دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: a floating offshore drilling unit that has pontoons and columns that, when flooded. cause the unit to submerge to a predetermined depth. Living quarters, storage space, and so forth are assembled on the deck. Semisutxnersible rigs are self-propelled or towed to a drilling site and anchored or dynamically positioned over the site, or both. In shallow water, some semi-submersibles can be ballasted to rest on the seabed. Semi-submersibles ale more stable than drill ships and ship-shaped barges and are used extensively to drill wildcat wells in rough waters such as the North Sea. Two types of semi-submersible rigs ale the bottle- type and the column-stabilized. See floating offshore drilling rig.

n: a floating offshore drilling structure that is towed to and from the drilling site. The unit has a streamlined bow and squared-off stern, a drilling derrick usually located near the middle of the barge, and a moon pool below the derrick through which drilling tools pass to the seafloor. It is identical in appearance to a drill ship, but is not self-propelled. It must therefore be towed to the drill site. Shipshaped barges are most often used for drilling wells in deep, remote waters. See floating offshore drilling rig.

n: see barge, drill ship, ship-shaped barge.