Abstract

The ability to keep station is recognized as a key technical demand for yearround hydrocarbon exploration, development and production operations in thehigh arctic deepwater environment. Ice management has been used as ameans to improve station keeping ability in sea ice and extend operabilitybeyond the relatively short, ice free season in the Canadian BeaufortSea. The reliability of ice management is contingent upon accurate icedrift forecasting so decisions about operation suspension in the event of apotentially unmanageable ice intrusion can be conducted in a timelymanner. This paper demonstrates tactical level sea ice drift forecastingand proposes a model for free ice drift applicable to the shoulder seasons ofthe Canadian Beaufort Sea exploration window. Model calibration isdemonstrated with real ice drift time histories and the assumptions andlimitations of the approach are discussed.

Introduction

A significant hydrocarbon reserve is believed to exist in the higharctic. U.S. Geological Survey data [Bird et al. 2008] was used byHamilton [2011] to estimate that 40 billion bbl of oil could lie in the higharctic deepwater (defined as water depths >100m). A vision foraddressing the technical challenges associated with safe and economic floatingdrilling in the high arctic was also defined. With respect to executionof ice management operation support, Hamilton et al. [2011] and Younan et al.[2012] begin to address these technical challenges by defining a near-fieldicebreaker tasking process control framework and a far-field riskcharacterization / alert system framework, respectively. A necessarycomponent of the proposed far-field risk characterization / alert system isaccurate ice drift forecasting.

Some of the earliest calibrated, physics based ice drift models wereproposed by McPhee [1978] and Hibler [1979]. The fundamental dynamics ofboth models is governed by Newton's second law with special consideration givento turning due to the Coriolis force. Hibler [1979] decoupled ice / oceanmomentum and considered the relationship between the two in terms of water dragacting along the bottom surface of the ice. This was acceptable becauseHibler emphasized Arctic basin scale gridded models and therefore spentconsiderable time developing constitutive laws for the rheological behavior andmass conservation associated with ridging and rubbling in pressured ice. McPhee [1978] relied heavily on the 1975-1976 AIDJEX (Arctic Ice Dynamics JointExperiment) field project for model calibration and focused on modeling freeice drift of individual floes.

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