The Tension Leg Platform: from Hutton to Big Foot

Abstract

This paper is one of seven papers that will be included in the special session: Floating Memories – Look Back to Leap Forward. The focus for this paper is on the Tension Leg Platform (TLP), one of the four major platform types that include the Floating Production Storage and Offloading platform (FPSO), the semisubmersible floating production system (Semi) and the Spar platform. The paper summarizes the evolution of the TLP over three and half decades, and provides a thirty-five year retrospective of the progression of TLP technology, including hull shapes, tendon connectors, flex elements, and riser systems. It will walk through the evolution of understanding, analytical methods, and model testing to assess the complex global performance of a TLP, and the unique challenges of system dynamic resonant excitation, the so-called "ringing" and "springing" phenomena. The TLP was a game-changer in bringing dry tree wells to floating platforms, leveraging dry tree drilling and well control methods from a generation of fixed platforms, and enabling multiple top- tensioned production and drilling risers in close proximity due to the limited tensioner stroke not possible on a drill ship or semisubmersible. The TLP has shown its applicability in water depths from the Hutton TLP (1982) in barely 150 m of water in the North Sea, to the Big Foot TLP installed in 1584 m of water in the Gulf of Mexico in 2018, the deepest TLP to date. And it has shown its flexibility in size ranging from the smallest mini-TLP's of 10,000 tonnes displacement, to the North Sea concrete hulled Heidrun TLP of 290,000 tonnes.