DEEPWATER HORIZON (2010) | Novatug Maritime Wiki

Classification

Incident Type: Fire / Sinking
Severity: High
Tug involvement: no
Tug mechanism: N/A

Mass rescue operation, major marine casualty.

Vessel Details

Field	Value
Vessel Name	DEEPWATER HORIZON
Vessel Type	Offshore Vessel
Flag State	Marshall Islands [MH]
IMO Number	8764597
MMSI	538002213
Official Number	2213
Call Sign	V7HC9
Gross Tonnage	32588
LOA (m)	114
Breadth (m)
TEU
Year Built	2001
Crew Size	126

Incident Details

Field	Value
Date	2010-04-20
Location	Mississippi Canyon Block 252
Coordinates	28.7380, -88.3650
Region	Gulf of Mexico
Fatalities	11
Injuries	16
Missing	0
Outcome	Two explosions and an uncontrollable fire followed a Macondo well blowout; 115 people survived, 11 crew members were missing and presumed deceased, 16 were injured, and the MODU sank on 22 April 2010.
Direct Damage
Estimated Economic Damage

Key facts

Hydrocarbons rising from the Macondo well ignited at about 21:50 on 20 April 2010, causing two explosions and a massive fire.
The blowout could not be shut in or disconnected from the wellhead, so hydrocarbons continued to fuel the fire.
115 people evacuated and survived; 11 crew members were missing and presumed deceased, and 16 people were injured.
Firefighting vessels worked for about 36 hours while rescue and recovery operations continued. The MODU sank at 10:26 on 22 April 2010.
The investigation identified deficiencies in well-control decisions, emergency procedures, fire protection, crew training, watertight integrity, and coordination of firefighting operations.

Narrative

At approximately 21:50 local time on April 20, 2010, the MODU DEEPWATER HORIZON was conducting temporary well abandonment operations at the Macondo Prospect when an influx of hydrocarbons bypassed barriers and reached the rig floor. Earlier that evening, a second negative pressure test had been judged successful, and the crew began displacing drilling mud with seawater. Abnormal pressure changes were not recognized as a well kick until the influx was already developing. The flammable gas ignited, creating two catastrophic explosions that destroyed the main power and disabled the emergency disconnect system. Unable to stop the flow of gas and oil fueling the inferno, the master ordered the vessel abandoned. Lifeboats and liferafts were deployed, while several crew members jumped into the sea. The offshore supply vessel DAMON B. BANKSTON retrieved 115 survivors. 11 crew members remained missing and were presumed dead. Firefighting vessels spent 36 hours trying to quench the fire while ROVs attempted to actuate the blowout preventer, but these efforts failed. The massive amount of firefighting water, coupled with blast damage to watertight boundaries, caused the DEEPWATER HORIZON to list, capsize, and sink at 10:26 on April 22, 2010.

The joint investigation reported that the precise ignition sources could not be definitively established, but testimony and evidence placed the first explosion and fire near the drill floor. It also identified a loss of electrical power, ineffective fire-pump availability, gaps in emergency procedures and drills, and blast damage that compromised fire and watertight boundaries. Investigators could not determine the exact loss-of-stability mechanism. Possible factors included explosion and fire damage, accumulated firefighting water, and migration through damaged, poorly maintained, or open watertight barriers. These findings describe the investigation's evidence and system deficiencies rather than a single isolated failure.

The report therefore left the precise sinking mechanism unresolved on the available evidence.

Sequence of events

Date/time	Event
2010-04-20 about 21:50	Hydrocarbons from the Macondo well ignited on DEEPWATER HORIZON.
2010-04-20	Two explosions followed, the MODU lost power, and the fire became uncontrollable.
2010-04-20 to 2010-04-21	Crew members evacuated by lifeboat, liferaft, and by jumping into the sea; DAMON B. BANKSTON rescued survivors.
2010-04-22 10:26	DEEPWATER HORIZON sank into the Gulf of Mexico.

Contributing factors

Factor	Evidence status	Description
Loss of well control	Confirmed finding	Hydrocarbons reached the drill floor and ignited during temporary well-abandonment operations.
Blowout preventer and emergency disconnect	Confirmed finding	The well could not be shut in or disconnected, allowing hydrocarbons to continue fueling the fire.
Emergency-procedure deficiencies	Confirmed finding	The investigation identified failures in emergency notification, evacuation preparation, drills, and command and control.
Fire-protection limitations	Confirmed finding	Explosions caused a total loss of power, disabling electrically driven fire pumps, while fire boundaries did not contain the hydrocarbon fire.
Uncoordinated firefighting and downflooding	Confirmed finding	Firefighting water accumulated in the MODU after blast damage and compromised watertight boundaries, contributing to the loss of stability and sinking.

Investigation

The United States Coast Guard and the Bureau of Ocean Energy Management, Regulation and Enforcement conducted a joint investigation and issued the report of investigation published on 1 April 2011. The report covered the well-control events, explosions, fire, evacuation, sinking, safety systems, and loss of life. It identified numerous system deficiencies and acts or omissions affecting well control, fire protection, emergency response, crew training, watertight integrity, and firefighting coordination.

References

USCG / BOEMRE source note
USCG / BOEMRE report of investigation