An investigation into a potentially fatal offshore rig incident in Norway in which a worker lost his arm after getting crushed by a heavy drag chain, has now been completed.
The incident occurred on the Linus jack-up rig on November 10, 2022, during repairs to the port drag chain on the jack-up drilling rig, which is operated by Odfjell Technology (Odfjell).
A drag chain is a linked cable/pipe tray carrying power cables and hoses to supply water, drilling mud, and air to the cantilevered drilling rig when the latter is skidded between various well slots.
Measuring 115 centimeters wide, the port drag chain on the Linus jack-up rig comprises two cable trays, one atop the other.
One of its outer plates was damaged (bent), and a two-member team comprising the injured person with an assistant was to look at this and consider what to do, the Norwegian offshore safety body, the Petroleum Safety Authority Norway (PSA) said.
The incident
According to the PSA, the injured person had undone the nuts on a damaged side plate in one of the drag chain links and was lying between the upper and lower drag chain when the upper section collapsed.
"He was standing on the knees and worked between the upper and lower drag chain when the upper section collapsed. Parts of the chain dropped and compressed the IP’s arm and head. After being released, he was taken to the hospital and then flown by SAR helicopter to the SUS. His left arm had to be amputated," the PSA said.
According to the PSA, the weight of the collapsed structure was "considerable," with the load cell on the offshore crane showing about two tonnes when the police came to secure the injury site for their investigation.
The assistant suffered no physical injury during the incident, but, the PSA said, in minimally different circumstances, this incident could have had a fatal outcome for both the injured person and his assistant.
The causes
According to the PSA, the most important direct cause was the collapse of the drag chain over the injured person.
"This occurred after he had undone several nuts on a damaged side plate for workshop repair," the PSA said.
The PSA said that the job was not registered, planned, or risk-assessed per the requirements in the company’s governing systems.
Underlying causes were a lack of control and management of technical condition, lack of job control, deficiencies in governing documents and procedures, and inadequate handover routines and clarification of roles and responsibilities. The incident occurred the day after a swing shift from night to day work. It is unclear whether this might have affected the assessment of risk posed by the repair work, the PSA said.
"The incident occurred the day after a swing shift from night to day work. It is unclear whether this might have affected the assessment of risk posed by the repair work," the PSA Norway said.
Seven nonconformities and one improvement point were identified: registration and classification; procedures and work description for the drag chain; roles and responsibilities; decision basis and safety clearance; compliance with governing documents; noise; information at shift and crew changes.
The PSA has given Odfjell until March 23, 2023, to explain how the nonconformities will be handled and to provide its assessment of the improvement point observed by the investigation.
The port side of drag chain after the chain was raised, moved to one side and laid on the support structure
in order to free the injured person (before safeguarding access to permit investigation of the site).
Source: South-west Norway police district via the PSA Norway
Linus jack-up
The Linus is a jack-up drilling rig owned by SFL and operated by Odfjell Technology (Odfjell) and working for ConocoPhillips Scandinavia AS on the Ekofisk area.
Previously managed by Seadrill, the received an Acknowledgment of Compliance in 2014. Acknowledgement of compliance is issued by the PSA to
offshore drilling rigs so they can work on the Norwegian Continental Shelf. A new AOC for the rig was issued on September 27, 2022 when Odfjell took over.
A 26-inch hole section for surface casing was being drilled in well 1/9-AB-3 H on Tommeliten A for ConocoPhillips when the incident occurred. Located south-west of Ekofisk area, Tommeliten A is a gas/condensate field developed with a six-slot subsea template.
According to the PSA Norway, personnel involved in the incident had long experience of and service on the facility, and had worked together for a long time. The work team doing the repair job had remained with Linus in the transition from Seadrill to operation by Odfjell at the time of the incident.
The drilling operation was halted for 48 hours from the time of the incident.
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