In 2003, the U.S. National Science Foundation (NSF) initiated a program to determine the national requirements for polar marine science in the Antarctic and to assess vessel characteristics for a new generation Polar Research Vessel (PRV). This paper describes the results of that investigation. Science requirements included a need for year-round operations covering a wide range of diverse activities in geographic areas currently inaccessible. These requirements were followed by a series of technical studies that provided an assessment of vessel size, hull form, and power plant to successfully operate in 1.4 m (4.5 ft) level ice.
The Arctic offshore may hold the largest undiscovered oil deposits which could account for up to 25% of the world’s undiscovered hydrocarbons based on Gautier et al (2009). Access to the deepwater deposits in the Arctic Ocean presents a special challenge. In the past four decades only shallow water drilling campaigns have been executed in relatively mild ice environments and have accumulated valuable drilling experience. To drill an exploratory well at a deepwater Arctic location, a floating drilling platform is required. Floating platform design poses significant challenges given the harsh ice loading conditions and the demand on the hull and mooring system strengths. In most of the deep water Arctic regions, the winter season is characterized by the presence of first-year ice, multi-year ice, and in some areas ice islands and icebergs. Compared to the environmental loads due to waves, winds and currents, ice actions (both forces and moments) are considerably higher and are the governing loads for deepwater Arctic systems. The capability of a floater mooring system to withstand ice loads is limited as compared to gravity based structures. One of the solutions is a disconnectable system utilizing the ability to disconnect the floater from the mooring system and move off site when the ice loads are forecasted to approach the design limit. As of today, several disconnectable floating system concepts have been proposed, such as disconnectable FPSO, non ship-shaped circular FPSO, Arctic Spar and semi-rigid floater. These concepts are either intended for relatively mild Arctic ice conditions or require long durations for disconnection and re-connection. This paper presents an innovative disconnectable floating platform concept for deepwater Arctic, which can perform exploratory, development drilling and potentially year-round production in various deep water Arctic locations. This design, like many other similar concepts, by limiting the design ice loads to a pre-defined level, enables reasonable hull and mooring system configurations within existing technology limits for an environment where the environmental loading seems to approach infinity in practical terms, if unmanaged. In the event of an excessive ice feature approaching, the innovative platform can be quickly disconnected and towed away, and can then be quickly re-connected once the ice feature has passed.
Research on measuring the ice impact pressure on icebreaker hulls began in the late 1970's, and its focus was to determine the magnitude of the impact pressures and to obtain long-term statistics of the impacts. Increased computing power in the 1980's allowed the recording of time-histories on multiple sensors that led to the development of the pressure-contact area relationship. The aim of these systems, however, was to understand the ice impact process and to provide guidance to design engineers. This paper presents a new hull structure monitoring system that can benefit both the ship designers and operators for ships operating in ice-covered waters. With this system, the ice load monitoring system can measure and process the ice impact loads immediately after each impact in near real-time. The impact measurements are used to estimate the resulting stresses on the hull structures which are then compared to the allowable stresses. This system can provide meaningful near real-time feedback to the ship's crew of the stresses due to ice impact compared to the allowable stress. This information can assist the ship's crew in making informed decisions for safe and efficient operations in ice. The main focus of this paper is on the methodology for assessing the hull structural responses under ice impact and the presentation of this information to the ship's crew.
The largest icebreaking tanker built so far, Vasily Dinkov was delivered by Samsung Heavy Industries shipyard to Russian ship-owner SOVCOMFLOT. The vessel was designed and built for the transport of crude oil from the Varandey offshore terminal in east-southern part of the Barents Sea to a transshipment location near Murmansk. The vessel is under long-term charter for NARYANMARNEFTEGAS (NMNG), a joint venture of LUKOIL and ConocoPhillips. The new ship was constructed strictly to the requirements, specification, and concept design provided by the charterer as a basis for final design, building contract, and time-charter agreement. That approach was driven by time constrain, challenges of the project, and uncertainty about experienced icebreaker builder shipyard availability. The ConocoPhillips-LUKOIL marine technical group led the efforts for the feasibility design study at the early vessel design stage and contributed arctic design expertise and oversight of the final design and construction.
Numerical simulations are carried out to represent the historical data of ice interaction with the Kulluk during the 1980s. Three dimensional simulations include dynamics of the ice cover and the response of the mooring system. The results give modes of ice accumulation, clearing and ice forces. Depth-averaged simulations consider larger zones of the ice cover to examine a range of conditions that were observed during the past operation of the Kulluk in the Beaufort Sea. The simulations evaluate the effects of managed ice cover characteristics such as floe sizes and confinement. Predicted forces are compared to the historical record of measurements.
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