Banca de DEFESA: LEONARDO CARVALHO PALHANO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : LEONARDO CARVALHO PALHANO
DATE: 22/12/2025
TIME: 14:00
LOCAL: Videoconferência
TITLE:

Fault zones with deformation bands and hydrothermal silicification: structural and petrophysical characterization

KEY WORDS:

Hydrothermal silicification; Deformation bands; Tectonic Regimes; Porous sandstones; Petrophysical properties; Geomechanical properties; Damage zone; Basin-boundary fault.

PAGES: 171
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geofísica
SPECIALTY: Geofísica Aplicada
SUMMARY:

This research investigates hydrothermal silicification and the presence of deformation bands in a damage zone, with a focus on their impact on petrophysical and geomechanical properties in sandstones. In addition, we investigate how the tectonic regime influences the development and deformation processes that give rise to deformation bands, highlighting their effects on petrophysical properties. Hydrothermal silicification and deformation bands significantly influence the physical properties and fluid flow behavior of porous siliciclastic rocks. However, their combined effects within fault zones remain poorly constrained. This study integrates structural, microstructural, geomechanical, and petrophysical analyses to investigate how silicification and deformation bands kinematics impact reservoir-quality parameters in fault zones from the BRP and Jatobá basins in northeastern Brazil. In the BRP Basin, quartz cementation is confined to a halo around the fault, defining three main silicification zones: (1) non-silicified sandstone, (2) moderately silicified sandstone, and (3) intensely silicified sandstone. Silicification, sourced from both external silica influx and feldspar dissolution, drastically reduces porosity and permeability by up to four orders of magnitude while increasing uniaxial compressive strength by one order. Cement precipitation also occurs within DBs, further decreasing pore connectivity and fluid flow capacity. In the Jatobá Basin, DBs formed under sequential extensional and contractional regimes display contrasting microstructural and petrophysical characteristics. Normal-sense deformation bands, dominated by shear and grain breakage, exhibit the highest cataclastic matrix content and the lowest porosity (0.21%) and permeability (0.41 mD). Conversely, reverse-sense deformation bands, shaped by compactional processes, retain higher porosity (2.21%) and permeability (142.4 mD). The tectonic regime thus exerts a fundamental control on deformation mechanisms, cataclasis intensity, and fluid flow behavior. Overall, the integration of silicification and deformation processes reveals that both chemical and mechanical modifications within fault zones critically affect sandstone reservoir quality, promoting significant heterogeneity and compartmentalization that must be accounted for in flow modeling of structurally complex siliciclastic systems.

COMMITTEE MEMBERS:
Externa à Instituição - CRISTIANE PAULINO DE MENEZES
Presidente - 350640 - FRANCISCO HILARIO REGO BEZERRA
Externo à Instituição - MICHAEL STRUGALE - PETROBRAS
Externo à Instituição - SÉRGIO VIEIRA FREIRE BORGES - IFRN
Interno - ***.785.944-** - VINCENZO LA BRUNA - NÃO INFORMADO