It is known that the performance of inflatable packer is susceptible to
the pressure change after it is set. When setting an inflatable bridge plug and
then perforating nearby, it was "conventionally" believed that inflatable plug
would fail when subjected to the perforating gun-shock loads. A common practice
to protect the inflatable from these shock loads is to place an additional
barrier to absorb these loads.
During one such instance, an offshore operator required setting an
inflatable bridge plug and then stimulating the zone above it. However, after
the plug was set, a contingency came up as it was not possible to open SSD of
this zone. In order to stimulate this zone, perforating this zone was requested
by the client. Due to the time and equipment limits, placing an additional
barrier above the plug to protect it from the gun-shock loading was deemed
impractical and seen as an unnecessary operational delay.
In this proposed perforating operation, the risk caused by the pressure
surge from perforating to the inflatable plug had to be evaluated. Risk
evaluation requires the modeling of the perforating-generated pressure surge.
This paper presents a methodology to simulate pressure transients reliably both
in magnitude and time and evaluate the risks involved with the inflatable plug.
The impact of these pressure transients on the inflatable plugs can then be
analyzed during job planning. This methodology enables engineers to evaluate
the job risks, mitigate these risks, and then be able to optimize the operation
One case study will be presented in this paper. With the ability to
predict the pressure surge, a decision, such as whether or not to need an
additional barrier between the perforating gun and inflatable plug to absorb
the pressure surge, can be made, and a successful operation of inflatable plugs
with perforation can be expected.
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