Prediction of Shale Mechanical Properties from Global and Local Empirical Correlations

Abstract

Triaxial testing was used on a suite of shales of varied age and geographic distribution in order to ascertain static and dynamic elastic properties, strength and frictional response. The shales were also fully characterized in terms of composition, fabric elements, standard and exotic physical and petrophysical properties, including dielectrics and nuclear magnetic resonance. Empirical correlations were made between static mechanical properties and the other properties measured in order to determine empirical strength correlations for a global and a local shale population. For the global population, dynamic elastic properties were poor empirical predictors of shale strength. Better correlations could be obtained with physical properties such as cation exchange capacity and porosity. Good porosity‐velocity and impedance correlations were obtained however from the global shale population. Dynamic properties were better predictors of strength and static elastic properties in a local shale population where the rocks have shared similar compactional and diagenetic histories.