physics

Troll A platform

Troll A platform is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Troll A platform rather than just read about it. In short: The Troll A platform is a Condeep gravity-based structure offshore natural gas platform in the Troll gas field off the west coast of Norway. Built from reinforced concrete, as of 2014, it was the tallest structure that has ever been moved to another position, relative to the surface of the Earth, and is among the largest and most complex engineering projects in history.

Key takeaways

Troll A platform belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Troll A platform to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Troll A platform from memory before moving on to harder problems.

Reference excerpt

The Troll A platform is a Condeep gravity-based structure offshore natural gas platform in the Troll gas field off the west coast of Norway. Built from reinforced concrete, as of 2014, it was the tallest structure that has ever been moved to another position, relative to the surface of the Earth, and is among the largest and most complex engineering projects in history. The platform was a televised sensation when it was towed into the North Sea in 1995, where it is now operated by Equinor. It is also the heaviest object moved and the object with the second highest displacement at 1.2 million tons (the object with the highest displacement is the Gullfaks C, which had a displacement approaching 1.5 million tons). Troll A was towed from the afternoon 10 May 1995 until the platform was in place 17 May 1995. It was lowered to the seabed in 303 meters of water, and had penetrated 36 meters into the soil by 19 May 1995. It was self-supporting with no further mooring required.

Dimensions

The Troll A platform has an overall height of 472 metres (1,549 ft), weighs 683,600 tons (1.2 million tons with ballast) and has the distinction of being the tallest structure ever moved by mankind. The platform stands on four legs extending down to the sea floor 303 meters (994 feet) below the surface of the sea, and the leg containing the import and export risers has an elevator that takes over nine minutes to travel from the platform above the waves to the sea floor. The legs must be able to withstand intense pressures, so the walls of Troll A's legs are over 1 metre thick and are made of steel-reinforced concrete that was formed in one continuous pour – a lengthy process that takes 20 minutes per 5 cm laid. Each leg is a mathematically joined composite of several conical cylinders that flares out smoothly to greater diameters at the top and bottom, so each support is somewhat wasp-waisted when viewed in profile and circular in any cross-section (see picture at right). The four legs are joined by a "chord shortener" (not present in the picture at right), a reinforced concrete box connecting the legs that damps out any potentially destructive wave-leg resonances by retuning the legs' 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 metres (130 ft) tall vacuum-anchors holding them fixed in the mud of the sea floor.

Construction Troll A was built by Norwegian Contractors for Norske Shell, with base construction beginning in September 1991 at a cost of 4150 million NOK, or approximately US$650 million at the time. The base and the deck were built separately, and were joined in 1998 while the base was partially submerged. The base is a Condeep gravity base structure built from reinforced concrete. The Troll platform was towed over 200 kilometres (120 mi) from Vats, in the northern part of Rogaland, to the Troll field, 80 kilometres (50 mi) north-west of Bergen. The tow took seven days.

Expansion In the autumn of 2010, the Troll A platform was expanded with a new module. This module contains living quarters and a new control room. The new control room and expanded facilities are needed to support new compressors. These compressors are needed due to the dropping reservoir pressure in the wells. On the 18th of June, 2013, the new support module "M12" for compressors 3 and 4 was lifted on board of Troll A. The increased electricity consumption of these compressors required new power cables from shore, and due to grid constraints, the platform is cut off from shore power if a grid emergency arises.

Operation Gas rises from 40 wells and is exported through a number of pipes to a processing plant at Kollsnes. Troll A is scheduled to receive two additional gas compressors to increase production volume and compensate for dropping reservoir pressure in the wells.

World records In 1996, the platform set the Guinness World Record for the largest offshore gas platform. In 2006, the 10th anniversary of Statoil's operatorship of Troll gas production was celebrated with a concert by Katie Melua held at the base of one of the hollow legs of the platform. The concert set a new world record for the deepest underwater concert, at 303 metres (994 ft) below sea level.

Illustrations

Worked examples

Example 1 — a first encounter with Troll A platform

Start with the simplest possible case. Write down what Troll A platform claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Troll A platform before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Troll A platform ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Troll A platform

In research: Troll A platform appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Troll A platform in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Troll A platform is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1996 establishments in Norway, Equinor, Natural gas industry in Norway, so understanding it makes those chapters shorter.
In everyday life: Look for Troll A platform outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Troll A platform in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Troll A platform means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Troll A platform out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Troll A platform in simple terms?

Why does Troll A platform matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Troll A platform?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Troll A platform.