Oil Rig Explosion

By ThinkReliability Staff

On April 20, 2010 about 10 pm a huge explosion rocked a semi-submersible drilling oil rig about 40 miles off the coast of Louisiana in the Gulf of Mexico. The oil rig was called the Deepwater Horizon and was owned by Transocean Ltd and leased to the British Petroleum Company through September 2013.

The oil rig burned for about 36 hours before sinking.  126 people were on the oil rig at the time of the explosion.  Eleven are missing and presumed dead and 4 were critically injured. Oil continues to leak from the wellhead more than a mile underwater on the ocean floor at an estimated rate of 42,000 gallons a day.

Remotely operated submersible vehicles were used to examine the wellhead.  The vehicles were also used in an effort to manually trigger the blowout preventer, which would close the wellhead and prevent any farther release of oil.  The blowout preventer is a 450-ton valve installed at the wellhead that is designed to automatically shut to prevent oil leaks in the event of an accident.  Attempts to manually close the blowout preventer have not been successful.

The other containment options being explored are drilling a separate well nearby to plug the flow at a location below the blowout preventer and building underwater domes that would contain the oil until it could be safely pumped to the surface for disposal.  Both of these alternatives are being actively worked and will take months to complete.  It is estimated that 4.2 million gallons of oil will be released if the blowout preventer is not able to be closed.

The cause of the explosion is unknown at this time.  An investigation is underway by the Coast Guard and the Minerals Management Service.

A preliminary root cause analysis can be started using the information that is known and details can be added as they become available.  The analysis can be documented using a Cause Map which is a simple, intuitive format that visually lays out all known causes for an incident.  The first step in building a Cause Map is to determine how the organizational goals were impacted by the incident.  Causes for each impacted goal are determined to begin building the Cause Map.

In this case, the safety goal was impacted because 11 people were killed and several injured.  The environmental goal was impacted because there was a significant oil release.  The materials goal was impacted because the $700 million oil rig is a complete loss and the production/schedule goal was impacted because the oil drilling operation is shut down.

Click on the “Download PDF” button above to view an initial Cause Map.