The effect of asphaltene molecular characteristic on the instability of Kuwaiti crude oils

• Published in: Petroleum science and technology Vol. 40; no. 2; pp. 237 - 256
• Main Authors: Safa, Muhieddine A., Enayat, Shayan, Rashed, Abeer M., Tavakkoli, Mohammad, Ghloum, Ebtisam F., Gharbi, Ridha, Santhanagopalan, Sriram, Vargas, Francisco M.
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 27-01-2022; Taylor & Francis Ltd
• Subjects: Alkanes; Aromaticity; asphaltene stability; Asphaltenes; asphaltenes characterization; Chemical properties; Condensates; Continuous production; Crude oil; Crude oils; Fourier transforms; Heptanes; Infrared spectroscopy; Low molecular weights; Refineries; solid detection system; Stability analysis
• ISSN: 1091-6466; 1532-2459
• DOI: 10.1080/10916466.2021.2017455

Asphaltene precipitation and subsequent deposition are challenging problems that hinder the continuous production of crude oil in many fields worldwide. In the present work, advanced technologies were implemented to effectively assess the effect of asphaltene characteristics on its stability in different Kuwaiti oils. Physical and chemical properties of stock tank oils (STO) have been measured. The extracted asphaltenes from the different STOs were characterized using X-ray diffraction (XRD) and Fourier Transform Infrared (FT-IR) spectroscopy techniques. The results showed that asphaltene with the lowest H/C ratios, the greatest aromaticity, and the highest degree of condensation exhibited a higher tendency to precipitate due to extreme variations in thermodynamic factors. The onset of asphaltene precipitation for crude oil was determined by the indirect method using three different n-alkane solvents. The onset of asphaltene precipitation was found to be around 40, 50, and 60 vol% of n-pentane, n-heptane, and n-octane, correspondingly. Thus, indicating that low molecular weights alkanes have a higher tendency to precipitate a wider range of soluble asphaltene in the crude. Moreover, asphaltene that was characterized to be the least stable showed the lowest asphaltene onset point detected by the indirect method.