부산대학교 도서관

Oil recovery by water injection is a common method in petroleum industry. Although the macroscopic point of view monitoring the sweep efficiency is the usual approach, several phenomena could studied more effectively at the microscale. Capillary and viscous forces, together with geometry arrange of the medium, are responsible by the mobilization and trapping the oil. In numerical simulation, the correct choice of numerical algorithms is also a relevant question. With the goal of studying the dynamic of the microscopic process and the influence of discretization algorithms, boundary condition, and time step, in this work it is used the software Ansys Fluent, with volume of fluid technique, to simulate the two-phase, transient, Newtonian and laminar flow. The 2D Cartesian domain is a system with circular constrictions representing a simplified porous media initially fully filled with oil. It is used the periodicity boundary condition and the choice of the time step is realized comparing three options. The oil removal is a complex process. Oil films are retained around the grains walls and recirculation acts trapping the oil. This volume is slowly removed result of the continuous water injection. Two stages are well identified in this process. One with linear decrease whit time, which is in according with our analytical prediction until the water breakthrough, followed by the stabilization where the continue water injection has no effect in the oil displacement. As a consequence the oil recovery is not complete, a fraction of it will remains in the porous medium. In addition, it is possible to identify the numerical algorithms for this microscale immiscible liquid/liquid displacement problem, which presents the more coherent physical results.