Speaker
Description
In this work, the microscopic characterization of sandstones from Morro Pelado, the upper member of the Rio do Rasto Formation (Paraná Basin, Brazil), is presented. The depositional and petrophysical characteristics of sandstones from eolian, fluvial, and floodplain environments were analyzed to gain a comprehensive understanding of the variability in pore systems. To achieve this, petrographic analyses, mercury intrusion capillary pressure (MICP), and X-ray micro-computed tomography (Micro-CT) were integrated, allowing for a multiscale evaluation of petrophysical properties. The results revealed highly heterogeneous pore systems, with total porosity ranging from 0.33% to 25.53% and estimated absolute permeability values varying from less than 3 mD to over 2,400 mD. The best reservoir quality was identified in fluvial sandstones, particularly in lateral accretion bar facies and aggradational sandy bedforms, which are associated with high primary porosity, good pore connectivity, and low cement content. In contrast, the eolian sandstones behave as unconventional reservoirs, dominated by micropores, narrow pore throats, and poor connectivity. In floodplain deposits, highly productive reservoirs were observed in terminal crevasse splay lobes, contrasting with matrix- and cement-rich units. Permeability anisotropy and the presence of dual porosity emerged as key factors controlling subsurface flow. The integrated analyses reinforce the need for applying multiscale models in the petrophysical characterization of the unit, considering the contribution of isolated microporosity and the role of sedimentary structures in directing preferential flow paths. The results highlight the potential of the Morro Pelado Member as a heterogeneous siliciclastic reservoir, with significant implications for hydrogeological studies.
| Country | Brazil |
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