Patent Application
20060266514
The field of this invention relates to expandable downhole tools and more particularly to such tools with enhanced exterior features for bridging an annular gap around the tool.
In the past in the context of downhole tools that employ expansion to seal an annular gap around its mandrel the degree of sealing contact of a resilient sleeve mounted to the mandrel with the surrounding wellbore could be controlled in two ways. One way was the degree of expansion from within the mandrel afforded by the swage being employed. Another way was to simply alter the thickness of the sleeve mounted to the mandrel. For a given borehole size, a thicker resilient sleeve resulted in a tighter seal of the sleeve against the surrounding borehole for a given amount of mandrel expansion with a swage. A given size pipe had limits on how much it could be expanded. On the other hand keeping many versions of a tool on a job site that have different thicknesses of resilient sleeves is impractical logistically and is very expensive. What is needed in an expandable tool is a way to activate the exterior member be it a seal in the form of a resilient sleeve or a porous member to be subsequently used for passing or filtering fluid. The present invention provides this opportunity. It employs the progressive expansion of the mandrel to move a ring into the exterior member to compress it and increase its outer dimension. The ring is capable of being locked to the mandrel after being moved by the swage that moves within the mandrel. The ring can expand so as to not put the swage in a bind while still having a capability to latch to the mandrel to prevent the exterior member from snapping back in length at the conclusion of the expansion.
The invention can be compared to known techniques one of which is illustrated in U.S. Pat. No. 6,530,574 where the mandrel is pushed in to accommodate a sealing material on the exterior of the mandrel. The swage is passed through the mandrel pushing out the interior projection that initially allowed the sealing material to sit flush with the mandrel exterior wall for run in. By returning the inner dimension of the mandrel back to a cylindrical shape the sealing material is pushed radially outwardly into contact with a surrounding tubular. Other known art keeps packer sealing elements from extrusion when they are squeezed longitudinally by a setting sleeve device. This tool, shown in U.S. Pat. No. 6,203,020 does not involve mandrel expansion. Yet other designs simply use mandrel expansion to engage a seal on the exterior of a casing patch with a surrounding wellbore tubular. Some examples of this design are U.S. Pat. No. 6,622,789 and U.S. Applications 2003/0102127 and 2004/0016544.
Those skilled in the art will better understand the invention from the description of the preferred embodiment, the drawings and the claim, all of which appear below.
An expandable downhole tool features a mandrel that is expanded from within by a swage or other technique. The expansion of the mandrel advances an exterior ring or comparable slidably mounted object against an exterior sleeve that can be impervious or porous. The ring engages a ratchet mechanism to hold its position with respect to the mandrel as the swage advances through the mandrel and expands the ring and the exterior sleeve. The locking of the ring to the mandrel keeps the exterior sleeve from springing back longitudinally as the expansion is concluded.
In a packer application of the present invention the mandrel 10 defines a passage 12 that runs along the longitudinal axis 14. A sleeve 16 is connected to mandrel 10. A recess 18 on the mandrel 10 accepts a protrusion 20 on the sleeve 16. A bonding agent (not shown) can be used in the recess 18 or/and elsewhere wither on the sleeve 16 or the portions of the mandrel 10 that it contacts. Preferably the sleeve 16 is rubber bonded to mandrel 10 but other materials that seal against a borehole wall or casing can be used in a packer application.
As shown in
Ring 22 can be a C-ring with a single split or it can be made of segments that are retained together such as with a band spring. Those skilled in the art will appreciate that even though the mandrel 10 is expanded into a set position that it can be re-stretched after expansion for a release. A recess 36 can also be fitted on the ring 22 to allow a fishing tool to grip it and pull it so that the locking devices such as 24 and 32 fully disengage to allow the sleeve 16 to further elongate and thereby reduce its diameter to facilitate removal of the tool.
The tool offers the ability to employ an enhanced squeezing force for better wellbore contact. It also eliminates the need for matching thickness of sleeve 16 to the available swage or the anticipated well dimensions. The orientation of the sleeve 16 and the ring or other structure 22 that compresses the sleeve 16 can be reversed from that shown in the Figures if the direction of expansion is reversed. Preferably the end 38 closest to ring 22 is not secured to mandrel 10 and may actually optionally not even initially touch the mandrel 10 until after longitudinal compression.
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:
