Singapore-headquartered independent Jadestone Energy has restarted production at its Montara oilfield offshore Australia after output was shut-in following a recent oil leak.

Production was safely reinstated on 3 July following a temporary repair of the leak point in the 2C crude storage tank on Montara’s floating production, storage and offloading vessel and its complete isolation from the production system.

Australia’s offshore regulator, the National Offshore Petroleum Safety & Environmental Management Authority (Nopsema), also reviewed the operator’s inspection and repair records relating to the floater’s crude tanks before the restart.

The oil that was contained within the 2C crude storage tank has now been pumped to other tanks on the Montara Venture FPSO so that there is no threat to the environment, Jadestone confirmed.

A permanent repair of the 2C tank is being advanced, with work expected to start within the next few days.

In tandem, the company will begin to carry out full inspection and remediation on the tank, which was originally planned for July, as part of its rolling tank inspection and repair programme.

The 17 June crude leak left the independent with a repair bill of up to US$3 million and the prospect of a month-long shutdown at Montara, which would take its toll on full-year production.

“The restart of production at Montara is significantly ahead of our initial four-week assumption, and underscores both the integrity of the FPSO following our remediation campaign in recent years as well as our response to Nopsema’s direction to ensure the risk to the environment is as low as reasonably possible,” Jadestone chief executive Paul Blakeley said.

“Our teams, both onshore and offshore, have worked tirelessly to secure the vessel’s integrity and to design and implement detailed solutions which satisfy the regulator, and I thank them for their efforts. I am also grateful to Nopsema for its constructive and balanced approach as we have worked to restore safe operations at Montara.”

The volume of released oil from the Montara FPSO was estimated at between three and five cubic metres, which was monitored and had fully dispersed by the morning of 19 June.

“We will ensure that the lessons learned from this event are incorporated into the future operating strategy for the Montara Venture FPSO, which aims to deliver a prolonged safe operating life for the vessel in years to come,” Blakeley added.

Nopsema had raised concerns in 2021 about historic corrosion issues at the Montara field facilities.

The industry watchdog reported Jadestone had failed to demonstrate that topsides modules’ structure elements were being maintained to ensure that they were fit for purpose, while Nopsema inspectors also found corrosion on piping systems was not being managed to ensure they were fit for purpose.