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.

The autothermic pyrolysis in-situ conversion process (ATS) consumes latent heat of residual organic matter after kerogen pyrolysis by oxidation reaction, and it has the advantages of low development cost and exploitation of deep oil shale resources. However, the heating mechanism and the characteristic of different reaction zones are still unclear. In this study, an ATS numerical simulation model was proposed for the development of oil shale, which considers the pyrolysis of kerogen, high-temperature oxidation, and low-temperature oxidation. Based on the above model, the mechanism of the ATS was analyzed and the effects of preheating temperature, O₂ content, and injection rate on recovery factor and energy efficiency were studied. The results showed that the ATS in the formation can be divided into five characteristic zones by evolution of the oil and O₂ distribution, and the solid organic matter, including residue zone, autothermic zone, pyrolysis zone, preheating zone, and original zone. Energy efficiency was much higher for the ATS than for the high-temperature nitrogen injection in-situ conversion process (HNICP). There is a threshold value of the preheating temperature, the oil content, and the injection rate during the ATS, which is 400 ℃, 0.18, and 1100 m³/day, respectively, in this study.