Probing the Mechanical Properties of Shales by Nanoindentation

摘要

Nanoindentation testing was performed on 121 fractured core and drill cutting shale samples to investigate the mechanical properties of samples. With a twofold goal to examine the possibility of obtaining mechanical properties from small intact core fragment and to hereafter establish an understanding for upscaling relationship between cuttings and cores. A new hardness-based method for clay matrix is proposed to reasonably process and interpret indentation data. Results reveal that the clay matrix's mechanical properties including Young's modulus, hardness, and fracture toughness can be obtained. Such a hardness-based method for processing indentation data proves to be convenient and feasible. Weak anisotropy is observed for the studied shale samples. The fracture toughness exhibits stronger anisotropy. Comparison of the results from fractured core blocks and shale cuttings shows encouraging agreement in their mechanical properties, hence intact drill cuttings may be advantageously used for nanoindentation testing in cases where intact core samples are unavailable.