Oil Displacement by the Magnetic Fluid Inside a Cylindrical Sand-Filled Sample: Experiments and Numerical Simulations.

Magnetic fluid is a new type of smart material, which holds implications for highly enhancing the oil displacement efficiency. In the present study, we perform a comprehensive investigation to probe the influence of a magnetic fluid on the displacement efficiency in porous media under the action of magnetic force. First, the displacement efficiency is measured by a self-developed setup, where factors such as the magnet thicknesses, the volume of the fluid injected, the fluid injection speed, and the porosity of the sample are surveyed as controllable variables. Moreover, the experimental results are well verified by the scaling laws according to the principle of dimensional balance. Next, a numerical simulation is performed to explore the detailed displacement process. First, the magnetic force generated by the ring magnet is calculated. Then, the function curves of the displacement efficiency with respect to the controlling variables are validated by the numerical simulation. In addition, the numerical simulation also demonstrates the volume phase distribution, the pressure field, and the velocity field of the mixed fluid during the displacement process. The simulation results are in excellent agreement with the experimental data. These findings are beneficial for us to better understand the oil displacement with the aid of external fields, which also provide inspiration for the areas of microfluidics, diffusion of pollutants, microsensors, etc.