| 摘要 |
<p>Method and apparatus 10 for sealing a borehole comprising two seals 54 & 56, arranged so that when an axial compressive force is applied the first seal is compressed, expands circumferentially and extended radially, the second seal is held in the uncompressed configuration, once the first seal is fully extended the compressive pressure extends the second seal. An intermediate seal element 20 may be provided to restrict the compression of the second of the paired seals. The axial compression may bypass the second sealing element by means of an axial support member 50, which may be equipped with a shearable region 52 to compress or buckle the deformable material of the duplicate seal once the first seal has been compressed.</p> |
