Abstract:
An apparatus for facilitating the connection of tubulars using a top drive, the apparatus comprising a stator attachable to said top drive, and a supporting member for supporting a tool, wherein means are provided to allow substantially horizontal movement of said supporting member.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to methods and apparatus for facilitating the connection of tubulars using a top drive and is more particularly, but not exclusively for facilitating the connection of a section or stand of casing to a string of casing. 
   2. Description of the Related Art 
   In the construction of wells such as oil or gas wells, it is usually necessary to line predrilled holes with a string of tubulars known as casing. Because of the size of the casing required, sections or stands of say two sections of casing are connected to each other as they are lowered into the well from a platform. The first section or stand of casing is lowered into the well and is usually restrained from falling into the well by a spider located in the platform&#39;s floor. Subsequent sections or stands of casing are moved from a rack to the well centre above the spider. The threaded pin of the section or stand of casing to be connected is located over the threaded box of the casing in the well to form a string of casing. The connection is made-up by rotation therebetween. 
   It is common practice to use a power tong to torque the connection up to a predetermined torque in order to perfect the connection. The power tong is located on the platform, either on rails, or hung from a derrick on a chain. However, it has recently been proposed to use a top drive for making such connection either alone or in combination with a power tong. 
   It has been observed that sections or stands of tubulars are often not as uniform as desired. In particular, the sections or stands of tubulars are often not straight. The top drive is in perfect alignment with the centre of the spider in the platform of an oil or gas rig. However, a section or stand of tubulars located in the spider would not always be in alignment with the top drive. 
   SUMMARY OF THE INVENTION 
   According to a first aspect of the present invention there is provided an apparatus for facilitating the connection of tubulars using a top drive, the apparatus comprising a stator attachable to said top drive, and a supporting member for supporting a tool wherein means are provided to allow substantially horizontal movement of said supporting member. 
   According to a second aspect of the present invention there is provided a method for facilitating the connection of tubulars using a top drive, the method comprising the steps of attaching a tool to the top drive using a supporting member and adjusting the supporting member to cause the tool to be displaced horizontally relative to the top drive. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the present invention and in order to show how the same may be carried into effect reference will now be made, by way of example, to the accompanying drawings, in which: 
       FIG. 1  is a side view in perspective of an apparatus in accordance with an embodiment of the invention in use; 
       FIG. 2  is an enlarged view of parts of  FIG. 1 , with parts inserted in a tubular and with parts cut away; 
       FIG. 3  is an enlarged cross-sectional view in perspective of part of the apparatus of  FIG. 1 ; 
       FIG. 4  is an enlarged view of parts of the supports of  FIG. 1  in a displaced position; 
       FIG. 5  is an enlarged view of parts of the apparatus of  FIG. 1  in a second displaced position; 
       FIG. 6  shows the apparatus of  FIG. 1  in a further stage of operation; and 
       FIG. 7  shows a second embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIG. 1  there is shown an apparatus which is generally identified by reference numeral  1 . 
   The apparatus I depends from a rotor  2 ′ of a top drive  3 . A tool  4  for gripping a tubular depends from the lower end of the apparatus  1 . A rigid guide member  5  is provided to guide the rotor  2  of the apparatus  1 . The rigid guide member  5  is fast with a stator  5 ′ of the top drive  3 . The rotor  2 ′ of the top drive  3  is coupled by a threaded connection to the rotor  2  of the apparatus  1 . The rigid guide member  5  may be provided with a clamp for clamping the rotor  2  of the apparatus I so that the threaded connection to the rotor  2 ′ of the top drive  3  can be made, after which the clamp would be released. 
   An elevator  6  is provided on the end of bails  7 ,  8  which are hung from the top drive  3 . Piston and cylinders  9 ,  10  are arranged between the bails  7 ,  8  and the top drive  3  for moving the elevator  6  from below the top drive  3  to an out of the way position. 
   Referring now to  FIG. 2 , there is shown the apparatus  1  which comprises a plate  11  which is fixed to a connecting tubular  12  by a collar  13 . The connecting tubular  12  passes through a hole  14  in rigid body  5  and connects with the rotor  2  ( FIG. 1 ). The plate  11  has two projections  15  and  16  which have holes  17  for accommodating axles  18  which are rotationally disposed therein. The axles  18  are integral with a rigid body  19 . A slider  20  is arranged on runners  21  on either side of the rigid body  19 . Arms  22  are connected at one end to the slider  20  via spherical bearings  23 . 
   The other end of arms  22  are connected to a supporting member  24  via spherical bearings  25 . 
   The arms  22  and are provided with lugs  26  to which one end of a piston and cylinder  28  and  29  is attached and are movable thereabout. The other end of each piston and cylinder  28  and  29  is attached to lugs  30  and  31  and is movable thereabout. The lugs  30  and  31  are fixed to plate  11 . 
   A mud pipe  32  is provided between the plate  11  and the supporting member  24  for carrying mud to the inside of a tubular therebelow. The mud pipe  32  is located in cylindrical sections  33  and  34  which are attached to the plate  11  and the supporting member  24 . The mud pipe  32  is provided with a lobe  35  formed on the outer surface thereof and is located in a corresponding recess  36  in a cylindrical section  33  ( FIG. 3 ). A lobe  37  is slidably arranged on the lower end of the mud pipe  32  with an O-ring seal  38  arranged therebetween to inhibit fluid from leaking therebetween. The lobe  37  is located in a corresponding recess  39  in cylindrical section  34 . This arrangement allows a ball and socket type movement between the plate  11  and the supporting member  24  and relative longitudinal movement therebetween. 
   Referring back to  FIG. 2 , a tool  4  for gripping a tubular is fixed and depends from the supporting member  24  of the apparatus  1 . Such a tool may be arranged to be inserted into the upper end of the tubular, with gripping elements of the tool being radially displaceable for engagement with the inner wall of the tubular so as to secure the tubular to the tool. 
   In use, a tubular  40  to be connected to a tubular string held in a spider (not shown), is located over the tool  4 . The tool  4  grips the tubular  40 . The apparatus  1  and the tubular  40  are lowered by moving the top drive so that the tubular  40  is in close proximity with the tubular string held in the spider. However, due to, amongst other things, manufacturing tolerances in the tubular  40 , the tubular often does not align perfectly with the tubular held in the spider. The apparatus  1  allows minor vertical and horizontal movements to be made. The piston and cylinders  28  and  29  allow vertical movement, and may be controlled remotely. The piston and cylinders  28  and  29  may be of the pneumatic compensating type, i.e. their internal pressure may be adjusted to compensate for the weight of the tubular  40  so that movement of the tubular may be conducted with minimal force. Pneumatic compensating piston and cylinders also reduce the risk of damage to the threads of the tubulars. This can conveniently be achieved by introducing pneumatic fluid into the piston and cylinders  28  and  29  and adjusting the pressure therein. The piston and cylinders  28  and  29  may be hydraulic or may be hydraulic and provided with pneumatic bellows. 
   Tubular manipulating equipment such as stabbing guides may be used to direct the pin (not shown) of the tubular  40  into the box of the tubular string held in the spider. The apparatus I allows horizontal movement of the tubular  40  relative to the top drive  3 . Once the tubular  40  is in line with the tubular string, the top of the tubular  40  may be brought in line with the top drive which may be carried out with pipe handling equipment. The top drive  3  is now in direct alignment with the tubular string held in the spider, and can now rotate the apparatus  1  and hence the tool  4  and the tubular  40  to perfect a connection between the tubular  39  and the tubular string. 
     FIG. 4  shows the supporting member  24 , the tool  4  and the tubular  40  laterally in a ‘Y’ direction out of alignment with the top drive  3 . The mud pipe  32  has moved in recesses  36  and  39  and longitudinally in relation to O-ring seals  38 . The piston and cylinders  28  and  29  have moved about lugs  26 ,  27 ,  30  and  31 . Arms  22  and  22 ′ have moved about spherical bearings  23 ,  23 ′,  25  and  25 ′. 
     FIG. 5  shows the supporting member  24 , the tool  4  and the tubular member  40  laterally in an ˜x′ direction. The mud pipe  32  has moved in recesses  36  and  39  and longitudinally in relation to O-ring seals  38 . The piston and cylinders  28  and  29  have moved about lugs  26 ,  27 ,  30  and  31 . Rigid member  19  has moved about axles  18  and  18 ′ and spherical bearings  23 . 
     FIG. 6  shows the elevator  6  swung in line with the top drive  3  by rotation of the piston and cylinders  9  and  10  acting on bails  7  and  8 . The elevator  3  is located below a box  41  of tubular  40 . The tubular  40  may be released from engagement with the tool  4 . The elevator  6  may now be raised to take the weight of the tubular  40  and tubular string. The tubular string may now be lowered into the well. 
     FIG. 7  is a second embodiment of the present invention and is generally similar to that of  FIGS. 1 to 6  further incorporating adjusting piston and cylinders  42  and  43  so that actuation of the piston and cylinders  42  and  43  can move the supporting member  24 , the tool  4  and the tubular  40  depending therebelow in a horizontal plane in an x and y axis. 
   The piston and cylinder  42  is arranged between the plate  11  and the rigid member  19  on lugs  44  and  45 . Actuation of the piston and cylinder  42  moves the supporting member  24 , the tool  4  and the tubular  40  along a generally x-axis about axles  18  and  18 ′. 
   The piston and cylinder  43  is arranged between an extension of arm  22  and slider  20  on lugs  46  and  47 . Actuation of the piston and cylinder  43  moves the supporting member  24 , the tool  4  and the tubular  40  along a generally y-axis about spherical bearings  23 , and  25  and the corresponding spherical bearings arranged in arm  22 ′. 
   The piston and cylinders  42  and  43  may be hydraulically of pneumatically operable and may be controlled via a remote control unit (not shown). 
   In use, a tubular  40  may be gripped by the tool  4  in the way described above and lowered into close proximity with the tubular string held in a spider. The adjusting piston and cylinders  42  and  43  may then be actuated to obtain alignment of the pin of the tubular  40  with the box of the tubular string held in the spider. The tubular  40  may then be rotated to obtain a partial connection or be held in alignment with an additional tool. The piston and cylinders  42  and  43  may then be returned to their original positions to obtain alignment with the top drive  3 . The top drive  3  may then be used to torque the connection up to a predetermined torque to complete the connection. 
   It is envisaged that various modifications may be made to the above described embodiments, such as using a hydraulic motor in place of the supporting member  24 .