First Barrier: Cement Job
In this process safety training video Professor Andrew Hopkins analyses the failure of the barriers or controls that should have prevented the Macondo blowout in the Gulf of Mexico. If any one of these barriers had worked as intended, the blowout would not have occurred.
In examining why they all failed, he looks at how independent the barriers were, or rather, how interdependent they were. The barriers behaved like falling dominos. Once one fell, all the others followed. What happened at Macondo was the failure of the system of defence in depth. It wasn’t just one or two barriers that failed, but the whole system.
The first barrier was a physical barrier - a cement plug.