Patent Application
20140131953
The field of the invention is sealing and/or centralizing devices that can be deployed of a tubular string at a subterranean location and more particularly structures that are self energized and held retracted for release at a desired location and subsequent retraction for removal from the subterranean location.
Cup seals are called that because of their shape. They are closed at an end where they are mounted to a mandrel and open on an opposite end so that pressure applied in one direction pushes the edge of the cup outwardly to enhance the seal. The closed end can be backed up with rings that have the same cup shape which provide structural support against differential pressure on the inside of the cup and behind the lip of the cup that is against a surrounding tubular. The cup wall can be reinforced with internal ribs. Other mechanisms apart from the self energized feature of the cup shape generally rubber can be used to enhance the seal other than applied differential pressure in the cup and one such technique is to energize the ribs with external power sources. Some examples of one or more of these features are US Publication 2003/0098153 FIGS. 1 and 2; U.S. Pat. No. 7,357,177 noting the scalloped interior of the inside wall in FIGS. 4A and 4B; U.S. Pat. No. 4,424,865 using shape memory ribs in a geothermal application to enhance a seal; U.S. Pat. No. 7,703,512 using a rubber backup ring to push a rib into a packer cup wall; US Publication 2003/0098153 illustrating a composite wall structure for a packer cup; US Publication 2010/0243237 showing use of pairs of packer cups to isolate a zone to create relative movement between components and US Publication 2012/0217004 illustrates a multilayered ring with overlapping elements that are radially extended from expansion of an underlying mandrel to enhance the seal of a surrounding swelling packer element.
USRE 41,118 FIGS. 28 and 29 shows a petal design in multiple rows where the petals are circumferentially offset and retained with a band 314 for run in. Pipe 312 is expanded to break the band 314 and allow the petal rows to radially move toward the borehole wall as shown in FIG. 29.
The seal and centralizer of the present invention can have application in expansion methods where the seal is not itself expanded as shown in US Publication 2012/0061097 or US Publication 2012/0085549.
U.S. Pat. No. 6,725,939 illustrates a centralizer that can be expanded. US Publication 2008/0190602 illustrates another centralizer design.
The present invention is envisioned in a seal or centralizer configuration. It features a Self-energized construction that is retained for run in to have a small dimension and released at a desired subterranean location. This can happen in a variety of ways one of which is axially shifting a sleeve that overlays the structure to adjacent the structure by a variety of motive sources. In the shifted position the retainer can back up the structure. The structure is preferably in multiple rows when retracted and then when allowed to expand reconfigures to a single row with edge ledges used to align adjacent segments as all the segments move outwardly to reach a surrounding borehole wall. The edge ledges are on alternate segments so that in between another segment rests on the ledges on opposed sides. Such structures can be stacked with each assembly in the stack as described above. The stacks can also be spaced to isolate zones or they can function as backup to each other against flow in a single direction while permitting flow in an opposite direction. The extended position can also be changed to a retracted position for removal of the seal or centralizer structure by shifting a sleeve that released the structure in an opposite direction where the sleeve has internal splines that push in the segments with end ledges first so that the single row of segments can then revert to multiple rows as the sleeve progresses to a position where the segments are substantially overlaid. The structure can function as a centralizer that permits flow therethrough by leaving out alternate segments in which case the internal splines in the sleeve can be eliminated. These and other features of the present invention will be more readily apparent to one skilled in the art from a review of the description of the preferred embodiments and the associated drawings while recognizing that the full scope of the invention is to be found in the appended claims.
A self energizing structure can function as a centralizer or as a seal when allowed to spring out after a retainer is moved away from an overlying position for run in to protect the structure. Segments extend from a common base ring and are radially offset during run in. Alternating segments have landing surfaces on opposed ends such that on release of the structure the intervening segments land on such surfaces to form a cohesive single layer with all segments circumferentially aligned and against a surrounding tubular or the borehole wall. The structure is held retracted with a bi-directionally movable sleeve operable in a variety of ways from the surface. Internally the sleeve has splines to push the segments with the landing surfaces back so that the structure can collapse back into the sleeve for removal. Structures can be stacked and used as centralizers with alternating segments removed.
The nature of the seal assembly is best understood using
Those skilled in the art will appreciate that a structure that can function as a seal or as a centralizer is disclosed that can be held retracted with a shiftable sleeve that overlays it for run in and pulling out of the hole. The structure can be self energized to move out radially when the sleeve is withdrawn and alternatively can be pushed out by a swage into a sealing position. The general shape is a cup with an open end to prevent flow in the direction of going into the cup open end while allowing flow in the opposite direction. The cup can be formed of at least two layers that in the running in position radially overlay each other. In the deployed position gaps open between segments on the at least two layers such that the segments of an outer layer drop into alignment with segments from an inner adjacent layer so that the segments are at the same radial distance from the mandrel that passes through an opening in the seal assembly. The segments are shaped so that on a predetermined amount of radial movement their shapes conform to the shape of an opening gap between segments on another row so that alignment occurs circumferentially. Alternating segments have edge landing surfaces to align the segments from the adjacent layer that then get into place. The result is a single circumferential layer. The sleeve can have internal splines that push in the segments with edge supports first to allow gaps between segments to again be restored so that such gaps can get smaller as the assembly collapses to the run in condition. Leaving out alternative segments allows the structure to function as a centralizer while letting flow therethrough. In that instance the covering sleeve does not use the internal splines. When used as seals or centralizers the assemblies can be provided as redundant to each other with the open cup orientations identical or the orientations can be opposed for isolation and pressuring up between spaced seal assemblies. The segments and the base that connects them in any given layer or all the layers can be coated for durability and enhanced sealing engagement between the segments. A variety of applications are envisioned in vertical and horizontal wells. The sleeve can be fully retracted away from the segments and the base from which they extend or part way as desired.
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:
