Rick Wilkinson
OGJ Correspondent
Woodside Petroleum Ltd., Perth, would like to accelerate and increase the breadth of its plans through development of the Scarborough natural gas fields on the Exmouth Plateau offshore Western Australia.
Woodside CEO Peter Coleman outlined the plans in a recent investor briefing that could lead to the $11-billion project (upstream cost) brought on stream in 2023, 2 years earlier than previously suggested. LNG from the expanded Pluto onshore facilities could begin in 2024.
Woodside first bought into Scarborough via BHP Billiton’s stake in September 2016 and then bought ExxonMobil Corp.’s interest in February.
The development concept includes a 20,000-25,000 tonne semisubmersible unit supporting some 20,000-25,000 tonne of topside processing plant in 900 m of water. The unit would be fitted with gas compression and water-handling facilities and could accept future tie-ins.
The semi would be fed by 7 subsea wells, each producing as much as 300 MMcfd of gas. The dewatered gas would be sent to shore via a 430-km pipeline, which would be laid first to the Woodside-operated Pluto offshore platform and then on to the Pluto onshore LNG plant facilities on the Burrup Peninsula through a duplicate trunkline to the existing Pluto pipeline.
Coleman said, along the way from Scarborough, the new pipeline would have capacity to source gas from third-party fields, such as those in the outer Exmouth region, the Equus fields, and the Chevron Corp.-operated Geryon, Orthrus, and Maenad gas fields (OGJ Online, May 18, 2018).
Scarborough field reservoir has a porosity of 30% and a permeability of 1,600 md. The field has estimated 2C resource of 7.3 tcf of gas, comprised of 96% methane and 4% nitrogen and is 50 ppm of carbon dioxide.
Front-end engineering for Scarborough upstream development is expected to begin during first-quarter 2019 with a final investment decision in 2020 leading to a gas flow readiness in 2023.
At the Pluto onshore plant, Woodside plans a second LNG train now sized at 4-5 million tonnes/year capacity to cater for any third-party gas instead of the earlier suggested 2-3.3 million tpy capacity for Scarborough gas alone. The Pluto addition would be of modular design and include a 130 terajoule/day domestic gas facility.
The plans also include construction of an interconnector pipeline on the Burrup between the expanded Pluto and the existing North West Shelf plant facilities. First Scarborough gas would be sent to the NWS facilities via this line until the upgraded Pluto plant can begin LNG production in 2024.
