Thermal analysis of extracted asphaltenes from Yarega heavy crude oil experimental measurements were made for better understanding behavior of the asphaltenes during SAGD (steam) and in-situ combustion (air) methods of heavy oil recovery. Scanning electrone microscope (SEM) and second law of thermodynamics were also used.
Figure 1 shows TG curve of the asphaltenes behavior during different methods of recovery. The higher amount of coke yield was obtained as a result of SAGD. It should be noted that this process has the highest temperature range of weight loss and the temperatures of the beginning and the end of process. The energy activation of this process is 248.7 kJ/mol.
Asphaltenes during in-situ combustion have no coke yield, but occurs in the highest temperature rate (from 485⁰C to 521⁰C) and has the highest energy activation (294.2 kJ/mol).
Based on thermodynamic calculations and photos of coke yields, which were made by SEM, difference between asphaltenes during in-situ combustion and SAGD were obtained (Fig. 2).
The asphaltenes have the lower strong and well-ordered structure as a result of in-situ combustion. It could be the reason of absence of coke yield. During SAGD the most strong and well-ordered structure occurs.
Boytsova Alexandra is a Ph.D, student at Saint Petersburg Mining University, Russia. She has published more than 40 research articles.