1. Field of the Invention
The present invention generally relates to the design of axial containment systems for packer devices.
2. Description of the Related Art
Packers are used to form fluid seals between an inner tubular string and an outer tubular string which radially surrounds the inner tubular string. A common form of packer device is a “squeeze” type packer wherein an elastomeric packer element is axially compressed in order to cause it to expand radially outwardly and into sealing contact with the surrounding tubular member.
When used at great depths, where there are high temperatures and pressures, the elastomeric elements used in packers begin to break down. As a consequence, the elastomer may extrude and bleed out into the area between the packer and the surrounding tubular. If the elastomeric element extrudes out excessively, the sealing capability of the packer device will be destroyed.
Containment devices are used to try to prevent undesirable extrusion of the elastomeric element. Usually, the containment device consists of a pair of anti-extrusion containment rings that are located on each axial side of the elastomeric element. Typically, these rings are formed of a solid material that, while more rigid than the elastomeric element, will deform and at least partially envelop the axial ends of the elastomeric element during all stages of packer operation.
The invention relates to the construction of packer devices as well as gage ring back-up arrangement used with packer devices. In particular aspects, the present invention provides a gage ring that is used to provide support to an anti-extrusion containment ring in a packer device. In a currently preferred embodiment, the gage ring includes a compression ring and a plurality of interlocking arcuate segments. A first set of segments each have a wedge-shaped body that is wider at a proximal axial end than it is at its distal axial end. A second set of segments preferably each have a wedge-shaped body wider at its distal axial end than it is at its proximal axial end. The first and second arcuate segments are disposed radially around a central mandrel for the packer device in an alternating fashion such that a first segment is disposed between each two of the second segments and vice versa. In a preferred embodiment, the first and second segments are interlocked with one another by a tongue-in-groove type connection which permits the first and second segments to slide axially with respect to each other while maintaining the segments in radial alignment with each other.
The packer and gage ring assemblies are set by axial movement of a compression member. During setting, the first segments are moved through sliding action from the tongue-in-groove arrangement in between the second segments. All of the segments are collectively displaced radially outwardly as this occurs so that the gage ring assembly presents a larger diameter than in the unset condition. In the set condition, the distal end surfaces of both the first and second segments provide a substantially unbroken support wall for an adjacent packer containment ring.
The gage ring assembly can be unset and returned to a radially reduced condition by moving the compression member axially away from the packer element. This movement will withdraw the first segments from in between the second wedge members, thereby permitting all of the segments to move radially inwardly with respect to the mandrel.
The advantages and other aspects of the invention will be readily appreciated by those of skill in the art and better understood with further reference to the accompanying drawings in which like reference characters designate like or similar elements throughout the several figures of the drawings and wherein:
The packer device 10 includes a central tubular mandrel 12 which defines a flowbore 14 along its length. An elastomeric packer element 16 radially surrounds the mandrel 12. Annular metallic containment rings 18, 20 are located on each axial side of the packer element 16. The containment rings 18, 20 are preferably slightly elastically deformable and each is formed to envelop or partially envelop the respective axial end of the packer element 16. It is noted, with reference to
Gage ring assemblies, generally shown at 22 and 24, surround the mandrel 12 and lie axially outside of the containment rings 18, 20. In the depicted embodiment, the gage ring assemblies 22 and 24 are substantially identical to one another in terms of construction and operation. Therefore, a description of the construction and operation of one gage ring assembly will serve to describe both gage ring assemblies 22, 24. The gage ring assemblies 22, 24 each include an annular compression ring 26 which radially surrounds the central mandrel 12. In usual operation, one of the compression rings 26 is affixed to the mandrel 12. The other compression ring 26 is axially moveable with respect to the mandrel 12. The compression ring 26 may be moved by means of a hydraulic setting arrangement (not shown), of a type known in the art, or in other ways known in the art. Preferably, the compression rings 26 each present a plurality of generally T-shaped projections 28 (see
The gage ring assemblies 22, 24 each include a first set of arcuate segments 32. A single segment 32 is depicted in
The gage ring assemblies 22, 24 also include a second set of arcuate segments 54.
As can best be seen in
In operation, the gage ring assemblies 22 and 24 provide structural support to the containment rings 18, 20. During setting of the packer device 10, a setting force is applied to the compression ring 26 using means known in the art. The shear pin 75 is ruptured, and the compression ring 26 is moved axially with respect to the mandrel 12 toward the packer element 16. The gap 21 between the containment ring 18 and the packer 16 is closed. The first segments 32 are then moved in between the second segments 54 so that the diverging side walls 44, 46 of the segments 32 will slide against the side walls 68, 66, respectively of the segments 54. The segments 32 and 54 are both physically displaced radially outwardly and away from the inner mandrel 12, as depicted in
It is noted that the gage ring assemblies 22, 24 are moveable between a reduced diameter condition (when not set) and an enlarged diameter condition (when set). As can be seen with reference to
When the packer device 10 is run into a surrounding wellbore, the packer device 10 is in an unset position wherein the packer element 16 is at a reduced diameter condition. Also, the gage ring assemblies 22, 24 are in a reduced diameter condition. However, when the packer device 10 is set, the segments 32 and 54 orient themselves through a compressive load from the compression ring 26 to a final, expanded diameter condition gage ring that is greater than the reduced diameter condition. Further, the expanded diameter of the gage rings 22, 24, when so set, is greater than the diameter of the containment rings 18, 20. The inventors have found that the ability of the gage ring assemblies 22, 24 to expand in this manner is advantageous in that, when the gage ring assemblies 22, 24 are expanded radially, to a larger diameter than the compression ring 26, they provide superior support to the containment rings 18, 20.
Unsetting the packer device 10 is done by moving the compression ring 26 axially away from the packer element 16 upon the mandrel 12. As the compression ring 26 is moved away from the packer element 16, the first set of segments 32 are pulled axially away from the segments 54 allowing the gage ring assemblies 22, 24 to return to their reduced diameter condition.
Those of skill in the art will recognize that numerous modifications and changes may be made to the exemplary designs and embodiments described herein and that the invention is limited only by the claims that follow and any equivalents thereof.