Petroleum potential from Permian-Triassic strata of the Maniamba Basin, Mozambique: A preliminary characterisation

In order to further our understanding regarding the petroleum potential of the Maniamba Basin, Mozambique, organic rich sediments from four outcrops were investigated. Organic-rich shales, claystones, sandstones and siltstones were sampled for geochemical organic analyses that included Total Organic Carbon (TOC), and Rock Eval Pyrolysis. The pyrolysis analysis showed that the TOC ranges from good to excellent, thus indicating a potential for hydrocarbon generation. Based on the hydrogen index (HI) versus oxygen index (OI) diagram, most samples were classified as kerogen type III or IV, however, a mixed type II and III was also observed. These data suggest that the Organic Matter (OM) is of terrigenous origin with the occurrence of organofacies C, CD and D. The majority of the studied samples are found to be at mature to overmature stages. The overmaturation of the OM may be associated with tectonic events during the process of basin subsidence, and close proximity to igneous intrusions. Further, an indigenous nature of the hydrocarbon has been identified. Similar organic matter properties of the studied sections are correlatable with those from Moatize Minjova, Sanangoé-Mefidezi (Mozambique), Ruhuhu (Tanzania) and the Main Karoo Basin in South Africa. Overall, the results of this study suggest a good potential for gas.