A New Correlation Between Cumulative Hydrocarbon Production Time and Heater Spacing of in Situ Conversion Process of Oil Shale

The heat injection well or subsurface heater temperature plays an important role during the in situ conversion process (ICP) of oil shale formation because of the strong temperature dependency of pyrolysis of solid kerogen into fluid. The oil and gas generation and production are greatly affected by heater well spacing too. In this paper, a reservoir simulation model of oil shale ICP was generated which incorporated all the complicated processes of heat dissipation through oil shale’s porous medium, the transportation of heat through the fluid, temperature-dependent chemical reactions, oil and gas generation through solid kerogen and production of these oil and gas, was generated. The outcomes of the simulation model were further used to explore the relationship between cumulative hydrocarbon production time and heater wells spacing. The results showed that the generation of hydrocarbon fluid through solid-phase kerogen is strongly temperature-dependent process. As a result, with the decrease in heating temperature or increase in heater well spacing, the oil rate peak noteworthy decreases and the production time is delayed. Additionally, both of lowering down the heating temperature or increasing the heater well spacing also affect (reduce) the cumulative hydrocarbon production. But the ultimate hydrocarbon recovery is expected to be equal if the simulations are performed over a very long time period. This work introduced a set of detailed simulation studies to examine the scenarios or conditions that may be responsible for different production times as a function of heater wells spacing during the oil shale ICP. The results revealed that the ICP is a strong heater wells spacing dependent process.