Improved visualization of heterogeneity within shales: Colour contoured maps constructed from large area high-resolution SEM montages

Large area high-resolution scanning electron microscopy montages are often taken of shales to characterise variability in composition. Although resolution can be superb in such montages, details can be hard to ascertain from the full images, and observations made from single high-resolution tiles are difficult to place within the context of the whole sample. This paper presents a new method that utilizes the individual images collected from such montages, to produce contoured coloured maps to better visualise heterogeneous distributions within shales. The method repurposes previously collected backscattered electron images, through batch image analysis processing, to quickly extract numerical data and produce coloured maps of a range of important parameters. Examples of maps for mean gray value, pyrite, quartz, calcite, porosity and permeability distribution are illustrated and discussed. Such maps allow variability in distribution to be graphically displayed in a fashion that clearly displays any heterogeneity at the millimetre to centimetre scale, as well as numerically defining any variation present.