McDermott International delivered its 7,200-ton riser support structure (RSS) tower for the Ichthys project in the Browse basin, about 124mi off Western Australia.
Engineered in Singapore and fabricated on Batam Island, Indonesia, the RSS tower is more than 328ft tall. McDermott said that its 425ft-long arch, to be installed at a future date, will support 25 flexible risers and dynamic umbilicals. Operator Inpex said it was the largest-ever subsea structure laid on the seafloor.
“The RSS accounts for more than 25% of the total 28,700-ton of subsea structures we are fabricating for Ichthys,” Tony Duncan, executive vice president subsea, said in a statement. “It is an integral piece of the subsea field architecture as all other subsea structures will be installed and oriented relative to its location.”
Installation for the tower began in mid-October, and was completed last week with the deepwater construction vessel Aegir, a newbuild by Heerema Marine Contractors.
McDermott was appointed the main contractor for the Ichthys project’s subsea umbilicals, risers and flowlines (SURF) engineering, procurement, construction and installation. It is also responsible for the project’s engineering, procurement, construction, installation and pre-commissioning of production flowline systems. Inpex was awarded this approximate US$2 billion contract by Japan’s Inpex on 25 January 2012, days after Inpex and joint venture partner Total confirmed the final investment decision on the $34 billion project on 13 January 2012.
On 17 September 2014, Neptune Marine Services Ltd. announced that it had been awarded two subcontracts by McDermott, the second of which which included grouting the RSS.
The Ichthys project is scheduled to come onstream by the end of 2016, and is expected to produce 8.4mtpa LNG and 1.6mpta LPG, along with more than 100,000 bbls of condensate daily at peak levels. Most condensate will be directly shipped to global markets from a FPSO permanently-moored in the field, which is due to arrive at the field in 2015.
The project celebrated its halfway mark on 25 June; then, on 6 July, the Ichthys hull was launched from the dry dock of the Daewoo Shipbuilding and Marine Engineering yard in Okpo, South Korea. According to Inpex’s project timeline, the next step for the offshore portion of the project would be the start of developmental well drilling.
Inpex operates the Ichthys project with 66.7% interest with partners Total (30%), Tokyo Gas (1.575%), Osaka Gas (1.2%), Chubu Electric Power (0.35%), and Toho Gas (0.42%).
Image of RSS tower from McDermott International.