Newer Frontiers in the Design of Steel Catenary Risers for Floating Production Systems

Abstract

It is not uncommon nowadays to have a new floating production facility installed with steel catenary risers (SCRs) as the main method for receiving and exporting fluids. The use of steel catenary in deeper and shallower waters alike where it was challenging and even unthinkable some years back is now feasible. Advancements in the SCR technology cover not only design and software, but also manufacturing, installation methods and capabilities. Since the first author’s OMAE 2001 paper “New Frontiers in the Design of Steel Catenary Risers for Floating Production Systems” [1] was published, a number of significant advances have been made in the design, manufacture and installation of steel catenary risers. In design aspects for example, the soil structure interaction and modeling of soil stiffness and trench formation has been the topic of many publications and research. The manufacturing capabilities of the pipe mills to produce and machine SCR pipe joints with upset ends has been advanced and implemented in recent projects. Advancement in the capability of Automated Ultrasonic Testing (AUT) systems to detect very small flaws in thick carbon steel and clad pipe welds is expanding the manufacturing envelop of SCRs while meeting design requirements. In addition, there is improvement in the capabilities of installation vessels; and more comprehensive material and fatigue test data have been accumulated providing data better basis to design and perform fracture mechanics analysis of SCRs. Lazy wave SCR configurations are being used to significantly expand the application of SCR technology to high motion vessels and more severe environments. This paper contains a review of the current state of the art with a description of some of the important advancements that have extended the range of applicability of SCR technology. The SCR technology advancements presented and discussed in this paper include a better understanding of the soil behavior and trench formation with some analytical results, the use of upset ends and their manufacturing options, improvement in the AUT systems and flaw detection capabilities, CRA clad SCRs and Lazy Wave SCRs.