Extension cord fault likely cause of offshore Norway drilling rig fire

The Norwegian Petroleum Safety Authority has issued its findings concerning a fire on Seadrill’s semisubmersible drilling rig West Phoenix.

Offshore staff

OSLO, Norway – The Norwegian Petroleum Safety Authority (PSA) has issued its findings concerning a fire on Seadrill’s semisubmersible drilling rig West Phoenix.

This occurred in the rig’s mud laboratory on Nov. 5, 2018. At the time the rig was drilling well 6406/2-9 S in the Norwegian Sea for operator Equinor: 117 personnel were onboard.

The incident was connected to testing of drilling fluid in a retort, an electrical apparatus used to measure and monitor the quantities of water, oil, and solids. During drilling operations, the retort is used several times a day.

On this occasion the retort was in use when the fire started. No one was in the lab at the time, but the smoke alarm was activated and the presence of flames in the room was reported.

Following activation of an alarm, a fire team arrived, extinguishing the fire shortly afterwards. The incident caused drilling to be halted for five days.

According to the PSA’s investigation, the mud lab was not considered to be an area at high risk of a fire, with the wall meeting fire class A0 requirements. But if the fire had not been quickly extinguished, it would likely have spread because flammable materials were stored and used in the room.

This could have caused a much longer suspension of drilling and substantially greater material damage, with the smoke potentially spreading to large areas.

The fire is said to have started in the fume cabinet where the retort was located, and analysis suggests the cause was probably serial arcing in the extension cord. This arcing developed a high temperature, igniting flammable material in the vicinity.

Chemicals for mud testing were also stored in the fume cabinet, which was clad internally with flammable sheets, and both these factors contributed to the fire’s rapid escalation.

The PSA has identified various nonconformities and improvement points and has asked Seadrill to respond by March 29.

03/05/2019

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