Caracterização da matéria orgânica potencialmente geradora de petróleo e seu posicionamento bioestratigráfico, com base em palinologia e palinofácies da Formação Pojuca - Bacia do Recôncavo

• Autor(a) principal: Portela, Helena Antunes
• Data de Publicação: 2012
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/7011
• topic: Palynology; Palynofacies; Bioestratigraphy; Recôncavo Basin; Palinologia; Palinofácies; Bioestratigrafia; Bacia do Recôncavo; CNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOLOGIA

This study presents an integrated study encompassing palynological, palynofacies and organic geochemistry (particularly Total Organic Carbon [TOC] and pyrolysis) investigations. It was based on analysis of the organic content from 173 core samples of the Pojuca Formation collected from the 9-FBA-65-BA e 9-FBA-79-BA wells drilled in the Recôncavo Basin. The identified palynoflora suggest a predominantly continental depositional paleoenvironment, composed by a fluvial deltaic-lacustrine system in a hot and arid climate. Comparisons with overseas palynofloras support the hypothesis that this assemblage belongs to the Dicheiropolis (ex W.A.S.A) palynofloristic belt. Fift six palynomorphs species have been identified and partially illustrated. The identification of the Dicheiropollis etruscus and Vitreisporites pallidus species allows inserting these strata in the Vitreisporites pallidus Biozone, which is considered as Aratu in age. By observing optical microscopy transmitted white and ultraviolet light, it was possible to identify three distinct Palynofacies, taking into account the types and degree of preservation of organic matter. The quantitative analysis of organic content show a mixture of allochtone organic material, represented by pollen grains, spores and indigenous phytoclasts (woody tissue) and dominated by amorphous organic material. The highest observed fluorescence are present in the Palynofacies 1 and 2, indicating a more reducer conditions at the sedimentation environments of these strata. The SCI data present maturation values 5 for well 9 FBA-65-BA and 6.5-7 to the well 9 FBA-79-BA, inserting the organic material content in the hydrocarbon generation window. Based on the results of Rock-Eval pyrolysis, it was found that the Pojuca Formation samples is constituted by overwhelming majority of organic matter type II, rich in hydrogen and oxygen-poor, corresponding to a type of organic matter for the generation of liquid and gaseous hydrocarbons. Levels 3 and 4, belongs to the Palinofácies 1 and 2 of the 9 FBA-79-BA well and present TOC values greater than 1.5%. Considering the Rock-Eval pyrolysis data, it s possible to affirm that these ranges are potential generator, since S2 values exceed 5.0 mg HCg, and IH values surpass 200 reaching 600.