Deep water depositional system in Rovuma Basin, East Africa and its bearing on hydrocarbon exploration

Based on the high-resolution 3D seismic data, in addition to well logging data and drilling data, the deep-water deposits in the Rovuma Basin of East Africa are systematically studied in this paper. According to the seismic facies of the deep-water depositional bodies, the architectural elements of the system, such as the canyon, channel, overbank, lobe, mass-transport deposits (MTDs) and condensed layers are recognized, and the seismic identification criteria established, while the lithologic, electrical and reservoir-physical characteristics are analyzed and summarized. Sandstones are usually low in gamma ray (GR) and high in electrical resistance (RT). The GR curve of thick sandstone is “boxlike” and the sandstone sequence intercalating mudstone layers in superimposed “bell-shape”. The compaction of reservoirs is rather weak and the primary intergranular pores are relatively developed, and, therefore, medium to high porosity and permeability are widely developed. The overall study of reservoir forming conditions suggest that there occur a good hydrocarbon forming system with channel and lobe turbidite sandstone as reservoirs, condensed section and overbank mudstone as caprocks, and levee and MTDs for lateral plugging. The model has significant implications for deep-water oil and gas exploration.