Variação espacial e análise topológica em bandas de deformação na Bacia Rio do Peixe, Nordeste do Brasil : impacto das conexões na permeabilidade.

Abstract

Topological analysis can help in structural characterization, as well as in understanding the influence of connections on flow properties in reservoir rocks affected by deformation bands. In the present work, we used a three-dimensional exposure (wall and floor) of a fault zone in the Rio do Peixe Basin, Northeastern Brazil, to evaluate the influence of connections on permeability. From detailed structural mapping, we analyze the topological pattern of deformation bands. Additionally, we performed in situ permeability measurements. The combination of structural data with permeability data allowed us to investigate the influence of the connectivity of a deformation band network and its impact on fluid flow properties in a fault zone. The results showed the variation of the connectivity pattern along the fault zone, with the core presenting Y>I>X pattern and the damage zone Y>X>I. We observed that in the core, the highest permeability values were recorded at I - nodes, followed by Y- and X- nodes. In the damage zone, there is an anisotropic variation, where the exposure wall registers higher permeability for I - nodes and secondarily for Y- and X- nodes, while on the floor the highest permeability was recorded at I - nodes and secondarily at X- and Y- nodes. In addition, new nodes (with five and six branches) formed from the crossing of two fault systems formed in different tectonic phases of the basin (sin-rift and post-rift) were identified. This study contributes with new perspectives about the influence of deformation band connections on permeability in a fault zone. This information may imply the modeling and simulation of siliciclastic reservoirs affected by fault zones, because possible to assess the impact of connectivity variation on fluid flow.