Brittleness of shales: Relevance to borehole collapse and hydraulic fracturing

Brittleness is often used to guide selection of fracturing targets in unconventional reservoirs. There are however several definitions of brittleness parameters, with varying degree of scientific basis. Using parameters which lack scientific basis to solve operational problems that require fundamental physical understanding is a risky engineering practice. It is therefore important to identify to what extent and in case how brittleness can be...