Introduction to Offshore Structures - Offshore Structures: Design, Construction and Maintenance - page 15

FIGURE 1.6 Concrete gravity platform.
In areas where there is a low oil reserve, only one well will be drilled. Many
alternatives were devised to address this situation and to obtain the business
target. One solution is to have a subsea well that is connected to the nearest
platform by a pipeline. This solution is costly, but it is now used widely in
deep water.
Another solution is to use a minimal offshore structure, as is shown in
elevation and plan views in Figure 1.8(a) and (b) . The concept for this platform
is to use the conductor itself as the main support for the small deck. There are also
two diagonal pipes that are connected to the soil by two piles, as shown in the
elevation view ( Figure 1.8(a) ). Figure 1.9 shows the shape of the topside of
this three-legged platform.
Floating Production, Storage and Offloading
The first floating production, storage and offloading (FPSO) platform was the
Shell Castellon, built in Spain in 1977. The first conversion of an LNG (lique-
fied natural gas) carrier (Golar LNG owned the Moss-type LNG carrier) into an
LNG floating storage and regasification unit was carried out in 2007 by the
Keppel Shipyard in Singapore. In the last few years, concepts for LNG
FPSOs have also been launched. An LNG FPSO works under the same
principles as an oil FPSO, but it produces only natural gas, condensate and/
or liquefied petroleum gas (LPG), which is stored and offloaded.