Comparison Study of Different Floater Effect on Deepwater SCR

Abstract

With the development of deepwater offshore industries, Steel Catenary Riser (SCR) offers great advantages over other risers and has been widely deployed. SCRs have been installed and in service in offshore oil and gas industries in the Gulf of Mexico, Campos Basin, Brazil and West of Africa since the 1990s. The platforms designed for SCRs range from semi-submersible, Spar, TLP to FPSO. Severe motions of a floating host facility such as a TLP, FPSO or other platform may have implications for the strength and fatigue life of SCR. To better understand the effect of floater motion on deepwater SCR, a comparison study of such effect was conducted. Three typical floaters including semi-submersible, Spar and TLP were selected for comparison purpose. An identical SCR was assumed for all floaters in order to make comparison on the same basis. Study focus was given to the strength and motion fatigue analysis. To illustrate the floater effect on SCR performance, an example was given for an 8.625 inches diameter SCR. Detail finite element analysis were performed by use of ABAQUS. It was found that the floater motion has significant impact on SCR’s both strength and fatigue. Among the selected floaters, it was found that semi-submersible and Spar are much more friendly to SCR, while TLP makes SCR design more challenging. In addition, the effect of different floater concept on SCR global configuration design was also discussed. Meanwhile, the analysis technique was also discussed through this study. It is concluded that focus should be given to SCR motion fatigue and strength for different platforms.