An investigation on the pyrolysis of low-maturity organic shale by different high temperature fluids heating.

• High temperature of CO 2 and steam were investigated to convert the shale oil. • The critical influencing factors of thermal fluid pyrolysis were determined. • The mechanical properties of shales during CO 2 and steam heating were captured. • Change of pore structures of shale oil during CO 2 and steam pyrolysis were determined. This study evaluates the potential of oil and gas generation from thermal pyrolysis of low-maturity organic rich shales by high temperature fluids injection. This method aims to convert the solid organic matter into hydrocarbons, thereby enhancing the quality of shale oil. The effectiveness of this technique hinges on its ability to convert retained heavy compounds and kerogen into light, moveable hydrocarbons, while also improving the oil recovery factor. Our experimental findings reveal that the decrease of total organic carbon content predominantly occurs between 400–550 °C or even higher. Different heating fluid media were tested for their pyrolysis effectiveness, among the heating media tested, CO 2 and steam mixture proved the most productive. A comparison of CO 2 , steam and CO 2 -steam pyrolysis experiments were carried out. It is observed that the oil yield is the lowest in a pure CO 2 atmosphere, while oil yield from the mixture of CO 2 -steam pyrolysis is the highest. In addition, the pore structure and mechanical properties of shales during pyrolysis process are examined. This investigation provides a theoretical basis for the large-scale upgrading of organic-rich shale formations, highlighting the critical influencing factors of thermal pyrolysis in optimizing shale oil recovery and quality. [ABSTRACT FROM AUTHOR]