Real-time imaging of oil shale pyrolysis dynamics at nanoscale via environmental scanning electron microscopy.

Pyrolysis is a promising technology to increase pore and fracture connectivity in oil shale and thereby accomplish commercial recovery of unconventional hydrocarbons. Herein, real-time oil shale pyrolysis dynamics are imaged at nanoscale via environmental scanning electron microscopy (imaging resolution of 58 nm/pixel, imaging speed of 1 frame per second, and heating temperature up to 750 °C). It is counterintuitively observed that 1) inorganic nano-fractures started to appear below 100 °C; 2) inorganic nano-fracture width had a non-monotonous relationship with temperature; and 3) organic kerogen areas decreased monotonously with increasing temperature. These findings will establish a standard benchmark for unconventional resource recovery, promote fundamental understanding of oil shale pyrolysis dynamics at nanoscale and provide key guidance on oil shale extraction at reservoir scale. • Real-time imaging of oil shale pyrolysis dynamics is performed at nanoscale • The initial appearance and growth of nano-fractures are observed below 100 °C • A non-monotonous relationship between nano-fracture width and temperature is identified [ABSTRACT FROM AUTHOR]