The Evolution of Free Standing Risers

Deepwater riser selection is a complex evaluation of technical and commercial project drivers. The free standing hybrid riser (FSHR) has evolved in the last 10 years through major use in West Africa and is now gaining serious consideration in other deepwater provinces. The key benefit of the free standing riser is that the steel riser vertical section is offset from the vessel using flexible jumpers, thereby decoupling the riser from vessel dynamic motion. Early FSHR configuration took the hybrid bundle tower form. The very first free standing riser system, installed in 1988, consisted of the Placid hybrid bundle in the Gulf of Mexico. In the late nineties, a hybrid bundle tower was chosen for the Girassol development in West Africa. Since then, the industry has sanctioned numerous developments using multiple single line freestanding risers. Optimization of the FSHR is continuing with new concepts such as the Grouped SLOR developed to offer the combined benefits of both the bundle and single line multiple arrangements. This paper will describe how the FSHR configuration has evolved to meet increasing industry demands over the past 10 years and will discuss the future of this type of riser system. Increasing applications in ultra deepwater regions, hurricane prone locations and tiebacks to existing payload limited production vessels will be discussed with riser system architecture described including interfaces with the vessel and seabed.