Abstract:
A method and apparatus for facilitating the connection of tubulars using a top drive which, in one aspect, the apparatus includes a body connectable to said top drive. The body includes at least one gripping element radially displaceable by hydraulic or pneumatic fluid to drivingly engage a tubular to permit a screw connection between said tubular and a further tubular to be tightened to the required torque.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation of U.S. patent application Ser. No. 11/129,734, filed on May 13, 2005, now U.S. Pat. No. 7,137,454; which is a continuation of U.S. patent application Ser. No. 10/967,387, filed on Oct. 18, 2004, now abandoned; which is a continuation of U.S. patent application Ser. No. 09/509,073, filed on Aug. 22, 2000, now abandoned; which is the National Stage of International Application No. PCT/GB99/02203, filed on Jul. 22, 1999; which claims priority to GB 9815809.0, filed on Jul. 22, 1998 and claims priority to GB 9818358.5, filed on Aug. 24, 1998. All of the above referenced patent applications are herein incorporated by reference in their entirety. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to an apparatus for facilitating the connection of tubulars using a top drive and is more particularly, but not exclusively, intended 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 oil or gas wells it is usually necessary to line the borehole with a string of tubulars known as casing. Because of the length of the casing required, sections or stands of say two sections of casing are progressively added to the string as it is lowered into the well from a drilling platform. In particular, when it is desired to add a section or stand of casing the string is usually restrained from falling into the well by applying the slips of a spider located in the floor of the drilling platform. The new section or stand of casing is then moved from a rack to the well center above the spider. The threaded pin of the section or stand of casing to be connected is then located over the threaded box of the casing in the well and the connection is made up by rotation therebetween. An elevator is then connected to the top of the new section or stand and the whole casing string lifted slightly to enable the slips of the spider to be released. The whole casing string is then lowered until the top of the section is adjacent the spider whereupon the slips of the spider are re-applied, the elevator disconnected and the process repeated. 
   It is common practice to use a power tong to torque the connection up to a predetermined torque in order to make 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. A “top drive” is a top driven rotational system substantially used for drilling purposes, assigned to the drawworks at a higher level than the elevator, as is previously known. 
   Because of the high costs associated with the construction of oil and gas wells time is critical and it has been observed by the applicants that the time to connect a tubular to a top drive using existing equipment could be reduced. 
   SUMMARY OF THE INVENTION 
   Accordingly there is provided an apparatus for facilitating the connection of tubulars using a top drive, which apparatus comprises a body connectable to said top drive, said body comprising at least one gripping element radially displaceable by hydraulic or pneumatic fluid to drivingly engage a tubular to permit a screw connection between said tubular and a further tubular to be tightened to the required torque. 
   The present invention also provides an apparatus for facilitating the connection of tubulars using a top drive, said apparatus comprising a body connectable to said top drive, said body comprising at least one gripping element radially displaceable to drivingly engage said tubular and a sealing packer to inhibit, in use, fluid in said tubular from escaping therefrom. Preferably, said sealing packer can be actuated by hydraulic or pneumatic fluid. 
   One advantage of at least preferred embodiments of the invention is that the gripping elements transfer the full torque capacity of the top drive to the casing without damaging the pipe surface. Elastomeric jaws greatly reduce the marks made by the dies as compared to simple metal dies. Elastomeric jaws also enable pipes with differing inside diameters to be clamped with only one set of jaws. 
   The present invention also provides an apparatus for running tubulars into a borehole, said apparatus comprising a body provided with a wedge lock assembly and a hydraulically operable grapple to mechanically grip the inside wall of a tubular to be run into, or withdrawn from, the borehole, said grapple incorporating positive locking means to prevent inadvertent release of said grapple, said body further comprising means to prevent spillage of drilling fluid when the body is withdrawn from the tubular, a sealing packer for engagement with the tubular to permit fluid to be circulated within the tubular, and a stabbing guide. 
   In use, such an apparatus may be connected to a top-drive unit via a threaded connection, or to a Kelly driven rig via a pump joint latched into an elevator. Both systems have available a means of connecting up to a circulating system that will permit the casing to be filled or circulated at any time during the running operation. 
   Casing is normally run by picking up a joint at a time, utilizing single pickup elevators to bring the joint into the derrick and connect it to the previously run joint, whether it be by threaded connection or “mechanical latching or locking”. The two joints are either screwed or locked together and then lowered into the well bore using elevators. 
   With heavy casing strings it is required that very large elevators are used to be able to handle the load. This often means that the top of the casing joint must be set 8-10 feet above the rig floor to permit disengagement to take place. Scaffolding is often required for the rig crews to be able to stab or connect the next joint to the string. It is also normal to either utilize a separate pack-off assembly, or a fillup hose that must be installed by the rig crew after it has been lowered and set in the slips. 
   Preferred embodiments of the present invention will permit the casing to be picked up by single pickup elevators, connected either by rotation or mechanical latch, and then the casing running tool to be “stabbed” into the bore of the top joint without damage, due to the rubber bull-nose guide  216 . When the tool is at the correct depth of penetration within the casing bore, the hydraulic piston is actuated to drive the grapple down onto the wedge lock and secure the grapple to the casing wall. As the casing string is lifted, the wedge-lock continues to drive into the grapple bore, providing an ever increasing wedge lock. The compression spring installed within the hydraulic piston provides a “positive-lock” or failsafe should the hydraulic system fail for any reason. 
   When the apparatus is engaged, it is then possible to push, pull, or even rotate the casing string. A seal ring assembly is required to rotate the casing string to permit constant control of the hydraulic actuating piston to be maintained. 
   Preferred embodiments of the apparatus are equipped with a through-bore to permit casing fillup and circulation to take place at any time. There may also be provided a pack-off that can be either inflatable or flow pressure operated. 
   The present invention also provides a top drive having an apparatus in accordance with the present invention attached thereto. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Some preferred embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings, in which: 
       FIG. 1  is a cross-sectional side view of a first embodiment of an apparatus in accordance with the present invention inserted in a section of casing; 
       FIG. 2  shows the apparatus of  FIG. 1  connected to a top drive and inserted in a section of casing; 
       FIG. 3  shows a cross-sectional side view in perspective of part of a second embodiment of an apparatus in accordance with the present invention; 
       FIG. 4  shows a cross-sectional side view of a third embodiment of an apparatus in accordance with the present invention; and 
       FIG. 5  shows a cross-sectional side view of the embodiment of  FIG. 4  in use. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIG. 1  there is shown an apparatus which is generally identified by reference numeral  1 . The apparatus  1  comprises a cylindrical body  2  which has a central passage  3  therethrough. The cylindrical body  2  has circumferentially spaced recesses  4  thereabout in which respective gripping elements  5  are located. 
   The upper part  6  of the cylindrical body  2  is of a reduced outer diameter. The upper part  6  passes through a rotary transmission  7  and is rotatably supported by two bearings  8 ,  9  which are arranged in corresponding channels  10 ,  11  in an annular support  12 . A circumferentially raised portion  13  between the two bearings  8 ,  9  is provided in the upper part  6  to inhibit longitudinal movement of the cylindrical body  2 . 
   The rotary transmission  7  is mounted fast on the annular support  12  and is in sealing tight relation with the upper part  6  which is rotatable relative thereto. The rotary transmission  7  is provided with a feed passage  15  in the annular support  12  and with a feed line  16 . One end of a feed passage  14  is in fluid communication with the feed passage  15  and the other end of the feed passage  14  is in fluid communication with a radial channel  17 . Feed passages  18  are provided in the cylindrical body  2  to link the radial channel  17  with the circumferential recesses  4  behind each gripping element. 
   The upper part  6  is provided with internal splines  19  along the upper part of the passage  3 . The lower end of a connecting member  20  is provided with corresponding external splines and is located in the upper part of the passage  3 . The upper end of the connecting member  20  is provided with a circulating canal  22  and threads  23  for connection to a top drive ( FIG. 2 ). 
   The support member  12  is provided with two axles  24 ,  25  to which compensating cylinders  26 ,  27  are attached, the corresponding pistons  28 ,  29  being, in use, connected to the body of the top drive ( FIG. 2 ). 
   Gripping elements  5  are preferably based on the construction described in PCT Publication No. WO 94/05894 which is incorporated herein for all purposes, and sold by the applicants under the trade mark “MICRO-GRIP”. 
   The gripping elements  5  comprise a plurality of longitudinally extending strips (not shown) which are embedded side by side in an elastomeric base member (not shown). Each strip projects out from said elastomeric base member, and each strip has a pipe gripping edge (not shown) facing away from the elastomeric base member, so that channels are formed between adjacent strips to accommodate debris from the surface of the casing to be gripped. The pipe gripping edge may, for example, comprise teeth, so that the strips resemble saw blades, or may comprise particulate material bonded to the strips. This type of gripping element allows rotational torque to be applied to the tubular and longitudinal forces produced by circulating fluid within the tubular and the weight of the tubular to be taken. 
   The cylindrical body  2  is shown in  FIG. 1  in a section of casing  30  with gripping elements  5  in a radially extended position, engaging the inner wall  31  of the section of casing  30  beneath a threaded box  32 . 
   In use, the pistons  28 ,  29  are connected to the stator  34  of the top drive  33  ( FIG. 2 ). The rotor  35  of the top drive  33  is connected to the connecting member  20 . The section of casing  30  is positioned over the upper portion of a casing string using, for example, a pipe positioning device. The top drive  33  with the attached apparatus  1  is lowered so that the cylindrical body  2  thereof enters the casing  30 . Alternatively, the section or stand of casing may be brought towards the apparatus  1  using the methods and apparatus disclosed in co-pending UK Patent Application No. 9818366.8 entitled “Methods and Apparatus for Facilitating the Connection of Tubulars Using a Top Drive” filed by the applicant for the present application on 24 Aug. 1998. If the support member  12  hits the top of the threaded box  32 , the compensating cylinders  26 ,  27 , which contain compressed air, cushion the impact whilst the splines  19 ,  21  in the upper part  6  of the cylindrical body  2  will allow relative longitudinal movement between the apparatus  1  and the top drive  33  whilst being able to transmit rotation therebetween. 
   Hydraulic pressure is applied through feed line  16 , feed passage  15 , feed passage  14 , radial channel  17 , and feed passage  18  into recess  4  behind gripping elements  5 , forcing the gripping elements  5  radially outwardly to engage the inner wall  31  of the casing  30 . 
   The top drive  33  may now be used to rotate the rotor  35  which in turn rotates the connecting member  20 , the cylindrical body  2  and hence the casing  30 . The compensating cylinders  26 ,  27  will allow a small downward movement as the threaded pin on the bottom of the casing enters the box on the top of the string, and may be controlled remotely. The compensating cylinders  26 ,  27  may be of the pneumatic compensating type, i.e. their internal pressure may be adjusted to compensate for the weight of the casing  30  so that movement of the tubular may be conducted with minimal force. Pneumatic compensating cylinders also reduce the risk of damage to the threads of the tubulars. This can conveniently be achieved by introducing pneumatic fluid into the cylinders  26 ,  27  and adjusting the pressure therein. Hydraulic cylinders may, however, be used or hydraulic cylinders provided with a pneumatic bellows system. 
   Once the joint is correctly tightened the elevator  37  is swung into position and the elevator slips therein (not shown) are actuated to grip the casing  30  beneath the box  32 . The top drive  33  is then raised a small amount using the drawworks to enable the slips in the spider to be released and the top drive and casing string is then lowered. 
   As the casing is lowered liquid may be introduced into the casing  30  via the connecting canal  22  and the central passage  3 . The introduction of such liquid is often desirable to facilitate the lowering of the casing. 
   Referring to  FIG. 3  there is shown an apparatus in accordance with a second embodiment of the present invention which is generally identified by the reference numeral  101 . 
   The apparatus  101  is generally similar to that of  FIG. 1 , in that it comprises a cylindrical body  102  which has a central passage  103  therethrough. The cylindrical body  102  has recesses  104  thereabout in which gripping elements  105  are located. The gripping elements  105  are provided with recesses  106 . 
   The cylindrical body  102  is also provided with a cylindrical sealing packer  107  arranged below the gripping elements  105 . The cylindrical sealing packer  107  is provided with a recess  108 . The cylindrical sealing packer  107  which is made from an elastomeric material is fast with the cylindrical body  102 . 
   The cylindrical body  102  is provided with a feed passage  109  which is at the upper end connected to a hydraulic fluid supply, and at the other, to the recesses  106  and  108  in the gripping elements  105  and the cylindrical sealing packer  107  respectively. 
   In use, the apparatus  101  is connected to a top drive, such as that shown in  FIG. 2 , and is inserted into the top of a section or stand of casing  110 . Hydraulic fluid pressure is applied through feed passage  109  into recesses  106  and  108  which moves the gripping elements  105  into engagement with the inner wall  111  and the cylindrical sealing packer  107  into contact with the inner wall  111 . The gripping elements  105  engage with the inner wall  111  of the casing  110  so that rotational force can be transmitted from the apparatus  101  to the casing  110 . The sealing packer  107  substantially prevents any fluids such as mud from escaping between the apparatus  101  end the casing  110 . This is particularly advantageous where it is desired to circulate fluid to facilitate running the casing. In particular, if the casing string becomes lodged on an obstruction, liquid can be pumped down the casing string under high pressure to remove the obstruction. The sealing packer  107  facilitates this operation by inhibiting liquid under high pressure escaping through the top of the casing  30 . 
   Referring to  FIGS. 4 and 5  there is shown an apparatus in accordance with a third embodiment of the present invention which is generally identified by the reference numeral  201 . 
   The apparatus comprises a cylindrical body  202  with a threaded connection  203  at the upper end for connection to a top drive. Attached to the cylindrical body  202 , or machined into it, is a hydraulic cylinder  204 , with threaded ports  205 ,  206  at opposite ends. These ports  205  and  206  permit hydraulic fluid to be injected under pressure to manipulate a hydraulic piston  207 , secured within the cylinder by a threaded lock ring  208 . A compression spring  209  is located in the cylinder  204  above the piston  207 . 
   A grapple  210 , provided with serrated teeth machined into its outer surface, is provided around the cylindrical body  202  below the hydraulic cylinder  204 . The grapple  210  is connected to the hydraulic piston  207  by a threaded connection  211 . A corresponding wedge lock  212  is provided on the cylindrical body  202 . The grapple  210  and corresponding wedge lock  212  are located, in use, inside a casing  213 . The piston  207  and lock ring  208  are fitted with seal rings (not shown) to prevent hydraulic fluid leakage. 
   A mud-check valve  214  is connected by a threaded connection at the lower end of the wedge lock  212 . Below this valve is a rubber pack-off assembly  215 . These prevent spillage of drilling fluid when the apparatus  201  is removed from within the casing joint  213 . The pack-off  215  can be energized by either internal mud pressure or external mud flow. 
   In use, the apparatus  201  is lowered into the casing joint  213  as shown in  FIG. 4 . The grapple  210  is held out of contact with the wedge lock  212  by hydraulic fluid injected into port  206 . 
   When the apparatus  201  is located at the correct installation depth within the casing  213 , the pressure and fluid is released from port  206 , and fluid is injected into port  205 . This pushes the piston  207  downwards, pressing the grapple  210  against the wedge lock  212 . The grapple  210  is forced outwards by the wedge lock  212 , forming a mechanical friction grip against the inner wall of the casing  213 . This is shown in  FIG. 5 . 
   The rig lifting equipment (not shown) raises the apparatus  201 , and this causes the wedge lock  212  to be pulled upwards against the inner surface of the grapple  210 , ensuring that constant outward pressure is applied to the grapple  210 . The grip becomes tighter with increasing pull exerted by the rig lifting equipment. 
   Should hydraulic pressure be lost from port  205 , the compression spring  209  ensures that the piston  207  continues to press the grapple  210  against the wedge lock  212 , preventing release of the grapple from the wedge lock. 
   The apparatus  201  and casing  213  are then lowered into the well bore and the casing is secured. The apparatus  201  is lowered so that it supports its own weight only, and hydraulic fluid is then pumped out of port  205  and into port  206  to release the grapple  210  from the wedge lock  212  and thus release the apparatus  201  from the casing  213 . The apparatus is then removed from the casing joint  213  and the process is repeated. 
   It is envisaged that the apparatus as described above could be used in conjunction with any of the apparatus and used with any of the methods as described in the co-pending International Applications based on GB Application Nos. 9818360.1, 9818363.5 and 9818366.8, entitled “An Apparatus for Facilitating the Connection of Tubular Using a Top Drive”, “Method and Apparatus for Facilitating the Connection of Tubulars using a Top Drive,” and “Method and Apparatus for facilitating the Connection of Tubulars using a Top Drive,” respectively.