Infrared Hyperspectral Mineral Mapping of Sedimentary Drill-Core

We have investigated the feasibility of using lab-based short-wave infrared (SWIR) hyperspectral imagery to identify and map the mineralogical composition of selected sedimentary drill core from the subsurface of the Netherlands. We aimed at i) identifying and mapping spectrally active minerals, such as white mica, clay and carbonate minerals and ii) the quantification of clay content in the core and their detection limits.
Twenty-six core samples from four wells located offshore of the Dutch coast in the Southern Permian Basin were imaged with a SWIR hyperspectral scanner. The images were processed to interpretable products, such as spectral parameters and classified maps that enhanced the variation in mineralogical composition. Results showed that nearly all image-spectra of all core samples were dominated by white mica (muscovite-illite) and clay minerals (kaolinite-dickite and illite-smectite).
The total clay content (the sum of white mica and clay minerals) could be estimated from the SWIR hyperspectral data by comparison with compositional data of previous mineralogical studies for Wintershall Noordzee B.V. (with QEMSCAN and SEM methods) on the same core samples. Regression models showed that the total clay content can be modeled from the depth of clay features near 1400 and 2200 nm with a mean error of 4.1 % in the preferred regression model.
We conclude that laboratory-based SWIR hyperspectral imaging at 200 μm provides a useful, non-destructive method to identify and map the white mica, clay and carbonate minerals in the investigated sedimentary drill core.