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 Chief Executive Officer Peter Coleman outlined the plans in an investor briefing this week 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.
Scarborough development
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 16, 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.
Pluto onshore plant
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.
Coleman said he was open to talking to other resource owners who could hook into Woodside’s pipelines and LNG plants.
Browse basin plans
Looking ahead, Coleman said the company’s concept to develop Browse basin gas also was planned to fit this overall scenario. Browse would have two floating production, storage, and offloading facilities connected to the North Rankin complex in the Carnarvon basin via a 900-km pipeline. Gas would be processed through the NWS Project facilities.
The Browse fields have an estimated resource of 13.9 tcf of gas and 390 million bbl of condensate.
Woodside would like to see concept definition completed by this year’s third quarter with a front-end engineering and development phase to begin in fourth-quarter 2019 and a final investment decision in 2021.
That would lead to Calliance and Brecknock fields being brought on stream in 2026 and Torosa in 2027.
Coleman pointed out that Woodside was in a commanding position in this sector of offshore Western Australia development as it now has operatorship and major shareholding in Scarborough, the NWS, and Browse projects.