What happened

Gas and drilling fluid flowed uncontrollably onto the Deepsea Bollsta drill floor after workers cut the casing of Troll well Q-21 during permanent plugging. Equinor estimated that about 930 kg of methane, ethane and propane escaped. One of the 114 people aboard sustained minor injuries. Gas detection triggered the general alarm, emergency shutdown and ignition-source isolation. Havtil classified the event as having major-accident potential and found that the well lacked functioning barriers.

When cited sources give different casualty, damage or spill figures for this event, they’re reported side by side above rather than merged into one number. See how confidence levels work.