An Innovative Energy-Efficient In Situ Conversion Process of Oil Shale: Numerical Simulation Study of Mechanism and Development Scheme

Abstract The in situ conversion process (ICP) of oil shale has gained significant attention after successful pilot testing in the USA besides having a relatively lower energy input–output ratio. In this paper, a novel method of stored heat recovery and its reutilization during ICP is presented and modeled through a simulator. The actual data of the pilot field project were used to model the complex mechanisms of heat transportation, chemical reactions, fluid generation, and production and heat losses through overburden and underburden geologic formations during the ICP of oil shale. The results of oil and gas generation and production by heating through downhole electrical heaters were validated by the previous model of the same field data. Since the posthydrocarbon production leftover temperature of oil shale was around 370°C, this developed model of ICP was extended to field scale to incorporate the novel concept of stored heat recovery by injecting the fluid. Based on the modeling of the mechanism and the amount of heat energy recovery, a comparative analysis of the same field was carried out and it was found that this proposed method is more energy-efficient with higher energy output. The field development strategy of oil shale through this proposed energy-efficient in situ conversion process was also offered. This research provides novel insights and comprehensive methods for a significantly higher energy output–input ratio for conventional ICP.