基于VOF方法的水驱油藏孔隙尺度剩余油分布状态研究

Distribution of Remaining Oil in Water Flooding at Pore Scale:Volume of Fluid Method

准确认识多孔介质内水驱剩余油的微观赋存状态对于改善高含水油田水驱开发效果,提高水驱采收率具有重要意义。在对Volume of Fluid(VOF)方法验证的基础上,充分利用其追踪两相界面动态变化、再现微观渗流物理过程的优势,开展特高含水期砂岩油藏物性条件、驱替方式对剩余油微观赋存特征和采收率的影响研究。通过分析典型孔隙结构的微观渗流特征和剩余油受力情况,揭示不同类型微观剩余油的动用机制和规律:水湿条件下驱替速度的增大和驱替方向的改变会使得微观剩余油分布较为分散且采收率得到不同程度的提高;油湿及高黏度比条件下毛管阻力、黏滞力较大,剩余油多以簇状和多孔状聚集分布,采出程度相对较低。

Accurate understanding of the microscopic occurrence state of water flooding residual oil in porous media is of great significance for improving the development effect of water flooding and enhancing the recovery factor of water flooding in high water cut oil fields.Based on the verification of the Volume of Fluid(VOF)method,influence of physical property conditions and displacement modes on the microscopic occurrence characteristics and recovery factor of remaining oil in ultra-high water cut sandstone reservoir was studied by making full use of its advantages of tracking the dynamic change of two-phase interface and reproducing the physical process of microscopic seepage.By analyzing the microscopic seepage characteristics of typical pore structures and the stress of remaining oil,mechanism and law of different types of microscopic remaining oil are revealed:The increase of displacement velocity and the change of displacement direction make the distribution of microscopic remaining oil dispersed and the recovery efficiency is improved in different degrees under the condition of water and humidity;As the oil is wet and the viscosity ratio is high,the capillary resistance and viscosity are great,the remaining oil is mostly clustered and porous,and the recovery degree is relatively low.