10 CO2 Pipeline Operation and Maintenance
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Published:2012
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Review of numerous large natural deposits of CO2 that have been existing underground for millions of years are testament to stable long-term possibility of storage of CO2 [1]. Since early 1970, many of these CO2 reservoirs have been accessed and used mostly for enhanced oil recovery (EOR) operations. An extensive pipeline network (transporting pure CO2) has been built that now stretches nearly 8000 km, mostly as previously referred to, in the United States. As a result, the technology, operations and risks associated with the transportation of pure CO2 are well understood and can be relied as a basis for transporting CO2 containing impurities.
For most pipelines designed for the transportation of supercritical CO2, the ability to maintain adequate/minimum pressure is important for successful operations. This is typically achieved by compressing CO2 at source and recompressing it at various locations along the pipeline length (if needed). Not all pipelines require recompression if adequate high pressure is available at the source to overcome frictional and elevation losses while meeting the delivery pressure at the outlet of the pipeline. For example, the Weyburn pipeline, which transports CO2 over 345 km from an industrial facility in North Dakota from Basin Electric Cooperative Dakota Gasification Project (Figures 10-1 and 10-2) to an EOR site in Saskatchewan, Canada, operates without a recompression system [2]. The Synfuels Plant has been successfully capturing and transporting a portion of its CO2 emissions to Canada since 2000. However, it is also designed to ensure that the delivery pressure at the terminal point meets the objective of injection pressure. Thus, the delivery pressure is 14800 kPa (2175 psi).
Transportation of CO2 by pipelines is widely practiced and accepted as a technological application, not only for EOR but also for industrial and commercial purposes. Moreover, operational risks of pipeline failure are well established, but again mostly for relatively pure CO2. Gathering or extraction, processing, transportation, and injection of (mostly pure) CO2 are common business operations and have been accepted sometimes to handle larger-scale geologic storage operations.