The paper deals with the numerical modelling of the fully coupled behaviour of rigid risers and floaters in deep water. After a brief review of the main risers / floater configurations proposed for production in deep water, uncoupled models used for the dynamic analysis of risers and floaters are described. Details are given on their theoretical bases. Based on these models, a new numerical model DEEPLINES, performing the fully coupled dynamic analysis both in frequency domain and in time domain, was developed. The model includes 1st and 2nd order wave loads on the floaters, hydrostatic restoring loads, drag loads on the hull, mooring lines and risers, static and dynamic structural response of the risers and mooring lines. A typical application to a TLP in deep water is described in the last part of the paper.
The gas and oil production in very deep waters is a major challenge for the offshore architect. New concepts are based on multi-structures systems including floaters and complex mooring and risers systems. However in deep water the large number of lines and risers can induce the main contribution to the hydrodynamic loads on the FPS. Then the hydrodynamic analysis of such concepts requires methods taking into account the coupling effects between the floater and the rigid risers and mooring lines. Typical riser configurations in deep water A large variety of floaters can be used, depending on the field conditions: FPSO on SPM, turret or spread mooring, TLP, deep draft floater (spar and emis). For drilling or offloading operations, floaters motions can interact. The same phenomenon may occur for risers configurations which can include taut rigid risers, catenary steel risers, flexible risers (catenary, lazy wave, lazy s, …), hybrid risers.
