Study on flooding displacement based on the influence of fluid gravity differentiation

In order to visualize multiphase fluid seepage in porous reservoir media due to gravitational differentiation, a series of innovative experimental devices for individual or composite repulsion were fabricated to study and analyze the effects of repulsion mode, glass bead diameter, inclination angle, settling time, and crude oil viscosity on the gravitational differentiation of oil, gas, and water. The results show that compared with the actual production process in the reservoir, which requires a long time for the transport and aggregation of multiphase fluids under the action of gravity, this device can make the oil, gas, and water to produce gravity differentiation quickly and obviously. Compared with water flooding and gas flooding, combination flooding mainly extracted the emulsion of the oil–water mixture. The gravity differentiation effect of the oil–water mixture is much more significant than that of the oil–gas mixture. Static treatment of the emulsion is also required for reading numbers and producing a clear oil–water interface by oil–water gravity differentiation. Neither too low nor too high, the bank angle of a pipe filled with sand is conducive to the oil–water gravity differentiation. The effect of gravity differentiation within a specific time is directly proportional to the standing time. The change in the displacement mode can further amplify the three-phase gravity differentiation of oil, gas, and water. The greater the viscosity of crude oil, the harder the displacement. Finally, the microscopic experiment witnessed the oil–water gravity differentiation process of the extracted emulation. This experimental study identifies the main factors affecting the gravitational differentiation of multiphase fluids and methods to improve the gravitational differentiation rate of oil and water or oil and gas. The findings provide a theoretical basis for the rational and effective development of oil reservoirs.