PACKER

摘要

A packer (2) for an oil gas or water well comprises a radially expandable member (16) to seal off e.g. an annulus between the well casing and a tubing string that carries the packer. The packer has a fluid chamber, a fluid injection device (8) adapted to inject fluid into the fluid chamber to cause expansion of the radially expandable member, and a one-way device to prevent fluid egress from the fluid chamber after injection, and thereby maintain the expansion of the radially expandable member within the annulus. The one-way device can be a ratchet (6r, 8r) or a valve.