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Título

Main Challenges and Mitigation Strategies for the Carbonate Reservoirs in Libra Block, Santos Basin: Geology and Petrophysics Portfolios in Libra Applied Technology

Texto do resumo

The Libra Block is an offshore area in the ultra-deep waters of the Santos Basin. A portion of this block has become the super-giant Mero Field, which is currently the third largest field in Brazil in terms of oil in place volume. It is operated
by Petrobras in partnership with Shell Brasil, TotalEnergies, CNPC, CNOOC, and Pré-Sal Petróleo SA. The exploration and development of this area pose unique challenges due to the presence of complex carbonate reservoir rocks and associated igneous rocks. To address these challenges, the Libra Applied Technology (AT) team has conducted extensive studies. The objective of this work is to present an overview of the four main different topics investigated, along with the methods and results obtained: 1）Igneous rocks studies - Libra block has experienced at least two distinct magmatic events: the Aptian and the Santonian-Campanian. Research performed by the Libra Team revealed that the Aptian magmatism was characterized by eruptive rocks, featuring multiple eruptions and intrusions. In addition, the emplacement pattern of Santonian-Campanian magmatism is complex, with intrusions cutting across the entire stratigraphic framework and massive sills near the top of the Barra Velha Formation reservoir and the salt layer’s boundary. The Libra Team has also observed analogous outcrops in the Isles of Skye and Mull in Scotland. Additionally, joint cooperation with UNESP Rio Claro involved studying two outcrops: the Irati Formation in Paraná Basin and the Mendoza area in Neuquén Basin, Argentina. The results of these studies have contributed to identifying the main controls, geometry of igneous bodies, and their corresponding impacts on the petroleum system, reservoir heterogeneity and carbonate petrophysical properties. 2）Coquinas studies: Cooperation with IPH/UFRGS has investigated coquinas through physical modeling and modern outcrops. The coquinas’ distinct clastic sedimentary features prompted an investigation into dynamic formation processes and the geometry of analogous geometries. The results have provided insights into the textural properties, facies distribution, and reservoir characteristics under
shallow water environments. This knowledge is crucial for understanding the Itapema Formation, which is composed mainly by coquinas facies. 3) Karst: Evidence suggests that carbonate reservoir in the Mero Field has undergone
dissolution throughout geological history. Research on karst has been initiated in cooperation with PUC-Rio to characterize its development and distribution patterns at different scales. This research aims to reduce the uncertainty regarding preferred pathways, which can have implications for reservoir management. 4) Stratigraphy: This topic involves the construction of a higher-resolution stratigraphic framework for the Libra Block based on magnetostratigraphy and cyclostratigraphy. Once the method is validated, a comprehensive paleomagnetic study will be conducted to further refine the temporal scale of basin evolution history. In conclusion, these research efforts have improved the geological characterization and understanding of controls within the Libra Block/Mero Field. Furthermore, they have the potential to greatly reduce uncertainties in geological models and increase the recovery factor of oil resources.

Palavras Chave

Santos Basin; Libra block; Mero Field; Pre-salt carbonate reservoirs