offshore drilling

There are various types of underwater oil drilling installations; the one used depends on the location of the deposit and the depth of the water.

drill ship

Ship for drilling for oil in deep water (3,300 ft and more); it is more mobile but less stable than a semisubmersible or jack-up platform.

semisubmersible platform

Movable structure that is anchored to the seabed and used at depths of 350 to 1,650 ft; it is mounted on pontoons submerged at about 100 ft to provide stability.

fixed platform

Structure that is mainly used at moderate depths (up to 1,300 ft); it rests on the seabed on pillars buried deep in the sea floor.

pier

Structure that extends into the sea from a land-based installation; it is used for land drilling extending offshore (about 10 ft deep).

emergency support vessel

Floating structure equipped with specialized equipment; it is used for rescue operations on drilling rigs.

jack-up platform

Movable structure that is used in shallow water (between 65 and 330 ft); it is raised above sea level on retractable pillars resting on the ocean floor.