Microscale multiphase oil displacement simulation and experimental study based on microfluidics approach

Oil exists in the underground formation in the form of tiny droplets trapped inside the pores. Pores have a diversity of shapes, uneven pore distribution, and unstable fluid status in the reservoir, and all these complexities have brought great challenges to crude oil displacement and recovery in the oil industry. The crude oil displacement process and mechanism at the micro-scale or even nano-scale have been a hot research spot in the recent decade. With the rapid development of microfluidics techniques in biological and medical fields with the unique advantage of precise liquid handling, researchers have started to use microfluidics for direct visual observation and manipulation of tertiary oil recovery. And microfluidics method helps to deeply explore the underly complex displacement mechanism of crude oil at the micro or nano-scale. This study used the simulation and experimental method for the study of foam flooding on oil recovery with the help of microfluidics technique. This study first built the mathematical model and simulated the foam flow in porous media with finite element analysis, and then prepared a PDMS microfluidic chip with the soft lithography method. In the experimental process, the foam flooding and displacement process can be visually observed with the transparent microfluidic chips, and the detailed foam flooding process was analyzed and compared with the simulation result. Also, in the experimental process, we confirmed that compared with the displacement process of crude oil with saline, foam can effectively improve the oil displacement efficiency. This study helps to reveal the mechanism of micro-scale foam flooding and displacement process in the reservoir to improve the oil recovery efficiency in the oil production process.