Micromechanical characterization of the lower Triassic Montney Claraia biostrome

摘要

Hydraulic fracturing operations favour mechanically weak horizons over soft lithologies for fracture propagation; thus, accurate assessment of the elasto-plastic properties of these bedded layers is crucial for deliverability. Moslow, Adams, & Terzuoli, 2016 proposed the deliverability of hydrocarbons in the Montney shale play to be related to the mechanical contrast of biostromes with surrounding siltstones; however, the logistics of determining these mechanical properties are difficult. This work aims to characterize the constituent biogenic and silt rich phases present in the lower Triassic Montney formation through micromechanical testing. Petrographic thin sections (~30 μm thick) are prepared from Montney shale core trimmings from a silt rich and a bioclast rich horizon to quantify the elastic and plastic deformations of the material at a micromechanical scale. Nanoindentation combined with photomicrography and scanning electron microscopy with energy/wave dispersive spectrometry (SEM: EDS/WDS) are used to analyze the mechanical properties such as fracture toughness and stiffness of the samples along the view inplane with bedding, where mechanical properties out of plane are to be incorporated in future works. The observed micromechanical behaviour stemming from structural/mineralogical causes will ultimately serve to better understand reservoir fracability in difficult geomechanical sampling conditions.