Characterization of turbidites from the Urucutuca Formation of the Almada Basin, Bahia, Brazil, using seismic and petrophysical well log data

摘要

Fifty seismic lines and petrophysical logs from 15 wells were used to characterize the reservoirs of the Urucutuca Formation palaeo-canyon in the Almada Basin. The resulting 3D geological model allowed the Urucutuca Formation and its turbidite canyons to be evaluated as potential petroleum reservoirs. The log analyses indicate great variations in effective porosity (reaching a maximum value of 25%) and the clay content of the sandstones (ranging from less than 5% to greater than 40%). Other relevant factors in this context are the sandstone and calcarenite thicknesses which reach 243 m and 93 m, respectively. Information obtained from the seismic lines indicates that there was a strong tectonic influence on the geometry of the Almada Canyon, resulting in the formation of two canyons that join in the offshore portion of the basin. The connection between the canyons has been observed to extend from the continent to 27 km offshore. The results indicate that the Urucutuca Formation is an important horizon for future oil exploration, having favourable genetic and petrophysical characteristics.