Page 14 - Oil and Gas Production Handbook An Introduction to Oil and Gas Production

A variation of the FPSO is the
Sevan Marine design. This uses a
circular hull which shows the same
profile to wind, waves and current
regardless of direction. It shares
many of the characteristics of the
ship-shaped FPSO such as high
storage capacity and deck load,
but does not rotate and therefore
does not need a rotating turret.
Photo: Sevan Marine
A Tension Leg Platform (TLP –
left side in picture) consists of a
structure held in place by vertical
tendons connected to the sea floor
by pile-secured templates. The
structure is held in a fixed position
by tensioned tendons, which
provide for use of the TLP in a broad water depth range up to about 2000m.
Limited vertical motion. The
tendons are constructed as hollow
high tensile strength steel pipes
that carry the spare buoyancy of
the structure and ensure limited
vertical motion.
Semi-submersible platforms
(front of picture) have a similar
design but without taut mooring.
This permits more lateral and
vertical motion and is generally
used with flexible risers and
subsea wells.
Something similar are Seastar
platforms which are miniature
floating tension leg platforms,
much like the semi-submersible
type, with tensioned tendons.
A SPAR consists of a single tall floating cylindrical hull, supporting a fixed
deck. The cylinder does not however extend all the way to the seabed, but is
tethered to the bottom by a series of cables and lines. The large cylinder
serves to stabilize the platform in the water, and allows for movement to

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