Chromatographic study of Spanish shale oils

Abstract

A chromatographic study of the distillates obtained from selected Spanish oil shales has been carried out and the results has been related to the organic constituents identified by microscopy and the measured vitrinite reflectance. The oil shales differ in geological age, depositional environment, source location and degree of maturity. The chromatographic profiles have shown that unrelated samples of different origin (lacustrine and marine) had similar and peculiar alkane/alkene fingerprints with odd n-alk-1-ene dominance and even n-alkane dominance in the medium boiling point region. This might be attributed to a common bacterial source or more likely to a common diagenetic route generating similar products from an originally different material. All the lacustrine samples containing Botryococcus have shown an odd predominance of n-alkane in the high boiling point region and also relatively large amounts of long paraffins regardless their maturity. The hopanes identified in the pyrolysates indicated higher concentration of the less stable configurations than that found in the extracts and allowed the establishment of differences in maturity for samples with a similar maturation degree as determined by vitrinite reflectance.