Change in the structural-group composition of bitumen asphaltenes upon thermal bitumen recovery

Comparative analysis of thermal analysis and EPR spectroscopy data on asphaltenes from Ashal’chinskoe and Mordovo-Karmal’skoe bitumens recovered by steam drive and in situ combustion has been performed. It has been found that the steam drive does not alter the structural-group composition of asphaltenes whereas the in situ combustion lead to conversion of asphaltenes into coke-like particles deposited onto the rock surface in the reservoir. It has been shown that the asphaltenes with a high proportion of condensed aromatic entities are carriers of genetic information on the petroleum system.