ABSTRACT

• Suction piles or suction anchors were first introduced some 20 years ago. But, it was only after further research and development in late 80's and early 90's that the widespread use in mooring applications for floating production units took place. Today, less than 10 years after this research, their position and application are significant in the offshore oil industry world-wide. Their preference in major offshore development areas like Brazil, West Africa, North Sea, Norwegian Sea, West of Shetland and the Gulf of Mexico where reliable high capacity foundations for catenaries and taut legged moorings are required is well known. Key factors which have influenced their selection as a preferred foundation include:

  • Reliable design methods both for installation and in service behaviour

  • Predictable installation behaviour

  • Redundancy, i.e. installation may be reversed and repeated

  • Cost efficiency

  • Removal is easy if planned for Suction pile technology has been applied for a great variety of fixed and floating offshore structures and proved to be extremely adaptable to soil conditions, structural requirements and type and magnitude of loading.

The suction pile used in mooring application is a flexible foundation solution: Geometry and aspect ratio (length to diameter ratio) can vary significantly. Installation methods likewise can vary similarly and the anchors may be fabricated at a great variety of construction yards. Design methods used to date are based on general soil mechanics and soil modeling. General rules and regulations are not specifically reflecting this new foundation technique although some codes (e.g. NS 3481) have made certification or authority approval easier and as such, contributed to the rapid growth of this foundation solution. Work is now progressing within API to establish the state of the practice in design of deep water anchors.

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