Banca de QUALIFICAÇÃO: DANDARA DAVID BRAGA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : DANDARA DAVID BRAGA
DATE: 28/11/2022
TIME: 10:00
LOCAL: Departamento de Petrologia e Geotectônica
TITLE:

Volcanic facies architecture in the Badejo Field, Campos Basin

KEY WORDS:

Campos basin, volcanic facies architecture, basalts

PAGES: 110
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geologia
SPECIALTY: Petrologia
SUMMARY:

Campos Basin is located in SE Brazil, being among the most productive sedimentary basins regarding hydrocarbons in the country. Hydrocarbon production from volcanic reservoir rocks in Brazil is rare but it was succesfully achievied in the Badejo field, Campos Basin. The Badejo field is located southern Campos, about 75 km offshore SE the São Tomé Cape, in the continent, under 85 m of sea water. The volcanic rocks are basalts of the Cabiúnas Formation, related with the voluminous flows that erupted prior and during the Gondwana breakup in the Early Cretaceous. Despite their widespread distribution in Campos Basin, volcanic facies architectures and studies of physical volcanology regarding the Cabiúnas basalts are still scarce. The study area is 12 km2 and includes about 650 m of magmatic rocks of the Cabiúnas Formation. The aims of the study was to discriminate volcanosedimentary sequences in detail and to represent their distribution using concepts of physical volcanology and architecture of volcanic facies. The methods applied included usual systematics in petrological research as well as volcanic stratigraphy, with macroscopic description of well cores, optical microscopy and lithogeochemical analysis. The cores recovered from wells BD-02, BD-04 and BD-08, drilled in the Badejo field, provided an excelent material to reconstruct the 3D geometries of the volcanic flows in the area. Two Compound-braided flows (Sequence 1 and 3) and a Tabular-classic flow Sequence (Sequence 2) were identified in the studied wells. Morphologies or lithofacies associations include classical, hummocky, sheet and rubbly pahoehoe lavas. Coherent, brecciated, peperites and intertraps lithofacies were also described in the well cores. Effusion rates, based on the thickness of the lobes, indicated that pulsed inflation was the major process in Sequence 3. Minimum emplacement duration is estimated in 3 and 7 months for wells BD-2 and BD-04, respectively. Estimated D values for hummocky lavas are higher than those for classical pahoehoe lavas, pointing to porosities and permeabilities adequate to potential plays. Lithogeochemical data revealed a good correlation in the upper part of Sequence 3 indicating eruption from the same emission center. The compound-braided Sequence 2 may have reach 89.5 m, much thicker than the 40 m thick tabular-classical lavas in Sequence 3. The volcanic paleoenvironment corresponds to subaerial lava flows with humidity in all sequence. This information can be of great importance for better characterization of potential offshore volcanic reservoirs within Campos and other sedimentary basins associated with the Gondwana breakup in SE Brazil.

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