Examples of landmark accidents from offshore engineering past (compiled and adapted from Christou and Konstantinidou (2012), Oil Rig Disasters (2019) and completed with own research).
| Accident | Location | Losses | Description | Relevant outcomes |
|---|---|---|---|---|
| Sea Gem Rig Collapse | UK Continental Shelf, 1965 (United Kingdom) | Total property loss and 13 life losses | Two of the rig's ten legs failed, leading the rig to fall sideways. Subsequently, the rig was reported to capsize and sank with one leg remaining above the sea | – |
| Santa Barbara Oil Spill | California coastline, 1969 (USA) | More than 71,400 barrels of crude loss and unprecedented environmental destruction | A first well blew out, spewing oil and gas, which then led to an explosion that cracked the sea floor in 5 places and released 1,000 gallons of oil an hour. A second blow out in a different well followed on two months later | This event is considered to have led to the signing of the National Environmental Policy Act, which required the creation of environmental impact reports on major projects. It is also known for its positive impact on environmental awareness by regular Americans towards offshore drilling and exploitation |
| Ekofisk B Blowout | North Sea, 1977 (Norway) | Estimated production loss between 80,000 to 126,000 barrels, largest blowout in North Sea | Oil well blowout occurred at the Ekofisk Bravo platform, due to an incorrectly installed downhole safety valve. This resulted in the well blowing out with an uncontrolled release of oil and gas. Human errors were the major factor which led to the mechanical failure of the safety valve. These errors included faults in the installation documentation and equipment identification and misjudgements, improper planning and improper well control | – |
| Ixtoc I Blowout | Gulf of Mexico, 1979 (Mexico) | Extensive damage along the US coast with the Texas coast suffering the greatest. Biggest single spill before the occurrence of Macondo accident, with an estimated 3·5 million barrels of oil lost | Well suffered a blowout, with oil and gas flowing to unrestricted surface igniting and engulfing the semi-sub Sedco 135F in flames. Later the rig collapsed and sank onto the wellhead area on the seabed. Oil and gas leakage lasted for 9 months ending in an oil slick of 180 km by 80 km | – |
| Bohai 2 Jack-up | Gulf of Bohai, 1979 (China) | 72 life losses (2 survivors) | Jack-up faced major storm waves and wind loads which overtopped the main deck and broke a ventilator pump free, causing it to fall and puncture the deck, which caused a flood in the pump-room. The rig became unstable and due to harsh weather conditions the jack-up capsized and sank | Improvements were made in regulations and standards related to emergency and evacuation procedures, usage of lifesaving equipment and proper equipment storage at platforms |
| Alexander L. Kielland capsize – floating hotel | North Sea, 1980 (Norway) | 123 life losses (89 survivors); Total asset loss | Failure of supporting leg due to severe gale force winds, but not severe storm. Problems were detected in a weld of an instrument connection on the bracing which contained cracks | Improvement of failure cause analysis and increasing standards for evacuation and rescue operations |
| Piper Alpha explosion | North Sea, 1988 (Scotland) | 167 life losses, including 2 operators of a Fast Rescue Craft (62 survivors) and property damage estimated in € 2 billion | Condensate leak resulting from maintenance work being carried out simultaneously on a pump and related safety valve led to gas ignition and explosion, causing fire and sequential explosions in risers and structural damage with the further release of gas and oil | The Cullen inquiry resulted in more than 100 recommendations that re-shaped offshore safety legislation and practices, namely in chains of command and communication procedures for platform's crew. Necessity of creating fire and blast walls at the platforms. Increased regulations on safety at offshore installations |
| Seacrest Drillship | Platong Gas Field, Gulf of Thailand, 1989 (Thailand) | 91 life losses and total asset loss | Drillship capsized in heavy seas during Typhoon Gay. No distress signals were heard from the Seacrest and none of its lifeboats were found, suggesting that capsize occurred too quickly for the crew to respond | – |
| Adriatic IV Blowout | Mediterranean Sea, 2004 (Egypt) | Adriatic IV was declared as sunk and not salvageable, the platform was damaged beyond repair | Gas blowout occurred during drilling operations. An explosion was followed by fire, which then spread to the Petrobel-run platform | More than 150 workers on the jack-up and platform were evacuated with no casualties, due in part to the prior recommendation that production activities be ceased as a precautionary measure |
| Montara Blowout | Timor Sea, 2009 (Australia) | For a period of just over 10 weeks, oil and gas continued to flow into the sea, and patches of sheen or weathered oil could have affected at various times an area as large as 90,000 km2 | During drilling operations at the Montara Wellhead Platform an uncontrolled release of oil and gas occurred from the H1 well. In the operations to complete the “well kill”, fire broke out on the West Atlas rig and the Montara Wellhead Platform | – |
| Macondo Well – Deepwater Horizon Blowout | Gulf of Mexico, 2010 (USA) | 11 life losses. More than 4 million barrels spilled into the Gulf of Mexico, disrupting the entire region's economy, fisheries and critical habitats. The leakage lasted for 87 days with unprecedented environmental consequences | Methane gas from the well, under high pressure, shot all the way up and out of the drill column, expanded onto the platform, and then ignited and exploded. Fire then engulfed the platform, which eventually sank | Recommendations were produced regarding safety, risk and emergency management procedures, including the need to separate leasing from safety oversight regulatory functions |
| Sea Gem Rig Collapse | UK Continental Shelf, 1965 (United Kingdom) | Total property loss and 13 life losses | Two of the rig's ten legs failed, leading the rig to fall sideways. Subsequently, the rig was reported to capsize and sank with one leg remaining above the sea | – |
| Santa Barbara Oil Spill | California coastline, 1969 (USA) | More than 71,400 barrels of crude loss and unprecedented environmental destruction | A first well blew out, spewing oil and gas, which then led to an explosion that cracked the sea floor in 5 places and released 1,000 gallons of oil an hour. A second blow out in a different well followed on two months later | This event is considered to have led to the signing of the National Environmental Policy Act, which required the creation of environmental impact reports on major projects. It is also known for its positive impact on environmental awareness by regular Americans towards offshore drilling and exploitation |
| Ekofisk B Blowout | North Sea, 1977 (Norway) | Estimated production loss between 80,000 to 126,000 barrels, largest blowout in North Sea | Oil well blowout occurred at the Ekofisk Bravo platform, due to an incorrectly installed downhole safety valve. This resulted in the well blowing out with an uncontrolled release of oil and gas. Human errors were the major factor which led to the mechanical failure of the safety valve. These errors included faults in the installation documentation and equipment identification and misjudgements, improper planning and improper well control | – |
| Ixtoc I Blowout | Gulf of Mexico, 1979 (Mexico) | Extensive damage along the US coast with the Texas coast suffering the greatest. Biggest single spill before the occurrence of Macondo accident, with an estimated 3·5 million barrels of oil lost | Well suffered a blowout, with oil and gas flowing to unrestricted surface igniting and engulfing the semi-sub Sedco 135F in flames. Later the rig collapsed and sank onto the wellhead area on the seabed. Oil and gas leakage lasted for 9 months ending in an oil slick of 180 km by 80 km | – |
| Bohai 2 Jack-up | Gulf of Bohai, 1979 (China) | 72 life losses (2 survivors) | Jack-up faced major storm waves and wind loads which overtopped the main deck and broke a ventilator pump free, causing it to fall and puncture the deck, which caused a flood in the pump-room. The rig became unstable and due to harsh weather conditions the jack-up capsized and sank | Improvements were made in regulations and standards related to emergency and evacuation procedures, usage of lifesaving equipment and proper equipment storage at platforms |
| Alexander L. Kielland capsize – floating hotel | North Sea, 1980 (Norway) | 123 life losses (89 survivors); Total asset loss | Failure of supporting leg due to severe gale force winds, but not severe storm. Problems were detected in a weld of an instrument connection on the bracing which contained cracks | Improvement of failure cause analysis and increasing standards for evacuation and rescue operations |
| Piper Alpha explosion | North Sea, 1988 (Scotland) | 167 life losses, including 2 operators of a Fast Rescue Craft (62 survivors) and property damage estimated in € 2 billion | Condensate leak resulting from maintenance work being carried out simultaneously on a pump and related safety valve led to gas ignition and explosion, causing fire and sequential explosions in risers and structural damage with the further release of gas and oil | The Cullen inquiry resulted in more than 100 recommendations that re-shaped offshore safety legislation and practices, namely in chains of command and communication procedures for platform's crew. Necessity of creating fire and blast walls at the platforms. Increased regulations on safety at offshore installations |
| Seacrest Drillship | Platong Gas Field, Gulf of Thailand, 1989 (Thailand) | 91 life losses and total asset loss | Drillship capsized in heavy seas during Typhoon Gay. No distress signals were heard from the Seacrest and none of its lifeboats were found, suggesting that capsize occurred too quickly for the crew to respond | – |
| Adriatic IV Blowout | Mediterranean Sea, 2004 (Egypt) | Adriatic IV was declared as sunk and not salvageable, the platform was damaged beyond repair | Gas blowout occurred during drilling operations. An explosion was followed by fire, which then spread to the Petrobel-run platform | More than 150 workers on the jack-up and platform were evacuated with no casualties, due in part to the prior recommendation that production activities be ceased as a precautionary measure |
| Montara Blowout | Timor Sea, 2009 (Australia) | For a period of just over 10 weeks, oil and gas continued to flow into the sea, and patches of sheen or weathered oil could have affected at various times an area as large as 90,000 km2 | During drilling operations at the Montara Wellhead Platform an uncontrolled release of oil and gas occurred from the H1 well. In the operations to complete the “well kill”, fire broke out on the West Atlas rig and the Montara Wellhead Platform | – |
| Macondo Well – Deepwater Horizon Blowout | Gulf of Mexico, 2010 (USA) | 11 life losses. More than 4 million barrels spilled into the Gulf of Mexico, disrupting the entire region's economy, fisheries and critical habitats. The leakage lasted for 87 days with unprecedented environmental consequences | Methane gas from the well, under high pressure, shot all the way up and out of the drill column, expanded onto the platform, and then ignited and exploded. Fire then engulfed the platform, which eventually sank | Recommendations were produced regarding safety, risk and emergency management procedures, including the need to separate leasing from safety oversight regulatory functions |
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