基于相场方法的孔隙尺度油水两相流体流动模拟

基于真实岩心颗粒粒径分布，利用过程法构建疏松砂岩油藏的三维孔隙结构模型，利用相场方法建立两相流体流动数学模型并利用有限元方法进行求解，研究驱替速度、流体性质、润湿性对剩余油分布以及采出程度的影响.结果表明：驱替速度的增大和油水粘度比的减小会导致较大的毛管数，进而有利于采出程度的提高；就润湿性而言，水湿条件下毛管力是水驱油的动力，而在油湿条件下是阻力，因此水湿岩心采出程度更高.同时，从孔隙尺度对油水渗流机理及剩余油分布机理进行揭示，结果表明：由于多孔介质的复杂孔隙结构，流体在流经不同孔隙时呈现不同的流动特征，进而对油水两相流整体的压力分布、流速分布造成重要影响.

Pore-scale Oil-Water Two-phase Flow Simulation Based on Phase Field Method

Based on a typical particle size distribution of conventional sandstone, we establish a three-dimensional porous media of unconsolidated sandstone reservoir with process method. By using phase field method(PFM), a two-phase flow model is established on the basis of two-dimensional porous media model, which is solved with finite element method. Influences of displacement velocity, fluid properties and wettability on remaining oil distribution and recovery are discussed. It shows that displacement speed increase and inviscosity ratio decrease lead to a higher capillary number, thereby facilitating enhancing oil recovery. As for wettability, capillary force is the driving force for displacement under-water wet condition and it is a resistance under oil-wet condition,which results in a higher oil recovery in water-wet core.Meanwhile, this study reveals mechanism of two-phase flow and remaining oil distribution in pore scale. It can be seen that due to complex pore structure, fluid exhibits various characteristics as flowing through pores,which have an important impact on pressure distribution and fluid velocity distribution of oil-water two-phase flow.