In this blog, we will explore four of the worst disasters in the history of offshore drilling. We will look at what went wrong, from a simple communication error on Piper Alpha to a flawed design in the Alexander L. Keilland.
We’ll also cover the sinking of the “unsinkable” Ocean Ranger and the massive environmental damage from the Deepwater Horizon spill. By understanding these past tragedies, we can learn how to make this crucial work safer for everyone in the future. Let’s begin.
 1. Piper Alpha
On July 6, 1988, an explosion on the rig caused the deaths of over 160 workers. A case study completed by NASA determined it to be caused by a communication error facilitated by shift change. During the day shift, a worker began routine maintenance on the pressure safety valve responsible for regulating pressure on condensate Pump A. The worker determined they could not finish maintenance in the time remaining on the shift and installed a temporary, hand-tightened valve. Though the worker filled out the appropriate permit to communicate that the pump was not in safe operating order, the permit was placed near the valve, per policy, but not in the permit binder.
Later that evening, condensate pump B malfunctioned. When workers pulled the permit binder, they did not find the permit stating Pump A was not functional. Believing it was safe, the workers activated Pump A, which failed almost immediately. An explosion soon followed, causing an evacuation of the control room.
Management’s procedure dictated the automatic fire suppression system should be deactivated when divers were near the water intakes.
No order was given to stop drilling, so the fire was constantly fueled. Workers began to jump from the rig within an hour of the initial explosion. Helicopters attempted rescue but could not reach the scene due to wind conditions and the smoke from the fire, resulting in the death of 165 workers and two rescue team members.
2. Alexander L. Keilland Disaster
On March 27, 1980, there were over 212 workers in the housing facilities attached to the Norwegian semi-submersible drilling rig in the North Sea. The Alexander L. Keilland disaster was responsible for the death of 123 workers. While Piper Alpha is seen as the most devastating loss of life for the United States, Alexander L. Keilland is that for Norway. Final counts confirmed only 89 survivors from the 212-man crew.
The weather on the day of the incident was dangerous, with heavy rains and waves reaching nearly 40 feet high. Just before 7 pm, five of the cables tethering the platform to the ocean floor snapped. This shift caused one of the support legs to give out and the ultimate capsizing of the rig. A National Oceanic and Atmospheric Administration (NOAA) report states three of the four rescue boats were damaged. This was partially due to a failure of the release hooks.
The cause of the disaster was ultimately inadequate structural support and poor integrity of the beams. Ultimately, the design of the rig was flawed owing to the absence of structural redundancy.
3. Ocean Ranger
The Ocean Ranger offshore oil rig was seen as the most advanced rig of the time. On Valentine’s Day of 1982, that would no longer be the case. According to a system failure case study by NASA, the rig was battered by bad weather. The crew was unconcerned due to the rig’s impressive history of withstanding storms. Just before 8 pm that evening, a wave hit the control room, shattering the windows. The crew was able to disconnect the power to the control panel to prevent electrical issues from the salt water. For reasons still unknown, the crew prematurely re-established power to the control room, causing the ballast tanks to flood and the rig to tilt. Of the 84 men onboard, there were no survivors and only 22 of the deceased could be recovered.
The NASA report ultimately cites a lack of knowledge and training on behalf of the crew as the reason for this tragedy.
Training to operate the control room was inadequate, consisting of two weeks of shadowing day-to-day operations with no instructional time in the classroom. Investigators also feel the crew as a whole had an incomplete understanding of how the rig functioned and how the ballast tanks could be affected by the restoration of power.
4. Deepwater Horizon Oil Spill
On April 20, 2010, there was an explosion on the Deepwater Horizon drilling rig, causing it to sink and allow oil to flow into the Gulf of Mexico. The Environmental Protection Agency(EPA) reports the well was open and leaking for 87 days before it was capped. In a statement from BP (formerly British Petroleum) on the causes of the Gulf of Mexico tragedy, several causes for the accident were cited:
- The slurry used was not adequate to control the hydrocarbons and allowed liquid and gas to flow back up.
- Workers inaccurately reported – or B.P. inaccurately accepted – the negative pressure test results.
- The crew failed to notice and act on the influx of hydrocarbons.
- The crew mistakenly diverted the gas flow to the engine rooms instead of off of the rig.
- The rig did not prevent the flow of gas into the engine room, which only increased the risk of an explosion.
- After the explosion, the failsafe to seal the well failed. This was likely because of damage done in the initial explosion.
