Shell’s Prelude floating liquefied natural gas facility offshore Western Australia was at risk of suffering a “catastrophic failure” following last month’s power issues, according to local media.

Australian news outlet WAtoday claimed this week to have obtained a copy of the full investigation report by Australia's offshore safety regulator into last month's fire and subsequent power failures on board the giant offshore facility.

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The report from the National Offshore Petroleum Safety & Environmental Management Authority (Nopsema) reportedly stated the steel spine of the vessel was potentially at risk of failing to support the more than 80,000 tonnes of topsides equipment on the FLNG vessel.

According to the report, a water filled cavity lies along the centre of the vessel, between the tanks that store LNG at minus 162 degrees Celsius, however, without power to heat the cavity, there is a risk the temperature of the steel could fall to dangerously low levels and weaken it.

According to WAtoday, Nopsema’s inspectors found that the unreliable power following the fire produced “significantly higher than normal” risks, noting that “cooling of the substructure in the vicinity of the LNG tanks could lead to catastrophic failure if unmitigated”.

However, Upstream understands the report also stated that Nopsema inspectors found that the operator had “appropriately managed” immediate risks to Prelude through established processes following the incident.

It is also understood that inspectors cited process safety risk controls had been implemented on Prelude, including the reinstatement of glycol heating to cargo spaces to mitigate subcooling of the substructure.

Union group's take aim at regulator

However, Nopsema’s findings have angered union groups, with the Offshore Alliance — a coalition between the Australian Workers’ Union and the Maritime Union of Australia —calling out the claim that Shell had appropriately managed the immediate risk to workers onboard Prelude.

“Shell went through similar issues in 2020 and learnt nothing from their previous mistakes,” the union group said.

“Shell didn't even have back-up emergency power for the Prelude hospital - this is not properly "managing the immediate risks".

“Neither [are]... the associated risks of having a lack of sanitation and HVAC (heating, ventilation and air conditioning). Or having workers work 30 hour shifts to deal with the emergency.”

The Offshore Alliance also hit out at Nopsema's decision to not prosecute Shell, at this time, with the union group claiming Shell’s senior management needs to be “held to account” over the incident.

Following the release of the Nopsema report, a Shell spokesperson confirmed: “Production on Prelude has been suspended temporarily, and an investigation into the root cause of the incident is underway.

“We will continue to work methodically through the stages in the process to prepare for hydrocarbon restart with safety and stability foremost in mind.”

Upstream understands that mainspower has since been restored on Prelude and that Shell is still working through its own internal investigation into the incident.