A Satellite Terminal System for the Arctic

Abstract

ABSTRACT Experience has shown that ice rubble fields form around artificial islands in the Beaufort Sea, the extent depending upon water depth, island slopes, and overall is 1an d configuration. If sand is1ands or retained islands are used for production and product storage, there is a possibility that access by export tankers to docking facilities adjacent to the island would be impeded by the rubble formations. It is for this reason that the feasibility of installing a terminal remote from the production facility was examined. This paper covers the basic philosophies used in the layout of the satellite terminal system; the choice of structural shape; the ice loading return periods; the action of ice around the structure; and the proposed methods for mooring and loading. INTRODUCTION As a result of a request from the Canadian Government, the three main Canadian Beaufort Sea operators, Dome Petroleum Limited. Esso Resources Canada Ltd. and Gulf Canada Resources Inc., jointly agreed to submit to the Beaufort Sea Environment Assessment Panel an Environmental Impact Statement (EIS) relating to future offshore hydrocarbon development in the Beaufort Sea 1. This EIS addresses production, storage and shipment aspects. particular related to oilfield development, as well as matters more commonly referred to as "environmenta1". Swan Wooster Engineering was invited to provide technical back-up to the Participants in matters relating to the conceptual design of support structures for production, storage and marine terminal facilities 2. The work presented in this paper was developed during the course of this study. In the area of interest the water depth range is between 0 and 60 metres. To date, drilling operations using artificial islands or bottom founded platforms have reached the 30 metre mark (with plans in hand to reach 40 metres). and have entailed the use of varying quantities of sand fill which are generally available in the Canadian Beaufort. For initial production. it was considered that the structures or concepts used would be a developmen1 of techniques used or proposed so far for the arctic, and this step-wise approach led largely to consideration of artificial islands or retained fill solutions. This type of solution is considered to provide excellent protection from the more severe ice features but, in winter, the structures are likely to be surrounded by floating or grounded rubble fields. Atpresent. however, little is known about the ability to navigate ship traffic through rubble which is in, or approaching, the grounded mode. Consequently, as one of the alternatives, attention turned to the development of a terminal remote from the main structures. and of a shape and depth which would limit the formation of a rubble field. In the study. the potential system alternatives were considered in two categories; "separate" and "combined" systems. In the "separate" configuration. each facility could be physically remote from the other, but linked by submerged pipelines to form a complete unit. In the "combined" system, the production, storage and loading facilities could be contained on. or in. a single structure.