Source Rocks of the Onshore Kwanza Basin - A New Geochemical Approach

The Onshore Kwanza Basin can be faced as a complementary sector in the Oil Scenario, considering the new crisis in the Oil Market. In fact, bearing in mind the already known resources, the Onshore can be considered the next promising exploration area, which is less expensive and the oil production would be quicker than expected in the offshore areas. The main purpose of this paper is to present a pioneer surface organic geochemistry study developed at a regional scale by Sonangol to characterize and identify potential source rocks. The 1/250 000 scale geological maps (Sonangol/Total 1987 and Sonangol/Obrangol 2015) were used to support the sampling programme developed. To implement this work were involved field sampling and laboratorial analyses. A number of 800 outcrop samples were collected in the entire basin, which were strategically selected considering the stratigraphic framework. The methods and analyses selected for the present study were palynostratigraphy, optical organic maturation and organic geochemistry (TOC, Pyrolysis, carbon stable isotopes, gaseous chromatography/mass spectrometry). Results suggest that some shale dominated layers of Quifangondo, Cunda/Gratidão, Teba and Cabo Ledo Formations, when compared to the rest of the analysed formations, present the highest potential source rocks, in specific areas of the basin.