Dark Roasted Blend: The Ultimate Moving: Troll-A Gas Platform

"QUANTUM SHOT" #658
Link - article by Avi Abrams


      The biggest man-made object ever towed

      

      Immense Troll Tower to Move & Conquer! No it's not something from the
      "World of Warcraft", it's an offshore oil rig, but a mind-numbingly huge
      one - in 1996 the Troll A platform set the Guinness World Record for
      'largest offshore gas platform'. 
      
      It stands almost 500 meters tall and weighs 656,000 tons - it's one of the
      biggest man-made objects ever towed (it has now been dwarfed by
      Texaco's Petronius platform which is "arguably" the tallest structure in
      the world.)

      
      

      Bigger than any aircraft carrier, higher than most TV towers, this vessel
      asks for a titanic team of ships to tow it to another location - and
      imagine splash this thing would make if it toppled!

      
      
      

      At 1.2 million ton ballasted under tow, 472 meters high, with underwater
      concrete structure at 369 meters, and dry weight: 656,000 tons... Not many
      people realize how tall these things really are. 
      
      Here's a comparison with the Eiffel Tower:

      

      Also compare the height of some other oil platforms with the world's
      tallest buildings ("Troll A" is not in the picture, but it has overall
      height of 472 meters):

      
      (image via)

      I can just see Steven Seagal bossing around this rig, with Charles Bronson
      supervising a move (or the other way around) - either way, you can better
      grasp the immensity and power of this event!

      
      (another platform being towed in the North Sea - more
        info, photo via StatOil)

      Towing an iceberg away from the oil platform is a... beautiful task:

      
      (photo by Randy Olson,
        National Geographic)

      -------

      The Troll Giants (Sucking the Oil Out)

      Troll-A is not the only one (more
      info). There are a few big gas platforms in the North Sea Troll oil field -
      yes, you guessed right, "B" and "c":

      
      (photos:
        Eilif Stene
        / Statoil)

      And here is the Mighty "Troll-A" itself:

      
      
      
      (images credit: StatOil)

      The Goldeneye Gas Platform in the North Sea Northern, United Kingdom,
      looks puny compared with the 500-meter height of the "Troll A" (right):

      
      (images via)

      This is looking up from inside the platform's column:

      
      (image credit: StatOil)

      Moving this platform was comparable only to building it (the construction
      of the Troll A was considered to be the greatest engineering achievement
      of the century at the end of 1999). The immensity of construction is
      clearly seen in this photo: those are huge ships down there, not boats!

      
      
      (images via 1,
        2)

      The way the Troll-A platform was installed and moved, is amazing in
      itself. Normally a platform's legs are transported on their side and then
      - supported by flotation devices - are dropped into place (sunk under the
      waves). This time though, the whole platform was assembled in one
      location, and then floated out!

      
      (images via)

      Here are a couple of photos to give you an idea how huge these platforms
      really are - looking inside the "StatOil" rig over 1.5 kilometers west of
      the Sleipner West in the North Sea:

      
      
      
      (images credit: StatOil)

      Here is "Nortrym" platform in Statfjord - in fact, one of many! Look at
      the bottom right image for location of these units:

      
      
      (images via)

      
      
      ("Deepsea Trym" drilling rig by Nortrym - photo by Chiefen,
        via)

      The Ekofisk oil and gas field development complex is 200 miles from
      Norway:

      
      (images via 1,
        2)

      ------

      Big Oil Platforms Encounter Huge Waves

      You've seen encounters of tankers and passenger ships with waves -
      Ships vs. Big Waves. But huge oil rigs routinely endure heavy seas and sometime suffer
      serious wave damage, especially those that are anchored to one place and
      can't be towed away from approaching storms easily. Here are some images
      to give you an idea:

      

      The "Borgila" and "Nortrym" oil platforms are among many threatened by
      extreme storms, hurricanes (in the vicinity of the US) and the possibility
      of fires and oil leaks:

      
      
      (images via
        1,
        2)

      The recent oil spill disaster caused many people to re-examine the safety
      record of gas platforms:

      The offshore oil platform 'Gullfaks C' stands up to a fierce, North Sea
      storm (with 7 meter high waves):

      

      A rogue wave model was created to test oil platforms (more
      info
      and a
      video
      of a monster wave):

      
      (image
        via)

      And finally - here is our "Troll A" giant platform valiantly enduring some
      good-sized waves: hopefully nothing more extreme than this -

      
      (image via)

      Watch the long video about this platform and how it was moved -
      click here.

      READ THE WHOLE SERIES HERE ->

      Also Read:
      Transporting Space Shuttles
      Wind Power in Stormy Waters

5 Comments:

Sunduvan said...: Ohh wow. Impressive oil rig photos. How do they tow the oil rig? Aren't connected to the ground?; ___
Anonymous said...: You seem to have forgotten to talk about the ingenious construction of "Slip forming" of the concrete legs themselves-- (From Wikipedia):

The platform stands on the sea floor 303 metres (994 feet) below the surface of the sea and each of the continuous-slip-formed concrete cylindrical legs has an elevator that takes over nine minutes to travel from the platform above the waves to the sea floor. The walls of Troll A's legs are over 1 metre thick made of steel reinforced concrete formed in one continuous pour -"Slip forming) and each is a mathematically joined composite of several conical cylinders that flares out smoothly to greater diameters at both the top and bottom, so each support is somewhat wasp-waisted viewed in profile and circular in any cross-section. The concrete legs must be able to withstand intense pressure so are built using a continuous flow of concrete, a lengthy process that takes 20 minutes per 5 cm laid.

The four legs are joined by a "Chord shortener", a reinforced concrete box interconnecting the legs, but which has the designed function of damping out unwanted potentially destructive wave-leg resonances by retuning the leg natural frequencies. Each leg is also sub-divided along its length into compartments a third of the way from each end which act as independent water-tight compartments. The legs use groups of six 40 m vacuum-anchors holding it fixed in the muck of the sea floor.; ___
Stomatoloq said...: Baku, Azerbaijan
and
Caspian Sea; ___
Anonymous said...: They have huge chains for towing (I think). I'm not quite sure myself how it moves over the seabed, but the "pods" you see at the bottom in the Eiffel tower comparison are basically suction cups. They open up valves on the top and let the structure sink into the murky seabed. Then they close off the valves which will anchor the structure to the ground (try to lift it and a vacuum will be generated, sucking it to the floor).

The band that is halfway up the legs is specifically tailored to change the resonance frequency of the platform. This is to prevent the platform from "breaking" due to the frequency generated by wave action (resonance is what causes bridges to "flail" about violently; in that case due to wind action).

I was actually offshore in September doing commissioning work on the Gjøa platform (the semi-submersible with green legs), and this summer I enjoyed 10 days of warm weather on a boat laying in between Statfjord A and B some hundred meters away :) will hopefully get to visit Troll A and the other massive condeeps later on as well (I'm a rookie petroleum engineer from Norway ;)

The "3 meter waves" has got to be a typo :P that's probably somewhere in between 10-15 meters. 4-5 meter waves is common during the autumn and winter.

At New Years Eve 1995 a freak wave of 25.6 meters (84 ft!)/significant wave height ~18.5 m, hit the Draupner field. I can't even imagine seeing that. (http://en.wikipedia.org/wiki/Draupner_wave)

Thanks for a nice article.; ___
Pie said...: @Sunduvan:

Note that in the photos where they're moving her, she towers over the ships around her. Compare that to the photos where she's in place - when she's being moved, she's multiple hundred feet taller. I suspect that she has ballast tanks in those huge legs - when they're full of air, she floats high and can be towed about, but when they're flooded, she sinks until she comes to rest on the bottom.; ___

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