Optimization of composite catenary risers

Abstract

The use of composite risers may offer important advantages over the use of conventional steel risers in deepwater oil fields. However, the design of laminated composite risers is much more complex than the design of steel risers, due to the large number of parameters that need to be chosen to define the riser layup. This work presents a methodology for optimum design of composite catenary risers, where the objective is the minimization of crosssectional area of the riser and the design variables are the thickness and fiber orientation of each layer of the composite tube. Strength and stability constraints are included in the optimization model and multiple load cases are considered. The methodology can handle both continuous and discrete variables. Gradient-based and genetic algorithms are used in the computer implementation. The proposed methodology is applied to the optimization of composite catenary risers with different water depths, liner materials, and failure criteria. The numerical examples show that the proposed methodology is very robust.