The Troll A platform was towed into the North Sea in 1995. Its enormous concrete gravity-based structure was moved from a Norwegian fjord to the offshore Troll gas field in one of the most spectacular engineering operations in petroleum history.
Troll A was built for the Troll gas field off Norway’s west coast. Norwegian Contractors constructed its reinforced-concrete Condeep base, while the deck and base were assembled separately. The platform was towed more than 200 kilometres from Vats in Rogaland toward the field, which lies northwest of Bergen.
The tow began on May 10, 1995, and the platform reached its position on May 17, taking seven days. It was then lowered onto the seabed in about 303 metres of water. The structure stands 472 metres tall overall, with long concrete legs extending from the deck to the sea floor.
Troll A is often confused with later expansion or commissioning dates. The key date in the question is the offshore tow, not the later joining of the deck and base or subsequent compressor upgrades. Equinor operates the platform today, and gas from numerous wells is sent through pipelines to the Kollsnes processing plant.