Abstract: Today’s oil and gas industry is facing deeper waters and harsher environmental conditions. Offshore platforms and marine risers, as the main parts of this industry, have many challenges and design issues. Steel Catenary Riser (SCR) connected to Floating, Production, Storage, and Offloading unit (FPSO), is a preferred and commonly used solution to the challenges. It is needed to have more understandings of SCR behavior. So in this study, the significance of SCR-seabed interaction is investigated. Also, the effect of seabed stiffness on the structural behavior of the SCR is studied. Results show that the seabed stiffness makes considerable differences in dynamic and fatigue responses of SCRs in the touch down zone (TDZ) and reveal the importance of proper seabed stiffness modeling. Model (I), which represents weak soils with very low stiffness, could resist on continuously applied harsh environmental condition for 139.6 days. Model (IV) which represents a very stiff seabed, had a minimum fatigue life of about 6.5 percent of the model (I). The results indicated that the SCR responses were highly separated in terms of fatigue performance especially for weak to normal soils.
Keywords: Riser, seabed, fatigue, random waves, soil stiffness
