A mobile submersible drilling structure consisting of a barge hull that rests on bottom, steel posts that rise from the top of the barge hull, and a deck that is built on top of the posts, well above the waterline. it is used to drill wells in water no deeper than about 30-35 feet (9-10.7m). [...]

An offshore drilling rig, usually with a large hull. it has a mat or legs that are lowered to the sea-floor and a main deck that is raised above the surface of the water to a distance where it will not be affected by the waves. also called a jackup drilling rig.

A floating offshore drilling unit that has pontoons and columns that when flooded cause the unit to submerge in the water to a predetermined depth. living quarters, storage space, and so forth a reassembled on the deck. semisubmersible rigs are either self-propelled or towed to a drilling site and either anchored or dynamically positioned over [...]

A mobile bottom-supported offshore drilling structure with columnar or open-truss legs that support the deck and hull. when positioned over the drilling site, the bottoms of the legs rest on the seafloor. a jackup rig is towed or propelled to a location w

An opening into a tank, usually through the top deck.