Contourite vs Turbidite Outcrop and Seismic Architectures

Abstract

The hydrocarbon exploration of oceanic depositional systems demands a better understanding of the role of bottom currents and their implications for petroleum systems such as reservoir and sealing rocks. Deep-marine bottom-current reworked sands (sandy contourites) have been recognized in hydrocarbon-bearing sands of the Kwanza Basin. Such understanding implies additional alternatives for the definition of exploration targets and prospect risk reduction. The southernmost part of the Kwanza Basin (Miradouro da Lua zone) comprises one of the best outcrops of contourites deposits, formed during the Miocene and Pliocene age. Laterally, coeval sandy deposits are found offshore Kwanza Basin along the continental margin, and have been one of the great challenges for the oil companies operating in Angola. Therefore, the aim of the current proposal is to characterize sandy contourite deposits at Miradouro da Lua and compare them with offshore deep-water sandy deposits, evaluating their conceptual and economic implication. Modern field sedimentology technique merged with reflection seismic data and other geographic information system (GIS) techniques, allow the characterization and proposal of a stratigraphic architecture diagram that explains the interaction of the deep-marine processes, especially gravitational (down-slope) and bottom current (along-slope) processes as well as its vertical and spatial association. Sonangol (Angolan State Oil Company) and Total (French Multinational Company) explore similar deposits in Block 48 in Ultra deep-sea, and they will also reactivate the exploration of the Iabe Formation in Block 4. The Tertiary Stratigraphic Architecture in Blocks 6, 7, 8, 19 and 20 are similar to the Lower part of the Miradouro da Lua zone. All these observations and data are very important to calibrate oil reservoir models.