Reservoir characterization of the unconventional shale plays necessitates rock physics modeling of the effects of organic richness and thermal maturity in shales.

Any rock physics model (RPM) designed for organic shales requires knowledge of the bulk density and elastic moduli of the nanoporous organic matter (OM), or better, the solid OM with varying amounts of nanoporisity and hydrocarbon saturation.

Laboratory measurements of the elastic properties of OM are difficult and largely unreliable, albeit some Atomic Force Microscopy (AFM) studies show some promise.

To constraint elasticity of solid OM, I combine empirical evidence in the form of log data with fitting RPM application to estimate elasticity of OM present in two different subsets of thermally mature shales: (1) oil and condensate shale and (2) dry gas shale, where OM porosity averages 25±5% of the porous OM volume fraction. Then a joint inversion using the Mori-Tanaka-Benveniste and Gassmann theories yields reliable estimates of the bulk and shear moduli of the solid OM, which can be compared with AFM-based results. When the density and elastic properties of solid OM are known, it is straightforward to estimate those properties for the porous OM with varying porosity and thermal maturity to be used in dedicated RPMs.

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Presented by Lev Vernik, Scientific Advisor

Lev Vernik is a Scientific Advisor at GeoSoftware, where he shares his extensive expertise in seismic petrophysics, rock physics, geomechanics, and quantitative seismic data analysis.

With 27 years of experience in the field, Lev is a globally recognized pioneer in Rock Physics and has authored more than 100 papers in peer-reviewed journals. His book, "Seismic Petrophysics in Quantitative Interpretation" (2016, SEG), has been a top seller on the SEG list for three consecutive years.