A study on the characteristics of Algerian Hassi-Messaoud asphaltenes: solubility and precipitation
Hadj Abbas Abbas, Abdallah D. Manasrah, Lante Carbognani, Khaled O. Sebakhy, Mustapha El Hariri El Nokab, Messaoud Hacini, Nashaat N. Nassar
Abstract
This study focuses on detailed characterizations of asphaltene fractions extracted from the Algerian Hassi-Messaoud oil field. It was found that the extracted asphaltenes are not completely soluble in toluene, instead two fractions of asphaltenes were obtained upon solubilizing the heptane-precipitated neat asphaltenes in toluene. Extensive characterizations of the toluene-soluble and insoluble fractions were carried out using elemental analysis, Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and solid-state nuclear magnetic resonance (ssNMR). It was suggested that the high oxygen content and uneven compositional structures are the main contributors to asphaltene instability. The toluene-insoluble fractions were found to have higher polarity and aromaticity as well as more oxygen content than the neat asphaltenes and toluene-soluble fractions.