Drilling Rigs - Semi-Submersible
A Semi-submersible platform or rig, is a mobile structure used for drilling for oil and natural gas in offshore environments. Their superstructures are supported by columns sitting on hulls or pontoons which are ballasted below the water surface. They provide excellent stability in rough, deep seas. Semi-submersible rigs can be moved from place to place; and can be ballasted up or down by altering the amount of flooding in buoyancy tanks; they are generally anchored by cable anchors during drilling operations, though they can also be kept in place by dynamic positioning. Semi-submersibles can be used in depths from 600 up to 35,000 feet (180 to more than 10,600 m).
Ensco 121 in Singapore October 2013.
Pic taken from Maersk Logger.
Anchors and chain
For those who wonder what holds the rigs in position while they are drilling. Picture taken in Montr...
Picture taken from Maersk Laser. We where up doing some bouy work round the Brent-B and Bent-A had s...
Maersk Helper alongside the Wil Pheonix about to start anchor handling. Picture taken from Maersk La...
Treasure Swan Semi Sub.
shows Dresser Atlas wireline logging unit with logging tools and d...