Oil and Gas News

NOPSEMA hands Stag authority over to AMSA

The national petroleum regulator has given Jadestone Energy the green light to progress with a new operating model for the Stag facility offshore Western Australia.

The National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) has approved the facility as a new operational and commercial development.

The historical operations at the Stag field have seen the inclusion of a floating, storage, and offtake (FSO) vessel, which has been moored in field and receives production oil from the central production facility (CPF), and then off take to the cargo to a third-party tanker.

Recent operational and commercial developments have seen a shift to an operating model that requires only a third-party tanker and thereby permanent relinquishment of the FSO field.

As a result, the Stag field environment plan was revised, with the changes including: description of the third-party tanker; inclusion of waste incineration; and further information provided on the risk management associated with marine pest introduction.

The changes also listed are the reduction in the spill volume in the scenario of a vessel collision resulting in release of crude oil to sea; and minor changes including updates to priority receptors, volumes ashore and resourcing of response strategies to reflect revised modelling for the worst‐case credible spill scenario.

In addition, in March 2019 a memorandum of understanding was established between NOPSEMA and the Australian Maritime Safety Authority (AMSA) to guide cooperation and mutual assistance in relation to their respective statutory functions for safety and environmental management in the offshore petroleum sector.

Following the approval of the additional Stag facility work, AMSA is now the recognised statutory authority.

The Stag field production and export facility is located in permit WA-15-L, located in 49m water depth, and produces oil forms he Stag reservoir.

“Oil is loaded continuously to the third‐party tanker at a production rate of up to 4,000 barrels a day. The CPF has been in production since 1998 with only minor modifications carried out during this time,” Jadestone outlined in its environment plan.

Stag oil is a medium crude with a very low proportion of volatile compounds due to microbial degradation within the reservoir.

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