ABSTRACT

The design of subsea systems in ice prone environments must consider the potential for interaction with ice features. Many methods designed to protect subsea equipment from ice contact have been previously investigated and utilized; the most common of which is open glory holes. Many models have been developed to simulate ice interaction events. This paper begins with a review of related literature to date. The review summarizes kinematic and numerical models that have been developed to study ice feature behavior and ice interaction with the seabed and subsea infrastructure. Additionally, an analytical tool was developed using MATLAB in order to model ice kinematics for ice features contacting structure and the seabed. The model examines heave and pitch of the ice feature during interaction, as well as physical limits of the ice feature. Results and future considerations are presented.

INTRODUCTION

As the worlds supply of conventional oil and gas decreases and demand steadily increases, utilizing reserves that, at one time would have been considered uneconomical, is now becoming a reality. It has been estimated that Arctic and harsh environment regions contain 15% to 25% of the world's petroleum reserves (Kenny et al., 2007a; Pike et al., 2011a). However, operating in Arctic and harsh environments poses many challenges, including remote locations, harsh weather and extreme temperatures, as well as many complications due to the presence of ice. Free-floating and gouging ice features pose a threat to the mechanical integrity of subsea equipment (e.g. wellheads, manifolds) and pipelines that protrude above the mudline. These ice features may contact, and damage or destroy the subsea equipment. On the Grand Banks, offshore Newfoundland, Canada, the annual contact probability for a 25 m diameter structure ranges from 10−4 to 10−3 for heights of 1 m to 10 m above the mudline (Croasdale et al., 2001).

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