Against heat and strong seas: Allseas delivers nearshore pipeline for Santos off Australia

Allseas’ recently converted shallow-water pipelay barge has completed nearshore construction activities for the Darwin Pipeline Duplication project being developed by Australian energy giant Santos offshore Northern Australia.

The flat-bottom, anchored barge Sandpiper carried out the work to deliver the 32-kilometer shallow water section, including pull-in to the existing Darwin Liquified Natural Gas (DLNG) facility.

According to Allseas, the crew endured intense heat and humidity, strong currents and tidal changes up to 8 metres, with the pipelay further complicated by the congested nearshore seabed, home to live gas lines, exclusion areas, protected wrecks and potential UXOs, requiring each anchor position to be carefully pre-engineered.

Allseas completed an upgrade of Sandpiper last year, with the barge becoming the first in its fleet to be fitted with an in-house developed automated anchor positioning system, designed to maximize safety and efficiency when operating its anchor mooring spreads in shallow waters.

Santos, as the operator of the Barossa joint venture, announced at the end of August 2022 that a final investment decision (FID) had been taken to proceed with the Darwin Pipeline Duplication Project.

The pipeline will extend the Barossa Gas Export Pipeline to the Darwin LNG facility and allow for the repurposing of the existing Bayu-Undan to Darwin pipeline to facilitate carbon capture and storage (CCS) options.

This January, Santos reported that the Darwin Pipeline Duplication was 71.4% complete. At that time, the Barossa gas project was 88.3% complete, remaining on track for first production in the third quarter of 2025.

In terms of Allseas’ other recent activities in Australia, the company announced at the end of 2024 that it had begun the planning and preparation for the largest-ever offshore decommissioning assignment in the country encompassing the removal of up to 12 retired platforms.