Ichthys LNG Project mooring system pre-lay completed

Posted 11 May 2016

The INPEX-operated Ichthys LNG Project reached a significant milestone with completion of the offshore pre-lay of the 77 kilometre chain and cable mooring system in the Browse Basin, located off the northern coast of Western Australia.

As part of the mooring system, 49 chains were laid on the seabed in water depths of up to 250 metres and anchored to foundation piles—5.5 metres in diameter and 63 metres long. 

The mooring system will secure the Project’s two massive offshore facilities—the Central Processing Facility (CPF) and Floating Production, Storage and Offloading (FPSO) facility—in the Ichthys Field seabed for at least 40 years of continuous 

Once located in the Field, the CPF will deliver natural gas and some condensate through an 890 kilometre subsea gas export pipeline to onshore processing facilities in the Northern Territory. Most condensate will be processed through the FPSO and shipped directly to market from the Field.

Supplying more than 40,000 tonnes of large-scale anchor chains for the Project represented nearly 18 months of worldwide chain production. Each chain link weighs more than 700 kilograms.

The 28 CPF mooring chains required more than 25,000 tonnes of mainly 178 millimetre diameter chain, while the 21 FPSO mooring chains needed more than 15,000 tonnes of mainly 161 millimetre diameter chain.

The mooring system is part of the complex network of subsea infrastructure and equipment across the Ichthys Field.

Ichthys Project Managing Director Louis Bon said the mooring system pre-lay was a significant undertaking with challenging soil conditions for the piling scope of work.

“Despite the difficulty of the task, I’m proud to say that it was successfully completed without a single Lost Time Injury or any harm to the environment,” Mr Bon said. 

“For example, because the Ichthys Field is located just 120 kilometres from the main hump back whale migratory routes and calving grounds of North West Australia, an early decision was made to avoid pile driving during the whale calving period where associated underwater noise may have created a disturbance.”

Mr Bon said the successful completion of the mooring chains pre-lay marked another major step ahead of the arrival of the CPF and FPSO currently under construction in ship yards in South Korea and, once completed, will be towed 5600 kilometres to the Ichthys Field.

"The offshore facilities will operate for decades and the mooring system plays a key role in ensuring their integrity.”

In addition to the mooring system, more than 16,000 tonnes of subsea structures and 140 kilometres of rigid flowlines have been installed across the Ichthys Field to safely and efficiently extract gas and condensate.


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