Elastic anisotropy modeling of Kimmeridge shale

Anisotropy of elastic properties in clay‐rich sedimentary rocks has been of long‐standing interest. These rocks are cap rocks of oil and gas reservoirs, as well as seals for carbon sequestration. Elasticity of shales has been approached by direct velocity measurements and by models based on microstr...

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Bibliographic Details
Published in:Journal of geophysical research. Solid earth 2013-08, Vol.118 (8), p.3931-3956
Main Authors: Vasin, Roman N., Wenk, Hans-Rudolf, Kanitpanyacharoen, Waruntorn, Matthies, Siegfried, Wirth, Richard
Format: Article
Language:English
Subjects:
Anisotropy
Carbon sequestration
Elastic anisotropy
Elastic constants
Elastic properties
Geophysics
Grains
Mathematical models
Microstructure
Oil reservoirs
Oil shale
physical properties of rocks
Porosity
Rocks
Sedimentary rocks
Shale
Shales
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Summary:Anisotropy of elastic properties in clay‐rich sedimentary rocks has been of long‐standing interest. These rocks are cap rocks of oil and gas reservoirs, as well as seals for carbon sequestration. Elasticity of shales has been approached by direct velocity measurements and by models based on microstructures. Here we are revisiting the classical Kimmeridge shale studied by Hornby (1998) by first quantifying microstructural features such as phase volume fractions, grain shapes and grain orientations, and pore distributions with advanced analytical methods and then using this information in different models to explain bulk elastic properties. It is shown that by application of a self‐consistent algorithm based on Eshelby's (1957) model of inclusions in a homogeneous medium, it is possible to explain most experimental elastic constants, though some discrepancies remain which may be due to the interpretation of experimental data. Using a differential effective medium approach, an almost perfect agreement with experimental stiffness coefficients can be obtained, though the physical basis of this method may be questionable. The influence of single crystal elastic properties, grain shapes, preferred orientation, and volume and shapes of pores on elastic properties of shale is explored. Key Points ·Quantitative characterization of shale microstructure · Modeling elastic anisotropy of shale based on observed microstructures · Models describe elastic coefficients within experimental uncertainties
ISSN:2169-9313
2169-9356
DOI:10.1002/jgrb.50259