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PALEOESTRUTURAS E PETRÓLEO NA BACIA DO PARANÁ, BRASIL

2002; Sociedade Brasileira de Geologia; Volume: 32; Issue: 4 Linguagem: Inglês

10.5327/rbg.v32i4.997

2317-4889

Paulo César Artur, Paulo Soares,

Geological and Geophysical Studies

Structural styles contribute decisively to the location of economic petroleum accumulations. The intracratonic basins show close relationship between major structures and the occurrence of the petroleum fields. In the Parana Basin, many doubts remain with regard to the origin and location of the different types of structures, the time they were active and the role that they played in the evolution of the basin. The methodological procedure developed has two purposes: (1) the identification of paleostructures and (2) their role in the accumulation of petroleum. For identification and mapping of the paleostructures, thickness data of five rock sequences, from Devonian to Triassic were analyzed. The sequences are bound by general maximum flood or unconformities surfaces, characterizing the forming tectonic and separately the modifying tectonic. The regional subsiding or uplifting differential process were removed by trend analysis. On the trend surface residuals, directional variographic analysis was applied and, successively, the semivariograms were modeled and the residual were interpolated by anisotropic kriging, standing out local directional anomalies of thickness. Similar procedures were adopted to investigate the distribution of the diabase sills and for Bouguer anomaly values. The data were compared with morphostructural and surface lineaments. For to investigate the relationship of the mapped structures with known petroleum accumulations, a favorability quantification method was used based on the conditional probability analysis, with some modifications. Besides paleostructures and lineaments, the areas with mature source rocks potential and reservoir protection of the two petroliferous systems were also considered as variables in the favorability analysis.It was verified that the main controls for petroleum accumulations in the Ponta Grossa-Itarare petroleum system were the Devonian northeast striking paleostrutures, reactivated until the Quaternary, and north-south striking faults during the tectono-magmatic Cretaceous event. For the Irati-Rio Bonito/Tiete petroleum system the most favorable areas are related to the paleostructures with northeast direction, active during Triassic and Cretaceous, in addition to the areas with larger cumulative thickness of intrusive bodies. The variations of thickness of the different isochronal units put in evidence the reversion of movements in the same structure in successive tectonic phases.