Ultra-Frontier of Santos Basin - Positive Perspective for the Discovery of Pre-Salt Giant Fields Beyond the EEZ

Authors: Pedro Victor Zalán, ZAG Consulting in Petroleum Exploration (presenter); Eric Newman, TGS

The acquisition and interpretation of 3 long offset 2D seismic surveys in the southern part of the Campos Basin and in the whole of Santos Basin allowed the recognition of the southward extension of the External High beyond the EEZ. The External High is the most important feature of both basins because, being a >600 km continuous feature, it plays the role of main focusing high for both surrounding Internal and External Kitchens. It controls the location of the majority of the Pre-Salt and Post-Salt producing fields. Upon this newly mapped extension very large structural highs (> 1000 km2 of 4-way closure) were identified at the base of the salt beyond the EEZ. Recently shot 3D surveys confirmed the existence of such huge structures and allowed an unprecedented view of their complex deformation. For the first time, a glimpse into the highly complex deformation history of the last lapses of continental separation can be attained. Very strong strike-slip related positive and negative flower structures of great relief can be observed. A holistic view of the intensively broken, faulted, uplifted and twisted outer continental crust is displayed in accompanying figures. Amidst this intense deformation, very large structural closures occur, completely sealed by salt. Typical Pre-Salt reservoir seismic facies can be observed in the structures. Planar, parallel reflectors indicative of the carbonate ramp model of microbialite deposition and travertine cones/buildups related to hydrodynamically active syn-rift faults can be seen right beneath the base of salt. Another important feature revealed by the 3D surveys is the presence of thick, deep-seated grabens filled by sedimentary strata adjacent to such highs. Their existence is important as they may contain the so-needed source rocks of the External Kitchen.

Bio:

Pedro Victor Zalán, ZAG Consulting in Petroleum Exploration

Pedro holds a MSc and a PhD from the Colorado School of Mines. With 42 years of experience in the industry, he is independent consultant in petroleum exploration at ZAG Consulting in Petroleum Exploration, in Rio de Janeiro. He worked for 34 years in Petrobras.

Pedro is a member of AAPG and ABGP.