An Approach to Mechanical Proxy in Shales Using Nanoindentation and SEM/EDS – XRD Composition in Cutting Samples

M. NOYA; T.M. PIQUE; E. CAMILION; A. FLORIDIA; A. CANEIRO; G. PANIZZA; C. GRASETTI; N. CALARAMO; H. CELLERI; J. RAMALLO; M. FUENTES

Texas

Congreso; 55th U.S. Rock Mechanics/Geomechanics Symposium; 2021

A mechanical proxy for an exploration shale project is presented to identify suitable zones to acquire better information, such as cores or perform detailed geomechanical studies. Usually, this is done using brittleness indexes which have been very useful tools for exploration projects, but present certain deficiencies, such as the lack of calibration for a specific site and units of measurement. In this project an exploration proxy is proposed based on compositional properties obtained with SEM-EDS and XRD, and mechanical properties obtained with nanoindentation of drill cutting samples. A Multivariate Linear Regression (MLR) was used to correlate the modulus and hardness obtained by nanoindentation with compositional data from SEM-EDS, performing a robust equation calibrated with experimental data measured from the drill cutting shale samples. The MLR provides an indentation modulus and hardness after compositional independent variables, such as TOC, porosity, and mineralogy were measured. This was obtained both with SEM-EDS and XRD and a good agreement between the measurements was found. The MLR was extrapolated to several measurement of drill cuttings of the same well that were not nanoindented and an exploration proxy comparable to different brittle indexes was built, but with the advantage that the value reported is an actual modulus, comparable to the dynamic Young modulus, and that it was calibrated to the particular site.