FTIR Hyperspectral Imagery: A New Method for Identifying Aragonite, Calcite, and Dolomite in Carbonate Rocks and Assessing their Formational History on the Micron Scale

Abstract

Hyperspectral imaging combines digital imaging with reflectance spectroscopy, and allows for the in-situ identification of minerals in rock samples in a non-destructive manner. The project presented here focuses on the collection and analysis of hyperspectral images from carbonate rocks for the purpose of developing a technique to identify aragonite, calcite, and dolomite on the micron scale. The information gathered using this technique will serve to better understand the microscopic alterations taking place in minerals throughout diagenesis, and the results are intended to help interpret the paragenetic history of the carbonate rocks. In summary, this presentation will showcase a new analysis method that will aid in the assessment of the quality of carbonate rocks as oil reservoirs. Long-wave infrared (LWIR) hyperspectral images were collected from polished thick sections using a Micro-FTIR instrument with a Focal Plane Array (FPA) detector, which collects hyperspectral images at a pixel size of 2.7 x 2.7 µm. Each hyperspectral image was processed and analyzed to produce a compositional map that shows the location of each mineral and/or the crystallographic orientation of individual mineral grains. Textural analyses were then performed on the compositional maps to extract grain size and textural information. The samples used in this study originated from the Western Canadian Sedimentary Basin and the Austrian Alps, and this work will serve as a foundation for subsequent studies, which will examine the feasibility of using LWIR hyperspectral imagery as an automated drill core logging tool for carbonate rocks.