Recently turret-Moored Floating Production Storage and Offloading systems (FPSO) have been used in many deep water developments worldwide, with consideration of disconnectable turrets for harsh environment applications. This trend makes the interactions between FPSO and riser system more important. Further, Steel Lazy Wave Riser (SLWR), which is a compliant variant of the most commonly used Steel Catenary Risers (SCR), is becoming an attractive riser option.
The paper provides a review of the various riser systems that can be considered for turret-moored FPSOs, and specific emphasis on SLWR. A detailed case study of SLWR for a typical turret moored FPSO with disconnectable turret is presented. This system is described in terms of design and functionalities, the fabrication and installation methods are presented. The case study shows clearly that an improvised SLWR is an attractive alternative to be used for FPSO with disconnectable turret and is very efficient to fabricate and install in a very cost effective manner.
Pros and cons for SLWR are discussed, with consideration of the particular challenges of turret-moored FPSOs with large floater motions, hang-off geometry constraints at turret, hang-off loads, riser interferences, risers pre-installation, and turret disconnection constraints.