The areas north of the Arctic Circle 66.56 degree North Latitude have significant potential for oil and gas accumulations. This paper presents a state of the art production, drilling and storage facility support circular FPSO structure for the round the year operation for arctic offshore areas in the presence of permanent sea ice and oceanic deeper water depth. The paper addresses the cutting-edge technologies and innovative method to resist the ice sheets and ridges load. Extensive analytical and experimental studies had been conducted to evaluate the applicability of the concept structure for the typical extreme ice and wave loads of the arctic condition and the results are presented. The engineering analyses studied show that the new circular FPSO is meets the arctic class requirement for the round the year operation with self ice braking and station keeping feasibility and is also viable for applications.
Circular FPSO for Arctic Deepwater is a high specification to operate, stand by and survive round the year in the arctic during summer and winter storm in water depths of 150 m and above. A self and inherent ice breaking capability is in built in the design of this circular FPSO. It is assumed that influence of an iceberg impacts on the circular FPSO is prevented, or managed or with least impact consequences by disconnecting the risers and mooring system with the help of the turret. The vessel is primarily designed to break ice sheets and ice floes continuously and thus reduces the ice forces on the vessel. The vessel could resist the kinetic energy of the drifting smaller ice bergs by means of the potential energy in mooring line tensioning and by rotating the circular vessel. Arctic developments are by far real challenges with their environment and the state of conditions.
Russia's Gazprom and Rosneft oil companies want to develop the Shtokman gas field in the Barents Sea and the Sakhalin V oil field, respectively. They both are severe arctic conditions during peak winter. Ice as thick as 1-2m may have a speed over 1 m/s with ridges as deep as 25m. In Barents Sea, severe ice bergs may pass through during in-between seasons. The present vessel is designed and shaped for these worst ice conditions in the deep arctic-ocean. Moreover, the Barents Sea with ice environment everywhere around does not have natural light in most days of the year and is generally dark. A round the year drilling and production needs a reliable and risk free vessel to operate in these fields. The non-ship-shaped FPSO is designed with the aim of being self-sufficient in ice breaking capability without the need of significant ice management. The initial design requirement set for this vessel is a severe arctic environment with water depth ranging from 120m to 500m. The lower limit of water depth is determined by the turret mooring system and its ability to disconnect and connect to the vessel.