Dry Tree Top Tensioned Riser Systems

Abstract

Abstract As oil production moves further offshore and into deeper water, the technology needed to meet the increased demands evolves. New technologies and new applications of existing technologies bring new challenges and often create unintended consequences. For floating production vessels, the riser system is critical to the safety of personnel and protection of the environment. However, there is no universal riser package suitable for every project. The riser system must be designed not only for the environmental loads, but also the specific and unique demands of the vessel. Project engineers responsible for selecting the best solution for developing a field must maintain a holistic view. The decision of the type of production vessel should be based not only on leading interfaces such as location and environment, but also consider trailing interfaces such as the hardware used on the vessel. This paper outlines the impact that production vessel type has on top tension riser (TTR) systems. Tension leg platforms (TLPs), spars, and semi-submersibles are considered. Design requirements, functions, interfaces, and standard componetry of TTRs are identified. Case studies of riser packages for various vessel types are presented for illustration. Effects on cost, complexity, installation, and ancillary equipment are documented. Future projections and trends are included. Introduction Brazil is a major and growing market for offshore oilfield development. As of August 2012, more floating production projects were planned in Brazil than any other country. With that growth comes an expansion of technology and a diversity of solutions to meet the evolving needs of the marketplace. Upon its planned completion, Papa Terra will be the first dry tree offshore development in Brazil. Given the advantages of dry tree systems in the flexibility for drilling, completion, and workover, many more can be expected in the coming years. Due to the lack of prior dry tree projects in Brazil, many engineers, project managers, and other decision-makers lack exposure to and experience with these systems. This paper provides general information about floating production systems and their corresponding top tension riser systems. Other components and riser types, such as pipelines and steel catenary risers, are not addressed.