Experimental and Numerical Study of Coupled Dynamic Response of a Mini Tension Leg Platform

Abstract

Role of mini tension leg platforms (TLP) in oil exploration and production in marginal deepwater fields is becoming increasingly important. Mini TLP combines the simplicity of a spar and favorable response features of a TLP. In this paper, the results of a detailed experimental and numerical investigation of the coupled dynamic behavior of a mini TLP are reported with special attention to hull-tether coupling. The experimental study has been carried out using a scaled model in wave flume with specially designed tethers whose first two “string” natural frequencies are excited by waves, thus achieving strong hull-tether coupling. The numerical study has been carried out using a nonlinear time domain finite element method specifically addressed to compliant offshore platforms using a combination of potential theory based wave loading and Morison-type wave loading. Extensive comparisons between numerical and experimental results have been made both for platform motions and deflected shapes of the tethers and conclusions drawn.