ABSTRACT

Since 2001, suction piles have been used extensively in the Gulf of Guinea, notably at several deepwater oil fields operated byTotal offshoreAngola and Congo.At these sites, suction piles were installed for the moorings of two large FPSOs and off-loading buoys, one FPU, four riser towers, and a number of manifolds. With several more applications to come, the lessons learned may have some implications for future design studies. In particular, when considering the minimum consolidation time required between installation and hook-up or loading of suction piles with significant pull-out loading component (forTLM moorings, or for riser tower anchors under constant tension, for example), the pile shaft friction resistance and its increase with time are key design issues. The topic of the paper is the increase in pile friction resistance with time (“set-up” due to thixotropy and/or consolidation after installation) in soft deepwater West Africa clays, as determined from field extraction testing of suction piles at various set-up times ranging from one day to 3 ½ years.