DeepOcean disconnects decommissioned North Sea Gryphon Alpha FPSO, subsea structures

DeepOcean is close to completing a decommissioning program for TotalEnergies for the disconnection and tow of the Gryphon Alpha FPSO from the UK northern North Sea and the removal of associated subsea infrastructure.

Kerr McGee originally commissioned the FPSO, which had been permanently moored in Block 9/18b, 11 km from the UK/Norwegian North Sea median line. It has hosted production from the Gryphon, Tullich, Ballindalloch and Maclure fields, previously operated by Maersk Oil, which TotalEnergies acquired in 2017.

DeepOcean said it had deployed proprietary tooling for the removal campaign that had allowed the entire scope to be performed fully diverless. The spool disconnection and blind flange installation represented standout diverless operations, the company claimed.

Tasks included flushing of subsea pipelines and manifolds, disconnecting flowlines and umbilicals from trees, removing risers and midwater arches, and recovering the FPSO moorings. Once disconnected, DeepOcean also managed towing of the FPSO.

DeepOcean’s team in Aberdeen executed the work with support from the company’s branch in Oslo. Recovery of mooring chains and removal of the risers and mid-water arches should be completed before the end of this year.