Subsea installation campaigns in support of deepwater field developments are expensive and require specialized vessels to carry-out the work scope. The traditional method entails deploying a costly subsea construction vessel, complete with remote operated vehicle (ROV) capabilities, survey and heave-compensating cranes. However, with a Floating, Drilling, Production, Storage and Offloading (FDPSO) postioned directly over the drill center, a new alternative to the traditional subsea installation campaign came into view. This paper presents the unique challenges related to subsea hardware installation from an FDPSO, and the methods developed to overcome those challenges.
The Floating, Drilling, Production, Storage and Offloading (FDPSO) concept requires that it is located over the wells for direct access, and so the ability to perform subsea construction and intervention activities directly from the host becomes a real possibility. The FDPSO provides a large stable platform from which these activities can be accomplished, but it has limited access and maneuverability, and so these challenges must be addressed.
These challenges were met and overcome in the pioneering Azurite field development in Mer Profonde Sud (MPS) block offshore Republic of Congo. The FDPSO was fitted with a working class remote operated vehicle (ROV) spread, along with a 100 tonne heave-compensating crane mounted to the deck. The 100 tonne crane was sized to install hardware as heavy as subsea trees.
Some of the equipment deployed from the Azurite FDPSO included: subsea trees, flexible well jumpers, steel tube flying leads and electrical flying leads.