OTC 21857--Cascade Chinook Subsea Development: The World's Deepest Production Risers

摘要

Located in 8,200 feet water depth, the Cascade & Chinook subsea development risers are the deepest production risers in the world. These are also the first offset free-standing hybrid risers to be installed in the Gulf of Mexico, and the world’s first use of hybrid risers in combination with a disconnectable turret-moored FPSO. This paper presents the unique benefits and challenges associated with using hybrid riser tower technology in the deepwater Gulf of Mexico, based on the experience gained by both client and contractor in executing the Cascade & Chinook riser project. The authors review the history of the Cascade & Chinook riser system, from concept selection through engineering, procurement, construction, installation and pre-commissioning. The most significant challenges and the key project management decisions are highlighted, covering: field layout considerations; strength and fatigue performance; design verification; interfaces with the production facility and subsea infrastructure; procurement and fabrication logistics, and spare materials philosophy; installation engineering and execution; safety and quality management; and regulatory compliance. The project management strategy, and the relationship between client and contractor through the project life cycle, are presented and critically assessed. The paper concludes with an evaluation of the delivery time, cost and project execution risks associated with the hybrid riser concept, and compares this with more traditional deepwater riser solutions, in the context of a deepwater Gulf of Mexico development.