Oil shale in situ conversion provides an important pathway for developing medium- to deep-buried, low-grade, and thin oil shale resources. Among the available approaches, the in situ conversion technology triggered by the topochemical reaction method, hereafter referred to as the TSA method, induces local oxidation reactions of pyrolysis residuals, fixed carbon, and reactive organic matter through preheating and oxygen-containing gas injection. The released in-formation heat then supports continued kerogen cracking and reaction-front propagation. This review summarizes the TSA method from a process-oriented perspective, linking reaction mechanisms, engineering controls, geochemical process identification, pilot tests, economic–environmental constraints, and scale-up evaluation. Existing studies indicate that the TSA method has formed a technical chain involving reaction initiation, heat/reaction-front propagation, oil and gas recovery, and process monitoring. Pilot tests provide evidence for operational feasibility, but not yet for full commercial feasibility. Thermal simulation results show that oil and gas generation and expulsion become significant above ~350 °C, and that 375–425 °C can be used as an important reference window for temperature control rather than a fixed optimum for all oil shale reservoirs. Geochemical indicators can provide complementary constraints for identifying reaction progress, especially when calibrated with produced oil and gas. Further development should focus on fracture-network control, heat-transfer enhancement, oxygen-supply regulation, multi-well coordination, equipment reliability, economic evaluation, groundwater protection, and CO2 emission accounting. These issues are critical for advancing the TSA method toward larger-scale, low-carbon, and well-regulated application.
Shen et al. (Tue,) studied this question.