Ice Based Construction of Offshore Arctic Pipelines

Abstract

Abstract In the nearshore zone of the Alaskan Beaufort Sea, three subsea pipeline bundles have been successfully installed by using conventional onshore construction equipment in the winter season operating from a thickened sea ice platform. Differences in water depth, route length and corresponding pipeline design for BP Northstar, Pioneer Oooguruk and Eni Nikaitchuq impacted the winter construction procedures used for each project. Each of these projects used the winter construction season to its maximum advantage, allowing the use of conventional and adapted onshore construction equipment and techniques. Comparatively, ice based winter pipeline construction in subarctic conditions has been generally less successful. On-ice pipeline fabrication and installation into a subsea trench has a track record for shallow water pipeline installation with reduced permitting issues compared to summer installation. Based on the experiences of these projects, this paper reviews the limitations of on-ice construction, the typical construction activities; the main equipment used and will highlight the main lessons learned.