Study on the Steel Lazy Wave Riser Configuration via a Simplified Static Model Considering Critical Sensitive Factors

Catenary risers have been broadly adopted for mass transportation between seabed and platform during offshore oil and gas production due to its characteristics such as simple construction and relative low delivery cost. However, because of the dynamic conditions in deep water, a simple steel catenary riser (SCR) is vulnerable to yielding and short fatigue life at the critical sections such as hang-off zone (HOZ) and the touch down zone (TDZ). The conventional SCRs are subjected to even more challenges for ultra-deep field developments. Therefore, many new riser system concepts have been proposed in order to solve the related stress and fatigue challenges, in which steel lazy wave catenary riser (SLWR) is the most popular one in recent years. In this work, a simplified static model and tool based on catenary theory and static equilibrium in mechanics was developed for an initial screening of SLWR configuration in the riser early design phase. According to the analysis, it is implied that each section of the SLWR is conformed to a hyperbolic function numerically. Using the configuration tool developed, a trial calculation case has been carried out assuming a water depth of 1500 m, and the critical sensitive factors including hang-off angle, elevation, and content density have been discussed respectively. The findings can provide certain reference information for the further study and detailed design in the future engineering phases.