A pore-scale numerical study on the two-phase flow characteristics in fractured porous media.

Understanding the fracture effect on the two-phase displacement process in porous media is potential for fulfilling the efficient development of geo-energy resources. In this paper, a pore-scale numerical study is carried out based on digital rock physics (DRP) and computational fluid dynamics (CFD) methodology. Advanced image processing technology is employed to incorporate the fracture structure of different aperture sizes in the rock pore matrix, and the sophisticated CFD approach is employed to simulate the single-phase and two-phase displacement flow characteristics in fractured porous media. In single flow cases, it is found that larger fractures always lead to higher water flow rates, therefore resulting in higher rock permeability. For the specific water flooding oil two-phase flow process under a pressure drop of 500 Pa, the presence of fractures could help achieve a steady flooding process that cannot be fulfilled in the homogeneous core due to the interfacial tension (IFT) blockage effect. Under a higher pressure drop of 1000 Pa, the relationship between the ultimate oil displacement rate and the aperture size is not uniform. The optimal oil recovery rate of 82.4% is achieved at the model with the intermediate aperture size. [Display omitted] [ABSTRACT FROM AUTHOR]