Photo: John Brookes platform; Source: Santos

Offshore platform shut in following gas leak

After finding a gas leak, Australia’s energy giant Santos has temporarily shut down a platform and a subsea pipeline offshore Western Australia.

Santos reported on Tuesday that “a small gas leak” has been identified in a subsea flange on the main gas trunkline from the John Brookes platform, offshore Western Australia to the Varanus Island gas processing facilities.

Following the observation of the leak during routine activities on the normally un-staffed facility, the Australian player highlighted that the platform and pipeline were “immediately shut down and depressurised and all personnel demobilised.” The firm also confirmed that it has notified “all relevant regulatory bodies.”

As it is currently expected that repairs will take approximately four to six weeks to return to full production, Santos is working with customers and other parties to manage gas supply arrangements while the leak is repaired.

“Varanus Island will continue producing at reduced rates and no changes to Santos’ previously communicated production market guidance is anticipated,” underscored the Australian giant.

Santos is the operator of the John Brookes and Greater East Spar gas fields located in offshore Commonwealth waters on the North West Shelf of Western Australia. The gas and condensate from these fields are transported by subsea pipelines – the John Brookes Pipeline and East Spare Pipeline –  to the Santos-operated Varanus Island (VI) oil and gas processing hub.

Afterwards, the gas is transported to mainland WA via two 100-kilometre pipelines to be supplied to mining and industrial customers while oil and condensate are stored on the island and transferred to tankers for direct export.

The John Brookes wellhead platform is located in approximately 45 metres of water. The production started in 2005, and the field’s facilities consist of the John Brookes WHP, a normally unmanned wellhead platform designed to accommodate a maximum of six production wells; the John Brookes pipeline, a 55-km-long, routed to the VI onshore processing facilities; and John Brookes wells, four producing wells at the John Brookes WHP.

In addition, the John Brookes facility provides infrastructure for the control of the Halyard and Spar-2 subsea wellheads. However, production from the Halyard and Spar wells is independent of the John Brookes facility, as Halyard well fluids are exported to VI via the 65 km long East Spar pipeline.

Varanus Island operators provide 24/7 control of the WHP via telemetry and a distributed control system from a central control building on VI. Moreover, WHP visits are required for inspection, maintenance, monitoring and repair (IMMR) activities.

To this end, crews travel via helicopter or support vessel to the WHP to carry out inspection, maintenance, monitoring and repair; to replenish fuel or chemicals; and to carry out operational requirements, such as a restart after a trip.

Regarding Santos’ recent activities, it is worth noting that the Australian firm suspended drilling activities at its Barossa offshore gas project, pending a favourable appeal outcome or the approval of a new environment plan.

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This happened after the Federal Court in Australia ruled against the energy giant and in favour of an indigenous group that launched a legal challenge in June 2022, claiming they had not been adequately consulted about the project, the pipeline of which will run through the Tiwi sea country.