Evaluation of the organic matter product of Huadian oil shale during pyrolysis using multiple approaches: Guidance for the in situ conversion of oil shale

The in situ conversion of oil shale has gradually become the main method of oil shale development, which provides theoretical guidance for the Huadian oil shale in situ conversion programme. In this paper, a retorting simulation experiment of real underground pressure is carried out for Huadian oil shale, and the pyrolysis process of oil shale samples, the subsurface conversion environment and hydrocarbon generation patterns are systematically analysed. The results show that the 375–425 °C stage is the main oil production stage of oil shale. According to the group composition characteristics and low-temperature retorting data of residual oil collected in oil shale semicoke and pyrolysis oil at different pyrolysis temperatures, the heating temperature should not be lower than 350 °C. The pyrolysis evaluation results of oil shale semicoke indicate that the pyrolysis temperature of 425 °C is a turning point. When the temperature reaches 425 °C, the oil shale has no hydrocarbon generation value. The temperature of Huadian oil shale should be controlled within 375–425 °C in the in situ conversion project to obtain the greatest shale oil resources with the lowest energy input cost.