Analytical approach for the establishment of critical length criterion for the safe and economical design of the flexible jumper in deepwater applications

The Hybrid Riser (HR) configurations based on flexible jumpers connected to a submerged buoy offer certain unique advantages over other field proven riser concepts in deepwater, and have been used successfully in industry. In particular, flexible jumpers can effectively isolate the dynamic Floating Production Unit (FPU) motions, and thus in place riser fatigue is minimized. This paper focuses on the flexible jumper issue, and aims to propose a highly effective analytical approach for setting its critical length criterion (CLC). The critical length is defined as the minimum length that can maintain the equilibrium between the de-coupled property and economics of the flexible jumper. Furthermore, the analytical approach is verified by numerical parametric studies for the flexible jumper of a Single Line Offset Riser (SLOR). The results demonstrate that there exists a CLC for the safe as well as economical design of the flexible jumper. Therefore, the usual design approach employed for the flexible jumper is not completely adequate, and should be complemented by alternative approaches. A new practical design method of flexible jumpers can be developed following the CLC presented here.