August, 2013

201315AugAll DayMultiple barrier failures led to a major accidentPSF Learning Brief 005 Origin: PSF Lessons:Asset integrity,Operational IntegrityLanguage:EN


Defence-in-depth through use of multiple barriers to prevent, detect, control and mitigate major accidents are common in high hazard industries. However multiple barrier failure is much more likely where the barriers are connected.

On 20 April 2010 there was an uncontrolled release of oil and gas from a well (a blowout) at an installation working in the Gulf of Mexico. The Deepwater Horizon, a massive floating drilling rig had just finished drilling an ultra deep well while working in water 1500m deep. The well was a further 4000m below the sea floor. The drilling work was considerably behind schedule, but the job was now finished. The crew were relieved and as they were making ready for departure drilling mud accompanied by oil and gas began spewing from the top of the derrick. Alarms sounded and almost immediately there was an explosion. The rig was soon an inferno: 11 people were killed. The well was finally capped 87 days later: this was an environmental disaster on an unprecedented scale..


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