Study on the Micro-Mechanism of Surfactant-Driven Oil Recovery and the Evolution of Residual Oil Distribution based on Microfluidics
Due to their minute throats and strong heterogeneity, tight reservoirs are prone to forming bypass channels during conventional water flooding, resulting in low recovery rates. To elucidate the microscopic oil displacement mechanism of surfactants, this study constructed a heterogeneous microfluidic model featuring typical throat characteristics. Visualization experiments were conducted to compare the performance of water flooding versus surfactant flooding. Results indicate: - Water flooding leaves residual oil predominantly in networked and columnar patterns, achieving a final recovery rate of approximately 43%; Surfactants, by reducing oil-water interfacial tension and modulating wettability, weakened capillary confinement. This transformed residual oil into columnar and isolated droplet forms, boosting recovery to approximately 65%. The treatment significantly enhanced mobilization of large and medium-pore residual oil but remained ineffective for small-pore network residual oil. This study provides experimental and theoretical support for optimizing chemical flooding in tight reservoirs.
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