Australia’s National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) has issued a directive that Royal Dutch Shell’s Prelude floating LNG vessel offshore Western Australia remain shut in until the company can demonstrate it has made specified safety improvements.
NOPSEMA issued its four-part directive just prior to Christmas that could keep the vessel offline until at least March 2022.
Prelude’s current troubles began on Dec. 2, 2021, when a small fire in an electrical compartment resulted in a complete loss of power on the vessel. A number of attempts over the following days failed to re-establish reliable power. The facility’s automatic safety systems shut down production systems and began flaring gas which diverted gas supply from the steam-fed turbine generators. Back-up diesel generators failed to start.
NOPSEMA inspectors boarded Prelude Dec. 9-10 and concluded that Shell “did not have sufficient understanding of the risks of the power systems on the facility, including failure mechanisms, interdependencies and recovery.”
The inspectors found that the power failure had knocked out the communication system, access to the vessel’s safety documentation, and evacuation of personnel by helicopter and boat transfer as well as the habitability on board. Essential services like lighting, safety systems, potable water, and sewage treatment were affected.
Although Shell has begun an investigation to determine the cause of the original power system failures, NOPSEMA said the investigation did not go far enough into a root cause analysis of the entire series of events nor did it provide for a review of the risks for future similar incidents and actions to mitigate them.
Consequently, NOPSEMA has directed (1) that Shell widen its investigation to cover these issues, then (2) develop a detailed plan, schedule and commitment to timely implementation of all the necessary corrective actions and present this completed plan to NOPSEMA.
The authority has also directed (3) that prior to hydrocarbon production re-starting, Shell must demonstrate to NOPSEMA’s satisfaction that Prelude can safely recover essential power and associated services following a loss of power and that the safety systems and essential support systems operate to maintain safety of personnel.
NOPSEMA’s fourth directive is that the first business day of each month beginning in March 2022, Shell must provide the authority with an update detailing progress under directions 1 and 2 until NOPSEMA is satisfied under direction 3.
Prelude had previously been shut down for 11 months in 2020 due to electrical problems.
The 488 m-long, 74 m-wide, 3.6 million tonne/year LNG vessel is moored in Browse basin production permit WA-44-L about 475 km from Broome on the Western Australian coast.