Detecting leaks and oil pollution at not normally attended facilities

Environment alert ι Published: November 2018

What happened?

NOPSEMA was notified of a hydrocarbon release incident at a not normally attended production facility located off the coast of Western Australia.

Personnel arriving on the facility inadvertently discovered a hydrocarbon leak when conducting maintenance on the corrosion inhibition system.

The source of the leak was identified to be a fracture (fatigue crack) in the discharge line of a coriolis mass flow meter. The well was immediately shut-in and the facility’s emergency shutdown procedures were implemented.

NOPSEMA immediately commenced an investigation into the incident and deployed inspectors to the titleholders incident control centre. Following the deployment of inspectors. NOPSEMA issued a Direction (708) to the titleholder that production not be restarted at the facility until specific actions had been undertaken and supporting evidence of such was provided to NOPSEMA.

The Direction required the titleholder to:

  • isolate damaged equipment on the facility identified as responsible for the hydrocarbon leak

  • implement an immediate inspection activity (e.g. non-destructive testing programme and service testing) to confirm the asset integrity of similar equipment and their interconnecting  pipework

  • restore secondary containment equipment to be able to retain its full capacity

  • develop and implement effective controls to detect loss of containment and any subsequent loss of hydrocarbon to the environment.

NOPSEMA also deployed inspectors to the offshore facility to assess and inspect the operator’s control, systems and processes for preventing loss of containment events. NOPSEMA issued a series of recommendations for future improvement. These included:

  • Asset integrity management – NOPSEMA’s inspectors noted that the operator’s facility inspections had failed to identify defects. For example, NOPSEMA’s inspectors found corroded ‘fixed’ and ‘spring’ type supports for hydrocarbon equipment, galvanic corrosion ingress on critical flange and valve interfaces, pipes unrestrained to designated fixed civil structures.

  • Operating envelope – NOPSEMA’s inspectors noted that during the duration of the leak, a drop in pressure trend was sighted on the distributed control system. This drop in pressure did not alert the control room operator to further investigate for potential issues related with a gradual drop in pressure which could be an indicator of a ‘leak event’.

  • Closed-circuit television (CCTV) - Cameras are installed on the mezzanine, cellar and sub-cellar decks of the offshore facility as well as the onshore processing plant. Due to design constraints and software limitations, the DCS operator can view a maximum of two CCTV cameras at any given time on a single screen. The two CCTV viewed at the time of the incident were not of the offshore production facility, but were of the onshore processing plant.

  • Gas detection systems – The offshore facility is installed with a number of gas detection devices for the purpose of detecting a hydrocarbon leak. During the ‘leak event’ which has been estimated to have occurred over an approximate seven hour duration, none of the flammable gas detectors were activated. This was largely due to the makeup of the production fluid (low percentage oil cut and little to no gas).

What could go wrong?

Control measures to ensure asset integrity and detect leak events that are ineffective could result in oil leaks extending for prolonged periods, in particular for not normally attended offshore facilities. Hydrocarbons released to the environment could cause environmental damage and contribute to pollution effects that may impact marine life.

Failure to detect a hydrocarbon leak for prolonged duration may result in significant costs to titleholders including prolonged shutdown of a facility and associated clean-up costs. Failure to prevent hydrocarbon leak events may also lead to NOPSEMA taking enforcement action.

Key lessons

Titleholders should ensure where controls are in place to detect leaks they are effective and fit for purpose. For example:

  • CCTV monitoring systems should ensure sufficient resolution and coverage of the facility to allow onshore operators to adequately detect leaks. Onshore CCTV systems should also allow control room operators to view all cameras at all times. Alternatively there should be systems in place to ensure operators regularly cycle through all cameras to prevent areas of the facility going unmonitored for long periods of time.

  • Distributed control system alarm set points should allow operators to identify potential leaks and processes should be in place to ensure control room operators adequately investigate operating envelope deviations.

  • Titleholders should ensure that systems for maintaining records such as CCTV footage are adequately understood and fit for purpose. Titleholders should ensure footage is backed up as a priority post incident to ensure that critical records are maintained.

The legislation

Section 569(1) of the Offshore Petroleum and Greenhouse Gas Storage Act 2006 states that the registered holder of a petroleum exploration permit, petroleum retention lease or petroleum production licence must:
(c) control the flow, and prevent the waste or escape, in the permit area, lease area or licence area, of petroleum or water.

Regulation 7 states that a titleholder must not undertake an activity in a way that is contrary to:
 (a)  the environment plan in force for the activity.

Regulation 27 states that a titleholder commits an offence if the titleholder:
(a)  creates a document or other record mentioned in subregulation (6); and
(b)  does not store the document or record in a way that makes retrieval of the document or record reasonably practicable.

Regulation 28 states that a titleholder must make available, in accordance with this regulation, copies of the records mentioned in regulation 27, and the titleholder must make copies of the records available to any of the following persons, on request in writing by the person:
(a)  the Regulator.


Enforcement policy (PDF 234KB)

Environment plan content requirements (PDF 953KB)


Enquiries should be directed to and quote ‘Environment Alert 4'.