The Greater Plutonio Riser Tower is installed in Angolain a Water depth of 1310 meters (4300 feet), andgathers 11 risers (two production loops, three waterinjection, one gas injection and three gas lift lines) andone gas lift umbilical. The total mass of this uniqueriser system is more than 4000 tons.This paper aims at describing the main challengesassociated to the Riser Tower design.After a description of the riser tower main elements(flexible jumpers, buoyancy tank, guiding frameswelded to the core pipe, gas lift manifolds...),numerical analyses are presented (in place extremeand fatigue analyses). Assessment of the frictiondeveloped by the risers against the guiding frames andassociated effects on the global behaviour of the risertower are detailed.Various sources of conservatism, lessons learned andways of improvements are also shared for futureprojects.
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