This paper introduces a potential novel concept for glacial ice management. The concept involves the capability of a platform and its riser and mooring systems to shift for a relatively large distance—hence the ‘sidestep’ term—in order to bypass the glacial ice. However, in order for the platform to be able to sidestep, the platform needs to be equipped with features which support the large distance movement.
For floating platforms like semi-submersibles, the sidestep movement may be accomplished by varying the tension rate of the mooring system to make it more slack or taut. However, a turret-moored FPSO needs to have a larger thruster capability, since the sidestep movement will be executed by the use of thrusters. This sidestep capability can be used as an additional safety measure for floaters operating in deep-water regions, which are susceptible to glacial ice. In particular for a turret-moored FPSO, this capability may be beneficial as an option prior to the turret disconnection.
For this concept, the configuration of risers and mooring system should be carefully designed to withstand the shifting conditions, as the riser and mooring system will still be attached to the platform during the sidestep process. A steel riser in a lazy wave configuration (SLWR) is proposed to fulfill this requirement.
This paper discusses the benefits and challenges of the sidestep concept. This paper also presents the analysis results of a lazy wave riser during the sidestep condition. Analysis works are carried out using the OrcaFlex simulation program.
Oil and gas activities have now reached the ‘new frontier’ areas within the Arctic Circle. This area has always been regarded as challenging due to the harsh environmental conditions, which are characterized by sub-zero temperatures, severe sea-states, intensive seasonal fog and glacial ice masses.
Glacial ice occurs in many areas of the Arctic and sub-Arctic regions, for example west and south east of Greenland, west of Baffin Island, on the Green Banks and in the Russian Arctic. Each of the field developments in the area above has its own specific ice management strategies. However, the strategies generally have two objectives: to ensure the safety of the assets (people, installations and environment) and to maximize operational efficiency.