Aggregation behavior of asphaltene of different crude oils as viewed from solution surface tension measurement

作者：Ghatee Mohammad Hadi^*; Shabih Manizheh

来源：Journal of Petroleum Science and Engineering, 2017, 151: 275-283.

DOI：10.1016/j.petrol.2017.01.017

• Capillary rise method
• Concentration and temperature dependence
• Crude oil asphaltene aggregation
• Surface tension measurement
• Toluene solvent

Deposition of asphaltene critically affects crude oil production and refining. Deposition extent depends on condition and crucially on the nature and chemical structure of asphaltene. Diversity of crude oil reservoirs makes the measuring technique, method, and deposition modeling an active field of research. In this work, solution of asphaltene sample (in toluene) of three oil reservoirs Gachsaran, Bangestan, and Kuh-e-Mond were studied to understand and characterize asphaltenes behavior at surface and aggregation in bulk by surface tension measurement. The surface tension was measured under liquid-vapor equilibrium by capillary rise method as a function of asphaltene concentration (13.3-2660 ppm) in the temperature range of 298-333 K. At very low concentrations (< 200 ppm), the surface tension of three samples is rather high and close to the surface tension of neat solvent. As the concentration increases (up to 266 ppm), surface tension decreases with a dip minimum characteristics of each reservoir. Therefore, at the low characteristics concentration (266 ppm), asphaltene highly adsorbed to the solution surface. At the high characteristic concentration (1700 ppm) aggregation may occur solely in bulk, at surface, or both dependifig on the asphaltene nature and temperature. As a result, an aggregation phenomenon at specific solution concentration represents the structural feature of each asphaltene sample. Overall, while the dependence on temperature is enhanced at higher concentration, asphaltene of the three reservoirs can be characterized by the concentration and temperature dependence of their solutions surface tension. Conclusively, the surface tension of asphaltene of Gachsaran (light crude oil) show strong dependence on concentration at low and high characteristic concentrations, while no such dependence is seen for Bangestan and Kuh-e-Mond (both of heavy crude oil) samples at high concentrations. These results are highly correlated with the reported asphaltene deposition features of each oil field.

• 出版日期2017-3