The stability of the waterfront in a heterogeneous porous medium and in the absence of gravity effects is controlled by capillary and viscous forces. Under oil-wet conditions, waterflood is a drainage process and the displacement front advances in zones with larger pores where capillary forces are lower, and the rate of displacement is higher compared to zones with smaller pores. Hence, in a waterflood process, a transition zone is formed where the water saturation gradually decreases from a trailing front to the leading end of advanced water fingers. In a heterogeneous medium, oil–water capillary pressure fluctuates due to variations of pore sizes in flooding paths. The difference in the capillary pressures between leading and trailing zones can help with the stability of the waterfront when the capillary pressure in frontal zones is increased by displacing oil through smaller pores. However, this mechanism creates a limited pressure gradient in the oil phase, so the waterfront instabilities continue to grow, especially at the adverse mobility ratio and high displacement rates. In this study, different oil samples with low, medium and high viscosities are displaced by water in an oil-wet medium containing pore-level heterogeneities. Herein, the effect of flow swing, which is introduced to the direction of oil–water displacement, on waterflood performance is investigated. Under flow-swing conditions, we reverse the fluid flow direction periodically; however, the overall volume of injected water is maintained the same for all scenarios by adjusting the periods of the forward and reverse steps. The flow reversal promotes the refill of water paths with oil, hence attenuating the advanced fingers. Consequently, the sweep efficiency of waterflood is improved and higher oil sweep efficiency is obtained at the time of breakthrough. The flow-swing mechanism is more effective when oscillations of capillary pressure result in a faster flow of oil between trailing and leading zones, thus decreasing the waterfront instabilities. The new process can be optimized and utilized at larger scales for improving the sweep efficiency of flooding operations.

在毛细作用力和粘性作用力的作用下，滨水区在非均质多孔介质中的稳定性以及在没有重力作用的情况下。在油湿条件下，注水是一个排水过程，在毛细作用力较低的较大孔隙的区域中，驱替锋前进，而较孔隙较小的区域，驱替速率较高。因此，在注水过程中，形成过渡带，在该过渡带中，水饱和度从先进的水指的尾端到前端逐渐降低。在非均质介质中，由于注水路径中孔径的变化，油水毛细管压力会波动。当通过较小孔中的油置换来增加前部区域中的毛细管压力时，前部区域和后部区域之间的毛细管压力差异可有助于提高滨水区的稳定性。但是，这种机理在油相中产生了有限的压力梯度，因此，海旁的不稳定性持续增长，尤其是在不利的流动率和高驱替速率下。在这项研究中，低，中和高粘度的不同油样在含有孔隙水平非均质性的油湿介质中被水置换。在此，研究了在油水驱替方向上引入的水流摆动对注水性能的影响。在摆流条件下，我们会定期反转流体的流动方向。然而，通过调整前进和后退步骤的周期，在所有情况下总注水量保持不变。逆流促进了油中水的补充，从而削弱了前进的指状物。因此，提高了注水效率，并且在突破时获得了更高的扫油效率。当毛细管压力的波动导致尾部和前部区域之间的油流更快时，这种流动摆动机制会更加有效，从而减少了江边的不稳定性。可以优化和大规模利用新工艺，以提高驱油作业的清扫效率。因此削弱了高级手指。因此，提高了注水效率，并且在突破时获得了更高的扫油效率。当毛细管压力的波动导致尾部和前部区域之间的油流更快时，这种流动摆动机制会更加有效，从而减少了江边的不稳定性。可以优化和大规模利用新工艺，以提高驱油作业的清扫效率。因此削弱了高级手指。因此，提高了注水效率，并且在突破时获得了更高的扫油效率。当毛细管压力的波动导致尾部和前部区域之间的油流更快时，这种流动摆动机制会更加有效，从而减少了江边的不稳定性。可以优化和大规模利用新工艺，以提高驱油作业的清扫效率。