Patent Application
20130269956
The field of the invention is packers that are actuated by internal mandrel expansion and more particularly where the sealing element is initially disposed in an external mandrel recess with one or more spikes into the sealing element that act to resist extrusion when the packer is set against a surrounding tubular and exposed to differential pressures.
In an effort to obtain adequate sealing in an environment where the mandrel for a packer or hanger or other annular seal is to be expanded, there have been a variety of approaches. Some adopt an internally tapered wedge ring that is expanded under compressive stress with a wedge that is driven into it. The ring grows in diameter but its exterior configuration remains the same and the sealing element and spikes extending from the ring move into contact with the surrounding tubular to resist seal extrusion. This design is illustrated in U.S. Pat. No. 7,784,797.
Other designs simply push out a short segment of a tubular string that has a seal and extrusion barriers above and below as shown in U.S. Pat. No. 6,959,759 FIGS. 1 and 2.
Other designs combine expansion with external energizing the sealing element, such as U.S. Pat. No. 6,854,522 FIGS. 17-19.
Ring or spike type extending members that retain the seal in place after set by expansion have been used in U.S. Pat. No. 5,511,620 in FIG. 4. More traditional type of end extrusion barriers that are not in the context of mandrel expansion are located at ends of a compression set sealing element as in U.S. Pat. Nos. 5,215,145 and 5,961,123.
US Publication 2010/0314130 shows in FIGS. 3 and 4 the use of internal inserts 40 somehow assembled in a tubular that is to be expanded only in the regions where there are external seals 34 in a recess built into the wall 36. The swage is somehow mounted in the lower end of the tubular with the swage outside diameter about equal to the drift diameter of the tubular as shown at the bottom of FIG. 3. How the inserts 40 are installed and firmly held in place is not discussed. After expansion the entire pipe has the drift of the expander 46 but only segments of the pipe have been expanded and the initial drift of the pipe has not increased because of the presence of the rings 40 being used under the seals 34 assuming the same drift as the rest of the pipe that is not expanded.
The present invention expands the tubular to increase its drift while the initial exterior recess that hold the seal material are expanded into alignment with the new dimension of the tubular. Rings or spikes that extend generally radially from the recesses before the expansion move radially outwardly with the seal and can penetrate the seal on the way to making contact with the surrounding tubular. The rings or spikes function as extrusion barriers under differential pressure loading after expansion. The rings or spikes can also penetrate the wall of the surrounding tubular for metal to metal sealing or for fixation of the assembly due to the wall penetration of the surrounding tubular. Those skilled in the art will better appreciate additional aspects of the invention from a review of the detailed description of the preferred embodiment and the associated drawings while appreciating that the full scope of the invention is to be determined from the appended claims.
A tubular has an exterior sealing element disposed in a recess. A swage passes through the tubular to increase its drift dimension from a location above the seal to below the seal. The interior projection that initially defined the exterior wall recess where the seal is located is expanded to the new drift dimension of the balance of the tubular. Extending members that are initially embedded in the seal while extending from the tubular wall that defines the recess move out during the expansion to engage the surrounding tubular to act as extrusion barriers and to aid in the fixation of the seal while being able to penetrate the wall of the surrounding tubular in so doing.
Referring to
Seal 22 can be Nitrile rubber or HNBR or Alfas for higher temperature applications. It can swell in certain applications and may be covered with a removable cover to delay the onset of swelling until proper placement is achieved.
Extending members 48 can take a wide variety of forms and serve multiple purposes. As shown in
Those skilled in the art will appreciate that the present invention incorporates one or move seals in an exterior recess in a context where the string is expanded over its length to increase the drift diameter and reduce the size of the surrounding annulus with the seal spanning the annulus to contact an open or cased hole. The seal thickness can be increased due to the recess without adding to the exposure of the seals during run in. The presence of the recess also extends the seal reach as the recess is expanded to the original drift dimension of the string and then beyond as the entire string is further expanded. With the use of a variable swage that can then further expand the lower end of the string to make a bell; a monobore completion can be produced. The top end is initially delivered into position with a running string and an anchor and stroker in a known manner and the upper end can be initially fixed to a bell at a lower end of an existing tubular, at which point the running tool can be released and the assembly of an anchor and stroker can advance with each stroke and expand the tubular with the recess or recesses in the wall in a top down direction. A bottom up expansion can also be accomplished by supporting the string on the swage that is below it with the swage supported on the running string. The swage can then be retained in position as a bell is made at its lower end with the swage then being rebuilt to a smaller expansion dimension for the remainder of the expansion until the overlap to the tubular above is reached and the running string is released.
The seal 22 conforms to the shape of the surrounding borehole or tubular upon expansion for the length of the string in which the tubular 10 is to be found. Members 48 then enhance the performance of the seal 22 in the manner described above. The region of the tubular 10 at the location of the seal 22 is expanded more than the adjacent regions but well within the ability of the tubular to retain its desired pressure rating despite some wall thinning due to the anticipated degree of expansion.
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:
