GVA 8000 Floating Production and Drilling Unit (FPDU), an Umoe/design
Visund was installed at StatoilHydro's Visund field in 1998. The unit is fully self-contained. Hence in addition to performing oil production, it drills its production wells, installs wellheads through the moon pool and performs all the necessary work over activities. The production rates for the Visund semi are 100,000 BPD of oil and 350 MMSCFPD of gas, initially for injection and later on for export.
GVA involvement in the project included Hull FEED and site support in Norway.
With the development of directional drilling it is nowadays possible from one drilling location to reach the boundaries of large reservoirs or develop several reservoirs located far apart in horizontal direction.
Visund drilled in 2005 the world’s longest well from a floating installation (9082 meters), at the time also the longest well ever drilled by StatoilHydro.
The Visund FPDU represents our first quadrangular pontoon design, which makes braces unnecessary. Still it features the four column design with a deck-box configuration. The platform was built in Norway, with the lower hull and the deck fabricated at different sites and joined together in a mating operation. The risers are all flexible and tied in to the deck level.
A FPDU with subsea wellheads gives similar drilling and work-over capabilities and costs as for a Spar or a TLP development. Considering the smaller hull size and mooring dimensions for a semi compared with these two competing concepts, the cost reduction for subsea X-mas trees and the evolution of risers, both flexible and steel catenary, a semi based FPDU is in many cases a more cost effective concept than a Spar or a TLP.