Stones Turritella FPSO pre-commissioning
Project overview
Project name
Stones Turritella FPSO
Location
Gulf of Mexico
Water depth
Ultra-deep water 9,490 ft. (2,892 m)
The Turritella FPSO, which arrived in January 2016, is turret-moored via a dis-connectable Buoyant Turret Mooring (BTM) system with nine mooring lines arranged in three bundles. Each line includes an in-line mooring connector (ILMC) located ~900 ft subsea, pre-tensioned prior to FPSO arrival. Upon recovery of the BTM, Intermoor performed final chain tensioning via the ILMCs, removed excess chain, and managed riser pull-in rope transfer to the FPSO.
Facing ultra-deepwater challenges
As well competing with other contractors for good weather windows during simultaneous pre-commissioning operations, our team faced several technical challenges typical of ultra-deepwater projects, including high loads (over 200 mT) and large size of chain components.
High-level integration and specialist engineering
Intermoor supported this FPSO’s mooring needs by utilising a cost-effective and Jones Act compliant anchor handling vessel (AHV), whereas competitors would typically resort to a large construction vessel.
We successfully provided full project management and engineering, including design, procedures, procurement, dock support, offshore equipment and personnel for all phases.
Through meticulous planning and top-tier specialist engineering, our team designed installation aids and fabricated them in our Morgan City facility, in Louisiana, such a specific interface adapter between the clamp and the cutting saw to mitigate the heave. Our team also developed an advanced application of Orcaflex to model the vessel movements in relation to the FPSO.
The scope of work included:
- Chain tensioning/de-tensioning through the 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
The result
Acteon provided a fully integrated and efficient solution: alongside Intermoor, UTEC provided the positioning survey for the AHV, and we used our other capabilities to custom-design and fabricate the diamond wire cutting saw and clamping system.
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