Resumo Baseado em perfis eletrorradioativos, testemunhos, amostras de calha e sísmica 3D este trabalho apresenta o arcabouço estratigráfico de média resolução das formações Feliz Deserto, Barra de Itiúba e Penedo dirigido ao zoneamento de reservatórios no Campo de Furado (Bacia de Sergipe-Alagoas). Também discute a influência da tectônica na sedimentação ao início do estágio rifte da bacia. A Seqüência J20-K5 (formações Candeeiro, Bananeiras e Serraria-andares Dom João/Rio da Serra), lacustre rasa e fluvial, passa concordantemente para a Seqüência K10-K20 (Formação Feliz Deserto, Andar Rio da Serra), compondo uma única seqüência de 2ª ordem. A Seqüência K10-K20, formada por depósitos de lago raso, registra um gradual aumento do tectonismo, com estratos passando de paralelos para divergentes. A discordância angular Pré-Aratu separa as seqüências K10-K20 e K34-K36 e marca um importante evento regional de soerguimento. Um novo pulso de subsidência, agora mais acelerada, resultou na deposição da Seqüência K34-K36. Em sua porção inferior (andares Aratu a Buracica-Formação Barra de Itiúba) possui depósitos lacustres e deltaicos que registram grandes oscilações batimétricas. As seqüências de 3ª ordem superiores retratam o preenchimento da bacia por depósitos fluviais, a última correspondendo à Formação Penedo (Eo-Jiquiá). No Andar Alagoas, um grande número de falhas pós-deposicionais de grande rejeito seccionou todo o conjunto. Contudo, existem evidências de uma discreta atuação de falhas desde o Andar Rio da Serra, formando depocentros e altos localizados, ligadas a dobras de crescimento relacionadas à iniciação e propagação de falhas em profundidade, feições essas típicas dos estágios iniciais do rifteamento.
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AbstractPilar oil and gas field, located onshore northeastern region of Brazil, had the production peak by 1985, when produced 1300 m 3 /d of oil, decreasing since then until reaching 350 m 3 /d in 1997. Forecasts at that time indicated a very low oil production of about 200 m 3 /d by year in 2002.A study was launched in 1997, strongly focused on the characterization of sealing fault planes that control the oil and gas accumulations, which resulted in the projects of deviated wells, following the fault planes. This approach has made possible to drill one single well crossing multiple sets of reservoirs, increasing the possibility of finding virgin reservoirs along trends of producing reservoirs.As a result, the oil rate has been rising since 1998, reverting the declining tendency of the period between 1985 and 1997. In 2003 the oil rate reached 1100 m 3 /d. In the period of revitalization, the OOIP has increased 50%.Nomenclature GIP = gas in place GOR = gas oil ratio OOIP = original oil in place WOR = water-oil ratio mD = millidarcies
Conversion FactorsMeters (m) = 3.281 feet (ft) Cubic meters (m 3 ) = 6.290 barrels (bbl) Cubic meters (m 3 ) = 0.028 cubic feet (ft 3 )
The oldest petroleum discoveries on the Brazilian offshore margin are in Paleogene reservoirs of the Guaricema and Dourado fields in the structural Mosqueiro Low, the Southern Sergipe-Alagoas Basin. Study of well logs and biostratigraphic data of the Eocene Series allowed its subdivision into three stratigraphic intervals representing the Ypresian, Lutetian-Bartonian, and Priabonian stages. The Ypresian depocenter is in the Dourado Trough, whereas the Lutetian-Bartonian and Priabonian depocenters are in the Vaza-Barris Trough, controlled by halokinesis in the first one and basement deformation in the others. The Ypresian interval mainly comprises retrogradational deposits related to the Early Eocene Climate Optimum. The Middle-Eocene Basal Unconformity is the main erosive feature in the Series. The Lutetian-Bartonian and Priabonian depositional systems are progradational. Their deposition is related to basement uplift due to both intense deep-water magmatism and to the Incaica Phase of the Andean Orogeny.
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