Singapore-headquartered Jadestone Energy has identified no further integrity issues or safety-critical exceptions during the inspection and maintenance work carried out at its Montara oilfield off Western Australia that was shut in last month.

Thai state player PTTEP on 1 November shut in the Montara asset, just one day before Australian regulator the National Offshore Safety & Environmental Management Authority (Nopsema) issued new occupational health and safety improvement notices.

Jadestone said since then the operating team has made “excellent progress” in efficiently and safely completing more than 8000 hours of work offshore. This work included dealing with “a small number of improvement notices issued by Nopsema”, as well as inspections throughout all parts of the facilities.

The company added that all activities associated with the oil system are now fully complete, and the facility is ready to restart oil production, subject to an independent audit currently under way, and regulator support.

Meanwhile, work on the gas system is progressing, independent of the oil system, and is now approximately 85% complete and expected to be finished in the near future.

Also the maintenance management system (MMS), which was identified as inadequate to reliably guide the asset’s on-going maintenance regimen, has had to be partially rebuilt, tested and audited internally for compliance.

“Whilst we were aware, through the due diligence process, of the opportunity to improve operating performance at the Montara asset, and had factored this into our analysis, integrity flaws in the incumbent operator’s MMS made it impossible to identify the full extent of the inspection backlog, and couldn’t provide clear information on inspection status, or the ability to plan future maintenance tasks,” said Jadestone chief executive Paul Blakely.

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“Having opted to shut down the facility and remedy the broad maintenance and inspection backlog, we have also corrected the MMS itself.

“While this work scope has resulted in a protracted shutdown timeline, it was a prudent operational decision and one that will significantly reduce on-going work effort, uncertainty and inefficiency,” he said.

The safety management system has also been reviewed with extensive updates to the assurance plan, and all maintenance routines and inspection records have now been correctly incorporated into the two systems.

Thereafter, all inspection and maintenance work will be complete, with the exception of one activity – the long-planned replacement of the subsea control umbilical – which is now due to be delivered early in 2019 and installed shortly thereafter.

However, Jadestone still expects the field to restart before year-end.

“The asset is now up to date with regards to inspection and major maintenance,” Blakely said.

“The extensive scope of inspection work we have undertaken has confirmed our view that the Montara facility is in excellent condition. After having completed over 800 assurance tasks, we see nothing that changes our view of the exceptional value we have attributed to the Montara asset.”

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He added that while unplanned outages can always happen, the work carried out during this shutdown is expected to “materially improve” uptime performance in the years ahead.

Jadestone completed acquisition of the Montara field from PTTEP in September, however the Thai upstream company still operates the field during a transition period in line with normal regulatory approval processes.

Jadestone has also completed the secondment of a number of key operational leaders, both onshore and offshore, and is now well positioned to advance a seamless transition over the next few months while its safety case and environment plan are under review, prior to acceptance by Nopsema.

The independent added that it anticipates that the Montara facility will now be able to operate reliably and without the need for a planned major maintenance shutdown until at least the second half of 2020.