Tectono-stratigraphic control of the generation, migration and trapping process in the Irati-Rio Bonito Petroleum System, Santa Catarina coalfield region
Abstract
The work aims at the geological characterization of the structural and stratigraphic system responsible for the petroleum oils that occurs in Rio Bonito Formation, in the coalfields of Santa Catarina, eastern edge of Paraná Basin, in the municipalities of Lauro Muller, Siderópolis and Criciúma, state of Santa Catarina. Currently, it has been speculated that the geochemical signature of this oil is related to the Irati Formation associated with an unconventional model generation, by the thermal maturation of diabase intrusion, due to source rock insufficient burial. As the Irati is stratigraphically positioned above the Rio Bonito Formation, the system is associated to a strong structural control for the migration model. The preparation of a geological map for the area that includes the geological field data, aeromagnetometry map data and drillhole information has enabled to a deep understanding of tectonic-stratigraphic region. Geological cross-sections showed the presence of faults that caused a system of grabens and horsts related to NE-SW faults and secondarily E-W, mapped in the study area, that may have positioned the Irati Formation alongside or below the Rio Bonito Formation. Cronostratigraphic sections made it possible to recognize seals, structural and stratigraphic traps associated with the petroleum system Irati-Rio Bonito. The geochemical analysis of the oil (biomarkers) and isotopes collected at the Rio Bonito Formation, indicated that they are associated with the Assistência Member shales (Irati Formation). The structural framework and studied oils in the region suggest that the migration occurred from south-west to northeast along the NE-SW fault system that was generated previously the basalt floods associated with the Serra Geral Formation.
