(631a) Textural Characterization of Shale Nanostructure

Nanostructure characterization of shales has received tremendous interest in recent years and aids in the understanding of how gases (and in what volume) are stored and permeate or transport through a shale formation. Of particular interest is also how the different components of shale (clay, kerogen, mineral, total organic content, etc) contribute to the nanostructure. The pore size range in shales spans from ultramicropores to macropores, so there is a need to combine several different techniques in order to determine the complete shale pore structure.

Gas sorption, including CO₂ adsorption at 273 K to assess the ultramicropores combined with Ar adsorption at 87 K to assess the mesoporosity, coupled with mercury porosimetry gives a complete micro-, meso-, and macropore size distribution as well as total pore volume. Micro- and mesopore size distributions were obtained from gas adsorption using state-of-the-art density functional theory (DFT) methods. Pore connectivity was explored through a detailed study of the hysteresis loops of the Ar isotherms.

In addition to the study of the shale nanostructure, kerogen was isolated intact from the shale sample and studied independently to compare the porosity of kerogen to the porosity of the shale. Comparison of the micro- and mesoporosity of the shale and its isolated kerogen indicate that kerogen is the main contributor to the porosity in this pore size range.

Finally, transport in shale and the isolated kerogen component was studied via experiments utilizing a zero length column and correlated with the determined structural properties of the materials.