Spread Mooring Systems

In the case of a spread-moored FPSO/FSO, the tanker or process barge is moored in a fixed heading with anchor lines distributed over the bow and stern of the vessel, to anchor points situated on the seabed. The heading is determined by the prevailing sea and weather conditions. The spread-moored FPSO/FSO can only be used on locations where currents, waves and winds are very moderate or normally come from a prevailing direction.

With this type of FPSO/FSO no turret or swivel stack is required, as the vessel does not change heading in relation to the risers connecting the tanker with the wells on the seabed. To offload crude from a spread-moored FPSO/FSO, a separate tanker loading facility should be provided as the shuttle tanker cannot safely moor in tandem to the FPSO/FSO due to changing current, wind and wave direction, possible interference with anchor lines and high risk of collision.

SBM Offshore’s deepwater CALM buoys have been designed as offloading facilities for deepwater spread-moored FPSOs.