GEOCHEMICAL CORRELATIONS BETWEEN PETROLEUM SAMPLES FROM THE POTIGUAR BASIN AND DEFINITION OF THEIR POSSIBLE GENERATING ROCKS

Eight petroleum samples from Potiguar Basin were submitted for determination of saturated biomarkers by gas chromatography (fingerprint), liquid chromatography (saturates, aromatics, resins and asphaltenes), gas chromatography-mass spectrometry (GC-MS), nickel and vanadium by high resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). The geochemical parameters provided information on type of depositional paleoenvironment in which organic matter that gave rise to each oil sample and level of thermal maturation reached by generating rocks that make up the Potiguar Basin were deposited. The relationships between the stable isotopes of carbon (δ13C) and between Ni and V concentrations of each petroleum sample were also evaluated. The evaluations separated for oil samples into two distinct groups. Group 1 formed by samples P1, P2, P5 and P8, with characteristics of generating rock that was deposited in a marine hypersaline environment. Group 2 composed of samples P3, P4, P6 and P7 with freshwater lacustrine depositional paleoenvironment, which were elucidated through the geochemical parameters studied. The hierarchical cluster analysis was presented as promising chemometric tool for characterization of petroleum samples in the according to their origin of the generating rock by ratio parameters of hopane/sterane , tetracyclic polyiprenoids/diastereomers and diastereos R+S/cholestane R+S.