Fates of pyrolysis oil components in the non-isothermal propped fractures during oil shale in situ pyrolysis exploitation

Abstract

In situ pyrolysis by heating the reservoir is an effective method to convert oil shale resources to liquid oil. However, in the in situ non-isothermal reservoir during artificial heating, pyrolysis oil components experience extremely complex processes from generation to recovery, including phase transition, component separation, migration, secondary cracking, etc. These processes determine the in situ pyrolysis exploitation efficiency. In this study, pore-scale experiments of distribution, migration, and recovery were performed in a non-isothermal propped fracture. Results showed that pyrolysis oil flowed in a mixed state of multi-components through continuous oil channels below 260 °C, and the continuous oil channels narrowed with the improvement of temperature; while the separation of the light and heavy components occurred at higher temperatures. The fates and recovery mechanism of pyrolysis oil components were revealed under different temperatures, results indicated that the distribution and migration characteristics contributed to the lightness of the produced oil, and might induce the blockage of the in situ reservoir. The obtained results can provide preferences for predicting and adjusting the status of in situ pyrolysis exploitation.