As one of the field proven riser concepts, tower riser is a popular concept in particular for deepwater application in the West of Africa (WoA). This paper addresses on the design exercise of a deepwater tower riser in WoA. A brief presentation of deepwater hybrid riser history and evaluation is given first. Secondly, design basis for the tower riser study is described. Thirdly, design of the tower riser has been focused on including logistical design procedure, major design issues, and critical factors affecting the design, global configuration design, connection design, and local component design. To verify the design and to provide input for local component sizing, global analysis was performed and results were presented as the fourth part of this paper using riser tool and ABAQUS. Lastly, conclusions are drawn from this study and recommendations are made.
In recent years, exploration and production activities have increased dramatically in deep and ultra-deep water. The targeted water depths for oil and gas developments in areas such as the Gulf of Mexico (GoM), West of Africa (WoA), and Brazil are increasing every year.
As one of the key elements in offshore infrastructure, deepwater riser technology plays an important role in offshore development. Among the field proven riser concepts, which include steel catenary risers (SCRs), top tension risers (TTRs), flexible risers (FRs), and hybrid risers (HRs) as shown in Figure 1-1, hybrid risers offer unique advantages over other concepts for specific applications and requirements. Even though hybrid riser concept initiated and started in the GoM, its popularity in deepwater development starts in the WoA with the deployment of the Girassol tower riser followed by Kizomba single line hybrid riser, Greater Plutonio tower riser, etc.
