Geochemical evaluation of crude oils using nuclear magnetic resonance spectroscopy

Abstract Nuclear magnetic resonance (NMR) technique has been used for the characterization and geochemical studies of oils and bitumens. Structural parameters like percentage of aromatic proton (PAP), carbon chain length, alkyl group percentage, etc., have been used for better understanding the thermal maturity and genetic classification of Cambay Basin crude oils. These structural parameters also provide information about the degree of thermal maturity of biodegraded oils. Thermally more evolved oils have a PAP value between 15–23 and an average carbon chain length of 4 carbon atoms, whereas oils of low maturity have a PAP value between 7 and 10 and a carbon chain length of 7 carbon atoms. PAP correlates positively with other maturity parameters—vitrinite reflectance ( VR 0 ) and subsurface temperature of the studied sediment samples.