SemiSub Drilling Rigs

What is a semisub drilling rig?

A semi-submersible drilling rig or a semisub is a type of floating drilling rig that is partly submerged to provide station keeping and stability. It comprises a submerged hull typically pontoon-type columns joint together with the drilling platform by large tubulars. The main purpose of the semisub is to avoid large surge movements from wave by having the slender tubulars in the splash zone.

Semi-sub drilling rigs
Semisub Drilling Rig courtesy of Transocean

Rig for both Shallow and Deep Water Drilling

Semisub is a floating installation used for drilling, completion and well service on the Norwegian and international shelf. The lower structure of the rig consists of floating elements (pontoons). The pontoons have tanks that can be filled with water (ballast) so that the center of gravity of the rig becomes lower when operating on the well. This makes the rig stable in the sea. When the rig is to be moved, the ballast tanks are emptied so that it is easier to sail. This type of rig can be used on both shallow and deep water.

Wellhead Fatigue and WLR Systems

The drilling is done through the drilling riser system which is connected to the subsea blow out preventer (BOP). The BOP is connected to the subsea wellhead or xmas tree on the subsea drilling template or satellite. The fatigue loading on the wellhead can cause wellhead fatigue and a wellhead load relief system may be needed.

List of Semi-Sub Drilling Rigs

Below is a list of 10 random semis from out drilling rigs data base. Use the search function to find more.

  • Viking Producer Rig owned by Viking Drilling ASA
    The Viking Producer drilling rig is owned by Viking Drilling ASA which can be contacted for jobs and careers on the Viking Producer. The Semisub is a Semisub type of rig and is designed as a CFEM Pentagone and built by at the Cfem LE Havre France shipyard. The rig can be operated in water ...
  • Transocean Searcher Rig owned by Transocean Inc.
    The Transocean Searcher drilling rig is owned by Transocean Inc. which can be contacted for jobs and careers on the Transocean Searcher. The Semisub is a Semisub type of rig and is designed as a Trosvik Bingo 3000 and built by Kaldnes Mek Verkstad at the Tonsberg Norway shipyard. The rig can be operated ...
  • Transocean Winner Rig owned by Transocean Inc.
    The Transocean Winner drilling rig is owned by Transocean Inc. which can be contacted for jobs and careers on the Transocean Winner. The Semisub is a Semisub type of rig and is designed as a Gotaverken GVA 4000 and built by Gotaverken Arendal at the Sweden shipyard. The rig can be operated in water ...
  • Transocean John Shaw Rig owned by Transocean Inc.
    The Transocean John Shaw drilling rig is owned by Transocean Inc. which can be contacted for jobs and careers on the Transocean John Shaw. The Semisub is a Semisub type of rig and is designed as a Friede & Goldman 9500 Enhanced Pacesetter and built by Mitsui at the Japan shipyard. The rig can ...
  • Transocean Leader Rig owned by Transocean Inc.
    The Transocean Leader drilling rig is owned by Transocean Inc. which can be contacted for jobs and careers on the Transocean Leader. The Semisub is a Semisub type of rig and is designed as a Aker H-4.2 and built by Hyundai Heavy Ind. at the Hyundai Ulsan Korea shipyard. The rig can be operated ...
  • Transocean Legend Rig owned by Transocean Inc.
    The Transocean Legend drilling rig is owned by Transocean Inc. which can be contacted for jobs and careers on the Transocean Legend. The Semisub is a Semisub type of rig and is designed as a Trosvik Bingo 3000 modified and built by Nippon Kokan at the Japan shipyard. The rig can be operated in ...
  • Transocean Marianas Rig owned by Transocean Inc.
    The Transocean Marianas drilling rig is owned by Transocean Inc. which can be contacted for jobs and careers on the Transocean Marianas. The Semisub is a Semisub type of rig and is designed as a Earl & Wright/Sedco 700 Series Enhanced and built by AMFELS at the Brownsville, TX shipyard. The rig can be ...
  • Transocean Polar Pioneer Rig owned by Transocean Inc.
    The Transocean Polar Pioneer drilling rig is owned by Transocean Inc. which can be contacted for jobs and careers on the Transocean Polar Pioneer. The Semisub is a Semisub type of rig and is designed as a Hitachi Zosen HITACHI ARCTIC and built by Hitachi Zosen at the Japan shipyard. The rig can be ...
  • Transocean Prospect Rig owned by Transocean Inc.
    The Transocean Prospect drilling rig is owned by Transocean Inc. which can be contacted for jobs and careers on the Transocean Prospect. The Semisub is a Semisub type of rig and is designed as a Trosvik Bingo 3000 modified and built by Nippon Kokan at the Japan shipyard. The rig can be operated in ...
  • Transocean Rather Rig owned by Transocean Inc.
    The Transocean Rather drilling rig is owned by Transocean Inc. which can be contacted for jobs and careers on the Transocean Rather. The Semisub is a Semisub type of rig and is designed as a Gotaverken GVA 4500 Enhanced and built by Daewoo Shipbuilding at the Okpo Korea shipyard. The rig can be operated ...