Banca de DEFESA: CRISTIANE PAULINO DE MENEZES SANTOS
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.DISCENTE : CRISTIANE PAULINO DE MENEZES SANTOS
DATA : 15/07/2019
HORA: 15:00
LOCAL: Auditório do Departamento de Geologia
TÍTULO:
Hydrothermal silicification along faults affecting carbonate-sandstone units and its impact on reservoir quality, Potiguar Basin, Brazil
PALAVRAS-CHAVES:
fluid flow, hydrothermal silicification, fault zone, reservoir analogue
PÁGINAS: 100
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Geociências
SUBÁREA: Geologia
ESPECIALIDADE: Sedimentologia
RESUMO:
We analyzed hydrothermal silicification along the Afonso Bezerra strike-slip fault system in the Potiguar Basin, Equatorial margin of Brazil, to assess the role of Si-rich fluids on fault geometry, properties, and evolution. The fault cut across the whole basin, including its crystalline basement, a late Cretaceous siliciclastic and a lower carbonate unit, and a Paleogene-Neogene upper carbonate unit. Intense fault-controlled silicification caused by upward migration of hydrothermal fluids and their diffusion occurred repeatedly. Fault zone is characterized by multiple events of syntectonic (dynamic) silicification with hydraulic brecciation at all scale in the fault core and static silicification, where no lattice orientation or deformation occurred, in the damage zone. In the carbonate units, silicification resulted in the complete replacement of the carbonate mineralogy by quartz, chalcedony and opal, and the Si02 content increased from 3-15% in the host carbonate units to as much as 94-97% in the silicified portions of the fault. The silicified fault zone presents an abrupt widening from 150 m in the siliciclastic unit to as much as 800 m in the lower carbonate unit. The matrix of the siliciclastic unit exhibits porosity reduction from 27% to 4%. By contrast, the matrix porosity of the lower carbonate unit exhibits primary porosity around 5-10%, which is either reduced to ~less than 1% or increased to more than 15% in the silicified zone. In both carbonate units,centimeter-scale vuggy porosity along fractures occurs in the silicified zone. This anomalous vuggy porosity could serve as reservoir pore space. The special proximity and chronology of basalt intrusions along and at the vicinity of the fault suggest the volcanic intrusion play an important role in silicification. This work may shed light on the origin and likely geometry of the fault-controlled silica distribution causing heterogeneities within carbonate and siliciclastic reservoirs.
MEMBROS DA BANCA:
Externo à Instituição - VICENZO LA BRUNA
Externo à Instituição - JAZIEL MARTINS SA - UFRN
Presidente - 277437 - MARCELA MARQUES VIEIRA
Externo ao Programa - 347536 - NARENDRA KUMAR SRIVASTAVA
Externo à Instituição - SÉRGIO VIEIRA FREIRE BORGES - IFRN