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Multivariate analysis of ATR-FTIR spectra for assessment of oil shale organic geochemical properties

October 1, 2013

In this study, attenuated total reflectance (ATR) Fourier transform infrared spectroscopy (FTIR) was coupled with partial least squares regression (PLSR) analysis to relate spectral data to parameters from total organic carbon (TOC) analysis and programmed pyrolysis to assess the feasibility of developing predictive models to estimate important organic geochemical parameters. The advantage of ATR-FTIR over traditional analytical methods is that source rocks can be analyzed in the laboratory or field in seconds, facilitating more rapid and thorough screening than would be possible using other tools. ATR-FTIR spectra, TOC concentrations and Rock–Eval parameters were measured for a set of oil shales from deposits around the world and several pyrolyzed oil shale samples. PLSR models were developed to predict the measured geochemical parameters from infrared spectra. Application of the resulting models to a set of test spectra excluded from the training set generated accurate predictions of TOC and most Rock–Eval parameters. The critical region of the infrared spectrum for assessing S1, S2, Hydrogen Index and TOC consisted of aliphatic organic moieties (2800–3000 cm−1) and the models generated a better correlation with measured values of TOC and S2 than did integrated aliphatic peak areas. The results suggest that combining ATR-FTIR with PLSR is a reliable approach for estimating useful geochemical parameters of oil shales that is faster and requires less sample preparation than current screening methods.

Citation Information

Publication Year 2013
Title Multivariate analysis of ATR-FTIR spectra for assessment of oil shale organic geochemical properties
DOI 10.1016/j.orggeochem.2013.07.007
Authors Kathryn E. Washburn, Justin E. Birdwell
Publication Type Article
Publication Subtype Journal Article
Series Title Organic Geochemistry
Series Number
Index ID 70074336
Record Source USGS Publications Warehouse
USGS Organization Central Energy Resources Science Center

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