Houston Offshore Engineering

Concept-neutral experience with every major technology used to support offshore facilities.

Spar

Spar offshore Engineering example The spread mooring system of a Spar does not influence the wave-induced motions of the platform. Instead, the Spar relies on its deep draft and large effective mass to keep vertical motions within an acceptable range.

Advantages of the Spar

Less sensitive than TLPs to water depth and payload
Allows surface wellheads (dry trees)
Vertical access to wells
Support of remote wells
Drilling and workover capability
Active lateral mooring system can provide drilling access to a large well pattern

Limitations of the Spar

More extensive offshore campaign for integration and installation
Sensitive to long period waves
Support of TTRs in very deep water
Limited centerwell space for large numbers of TTRs

The Spar configuration typically includes a buoyant upper section (hard tank), a deep lower section to contain permanent solid ballast material (keel tank), and a structural connection between the hard tank and keel tank that may take the form of a truss structure (for a Truss Spar) or a flooded circular cylinder (Classic Spar).

The Spar is very effective once installed but the large size and draft increase the complexity of fabrication and delivery. Loadout, transporation, upending and offshore installation and hookup for the topsides must be carefully planned and executed to avoid cost escalation and schedule delays.