Assessment of Ultra Deepwater Riser Concepts for High-Motion Vessels

Abstract

The paper presents the results of the second half of a study funded by Research Partnership to Secure Energy for America (RPSEA) under project 10121-4401-02 Ultra-Deepwater Riser Concepts for High Motion Vessels. In the first half of the study, candidate riser systems consisting of alternatives to the steel catenary riser in both geometry – for the purpose of isolating the fatigue-critical riser touchdown zone from the motions of the vessel – and material were identified then down-selected to meet the constraints of high motion vessels like the conventional semi-submersible or a ship-shape floating, production, storage, and offloading vessel (FPSO). In addition to water depths approaching 10,000 feet, the present-day challenges of high pressure, high temperature, and sour well product are incorporated into the problem being framed. Results from dynamic analyses of riser concepts passing through the down-selection process are used to assess both utilization of strength capacity and fatigue performance. Comparisons of dynamic responses highlight the differences of each riser concept's behavior and provide understanding of the limitations of riser concepts. Assessments to other criteria such as cost, failure modes, and installation considerations are also used to ascertain safe riser systems that meet the performance demand of high-motion vessels.

Dynamic analysis of a hang-off drilling riser considering internal solitary wave and vessel motion

“…Sexton and Agbezuge(1976) researched the influence of both random waves and vessel motion on connected drilling risers. Head et al(2013) and Royer et al(2014) evaluated various potential concepts of a steel catenary riser for high-motion vessels operating in ultra-deepwater. analysed the out-of-plane vortex-induced vibration of a steel catenary riser caused by vessel motions and evaluated its fatigue damage.…”

Sensitivity Study on SCR Design for Spread-Moored FPSO in West Africa

“…McGrail and Lim performed a technical appraisal of hybrid riser and SCR in deep water applications and established the technical design approach (McGrail and Lim, 2004 (Yue et al, 2010). Royer and Power evaluated riser concepts for high-motion vessels(FPSO and Semi-submersible) operating in waters at up to 10,000 feet in the Gulf of Mexico (Royer and Power, 2014).…”