| 摘要 |
The packer includes the usual outer bladder, which is inflated against the sides of the borehole, to seal around a work-pipe. But the packer also includes an inner bladder. The packer is mechanically secured to the work-pipe by the grip of the inner bladder around the work-pipe. The inner bladder is sucked outwards by a vacuum pump, to enable the packer to be moved along the work-pipe. The same port through which vacuum w as admitted to the inner bladder can then be used to admit pressurised fluid to the outer bladder.
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