Introduction to Offshore Structures - Offshore Structures: Design, Construction and Maintenance - page 11

called well protectors or well jackets. Usually a well jacket serves from one to
four wells.
Tender Platforms
Tender platforms are not used as commonly now as they were 40 years ago.
Tender platforms function as the drilling platform, but the drilling equipment
rests on the the platform topside. Nowadays it is common to use a jack-up
drilling rig, which does not rest on the platform deck.
With tender platforms, the derrick and substructure, drilling mud, primary
power supply and mud pumps are placed on the platform.
As mentioned, since tender platforms are not used much anymore, they will
not be encountered in new designs or new projects, but they may be encountered
in existing structures, so you must be familiar with them in order to perform
assessments for an existing drilling platform.
Figure 1.2 shows a tender platform. It is shown with two beams along the
platform deck length; the beams are used as a railway to the tender tower
above the deck for drilling activity.
Self-contained Platforms
The self-contained platform is large, usually with multiple decks that have
adequate strength and space to support the entire drilling rig with its auxiliary
equipment and crew quarters, and enough supplies and materials to last through
the longest anticipated period of bad weather when supplies cannot be brought
in. There are two types of self-contained platform: the template type and the
tower type.
Beam for moving
the drilling unit
FIGURE 1.2 Tender platform.