Understanding immiscible-phase fluid displacement in non-homogeneous pore structures is crucial to enhance resource recovery in the secondary development of old petroleum reservoirs. Reducing residual oil resources requires quantifying the effects of pore characteristics on the development of preferential displacement paths in porous reservoirs, which can be used to predict the preferential path of water displacement during secondary oil recovery, and therefore, to design an effective plugging strategy. The non-homogeneity of pore structures of rocks makes it extremely difficult to directly observe the water-oil displacement in subsurface rock reservoirs and quantify the sensitivity of preferential paths to pore characteristics. As an effective alternative, numerical methods have been applied to explore the fluid displacement process in old petroleum reservoirs. In this study, a two-dimensional (2D) pore-scale multicomponent lattice Boltzmann model (LBM) was developed and used to study water-oil displacement in non-homogeneous pore structures that shared identical topological skeletons and porosities but had different pore size distributions and pore geometries. The effects of pore characteristics on the preferential displacement path of the water-oil imbibition were analyzed. The influence of the density ratios of incompressible fluids on the two-phase displacement was also compared. The comparison between the numerical results of different pore-scale models indicated that the variation of pore size distribution and pore geometry affects the development of water fingering and promotes different local displacement paths. The primary preferential displacement path remains unchanged in different pore structures, which can possibly be attributed to the invariant topological skeleton of the pore structures. The results demonstrate that the fluid density ratio dramatically influences the water-oil displacement behaviors and suggests coupling the real density ratio in an LBM simulation. This study provides a method to quantitatively evaluate the effects of pore characteristics on the water-oil two phase displacement in porous oil reservoirs and to help draft a strategy to enhance the resource recovery of old petroleum reservoirs.

了解非均质孔隙结构中的不混相流体驱替对于提高旧石油油藏的二次开发中的资源采收率至关重要。减少剩余石油资源需要量化孔隙特征对多孔油藏优先驱替路径发展的影响，这可用于预测二次采油过程中优先驱水路径，从而设计有效的堵漏策略。岩石孔隙结构的非均质性使得直接观察地下岩石储层中的水-油驱替和量化优先路径对孔隙特征的敏感性极为困难。作为有效的替代方法，数值方法已被用于探索老石油储层的驱油过程。在这项研究中，建立了二维（2D）孔尺度多组分晶格玻尔兹曼模型（LBM），并用于研究具有相同拓扑骨架和孔隙度但孔径分布不同的非均质孔结构中的水-油驱替。和孔的几何形状。分析了孔隙特征对水-油吸收优先位移路径的影响。还比较了不可压缩流体的密度比对两相位移的影响。不同孔隙尺度模型数值结果的比较表明，孔径分布和孔隙几何形状的变化会影响水指的发育，并促进不同的局部位移路径。主要的优先位移路径在不同的孔隙结构中保持不变，这可能归因于孔隙结构的不变拓扑骨架。结果表明，流体密度比极大地影响了水油驱替行为，并建议在LBM模拟中耦合实际密度比。这项研究提供了一种方法，以定量评估孔隙特征对多孔油藏中水油两相驱替的影响，并有助于起草提高老油藏资源采收率的策略。