Improvements relating to drilling apparatus

Abstract

A drilling apparatus ( 1 ) is for use on a rotary drilling rig with a top drive which enables circulation and rotation of a drill string ( 3 ) to continue uninterrupted during the making of drill string connections. It has a snubber gripping mechanism ( 10, 9 ) to enable tool joints ( 2, 3 ) to be supported and gripped with a reduced pressure chamber ( 5 ) volume and snubbing force, during tool joint connections. The gripping mechanism has gripping pads ( 14 ) arranged to move radially by relative rotation of a drive cylinder ( 34 ) causing a tapered surface ( 36 ) of the drive cylinder ( 34 ) to press against or release the pad ( 14 ). A guide cylinder ( 30 ) supports and guides the pads ( 14 ) and collets ( 13 ) for retaining a drill string at an upset shoulder ( 19 ).

1 .- 29 . (canceled) 
     
     
         30 . A drilling apparatus for use on a rotary drilling rig with a top drive which enables circulation and rotation of a drill string to continue uninterrupted during the making of drill string connections, wherein the apparatus comprises a tool joint gripping mechanism arranged to rotate at the same speed as a drill string and comprising:
 gripping pads arranged to move radially relative to a drill string tubular or upset, and   
       a drive to drive the pads radially relative to a drill string tubular or upset. 
     
     
         31 . The drilling apparatus as claimed in  claim 30 , wherein the gripping pads are wedge-shaped, with a tapered surface upon which a gripping force is exerted and a contact surface for contacting a drill string or tubular. 
     
     
         32 . The drilling apparatus as claimed in  claim 30 , wherein the gripping mechanism comprises one or more drive cylinders each having an internal wedge profile which, on relative rotation, moves the pads radially to contact and grip a tool. 
     
     
         33 . The drilling apparatus as claimed in  claim 30 , wherein the gripping mechanism comprises one or more drive cylinders each having an internal wedge profile which, on relative rotation, moves the pads radially to contact and grip a tool; and wherein the gripping mechanism comprises a guide to restrain the pads to move radially. 
     
     
         34 . The drilling apparatus as claimed in  claim 30 , wherein the gripping mechanism comprises one or more drive cylinders each having an internal wedge profile which, on relative rotation, moves the pads radially to contact and grip a tool; and wherein the gripping mechanism comprises a guide to restrain the pads to move radially; and wherein the drive is arranged to rotate the drive cylinder and the guide at the same speed, and to introduce a temporary relative movement to cause radial movement of the pad. 
     
     
         35 . The drilling apparatus as claimed in  claim 30 , wherein the gripping mechanism comprises one or more drive cylinders each having an internal wedge profile which, on relative rotation, moves the pads radially to contact and grip a tool; and wherein the gripping mechanism comprises a guide to restrain the pads to move radially; and wherein the drive is arranged to rotate the drive cylinder and the guide at the same speed, and to introduce a temporary relative movement to cause radial movement of the pad; and wherein each of the drive cylinder and the guide comprises a flange which is engaged by a drive member to rotate. 
     
     
         36 . The drilling apparatus as claimed in  claim 30 , wherein the gripping mechanism comprises one or more drive cylinders each having an internal wedge profile which, on relative rotation, moves the pads radially to contact and grip a tool; and wherein the gripping mechanism comprises a guide to restrain the pads to move radially; and wherein the drive is arranged to rotate the drive cylinder and the guide at the same speed, and to introduce a temporary relative movement to cause radial movement of the pad; and wherein each of the drive cylinder and the guide comprises a flange which is engaged by a drive member to rotate wherein the drive member comprises a gear. 
     
     
         37 . The drilling apparatus as claimed in  claim 30 , wherein the guide and the drive cylinder overlap in the radial direction. 
     
     
         38 . The drilling apparatus as claimed in  claim 30 , wherein the guide and the drive cylinder are at least partially offset in the axial direction so that they do not overlap in the radial direction for at least some of the axial dimension of the pad; and wherein the guide comprises guide rings engaging upper and lower parts of the pad and the drive cylinder is arranged to engage the pad between said guide rings. 
     
     
         39 . The drilling apparatus as claimed in  claim 30 , wherein the guide comprises at least one drive shaft interconnecting said guide rings. 
     
     
         40 . The drilling apparatus as claimed in  claim 30 , wherein the gripping mechanism comprises collets arranged to engage an upset at a shoulder with a tubular, and a collet drive arranged to move the collet radially with respect to the tubular or upset; and wherein the collet is adjacent to the pad in the axial direction. 
     
     
         41 . The drilling apparatus as claimed in  claim 30 , wherein the gripping mechanism comprises one or more drive cylinders each having an internal wedge profile which, on relative rotation, moves the pads radially to contact and grip a tool, and wherein said guide cylinder includes a port for the pad and a port for the collet. 
     
     
         42 . The drilling apparatus as claimed in  claim 30 , wherein the gripping mechanism comprises collets arranged to engage an upset at a shoulder with a tubular, and a collet drive arranged to move the collet radially with respect to the tubular or upset; and wherein the collet is adjacent to the pad in the axial direction; and wherein the collet drive and the pad drive are interconnected. 
     
     
         43 . The drilling apparatus as claimed in  claim 30 , wherein the apparatus comprises a pressure chamber and two gripping mechanisms including an upper gripping mechanism arranged to engage a tubular or upset above the pressure chamber and a lower mechanism arranged to engage a tubular or upset below the pressure chamber; and wherein said gripping mechanisms are snubbers. 
     
     
         44 . The drilling apparatus as claimed in  claim 30 , wherein the gripping mechanism comprises seals arranged to act on a tool joint upset immediately adjacent to and above and below a blind ram or valve that segregates a pressure chamber into two parts; and wherein the pads and seals are arranged to contact an upper upset and the apparatus comprises a lower gripping mechanism having grips and seals arranged to contact a lower upset while leaving space for an open blind ram or valve between them when a tool joint is connected. 
     
     
         45 . The drilling apparatus as claimed in  claim 30 , wherein the gripping mechanism comprises collets arranged to engage an upset at a shoulder with a tubular, and a collet drive arranged to move the collet radially with respect to the tubular or upset; and in which the collets and the pads are held in place by a keyway or ridge in the drive cylinder and are releasable by an additional rotation of the drive cylinder to facilitate inspection and replacement, being as they. 
     
     
         46 . The drilling apparatus as claimed in  claim 30 , further comprising a jack arranged to lift the gripping mechanism relative to a blind ram or valve or of the blind ram or valve relative to a lower gripping mechanism to provide separation to inspect the gripping mechanisms; and wherein the lower gripping mechanism collets are configured to support a tool joint box upset shoulder before the collets of the upper mechanism are closed and lowered to interfere with a tool joint pin upset shoulder; and wherein the collets provide a fail-safe support for the tool joint upset, such that the collets of the lower mechanism cannot retract until the drill string weight is taken off the collets and the collets of the upper mechanism cannot be retracted until the snubbing force is removed. 
     
     
         47 . The drilling apparatus as claimed in  claim 30 , wherein the gripping mechanism comprises collets arranged to engage an upset at a shoulder with a tubular, and a collet drive arranged to move the collet radially with respect to the tubular or upset; and wherein the pad drive and the collet drive are related by differential gearing; and wherein the differential gearing comprises planet gears arranged such that movements of planet gears can alter the rotary relationship between the drives. 
     
     
         48 . A method of operation of a drilling apparatus comprising a tool joint gripping mechanism arranged to rotate at the same speed as a drill string and comprising gripping pads arranged to move radially relative to a drill string tubular or upset, and a drive to drive the pads radially relative to a drill string tubular or upset, wherein the method comprises the steps of:
 driving the gripping mechanisms so that the pads and the collets rotate at the same speed as a drill string, and   retarding or advancing the pad drive to radially move the pad relative to the drill string.   
     
     
         49 . The method as claimed in  claim 48 , wherein the apparatus is fixed to a rig floor and an extension sub in the drill string enables a bit to drill on during connections with a predetermined weight on bit; and wherein the apparatus is mounted on a hoist to allow vertical motion during connections and therefore enable continuous drilling and continuous tripping if required on new rigs. 
     
     
         50 . The method as claimed in  claim 48 , wherein a pin upset is moved away from a box upset by the depth of the pin plus a distance to allow blind ram or valve to close and to allow mud to flow into the drill string below and out of a tubular above.