Prelude Overview
Prelude is an operational floating liquefied natural gas (FLNG) facility, located offshore, north-north east of Broome in Western Australia.
Find out more about Prelude by watching the video, or scroll down to learn more.
What is Prelude?
The Prelude FLNG facility is 488m long and 74m wide. It has been designed to remain moored in the field for at least 25 years. Prelude FLNG is designed to extract, liquefy and store natural gas at sea, before it is transferred and shipped to customers.
The technical components of Prelude’s subsea infrastructure
Anchor chains
The Prelude FLNG facility is connected to a series of anchor chains which secure the facility to the seafloor.
Flexible risers and flowlines
There are four, 12-inch flexible risers below the Prelude facility. LNG Products are transferred to Prelude by four 12-inch flowlines.
Subsea system hardware
The subsea system is made up of hardware that includes wellheads, subsea Christmas trees, production manifolds and a riser-based manifold.
Umbilical
The steel tube umbilical provides power and hydraulics to control the subsea system hardware.
What happens at Prelude?
LNG is made by taking water and other impurities out of the gas and cooling it to minus 165 Celsius. Condensate is also produced during the process, which is a light hydrocarbon, somewhat like diesel.
After processing, the gas is transferred onto carrier vessels and transported to customers throughout the world.
Prelude is supported by three infield support vessels, which provide security surveillance, emergency standby and product transfer support. Other multi-purpose supply vessels provide additional transport and logistical support, out of Darwin.
The offshore infrastructure is supported by onshore servicing. The helicopters which transfer personnel to and from Prelude are refuelled at the Djarindjin Airport, which is Aboriginal owned and employs local people.
Prelude has an onshore supply base located in Darwin, Northern Territory, which houses equipment and spare parts.
Shutdowns for maintenance are expected to be needed every four years. Underwater equipment is designed to require minimal maintenance and is inspected regularly.
Where is Prelude?
Prelude is located approximately 475km north-east of Broome, Western Australia, in the Browse Basin.
Prelude’s safety zone extends in a 1.5km radius around the facility.
What is an Environment Plan?
An Environment Plan, or EP, outlines all the environmental impacts and risks of an activity and how these are managed to minimise risks to the environment. It is required by the National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) for approval (acceptance), prior to starting an offshore oil and gas activity. NOPSEMA requires all EPs extending longer than five years to be revised.
Shell plans to submit a five-yearly revision of the Prelude EP to NOPSEMA in 2025.
