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Reversibility of Asphaltene Aggregation in Live Oils: Qualitative and Quantitative Evaluation

Mohammadi, S ; Sharif University of Technology | 2015

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  1. Type of Document: Article
  2. DOI: 10.1021/acs.jced.5b00297
  3. Publisher: American Chemical Society , 2015
  4. Abstract:
  5. Despite the numerous experimental studies concerning asphaltene, the extent of reversibility of asphaltene aggregation at reservoir conditions remains still an elusive and controversial issue in the available literature. In this work, a series of depressurization and repressurization experiments were performed on three different live oils for qualitative and quantitative evaluation of the reversibility of asphaltene aggregation under typical pressure and temperature conditions of oil fields. The obtained results reveal that the kinetics and the extent of reversibility of asphaltene aggregation at elevated pressure and temperature are majorly controlled by the characteristics of the reservoir fluid and asphaltene formation driving forces induced by change in pressure and temperature. It is observed that asphaltene aggregation in problematic/unstable live oils tends to be a reversible process upon pressure change with subtle to intense hysteresis dependent on the temperature of the system. Furthermore, temperature reversibility experiments show severe hysteresis in precipitation and redissolution of asphaltene which is intensified by temperature decrement. In addition, at lower temperatures the kinetics of asphaltene redissolution is slower than the kinetics of aggregation. For the case of unproblematic/stable live oil, although asphaltene particles are formed by change in pressure and temperature, the particles do not severely grow and the aggregation process exhibits complete reversibility with no apparent hysteresis. The major interest of presented results is their important implications for better understanding and formulation of asphaltene phase behavior at reservoir conditions
  6. Keywords:
  7. Asphaltenes ; Hysteresis ; Kinetics ; Oil fields ; Aggregation process ; Asphaltene aggregation ; Asphaltene formation ; Lower temperatures ; Pressure and temperature ; Quantitative evaluation ; Reservoir conditions ; Reversible process ; Agglomeration
  8. Source: Journal of Chemical and Engineering Data ; Volume 60, Issue 9 , August , 2015 , Pages 2646-2654 ; 00219568 (ISSN)
  9. URL: http://pubs.acs.org/doi/10.1021/acs.jced.5b00297