Infrared spectroscopy methods in reservoir rocks analysis – semiquantitative approach for carbonate rocks

Abstract

Infrared spectroscopy methods in reservoir rocks analysis -semiquantitative approach for carbonate rocks Experimental results and methodology for mineral composition determination of reservoir rocks by means of Fourier Transformed Infrared Spectroscopy technique (FTIR) was a subject to present in the paper. The FTIR data were calibrated with use of X-ray diffraction and X-ray fluorescence (XRF) methods. This approach allows quantitative and semiquantitative analysis basing on use of statistical methods like PCR (Principal Component Regression) or PLS (Partial Least Squares) to calibrate FTIR ATR in purpose to create efficient and cost saving tool for quick screening analysis of reservoir rocks samples. The presented approach allows for calibration of FTIR ATR using statistical methods like PCR (Principal Component Regression) or PLS (Partial Least Squares) in order to create efficient and cost saving tool for quantitative and semi-quantitative analysis of reservoir rocks samples. In the paper, 18 surface carbonate rocks samples of limestone and dolomite type belonging to the Paleozoic and Mesozoic age from the Krakw-Czstochowa Upland and Main Dolomite from Fore-Sudetic Monocline were analyzed. FTIR results were qualitatively described by analysis together with tentative assignments of their molecular bonds vibrations assignments are presented and a spectra interpretation for typical carbonates associated minerals. The technical constrains of the methodology resulting from proper method calibration and metal oxide analysis limitations were also discussed. Furthermore the behavior of the PCR and PLS algorithms in case of monomineral samples was commented and the necessity of additional qualitative spectra verification was indicated in this case for the final assessment of quantitative data quality. The quantitative results of FTIR analysis were compared with X-ray diffraction (XRD) quantitative data, part of them has been used as validation data. The accordance of the data series was better than 6% for each analyzed mineral phases excluding the outliers indicated by the analytical algorithm. The method was also successfully applied to the quantitative analysis of shale rocks, however, this part of the research will be presented in a separate paper.