When the Water Goes Marching in: Integrating Geosciences with Reservoir Management to Handle Water Breakthrough in a Mature, Highly Fractured, Carbonate Reservoir Field

Approximately 70% of the world's hydrocarbon reserves are contained in naturally fractured carbonate reservoirs. Despite their exceptional deliverability and favorable reservoir characteristics, managing these reservoir types poses distinct challenges, particularly when dealing with fluids of varying mobilities. Addressing these complexities necessitates: 1) an agile geoscience workflow capable of rapidly integrating and interpreting subsurface data, 2) adaptability in decision-making and field development strategies, including criteria for identifying drillable targets and optimizing well designs, and 3) comprehensive analysis of static and dynamic reservoir data to guide management and operational adjustments effectively. A fictional, representative highly fractured, heterogeneous Middle East carbonate field was designed to characterize and model water pathways. The work focuses on the management of water during significant water breakthrough in a mature field, aiming to integrate geosciences and reservoir engineering to trace probable fluid flow pathways. Three critical datasets were identified: fracture characteristics, continuous bottomhole pressure logs for the wells, and seismic attributes to detail inter-well reservoir properties. A fracture catalogue was developed to assess which fractures likely contribute to fluid transport. Water presence and its dynamic behavior was closely analyzed and followed up from existing well pressure and production data. Seismic attributes reveal reservoir discontinuities beyond well drainage volumes. Hypothesized flow paths, based on these tools, were validated against observed well performance. As a result of the applied methodology, the most probable pathways for both oil and water movement are determined, leveraging dynamic data that can be continuously updated as new field information becomes available. This approach is valuable for identifying active fracture networks, critical for production optimization and the selection of new drillable targets. It supports decisions such as adjusting planned well trajectories across under-drained areas, managing production on existing wells, or modifying open producing intervals in selective completions. Furthermore, the methodology enables the hierarchization of fracture networks as fluid paths under current conditions, providing insights to guide infill drilling campaigns and improve the efficiency of the field production at different stages of its evolution. This approach surpasses conventional reservoir analysis methods in both speed and reliability by integrating an extensive static and dynamic dataset with multidisciplinary expertise. Each map realization encourages collaborative discussions, leveraging specialized knowledge across geoscience, reservoir engineering, and production disciplines. The workflow is completed in significantly less time than traditional reservoir modelling, making it more agile and efficient. Additionally, it serves as a team-building process, promoting dialogue among subsurface, production, and field teams. Being heavily data-driven, this methodology reduces bias compared to conventional reservoir modelling, ensuring more objective insights and facilitating informed decision-making.