Allseas’ heavy lift and pipelay vessel “Pioneering Spirit” has safely completed the single-piece removal of the 25,000 t Brent Bravo topsides from the North Sea.
Image: Pioneering Spirit removes 25,000 t Bravo platform. Photo courtesy of Allseas Group S.A.
Completed early Tuesday morning, the operation took approximately 4 hours, from positioning the vessel around the platform to the moment of the lift. The actual “fast lift” of the topsides took only 9 seconds.
Brent Bravo is the second of four platforms, after Brent Delta in 2017, to be decommissioned and removed from the Brent oil and gas field. On both occasions, Shell U.K. Limited has utilised Pioneering Spirit’s revolutionary single lift, motion-compensated technology. Today’s lift successfully concludes two years of intense planning and offshore engineering works, and further reinforces the vessel’s reputation as an industry game-changer.
Located 186 km off the northeast coast of the Shetland Islands, the Brent Bravo platform comprised a topsides structure supported by three 12 m diameter steel-reinforced concrete legs, which stand in 140 m of water. Cuts between the topsides and supporting legs were made during the final months of platform preparations. Until the lift, the structure was held in place by purpose-built shear restraints that prevented lateral movement. The concrete legs remain in situ, capped with concrete covers fitted by one of the vessel’s cranes. A solar-powered navigational aid has also been installed on top of one of the capped legs.
The 125 m tall, 70 m wide topsides have since been sea-fastened on board Pioneering Spirit for transport to the Able UK decommissioning yard in Teesside, North East England. At a nearshore location off the coast of Hartlepool, the topsides will be transferred to Allseas’ cargo barge “Iron Lady” for the final leg of its journey, towage up the Seaton Channel and load-in to the quay at Able UK’s yard for dismantling.
Since becoming operational in 2016, Pioneering Spirit has lifted more than 130,000 t of topsides weight and installed over 1500 km of subsea pipeline. The single-lift removal of the 24,200 t Brent Delta topsides in April 2017 set a new record for a lift undertaken at sea, until Pioneering Spirit’s installation of the 26,000 t production platform for the Johan Sverdrup development offshore Norway, earlier this year.
Source: Company Press Release