Definitions of Various Offshore Drilling Rig Types and Generations

Many people ask us about the definitions of the various generations of offshore drilling rigs.The details below consist of definition of offshore rig types and meaning of rig generations. This will help you get more understanding so when you hear about this drillship is 5th generation rig and you will know right away what it means.

offshore rig definition

Jackup

jackup

Jackups are mobile, self-elevating drilling platforms that are equipped with moveable legs. Jackups are towed to a drilling site by tug boats before the unit lowers its legs to the seabed and then jacks up the hull to elevate it above the sea level, after which drilling operations can begin. The units are used exclusively for shallow water exploration and production drilling.

Semi-submersible

semi

 

A semi-submersible drilling rig is a floating drilling rig that is capable of working in water depths ranging from shallow through to ultra-deepwater. Semi-submersibles use a number of pontoons that are submerged beneath the water line to float and remain stable in a single location. The deck is positioned above the water line and sits on top of a number of columns that connect the hull to the submerged pontoons. Semi-submersibles offer an increased level of stability whilst drilling in comparison to drillships and are thus preferred for drilling in harsh environment regions

Drillships

drillship

A drillship is ship-shaped vessel that has been equipped for drilling operations. The unit can be utilised for drilling operations in midwater to ultra-deepwater areas and are generally preferred for exploration drilling as the assets are self-propelled. Drillships are kept on station using dynamic positioning systems

Tender assist drilling units (Tender/Semi-Tender)

tender

Tender assist drilling units (TADs) allow drilling operations to be carried out on a fixed platform without the need for a permanent drilling package on the platform. The TAD is stationed next to the platform and its drilling package is lifted onto the platform. The TAD remains in place in order to provide power and other services that support the drilling operation. There are two different types of TADs, a tender rig and semi-tender, both units carry the same equipment but the semi-tender is capable of operating in deeper waters and harsher environments

Rig Generations

7 basic generations determined by delivery year and water depth characteristics

Semi-submersible rig generations:

  • 1st Generation
    • Unit constructed from 1961 – 1972. Max water depth is N/A
  • 2nd Generation
    • Unit constructed from 1973 – 1979. Max water depth is N/A
  • 3rd Generation
    • Unit constructed from 1980 – 1985. Max water depth is N/A
  • 4th Generation
    • Unit constructed from 1986 – 1997. Max water depth is N/A
  • 5th Generation
    • Unit constructed from 1998 – 2004. Max water depth is N/A
  • 6th Generation   
    • Unit constructed from 2005 onwards. Max water depth is 10,000ft
  • 7th Generation
    • Unit constructed from 2015 onwards. Max water depth is 12,000ft

Drillship rig generations:

  • 1st Generation
    • Unit constructed from 1961 – 1970. Water depth is N/A
  • 2nd Generation
    • Unit constructed from 1971 – 1979. Water depth is N/A
  • 3rd Generation
    • Unit constructed from 1980 – 1985. Water depth is N/A
  • 4th Generation
    • Unit constructed from 1986 – 1997. Water depth is N/A
  • 5th Generation
    • Unit constructed from 1998 – 2005. Water depth is N/A
  • 6th Generation
    • Unit constructed from 2006 onwards. Max water depth is 10,000ft
  • 7th Generation
    • Unit constructed from 2010 onwards. Max water depth is 12,000ft

Jackup rig types

Four jackup type categories

  • High Specification
    • Water depth is 400ft+, with a hookload capacity of over 2,000kips
  • Premium
    • Water depth is 350ft+, with a hookload capacity from 0 – 1,999kips
  • Standard
    • Water depth is less than 350ft
  • Mat Cantilever/Slot
    • Any jackup that does not have an Independent Leg Cantilever (ILC) sub-type

Sub type definitions

  • Floating rigs
    • Midwater
    • Deepwater
    • Ultra-deepwater
  • Jackups
    • Independent Leg Cantilever
    • Independent Leg Slot
    • Mat Cantilever
    • Mat Slot
    • Cantilever

Floating rig water depths

  • Midwater
    • 4,000ft or less
  • Deepwater
    • 4,001- 7,499ft
  • Ultra-deepwater
    • 7,500ft and greater

Ref: http://www.infield.com/rigs/rig-glossary

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