The Tyra platforms have been used as core infrastructure of Denmark’s energy for 30 years.
However, due to the subsidence of the depleted reservoirs causing the platforms to sink, the field required decommissioning and redevelopment. Allseas awarded Mammoet’s Conbit operation with an extensive platform preparation scope at the Tyra field. In partnership with Allseas, a multi-disciplinary project was carried out to prepare two topsides for single-lift removal by the Pioneering Spirit vessel.
The project took place between May and August 2020. The outbreak of COVID-19 impacted the project significantly. Mobilization of a 60 people crew from all over Europe to Denmark is always challenging. The Corona measures in the different EU states make it even more complex. Travel to Germany was restructured and Denmark had a quarantine measure in place, which impacted the duration of the rotation of the crew. However, Conbit proved to be very effective in planning the mobilization of the crew.
The scope of work required the use of different cutting techniques. Conbit used blow torches, diamond wire cutting, and hot cutting methods, besides deploying a semi-remote blow torch machine to cut a large-diameter monopile. Welding was also required at the topsides to sea fasten modules, create reinforcements, and reinstate pad eyes. Below deck items needed to be secured by welding, subject to thorough quality control.
Rigging and lifting is the core competency of Mammoet’s Conbit operation. Many components had to be rigged from underneath the topsides, giving rise to long traveling routes until components are within crane reach that had to be designed with care to not affect project scheduling. For all works below the topsides, Conbit used rope access techniques. Welding and cutting activities were performed using these techniques, but for the lifting and rigging work packages rope access was also the preferred method, as it reduced the requirement for scaffolding to be constructed, saving time.
More than 27,000 tons of platform facilities from the North Sea’s Tyra gas field were safely transferred to the M.A.R.S. recycling yard in Frederikshavn. It is expected to recycle 95% of the old facility. Thanks to the redevelopment project of Tyra initiated by Total E&P, Tyra platforms will maintain their role as a core of Danish energy production. The redeveloped platforms are expected to produce 60,000 barrels of oil equivalent per day after the completion of the Tyra project.