Print this pageNon Conventional Oil and Gas Generation Process in Brazilian Paleozoic Basins
Non conventional oil and gas generations process is considered to be the most important hydrocarbon generation process in the Brazilian Paleozoic Basins.
The recovered oil and gas samples present thermal evolution indexes which are normally greater than those measured on rock samples collected in areas of maximum burial of the basin, not affected by dolerite intrusions. A good agreement between oil and rock samples thermal maturation values were obtained when was considered the heat effect produced by dolerite intrusions on the source rock intervals. Case histories of the Brazilian Paleozoic basins are presented and discussed.
In the Solimões and Parnaíba basins, the regional thermal maturity data of the source rock interval indicate an immature stage before the igneous intrusions. The overall immature stage of this potential source rocks was due to its shallow burial, reaching a maximum of 3,000 m depth in the central part of the basin. Therefore, all oil and gas shows (Parnaíba Basin) or oil and gas production (Solimões Basin) are related to thermal effect caused by basic igneous intrusions. On the other hand, in the Amazonas and Paraná basins the thermal maturation was reached due to burial before the igneous intrusions, as shown by the vitrinite reflectance data: Ro < 0.60% in the basin margins to 0.60% < Ro < 1.35% toward the central part of the basin. Therefore, the noncommercial oil and gas production in these basins could be due to conventional and non conventional hydrocarbons generation processes.
AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil