Geomechanical Innovations and Multidisciplinary Approaches in the Búzios Field

The Búzios Field is a pre-salt carbonate reservoir located in the Santos Basin, approximately 180 km off the coast of Rio de Janeiro, Brazil, spanning 852 km2 with an average net pay of 400 meters. Positioned beneath 1000 meters of post-salt sediments and 2000 meters of salt, Búzios is a critical asset for Petrobras, projected to achieve a daily processing capacity exceeding 2 million barrels of equivalent oil by 2028. To address its complex geomechanical challenges, Petrobras employs a multidisciplinary team comprising geophysicists, geologists, petrophysicists, and engineers, employing the in-house stress analysis software to develop a geomechanical model with over 62 million finite elements that extends beyond the reservoir into surrounding formations. High-quality geomechanical data for the post-salt interval is acquired through investigative wells drilled with dual rigs, enhancing predictions of geohazards and optimizing well designs, while achieving significant cost savings (approximately 1.8% compared to conventional operations). A one-way coupling methodology evaluates the effects of reservoir depletion on compaction, subsidence, and wellbore stability, while the Ensemble Smoother-Multiple Data Assimilation (ES-MDA) technique strengthens model robustness against uncertainties. Furthermore, a two-way coupling approach is tested on synthetic models to assess geomechanical impacts on reservoir permeability. The representation of karst features, including their compressibility and elastic properties, is vital for ensuring the reliability of the geomechanical grid and improving simulations of rock behavior under stress. Alternatively, the use of pseudo-coupling tables in reservoir simulation models shows to be a simplified and efficient way to dynamically incorporate karst behavior into flow simulations. The innovation of this work lies in integrating advanced methodologies and multidisciplinary collaboration to address the geomechanical challenges, ensuring the safe and efficient exploitation of the world's largest carbonate offshore oil field.