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BACKGROUND 
     This invention relates to a system and method for transferring pipe between a storage device for the pipe and a pipe string extending over a well. 
     Hydraulic workover units for transferring pipe between a storage device and a pipe string extending over a well, or the like, are well known. These units traditionally have been limited to a series of winches and associated equipment, requiring heavy manual labor to deliver the pipe, via the winches, from a pipe rack to an elevated position for lowering into a work basket, or the like, for introduction into the well, and visa versa. Therefore, what is needed is a more automatic system that reduces the manual labor and the time involved in these type of operations. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an isometric view of a system for transferring pipe according to an embodiment of the invention. 
     FIG. 2 is a top plan view of the system of FIG.  1 . 
     FIG. 3 a  is a diagrammatic view of a pipe feeder of the system of FIG.  1 . 
     FIG. 3 b  is an elevational view of a component of the pipe feeder of FIG. 3 a.    
     FIG. 4 is an isometric view of a pipe shuttle of the system of FIG.  1 . 
     FIG. 5 a  is an diagramatic view of a mechanism for raising and lowering the pipe shuttle of FIG.  4 . 
     FIG. 5 b  is an diagramatic view of an alternate embodiment of the mechanism of FIG. 5 a.    
     FIGS. 5 c  and  5   d  are diagramatic views of another alternate embodiment of the mechanism of FIG. 5 a.    
     FIG. 6 is a diagrammatic view of a controller used in the system of FIG.  1 . 
     FIGS. 7 and 8 are views similar to FIGS. 1 and 2 respectively, but depicting an an alternate embodiment of the system of the present invention. 
     FIG. 9 is a view similar to FIGS. 1 and 7, but depicting another alternate embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION 
     Referring to FIGS. 1 and 2 of the drawings, the reference numeral  10  refers, in general, to a system for transferring pipe which is designed to operate in conjunction with a tower  20 . The tower  20  is designed to allow various drilling or workover operations to be performed on a well  22  which well may be an oil, a gas, or another type of well located onshore or offshore. For example, a typical operation of this type would be a snubbing operation according to which a plurality of tubulars, such as pipes, pipe joints, etc. are run into or out of the well  22 . 
     A deck  24  surrounds the well  22  and includes a platform  26  supported in a vertically spaced relation to the well  22  and the deck  24  by a plurality of support members  28 . The tower  20  is formed by a plurality of additional support members, or beams, extending substantially vertically from the platform  26 , along with several horizontal support members, or beams, attached to the vertical members. Since the tower  20  is conventional and does not, per se, form any part of the present invention, many details of the tower have been omitted in the interest of clarity. 
     The tower  20  and the platform  26  accommodate a substantially vertically extending pipe string  30  which passes through suitable openings formed in the tower  20  and the platform  26 . To this end, a mast  32  (shown partially in FIG. 1) is supported on the tower  20  and operates in a conventional manner to engage the pipe string  30  to enable it to be raised and lowered through the tower  20  and the well  22  in a conventional manner. A work basket  34  is attached to the tower  20  to permit various operations on the pipe string  30 , such as joining additional pipe joints to, and removing pipe joints from, the pipe string  30 , as will be described. 
     A plurality of pipe joints  40  are supported on a horizontally-extending rack  42  disposed adjacent the tower  20 , and the system  10  operates to engage a pipe joint  40  from the rack  42  and transfer it to the work basket  34  for attaching to the pipe string  30 ; and to transfer a pipe joint  40  from the pipe string  30  to the rack  42 , in a manner to be described. 
     A pipe feeder  44  is disposed on one side of the rack  42  for receiving the pipe joints  40  from the rack  42 . The pipe feeder  44  is shown partially in FIGS. 1 and 2 and details will be described later. The pipe feeder  44  functions to feed the pipe joints  40  between the rack  42  and a pipe lift  50  mounted for pivotal movement on the platform  26 . The pipe lift  50  is adapted to transfer the pipe joints  40  between the rack  42  and a shuttle  60  which is supported by the tower  20 , and the shuttle  60 , in turn, is adapted to transfer the pipe joints  40  between the pipe lift  50  and the work basket  34 . The pipe lift  50  and the shuttle  60  will also be described in detail later. 
     Details of the pipe feeder  44  are shown in FIGS. 3 a  and  3   b . The pipe feeder  44  includes a motor  70  configured to drive a shaft  72  which is supported between the motor  70  at one end and a bearing  74  at the other end. Star wheels  76  and  78  are disposed on the shaft  72  in a spaced relation for rotation with the shaft  72 , and the details of the star wheel  76  are shown in FIG. 3 b . More particularly, the outer circumference of the star wheel  76  is configured to define five angular-spaced recessed portions  76   a , each of which is adapted to receive a pipe joint  40  as shown, for example, in connection with one of the recessed portions  76   a  in FIG. 3 b . It is understood that the star wheel  78  is identical to the star wheel  76 , and the design is such that a pipe joint  40  will be received by corresponding recessed portions of both star wheels  76  and  78 . 
     Thus, the pipe feeder  44  can function to transfer a pipe joint  40  from the rack  42  to the pipe lift  50 . In this context, it is assumed that the pipe joints  40  are stacked, or otherwise arranged on the rack  42  so that they can sequentially fall from the rack  42  to the pipe feeder  44 . The motor  70  is activated to rotate the shaft  72  to allow a pipe joint  40  from the rack  42  to be received in the recessed portion  76   a  of the star wheel  76  and the corresponding recessed portion of the star wheel  78 . After a pipe joint  40  is received, continual rotation of the motor  70  causes the pipe joint  40  to move angularly relative to the shaft  72  until it rolls out of the recessed portion  76   a  and the corresponding recessed portion of the star wheel  78  and into pipe lift  50 . The motor  70  then pauses until the pipe lift  50  is ready to receive another pipe joint  40  and the operation can be repeated. 
     Also, the pipe feeder  44  can function to rotate the shaft  72  to transfer a pipe joint  40  from the pipe lift  50  to the rack  42 . In this mode, the motor  70  rotates the shaft  72  in a direction that is opposite to the direction of rotation in the previous mode to allow a pipe joint  40  from the pipe lift  50  to be received in one of the recessed portions  76   a  of the star wheel  76  and the corresponding recessed portion of the star wheel  78 . After a pipe joint  40  is received, continual rotation of the motor  70  causes the pipe joint  40  to move angularly relative to the shaft  72  until it rolls out of the recessed portion  76   a  of the star wheel  76  and the corresponding recessed portion of the star wheel  78  and onto the rack  42 . The motor  70  is then paused until the pipe lift  50  is ready to provide another pipe joint  40  and the operation is repeated. 
     As shown in FIGS. 1 and 2, one end is the pipe lift  50  is pivotally mounted to the deck  24  about a hinge  50   a , and a pair of pipe grips  52   a  and  52   b  are mounted in a spaced relation on the pipe lift  50 . It is understood that the pipe grips  52   a  and  52   b  are adapted to be actuated to move into and from a position in which they grip the pipe joint  40 , in a conventional manner. The pipe lift  50  moves between a substantially horizontal position shown by the solid lines in FIG. 1 in which a pipe joint  40  is transferred between the pipe lift  50  and the rack  42 , through an intermediate position shown by the phantom lines, and to an upright position extending at a slight angle to the vertical, also shown by the phantom lines. In the last position, the pipe lift  50  is adjacent the shuttle  60  so that a pipe joint  40  can be transferred between the pipe lift  50  and the shuttle  60 . It is understood that a conventional hydraulic cylinder, or the like, (not shown) is provided to pivot the pipe lift  50  about the hinge  50   a  between the above positions. 
     After the pipe joint  40  from the rack  42  is grasped by the pipe grips  52   a  and  52   b  and the pipe lift  50  is pivoted to transfer the pipe joint  40  to the shuttle  60 , the pipe joint  40  is released to the shuttle  60  by releasing the pipe grips  52   a  and  52   b . Likewise, when the pipe joint  40  from the shuttle  60  is grasped by the pipe grips  52   a  and  52   b  and the pipe lift  50  is pivoted to transfer the pipe joint  40  to the rack  42 , the pipe joint  40  is released to the shuttle  60  by releasing the pipe grips  52   a  and  52   b.    
     The shuttle  60  moves vertically along a set of rails  62   a  and  62   b  supported by the tower  20 , with the movement being between a lower position shown in FIG. 1 in which the shuttle  60  receives a pipe joint  40  from, or transfers a pipe joint  40  to, the pipe lift  50 ; and an upper position in which it receives a pipe joint  40  from, or transfers a pipe joint  40  to, an operator in the work basket  34 . 
     As shown in FIG. 4, the shuttle  60  includes a base  82  and a pair of spaced grips  84   a  and  84   b  mounted to one surface of the base  82  in a spaced relation. A trough  86  is also mounted to the latter surface of the base  82  and extends between the grips  84   a  and  84   b . Two spaced rollers  86   a  and  86   b  are provided on one side of the base  82  for engaging the rail  62   a , it being understood that two other rollers (not shown) are provided on the other side for engaging the rail  62   b . A bumper  88 , preferably of a relatively soft material, is disposed at one end of the base  82  for receiving an end of the pipe joint  40 . 
     When a pipe joint  40  is received from either the pipe lift  50  or from the work basket  34 , the pipe joint  40  is guided into position on the shuttle  60  by the trough  86 , with the bumper  88  providing a lower guide and absorbing some of the downward shock from the pipe joint  40 . It is understood that the grips  84   a  and  84   b  are adapted to be actuated to move into and from a position in which they grip the pipe joint  40 , in a conventional manner. 
     One embodiment of a mechanism for moving the shuttle  60  along the rails  62   a  and  62   b  between its lower position and its upper position is shown in detail in FIG. 5 a . The mechanism is referred to, in general, by the reference numeral  90  and includes a winch  94  and a cable  96  connected between the winch  94  and the shuttle  60  and extending around a pulley  100 . The winch  94  is powered in a conventional manner and rotates in one direction to take up the cable  96  and raise the shuttle  60  on the rails  62   a  and  62   b  using the pulley  100 , and also rotates in an opposite direction to release the cable  96  and permit the shuttle  60  to be lowered on the rails  62   a  and  62   b  by gravity. Although not shown in FIGS. 1-3 in the interest of clarity, it is understood that the mechanism  90  can be supported by the tower  20  in any conventional manner. 
     FIG. 5 b  illustrates another embodiment of a mechanism for moving the shuttle  60  along rails  62   a  and  62   b , which embodiment is referred to in general by the reference numeral  102 , and includes several components of the embodiment of FIG. 5 a  which are given the same reference numerals. According to the embodiment of FIG. 5 b , the winch  94  of the embodiment of FIG. 5 a  is replaced by a hydraulic cylinder  106  including a reciprocal rod  106   a  having a pulley  108  mounted to its distal end. The cable  96  is connected at one end to the shuttle  60 , extends around the pulleys  100  and  108 , and is connected at its other end to a fixed structure. The hydraulic cylinder  106  can be activated to move the rod  106   a  downwardly in a conventional manner to take up the cable  96  and raise the shuttle  60  on the rails  62   a  and  62   b  using the pulleys  100  and  108 , and to move the rod  106   a  upwardly to create slack in the cable  96  so that the shuttle  60  is lowered on the rails  62   a  and  62   b  by gravity. Although not shown in FIGS. 1 and 2 in the interest of clarity, it is understood that the mechanism  102  can be supported by the tower  20  in any conventional manner. 
     FIGS. 5 c  and  5   d  illustrate another embodiment of a mechanism for moving the shuttle  60  along rails  62   a  and  62   b , which embodiment is referred to in general by the reference numeral  110  and includes several components of the embodiment of FIG. 5 b  which are given the same reference numerals. According to the embodiment of FIGS. 5 c  and  5   d , the pulley  108  of the embodiment of FIG. 5 b  is replaced by a set of pulleys  112 , and another set of pulleys  114  are mounted to a fixed structure in a spaced relation to the pulleys  112 . The cable  96  is connected at one end to the to the shuttle  60 , extends around the pulley  100 , and is wrapped around each pulley of the set of pulleys  112 . The cable  96  then extends to, and is wrapped around, each pulley of the set of pulleys  114 , and the other end of the cable is connected to one of the latter pulleys or to a fixed structure. The hydraulic cylinder  106  can thus be activated to move the rod  106   a  downwardly to take up the cable  96  and raise the shuttle  60  on the rails  62   a  and  62   b  using the pulleys  100 ,  112  and  114 . Also, the hydraulic cylinder  106  can be activated to move the rod  106   a  upwardly to create slack in the cable  96  and thus lower the shuttle  60  on the rails  62   a  and  62   b  by gravity. Although not shown in FIGS. 1 and 2 in the interest of clarity, it is understood that the mechanism  110  can be supported by the tower  20  in any conventional manner. 
     With reference to FIG. 6, a controller  116  is provided to control the operation of the pipe feeder  44 , the pipe lift  50 , the aforementioned hydraulic cylinder  106  that controls the movement of the pipe lift  50 , the shuttle  60 , and the mechanism  90  (or  102  or  110 ). The controller  116  includes a switch  120  to select whether the system  10  raises the pipe joints  40  to, or lowers the pipe joints  40  from, the work basket  34 . After the switch  120  is set to a desired position, a control  122  may be selected to cause the system  10  to cycle through the operations described above according to which the pipe joints  40  are either transferred from the rack  42  to the work basket  34 , or vice versa. The controller  116  also includes a switch  124  to stop the shuttle  60 , a switch  125  to raise the shuttle  60 , a switch  126  to lower the shuttle  60 , and a switch  127  to cause an emergency stop of the system  10 . Since the electrical components of the controller  116 , including the above-mentioned switches, are conventional, the controller will not be described in any further detail. 
     In operation of the system  10 , the controller  116  is provided to a worker on the work basket  34  and, assuming that it is desired to transfer some pipe joints  40  from the rack  42  to the pipe string  30 , the switches  120  and  122  are tripped. This activates the motor  70  of the pipe feeder  44  so that it receives a pipe joint  40  from the rack  42 , and transfers it to the horizontally disposed pipe lift  50  as described above. The motor  70  then pauses until the pipe lift  50  is ready to receive another pipe joint  40  and the operation is repeated. 
     The pipe grips  52   a  and  52   b  of the pipe lift  50  are activated to grasp the pipe joint  40 , and the above-mentioned hydraulic cylinder  106  is activated to pivot the pipe lift  50  from its horizontal position shown by the solid lines in FIGS. 1-3 to its upright position shown by the phantom lines in FIG. 1 adjacent the tower  20 . The pipe grips  52   a  and  52   b  are then released and the grips  84   a  and  84   b  of the shuttle  60  are activated to grip the pipe joint  40 . 
     The mechanism  90  (FIG. 5 a ), is then activated to move the shuttle  60  vertically along the rails  62   a  and  62   b  until it reaches its upper position near the work basket  34 . A worker at the work basket  34  receives the pipe joint  40  and attaches a lifting device (not shown) such as a cable operated in conjunction with the mast  32  to the pipe joint  40 . The grips  84   a  and  84   b  of the shuttle  60  are released, and the above lifting device raises the pipe joint  40  to allow the bottom of the pipe joint  40  to be attached to the top of the pipe string  30  which is then lowered into the well  22  to allow another pipe joint  40  to be attached. During this movement of the shuttle  60  and the transfer of the pipe joint  40  to the pipe string  30 , the pipe lift  50  may be returned to its horizontal position shown in FIG. 1 to begin the next cycle. This cycle can then be repeated for a desired number of pipe joints  40 . Of course the above steps can be reversed if it is desired to transfer one or more pipe joints  40  from the pipe string  30  to the rack  42 . It is understood that either of the lifting mechanism  102  and  110  (FIGS. 5 b - 5   d ) can be used instead of the mechanism  90  in the above operations. 
     Alternates and Equivalents 
     According to the embodiment of FIGS. 7 and 8, a system  10   a  is provided which is similar to the above embodiment and includes many components of the above embodiment which are given the same reference numerals. According to the system  10   a , the pipe shuttle  60  and the rails  62   a  and  62   b  of the previous embodiment are replaced by a shuttle  140  and a single, upright, rail  138  connected to the tower  20  in any conventional manner. The shuttle  140  is similar to the shuttle  60  with the exception that it includes a pair of arms  144   a  and  144   b , respectively, that extend radially outwardly from the body of the shuttle  140 , as better shown in FIG.  8 . The arms  144   a  and  144   b  are adapted to rotate relative to the body of the shuttle  140  in a conventional manner. A pair of grips  146   a  and  146   b  are attached to distal ends of the arms  144   a  and  144   b , respectively, and are identical to the grips  84   a  and  84   b  of the shuttle  60 . It is understood that one of the lifting mechanisms  90 ,  102 , or  110  of FIGS. 5 a - 5   d  can be connected to the shuttle  140  to move it between a lower position and an upper position as shown in FIG.  7  and as described above, 
     With the shuttle  140  in its lower position, the grips  146   a  and  146   b  grasp the pipe joint  40  from the pipe lift  50  after the pipe lift  50  has reached its upright position described in connection with the previous embodiment. After receiving the pipe joint  40  from the pipe lift  50 , the lifting mechanism  90 ,  102 , or  110  is activated to raise the shuttle  140  to its upper position. The arms  144   a  and  144   b  are rotated to move pipe joint  40  angularly relative to the body of the shuttle  140  and deliver the pipe joint  40  to the work basket  34  at a point relatively close to the pipe string  30  as shown in connection with the upper position of the shuttle  140 . The above operation is reversed to transfer the pipe joints  40  from the pipe string  30  to the pipe lift  50 . Otherwise the operation of the system  10   a  is identical to that of the previous embodiment. 
     According to the embodiment of FIG. 9, a system  10   b  is provided which is similar to the embodiment of FIGS. 7 and 8 and includes many component of the latter embodiment which are given the same reference numerals. According to the system  10   b , the rail  138  of the embodiment of FIGS. 7 and 8 is replaced by a rail  142  which is identical to the rail  138  with the exception that it extends through, and substantially beyond, the work basket  34 . Therefore, the shuttle  140  carrying a pipe joint  40  can be raised to a position above the work basket  34  and the arms  144   a  and  144   b  rotated as described above, to move the pipe joint  40  directly above the pipe string  30  for connection to the pipe string  30  by a worker. Thus, according to this embodiment, the pipe joint  40  may be raised to a position to allow it to be attached to the pipe string  30  without the use of an additional lifting device as discussed in the previous embodiment. 
     It is understood that other variations may be made in the foregoing without departing from the scope of the invention. For example, the tower  20  can be replaced with other types of towers or support structures. Also, the systems described above can be converted to transfer two or more pipe joints  40  in each cycle. Further, although the controller  116  was described above as being located on the work basket  34 , it can be placed in other locations, and can be adapted to communicate with the systems  10   10   a  and  10   b  using wired or wireless devices. Still further, in the embodiments of FIGS. 7-9 the pipe joint  40  may be moved laterally to a position adjacent the work basket  34  in a manner other than that described above. 
     Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims.

Summary:
A system and method for transferring pipe according to which a pipe joint is positioned in a pipe lift in a first position and moved to a second position before being transferred from the pipe lift to a pipe shuttle and moved to a third position.