Formation of Hydrocarbons during the Thermal Maturation of Kaa-Khem Coal

The paper examines coal from the Kaa-Khem field from the viewpoint of its oil and gas generation potential. Coal from the Kaa-Khem field was subjected to hydrothermal treatment at 350°C/24 h to simulate the maturation of its organic matter. The kinetic characteristics of the organic matter of Kaa-Khem coal were assessed from the results of Rock-Eval pyrolysis at three heating rates. The kinetic characteristics of individual C1–C5 hydrocarbons were additionally studied by dry stepwise pyrolysis. Changes in the composition of hydrocarbon biomarkers before and after hydrous pyrolysis were also analyzed, and the hydrothermal treatment was found out to have affected mainly the distribution of n-alkanes and aromatic hydrocarbons, whereas the composition of the sterane and hopane biomarkers have not been modified any significantly. The study of the coal composition by pyrolytic gas chromatography–mass spectrometry made it possible to record the loss of long alkyl chains in the studied range of thermal maturity. Although the studies led us to estimate the hydrocarbon potential of Kaa-Khem coal as high, the possibility of its conversion and the prediction of the phase composition of the fluids remain uncertain and require further studies.