Patent Publication Number: US-8973653-B2

Title: Running tool

Description:
TECHNICAL FIELD 
     This invention relates to a running tool for inserting and setting an assembly into a bore in a well. The running tool may be for inserting a seal assembly or any other such item that is set by the application of axial force (which may be produced hydraulically within the tool) and then locked into a bore of a well housing by means of rotation. 
     BACKGROUND 
     Conventionally, assemblies which need to be inserted and set into a bore in a well typically require other multiple tools which necessitate more than one trip down the well or other than one rotation step, if multiple elements in the tool must be rotated. This leads to increased complexity and increased installation time, and therefore a greater time for which the well is not operational. 
     In practice, as an example, a seal assembly typically needs to be locked in place by rotation of one item to around 60,000 lb feet of torque and then subsequent rotation of a second item to around 12,000 lb feet to lock the hanger and seal assembly in place. This requires two separate rotation steps, and may be done either in one or two trips. Furthermore, the high torque figure required means that conventional tools are particularly large and heavy, and cause significant safety issues in achieving such high torques in a controlled manner. 
     SUMMARY 
     Thus, the present invention aims to provide a tool which reduces the amount of torque that is necessary and which can minimise the number of rotations required to insert and set an assembly in to a bore in a well. 
     According to the present invention, there is provided a running tool for inserting and setting an assembly in to a bore in a well, the tool comprising:
         a main body having a hydraulic cylinder for actuating one or more locking elements on the main body for, in use, reaction with the bore;   an outer sleeve rotationally mounted on the main body;   a rotatable mandrel to which, in use, torque is applied; and   means for transmitting the torque from the mandrel to the outer sleeve.       

     Thus, the present invention provides a hydraulic cylinder for actuating the assembly, thereby avoiding the high torque requirement for the initial locking step in the prior art. Furthermore, the present invention requires only the rotation of the outer sleeve, via rotation of the mandrel, for subsequent insertion and setting of the assembly within the bore. 
     The running tool may further comprise a piston arranged to cause relative movement of the piston and the hydraulic cylinder. 
     The hydraulic cylinder is preferably axially mounted within the main body. The mandrel is also preferably axially mounted in the main body and, when this occurs, the mandrel is preferably surrounded by the hydraulic cylinder. 
     The mandrel may extend through the hydraulic cylinder such that the mandrel has a driven end extending from one end of the hydraulic cylinder and a transmitting end extending from the other end of the cylinder. 
     The torque transmitting means may be a planetary gear system which is preferably mounted on the mandrel at the distal torque transmitting end. The planetary gear typically consists of a sun gear and a plurality of planetary gears and the sun gear is preferably mounted on the mandrel at the distal end. The planetary gears are preferably mounted between the sun gear and an inner wall of the outer sleeve of the running tool. In this way, torque is transmitted from the mandrel, via the sun gear, to the planetary gears and on to the outer sleeve. Rotation of the outer sleeve causes, in use, the assembly which is being inserted to be set in place in the bore in a well. 
     The locking element(s) of the running tool preferably include one or more locking dogs or split lock rings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One example of the present invention will now be described with reference to the accompanying drawings, in which: 
         FIG. 1  shows a top end view of the present invention; 
         FIG. 2  shows a cross sectional view along the axis of the tool of  FIG. 1 ; 
         FIG. 3  shows a cross sectional view across the gears in  FIG. 2 ; 
         FIG. 4  shows a running tool seal assembly and hanger; and 
         FIG. 5  shows the provision of a shear ring on the tool of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     The top end view of  FIG. 1  shows a running tool  10  having a main body  11 , having an axis  11   a  ( FIG. 2 ). Coaxially mounted with the main body  11  are a hydraulic cylinder  12  and a rotatable mandrel  13 . A retaining ring  14  is radially located between the hydraulic cylinder  12  and the main body  11 . A plurality of plugs  15  is located in the end wall of the hydraulic cylinder. One or more of these plugs may have openings through which, in use, hydraulic fluid can be supplied and/or vented during operation. 
     Turning now to  FIG. 2 , the invention can be seen in greater detail. In particular, the hydraulic cylinder  12  is provided with an inner body  20  and an outer body  21 . The inner body is located adjacent to the mandrel  13 , with the outer body radially outwards of the inner body. 
     The tool is also provided with a split lock ring  22  which is, in use, moved out radially so as to engage with a groove  72  in a high pressure housing (or riser)  70  (sec  FIG. 4 ) in a well. The locking ring is caused to move radially outwards by an actuation piston  23  which is retained in position by a retainer ring  14 . In use, hydraulic fluid is supplied through plug  15   a  and into an annulus between a shoulder of piston  23  and an end surface of retainer ring  14 . This causes the piston to move, in  FIG. 2 , to the right, thereby causing the stepped outer surface  23   a  of the piston  23  to engage with the corresponding inner surface  22   a  of the split lock ring. The lock ring segments are thereby caused to move radially outwards and engage with the high pressure housing in the well. In this way, the tool is locked into the housing and gives a reaction point for the hydraulic setting piston  30 . To disengage the lock ring segments, the hydraulic fluid previously supplied through plug  15   a  may be vented from the annulus between the shoulder of the piston  23  and the end surface of the retainer ring  14 , and hydraulic fluid may be supplied from another plug to the annulus between the opposite side of the shoulder of the piston  23  and the outer body  21 . This causes the piston to move, in  FIG. 2 , to the left, allowing springs of the cap screws that retain the lock ring segments on the outer body  21  to move the lock ring segments radially inwards (e.g., to disengage groove  72 ). 
     The mandrel  13  is typically retained to the hydraulic cylinder  12  by means of a shear ring  80 , shown in  FIG. 5 . The shear ring ensures that the assembly doesn&#39;t expand prematurely, and that the split lock ring  22  will be level with the grooves in the housing  70  when the assembly lands out. 
     A further piston  30 , this time typically for setting the seal, is located around the distal end of the inner part of the hydraulic cylinder and, together with the inner and outer cylinder bodies defines an annular chamber  31 . This chamber is supplied with hydraulic fluid via plug  15   b  and along pathway  15   c  through the outer body of the cylinder. In use, supply of hydraulic fluid through plug  15   b  causes the chamber  31  to expand causing relative movement of the piston  30  and the hydraulic cylinder. 
     In particular, in use, hydraulic fluid is supplied to plug  15   b  only once the split lock ring  22  has been expanded radially. Thus, the piston  30  is forced, in  FIG. 2 , to the right and the hydraulic cylinder  12  is caused to move, in  FIG. 2 , to the left. In practice, this means that the locking elements of the split lock ring  22  are forced upwards in the well (e.g. upwards in  FIG. 4 ) to such a force that the shear ring shears and the locking elements are forced against an upper shoulder  71  of a groove  72  in the high pressure housing  70 . The piston  30  is then able to move, in the well, in a downward direction thereby energising the seals in the casing hanger packoff assembly (see  FIG. 4 ). 
     The tool has an outer sleeve  40  which is rotatable relative to the piston  30  and the hydraulic cylinder  12 . Such rotation is achieved by the use of a planetary gear system  41  which includes a plurality of planetary gears  42  which are in driving engagement with an internal gear  43  in the outer sleeve  40 . The planetary gear or gears  42  engage with a sun gear  44  which is mounted around the distal end of the mandrel  13 . Thus, rotation of the mandrel  13  as it passes through the hydraulic cylinder causes the sun gear  44  to be rotated. Such rotation is passed on to the planetary gears and subsequently on to the outer sleeve  40 . 
     Thus, in use, whilst holding the seal setting pressure through plug  15   b , the mandrel  13  is rotated to rotate the sun gear  44 , thereby rotating the, typically, three planetary gears  42  which in turn rotate the outer sleeve  40 . In use, the outer sleeve assembly moves down in the well (to the right in  FIG. 2 ) and means that the outer sleeve  40  can travel axially independently of the rest of the tool. An extended groove  45 , in this example located in the outer hydraulic cylinder housing, but it could be located in the inner wall  43  of the outer sleeve  40 , co-operates with ball bearings  46  to assist in the independent movement of the outer sleeve  40  with respect to the rest of the tool. 
     The movement of the outer sleeve downwards in the well causes an energising ring on the casing hanger packoff assembly to be rotated, thereby expanding a lock ring. The casing hanger packoff lock ring then engages in a groove in the high pressure housing. Continued rotation of the outer sleeve and thus the energising ring in the packoff causes locking pins to be sheared, thereby allowing a further ring in the packoff to be rotated to lock the packoff and hanger in place. 
     This is shown in reference to  FIG. 4  which shows the energising ring  60 , the casing hanger lock ring  61  in the casing hanger packoff  62 . It also illustrates the casing hanger  63  which is being inserted and the connection of the running tool  10  and, in particular, the outer sleeve  40  to the energising ring  60  by virtue of an extension  64  of the outer sleeve.