Woodside Petroleum is seeking expressions of interest from subsea engineering houses keen to participate in the design of the massive offshore pipeline for the Browse liquefied natural gas project in Australia, writes Russell Searancke.

The 900-kilometre 42-inch pipeline will extend from the two Browse floating production, storage and offloading vessels and end at the North West Shelf LNG facility.

It will transport dry gas and will navigate subsea features including water depths up to 550 metres, seabed sand waves and undulations that may require pre and/or post-lay corrections, and crossings by other operators, said Woodside.

The operator has given subsea engineering houses until 8 April 2019 to express their interest in performing front-end engineering and design services on the trunkline.

Perth-based Atteris is currently performing the subsea concept definition engineering for the Browse infield layouts, infield flowlines, dynamic risers and the export trunkline.

The trunkline will be capable of transporting up to 2 billion cubic feet per day of gas based on the design throughput of the two planned FPSOs.

Woodside said recently that a reconnaissance survey along the proposed pipeline route from the Brecknock, Calliance and Torosa fields to the proposed tie-in point adjacent to the North Rankin platform complex was completed in November 2018.

Meanwhile a metocean survey programme began in January 2019 along the planned pipeline route.

The Browse project covers three fields — Torosa, Brecknock and Calliance — in water depths of up to 750 metres.

They contain a combined best estimate contingent resource of 13.9 trillion cubic feet of gas and 390 million barrels of condensate.

The Browse joint venture and the North West Shelf Venture are currently working on converting a preliminary agreement for the processing of Browse gas through the North West Shelf LNG facility.

The Browse joint venture comprises Woodside on 30.6%, Shell on 27%, BP on 17.33%, Mitsubishi-Mitsui (MiMi) on 14.4% and PetroChina on 10.67.

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