Technical feasibility of constructing Arctic marine pipelines

Abstract

The Polar Gas Project was formed in 1972 to find the best means of transporting the significant quantities of natural gas that have been discovered in Canada's Arctic Islands to southern markets. After examining a variety of forms and modes in which the energy could be moved to market, Polar Gas concluded that a large diameter pipeline is the most efficient and secure way to transport large quantities of natural gas. Polar Gas initially concentrated its research and investigations in determining the technical and economic feasibility of installing large diameter pipelines across Arctic channels which were ice-infested for the major portion of the year. A number of construction methods were proposed and studied. Some of the marine crossings were to be constructed utilizing conventional laybarges, pullships or shore-to-shore bottom pull. However, for those channels in which the open water season would be too short, other methods were developed. The most appropriate technique appeared to be the ice island bottom pull method which utilizes the principles of bottom pull but operates from the ice surface on artificially thickened ice islands. Having established the technical feasibility, in December 1977 Polar Gas filed an application to the Canadian regulatory authorities requesting permission to construct pipeline facilities from Melville Island to Longlac, Ontario. However, recent advances in marine pipelaying technology have made it possible to evaluate new routing options which could combine natural gas resources from two areas in a single pipeline system. Welding techniques have now progressed to the stage whereby connections can be made in water depths exceeding those expected to be encountered by Polar Gas. It is now possible to consider welding to be accomplished either at the surface or on the sea bed. A new marine construction method is proposed for M'Clure Strait and it is a variation of the ice island bottom pull technique. The new procedure is referred to as the ice hole method, and it eliminates the need for a continuous ice trench. Continuing studies of construction methods, routings, the environment, socio-economic benefits and capital requirements have assured Polar Gas that the construction of a natural gas pipeline from the Arctic Islands is technically feasible and would offer significant benefits to the energy industry and Canada.