Optimization of complex configuration of catenary risers buoyancy modules

Risers are pipes that conduct oil and gas from the subsea wellhead to the floating production unit. For such structures, the pre-sizing approach is usually based on a trial-and-error methodology, fairly dependent on the designer’s experience. The use of catenary risers in complex configuration brings the advantage of overcoming the challenges imposed by deep-water fields for oil exploitation. On the other hand, pre-sizing complexity increases as new design variables are added to define the geometrical parameters of the buoyancy modules attached to a riser intermediary segment. This work presents the pre-sizing approach of catenary risers in complex configuration using optimization techniques for the definition of the riser static equilibrium configuration. Thus, the optimization problem is numerically represented and formulated resulting in a computational application that couples the framework DOOLINES, a simulator for the static and dynamic analysis of mooring lines and risers, with the MATLAB® optimization toolbox, for managing this process, applying a hybrid method, starting with the application of Genetic Algorithms followed by the Sequential Quadratic Programming. A case study is presented and discussed to demonstrate the functionality of this applicative that produces the optimal result according to an objective performance measure.