Comprehensive preparation and multiscale characterization of kerogen in oil shale

Abstract

Despite the importance of kerogen as the organic backbone of hydrocarbon production from source rocks such as oil shale, properties of kerogen at both the atomic and micron scales remain unexplored under non-destructive conditions. As the demand for the utilization of kerogen in oil shale rises, identifying its atomic anisotropy and three-dimensional (3D) distribution in oil shale becomes even more important. In this study, using a hybrid preparation-analysis method, we propose a panel of physical preparation methods, including mechanical stripping and polishing thinning, and characterization techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), terahertz time-domain spectroscopy (THz-TDS), and oblique incidence reflectance difference (OIRD) analysis without considering pyrolysis and the chemical separation of kerogen. We investigated kerogen's anisotropy at the atomic scale and its 3D distribution as flocculants and strips and developed a new OIRD computed tomography (CT) method (OIRD-CT) amenable to experimental validation, including SEM and THz scanning. Thus, the multiscale properties of kerogen detected using the combination of physical preparation and advanced characterization techniques, especially OIRD-CT, are helpful in improving our understanding of the precise utilization of oil shale.