Nanochemo-mechanical signature of organic-rich shales: a coupled indentation–EDX analysis
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Nano-ChemomechanicalSignatureofOrganic-RichShalesACoupledIndentation-EDXAnalysis.pdf
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Author(s)
Hofmann, Ronny
Bryndzia, Taras
Abedi Mashhadi Mighani, Sara
Slim, Mirna I.
Ulm, Franz-Josef
Date Issued
January 2016
Journal
Acta Geotechnica
Publisher
Springer-Verlag
Citation
Abedi, Sara et al. “Nanochemo-Mechanical Signature of Organic-Rich Shales: a Coupled indentation–EDX Analysis.” Acta Geotechnica 11, 3 (January 2016): 559–572 © 2016 Springer-Verlag Berlin Heidelberg
Version
Author's final manuscript
Abstract
The organic-inorganic nature of organic-rich source rocks poses several challenges for the development of functional relations that link mechanical properties with geochemical composition. With this focus in mind, we herein propose a method that enables chemo-mechanical characterization of this highly heterogeneous source rock at the micron and submicron length scale through a statistical analysis of a large array of energy-dispersive X-ray spectroscopy (EDX) data coupled with nanoindentation data. The ability to include elemental composition to the indentation probe via EDX is shown to provide a means to identify pure material phases, mixture phases, and interfaces between different phases. Employed over a large array, the statistical clustering of this set of chemo-mechanical data provides access to the properties of the fundamental building blocks of clay-dominated organic-rich source rocks. The versatility of the approach is illustrated through the application to a large number of source rocks of different origin, chemical composition, and organic content. We find that the identified properties exhibit a unique scaling relation between stiffness and hardness. This suggests that organic-rich shale properties can be reduced to their elementary constituents, with several implications for the development of predictive functional relations between chemical composition and mechanical properties of organic-rich source rocks such as the intimate interplay between clay-packing, organic maturity, and mechanical properties of porous clay/organic phase. Keywords:
Anisotropy; Cluster modeling; Ductility; Energy-dispersive; X-ray spectroscopy; Nanoindentation; Organic-rich shale; Volume fraction
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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DOI of Published Version
https://doi.org/10.1007/S11440-015-0426-4
