Allseas’ heavy lift vessel Pioneering Spirit has completed its first decommissioning job of this summer, the single-lift removal of Shell’s Brent Alpha platform from the North Sea.
Several years of planning and 15 months of offshore preparation, including strengthening and cutting the steel jacket’s six legs, culminated in the 9-second “fast lift” of the 17,000-t topsides in the evening of 21 June 2020, Allseas reported on Monday.
Pioneering Spirit will now deliver the 44-year old structure to Able UK’s Teesside decommissioning yard in North East England for dismantling and recycling.
Brent Alpha is the third of four platforms, after Delta (2017) and Bravo (2019) , to be decommissioned and removed from the Brent oil and gas field.
Shell selected the Pioneering Spirit vessel for all four jobs.
Production from the field continues through Brent Charlie, with Pioneering Spirit booked to remove the 34,000-t topsides when the platform finally ceases production.
Located 186 km off the northeast coast of the Shetland Islands, Brent Alpha comprised a topsides structure supported by a steel six-legged jacket standing in 140 m of water.
Like Delta and Bravo, the Alpha topsides features multiple decks with living quarters, power generation, process systems, drilling derrick, flare stack and other platform facilities.
According to Allseas, the removal of Brent Alpha was the first offshore lift to utilise specially developed “horseshoes”: connection tools that clamp around pre-installed lift points called bearing brackets mounted on the upper sections of the steel jacket’s legs.
The Brent Alpha topsides removal project involved engineering, preparation, removal and disposal of the 94 m tall, 52 m wide structure.
As with the two previous Brent jobs, Pioneering Spirit will transport the Alpha topsides to a nearshore location off the Hartlepool coastline, where it will be transferred to Allseas’ cargo barge Iron Lady for the final leg of its journey by towage up the Seaton Channel and load-in to the quay at Able UK.
All photos by Allseas