Abstract:
A latching assembly for a lower collar on an inflatable is provided. After deflation, the lower collar is engaged to the mandrel so that the deflated inflatable can be advanced with other connected downhole equipment, such as screens to be expanded, in a location further downhole without swabbing.

Description:
PRIORITY INFORMATION 
   This application claims the benefit of U.S. Provisional Application No. 60/339,030 on Oct. 30, 2001. 

   FIELD OF THE INVENTION 
   The field of this invention is inflatable packers and more particularly those that can be deflated and subsequently advanced downhole without swabbing. 
   BACKGROUND OF THE INVENTION 
   Saving trips in a completion procedure saves money. Recently, screens have been run into open hole and expanded as a technique to replace the need to gravel pack. In these situations it is desirable to isolate the formation pressure from the upper part of the well as the screens are run in. The problem in the past has been that once the inflatable is deflated, trying to advance it further into the wellbore to total depth can cause a condition known as swabbing. In an inflatable, the element has a lower movable collar, which rides uphole as the element is inflated. When the element is deflated the lower collar is free to move on the mandrel. Thus if the screen, which had before deflation been tagged into the inflatable, is advanced with the deflated inflatable, the lower collar will ride up when any portion of the element engages the borehole wall. The element will then ball up in a phenomenon known as swabbing. 
   The present invention addresses this problem by using the downhole force to advance the deflated inflatable with the screen to also keep the deflated element in a stretched condition to avoid swabbing. Those skilled in the art will appreciate the scope of the invention from the illustrative example of the preferred embodiment, which appears below and more particularly for the appended claims based thereon. 
   SUMMARY OF THE INVENTION 
   A latching assembly for a lower collar on an inflatable is provided. After deflation, the lower collar is engaged to the mandrel so that the deflated inflatable can be advanced with other connected downhole equipment, such as screens to be expanded, in a location further downhole without swabbing. 

   
     DETAILED DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic view, showing the inflatable being run in; 
       FIG. 2  shows the inflatable being set; 
       FIG. 3  shows a screen assembly being tagged into the set inflatable; 
       FIG. 4  shows the inflatable being deflated; 
       FIG. 5  shows the assembly of the de3flated inflatable and the screen advanced downhole, where the screen is to be deployed; 
       FIG. 6  is a half section view of the inflatable and the latch system in the run in position; 
       FIG. 7  is the view of  FIG. 6  with the inflatable set; 
       FIG. 8  is the view of  FIG. 7  with the inflatable deflated and latched 
       FIG. 9  is the view of  FIG. 8  with the deflated element stretched out from being advanced downhole. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The overview of the present invention is shown in  FIGS. 1-5 . The inflatable  10  is run in the wellbore  12  on drill pipe, coiled tubing or electric wireline  14 . It is set, as shown in  FIG. 2 , effectively isolating the top of the wellbore  12  from the formation below the now set inflatable  10 . At this time, other downhole equipment can be run into the wellbore  12  without the use of a lubricator at the surface. In  FIG. 3 , a screen assembly  15  is tagged into the inflated inflatable  10 . At the conclusion of the tagging procedure, the inflatable is deflated by mandrel manipulation, in a known manner. As will be later explained, the deflation of the inflatable  10  secures its inflatable element  16  to the mandrel  18  via a latch system  20  (see FIG.  8 ). Thereafter, as shown in  FIGS. 5 and 9 , the element  16  is stretched to its run in position, as the mandrel  18  is advanced downhole with the screen assembly  15 . Those skilled in the art will appreciate that other equipment can be tagged into the inflatable  10  than screen assembly  15 . The inflatable  10  can be run downhole and inflated in a variety of ways. The new feature of the latch system  20  can be executed in a variety of ways to allow a stretching force to be transmitted to the element  16  after it is deflated. This stretching force prevents the element  16  from swabbing, as it is advanced downhole after being inflated and deflated. 
   In the preferred embodiment, the latching system is in the form of a ratchet. As shown in  FIG. 6 , in the run in position, the inflatable  10  has its element  16  in the stretched position to facilitate insertion. Typically the element  16  has a slidably mounted lower collar  22 , which rides up when the element  16  is inflated, as shown in FIG.  7 . In the present invention, the mandrel  18  has an extension  24  secured at thread  26 . Extension  24  has ratchet teeth  28 . Collar  22  has a sleeve  30  attached at thread  32 . Sleeve  30  supports teeth  34 , which selectively engage teeth  28 , as will be explained below. Teeth  34  are retained by end cap  36 , which is secured to sleeve  30  at thread  38 . 
   As the element  16  is inflated, the collar  22  and sleeve  30  both ride up. This movement, shown in  FIG. 7 , tends to bring teeth  34  further away from teeth  28 . It should be noted that during run in and set, there has been no engagement of the teeth  34  and  28 . 
   When the screen assembly  15  has been tagged into the inflatable  10  (see FIG.  3 ), the inflatable is deflated in a known manner by setting down weight and then picking up. As shown in  FIG. 8 , when the pickup force is applied the teeth  28  ratchet past teeth  34 . Subsequent downhole movement of the mandrel  18  with the extension  24  pulls teeth  34  down, since opposed relative movement is precluded by the orientation of teeth  28  and  34 . As shown in  FIG. 9 , the downward force on the mandrel  18  and extension  24 , pulls the deflated element  16  toward its retracted or run in position. The occurs because the lower collar  22  is forcibly pulled down by the latch system  20  while the upper collar (not shown) on the element  16  remains in position with respect to the advancing mandrel  18  carrying with it the lower collar  22 . 
   Those skilled in the art will appreciate that the element  16  will not swab if it is stretched out using the latch system  20  of the present invention. The screen assembly  15  can then be run further downhole and expanded into place against the open hole. Those skilled in the art will appreciate that the present invention encompasses all techniques to grab the element and stretch it out after deflation. The ratchet teeth engagement depicted in the Figures is but one embodiment that is preferred. The full scope of the invention is delineated in the claims, which appear below. Modifications from the embodiment described above are clearly contemplated to be within the scope of the invention particularly if the result is an extension of the element after deflation so that upon further advancement into the wellbore, it will be prevented from swabbing. Apart from ratchets, the stretching of the element can be accomplished with a pressure responsive piston, a J-slot mechanism, or engaging a thread, to mention a few variations. 
   While the preferred embodiment has been described above, those skilled in the art will appreciate that other mechanisms are contemplated to accomplish the task of this invention, whose scope is delimited by the claims appended below, properly interpreted for their literal and equivalent scope. 
   The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made without departing from the spirit of the invention.