The Underbalancing Pressure
Sub - Ported version, is used in a perforating
system to provide an economical method of achieving an underbalanced
condition between the tubing and the wellbore formation.
The tool incorporates a high strength ceramic dome which
prevents communication between the tubing and annulus until
a detonating bar is dropped from surface. The ported sub
is normally run below a packer system, the ports are located
below the ceramic dome to allow flow into the tubing.
The ported underbalancing pressure sub is
installed in the tubing string normally below a packer system
to create the desired underbalanced condition as well as
replaces a fill-flow sub assembly. The ported section is
located below the ceramic dome, this ported section area
is always equal to or greater then the tubing i.d. cross
sectional area which does not restrict or choke the wellbore
flow into the tubing once the dome has been shattered from
the drop bar passing through the tool.
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