Arctic Offshore Pipeline Design and Installation Challenges

Abstract

With the oil industry’s continued quest for oil and gas in frontier offshore locations, several developments have taken place in regions characterized by seasonal ice cover including the US Beaufort, North Caspian, and Sakhalin Island. In these projects, pipeline systems have been used, which are a cost-effective, safe, and reliable mode of hydrocarbon transport. For pipeline development in Arctic, several years of data need to be collected to support the pipeline design and construction planning, and may be required by regulations. Therefore, Arctic offshore pipeline projects generally require repetitive mapping surveys and geotechnical programs to verify design loads, soil properties, and thaw settlement potential. The major design loads that are considered for Arctic projects include ice gouging, strudel scour, upheaval buckling as well as thaw settlement. These issues can have a significant influence on the pipeline engineering considerations such as strain based design, target burial depth requirements, cost, and safety. While important to the design of the pipeline, these issues account for just a few of the many criteria that must be considered when routing a pipeline; criteria which can be categorized as either engineering, environmental, social, administrative, or infrastructural. The pipelines which are currently operational in the Arctic are located in shallow water depths and close to shore but were influenced by the unique Arctic environmental loading conditions. The experience from these past projects provides a significant base for the design, and operating of future offshore arctic pipelines. Pushing the limits to developments further offshore in deeper water will require that additional consideration be given to aspects related to pipeline design, in particular with respect to burial for protection against ice gouging.