Stratigraphy and play models of Madagascar
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Three western sedimentary basins (Morondava, Majunga and Ambilobe) constitute the main area of interest regarding the hydrocarbon potential of Madagascar. They result from the separation of the island from Africa. Nine depositional sequences are observed in these basins leading to development of important geological formations such as Sakoa, Sakamena, Isalo, Bemaraha and Sitampiky. Moreover, nine potential reservoir rocks and four potential source rocks have been identified in the western sedimentary basins. Concerning the hydrocarbon potential, the Jurassic and the Cretaceous plays are the most attractive, respectively, in Majunga and Morondava basin. Many trapping mechanisms are found among Madagascar plays. Most of them contain rollover structures. The hydrocarbon exploration in Madagascar Island started in early 1900. It is subdivided in four rounds or phases. Seventy five wells have been drilled so far. Most of them are located onshore Morondava. The exploration led only to few discoveries of gas accumulation (Eponge, Mariarano, Sikily, and West Manambolo), two heavy oil accumulation (Maroaboaly and Tsimiroro), one light oil accumulation (Manandaza) and one tar sand deposit (Bemolanga). The past explorations showed a general lack of success. The main reason was the poor quality of available seismic data used by companies. Nowadays, Madagascar has three hundred sixty three blocks which 94% are located offshore. The country also established petroleum activities regulations with regard to environment protection. The main texts are the Malagasy Petroleum code, the charter of environment and the MECIE decree.
Master's thesis in Environmental technology