Pore-Scale Fluorescence Evidence for Mineral-Controlled Oil Fractionation in Lacustrine Shale

Taking shale samples from the Shahejie Formation in the Dongying Sag as the study object, this study integrates XRD, TOC, Rock–Eval pyrolysis, low-temperature N₂ adsorption, scanning electron microscopy, single-mineral adsorption experiments, laser-scanning confocal microscopy, and fluorescence lifetime imaging microscopy (FLIM) to investigate the relationships among mineral composition, pore structure, and shale-oil component differentiation.

The results show that the studied interval is dominated by calcareous shale and mixed shale, and that mineral composition significantly affects pore structure and shale-oil occurrence characteristics. Clay-rich samples generally develop more nanoscale pores and are more likely to retain heavy components, whereas carbonate-associated pore systems, especially those related to calcite, are more favorable for the occurrence and migration of light components.