LUCAS, L. C. V.; http://lattes.cnpq.br/4591012436912968; LUCAS, Luiza Cavalcante Vinhas.
Resumen:
Several factors influence the development of fault damage zones. However, the
influence of the interaction and linkage of fault segments in fault zones and its implications for
the spatial distribution of subseismic structures and characterization of permeability and,
consequently, the flow of fluid in porous media, still need further explanation. This study
analyzes the relationship between the structural context and the petrophysical properties
through the characterization and modeling of structural elements and permeability in an outcrop
located in the lower block of an boundary fault (Portalegre Fault) of the Rio do Peixe Basin,
Northeastern Brazil. Based on data acquired from two scanlines, we analyzed the cumulative
frequency of deformation bands crossing the damage zone and the protolith, and identified three
fault zones marked by three inner damage zones. The first fault zone is related to a seismic-
scale segment of the Portalegre Fault, while the second and third fault zones are associated with
two secondary subseismic faults. The spatial distribution of subseismic structures is marked by
decreases and increases in the frequency of deformation bands according to the distance from
each fault. We performed the petrophysical characterization of these fault zones and recognized
a pattern of successive increases and decreases in permeability as we move away from the fault
and approach another. These interpretations were used in the construction of permeability
models that show that permeability across the fault zone varies without a well-defined pattern
and that the impact of deformation bands on permeability is much more evident perpendicular
to the preferential dip direction of these structures. The structural complexity of the studied
fault zone and the variations in the dip direction of the analyzed segment of the Portalegre Fault
led us to the interpretation of a linking damage zone. The patterns observed here are opposed
to the distribution pattern of subseismic structure and permeability of a wall damage zone,
which comprises a gradual decrease in frequency of structure, a gradual increase in permeability
as we move away from the main fault, and an influence of the deformation on the equivalent
permeability even if parallel to the structures. Thus, this study highlights the effect of the interaction and linkage of fault terminations on the distribution of deformation bands and its
impact on permeability, clarifying some aspects associated with the structural heterogeneities
of siliciclastic reservoirs affected by fault zones