Eleventh International Congress of the Brazilian Geophysical Society LOWER CRETACEOUS TURBIDITE RESERVOIR CHARACTERIZATION IN THE SOUTH PART OF THE RECÔNCAVO BASIN, BRAZIL Márcia Karam*, José Ayrton Estrella Braga*, Luiz Fernando Figueiredo*, Felipe Dias*, Roberto Porto* and Christian Buck** * Queiroz Galvão Óleo & Gás, ** Brasoil do Brasil Copyright 2009, SBGf - Sociedade Brasileira de Geofísica This paper was prepared for presentation during the 11 th International Congress of the Brazilian Geophysical Society held in Salvador, Brazil, August 24-28, 2009. Contents of this paper were reviewed by the Technical Committee of the 11 th International Congress of the Brazilian Geophysical Society and do not necessarily represent any position of the SBGf, its officers or members. Electronic reproduction or storage of any part of this paper for commercial purposes without the written consent of the Brazilian Geophysical Society is prohibited. ____________________________________________________________________ Abstract The Maracangalha Formation was mapped using 2D and 3D seismic data on BT-REC-8 Block of the Recôncavo Basin. Within the block area the Maracangalha Formation is present as the Pitanga and Caruaçu members. Geological and petrophysical studies were conducted on the Caruaçu Member sandstones as they are commercially important in the area. The geological model of Caruaçu Member used in this paper was based on Jacuípe and Miranga Profundo field analogues where turbidite channel and lobe deposits form hydrocarbon bearing resorvoirs. Porosity and permeability within the Caruaçu turbidite sandstones at BT-REC-8 form the reservoirs of the Jaó discovery field. The Jaó Field, discovered by 1-QG-4 well drilled by Queiroz Galvão Óleo & Gás and Brasoil do Brasil in 2007, has potential resources estimated between 1,1 and 3,6 MMBO over a 9 km 2 area. Introduction The BT-REC-8 Block was acquired during the fourth ANP Round of bidding in 2002. It is located in the south compartment of the Recôncavo Basin (Fig. 1) and is situated on the hanging wall of the Mata-Catu Fault. The block, towards west is delimited by Massapé, Caruaçu and Taquipe fields. The presence of these fields and the source depocentre to the southeast confirm the presence of hydrocarbons in the area (Fig. 2). In the Recôncavo Basin, the hydrocarbon migration process usually occurs through normal faults and discontinuities. This appears to be the case at Jaó Field. The trapping mechanism at the Jaó Field is a combination of structure and stratigraphic factors. The Caruaçu Member reservoirs found in the 1-QG-4 well are characterized by sandstone layers between 5 and 10 m thick interbedded with shales. The sandstones are clean, with low clay content and show a fining upward sequence with variable lateral thickness and discontinuity. At the base of the Maracangalha Formation package, the Pitanga Member sandstone is found. It exhibits, a blocky gamma ray character over its entire thickness. It has a maximum thickness of approximately 370 m and is interpreted as reworked sandstones deposits (Fig. 3). The stratigraphic correlation between three wells(1-QG-3, 1-QG4 and 1-TI-4) in the Jaó Field area made the interpretation of Caruaçu turbidite deposits in the area possible (Fig. 3). In the 1-QG-4 well area the sandstones are not fractured and tend to have good to fair porosities and low permeabilities. The equivalent sandstones found in the Jacuípe and Miranga Profundo fields have enhanced permeability and reservoir quality as a result of fault and drape related fractures. Methodology Reprocessing of 3D seismic data by Geo-x in Calgary, Canada improved Caruaçu Member resolution and made it possible to map a stratigraphic/structural trap on the block. Geological information was tied to the seismic data by check shot information obtained from the 1-QG- 4 well. Stratigraphic correlation of the 1-QG-3, 1-QG-4 and 1-TI- 4 wells in the area used sequence stratigraphy concepts. The sequence datum used is a continuous shale layer that occurs in the clay zone in the three wells where a correlatable gamma ray interval was picked. The hydrocarbon presence in the 1-QG-4 well was detected in the well cuttings and gas detector measurements. Formation tests and production tests were then conducted on these intervals. Oil in place volume estimates were achieved through a deterministic distribution using area, porosity and water saturation as variables. Seismic Data Seismic interpretation over the area was based on a time data set. A time-depth conversion was performed by