Numerical simulation of oil shale in-situ exploration productivity comparison between steam injection and electrical heating

Oil shale is an important alternative resource to the conventional oil and gas because of its rich reserves. The in-situ heating exploitation is the most promising method to produce oil from the oil shale, mainly including electrical heating and steam injection heating. However, to the best of our knowledge, a comprehensive comparison between these two kinds of heating methods is still absent, thus the comparison is necessarily conducted to provide suggestions on how to select heating modes for the oil shale in-situ exploitation. On this basis, a systematic comparison is presented between in-situ steam heating and electrical heating, including physical and process parameters, and then sensitivity analysis and optimization on key parameters are carried out. Simulation results show that steam injection heating is superior to electrical heating in output, energy consumption and production cycle. The flow rate and temperature of the injected steam and the specific heat capacity of oil shale are sensitive to productivity. The production will be increased with larger injection flow rate and temperature. The thermal conductivity and porosity are less sensitive to the mining efficiency compared to the injection flow rate and temperature. At the same time, different well pattern structures also have an impact on productivity, and the hexagonal well pattern has better productivity benefits than the triangular and quadrilateral well patterns. In the simulation case of this paper, the most conducive parameters for exploitation were derived as injection flow rate 0.20 kg/s, injection temperature 650 °C, specific heat capacity 1.5 kJ/(kg⋅K), thermal conductivity 0.5 W/(m⋅K), porosity 0.05. These results are expected to provide theoretical suggestions for improving the productivity efficiency of oil shale in-situ exploitation.