The setdown phase of the installation of a gravity platform requires a careful analysis of each step involoved to prevent any damage to the structure. To do this, it is important to include all the significant forces, including the tensions in the moorning lines, in a setdown simulation. In this article, the setdown of a conical gravity platform is simulated when temporary mooring lines that assist the setdown are fully accounted for. Thesetdown is achieved by ballasting the tanks in the platform according to a sequence controlled basically by the stability of the platform. as well as by its final location. A theory is developed to account for all the exact hydrostatic and ballasting forces, as well as the tensions in the moorning lines, which are catenary. Based on this theory, an interactive microcomputer program is developed to instantly minitor, report, and take actionto correct any undesirable movements of the platform that may lead to negative metacentric height. The numerical scheme devised is applied to a conical platform to analyze its real-time behavior duriung the setdown process. The effect of catenary mooring lines on the setdown prpcess is shown bycomparing the stability parameters with and without the moorning lines. Also different ballasting sequences are shown to have a significant effect on the safety of the platform.
Setdown of a catenary-moored gravity platform
Absetzen einer mit Ketten festgemachten Schwerkraftplattform
Marine Structures ; 9 , 7 ; 721-742
1996
22 Seiten, 11 Bilder, 9 Quellen
Article (Journal)
English
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