Mariners have been warned of equipment floating west of Barrow Island at ENI’s Woollybutt oil field months after ENI was told its poor maintenance posed a risk to vessels.
The Australian Maritime Safety Authority issued an alert shortly before 1 PM WA time Monday of a “20m wellhead frame semi-submerged, possibly adrift” at a latitude and longitude very close to the Woollybutt location.
A member of the public sighted the object from a vessel and reported it to the Authority, an AMSA spokesperson said.
Boiling Cold understands the object is a mid-depth buoy that should be chained to the seabed and float well below the surface.
The Woollybutt oil development consisted of a production vessel that rotated around a single point mooring buoy tethered to the seabed with chains. Oil lines and umbilicals rose from the seabed and draped over buoys position between the seabed and sea surface before going to the SPBM. The two mid-depth buoys were themselves attached to the seabed with chains.
Woollybutt ceased production in 2012, and the vessel left a few weeks later.
Little has happened since.
Offshore safety regulator NOPSEMA in July 2019 approved an ENI plan to plug and abandon the wells and monitor the equipment that had been unused for eight years.
Six months later, in January 2020, ENI reported that the single point mooring buoy had sunk to the seabed.
NOPSEMA concluded that ENI failed to maintain so-called cathodic protection to stop the buoy from corroding. Cathodic protection typically involves attaching an easily corroded material that corrodes instead of the structure to be protected.
NOPSEMA told ENI to inspect the chains that secured two MDB’s to the surface as the Italian firm was not properly conducting proper inspection and maintenance.
“In the event of a mooring system failure resulting in an MDB floating to the surface, this would create a marine vessel collision hazard leading to vessel damage or sinking and could result in injuries to, or loss of life of, vessel personnel,” the NOPSEMA notice stated.
The floating object remains within the Petroleum Safety Zone surrounding Woollybutt and is being monitored by a vessel, according to ENI.
“There was no release of hydrocarbons as the equipment was properly cleaned during FPSO departure,” the ENI spokesperson said.
“Planning is in place to abandon and decommission the subsurface equipment by 2021.”
Boiling Cold has asked ENI whether it plans to leave the equipment in place or remove it. The remaining equipment includes as a minimum: wellheads, umbilicals, chains, gravity-based structures, two mid-depth buoys and the sunken single point mooring buoy.
Woodside has proposed that all equipment be left on the seabed when it abandons the North West Shelf Project’s Echo Yodel field.
NOPSEMA said it had not yet confirmed whether the object was free to float away or still tethered to the seabed.
Boiling Cold asked NOPSEMA if, given this mooring failure, it would require ENI to remove the two mid-depth buoys before the cyclone season.
“It’s premature at this point to be issuing any further Notices or Directions prior to confirming various details that will need to be clarified by Eni in the coming days, and up to 30 days in the final report issued to NOPSEMA,” a spokesperson for the regulator said.
ENI’s delayed work on Woollybutt is a tiny part of the estimated $76 billion to be spent cleaning up Australia’s oil and gas fields over the next 30 years.
ENI is seeking to sell all its Australian assets, that include interests in the Darwin LNG plant, Bayu-Undan project, and the Blacktip gas field off the Northern Territory coast.
Correction: September 1 2:20 PM: Original story incorrectly said Woollybutt was east of Barrow Island.
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