1. Field of the Invention
This invention relates to expandable seals. In one aspect, the present invention relates to sealing systems for use in wellbores.
2. Description of the Related Art
To recover hydrocarbons from the earth, wells are drilled through one or more subterranean hydrocarbon reservoirs. The wells often include a cemented a casing/liner string that strengthen the well (i.e., provide structure integrity) and provide zonal isolation. Typically, the portion of casing adjacent a hydrocarbon reservoir to be drained is perforated so that the hydrocarbons (e.g., oil and gas) can flow into the wellbore.
During the drilling, completion, and production phase, operators find it necessary to perform various remedial work, repair and maintenance to the well, casing string, and production string. For instance, in addition to perforations, holes may be accidentally created in the tubular member. Alternatively, operators may find it beneficial to isolate certain zones. Regardless of the specific application, it is necessary to place certain down hole assemblies such as a liner patch within the tubular member, and in turn, anchor and seal the down hole assemblies within the tubular member.
Referring initially to FIG. 1, there is shown a conventional seal arrangement 10 provided on an end 12 of a tubular member 14 that is to be conveyed and fixed in a wellbore (not shown). The seal arrangement 10 includes metal ribs 16 that act as an anchor and a liquid seal and an elastomer seal 18 that acts as a gas seal. The end 12 is adapted to be expanded diametrically by a swage 20 that is driven axially into the end 12 in a telescopic fashion. In one conventional arrangement, the elastomer seal 18 is positioned approximate to the outer portion of the end 12 and has a rectangular cross section. The radial expansion of the end 12 by the swage 20 expands the seal 18 until it contacts the casing wall (not shown). Further expansion of the seal 18 increases the compressive force applied to the casing wall (not shown) by the seal exterior surface 24. Of note is that the substantially rectangular cross-section of the seal 18 causes all of the exterior sealing surface 24 to contact the casing wall (not shown) at substantially the same time. Therefore, there is a distributed loading of the compression forces applied by the seal 18.
The FIG. 1 embodiment has performed satisfactorily in a variety of applications. Nevertheless, there is a persistent need for wellbore anchoring and/or sealing devices that can meet the ever increasing demands posed by evolving wellbore construction techniques. The present invention is directed to meet these challenges.