Modernized mechanical testing of kerogen-rich shales (KRS) by monitoring in situ microscale tensile failures

The nanoindenter has recently been expanded as a method to monitor the tensile failures of KRS, by loading and failing micro-cantilever geometries. Existing methods have not identified the micro effects of the interlacing kerogen into the overall clay and non-clay matrices. Here we demonstrate a sophisticated tool for mechanically characterizing KRS in that it accounts for contributions from both the rock and the organic matter. Micro-beams are manufactured with a focused ion beam under a scanning electron microscope (FIB-SEM) and then loaded in cantilever mode with a nanoindenter while monitoring in-situ via SEM. The force-displacement curves were analyzed in light of the high resolution images collected during fracture initiation, propagation, and ultimate failure. Under loading, the micro-beams exhibit linear elastic behavior followed by plastic yielding before complete failure. This behavior has been shown to correlate with the amount of organic matter in the failure zone of the cantilever beam.