Features of a taut leg mooring system for deep water

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:256935

Loevstad, T; Namork, J; Nilsen, A U ^[1]

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1. Norsk Hydro, Bergen (Norway)

As oil exploration and production is moving into greater water depths there is a need for cost effective stationkeeping systems. To date all floating production units have used conventional catenary mooring systems consisting of chain or a chain/wire combination. For greater water depths the use of a catenary mooring system (CMS) will result in very long lines and a large additional vertical load on the platform. The objective of the present work has been to develop cost effective stationkeeping systems for floating production units in 500--1,500 m water depth. The work is based on a case study of a large steel floater (semi). A conceptual design of a taut mooring system (TMS) has been developed. This investigation has focused on the dynamic behavior of the TMS in order to document acceptable dynamic performance. A taut mooring system based on a polyester fiber rope offers an alternative. For a water depth of 1,200 m the line length is reduced from 3,100 m to 2,030 m and the footprint is reduced from 2,800 m to 1,700 m by using a taut mooring system instead of a catenary system. In addition, a taut mooring system using polyester ropes is significantly more cost effective than a conventional catenary mooring system at large water depths. As an overall conclusion the investigation has confirmed satisfactory behavior of the proposed TMS concept.

• OSTI ID: 256935
• Report Number(s): CONF-950604--; ISBN 1-880653-17-6
• Country of Publication: United States
• Language: English

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