Petroleum Geology Characteristic And Prospect Of The Onshore Sedimentary Basins In Brazil

Brazil is located in the central South America, in which the reserves and production of oil & gas increase rapidly these years, and it has become one of the major petroleum production countries. In the past few years, Brazil has begun to value the importance of onshore sedimentary basins in the country. In the paper, with the help of previous research done by predecessors, basal geologic feature and petroleum geology characteristics of different kinds of onshore sedimentary basins are studied, and the profitable areas are selected, and the distribution characteristics of hydrocarbon resources are also defined.Through the research, the tectonic setting and tectonic evolution of the basins are learned. During the Archean period, continental nucleus of South America formed. In the Proterozoic time, main cratons in Brazil formed. During the Paleozoic, when the Pangaea formed, main craton basins deposited sediments. Later, in the Mesozoic, some basins kept on depositing sediments, while others uplifted and were eroded.On the basis of evolutionary history and structural features, onshore sedimentary basins in Brazil can be divided into three kinds, Proterozoic superposed basin, Phanerozoic craton basin and failed rift basin. Only the Sao Francisco Basin is the first kind of basin. Paleozoic craton basins include the Solimoes Basin, Amazonas Basin, Parecis Basin, Parana Basin and Parnaiba Basin. Failed rift basins include Tucano Basin, Iguatu Basin, Rio do Peixe Basin, Jatoba Basin, Tacutu Basin, Araripe Basin and Taubate Basin.Profound understanding about the different kinds of basins has been acquired in the paper. Different kinds of basins possess diverse basal geologic feature and petroleum geology characteristics. Though the Phanerozoic craton basins has some common characteristics, there are discrepancy among them. However, basins locate closely on the same craton have the similar basalgeologic feature and petroleum geology characteristics.All failed rift basins has common characteristics on both aspects. The feature of Proterozoic superposed Basin is its ancient forming time and complicated evolutionary history. Based on the research above, with the help of methods of geologic analogy and analysis of exploration effects, the hydrocarbon resources capacity of different kinds of basins are evaluated. And the basins can be classified into three degrees. Solimoes Basin, Parana Basin and all failed rift basins are "excellent". Amazonas Basin, Parecis Basin and Sao Francisco Basin are "good". Parnaiba Basin is considered to be "average".