Modelagem de reservatórios fraturados e carstificados usando afloramento análogo de alta resolução e análise de sensibilidade de cenários simulados

Abstract

This study presents a multidisciplinary workflow to improve understanding of fractured and karstified carbonate reservoirs. The study seeks to uncover geological mechanisms behind fracturing and karstification by integrating analog outcrop fieldwork with regional correlation. This knowledge is crucial for constructing more accurate geological models and improving the management of these complex reservoirs. We use the Jandaíra Formation in the Potiguar Basin, Brazil, as an analog for fractured and karstified carbonate reservoirs. Our results focus on the Furna Feia cave, characterized by dissolution dome structures and NW-SE-trending conduits. Regional stratigraphic analysis identified lithofacies patterns and correlated system tract cycles to map more karstified layers, relating the cave formation to the SB-2 unconformity. Structural analysis revealed that rift faults, caves, and fractures are oriented NW-SE and NE-SW. The regional 3D geological model, covering an area of 30x14 km with 179 layers, integrates data from two wells, interpreted surfaces, fracture models (DFN), and karst features, revealing intensely dissolved layers between the SB-1 and SB-2 unconformities. Building upon this, we propose a new approach to karst modeling that combines conduits and karstified fractures following a comprehensive conceptual model. Four models were simulated to evaluate the water and oil production history, similar to analog carbonate reservoirs. We concluded that including karst and fractures improves performance, increasing production, but it affects some wells due to premature water breakthroughs. Therefore, effective management and optimized planning for wells are essential for reservoirs containing karst and fractures. This multidisciplinary workflow, from creating geological models to reservoir simulation, assesses different scenarios, providing insights into potential outcomes and associated risks that would influence decision-making in production development projects.