The leak occurred in the process module on the Gjøa semisubmersible platform and led to gas detection, a general alarm, automatic shutdown of the process plant, pressure blowdown, and mustering in accordance with the alarm instructions.
Gjøa, which came onstream in 2010, has been developed with four subsea templates and a satellite well tied back to the platform.
Engie estimated the leakage rate at 1.06 kg/s and the total quantity at around 1.25 cu m (44 cu ft). Analysis showed that the fluid consisted largely of produced water with small quantities of hydrocarbons (gas and condensate).
The condensate did not ignite during the incident, and the leak was stopped after about 30 minutes.
According to the PSA, the cause was a fatigue fracture in a weld on a ½-in. pipe nozzle on a condensate pump connected to the gas recompression system.
An emergency shutdown valve (ESV) upstream from the leak site failed to close.
The emergency response command on the facility decided to evacuate staff to the shore, however, the all-clear was given on Gjøa soon afterwards.
Engie’s maintenance of the ESVs and associated actuators was inadequate, the investigation found: these problems had been known over a long period, but not dealt with, the PSA pointed out.
The main non-conformities with regulations related to the:
- Barrier management system
- Management and maintenance system
- Response to vibration
- Organization and management.
In addition, the PSA identified the need for improvement point concerning carcinogenic and mutagenic chemicals.
It has ordered Engie to take steps to ensure that safety-critical equipment is operated, tested and maintained in a way which ensures the performance of the barriers at all times. Deadline for compliance is Feb. 2.