The program involved removal of six subsea conductors and four vertical supports in varying water depths, and also the upper conductor guideframes with an estimated weight of 400 metric tons.
In addition, the company was responsible for the design and installation of bespoke clamps.
DeepOcean completed all work within 16 weeks of contract award. Gary Scott, UK commercial manager and legal counsel, said, “The project required intensive dynamic and structural analysis to enable the removal of the upper conductor guide frames. The scope also required significant shallow-water ROV operations for the removal of the upper guide frame and conductors.”
Preparatory engineering and contingency options and spares packages ensured minimal weather downtime and avoided the risk of loose conductors left hanging during the winter season.
DeepOcean’s Aberdeen office handled the engineering and project management, with support from its operations in Haugesund and Stavanger, with offshore work executed from the hybrid-battery-powered construction support vessel Edda Freya.
Subcontractors included Claxton, Machtech and Global Energy Group.
The Dunlin Alpha platform, installed by Shell 137 km northeast of Shetland in a water depth of 151 m, came onstream in 1978 and produced more than 522 MMbbl of oil from fields in the area over the next 37 years. Fairfield Energy assumed full operatorship in 2014.