Advanced Analytical Methods for Water Breakthrough Timing Forecasting in Fractured Bottom-Water Reservoirs

Abstract Bottom-water-drive buried hill oil reservoirs, characterized by natural fractures, are challenging for predicting water breakthrough timing. Common methods include time-intensive numerical simulation and simpler analytical approaches that overlook fracture characteristics. This study aims to enhance analytical prediction methods by incorporating fracture variability, reducing time costs without sacrificing accuracy. This study enhances three prevalent analytical methods for predicting water breakthrough timing in bottom-water oil reservoirs by incorporating natural fracture distribution characteristics. We calculate fracture permeability using an improved cubic law and apportion it vertically and horizontally based on fracture orientation and connectivity. Permeability values in both directions are derived from actual well data. These values are integrated into the water breakthrough model, and the timing is determined through integration and compared with real-data fits. The study also assesses the differences and applicability of various methods, establishing water breakthrough timing templates under different scenarios. The enhanced models for predicting water breakthrough in bottom-water oil reservoirs offer specific advantages in fractured settings. The improved Sobocinski-Cornelius (S-C) and no-barriers methods provide quick insights into water breakthrough timing across oil production rates and shut-off heights, enabling re-predictions based on well-specific shut-off heights. The improved composite flow method additionally delineates water cone morphologies at various bottom-water lift stages. These methods cater to reservoirs with varying degrees of heterogeneity and flow regimes, with the first two suitable for early development and the latter for complex geological conditions. Validated against actual data, the methods exhibit low errors in predicting water breakthrough timing in specific conditions and have been utilized to develop prediction charts considering various factors. This study improves water breakthrough prediction in fractured bottom-water oil reservoirs by quantifying fracture variations, avoiding the high time costs and low accuracy of traditional modeling. It offers swift predictions and aids in devising field development strategies.