Liberation of hydrogen-containing gases during closed system pyrolysis of immature organic matter-rich shales

At pyrolysis temperatures < 450 °C the sulfur-rich kerogens liberate more hydrogen as H2S than as CH4 and H2. At high temperatures hydrogen release as H2 and H2S is less significant. These results indicate that, besides the amounts of molecular hydrogen released, the liberation of H2S should be taken into account for a comprehensive H mass balance of organic sulfur-rich source rocks. Approximately 50% of the hydrogen in sulfur-rich kerogen is released as CH4 during cracking at high temperatures (600 °C).