It is usually run in close to the bottom end of the production tubing and set at a point above the top perforations or sand screens.
In general, well completions may not incorporate a packer when the annular space is used as a production conduit.
In situations where the sealed pressure is very high (above 5,000 psi), metal rings are used on either side of the elements to prevent the rubber from extruding.
Axial loads are applied to push the slips up a ramp and to compress the element, causing it to expand outward.
The axial loads are applied either hydraulically, mechanically, or with a slow burning chemical charge.
The main advantages of permanent packers are lower cost and greater sealing and gripping capabilities.
To unset the tool, either a metal ring is sheared or a sleeve is shifted to disengage connecting components.
Retrievable packers have a more complicated design and generally lower sealing and gripping capabilities, but after removal and subsequent servicing, they can be reused.
Also used in wells where the packer must pass through a restriction and then set at a much larger diameter in casing or open holes.
Many variations for specific applications are available including those capable of withstanding high pressure differentials.
Permanent packers are run and set on an electric wireline, drill pipe or tubing.
They are good in wells that have high pressure differentials or large tubing load variations and can be set precisely.