Scarborough gas field

The Scarborough gas field is a natural gas field located in the Indian Ocean north-west of Exmouth on the coast of Western Australia.[1]

The total Contingent Resource of the Scarborough gas field is around 7.3 trillion cubic feet.[2] In 2018 Woodside bought ExxonMobil's 50% share of the retention lease, adding to the 25% it had acquired from BHP in 2016.[3] Woodside now owns 75% of the retention lease and are operator of the joint venture, with BHP retaining the final 25%.[4] On 7 April 2022, the company announced that final Australian federal and state government approvals for the project had been received.[5]

Offshore development concept

The Scarborough gas field is currently not a producing asset. Woodside is proposing to develop the Scarborough resource with 12 subsea, high-rate gas wells tied back to a semi-submersible platform moored in 900 m of water. The ~20,000 t topsides has processing facilities for gas dehydration and compression to transport the gas through a ~400 km pipeline to the Woodside operated Pluto LNG facility.[2]

The Scarborough resource has been fully appraised and the reservoir consists of excellent quality sands which support recoverable volumes in excess of 0.5 Tcf per well. The Scarborough gas reservoir is relatively shallow at only 900 – 1,000 m below the mudline. The lean reservoir gas is classified as ‘sweet’ with no detectable H2S and only trace levels of CO2.[2] However, sources other than Woodside have contradicted this finding and established that the field would result in an additional 1.6 billion tonnes of CO2 emissions over its lifetime - the equivalent of 15 coal fired power plants.[6] Other sources have suggested that no new oil or gas resources should be developed for Australia to have a chance of meeting their climate goals.[7]

A phased development drilling program is proposed, with seven wells available at ready for start-up (RFSU). Given the shallow depth below the mudline and anticipated strong aquifer support, a combination of horizontal and high angle wells have been designed with maximum well lengths of ~2,500 m. The well and completion designs align with Woodside's extensive development experience offshore north-western Australia.[2]

The proposed carbon steel trunkline will be ~400 km long, significantly shorter than recently constructed offshore gas pipelines in the region. Woodside's ongoing subsea development programs in the North West Shelf and Exmouth area provide contemporary analogues for cost and execution schedule estimates. The seabed transition zone from the deep water to the North West Shelf is well known to Woodside after previous successful projects in the area. In preparation for future expansion, Pluto LNG constructed a shore crossing for a second trunkline.[2]

country	Australia
region	Indian Ocean
offonshore	offshore
operator	Woodside
discovery	1979
est gas bft	7300
est gas bcm	200

Scarborough gas field

Offshore development concept

Onshore development concept

Cost

References