Tubular Connection Assembly for Improved Fatigue Performance of Metallic Risers

Abstract

Fatigue is a primary challenge in the design of steel catenary risers (SCRs) and different measures and methods are utilized to mitigate it. Traditional upset ends and steel lazy wave risers (SLWRs) are such methods to mitigate fatigue. SLWRs were first used in 2009 on the Espirito Santo floating, production, storage, and offloading (FPSO) vessel of Shell Company’s Parque das Conchas (BC-10) project offshore Brazil. SLWRs have been used increasingly since then and gained popularity especially in recent years. A novel patented tubular connection assembly is presented herein which improves the fatigue life of SCRs and welded connections in general. This novel tubular connection assembly has many advantages. It overcomes the thickness limitation of welding traditional upset ends and reduces offshore welding time, cost, and risk. When used in simple SCRs, this novel tubular connection assembly renders simple SCRs an alternative robustly viable at significantly lower cost, shorter schedule, and many additional advantages as compared to SLWRs. Of such many advantages, simple SCRs are simpler to configure, analyze, design, and install using wider installation methods and vessels. They also use less material and offer better short- and long-term integrity especially for insulated SCRs. In addition, they have smaller footprint and are less prone to clashing.