Page 72 - 4714

 What are the differences between land rigs and offshore rigs?

 What does the word “portability” mean?

 Are both land and offshore rigs portable?

 What is MODU?

 What types of submersibles do you know?

 Describe the structure of a bottle-type rig.

 Which types of barges are sometimes called "swamp barges"?

ROTARY RIG TYPES
Many kinds of rotary drilling rigs are available, particularly
offshore where the marine environment plays an important role in rig
design. Two broad categories of rig are those that work on land and
those that work offshore. Some experts like to create a third category:
rigs that work in inland waters. Inland rigs usually drill in lakes,
marshes, and estuaries, places that are neither land nor offshore,
places where, as one wit put it, "it's too wet to plow and too muddy to
drink." For our purposes, though, dividing rotary rigs into land and
offshore types is acceptable, because inland rigs also drill in water,
even if it is shallow.
LAND RIGS
Land rigs look much alike, although details vary. A major
difference is their size, and size determines how deep the rig can drill.
Well depths range from a few hundred or thousand feet (metres) to
tens of thousands of feet (metres). The depth of the formation that
contains, or is believed to contain, oil and gas controls well depth.
Classified by size, land rigs are light duty, medium duty, heavy duty,

71