Foundations for floating production systems in deep water are designed using methods adopted from those used for jacket platforms in shallow water. While significant efforts have been undertaken to quantify and understand the reliability of pile foundations for jackets, comparatively little effort has been made to do the same for foundations in floating production systems. In this paper, a reliability analysis is conducted for a study spar that is representative of existing technology and design practice in the Gulf of Mexico. Biases and uncertainties that are inherent in the design loads and capacities are addressed. The effect of a lower-bound value on the foundation capacity is considered. Finally, the reliability for the foundation in the study spar is compared with that for a pile foundation in a typical jacket platform and with an industry-recommended target level for mooring systems. The major conclusions are (1) foundation designs for floating production systems may be excessively conservative; and (2) a lower-bound or minimum available foundation capacity can have a significant effect on the reliability and is useful design input.
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