Offshore staff
MARSEILLE, France – Bourbon Subsea Services has for the first time decommissioned a catenary anchor leg mooring (CALM) buoy.
Between July 27 and Aug. 12, 2018, various vessel crews working with numerous operators disconnected the buoy from theKuito oil field offshore Angola, then towed it to the Sonamet Yard onshore in Lobito for decommissioning.
AlthoughKuito, which had produced from 2000-2014, had ceased operations, one of the buoy’s six moorings had ruptured.
TheBourbon Evolution 804 was delegated to raise the anchor chains. After the vessel had performed the cut at a water depth of nearly 400 m (1,312 ft), the chains were lifted and underwent further cuts onboard a tug chartered by the client.
The risers had also been cut previously by a diving team contracted by the client.
During the campaign the anchor handler tug supply vesselBourbon Rhesos was connected to the buoy to check its movements and to limit tension on the remaining anchors.
The buoy, fitted with navigation lights, then started its four-day tow to Lobito.
“We had to face several difficulties,” said Bourbon spokesman Philippe Mazurier. “It was an old installation and access to the buoy had deteriorated. Several vessels worked at close quarters around the buoy and there were numerous operators.”
In order to board the buoy, the ladder to which had been damaged and no longer complied with boat landing criteria, the seamen were equipped with harnesses.
However, access was strictly limited due to weather criteria and light conditions. This necessitated careful coordination between the crews to manage the proximity of the vessels at work, including anticipation of vessel movements, the effect of waves and the movements of the buoy, with dedicated radio channels.
The operation also had to be postponed several times as the client wanted to simultaneously position the three vessels which were on long-term contracts.
01/04/2019
