Page 254 - Well Control for Completions and Interventions

248 Well Control for Completions and Interventions

direction of circulation and invalidate any pressure observation made on the
annulus.
If a well has not been completed with a circulating device, communi-
cation can be established by punching holes in the tubing. There are
several considerations before punching the tubing:
• A mechanical punch run on slickline is simple and inexpensive, but
only creates a single hole. Circulation rates will be restricted.
• An explosive punch using shaped charges will produce a flow area
equal to or greater than the flow area through the tubing.
• If an explosive punch is used, it should be designed for limited
penetration. This is to prevent casing damage when the tubing is
perforated.
• An explosive tubing punch can be run on slickline using a time delay
detonator, but if depth is critical it is better to run it on e-line and use
Gamma ray and Casing Collar Locator (GR/CCL) to place the punch
accurately on depth.
• To prevent any debris that has settled on the packer entering the tub-
ing, a space is normally left between the packer and the location of
the punch, typically, at least 50 ft.
Before opening or creating a communication flow path, it is important
to minimize pressure differential between tubing and annulus. To do this,
SITP 1 tubing HP and SICP 1 casing HP at the depth of the communi-
cation device must be calculated. If there is uncertainty about the depth
gas/oil and OWCs, pressure gauges can be run. If this is not possible,
tubing pressure at the point of circulation may have to be estimated.
• Pressure differential across a sliding sleeve (SSD) will make it more
difficult to open.
• There is a risk of the wireline tools being “blown up the hole” if that
differential is from annulus to tubing.
• When punching a hole in the tubing, there is a risk of the wireline
tools being “blown up the hole” if there is too great a pressure differ-
ential from annulus to tubing.
• If a dummy valve needs to be pulled from a side pocket mandrel, there
is a risk of the wireline tools being “blown up the hole” if there is too
great a pressure differential from annulus to tubing.
• If a gas lift unloading valve or gas lift orifice valve need to be pulled
from a side pocket mandrel, pressure from the annulus will equalize
across the valve to the tubing. Pressure differential from tubing to
annulus will make the valve more difficult to pull.