Abstract:
A one trip top to bottom expansion to form a lower end recess on a tubular is described using two swages of different dimensions. The smaller swage is run down hole with the larger swage behind it in a locked collapsed position. When the proper depth is reached the leading swage hits a no go. A pickup force with dogs engaged in a groove releases the lock on the larger swage at which point applied pressure sets an anchor, extends the larger swage to take over the expansion for the recess at the lower end of the tubular. An emergency release is provided to pull out of the hole if the swage cannot complete the task.

Description:
FIELD OF THE INVENTION 
   The field of this invention is tubular expansion downhole and more particularly two stage expansion to create a recess so one string can be expanded into another to create a monobore and even more particularly doing it in one trip in a downhole direction. 
   BACKGROUND OF THE INVENTION 
   Monobore completions result in a common diameter of the well from the surface using expansion techniques. Usually a string has a recess at its lower end representing a zone of enlarged diameter at its lower end. When that string is secured in position another string is run through it and the top end of the second string is placed in alignment with the recess at the lower end of the first string. An expansion device is then applied to the second string to make its inside diameter approximately the same as the inside diameter of the upper string. The two strings are secured to each other in the recess of the upper string. Because of the recess, the expansion of the lower string results in no internal dimension reduction in the overall assembled strings. 
   One way to do this is to mount a recess on the lower end of the upper string and expand the upper string to the recess and then put the lower string into position adjacent the recess of the upper string and expand the lower string. Another way is to form the recess downhole. One such technique is described in the July 2005 edition of World Oil article by Fischer and Snyder a technique of forming a bell at the bottom and then continuing liner expansion to the surface was described. This bottom up technique puts the tubular being expanded into compression and risks buckling during the expansion. What is needed and not provided by this technique is a way to expand from top to bottom with the string in tension and a simple technique of transitioning between swages after the tubular is expanded so that the recess can then be produced. This is more technically challenging to do than a bottom up expansion because in a top down expansion there has to be a swage transition to a bigger size within an expanded tubular to form the even larger recess. A technique of disabling the larger swage until the recess needs forming is also incorporated into the invention. Features are also provided for emergency release in case the expansion assembly cannot fully advance and needs to be pulled out of the hole to the surface. These and other advantages of the present invention will be more apparent to those skilled in the art from a review of the description of the preferred embodiment and the associated drawings while recognizing that the claims define the full scope of the invention. 
   SUMMARY OF THE INVENTION 
   A one trip top to bottom expansion to form a lower end recess on a tubular is described using two swages of different dimensions. The smaller swage is run down hole with the larger swage behind it in a locked collapsed position. When the proper depth is reached the leading swage hits an integral or releasable no go shoulder. A pickup force with dogs engaged in a groove releases the lock on the larger swage at which point applied pressure sets an anchor, extends the larger swage to take over the expansion for the recess at the lower end of the tubular. An emergency release is provided to pull out of the hole if the swage cannot complete the task. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a section view showing the leading in the no-go position; 
       FIG. 2  is the view of  FIG. 1  showing the dogs stopped against a shoulder recess; 
       FIG. 3  is the view of  FIG. 2  with the shear screws sheared to allow relative movement between mandrels; 
       FIG. 4  is the view of  FIG. 3  with the leading swage bottomed on the no go and the trailing swage released to get bigger on application of pressure in the string; 
       FIG. 5  is the view of  FIG. 4  with the trailing swage actuated to form the recess; 
       FIG. 6  is the view of  FIG. 5  in the emergency release position where the trailing swage is collapsed; 
       FIG. 7  is a perspective view of the lock for the trailing swage in the run in position as expansion takes place with the leading swage; 
       FIG. 8  is the view of  FIG. 7  with the lock released so that the trailing swage can go to its full dimension on pressure application which strokes it further downhole; 
       FIG. 9  is a sectional detailed view of a releasable no go locked in position and before it is engaged by the swage assembly; 
       FIG. 10  is the view of  FIG. 9  with the releasable no go engaged by the swage assembly; 
       FIG. 11  is the view of  FIG. 10  with the releasable no go engaged from below and just before its release; 
       FIG. 12  is the view of  FIG. 11  with the releasable no go fully released; 
       FIG. 13  is a perspective view of some of the components of the releasable no go showing the c-ring positions when the no go is locked in; and 
       FIG. 14  is the view of  FIG. 13  showing the c-rings collapsed for release of the releasable no go. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  illustrates the component positions for the initial top down expansion of a tubular  10 . The tubular  10  preferably has a recess  12  below a restrictor  14 . The purpose of restrictor  14  is to give an early signal at the surface that the leading fixed cone  16  is approaching the restrictor  14 .  FIG. 1  shows a mandrel  18  that supports a series of dogs  20  that are movable against the bias of spring  22 . When the dogs  20  on the way downhole engage the restrictor  14 , the mandrel keeps moving to compress spring  22  and present groove  24  opposite dogs  20  to allow them to radially retract and clear the restrictor  14 , at which time spring  22  pushes dogs  20  out of groove  24  so that they again radially extend outwardly and far enough to be captured in recess  12 , as shown in  FIG. 2 , when the assembly A is picked up again. 
   The components of the assembly A will now be described. Referring to  FIG. 2 , the leading cone  16  is preferably fixed. A variable diameter swage  26  has alternating segments only one  28  is seen in the section view because the segments are all in alignment. Segments  28  each have a lower retainer  30  that is engaged to the fixed cone  16 . The other nested segments that can&#39;t be seen in the section view each have upper retainers  32  that are collectively pushed down by ring  34  when an anchor and associated stroker (both not shown) advance the mandrel  18  downhole. This occurs by getting the anchor to grip as pressure extends the stroke to advance a swage assembly. As retainers  30  and  32  are brought together by a downhole force, the segments fall into alignment on variable diameter swage  26  and make a continuous expansion circumferential surface  36  to expand the tubular  10 . 
   Uphole of leading variable diameter swage  26  is a larger swage  38  of a similar design and shown in its extended or smaller diameter dimension. In the position shown in  FIG. 2 , alternating segments  40  and  42  are shown with their peaks  44  and  46  offset. Segments  40  have retainers  48  secured to ring  50 . Segments  42  have retainers  52  secured to ring  34 . Segments  40  can be aligned with segments  42  unless that movement is locked, as will be explained below. For initial expansion of the tubular  10 , the fixed cone enters first and the force from the stroker supported by an anchor (both not shown) is enough to make the leading swage  26  get its segments  28  and their alternating segments that are not shown into alignment so that the maximum dimension of swage  26  represents the degree of the initial expansion of tubular  10 . 
   During this initial expansion of tubular  10  the segments  40  and  42  are locked in the  FIG. 2  position. C-ring  58  is a circlip. During the initial expansion ring  34  is prevented from moving because the body lock ring  58  transfers the load from sleeve  56  (attached to  34 ) directly to sleeve  52  thus by-passing the larger swage. 
   Sleeve  56  carries c-ring  58  that is held radially spread out until it is moved into alignment with groove  60  on mandrel  18  at which point it locks the relative movement that created that alignment, as will later be discussed. A lock ring  62  in the  FIG. 2  component position, locks sleeve  56  to sleeve  52  as the swage  26  is advanced to expand the tubular  10  initially. Mandrel  18  has a lost motion design that is better illustrated in  FIGS. 7 and 8 . Lock ring  62  initially holds sleeve  56  to sleeve  52 . While  FIGS. 7 and 8  are schematic, those skilled in the art will appreciate that dogs  20  shown in  FIG. 2  can be designed to extend through windows  68  to engage shoulder  70  shown in  FIG. 2 . This engagement keeps component  66  from moving uphole while component  64  is pulled up. Component  64 , which is the same part as sleeve  52  moves with sleeve  56  shown in  FIG. 2  while component  66  is part of the mandrel  18  that is held by shoulder  70 . Component  64  has wickers  72  which engage lock ring  62  on its underside leaving a relatively small gap  74  in lock ring  62 . Wickers  72  are segmented and are disposed on fingers  76 , three of which are shown in  FIG. 7 . Fingers  76  extend from segment  64  and move with it. Fingers  78  alternate with fingers  76  and extend from segment  66  which doesn&#39;t move due to dogs  20  engaged to surface  70  as shown in  FIG. 2 . Fingers  78  have a recess  80  which is initial alignment with wickers  72 . Adjacent to recess  80  is a high section  82  that upon relative movement between segments  64  and  66  rides under ring  62  to lift it off wickers  72  as shown in  FIG. 8 . Once this position is attained, reversing the movement is possible without impediment from ring  62  to allow the segments  40  and  42  to go into alignment so that continuing expansion of tubular  10  can add the recess  84  (see  FIG. 5 ) to the already expanded tubular  10 . 
   The operational sequence can now be better understood with a sequential look at the  FIGS. 1-5 . In  FIG. 1  the dogs  20  have jumped past restrictor  14  to give a signal at the surface that the dogs are in recess  12  and that very soon the fixed cone  16  will bottom out on restrictor  14 . At that point further expansion with swage  26  is halted and the assembly is picked up to the  FIG. 2  position with dogs  20  up against shoulder  70 . At that point an upward pull from the surface moves sleeve  56  uphole relative to the portion of mandrel  18  held by the dogs  20 . The result is that shear pin  54  breaks and c-ring  58  lines up with groove  60  and snaps into it preventing further relative movement that just occurred in either direction. This position is shown in  FIG. 3  which also shows spring  22  has extended. That same relative movement no locked in by c-ring  58  has also resulted in bringing high sections  82  under lock ring  62 , as shown in  FIG. 8  so that lock ring  62  no longer engages wickers  72  below it. This is also shown in  FIG. 3 .  FIG. 4  shows weight set down again until cone  16  lands on restrictor  14 . Form this point when the anchor and stroker (both not shown) are activated relative movement is now possible between rings  50  and  34  so as to put segments  40  and  42  into alignment to expand tubular  10  to a larger dimension than with swage  26  as shown in  FIG. 5 . Because the high sections  82  separate lock ring  62  from wickers  72 , swage  38  can now be activated to a larger dimension whereupon further expansion with swage  38  can make the recess  84 . After coming out the bottom of the tubular  20  the pressure that set the anchor and operated the stroker is removed and a pickup force allows swage  38  and  26  to extend and radially collapse so that the assembly A can be withdrawn. 
   If an emergency release is needed when dogs  20  are still in a position to hang in recess  12  a pickup force is applied to shear shear ring  86  which in turn allows spring  22  to push down dogs  20  into groove  88  and once there they can clear the restrictor  14  to allow the assembly A to be pulled out of the hole. 
   While  FIGS. 1-8  showed a fixed restrictor  14  a removable design is illustrated in  FIGS. 9-14 . Restrictor  14 ′ has a groove  100  in which sits a locator split ring  102  shown having a pair of circumferential projections that can spring into a matching pattern of depressions  104  in tubular  10 ′. Ring  102  locates restrictor  14 ′ while the location is locked with split lock ring  106  having wickers  107  that engage wickers  108  on tubular  10 ′ when humps  110  engage humps  112 .  FIG. 9  shows dogs  20 ′ approaching stop surface  114 .  FIG. 10  shows dogs  20 ′ having jumped past surface  114  and taper  116  landed on that surface. Taper  116  in this embodiment is slightly in advance of the fixed cone  16  shown in  FIGS. 1-8 .  FIG. 11  shows tapered surface  120  of dogs  20 ′ engaging tapered surface  118  at the lower end of the removable restrictor  14 ′. Any further uphole movement of dogs  20 ′ from the  FIG. 11  position will result in the  FIG. 12  position where humps  110  and  112  get into misalignment as shown in  FIG. 12  rather than the alignment shown in  FIG. 11 . In essence hump  110  falls into groove  122  and the restrictor  14 ′ is captured on shoulder  120  for removal from the tubular  10 ′ as shown in  FIG. 12 .  FIGS. 13 and 14  show the relative movement within restrictor  14 ′ that locks it to tubular  10 ′ in  FIG. 13  and releases it in  FIG. 14  as well as the c-ring preferred shape of rings  104  and  106 . 
   The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below.