Method for Quantitative Characterization of Advantage Channel Parameters in Water Flooding of Fractured-Cave Reservoirs

Abstract Fault-controlled fracture-cavity reservoirs are significantly influenced by strong fault activity and dissolution processes. Injected water tends to advance rapidly along fault zones, resulting in a limited waterflood sweep area and ineffective displacement, highlighting the urgent need for dominant channel plugging. To enhance the success rate of water control measures, accurately characterizing the inter-well water channeling parameters is crucial. The stepwise water-cut curve is the most common type observed in fault-controlled fracture-cavity reservoirs, as the breakthrough times of injected water vary among multiple oil production channels, and the presence of karst cavities prolongs water advancement. To quantitatively characterize dominant flow channels in such reservoirs, this study treats the cavern section as an additional fracture flow pathway and derives parameter equations for fracture aperture, fracture count, and equivalent seepage length of fracture-cavity systems. These equations are then applied to an actual reservoir, with the fitting results aligning well with actual production data. The proposed method for determining parameter equations provides significant guidance for the effective plugging design of fault-controlled fracture-cavity reservoirs.