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Application of Confocal Laser Scanning and Atomic-Force Microscopy in Elastic Properties Estimation of Organic-Rich Rocks

Ramil Ahmadov
Department of Geophysics, Stanford University, Stanford, CA; [email protected]

We estimate the indentation modulus (related to Young’s modulus via Poisson’s ratio) of organic-rich shale samples using a nano-indentation technique based on atomic-force microscopy, coupled with scanning electron microscopy and confocal laser scanning microscopy. Our approach is based on elaboration of data from two types of microscopy scanning electron and confocal laser scanning to separate organic-rich (kerogen containing) regions from the mineral matrix of oil shales, with subsequent nanoscale probing via atomic force microscopy.

First, the microtexture of shales is characterized by scanning electron microscopy. Possible regions of interest are selected, and confocal laser scanning microscopy imaging is performed to confirm the presence of organic matter. Then, an atomic force microscopy-based nano-indentation probe is employed to test the hardness of the previously identified region. Finally, nano-indentation modulus values are determined for individual mineral and organic-rich phases. This allows mapping of the absolute value of the modulus, providing spatial variation of elasticity, which then can be correlated with the initial mineralogy of the sample.

AAPG Search and Discovery Article #90083 © 2008 AAPG Foundation Grants in Aid