Basin development and petroleum prospectivity of the hybrid turbidite-contourite system in the east Pande area, offshore Tanzania

2D seismic reflection and wellbore data were used to investigate the structure and stratigraphy of the East Pande block, offshore Tanzania, allowing an assessment to be made of basin development and the occurrence of petroleum system elements. Interpretation of the 2D seismic data showed that patterns of sedimentation were controlled by the Cretaceous- Quaternary oceanic circulation (including bottom currents) together with sea level changes and the basin-ward input of detrital material from the Tanzania mainland, resulting in the development of at least five reservoir-seal combinations. The identified reservoir rocks include hybrid turbidite-contourite deposits together with channel sands and their associated levee successions which have moderate porosity and a low shale volume. Regionally, the hybrid turbidite-contourite deposits have not been studied in detail; their presence in the East Pande area may be of interest to both local and regional researchers. Potential structural traps in the study area include faults and local folds; another trapping mechanism is provided by stratigraphic pinch-outs which are characterized in seismic data by flat spots indicative of hydrocarbon accumulations. Deep-rooted faults and erosive channel bases are interpreted to have allowed petroleum migration from underlying source rocks to shallower reservoir intervals. The mapped faults in the study area have N–S to NNW-SSE trends which conform to the Permo-Triassic fault systems of the coastal Tanzania basin. This suggests that the locations and orientations of younger faults was controlled by the pre-existing structural grain linked to Karoo (Permo-Triassic) faulting. The results of this study suggest that the East Pande area offshore Tanzania may have significant petroleum prospectivity.