Abstract:
The present invention provides an apparatus for attachment to pipe handling arm, comprising a clamp for gripping a tubular and a guide for aligning said tubular with another tubular prior to connection thereof, characterized in that said clamp and said guide are movable relative to each other in a direction longitudinal of the tubular, the arrangement being such that said tubular can be brought closer to said another tubular in a direction longitudinal of the tubular.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation of U.S. patent application Ser. No. 09/600,764, filed Sep. 19, 2000 U.S. Pat. No. 6,550,128 which is a 371 of PCT/GB99/00432 filed Feb. 11, 1999. The aforementioned related patent application is herein incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   Field of the Invention 
   Embodiments of the present invention generally relate to an apparatus or attachment to a pipe handling arm and to a method of handling a tubular. 
   SUMMARY OF THE INVENTION 
   Pipe handling apparatus generally comprises a pipe handling arm and a clamp. The pipe handling arm is fixed at one end to a derrick or to a rig floor of a drilling rig. The other end of the pipe handling arm is free to move in at least one plane, and usually two or three planes. The clamp is attached to the free end of the pipe handling arm In use, the free end of the pipe handling arm is swung over to a pipe rack. The clamp clamps on to a tubular and then picks the tubular up and maneuvers it into a position generally over an upper section of a tubular string at the well centre. Typically the tubulars are not in perfect alignment due to tolerance in the pipe handling arm. In order to ensure correct alignment a stabbing guide is then strapped around the threaded box of the upper section of the tubular string. The threaded pin of the tubular is then lowered into the threaded box of the upper section of the tubular string, and is guided into alignment therewith by the stabbing guide. 
   Although it only takes a relatively short time to mount and remove a stabbing guide it would be desirable to reduce this time because of the high costs associated with the running of a drilling rig. 
   In order to reduce this problem the present invention provides a clamp for gripping a tubular, characterised in that said apparatus further comprises means for, in use, aligning said tubular with another tubular prior to connection thereof. 
   The tubulars could be casing, liner or other type of pipe and especially large diameter tubulars, for example 36″ casing. 
   Preferably, said means comprises a guide. 
   Advantageously, said clamp and said guide are movable in relation to each other, the arrangement being such that, in use, said tubular can be brought closer to said another tubular. 
   Preferably, said clamp and said guide are arranged on a strut. 
   Advantageously, at least one of said clamp and said guide is movable along said strut by a hydraulic piston and cylinder. 
   Alternatively, at least one of said clamp and said guide is movable along said strut by a pneumatic piston and cylinder. 
   Preferably, said strut is divided into a first portion and a second portion and said second portion is offset from said first portion. 
   Advantageously, said apparatus further comprises a second clamp which is in a fixed relation to said clamp. 
   Preferably, said clamp(s) comprise jaws movable between an open and a closed position. 
   Advantageously, said apparatus further comprises a hydraulic piston to move said jaws between their open and closed positions. 
   Preferably, said jaws comprise cylindrical rollers, to facilitate rotation of said tubular whilst inhibiting axial movement thereof. 
   Advantageously, said apparatus comprises a lug for attachment to a pipe handling arm. 
   Preferably, said guide comprises a clamp. 
   The present invention also provides a pipe handling arm provided with an apparatus in accordance with the present invention. 
   The present invention also provides a method of handling a tubular to be connected to another tubular, which method comprises the steps of:
         gripping said tubular with an apparatus in accordance with the present invention, and   using said apparatus to align said tubular with said another tubular.       

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the present invention, reference will now be made, by way of example, to the accompanying drawings in which: 
       FIG. 1A  shows a top portion of an apparatus according to the present invention in use; and 
       FIG. 1B  shows a bottom portion of the apparatus according to the present invention in use. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to the drawings there is shown an apparatus which is generally identified by reference numeral  1 . 
   The apparatus  1  comprises a substantially vertical box-section upper strut  2  which has longitudinally spaced upper and lower clamping units  3  and  4  slidably mounted thereon. The upper and lower clamping units  3  and  4  are linked by a bar  5 . The upper clamping unit  3  is attached to the piston of a hydraulic piston and cylinder  7 . Activation of the hydraulic piston and cylinder  7  moves the upper and lower clamping units  3  and  4  along the upper strut  2 . 
   A substantially vertical box-section lower strut  8  is attached to the upper strut  2  by a plate  9 . The lower strut  8  is set back from the upper strut  2 . A guide in the form of a clamping unit  10  is arranged near the lower end of the lower strut  8 . 
   The apparatus  1  is connectable to a standard pipe handling arm (not shown) in place of the known clamping device described hereinbefore via lug  11 . 
   Each clamping unit  3 ,  4 ,  10  comprises two jaws  12 ,  13 ;  14 ,  15 ;  16 ,  17 ; each jaw  12  to  17  being pivotable about a respective pin  18 ,  19 ,  20 ,  21 ,  22 ,  23  by a hydraulic piston  24 ,  25 ,  26 . 
   Each jaw  12  to  17  comprises an upper plate  27  to  32  and a lower plate  33  to  38  which are separated by bolts  39  to  50  onto which cylindrical rollers  51  to  62  are mounted so that the longitudinal axis of the cylindrical rollers  51  to  62  is substantially perpendicular to the upper and lower plates  27  to  38 . 
   Each jaw  12  to  17  is attached to a lug  63 ,  64 ,  65 . Lugs  63  and  64  are welded to respective sleeves  66  and  67  which are slidalbly arranged on the upper strut  2 . Lug  65  is welded to an intermediary section  69  which in turn is welded to sleeve  68 . The sleeve  68  is fixed to the lower strut  8  by grub screws (not shown). The sleeve  68  may however be moved along lower strut  8 . The jaws  12  to  17  of the clamping units  3 ,  4 ,  10  are substantially in vertical alignment with each other, and preferably to within a tolerance of a few millimetres. 
   In use, the apparatus  1  is connected to a pipe handling arm via lug  11 . The pipe handling arm is generally movable in three planes. Such pipe handling arms are currently supplied by Varco BJ™ such as the PLS-3™ Automatic pick-up/Lay-downs system and Martine Hydraulics™ such as the Eagle™ and Eagle Light™ transfer system. 
   A tubular  70  to be connected to the upper end of a tubular string  71  is picked up by the jaws  12 ,  13 ,  14 ,  15  of the clamping units  3 ,  4  from a rack (not shown). The jaws  12 ,  13 ,  14 ,  15  of the clamping units  3 ,  4  move about pins  18 ,  19 ,  20 ,  21  by activation of the hydraulic pistons  24 ,  25 . The rollers  51  to  58  engage with the tubular  70 . The upper end of the tubular string  71  is held in a spider (not shown) in the rig floor (not shown). The tubular  70  is then brought into approximate alignment, for example within a few centimetres of the upper section of the tubular string  71  by manipulation of the pipe handling arm to which apparatus  1  is connected. 
   The jaws  16 ,  17  of the clamping unit  10  move about pins  22 ,  23  by activation of the hydraulic pistons  26  and rollers  55  to  58  move circumjacent and engage the upper section of the tubular string  71 . As the rollers  55  to  58  move into engagement with the tubular string  71  the tubular  70  moves into alignment with the tubular string  71 , such movement being permitted by the “slack” in the pipe handling arm. The tubular  70  is now in alignment  5  with the upper section of the tubular string  71  to preferably within a few millimetres. The tubular  70  can now be lowered by activating the hydraulic piston  7 . A threaded pin  72  of the tubular  70  locates in the threaded box  73  of the upper section of the tubular string  71 . 
   The lower strut  8  is set back from the tubular  70  and the upper section of the tubular string  71 , to allow a tong and a back-up tong (not shown) to be used to screw the threaded pin  72  into the threaded box  73  to make the connection. Alternatively, a top drive (not shown) on the derrick may be used to screw the threaded pin  72  into the threaded box  73 . The rollers  51  to  58  allow rotation of the tubular  70  whilst inhibiting a longitudinal movement thereof. 
   It is envisaged that various modifications may be  20  made to the preferred embodiment including replacing hydraulic piston  7  with a pneumatic piston, which, with the appropriate control apparatus, will be able to compensate for the weight of the tubular  70  and minimise potential damage to the threads as the tubular  70  is lowered into the threaded box  73 . 
   It should be noted that the clamp  10  could be replaced by a guide which could be slidable on the upper section of the tubular string  71  when closed thereabout. However, it is recommended that a clamp  10  should be used. 
   While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.