Diver exposed to unplanned release of production gas

Description of Incident

During saturation diving activities at 65m water depth, from a Diving Support Vessel (DSV), a diver was exposed to a sudden and unplanned release of hydrocarbon gas under pressure (estimated pressure >150bar). The pressure release resulted in ejection of a stuck blind stab and the diver being pushed backwards by the force of the gas. The diver was unharmed. Our member considered the incident to be a very high potential near miss.

Nearing the end of the bell run, saturation divers were working on a subsea skid when they identified incorrect tagging. Work was stopped and the divers were then instructed by the Diving Supervisor to proceed with a dummy stab removal at the same location, using hand tools (T-Bar and hammer). During initial hammering of the dummy stab, a discharge of gas bubbles was observed coming from the receptacle, followed by a larger one. At this time, both divers were instructed to stop working for ten minutes to allow for the gas to discharge. Diver 1 was instructed to return to the bell and Diver 2 was subsequently instructed to restart tapping the blind stab with the hammer. Suddenly the dummy stab ejected and trapped production gas was released. Diver 2 was positioned just outside the line of fire, but he was pushed backwards by the force of the gas release, though he remained on the top of the skid.

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