This paper is a description of the Veslefrikk transfer systems which are the connections between the permanently installed fixed wellhead platform and the floating production platform on the Veslefrikk field. The main elements in the system are a 40 m long telescopic bridge and a number of 150 m long free hanging flexible pipes and electrical cables transferring fluids, power and control signals. The transfer systems operational and design requirements are addressed as well as a general description of the system design and analysis.
The Veslefrikk field development consists of a jacket wellhead platform (VFA) and a semisubmersible production and quarters platform (VFB). VFB is moored close to VFA and the normal operational distance between the two platforms is 36 m. The water depth at the Veslefrikk location is 174 m.
The major system split between the two platforms and location of main equipment are as follows:
VFB:
Process facilities
Power generation
Living quarters
Water injection System
Gas export compressor system
Crude export pumping system
Gas lift compressor system
Mud pits and cleaning system
Mud pumps
Cement pumps
Wellhead systems for production and water injection wells
manifold system
Drilling derrick
Connections for gas and crude export pipelines
Pig launchers
Sale-shakers for primary mud-cleaning
Due to this system separation, a transfer system as shown in fig. 1 and fig. 2 is required between VFA and VFB compromising the following main elements:
telescopic bridge
flexible pipe system
electrical cable system
The flexible pipe system consists of pipes for transfer of production fluid from the wellhead and manifold system on VFA to the process facilities on VFB. Further, the system consists of pipes transferring produced oil and gas from VFB to VFA where the export pipelines for oil and gas are terminated. Gas lift and water injection are transferred from VFB to VFA through the system.
The mixing and pumping systems for mud and cement are located on VFB. Flexible pipes transfer mud and cement over to VFA and return mud back to VFB
The power generation plant and the main control centre are located on VFB. The electrical cable system transfers electrical power from VFB to VFA and control signals between the two platforms.
Transfer system considerations Previous examples of floating platforms operating alongside fixed platforms were evaluated in the early Veslefrikk project study phase in 1986 to establish the feasibility of such a concept. The fixed/floater combination had been used on the Odin field in 1983 where a semisubmersible drilling rig provided drilling mud, casing, storage and extra accommodation facilities. Also a number of flotels had been in operation anchored close to a fixed platform to provide extra accommodation.
