Stones Turritella FPSO pre-commissioning

Location: Stones field along the Walker Ridge protraction area
Region: Gulf of Mexico
Water depth: Ultra-deep water 9,490 ft. (2,892 m)
Date: Q1 2015

CHALLENGES

As well competing with other contractors for good weather windows during simultaneous pre-commissioning operations, InterMoor, a brand in Acteon’s Engineering, Moorings and Foundations division, faced several technical challenges typical of ultra-deep water projects, including high loads (over 200mT) and size of chain components.

SCOPE OF WORK

• Chain tensioning/de-tensioning through the in-line mooring connector (ILMC) tensioning system
• Subsequent cut and removal of excess chain
• Riser pull-in rope stretching and transfer to the FPSO
• Provision of Tow Masters on-board the FPSO
• BTM buoy clump weight rigging removal
• Dock and equipment support to Shell contracted heading control tugs
• FPSO heading control steering lines design, procurement and offshore installation
• Dive-Support Vessel mooring design, procurement and offshore support for hook-up and disconnection

InterMoor provided full project management and engineering, including: design, procedures, procurement, dock support, offshore equipment and personnel for all phases.

UTEC provided the positioning survey for the AHV

Mirage custom-designed and fabricated the diamond wire cutting saw and clamping system.

KEY ASSETS

Seacor Keith Cowan anchor-handling vessel (AHV)

HOS Iron Horse in the second part of the operations.

SOLUTIONS AND KEYS TO SUCCESS

• Integrated project team
• Extensive and thorough planning
• High quality engineering
  • E.g. design of specific interface adapter between clamp and cutting saw to mitigate heave
  • E.g. special use of Orcaflex to model dive vessel movements in relation to FPSO
• Responsiveness to client’s changing needs
• HSE focus
• Flexible/cost-effective spread: cheaper/smaller vessel (AHV)

OUTCOMES

• Chain removal completed successfully, i.e. no dropped objects
• No LTIs or recordable incidents
• The job was completed without schedule impacts for the FPSO