Page 127 - Well Control for Completions and Interventions

Completion Equipment 119

dynamic seal helps reduce axial loads caused by pressure and temperature
changes in the tubing. Most dynamic seals will no-go at the packer, limit-
ing downward movement. Upward movement is not normally restricted,
and so extremes of temperature (cooling) and pressure (ballooning and
piston forces) could cause the seals to stroke out the top of the packer.
Seal length can be varied, and will depend on how much movement is
expected when the well is in service.

3.12.4 Seal bore extension
Some seal assemblies can be quite long, in excess of 25 ft. The seal bore
section of the packer, on the other hand, is usually short. Two or three
feet is typical. If seals are continually moving in and out of the seal bore
they will be prone to damage. To prevent this, an extension of the seal
bore can be run on the bottom of the packer.

3.12.5 J-Latch connector
Some seal stacks will be anchored to the packer using a j-slot or j-latch
device above the seals. This allows the seals to be un-jayed from the
packer, and the upper completion removed for workover.

3.12.6 Seal assembly and polished bore receptacle (ELTSR) d
A seal assembly/PBR is subtly different from the locator seal assembly,
but fulfills the same purpose as the locator seal. Whereas the locator seal
stabs into a seal bore within the body of the packer, the PBR is posi-
tioned above the packer. PBRs generally have a larger through bore than
a locator, usually matched to the tubing ID. They are used where a lot of
seal movement is anticipated (Fig. 3.26).

3.12.7 Telescoping joint
The telescoping joint can be used instead of the seal assembly. It performs a
similar function—expansion and contraction of the tubing string. The only
advantage of the telescoping (expansion) joint is that it can be positioned
anywhere in the string. However, they are rarely used in modern comple-
tion as they are not normally as reliable or robust as a seal assembly. They
are still widely used to allow string movement in well test DST strings.

d
ELTSR-Extra long tubing seal receptacle.