Multiphase Salt Tectonics in the Campos Basin, Offshore SE Brazil: Implications for Petroleum Exploration

Authors: Francyne Bochi do Amarante, Universidade Federal do Rio Grande do Sul - Imperial College London (presenter); Christopher Aiden-Lee Jackson, Imperial College London; Leonardo Muniz Pichel, University of Bergen; Claiton Marlon dos Santos Scherer, Juliano Kuchle, Universidade Federal do Rio Grande do Sul

Salt-bearing passive margin basins offshore SE Brazil have been and remain attractive for hydrocarbon exploration and production. In the Campos Basin, major reservoir types include post-salt turbidites, which are located in structural traps related to thin-skinned faulting above salt pillows and rollers. Classic models of gravity-driven salt tectonics commonly depict kinematically linked zones of deformation, characterised by updip extension and downdip contraction, separated by a weakly deformed zone associated with downdip translation above a relatively smooth base-salt surface. We use 2D and 3D seismic reflection and borehole data from the south-central Campos Basin to show that this does not adequately capture the styles of salt-detached gravity-driven deformation above relict, rift-related relief. We show that base-salt ramps can create local stress fields and complex structures in the translational zone, with these overprinting the regional, margin-scale patterns of deformation. These structures include c. 20-30 km wide ramp-syncline basins and contractional salt anticlines that were later extended and faulted. This multiphase deformation relates to changes in the volume and velocity of the salt crossing seaward-dipping base-salt ramps, with the most complex structures forming in response to translation of salt and overburden across two ramps. We show that salt-cored anticlines in the translational domain can create large traps that may contain post-salt turbidites. Later extensional faulting of these anticlines can provide conduits for oil migration from the underlying source rocks, as well as define reservoir compartments.

Bio:

Francyne Bochi do Amarante, Universidade Federal do Rio Grande do Sul, Imperial College London

Francyne earned a BSc in Geology at Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil; a MSc in Geosciences with focus on Stratigraphy and Sedimentology at UFRGS; and currently is a PhD Candidate in Geosciences with focus on Basin Analysis at UFRGS; she also is a Visiting Researcher at Imperial College London during her PhD researching salt tectonics.

Her professional experience includes research projects funded by Shell and Petrobras at UFRGS.