Hydraulic pulsation for enhanced oil recovery in high-water-cut sandstone reservoirs

In high water-cut sandstone reservoirs, improving microscopic sweep efficiency is critical for enhancing oil recovery. Hydraulic pulsation generates pressure waves that induce pore dilation between injection and production wells, disrupting interfacial equilibrium at the pore scale. This study systematically optimizes key operational parameters—amplitude, frequency, and timing—to increase displacement efficiency. Core-flooding experiments establish quantitative relationships between these parameters and incremental oil recovery. The results identify an optimal frequency of 1.0 Hz for effective wave energy superposition and a critical amplitude threshold (approximately 2.0 ml·min−1 at laboratory scale), beyond which incremental recovery plateaus due to exacerbated channeling. This critical amplitude correlates with a capillary number criterion (Ca > 10−6), while the optimal frequency corresponds to a Womersley number of approximately 0.32. A simplified fluid–solid coupling model is developed to predict parameter effects. Field application under scaled conditions (0.025 Hz, 3 MPa amplitude) increased well-group oil production by 45.5%, validating the methodology. This work provides a theoretical and practical framework for optimizing hydraulic pulsation to enhance oil recovery in mature sandstone reservoirs.