Abstract: The final temperature, heating time and the final oil and gas conversion rate of in-situ transformation of oil shale are closely related to the economic cost of in-situ mining. The relationship between hydrocarbon yield-conversion rate and hydrocarbon yield-activation energy of oil shale under different heating rates was obtained by using Rock-Eval 6 rock pyrolysis analyzer. The relationship between activation energy and conversion rate was established based on hydrocarbon yield. Further, based on the principle of chemical kinetics, the process of oil shale organic matter (kerogen) evolution was approximated to the thermal cracking reaction with the first-order reaction characteristics, and the relationship between reciprocal of temperature (1/T) and logarithm of heating time (ln t) under different conversion rates was obtained, and the temperature-time-conversion diagram of in-situ conversion of oil shale was established. Taking the oil shale of E_2-3 y Formation in Maoming Basin of Guangdong Province as an example, the temperature-time-conversion diagram of oil shale was drawn by the above method. It is shown that it would take 98 years to extract oil shale in this area by heating to 350℃ with 90% conversion rate, and 147 years to heat to 200℃ with 10% conversion rate without other measures. In fact, the in-situ heating of underground oil shale is heterogeneous,and the energy consumption of heating is large. It is possible to reduce the temperature and improve the quality of oil shale by adding catalyst to oil shale in-situ production.

Key words: oil shale, in-situ mining, conversion rate, shale oil, Maoming basin