ABERDEEN, UK – DOF Subsea has completed decommissioning works for Repsol Sinopec Resources UK at the Buchan and Hannay fields in the central UK North Sea.
For the 74-day offshore portion of the Engineering Preparation, Removal and Disposal (EPRD) services program, DOF Subsea deployed the Skandi Acergy and Skandi Skansen vessels to recover 135 concrete mattresses weighing around 800 metric tons (882 tons), more than 12 km (7.5 mi) of rigid pipelines, subsea isolation valve/PLEM structures, 15.5 km (9.6 mi) of flexible pipelines and umbilicals, spoolpieces, and around 1,500 grout bags and general debris.
Material was shipped to Aberdeen Harbour’s Clipper Quay for dispersal, with 95% being recycled and 4% repurposed. The remaining 1% was sent to landfill.
Fifteen of the concrete mattresses were repurposed into aggregate for use in roads at the Aberdeen Harbour extension project, while the plastic sheaths from the flexible risers and umbilicals were recycled and all the metal smelted.
DOF Subsea worked with Scotoil Service in Aberdeen throughout the process, Scotoil removed any NORM-contaminated waste in metals or plastics via high pressure cleaning. Decontaminated metals and plastics were then recycled.
In 2019, DOF Subsea performed EPRD services for the same two offshore fields, including the 124-metric ton (137-ton) mid-water arch.