Modeling and Validating Pressure Transient Effects on Inflatable Bridge Plugs during Coiled Tubing Conveyed Perforating

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 design.

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.