Dynamic Kill Method Using Staged Fluid Densities can Improve the Killability of Relief Wells for Challenging Blowouts

Abstract

In the event of a blowout, the kill method that usually has the highest probability of success is a relief-well intervention. After the relief well gains hydraulic communication with the blowing well, a dynamic kill is often used to bring the well under control. In some cases, the pumping operation may call for more than one fluid density, which is referred to as a staged kill. Although the staged-kill technique has been around for a long time and has been successfully used on many blowouts, little information is available on applications, benefits, technical challenges, and operational requirements. In this paper, two case studies demonstrate how a staged kill can successfully kill challenging blowouts under various conditions. One example, for a staged-kill application, is an actual gas-condensate blowout that could not be brought under control with a standard dynamic-kill operation. Staging a heavy kill mud ahead of a lighter mud that would not fracture the exposed formations successfully killed the well. The second example summarizes the results from a relief-well contingency study for a planned high-pressure, ultradeepwater well with a weak formation that would be fractured by the required kill mud. Dynamic simulations demonstrate that a lighter mud circulated ahead of the static kill fluid could bring the well under control without fracturing the weak zones.