Global ocean services provider DeepOcean has successfully completed the recovery of the remaining subsea wellhead protection structure at the Spirit Energy-operated Seven Seas field, as well as the disconnection of subsea infrastructure at the operator’s nearby Grove West field in the southern North Sea, using proprietary tooling developed in-house for decommissioning.
DeepOcean delivered onshore engineering and project management, deploying the high-specification construction vessel Edda Freya to retrieve the more than 100 tonne wellhead protection structure, in addition to associated subsea infrastructure. All recovered materials have been transported for reuse, recycling or responsible disposal. The project was managed and executed by DeepOcean’s Aberdeen-based operations in the UK.
The work forms part of Spirit’s wider decommissioning programme for the Seven Seas and Grove West fields. Both scopes were carried out in preparation for a rig campaign.
“The wellhead protection structure at Seven Seas has served the field since 2011 and remains in very good shape. The piles were cut three metres below the seabed and the subsequent retrieval of the structure was conducted. We were delighted to support Spirit Energy on this project and look forward to working with Spirit Energy on future scopes of work,” says Robin Mawhinney, Executive Vice President for DeepOcean’s EMEA region.
The scope also included the disconnection of a spool from a subsea Christmas tree at Grove West. The operation was executed using a remotely operated vehicle (ROV) combined with specialized tooling, replacing the need for diver intervention traditionally required for such tasks.
Spirit Energy’s Decommissioning Manager, Ceri Wheaton, said: “We are committed to maximising material recovery and minimising waste throughout our decommissioning activities. By working closely with specialist contractors such as DeepOcean and leveraging the UK supply chain, we have safely recycled more than 95% of materials from decommissioned assets and infrastructure. This approach not only reduces environmental impact but also improves efficiency through streamlined logistics and the responsible reuse of valuable resources.”
“At Grove West, we disconnected two subsea flanges using methodologies and proprietary tooling developed during the Gryphon Alpha FPSO removal project last year. This project adds to DeepOcean’s growing track record of meeting project objectives across subsea decommissioning campaigns,” says Øyvind Mikaelsen, Chief Executive Officer at DeepOcean.
The Seven Seas structure was located approximately 80 km offshore the East Yorkshire coast in a water depth of around 33 metres. The Grove West structure was located approximately 130 km east of the UK coastline in a water depth of around 40 metres.