Designing feasible Steel Catenary Risers (SCRs) for semisubmersible and FPSO host platforms is a challenge in certain geographic locations and water depths. An alternative application gaining acceptance is Steel Lazy Wave Risers (SLWRs), which are an adaptation of conventional SCRs with distributed buoyancy modules. While this alternative solves strength and fatigue issues of SCRs, the addition of buoyancy modules increase installation complexity and costs. Therefore, designing an SLWR with minimum buoyancy is imperative. Several parameters affect the performance of an SLWR include location of buoyancy, length of buoyancy sections, discrete versus continuous modules and distance above seabed for several operating conditions. Buoyancy modules are also limited by size, water depth and installation considerations. Vortex Induced Vibrations (VIV) fatigue damage to buoyancy sections has to be assessed as well. This paper will present an optimization method for estimating minimum buoyancy requirements for SLWRs based on design constraints such as maximum stress, effective tension and curvature along the pipe. It will also address an automation tool that can accelerate the optimization cycle and eliminate uncertainties associated with a conventional trial-and-error approach.
展开▼
