Client: Dana Petroleum
Location: UK North Sea

The Western Isles Development Project will be developed using a floating production, storage and offloading (FPSO) facility.

Oil will be exported by shuttle tanker and excess produced gas will be exported through a dedicated pipeline to Tern-NC gas line. The subsea facilities will be tied back to the floating production facility by a subsea pipeline bundle including flexible risers. Water injection is required to maintain the reservoir pressure and gas lift is also required to assist production.


  • Flow assurance
  • Pipeline mechanical and structural design
  • Design and specification of flowline and pipeline and tie-in systems
  • Dynamic analysis of the flexible riser system
  • Control system and umbilical design
  • EPCI cost estimate and schedule
  • ITT bid evaluation.


  • Multidisciplined integrated service offering
  • Full suite of subsea FEED engineering to support EPIC tendering
  • Experienced flexible riser team.

Lessons learned

  • Multiple FPSOs required 18 month FEED in order to develop subsea solutions for three FPSO options
  • Two separate EPCI ITTs required due to lack of decision on FPSO selection
  • Large number of risers versus MWA versus flow assurance complexity
  • Decisions with manifold size and well count delayed until late in FEED – requirement for rework
  • Export / import pressure discussions with Tern early in FEED.