A drillship is a maritime vessel that has been fitted with drilling apparatus. It is most often used for exploratory offshore drilling of new oil or gas wells in deep water or for scientific drilling. The drillship can also be used as a platform to carry out well maintenance or completion work such as casing and tubing installation or subsea tree installations. It is often built to the design specification of the oil production company and/or investors, but can also be a modified tanker hull outfitted with a dynamic positioning system to maintain its position over the well.
The greatest advantages these modern drillships have is their ability to drill in water depths of more than 2500 meters and of course the valuable time saved sailing between oilfields worldwide as per contractual agreement, they are completely independent compared with Semi-submersibles and jackup barges.
In order to drill,Marine Riser is lowered from the drillship to the seabed with a Blow Out Preventer (BOP) at the bottom that connects to the wellhead.
Drillships are just one way to perform exploratory drilling. This function can also be performed by Semi-submersibles, jackup barges, barges, or platform rigs.
The first drillship was the Cuss 1 [1] and the fleet size has been growing ever since with the 2009 fleet size expected to double to over 80 ships worldwide in 2013 [2]. Drillships are not only growing in size but also in capability with new technology assisting operations from academic research[3] to ice drilling [4]
References
- ^ [A Brief History Of Dynamic Positioning]
- ^ "Drillship Building Statistics". http://www.shipbuildinghistory.com/world/highvalueships/rigsonorder.htm.
- ^ Konrad, John (July 25, 2008). "Drillship R/V Aurora Borealis - Future Ships". gCaptain. http://gcaptain.com/maritime/blog/future-ships-rv-aurora-borealis/.
- ^ Konrad, John (May 20, 2008). "DrillMAX ICE - Stena To Build Ice-Class Drillship". gCaptain. http://gcaptain.com/maritime/blog/stena-to-build-ice-class-drillship/.
See also
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