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

Area of Science:

• Geochemistry
• Materials Science
• Spectroscopy

Background:

• Raman spectroscopy is used to determine carbonaceous matter (CM) maturity in geologic samples.
• Current methods rely on mathematical decomposition of Raman bands, introducing uncertainty due to variations in methods, software, and user interpretation.
• Spectra pre-treatment and spectrum-by-spectrum analysis can lead to bias and wide uncertainty ranges.

Purpose of the Study:

• To propose an alternative chemometric method for assessing CM maturity using Raman spectroscopy.
• To overcome the limitations of traditional methods, such as mathematical band decomposition and the need for spectra pre-treatment.
• To provide a more robust and less biased approach for comparing CM maturity and H:C ratios.

Main Methods:

• Utilized principal component analysis (PCA) on the entire spectral range of Raman data.
• Applied a chemometric approach that considers the whole spectrum, rather than specific regions or band decompositions.
• Avoided the requirement for spectra pre-treatment, simplifying the analysis process.

Main Results:

• The proposed PCA method effectively groups coal standard samples by maturity.
• The method allows for comparative analysis of different carbonaceous matter samples regarding their maturity and H:C ratio.
• Demonstrated that considering the entire spectrum circumvents uncertainties associated with band decomposition techniques.

Conclusions:

• The developed chemometric method offers a reliable alternative for assessing carbonaceous matter maturity using Raman spectroscopy.
• Principal component analysis (PCA) provides a robust framework for comparative maturity assessments without complex spectral manipulation.
• This approach minimizes user-induced bias and uncertainty, enhancing the reliability of geochemical maturity studies.