Coupled flow-thermal-hydrocarbon generation numerical simulation of IFCD oil shale in-situ pyrolysis and mining based on experiments from a large-scale ground experiment device

Oil shale, an important unconventional oil and gas resource, has drawn increasing attention for in-situ mining. This study focuses on combustion-heating-based in-situ pyrolysis using oil shale from the Huadian Basin, Jilin Province, China. Large-scale ground experiments were conducted, and a corresponding three-dimensional finite-volume numerical model was developed to simulate hot flue gas flow, heat conduction, and hydrocarbon generation. Comparative analysis shows the model accurately predicts temperature, oil production, and kerogen degradation. After 20 days, simulated oil production was 8.14 kg versus 7.99 kg in experiments (1.88% relative error), and simulated kerogen degradation was 58.54% versus 57.48% (1.84% relative error). The integrated experimental-numerical approach elucidates the coupled flow-thermal-reaction mechanisms of in-situ pyrolysis and evaluates the effects of key parameters. Results indicate that a gas injection velocity of 14 m/s and a gas injection temperature of 800 K optimize fluid flow, heat conduction, and oil production. These findings provide a reliable basis for process optimization and have significant implications for the industrial-scale development of oil shale resources.