North Sea Decommissioning and Green Vessel Innovation Headline Offshore Activity

## Offshore Industry Briefing: Decommissioning Milestones and Green Vessel Innovation ### Allseas Taps ABL for Record-Scale North Sea Topside Lift Swiss-based offshore contractor Allseas has engaged energy and marine consultancy ABL to provide technical support for what is set to be one of the most ambitious single-lift decommissioning operations in North Sea history. According to Offshore Energy, the project involves the removal of a 60,000-ton topside structure in a single motion on the Norwegian Continental Shelf. ABL, which operates as part of Oslo-listed global consultancy group Aqualis, will provide specialist marine and engineering consultancy services to underpin the complex operation. Single-lift removal at this scale demands rigorous planning, structural analysis, and marine assurance — disciplines central to ABL's service offering. The engagement marks the next chapter in Allseas' growing North Sea decommissioning portfolio. The company is widely recognised for its heavy-lift expertise, having previously executed large-scale offshore removals using its flagship vessel *Pioneering Spirit*. A 60,000-ton single-lift would represent a significant operational benchmark for the sector, underscoring the increasing scale and technical complexity of North Sea decommissioning as ageing infrastructure reaches end-of-life across the basin. With the Norwegian Continental Shelf alone facing billions of dollars in projected decommissioning expenditure over the coming decades, projects of this nature highlight the critical role specialist contractors and consultancies play in safely and efficiently retiring legacy assets. --- ### Methanol-Ready Rock Installation Vessel Launched in Rotterdam In a separate development reflecting the offshore industry's push toward greener operations, Rotterdam-based CSL OWL Subsea Rock Installation (CSL OWL SRI) — a partnership between The CSL Group and OWL — has launched a new methanol-ready subsea rock installation vessel, Offshore Energy reports. The vessel's methanol-ready designation positions it at the forefront of the industry's energy transition efforts, enabling future fuel switching as methanol bunkering infrastructure matures across European ports. Subsea rock installation vessels play a vital role in offshore wind and subsea pipeline projects, providing seabed preparation, cable protection, and scour prevention services. The launch in Rotterdam, a hub for offshore and maritime innovation, signals continued confidence in the European offshore wind market, where demand for specialised installation vessels remains robust as governments accelerate renewable energy targets. --- Together, these developments illustrate the dual pressures shaping the offshore sector: the growing urgency of decommissioning North Sea legacy infrastructure at scale, and the industry-wide imperative to decarbonise vessel operations in support of net-zero commitments.