; 
       FIG. 8  is a cross-sectional view taken along line C′ of the coiled tubing directional drilling apparatus illustrated in  FIG. 6 , more particularly illustrating substantial alignment of the lower CV joint in the CV housing; 
       FIG. 9  is a longitudinal sectional view of the lower mid-section of the coiled tubing directional drilling apparatus illustrated in  FIG. 3 , more particularly illustrating preferred shifting and pinion gear assemblies of the apparatus; 
       FIG. 10  is a sectional view of the lower section of the coiled tubing directional drilling apparatus illustrated in  FIG. 3 , more particularly illustrating the bent section, bit box and drill bit components of the apparatus; 
       FIG. 11  is an enlarged view of the clutch or shifting mechanism of the coiled tubing directional drilling apparatus illustrated in  FIG. 9 , more particularly illustrating castle lock apparatus components in disengaged configuration for non-rotation of the bent housing section of the apparatus with respect to the fixed housing; 
       FIG. 12  is an enlarged plan view, partially in section, of the electric motor and castle lock apparatus components of the shifting apparatus illustrated in  FIG. 11 ; 
       FIG. 13  is an enlarged view of the shifting mechanism of the coiled tubing directional drilling apparatus illustrated in  FIG. 9 , more particularly illustrating castle lock apparatus in engaged configuration for rotation of the bent housing section of the apparatus with respect to the fixed housing; 
       FIG. 14  is an enlarged view partially in section, of the electric motor and castle lock apparatus components of the shifting or clutch apparatus illustrated in  FIG. 11 ; 
       FIG. 15  is a cross-sectional view taken along line F′ of the coiled tubing directional drilling apparatus illustrated in  FIG. 9 , more particularly illustrating the mud bore, drive shaft, bushing, first or elongated sun gear, splined shaft, thrust bearing mount and shifting mechanism cross-nut components of the apparatus; 
       FIG. 16  is a cross-sectional view of the coiled tubing directional drilling apparatus taken along line H′ in  FIG. 9 , more particularly illustrating the set of middle pinion gears, gear housing (ring gear) and planetary gear components of the apparatus; and 
       FIG. 17  is an exploded view of two sets of the preferred pinion gear and sun gear components illustrated in  FIG. 9 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring initially to  FIGS. 1 and 3  of the drawings in a first operational configuration the coiled tubing directional drilling apparatus of this invention is generally illustrated by reference numeral  1  and is positioned in an offset leg  10 , which connects to the vertical leg  9  of a well bore  8 , extending from a horizontal surface  7 . The coiled tubing directional drilling apparatus  1  is attached to a length of coiled tubing  2  which extends downwardly into the well bore  8  from a tubing coil  3 , wound on a drum  4  which is rotatably attached to a carrier  6 , typically by means of a drive chain  5 . The coiled tubing  2  extends from the tubing coil  3  downwardly through the vertical leg  9  of the well bore  8  and into the offset leg  10 , where it connects to the top sub  12  of the coiled tubing directional drilling apparatus  1 , illustrated in  FIG. 3  of the drawings. A drill bit  50  is located at the extreme bottom end of the coiled tubing directional drilling apparatus  1  and is positioned at the end of the offset leg  10 , as further illustrated in  FIG. 1  of the drawings. 
   Referring now to  FIG. 2  of the drawings in another operational configuration the coiled tubing directional drilling apparatus  1  is set-up for horizontal boring, as it is positioned in the offset leg  10  extending from an angled leg  11  that projects from the horizontal surface  7 . As in the case of the configuration illustrated in  FIG. 1 , the coiled tubing directional drilling apparatus  1  is attached to a length of coiled tubing  2  that extends from a tubing coil  3 , rotatably mounted on a carrier  6  and typically operated by means of a drive chain  5  in conventional fashion. 
   Referring to  FIGS. 3-6  of the drawings in a preferred embodiment of the invention the coiled tubing directional drilling apparatus  1  is characterized by a top sub  12 , which is adapted to receive and mount the free end of a length of coiled tubing  2 , as illustrated in  FIGS. 1 and 2  of the drawings. The coiled tubing  2  can be attached to the top sub  12  in any convenient manner known to those skilled in the art. A top sub bore  13  extends through the center of the top sub  12  and the top sub  12  is typically threaded to the upper or top end of a stator tube  15  by means of threads  14 . The stator tube  15  is characterized by a stator tube bore  16  that receives the rubber transfer section  18  of a mud motor  17 . The rubber transfer section  18  is typically characterized by spirally-shaped transfer lobes  18   a  that correspond to the companion rotor lobes  15   b  ( FIG. 5 ) of a rotor  15   a , which is rotatably disposed in the stator tube bore  16  to complete the mud motor. Accordingly, a supply of drilling mud (not illustrated) pumped through the coiled tubing  2  into the top sub bore  13  and the stator tube bore  16 , and through a power annulus  20  defined by the rotor lobes  15   b  of the rotor  15   a  and the transfer lobes  18   a  of the rubber transfer section  18 , facilitates rotation of the rotor  15   a  in the rubber transfer section  18  to power the coiled tubing directional drilling apparatus  1 . The top end of a universal or CV housing  19  is typically attached to the bottom end of the stator tube  15  by additional threads  14  and the bottom end of the rotor  15   a  terminates in a mud annulus  21  that communicates with the CV housing bore  19   a . A CV joint top end  22   a  is attached to the narrowed bottom end of the rotor  15   a  and mounts a top CV joint  22 , as further illustrated in  FIGS. 3 and 6 . The top CV joint  22 , in turn, mounts a downwardly-extending CV drive shaft  24  that connects to a bottom CV joint  26 , also located in the CV housing bore  19   a  of the CV housing  19 , for alternating wobble in torque transition. Drilling mud flowing through a mud annulus  21 , extending the CV housing bore  19   a , is diverted around the bottom CV joint  26  and the CV joint bottom end  26   a , through the mud transfer passages  27  and into a mud bore  28 , all provided in a downward-extending top bearing drive shaft  30 . The top bearing drive shaft  30  is connected to or integrally formed with the CV joint bottom end  26   a  and is seated in a top bearing housing  31 , connected to the bottom end of the CV housing  19 , typically by additional threads  14 , and the seals  25  serve to seal the joint between the top bearing drive shaft  30  and the top bearing housing  31  above the bushing  34  ( FIG. 6 ). 
   Referring now to  FIGS. 3 ,  6  and  9  of the drawings a bearing drive shaft  32  is provided in the CV housing  19  and connects to the top bearing drive shaft  30 , typically by additional threads  14 , as further illustrated in  FIG. 3 . A top thrust bearing  33  is seated in the bottom end of the CV housing  19  and in the bearing drive shaft  32  at the top end of the shifting mechanism housing  36 , which is typically secured to the bottom end of the CV housing  19  by additional threads  14 . A bushing  34  is provided between the bearing drive shaft  32  and the upper end of the shifting mechanism housing  36  to facilitate reduced friction during rotation of the bearing drive shaft  32  with respect to the fixed shifting mechanism housing  36 . A seal  25  is also typically provided between the shifting mechanism housing  36  and the internal bearing drive shaft  32 , as further illustrated in  FIGS. 3 and 9 . 
   A shifting mechanism assembly  51  is mounted in the bearing drive shaft  32  for purposes which will be hereinafter further described and a gear housing  37  extends downwardly from threaded attachment at additional threads  14  to the bottom end of the shifting mechanism housing  36 , as further illustrated in  FIGS. 3 and 9 . A gear housing drive shaft  38  is attached to the bottom end of the bearing drive shaft  32 , typically by additional threads  14 , to facilitate continued rotation of the gear housing drive shaft  38  with the bearing drive shaft  32  and upper drive train, as hereinafter further described. 
   A pinion gear assembly  70  is provided in the coiled tubing directional drilling apparatus  1  below the shifting mechanism assembly  51  and between the gear housing  37 , having gear housing teeth  37   a  at the lower end, and the gear housing drive shaft  38 , for rotating a bent section  41 , 360-degrees, as further illustrated in  FIGS. 3 ,  9  and  16  of the drawings. Furthermore, a gear bearing housing  39  is secured to the bottom end of the gear housing  37  at the gear bearing housing teeth  39   a , to mount a bent section housing  41   a  and further accommodate the rotating gear housing drive shaft  38  ( FIGS. 3 and 9 ), as hereinafter described. A planet gear sub  40  also extends upwardly from the gear bearing housing  39  to the pinion gear assembly  70  ( FIG. 9 ) and is threaded on the bent section housing  41   a  by the planet gear sub threads  40   a  and the bent section housing threads  41   b.    
   Referring now to  FIGS. 3 ,  9  and  10  of the drawings, the bent section  41  extends downwardly from attachment to the planet gear sub  40  and encloses a pair of bent section universal or CV joints  43 , attached by a bent section CV joint connector  44 , which articulates between the bottom end of the gear housing drive shaft  38  and a correspondingly rotating bent section CV joint support  45 . As heretofore described, the bent section housing  41   a  is attached to the bottom end of the planet gear sub  40  ( FIG. 9 ) and a bit box  47  is secured inside a bit box sleeve  47   a , disposed inside the bit box housing  46 . The upper end of the bit box  47  is attached to the bent section CV joint mount  45 , seated in the bit box housing  46 , typically by threads  14  and a bit box thrust bearing  48  is also seated in the bit box housing  46  above the bit box sleeve  47   a . Bushings  34  are also provided in the bent section housing  41   a  and a drill bit  50  is attached to the rotating bit box  47 , which rotates at the speed of the mud motor rotor  15   a , as further illustrated in  FIGS. 3 and 10  of the drawings. 
   Referring now to  FIGS. 9 ,  11  and  12  of the drawings in one embodiment of the invention the shifting mechanism assembly  51  is illustrated in  FIG. 9  in non-engaging configuration, thus facilitating rotation of the mud motor drive train, which includes the rotor  15   a , the top bearing shaft  30 , the bearing drive shaft  32 , the gear housing drive shaft  38 , the bit box  47  and the drill bit  50 , without positional rotation of the bent section  41 , including the bent section housing  41   a . Accordingly, as further illustrated in  FIGS. 9 ,  11  and  12 , the shifting mechanism assembly  51  is characterized by a typically electric motor  52 , vertically mounted in and rotatable with the gear housing drive shaft  38  in a motor access  52   b  ( FIG. 9 ). The motor shaft  52   a , extending from the motor  52 , is connected to a lead screw  53  that extends through a lead screw guide  54 , fitted with lead screw guide bearings  53   a  at the top thereof. The lead screw  53  extends downwardly through a lead screw thrust bearing and housing  55  inside a shaft cap  61  ( FIG. 12 ) and threadably engages an internally-threaded cross-nut  56  ( FIGS. 11 and 12 ). A power take-off or castle lock apparatus is generally illustrated by reference numeral  60  and includes the shaft cap  61 , a top castle lock  64  and a bottom castle lock  67 , as further illustrated in  FIG. 12  of the drawings. The shaft cap  61  is fitted with shaft cap teeth  62  and shaft cap slots  63  that selectively engage the top castle lock slots  66  and top castle lock teeth  65 , respectively, as hereinafter further described. The bottom castle lock  67  includes an upper bottom castle lock  67   a , with upper bottom castle lock teeth  68  and a fixed lower bottom castle lock  69 , having companion lower bottom castle lock slots  69   a  for receiving the upper bottom castle lock teeth  68 . A castle lock thrust bearing and housing  57  is provided in a thrust bearing mount  59  located at the base of the castle lock apparatus  60 , to compensate for upward and downward thrusting of the lead screw  53  ( FIGS. 11 and 12 ). 
   Accordingly, referring again to  FIGS. 11 and 12  of the drawings under circumstances where the lead screw  53  is rotating in a selected first direction inside the cross-nut  56 , the top castle lock  64  and upper bottom castle lock  67   a  are moved downwardly ( FIG. 12 ) along with the thrust bearing mount  59  and the castle lock thrust bearings and housing  57  ( FIG. 11 ). This action disengages the respective shaft cap teeth  62  from the corresponding top castle lock slots  66 , as well as the top castle lock teeth  65  from the corresponding and opposite shaft cap slots  63  and engages the upper bottom castle lock teeth  68  with the lower bottom castle lock slots  69   a , to facilitate free rotation of the mud motor drive train defined above without corresponding independent rotation of the bent section  41  illustrated in  FIG. 10 , thus effectively locking the orientation of the bent section  41 . 
   Conversely, under circumstances where it is desired to positionally rotate the bent section  41  with respect to the shifting mechanism housing  36  in a 360-degree range of rotation using the mud motor drive train torque, the rotational direction of the lead screw  53  is reversed by reversing the rotation of the electric motor  52  and motor shaft  52   a  (typically remote control) to force the top castle lock  64  upwardly, along with the upper bottom castle lock  67   a , as illustrated in  FIGS. 13 and 14 , such that the respective shaft cap teeth  62  engage the corresponding top castle lock slots  66  and the top castle lock teeth  65  engage the aligned shaft cap slots  63 . This action effects rotation of the top castle lock  64  along with the upper bottom castle lock  67   a  and disengages the upper bottom castle lock  67   a  from the lower bottom castle lock  69 , which is fixed to the gear housing  37 , by removing the upper bottom castle lock teeth  68  from engagement with the aligned lower bottom castle lock slots  69   a . Rotation of the locked top castle lock  64  and the upper bottom castle lock  67   a  under these circumstances facilitates rotation of the first sun gear  49  due to the splined connection with the corresponding splined shaft  58  lying alongside the first sun gear  49  and engaging the thrust bearing mount  59  ( FIG. 15 ). 
   Referring now to  FIGS. 9 ,  16  and  17  of the drawings the planetary pinion gear assembly  70  illustrated in  FIG. 9  is designed to effect speed reduction in the 360-degree rotation of the bent section  41  and is further characterized by three sets of stacked pinion gears  71 , each stack of which is individually mounted on a pinion gear shaft  72 . The top array of pinion gears  71  engages the gear housing  37  at the gear housing teeth  37   a  and the first sun gear  49 , as illustrated in  FIG. 9 , such that the top array of pinion gears  71  are rotated in concert with the rotation of the first sun gear  49 . The second or middle array of pinion gears  71  also engage the ring gear or gear housing  37  at the gear housing teeth  37   a , as well as a second sun gear  73 , while the third and bottom array of pinion gears  71  engage the gear housing  37  at the gear housing teeth  37   a , and a third sun gear  74  ( FIG. 9 ). The third or bottom set of pinion gears  71  are located above the planetary gear sub  40  positioned above the gear bearing housing  39 . The pinion gears  71  operate to cause rotation of the planetary gear sub  40  and the entire bent section  41 , including the bent section housing  41   a , the bent section CV joint connector  45 , the bit box housing  46 , the bit box sleeve  47   a  and the bit box  47 , along with the drill bit  50 . Accordingly, it will be appreciated that due to the effect of the planetary gears described above, rotation of the motor  52  with the shaft cap  61  engaged with the top castle lock  64  ( FIG. 14 ), effects rotation of the entire bent section  41  at a speed less than the rotational speed of the mud motor drive train driving the drill bit  50 . However, the drive train rotational torque is used to effect this rotation and orient the entire bent section  41 , as well as the bit  50 , in a desired position on a 360-degree circle in the offset leg  10  of a well bore  8 , as illustrated in  FIGS. 1 and 2  of the drawings. It is understood that the speed of rotation of the bent section  41  is determined by the number and size of the pinion gears  71  in the planetary gear system described above. Typical gear ratios for the three pinion gears  71  is 2:1, 8:1 and 100:1, respectively, in non-exclusive particular. 
   Under circumstances where it is desired to terminate rotation of the bent section  41  at a selected point in the 360-degree circle described above, operation of the electric motor  52  is reversed, typically by radio control of the motor  52 , the shaft cap  61  is disengaged from the top castle lock  64 , while the upper bottom castle lock  67   a  of the bottom castle lock  67  is again engaged with the lower bottom castle lock  69  ( FIG. 12 ) to stop the bent section  41  rotation and facilitate drilling an alternative offset leg  10  in a new direction. It will be appreciated by those skilled in the art that the electric motor  52  clutch system can be replaced by a mud-operated, hydraulic or electro-magnetic system which accomplishes the same bent section  41  locking and unlocking function described above. 
   Accordingly, while the preferred embodiments of the invention have been described above, it will be recognized and understood that various modifications may be made in the invention and the appended claims are intended to cover all such modifications which may fall within the spirit and scope of the invention. 
   Having described my invention with the particularity set forth above: