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.