Tectono-Stratigraphic Modeling of the Wildcat Prospect (Gato do Mato), Santos Basin, Brazil Focusing on Presalt Carbonate Reservoirs

Abstract

The Santos Basin is the largest Brazilian offshore basin and is currently the main hydrocarbon producer in the country, comprising an area of approximately 350,000 km2 . Given the importance of understanding and analyzing its carbonate reservoirs (Itapema and Barra Velha formations), a tectono-stratigraphic model of the Wildcat Prospect was created. This area is in the Outer High of the Santos Basin, main region of the presalt carbonate reservoirs in the Santos Basin. The 3D model is focused on the presalt reservoir and the understanding of the main tectonic structures in this area and their relationships that conditioned the carbonate successions deposition. Four steps were followed to analyze the depositional and structural framework and build the tectono-stratigraphic model: (i) generation and analysis of seismic attributes to identify and characterize seismic terminations (erosional truncation, toplap, and onlap), seismic facies (debris, build-ups, platform carbonates, and bottom lake), and assist in the tectono-stratigraphic analysis; (ii) seismic interpretation of horizons and faults, which were used as input for the modeling as surfaces and fault planes, creating compartmentalized blocks; (iii) construction of the stratigraphic column to classify the succession of tectonic and sedimentary events; and (iv) the construction of the model. This study helps to understand the depositional and structural evolution of the presalt and provides a three-dimensional understanding of the influence of faults on the reservoir geometry. Faults influenced the eroded zone observed in the Upper Barra Velha Formation, since this erosion occurs mainly at the edges of the large-throw faults. The build-up seismic facies, the main reservoirs in the study area, have a trend NW-SE to N-S following the large-throw faults.