From mooring to decommissioning with a deepwater FPU

Lifecycle support across multiple phases

From relocation in 2006 to decommissioning in 2014, we provided tailored engineering and operational services. 

We designed and installed a 12-leg mooring system comprising suction embedded plate anchors (SEPLAs), stud link chain, subsea connectors and polyester mooring ropes. To address limited platform space, we developed a custom solution: routing excess inboard chain through hawsepipes and suspending it below the platform in the water. This configuration required meticulous management using deadman slings and straps to prevent overloading the chain jacks, with divers assisting in operations. 

In 2011, to comply with updated Metocean regulations and possibly extend the platform's life, we conducted mooring line inspections, replaced all rig wires and upgraded five mooring legs. Detailed analytical modelling and design processes ensured the upgraded system met new criteria. Strategic equipment placement and clear communication were vital during rig wire replacements, especially given the confined workspace and limited crane access. 

Three years later, we managed the decommissioning process:  disconnecting all 12 mooring lines and 10 risers/umbilicals, securing them to the seabed with concrete mattresses. Detailed modelling predicted riser behaviour, enabling precise and reliable laydown within 50 ft of projections. Coordinated efforts ensured the safe towing of the Innovator hull to Ingleside, Texas. 

Innovations in action

• SEPLAs for secure deepwater mooring
• Custom hawse pipe system for managing excess inboard chain
• Deadman slings and straps to control chain weight distribution
• Detailed analytical modelling for mooring system upgrades and decommissioning planning
• Strategic rigging and simultaneous operations coordination  

The result

Our integrated approach ensured the FPU Innovator's mooring system operated safely and efficiently throughout its life. Innovative solutions addressed unique challenges, from initial installation through upgrades to decommissioning.  

We delivered a safe, compliant and effective transition from production to decommissioning highlighting our ability to deliver across the offshore asset lifecycle.