Liner Hanger

A liner hanger is a tool system used to hang a liner in a production well. Unlike casing, it is not run through the full depth of the well: the hanger allows the liner — the casing below it — to be suspended in the previous casing string, reducing material cost and providing completion solution options. A seal is required at the top of the liner hanger to prevent transfer of fluid or pressure from either direction.

Aside from its structural role in well construction, the purpose of the liner hanger is to isolate flow up inside the liner rather than the annular space, which is what would carry that flow if no liner hanger were set. Liners save on metal cost, since the pipe does not run to the top, and sometimes on cementing cost, as some liners are not cemented.

The feature that distinguishes a liner from a regular casing column is that it starts not at the top of the well, but at some point below ground — usually deeper than 1,000 m.