Oilfield Catalog - Gates Corporation

Rig Technology
Choices range from ships to artificial islands
used in the Arctic where ice would
crush other structures.
Another consideration is how long it will be
on location. A tremendously costly permanent
platform would not be chosen for a
wildcat well that may or may not find oil. But
it may be the choice in a proven field where
reserves are expected to last 25 years.
It is important to distinguish offshore drilling
rigs from offshore platforms. Platforms are
immobile units used in known oilfields from
which several development wells can be
drilled to tap a proven reservoir. Platforms
are large enough to contain both production
as well as drilling facilities.
Rig Types
Jackup
Today, most of the world’s offshore drilling
is in continental shelf waters, which vary to
a maximum of about 600 feet (183 meters).
This has made the jack up rig one of the most
common in the world. Jackups work in up to
450 feet (137 meters) of water (Figure 5).
A jackup can be floated to its site since its
legs (which pass through its hull) can be
jacked up out of the water. On site, the legs
are jacked down until they sit firmly on the
seafloor. Then the hull is jacked up out of
the way of waves.
Fig. 5 Offshore drilling rigs
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