Abstract An automatic approach for analyses of Raman spectra of dispersed organic matter in diagenesis is proposed in this work. The need for a reproducible method of thermal maturity assessment by means of Raman spectroscopic analyses on the organic matter is essential for the development of this technique as a robust support in organic petrographical analyses. The new method was tested on concentrated kerogen derived from a set of 33 samples that originated from cuttings from a 5000 m-thick section drilled in offshore Angola. The proposed method can be applied separately in the D and G bands regions of the Raman spectra, and uses a fitting approach based on asymmetrical Gaussian deconvolution and on the measurement of the integrated area. Results from this work demonstrate that Raman parameters carried out by the new methods reflect the increase in aromaticity in kerogen in diagenesis. Finally, two parametric equations have been proposed to correlate Raman parameters and thermal maturity: the first is for the thermal maturity interval between 0.3 and 1.5% R o ; and the second has a higher precision of between 1.0 and 1.5% R o . The two equations are the result of a multi-linear regression based on robust correlations between Raman parameters and vitrinite reflectance (R o %).

Abstract In West Africa, the presalt is an established play since the 1950s. Even so, only recently has the expectations for a potential extension of the Brazilian Santos/ Campos basins proven presalt carbonate play boosted spectacular interest in the Kwanza basin (south Angola). The “Sag carbonate Play” has gained most of the attention and promises to be the real “sweet spot” of future presalt exploration, at least in Angola. Moreover, new technologies and ideas allow us to reexamine the great complexity of the presalt play on the historically explored trend (onshore and in conventional waters) along the whole West African margin.