IntecSea conducted a study to investigate the feasibility of lazy wave steel catenary risers (SLWR) for the Sea Lion Project. Four different riser types, namely: production riser, water injection riser, gas injection/production and gas lift were assessed.
Steel catenary risers (SCRs) have been the preferred risers for deep and ultra-deep waters on account of their simplicity and lower cost. In the harsh environmental conditions of the south Atlantic sea, lazy wave SCRs offer reduced payload on the host vessel, and strength and dynamic response along the riser can be better controlled. The design challenge was to determine a suitable riser configuration ensuring strength and fatigue objectives were met.
The shape was determined to reduce vessel payload, the quantity of buoyancy modules, lateral motions and vertical distance between the arch and the sag bend. A combination of engineering judgement, past experience, and model iteration was required before zeroing in on the best configuration for riser strength and fatigue performance.
The study confirmed the feasibility of SLWR (Steel Lazy Wave Riser) at water depths of 450 m.