Evaluation of the potential generator Aptian-Albian oil section of the Sergipe Basin, integrating palynofacies and organic geochemistry analyses

Data presented in this investigation refer to studies integrating palynofacies and organic geochemistry analyses that were performed on 51 samples of PEC-41-SE-9 well, located in the Sergipe Basin, Eastern Brazilian continental margin. It was evaluated the potential for oil generation, identifying the type and degree of maturation of the organic matter. Optical analyzes show that the organic matter is composed in greater proportion by amorphous organic matter in good preservation, with high fluorescence. It also presents a 67% average concerning the total composition of the kerogen. The phytoclasts usually are well preserved in almost all the section. The palynomorphs are composed of an association, predominantly, of spores and pollen grains of genus Classopollis, featuring a predominantly arid to semi-arid climate environment at deposition time. Presence of the dinoflagellate in the upper section displays the first marine ingressions that happened in the end of Aptian. Based on the qualitative and quantitative results of kerogen, it was possible to characterize three distinct palynofacies, in which the palynofacies I had the best features for quality and preservation of organic matter. The results show total organic carbon values up to 6.39% and Rock-Eval pyrolysis data pointed to the type II kerogen rich in organic matter suitable for the formation of hydrocarbon accumulations. The hydrogen index is found between 200 and 550 mg HC/g of total organic carbon, which shows good potential for oil and gas generation. Spore color index data conclude that the organic matter is found predominantly on the immature maturation phase, with SCI values of 4.0 to 4.5, corroborating with data of maximum temperature, of up to 432°C.

Sergipe Basin; organic geochemistry; petrography; palynofacies; petroleum geology; hydrocarbons