Catenary Equations for Top Tension Riser Systems

摘要

Top Tension Riser Systems provide direct access to subsea wellheadsrnfrom the floating platforms for workover;;completion;;and drillingrnoperations. This class of riser systems is widely used in a number ofrndeepwater field developments with different floating platforms. The toprntensioned risers are tensioned by buoyancy can riser tensioning systemsrnwhich have minimum interaction with the floater or by hydraulicrntensioners directly attached to the floater.rnThis paper presents a unique closed-form analytical formulation torndescribe the catenary shape of the top tension riser system as a functionrnof top tension and motions of the floating platform. The formulation isrnsuitable for determining the relationships among the riser weight;;riserrntension;;riser stroke with respect to hull;;riser seabed angle;;riserrndeparture angle;;and platform offset;;heave;;and pitch motions. Therndeveloped formulation quantifies the complex interplay among thesernkey design variables;;identifies the controlling design variables;;andrnallows the designer to improve riser system design.rnThe developed catenary equations form the basis for a systematicrndesign methodology for top tension riser systems.