In the Exmouth sub-basin, offshore Northwest Australia, Apache Energy ltd. is developing the Van Gogh oilfield. In the future, an FPSO will be used for production and storage of the oil. The FPSO will be moored to a dis-connectable turret-mooring (DTM) buoy. Flexible flowlines, which connect to two subsea manifolds, will be attached to this same buoy.
The offshore installation contractor for the Van Gogh project, Acergy Australia pty ltd., asked Jumbo to take care of the transportation of the DTM buoy from Singapore to the Exmouth gulf, delivering subsea equipment to the subsea installation vessel mv Toisa Proteus, and demobilizing equipment. Beside an extensive engineering procedure, additional brainwork was required in the preparation phase of the project. Lifting the DTM buoy was only possible from the top, using a single point connection. A special lifting device to suspend the ball tool, was designed in-house and manufactured under supervision of Jumbo in Singapore. A special grillage was designed to support and sea-fasten the buoy.
Halfway October 2008, Jumbo's mv Fairlane arrived in Singapore to load the 500 tons DTM buoy. A barge carrying the buoy was maneuvered alongside. The ball tool male connector was lowered into the female receptacle on top of the buoy and the connection fixed. The Fairlanes' two 400 tons mast cranes then slowly lifted the buoy on deck, using almost all the available lifting height. After the buoy was thoroughly sea fastened, mv Fairlane sailed to the Exmouth Gulf and met the Toisa Proteus and two anchor handling tugs (AHT's) at the end of October.
After the final joint preparations, the ball connector was again lowered into the top of the DTM buoy, while one AHT was already connected with a long polyester line. The Fairlane very gently discharged the buoy into the water, while it was automatically ballasted. The other AHT was also connected to the buoy, and when the stability and draft of the buoy were correct, the ball connector was disengaged. The buoy could be towed to its final destination offshore.
Subsequently, the Fairlane sailed to the port of Henderson, near Perth and loaded two subsea manifolds of respectively 160 and 180 tons, four riser bases of 100 tons, and some smaller items. After returning to the Exmouth gulf, the Fairlane lifted the subsea equipment onto the main deck of the Toisa Proteus. Jumbo's heavy lift vessel completed the challenging project by demobilizing equipment to Singapore on the 3rd of December. First oil from the Van Gogh field is expected march 2009.
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