A new methodology for kerogen maturity estimation based on Raman spectroscopy and chemometric analysis

Diverse criteria or parameters have been cited as tools to determine the maturity of carbonaceous matter (CM) found in geologic samples using Raman spectroscopy. However, these approaches involve the mathematical decomposition of Raman bands which can vary with the specific method, the software employed, or even the individual user. Data should be treated spectrum by spectrum and a similar spectroscopic pre-treatment should be applied to the whole dataset. All these factors affect the final result and can introduce a wide uncertainty and bias. We propose an alterna-tive chemometric method that avoids these sources of uncertainty by considering the entire spectrum, not just certain regions, while allowing specific regions of interest to be defined. Moreover, spectra pre-treatment is not required. We employ principal component analysis (PCA) across the whole range of spectra. While the method does not provide an absolute maturity value, it allows comparison of different CM in terms of maturity or H:C ratio. In the analysis of coal standards, samples were grouped by maturity.

Automated summary

Various criteria or parameters have been proposed to determine the maturity of carbonaceous matter (CM) in geological samples using Raman spectroscopy. However, these methods involve the mathematical decomposition of Raman bands, which can be influenced by the specific method, software, or user. Pre-treatment of spectra and the use of chemometric methods, such as principal component analysis (PCA), can reduce uncertainty and bias. By considering the entire spectrum, not just specific regions, this approach allows for the comparison of CM based on maturity or H:C ratio.