The XV International Congress On Rheology: The Society of Rheology 80th Annual Meeting, Monterey (California) (3–8 August 2008):
AIP Conference Proceedings, 07 July 2008, Vol.1027(1), pp.1202-1204
As the trend for future crude oil reservoirs goes towards more and more extreme depths, the requirements for enhanced oil recovery become more sophisticated. This is due to the fact that one has to face not only extremely elevated temperatures and pressures, but the crude oil itself exhibits a high content of high molecular weight hydrocarbons. As these hydrocarbons contain different functional groups like paraffins and asphaltines they are prone to show pronounced waxy crystallization during later transportation processes. Hence the rheological properties of the crude oil itself as well as supporting fluids used in the process, e.g. drilling fluids, have to be monitored for the whole process cycle, from the well to the refinery. Whereas the rheological properties in the reservoir is dominated by the salinity, temperature and pressure, all of which can be simulated in the measuring cell of a rheometer, the rheological properties during the actual transportation is a completely different challenge. One of the major issues is the enormous volume of the oil itself that has to flow through a pipeline. As crude oil always contains a high amount of high molecular weight saturated hydrocarbons it will show a tendency to precipitate or “wax” while the oil cools down being pumped to the surface. The precipitated wax may cause partial congestion of the pipeline which again can lead to a significant pressure drop. Trying to reduce this waxy crystallisation by insulating or even heating the pipeline requires tremendous financial efforts, requiring more pumps, heating elements or additives. The complete transportation cycle of a crude oil, starting at the drilling site, leading through the pipeline (which may cover diverse climatic zones) before finally reaching the refinery, can be simulated with a rotational rheometer by implementing time profiles of distinct shear rates, temperatures and pressures. Moreover, the formation of wax can be measured under shear by means of optical microscopy, providing rheological data and microscopic images simultaneously. Even in a pipeline accident, Rheology can help providing the answers on how to recover the oil with minimum environmental damage.
Materials Physics and Applications
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