Lessons associated to the FFFA development comprises of the Fife, Fergus, Flora and Angus fields. The FFFA fields are located in the central North Sea, in Blocks 31/21, 31/26, 31/27a, 39/1 and 39/2, of the UK Continental Shelf (UKCS), approximately 330 km east-south-east of Aberdeen, in a water depth of approximately 71m. Hess was the Operator of the four fields on behalf of the co-venturers. Bluewater Energy Services (BES) owned and supplied the FPSO Uisge Gorm and operated the four fields as Duty Holder, under contract to Hess.
KEY PROJECT LEARNINGS: Execution philosophy has evolved during the lifecycle of the project with key learnings from each phase being captured and implemented during future activities as far as possible.
Data retention: Accurate recording of historical subsea configuration changes to wells and infrastructure is essential for efficient decommissioning planning.
Ageing Infrastructure – Flexible riser integrity: Increased risks associated with recovering flexible risers of deteriorated integrity.
Efficiency of subsea infrastructure flushing regime during decommissioning: Removal of entrained hydrocarbons from all associated subsea flow-lines achieved by accurate as-left status mapping prior to devising subsea infrastructure flushing programme.
Disconnection of flowline infrastructure from subsea trees: Initiate as early as possible during field suspension phase after CoP to mitigate against the potential for well pressure migration through shut-in trees.
Removal of subsea infrastructure by cutting and lifting in sections: Seabed surface pipeline topography mapping to be understood prior to cutting subsea pipelines. Cutting methodology to allow for remedial containment plan in the event of trapped hydrocarbons at high points.
Ageing Infrastructure – Subsea mattresses construction: Evaluate subsea structures integrity prior to defining recovery inventory, decommissioning strategy and programme approval.
NORM scale management: Evaluate recovery to shore vs decontaminate and dispose offshore vs leaving contaminated components buried in situ subsea to arrive at the optimal solution with minimum environmental impact and EHS risks.
Well Abandonment: The use of dedicated disposal wells to flush subsea flow lines clear of residual hydrocarbons prior to disconnecting at the tree wing flange (production or injection) can result in serious well control uncertainty and clean up issues during the future well abandonment phase.
Well Abandonment: Recovery of completion tubing and verification of casing cement bond by logging essential to dictate requirement for section milling and provide assurance of effective casing / zonal isolation in perpetuity.