Tectonic and Stratigraphic Evolution Based on Seismic Sequence Stratigraphy: Central Rift Section of the Campos Basin, Offshore Brazil

Renata Dos Santos Alvarenga,Karin Goldberg,Patrycia Leipnitz Ene,Claiton Marlon Dos Santos Scherer,David Iacopini,George Pantopoulos,Juliano Kuchle

doi:10.3390/geosciences11080338

Renata Dos Santos Alvarenga, Karin Goldberg + Show 5 more

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https://doi.org/10.3390/geosciences11080338

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Abstract

The rift section of the Brazilian basins represent the sedimentary record associated with the first stages of Gondwana break-up in the Early Cretaceous phase (Berriasian to Aptian). The rift succession of the Campos Basin constitutes one of the main petroleum systems of Brazil’s marginal basins. This interval contains the main source rock and important reservoirs in the Lagoa Feia Group deposits. The Lagoa Feia Group is characterized by siliciclastic, carbonate and evaporite sediments deposited during the rift and post-rift phases. Despite the economic relevance, little is known in stratigraphic terms regarding this rift interval. To date, most studies of the Lagoa Feia Group have adopted a lithostratigraphic approach, while this study proposes a tectonostratigraphic framework for the deep-rift succession of the Campos Basin (Lagoa Feia Group), using the fundamentals of seismic sequence stratigraphy. This work also aims to establish a methodological and practical procedure for the stratigraphic analysis of rift basins, using seismic data and seismofacies, and focusing on tectonicstratigraphic analysis. The dataset comprised 2D seismic lines, core and lithological logs from exploration wells. Three seismic facies were identified based on reflector patterns and lithologic data from well cores, providing an improved subdivision of the pre-, syn- and post-rift stages. The syn-rift stage was further subdivided based on the geometric patterns of the reflectors. Tectonics was the main controlling factor in the sedimentary succession, and the pattern and geometry of the seismic reflectors of the syn-rift interval in the Campos Basin allowed the identification of three tectonic systems tracts: (i) a Rift Initiation Systems Tract; (ii) a High Tectonic Activity Systems Tract and (iii) a Low Tectonic Activity Systems Tract.

Highlights

The Campos Basin is one of the largest hydrocarbon-producing basins of the Brazilian margin [1], with substantial oil reserves first discovered in its shallower part during the
All the stratigraphic units bounding surfaces are related with abrupt accommodation creation and half-graben expansion, and some of them are related to erosion of the upper flexural margin due to block rotation
The stratigraphic framework proposed here (Figure 8) for the rift section of the Campos Basin comprises units that are representative of distinct events and based on specific conditions defined by controls

Summary

Introduction

The Campos Basin is one of the largest hydrocarbon-producing basins of the Brazilian margin [1], with substantial oil reserves first discovered in its shallower part during the1970s [2]. Exploration has focused on the deeper parts of the basin, reaching turbidite and carbonate deposits at the beginning of the 21st century [3]. The discovery of the pre-salt reservoirs [4] in 2006 shifted the exploration focus to deeper, larger accumulations. The Lagoa Feia Group, recording the rift and sag phases, has a central role on the Campos Basin’s petroleum system, comprising both the main source rock and reservoir formations (mainly rudstone accumulations, known as “coquinas”). A chronostratigraphic framework for the rift section based on sequence stratigraphic premises and a tectonostratigraphic framework for these deposits is still lacking [5,6]. Previous studies have only provided a lithostratigraphic partition [3,7,8], dividing the rift section into units defined mainly by lithological changes [9]

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