Dynamic optimization control of injection-production parameters for autothermic pyrolysis in-situ conversion process of oil shale

The autothermic pyrolysis in-situ conversion process of oil shale has emerged as a vital development direction due to its advantages of environmental friendliness and low cost. However, previous studies predominantly employed constant injection and production parameters, which often result in inefficient compression energy injection and formation oxidation losses, thereby limiting further improvements in energy efficiency and oil production. To address these issues, this study establishes a dynamic optimization model for injection-production parameters in the autothermic pyrolysis in-situ conversion process of oil shale, developing a dynamic control methodology for gas injection rate and oxygen content to enhance the economic viability and feasibility of the process. The results indicate that under the optimal combination of gas injection – adjustment time, decay rate, and terminal flow rate – the steady-state phase during late production can significantly reduce input compression energy and inhibit hydrocarbon oxidation losses, ultimately leading to a substantial increase in the peak energy efficiency and cumulative oil production. Furthermore, by synergistically regulating oxygen content and injection rate during the early production stage, the compression energy can be further reduced, ultimately elevating the energy efficiency to approximately fourteen, demonstrating the technical feasibility for industrial-scale production. These findings and the identified key parameters provide crucial theoretical and technical support for the large-scale application of the autothermic pyrolysis in-situ conversion technology for oil shale.