Preliminary geochemical investigation of some crude oils from the Niger Delta Basin Nigeria

Geochemical studies on twenty-eight crude-oil samples from nine oilfields, onshore-offshore parts of Niger Delta Basin, were performed to classify the oils into various classes, determine the bulk compositions of oils, organic matter inputs, source depositional environment, thermal maturation, and in-reservoir processes, for petroleum system prediction. The oils were fractionated into individual bulk compositions of saturates, aromatics, resins, and asphaltenes (SARA), using the Iatroscan thin-layer chromatography-flame ionization detector (FID) technique. Column chromatography was utilized to separate the saturates, and were further analyzed with gas chromatography-FID for n-alkane and acyclic isoprenoid distributions. SARA results, classified the oils into: paraffinic (>72%Hc, sat/arom: 2.61-3.68); paraffinic-naphthenic (63-70%Hc, sat/arom:1.77-2.31) and aromatic-naphthenic/aromatic-intermediate (