Nord Stream: Technical Planning in an Early Stage of the Project
Proceedings Publication Date
Dr. Werner Rott
Dr. Werner Rott
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On the basis of comprehensive feasibility studies, GAZPROM, EON Ruhrgas and Wintershall have decided to fill the emerging gap in transport capacities to Western Europe by building a new gas transport corridor under the Baltic Sea from the Russian region near Vyborg to Germany in the area of Greifswald. The decision to route the project offshore was taken under consideration of environmental and economic studies. This is more economical than onshore options because the consumption of fuel gas is minimized and thereby the CO2 emissions due to gas transport are reduced dramatically. The economic effect more than compensates for the initial higher investments for the offshore construction. The impact on the environment during construction and operation of the pipelines is under investigation strictly taking into account national and international law.

Nord Stream is an EU priority project to safeguard the deliveries of natural gas from the world largest gas reserves in Russia to Western Europe by diversifying transport routes. The challenge of this project is to plan and construct a EUR 5 billion project in an extremely short time through the Exclusive Economic Zones of five countries and the territorial waters of Russia and Germany. To meet this ambitious time schedule and to ensure the transport capacity of the project of up to 55 bcm p.a. of natural gas, proven engineering solutions were adopted wherever possible.

The material chosen is the well known X70, the route avoids wherever possible hazard areas, the construction itself is based on of state-of-the-art techniques.

Nevertheless, the project will be economically optimized by using modern design approaches. To minimize material requirements the so-called segmented wall thickness design is under consideration. The wall thickness of the pipeline can be reduced to a certain extent to match the pressure drop of the flowing gas. By using this principle the wall thickness might be reduced from 34.4mm through 30.9 mm to 26.8mm. Only in certain water depths and in the landfall areas as well as at the platform risers are the thicker walls necessary. This design would save significant amounts of material.

To safeguard a system designed in this manner, calculations will be carried out to ensure that even in the event of a sudden shut in at the delivery point in Germany resulting in a shut down at the intake point in Russia, the overall pressure after equilibrium cannot exceed the maximum permissible pressure for the lowest wall thickness.

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