Exploration and development of the gas fields in the northern areas of Alberta and British Columbia have been increasing in recent years. In response to the activities, the pipeline systems for transporting the gas to markets in eastern Canada and the United States have been, and will continue to be, expanden northward. This expansion places the pipelines within discontinuous permafrost regions. Discontinuous permafrost presents at least two challenges to the integrity design of high pression gas pipelines, namely, differntial settlement resulted from thawing of frosen soil and frost heave resulting from freezing of soil. The thawing and freezing processes of soil surrounding the pipeline are closely related to, among other factors, the pipeline temperature profile along the pipeline route. In order to identify the potential locations and the magnitudes for differential settlement and frost heave, the temperature profile along the pipeline need to be determined. Nova Gas Transmission Ltd. (NGTL) has been expanding its pipeline system in northwest of Alberta. As a part of design process, a methodology for prediction of pipeline temperature profile has been developed. This paper outlines the methodology and analysis procedure for temperature profile prediction which are illustrated with some numerical examples.The analysis is based on NGTL's simulation tool HART (Hydraulic Analysis and Resources Management Tool) with some modifications to investigate node to node temperature change of the network considering different ground temperatures and gas inlet temperatures. The pipeline temperature profile is found to be sensitive to gas volume, gas velocity, ground temperature, gas temperature at tie-in points, and the elevation changes of the pipeline route.
Gas pipeline temperature profile predictions in discontinuous permafrost regions
Vorhersagen des Gaspipeline-Temperaturprofils in Gebieten mit diskontinuierlichem Dauerfrostboden
1997
8 Seiten, 7 Bilder, 7 Quellen
Aufsatz (Konferenz)
Englisch
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