Formation of hydrocarbon gases in domanik shale during hydrous pyrolysis

A sample of Domanik shale from a stratotype section along the river Chut (Ukhta District, Komi Republic, Russia) was affected to temperatures of 250-375 °C in an autoclave in the presence of water. The composition and yield of the resulting hydrocarbon gases was studied by gas chromatography. The yield of all C1-C5 hydrocarbons grew exponentially with increasing temperature in the autoclave. The total yield of gaseous hydrocarbons C1-C5 at 375 °C was 71 mg/g Corg and reached 18 mg/g Corg for methane. The increasing temperature in the autoclave resulted in decreasing ratio of methane/C2+ gases, which reflected a changing mechanism of methane formation at the corresponding stage of the thermal evolution of the Domanik organic matter.