The incident on West Venture occurred immediately before midnight on 23 March 2015 while it was operating on the Troll field.
A test plug belonging to a test tool for the blowout preventer (BOP) fell to the drill floor and continued through a spider work platform and the rotary table opening. It was halted after falling eight metres and hit the top of the BOP before coming to rest between the kill-line hub and the BOP frame.
The test plug weighed 90 kilograms, and its kinetic energy just before impact was estimated at 5 297 Joules. Two people were standing on the other side of the BOP frame when the incident occurred.
The PSA’s investigation has identified nonconformities from the regulations related to:
- preparations for lowering the test tool through the rotary table/spider
- planning and leadership, and compliance with the management system for mechanical handling operations.
Actual consequences
The incident caused minor material damage to the BOP flange and the test plug. No other damage was caused to material assets or injury to personnel.
Potential consequences
Under slightly different circumstances, the dropped test plug could have caused injury to personnel. The plug had an equal likelihood of falling on the side where people were present. Its kinetic energy just before impact was sufficient to cause serious personal injury or death from a direct hit. The position of the personnel in this case meant they could not have suffered a direct hit, but the plug might have hit the BOP in such a way that it changed direction and thereby struck one of the people beneath the drill floor.
West Venture is operated by North Atlantic Drilling (NAD). The PSA has now asked NAD to describe how it intends to deal with these nonconformities.